US2620624A - wislicenus - Google Patents

Description

1952 G. F. WIS'LICENUS 2 JET PROPULSION UNIT WITH THRUST INCREASER wig-11 Sept 27, 1946' 5 Sheets-Sheet 1 Dec. 9, 1952 G. F. WISLICENUS JET PROPULSION UNIT WITH THRUST-INCREASER- Filed Sept. 27, 1946 5 Sheets-Sheet 3 Dec. 9, 1952 G. F. WISLICENUS JET PROPULSION UNIT WITH THRUST INCREASER 5 Sheets-Sheet 4 Filed Sept. 27, 1946 IIYVEIYTOR. G 96 Zflwlwemw,

G. F. WISLICENUS JET PROPULSION UNIT WITH THRUST INCREASER Dec. 9, 1952 5 Sheets-Sheet 5 Filed Sept. 27, 1946 Patented Dec. 9, 1952 UNITED STATES ATENT OFFICE JET PROPULSION UNIT WITH THRUST INCREASER Application September 27, 1946, Serial No. 699,945

(Cl. Gil-35.6)

23 Claims.

The invention relates to a jet propulsion unit of the type utilized for propelling a vehicle such as an airplane.

The general object of the invention is to provide a novel jet propulsion unit having an increased propulsive efficiency without loss of thermodynamic emciency of the unit.

Another general object is to provide novel means for increasing the thrust of a jet propulsion unit of a given power by increasing the mass rate of flow of the jet.

A further important object is to provide a jet propulsion unit having a propulsive jet of relatively low average velocity and temperature in normal operation in order to maintain discharge losses at a minimum.

Stated in other words, it is an object to provide a jet propulsion unit having maximum efficiency at relatively low power, in contrast with prior units where efficiency is poor at reduced speeds.

Still another object is to provide a jet propulsion unit having a high overall eiiiciency at normal operation with a large overload capacity.

Another object, related to the foregoing, is to provide a jet propulsion unit having increased fuel economy at moderate loads and low vehicle speeds but with the capacity to meet exceptionally high overload requirements.

A stil further object is to provide a jet propulsion unit which, because of its high eii'iciency at relatively small loads and speeds and its capacity to meet high overload requirements, is particularly adapted to airplanes for military purposes.

A further object, somewhat more specific, is to provide a jet propulsion unit having means for increasing the thrust of the jet produced thereby and constructed in such a manner as to provide highly favorable conditions for supplementary combustion to meet overload requirements.

Another object is to provide a jet propulsion unit comprising structure for providing a powerproducing gas stream and structure operated by such stream for increasing the mass rate of flow thereof, both of said structures including rotary means which are independent of each other so they may operate at the optimum speeds for performing their respective functions.

it is also an object to provide a jet propulsion unit provided with means for increasing the thrust of the jet, with all important stress carrying structure adequately cooled by air.

Another object is to provide a jet propulsion unit having means for increasing the thrust of the jet, in which surfaces of substantially all essential portions subjected to heat are amply pro- 2 tected by being cooled on their oppsite faces or sides.

Still another object is to provide a jet propulsion unit which is air cooled as set forth in the preceding objects and in which cooling air may freely be used without loss other than a slight frictional loss, since such cooling air, after performing its function, is added to the propelling stream.

A further object is to provide a jet propulsion unit provided with means to increase the thrust of the jet by adding a mass of air thereto, said means including a passage for the air in which the flow is facilitated by removing a boundary layer of air within the passage, the air so removed being utilized for cooling the structure.

A still further object is to provide a jet'propulsion unit for an airplane, provided with means. to increase the thrust of the jet by adding a mass of air thereto, such air being taken from various points on the exterior surfaces of the airplane to.

provide for boundary layer control.

Another object is to provide a novel method of attaining the foregoing objects.

Other objects and advantages will become apparent from the following description taken in connection with the accompanying drawings, in which:

Figure 1 is a side elevational view of a jet propulsion unit embodying the features of the inven-.

tion.

Fig. 2 is a longitudinal sectional view, with certain internal parts shown in elevation, of the unit illustrated in Fig. 1.

Fig. 3 is a fragmentary view, in section, of a portion of Fig. 2 on a somewhat larger scale.

Fig. 4 is a fragmentary view, on an enlarged scale, showing a portion of Fig. 3.

Fig. 5 is a fragmentary transverse sectional view taken on the line 55 of Fig. 3.

Fig. 6 is a, fragmentary transverse sectional view taken on the line B-6 of Fig. 3.

Fig. '7 is an enlarged fragmentary view of a portion of Fig. 3.

Fig. 3 is an enlarged sectional view taken on the line 88 of Fig. 3.

Fig. 9 is an enlarged sectional view taken on the line 99 of Fig. 3.

Fig. 10 is an enlarged sectional view taken on the line |o- |e of Fig. 3.

Fig. 11 is an enlarged sectional view taken on the line Hii of Fig. 3.

Fig. 12 is a diagrammatic View of an airplane provided with a jet propulsion unit of the character herein disclosed.

Fig. 13 is a sectional view taken on the line I3--l3 of Fig. 12.

The propulsive efficiency and, consequently, the thrust of a jet propulsion unit can be improved by increasing the mass rate of flow of the jet for given operating conditions. If, instead of the conventional single-temperature jet turbine, a two-temperature jet propulsion unit i provided, it is possible to obtain this increase in mass flow without a reduction in turbine temperature, which reduction would result in a marked drop of the thermodynamic cycle efficiency.

Such increased thrust may be obtained by a propulsive jet of relatively low average discharge velocity and temperature in order to reduce discharge losses at normal operation. This permits normal operation of the jet propulsion unit with high overall efficiency where power requirements are low, in contrast to prior jet units where the efficiency is poor at reduced engine and vehicle speeds. Furthermore, by supplementary c-ombustion, the unit may be made capable of meeting large overload requirements, thereby rendering it particularly useful in airplanes for military purposes.

A further advantage is to be found in a jet propulsion unit of this character if the air which is utilized to increase the mass rate of flow of the jet is taken from a low velocity region of the airplane, that is, from the boundary layer of some external portion of the plane. The jet propulsion unit herein disclosed thus not only provides for increased thrust of the jet itself, but also lends itself to improvement in operating conditions of the airplane as a whole.

A jet propulsion unit embodying the features of the invention may be said to comprise two major portions, namely, a unit for providing a primary power-producing gas stream, and a unit for increasing the thrust which such gas stream would normally produce by conventional means. The unit for providing a power-producing gas stream may be of any desired form but preferably is of the character shown in copending application Serial No. 649,871, filed February 25, 1946, in which Robert M. Williams and Curtis N. Lawter were co-inventors. The unit shown in said application may be characterized generall as comprising a single-stage mixed flow compressor, a diffuser, an annular combustion chamber and a compressor-driving turbine driven by the power stream produced in said unit.

The thrust increaser unit, as herein disclosed and described in general terms, comprises a passage or intermediate zone to receive the power stream from the aforementioned unit. Paralleling such power stream passage is a zone for an augmenting stream, which in the present instance is air. Preferably an intake or passage is provided through which the air is caused to flow and to be mixed with the power stream to increase the mass rate of flow thereof and thus increase the thrust of the thrust stream or jet. 'Io efiect such air flow, driving means comprising a turbine is provided which has blades mounted within the power stream passage so as to be driven by the power stream before the tem perature thereof is reduced by being mixed with the cold air. The turbine is adapted to drive a fan extending into the air stream passage to produce the flow of air therein and feed or force it under pressure approximately equal to that of the power stream into the mixing zone to mix with the power stream after discharge of the latter from the turbine. The static pressure of the zone where the mixing occurs is obviously greater than the static pressure of the final jet. The turbine, under certain design conditions, may be shown as a two-stage reaction type, while the fan is shown as a single-stage axial flow type. In the present structure, the blades of the second stage of the turbine are extended to provide portions within the air flow passage constituting the fan. In order to provide the optimum conditions for operation of such turbine, the velocity of the power stream discharged from the primary unit is, in the present instance, reduced. To this end, the turbine .in the primary or compressor-turbine unit is changed from a single-stage type, as shown in the aforementioned copending application, to a two-stage type.

The two turbines are preferably independently mounted so that each may operate at the optimum speed to perform its own function. Furthermore, the two turbines preferably rotate in opposite directions so as to reduce the external gyroscopic moment of the propulsion unit as a whole.

The structure providing the power stream passage and the air flow passage preferably com prises a circular housing surrounded by an inner circular casing to provide the power stream passage, and also by an outer circular casing cooperating with the inner casing to provide the air flow passage, the forward end of such passage being open to receive air from the exterior of the unit. The two passages open at their rear ends into a discharge nozzle which provides a mixing zone and a rearwardly extending portion providing a discharge zone for discharge of the jet or thrust stream. The second stage of the turbine is mounted at the rear end of theinner casing and may be provided with a shroud carried by the blades constituting a short extension or continuation of the inner casing to maintain separation of the two streams and thus permit the two portions of the blades to properly perform their respective functions. The rotating blades of both stages of the turbine are also provided with inner shrouds constituting in effect portions of the internal housing, and bafiles are provided to prevent the heat of the power stream from penetrating materially into the interior of the housing.

As heretofore mentioned, the jet propulsion unit herein disclosed is adapted to meet large overload requirements by having provision for secondary or supplementary combustion. To this end, fuel may be introduced at one or more points in the path of. the power stream to increase the energy thereof. Thus, fuel may be added at a point between the primary unit and the first stage of the two-stage turbine of the thrust increaser unit. Fuel may also be introduced at points between the two stages of the last-mentioned turbine as well as in the mixing zone. Thus, large overload requirements may readily be met by adding fuel at one or more of these points.

The rotor of the turbine is mounted within the housing in bearings provided by supporting struc ture carried by the housing and inner and outer casings. The independence of the turbine of the thrust increaser unit is thereby obtained since no connection between the rotor of this turbine need be made with the turbine of the power-producing unit. The support for these bearings is preferably in the form of struts extending through hollow guide vanes traversing the passages of the structure.

The parts of the thrust increaser unit are adapted to be cooled preferably by air, and free use'ofsuch air is permitted because the air, after serving its cooling function, is discharged into the propelling stream of the unit and does not constitute a loss beyond the unavoidable friction loss in the cooling passages. The intake for the cooling air is preferably in the form of an annular opening within the intake of the air passage and is located in such manner as to eliminate separation in the air passage, the elimination being provided for by withdrawal of a part of the local boundary layer within the passage.

The cooling air is carried to the interior of the housing through hollow guide vanes traversing thepower stream passage. The support structure for the front bearing of the rotor is in the form of a spider, while the rotor itself is hollow and is provided with slots adjacent its front end andblades causing the air to be drawn into the interior of the rotor from the hollow guide vanes between the arms of the spider and through such slots." Part of the cooling air thus introduced into the interior of the rotor is drawn forwardly through the front bearing to maintain it in a cooled condition. Other portions of the air fiow rearwardly and are permitted to circulate radially outward through openings in the rotor to cool the root portions of the blades. The blades which provide the second stage of the turbine and constitute the fan are preferably hollow so that a further part of the cooling air is drawn outwardly therethrough by the rotation of these blades and is discharged at their outer extremities into the air stream flowing through the air passage. The cooling air is also caused to flow through the rear bearing support for the rotor and thence into an extension of the housing centrally located within the discharge nozzle so that the discharged air is thereby added to the propelling stream.

By the foregoing structure for handling cooling air, substantially all important parts: of the.

structure which are exposed to hot gases on one side are-cooled on their opposite side by the cooling air. All suchstructures as are subjected to theheat are guided by radial pins and bushings in order topermit expansion without transmitting undue stress to thecooled structure of the unit.

The intake of the air passage may be so connected and constructed as to provide for boundary layer control of the airplane as a whole, thus increasing the overall efficiency. To this end, the air intake opening may be connected to boundary layer control slots in the wings of the plane or to openings in the fuselage.

As heretofore mentioned, a jet propulsion unit embodying the features of the invention includes means for providing a primary power-producing gas stream. While any desired form of such means-may beemployed, I prefer to utilize :a means .of the character disclosed in the above mentioned copending application. Such means comprises'an intake opening 20, (see 'Fig. 2) centrally positionedat' the front end or the unit and i provided by a shell or cover 2i. Within the shell 1 2| are a plurality of guide vanes 22 for directing the flow of air rearwardly to a single-stage mixed flowcompressor formed by blades 23 carried by 9.

rotor24 mounted on a shaft 25 journaled at its frontend in a bearing 26 supported by guide vanes 22. The air entering the intake openingZfi passes betweenthe guide vanes 22 and is directed axially to the blades 23, from which it is discharged substantially radially and peripherally into a vaneless diffuser 21.

From the vaneless diifuser 21 the air is directed rearwardly through a vaned diffuser, indicated generally at 3!], and formed by inner and outer nested members 3| and 32 constituting an intermediate portion of the unit. The members 3| and 32 are so formed, as is apparent in Fig. 2, as to direct the air inwardly and rearwardly. The

' space between the members 3| and 32 is divided by spiral partitions 33 constituting the vanes in such space. The members 3| and 32 are so dimensioned as to provide an increased crosssectional area in the passage therebetween, in spite of the fact that the diameter of such space is reduced, so that the velocity of the air is gradually but materially reduced as it flows rearwardly through the vaned diffuser 30.

From the vaned diffuser 30 the air is conducted rearwardly into an annular space formed in the rear portion of the unit by an inner annular member 34 and an outer substantially cylindrical member 35. Within the space between the members 34 and 35 is located a combustion chamber, indicated generally at 35. The combustion chamber 36 is shown to be provided by an inner tapering wall it and an outer wall 4| capped at its forward end by a semitoroidal member 42. The members 40 and 4| are perforated to permit the entrance of the air therein, while injection nozzles 53 are mounted in the semitoroidal member42 to inject fuel into the combustion chamber 36. Spark plugs 44 may be provided for igniting the fuel.

A power-producing stream is thus produced within the combustion chamber 36 and is directed rearwardly therefrom. This power stream then passes through a compressor-driving turbine, indicated generally at 45 (see Figs. 2 and 3). The compressor-driving turbine 45 includes guide vanes 46 to direct the stream toward blades 41 carried on a rotor 48 mounted on the rear end of the shaft 25. The shaft 25 is preferably tubular in form and open at its front end to conduct air rearwardly into the rotor 48 to cool the interior of the latter. Cooling air is also conducted -to a bearing support 56, carrying the rear end of the shaft 25, the cooling air being transmitted to the bearing-structure in a mannerdescribed in the said copending application;

The thrust increaser unit disclosed herein is" adapted to receive the power stream asit is discharged from the turbine 25 and to increase the;

mass rate of flow thereof by adding a substantial mass of air thereto. To this end, I provide an annular housing 6|] (see Figs. 3 and 5) which flares rearwardly from its front end and then tapers toward its rear end. Surrounding the annular housing Bil is an annular inner casing 6| in spaced relation to the housing to provide a receiving passage 62. for the power stream of generally flaring form as it extends rearwardly The outer cas- 1 ing- .65, as is clearly indicated in Figs. 3 and 5,-

is preferably of double-walled construction. The outer casing 85 extends rearwardly of the ring 64' and is connected to a rearwardly taperingv annular discharge nozzle I8. The air passage 6'5 and the power stream passage 62 thus join and merge into a discharge passage II within the nozzle I8. The front end of the outer casing 65 terminates at a point intermediate the ends of the complete unit, as indicated at 72, while the inner wall of the air passage 55, at its forward end, is formed by a tapering annular casing structure 13 enclosing an intermediate portion of the means for producing the power stream, the forward end of the casing structure 13 preferably being rigidly secured to the member 3I constituting the outer wall of the vaned diffuser 38 (see Fig. 2). The forward end of the air passage 68 is thus provided with an annular intake opening extending from the front edge I2 of the outer casing 65 forwardly to the point where the casing structure I3 is attached to the outer member 3| of the vaned diffuser 38.

vBy means of the casing structures just described, the thrust increaser unit is provided with a power stream passage 62 and an air flow passage 66, the two merging into the discharge passage II so that air may be mixed with the power stream to increase the mass rate of flow thereof. To create the desired air flow within the air passage 68, energy in the power stream is utilized. To this end, I provide a turbine driven by the power stream and in turn driving a fan or compressor for creating the air flow. Preferably, I mount the turbine, indicated at 88 (see Fig. 3), within the power stream passage 62 adjacent the ring 84, while thefan, indicated generally at BI, is preferably mounted in the air passage 66 at the rear end thereof where the air is directed inwardly to mix with the power stream.

The turbine 88 may be of the multi-stage reaction type having two stages in the present instance, blades 82 constituting the first stage. The blades 82 are here shown as located within the ring I54 adjacent the point where it joins the inner casing BI. Rearwardly of the blades 82 are guide vanes 83 extending inwardly from and carried by the ring 64, the vanes 83 being mounted on radial pins and bushings in order to provide for heat stresses. Rearwardly of the guide vanes 83 are blades 84 constituting the second stage of the turbine. To simplify the structure and to reduce the weight of the moving parts, the blades 84 are extended outwardly or laterally beyond the path of the power stream to provide portions 85 located within the air passage 68 and constituting the fan 8|. The fan blades and the blades of the second stage of the turbine are thus directly connected by being made integral with one another so that the power derived from the power stream by the two stages of the turbine is utilized to produce the how of air within the air passage 66. The foregoing structure thus provides a turbine operating at a velocity adapted to permit efficient utilization in not more than two stages of the energy of the power stream and a singlestage fan having relative velocities in the vicinity of or above the local acoustic velocity.

In order to render the second-stage blades 84 fully effective, the separation between the power stream passage 62 and the air passage 68 is shown as being maintained substantially to the rear edge of the blades 84 and 85. To this end, the

extending guide vanes 98 connecting the housing- 68 with the inner casing BI. The guide vanes 98 are curved, as shown at 89 in Fig. 10, to direct the power stream at a proper angle of attack toward the turbine blades 82. In the present instance, twelve guide vanes 98 are provided. Within the air passage 66 are guide vanes 9| which extend radially between the auxiliary casing 63- and the outer casing 65. The guide vanes 9I extend forwardly to the casing structure member I3 and thus lie within the area of the intake opening for the air passage 68. The guide vanes SI are straight throughout the major p r-' tion of their length, thus lying in an axial plane,

while the rear end portions of the vanes 8|, as

shown in Fig. 8, are curved as at '82, to direct the air in the proper direction to facilitate operation of the fan 8I, the rear edge of the curved portion 92 being located adjacent the outer blade portions 85. Within the discharge nozzle are located further guide vanes 93 (see Figs. 2, 3 and 11) extending inwardly from the forward end of the nozzle I8 and secured at their inner ends to a rearwardly tapering member 94 constituting an extension of thehousing 68. Six guides 93 are provided in the present instance. The vanes 93 are thus located within the zone where mixing of the air with the power stream takes place, and smooths out the flow of the mixture 'in the passage H.

The blades 82 and 84 of the turbine 88 are carried on a rotor mounted within the housing 68.

The rotor is of a two-part construction compris-' ing a forward portion I88 (see Fig. 3) carrying the blades 82 and a rear portion I8I carrying the blades 84, the two portions, of course, being Iig-' idly connected with one another. portion I88, at its front end, is journaled in an anti-friction bearing I82 carried in supporting structure comprising a spider I83. I83 is provided with outwardly and rearwardly extending arms I84 integral with a ring I85. The ring I 85 is supported by radially extending struts I86 (twelve such struts being provided in the present instance) bolted to the ring I85 and extending outwardly through the guide vanes 98 which are made hollow for this purpose, as shown in Fig. 10. The outer ends of the struts I88 extend beyond the guide vanes 98 and into the guide vanes 9|, to which they are rigidly secured as by bolts I81, as shown in Fig. 8. The bearing I82 for the front end of the rotor is thus rigidly supported by the casing structure.

The rear part I8I of the rotor, which carries the second-stage blades 84 and the fan portions 85, is journaled within a plain bearing in a flanged member II8 located at the rear end of the housing within the tapering extension 94 of the housmg 68. The flanged member III) is carried by a. plurality of tubular struts III (six such struts being employed in the embodiment herein disclosed) extending radially through the guide vanes 93 and secured at their outer ends to the outer casing 65 by a construction providing for heat expansion.

The rotor is thus supported both at its front The forward The spider and rear ends by struts extending to the casing structure. With this construction, the rotor is mounted independently of the turbine 45 of the jet unit so that each turbine may rotate independently of the other at the optimum speed for performing its function. With such independence of the two turbines, the rotors may be rotated in opposite directions to reduce the external gyroscopic moment of the unit as a whole. In the present instance, the fan is of substantially greater diameter than the compressor 23 of the primary unit so that it is desirable to drive the turbine 80 at a substantially lower speed than the turbine 45. With the turbine 80 being op-- erated at the lower speed, the blades 82 may be subjected to higher temperatures without incurring undue stresses because of the heat. Because of this difference in operational speeds, the velocity of the power stream as it leaves the turbine 45 is reduced to that which is most suitable for operation of the turbine 80. In the present instance, while any desirable means may be provided to effect such reduction, I prefer to do so by adding a second stage of blades to the turbine 45. Thus, as shown in Fig. 3, the rotor 48 of the turbine 45 is provided with second-stage blades H2 (see Fig. 3), the usual guiding vanes H3 being placed between the two stages.

The blades 82 of the first stage of the turbine 80 are preferably supported on the rotor part I by means of pivot pins H4, the rotor part I00 and the inner end of each blade 82 being provided with intermeshing finger portions through which the pivot pin H4 extends. The blades 84 are similarly supported by the pivot pins H5 as shown in Figs. 3 and 6. Any other suitable means for attaching blades of this character could be utilized in place of the pivot pins H4 and H5, but it has been found that the use of such pins provides a highly desirable means for securing the blades to the rotor to avoid undue heat stresses.

The housing 60 protects the rotor and its supporting bearings from the direct heat of, the power stream, but, because the blades of the turbine extend beyond it, the housing terminates adjacent the front edge of the blades 82 while the tapering member 94 extends from the rear edge of the second-stage blades 84 to provide an annular opening through which the blades extend. Between the two sets of blades 82 and 84, the guide vanes 83 carry a shroud I (see Figure 3! constltutin an extension or the housing til. The shroud I20 has an inwardly directed flange I2I, while the housing 80 has a similar flange I22 and the tapering member 94 has a similar flange I23. Each set of blades carries shrouds I24 with inwardly directed portions paralleling the flanges I2I, I22 and I23. The shrouds I24 together with the shroud I20 thus substantially fill the space between the rear end of the housing 60 and the tapering member 94. To prevent any major leakage of the jet into the interior of the housing, labyrinths or baffies I may be mounted on the flanges I22 and I23 to cooperate with the inwardly directed portions of the shrouds I24 and thus prevent any substantial passage of gas from the power stream into the interior of the housing. A similar labyrinth I25 may be mounted on the flange I2I to cooperate with a ring I21 surrounding the rotor to prevent the gas stream from bypassing around the inner ends of the guide vanes 83.

The foregoing structure provides for operation under normal conditions and permits the attainment of maximum'efficiency at relatively low average velocity and temperature of the jet and, consequently, at reduced airplane speeds. This is in contrast with et propulsion units heretofore provided where efiiciency is poor at reduced speeds.

The present invention has the additional feature of providing for a high overload capacity, which permits a still greater increase in thrust. The capacity to meet high overload requirements is attained by supplementary combustion, by which the energy of the jet may be greatly increased. Such supplementary burning may be provided at one or more points in the path of the power stream before it is mixed with the air, as well as at an additional point in the mixing zone. With such additional combustion in the mixing zone, the fuel is used at lower efiiciency than that at points of secondary combustion within the power stream before the point of mixing, but it has a major eifect on the thrust because of the magnitude of the cold stream affected.

In the particular arrangement herein disclosed, I provide for supplementary burning at three points, two of which are located within the jet stream before mixing and the third point within the mixing zone. Thus, I may provide for secondary combustion by the introduction of fuel at a point in the power stream passage immediately to the rear, as indicated at I30, of the second stage IIZ of the turbine 45 of the primary unit, as shown in Figs. 3 and 4. I provide for further secondary combustion by the introduction of fuel into the power stream at a point between the two stages of the turbine 80, as indicated at I3I in Figs. 3 and 7. The third point of supplementary combustion lies within the mixing zone, as indicated at I32 in Figs. 3 and 11. When overload conditions are encountered in operation, fuel is preferably introduced first at the point I30. If that is insufficient, fuel would also be introduced at the point I32, while for maximum overloads fuel would be introduced at all three points.

In the case of supplementary combustion at the point I30, fuel may be introduced through apertures I33 formed in a ring structure I 34 constituting a portion of the inner casing BI. Fuel may be supplied to the apertures I33 by a pipe I35 connected with a source of fuel (not shown). It will be noted that, as shown in Fig. 3, the apertures I33 will direct the fuel rearwardly in the outwardly flaring portion of the power stream passage 62 so that combustion will take place within such flaring portion as the power stream passes to the turbine 80. While the velocity of the power stream is reduced at this point by making the turbine 45 a two-stage turbine to provide for the optimum velocity for operation of the turbine 80, such reduction of velocity is also desirable to provide for proper combustion at the point I30.

For supplementary burning at the point I3I in the power stream, the ring 64 is provided with nozzles I36 (see Fig. '7) for directing the fuel radially inward into the power stream. The nozzles I36 are supplied with fuel through passages I3l in the supporting structure, the passages I37 being connected to a supply pipe I38. The supply pipe may be carried within the vane 3|.

The third point of burning I32 located in the zone of mixing may be provided by apertures I40 (see Figs. 3 and 11) provided adjacent the forward edge of and in the guide vanes 93;the apertures I40 being connected with the supply pipes I4I mounted within the vanes 93.

The energy supplied to the power streammay thus be greatly increased by introduction of fuel atone or more of the points I30, I3 I and I32, and the resultant thrust of the jet sufiiciently increased to meet extreme overload requirements.

As heretofore mentioned, the rotor for the turbine 86 and the supporting structure therefor are adapted to be cooled. The construction of the housing 65'- with the shrouds i2 1 and the lea-flies I25 prevents the direct heat of the power stream from entering the interior of the housing. However, considerable heat would be conducted into the housingif adequate provision were not made for cooling of the interior. The cooling is effected in the present instance by air which may be usedin any desired quantity without undue loss of energy, since it is added to the propelling stream after it has served its function as a cooling medium. I Generally, coolin air is drawn inwardly into the interior of the housing 60 adjacent the front end of the rotor by means carried by the rotor, and is circulated through the interior thereof, including both of the supporting bearings therefor and in andaroundthe root portions of the blades of both stages of the turbine 80. Furthermore, a portion of the cooling air is utilized to cool the blades 84-85, the latter being made hollow for this purpose and dischargingthe cooling air into the air stream in the passage 68.

Specifically, the structure involved in efiecting cooling comprises an air intake of annular form located in the air passage 66 adjacent the intake opening of the latter. In the present instance, such air intake is provided by a deflector comprising an annular wall I56 (see Figs. 2 and 3) constituting a forward extension of the auxiliary casing member 53 and paralleling the annular casing structure 13 inthe front part of the air passage 66. The front edge of the annular wall [50 is located within the air passage and, by its relation to the annular casing structure 13, defleets a portion of the air inwardly. By locating the annular wall I53 in this manner, a local boundary layer of air within the air passage 65 is removed, thereby eliminating separation in the air passage and facilitating flow therein.

The air is conducted inwardly between the annular wall I50 and the annular casing structure I3 to an annular space of generally triangular cross section formed by the auxiliary casing member 63- 'and the inner casing 6I-. The guide vanes 9| inthe air passage 65- extend into the space between the Walls I50 and I3, as is shown in Figs. 3 and 9, to maintain a smooth flow therein. From the annular space between the auxiliary casing structure 63 and theinner casing 6-I, the air may enter the hollow guide vanes 90 to be conducted transversely through the-power stream passage 62 into. the interior of the housing 60.

Within the housing 60, means is provided for drawing the air inwardly through the path just described and for effecting circulation thereof within the housing:- Such means, in the present instance, comprises an inward flow fan formed by blade I:5.I. (seeFigs. 3 and carried by the front rotor part I110. The blades I 51, by their rotation, draw the air inwardly through the guide vanes 90 and through the spaces between the arms I04 of the spider'l03, and thence through slots I52 in the rotor part I00.

From the interior of the rotor, the air is distributed, in a number of. directions to cool various parts of the, structure. within the housing 60. Thus, to cool the frontbe'aring M2, the front rotor 12 part I09 is provided with an axial openingfex tending forwardly, and a fan I53 (see Fig. 3-)- is mounted on the front end of the rotor in front of the bearing Iii-2 to draw air axially" therethrough and discharge it laterally into the'space outside of the bearing I02. To-deflect such air as it leaves the fan I53 so that it will pass around the exterior of the spider I03, anannula-r. shield I54 is mounted Within the front end-of the housing 60. The shield I54 also serves toclose the front end of the housing 6%. Th -root portions of the blades 82 of the first stage of the turbine are cooled, as well asthe blade support portions of the rotor part H30, by air discharged through radial apertures I55 adjacentthe blades 82. Such air passes outwardly through the apertures I55 and circulates around the finger-like projections and the pivot pins l-M'by which the blades 82 are secured to the-rotor part I011. Similarly, cooling air iscirculated aroundthe exterior of the root portions of the-blades 8d of the second stage by passing radially through openings I 56 formed in the rear rotor part NH Further cooling of the blades 84 is effected by making them hollow and permitting -air'to pass into the interior thereof through apertures; 151 formed in the rear rotor part L01. The cooling air entering the blades 84 is forced outwardly by the rotation thereof and maybe discharged into the air stream adjacent the tips of the portions by rearwardly directedapertu-res IBU. CooI- ing air cannot be discharged through the blades 82 because of the pressures occurring the power stream passage 62. However, the reduced stresses on the blades 82 because of theirsmaller diameter make internal cooling unnecessary;

The flanged member H 0 supporting the rear end of the rotor may be cooled by air circulating around it and passing through apertures -I-6'-I formed in the rotor part Ill-I, such air being'disicharged through the flanged member by means of apertures I62. The rear bearing is further-cooled by an axial passage I63 in'therear rotor part IN. The air discharged through the axial passage-I 63 as well as that passing" through the apertures; F6] and IE2 is carried rearwardly'through the-tapering extension of the housing to be discharged along with the propelling streamwere; as previously mentioned, the air, utilized 'for coln'g the interior of the blades 8'4- is dischargedinto the air stream. Thus', sinceall ofthe' cooling air is discharged along with the jet stream; nolimitae tion need be placed onthe amount thereof utili-zed' and the only loss incurred is, due; to the unavoidable friction occurring the; cooling passages, which loss can be keptlow. H

The vanes 9-3 may becooled by permitting air from the air stream, as it passes, through the mixing zone; to enter the; outer ends ofthe vanes 93; such outer ends being spacedyas in:- dioatedat I64- in' Fig: 3-; from the outericasing 65-forthis purpose. Such cooling fair-passes inwardly through the vanes 93 to; ententhe tapered extension 94. The struts Il-hmay be further cooled by utilizing their tubular-form to draw outside air inwardly through their outer ends and discharge it into the stream within the tapered extension 94; 7 Such action occurs-because of the aspirating action of the jet stream about the rear end ofth extension S'Aycausing a reduction of pressure in the extension-194 efliciency of the airplane may be obtained by supplying such air from surfaces of the airplane along which the air tends to separate into a boundary layer. In Figs. 12 and 13 I have diagrammatically illustrated an airplane in which the air entering the air passage 66 is taken'from a. plurality of external surfaces of the airplane where boundary layer separation tends to occur. Thus, as shown in these figures, the wings of a plane may be provided with boundary layer control slots I10 which communicate with interior passages Ill. The passages I'II communicate at their inner ends with the air intake passage, indicated at I12, of a thrust increaser unit I13 of the character herein disclosed. The air intake passage I12 may also be provided with a forwardly facing opening I14 to withdraw a boundary layer of air along the exterior surface of the fuselage of the plane. The main air intake for the primary power stream producing unit has been indicated at I15 while the primary unit is indicated at I16, the latter discharging its power stream into the thrust increaser unit I13 in the manner herein described. Thus, an increase in overall eliiciency may be gained where the mass of air which is added to the power stream is taken from such locations on the exterior of the airplane where separation tends to occur.

' In operation of the jet propulsion unit herein disclosed, the means for initially producing the power stream operates in substantially the same manner as the jet producing unit disclosed in the said copending application, with two exceptions. The first exception is that a second stage of turbine blading is utilized in the turbine 45 to reduce the velocity to the desired value, and the second that the primary unit, instead of dis charging its power stream to directly produce the thrust, discharges it into the thrust increaser and then, after having its mass rate of flow increased by the addition of air, is discharged through the nozzle I to create the thrust stream.

More specifically, air enters the forwardly opening intake 20 (see Fig. 2) of the primary unit, passing between the guide vanes 22' and thence through the compressor 23 to the vaneless diffuser 2'! and the vaned diffuser 30. Because of the proportions of the latter, the velocity of the air is reduced to the optimum quantity for combustion effected in the annular combustion chamber 36 where, it may be said, the power stream is produced. The resulting stream thereupon passes through the two stages of the turbine 45 in which some of the energy of the stream is utilized to drive the shaft 25 and the compressor 23.

On passing to the thrust increaser unit, the power stream enters the flaring passage 62 thereof, in which the stream is directed by guide vanes 90 to the first stage of blades 82 of the turbine .80, and thence to the second stage of blades 84. The power stream thereupon passes into the mixing zone formed by the rear end of the outer casing 65 and the discharge nozzle I0.- I

With the fan 8| driven by the turbine 80, air is drawn rearwardly through the air passage 66 and forced under pressure into the mixing zone to be thermally mixed with the power stream in this zone. Within this zone, the guide vanes 93 serve to straighten out the flow for discharge in the passage 1 I.

Under normal operation, the thrust of the jet is substantially increased by such increase in the mass rate of flow thereof without any increase in fuel consumption. Moreover, with this construc- 45 and are located within the initial power stream before the temperature thereof is reduced by the addition of the mass of air. The aerodynamic loss in the two stages of the turbine 80 and the fan 8I are found to be balanced to some extent by the gain derived from the thermal mixing of the hot initial power stream and the relatively cold air before reaching the final jet velocity. When overload requirements are to be met, supplementary burning is provided by introducing additional fuel at one or more of the points I30, ISI and I32, thereby materially increasing the energy of the jet.

The structure of the thrust increaser unit as a whole is adequately cooled since substantially all of the important parts which are subjected to heat on one face or side are air cooled on the opposite side. The cooling air is drawn from an area within the air passage 66 in such manner that the boundary layer along one wall is utilized for this purpose, and with such arrangement the flow Within the passage 66 is thereby facilitated. The cooling air, on entering the housing 60, is distributed throughout the space therein, adequately cooling all structure contained therein as well as beingdischarged outwardly through the blades 8485 to cool the latter. The cooling air is discharged into the propelling stream both through the outer ends of the blades 85 as well as through the tapering member 94, constituting an extension of the housing 60. Because of this fact, free use of air may be made for cooling purposes without entailing loss other than such small frictional loss as results from movement of the air in and around the parts within the housing 60.

The rotary parts of the thrust increaser unit comprising the turbine 8% with the fan 8! are supported independently of the turbine 45 so that each may operate at the optimum speed for the function it is to perform. Further advantage of this independence of the two units is obtained by providing for rotation in opposite directions to reduce the external gyroscopic moment of the unit as a whole.

The structure is self-supporting in that the various casing members are tied together by the guide vanes, while the rotary structure within the housing 60 is adequately supported by the front and rear struts I06 and I I I extending through guide vanes to outer portions of the casing structure.

By utilizing the intake opening of the air passage 66 to draw air from external surfaces of the airplane where boundary layer separation may tend to occur, as shown in Figs. 12 and 13, a still greater improvement in overall propulsive efficiency may be thereby obtained.

I claim 1. In a jet propulsion unit having means for providing a power-producing stream, an annular housing structure and an annular wall providing a passage for saidstream, and supporting structure within said housing, a rotor carried by said supporting structure, said housing structure having an annular opening and inturned flanges at the margins of said opening, turbine blades mounted on said rotor and extending through said opening into said passage, an annular shroud structure carried by said blades for rotation therewith and substantially closing said opening,

eipadcgs said shroud structure having inturned flanges paralleling the flanges of said housing structure, and baliies positioned between the flanges on the housing structure and the flanges on the shroud structure to prevent said stream from entering said housing structure.

2. A jet propulsion unit comprising means for providing a power-producing stream including combustion means, an annular housing, an outer casing surrounding said housing in spaced relation, an annular wall interposed between said housing and said casing to separate the space into an inner stream-receiving passage and an outer air passage, means driven by said stream for producing a flow of air rearwardly through said air passage, a plurality of hollow vanes extending inwardly from said outer casing to support the rear end of said housing, and means mounted in said vanes for introducing fuel therethrough into said stream to increase the energy thereof.

3. A thrust increaser for a jet unit comprising a, central annular housing, means providing annular power stream receiving and air passages surrounding said housing, a rotor located within said housing and having blades extending into both of said passages to be driven by the power stream and to produce a flow of air in said air passage, hollow guide vanes extending through said stream-receiving passage, and means carried by said rotor within said housing for drawing air through said vanes into said housing to cool the interior thereof.

4. A thrust increaser for a jet unit comprising a central annular housing, means providing annular power stream receiving and air passages surrounding said housing, a hollow rotor mounted within said housing and having blades extending into both of said passages to be driven by the power stream and to produce a flow of air in said air passage, hollow guide vanes extending through said stream-receiving passage and open to said air passage, and means carried by said rotor within said housing for drawing. air from said air passage inwardly through said vanes and circulating it in and around said rotor.

5. A thrust incr-easer for a jet unit comprising a central annular housing, means providing annular power stream receiving and air passages surrounding said housing, a rotor located within said housing and having blades extending into both ofsaid passages to be driven by the power stream and to produce a flow of air in said air passage, hollow guide vanes extending through said stream-receiving passage, a spider rotatably supporting the front end of said rotor, struts connected to said spider and extending through said vanes, and means carried by said rotor adjacent the front end thereof for drawing air inwardly through said vanes and between the arms of said spider to cool the interior of said housing.

drawing cooling air inwardly through said vanes and said slots to cool the interior of said rotor.

7'. A thrust increaser for a jet unitv comprising .16 a central annular housing, means providing arinular power stream receiving and air passages surrounding said housing, a hollow rotor located within said housing and having bladesextending into both of said passages to be driven by the power stream and to produce: a flow or 'air through said air passage, hollow guidevanes extending through said stream-receiving passage, means carried by said rotor for drawing cooling air inwardly through said vanes and into said rotor, means for supporting said rotor including a bearing for the front end thereof, and means carried by the front end of said rotor for drawing a portion of said cooling air through, said bearing for cooling it.

8. A thrust increaser for a jet unit comprising a centralannular housing, means providing annular power stream receiving and air passages surrounding said housing, a hollow rotor located within said housing. and having blades extending into both of said passages to be driven by the power stream and to produce a flow of: air through said air passage, hollow guide vanes extending through said stream-receiving passage, said rotor having radial openings adjacent said blades, and means carried by said rotor for drawing cooling air inwardly through said vanesinto said rotor and for forcing it rearwardly tocirculate through said openings to cool the inner ends of said blades.

9. A thrust increaser for a jet unit comprising central annular housing, means providing annular power stream receiving and air passages surrounding said housing, a hollow rotor located within said housing and having bladesextending into both of said passages to be driven by the power stream and to produce a flow of air through said air passage, hollow guide vanes extending through said stream-receiving passage, and'meanscarried by said rotor for drawing cooling air inwardly through said vanes intosaid rotor; said blades being hollow and said rotor having openings in communication with themteri-orv of said blades whereby cooling; air from the rotor will be drawnoutwardly through said openings and said blades to cool the latter.

10. A thrust increaser for a jet unit comprising a central annular housing, means providing annular power stream receiving andair passages surrounding said housing, a hollow rotor located within said housing and having blades extending into both of said passages to be driven by. the power stream and to produce a flow of air through said air passage, hollow guide vanes extending through said stream-receiving passage, bearing structure supporting the rear end of said rotor, andmeans carried by said rotor for drawing cooling air inwardly through said guide vanes into said rotor adjacent the front end thereof and for discharging it through said bearing structure to cool the latter.

ll. A thrust increaser for a jet unit comprising an annular housing, inner and outer annular casings in spaced relation to each other and to said housing to provide an inner passage for receiving the power stream from said unit and an outer air passage, a turbine mounted in said housing and having blades extending into both passages to be driven by said power stream and to produce a flow of air through said air passage, means carried by said turbine for drawing cooling air into said housing to cool the interior thereof, a, discharge nozzle for mixing and discharging. saidflow of air with said power stream, and tubular means extending fromsaid housing passage for receiving the power stream from said unit and an outer annular air passage, drive means mounted in said housing and having blades extending into said inner passage to be driven by said stream and into said air passage to produce an air stream therein, a nozzle through which said streams discharge, tubular means within said nozzle and constituting an extension of said housing, and hollow guide vanes in said nozzle in the area where said streams enter said nozzle and openinginto said tubular means, the outer ends of saidvanes being open to receive air from said air stream whereby such air is conducted inwardly into said tubular means for cooling said vanes and-is discharged with the propelling stream.

13. A thrust increaser for a jet unit comprising casing structure providing an inner annular passage for receiving the power stream from said unit and an outer annular passage for an air stream, drive means mounted in said casing structure adapted to be driven by said power stream and to produce said air stream, a nozzle for receiving both of said streams, tubular means within said nozzle, and hollow guide vanes extending radially in said nozzle in the area where said streams enter said nozzle and opening at their inner ends into said tubular means, said guide vanes having openings in their portions contacted by the air stream to permit air to enter the guide vanes for coolin of the portions contacted by the power stream, such cooling air being-conducted inwardly through the guide vanes into said tubular means for discharge therethrough.

14. A thrust increaser for a jet unit comprising casing structure providing an inner annular passage for receiving the power stream from said unit and an outer annular passage for an air stream, drive means mounted in said casing structure adapted to be driven 'by said power stream and to produce said air stream, a nozzle for receiving both of said streams, tubular means within said nozzle, and tubular struts extending radially inward from the exterior of said casing structure into said tubular means to support said drive means, said struts being open at both ends to permit air to be drawn inwardly therethro-ugh 'into said tubular means for discharge therethrough.

15. A jet propulsion unit comp-rising a first annular casing having an intermediate portion rearwardly tapered and a substantially cylindrical rear portion, a second annular casing surrounding said rear portion in spaced relation thereto to provide an air passage and tapering rearwardly thereof to provide a discharge nozzle, the front end of said second casing being located rearwardly of the front end of said intermediate portion to provide an annular intake opening for said air passage, means in said first casing for providin a power-producing stream, an annular housing located within said rear portion in spaced relation thereto to provide therewith a stream-receiving passage, and a turbine mounted in said housing and having blades extending into said streamreceiving passage to be driven by said stream and into said air passage to produce a flow of air therethrough.

16. A jet propulsion unit comprising a first an- 18 nular easing having an intermediate portion rearwardly tapered and a substantially cylindrical rear portion, a second annular casing surrounding said rear portion in spaced relation thereto to provide an air passage and tapering rearwardly thereof to provide a discharge nozzle,

"the front end of said second casing being located rearwardly of the front end of said intermediate portion to provide an annular intake opening for said air passage, means in said first casing for providing a power-producing stream, an annular housing located within said rear portion in spaced relation thereto to provide therewith a streamreceiving passage, a turbine mounted insaid housing and having blades extending into said stream-receiving passage to be driven .by said stream and into said air passage to produce a flow of air therethrough, hollow guide vanes mounted in said stream-receiving passage and open at their inner ends tothe interior of said housing, and means mounted .in said air passage adjacent its intake opening'to deflect air into 'said guide vanes to cool'the interior of said housing.

17. A jet propulsion unit comprising'annular casing structure having an internal housing and providing an inner annular passage to receive a power stream and an outer annular air pas sage having an annular intake opening, a turbine mounted within said housing and having blades extending into said inner passage to be driven by said stream and into said air passage to produce a flow of air therethrough, hollow guide van-es in said inner passage and communicating with said housing, and means mounted in said air passage adjacent its intake opening to deflecta boundary layer of air in said passage into said vanes to cool the interior of said housing.

'18. A jet propulsion unit comprising annular casing structure having an internal housing and providing an inner annular passage to receive a power stream and an oute annular air passage having an annular intake opening, a' turbine mounted within said housing-and having blades extending into said inner passage to be driven by said stream and into said air passage to produce a flow of air therethrough, hollow guide vanes in said inner passage and communicating with said housing, said air passage having an inner wall tapering inwardly from the front edge of 'said intake opening, and an annular deflector paralleling a portion of said wall to deflect the boundary layer of air along said wall into said vanes to cool the interior of said housing.

19. A jet propulsion unit comprising means for providing a power-producing stream including combustion means, casing structure including an inner annular housing and an outer casing in spaced relation and providing a passage for said stream, a plurality of hollow vanes extending inwardly from said outer casing in said passage to support said housing, and fuel nozzles mounted in said vanes for introducing fuel into said stream for secondary combustion to increase the energy of the stream.

20. In a jet propulsion unit, a central annular housing, a casing extending about said housing and providing therewith an annular passage for a power stream, said casing being subject to the passage of air over its exterior, a rotor located within said housing and having blades extending into said passage to be driven by the power stream, hollow guide vanes extending generally radially through said passage and open at their ends to the exterior ofsaid casing and the interior of said housing, and an air impeller carried 19 by said roton'withinsaid: housing'ifor drawing :air inwardly through said vanes into. said'housingto cool the irrterior' thereof;

a 21.: In azjet:propulsioniunit, a central annular housing, acasing. extending about said housing and-providing therewith an. annular passage. for apowersstream; said casing. being subject. to the passageiofi airover its exterior, a rotor located within .said housing. and having blades extending into; saidpassage: to be driven by the power stream; hollow guidev vanes; extending generally radially'through' said passage and open at their ends. to. the exterior of'said casing and the interior ofi saidhousing; supports for. the rotor extending through: said. guide vanes,. and an. air impeller .carried by said rotor within said. housing-for drawingair inwardly throughsaid vanes into'saidhousing. andv for circulating it. in and around-.saidrotor'.

22:. In a jet" propulsion: unit h'aving'means for providing; a power producing stream, a. casing structure having an annular: wall separating the space Withinsaid' structure: into an inner. passage toreceive said stream and an outer passage open-at its front end to'receive air, said passages merging at their rear ends, said casing terminating in a nozzle, said nozzle beginning at the junction of said merging inner and outer passages, a rotor mounted within said structure and having at least two stages of turbine blades. positioned in said :stream to be driven thereby, said turbine bladesbeing. enclosed'within said inner passage, a shroud enclosing 'at least the rearmost stage of said turbineblades to complete the enclosing of all of said turbine blades, said fan blades'being disposed substantially at the junction of said passages, said-shroud forming an extension of said annular Wall, and supplementary burners disposed to-therear of said fan and generally at the. front end of saidnozzle Where the streams are mixed. together;

-;=23. A jet propulsion unit comprising means for providing a power producing stream including combustion; means, inner. and outer; generally concentric casings to provide an inner stream receiving passage'and an outerair passage, a turbine having blades extending into said inner passage, fan blades fixed to said turbine and extending into said air passage for forcing air into said stream, a nozzle to receive said streamand the air and supplementary fuel burners certain of which are disposed before said turbine and others of'Which are disposed. after said fan; in said composite power'and air stream.

GEORGE: F. W'ISLICENUS.

REFERENCES CITED The following references are of record in the file ofthis; patent:

UNITED. STATES. PATENTS Number Name Date I Be. 14,355 Ljungstrom Sept/11,1917 1,362,405 Emmet Dec. 14, 1920 2,168,726 Whittle Aug. 8, 1939 2,216,731 Birmann Oct. 8,1940 2,243g467 'Jendrassik May 27, 1941 2,333,053" Stroehlen Oct: 26, 1943 2,336,323 Warren Dec. 7, 1943 2,346,178 Mercier Apr: 11', 1944 2,396,911 Anxionnaz et al. Mar; 1-9, 1946 2,399,046 Larrecq Apr.23, 1946 2;405,919 Whittle; W A11'gr13, 1946 2,409,176" Allen Oct. 15, 1946 2,410,804 Baumann Nov. 12, 1946 2,425,177 Cronstedt Aug. 5, 1947 2,435,836 Johnson Feb: 10, 1948 2,455,458 Whittle Dec.7, 1948 2,463,461 Price Apr.'26, 1949 2,479,777 Price Aug. 23, 1949 2,505,660 Baumann Apr. 25, 1950 2,509,890 Stalker May '30, 1950 FOREIGN PATENTS Number Country Date I GreatvBritain Aug. 29, 1939

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