RU2616433C1 - Input device of centrifugal turbines - Google Patents

Abstract

FIELD: machine engineering.

SUBSTANCE: invention applies to these input devices that contain consecutive on-the-go working environment radial oriented round adapter input section to the rectangular section, increase the width of the cross-section in the radial plane, an intermediate Chamber and radial-axial axisymmetric konfuzor, with adapter in the direction of progress working environment expanding in radial plane and narrows in the meridional section, and the camera are narrowed towards the working progress environment in a meridional plane with the same angle, the boundary between the camera and the section konfusor-cylindrical and convex meridional circumscription of konfusor rounded to its radius. Square boundary sections between adapter, section camera and konfusor are equal (1.1…0.9) to the square of the section input device. Radius of convex meridional konfusor outline is (4…1) width of its output. Taper angle adapter in the meridional plane is equal to the corner of the narrow sections, and the camera in the plane. Taper angle sections and Chambers in a meridional plane is determined by a formula which included four geometric parameter of device: edge square cross-section between the section and the camera, the width of this section in the radial plane width and edge diameter cross section between the camera and the konfusor.

EFFECT: invention reduces head loss in the device.

7 dwg

Description

The invention relates to energy turbomachines and can be used in centrifugal compressors, blowers and pumps.

Entrance devices of centrifugal turbomachines having three-dimensional sections of the working surface are known (Fig. 56 in the industry catalog "Centrifugal and Axial Compressor Machines". - M .: TSNIITEI for heavy and transport vehicles, 1992). The disadvantage of such input devices is the high complexity of manufacturing.

The noted drawback is eliminated in the input devices, the working surface of which does not have three-dimensional sections. A well-known input device of this type (Fig. 1 in the article "Comparison of low-pressure air centrifugal compressors offered by firms of the CIS countries." // Proceedings of the fifth international symposium "Consumers-manufacturers of compressors and compressor equipment." - St. Petersburg, 1999, p. 170 -174) contains a radially oriented adapter arranged in series along the working medium from a circular input section to a rectangular section, a section for increasing the width of the section in the radial plane, an intermediate chamber, and a radially axial esimmetrichny converger annular outlet section. In this case, the adapter in the direction of the working medium’s expansion expands in the radial plane and narrows in the meridional plane, the section and the camera taper in the direction of the working medium’s movement in the meridional plane with the same angle, the boundary section between the chamber and the confuser is cylindrical, and the convex meridional contour of the confuser is rounded off in radius .

A disadvantage of the known input device is a significant pressure loss.

The causes of significant pressure losses are:

a big difference between the areas of the boundary sections between the adapter, section, camera and confuser from the input section of the device;

small radius of curvature of the convex meridional contour of the confuser (this radius is less than the width of the output section);

significant fractures of the working surface in boundary sections between the adapter, section and camera;

the narrowing angle of the section and the chamber in the meridional plane is taken from structural considerations without taking into account the rational area of the boundary section between the section and the camera.

The aim of the present invention is to reduce the pressure loss.

This goal is achieved by the fact that in the known input device of a centrifugal turbomachine containing a radially oriented adapter from a circular input section to a rectangular one, a section for increasing the width of the section in the radial plane, an intermediate chamber and an axially symmetric axisymmetric confuser with an annular output section, arranged sequentially along the working medium moreover, the adapter in the direction of travel of the working medium expands in the radial plane and tapers in the meridional plane, the section and the chamber taper in board working fluid running in the meridional plane with the same angle, the boundary section between the chamber and the confuser - cylindrical and convex meridian bypass converger rounded radially,

the area of the boundary sections between the adapter, section, camera and confuser are equal (1.1 ... 0.9) to the area of the input section of the device;

the radius of curvature of the convex meridional contour of the confuser is (4 ... 1) the width of its output section;

the narrowing angle of the adapter in the meridional plane is equal to the narrowing angle of the section and the chamber in this plane;

the narrowing angle of the section and chamber in the meridional plane is determined by the ratio

in which γ is the angle of narrowing of the section and chamber in the meridional plane,

f _f and a _f - respectively, the area and width in the radial plane of the boundary section between the section and the camera,

b _c and D _c - respectively, the width and diameter of the boundary section between the camera and the confuser.

This technical solution meets the criterion of "significant differences", as it allows you to comprehensively optimize all the basic geometric parameters of the known input device of centrifugal turbomachines and thereby ensure maximum gas or hydrodynamic efficiency of this device.

In FIG. 1 shows the input device of a centrifugal turbomachine, a meridional section; in FIG. 2 is a radial section AA in FIG. one; in FIG. 3 is an I / O section in FIG. 2; in FIG. 4 - section p-p in FIG. 2; in FIG. 5 is a cross section ff in FIG. 2; in FIG. 6 - dependence of the pressure loss coefficient ζ of the radial-axial confuser on the arguments ζ; in FIG. 7 is a section BB in FIG. 2.

The input device comprises an adapter 1, a section 2, an intermediate chamber 3 and a radially axial axisymmetric confuser 4 arranged in series with the working medium. The axis 5 of the adapter is oriented radially. The input section 6 of the device and the adapter 1 is round. Boundary section 7 between the adapter 1 and section 2 is rectangular. Boundary section 8 between the section 2 and the camera 3 is shaped. The boundary section 9 between the camera 3 and the confuser 4 is cylindrical. The output section 10 of the confuser 4 and the device is annular.

The adapter 1 in the direction of travel of the working medium expands in the radial plane with an angle α and narrows in the meridional plane with an angle δ. Section 2 in the direction of the working medium expansion expands in the radial plane with an angle β and narrows in the meridional plane with an angle γ equal to the narrowing angle in the meridional plane of the chamber 3. The convex meridional contour 11 of the confuser 4 is rounded with a radius R _iss .

The input device is made in accordance with the invention:

the area of the boundary sections 7, 8 and 9 between the adapter 1, section 2, the camera 3 and the confuser 4 are (1.1 ... 0.9) the area of the input section 6 of the device;

_MY radius R of curvature of the convex contour of the meridian 4 converger 11 is in the range (1 ... 4) the width of the outlet section b _O 4 converger 10;

the narrowing angle δ of adapter 1 in the meridional plane is equal to the narrowing angle γ of section 2 and chamber 3 in this plane;

the narrowing angle γ of section 2 and chamber 3 in the meridional plane corresponds to relation (1).

The input device operates as follows.

The working environment of the feed pipe (in the drawing the pipe is not shown) enters the circular inlet section 6 device at a speed with _Bx, passes successively adapter 1, section 2, the camera 3, the converging tube 4 and exits the apparatus via an annular outlet section 10 at the speed c _O at the entrance to the first impeller of the turbomachine (the wheel is not shown in the drawings). _O speed with a lot more speed with _Rin as much smaller than the area of its inlet cross-section (from 521 in the book YB Galerkin "Turbochargers" in any centrifugal turbine engine output section of the input device area -.. M .: Inform -. Publishing Center " KHT ", 2010). The flow of the working medium through the device is accompanied by pressure losses.

The adapter 1, section 2, the chamber 3 and the confuser 4 are local resistances, since their lengths are small in comparison with their hydraulic diameters. The pressure loss in local resistances is the sum of friction losses and additional local losses (section 1.5.4 of the Handbook for the calculation of hydraulic and ventilation systems. - St. Petersburg: Mir and Family Publishing House, 2002). Since the friction loss is proportional to ² , for given areas of the input section 6 and output section 10, these losses in the adapter 1, section 2, chamber 3 and confuser 4 are the smaller, the larger the area of the boundary sections 7, 8 and 9 between the adapter 1, section 2, chamber 3 and confuser 4 compared with the inlet cross-sectional area 6. Local losses are due to local diffuser zones in the flow of the working medium. Therefore, these losses, unlike friction losses, the smaller the smaller the area of the boundary sections 7. 8 and 9 compared with the area of the inlet section 6. Therefore, the condition for the minimum pressure loss in the input device is the approximate equality of the areas of the boundary sections 7, 8 and 9 of the input section 6 of the device, which is reflected in the invention.

Appearing in expediency invention recommendations for converger 4 (R = _MY (1 ... 4) b _O) of radius of curvature R of the convex meridian _MY bypass 11 follows from FIG. 6, which shows the dependence of the pressure loss coefficient ζ of confuser 4 on its dimensionless geometric parameters R _vy / b _o and b _c / b _o . Referring to FIG. 6 curves are calculated according to the method described on p. 14 ... 16 in No. 4 of the journal "Compressor Engineering and Pneumatics" for 2011. From FIG. 6 it can be seen that the optimal value of R _vy / b _out , corresponding to the minimum of ζ, is practically independent of b _c / b _out and is approximately 4. Therefore, if we pursue the only goal of reducing pressure losses in the confuser (and, therefore, in the entire input device ), then R _{issue. opt} ≈4b _out However, the value of R _vyp , which is 4 times superior to b _out , determines the large size of the input device, especially radial ones. Therefore, referring to the limited sizes of the device can prevent R 4b _{O MY} less, but not less than _O 1b, since _MY R <1b _O of Fig. 6 ζ begins to increase very rapidly.

The recommendation in the invention to equate the narrowing angle δ of the adapter 1 in the meridional plane to the narrowing angle γ of the section 2 and chamber 3 in the same plane helps to achieve the objective of the invention (to reduce the pressure loss) due to the fact that at δ = γ the kink of the working surface of the device in the boundary section 7 between the adapter 1 and section 2 in the meridional plane (see Fig. 1).

The relation (1) in the invention for the narrowing angle γ of section 2 and chamber 3 in the meridional plane follows from the expression

for the area f _{f of the} boundary section 8 between section 2 and the chamber 3. The proof of expression (2) is given below.

From FIG. 5 shows that

From FIG. 7

From FIG. 2

Substituting (5) in (4) and (4) in (3), we have

According to the table of indefinite integrals (p. 125 on p. 97 of the Handbook of Mathematics by I. N. Bronstein and K. A. Semendyaev, 1986 edition)

Therefore, the definite integral in (6)

Substitution of (7) into (6) gives expression (2) for the area f _f , as required.

Claims (6)

The input device of a centrifugal turbomachine, comprising a radially oriented adapter from a circular input section to a rectangular one, a section for increasing the section width in the radial plane, an intermediate chamber and an axial axisymmetric radial-axial confuser with an annular output section, arranged in series with the working medium, the adapter in the direction of the working medium expands in the radial plane and narrows in the meridional, the section and the chamber narrows in the direction of the working medium in the meridional flatness with the same angle, the boundary section between the camera and the confuser is cylindrical, and the convex meridional contour of the confuser is rounded in radius, characterized in that the areas of the boundary sections between the adapter, section, camera and confuser are equal to (1.1 ... 0.9) the area of the input section of the device, radius the rounding of the convex contour of the confuser is (4 ... 1) the width of its output section, the narrowing angle of the adapter in the meridional plane is equal to the narrowing angle of the section and the chamber in this plane, and the latter is determined by the ratio

wherein γ is the angle of narrowing of the section and chamber in the meridional plane, f _f and a _f - respectively, the area and width in the radial plane of the boundary section between the section and the camera, b _c and D _c - respectively, the width and diameter of the boundary section between the camera and the confuser.

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