US2701445A - Ignition equipment for the combustion equipment of rocket motors - Google Patents

Description

Feb. 8, 1955 E. G. D. ANDREWS ET AL 2,701,445

IGNITION EQUIPMENT FOR TME cOMEUsTION EQUIPMENT OF ROCKET MOTORS Filed Aug. 5, 1951 United States Patent O IGNITION EQUIPMENT FOR THE COMBUSTION EQUIPMENT OF ROCKET MOTORS Edward G. D. Andrews and Anthony W. T. Mottram, Coventry, England, assignors to Armstrong Siddeley Motors Limited, Coventry, England Application August 3, 1951, Serial No. 240,197

Claims priority, application Great Britain September 8, 1950 1 Claim. (Cl. 60-39.82)

The main object of this invention is to provide a satisfactory ignition equipment, for the combustion equipment of a rocket motor adapted to burn a mixture of a liquid fuel (such as methyl alcohol admixed w1th water) and a liquid oxidizer (such as liquid oxygen or nitric acid).

According to the invention, the ignition equipment includes a precombustion or igniter chamber in which a portion of the fuel and oxidizer are combined (belng ignited by means of a spark plug or the like), and which is surrounded by a cooling jacket through which a portion of the fuel is passed to be sprayed from the outlet of the chamber.

In the accompanying drawing:

Figure l is an elevation of the main chamber of the combustion equipment having attached thereto ignition equipment according to the invention;

Figure 2 is a sectional elevation, and Figure 3 an end elevation, of the ignition equipment; and

Figure 4 is a fragmentary view, to a larger scale, mainly of the outlet end of the igniter chamber.

The drawing shows the invention in a form which is intended for use in a rocket motor adapted to be operated as disclosed in the specication of co-pending patent application Serial No. 240,216 tiled August 3, 1951, and having combustion equipment arranged as therein disclosed. The ignition equipment 8 includes an igniter chamber 9 communicating with the main chamber 10 of the combustion equipment such that the jet of flame issuing from the outlet 11 of the igniter chamber will meet the main supplies of liquid fuel and oxidizer delivered to the main chamber, thereby igniting these main supplies. The main chamber is provided with a jacket 12 through the jacket space of which is circulated fuel i supplied thereto by the pipe 13, the outlet end of the jacket space being connected by a pipe 14 to an annular spray device coaxial with a spray device for the oxidizer supplied by a pipe 15.

The actual igniter chamber is formed as a shell, for 7 example, of stainless steel, which is cylindrical at 17 for about half its length and is then connected by a substantially truste-conical portion 18 to the short outlet 11 which is also cylindrical. This shell is spaced within and with quite a small clearance from a correspondinglyshaped jacket wall 19 of the ignition equipment, the wall being built up of a main part 19a, a nozzle part 19b, and a uniting sleeve 19e. At the inlet end of the igniter chamber are connections 20, 21 for delivering liquid fuel and oxidizer respectively to orifices 22 through which they are sprayed, the sprays meeting one another near that end of the ignitor chamber and in the vicinity also of the operative end of a spark plug or the like 23 inserted through a hole 24 in the wall of the ignition equipment for initiating the pilot ame when starting up.

2,701,445 Patented Feb. 8, 1955 ICC Approximately one-third of the total fuel delivery to the ignition equipment may be sprayed directly into the chamber in this manner, the remaining two-thirds being led by a duct 25 to the jacket space 26 between the shell and the surrounding jacket wall. The shell engages part of the wall by means of a helical ridge 27, whereby to cause the fuel in the jacket space to swirl about the axis of the shell as it travels along the jacket space, and at other places, as shown at 28, 29 and 30, the shell may be provided with plain ridges each having in them a series of swirl-introducing openings 31 for the same purpose. Thus, this cooling fuel has obtained a considerable swirl velocity by the time it leaves the jacket to join the burning gases issuing from the outlet 11 of the igniter chamber. The fuel leaving the jacket space is subject to an ejector action by reason of the elllux of gases from the outlet 11 of the igniter chamber, the frusto-conical portion 18, as well as the expansion due to combustion wthin the chamber 10, ensuring a high velocity for this e ux.

The total igniter fuel may be about 3% to 5% of the main fuel supply t0 the combustion equipment.

It is convenient to provide the inlet wall of the igniter chamber with a pressure tapping, shown at 32, by means of which it is possible to indicate when ignition in the chamber has taken place-and, e. g., to disconnect the supply to the spark plug or the like by means of the systern disclosed in the specification of the aforesaid co pending patent application. v

What we claim as our invention and desire to secure by LettersPatent of the United States is:

For the combustion equipment of a rocket motor adapted to burn a mixture of a liquid fuel and oxidizer, ignition equipment including an igniter chamber which is substantially cylindrical for about half its length and is then connected by a substantially frusto-conical portion to a short outlet to communicate with the combustion equipment, said frusto-conical portion and short outlet accelerating the ow of the burning gases from the cylindrical portion of said igniter chamber, means for supplying a portion of the fuel and oxidizer to said chamber, means for igniting the fuel and oxidizer supplied thereto, a jacket around said chamber, and means for circulating another portion of the fuel through the jacket space to cool the igniter chamber and to be preheated thereby, said jacket having an outlet for connection to the combustion equipment and surrounding with clearance said short outlet and from which the preheated jacket fuel is entrained by an ejector action by the burning gases passing out of said short outlet from said igniter chamber.

References Cited in the le of this patent UNITED STATES PATENTS 1,879,186 Goddard Sept. 27, 1932 2,286,909 Goddard June 16, 1942 2,395,403 Goddard Feb. 26, 1946 2,408,111 Truax et al. Sept. 24, 1946 2,470,564 Lawrence et al May 17, 1949 2,480,147 Letvin Aug. 30, 1949 2,489,716 McCollum Nov. 29, 1949 2,500,334 Zucrow Mar. 14, 1950 2,520,751 Zucrow Aug. 29, 1950 2,525,207 Clarke et al. Oct. 10, 1950 FOREIGN PATENTS 522,435 Germany Apr. 9, 1931

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