US2618925A - Flow control means for pulse jet combustion units - Google Patents

Description

Nov. 25, 1952 G. F. WISLICENUS FLOW CONTROL MEANS FOR PULSE JET COMBUSTION UNITS Filed Jan. 31, 1947 InvenTor George F Wislicenus Attorneys Patented Nov. 25, 1952 FLOW CONTROL MEANS FOR PULSE JET COMBUSTION UNITS George F. Wislicenus, Toledo, Ohio, assignor to Packard Motor Car Company, Detroit, Mich., a corporation of Michigan Application January 31, 1947, Serial No. 725,667

3 Claims.

The invention relates generally to jet propulsion units and more particularly to a combustion unit for producing a pulse jet.

The general object of the invention is to provide a combustion unit for producing a pulse jet and having a novel inlet valve.

Another object is to provide a combustion unit of the foregoing character, in which the inlet valve has no moving parts.

A further object is to provide a combustion unit of the foregoing character, in which the energy tending to create a back or reverse flow from the point of combustion is utilized to substantially prevent such flow.

Still another object is to provide a novel method of preventing reverse flow in a combustion unit for producing a pulse jet.

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

Figure 1 is a longitudinal sectional view of a combustion unit embodying the features of the invention.

Fig. 2 is an end view of the left-hand end of the unit as shown in Fig. 1.

Fig. 3 is a fragmentary developed view taken substantially on the line 33 of Fig. 1.

In a jet propulsion unit of the pulse jet type, air is forced into a combustion chamber where fuel is intermittently supplied and ignited,

thereby producing pulsations of combustion gases tending to move in both directions from the point of combustion. The gases moving toward the tail pipe of the unit of course produce the propelling jet. The gas moving toward the air intake would produce an adverse reaction, if permitted to pass out through the air intake, and for this reason a valve is provided in the intake to prevent the passage of gas forwardly therethrough. In units of this character, the valve has heretofore usually been of the flap valve type involving moving parts which are held open when air is forced inwardly or rearwardly through the intake but which are forced closed by any flow of gas forwardly. Obviously, because of the high velocities of flow involved and, more importantly, the high temperature of the gas, a flap valve construction is not very satisfactory and may rapidly become disabled to perform its function of preventing reverse flow.

The present invention provides a structure which eliminates the difficulties encountered in the use of a flap valve and includes a valve having no moving parts. The present valve utilizes the energy of any gas tending to move reversely, to prevent the flow thereof, and the air passage leading from the intake to the combustion cham-,

her is formed to attain this end. At the same time the passage permits a free flow of air to the combustion chamber to effect combustion therein.

Generally described, a device embodying the invention involves means for imparting to a reverse flow of gas a swirling movement and then confining the gas in a portion of the passage where the diameter of the swirling movement is gradually reduced. Such reduction of diameter increases the velocity of the gas and consequently the kinetic energy in the gas. This results in a resistance to flow. At the point where the passage meets the intake, means is provided for dissipating the energy and thereby preventing any major reverse flow.

In the embodiment of the invention shown in the drawings, the unit comprises a body structure indicated generally at Ill and having an inner casing II providing an axially positioned passage through the entire length of the body structure Ill. The passage comprises an intake portion I2, an intermediate portion I3, and a combustion chamber portion I l. The intake portion I2 is centrally located and preferably converges slightly toward its downstream end. Air is adapted to be forced inwardly through the intake I2 by means of ram pressure or of an impeller or the like (not shown). If the unit shown in the drawings is to be utilized by itself as a jet unit, then such compressor means will be mounted Within the intake portion I2. However, if the jet propulsion unit is to be composed of a plurality of combustion units as illustrated in the drawings by arranging such units in an annular series within a main casin then the compressor will be positioned forwardly of the intake portion I2 and will distribute air to all of the combustion units.

Extending rearwardly from the intake portion I2 is the intermediate portion I3 which is given an annular form diverging first outwardly from the intake portion I2 and then converging to the combustion chamber portion I4, which is centrally positioned. To so shape the intermediate portion I3, an inner cone member I5 tapered toward both ends is mounted within the intermediate portion to provide the annular form for the air passage. The inner cone l5 may be supported in the position shown by a plurality of radial vanes I6. To effect combustion of the fuel in the combustion chamber I4, a burner 23 may be mounted on the rear end of the inner cone member I5 to spray fuel rearwardly in the combustion chamber portion It. To ignite the fuel, the spark plug 2| may be mounted in the wall of the combustion chamber portion. With this arrangement, air will. enter the intake I2,

pass rearwardly through the intermediate portion I3 about the inner cone member [5, and then mix with the fuel supplied by the burner 20 for combustion within the portion 14.

When combustion takes place within the portion M, the resulting gas, of course, will tend to move in all directions from the point of combustion. The combustion gas fiowing'rearwardly from the combustion chamber l4 ultimately produces the jet stream. The gas moving forwardly from the combustion chamber toward *the'intermediate portion [3 would produce an adverse reaction unless the flow of such gas forwardly were greatly reduced. To throttle such flow, the intermediate portion is given the particular form shown in the drawing and the vanes [6 are shaped to cooperate therewithin preventing the forward 'ilow. Thus, the vanes :l B which are located at the point of maximum diameter in the intermediate portion l3 are given a helical form, as clearly shown in Fig. 3. Such helical form imparts to any gas moving forwardly at'that point .a swirling motion. Forwardly from the vanes 16, the intermediate portion l3 converges toward the .iintake portion 12 so that the gas, as it moves forwardly from the vanes, attains a 'higher'linear velocity because of the decreasing diameter since, .in such a circumstance, the velocity of the gas multiplied by the radius at which it is spinning er swirling remains constant. The centrifugal force of the gas thus increases so that a resistance is set up which tends to prevent the gas from moving inwardly, .as it must in passing to the intake portion l2. The increased velocity also increases the kinetic energy inthe gas and, by dissipating such energy as the gas approaches the intake portion I2, it will be partially obstructed in passing forwardly .through such intake portion. To dissipate the kinetic energy remaining in the gas at thisipoint, a transverse partition 22 .(see Figs. 1 and 2) is mounted in the rear end of thejintake portion 12 so that the spinning or :swirling movement of any forwardly moving gas will be abruptly stopped by the partition 22. Thus, forward movement of the ,gas :will ,be hindered by :the energy of the-gas itself and no movin parts are required in the construction'toreduce the forward flow. The structure thus' eliminates the .dimculties heretofore encountered with a .flap .valve and provides a structure which is simple in character, with the vanes 16 as well as the transverse partition '22 utilized to controlthe gasas well-as to lend rigidity'to'the various parts.

vI claim:

1. Ina-jet pulse imitthe combinationincluding 'a body "structure "having an intake portion that converges inwardlyina downstream direction,-an intermediate portion'thatfirst diverges outwardly and then converges inwardly in a downstream direction, and a combustion chamber portion; 'a

transverse partition disposed-in the downstream tween said intermediate portion andsaidcone '.member substantiallyat the point of maximum diameter of the'intermediate portion; and a'fuel 4 burner disposed adjacent the downstream end of said cone member.

2. In a jet pulse unit the combination including a body structure having an intake portion that converges inwardly in a downstream direction, an intermediate portion having a section that diverges outwardly and a downstream section that converges inwardly, and a combustion chamber portion; a transverse partition disposed in the downstream end of the air intake portion of said 'body; an inner cone member generally concentrically disposed within said intermediate portion, said cone member being tapered toward both ends and being smaller than said intermediate portion whereby to provide an annular passage therearound, the tapered front end of said cone diverging outwardly at a faster rate than the diverging section of said intermediate portion, and the downstream taper of said cone member converging inwardly at a faster rate than the converging section of said intermediate portion; a plurality of helically disposed supporting vanes for fixedly holding said cone member within said intermediate portion, said vanes fleeing fixed between said intermediate portion and said cone member substantially at the point of maximum diameter of the intermediate-portion; and a fuel burner disposed adjacent the downstream end of said cone member.

3. In a jet pulse unit the combination including a body structure having an intake portion that converges inwardly in a downstream direction, an intermediate portion that first diverges outwardly and then converges inwardly in a downstream direction, and a combustion chamber portion; a transverse partitiomdisposed in the downstream end of the air intake portion of said body; an inner cone member generally concentrically disposed within said intermediateportion, said cone member being tapered toward-bothends and being smaller than said intermediate portion whereby to provide an annular passage therearound; a plurality of helically disposed supporting vanes for fixedly holding said cone member within said intermediate portion, said vanes being fixed in overlapping but spaced relation between said intermediate portion and said cone member substantially at the point-of maximum diameter of the intermediate portion; and a fuel burner disposed at the. downstream endof saidcone -member.

GEORGE F. =WISLZICENUS.

file of this patent:

UNITED STATES- PATENTS Number Name Date 1,246,159 Ricardo et al. Nov. 13, 1917 1,329,559 Tesla Feb. -3, 1920 1,566,862 Halterman Dec, 22, 1925 2,007,080 Dintilhoc July :2, 1935 2,167,303 'Kadenacy j July 25, 1939 2,198,730 Kadenacy .Apr. 30, 1940 2,208,984 Jahn -July 23, 1940 2,427,845 Forsyth Sept. 23, 1947 2,575,682 Price Nov. .20, 21951 ,FQREIGN .PAIENTS Number IC-ountry :Date

386,908 IGreat Britain .Jan; 26; 1933 $12,478 France May '3; 1910 --6fl0',228 -'Germany -Dec.23, 1936 852,971 France Nov. 18, 1939

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