US3059429A - Reaction chamber - Google Patents

Description

Oct 23, 1962 J. w. BJERKLIE ETAL REACTION CHAMBER Filed March 25, 1958 Zafra. .L C

2 Sheets-Sheet l INVENTORJ'.

BY @Z4 m4;

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OC- 23, 1962 J. w. BJERKLIE ETAL REACTION CHAMBER 2 Sheets-Sheet 2 Filed March 25, 1958 1NVENTOR5.

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3,059,429 REAC'HN QHMBEQ .lohn W. Bjerklie, Sepuiveda, and Hunter H. lCover, Jr., Burbank, falif., assignors, by rncsne assignments, to Sunstrand Corporation, a corporation of Illinois Filed Mar. 25, i953, Ser. No. 723,859 7 Claims. (Ci. oli-39.46)

This invention relates -to reaction chambers and more particularly to the monopropellant fuels reaction chambers, which are also known as decomposition chambers since the reactions taking place in such chambers are primarily decomposition reactions.

There are a number of monopropellant fuels which are now in use, such as ethylene oxide, propyl nitrate, hydrazine, hydrogen peroxide and nitromethane. Fuels of this type are introduced into a decomposition charnber by means of spraying nozzles since all of the above fuels are liquids at room temperature. The decomposition chambers are provided with electrical heating elements which initiate the reaction by vaporizing and then decomposing the fuel. Upon decomposition, there may be an oxidation reaction, or burning of the fuel, the fuel itself supplying free oxygen for supporting the burning. The heated gases are then used as a working fluid in a gas turbine, such as Terry wheel turbine, the latter acting as a prime mover for an electric generator or a combination of an electric generator and a hydraulic pump. The entire combination of the above elements is known as auxiliary power units which supply electric and hydraulic power for such devices as guided missiles.

Effective operation of any decomposition, or reaction, chamber and proper utilization of fuel `are accomplished only when the following steps are performed in proper manner: injection of the fuel; vaporization of the fuel; initiation of the exothermic reaction; burning, or decomposition, of the fuel (if there is any burning); sustenance of operation; and, finally, optimum solution of the operating problems. Successful solution of the operating problems produces the following: lack of deposition of solids within the chamber; smooth operation f the chamber (steady pressure and constant rate of burning); minimum residence time for the injected fuel as a function of pressure; and reproducibility of the operating performance from chamber to chamber, i.e., obtaining of identical performance characteristics with the chambers of one type.

The injection of the fuel into the chamber, as a rule, does not present any difficult problems since all of the above mentioned fuels have reasonably low viscosities so as to attain proper atomization of fuel by means of the spray nozzles.

It is obvious that it is always desirable to vaporize the fuel as fully and as quickly as possible upon its entry into the decomposition chamber -because such rapid vaporization contributes to the rapid mixing of the fuel with the heated gases and initiation of the exothermic reaction. Rapid vaporization of fuel also has a direct effect on the initiation, burning and sustenance of the operation as well as obtaining of the optimum operating characteristics, such as smooth burning, minimum residence time, etc. The initial vaporization of the fuel is obtained by supplying suilicient amount of heat to the electrical heating elements and by proper positioning of these elements so that the injected fuel, upon its atomization, is furnished the necessary heat promptly and in suiiicient quantity to produce eifective Vaporization and subsequent ignition and burning as well as sustenance of reaction. No outstanding difficulties are encountered, as a rule, with the electrical heaters as long as they are properly positioned within the chamber and furnish a sufficient amount of heat 3,@5929 Patented Get. 23, 1952 energy. The main problem that is encountered with the heaters is that the initiation of the reaction should be obtained with a minimum amount of electrical energy supplied to the electrical heaters, and the solution of this problem usually is obtained through an empirical experimentation. Other means, such as pyrotechnic devices `and ante-chamber devices, may be used for providing initial starting, or ignition, but the basic considerations remain the same.

The sustenance of the operation,`which should also include the smooth operation of the chamber, is a much more difficult problem than what has been discussed already because it requires ya very eiicient, continuous, smooth and stable intermixing of the injected fuel with hot gases produced by the exotherrnic reaction; effective and continuous supply of heat to the atomized fuel when heat is supplied to the atomized fuel directly by the products of reaction, such Vas, hot gases, and the uid dynamic characteristics of the chamber must be such that the ame front remains stable, or geometrically fixed within the chamber even though there may be fluctuations in the velocity of the injected fuel. Supplying the necessary heat to the injected fuel by using the hot gases is the most effective and the most rapid mode of supplying the required heat. To date, it has -not been possible to supply heat in `such a manner to the injected fuel because the known chambers' did not have any effective way of stabilizing the flame front and obtaining smooth continuous inte-rmixing of the injected fuel with the heated gases. The disclosed chamber-the socalled vortex chamber-solves this problem by establishing a stable vortex of the circulating fuel and gases within the chamber, with the result that it is possible to obtain stable, smooth operation andsustenance of the reactions after the electric he-ater or heaters are disconnected. It is inherent in the physical characteristic of the vortex flow itself that it is not critically affected by the large fluctuations in the velocity of the fuel flow. Such large iluctuations in the flow velocity of the fuel may, to some extent, affect the velocity of the diffusion of the heated gases into the injected fuel and vice Versa, but it will not affect the position of the flame front since the latter is iixed in the vortex ow. Accordingly, with this type of supply ofthe necessary heat energy to the injected fuel, it is possible to attain high reproducibility of the operation from chamber to chamber las well as all other desired operating characteristics. For example, such a chamber produces an operation without any deposition of any solids within the chamber because the chamber is free of any localized hot spots. Moreover, the ow of gases is such that if there is any formation of solids which is inherent in the reaction itself, such formation of solids takes place within the gas -medium traveling at reasonably high velocity with the concomitant'high dispersion of such solids. Accordingly, with the minute solid particles and their wide distribution within the chamber, they can leave the chamber very readily without being deposited on the walls orY other members of the chamber.

It is also Very well known that it is desirable to provide as long a path of travel for the fuel within the chamber as possible, with a minimum of volume of the chamber.

Such long path is obtained within the vortex chamberV herently` capable of having stationary flame fronts and therefore it is extremely diflicult to obtain reproducible results from chamber to chamber and it is also difticult to obtain sustenance of the operation when there is a variation in pressure of "the injected -fuel and a marked vari'- ation in the external pressure. The variation in the external, or ambient, pressure,'as a rule, does not play an important role in the operation of theV chambers of the above type.

- There are also decomposition chambers and combustion chambers which use a return flow, or the return of hot, gases (the products of combustion) back to the region of the fuel-injecting nozzle, so that there is a rapid mixing between hot gases and the atomized fuel. Chambers of this type produce excellent results as long as the velocity of the fuel ow remains constant and therefore the flame front also remains fixed in its position within the chamber. However, such ilarne front position and the velocity of the recirculating gases are functions of the velocity of travel of gases through Vthe chamber and therefore it is impossible reliably to operate such chambers effectively over a Wide range of gas velocities.

One additional advantage of the chambers of this type resides in the fact that lthey can be very readily scaled up or down for obtaining the desired rate of how. Such scaling up or down of the chambers utilizing through flow Y or recirculating vflow is impossible to achieve because of the purely empirical nature of such chambers.

It is therefore an object of this invention to provide a vortex chamber in which one or a plurality of nozzles are so positioned with respect to the inner circular periphery of the chamber as to produce a vortex i'low of injected fuel and of the products of reaction, with the result that the chamberrhas a stationary llame front independentof the variations in the flow velocity.

It is an additional object of this invention to provide a vortex chamber which has a vortex flow of gases within the chamber with the concomitant rapid mixing between hot gases and atomized fuel, and effective supply of heat to the newly injected fuel by the products of combustion as well as obtainingl of a long path of travel for the fuel within a small Volume of the chamber.

The novel features which are believed to be characteristie of this invention, both as to its organization and methods of operation, together with further objects and advantages thereof, will be better understood from the following description given in connection with the accompanying drawings in which several embodiments ofthe invention are illustrated by way of several examples. It is to be understood, howeven'that the drawingsY are for the purpose of illustration only and .are not intended as a definition of the limits of the invention.

Referring to the drawings:

FIG. 1 is a vertical section of the chamber;

FIG. 2 is a horizontal sectional view of the chamberv taken along line 2 2 shown in FIG. 1;

FIG. 3 isa plan View of the chamber with the insulating cover in section;

FIG. 4 is a vertical side view of the fuel spray;

FIG. 5 is a horizontal view of the fuel spray;

FIG. 6 is a transverse section of the fuel spray taken along line 6--6 of FIG. 4;

FIG. 7 is a sectional view of a modified version of the chamber which has a plurality of individualV chamber cells and a corresponding plurality of injection nozzles;

FIG. 8 is a vertical sectional view of a single cell chamber having a plurality of injection nozzles; and l FIG. 9 is a vertical sectional view of a chamber in which the heater coils are positioned betweenthe inner lining and the outer shell of the chamber.

Referring to FIGS. l, 2 and 3, the chamber comprises a hollow right cylinder 10 whose two ends are closed off by two curved, disk-shaped side walls 11 `and 12, each provided with reinforcing ribs through 39. The

terial 41. A spray nozzle 14 is mounted on the cylinder wall V10, this nozzle being connected to a fuel tank (not shown) through a pipe, or tube, 16. The chamber is provided with an electric heater coil 17 which is connected to a source of electric current, not shown in any of the figures. The chamber may be also provided with an external heating coil 18 which surrounds wall 10 and is in direct metallic contact with wall 10. When coil 18 surrounds the entire circumference of cylinder 1d, then the central heater coil 17 may be eliminated altogether and the initial heating of the chamber is then obtained by heating coil 18 and wall 10 of the chamber. The heated gases leave Vthe chamber through a tube l provided with a De Laval nozzle 2n. Tube 19 is connected to side wall 12 in the manner indicated in FIG. 2, wall 12 having an orifice 21 within it. This orifice is positioned along the transverse, or the axisymmetric, axis 22 of the chamber. The fuel nozzle 14 is positioned in wall V10 in such manner that the longitudinal axis 23 of the nozzle makes an angle of approximately 40 to 50 with the' radius line 24 which passes through the axisymmetric axis 22 of the chamber. This angle, as indicated by a relatively wide range of its magnitude, is not a critical angle and its actual magnitude is determined by the desired dimension c (see FIG. 1) which indicates the distance between the tip of the nozzle and the intersection of wall 10 by the longitudinal axis 23 of the nozzle. This intersection point is indicated at 25 in FIG.

1. Dimension c is determined by the contemplated velocity of the injected fuel since wall 10 is a hot wall and the injected fuel should not impinge upon the inner surface of wall 10. In order to obtain as efficient a dispersion of fuel as possible, the shape of the fuel stream leaving nozzle 14 is of the fan-shaped type, as illustrated in FIGS. 4, 5 and 6.V FIG. 4 illustrates the vertical section of the fuel( stream, which indicates that the angle subtended by this stream may be of the order of from 5 to 10. The angle subtended in the horizontal plane is illustratedV in FIG. 5 and may be of the order of from 5070. It is also undesirable to encounter the conditions under which the injected fuel would impinge on the side walls 11 and 12 and therefore the horizontal angle illustrated in FIG. 5 would have such magnitude as to produce the* entry of the entire fuel into the gaseous vortex without the impingement upon the wall 1t) or the side walls 11 and 12.

As illustrated in FIGS. 1 through 3, the chamber may be provided with the external wall heater 18 aswell as theY internal wall heater 17. When very fast starting is desired, two heaters may be used. However, when the period of initial preheating for starting of the chamber need not be especially short, either one of the heaters can be eliminated. Also when the central heating coil 17 is used and the heat furnished by this coil is subtended by v.theheat furnished by the external coil 18, then the external coil 18 may extend throughout the 360 of the circular outer surface of cylindrical wall 10 or through some lesser portion of its circumference, depending upon the desired starting time.

yFIG. 7 illustrates a reaction chamber similar to that illustrated in the preceding FIGS. l through 6 except that in this case a plurality of reaction chambers are placed side by side to increase the rate of ow through the chamber. The chamber again includes a hollow cylindrical wall 700, two side walls 701 and 702 provided with reinforcements 703 and 704, external heaters 705, 706 and 707, and internal heater 708, disk-shaped baies 709 and 710, and an exhaust pipe 711 which has a plurality of orifices 712 for conveying hot gases from the three chambers 714', 715 and 716 which are placed side by side as illustrated in the drawing. The chambers also have three injection nozzles 717, 718` and 719, which are placed in the same manner as nozzle 14 in FIG. 1. The entire chamber is surrounded -by an insulation jacket 720. It is desirable to have baies 709 and 710 so as to isolate the individual vortexes from each other and thus avoid the creation of any fluid dynamic discontinuities along the boundary lines of the individual vortexes. The functioning of the chamber is identical to that illustrated in FIG. l and therefore it does not need any additional description.

FIG. 8 illustrates a reaction chamber which has a much larger specific weight flow than the chamber illustrated in FIG. 1. In this case, the chamber of FIG. l has been -scaled up by increasing the diameter of the hollow cylinder S00. In order to obtain an effective vortex within the large diameter hollow cylinder 800, four nozzles 801 through 804 are uniformly spaced around the periphery of cylinder 800. All of these four nozzles contribute equally to the creation and sustenance of the vortex within cylinder 800. The remaining elements of the chamber, such as insulation jacket 805, external heater 806 and internal heater 807, and an exhaust pipe 808 are identical to the corresponding elements in FIG. 1 and therefore need no additional description.

illustration of FIGS. 7 and 8 reveals the fact that the vortex combustion chamber can be scaled up or down, the scaled down version being illustrated in FIG. 1 and the scaled up versions being illustrated in FIGS. 7 and 8. In FIG. 7, the scaled up version merely multiplies the number of the miniature reaction chambers of the type illustrated in FIG. 1, while in FIG. 8 the scaled up version is obtained by enlarging the diameter of the cylindrical wall 10 and also by correspondingly enlarging the number of nozzles positioned around the periphery of the cylinder.

FIG. 9 differs from FIG. l only in one respect, namely, the outer cylinder 900 is the main structural wall of the chamber. The insulation layer 901 is positioned along the inner surface of wall 900 with the heater element 902 being surrounded by the insulation layer 901, except on that side which makes a direct metallic contact with the inner metallic lining 903 of the chamber. In order to increase the effectiveness of the heat transferred from the heater 902 to the lining 903, the heater Wires 902 may have a flattened portion 904 which makes a direct contact with the lining 903. It is obvious that the construction of this `type of chamber will have a more eicient heat transfer characteristic and will have less heat loss than the chamber illustrated in FIGS. l, 7 and 8. In other respects this chamber is identical to the previously described chambers and, therefore, needs no additional description. Nozzle 90S should project into the chamber sufficiently to introduce the fuel jet 906 in the manner described in connection with the previously described figures.

What is claimed as new is:

l. A vortex reaction chamber comprising a hollow cylinder and two end-walls closing off said cylinder, an injection nozzle, said nozzle being mounted within said cylinder for introducing fuel into said chamber in a fanshaped spray of 50 to 70 breadth and 5 to 15 thickness, with the major axis of the spray cross-section being parallel to the axisymmetric axis of the cylinder, and the center line of the spray forming an angle of 40 to 50 with the radius line extending from the axisymmetric axis to the point of injection of said fuel into said chamber, electric heater means associated with said chamber, and an exhaust pipe connected to one of the endwalls of said chamber, said pipe being coaxially positioned with respect to said axisymmetric axis.

2. The vortex chamber as defined in claim l which includes an inner metallic lining in spaced relationship with respect to said cylinder and said two end-walls, said heater means comprising a sinuous heater coil in metallic contact with said lining, and an insulation material stuffed into the spacing between the lining and the walls of said chamber.

3. The reaction chamber as defined in claim 1 in which said heater means includes a first heater element in metallic contact with said cylinder and a second heater element comprising a helical coil concentrically positioned with respect to said axisymmetric axis within said chamber.

4. A vortex chamber comprising a hollow, metallic cylinder, said cylinder comprising the cylindrically-shaped portion of the -outer wall of said chamber, two diskshaped end-wall members closing off said cylinder and completing the outer wall of said chamber, a plurality of fuel-injecting nozzles uniformly distributed around the periphery of said cylinder and having points of injection positioned substantially along the inner circumference of said cylinder, with the longitudinal axis of each spray produced by the nozzle being perpendicular to the axisymmetric axis of said chamber and forming a 40 to 50 angle with the radius line extending from the axisymmetric axis to the point of injection of said fuel, said nozzles having means for producing a spray having an elliptic cross-section of progressively increasing cross-sectional area, said spray subtending an angle of the order of 50 to 70 in the plane passing through the longitudinal and major cross-section axes of said spray, and said major cross-section axis being parallel to said axisymmetric axis of the chamber, and means defining an exhaust passage through an end wall member of said chamber, located substantially on said axisymmetric axis, the fuel spray establishing a vortex flow of fuel and combustion products away from the outer chamber wall, toward the axis of said chamber and out said exhaust passage.

5. A vortex chamber comprising a hollow cylinder having irst and second end portions, said first and second end portions being closed off by -lirst and second side-walls respectively, fuel injecting means mounted in said right cylinder, said fuel injection means being characterized to inject said fuel in the Iform of a diverging fan-shaped spray having a substantially elliptic crosssection of progressively increasing cross-sectional area as one travels from said means into said chamber, said spray subtending an angle inthe order of 50 to 70 in the plane passing through the longitudinal and major crosssection axes of said spray, said longitudinal axis being perpendicular to the axisymmetric axis of the chamber, and being displaced from said axisymmetric axis to the extent so that the radius line extending from the axisymmetric axis to the point of injection of said fuel yforms a 40 to 50 angle with said longitudinal axis, and means defining an exhaust passage through an end Wall member of said chamber, located substantially on said axisymmetric axis, the yfuel spray establishing a vortex iiow of fuel and combustion products away from the outer chamber wall, toward the axis of said chamber and out said exhaust passage.

6. A vortex reaction chamber comprising a hollow cylinder wall and two end-Walls closing off said cylinder wall, an injection nozzle having a longitudinal axis, said nozzle producing a fan-shaped diverging spray of fuel having an elliptic configuration of progressively increasing area extending away from said nozzle, the plane passing through the major axis of said ellipse being parallel to the axisymmetric axis of said chamber, and the plane passing through the minor axis of said ellipse being perpendicular to said axisymmetric axis and the radius line joining said axisymmetric axis with the apex of said fan-shaped spray and lying in said vertical plane forming a 40 to 50 angle with the longitudinal axis of said fanshaped spray, means delining an exhaust passage through an end wall member of said chamber, located substantially on said axisymmetric axis, the fuel spray establishing a vortex flow of fuel and combustion products away from the outer chamber Wall, toward the axis of said chamber and out said exhaust passage said spray entering the vortex produced by said spray within said cham- 3,059,429 7 8.; ber prior to its impingc-ment upon the inner surface of References Cited in thele of this patent said cylinder Wall. Y l I 7. A vortex reaction chamber having: a generally cylin- UNITED STATES PATENTS drical Wall and a pair of spaced end walls defining the 2,219,522 HDSCI f-" i OC- 29. boundaries of said chamber, said cylindrical Wall having 5 2,286,909 Goddard v 1; lune 16, 1942 an axis; a plurality of fuel spray nozzles spaced axially 2,633,943l Zwicky et al. i Jan. 6, 1948 along the wall edge having a discharge orifice adjacent 2,482,260 Goddard Sept. 20, 1949 said wall, the center line of the fuel spray from each noz- `2,574,495 Parker N0V 13, 1951 Zle forming an angle of the order of 45 with a radius 2,@4g317 Mikulasek Aug. 11, 1953 extending lfrom the axis of the cylindrical chamber Wall 10 2,654,997 Goddard Oct 13I 1953 to the discharge orilice; heater means associated with 2707 444 van Loon V May 3 1955 said chamber for establishing a reaction therein, the fue 2'749706 Goddard '"Euqe 12 1956 and reaction products moving in a vortex path towar the axis of the chamber; and an exhaust duct for eon- 2869321 Welch et al' Ian' 20 1959 ducting reaction products from said chamber, said duct 15 extending axially from end to end of the chamber and Y FOREIGN PATENTS away the reaction products from the center of the vortex.

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