RU2141052C1 - Combustion chamber of closed-loop liquid-propellant rocket engine - Google Patents

Abstract

FIELD: liquid-propellant rocket engines. SUBSTANCE: combustion chamber includes gas duct head with two bottoms and doublet gas-and-liquid injectors made in form of cylinder of lesser diameter located at inlet and projecting into gas duct and cylinder of larger diameter located at outlet. Central duct of injectors has two rows of tangential orifices for delivery of liquid component which is located in area where lesser diameter changes into larger diameter. Length of mixing chamber is equal to (1.4 to 1.5) of outlet diameter of injector nozzle. Central duct has form of diffuser immediately before tangential orifices. Provision is made in invention for protection of dependences of inlet and outlet diameters of diffuser and parts of injectors projecting into gas duct. EFFECT: enhanced economical efficiency and stability of engine operating process. 4 dwg

Description

 The invention relates to combustion chambers of liquid rocket engines of a closed circuit.

 Known combustion chamber of a liquid rocket engine J-2 company Rokitdaydn (USA), operating on components of hydrogen-oxygen fuel. The head of this chamber contains two-component nozzles, which supply liquid oxygen through the central channel and hydrogen through radial holes. Between the oxygen and hydrogen channels a cylindrical separation sleeve is made, cut off from the nozzle by a certain amount (JA Schelke Astronatics 1962, Vor 7, N 2, p. 41, 98. Collection of translations of articles published in the foreign press "Hydrogen rocket engines", TsIAM, Inv. 8942, 1963). However, due to small trimming, the separation sleeve prevents the components from mixing inside the nozzle and, therefore, a large length of the combustion chamber is required to ensure the required completeness of fuel combustion.

 Similar jet-centrifugal two-component nozzles were used in the combustion chamber of a closed-circuit SSME liquid rocket engine of the American company Rockidine for the Space Shuttle reusable space transport system (Levin V.R., Ilyin D.V., Lipatov I.N., Galankin E. M., American oxygen-hydrogen rocket engine Rockidine SSME, Proceedings of TsIAM, inv. 1018, 1982). In these nozzles, liquid oxygen is also supplied through the central channel and hydrogen-enriched generator gas is supplied through radial openings. To improve the mixing of fuel components inside the nozzle, the separation sleeve is cut to 6.1 mm with a mixing chamber diameter of 6.35 mm (l / d = 0.96).

 However, in such nozzles the efficiency of mixing the fuel components is insufficient due to the short length of their contact, the presence of a separation sleeve between the hydrogen gas blanket and a liquid stream of oxygen. In addition, the acoustic conductivity of the tangential holes is small and not regulated. The acoustic conductivity of the central channel of the nozzle is also small due to its small diameter and non-optimal length. Therefore, the design of the combustion chamber is complicated by anti-pulsation partitions and an acoustic absorber.

 The objective of the present invention is to increase the completeness of fuel combustion and high-frequency acoustic stability of the working process in a combustion chamber with two-component gas-liquid nozzles having a central channel for supplying a gaseous component and tangential openings for supplying a liquid component.

где D_к - диаметр камеры, n_ф - число форсунок.This problem was achieved in that two rows of tangential openings are located in the central channel of the nozzles at the place of transition of a smaller diameter to a larger one, the length of the displacement chamber l ₁ is equal to l ₁ = (1.4 ... 1.5) d ₁ , where d ₁ - nozzle outlet diameter. The Central channel directly in front of the tangential holes is made in the form of a diffuser (figure 2). The input diameter d _{3 of the} diffuser is assigned from the condition of ensuring the maximum total permeability of the nozzles in gas

where D _to - the diameter of the chamber, n _f - the number of nozzles.

и, следовательно, начальной толщине закрученной жидкой пелены. Выступающая в газовод часть форсунок выполнена длиной не менее 0,5 общей длины центрального канала. Общая длина центрального канала выбрана из условия обеспечения максимальной акустической проводимости.The output diameter d _{2 of the} diffusers is assigned from the condition of providing a step height equal to the diameter of the tangential holes

and, therefore, the initial thickness of the swirling liquid sheet. The nozzle part protruding into the gas duct is made at least 0.5 times the total length of the central channel. The total length of the central channel is selected from the condition of ensuring maximum acoustic conductivity.

The implementation of the length of the mixing chamber, equal to l ₁ = (1.4 ... 1.5) d ₁ , is selected according to experimental data. When l ₁ <1.4 d _{1, the} completeness of fuel combustion is significantly reduced (figure 3), when l ₁ > 1.5 d ₁ overheating of the nozzle nozzle begins. The two-row arrangement of tangential openings under conditions of open contact between the liquid sheet and the gas stream optimizes the twisting and mixing characteristics of the liquid component with the gaseous one. The first row of swirling jets of liquid is more exposed to the gas stream and mixes more with it, while maintaining the twist characteristics of the second row and the duration of contact of the swirling liquid with gas. Implementation of the diffuser in the central channel immediately before the tangential holes increases the length of the contact components inside the injectors at a constant ratio l ₁ / d ₁ and further improves the combustion efficiency of more than 0.5% (e.g., up to φ = 0.984 _pk instead 0.977). The presence of a step at the exit of the diffuser in front of the tangential openings also provides optimal characteristics of the swirling liquid sheet and thereby contributes to better mixing of the fuel components inside the nozzle and, consequently, to increase the completeness of fuel combustion.

 Performing the maximum permeability of the nozzles in the gas, optimizing the length of the central channel and the protrusions of the nozzle in the gas duct increase the transfer of wave energy from the combustion chamber to the gas duct, maximize the dissipation of wave energy and thereby increase the stability of the working process with respect to high-frequency acoustic vibrations. The influence of these factors is confirmed by full-scale experimental tests of engines.

In FIG. Figure 4 presents comparative experimental data on the amplitudes of pressure pulsations in the combustion chamber of a closed-circuit engine depending on the temperature of the generator gas at the inlet to the head for nozzles of length l / D _k = 0.13 and l / D _k = 0.23 with trimming of the separation sleeve on l ₁ / d ₁ = 0.66, 0.73 for l / D _k = 0.13 and for l ₁ / d ₁ = 0.98 for l / D _k = 0.23.

These data indicate that in a chamber with nozzles of a length that is not optimal in acoustic conductivity (l / D _k = 0.13), cutting the separation sleeve by l ₁ / d ₁ = 0.66 increases the amplitude of the pulsations when the temperature regime of the oxidizing gas increases from 200 ^o C to 400 ^o C 3 times, trimming by l ₁ / d ₁ = 0.73 - 6 times already at t _gas = 300 ^o C. With elongated nozzles (l / D _k = 0.23), protruding below the middle gazovode bottom in (l ₁ / d ₁ = 0.5), the amplitude of pulsation in the cell increased by only 1.7-fold even under the conditions with _{a gas} t = 540 ^o C. in nominal operation with _gas t = 300 ^o C elongation affectation approx with l / D = 0.13 to _a l / D = 0.23 _to reduced pulsation amplitude of more than 5 times (Figure 4).

In FIG. Figure 3 shows the experimental dependence of the increase in completeness of fuel combustion on the cutting of the separation sleeve with a cylindrical and diffuser channel in front of the tangential openings. From this figure it follows that trimming the separation sleeve to l ₁ / D ₁ = 0.5 does not affect the completeness of fuel combustion, a further increase in trimming to l ₁ / d ₁ = 1.46 increased the completeness of fuel combustion by 3%, the diffuser the central channel immediately in front of the tangential openings - another 0.5%.

 In FIG. 1 shows a combustion chamber.

 In FIG. 2 - the central channel of the nozzles.

In FIG. 3 - dependence of the completeness of combustion on the ratio l ₁ / d ₁ .

 In FIG. 4 - dependence of the amplitude of pressure pulsations on temperature.

Общая длина центрального канала форсунки выбрана из условия обеспечения максимальной акустической проводимости.A sketch of the proposed combustion chamber is shown in FIG. 2. The combustion chamber contains a gas duct 1, wall 2 and main 3 two-component nozzles, a middle bottom 4, a fire bottom 9. The central channel 5 is made with a diameter d ₃ at the inlet, has a diffuser 6 with an output diameter d ₂ and a mixing chamber 11 with tangential openings 7 At the junction of the diffuser 6 with the mixing chamber 11, a step 10 is made equal to the diameter of the tangential holes d _t . The main nozzles 3 protrude above the middle bottom 4 and the gas duct 1 to a length l _{3 of} at least 0.5 of the total length of the central channel. The length of the mixing chamber 11 is made of length l ₁ = (1.4 ... 1.5). The gas permeability of the nozzles, equal to the ratio of the total area of the central channels of the nozzle to the area of the combustion zone 11 of the chamber, is assigned by the condition:

The total length of the central channel of the nozzle is selected from the condition of ensuring maximum acoustic conductivity.

 Oxygen-rich generator gas flows from the gas duct 1 through the central channel 5 of the nozzles 3 and through the diffuser 6 into the mixing chamber 11, using the tangential holes 7 in the mixing chamber 11, the liquid component is twisted around the gas stream and mixed with it. The resulting mixture enters the combustion zone 8. The wave energy generated in the combustion zone is carried out through the central channels of 5 nozzles in the gas duct 1, where it dissipates between the 4 nozzles protruding above the middle bottom. The maximum removal of wave energy is provided by optimizing the length and diameter of the central channel to achieve maximum acoustic conductivity.

 The acoustic characteristics of a cylindrical pipe, and therefore of jet gas nozzles, are described in the work of A.G. Kukinov "One-dimensional flow oscillations in a cylindrical pipe", Transactions of TsAGI, issue 1231, M, ed. TsAGI department, 1970

 Thus, the use of the proposed combustion chamber will improve the efficiency and stability of the working process in liquid rocket engines of a closed circuit.

Claims (1)

The combustion chamber of a closed-circuit liquid-propellant rocket engine containing a gas duct, a head with two bottoms and two-component gas-liquid nozzles mounted in them, made in the form of sequentially arranged cylinders of a smaller diameter at the inlet protruding into the gas duct and larger at the outlet, characterized in that in the central channel nozzles at the transition point of a smaller diameter into a larger one are two rows of tangential holes with a diameter of d _t for feeding a liquid component, the mixing chamber is made of length l ₁ = (1.4 - 1.5) d ₁ where d ₁ is the outlet diameter of the nozzle of the nozzle, the central channel immediately in front of the tangential holes is made in the form of a diffuser, the input diameter of d _{3 of} which is assigned from the condition of ensuring the maximum total permeability of the nozzles in gas

where D _to - the diameter of the chamber;
n _f - the number of nozzles,
and the output diameter d ₂ - from the condition of ensuring the height of the steps equal to the diameter of the tangential holes

the nozzle part protruding into the gas duct has a length of at least 0.5 of the total length l of the central channel, which is selected from the condition of ensuring maximum acoustic conductivity.

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