A method for suppressing ignition shock of a hydrogen-oxygen rocket engine thrust chamber

Abstract

The application discloses a method for inhibiting ignition impact of a hydrogen-oxygen rocket engine thrust chamber, and comprises the following steps: determining the opening time T of an oxygen main valve; determining the blowing flow Q when helium is used for blowing; determining the pressure P of a fuel storage tank; igniting: opening the fuel main valve, and controlling the fuel storage tank to inject liquid hydrogen at the pressure P; the liquid hydrogen enters the inner cavity of the thrust chamber after passing through the fuel main valve, a cooling jacket and a fuel head cavity; after a time T-0.1s, the thrust chamber igniter is ignited; after another 0.1s, the oxygen main valve is opened, and liquid oxygen enters the inner cavity of the thrust chamber after passing through an oxygen inlet, the oxygen main valve and an oxidant head cavity; when the fuel and the oxidant in the inner cavity of the thrust chamber reach an ignition mixing ratio, the thrust chamber is ignited under the action of the thrust chamber igniter; the blowing valve is opened when the fuel main valve is opened, and is closed when the oxygen main valve is opened, and the helium flow is controlled as Q. The application aims to reduce the pressure peak generated at the ignition moment of the hydrogen-oxygen engine thrust chamber, and ensure the safety of the thrust chamber and the engine structure.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of aerospace technology, and particularly relates to a method for suppressing ignition impact of a hydrogen-oxygen rocket engine thrust chamber. BACKGROUND

[0002] A liquid rocket engine generates thrust by high-speed ejection of fuel and oxidizer after combustion in a thrust chamber, so that ignition of the thrust chamber is a key link in the starting process of the liquid rocket engine and directly determines whether the engine can enter a normal working state.

[0003] In order to avoid damage caused by a violent reaction between the metal of the inner wall of the thrust chamber and oxygen in a high-temperature oxygen-rich environment, a hydrogen-rich ignition method is generally used for a high-thrust hydrogen-oxygen engine thrust chamber, that is, hydrogen enters the thrust chamber first, and then oxygen enters for ignition. However, since a certain amount of hydrogen has been accumulated in the thrust chamber when the oxygen enters, and the thrust chamber is a relatively closed space, a pressure impact will be generated at the moment of ignition, which has an adverse effect on the structure of the thrust chamber and other components of the engine. If the pressure impact at the moment of ignition is too high, it may even cause structural damage to the engine. Therefore, for a hydrogen-oxygen engine using hydrogen-rich ignition, the ignition pressure impact of the thrust chamber at the start must be controlled. SUMMARY

[0004] The present application solves the technical problem: overcoming the shortcomings of the prior art, providing a method for suppressing ignition impact of a hydrogen-oxygen rocket engine thrust chamber, aiming to reduce the pressure peak generated at the moment of ignition of the hydrogen-oxygen engine thrust chamber and ensure the safety of the structure of the thrust chamber and the engine.

[0005] In order to solve the above technical problem, the present application discloses a method for suppressing ignition impact of a hydrogen-oxygen rocket engine thrust chamber, comprising:

[0006] Step 1, determining the opening time T of the oxygen main valve;

[0007] Step 2, determining the blowing flow rate Q of the fuel head cavity when helium is used for blowing;

[0008] Step 3, determining the pressure P of the fuel tank; wherein the fuel tank stores liquid hydrogen;

[0009] Step 4, ignition: open the fuel main valve, control the fuel tank to inject liquid hydrogen into the fuel inlet at a pressure P; the liquid hydrogen enters the cooling jacket through the fuel inlet and the fuel main valve, is pre-cooled in the cooling jacket, then enters the fuel head cavity, and then enters the thrust chamber inner cavity through the hydrogen nozzle; after a time T-0.1s, the thrust chamber igniter is ignited; after another 0.1s, the oxygen main valve is opened, and the liquid oxygen enters the oxidizer head cavity through the oxygen inlet and the oxygen main valve, and then enters the thrust chamber inner cavity through the oxygen nozzle; when the fuel and the oxidizer in the thrust chamber inner cavity reach the ignition mixing ratio, the thrust chamber completes ignition under the action of the thrust chamber igniter; wherein, the blowdown valve is opened at the same time as the fuel main valve, and the helium blowdown device blows helium into the helium inlet at a blowdown flow rate Q, and the helium enters the fuel head cavity through the blowdown valve to blow off the fuel head cavity; the blowdown valve is closed at the same time as the oxygen main valve.

[0010] In the method for suppressing ignition shock of a hydrogen-oxygen rocket engine thrust chamber, the time T is an average value of the time from when the fuel enters the cooling jacket to when the pressure of the fuel head cavity exceeds 0.15 MPa and the temperature of the fuel head cavity is lower than 150 K, which is measured through multiple tests.

[0011] In the method for suppressing ignition shock of a hydrogen-oxygen rocket engine thrust chamber, the time T is determined as follows:

[0012] Through multiple tests, the time T1 is determined as follows: the fuel main valve is opened, the liquid hydrogen enters the cooling jacket through the fuel inlet and the fuel main valve, and the pressure of the fuel head cavity is measured at the same time, and the time from when the fuel main valve is opened to when the pressure of the fuel head cavity exceeds 0.15 MPa is recorded; multiple tests are carried out to obtain a first time envelope, and the average value thereof is obtained and denoted as T1.

[0013] Through multiple tests, the time T2 is determined as follows: the fuel main valve is opened, the liquid hydrogen enters the cooling jacket through the fuel inlet and the fuel main valve, and the temperature of the fuel head cavity is measured at the same time, and the time from when the fuel main valve is opened to when the temperature of the fuel head cavity decreases to 150 K is recorded; multiple tests are carried out to obtain a second time envelope, and the average value thereof is obtained and denoted as T2.

[0014] According to the comparison result of T1 and T2, T is determined as follows: when T1>T2, T=T1; when T1

[0015] In the method for suppressing ignition shock of a hydrogen-oxygen rocket engine thrust chamber, the blowdown flow rate Q is determined as follows:

[0016] Determine the blowing flow rate Q through multiple tests: use helium to blow the fuel head cavity, record the pressure of the fuel head cavity corresponding to different blowing flow rates, and determine the blowing flow rate corresponding to the pressure of the fuel head cavity reaching 0.2 MPa; carry out multiple tests to obtain several blowing flow rates capable of making the pressure of the fuel head cavity reach 0.2 MPa, and obtain the average value, denoted as Q.

[0017] In the method for suppressing ignition impact of a hydrogen-oxygen rocket engine thrust chamber, when the pressure of the fuel tank is P, the pressure at the fuel inlet can be ensured to be the sum of the saturated vapor pressure of liquid hydrogen and the positive net suction pressure of the pump, so as to reduce the ignition impact.

[0018] In the method for suppressing ignition impact of a hydrogen-oxygen rocket engine thrust chamber, the pressure of the fuel tank + the liquid column pressure of the delivery system = the pressure at the fuel inlet.

[0019] In the method for suppressing ignition impact of a hydrogen-oxygen rocket engine thrust chamber, the pressure P is determined as follows:

[0020] Determine the pressure P through multiple tests: open the fuel main valve, control the fuel tank to inject liquid hydrogen into the fuel inlet at different pressures, and record the pressure at the fuel inlet at the same time, and determine the pressure of the fuel tank corresponding to the pressure at the fuel inlet being equal to the sum of the saturated vapor pressure of liquid hydrogen and the positive net suction pressure of the pump; carry out multiple tests to obtain several fuel tank pressures capable of making the pressure at the fuel inlet equal to the sum of the saturated vapor pressure of liquid hydrogen and the positive net suction pressure of the pump, and obtain the average value, denoted as P.

[0021] In the method for suppressing ignition impact of a hydrogen-oxygen rocket engine thrust chamber, the engine thrust chamber comprises: a fuel main valve, a cooling jacket, a fuel head cavity, an oxidizer head cavity, an oxygen main valve, a thrust chamber inner cavity and a blowing valve;

[0022] The fuel head cavity and the oxidizer head cavity are located at the head of the thrust chamber inner cavity;

[0023] The cooling jacket is located outside the thrust chamber inner cavity;

[0024] The fuel main valve is arranged at the inlet of the cooling jacket, the outlet of the cooling jacket is connected to the fuel head cavity, and the blowing valve is arranged on the connecting pipeline between the fuel main valve and the inlet of the cooling jacket;

[0025] The oxygen main valve is arranged at the inlet of the oxidizer head cavity.

[0026] The present application has the following advantages:

[0027] (1) The application discloses a method for inhibiting ignition impact of a hydrogen-oxygen rocket engine thrust chamber. The method is characterized in that the opening time interval of a liquid rocket engine fuel main valve and an oxygen main valve is controlled, the blowing flow of high-pressure helium in a fuel head cavity is set, and the fuel tank pressure is reduced, so that the fuel accumulation in the thrust chamber cavity at the ignition moment is reduced, the ignition pressure impact of the engine thrust chamber in the starting process is inhibited, and the safety of the engine structure is protected.

[0028] (2) The application discloses a method for inhibiting ignition impact of a hydrogen-oxygen rocket engine thrust chamber. The method can be applied to low-temperature liquid rocket engines including hydrogen-oxygen engines and liquid oxygen / methane engines, and can be popularized and applied to all liquid rocket engines adopting the hydrogen-rich ignition scheme of the thrust chamber. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is a structural schematic diagram of an engine thrust chamber in the embodiment of the application;

[0030] Figure 2 is a step flow chart of the method for inhibiting ignition impact of a hydrogen-oxygen rocket engine thrust chamber in the embodiment of the application;

[0031] Figure 3 is a principle diagram of the method for inhibiting ignition pressure impact of the thrust chamber in the embodiment of the application. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical scheme and advantages of the application clearer, the following will further describe the disclosed embodiments of the application in combination with the drawings.

[0033] In the embodiment, a method for inhibiting ignition impact of a hydrogen-oxygen rocket engine thrust chamber is disclosed. The method is mainly aimed at an engine thrust chamber as shown in Figure 1 . As shown in Figure 1 , the engine thrust chamber comprises a fuel main valve 2, a cooling jacket 3, a fuel head cavity 4, an oxidant head cavity 5, an oxygen main valve 6, a thrust chamber cavity 8 and a blowing valve 9. The fuel head cavity 4 and the oxidant head cavity 5 are located at the head of the thrust chamber cavity 8; the cooling jacket 3 is located outside the thrust chamber cavity 8; the fuel main valve 2 is arranged at the inlet of the cooling jacket 3, and the outlet of the cooling jacket 3 is connected to the fuel head cavity 4; the blowing valve 9 is arranged on the connecting pipeline between the fuel main valve 2 and the inlet of the cooling jacket 3; and the oxygen main valve 6 is arranged at the inlet of the oxidant head cavity 5.

[0034] In the embodiment, the method for inhibiting ignition impact of a hydrogen-oxygen rocket engine thrust chamber comprises the following steps: Figure 1

[0035] Step 1: determining the opening time T of the oxygen main valve 6.

[0036] ​In the embodiment, the time T refers to the average of the time measured by multiple tests from the time when the fuel enters the cooling jacket 3 to the time when the pressure of the fuel head cavity 4 exceeds 0.15 MPa and the temperature is lower than 150 K.

[0037] Preferably, the time T is determined as follows: by conducting multiple tests, the time T1 is determined: the fuel main valve 2 is opened, the liquid hydrogen enters the cooling jacket 3 through the fuel inlet 1 and the fuel main valve 2, and the pressure of the fuel head cavity 4 is measured at the same time, and the time from the opening of the fuel main valve 2 to the time when the pressure of the fuel head cavity 4 exceeds 0.15 MPa is recorded; multiple tests are conducted to obtain a first time envelope, and the average value thereof is obtained and recorded as T1. By conducting multiple tests, the time T2 is determined: the fuel main valve 2 is opened, the liquid hydrogen enters the cooling jacket 3 through the fuel inlet 1 and the fuel main valve 2, and the temperature of the fuel head cavity 4 is measured at the same time, and the time from the opening of the fuel main valve 2 to the time when the temperature of the fuel head cavity 4 decreases to 150 K is recorded; multiple tests are conducted to obtain a second time envelope, and the average value thereof is obtained and recorded as T2. According to the comparison result of T1 and T2, T is determined: when T1 > T2, T = T1; when T1 < T2, T = T2; when T1 = T2, T = T1 = T2.

[0038] It can be seen that the basic principle of setting the time T is that the time interval between the opening of the oxygen main valve and the fuel main valve cannot be less than MAXT1,T2, and the temperature of the fuel head cavity has begun to decrease approximately linearly. In this way, the cooling jacket has been cooled to a certain extent when the liquid oxygen enters the inner cavity of the thrust chamber, and the fuel storage in the inner cavity of the thrust chamber is as little as possible.

[0039] Step 2, determine the blow-off flow rate Q when helium is used to blow off the fuel head cavity 4.

[0040] In the embodiment, the blow-off flow rate Q is determined as follows: by conducting multiple tests, the blow-off flow rate Q is determined: the fuel head cavity 4 is blown off with helium, and the corresponding pressure of the fuel head cavity 4 is recorded when different blow-off flow rates are used, and the blow-off flow rate corresponding to the pressure of the fuel head cavity 4 reaching 0.2 MPa is determined; multiple tests are conducted to obtain a plurality of blow-off flow rates that can make the pressure of the fuel head cavity 4 reach 0.2 MPa, and the average value thereof is obtained and recorded as Q.

[0041] Preferably, after the fuel main valve is opened, high-pressure helium is used to blow off the fuel head cavity, which can discharge as much fuel as possible that enters the inner cavity of the thrust chamber in advance, thereby reducing the storage; the oxygen main valve is opened, and the blow-off is stopped.

[0042] Step 3, determine the pressure P of the fuel tank.

[0043] In the embodiment, when the pressure of the fuel tank is P, the pressure at the fuel inlet 1 can be ensured to be the sum of the liquid hydrogen saturated vapor pressure and the pump positive net suction pressure, so as to reduce the ignition impact.

[0044] Preferably, based on the principle that the pressure of the fuel tank + the pressure of the delivery system = the pressure at the fuel inlet 1, the pressure P can be determined by the following method: by conducting multiple tests, opening the fuel main valve 2, controlling the fuel tank to inject liquid hydrogen at different pressures to the fuel inlet 1, and recording the pressure at the fuel inlet 1, to determine the pressure of the fuel tank that can make the pressure at the fuel inlet 1 equal to the sum of the saturated vapor pressure of liquid hydrogen and the positive net suction pressure of the pump; conduct multiple tests to obtain several fuel tank pressures that can make the pressure at the fuel inlet 1 equal to the sum of the saturated vapor pressure of liquid hydrogen and the positive net suction pressure of the pump, and obtain the average value, denoted as P.

[0045] Preferably, the pressure P is set mainly to control the pressure of the fuel tank at start-up, to make the pressure of the fuel tank as low as possible under the premise of ensuring that the pump will not be in a cavitation state, and to slow down the filling speed of the fuel in the thrust chamber cavity.

[0046] It should be noted that the time T, the purge flow rate Q and the pressure P are all measured and calculated through multiple tests. The fuel stored in the fuel tank can be, but is not limited to, liquid hydrogen, methane and other low-temperature liquid fuels.

[0047] Step 4, ignition: open the fuel main valve 2, control the fuel tank to inject liquid hydrogen at pressure P to the fuel inlet 1; the liquid hydrogen enters the cooling jacket 3 through the fuel inlet 1 and the fuel main valve 2, is pre-cooled in the cooling jacket 3, then enters the fuel head cavity 4, and then enters the thrust chamber cavity 8 through the hydrogen nozzle; after a time T-0.1s, the thrust chamber igniter ignites; after another 0.1s, the oxygen main valve 6 is opened, the liquid oxygen enters the oxidant head cavity 5 through the oxygen inlet 7 and the oxygen main valve 6, and then enters the thrust chamber cavity 8 through the oxygen nozzle; when the fuel and the oxidant in the thrust chamber cavity 8 reach the ignition mixing ratio, the thrust chamber completes ignition under the action of the thrust chamber igniter. At the same time of opening the fuel main valve 2, the purge valve 9 is opened, and the helium purge device blows helium into the helium inlet 10 at a purge flow rate Q, and the helium enters the fuel head cavity 4 after passing through the purge valve 9, realizing the purge of the fuel head cavity 4; at the same time of opening the oxygen main valve 6, the purge valve 9 is closed.

[0048] Based on the above embodiment, the following describes a certain type of engine for suppressing ignition impact.

[0049] As Figure 3As shown, first, for a certain type of engine that needs to suppress the ignition impact, the filling test of the cooling jacket and the fuel head cavity is carried out. The fuel inlet pressure is ensured to be the design value, the fuel main valve is opened, and the cooling jacket and the fuel head cavity are filled under the action of the inlet pressure, and the time from the opening of the fuel main valve to the pressure rise of the fuel head cavity to 0.15MPa is recorded. After multiple tests, the envelope range of the interval time can be obtained, and on this basis, the opening time of the oxygen main valve can be obtained by considering the action response time of the oxygen main valve. In addition, according to the fuel filling time and the opening time of the oxygen main valve, the start and stop time of the high-pressure helium blowing can be determined, that is, the blowing starts from the fuel entering the fuel head cavity, and the blowing stops after the oxygen main valve is opened, so as to promote the part of the fuel entering the thrust chamber cavity before the oxidant to be discharged from the thrust chamber cavity, and reduce the fuel accumulation in the thrust chamber cavity. In addition, when the liquid rocket engine starts, pressure drop will occur in front of the pump, that is, negative water hammer phenomenon. When the pressure is lower than the saturated vapor pressure of the propellant, the pump will produce cavitation, which endangers the safe operation of the engine. Therefore, it is necessary to ensure that the fuel inlet pressure is higher than the sum of the saturated vapor pressure of the propellant and the negative water hammer amplitude during engine starting. Under the above premise, the fuel tank pressure is reduced, so that the fuel entering before the thrust chamber ignites is as little as possible, and the pressure impact at the ignition time is reduced.

[0050] Although the present application has been disclosed with the above preferred embodiments, it is not intended to limit the present application, and any person skilled in the art can make possible changes and modifications to the technical solutions of the present application by using the disclosed methods and technical contents without departing from the spirit and scope of the present application. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application, which does not deviate from the technical solutions of the present application, belongs to the protection scope of the technical solutions of the present application.

[0051] The contents not described in detail in the specification of the present application belong to the known technology of the person skilled in the art.

Claims

1. A method of suppressing ignition kick of a hydrogen-oxygen rocket engine thrust chamber, characterized by, Comprising: Step 1, determining the opening time T of the oxygen main valve (6); Step 2, determining the blow-off flow rate Q when the fuel head cavity (4) is blown off with helium; Step 3, determining the pressure P of the fuel tank, wherein the fuel tank stores liquid hydrogen; Step 4, ignition: open the fuel main valve (2), control the fuel tank to inject liquid hydrogen into the fuel inlet (1) at the pressure P; the liquid hydrogen enters the cooling jacket (3) through the fuel inlet (1) and the fuel main valve (2), is pre-cooled in the cooling jacket (3), then enters the fuel head cavity (4), and then enters the thrust chamber inner cavity (8) through the hydrogen nozzle; after a time T-0.1s, the thrust chamber igniter ignites; after another 0.1s, the oxygen main valve (6) is opened, and the liquid oxygen enters the oxidant head cavity (5) through the oxygen inlet (7) and the oxygen main valve (6), and then enters the thrust chamber inner cavity (8) through the oxygen nozzle; when the fuel and the oxidant in the thrust chamber inner cavity (8) reach the ignition mixing ratio, the thrust chamber completes ignition under the action of the thrust chamber igniter; wherein the blow-off valve (9) is opened at the same time as the fuel main valve (2) is opened, the helium blow-off device blows helium into the helium inlet (10) at the blow-off flow rate Q, and the helium enters the fuel head cavity (4) after passing through the blow-off valve (9), thereby blowing off the fuel head cavity (4); the blow-off valve (9) is closed at the same time as the oxygen main valve (6) is opened; The pressure of the fuel tank + the liquid column pressure of the delivery system = the pressure at the fuel inlet (1); when the pressure of the fuel tank is P, the pressure at the fuel inlet (1) can be ensured to be the sum of the saturated vapor pressure of liquid hydrogen and the positive net suction pressure of the pump, so as to reduce the ignition impact; the determination method of the pressure P is as follows: through multiple tests, the pressure P is determined: the fuel main valve (2) is opened, the fuel tank is controlled to inject liquid hydrogen into the fuel inlet (1) at different pressures, and the pressure at the fuel inlet (1) is recorded at the same time, so as to determine the fuel tank pressure corresponding to the pressure at the fuel inlet (1) being equal to the sum of the saturated vapor pressure of liquid hydrogen and the positive net suction pressure of the pump; multiple tests are carried out to obtain several fuel tank pressures corresponding to the pressure at the fuel inlet (1) being equal to the sum of the saturated vapor pressure of liquid hydrogen and the positive net suction pressure of the pump, and the average value is obtained, which is denoted as P.

2. The method of suppressing ignition kick of a hydrogen-oxygen rocket engine thrust chamber according to claim 1, characterized by, The time T refers to the average value of the time measured through multiple tests from the beginning of the fuel entering the cooling jacket (3) to the pressure of the fuel head cavity (4) exceeding 0.15MPa and the temperature being lower than 150K.

3. The method of suppressing ignition kick of a hydrogen-oxygen rocket engine thrust chamber according to claim 1, wherein The determination method of the time T is as follows: Through multiple tests, the time T1 is determined: the fuel main valve (2) is opened, the liquid hydrogen enters the cooling jacket (3) through the fuel inlet (1) and the fuel main valve (2), and the pressure of the fuel head cavity (4) is measured at the same time, and the time from the opening of the fuel main valve (2) to the pressure of the fuel head cavity (4) exceeding 0.15MPa is recorded; multiple tests are carried out to obtain a first time envelope, and the average value is obtained, which is denoted as T1; Determination of time T2: open the fuel main valve (2), liquid hydrogen enters the cooling jacket (3) through the fuel inlet (1) and the fuel main valve (2), and the temperature of the fuel head cavity (4) is measured at the same time. The time from the opening of the fuel main valve (2) to the reduction to 150K is recorded. Multiple tests are carried out to obtain a second time envelope, and the average value is obtained, denoted as T2. According to the comparison result of T1 and T2, T is determined: when T1>T2, T=T1; when T1 4. The method of suppressing ignition kick of a hydrogen-oxygen rocket engine thrust chamber of claim 1, wherein The determination method of blow flow Q is as follows: Determination of blow flow Q: the fuel head cavity (4) is blown by helium, and the corresponding pressure of the fuel head cavity (4) is recorded when different blow flows are used, and the blow flow corresponding to the pressure of the fuel head cavity (4) reaching 0.2MPa is determined. Multiple tests are carried out to obtain several blow flows that can make the pressure of the fuel head cavity (4) reach 0.2MPa, and the average value is obtained, denoted as Q.

5. The method of suppressing ignition kick of a hydrogen-oxygen rocket engine thrust chamber of claim 1, wherein Engine thrust chamber, comprising: fuel main valve (2), cooling jacket (3), fuel head cavity (4), oxidant head cavity (5), oxygen main valve (6), thrust chamber cavity (8) and blow valve (9); The fuel head cavity (4) and the oxidant head cavity (5) are located at the head of the thrust chamber cavity (8); The cooling jacket (3) is located outside the thrust chamber cavity (8); The fuel main valve (2) is arranged at the inlet of the cooling jacket (3), and the outlet of the cooling jacket (3) is connected with the fuel head cavity (4); the blow valve (9) is arranged on the connecting pipeline between the fuel main valve (2) and the inlet of the cooling jacket (3); The oxygen main valve (6) is arranged at the inlet of the oxidant head cavity (5).

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