Method for controlling the inlet pressure of cryogenic propellant engine tests based on flight profiles

Abstract

This invention discloses a flight profile-based inlet pressure control method for cryogenic propellant engine tests. It solves the technical problem that during the "tilted" pressure boosting process, the nitrogen gas temperature drops after heat exchange with the cryogenic propellant medium upon entering the container, causing the engine inlet pressure to fail to meet actual requirements. The method includes the following steps: first, determining the pressure boosting time period and the initial and final engine inlet pressure values; then, setting the pressure; and finally, controlling the engine inlet pressure according to the pressure control formula to complete the flight profile-based cryogenic propellant engine test inlet pressure control.

Description

Technical Field

[0001] This invention relates to a method for controlling the inlet pressure of a rocket engine during ground testing, specifically a method for controlling the inlet pressure of a cryogenic propellant engine based on flight profiles. Background Technology

[0002] During the test of a liquid rocket engine (hereinafter referred to as the engine), in order to simulate the pressure change of the propellant entering the engine inlet (hereinafter referred to as "inlet pressure") caused by changes in flight status and operating conditions during the engine's flight, the propellant supply system of the test stand must use a pressurization control system based on the engine's flight profile to control the inlet pressure within the required range.

[0003] Based on the engine characteristics and the flow resistance characteristics of the propellant supply system, manual adjustment calculations are performed. Then, based on these calculations, the size of the orifice matrix and the boosted nitrogen pressure are calculated. Before the test run, the container is pre-pressurized, and then pressurized again according to predetermined rules. This method is commonly referred to as the engine inlet pressure closed-loop control method based on an expert control system. Figure 1 As shown, the pressurization control system adopts a closed-loop control strategy. Container pressurization uses a "pressurization valve-pressurization orifice matrix" mode, where Pio is the engine inlet pressure and Pox is the container pressure. The pressurization control system controls the operation of the solenoid valves corresponding to different orifices on the pressurization orifice matrix 1 to introduce high-pressure nitrogen into the container, ultimately changing the Pio value by altering the Pox value. Based on the engine flight profile requirements, inlet pressure values ​​for all moments are preset. Nitrogen is pressurized into the propellant container through the pressurization orifice matrix 1. Finally, the instantaneous value of the engine inlet pressure Pio is detected in real time and fed back to the pressurization control system for comparison with the preset pressure value. The pressurization valve operation is adjusted to regulate the nitrogen pressurization gas flow rate, thereby ensuring the inlet pressure meets the engine flight profile requirements.

[0004] For controlling the increase in engine inlet pressure, existing technologies generally employ a "tilt-type" pressure deflection method. This method is typically suitable for ambient temperature propellant media (such as nitrogen tetroxide). However, for cryogenic propellant media (such as liquid oxygen), the nitrogen temperature decreases after entering the container due to heat exchange with the cryogenic propellant. The specific temperature decrease is estimated based on operational experience, but these estimates are often inaccurate during actual test runs. For engines using cryogenic propellant media, where the inlet pressure rises sharply during flight overload, a "tilt-type" pressure deflection method has been proposed to control the increase in engine inlet pressure based on actual flight requirements. However, due to the aforementioned reasons, accurate calculations are not possible, and this method may fail to meet actual requirements. Summary of the Invention

[0005] The purpose of this invention is to solve the technical problem that, during the pressurization process using the existing "tilt-type" pressure-pulling method, the nitrogen gas temperature drops after entering the container and exchanging heat with the cryogenic propellant medium, resulting in the engine inlet pressure failing to meet actual requirements. This invention provides a test inlet pressure control method for cryogenic propellant engines based on flight profiles.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for controlling the inlet pressure of a cryogenic propellant engine test based on flight profiles, employing a pressurization control system in a matrix pattern of pressurization valves and orifice plates; its unique feature lies in including the following steps:

[0008] Step 1: Obtain the engine to be tested and determine the required pressure pull-off time period for the test. to And the initial pressure value at the engine inlet during the pressure pull-off period. and end pressure value ,in, The initial time of the pressure pull-off period. The end time of the pressure pull-off period;

[0009] Step 2: Adjust the pressure for a specified time period. to The system is divided into N equal parts. The ending pressure value at the engine inlet in the (N-1)th time period is set to be equal to the initial pressure value at the engine inlet in the Nth time period, and both are... Where 3 ≤ N ≤ 6;

[0010] Step 3: Calculate the initial engine inlet pressure value for the first N-1 time periods. The final pressure value P at the engine inlet during the (N-1)th time period The pressure change values ​​are divided into N-1 parts, and the engine test inlet pressure is obtained according to the following formula. :

[0011] ;

[0012] in, Let A be a function of the engine inlet pressure versus time t, where A is the slope, b is the intercept, and t is... to Any moment within the time period;

[0013] Step 4: Based on the engine test inlet pressure obtained in Step 3 A pressurization control system based on a pressurization valve-pressurization orifice plate matrix mode was used to control the inlet pressure of the engine test, thus completing a method for controlling the inlet pressure of a cryogenic propellant engine test based on flight profiles.

[0014] Furthermore, N=4.

[0015] Furthermore, step 2 specifically involves:

[0016] Step 2.1: Adjust the pressure for a specified time period. to Divide into N equal parts;

[0017] Step 2.2: Based on the initial time of the pressure pull-off period. End time of the pressure pull-off period Initial pressure value at engine inlet and end pressure value Construct the initial pressure control formula ,in The initial slope, The initial intercept, ;

[0018] Step 2.3, according to Calculate the end pressure value of the initial (N-1)th time period. ;

[0019] Step 2.4: Set the engine inlet end pressure value for the (N-1)th time period and the engine inlet initial pressure value for the Nth time period to be... ,and .

[0020] Furthermore, in step 2.4, Where C is an empirical constant, and .

[0021] Furthermore, C takes the value 3.5.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] 1. This invention provides a method for controlling the inlet pressure of a cryogenic propellant engine test based on flight profiles. This method fully utilizes the pressurization capacity of existing test systems, effectively enhancing and improving their pressurization efficiency, thus saving costs and increasing work efficiency. Under the premise of an existing pressurization system, there is no need to replace the orifice plate or add an orifice plate matrix. It fully utilizes the pressurization capacity of the existing test system and allows for the setting of… Furthermore, the first N-1 time periods adopt a stepped pressurization method (i.e., instantaneous pressurization and pressure holding for a set time), while the last time period adopts a diagonal control method to meet the inlet pressure requirements of cryogenic propellants.

[0024] 2. The present invention provides a method for controlling the inlet pressure of a cryogenic propellant engine test based on flight profiles. By ensuring that the slope of the oblique line in the Nth time period is lower than the initial slope, the final pressurization effect is guaranteed, and the pressurization capacity of the existing pressurization system is fully utilized.

[0025] 3. This invention provides a cryogenic propellant engine test inlet pressure control method based on flight profiles. When an engine operates under high-performance conditions exceeding its rated operating conditions, performance parameters increase, but reliability decreases, potentially leading to risks such as propellant leakage or explosion. By employing a combination of stepped and inclined pressure control methods, the duration of the engine operating under high-performance conditions can be effectively controlled. This satisfies the engine's inlet pressure requirements while effectively controlling safety risks. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of a booster control system structure in the existing technology, which uses a booster valve-boost orifice plate matrix pattern.

[0027] Figure 2 This is a schematic diagram of pressure control using the existing "tilted" pressure pulling method;

[0028] Figure 3 This is a schematic diagram of the intersection of the "stepped" and "tilted" pressure deflection methods in step 2 of the embodiment of the cryogenic propellant engine test inlet pressure control method based on flight profile of the present invention.

[0029] Figure 4 This is a schematic diagram of the pressure control process in step 4 of an embodiment of the cryogenic propellant engine test inlet pressure control method based on flight profile of the present invention;

[0030] Figure 5 This is a schematic diagram of the actual engine inlet pressure detected during the test of an embodiment of the cryogenic propellant engine test inlet pressure control method based on flight profile of the present invention.

[0031] The attached diagram is labeled as follows: 1 - Pressure boosting orifice plate matrix. Detailed Implementation

[0032] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] A method for controlling the inlet pressure of a cryogenic propellant engine test based on flight profiles, employing a pressurization control system in a pressurization valve-pressurization orifice plate matrix pattern; including the following steps:

[0034] Step 1: Obtain the engine to be tested and determine the required pressure pull-off time period for the test. to And the initial pressure value at the engine inlet during the pressure pull-off period. and end pressure value ,in, The initial time of the pressure pull-off period. The end time of the pressure pull-off period;

[0035] Step 2: Adjust the pressure for a specified time period. to The system is divided into N equal parts. The ending pressure value at the engine inlet in the (N-1)th time period is set to be equal to the initial pressure value at the engine inlet in the Nth time period, and both are... Where 3≤N≤6; in this embodiment, N is 4, and the specific steps are as follows:

[0036] Step 2.1: Adjust the pressure for a specified time period. to Divide into N equal parts;

[0037] Step 2.2: Based on the initial time of the pressure pull-off period. End time of the pressure pull-off period Initial pressure value at engine inlet and end pressure value Construct the initial pressure control formula ,in The initial slope, The initial intercept, ;

[0038] Step 2.3, according to Calculate the end pressure value of the initial (N-1)th time period. ;

[0039] Step 2.4: Set the engine inlet end pressure value for the (N-1)th time period and the engine inlet initial pressure value for the Nth time period to be... ,and ,in, ,in In this embodiment, C is set to 3.5.

[0040] Step 3: Calculate the initial pressure value at the engine inlet for the first N-1 time periods. The final pressure value P at the engine inlet during the (N-1)th time period The pressure change values ​​are divided into N-1 parts, and the engine test inlet pressure is obtained according to the following formula. :

[0041] ;

[0042] in, Let A be a function of the engine inlet pressure as a function of time t, where A is the slope and b is the intercept.

[0043] Step 4: Based on the engine test inlet control pressure Pio(t) obtained in Step 3, the engine test inlet pressure is controlled by the booster control system based on the flight profile using the booster valve-boost orifice plate matrix mode, thus completing the method for controlling the test inlet pressure of a cryogenic propellant engine based on the flight profile.

[0044] The following is the design and control process of engine inlet pressure in a certain bottom surface test:

[0045] 1. Engine inlet pressure requirements

[0046] In a certain ground test, the requirements for the inlet pressure of the cryogenic propellant engine (hereinafter referred to as engine inlet pressure) were as follows: the inlet pressure requirement before start-up was 0.50 MPa, the pressure requirement after start-up was 0.45 MPa, the pressure began to rise after 60 seconds, reaching 1.0 MPa at 220 seconds, and then the pressure rapidly decreased. The pressure value before shutdown at 300 seconds was not less than 0.45 MPa. The pressure deviation period was from 60 seconds to 220 seconds.

[0047] like Figure 1 As shown, Pio is the engine inlet pressure. The boost gas source delivers boost gas to the air cushion part of the container through the closed-loop boost orifice plate matrix 1 (that is, the parallel valve orifice plate group), so that the container box pressure Pox is maintained or increased, and the engine inlet pressure Pio is adjusted according to the required value.

[0048] 2. Conventional inlet pressure deviation control method

[0049] like Figure 2 This design employs a conventional "tilted" pressure pull method for pressure control. From the graph, we can see that the pressure value is 0.45 MPa at 60 seconds and 1.0 MPa at 220 seconds, which is:

[0050] ;

[0051] ;

[0052] Easy to obtain Therefore, the oblique pressure control method can be expressed as:

[0053] ;

[0054] 3. Design a preliminary "stepped + inclined" pressure control method

[0055] like Figure 3 The pressure pull time period [60, 220] was divided into four equal parts. The first three parts adopted a "stepped" preliminary design and were compared and analyzed with the "diagonal" pressure pull method to form intersection points X1, X2, and X3. The pressure values ​​corresponding to the intersection points can be obtained using the formula... The calculated engine inlet pressure at the last intersection point X3 is:

[0056] ;

[0057] 4. The "stepped + inclined" pressure control method designed for application

[0058] satisfy and ,Can Set Value 0.9 and initial pressure value Calculate the difference, then further divide the difference into three equal parts. As a step value in a ladder-like manner, such as Figure 4 As shown.

[0059] By setting The value is 0.9 and the final pressure value. The slope A and intercept b of the slope can be obtained. From Figure 4 From this, we can obtain a pressure value of 0.9 MPa at 180s and a pressure value of 1.0 MPa at 220s, which means:

[0060] ;

[0061] ;

[0062] Easy to obtain Therefore, the oblique pressure control method can be expressed as: ;

[0063] Based on the above steps, a complete "stepped + inclined" pressure control method can be designed. A "stepped + inclined" pressure control method is designed. Further, the "stepped" method can be set to a 3-segment system, and the "inclined" method to a 1-segment system, ultimately resulting in the following formula:

[0064] ;

[0065] This pressure control method can increase the pressure to the required pressure value according to the time requirement. In the early stage of the test, the segmented step method is used to make full use of the existing pressurization capacity and make up for the problem of insufficient pressurization capacity in the later stage. At the same time, the oblique pressurization method is used in the later stage to effectively control the "dwell time" of the highest pressure value, ensuring that the engine does not stay in a high operating condition for a long time. It is also a way to keep basically consistent with the flight mission profile.

[0066] 5. Hot test run

[0067] Based on the specific pressure control method obtained from the above analysis, a "3-stage stepped + 1-stage inclined" pressure control method was adopted for hot commissioning.

[0068] like Figure 5 The pressure control method results in this embodiment are shown in the graph. It is clear from the graph that the engine inlet pressure reached 1.005 MPa at 220s, meeting the requirement of 1.0 MPa. Furthermore, the graph shows that the boost slope starting at 60s (calculated as 0.0116) is greater than the boost slope starting at 100s (calculated as 0.0087), and the boost slope starting at 100s is greater than the boost slope starting at 140s (calculated as 0.0061). This reflects that as the hot-running time progresses, the air cushion volume continuously increases, and the boost capacity gradually weakens. Therefore, the pressure control method of this invention can maximize the utilization of the boost system's working capacity. Simultaneously, it can be seen that the method of this invention can effectively control the duration of the engine operating at high pressure, that is, the duration when Pio is 1 MPa.

[0069] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present invention should be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for controlling the inlet pressure of a cryogenic propellant engine test based on flight profiles, employing a pressurization control system in a matrix pattern of pressurization valves and orifice plates; characterized in that, Includes the following steps: Step 1: Obtain the engine to be tested and determine the required pressure pull-off time period for the test. to And the initial pressure value at the engine inlet during the pressure pull-off period. and end pressure value ,in, The initial time of the pressure pull-off period. The end time of the pressure pull-off period; Step 2: Adjust the pressure for a specified time period. to The system is divided into N equal parts. The ending pressure value at the engine inlet in the (N-1)th time period is set to be equal to the initial pressure value at the engine inlet in the Nth time period, and both are... Where 3 ≤ N ≤ 6; Step 3: Calculate the initial pressure value at the engine inlet for the first N-1 time periods. The final pressure value P at the engine inlet during the (N-1)th time period The pressure change values ​​are divided into N-1 parts, and the engine test inlet pressure is obtained according to the following formula. : ； in, Let A be a function of the engine inlet pressure versus time t, where A is the slope, b is the intercept, and t is... to Any moment within the time period; Step 4: Based on the engine test inlet pressure obtained in Step 3 A pressurization control system based on a pressurization valve-pressurization orifice plate matrix mode was used to control the inlet pressure of the engine test, thus completing a method for controlling the inlet pressure of a cryogenic propellant engine test based on flight profiles.

2. The method for controlling the test inlet pressure of a cryogenic propellant engine based on flight profiles according to claim 1, characterized in that: N=4。 3. The method for controlling the inlet pressure of a cryogenic propellant engine based on flight profiles according to claim 1, characterized in that, Step 2 is as follows: Step 2.1: Adjust the pressure for a specified time period. to Divide into N equal parts; Step 2.2: Based on the initial time of the pressure pull-off period. End time of the pressure pull-off period Initial pressure value at engine inlet and end pressure value Construct the initial pressure control formula ,in The initial slope, The initial intercept, ; Step 2.3, according to Calculate the end pressure value of the initial (N-1)th time period. ; Step 2.4: Set the engine inlet end pressure value for the (N-1)th time period and the engine inlet initial pressure value for the Nth time period to be... ,and .

4. The inlet pressure control method for cryogenic propellant engine tests based on flight profiles according to claim 3, characterized in that: In step 2.4, Where C is an empirical constant, and .

5. The inlet pressure control method for cryogenic propellant engine tests based on flight profiles according to claim 4, characterized in that: The value of C is 3.5.

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