Aircraft fuel pump low temperature test system and test method

Abstract

The application discloses a kind of aircraft fuel pump low temperature test system and test method, including buffer tank, circulating oil tank, first heat exchanger, circulating oil pump, refrigeration temperature control unit, fuel pump to be tested, second heat exchanger, self force type shunt valve;When the power of aircraft fuel pump is invariable or power change is relatively slow, can rely on refrigeration temperature control unit to control the fuel temperature in circulating oil tank, can greatly reduce the refrigeration power of refrigeration temperature control unit.When the power of aircraft fuel pump changes rapidly, by setting shunt valve on oil return pipeline, when temperature fluctuation exceeds the allowed range, let a part of fuel enter buffer tank via second pipeline after shunt valve, reduce temperature fluctuation.

Description

A cryogenic test system and test method for aircraft fuel pumps Technical Field

[0001] This invention relates to the field of aircraft hydraulic accessory testing, specifically to a low-temperature testing system and method for aircraft fuel pumps. Background Technology

[0002] Aircraft fuel pumps are critical aircraft components, and their environmental adaptability directly determines the applicability of the entire system. Among various environmental factors, the performance of aircraft hydraulic pumps is significantly affected by the temperature of the medium. Therefore, low-temperature testing is required during the design, finalization, and testing stages of hydraulic pumps. During low-temperature testing of aircraft fuel pumps, the inlet fuel temperature must be maintained stably at the temperature specified in the test outline. However, aircraft fuel pumps are mostly variable displacement pumps, and their power needs to be adjusted during operation. This power adjustment leads to changes in heat generation, posing a significant challenge to temperature control in the test system. Summary of the Invention

[0003] The purpose of this invention is to provide a low-temperature testing system and method for aircraft fuel pumps. When the aircraft fuel pump power remains constant or changes slowly, the fuel temperature in the circulating fuel tank can be controlled by a refrigeration and temperature control unit, which can greatly reduce the refrigeration power of the refrigeration and temperature control unit. When the aircraft fuel pump power changes rapidly, a diversion valve is installed on the return fuel line. When the temperature fluctuation exceeds the allowable range, a portion of the fuel is allowed to enter the buffer fuel tank through a second line after the diversion valve, thereby reducing the temperature fluctuation.

[0004] A cryogenic test system for an aircraft fuel pump includes a buffer tank, a circulating tank, a first heat exchanger, a circulating oil pump, a refrigeration and temperature control unit, a fuel pump to be tested, a second heat exchanger, and a self-regulating diverter valve.

[0005] The buffer oil tank is connected to the circulating oil tank through a first connecting pipe, and a first heat exchanger is also provided on the first connecting pipe. The refrigeration temperature control unit is connected to the first heat exchanger through a first refrigerant pipe. The second heat exchanger is connected to the refrigeration temperature control unit through a second refrigerant pipe, and the second heat exchanger is also connected to the first heat exchanger through a third refrigerant pipe. The two sides of the fuel pump to be tested are respectively connected to the second heat exchanger and the circulating oil tank.

[0006] The circulating oil tank is also connected to the buffer oil tank through the second connecting pipe and the third connecting pipe. The buffer oil tank is connected to the self-regulating diversion valve through the second pipe after the diversion valve. The self-regulating diversion valve is connected to the second heat exchanger and the circulating oil tank through the pipe before the diversion valve and the first pipe after the diversion valve.

[0007] Preferably, a second reversing valve is connected to the first connecting pipeline between the buffer oil tank and the first heat exchanger, and a first reversing valve and a circulating oil pump are respectively connected to the two branches connecting the first heat exchanger and the circulating oil tank.

[0008] Preferably, a fourth reversing valve and a fifth reversing valve are connected to the second and third connecting pipelines, respectively, and a third reversing valve is connected to the pipeline between the circulating oil tank and the fuel pump to be tested.

[0009] Preferably, the buffer tank is equipped with a first temperature sensor, the circulating tank is equipped with a second temperature sensor, the inlet end of the fuel pump to be tested is equipped with a third temperature sensor, and the pipeline before the diverter valve is equipped with a fourth temperature sensor, and the third and fourth temperature sensors are also connected to a temperature controller.

[0010] A test method applied to a cryogenic test system for an aircraft fuel pump includes a preparation phase and a formal test phase.

[0011] The preparation phase includes the following steps:

[0012] Step 1: Before the test begins, cool the fuel in the buffer tank and circulating tank to the specified temperature.

[0013] Step 2: The first, third, and fourth reversing valves are closed, and the second and fifth reversing valves are opened. After the circulating oil pump is turned on, the fuel in the circulating oil tank enters the first heat exchanger through the circulating oil pump. In the first heat exchanger, it exchanges heat with the refrigerant prepared by the refrigeration temperature control unit, and then enters the buffer oil tank through the second reversing valve. The oil in the buffer oil tank flows into the circulating oil tank through the third connecting pipe.

[0014] The formal test phase involves the temperature controller detecting the inlet fuel temperature of the fuel pump under test as measured by the third temperature sensor and the return fuel temperature as measured by the fourth temperature sensor, and the internal controller calculating the difference between the two temperatures.

[0015] When the difference between the two is less than ±0.5℃, the flow rate of the self-operated diverter valve to the second pipeline after the diverter valve is zero, and all fuel flows back to the circulating oil tank. The fuel temperature in the circulating oil tank is controlled by the refrigeration and heating temperature control unit.

[0016] When the difference between the two exceeds ±0.5℃, the opening of the self-regulating diverter valve is adjusted, so that the flow rate of fuel entering the buffer tank through the second pipeline after the diverter valve gradually increases, while the amount of fuel returning to the circulating tank decreases. This forces some fuel to flow from the buffer tank into the circulating tank through the third connecting pipeline, and the buffer tank begins to play a temperature buffering role, reducing the burden on the refrigeration temperature control unit.

[0017] The advantages of this invention are: 1. When the power of the aircraft fuel pump remains constant or changes slowly, the temperature of the fuel in the circulating fuel tank can be controlled by the refrigeration and temperature control unit. At this time, the fuel in the buffer tank does not participate in the circulation of the fuel circuit. Therefore, the fuel circuit cooling does not take into account the volume of the fuel tank, which can greatly reduce the cooling power of the refrigeration and temperature control unit.

[0018] 2. When the power of the aircraft fuel pump changes rapidly, a 20-diverter valve is installed on the return fuel line. When the temperature fluctuation exceeds the allowable range, a portion of the fuel is allowed to enter the buffer tank 1 via the second line after the 22-diverter valve. The large volume of the buffer tank reduces the temperature fluctuation. Attached Figure Description

[0019] Figure 1 is a schematic diagram of the system principle of the device of the present invention;

[0020] Figure 2 is a control logic diagram of the device of the present invention;

[0021] The components are as follows: 1. Buffer oil tank; 2. First temperature sensor; 3. First connecting pipeline; 4. Second temperature sensor; 5. Circulating oil tank; 6. First reversing valve; 7. Second reversing valve; 8. First heat exchanger; 9. Circulating oil pump; 10. First refrigerant pipeline; 11. Refrigeration temperature control unit; 12. Second refrigerant pipeline; 13. Third refrigerant pipeline; 14. Third reversing valve; 15. Third temperature sensor; 16. Fuel pump under test; 17. Second heat exchanger; 18. Fourth temperature sensor; 19. Pipeline before diverter valve; 20. Self-operated diverter valve; 21. First pipeline after diverter valve; 22. Second pipeline after diverter valve; 23. Second connecting pipeline; 24. Fourth reversing valve; 25. Third connecting pipeline; 26. Fifth reversing valve. Detailed Implementation

[0022] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0023] As shown in Figures 1 and 2,

[0024] The buffer oil tank 1 and the circulating oil tank 5 are connected by a first connecting pipe 3, a second connecting pipe 23, and a third connecting pipe 25.

[0025] Furthermore, the interface between the second connecting pipe 23 and the buffer fuel tank 1 is located at the upper part of the fuel tank, while the interfaces between the first connecting pipe 3 and the third connecting pipe 24 and the buffer fuel tank 1 are located at the lower part of the fuel tank. The fuel tank volume fully considers the performance characteristics of the fuel pump and allows for a certain margin. The buffer fuel tank 1 is installed at a relatively high position, and the circulating fuel tank 5 is at a relatively low position. This ensures that the parts involved in the circulation process are full of fuel throughout the entire test.

[0026] Furthermore, during the test, the buffer oil tank 1, the circulating oil tank 5, and the pipelines were all covered with insulation material.

[0027] Furthermore, a first reversing valve 6, a second reversing valve 7, a first heat exchanger 8, and a circulating oil pump 9 are also installed on the pipeline between the buffer oil tank 1 and the circulating oil tank 5.

[0028] After the circulating fuel tank 5, the following components are connected in sequence via pipelines: a third reversing valve 14, a third temperature sensor 15, the fuel pump 16 of the aircraft under test, a second heat exchanger 17, a fourth temperature sensor 18, and a self-regulating diverter valve 20. After flowing out of the fuel pump 15, the fuel in the circulating fuel tank 5 first enters the second heat exchanger 17 to exchange heat with the refrigerant supplied via the third refrigerant pipeline 13 for cooling. The cooled fuel is then diverted through the diverter valve; part of it flows through the diverter valve and then through the second pipeline 22 into the buffer fuel tank 1, while the other part flows through the diverter valve and then through the first pipeline 21 into the circulating fuel tank 5.

[0029] The diversion valve is an electrically operated three-way regulating valve.

[0030] The refrigeration and temperature control unit 11 adopts a product with mature market technology. Its refrigeration power is selected according to 1.5 times the maximum heat generation power of the aircraft fuel pump to ensure the refrigeration effect. When the aircraft fuel pump is in a constant power operation state, it can be regulated by the refrigeration and temperature control unit so that the temperature after the fuel pump is controlled within the preset temperature range of ±0.5℃ after passing through the second heat exchanger 17.

[0031] The first heat exchanger 8 and the second heat exchanger 17 are plate heat exchangers to ensure high heat exchange efficiency.

[0032] Aircraft fuel pump low-temperature test requirements:

[0033] During cryogenic testing of aircraft fuel pumps, it is necessary to maintain the inlet fuel temperature stable at the temperature specified in the test outline. However, aircraft fuel pumps are mostly variable displacement pumps, meaning their power needs to be adjusted during operation, which leads to changes in their heat generation. The operating states of aircraft fuel pumps can be categorized into constant power and variable power states. To realistically simulate the operating states of aircraft fuel pumps as closely as possible during testing, the test system must maintain a constant inlet temperature for the aircraft fuel pump in both constant power and variable power operating states.

[0034] Detailed implementation methods and principles:

[0035] As shown in Figure 1, the buffer fuel tank 1 is installed at a relatively high position in the system, while the circulating fuel tank 5 is at a relatively low position. The main function of the buffer fuel tank 1 is to store a sufficient amount of cryogenic fuel to buffer fuel temperature fluctuations caused by changes in the aircraft fuel pump power; the main function of the circulating fuel tank 5 is to store a certain amount of cryogenic fuel to meet the system's circulating operation needs. The volume of the buffer fuel tank 1 is approximately 10 times the maximum flow rate of the fuel pump; the volume of the circulating fuel tank 5 is approximately twice the maximum flow rate of the fuel pump.

[0036] Specifically, the experiment can be divided into two stages:

[0037] Preparation phase:

[0038] Before the low-temperature test begins, the fuel in both tanks needs to be cooled to the specified temperature. During this process, the first reversing valve 6, the third reversing valve 14, and the fourth reversing valve 24 are closed, while the second reversing valve 7 and the fifth reversing valve 26 are opened. After the circulating oil pump 9 is turned on, the fuel in the circulating oil tank 5 enters the first heat exchanger 8 via the circulating oil pump 9. In the first heat exchanger 8, it exchanges heat with the refrigerant prepared by the refrigeration temperature control unit, and then enters the buffer oil tank 1 via the second reversing valve 7. The fuel in the buffer oil tank 1 flows into the circulating oil tank 5 through the third connecting pipe 25. The buffer oil tank 1 is installed at a relatively high position, while the circulating oil tank 5 is at a relatively low position. Therefore, this process allows the fuel in both tanks to participate in the circulation. When the fuel temperature in both tanks reaches the specified test temperature, the process ends. Both tanks are then wrapped with heat-insulating material to prevent ambient heat from entering the tanks.

[0039] Formal trial phase:

[0040] During the formal testing phase, the first directional valve 6, the third directional valve 14, and the fourth directional valve 24 are activated.

[0041] The formal test was divided into two scenarios: constant power operation and variable power operation of the aircraft fuel pump. In the constant power operation scenario, the flow rate in the second pipeline 22 after the diversion valve is zero, and the buffer tank 1 does not participate in the system circulation. In the variable power operation scenario, there is flow rate in the second pipeline 22 after the diversion valve, and the buffer tank 1 participates in the system circulation.

[0042] During the formal test phase, the opening of the self-regulating diverter valve 20 is adjusted by the temperature controller to determine the fuel flow rate entering the buffer tank 1 and the circulating tank 5.

[0043] The specific process is as follows: The temperature controller detects the inlet fuel temperature of the fuel pump 16 (measured by the third temperature sensor 15) and the return fuel temperature (measured by the fourth temperature sensor 18), and calculates the difference between the two temperatures using an internal controller. When the difference is less than ±0.5℃, the flow rate from the self-regulating diversion valve 20 to the second pipeline 22 after the diversion valve is zero, and all fuel flows back to the circulating fuel tank 5. The fuel temperature in the circulating fuel tank 5 is regulated by the refrigeration and heating temperature control unit. When the difference exceeds ±0.5℃, the opening of the diversion valve is adjusted, causing the flow rate into the buffer tank via the second pipeline 22 after the diversion valve to gradually increase, while the amount of fuel returning to the circulating fuel tank decreases. This forces some fuel to flow from the buffer tank 1 into the circulating fuel tank 5 through the third connecting pipeline 25, and the buffer tank 1 begins to play a temperature buffering role, reducing the burden on the refrigeration and heating temperature control unit.

[0044] Based on the above, when the aircraft fuel pump power remains constant or changes slowly, the fuel temperature in the circulating fuel tank can be controlled by the refrigeration and temperature control unit, which can greatly reduce the refrigeration power of the refrigeration and temperature control unit. When the aircraft fuel pump power changes rapidly, a diversion valve is installed on the return fuel line. When the temperature fluctuation exceeds the allowable range, a portion of the fuel is diverted through the diversion valve and then through a second line into the buffer fuel tank, thus reducing the temperature fluctuation.

[0045] As is known from common technical knowledge, this invention can be implemented through other embodiments that do not depart from its spirit or essential characteristics. Therefore, the disclosed embodiments described above are merely illustrative in all respects and are not the only ones. All modifications within the scope of this invention or its equivalents are included in this invention.

Claims

1. A cryogenic testing system for an aircraft fuel pump, characterized in that, The system includes a buffer oil tank (1), a circulating oil tank (5), a first heat exchanger (8), a circulating oil pump (9), a refrigeration and temperature control unit (11), a fuel pump to be tested (16), a second heat exchanger (17), and a self-regulating diverter valve (20). The buffer oil tank (1) is connected to the circulating oil tank (5) via a first connecting pipe (3), and the first heat exchanger (8) is also provided on the first connecting pipe (3). The refrigeration and temperature control unit (11) is connected to the first heat exchanger (8) via a first refrigerant pipe (10), and the second heat exchanger (17) is connected to the refrigeration and temperature control unit (11) via a second refrigerant pipe (12). The heat exchanger (17) is also connected to the first heat exchanger (8) through the third refrigerant line (13). The two sides of the fuel pump (16) to be tested are connected to the second heat exchanger (17) and the circulating oil tank (5) respectively. The circulating oil tank (5) is also connected to the buffer oil tank (1) through the second connecting line (23) and the third connecting line (25). The buffer oil tank (1) is connected to the self-operated diverter valve (20) through the second line (22) after the diverter valve. The self-operated diverter valve (20) is connected to the second heat exchanger (17) and the circulating oil tank (5) through the line (19) before the diverter valve and the first line (21) after the diverter valve respectively.

2. The aircraft fuel pump cryogenic testing system according to claim 1, characterized in that: A second reversing valve (7) is connected to the first connecting pipeline (3) between the buffer oil tank (1) and the first heat exchanger (8), and a first reversing valve (6) and a circulating oil pump (9) are respectively connected to the two branches connecting the first heat exchanger (8) and the circulating oil tank (5).

3. The aircraft fuel pump cryogenic testing system according to claim 2, characterized in that: The second connecting pipe (23) and the third connecting pipe (25) are respectively connected to the fourth reversing valve (24) and the fifth reversing valve (26), and the pipe between the circulating oil tank (5) and the fuel pump (16) to be tested is connected to the third reversing valve (14).

4. The aircraft fuel pump cryogenic testing system according to claim 3, characterized in that: The buffer tank (1) is equipped with a first temperature sensor (2), the circulating tank (5) is equipped with a second temperature sensor (4), the inlet end of the fuel pump (16) to be tested is equipped with a third temperature sensor (15), the pipeline (19) before the diverter valve is equipped with a fourth temperature sensor (18), and the third temperature sensor (15) and the fourth temperature sensor (18) are also connected to the temperature controller.

5. A test method applied to the aircraft fuel pump cryogenic test system as described in claim 4, characterized in that: The test includes a preparation stage and a formal test stage. The preparation stage includes the following steps: Step 1: Before the test begins, the fuel in the buffer tank (1) and the circulating tank (5) is cooled to a specified temperature. Step 2: The first reversing valve (6), the third reversing valve (14) and the fourth reversing valve (24) are closed, and the second reversing valve (7) and the fifth reversing valve (26) are opened. After the circulating oil pump (9) is turned on, the fuel in the circulating tank (5) enters the first heat exchanger (8) through the circulating oil pump (9). In the first heat exchanger (8), the fuel exchanges heat with the refrigerant prepared by the refrigeration temperature control unit. Then, the fuel enters the buffer tank (1) through the second reversing valve (7). The fuel in the buffer tank (1) flows into the circulating tank (5) through the third connecting pipe (25). The formal test stage is as follows: The temperature controller detects the inlet fuel temperature of the fuel pump (16) to be tested by the third temperature sensor (15) and the return oil temperature by the fourth temperature sensor (18). The internal controller calculates the difference between the two temperatures. When the difference between the two is less than ±0.5℃, the flow rate from the self-operated diverter valve (20) to the second pipeline (22) after the diverter valve is zero, and all fuel flows back to the circulating oil tank (5). The fuel temperature in the circulating oil tank (5) is controlled by the refrigeration and heating temperature control unit. When the difference between the two exceeds ±0.5℃, the opening of the self-regulating diversion valve (20) is adjusted so that the flow rate of the second pipeline (22) after passing through the diversion valve into the buffer oil tank (1) gradually increases, while the amount of fuel returning to the circulating oil tank (5) decreases. This forces a portion of the fuel to flow from the buffer oil tank (1) into the circulating oil tank (5) through the third connecting pipeline (25). The buffer oil tank (1) begins to play a temperature buffering role, reducing the burden on the refrigeration temperature control unit.

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