Air extraction test device and method for simulating high altitude of lubricating oil system

Abstract

The invention discloses an air exhaust test device and method for simulating the high altitude of a lubricating oil system, and belongs to the technical field of high altitude tests of lubricating oil systems of aero-engines. The device comprises a lubricating oil tank and a vacuum pump, the vacuum pump is connected with the top of the lubricating oil tank through an exhaust pipe A, and an air cooler is installed on the exhaust pipe A. According to the device, when the vacuum pump is adopted to pump negative pressure of the lubricating oil tank, the air cooler is installed on the exhaust pipe A to cool air pumped by the vacuum pump from the lubricating oil tank, and therefore the vacuum pump is protected and prevented from being damaged.

Description

Technical Field

[0001] The invention relates to an air extraction test device and method for simulating the high altitude performance of a lubricating oil system, belonging to the technical field of high altitude performance test of a lubricating oil system of an aero-engine. Background Art

[0002] The altitude performance of the aircraft engine lubricating oil system refers to the maximum flight altitude that the lubricating oil pump can reach to ensure the normal and reliable operation of the engine. The lubricating oil pump of an aircraft engine is generally a positive displacement type, and commonly used ones are gear pumps, rotary vane pumps and rotor pumps. The characteristics of a positive displacement pump are that the vacuum is drawn before the pump and the fluid is forced out after the pump. When the inlet conditions are the same, the pump outlet flow rate remains basically unchanged, and the pressure after the pump depends on the resistance after the pump. The performance of the lubricating oil pump is not only related to the structure of the lubricating oil pump itself, but also to the environment in which it is located. When the engine rises with the aircraft, the local atmospheric pressure where the engine is located will decrease with the increase in altitude. In the lubricating oil system, the lubricating oil tank or bearing cavity is connected to the atmosphere through a ventilator (except for throttling ventilation). The decrease in local atmospheric pressure will reduce the pressure in the oil tank or bearing cavity accordingly, resulting in a decrease in the flow rate in the lubricating oil inlet pipe. When the flow rate is reduced to a level that is insufficient to fill the pump's pumping capacity, the performance of the lubricating oil pump will drop sharply and cannot meet the normal needs of the engine. Therefore, the high-altitude performance of the engine lubricating oil system plays an important role in determining whether the lubricating oil system can work normally and even the safe flight of the aircraft. It is necessary to conduct experimental analysis on the high-altitude performance of the engine lubricating oil system.

[0003] A Chinese patent document with publication number CN105510037A discloses an altitude test system for an aircraft engine lubricating oil system, in which a vacuum pump is used to directly pump negative pressure into the lubricating oil tank to simulate the altitude conditions of the oil tank and each lubricating oil cavity.

[0004] However, during the test, the temperature of the lubricating oil reaches as high as 200°C, and the temperature inside the lubricating oil tank is also relatively high accordingly. The normal operating temperature of the vacuum pump is usually -10°C to 70°C. Therefore, using a vacuum pump to directly draw negative pressure from the lubricating oil tank may easily cause damage to the vacuum pump. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides an air extraction test device and method for simulating the high altitude performance of a lubricating oil system.

[0006] The present invention is achieved through the following technical solutions:

[0007] A vacuum test device for simulating the high altitude performance of a lubricating oil system comprises a lubricating oil tank and a vacuum pump. The vacuum pump is connected to the top of the lubricating oil tank through a vacuum pipe A, and an air cooler is installed on the vacuum pipe A.

[0008] The air cooler is a shell and tube heat exchanger.

[0009] The vacuum pump is a variable frequency screw vacuum pump.

[0010] It also includes a metering oil tank, the top of which is connected to the middle of the air extraction pipe A through the air extraction pipe B, the middle of which is connected to the bottom of the lubricating oil tank through the oil pipe, an oil pump and a valve C are provided on the oil pipe, and the valve C is located between the oil pump and the lubricating oil tank.

[0011] The metering oil tank is provided with a pressure sensor, a temperature sensor and a differential pressure level gauge.

[0012] The air extraction pipe B is provided with a valve B, the air extraction pipe A is provided with a valve A, and the valve A is located between the lubricating oil tank and the connection point between the air extraction pipe A and the air extraction pipe B.

[0013] An oil mist filter is provided on the exhaust pipe A between the air cooler and the vacuum pump.

[0014] It also includes an air intake pipe, on which a regulating valve is provided. One end of the air intake pipe is connected to the middle of the exhaust pipe A, and the connection point of the two is located between the air cooler and the oil mist filter.

[0015] A muffler is provided at one end of the air inlet pipe away from the exhaust pipe A and at the exhaust port of the vacuum pump.

[0016] A method for simulating the high altitude performance of a lubricating oil system by pumping air, comprising a pumping air test device, the method comprising the following steps:

[0017] Step 1: Open valve A and valve B, and adjust the opening of the regulating valve to 100%;

[0018] Step 2: Heat the lubricating oil in the oil tank to the required temperature;

[0019] Step 3: Start the vacuum pump to evacuate the lubricating oil tank and the metering oil tank, and gradually reduce the opening of the regulating valve by 2% to 10% as a step to simulate the high-altitude conditions of the lubricating oil tank and the metering oil tank;

[0020] Step 4: Open valve C and start the oil pump to pump part of the lubricating oil in the oil tank into the metering oil tank;

[0021] Step 5: Close valve C and the oil pump, start the lubricating oil pump to pump the lubricating oil in the metering oil tank to each oil point;

[0022] Step 6: After the oil pump runs stably, use the following formula to calculate the average volume flow rate q of the lubricating oil in any period of time: v :

[0023]

[0024] Where d is the inner diameter of the metering tank, ΔH is the level difference, Δτ is the duration of the calculated period, ΔP is the pressure difference in the metering tank, and ρ is the density of the lubricating oil.

[0025] The beneficial effects of the present invention are:

[0026] 1. While the device uses a vacuum pump to draw negative pressure from the lubricating oil tank, an air cooler is installed on the exhaust pipe A to cool the gas extracted from the lubricating oil tank by the vacuum pump, thereby protecting the vacuum pump and preventing it from being damaged.

[0027] 2. When the lubricating oil in the oil box heats up, oil mist will be generated. When the oil mist flows through the vacuum pump, it may remain and enter the lubrication system of the vacuum pump, affecting its normal use. For this reason, an oil mist filter is arranged at the air inlet of the vacuum pump. The air filtered by the oil mist filter meets the air intake cleanliness requirements of the vacuum pump and also meets the environmental protection requirements of the exhaust, so that the air extracted by the vacuum pump can be directly discharged into the atmosphere.

[0028] 3. By pumping air from the atmosphere at one end and from the oil tank at the other end, a more stable pressure value can be maintained in the oil tank during the vacuum pumping process. At the same time, it has better safety and will not cause the pressure in the oil tank to drop sharply due to excessive pumping rate. The pressure of the oil tank can reach the set pressure value required by the test more quickly.

[0029] 4. During the test, the lubricating oil temperature reaches up to 200℃, and the temperature in the oil tank is also relatively high. The normal working temperature of the vacuum pump is -10℃~70℃. In order to avoid damage to the vacuum pump, cooling measures should be set in front of the vacuum pump. The cooling measures adopt the following methods:

[0030] (1) Arrange an air cooler to cool the gas extracted from the lubricating oil tank by the vacuum pump.

[0031] (2) An air intake pipe is provided with a muffler installed at the pipe mouth. An appropriate amount of cold air is added into the exhaust pipe A to cool the air in front of the vacuum pump. The flow rate of the cold air added into the exhaust pipe A is adjusted by a regulating valve. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a structural schematic diagram of the present invention.

[0033] In the figure: 1-lubricating oil tank, 2-exhaust pipe A, 3-valve A, 4-air cooler, 5-vacuum pump, 6-muffler, 7-oil mist filter, 8-regulating valve, 9-air intake pipe, 10-valve B, 11-exhaust pipe B, 12-metering oil tank, 13-pressure sensor, 14-temperature sensor, 15-differential pressure level gauge, 16-oil pump, 17-oil pipe, 18-valve C. DETAILED DESCRIPTION

[0034] The technical solution of the present invention is further described below, but the scope of protection claimed is not limited to the description.

[0035] like Figure 1 As shown, the present invention discloses an air extraction test device for simulating the high altitude performance of a lubricating oil system, comprising a lubricating oil box 1 and a vacuum pump 5, wherein the vacuum pump 5 is connected to the top of the lubricating oil box 1 through an air extraction pipe A2, and an air cooler 4 is installed on the air extraction pipe A2. During the test, the temperature of the lubricating oil is as high as 200°C, and the temperature in the lubricating oil box 1 is correspondingly high, while the normal working temperature of the vacuum pump 5 is usually -10°C to 70°C. Therefore, while the device uses the vacuum pump 5 to extract negative pressure from the lubricating oil box 1, an air cooler 4 is installed on the air extraction pipe A2 to cool the gas extracted from the lubricating oil box 1 by the vacuum pump 5, thereby protecting the vacuum pump 5 from damage.

[0036] The air cooler 4 is a shell and tube heat exchanger. A water-cooled air cooler 4 is set to cool the air entering the vacuum pump 5. Since the extracted hot air contains oil gas, oil is formed after cooling and attached to the heat exchange surface, increasing the thermal resistance. The heat exchanger needs to be cleaned regularly. Therefore, the air cooler 4 is a shell and tube heat exchanger that is easy to clean and disassemble. The shell side is hot air and the tube side is cooling water. With an air flow rate of 200m 3 / h, pressure 87kPa (atmospheric pressure), temperature 200℃ as the inlet parameters of the hot side of the cooler, and the air outlet temperature is set to 60℃. Calculate the heat load:

[0037] Q=m Cp△T=4kW.

[0038] The shell side is hot air, the tube side is cooling water, and the total heat transfer coefficient is estimated to be about 50W / m 2 .K, the required heat dissipation area is about 0.8m 2 A U-shaped shell and tube heat exchanger is selected, with a shell side tube diameter of DN300 and a length of 1m, which can meet the design heat load requirements.

[0039] The vacuum pump 5 is a variable frequency screw vacuum pump. When in use, the vacuum pump 5 is a GHS350VSD+ variable frequency screw vacuum pump produced by Atlas Copco. The variable frequency screw vacuum pump adopts variable frequency regulation, and the pressure is more stable.

[0040] It also includes a metering oil tank 12, the top of which is connected to the middle of the air extraction pipe A2 via the air extraction pipe B11, the middle of the metering oil tank 12 is connected to the bottom of the lubricating oil tank 1 via the oil pipe 17, the oil pipe 17 is provided with an oil pump 16 and a valve C18, and the valve C18 is located between the oil pump 16 and the lubricating oil tank 1.

[0041] The metering oil tank 12 is provided with a pressure sensor 13, a temperature sensor 14 and a differential pressure level gauge 15. The pressure sensor 13 is used to detect the internal air pressure of the metering oil tank 12, the temperature sensor 14 is used to detect the temperature of the lubricating oil in the metering oil tank 12, and the differential pressure level gauge 15 is used to detect the liquid level in the differential pressure metering oil tank 12.

[0042] The air extraction pipe B11 is provided with a valve B10, the air extraction pipe A2 is provided with a valve A3, and the valve A3 is located between the lubricating oil tank 1 and the connection point between the air extraction pipe A2 and the air extraction pipe B11.

[0043] An oil mist filter 7 is provided on the exhaust pipe A2 between the air cooler 4 and the vacuum pump 5 .

[0044] It also includes an air intake pipe 9, on which a regulating valve 8 is provided. One end of the air intake pipe 9 is connected to the middle of the exhaust pipe A2, and the connection point between the two is located between the air cooler 4 and the oil mist filter 7. The lubricating oil in the oil tank 1 will produce oil mist after heating. When the oil mist flows through the vacuum pump 5, it may remain and enter the lubrication system of the vacuum pump 5, affecting its normal use. For this reason, the oil mist filter 7 is arranged at the air inlet of the vacuum pump 5. The air filtered by the oil mist filter 7 meets the air intake cleanliness requirements of the vacuum pump 5, and also meets the environmental protection requirements of the exhaust, so that the air extracted by the vacuum pump 5 can be directly discharged into the atmosphere.

[0045] A muffler 6 is provided at one end of the air inlet pipe 9 away from the exhaust pipe A2 and at the exhaust port of the vacuum pump 5 .

[0046] A method for simulating the high altitude performance of a lubricating oil system by pumping air, comprising a pumping air test device, the method comprising the following steps:

[0047] Step 1: Open valve A3 and valve B10, and adjust the opening of regulating valve 8 to 100%;

[0048] Step 2: heating the lubricating oil in the lubricating oil tank 1 to a desired temperature;

[0049] Step 3: Start the vacuum pump 5 to evacuate the oil tank 1 and the metering oil tank 12, and gradually reduce the opening of the regulating valve 8 by 2% to 10% to simulate the high-altitude conditions of the oil tank 1 and the metering oil tank 12. In fact, it simulates the pressure working conditions of the oil accessories in the high-altitude environment.

[0050] In the initial state, since the opening of the regulating valve 8 is adjusted to 100%, the vacuum pump 5 mainly pumps air from the atmosphere; when the opening of the regulating valve 8 is reduced, the vacuum pump 5 pumps air from the atmosphere on the one hand, and simultaneously pumps air from the lubricating oil tank 1 at the same time. By adopting this method of pumping air from the atmosphere at one end and from the lubricating oil tank 1 at the other end, the lubricating oil tank 1 can maintain a more stable pressure value during the vacuum pump 5 pumping air, and at the same time has better safety. The pressure in the lubricating oil tank 1 will not drop sharply due to an overly fast pumping rate, so that the pressure in the lubricating oil tank 1 can reach the set pressure value required by the test more quickly.

[0051] During the test, the lubricating oil temperature reaches up to 200°C, and the temperature in the lubricating oil tank 1 is also relatively high. The normal operating temperature of the vacuum pump 5 is -10°C to 70°C. In order to avoid damage to the vacuum pump 5, cooling measures need to be provided in front of the vacuum pump 5. The cooling measures adopt the following two methods:

[0052] (1) Arrange an air cooler 4 to cool the gas extracted from the lubricating oil tank 1 by the vacuum pump 5 by water.

[0053] (2) An air intake pipe 9 is provided, and a muffler 6 is installed at the pipe mouth. A proper amount of cold air is added into the exhaust pipe A2 to cool the air in front of the vacuum pump 5. The flow rate of the cold air added into the exhaust pipe A2 is adjusted by the regulating valve 8.

[0054] Step 4: open the valve C18 and start the oil pump 16 to pump part of the lubricating oil in the oil tank 1 into the metering oil tank 12.

[0055] Step 5: Close valve C18 and oil pump 16, start the lubricating oil pump to pump the lubricating oil in the metering oil tank 12 to each oil point. When in use, the lubricating oil pump includes a booster pump and an oil return pump. The booster pump pumps the lubricating oil in the metering oil tank 12 to each oil point, and the oil return pump returns the oil to each oil point, and the lubricating oil is recovered to the metering oil tank 12. The vacuum pump 5 is used to evacuate the lubricating oil tank 1 and the metering oil tank 12, in order to make the oil inlet pressure of the booster pump negative pressure, so as to simulate the working state of the booster pump in a high-altitude environment.

[0056] Step 6: After the oil pump runs stably, use the following formula to calculate the average volume flow rate q of the lubricating oil in any period of time: v :

[0057]

[0058] Wherein, d is the inner diameter of the metering oil tank 12, ΔH is the liquid level difference, Δτ is the duration of the calculated time period, ΔP is the pressure difference in the metering oil tank 12, and ρ is the density of the lubricating oil.

Claims

1. An air extraction test device for simulating the high altitude performance of a lubricating oil system, characterized in that: The invention comprises a lubricating oil box (1) and a vacuum pump (5), wherein the vacuum pump (5) is connected to the top of the lubricating oil box (1) via an air extraction pipe A (2), and an air cooler (4) is installed on the air extraction pipe A (2).

2. The air extraction test device for simulating the high altitude performance of the lubricating oil system according to claim 1, characterized in that: The air cooler (4) is a shell and tube heat exchanger.

3. The air extraction test device for simulating the high altitude performance of the lubricating oil system according to claim 1, characterized in that: The vacuum pump (5) is a variable frequency screw vacuum pump.

4. The air extraction test device for simulating the high altitude performance of a lubricating oil system according to claim 1, characterized in that: The invention also comprises a metering oil tank (12), the top of which is connected to the middle of the air extraction pipe A (2) via an air extraction pipe B (11), the middle of which is connected to the bottom of the lubricating oil tank (1) via an oil pipe (17), an oil pump (16) and a valve C (18) being provided on the oil pipe (17), and the valve C (18) being located between the oil pump (16) and the lubricating oil tank (1).

5. The air extraction test device for simulating the high altitude performance of the lubricating oil system according to claim 4, characterized in that: The metering oil tank (12) is provided with a pressure sensor (13), a temperature sensor (14) and a differential pressure level gauge (15).

6. The air extraction test device for simulating the high altitude performance of a lubricating oil system according to claim 4, characterized in that: The air extraction pipe B (11) is provided with a valve B (10), the air extraction pipe A (2) is provided with a valve A (3), and the valve A (3) is located between the lubricating oil box (1) and the connection point between the air extraction pipe A (2) and the air extraction pipe B (11).

7. The air extraction test device for simulating the high altitude performance of a lubricating oil system according to claim 1, characterized in that: An oil mist filter (7) is provided on the exhaust pipe A (2) between the air cooler (4) and the vacuum pump (5).

8. The air extraction test device for simulating the high altitude performance of a lubricating oil system according to claim 7, characterized in that: It also includes an air intake pipe (9), on which a regulating valve (8) is provided. One end of the air intake pipe (9) is connected to the middle of the exhaust pipe A (2), and the connection point between the two is located between the air cooler (4) and the oil mist filter (7).

9. The air extraction test device for simulating the high altitude performance of a lubricating oil system according to claim 8, characterized in that: A silencer (6) is provided at one end of the air inlet pipe (9) away from the exhaust pipe A (2) and at the exhaust port of the vacuum pump (5).

10. A method for simulating the high altitude performance of a lubricating oil system by means of an air extraction test, characterized in that: The device for conducting the air extraction test comprises the following steps: Step 1: Open valve A (3) and valve B (10), and adjust the opening of the regulating valve (8) to 100%; Step 2: heating the lubricating oil in the lubricating oil box (1) to a desired temperature; Step 3: Start the vacuum pump (5) to evacuate the lubricating oil tank (1) and the metering oil tank (12), and gradually reduce the opening of the regulating valve (8) by 2% to 10% to simulate the high-altitude conditions of the lubricating oil tank (1) and the metering oil tank (12); Step 4: Open valve C (18) and start the oil pump (16) to pump part of the lubricating oil in the oil tank (1) into the metering oil tank (12); Step 5: Close valve C (18) and oil pump (16), start the lubricating oil pump to pump the lubricating oil in the metering oil tank (12) to each oil consumption point; Step 6: After the oil pump runs stably, use the following formula to calculate the average volume flow rate q of the lubricating oil in any period of time: v : Wherein, d is the inner diameter of the metering oil tank (12), ΔH is the liquid level difference, Δτ is the duration of the calculated time period, ΔP is the pressure difference in the metering oil tank (12), and ρ is the density of the lubricating oil.

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