CN102023096B - A high-altitude simulation test device and test method for internal flow of aviation piston engine - Google Patents

Abstract

The invention discloses an aviation piston engine internal flow high altitude simulation test device and a method thereof. The method aims to realize the high-altitude performance test of the aviation piston engine at low cost on the ground and obtain the performance parameters of the aviation piston engine or the aviation piston engine with a supercharger in the air. The air intake simulation method is characterized in that the low temperature and low pressure are simulated only for the air intake of the aviation piston engine, and the low pressure is simulated for the air exhaust to simulate the air running state of the engine. The adjustment of the air inlet simulation and the air exhaust simulation can adopt an asynchronous mode or a synchronous mode, the simulation height is gradually increased, the operation state of a 12000-meter high-altitude aviation piston engine can be simulated finally, and high-altitude performance data including torque and power are tested. The test method is low in implementation cost, easy to implement and flexible in test mode, and can be widely applied to ground high-altitude simulation tests of all aviation piston engines.

Description

A high-altitude simulation test device and test method for internal flow of aviation piston engine

technical field

The invention belongs to the technical field of aviation piston engines, and relates to high-altitude simulation test technology of aviation piston engines, in particular to a high-altitude simulation test method of internal flow of aviation piston engines.

Background technique

As we all know, the working principle of the aviation piston engine is the same as that of the internal combustion engine for the ground vehicle. The fuel is mixed and burned with the compressed air in the cylinder to push the piston to do work. Since the engine needs to inhale fresh air from the external environment as the working medium to participate in the work, when the air conditions in the external environment change, that is, when the intake air temperature and air intake pressure decrease with the increase of the flight altitude, the torque and power output by the engine also decreased.

In order to obtain the performance data of the aviation piston engine at high altitude, there are two methods: numerical calculation and high-altitude simulation test. The results obtained by numerical calculation also need to be verified by experiments.

At present, there are two methods for conducting high-altitude simulation tests.

One way is to go to higher altitudes to conduct experiments. China's Qinghai-Tibet Plateau is relatively high in altitude, and local tests can be done to obtain engine performance data at a certain altitude. There are two main disadvantages of this method. One is that every time a height is changed, it is necessary to find a suitable place to re-test, and it is greatly affected by the site and region. The other disadvantage is that it is limited by the limit of the altitude of the geographical location. Only test data at a certain altitude can be obtained, and higher altitude test data such as above 5,000 meters cannot be obtained.

Another high-altitude simulation test method is the well-known high-altitude platform high-altitude simulation test method. At present, the high-altitude platforms built in China are all designed by high-power gas turbines such as turbojet engines and turbofan engines. The method adopted is to put the whole engine into a high-altitude simulated environment chamber for testing. The shortcomings of this method for high-altitude simulation tests of aviation piston engines are obvious. The high-altitude platform designed for high-power gas turbines has a large gas flow rate, and the test cost is extremely high. However, the actual work of aviation piston engines requires a small gas flow rate. Carrying out high-altitude simulations in high-altitude cabins will result in great waste.

Contents of the invention

The purpose of the present invention is to solve the existing problems in the high-altitude simulation test of the aviation piston engine, and to provide a high-altitude simulation test device for the internal flow of the aviation piston engine and its test method. The high-altitude simulation is carried out, and a low-cost aviation piston engine high-altitude simulation test is realized.

The internal flow high-altitude simulation test method of the aviation piston engine uses the engine body to be placed in the ground atmospheric environment, and only the high-altitude simulation of the engine's working intake and exhaust is performed. Since the gas flow required for the engine's operation is small, it is necessary to build such a test system. The air source requirements, site requirements and equipment requirements are very low, so that high-altitude simulation tests of aviation piston engines can be carried out at low cost.

The actual working intake flow rate of the engine is small, continuous dynamic low-temperature refrigeration for small flow gas is easy to achieve in the laboratory, and it is easy to reach the temperature of -56.5°C under standard atmospheric conditions of 12,000 meters, and continuous dynamic vacuum pumping for small flow gas It is also easy to realize, and it is easy to reach the pressure of 19.33kPa under the standard atmospheric condition of 12000 meters. This method can be implemented in the laboratory at relatively low cost. It not only solves the problem that the high-altitude simulation test of the aviation piston engine on the plateau is limited by the site and height, but also solves the problem of high cost and waste of the high-altitude simulation test of the aviation piston engine on the existing high-altitude platform.

The invention provides a test device for high-altitude simulation of the internal flow of an aviation piston engine. The device includes an air intake high-altitude simulation system and an exhaust high-altitude simulation system, and also includes a work absorber. The air intake high-altitude simulation The system is composed of refrigeration equipment and a throttling regulating valve. The exhaust high-altitude simulation system is composed of a proportional regulating valve and a vacuum pump. The refrigeration equipment and the throttling regulating valve are sequentially connected to the air inlet of the aviation piston engine for Provide low-temperature and low-pressure air for the aviation piston engine; the power absorber is connected with the output shaft of the aviation piston engine for absorbing and measuring the output torque and power of the aviation piston engine during operation; the proportional regulating valve and the vacuum pump are sequentially The exhaust port of a connected aviation piston engine is used to simulate the exhaust port environment of an aviation piston engine.

The present invention also provides a kind of high-altitude simulation test method for internal flow of aviation piston engine, comprising the following steps:

Step 1. Test preparation: connect the aviation piston engine to the engine test bench according to the normal ground test, including connecting the output shaft of the aviation piston engine to the work absorber; The pipelines are connected, and the required working air intake of the aviation piston engine is supplied by the air intake high-altitude simulation system; the exhaust port of the aviation piston engine is connected with the exhaust high-altitude simulation system through a sealed pipeline, and the exhaust air of the aviation piston engine is not directly discharged into the Atmospheric environment of the test room is taken away by the exhaust high-altitude simulation system;

Step 2. Start the aviation piston engine under the air intake condition on the ground, and after the aviation piston engine is running normally, adjust the aviation piston engine to run in a certain working state that needs to carry out high-altitude simulation test;

Step 3: The aviation piston engine works stably in the current working state, adjust the intake high-altitude simulation system and the exhaust high-altitude simulation system, so that the aviation piston engine is located at a test simulation height under the current working state;

Step 4, measure the output torque and power of the aviation piston engine in the current working state through the power absorber;

Step 5. Repeat steps 3 and 4 to complete the high-altitude simulation test of the aviation piston engine at all altitudes in the current working state;

Step 6. Change the working state of the engine, repeat steps 3 to 5 to conduct high-altitude simulation tests, and complete the aviation piston engine.

Simulated tests at all altitudes under all working conditions of the engine.

Step seven, the test ends.

The advantages of the present invention are:

(1) The present invention solves the problem of being affected by the area of carrying out the high-altitude simulation test of the aviation piston engine on the plateau by carrying out the high-altitude simulation test of the aviation piston engine in the laboratory, and solves the problem that the test limit height is restricted by the geographical altitude. The simulation method provided can be used for long-term tests in the laboratory at any time, and the high-altitude simulation height can reach 12,000 meters;

(2) In the high-altitude simulation test of the internal flow of the aviation piston engine, the difficulty of high-altitude simulation is greatly reduced due to the high-altitude simulation of the internal flow gas required for engine operation, and the test cost for high-altitude simulation is also greatly reduced. It solves the huge waste caused by the high-altitude simulation of aviation piston engines on the conventional high-altitude platform.

Description of drawings

Fig. 1 is the connection structure schematic diagram of aviation piston engine internal flow high-altitude simulation test device of the present invention;

Fig. 2 is a flow chart of the high-altitude simulation test method for the internal flow of the aviation piston engine of the present invention.

In the picture:

1-aviation piston engine, 101-intake port, 102-exhaust port, 2-power absorber,

3-refrigeration equipment, 4-throttle control valve, 5-proportional control valve, 6-vacuum pump;

AIR IN-air intake, Exhaust Gas Out-exhaust gas discharge.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments.

As we all know, under the normal regulation of the fuel supply system (carburetor or fuel electronic injection system) of the internal combustion engine, the fuel supply is completely determined by the mass flow rate of the fresh air sucked into the internal combustion engine. Therefore, under normal working conditions, the air mass flow rate actually entering the internal combustion engine determines the working state of the internal combustion engine, that is, the performance data (power, torque) in the current working state is determined by the air mass flow rate.

As a kind of internal combustion engine, aviation piston engine is no exception. As the flight altitude of the aircraft increases, the ambient atmospheric pressure and temperature continue to decrease, which will seriously affect the air mass flow into the aviation piston engine. The impact trend is that the decrease of atmospheric pressure will lead to the decrease of air density and the decrease of air mass flow into the engine; the decrease of atmospheric temperature will lead to the increase of air density and the increase of air mass flow into the engine; The effect of the increase is smaller than that of the decrease in air density caused by the decrease in atmospheric pressure, so the general trend is that as the flight altitude increases, the air mass flow rate into the engine decreases, and the performance of the aviation piston engine also decreases.

Based on the above principles and theoretical basis, the present invention provides a high-altitude simulation test device for the internal flow of an aviation piston engine. The ground high-altitude simulation of the corresponding altitude downpressure and temperature is performed on the intake air, and the ground high-altitude simulation of the corresponding altitude downpressure is performed on the actual exhaust, so that the high-altitude simulation performance test of the aviation piston engine can be carried out in the laboratory under the ground environment.

The test device provided by the present invention is shown in Figure 1, and described test device mainly comprises intake high-altitude simulation system and exhaust high-altitude simulation system, also comprises a power absorber 2, and described intake high-altitude simulation system is composed of refrigeration The device 3 and the throttling control valve 4 are composed, and the exhaust high-altitude simulation system is composed of a proportional control valve 5 and a vacuum pump 6 . The air in the ground environment first enters the cooling device 3, which is marked as AIR IN in the figure, and the air temperature is cooled in the cooling device 3. The cooling temperature is determined by the standard atmospheric temperature corresponding to the flight altitude to be simulated. Refrigeration equipment 3 does not refer to a piece of equipment, but a set of equipment capable of dynamic continuous refrigeration and temperature adjustment of a certain gas flow rate, which can be realized by any scheme in the prior art, such as expansion turbine refrigeration, liquid Nitrogen refrigeration, etc.

After being refrigerated by the refrigeration equipment 3 and reaching the required temperature, the low-temperature air passes through the throttling regulating valve 4 for high-altitude simulation adjustment of intake pressure. The adjustment work at this time must be carried out when the aviation piston engine 1 is running. The gas required for engine operation is supplied by the pipeline of the high-altitude simulation system. When the aviation piston engine 1 is running, the piston cooperates with the gas in the cylinder suction pipeline to enter the cylinder. Combustion, when the mass flow rate of the gas to be pumped does not meet the requirements, the low pressure state is gradually generated. At this time, different low pressure simulations are obtained by adjusting the opening of the throttling control valve 4 . The low-temperature gas becomes a low-temperature and low-pressure gas after being pressure-regulated by the throttling regulating valve 4 , and the low-temperature and low-pressure gas is sucked into the cylinder by the engine air inlet 101 of the aviation piston engine 1 to participate in combustion and work.

The output shaft of the aviation piston engine 1 is connected to a work absorber 2 (such as a dynamometer, a propeller), and the output torque and power of the aviation piston engine 1 are absorbed and measured by the work absorber 2 during operation.

The low-temperature and low-pressure gas obtained above enters the aviation piston engine 1 and is mixed with fuel oil and burned in the cylinder to perform work. The exhaust gas is discharged from the engine exhaust port 102. The engine exhaust port 102 is connected to the proportional control valve 5 through a sealed pipeline. The proportional control valve The function of 5 is to adjust the power loaded by the vacuum pump 6 on the engine exhaust, and through the adjustment of the proportional control valve 5, the low pressure of the engine exhaust high-altitude simulation can be controlled. The proportional regulating valve 5 is connected to the vacuum pump 6 through a sealed pipeline. The exhaust gas enters the vacuum pump 6 after passing through the proportional regulating valve 5, and then is discharged into the atmosphere by the vacuum pump 6. The icon is marked as Exhaust GasOut, which refers to the exhaust gas from the engine.

The low pressure of the engine intake port and the low pressure of the engine exhaust port can be realized in various ways in the prior art, for example, it can be realized by means of ejection or vacuuming.

With reference to Fig. 2, the present invention also provides a kind of aviation piston engine internal flow high-altitude simulation test method, and concrete test procedure is as follows:

Step 1. Test preparation.

Before the test, connect the aviation piston engine to the engine test bench according to the normal ground test, including connecting the output shaft of the aviation piston engine to the work absorber; connecting the air intake of the aviation piston engine to the air intake high-altitude simulation system through a sealed pipeline , the required air intake for the aviation piston engine is supplied by the air intake high-altitude simulation system. The exhaust port of the aviation piston engine is connected to the exhaust high-altitude simulation system through a sealed pipeline, and the exhaust of the aviation piston engine is not directly discharged into the atmospheric environment of the test room, but is sucked away by the exhaust high-altitude simulation system.

After the above-mentioned equipment is connected, ensure that the various systems in the aviation piston engine are working normally. If it is not normal, you need to troubleshoot; check the working status of the internal flow high-altitude simulation test equipment. The internal flow high-altitude simulation test equipment includes refrigeration equipment 3. Throttling adjustment Valve 4, proportional regulating valve 5, vacuum pump 6 and all levels of sealed pipelines for connection.

Step 2, the aviation piston engine starts to drive under the air intake condition on the ground.

At this time, neither the intake high-altitude simulation system nor the exhaust high-altitude simulation system works, and the air intake and exhaust of the aviation piston engine are directly connected with the ground ambient air. The air temperature is the ground ambient temperature, and the engine exhaust pressure is the ground ambient pressure.

After the aviation piston engine 1 is running normally, after necessary steps such as warming up and checking, the aviation piston engine 1 is adjusted to run in the first working state that needs to carry out the high-altitude simulation test.

Step three, high-altitude simulation.

After the aviation piston engine 1 works stably in the first working state, the air intake and exhaust of the aviation piston engine are actually working stably. When the working power of the exhaust high-altitude simulation system is increased, the pressure at the exhaust port of the aviation piston engine will gradually decrease, and the corresponding standard atmospheric altitude will gradually increase. At the same time, through the adjustment of the air intake high-altitude simulation system, when the engine is running, the piston cooperates with the cylinder to suck air, resulting in a gradual decrease in the air intake pressure of the aviation piston engine, and a gradual increase in the corresponding standard atmospheric altitude. The output power is adjusted by the intake high-altitude simulation system to achieve the required low temperature.

The above-mentioned improvement of the working power of the exhaust high-altitude simulation system is to make the pressure at the engine exhaust port 102 be in the required high-altitude simulation low pressure state by adjusting the proportional control valve 5 and the vacuum pump 6 . The adjustment of the above-mentioned air intake high-altitude simulation system refers to the operation of the aviation piston engine 1 by adjusting the throttle control valve 4, so that the pressure at the engine inlet 101 is in the required high-altitude simulation low pressure state, and at the same time, the output of the refrigeration equipment 3 corresponds to The low temperature required for upper-air simulations.

The pressure adjustment of the exhaust port and the pressure and temperature adjustment of the air intake port can be adjusted in an automatic synchronous way to adjust the intake and exhaust, and can also be adjusted in an asynchronous manual mode. The asynchronous manual mode adjustment needs to adjust the exhaust pressure first to make the engine exhaust The pressure at the port 102 is lower than the pressure at the engine intake port 101, and then adjust the throttle control valve 4 to synchronize the pressure at the engine intake port 1 with the pressure at the engine exhaust port 102, such as the pressure at the engine intake port 101 is lower than The pressure at the engine exhaust port 102 will easily cause the aviation piston engine 1 to work unstable. The adjustment of the simulated low temperature can be carried out by means of an automatic controller to control the cooling power, or it can be carried out by means of hot air mixing or electric heating fine-tuning.

The automatic synchronization mode adjustment can be realized by an automatic controller (PID controller) cooperating with an actuator (electric control valve).

For the asynchronous manual adjustment, the adjustment sequence is to first adjust the exhaust pressure to decrease, and then adjust the intake pressure to decrease. The order cannot be reversed, otherwise the aviation piston engine cannot work stably. When adjusting the exhaust pressure first, ensure that the exhaust pressure is lower than the intake pressure, but the difference should be kept at 3-5kPa. The intake air temperature simulation can then be synchronized with the temperature corresponding to the altitude of the exhaust pressure simulation.

Step 4. When the intake high-altitude simulation system and the exhaust high-altitude simulation system have reached the intake low pressure, intake low temperature and exhaust low pressure required by the aviation piston engine, measure the output of the aviation piston engine 1 at this time through the work absorber 2 torque and power.

Step 5. Under the current working condition, change the test simulation height of the aviation piston engine, repeat steps 3 and 4, and complete all high-altitude simulation tests of the aviation piston engine under the current working condition.

Step 6. Change the working state of the engine, repeat steps 3 to 5 to conduct high-altitude simulation tests, and complete the aviation piston engine.

Simulated tests at all altitudes under all working conditions of the engine.

After completing the test process of step 3, according to the test requirements, judge whether all the high-altitude simulation tests of all aviation piston engines 1 in the current working state have been completed, if not completed, return to step 5 for execution, if completed, change the engine Working state, return to step 3 to carry out the high-altitude simulation test under the changed working state.

It should be noted that if the aviation piston engine is changed from a low-power working state to a high-power working state, the air intake flow of the aviation piston engine will increase, and the exhaust flow will increase accordingly. Throttle control valve 4 allows more gas flow to enter the engine or adjusts proportional control valve 5 to cooperate with vacuum pump 6 to increase the vacuum output, thereby ensuring that when the working state of the aviation piston engine changes, the pressure at the engine inlet 101 is not lower than that of the engine exhaust The pressure at the port 102 (the pressure difference is maintained at 3 ~ 5KPa), otherwise, it will easily lead to unstable operation of the engine; on the contrary, if the engine changes from a high-power working state to a low-power working state, the required intake air flow of the engine will decrease at this time. The exhaust flow rate also decreases synchronously, so it is necessary to adjust the proportional control valve 5 to cooperate with the vacuum pump 6 to reduce the vacuum output, so as to ensure that the difference between the pressure at the engine exhaust port 102 and the pressure at the engine intake port 101 will not be too large. Avoid large differentials that cause the engine to backfire in the exhaust.

Step seven, the test ends.

The test ends when the high-altitude simulation tests at all altitudes required for all engine operating states required by the test are completed.

What needs special explanation is:

1. According to a specific test requirement of a specific aviation piston engine, the number and value of the engine working state points to be tested will be different, and the height of the high-altitude simulation that needs to be performed also does not necessarily need to reach 12,000 meters, but It can be flexibly carried out according to needs, and the test device and method provided by the invention can be used to realize the simulation test under different working conditions of the aviation piston engine from the ground to the height of 12000 meters.

2. The aviation piston engine internal flow high-altitude simulation test method of the present invention can adopt more and more flexible methods to carry out in the process of adjusting the high-altitude simulation height and engine working state change, such as not using to complete a certain engine working state. The method of changing the working state of the engine after all the high-altitude simulation heights is adopted, and the method of changing the working state of the engine and adjusting the high-altitude simulation height is alternately carried out; some high-altitude simulation heights or even most of the high-altitude simulation heights under certain engine working conditions can also be omitted Insignificant test points for aircraft. The specific test process is determined by the specific test requirements.

Claims (4)

1. a kind of aviation piston engine internal flow high-altitude simulation test method, it is characterized in that: described simulation test method comprises the following steps: Step 1. Test preparation: connect the aviation piston engine to the engine test bench according to the normal ground test, including connecting the output shaft of the aviation piston engine to the work absorber, which is used to absorb and measure the output torque and power; connect the air intake of the aviation piston engine with the output pipeline of the air intake high-altitude simulation system, and the required working air intake of the aviation piston engine is supplied by the air intake high-altitude simulation system; connect the exhaust port of the aviation piston engine with the exhaust The high-altitude simulation system is connected by a sealed pipeline, and the exhaust of the aviation piston engine is not directly discharged into the atmospheric environment of the test room, but is taken away by the exhaust high-altitude simulation system; Composed, the exhaust high-altitude simulation system is composed of a proportional control valve and a vacuum pump, and the refrigeration equipment and the throttle control valve are sequentially connected to the air inlet of the aviation piston engine through a sealed pipeline, which is used to provide Low-temperature and low-pressure air; the proportional regulating valve and the vacuum pump are sequentially connected to the exhaust port of the aviation piston engine through a sealed pipeline, for simulating the exhaust environment of the aviation piston engine; Step 2. Start the aviation piston engine under the air intake condition on the ground, and after the aviation piston engine is running normally, adjust the aviation piston engine to run in a certain working state that needs to carry out high-altitude simulation test; Step 3: The aviation piston engine works stably in the current working state, adjust the intake high-altitude simulation system and the exhaust high-altitude simulation system, so that the aviation piston engine is located at a test simulation height under the current working state; Step 4, measure the output torque and power of the aviation piston engine in the current working state through the power absorber; Step 5. Repeat steps 3 and 4 to complete the high-altitude simulation test of the aviation piston engine at all altitudes in the current working state; Step 6. Change the working state of the engine, repeat steps 3 to 5 to carry out the high-altitude simulation test, and complete the simulation test of all altitudes under all working conditions of the aviation piston engine; Step seven, the test ends. 2. a kind of aviation piston engine internal flow high-altitude simulation test method according to claim 1, is characterized in that: in the step 3, adjust intake high-altitude simulation system and exhaust high-altitude simulation system, make aviation piston engine be positioned at current working state The specific adjustment process is as follows: increasing the working power of the exhaust high-altitude simulation system, the pressure at the exhaust port of the aviation piston engine will gradually decrease, and the corresponding standard atmospheric altitude will gradually increase. Adjustment, when the aviation piston engine is running, the piston cooperates with the cylinder to suck air, causing the air inlet pressure of the aviation piston engine to gradually decrease, and the corresponding standard atmospheric altitude also gradually increases, and the corresponding air intake temperature is adjusted by the air intake high-altitude simulation system The output power is to achieve the required low temperature, and the pressure adjustment of the exhaust port and the pressure and temperature adjustment of the air inlet adopt automatic synchronous adjustment, or asynchronous manual adjustment. 3. A kind of aviation piston engine internal flow high-altitude simulation test method according to claim 2, it is characterized in that: described asynchronous manual adjustment needs to adjust exhaust pressure first to make the pressure at the engine exhaust port be lower than the engine intake Then adjust the throttle control valve to synchronize the pressure at the engine intake port with the pressure at the engine exhaust port. When the exhaust pressure is lowered, ensure that the exhaust pressure is lower than the intake pressure, and the difference is kept at 3. ~5kPa. 4. a kind of aviation piston engine internal flow high-altitude simulation test method according to claim 1 is characterized in that: change the operating state of engine in the step 6, if aviation piston engine changes to high-power operating state from low-power operating state, It is necessary to adjust the throttle control valve to make more gas flow into the engine or adjust the proportional control valve to cooperate with the vacuum pump to increase the vacuum output, so as to ensure that when the working state of the aviation piston engine changes, the pressure at the engine inlet is not lower than the engine exhaust port On the contrary, if the engine changes from a high-power working state to a low-power working state, it is necessary to adjust the proportional control valve to cooperate with the vacuum pump to reduce the vacuum output to ensure that the pressure at the engine exhaust port is lower than the difference between the pressure at the engine intake port Keep it at 3-5kPa.

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