Helicopter engine air starting system simulation method

Abstract

The invention belongs to the technical field of helicopter starting system design, and particularly relates to a helicopter engine air starting system simulation method which comprises the following steps: step a, selecting an engine bleed air type to be simulated; b, establishing a three-dimensional simulation model according to the air entraining type of the engine; c, importing the simulation model into fluid calculation software, and setting boundary conditions; d, selecting a turbulence model, a heat transfer model and a calculation method for calculation; e, setting a state point of simulation calculation; f, system pressure drop is set, and airflow characteristic parameters at an inlet of the air starter are calculated until the steady state is obtained; and g, obtaining the equivalent power of the air starter according to the airflow characteristic parameters at the inlet of the air starter, comparing the equivalent power with the starting power of the air starter, and judging whether starting succeeds or not.

Description

Technical Field

[0001] The invention belongs to the technical field of helicopter starting system design, and in particular relates to a helicopter engine air starting system simulation method. Background Art

[0002] The engine ground starting performance has a great impact on the overall performance of the helicopter. Reliable and fast engine starting is the premise for the normal operation and safe flight of the helicopter. Therefore, in addition to improving the starting performance of the engine itself, studying the influence of key parameters of the helicopter engine air starting system (including APU air source, air pipeline system, air starter, etc.) on system loss is of great significance for the design of helicopter engine air starting system.

[0003] The development of helicopter air start systems based on simulation models can greatly reduce design and testing costs, significantly shorten the development cycle of air start systems, improve the success rate of system trial production and testing, and avoid potential development risks in advance. Summary of the invention

[0005] Purpose of the invention: A helicopter engine air starting system simulation method is proposed, which belongs to the field of aviation engine system simulation application technology. There are three methods for starting the engine, including APU bleed air starting the engine, engine cross bleed air starting another engine and ground air source bleed air starting the engine. The function of the air starting system is to guide the high-pressure air from the air source to the required part. The engine air starting system is mainly composed of an air starter, an air pipeline and an air valve, which is used to start the engine and can also provide high-temperature and high-pressure air to the environmental control system.

[0006] Technical Solution

[0007] A helicopter engine air starting system simulation method comprises the following steps:

[0008] Step a: Select the engine bleed air type to be simulated;

[0009] Step b: establishing a three-dimensional simulation model according to the engine bleed type;

[0010] Step c: Import the simulation model into the fluid calculation software and set the boundary conditions;

[0011] Step d: Select turbulence model, heat transfer model and calculation method for calculation;

[0012] Step e: setting the state point of simulation calculation;

[0013] Step f: setting the system pressure drop, and calculating the air flow characteristic parameters at the air starter inlet until a steady state is obtained;

[0014] Step g: Obtain the equivalent power of the air starter according to the air flow characteristic parameters at the air starter inlet, compare it with the starting power of the air starter itself, and determine whether the starting is successful.

[0015] Furthermore, the engine bleed air types include: APU bleed air start engine, engine cross bleed air start engine and ground air source bleed air start engine.

[0016] Furthermore, the three-dimensional simulation model corresponding to the APU bleed air starting engine includes: taking the starting of the left engine as an example, the APU, the APU one-way valve, the left starting control valve, the left air starter, and the left engine are connected in sequence through pipelines.

[0017] Furthermore, when the engine bleed air type is APU bleed air to start the engine, the specific process is as follows:

[0018] Step b1: Establish a three-dimensional simulation model of the APU bleed air starting engine, import it into the fluid simulation software ANSYS to generate a mesh with a mesh quality of more than 0.3 and a mesh number of more than 2 million;

[0019] Step 2: Import the generated grid into the fluid calculation software FLUENT, set the boundary conditions, use the WALL boundary for the pipeline wall, the I NLET boundary for the APU bleed air outlet, and the OUTLET boundary for the air starter inlet; select stainless steel as the pipeline material, and set the pipeline wall thickness and pipeline roughness; select AIR for the gas in the pipeline;

[0020] Step 3: Select the turbulent k-ε model, the heat flux model as the heat transfer method, and the second-order upwind model for calculation;

[0021] Step 4: Given the state point of the temperature characteristic of the APU bleed air height, it is used as the state point for simulation calculation; at the APU bleed air outlet, a mass flow inlet is set in the I NLET boundary, and the specific mass flow and temperature values ​​of the state point are substituted into the inlet mass flow and temperature; at the air starter inlet, a pressure outlet is set in the OUTLET boundary, and the specific pressure value of the state point is substituted into the inlet pressure;

[0022] Step 5: Determine the valve resistance loss at different state points through the flow resistance characteristic curves of the APU check valve and the start control valve, which is used to set the system pressure drop. After calculating the system until the steady state, the air flow characteristic parameters at the air starter inlet, including pressure, temperature and mass flow rate, are obtained;

[0023] Step 6: Obtain the air starter equivalent power through pressure, temperature and mass flow, and compare it with the starting power of the air starter itself. If it is greater than the starter equivalent power, it means that the engine is successfully started through APU bleed air starting at this state point.

[0024] Furthermore, the three-dimensional simulation model corresponding to the engine cross-bleed starting engine includes: taking the starting of the left engine as an example, the right engine air inlet, the air pressure check valve, the left starting control valve, the left air starter, and the left engine are connected in sequence through pipelines.

[0025] Furthermore, when the engine bleed type is engine cross bleed to start the engine, the specific process is as follows:

[0026] Step 1: Establish a three-dimensional simulation model of the engine cross-bleed start engine, and generate a mesh by importing the model into the fluid simulation software ANSYS, with a mesh quality of more than 0.3;

[0027] Step 2: Import the engine cross-bleed grid into the fluid calculation software FLUENT, set the boundary conditions, use the WALL boundary for the pipe wall, and select AI R for the gas in the pipe;

[0028] Step 3: Select the turbulent k-ε model, the heat flux model as the heat transfer method, and the second-order upwind model for calculation;

[0029] Step 4: Given the state points of the engine at different altitudes and temperatures, use them as the state points for simulation calculations; at the engine air inlet, set the mass flow inlet in the I NLET boundary, and substitute the specific mass flow and temperature values ​​of the state point into the inlet mass flow and temperature; at the air starter inlet, set the pressure outlet in the OUTLET boundary, and substitute the specific pressure value of the state point into the air starter inlet pressure setting.

[0030] Step 5: Determine the valve resistance loss at different state points through the flow resistance characteristic curves of the air bleed control valve and the start control valve, which is used to set the system pressure drop. After calculating the system until the steady state, the air flow characteristic parameters at the air starter inlet are obtained, including pressure, temperature and mass flow rate;

[0031] Step 6: The air starter equivalent power can be obtained through pressure, temperature and mass flow rate. Compared with the starting power of the air starter itself, if it is greater than the starter equivalent power, it means that another engine can be successfully started by cross-engine air starting at this state point.

[0032] Furthermore, the three-dimensional simulation model corresponding to the ground air source induced air starting engine includes: taking the left engine as an example, the ground air source, the air pressure one-way valve, the left starting control valve, the left air starter, and the left engine are connected in sequence through pipelines.

[0033] Furthermore, when the engine air bleed type is the ground air source air bleed to start the engine, the specific process is as follows:

[0034] Step 1: Establish a three-dimensional simulation model of the ground air source bleed start engine, and generate a mesh by importing the model into the fluid simulation software ANSYS, with a mesh quality of more than 0.3 and a mesh number of more than 2 million;

[0035] Step 2: Import the grid generated by the simulation model into the fluid calculation software FLUENT, set the boundary conditions, use the WALL boundary for the pipeline wall, the I NLET boundary for the ground air source inlet, and the OUTLET boundary for the air starter inlet; select stainless steel as the pipeline material, and set the pipeline wall thickness and pipeline roughness; select AIR for the gas in the pipeline;

[0036] Step 3: Select the turbulent k-ε model, the heat flux model as the heat transfer method, and the second-order upwind model for calculation;

[0037] Step 4: Given the bleed air parameters of the compressed air from the ground air source as the state point of the simulation calculation; the ground air source bleed air port, set the mass flow inlet in the I NLET boundary, and substitute the specific mass flow and temperature values ​​of the state point into the inlet mass flow and temperature; the air starter inlet, set the pressure outlet in the OUTLET boundary, and substitute the specific pressure value of the state point into the inlet pressure;

[0038] Step 5: Determine the flow resistance loss of the valves at different state points through the flow resistance characteristic curves of the air pressure check valve and the start control valve, which is used to set the system pressure drop. After calculating the system until the steady state, the air flow characteristic parameters at the inlet of the air starter are obtained, including pressure, temperature and mass flow rate;

[0039] Step 6: The air starter equivalent power can be obtained through pressure, temperature and mass flow rate, and compared with the starting power of the air starter itself. If it is greater than the starter equivalent power, it means that the engine can be successfully started by bleed air from the ground at this state point.

[0040] The present invention can provide a simulation verification method for helicopter air starting system design, which is used to guide engine starting design and has the following characteristics:

[0041] a) The present invention can provide a simulation method for the design of a helicopter air start system, which can reduce iterations and avoid duplication of work in the early stage of system design.

[0042] b) The present invention can calculate the pressure, temperature and flow loss of the entire air starting system under given boundary conditions, which is used to guide the design and further improve the reliability and feasibility of the system;

[0043] c) The present invention can preliminarily determine the equivalent power of the air starting system under given boundary conditions through a simulation method, and evaluate the starting performance by comparing it with the starting power.

[0044] d) By performing simulation calculations with given boundary conditions and models, simulation cloud maps and calculation results can be obtained. Performance parameters and loss variation patterns can be obtained by analyzing the simulation pressure and temperature cloud maps. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 Schematic diagram of the air starting system configuration.

[0046] Figure 2 Schematic diagram of the APU bleed air starting engine simulation model.

[0047] 1. Engine air intake; 2. Air starter; 3. Starting control valve; 4. Air intake control valve; 5. Ground air source; 6. Air pressure check valve; 7. APU check valve; 8. APU air intake; 9. APU. DETAILED DESCRIPTION

[0048] An air start simulation method for an aircraft engine. There are three methods for starting an engine, including starting the engine with APU bleed air, starting another engine with cross-engine bleed air, and starting the engine with ground air source bleed air. The function of the air start system is to guide the high-pressure air from the air source to the required part. The engine air start system is mainly composed of an air starter, an air pipeline and an air valve, which is used to start the engine and can also provide high-temperature and high-pressure air to the environmental control system.

[0049] Method A: APU bleed air to start the engine

[0050] 1) Principle of APU bleed air starting engine system

[0051] Auxiliary Power Unit is referred to as APU. The starting system is a twin-engine configuration. The system works as follows: APU bleed air enters the engine air starter, the air starter drives the engine to a certain speed, and the combustion chamber ignites to start the engine. An APU check valve is installed at the APU bleed air port to prevent the engine bleed air from entering the APU after the APU stops. Figure 1 As shown, the air supply pipe connected to the APU is divided into two pipelines, which respectively enter the air starters connected to the left and right engines, and the left and right engine starting pipelines are respectively connected in series with a starting control valve, and the corresponding engine can be selected to start by controlling the starting control valve.

[0052] 2) APU bleed air start engine system model

[0053] APU bleed air starting model: Taking the starting of the left engine as an example, APU bleed air port-APU check valve-starting control valve-air starter-left engine; the models of each part of the system are as follows:

[0054] a) APU is a single-rotor small turboshaft engine that can draw compressed air from the centrifugal compressor outlet for engine starting.

[0055] b) The APU one-way valve is used to connect the APU bleed air and provide the gas required for engine starting. There is a conical separator inside the one-way valve damper seat, which divides the inlet into two parts, so that the bleed air can be introduced into the product from both sides;

[0056] c) Start control valve It is used to connect and close the air turbine starter air intake, to open and cut off the compressed air in the pipeline provided to the air starter, to control the operation of the air starter, and has the function of limiting the outlet pressure, thereby ensuring the safe operation of the air starter;

[0057] d) The pipeline is connected from the APU bleed air outlet, connected in sequence to the APU check valve, the start control valve, and reaches the air turbine starter inlet;

[0058] e) The air starter is used to rotate the engine gas generator rotor when the engine is started on the ground or in the air. When the air starter is working, compressed gas of a certain pressure and temperature enters the starter from the intake housing. Using the principle of compressed gas expansion to do work, the starter obtains shaft power through the turbine. The power is transmitted through the reduction mechanism and clutch, and finally the output shaft outputs torque and speed to drive the engine to start.

[0059] 3) Simulation method of APU bleed air starting engine

[0060] The simulation modeling of APU bleed air starting engine is shown in the figure. The simulation steps are as follows:

[0061] Step 1: Determine the three-dimensional simulation model of the system through simulation modeling, namely APU-helicopter air start system (including pipelines and supporting valve products)-air starter-engine, and generate a mesh by importing the model into the fluid simulation software ANSYS. The mesh quality is guaranteed to be above 0.3 and the number of meshes is guaranteed to be above 2 million.

[0062] Step 2: Import the mesh generated by the simulation model into the fluid calculation software FLUENT. After checking the mesh quality again, set the boundary conditions. The pipe wall uses the WALL boundary. The WALL boundary is the wall surface, and the fluid cannot flow through the wall surface. The APU bleed air outlet uses the I NLET boundary, that is, the inlet boundary, and the air starter inlet uses the OUTLET boundary, that is, the outlet boundary. Select stainless steel as the pipe material, and set the pipe wall thickness. The pipe wall thickness affects the heat transfer of the pipe and determines the temperature loss of the pipe. The pipe roughness determines the flow resistance loss of the pipe. Select AIR for the gas in the pipe.

[0063] Step 3: Since the gas flows in the pipeline system in a turbulent form, the turbulent k-ε model is selected. Since the pipeline material is stainless steel, the heat transfer method is mainly heat conduction, so the heat flux model is selected for heat transfer, and the second-order upwind model is selected for calculation method.

[0064] Step 4: Given the state point of the temperature characteristic of the APU bleed air altitude, it is used as the state point for simulation calculation; a mass flow inlet is set in the APU bleed air outlet, i.e., the I NLET boundary, and the specific mass flow and temperature values ​​of the state point are substituted into the inlet mass flow and temperature; a pressure outlet is set in the air starter inlet, i.e., the OUTLET boundary, and the specific pressure value of the state point is substituted into the inlet pressure.

[0065] Step 5: Determine the valve resistance loss at different state points through the flow resistance characteristic curves of the APU check valve and the start control valve. The valve resistance loss determines the system pressure drop. The greater the flow resistance, the higher the pressure drop. After calculating the system until steady state, the air flow characteristic parameters at the air starter inlet are obtained, including pressure, temperature and mass flow rate.

[0066] Step 6: The air starter equivalent power can be calculated through pressure, temperature and mass flow rate, and compared with the starting power of the air starter itself. If it is greater than the starter equivalent power, it means that the engine can be started successfully through APU bleed air starting at this state point.

[0067] Method B: Engine cross-bleed start

[0068] 1) Principle of engine cross-bleed starting system

[0069] When the engines are cross-started, the air source comes from the compressed air of the compressor of another engine. The system principle is that the bleed air of one engine enters the air starter of another engine, and the bleed air of the engine drives the air starter to reach a certain speed. After the air starter rotor drives the engine speed to a certain value, it supplies fuel and ignites to start the engine. A bleed air control valve is set on the cross-start pipeline. This valve is a solenoid valve, which can control the cross-start of the engine by signaling the on and off of the control valve, and can provide a certain amount of bleed air conditions for environmental control. Figure 1 As shown in the figure, the high-temperature and high-pressure air coming out of the engine bleed port passes through the bleed control valve and reaches the start control valve of another engine. It is adjusted to the appropriate air starter inlet parameters through the valve and enters the air starter connected to the engine, thereby starting the corresponding engine. Cross-starting is applicable to the process of starting the engine by cross-bleeding the engine to another start control valve when one engine of a twin-engine or multi-engine aircraft is working. The cross-bleeding of the power system can reduce the risk of engine starting when a single engine stops or an APU fails. In addition, using cross-starting on the ground can improve the maneuverability of the helicopter platform.

[0070] 2) Engine cross-bleed starting system model

[0071] The principle of engine cross-bleed starting: Taking the starting of the left engine as an example, the right engine bleed port - bleed control valve - starting control valve - air starter - left engine; the models of each part of the system are as follows:

[0072] a) Engine bleed air is generated by the compressor, and compressed air can be drawn out from the compressor outlet for starting the engine.

[0073] b) Engine bleed air starting uses the high-temperature and high-pressure gas generated by the engine compressor bleed air to drive another air starter to start the engine.

[0074] c) The bleed air control valve is a solenoid valve, which connects the engine bleed air by giving an on / off signal to provide the gas required for engine starting. There is a conical separator inside the one-way valve seat, which divides the inlet into two parts, so that the bleed air can be introduced into the product from both sides;

[0075] d) The pipeline is connected from the engine bleed air outlet, connected in sequence to the bleed air control valve, the starter control valve, and reaches the air starter inlet;

[0076] 3) Engine cross-bleed starting simulation method

[0077] The simulation modeling of the engine cross-bleed start engine is shown in the figure, and the simulation steps are as follows:

[0078] Step 1: Determine the cross-start three-dimensional simulation model through simulation modeling, namely, engine air inlet-helicopter air starting system (including pipelines and supporting valve products)-air starter-engine, and generate a mesh by importing the model into the fluid simulation software ANSYS, with quality assurance above 0.3.

[0079] Step 2: Import the engine cross-bleed grid into the fluid calculation software FLUENT, set the boundary conditions, use the WALL boundary for the pipe wall, the WALL boundary is a wall, and the fluid cannot flow through the wall. The APU bleed air outlet uses the I NLET boundary, that is, the inlet boundary, and the air starter inlet uses the OUTLET boundary, that is, the outlet boundary. Select stainless steel as the pipe material, and set the pipe wall thickness. The pipe wall thickness affects the heat transfer of the pipe and determines the temperature loss of the pipe. The pipe roughness determines the flow resistance loss of the pipe. Select AIR for the gas in the pipe.

[0080] Step 3: Since the gas flows in the pipeline system in a turbulent form, the turbulent k-ε model is selected. Since the pipeline material is stainless steel, the heat transfer method is mainly heat conduction, so the heat flux model is selected for heat transfer, and the second-order upwind model is selected for calculation method.

[0081] Step 4: Given the state points of the engine at different altitudes and temperatures, use them as the state points for simulation calculations; set a mass flow inlet in the engine air inlet, i.e., the I NLET boundary, and substitute the specific mass flow and temperature values ​​of the state point into the inlet mass flow and temperature; set a pressure outlet in the air starter inlet, i.e., the OUTLET boundary, and substitute the specific pressure value of the state point into the air starter inlet pressure setting.

[0082] Step 5: Determine the valve resistance loss at different state points through the flow resistance characteristic curves of the air induction control valve and the starting control valve, which is used to set the system pressure drop. After calculating the system until it reaches a steady state, the air flow characteristic parameters at the air starter inlet are obtained, including pressure, temperature and mass flow rate.

[0083] Step 6: The air starter equivalent power can be obtained through pressure, temperature and mass flow, and compared with the starting power of the air starter itself. If it is greater than the starter equivalent power, it means that another engine can be successfully started through engine cross-bleeding at this state point.

[0084] Method C: Starting the engine with ground air source

[0085] 1) Principle of engine starting with ground air source

[0086] When starting with ground air source, the air source comes from the compressed air from the ground air source. The system principle is that the air from the air source enters another engine air starter through a one-way valve, and the starter is driven by the air to reach a certain speed and then ignites and starts the engine. Figure 1 As shown, the bleed air temperature provided by the ground air source is compressed gas at room temperature. After passing through the air pressure check valve and the air pipeline, it reaches the engine starting control valve. The starting control valve is used to select and start the corresponding engine. The starting control valve adjusts the inlet air pressure to enter the air starter, driving the engine speed to increase and ignite and start.

[0087] 2) Ground air source bleed air starting engine model

[0088] Ground air source starting model: Taking the starting of the left engine as an example, the ground air source air inlet-air pressure check valve-starting control valve-air starter-left engine; the models of each part of the system are as follows:

[0089] a) Ground air source starting engine is to drive the air starter by using the gas of a certain pressure and flow provided by the ground air source vehicle to start the engine

[0090] b) The air pressure check valve is to prevent the gas from flowing back into the ground air source. The check valve damper seat has a conical separator that divides the inlet into two parts. The air source draws air from both sides.

[0091] c) The pipeline is connected from the ground air source to the one-way valve interface, connected to the starting control valve to reach the air turbine starter inlet.

[0092] 3) Simulation method of engine starting with ground air source

[0093] The simulation modeling of the ground air source bleed air start engine is shown in the figure. The simulation steps are as follows:

[0094] Step 1: Determine the three-dimensional simulation model of the system through simulation modeling, namely, the ground air source air inlet-helicopter air starting system (including pipelines and supporting valve products)-air starter-engine. Generate a mesh by importing the model into the fluid simulation software ANSYS. The mesh quality is guaranteed to be above 0.3 and the number of meshes is guaranteed to be above 2 million.

[0095] Step 2: Import the mesh generated by the simulation model into the fluid calculation software FLUENT. After checking the mesh quality again, set the boundary conditions. The pipe wall uses the WALL boundary. The WALL boundary is the wall surface, and the fluid cannot flow through the wall surface. The APU bleed air outlet uses the I NLET boundary, that is, the inlet boundary, and the air starter inlet uses the OUTLET boundary, that is, the outlet boundary. Select stainless steel as the pipe material, and set the pipe wall thickness. The pipe wall thickness affects the heat transfer of the pipe and determines the temperature loss of the pipe. The pipe roughness determines the flow resistance loss of the pipe. Select AIR for the gas in the pipe.

[0096] Step 3: Since the gas flows in the pipeline system in a turbulent form, the turbulent k-ε model is selected. Since the pipeline material is stainless steel, the heat transfer method is mainly heat conduction, so the heat flux model is selected for heat transfer, and the second-order upwind model is selected for calculation method.

[0097] Step 4: The air inlet parameters of the compressed air from the ground air source are given as the state point of the simulation calculation; the mass flow inlet is set in the ground air source air inlet, i.e., the I NLET boundary, and the specific mass flow and temperature values ​​of the state point are substituted into the inlet mass flow and temperature; the pressure outlet is set in the air starter inlet, i.e., the OUTLET boundary, and the specific pressure value of the state point is substituted into the inlet pressure.

[0098] Step 5: Determine the valve resistance loss at different state points through the resistance characteristic curves of the air pressure check valve and the starting control valve, which is used to set the system pressure drop. After calculating the system until steady state, the air flow characteristic parameters at the air starter inlet are obtained, including pressure, temperature and mass flow rate.

[0099] Step 6: The air starter equivalent power can be obtained through pressure, temperature and mass flow rate, and compared with the starting power of the air starter itself. If it is greater than the starter equivalent power, it means that the engine can be started successfully by bleed air from the ground at this state point.

[0100] Simulation calculation example:

[0101] Take the APU bleed air start engine as a simulation example, and the modeling is shown in Figure 2 , set the boundary conditions to get the calculation results. The following are the calculation data:

[0102] The pressure drop parameters of the starting control valve, bleed air control valve, APU check valve and air pressure check valve are obtained by the loss of the valve flow resistance characteristics. The air starting system loss consists of two parts: pipeline loss and valve loss; the pipeline surface roughness is 0.042, the pipeline inner diameter is 70mm, and the pipeline length is 11m; the flow, temperature and pressure requirements of the APU under different states are shown in Table 1, and the air starter inlet parameters obtained by calculation are shown in Table 2.

[0103] From the results, it can be seen that the pressure loss of the pipeline is controlled at about 16 to 32 kPa, and the lower the altitude, the greater the pressure loss. Due to the long pipeline, the temperature loss is controlled at about 16 to 49 K.

[0104] Table 1 APU bleed air parameters

[0105]

[0106] Table 2 Simulation results

[0107] Height / km Temperature / ℃ Temperature loss K Pressure loss kPa Flow loss kg / s Output Power 0 -50 16.6 31.2 - 74.0 0 15 29.7 27.0 - 67.9 0 45 37.7 26.7 - 65.3 4000 -45 25.2 22.1 - 58.6 4000 -11 34.1 20.8 - 52.2 4000 19 45.0 19.2 - 44.5 6000 -46 28.4 19.0 - 52.1 6000 -24 35.2 18.3 - 47.0 6000 6 48.5 16.3 - 40.2

Claims

1. A helicopter engine air starting system simulation method, characterized in that: The following steps are involved: Step a: Select the engine bleed air type to be simulated; Step b: establishing a three-dimensional simulation model according to the engine bleed type; Step c: Import the simulation model into the fluid calculation software and set the boundary conditions; Step d: Select turbulence model, heat transfer model and calculation method for calculation; Step e: setting the state point of simulation calculation; Step f: setting the system pressure drop, and calculating the air flow characteristic parameters at the air starter inlet until a steady state is obtained; Step g: Obtain the equivalent power of the air starter according to the air flow characteristic parameters at the air starter inlet, compare it with the starting power of the air starter itself, and determine whether the starting is successful.

2. The method according to claim 1, characterized in that: Engine bleed air types include: APU bleed air start engine, engine cross bleed air start engine and ground air source bleed air start engine.

3. The method according to claim 2, characterized in that: The three-dimensional simulation model corresponding to the APU bleed air starting engine includes: taking the starting of the left engine as an example, the APU, the APU one-way valve, the left starting control valve, the left air starter, and the left engine are connected in sequence through pipelines.

4. The method according to claim 3, characterized in that: When the engine bleed type is APU bleed to start the engine, the specific process is as follows: Step b1: Establish a three-dimensional simulation model of the APU bleed air starting engine, import it into the fluid simulation software ANSYS to generate a mesh with a mesh quality of more than 0.3 and a mesh number of more than 2 million; Step 2: Import the generated grid into the fluid calculation software FLUENT, set the boundary conditions, use WALL boundary for the pipeline wall, INLET boundary for the APU bleed air outlet, and OUTLET boundary for the air starter inlet; select stainless steel as the pipeline material, and set the pipeline wall thickness and pipeline roughness; select AIR for the gas in the pipeline; Step 3: Select the turbulent k-ε model, the heat flux model as the heat transfer method, and the second-order upwind model for calculation; Step 4: Given the state point of the temperature characteristic of the middle altitude of the APU bleed air, it is used as the state point for simulation calculation; at the APU bleed air outlet, a mass flow inlet is set in the INLET boundary, and the specific mass flow and temperature values ​​of the state point are substituted into the inlet mass flow and temperature; at the air starter inlet, a pressure outlet is set in the OUTLET boundary, and the specific pressure value of the state point is substituted into the inlet pressure; Step 5: Determine the valve resistance loss at different state points through the flow resistance characteristic curves of the APU check valve and the start control valve, which is used to set the system pressure drop. After calculating the system until the steady state, the air flow characteristic parameters at the air starter inlet, including pressure, temperature and mass flow rate, are obtained; Step 6: Obtain the air starter equivalent power through pressure, temperature and mass flow, and compare it with the starting power of the air starter itself. If it is greater than the starter equivalent power, it means that the engine is successfully started through APU bleed air starting at this state point.

5. The method according to claim 2, characterized in that: The three-dimensional simulation model corresponding to the engine cross-bleed starting engine includes: taking the starting of the left engine as an example, the right engine air intake port, the air pressure check valve, the left starting control valve, the left air starter, and the left engine are connected in sequence through pipelines.

6. The method according to claim 5, characterized in that: When the engine bleed type is engine cross bleed to start the engine, the specific process is as follows: Step 1: Establish a three-dimensional simulation model of the engine cross-bleed start engine, and generate a mesh by importing the model into the fluid simulation software ANSYS, with a mesh quality of more than 0.3; Step 2: Import the engine cross-bleed grid into the fluid calculation software FLUENT, set the boundary conditions, use the WALL boundary for the pipe wall, and select AIR for the gas in the pipe; Step 3: Select the turbulent k-ε model, the heat flux model as the heat transfer method, and the second-order upwind model for calculation; Step 4: Given the state points of the engine with different bleed air temperatures at different altitudes, these are used as the state points for simulation calculation; At the engine air inlet, a mass flow inlet is set in the INLET boundary, and the specific mass flow and temperature values ​​at the state point are substituted into the inlet mass flow and temperature; at the air starter inlet, a pressure outlet is set in the OUTLET boundary, and the specific pressure value at the state point is substituted into the air starter inlet pressure setting. Step 5: Determine the valve resistance loss at different state points through the flow resistance characteristic curves of the air bleed control valve and the start control valve, which is used to set the system pressure drop. After calculating the system until the steady state, the air flow characteristic parameters at the air starter inlet are obtained, including pressure, temperature and mass flow rate; Step 6: The air starter equivalent power can be obtained through pressure, temperature and mass flow rate. Compared with the starting power of the air starter itself, if it is greater than the starter equivalent power, it means that another engine can be successfully started by cross-engine air starting at this state point.

7. The method according to claim 2, characterized in that: The three-dimensional simulation model corresponding to the ground air source bleed air starting engine includes: taking the left engine as an example, the ground air source, the air pressure one-way valve, the left starting control valve, the left air starter, and the left engine are connected in sequence through pipelines.

8. The method according to claim 7, characterized in that: When the engine bleed type is ground air source bleed to start the engine, the specific process is as follows: Step 1: Establish a three-dimensional simulation model of the ground air source bleed start engine, and generate a mesh by importing the model into the fluid simulation software ANSYS, with a mesh quality of more than 0.3 and a mesh number of more than 2 million; Step 2: Import the grid generated by the simulation model into the fluid calculation software FLUENT, set the boundary conditions, use the WALL boundary for the pipeline wall, the INLET boundary for the ground air source inlet, and the OUTLET boundary for the air starter inlet; select stainless steel as the pipeline material, and set the pipeline wall thickness and pipeline roughness; select AIR for the gas in the pipeline; Step 3: Select the turbulent k-ε model, the heat flux model as the heat transfer method, and the second-order upwind model for calculation; Step 4: Give the air bleed parameters of the compressed air from the ground air source as the state point of the simulation calculation; At the ground air source inlet, a mass flow inlet is set in the INLET boundary, and the specific mass flow and temperature values ​​of the state point are substituted into the inlet mass flow and temperature; at the air starter inlet, a pressure outlet is set in the OUTLET boundary, and the specific pressure value of the state point is substituted into the inlet pressure; Step 5: Determine the valve resistance loss at different state points through the resistance characteristic curves of the air pressure check valve and the start control valve, which is used to set the system pressure drop. After calculating the system until the steady state, obtain the air flow characteristic parameters at the inlet of the air starter, including pressure, temperature and mass flow rate; Step 6: The air starter equivalent power can be obtained through pressure, temperature and mass flow rate, and compared with the starting power of the air starter itself. If it is greater than the starter equivalent power, it means that the engine can be started successfully by bleed air from the ground air source at this state point.

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