Method for quickly verifying capability of auxiliary power device based on rack

Abstract

The invention discloses a method for quickly verifying the capability of an auxiliary power device based on a rack, and the operation environment of the method comprises the steps: carrying out a simulation test on the rack, and simulating an inlet throat of an air turbine starter through a contraction nozzle in the test; before a test, a total pressure recovery coefficient sigma and a conversion inlet area At * of an air turbine starter are calculated, the minimum throat area At'of the shrinkage nozzle is determined, during the test, a test total pressure recovery coefficient sigma'and a conversion area At * 'of the shrinkage nozzle are calculated, and the minimum throat area At'of the shrinkage nozzle is determined by adjusting the test total pressure recovery coefficient sigma' or the minimum area At 'of the shrinkage nozzle. Enabling At * to be equal to At * ', obtaining the required power Pt of the auxiliary power device at the moment, calculating the test power Pt' of the auxiliary power device at the moment, and judging whether the capability of the auxiliary power device meets the requirement or not by comparing Pt with Pt '. Through the method, the verification method and difficulty are simplified, the capability of the auxiliary power device can be rapidly verified under the rack condition, and the verification efficiency is effectively improved.

Description

Technical Field

[0001] The present invention belongs to the field of aero-engine test design, and particularly relates to a method for quickly verifying the capabilities of an auxiliary power unit based on a test bench. Background Art

[0002] An auxiliary power unit (hereinafter referred to as APU) paired with an air turbine starter (hereinafter referred to as ATS) serves as the second power source for a carrier-based fighter and also as the engine starting power source, which can effectively improve the combat effectiveness of the fighter and simplify the shipboard support work. The APU supporting the BE engine is a newly developed equipment. Before conducting a starting joint test with the BE engine, it is necessary to quickly verify the bench capabilities of the APU to determine the bench transformation plan and test method.

[0003] However, in the existing verification methods, it is generally necessary to verify the capabilities of the APU on a dedicated test bench in cooperation with an air turbine starter, but this cannot be achieved under some test conditions.

[0004] As for the patent application document with the publication number CN106226060B, it specifically discloses an aircraft auxiliary power unit test system, which includes a main control console, an electronic control unit, a fuel tank, a test bench, vibration sensors, and an auxiliary power unit; the auxiliary power unit includes a pulse tachometer, a generator output terminal, an exhaust pipe, and an air intake port; the main control console includes a programmed computer, an electrical control box, a fuel control box, and an intake and exhaust lubricating oil tank; the programmed computer is respectively connected to the electrical control box, the fuel control box, and the intake and exhaust lubricating oil tank through a 485 data bus for communication; the test bench mainly includes a mounting base, a dynamometer system, an exhaust pipe line, and an air intake pipe line; the mounting base includes a metal platform and a three-point support vertically welded on the metal platform; the auxiliary power unit has three mounting points; the three-point support matches the three mounting points of the auxiliary power unit; at least two temperature sensors, a pressure sensor, and a gas flow meter are provided on the air intake pipe line; the dynamometer system includes an eddy current dynamometer and a connecting shaft, and the connecting shaft is a flexible connecting shaft, and the eddy current dynamometer is connected to the generator output terminal of the auxiliary power unit through the flexible connecting shaft; the exhaust pipe line is correspondingly connected to the exhaust port of the auxiliary power unit, and at least four temperature sensors are installed on the exhaust pipe line; the air intake pipe line is connected to the air intake port of the auxiliary power unit; the fuel control box includes a fuel pump, a fuel switch, and a fuel pressure regulating valve; the fuel pump is respectively connected to the fuel switch and the fuel tank, and the fuel pressure regulating valve is respectively connected to the fuel tank and the fuel regulator on the auxiliary power unit through a fuel pipeline; a fuel flow meter is provided on the fuel pipeline; a temperature sensor and a fuel flow meter are provided in the fuel tank; the electronic control unit is connected to the electrical control box through an electrical control cable, and a multi-way control switch is provided on the electrical control cable between the electrical control box and the electronic control unit; the electronic control unit is connected to the pulse tachometer and the electrical control interface on the auxiliary power unit through an electrical control cable; the programmed computer is communicatively connected to the eddy current dynamometer. A temperature sensor is provided at the position of the air inlet of the air intake port on the auxiliary power unit; the auxiliary power unit includes a lubricating oil circuit, and a temperature sensor and a pressure sensor are installed on the lubricating oil circuit; the programmed computer and the eddy current dynamometer are connected through RS232 data communication, the vibration sensor is connected to the auxiliary power unit body in a hard connection manner, and the temperature sensor, the pressure sensor, the gas flow meter, the fuel flow meter, and the vibration sensor are connected to the programmed computer through sensor cables and a PIC bus. This method ensures the real-time and accuracy of the test, but it requires designing a dedicated test system, and the test system and its test method are complex, have high requirements for test conditions, are prone to errors, have low practicability, and low test efficiency.

[0005] Therefore, there is an urgent need to design a set of methods that can be simply and quickly verified under bench conditions, have low requirements for test conditions, and can quickly verify the bench capabilities of the auxiliary power unit APU before starting the joint test with the BE engine, so as to facilitate the subsequent determination of the bench transformation plan and test method. Summary of the Invention

[0006] To solve the above technical problems, the present application provides a method for quickly verifying the capabilities of an auxiliary power unit based on a test bench. The operating environment of the method is: conducting a simulation test on a test bench, where the auxiliary power unit and the air turbine starter are simultaneously used as the starting power sources for the engine, and a convergent nozzle is used to simulate the inlet throat of the air turbine starter in the simulation test;

[0007] The method includes the following steps:

[0008] Before the test, obtain the total outlet pressure P1 of the auxiliary power unit on the aircraft, the total inlet pressure P2 of the air turbine starter, and the minimum throat area At of the air turbine starter, and calculate the total pressure recovery coefficient σ and the converted inlet area At* of the air turbine starter;

[0009] Determine the minimum throat area At' of the convergent nozzle used in the test according to the minimum throat area At of the air turbine starter, and complete the connection of the simulation test pipeline;

[0010] During the test, start the auxiliary power unit, measure the test total pressure P1' at the outlet of the auxiliary power unit and the test total pressure P2' at the inlet of the convergent nozzle at the measuring points of the test pipeline, and calculate the test total pressure recovery coefficient σ' and the converted area At*' of the convergent nozzle;

[0011] Compare the magnitudes of At* and At*'. When At*' is not equal to At*, adjust the test total pressure recovery coefficient σ' or the minimum area At' of the convergent nozzle until At* is equal to At*';

[0012] Obtain the connecting pipe area A1, the ambient temperature T0, and the required power Pt of the auxiliary power unit at this time, calculate the test power Pt' of the auxiliary power unit, and determine whether the capabilities of the auxiliary power unit meet the requirements by comparing the magnitudes of the required power Pt and the test power Pt'.

[0013] Further, the calculation formula for the total pressure recovery coefficient σ is σ = P2 / P1.

[0014] Further, the calculation formula for the converted inlet area At* of the air turbine starter is At* = At / σ.

[0015] Further, when At*' is not equal to At*, the specific operations for adjusting the test total pressure recovery coefficient σ' or the minimum area At' of the convergent nozzle are as follows

[0016] When At* > At*', increase the minimum throat area At' of the contraction nozzle or decrease the total pressure recovery coefficient σ' of the test;

[0017] When At* < At*', increase the total pressure recovery coefficient σ' of the test.

[0018] Furthermore, the method for decreasing the total pressure recovery coefficient σ' of the test is to shorten the length of the simulation test pipeline or replace it with a smooth pipeline to reduce the total pressure recovery coefficient σ', and the method for increasing the total pressure recovery coefficient σ' of the test is to increase the length of the simulation test pipeline.

[0019] Furthermore, the calculation formula for the test power Pt' of the auxiliary power device is Pt' = qm' * Cp * (T1' - T0'),

[0020] where T0' is the ambient temperature of the test, T1' is the total outlet temperature of the test of the auxiliary power device, qm' is the test flow rate of the contraction nozzle, and Cp is the specific heat at constant pressure.

[0021] Furthermore, the test flow rate qm' of the contraction nozzle is calculated by the flow formula,

[0022] where K is the flow coefficient; T is the total outlet temperature of the test of the contraction nozzle; p is the total inlet pressure of the test of the contraction nozzle; A is the minimum cross-sectional area of the contraction nozzle; q(λ) is the flow function, and when the minimum cross-section of the contraction nozzle is in the critical state, q(λ) = 1.

[0023] Furthermore, the calculation formula for the flow coefficient K is

[0024] where k is the specific heat ratio, and when the working medium is air, k = 1.4; R is the gas constant, and when the working medium is air, R = 287.06.

[0025] Furthermore, the method for determining whether the capacity of the auxiliary power device meets the requirements is specifically as follows:

[0026] When Pt' ≥ Pt, the capacity of the auxiliary power device meets the requirements;

[0027] When Pt' < Pt, it is necessary to adjust the fuel supply plan of the auxiliary power device to increase the power output.

[0028] Furthermore, the measuring points of the test pipeline are the outlet of the auxiliary power device and the inlet of the contraction nozzle, and total pressure and total temperature sensors are installed at the measuring points of the test pipeline.

[0029] The beneficial effects of the present invention are as follows: By using a convergent nozzle in the test to simulate the inlet throat of an air turbine starter on an aircraft for verifying the capabilities of an auxiliary power unit, the test method is simplified, the test difficulty is reduced, and the efficiency of verifying the capabilities of the auxiliary power unit based on a test bench is improved. By comparing the test power Pt' and the required power Pt of the auxiliary power unit, the capabilities of the auxiliary power unit can be quickly verified, achieving the purpose of quickly verifying the capabilities of the auxiliary power unit under bench conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 FIG. is a schematic diagram of a test for quickly verifying the capabilities of an auxiliary power unit based on a test bench according to an embodiment of the present invention;

[0031] Figure 2 FIG. is a flowchart of a test for quickly verifying the capabilities of an auxiliary power unit based on a test bench according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0032] The technical solution of the present invention will be further described below, but the scope of protection claimed is not limited thereto.

[0033] An embodiment of the present invention provides a method for quickly verifying the capabilities of an auxiliary power unit based on a test bench. The operating environment of the method is as follows: A simulation test is carried out on a test bench. In the actual working environment, when the auxiliary power unit APU and the air turbine starter ATS are simultaneously used as the engine starting power sources, due to the very high pressure ratio of the auxiliary power unit APU, the inlet throat of the air turbine starter ATS is in a critical state. Therefore, in the simulation test, a convergent nozzle is used to simulate the inlet throat of the air turbine starter ATS, so that the auxiliary power unit APU operates in a real working environment matching the air turbine starter ATS;

[0034] The test equipment used in the simulation test includes: the test bench, the auxiliary power unit APU, the convergent nozzle, the engine controller, the pressure sensor PSRT, the starting motor, the bleed air flow regulating valve, and the total pressure and total temperature sensor. The test bench is connected to the pressure sensor PSRT through a cable and transmits control instructions to the auxiliary power unit APU; the starting motor is connected between the pressure sensor PSRT and the test bench, and the starting motor supplies power to the auxiliary power unit APU through the test bench; the test bench supplies fuel to the auxiliary power unit APU; the engine controller is connected to the pressure sensor PSRT through a cable and transmits the air supply instruction; the pressure sensor PSRT and the convergent nozzle are connected through a cable, and the bleed air flow regulating valve is arranged in the middle of the two to control the pressure and temperature; the auxiliary power unit APU and the convergent nozzle are connected through an air duct, measurement pipes are arranged at both the outlet of the auxiliary power unit and the inlet of the convergent nozzle, and the total pressure and total temperature sensor is arranged on the measurement pipe.

[0035] Based on the test environment and the test equipment, the method for quickly verifying the ability of the auxiliary power unit based on the test bench includes the following steps:

[0036] Before the test, according to the actual measurement, obtain the total pressure P1 at the outlet of the auxiliary power unit APU on the aircraft, the total pressure P2 at the inlet of the air turbine starter ATS, and the minimum throat area At of the air turbine starter ATS, and calculate the total pressure recovery coefficient σ and the converted inlet area At* of the air turbine starter ATS;

[0037] The total pressure recovery coefficient σ = total pressure at the inlet of ATS / total pressure at the outlet of APU, and its calculation formula is: σ = P2 / P1;

[0038] Design the connection pipeline of the test according to the total pressure recovery coefficient σ, and the principle of the connection pipeline of the test is as Figure 1 ;

[0039] The converted inlet area At* of the air turbine starter ATS is the converted inlet area of the air turbine starter ATS, which is a comparison parameter for converting the inlet area of the convergent nozzle into the actual inlet area of the air turbine starter ATS;

[0040] The calculation formula for the converted inlet area At* of the air turbine starter ATS is At* = At / σ

[0041] Determine the minimum throat area At' of the convergent nozzle used in the test according to the minimum throat area At of the air turbine starter ATS, and complete the connection of the simulation test pipeline;

[0042] The minimum throat area At' of the converging nozzle is less than or equal to the minimum throat area At of the air turbine starter ATS; the converging nozzle can be obtained by machining or selecting a finished converging nozzle.

[0043] During the test, start the auxiliary power unit APU, measure the test total pressure P1' at the outlet of the auxiliary power unit APU and the test total pressure P2' at the inlet of the converging nozzle at the measuring points on the test pipeline, calculate the test total pressure recovery coefficient σ' and the converted area At*' of the converging nozzle;

[0044] The measuring points on the test pipeline are the outlet of the auxiliary power unit and the inlet of the converging nozzle, and total pressure and total temperature sensors are arranged at the measuring points on the test pipeline.

[0045] The test total pressure recovery coefficient σ' = the test total pressure at the inlet of the ATS / the test total pressure at the outlet of the APU, and its calculation formula is: σ' = P2' / P1';

[0046] The calculation formula for the converted area At*' of the converging nozzle is: At*' = At' / σ';

[0047] Compare the sizes of At* and At*'. When At*' is not equal to At*, adjust the test total pressure recovery coefficient σ' or the minimum area At' of the converging nozzle until At* is equal to At*', At* = At*';

[0048] The specific operations for adjusting the test total pressure recovery coefficient σ' or the minimum area At' of the converging nozzle are as follows:

[0049] When At* > At*', increase the minimum throat area At' of the converging nozzle or decrease the test total pressure recovery coefficient σ';

[0050] When At* < At*', increase the test total pressure recovery coefficient σ'.

[0051] The method for decreasing the test total pressure recovery coefficient σ' is to shorten the length of the simulation test pipeline or replace it with a smooth pipeline to decrease the test total pressure recovery coefficient σ', and the method for increasing the test total pressure recovery coefficient σ' is to increase the length of the simulation test pipeline.

[0052] When At* = At*', obtain the connecting pipe area A1, the ambient temperature T0, and the required power Pt of the auxiliary power unit APU at this time, calculate the test power Pt' of the auxiliary power unit APU, and judge whether the ability of the auxiliary power unit APU meets the requirements by comparing the sizes of the required power Pt and the test power Pt'.

[0053] The method for determining whether the ability of the Auxiliary Power Unit (APU) meets the requirements is specifically as follows:

[0054] When Pt' ≥ Pt, the ability of the Auxiliary Power Unit (APU) meets the requirements;

[0055] When Pt' < Pt, it is necessary to adjust the fuel supply plan of the Auxiliary Power Unit (APU) to increase the power output.

[0056] The calculation formula for the test power Pt' of the Auxiliary Power Unit (APU) is: Pt' = qm' * Cp * (T1' - T0').

[0057] Where, T0' is the ambient temperature of the test, T1' is the total temperature at the test outlet of the convergent nozzle, qm' is the test outlet flow rate of the convergent nozzle, and Cp is the specific heat at constant pressure.

[0058] In this embodiment, the working medium is air. Therefore, the value of the specific heat at constant pressure Cp is obtained by querying the air specific heat at constant pressure table according to the ambient temperature.

[0059] The test outlet flow rate qm' of the convergent nozzle is calculated by the flow formula,

[0060] Where, K is the flow coefficient; T is the total temperature at the test outlet of the convergent nozzle; p is the total pressure at the test inlet of the convergent nozzle; A is the minimum cross-sectional area of the convergent nozzle; q(λ) is the flow function. When the minimum cross-section of the convergent nozzle is in the critical state, q(λ) = 1.

[0061] Because the total pressure loss at the inlet and outlet of the convergent nozzle is very small, it is considered that the total temperature at the inlet and outlet of the convergent nozzle does not change and there is no total pressure loss.

[0062] The calculation formula for the flow coefficient K is

[0063] Where, k is the specific heat ratio. When the working medium is air, k = 1.4; R is the gas constant. When the working medium is air, R = 287.06.

[0064] The present invention simplifies the test method, reduces the test difficulty, and improves the efficiency of verifying the ability of the Auxiliary Power Unit based on the test bench by using the convergent nozzle to simulate the inlet throat of the air turbine starter on the aircraft during the test. By comparing the test power Pt' of the Auxiliary Power Unit with the required power Pt, the ability of the Auxiliary Power Unit can be quickly verified, achieving the purpose of quickly verifying the ability of the Auxiliary Power Unit under the test bench conditions.

[0065] The specific embodiments of the present invention disclosed above are only examples. However, the present invention is not limited thereto, and any changes that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A method for quickly verifying the capability of an auxiliary power unit based on a test bench, characterized in that: The operating environment of the method is: a simulation test is performed on a bench, when the auxiliary power unit and the air turbine starter are used as the engine starting power source at the same time, and in the simulation test, a convergent nozzle is used to simulate the inlet throat of the air turbine starter; The method comprises the following steps: Before the test, obtain the auxiliary power unit outlet total pressure P1, the air turbine starter inlet total pressure P2 and the minimum throat area At of the air turbine starter on the aircraft, and calculate the total pressure recovery coefficient σ and the converted inlet area At* of the air turbine starter; According to the minimum throat area At of the air turbine starter, the minimum throat area At' of the contraction nozzle used for the test is determined, and the connection of the simulation test pipeline is completed; During the test, the auxiliary power unit is started, and the total test pressure P1' at the outlet of the auxiliary power unit and the total test pressure P2' at the inlet of the contraction nozzle are measured at the measuring points of the test pipeline, and the total test pressure recovery coefficient σ' and the conversion area At*' of the contraction nozzle are calculated; Comparing the sizes of At* and At*', when At*' is not equal to At*, adjusting the test total pressure recovery coefficient σ' or the minimum area At' of the contraction nozzle until At* is equal to At*'; The connecting pipe area A1, the ambient temperature T0 and the required power Pt of the auxiliary power unit are obtained, the test power Pt' of the auxiliary power unit is calculated, and whether the capacity of the auxiliary power unit meets the demand is determined by comparing the required power Pt and the test power Pt'.

2. The method for quickly verifying the capability of an auxiliary power unit based on a test bench as claimed in claim 1, characterized in that: The calculation formula of the total pressure recovery coefficient σ is: σ=P2 / P1.

3. The method for quickly verifying the capability of an auxiliary power unit based on a test bench as claimed in claim 1, characterized in that: The calculation formula of the converted inlet area At* of the air turbine starter is: At*=At / σ.

4. The method for quickly verifying the capability of an auxiliary power unit based on a test bench as claimed in claim 1, characterized in that: When the At*' is not equal to the At*, the specific operation of adjusting the test total pressure recovery coefficient σ' or the minimum area At' of the contraction nozzle is as follows: When At*>At*', increase the minimum throat area At' of the convergent nozzle or reduce the test total pressure recovery coefficient σ'; When At*<At*', increase the test total pressure recovery coefficient σ'.

5. The method for quickly verifying the capability of an auxiliary power unit based on a test bench as claimed in claim 4, characterized in that: The method for reducing the test total pressure recovery coefficient σ' is to shorten the length of the simulation test pipeline or replace a smooth pipeline to reduce the test total pressure recovery coefficient σ', and the method for increasing the test total pressure recovery coefficient σ' is to increase the length of the simulation test pipeline.

6. The method for quickly verifying the capability of an auxiliary power unit based on a test bench as claimed in claim 1, characterized in that: The calculation formula of the test power Pt' of the auxiliary power unit is: Pt'=qm'*Cp*(T1'-T0'), Wherein, T0' is the test ambient temperature, T1' is the total temperature of the test outlet of the auxiliary power unit, qm' is the test outlet flow rate of the convergence nozzle, and Cp is the constant pressure specific heat capacity.

7. The method for quickly verifying the capability of an auxiliary power unit based on a test bench as claimed in claim 6, characterized in that: The test outlet flow rate qm' of the convergent nozzle is calculated by the flow rate formula, Wherein, K is the flow coefficient; T is the total temperature at the test outlet of the contraction nozzle; p is the total pressure at the test inlet of the contraction nozzle; A is the minimum cross-sectional area of ​​the contraction nozzle; q(λ) is the flow function, and when the minimum cross-sectional area of ​​the contraction nozzle is in a critical state, q(λ)=1.

8. The method for quickly verifying the capability of an auxiliary power unit based on a test bench as claimed in claim 7, characterized in that: The calculation formula of the flow coefficient K is: Among them, k is the specific heat ratio. When the working fluid is air, k=1.4; R is the gas constant. When the working fluid is air, R=287.

06.

9. The method for quickly verifying the capability of an auxiliary power unit based on a test bench as claimed in claim 1, characterized in that: The method for judging whether the auxiliary power unit capacity meets the demand is specifically as follows: When Pt'≥Pt, the capacity of the auxiliary power unit meets the requirements; When Pt'<Pt, it is necessary to adjust the fuel supply plan of the auxiliary power unit to increase the power output.

10. The method for quickly verifying the capability of an auxiliary power unit based on a test bench as claimed in claim 1, characterized in that: The measuring points of the test pipeline are the outlet of the auxiliary power unit and the inlet of the contraction nozzle, and the measuring points of the test pipeline are all provided with total pressure and total temperature sensors.

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