A method for verifying the pre-spin temperature drop test of an aero-engine

Abstract

The present application belongs to the field of engine testing technology, and specifically relates to a method for testing and verifying the pre-swirl temperature drop of an aircraft engine. The method comprises: step S1, carrying out an engine test run, obtaining the rotating disc cavity pressure of the pre-swirl system, the rotating disc wall temperature, the total temperature of the first airflow in front of the pre-swirl nozzle of the pre-swirl system, and the relative total temperature of the second airflow at the inlet of the air supply hole of the rotating disc; step S2, determining the flow rate of the pre-swirl nozzle flowing through the pre-swirl system; step S3, obtaining the surface heat flux density of the rotating disc throughout the test run; step S4, determining the real-time heat absorption and release of the rotating disc; step S5, determining the relative total temperature at the air supply hole of the rotating disc; step S6, determining the adiabatic pre-swirl temperature drop of the pre-swirl system, which is used to verify the design compliance of the pre-swirl system. The present application has significant advantages such as a simple testing method and high inverse calculation accuracy, and can be directly used to verify the design compliance of the pre-swirl system.

Description

Technical Field

[0001] The present application belongs to the field of engine testing technology, and specifically relates to a method for verifying a pre-spin temperature drop test of an aero-engine. Background Art

[0002] The pre-swirl system of an aircraft engine refers to the air system that provides cooling air to the turbine rotor blades, such as Figure 1 As shown in the figure, the pre-swirl nozzle 1 ejects high-speed, high-angle cold air, which enters the rotating chamber through the receiving hole 21 of the rotating disk 2 and then rotates and flows out through the air supply hole 22 of the rotating disk 2. The rotating disk 2 imparts a high circumferential velocity to the airflow. While the absolute total temperature remains unchanged, the static temperature of the airflow drops significantly, and the relative total temperature felt by the rotating disk surface also drops significantly. This results in a lower airflow temperature (relative total temperature) felt by the turbine rotor blades, further significantly improving blade cooling and significantly increasing engine safety and lifespan.

[0003] In order to obtain better cooling benefits, the pre-swirl system needs to be carefully designed, and after the design is completed, it is necessary to conduct tests under engine operating conditions to verify whether the actual use effect meets the design expectations. Figure 1 As shown, an absolute total temperature measuring point T1 is arranged at the inlet of the pre-swirl nozzle 1, and a relative total temperature measuring point T2 is arranged at the inlet of the air supply hole 22. T1-T2 is the actual pre-swirl temperature drop, which is the actual benefit of designing the pre-swirl system.

[0004] It should be noted that the actual pre-swirl temperature drop is different from the pre-swirl temperature drop during theoretical design. The actual pre-swirl temperature drop test value will reflect the influence of fluid-solid heat balance, while the pre-swirl system is considered adiabatically during theoretical design. This application refers to the former as the measured pre-swirl temperature drop and the latter as the adiabatic pre-swirl temperature drop. The former is the actual air supply temperature felt by the turbine rotor blades; the latter is the expected design value, and the latter can be used more directly to verify whether the pre-swirl system design meets expectations. After considering the thermal balance, during the engine push-up process, since the wheel is cooler, the measured pre-swirl temperature drop will be larger than the adiabatic pre-swirl temperature drop; the pull-down process is just the opposite, the wheel is hotter, and the measured pre-swirl temperature drop is smaller.

[0005] How to convert the measured pre-swirl temperature drop into the adiabatic pre-swirl temperature drop, thereby verifying the pre-swirl system's conformance to design expectations, is an urgent problem. The conventional approach is to use materials with low thermal conductivity during component testing to minimize the impact of heat transfer, thereby assuming that the pre-swirl temperature drop measured in the experiment is the adiabatic pre-swirl temperature drop. However, the relevant components in actual engines are made of metal materials with excellent thermal conductivity. Ignoring heat transfer can lead to significant errors. Therefore, a new method is needed to address this issue. Summary of the Invention

[0006] In order to solve the above problems, the present application provides an aircraft engine pre-swirl temperature drop test verification method. Under the engine or core engine test conditions, by testing the comprehensive temperature drop value of the pre-swirl system, the adiabatic pre-swirl temperature drop is inferred to verify the design compliance of the pre-swirl system.

[0007] This application provides a method for verifying the pre-spin temperature drop test of an aircraft engine, which mainly includes:

[0008] Step S1: Conduct an engine test to obtain the rotating disk cavity pressure of the pre-swirl system, the rotating disk wall temperature, the total temperature of the first airflow in front of the pre-swirl nozzle of the pre-swirl system, and the relative total temperature of the second airflow at the air supply hole inlet of the rotating disk;

[0009] Step S2, determining the flow rate of the pre-swirl nozzle of the pre-swirl system according to the rotating disk cavity pressure;

[0010] Step S3: Loading the rotating disk wall temperature into the finite element temperature field calculation model of the rotating disk in the form of a first-class thermal boundary condition to obtain the rotating disk surface heat flux density throughout the test run;

[0011] Step S4, determining the real-time heat absorption and release of the rotating disk based on the heat flux density;

[0012] Step S5, determining the relative total temperature of the air supply holes of the rotating disk in an adiabatic state according to the real-time heat absorption and release, the relative total temperature of the second airflow, and the flow rate;

[0013] Step S6: determining the adiabatic pre-swirl temperature drop of the pre-swirl system based on the relative total temperature and the first airflow total temperature, so as to verify the design compliance of the pre-swirl system.

[0014] Preferably, in step S1, the wall temperature of the rotating disk is determined by arranging a plurality of wall temperature measuring points on the surface of the rotating disk of the pre-rotation system, the cavity pressure of the rotating disk is determined by arranging static pressure measuring points at the inlet and outlet of the pre-rotation nozzle and at the inlet of the air supply hole of the rotating disk, the total temperature of the first airflow is determined by arranging a total airflow temperature measuring point at the inlet of the pre-rotation nozzle, and the relative total temperature of the second airflow is determined by arranging a total airflow temperature measuring point at the inlet of the air supply hole.

[0015] Preferably, step S2 further comprises:

[0016] Taking the rotating disk cavity pressure as the boundary condition, the flow resistance characteristics of the pre-swirl nozzle and the receiving hole are input, and a one-dimensional air system grid calculation is carried out to obtain the flow rate of the pre-swirl nozzle flowing through the pre-swirl system.

[0017] Preferably, in step S4, the heat flux density is integrated along the inner disk surface of the rotating disk to obtain the real-time heat absorption and release of the rotating disk.

[0018] Preferably, step S4 further includes obtaining the state of the engine throttle lever, and when the engine throttle lever is pushed up, the real-time heat absorption and release is set to a negative value, and when the engine throttle lever is pulled down, the real-time heat absorption and release is set to a positive value.

[0019] Preferably, in step S5, the relative total temperature T2 at the air supply hole is determined based on the following formula: ad (t):

[0020] Q(t)=C•m(t)•(T2(t)-T2 ad (t));

[0021] Where C is the specific heat capacity of the fluid, m(t) is the circulation flow rate, T2(t) is the relative total temperature of the second airflow, Q(t) is the real-time heat absorption and release, and t is time.

[0022] This application solves the problem that traditional methods cannot determine the adiabatic pre-swirl temperature drop through testing under engine operating conditions. It has significant advantages such as simple testing method and high back-calculation accuracy, and can be directly used to verify the design compliance of the pre-swirl system. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of the pre-spin system structure.

[0024] Figure 2 This is a flow chart of a preferred embodiment of the aircraft engine pre-spin temperature drop test verification method of the present application.

[0025] Figure 3 Schematic diagram of measurement point arrangement scheme.

[0026] Among them, 1 is a pre-spin nozzle, 2 is a rotating disk, 21 is a receiving hole, and 22 is an air supply hole. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the implementation of this application clearer, the technical solutions in the implementation of this application will be described in more detail below in conjunction with the drawings in the implementation of this application. In the drawings, the same or similar numbers throughout represent the same or similar elements or elements with the same or similar functions. The described implementation is a part of the implementation of this application, not all of the implementations. The implementation described below with reference to the drawings is exemplary and is intended to be used to explain this application, and should not be understood as a limitation on this application. Based on the implementation in this application, all other implementations obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. The implementation of this application is described in detail below in conjunction with the drawings.

[0028] The first aspect of the present application provides a method for verifying the pre-spin temperature drop test of an aircraft engine, such as Figure 2 As shown, it mainly includes:

[0029] Step S1: Conduct an engine test to obtain the rotating disk cavity pressure of the pre-swirl system, the rotating disk wall temperature, the total temperature of the first airflow in front of the pre-swirl nozzle of the pre-swirl system, and the relative total temperature of the second airflow at the air supply hole inlet of the rotating disk;

[0030] Step S2, determining the flow rate of the pre-swirl nozzle of the pre-swirl system according to the rotating disk cavity pressure;

[0031] Step S3: Loading the rotating disk wall temperature into the finite element temperature field calculation model of the rotating disk in the form of a first-class thermal boundary condition to obtain the rotating disk surface heat flux density throughout the test run;

[0032] Step S4, determining the real-time heat absorption and release of the rotating disk based on the heat flux density;

[0033] Step S5, determining the relative total temperature of the air supply holes of the rotating disk in an adiabatic state according to the real-time heat absorption and release, the relative total temperature of the second airflow, and the flow rate;

[0034] Step S6: determining the adiabatic pre-swirl temperature drop of the pre-swirl system based on the relative total temperature and the first airflow total temperature, so as to verify the design compliance of the pre-swirl system.

[0035] Step S1 mainly arranges static pressure, air temperature and wall temperature measurement points, organizes and carries out test runs under the engine or core engine state, and obtains static pressure, total airflow temperature and wheel wall temperature measurement data throughout the test run. Figure 3 In some optional embodiments, in step S1, the wall temperature of the rotating disk is determined by arranging a plurality of wall temperature measuring points (hollow measuring points in the figure) on the surface of the rotating disk of the pre-swirl system, the cavity pressure of the rotating disk is determined by arranging static pressure measuring points (semi-solid measuring points in the figure) at the inlet and outlet of the pre-swirl nozzle and static pressure measuring points (semi-solid measuring points in the figure) at the inlet of the air supply hole of the rotating disk, the total temperature of the first airflow is determined by arranging a total airflow temperature measuring point (solid measuring point in the figure) at the inlet of the pre-swirl nozzle, and the relative total temperature of the second airflow is determined by arranging a total airflow temperature measuring point (solid measuring point in the figure) at the inlet of the air supply hole.

[0036] Step S2 is used to calibrate the flow rate. In some optional embodiments, step S2 further includes: using the rotating disk cavity pressure as a boundary condition, inputting the flow resistance characteristics of the pre-swirl nozzle and receiving hole, and performing a one-dimensional air system network calculation to obtain the flow rate m(t) flowing through the pre-swirl nozzle of the pre-swirl system, where t is time. Because this application is intended to calculate the entire engine test cycle, the flow rate changes in real time with the test time. It should be noted that, given the known inlet and outlet pressure boundary conditions, once the flow resistance characteristics of the pre-swirl nozzle and receiving hole are input, the conventional network calculation can be performed to obtain the flow rate.

[0037] Step S3 is used to infer the wall heat flux. To avoid the complexity of obtaining the heat transfer coefficient, the rotating disk wall temperature test data is directly loaded into the finite element temperature field calculation model of the rotating disk in the form of a first-class thermal boundary condition to obtain the disk surface heat flux density q (t, x, y, z) throughout the test process, where t is time and x, y, and z are spatial coordinates.

[0038] Step S3 is used to calculate the amount of heat absorbed and released. In some optional embodiments, in step S3, the heat flux density is calculated along the inner disk surface ( Figure 3 The real-time heat absorption and release Q(t) of the rotating disk is obtained by integrating the bold part (in the figure). This heat absorption and release is the quantitative value of the heat exchange between the rotating disk surface and the pre-spin system.

[0039] In some optional embodiments, step S3 further includes obtaining the state of the engine throttle lever. When the engine throttle lever is pushed up, the real-time heat absorption and release is set to a negative value. When the engine throttle lever is pulled down, the real-time heat absorption and release is set to a positive value.

[0040] Step S5 is used to inversely calculate the relative total temperature of the adiabatic state. Considering the presence of a vortex system in the rotating disk cavity, which will transfer the heat transfer in the cavity to the outlet of the pre-swirl system (before the air supply hole), the temperature change of the fluid can be calculated in a lumped manner. Assume that the relative total temperature of the air supply hole inlet under the adiabatic condition is T2 ad (t), the difference between the measured relative total temperature of the second airflow T2(t) is the effect of fluid-solid heat exchange. In some optional embodiments, in step S5, the relative total temperature T2 at the air supply hole is determined based on the following formula: ad (t):

[0041] Q(t)=C•m(t)•(T2(t)-T2 ad (t));

[0042] Where C is the specific heat capacity of the fluid, m(t) is the flow rate, T2(t) is the relative total temperature of the second airflow, Q(t) is the real-time heat absorption and release, and t is time. ad(t) is the relative total temperature of the airflow under adiabatic conditions, that is, the temperature theoretically felt by the disk after pre-spin.

[0043] Finally, in step S6, the adiabatic pre-spin temperature drop is calculated. T1(t) - T2 ad (t) is the real-time adiabatic pre-swirl temperature drop throughout the test run, and T1(t) is the total temperature of the first airflow. The adiabatic pre-swirl temperature drop should have the same value during the same aerodynamic state during both the ascent and descent processes, indicating that it is no longer affected by thermal equilibrium. This value can be directly used to verify the design compliance of the pre-swirl system.

[0044] This application establishes a method for calculating the adiabatic pre-swirl temperature drop of an aircraft engine based on measured cavity temperature data, which solves the problem that traditional methods cannot derive the adiabatic pre-swirl temperature drop through testing under engine operating conditions. It has significant advantages such as simple testing method and high inverse calculation accuracy, and can be directly used to verify the design compliance of the pre-swirl system.

[0045] Although the present application has been described in detail above using general descriptions and specific embodiments, it will be apparent to those skilled in the art that modifications or improvements may be made based on the present application. Therefore, such modifications or improvements, which do not depart from the spirit of the present application, are within the scope of protection claimed in the present application.

Claims

1. A method for verifying the pre-spin temperature drop test of an aircraft engine, characterized in that: include: Step S1: Conduct an engine test to obtain the rotating disk cavity pressure of the pre-swirl system, the rotating disk wall temperature, the total temperature of the first airflow in front of the pre-swirl nozzle of the pre-swirl system, and the relative total temperature of the second airflow at the air supply hole inlet of the rotating disk; Step S2, determining the flow rate of the pre-swirl nozzle of the pre-swirl system according to the rotating disk cavity pressure; Step S3: Loading the rotating disk wall temperature into the finite element temperature field calculation model of the rotating disk in the form of a first-class thermal boundary condition to obtain the rotating disk surface heat flux density throughout the test run; Step S4, determining the real-time heat absorption and release of the rotating disk based on the heat flux density; Step S5, determining the relative total temperature of the air supply holes of the rotating disk in an adiabatic state according to the real-time heat absorption and release, the relative total temperature of the second airflow, and the flow rate; Step S6: determining the adiabatic pre-swirl temperature drop of the pre-swirl system based on the relative total temperature and the first airflow total temperature, so as to verify the design compliance of the pre-swirl system.

2. The aircraft engine pre-spin temperature drop test verification method according to claim 1, characterized in that: In step S1, the wall temperature of the rotating disk is determined by arranging multiple wall temperature measuring points on the surface of the rotating disk of the pre-rotation system, the cavity pressure of the rotating disk is determined by arranging static pressure measuring points at the inlet and outlet of the pre-rotation nozzle and at the inlet of the air supply hole of the rotating disk, the total temperature of the first airflow is determined by arranging the total airflow temperature measuring point at the inlet of the pre-rotation nozzle, and the relative total temperature of the second airflow is determined by arranging the total airflow temperature measuring point at the inlet of the air supply hole.

3. The aircraft engine pre-spin temperature drop test verification method according to claim 1, characterized in that: Step S2 further comprises: Taking the rotating disk cavity pressure as the boundary condition, the flow resistance characteristics of the pre-swirl nozzle and the receiving hole are input, and a one-dimensional air system grid calculation is carried out to obtain the flow rate of the pre-swirl nozzle flowing through the pre-swirl system.

4. The aircraft engine pre-spin temperature drop test verification method according to claim 1, characterized in that: In step S4, the heat flux density is integrated along the inner disk surface of the rotating disk to obtain the real-time heat absorption and release of the rotating disk.

5. The aircraft engine pre-spin temperature drop test verification method according to claim 1, characterized in that: In step S4, it further includes obtaining the state of the engine throttle lever. When the engine throttle lever is pushed up, the real-time heat absorption and release is set to a negative value. When the engine throttle lever is pulled down, the real-time heat absorption and release is set to a positive value.

6. The aircraft engine pre-spin temperature drop test verification method according to claim 1, characterized in that: In step S5, the relative total temperature T2 at the air supply hole is determined based on the following formula: ad (t): Q(t)=C•m(t)•(T2(t)-T2 ad (t)); Where C is the specific heat capacity of the fluid, m(t) is the circulation flow rate, T2(t) is the relative total temperature of the second airflow, Q(t) is the real-time heat absorption and release, and t is time.

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