A method for determining the bleed air flow rate of an external pipeline of an aircraft engine

Abstract

The present application belongs to the field of aircraft engine air system or thermal management, and in particular, relates to a method for determining the bleed air flow rate of an aircraft engine external pipeline, which performs heat exchange on the air of the external pipeline through a cold source medium; obtains the heat exchange amount of the heat exchange; calculates the target parameter of the external pipeline based on the heat exchange amount; increases the cooling effect of the external pipeline through a heat exchanger, and can determine the bleed air flow rate of the aircraft engine external pipeline through the heat exchanger, thereby solving the problem of significant test error influence when the pipeline flow rate is small and different test accuracy of bleed air due to a large flow change range during the test run.

Description

Technical Field

[0001] The present application belongs to the field of aircraft engine air system or thermal management, and in particular to a method for determining the bleed air flow rate of an external pipeline of an aircraft engine. Background Art

[0002] The external air duct of the engine internal flow system is a commonly used bleed air structure on aircraft engines. For example, the air extracted from the compressor is transported through the air duct to cool the high-temperature components of the turbine. In the performance design and analysis of aircraft engines, the actual air flow of the air duct must be obtained for the evaluation of the thermodynamic cycle and the function realization of the air system.

[0003] Since the flow rate in the air pipeline is generally small or the flow rate varies greatly under different conditions, the method of setting a flow meter on the air pipeline to test the flow rate has a large test error and it is difficult to accurately measure the air flow rate in all conditions during a test run.

[0004] The existing technology can measure the pressure / temperature of the air pipe inlet and outlet plenum on the aircraft engine as a whole, and use the pipe inlet and outlet flow characteristics calibrated by component test to calculate the flow through the air pipe on the whole machine. Or according to the patent 201711341713.4 (a method for calibrating the flow of air pipes in aircraft engines), the total pressure, static pressure, and total temperature test data of the same part as the component test are obtained on the aircraft engine as a whole, and the flow through the pipe on the whole machine is obtained according to the cross-sectional flow characteristics calibrated by the component test.

[0005] The disadvantage of the existing technical solution of using a flow meter to directly test the flow is that the flow in the air pipeline is generally small or the flow rate varies greatly under different conditions. Therefore, the method of setting a flow meter to test the flow rate has a large test error and it is difficult to accurately measure the air flow in all states during a test run.

[0006] The existing technical solution of calculating the flow through the air pipeline on the whole machine by measuring the air pipeline pressure / temperature according to the whole machine and using the pipeline inlet and outlet flow characteristics calibrated by component testing has the following disadvantages: mainly when the flow in the air pipeline is small, the pipeline inlet and outlet pressure ratio or the total static pressure of a certain section obtained by test is small, the test error has a significant impact on the pressure ratio of the horizontal axis, and the error is large when the flow characteristic obtains the corresponding flow. Summary of the invention

[0007] In order to solve the above problems, the present application provides a method for determining the bleed air flow rate of an external pipeline of an aircraft engine, comprising:

[0008] Perform heat exchange with the air in the external pipeline through the cold source medium;

[0009] Obtaining the heat exchange amount of the heat exchange;

[0010] The external pipeline target parameter is calculated based on the heat exchange amount.

[0011] Preferably, the target parameter is bleed air flow rate.

[0012] Preferably, a heat exchanger is installed on the external pipeline to allow the cold source medium to exchange heat with the external pipeline.

[0013] Preferably, the method for obtaining the heat exchange amount of the heat exchange comprises:

[0014] The heat absorption of the cold source working fluid is calculated by measuring the cold source working fluid flow rate, the cold source working fluid outlet temperature and the cold source working fluid inlet temperature; the heat release of the external pipeline air is converted by the heat absorption of the cold source working fluid.

[0015] Preferably, the method of converting the heat absorption into the heat release of the external pipeline air comprises:

[0016] Conduct component tests on the heat exchanger, and calculate the test heat absorption of the cold source working fluid and the test heat release of the air under the component test;

[0017] When the test heat absorption and the test heat release meet the preset requirements, the heat absorption of the cold source working fluid is equal to the heat release of the external pipeline air;

[0018] When the test heat absorption and the test heat release do not meet the preset conditions, correction values ​​of the test heat absorption and the test heat release are calculated, and the heat release of the external pipeline air is corrected by the correction values.

[0019] Preferably, the preset condition is:

[0020]

[0021] Q 1试验 is the experimental heat absorption of the cold source medium, Q 2试验 is the test heat release of air, and δ is the target value for judgment.

[0022] Preferably, the target value δ is determined to be 5%.

[0023] Preferably, the correction value is calculated as follows:

[0024] Q 1试验 -Q 2试验 =Q a ;

[0025] Q 1试验 is the experimental heat absorption of the cold source medium, Q 2试验 is the experimental heat release of air, Q a is the correction value.

[0026] Preferably, before the component test, the temperature range of the external pipeline air is calibrated through a component pre-test; and the flow resistance of the external pipeline air is calibrated.

[0027] Preferably, the method for calculating the external pipeline target parameter heating includes: measuring the air inlet temperature, the air outlet temperature, and calculating the air flow rate based on the heat release of the air in the external pipeline.

[0028] The advantages of the present application include: increasing the cooling effect of the external pipeline through the heat exchanger, and being able to determine the bleed air flow rate of the external pipeline of the aircraft engine through the heat exchanger, solving the problem of significant impact of test errors when the pipeline flow rate is small and different test accuracy of bleed air due to a large range of flow changes during the test process. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic diagram of the installation of a heat exchanger in a preferred embodiment of the present application;

[0030] Figure 2 This is a schematic diagram of the arrangement of temperature measurement points in a preferred embodiment of the present application;

[0031] Figure 3 This is a schematic diagram of a heat exchanger in a preferred embodiment of the present application;

[0032] Figure 4 The converted flow characteristic curve of the pipeline. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical scheme and advantages of the implementation of this application clearer, the technical scheme in the implementation of this application will be described in more detail in combination with the drawings in the implementation of this application. In the drawings, the same or similar reference numerals 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 cannot 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 combination with the drawings.

[0034] The present application provides a method for determining an external pipeline bleed air flow rate of an aircraft engine, comprising:

[0035] Perform heat exchange with the air in the external pipeline through the cold source medium;

[0036] Obtaining the heat exchange amount of the heat exchange;

[0037] The external pipeline target parameter is calculated based on the heat exchange amount.

[0038] Preferably, the target parameter is bleed air flow rate.

[0039] Preferably, a heat exchanger is installed on the external pipeline to allow the cold source medium to exchange heat with the external pipeline.

[0040] Preferably, the method for obtaining the heat exchange amount of the heat exchange comprises:

[0041] The heat absorption of the cold source working fluid is calculated by measuring the cold source working fluid flow rate, the cold source working fluid outlet temperature and the cold source working fluid inlet temperature; the heat release of the external pipeline air is converted by the heat absorption of the cold source working fluid.

[0042] Preferably, the method of converting the heat absorption into the heat release of the external pipeline air comprises:

[0043] Conduct component tests on the heat exchanger, and calculate the test heat absorption of the cold source working fluid and the test heat release of the air under the component test;

[0044] When the test heat absorption and the test heat release meet the preset requirements, the heat absorption of the cold source working fluid is equal to the heat release of the external pipeline air;

[0045] When the test heat absorption and the test heat release do not meet the preset conditions, correction values ​​of the test heat absorption and the test heat release are calculated, and the heat release of the external pipeline air is corrected by the correction values.

[0046] Preferably, the preset condition is:

[0047]

[0048] Q 1试验 is the experimental heat absorption of the cold source medium, Q 2试验 is the test heat release of air, and δ is the target value for judgment.

[0049] Preferably, the target value δ is determined to be 5%.

[0050] Preferably, the correction value is calculated as follows:

[0051] Q 1试验 -Q 2试验 =Q a ;

[0052] Q 1试验 is the experimental heat absorption of the cold source medium, Q 2试验 is the experimental heat release of air, Q a is the correction value.

[0053] Preferably, the correction value is calculated as follows:

[0054] Q 1试验 / Q 2试验 = k;

[0055] Q 1试验 is the experimental heat absorption of the cold source medium, Q 2试验 is the experimental heat release of air, Q a is the correction factor.

[0056] Preferably, before the component test, the temperature range of the external pipeline air is calibrated through a component pre-test; and the flow resistance of the external pipeline air is calibrated.

[0057] Preferably, the method for calculating the external pipeline target parameter heating includes: measuring the air inlet temperature, the air outlet temperature, and calculating the air flow rate based on the heat release of the air in the external pipeline.

[0058] The specific implementation of this application in conjunction with the accompanying drawings is as follows:

[0059] like Figure 1 As shown, during the engine test, a heat exchanger is placed on the air pipeline; the heat exchanger used can be a commonly used shell and tube heat exchanger, with relatively high temperature air passing through the internal heat exchange tube side and cold source working fluid passing through the shell side. The heat exchanger schematic diagram is shown in Figure 4 The cold source medium may be water or other media.

[0060] Conduct component tests on heat exchangers;

[0061] The test device itself must be checked and calibrated to prevent leakage.

[0062] Measure the parameters using measurement tools that meet the accuracy requirements.

[0063] According to the whole machine test run status, the flow resistance on the air side of the heat exchanger is calibrated to make it as close as possible to the resistance of the bleed air pipe of the replaced part.

[0064] According to the temperature range of the air in the bleed pipe during the whole machine test, the component pre-test is carried out for calibration. The main purpose is to verify the thermal balance or obtain the heat exchange between the fluid in the heat exchanger and the external environment, which is used for heat correction during the test.

[0065] During the component test, the measured parameters of each state reach a stable value before data recording. The test obtains the flow rate of the cold source working fluid, the inlet and outlet temperatures of the cold source working fluid, the flow rate of the air, the inlet and outlet temperatures of the air, and the thermodynamic formula obtains the test heat absorption of the cold source working fluid and the test heat release of the air to determine the thermal balance:

[0066]

[0067] Q 1试验 is the experimental heat absorption of the cold source medium, Q 2试验 is the test heat release of air, δ is the target value for judgment, and δ can be set to 5%. That is, the test result must satisfy that the heat absorption and heat release are basically equal. If the condition is met, the heat balance does not need to be corrected during the test run in this state. If not, the correction value needs to be calculated. The calculation method of the correction value is:

[0068] Q 1试验 -Q 2试验 =Q a ;

[0069] Q 1试验 is the experimental heat absorption of the cold source medium, Q 2试验 is the experimental heat release of air, Q a Preferably, the correction value is calculated as follows:

[0070] Q 1试验 / Q 2试验 = k;

[0071] Q 1试验 is the experimental heat absorption of the cold source medium, Q 2试验 is the test heat release of air, and k is the correction value.

[0072] In fact, it is always possible to adjust the temperature of the cold side medium to be close to the ambient temperature during component testing so that thermal equilibrium is achieved.

[0073] according to Figure 3 As shown, the temperature measuring points and the flow test device of the cold source working fluid are installed on the aircraft engine. It should be noted that the arrangement of the temperature measuring points of the pipeline should be as consistent as possible with the component test.

[0074] Carry out the whole machine test, and calculate the bleed air flow of the internal flow system according to the test parameters: the flow rate of the cold source working fluid, the inlet and outlet temperature of the heat exchanger cold source working fluid, the inlet and outlet temperature of the heat exchanger air, which is also the inlet and outlet temperature of the external pipeline:

[0075] When the thermal balance conditions are met in the component test, the calculation is performed through the following steps:

[0076] The amount of heat absorbed by the cold source medium through the heat exchanger is:

[0077]

[0078] Q1 is the amount of heat absorbed, G c is the flow rate of cold source working fluid, C pc is the specific heat capacity of the cold source fluid, is the outlet temperature of the cold source medium, for.

[0079] The heat released by air before and after passing through the heat exchanger is:

[0080]

[0081] Q2 is the heat released by air, G h is the air flow rate, C ph is the specific heat capacity of air, is the air inlet temperature, is the air outlet temperature.

[0082] Using the law of conservation of energy, that is, the heat absorption and heat release on the cold side and the hot side of the heat exchanger are equal, we can get:

[0083]

[0084] The air flow rate can be calculated.

[0085] When the thermal balance condition is not met during component testing, the calculation is performed through the following steps:

[0086] The amount of heat absorbed by the cold source medium through the heat exchanger is:

[0087]

[0088] Q1 is the amount of heat absorbed, G c is the flow rate of cold source working fluid, C pc is the specific heat capacity of the cold source fluid, is the outlet temperature of the cold source medium, for.

[0089] The heat released by air before and after passing through the heat exchanger is:

[0090]

[0091] Q2 is the heat released by air, G h is the air flow rate, C ph is the specific heat capacity of air, is the air inlet temperature, is the air outlet temperature.

[0092] Using the law of energy conservation and coefficient correction, we can get:

[0093]

[0094] The air flow rate can be calculated.

[0095] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A method for determining the bleed air flow rate of an external pipeline of an aircraft engine, characterized in that: include: Perform heat exchange with the air in the external pipeline through the cold source medium; Obtaining the heat exchange amount of the heat exchange; The method for obtaining the heat exchange amount of the heat exchange comprises: calculating the heat absorption of the cold source working fluid by measuring the flow rate of the cold source working fluid, the outlet temperature of the cold source working fluid and the inlet temperature of the cold source working fluid; converting the heat release of the external pipeline air by the heat absorption of the cold source working fluid; the method for converting the heat absorption into the heat release of the external pipeline air comprises: Conduct component tests on the heat exchanger, and calculate the test heat absorption of the cold source working fluid and the test heat release of the air under the component test; When the test heat absorption and the test heat release meet the preset requirements, the heat absorption of the cold source working fluid is equal to the heat release of the external pipeline air; When the test heat absorption and the test heat release do not meet the preset conditions, the correction values ​​of the test heat absorption and the test heat release are calculated, and the heat release of the external pipeline air is corrected by the correction values; The external pipeline target parameter is calculated based on the heat exchange amount; the target parameter is the bleed air flow rate, and the heating method for calculating the external pipeline target parameter includes: measuring the air inlet temperature, the air outlet temperature, and calculating the bleed air flow rate based on the heat release of the external pipeline air.

2. The method for determining the bleed air flow rate of an aircraft engine external pipeline according to claim 1, characterized in that: By installing a heat exchanger on the external pipeline, the cold source medium can exchange heat with the external pipeline.

3. The method for determining the air flow rate of an external pipeline of an aircraft engine according to claim 1, characterized in that: The preset conditions are: Q 1试验 is the experimental heat absorption of the cold source medium, Q 2试验 is the test heat release of air, and δ is the target value for judgment.

4. The method for determining the air flow rate of the external pipeline of an aircraft engine according to claim 3, characterized in that: The target value δ is judged to be 5%.

5. The method for determining the bleed air flow rate of an aircraft engine external pipeline according to claim 4, characterized in that: The correction value is calculated as follows: Q 1试验 -Q 2试验 =Q a ; Q 1试验 is the experimental heat absorption of the cold source medium, Q 2试验 is the experimental heat release of air, Q a is the correction value.

6. The method for determining the bleed air flow rate of an aircraft engine external pipeline according to claim 4, characterized in that: Before the component test, the temperature range of the external pipeline air is calibrated through the component pre-test; the air flow resistance of the external pipeline is calibrated.

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