A method for judging the accuracy of fuel quantity at ignition point of aircraft engine

Abstract

The present application belongs to the field of engine test technology, and specifically relates to a method for determining the accuracy of the ignition point fuel quantity of an aircraft engine. The method includes step S1, determining the ignition point fuel quantity before the fuel supply accessories of the field engine are replaced, and taking it as the standard flow value; step S2, respectively selecting the maximum value, minimum value, minimum value of the fuel nozzle area control, and the lowest value and highest value of the fuel temperature requirement range for testing to obtain the standard nozzle front and rear pressure difference range under the standard flow value; step S3, after the fuel supply accessories of the field engine are replaced, the fuel supply of the engine is set to the standard flow value, and the nozzle front and rear pressure difference is calculated. If the nozzle front and rear pressure difference is within the standard nozzle front and rear pressure difference range, the ignition point fuel supply is accurate, otherwise the ignition point fuel supply is inaccurate. The present application can effectively guide the calibration of the fuel supply accessories, reduce the use risk of the engine after the fuel supply accessories are replaced, and reduce the adjustment workload when stall surge occurs.

Description

Technical Field

[0001] The present application belongs to the technical field of engine testing, and specifically relates to a method for determining the accuracy of the ignition point fuel quantity of an aircraft engine. Background Art

[0002] Generally, when aircraft engines are used in the field, they are not equipped with an onboard fuel flow meter due to limitations such as installation cost, flow meter reliability, pipeline strength, installation space and practicality. When replacing fuel supply accessories in the field, it is necessary to check the fuel supply accuracy of the fuel supply accessories, especially the ignition point fuel supply (first, the ignition point fuel supply is generally open-loop controlled, and the fuel supply accuracy cannot be guaranteed; second, the ignition point fuel supply is crucial to successful starting), otherwise ignition stall will occur, resulting in engine start failure.

[0003] In the prior art, after the fuel supply accessories of an aircraft engine are replaced in the field, only the technical state of the fuel supply accessories when they leave the factory can be used. However, there will be certain differences between the inspection environment of the fuel supply accessories when they leave the factory and the use environment under the installation conditions, resulting in certain deviations in the accuracy of the fuel supply accessories. The fuel supply can only be gradually adjusted to a suitable state after the engine has an ignition point stall. However, there is a probability that the engine will be started in the air before the adjustment is appropriate, resulting in a probability of ignition point stall and starting failure, which brings certain risks of use. Summary of the invention

[0004] In order to solve one of the above problems, the present application provides a method for judging the accuracy of the ignition point fuel quantity of an aircraft engine. Without installing a fuel flow meter, the accuracy of the ignition point fuel supply is judged through measurable parameters under installed conditions, thereby determining the external field status of the fuel supply accessories.

[0005] The method for determining the accuracy of the ignition point fuel quantity of an aircraft engine provided in this application mainly includes:

[0006] Step S1, determining the fuel supply amount at the ignition point before the fuel supply accessory of the field engine is replaced, and taking it as the standard flow value;

[0007] Step S2, respectively selecting the maximum value and the minimum value of the fuel nozzle area control and the lowest value and the highest value of the fuel temperature requirement range for testing, so as to obtain the standard nozzle front and rear pressure difference range under the standard flow value;

[0008] Step S3, after replacing the fuel supply accessories for the external engine, set the fuel supply of the engine to the standard flow value, calculate the pressure difference before and after the nozzle, if the pressure difference before and after the nozzle is within the standard pressure difference before and after the nozzle, the fuel supply of the ignition point is accurate, otherwise the fuel supply of the ignition point is inaccurate.

[0009] Preferably, after step S3, the method further comprises:

[0010] Step S4, adjusting the adjustment pin of the fuel supply accessory so that the front-to-rear pressure difference of the nozzle is within the range of the front-to-rear pressure difference of the standard nozzle.

[0011] Preferably, in step S3, calculating the pressure difference before and after the nozzle includes:

[0012] The pressure after the nozzle is measured by an onboard measuring point set behind the nozzle;

[0013] The pressure before the nozzle is measured by a test joint arranged before the nozzle;

[0014] The difference between the pressure before the nozzle and the pressure after the nozzle is taken as the pressure difference before and after the nozzle.

[0015] Preferably, the test joint arranged in front of the nozzle is connected to a sensor for pressure measurement during use, and after the measurement is completed, the test joint is sealed by a plug.

[0016] Preferably, the test joint in front of the nozzle is connected to the oil supply pipeline in front of the nozzle.

[0017] The key point of this application is how to accurately judge the fuel supply accuracy of the fuel supply accessories after replacement, guide the relevant calibration work, and ensure the accuracy of the engine fuel supply accessories.

[0018] The present application provides a means for calibrating the fuel supply accessories of an outfield engine. When the fuel supply accessories of an outfield engine are replaced, the fuel supply accuracy of the fuel supply accessories can be accurately determined through the existing onboard measurement parameters and the measurement parameters that can be achieved by installing sensors, which can effectively guide the calibration of the fuel supply accessories, reduce the use risk of the engine after the fuel supply accessories are replaced, and reduce the adjustment workload when abnormal problems such as stall / surge occur. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The present invention is a flow chart of a preferred embodiment of the method for determining the accuracy of the ignition point fuel quantity of an aircraft engine. DETAILED DESCRIPTION

[0020] 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.

[0021] The present application provides a method for determining the accuracy of the fuel quantity at the ignition point of an aircraft engine, such as Figure 1 As shown, it mainly includes:

[0022] Step S1, determining the fuel supply amount at the ignition point before the fuel supply accessory of the field engine is replaced, and taking it as the standard flow value;

[0023] Step S2, respectively selecting the maximum value and the minimum value of the fuel nozzle area control and the lowest value and the highest value of the fuel temperature requirement range for testing, so as to obtain the standard nozzle front and rear pressure difference range under the standard flow value;

[0024] Step S3, after replacing the fuel supply accessories for the external engine, set the fuel supply of the engine to the standard flow value, calculate the pressure difference before and after the nozzle, if the pressure difference before and after the nozzle is within the standard pressure difference before and after the nozzle, the fuel supply of the ignition point is accurate, otherwise the fuel supply of the ignition point is inaccurate.

[0025] According to the fuel flow calculation formula, when the fuel nozzle area (guaranteed by machining accuracy and factory inspection standards) and the fuel temperature (the fuel temperature variation range at the engine ignition point speed is small) are within a certain range, the fuel supply of the fuel supply accessory is only proportional to the square root of the pressure difference before and after the nozzle, that is, when the pressure difference before and after the nozzle increases, the fuel supply also increases; otherwise, it decreases. Therefore, after replacing the fuel supply accessory in the field engine, the applicant sets the engine ignition point given fuel volume as the typical ignition point fuel volume value, measures the pressure difference before and after the nozzle, and determines the accuracy of the fuel supply accessory.

[0026] In some optional implementations, after step S3, the method further includes:

[0027] Step S4, adjusting the adjustment pin of the fuel supply accessory so that the front-to-rear pressure difference of the nozzle is within the range of the front-to-rear pressure difference of the standard nozzle.

[0028] Generally, for fuel supply accessories with small flow rates, they can be adjusted through a single mechanical adjustment pin, that is, the position of the adjustment pin can represent the fuel supply accuracy of the fuel supply accessory. This can ensure the fuel supply accuracy of the fuel supply accessory by determining the fuel supply accuracy of the ignition point, and reduce the workload of field inspections.

[0029] In some optional implementations, in step S3, calculating the pressure difference before and after the nozzle includes:

[0030] The pressure after the nozzle is measured by an onboard measuring point set behind the nozzle;

[0031] The pressure before the nozzle is measured by a test joint arranged before the nozzle;

[0032] The difference between the pressure before the nozzle and the pressure after the nozzle is taken as the pressure difference before and after the nozzle.

[0033] In some optional embodiments, the test connector disposed in front of the nozzle is connected to a sensor for pressure measurement during use, and after the measurement is completed, the test connector is sealed by a plug.

[0034] In some optional embodiments, the test joint in front of the nozzle is connected to the oil supply pipeline in front of the nozzle.

[0035] It should be noted that the pressure behind the nozzle is used to accelerate the fuel supply control, which is a conventional airborne measurement point and can be measured. The nozzle inlet fuel supply pressure can be measured by adding a test joint to the fuel supply pipeline and connecting the sensor when measurement is required. When not measuring, it can be blocked by a plug to prevent fuel leakage, and there is no risk of use.

[0036] The present application provides a means for calibrating the fuel supply accessories of an outfield engine. When the fuel supply accessories of an outfield engine are replaced, the fuel supply accuracy of the fuel supply accessories can be accurately determined through the existing onboard measurement parameters and the measurement parameters that can be achieved by installing sensors, which can effectively guide the calibration of the fuel supply accessories, reduce the use risk of the engine after the fuel supply accessories are replaced, and reduce the adjustment workload when abnormal problems such as stall / surge occur.

[0037] Although the present application has been described in detail above with general descriptions and specific implementation schemes, it is obvious to those skilled in the art that some modifications or improvements may be made to the present application. Therefore, these modifications or improvements made without departing from the spirit of the present application all fall within the scope of protection claimed in the present application.

Claims

1. A method for determining the accuracy of the fuel quantity at the ignition point of an aircraft engine, characterized in that: include: Step S1, determining the fuel supply amount at the ignition point of the field engine before the fuel supply accessory is replaced, and taking it as the standard flow value; Step S2, respectively selecting the maximum value and the minimum value of the fuel nozzle area control and the lowest value and the highest value of the fuel temperature requirement range for testing, so as to obtain the standard nozzle front and rear pressure difference range under the standard flow value; Step S3, after replacing the fuel supply accessories for the external engine, set the fuel supply of the engine to the standard flow value, calculate the pressure difference before and after the nozzle, if the pressure difference before and after the nozzle is within the standard pressure difference before and after the nozzle, the fuel supply of the ignition point is accurate, otherwise the fuel supply of the ignition point is inaccurate.

2. The method for determining the accuracy of the fuel quantity at the ignition point of an aircraft engine according to claim 1, characterized in that: After step S3, the method further comprises: Step S4, adjusting the adjustment pin of the fuel supply accessory so that the front-to-rear pressure difference of the nozzle is within the range of the front-to-rear pressure difference of the standard nozzle.

3. The method for determining the accuracy of the fuel quantity at the ignition point of an aircraft engine according to claim 1, characterized in that: In step S3, calculating the pressure difference before and after the nozzle includes: The pressure after the nozzle is measured by an onboard measuring point set behind the nozzle; The pressure before the nozzle is measured by a test joint arranged before the nozzle; The difference between the pressure before the nozzle and the pressure after the nozzle is taken as the pressure difference before and after the nozzle.

4. The method for determining the accuracy of the fuel quantity at the ignition point of an aircraft engine according to claim 3, characterized in that: The test joint arranged in front of the nozzle is connected to the sensor to measure the pressure when in use. After the measurement is completed, the test joint is blocked by the plug.

5. The method for determining the accuracy of the fuel quantity at the ignition point of an aircraft engine according to claim 3, characterized in that: The test joint in front of the nozzle is connected to the oil supply pipeline in front of the nozzle.

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