A method for determining the cold-running sensitive time period for restarting an aircraft engine

Abstract

The present application belongs to the technical field of determining sensitive time periods for restarting cold operation of aircraft engines, and specifically relates to a method for determining sensitive time periods for restarting cold operation of aircraft engines. The method is designed to obtain a sensitive time period by calculating the time interval range between the maximum vibration peak value exceeding the limit during the restart of the aircraft engine without cold operation and the previous operation, so as to more accurately determine the sensitive time period, greatly reduce the possibility of missing part of the sensitive time period or including an extra insensitive time range, and provide a starting vibration reduction effect as a vibration reduction effect of cold operation when the aircraft engine is restarted within the sensitive time period, so as to guide practice.

Description

Technical Field

[0001] The present application belongs to the technical field of determining a sensitive time period for restarting cold operation of an aircraft engine, and specifically relates to a method for determining a sensitive time period for restarting cold operation of an aircraft engine. Background Art

[0002] When an aircraft engine is restarted, if the time interval between the last operation and the restart is within a sensitive period, the aircraft engine rotor will experience uneven thermal bending due to the uneven temperature field inside the aircraft engine, causing the rotor to become unbalanced and causing the maximum vibration peak to exceed the limit during the aircraft engine startup process.

[0003] Practice has shown that when an aircraft engine is restarted, if the time interval between the last operation and the last operation is within a sensitive period, a cold run before restarting can effectively avoid exceeding the maximum vibration peak during the aircraft engine startup process.

[0004] Currently, sensitive time periods are mostly determined based on experience. For aircraft engines whose restart interval and the time interval between the last operation and the restart interval fall within the sensitive time period, a cold run is performed before starting. This method has low accuracy and is not strict enough. It is easy to miss some sensitive time periods and cannot effectively prevent the maximum vibration peak from exceeding the limit during the start-up of the aircraft engine. It may also include an insensitive time range, which will unnecessarily increase the number of cold runs of the aircraft engine.

[0005] This application is proposed in view of the above-mentioned technical defects.

[0006] It should be noted that the disclosure of the above background technology content is only used to assist in understanding the inventive concept and technical solution of the present invention, and it does not necessarily belong to the prior art of this patent application. In the absence of clear evidence that the above content has been disclosed on the filing date of this application, the above background technology should not be used to evaluate the novelty and creativity of this application. Summary of the Invention

[0007] The purpose of the present application is to provide a method for determining a cold-running sensitive time period for restarting an aircraft engine, so as to overcome or alleviate at least one of the known technical deficiencies.

[0008] The technical solution of this application is:

[0009] A method for determining a cold-running sensitive time period for restarting an aircraft engine comprises:

[0010] Collect test data for the entire aircraft engine. After the aircraft engine is warmed through, restart the aircraft engine at intervals of 30 minutes, starting from 0 minutes, until the interval reaches 4 hours. The aircraft engine should be restarted without cold running. The test procedure should include a minimum warm-up period of 3 minutes. Monitor the maximum vibration peak during the restart process.

[0011] Accumulate routine aircraft engine test data, monitor the maximum vibration peak value during the cold run and restart of the aircraft engine after warm-up operation for more than 3 minutes, and the time interval between the peak value and the previous run;

[0012] Select aircraft engine long-term test data to monitor the maximum vibration peak value during restart of an aircraft engine after warm-up operation for more than 50 hours, with or without cold operation, and the time interval between the maximum vibration peak value and the previous operation;

[0013] The time interval between the maximum vibration peak exceeding the limit during the restart of the aircraft engine without cold operation and the previous operation is counted as the sensitive time period;

[0014] Calculate the average value E1 of the maximum vibration peak value during the restart of the aircraft engine during the sensitive time period without cold operation, and the average value E2 of the maximum vibration peak value during the restart of the cold operation, and use (E1-E2)*100% / E1 as the vibration reduction effect of the cold operation.

[0015] According to at least one embodiment of the present application, in the above-mentioned method for determining the sensitive time period for restarting cold operation of an aircraft engine, when accumulating routine test data of the aircraft engine, the time interval between the restart of the aircraft engine and the previous operation in the samples to be monitored is required to be distributed in the range of 0-4h with an interval of less than 30min.

[0016] This application has at least the following beneficial technical effects:

[0017] A method for determining a sensitive time period for cold operation during restart of an aircraft engine is provided. The method is designed to obtain a sensitive time period by analyzing the time interval range between the previous operation and the maximum vibration peak value exceeding the limit during restart of the aircraft engine without cold operation. The method is used to more accurately determine the sensitive time period and greatly reduce the possibility of missing part of the sensitive time period or including an extra insensitive time range. The method also provides a starting vibration reduction effect, which serves as a vibration reduction effect for cold operation when the aircraft engine is restarted within the sensitive time period, and is used to guide practice. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of a method for determining a sensitive time period for restarting cold operation of an aircraft engine provided in an embodiment of the present application. DETAILED DESCRIPTION

[0019] To make the technical solution and its advantages of the present application clearer, the technical solution of the present application will be described in further detail below in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only some embodiments of the present application and are only used to explain the present application, not to limit the present application. It should be noted that, for ease of description, only the parts related to the present application are shown in the accompanying drawings, and other related parts can refer to the general design. In the absence of conflict, the embodiments of the present application and the technical features in the embodiments can be combined with each other to obtain new embodiments.

[0020] In addition, unless otherwise defined, the technical or scientific terms used in the description of this application should have the ordinary meanings understood by those of ordinary skill in the art to which this application belongs. The words "upper," "lower," "left," "right," "center," "vertical," "horizontal," "inner," and "outer" used in the description of this application are only used to indicate relative directions or positional relationships, and do not imply that the device or component must have a specific orientation, be constructed, or operate in a specific orientation. When the absolute position of the described object changes, its relative positional relationship may also change accordingly. Therefore, they should not be understood as limitations on this application. The words "first," "second," "third," and similar terms used in the description of this application are used only for descriptive purposes to distinguish different components and should not be understood to indicate or imply relative importance. The words "one," "an," or "the" used in the description of this application should not be understood as absolute limitations on quantity, but should be understood as meaning the presence of at least one. The words "include" or "comprises" used in the description of this application mean that the element or object listed before the word includes the elements or objects listed after the word and their equivalents, but does not exclude other elements or objects.

[0021] In addition, it should be noted that, unless otherwise clearly stipulated and limited, the words "install", "connect", "connect" and similar terms used in the description of this application should be understood in a broad sense. For example, the connection can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, an indirect connection through an intermediate medium, or a connection between two components. Technical personnel in the field can understand their specific meanings in this application according to the specific circumstances.

[0022] The following is combined with Figure 1 The method for determining the sensitive time period for restarting cold operation of an aircraft engine proposed in this application is further described in detail. The specific process can be referred to as follows:

[0023] S1 collects special planned test data of the entire aircraft engine and monitors the maximum vibration peak value during the restart of the aircraft engine

[0024] For a new model of aircraft engine, special planning tests are planned starting from the first complete engine. The specific requirements are as follows:

[0025] 1) Select the aircraft engine that was assembled for the second time for testing;

[0026] 2) Start the car at slow speed for the first time and check that all functions of the aircraft engine are normal;

[0027] 3) For subsequent startups, a step-by-step procedure should be prepared in advance. No cold running is allowed before startup. The engine should be at least warmed up. The engine should be run for at least 3 minutes above warm-up, preferably reaching an intermediate state. This will serve as the first valid sub-sample with an interval time of 0 minutes.

[0028] 3) The second effective start-up should be restarted after 30 minutes;

[0029] 4) For subsequent starts, the interval time will be increased by 30 minutes each time, with the maximum interval time being 4 hours;

[0030] 5) If the test cannot be completed continuously, when it is carried out again, a benchmark test with the same procedure as before the test was interrupted shall be added for the first start-up, and the second test shall be used as the valid sub-sample.

[0031] S2 accumulates routine test data of aircraft engines and monitors the maximum vibration peak during the restart of the aircraft engine and the time interval between the maximum vibration peak and the previous operation.

[0032] Before each routine test of an aircraft engine, a cold run is performed. An annual test plan for the aircraft engine is obtained and valid test data is accumulated. The specific requirements are as follows:

[0033] 1) Accumulate regular data of at least 5 times of going on stage, and those who have gone on stage more than 20 times each time will be given priority;

[0034] 2) Select the test data after the warm-up period and running time of more than 3 minutes on the same day as the valid sub-sample;

[0035] 3) Check that the intervals between valid sub-samples are evenly distributed in the range of 0-4 hours, and the time difference between adjacent sub-samples is less than 30 minutes.

[0036] S3 selects aircraft engine long-term test data to monitor the aircraft engine operation for more than 50 hours, with or without cold operation, and the maximum vibration peak value during the restart process and the time interval with the previous operation. For specific selection requirements, refer to S2.

[0037] S4 statistics do not include cold operation. The time interval between the maximum vibration peak value exceeding the limit during the restart of the aircraft engine and the previous operation is used as the sensitive time period. For this sensitive time period, it can be rounded off or slightly expanded or reduced based on daily test experience.

[0038] S5 calculates the average value E1 of the maximum vibration peak value during the restart of the aircraft engine during the sensitive time period without cold operation, and the average value E2 of the maximum vibration peak value during the restart of the cold operation, and uses (E1-E2)*100% / E1 as the vibration reduction effect of the cold operation.

[0039] Regarding the method for determining the sensitive time period for cold operation of an aircraft engine during restart disclosed in the above embodiment, its design is to obtain the sensitive time period by calculating the time interval range with the previous operation corresponding to the maximum vibration peak exceeding the limit during the restart of the aircraft engine without cold operation, so as to more accurately determine the sensitive time period and greatly reduce the possibility of missing part of the sensitive time period or including an extra insensitive time range. The design is also to obtain the sensitive time period by calculating the data of the maximum vibration peak exceeding the limit during the restart of the aircraft engine after cold operation and the corresponding time interval range with the end of the previous operation, and to give the starting vibration reduction effect, which is used as the vibration reduction effect of cold operation when the aircraft engine is restarted within the sensitive time period to guide practice.

[0040] So far, the technical solution of the present application has been described in conjunction with the preferred embodiments shown in the accompanying drawings. Those skilled in the art should understand that the scope of protection of the present application is obviously not limited to these specific embodiments. Without departing from the principles of the present application, those skilled in the art can make equivalent changes or replacements to the relevant technical features, and the technical solutions after these changes or replacements will fall within the scope of protection of the present application.

Claims

1. A method for determining a cold-running sensitive time period for restarting an aircraft engine, characterized in that: include: Collect test data for the entire aircraft engine. After the aircraft engine is warmed through, restart the aircraft engine at intervals of 30 minutes, starting from 0 minutes, until the interval reaches 4 hours. The aircraft engine should be restarted without cold running. The test procedure should include a minimum warm-up period of 3 minutes. Monitor the maximum vibration peak during the restart process. Accumulate routine aircraft engine test data, monitor the maximum vibration peak value during the cold run and restart of the aircraft engine after warm-up operation for more than 3 minutes, and the time interval between the peak value and the previous run; Select aircraft engine long-term test data to monitor the maximum vibration peak value during restart and the time interval between the maximum vibration peak value and the previous vibration peak value after the aircraft engine has been running for more than 50 hours, with or without cold running; The time interval between the maximum vibration peak exceeding the limit during the restart of the aircraft engine without cold operation and the previous operation is counted as the sensitive time period; Calculate the average value E1 of the maximum vibration peak value during the restart of the aircraft engine during the sensitive time period without cold operation, and the average value E2 of the maximum vibration peak value during the restart of the cold operation, and use (E1-E2)*100% / E1 as the vibration reduction effect of the cold operation.

2. The method for determining the aircraft engine restart cold operation sensitive time period according to claim 1, characterized in that: When accumulating the conventional test data of the aircraft engine, it is required that in the monitored samples, the time interval between the restart of the aircraft engine and the previous operation is distributed within the range of 0-4 hours at intervals of less than 30 minutes.

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