A method for compiling load spectrum for acceleration mission test considering heating and pressurization

Abstract

The present invention discloses a method for compiling an acceleration task test load spectrum taking heating and pressurization into consideration, taking a long-term life test spectrum without considering heating and pressurization as basic compilation data, and calculating and analyzing the corresponding turbine front inlet temperature when the engine speed reaches the maximum speed under the conditions of increasing the inlet total temperature and total pressure according to the engine performance model; according to the engine temperature limit condition, the corresponding inlet total temperature and total pressure when the turbine front inlet temperature reaches the temperature limit value are used as the final determined single-stage total temperature spectrum and single-stage total pressure spectrum; then, according to the engine performance model, the speed of the long-term life test spectrum with heating and pressurization is corrected, so that the damage of the long-term life test spectrum taking heating and pressurization into consideration is equivalent to that of the long-term life test spectrum without considering heating and pressurization; then, based on the characteristic load damage acceleration method such as low-cycle fatigue, creep, thermal fatigue, etc., the acceleration task test spectrum is compiled under the premise of damage equivalence, and finally the whole machine test is carried out.

Description

Technical Field

[0001] The present invention relates to the technical field of aircraft engine load spectrum compilation, in particular to a method for compiling an acceleration mission test load spectrum taking heating and pressurization into consideration. Background Art

[0002] With the rapid advancement of aviation technology, the service life of aircraft engines has gradually increased. Currently, the service life of mainstream fighter aircraft engines worldwide has exceeded 1,000 hours. For example, the latest modified version of the domestically produced WS10 engine has a service life of 3,000 hours, and the service life of civilian engines has even reached tens of thousands of hours. If a full-life test is conducted, the test cycle will last for months or even years, which will greatly extend the time it takes for an aircraft engine to be finalized and put into service, restricting the possibility of continuous engine modifications. At the same time, the long test period also increases the possibility of test failures due to external factors. More importantly, engines used in the field continue to experience faults that were not discovered during the full-life test, endangering the engine's safety and increasing its maintenance costs.

[0003] Modern aircraft engines operate in increasingly wide airspaces and speed ranges, experiencing diverse temperature / pressure conditions in actual service. These changes in inlet temperature / pressure can lead to variations in engine performance and mechanical and thermal loads on hot-end components, ultimately impacting their lifespan. Furthermore, extreme temperature / stress conditions exist within the engine's flight envelope. These conditions rarely occur in actual flight but offer significant safety benefits. However, traditional accelerated flight tests often struggle to assess these varying inlet temperature / pressure conditions. Therefore, research is needed to develop a methodology for compiling accelerated mission endurance test profiles with heating and pressurization. Due to hardware limitations, current engine life test methods used in my country lack the capability to conduct accelerated simulated flight endurance tests with heating and pressurization, and the methodology for compiling test profiles that incorporate heating and pressurization remains unclear. To support future aircraft engine life test needs in my country, research is being conducted on a methodology for compiling load profiles for accelerated simulated flight endurance tests that incorporate heating and pressurization.

[0004] In summary, the current method for compiling accelerated mission test spectra is performed under static conditions on a ground test bench. Such static conditions are insufficient to detect failure modes that may only occur under pressure or temperature, making it difficult to assess the operating life of aircraft engines under varying inlet temperature and pressure conditions. This is a critical engineering issue that urgently needs to be addressed and is of great significance to the research on complete aircraft engine testing in actual engineering applications.

[0005] Therefore, it is necessary to develop a compilation of accelerated mission test load spectrum that can take into account changes in import conditions, laying the foundation for aircraft engine life testing. Summary of the Invention

[0006] To address the existing problem of engine acceleration mission testing failing to effectively assess inlet temperature and pressure conditions, this paper provides a method for compiling a spectrum for an acceleration mission test with heating and pressurization. This method is intuitive and clear, ensuring consistent load characteristics and damage after varying inlet conditions. This provides a research foundation for whole-machine testing of complex mechanical components in actual engineering applications and represents an important step in evaluating the lifespan of complex mechanical components under actual service loads.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] The present invention is a method for compiling a load spectrum for an acceleration task test considering heating and pressurization, which is characterized by comprising the following steps:

[0009] Step 1: Based on the spectrum data of the long-term life test spectrum without considering heating and pressurization, according to the engine performance model, calculate and analyze the corresponding turbine inlet temperature when the engine speed reaches the maximum speed under the conditions of increasing the inlet total temperature and total pressure;

[0010] Step 2: Based on the engine temperature limit condition, the corresponding inlet total temperature and total pressure when the turbine inlet temperature reaches the limit value are used as the final single-stage total temperature spectrum and single-stage total pressure spectrum;

[0011] Step 3: Using the single-stage total temperature spectrum, single-stage total pressure spectrum, and long-term life test spectrum obtained in step 2 as input data, the temperature spectrum and stress spectrum of key components considering heating and pressurization are obtained based on the engine performance model;

[0012] Step 4: Compare the temperature spectrum and stress spectrum of the key components considering heating and pressurization with the temperature spectrum and stress spectrum corresponding to the long test spectrum without considering heating and pressurization. According to the damage accumulation calculation formula, the long test spectrum is repeatedly iteratively corrected to ensure that the stress spectrum and temperature spectrum corresponding to the long test spectrum considering heating and pressurization are consistent with the stress spectrum and temperature spectrum without considering heating and pressurization, thereby obtaining the long-term life test spectrum considering heating and pressurization;

[0013] Step 5: Based on the stress spectrum and temperature spectrum corresponding to the long-term life test spectrum considering heating and pressurization obtained in Step 4, the stress spectrum is equivalently converted to the stress spectrum at the limit temperature using the damage consistency formula;

[0014] Step 6: Perform rain flow counting on the stress spectrum obtained in step 5 to count the low-cycle fatigue load damage, and extract creep load and thermal fatigue load by combining the stress spectrum with the temperature spectrum;

[0015] Step 7: According to the characteristic load equivalent acceleration method, the low-cycle fatigue corresponding to the secondary cycle is converted into an slow-maximum-slow cycle, and the creep load corresponding to the low-power state is converted to the high-power state. For the thermal fatigue load, the throttle lever switching rate needs to be kept consistent with the long test spectrum, and an acceleration task test spectrum that takes into account heating and pressurization is compiled.

[0016] A further improvement of the present invention is that: the step 1 is specifically:

[0017] Step 1.1: Establish an engine performance model that matches the test engine's operating performance through machine learning or component-level model building;

[0018] In step 1.2, the spectrum data of the long-term life test spectrum without considering heating and pressurization is input into the engine performance model, and the corresponding turbine inlet temperature when the engine speed reaches the maximum speed is calculated and analyzed under the conditions of increasing the inlet total temperature and total pressure at different ratios.

[0019] A further improvement of the present invention is that in step 2, the temperature limit conditions of the engine are obtained by consulting the manual to determine the temperature limit of the materials of each component of the engine, and performing comparative analysis.

[0020] A further improvement of the present invention is that: the step 6 is specifically:

[0021] Step 6.1: Filter the peak and valley values ​​in the middle section of the stress spectrum in sequence. Starting from the first peak and valley value point, determine whether the rise or fall of the adjacent peak and valley value points meets the set threshold. Those with a value less than the threshold are retained, and those with a value greater than the threshold are removed.

[0022] Step 6.2: Determine whether the value of the last point of the rainflow filter spectrum is the same as the first point. If not, add a point with the same value as the last point of the original load spectrum to obtain the initial rainflow filter spectrum.

[0023] Step 6.3: Use the judgment method to add several points of the original load spectrum. The added points must satisfy the requirement that only rising points are allowed on the rising edge and only falling points are allowed on the falling edge to obtain the final rainflow filter spectrum.

[0024] In step 6.4, creep load and thermal fatigue load are extracted by combining stress spectrum and temperature spectrum according to creep load extraction principle and thermal fatigue load extraction principle.

[0025] A further improvement of the present invention is that the threshold of the rainflow filter in step 6.1 is determined according to the following formula:

[0026] Δ%=(G max -G min )×10%

[0027] Among them, Δ% is the rain flow filter threshold, G maxis the maximum value in the load history, G min is the minimum amplitude in the load history.

[0028] The beneficial effects of the present invention are as follows: based on the spectrum data of long-term life test spectra without considering heating and pressurization, the present invention matches and combines multi-parameter loads according to typical load cycles, thereby compiling a multi-parameter fatigue test spectrum with damage consistency as the optimization goal. Compared with existing multi-parameter fatigue test spectrum compilation methods, the beneficial effects are:

[0029] (1) By increasing the temperature of the gas before the turbine by heating and pressurizing, the acceleration coefficient is increased, which saves test time and reduces test costs;

[0030] (2) Fully assessing the engine's service life under wide airspace and speed range conditions resolves safety issues and allows potential service problems to be exposed in advance to a greater extent, enabling them to be identified and corrected in a timely manner on the test bench.

[0031] In summary, the present invention provides a basis for analyzing the accelerated mission test evaluation of aircraft engine complete machines and components in actual engineering, and provides a basis for damage analysis of aircraft engine complete machines and components simulating actual service environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Implementation flow chart of the present invention.

[0033] Figure 2 The speed spectrum of long-term life test without considering heating and pressurization.

[0034] Figure 3 Stress spectrum of a turboshaft engine turbine disk.

[0035] Figure 4 Consider the speed spectrum of long-term life test with heating and pressurization.

[0036] Figure 5 Acceleration task test spectrum without considering heating and pressurization.

[0037] Figure 6 Consider the accelerated task test spectrum with heating and pressurization. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0039] The present invention provides a method for compiling an acceleration mission test load spectrum that considers heating and pressurization. The specific steps are as follows: Step 1, based on the spectrum data of a long-term life test spectrum that does not consider heating and pressurization, according to the engine performance model, calculate and analyze the corresponding turbine inlet temperature when the engine speed reaches the maximum speed under the conditions of increasing the inlet total temperature and total pressure;

[0040] Step 1 The specific steps are:

[0041] Step 1.1: Establish an engine performance model that meets the required performance of a turboshaft engine through machine learning;

[0042] Step 1.2, input the spectrum data of the long-term life test spectrum without considering heating and pressurization into the engine performance model, and calculate and analyze the corresponding turbine inlet temperature when the engine speed reaches the maximum speed under the conditions of increasing the inlet total temperature and total pressure at different ratios. Figure 1 shown.

[0043] Step 2: Based on the engine temperature limit condition, the corresponding inlet total temperature and total pressure when the turbine inlet temperature reaches the limit value are used as the final single-stage total temperature spectrum and single-stage total pressure spectrum;

[0044] Step 2:

[0045] Step 2.1: The engine temperature limit is mainly determined by the temperature limit of the engine component materials. In this embodiment, the high-pressure turbine disk of the turboshaft engine is made of GH4169, and the material limit temperature is determined to be 826°C by consulting the manual. By comparison and analysis, the engine temperature limit is obtained.

[0046] In step 2.2, by comparing the turbine inlet temperature obtained by increasing the inlet total temperature and total pressure by different proportions with that obtained in step 1, the inlet total temperature and total pressure corresponding to the time when the turbine inlet temperature reaches the temperature limit are used as the final single-stage total temperature spectrum and single-stage total pressure spectrum, and the temperature increase ratio is 8%.

[0047] Step 3: Input the single-stage total temperature spectrum, single-stage total pressure spectrum, and long-term life test spectrum obtained in step 2.2 into the engine performance model to obtain the temperature spectrum and stress spectrum of key components considering heating and pressurization;

[0048] Step 4: Compare the temperature spectrum and stress spectrum of the key parts considering heating and pressurization with the temperature spectrum and stress spectrum corresponding to the long test spectrum without considering heating and pressurization, and iteratively correct the long test spectrum so that the stress spectrum and temperature spectrum corresponding to the long test spectrum considering heating and pressurization are consistent with the stress spectrum and temperature spectrum without considering heating and pressurization, and obtain the long-term life test spectrum considering heating and pressurization, such as Figure 2 As shown;

[0049] Step 5: Based on the stress spectrum and temperature spectrum corresponding to the long-term life test spectrum considering heating and pressurization obtained in step 4, the stress spectrum is equivalently converted to the stress spectrum at the limit temperature using the damage consistency formula. The stress spectrum is as follows: Figure 3 As shown;

[0050] Step 6: Filter the peak and valley values ​​of the middle section of the stress spectrum obtained in step 5 in sequence, and then, starting from the first peak and valley value point, determine whether the rise or fall of the adjacent peak and valley value points meets the set threshold. If it is less than the threshold, retain it, and if it is greater than the threshold, remove it. Determine whether the value of the last point of the rain flow filter spectrum is the same as the first point. If not, add a point with the same value as the last point of the original load spectrum to the end to obtain the initial rain flow filter spectrum. Secondly, use the judgment method to add several points of the original load spectrum. The added points meet the requirement that the added points on the rising edge are only allowed to rise, and the added points on the falling edge are only allowed to fall, to obtain the final rain flow filter spectrum.

[0051] The rain flow filter threshold is determined according to the following formula:

[0052] Δ%=(G max -G min )×10%

[0053] Among them, Δ% is the rain flow filter threshold, G max is the maximum value in the load history, G min is the minimum amplitude in the load history.

[0054] According to the creep load extraction principle and thermal fatigue load extraction principle, creep load and thermal fatigue load are extracted by combining stress spectrum and temperature spectrum.

[0055] (7) According to the characteristic load equivalent acceleration method, the low cycle fatigue corresponding to the secondary cycle is converted into the slow-maximum-slow cycle, and the creep load corresponding to the low power state is converted to the high power state. For the thermal fatigue load, the throttle lever switching rate needs to be kept consistent with the long test spectrum. Table 1 shows the temperature and load duration data corresponding to the original load and the load after heating. Finally, the acceleration task test spectrum considering heating and pressurization is compiled, as shown in Figure 4 Comparing the long test spectrum and acceleration spectrum of the accelerated task test with heating and pressurization and the accelerated task test, the acceleration coefficients of the two are calculated to be 3.82 and 3.29 respectively. It can be seen that the test time of each task segment has been significantly shortened and the acceleration coefficient has been improved.

[0056] Table 1 Comparison of temperature and load duration data corresponding to original load and heated load

[0057]

[0058]

[0059] The above description is only a specific embodiment of the present invention, and further details the purpose, technical solutions and beneficial effects of the present invention. Finally, it should be noted that the above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. For researchers and technicians in this technical field, without departing from the scope of the technical solution of the present invention, non-innovative embellishments, changes and modifications made to the technical solution of the present invention using the above content should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for compiling a load spectrum for an acceleration task test considering heating and pressurization, characterized by: The steps include: Step 1: Based on the spectrum data of the long-term life test spectrum without considering heating and pressurization, according to the engine performance model, calculate and analyze the corresponding turbine inlet temperature when the engine speed reaches the maximum speed under the conditions of increasing the inlet total temperature and total pressure; Step 2: Based on the engine temperature limit condition, the corresponding inlet total temperature and total pressure when the turbine inlet temperature reaches the limit value are used as the final single-stage total temperature spectrum and single-stage total pressure spectrum; Step 3: Using the single-stage total temperature spectrum, single-stage total pressure spectrum, and long-term life test spectrum obtained in step 2 as input data, the temperature spectrum and stress spectrum of key components considering heating and pressurization are obtained based on the engine performance model; Step 4: Compare the temperature spectrum and stress spectrum of the key components considering heating and pressurization with the temperature spectrum and stress spectrum corresponding to the long test spectrum without considering heating and pressurization. According to the damage accumulation calculation formula, the long test spectrum is repeatedly iteratively corrected to ensure that the stress spectrum and temperature spectrum corresponding to the long test spectrum considering heating and pressurization are consistent with the stress spectrum and temperature spectrum without considering heating and pressurization, thereby obtaining the long-term life test spectrum considering heating and pressurization; Step 5: Based on the stress spectrum and temperature spectrum corresponding to the long-term life test spectrum considering heating and pressurization obtained in Step 4, the stress spectrum is equivalently converted to the stress spectrum at the limit temperature using the damage consistency formula; Step 6: Perform rain flow counting on the stress spectrum obtained in step 5 to count the low-cycle fatigue load damage, and extract creep load and thermal fatigue load by combining the stress spectrum with the temperature spectrum; Step 7: According to the characteristic load equivalent acceleration method, the low-cycle fatigue corresponding to the secondary cycle is converted into an slow-maximum-slow cycle, and the creep load corresponding to the low-power state is converted to the high-power state. For the thermal fatigue load, the throttle lever switching rate needs to be kept consistent with the long test spectrum, and an acceleration task test spectrum that takes into account heating and pressurization is compiled.

2. The method for compiling a load spectrum for an acceleration task test considering heating and pressurization according to claim 1, characterized in that: The step 1 is specifically as follows: Step 1.1: Establish an engine performance model that matches the test engine's operating performance through machine learning or component-level model building; In step 1.2, the spectrum data of the long-term life test spectrum without considering heating and pressurization is input into the engine performance model, and the corresponding turbine inlet temperature when the engine speed reaches the maximum speed is calculated and analyzed under the conditions of increasing the inlet total temperature and total pressure at different ratios.

3. The method for compiling a load spectrum for an acceleration task test considering heating and pressurization according to claim 1, characterized in that: In step 2, the temperature limit conditions of the engine are obtained by consulting the manual to determine the temperature limit of the materials of each component of the engine, and performing comparative analysis.

4. The method for compiling a load spectrum for an acceleration task test considering heating and pressurization according to claim 1, characterized in that: The step 6 is specifically as follows: Step 6.1: Filter the peak and valley values ​​in the middle section of the stress spectrum in sequence. Starting from the first peak and valley value point, determine whether the rise or fall of the adjacent peak and valley value points meets the set threshold. Those with a value less than the threshold are retained, and those with a value greater than the threshold are removed. Step 6.2: Determine whether the value of the last point of the rainflow filter spectrum is the same as the first point. If not, add a point with the same value as the last point of the original load spectrum to obtain the initial rainflow filter spectrum. Step 6.3: Use the judgment method to add several points of the original load spectrum. The added points must satisfy the requirement that only rising points are allowed on the rising edge and only falling points are allowed on the falling edge to obtain the final rainflow filter spectrum. In step 6.4, creep load and thermal fatigue load are extracted by combining stress spectrum and temperature spectrum according to creep load extraction principle and thermal fatigue load extraction principle.

5. The method for compiling a load spectrum for an acceleration task test considering heating and pressurization according to claim 4, characterized in that: The threshold of the rainflow filter in step 6.1 is determined according to the following formula: Δ%=(G max -G min )×10% Among them, Δ% is the rain flow filter threshold, G max is the maximum value in the load history, G min is the minimum amplitude in the load history.

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