A control method for endurance test of an aero turboshaft engine with intake heating

Abstract

The application provides a kind of aviation turboshaft engine endurance test state control method using air intake heating, comprising the following steps: step one, obtaining engine acceptance delivery performance state;Step two, adjusting the performance of the engine;Step three, obtaining the temperature characteristics of the engine under the condition of air intake heating;Step four, obtaining the speed characteristics of the engine near take-off state;Step five, determine the endurance test control parameter;Step six, execute endurance test.The aviation turboshaft engine endurance test state control method using air intake heating of the application can ensure that power and turbine temperature reach at the same time during endurance test examination, and can fully examine without over-examination.

Description

Technical Field

[0001] This invention relates to the field of aircraft turboshaft engine testing technology, and in particular to a method for controlling the sustained test conditions of an aircraft turboshaft engine using intake air heating. Background Technology

[0002] The "General Specifications for Aircraft Turboprop and Turboshaft Engines" stipulates endurance testing as part of the pre-initial flight tests, design finalization tests, and production finalization tests to ensure flight safety. This endurance testing is a comprehensive assessment of the engine's structural integrity. Due to its heavy load and stringent requirements, it is considered the most important and difficult test to pass in the development of aero-engines.

[0003] The "General Specifications for Aircraft Turboprop and Turboshaft Engines" requires that, to fully assess the temperature resistance of the engine's hot-end components, "engine testing should be conducted with the turbine temperature equal to the maximum permissible steady-state exhaust gas temperature at each power setting." Please refer to [link to relevant documentation]. Figures 1a-1c However, the following technical challenges exist in the current experimental implementation process: First, the engine's delivery performance characteristics do not match the assessment requirements. Before entering sustained testing, the engine must meet acceptance delivery requirements. An accepted engine typically exhibits the following characteristics: output power higher than the target value, and turbine temperature lower than the target value. However, sustained testing requires: output power ≥ the target value, and turbine temperature ≥ the target value. There is a contradiction: if the turbine temperature is brought to the target value by increasing fuel flow, the output power will already far exceed the target value, causing the engine to fail the test.

[0004] Second, traditional auxiliary methods have shortcomings. To ensure that prolonged testing is both thorough and effective, auxiliary methods such as engine bleed air and power extraction are typically used to increase turbine temperature during the test. However, engine bleed air often leads to uneven temperature distribution at the combustion chamber outlet, and even localized high-temperature zones in the combustion chamber and turbine components, causing damage to hot-end components, especially severe turbine rotor creep, which poses a safety hazard. Power extraction can only slightly adjust turbine temperature, and its effect is not significant.

[0005] Third, performance degradation during testing makes control more difficult. As prolonged testing continues, engine performance will decline, and turbine temperature will gradually rise, making it more difficult to simultaneously control power and turbine temperature to meet performance targets.

[0006] Therefore, there is an urgent need to develop a control method that can ensure that power and turbine temperature reach the target simultaneously and without failing the test during sustained test runs. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of existing technologies by proposing a method for controlling the sustained test state of an aero-engine turboshaft engine using intake air heating. By adjusting the engine performance before the sustained test and combining precise calculations of intake air heating characteristics and speed characteristics, the output power and turbine temperature can be synchronously achieved to meet the test targets during the sustained test, ensuring that the test is both sufficient and does not exceed the test requirements.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a method for controlling the sustained test conditions of an aero-engine turboshaft engine using intake air heating, comprising the following steps: Step 1: Obtain the engine acceptance and delivery performance status: Under the reference atmospheric temperature conditions, obtain the actual output power Psda and turbine temperature T4a of the engine in the takeoff state. The actual output power Psda is higher than the target value Psd, and the actual turbine temperature T4a is lower than the target value T4. Step 2: Adjust the engine performance: Adjust the engine structural parameters so that the turbine temperature of the engine in the takeoff state reaches the specified index value T4, the output power increases to the measured Psda, and the measured Psdb > the Psd index. Record the measured output power Psda and the measured turbine temperature T4b in the takeoff state after the performance adjustment. Step 3: Obtain the engine temperature characteristics under intake air heating conditions: During takeoff, keep the engine speed constant, turn on the intake air heating device, and measure the engine output power and turbine temperature under multiple different intake air temperature T0 conditions to obtain the relationship function between intake air temperature and output power Psd(T0)=F1(T0) and the relationship function between intake air temperature and turbine temperature T4(T0)=F2(T0). Step 4: Obtain the engine speed characteristics near takeoff: In takeoff, reduce the fuel flow to lower the engine speed ng to multiple different speed points, measure the output power and turbine temperature at each speed point, and obtain the relationship function between speed and output power Psd(ng)=G1(ng) and the relationship function between speed and turbine temperature T4(ng)=G2(ng). Step 5: Determine the control parameters for sustained test run: Based on the measured Psdb and T4b data from Step 2, and the relationship functions obtained from Steps 3 and 4, calculate the intake air heating temperature T0 and engine control speed ng by simultaneously solving the following equations: Power balance equation: Psdb measured - F1(T0) + Psdb measured - G1(ng) = Psdb measured - Psd index; Temperature balance equation: F2(T0) - T4b measured = T4b measured - G2(ng); Step Six: Perform a sustained test run: After the engine reaches takeoff status, turn on the intake air heating device to make the intake air temperature reach the specified T0, and control the fuel supply to reduce the engine speed to the specified ng, so that the engine output power and turbine temperature reach the target value synchronously.

[0009] Furthermore, in step two, the engine structural parameters include at least one of the following: compressor guide vane angle, turbine throat area, and exhaust nozzle area.

[0010] Furthermore, in step two, when adjusting the performance by adjusting the turbine throat area as an example, the following steps are included: Within ±5% of the takeoff state, obtain the linear proportional relationship between the turbine throat area adjustment δAHP and the output power change δPsd and turbine temperature change δT4: δPsd=k1×δAHP, δT4=k2×δAHP, where k1 and k2 are proportionality coefficients. Based on the measured turbine temperature T4a in step one, calculate the required turbine temperature increase δT4 = T4 index - T4a measured. Calculate the turbine throat area adjustment amount δAHP=δT4 / k2; After adjusting the turbine throat area according to the δAHP, the engine performance was re-recorded to verify that the turbine temperature reached the T4 index and the output power reached the measured Psdb.

[0011] Furthermore, in step three, the temperature characteristic function Psd(T0) = F1(T0) is a monotonically decreasing function, and the temperature characteristic function T4(T0) = F2(T0) is a monotonically increasing function.

[0012] Furthermore, in step three, the multiple different intake temperatures T0 are multiple temperature points within the range of 16°C to 50°C. After each temperature point has been operating stably for 3 minutes, the power and turbine temperature are measured.

[0013] Furthermore, in step four, the speed characteristic functions Psd(ng) = G1(ng) and T4(ng) = G2(ng) are both monotonically increasing functions.

[0014] Furthermore, in step four, the multiple different speed points are 99.5%, 99%, 98.5%, and 98% of the engine speed ng. After each speed point has been running stably for 3 minutes, the power and turbine temperature are measured.

[0015] Furthermore, in step two, the performance adjustment step can be repeated until the engine turbine temperature reaches the target value T4.

[0016] Furthermore, the reference atmospheric temperature is 15°C.

[0017] Furthermore, the method is applicable to the dual-parameter synchronous control of takeoff power and turbine temperature during sustained test runs of aircraft turbine shaft engines.

[0018] Compared with the prior art, the advantages and positive effects of the present invention are as follows: First, it achieves precise synchronization of power output and turbine temperature to meet the target. Through a combined control path of "performance adjustment - intake air heating to increase temperature and reduce power - speed reduction to decrease temperature and reduce power", and through precise calculation of two balance equations, the engine output power and turbine temperature can reach the target value simultaneously during sustained test run and takeoff. This solves the contradiction in traditional methods where "power meets the target but temperature does not, and temperature meets the target but power exceeds the test."

[0019] Second, it avoids localized overheating damage to hot-end components. By using intake air heating to increase turbine temperature without altering the internal flow field distribution of the engine, it avoids the problems of uneven combustion chamber outlet temperature distribution and localized high-temperature zones caused by engine bleed air methods. This effectively reduces the risk of high-temperature creep in the turbine rotor and extends the service life of hot-end components.

[0020] Third, the test conditions are highly controllable. By pre-recording the engine's temperature and speed characteristics and establishing an accurate mathematical model, personalized control parameters can be calculated for the specific performance state of each engine. This is unaffected by individual engine performance differences or performance degradation during the test, and offers good operability and repeatability.

[0021] Fourth, it has strong versatility. This invention is not only applicable to aircraft turboshaft engines, but can also be extended to the sustained test of other types of aircraft engines, and has broad application prospects. Attached Figure Description

[0022] Figure 1a This is a schematic diagram illustrating the ideal state in existing technologies where both power and turbine temperature meet the requirements. Figure 1b A schematic diagram showing the power and turbine temperature status of a qualified engine in the prior art; Figure 1c This is a schematic diagram illustrating how increasing fuel flow can alter power and turbine temperature in existing technologies. Figure 2 This is a schematic diagram illustrating the changes in engine power and turbine temperature when using the method of the present invention; Figure 3 This is a schematic diagram showing the changes in power and turbine temperature during sustained engine testing using the method of the present invention. Figure 4 This is a schematic diagram of the temperature characteristics of the engine during takeoff. Figure 5This is a schematic diagram of the engine speed characteristic curve below the takeoff state; Figure 6a A schematic diagram showing the power and turbine temperature status of an engine to ensure it is delivered to a qualified standard. Figure 6b This is a schematic diagram showing the power and turbine temperature of the engine after performance adjustment according to the present invention. Figure 7 A comparison chart of creep values ​​of gas turbine blades in one embodiment (red represents subsample A of engine A, and blue represents subsample B of engine B). Figure 8 Metallographic diagram of the middle section of the blade of engine A, according to one embodiment; and Figure 9 The metallographic structure of the middle part of the blade of engine B is shown in one embodiment. Detailed Implementation

[0023] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention, and therefore only show the components relevant to the invention.

[0024] Please see Figure 2-6b This invention provides a method for controlling the sustained test state of an aero-engine turboshaft engine using intake air heating, comprising the following steps: Step 1: Obtain the engine acceptance and delivery performance status: Under the reference atmospheric temperature conditions, obtain the actual output power Psda and turbine temperature T4a of the engine in the takeoff state. The actual output power Psda is higher than the target value Psd, and the actual turbine temperature T4a is lower than the target value T4. Step 2: Adjust the engine performance: Adjust the engine structural parameters so that the turbine temperature of the engine in the takeoff state reaches the specified index value T4, the output power increases to the measured Psda, and the measured Psdb > the Psd index. Record the measured output power Psda and the measured turbine temperature T4b in the takeoff state after the performance adjustment. Step 3: Obtain the engine temperature characteristics under intake air heating conditions: During takeoff, keep the engine speed constant, turn on the intake air heating device, and measure the engine output power and turbine temperature under multiple different intake air temperature T0 conditions to obtain the relationship function between intake air temperature and output power Psd(T0)=F1(T0) and the relationship function between intake air temperature and turbine temperature T4(T0)=F2(T0). Step 4: Obtain the engine speed characteristics near takeoff: In takeoff, reduce the fuel flow to lower the engine speed ng to multiple different speed points, measure the output power and turbine temperature at each speed point, and obtain the relationship function between speed and output power Psd(ng)=G1(ng) and the relationship function between speed and turbine temperature T4(ng)=G2(ng). Step 5: Determine the control parameters for sustained test run: Based on the measured Psdb and T4b data from Step 2, and the relationship functions obtained from Steps 3 and 4, calculate the intake air heating temperature T0 and engine control speed ng by simultaneously solving the following equations: Power balance equation: Psdb measured - F1(T0) + Psdb measured - G1(ng) = Psdb measured - Psd index; Temperature balance equation: F2(T0) - T4b measured = T4b measured - G2(ng); Step Six: Perform a sustained test run: After the engine reaches takeoff status, turn on the intake air heating device to make the intake air temperature reach the specified T0, and control the fuel supply to reduce the engine speed to the specified ng, so that the engine output power and turbine temperature reach the target value synchronously.

[0025] Furthermore, in step two, the engine structural parameters include at least one of the following: compressor guide vane angle, turbine throat area, and exhaust nozzle area.

[0026] Furthermore, in step two, when adjusting the performance by adjusting the turbine throat area as an example, the following steps are included: Within ±5% of the takeoff state, obtain the linear proportional relationship between the turbine throat area adjustment δAHP and the output power change δPsd and turbine temperature change δT4: δPsd=k1×δAHP, δT4=k2×δAHP, where k1 and k2 are proportionality coefficients. Based on the measured turbine temperature T4a in step one, calculate the required turbine temperature increase δT4 = T4 index - T4a measured. Calculate the turbine throat area adjustment amount δAHP=δT4 / k2; After adjusting the turbine throat area according to the δAHP, the engine performance was re-recorded to verify that the turbine temperature reached the T4 index and the output power reached the measured Psdb.

[0027] Furthermore, in step three, the temperature characteristic function Psd(T0) = F1(T0) is a monotonically decreasing function, and the temperature characteristic function T4(T0) = F2(T0) is a monotonically increasing function.

[0028] Furthermore, in step three, the multiple different intake temperatures T0 are multiple temperature points within the range of 16°C to 50°C. After each temperature point has been operating stably for 3 minutes, the power and turbine temperature are measured.

[0029] Furthermore, in step four, the speed characteristic functions Psd(ng) = G1(ng) and T4(ng) = G2(ng) are both monotonically increasing functions.

[0030] Furthermore, in step four, the multiple different speed points are 99.5%, 99%, 98.5%, and 98% of the engine speed ng. After each speed point has been running stably for 3 minutes, the power and turbine temperature are measured.

[0031] Furthermore, in step two, the performance adjustment step can be repeated until the engine turbine temperature reaches the target value T4.

[0032] Furthermore, the reference atmospheric temperature is 15°C.

[0033] Furthermore, the method is applicable to the dual-parameter synchronous control of takeoff power and turbine temperature during sustained test runs of aircraft turbine shaft engines.

[0034] Specifically, this invention provides a method for controlling the sustained test state of an aero-engine using intake air heating, comprising the following steps: Step 1: Obtain the engine's performance status upon acceptance and delivery.

[0035] Under baseline atmospheric temperature conditions (15℃), the measured output power Psda and turbine temperature T4a of the engine during takeoff were recorded. For engines that pass acceptance testing and delivery, the measured output power Psda is higher than the target value Psd, and the measured turbine temperature T4a is lower than the target value T4.

[0036] Step 2: Adjust the engine performance.

[0037] The engine performance was adjusted so that the turbine temperature during takeoff reached the target value T4, and the output power increased to the measured value Psdb, with the measured value Psdb > the target value Psd.

[0038] Specifically, performance can be adjusted by modifying structural parameters such as the compressor guide vane angle, turbine throat area, or exhaust nozzle area. Taking the adjustment of the turbine throat area (AHP) as an example: Within ±5% of the takeoff state, the turbine throat area adjustment δAHP is linearly proportional to the output power change δPsd and the turbine temperature change δT4: δPsd=k1×δAHP, δT4=k2×δAHP.

[0039] Based on the measured turbine temperature T4a from step one, the required turbine temperature increase δT4 is calculated as: T4 target - measured T4a. Then, the turbine throat area adjustment δAHP is calculated as: δT4 / k2. After adjusting the turbine throat area according to this amount, the engine is reassembled and its performance is recorded on a test bench to verify that the turbine temperature reaches the T4 target and the output power reaches the measured Psdb.

[0040] Understandably, this step can be repeated until the engine turbine temperature reaches the target value T4.

[0041] Step 3: Obtain the temperature characteristics of the engine under intake air heating conditions.

[0042] According to engine principles, when the intake air temperature rises, the output power decreases and the turbine temperature rises. During takeoff, while maintaining a constant engine speed (ng), the intake air heating device was activated. The engine's output power and turbine temperature were measured at multiple different intake air temperatures (T0) (e.g., multiple temperature points within the range of 16°C to 50°C). Data was recorded after each temperature point had been operating stably for 3 minutes.

[0043] This yields the relationship functions between intake air temperature and output power: Psd(T0) = F1(T0) and T4(T0) = F2(T0). Psd(T0) = F1(T0) is a monotonically decreasing function, and T4(T0) = F2(T0) is a monotonically increasing function.

[0044] Step 4: Obtain the engine speed characteristics near takeoff.

[0045] During takeoff, the engine speed ng was reduced to several different speed points (e.g., 99.5%, 99%, 98.5%, 98%) by reducing the fuel flow. The engine operated stably at each speed point for 3 minutes, and the output power and turbine temperature at each speed point were measured.

[0046] This yields the relationship between rotational speed and output power, Psd(ng) = G1(ng), and the relationship between rotational speed and turbine temperature, T4(ng) = G2(ng). Both Psd(ng) = G1(ng) and T4(ng) = G2(ng) are monotonically increasing functions.

[0047] Step 5: Determine the control parameters for sustained test runs.

[0048] Based on the measured Psdb and T4b data from step two, and the relational functions obtained from steps three and four, the intake air heating temperature T0 and engine control speed ng are calculated by simultaneously solving the following equations: Power balance equation: Psdb measured - F1(T0) + Psdb measured - G1(ng) = Psdb measured - Psd index; Temperature balance equation: F2(T0) - T4b measured = T4b measured - G2(ng).

[0049] The physical meaning of the power balance equation is: the sum of the power reduction of the engine after performance adjustment Psdb after intake air heating to T0 [Psdb measured - F1 (T0)] and the power reduction after speed reduction to ng [Psdb measured - G1 (ng)] is equal to the total power reduction [Psdb measured - Psd index].

[0050] The physical meaning of the temperature balance equation is: the increase in turbine temperature [F2(T0) - T4b measured] caused by heating the intake air to T0 is offset by the decrease in turbine temperature [T4b measured - G2(ng)] caused by reducing the speed to ng, so that the turbine temperature is ultimately maintained at the target value T4.

[0051] Step 6: Perform a sustained test run.

[0052] After the engine reaches takeoff status, the intake air heating device is turned on to make the intake air temperature reach T0 calculated in step five, and the fuel supply is controlled to reduce the engine speed to ng calculated in step five. At this time, the engine output power and turbine temperature reach the target value simultaneously.

[0053] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. Example 1

[0054] A certain type of aircraft turboshaft engine underwent a sustained test run using the control method of this invention. The specific steps are as follows: Step 1: Obtain the engine's performance status upon acceptance and delivery.

[0055] Under a baseline atmospheric temperature of 15°C, the engine's measured performance data during takeoff were recorded. The output power Psda was measured using a hydraulic dynamometer, and the turbine temperature T4a was measured using a temperature sensor on the engine. For the engine that passed acceptance testing, the measured Psda was higher than the target value Psd, while the measured T4a was lower than the target value T4.

[0056] Step 2: Adjust the engine performance.

[0057] This embodiment improves engine performance by adjusting the turbine throat area (AHP).

[0058] First, the proportional relationship between the turbine throat area adjustment δAHP and the output power change δPsd and turbine temperature change δT4 was determined based on the test run. Within ±5% of the takeoff condition, this relationship is linear: δPsd = k1 × δAHP, δT4 = k2 × δAHP.

[0059] Based on the measured turbine temperature T4a from step one, calculate the required turbine temperature increase δT4 = T4 index - T4a measured, and calculate the turbine throat area adjustment δAHP = δT4 / k2.

[0060] After disassembling the engine, the turbine throat area was adjusted according to δAHP. After reassembly, the engine was re-tested on the test bench. The verification results were: the measured turbine temperature T4b equaled the T4 specification, and the measured output power Psdb equaled the Psd specification plus 88kW, meaning the power exceeded the specification value by 88kW.

[0061] Step 3: Obtain the temperature characteristics of the engine under intake air heating conditions.

[0062] During takeoff, while maintaining the engine speed ng constant, the intake air heating device was turned on and operated stably for 3 minutes at each temperature point of 16℃, 20℃, 25℃, 30℃, 35℃, 40℃, 45℃, and 50℃, and the power and turbine temperature were measured.

[0063] The measurement data are shown in Table 1:

[0064] As shown in Table 1, within the temperature range of 15℃ to 50℃, power and turbine temperature exhibit a good linear relationship with the change in intake air temperature. Compared to the baseline performance at 15℃, for every 1℃ increase in intake air temperature, power decreases by 5kW, while turbine temperature increases by 1℃.

[0065] This yields the temperature characteristic function: Psd(T0) = F1(T0) = Psd + (-5) × (T0 - 15) (Equation C) T4(T0) = F2(T0) = T4 + (+1) × (T0 - 15) (Equation D) Step 4: Obtain the engine speed characteristics near takeoff.

[0066] After operating stably for 3 minutes during takeoff, the engine speed was reduced to 99.5%, 99%, 98.5%, and 98% by decreasing the fuel flow. The engine operated stably for 3 minutes at each speed point, and the power and turbine temperature were measured.

[0067] The measurement data are shown in Table 2:

[0068] As shown in Table 2, within the 98% to 100% speed range, power and turbine temperature exhibit a good linear relationship with speed changes. When ng decreases by 1%, power decreases by 66kW, and turbine temperature decreases by 22℃.

[0069] Thus, the rotational speed characteristic function is obtained: Psd(ng)=G1(ng)=Psd+(-66)×(100-ng) (Equation E) T4(ng)=G2(ng)=T4+(-22)×(100-ng) (Equation F) Step 5: Determine the control parameters for sustained test runs.

[0070] Substituting the measured Psdb minus the Psd index from step two into the power balance equation and the temperature balance equation: Power balance equation: 5×(T0-15)+66×(100-ng)=88 (Equation A') Temperature equilibrium equation: T0 - 15 = 22 × (100 - ng) (Equation B') Solving equations A' and B' simultaneously, we get: T0 = 26℃, ng = 99.5%.

[0071] Step 6: Perform a sustained test run.

[0072] During sustained test runs, in takeoff mode, the intake air heating device was activated to raise the intake air temperature to 26°C, and the fuel supply was controlled to maintain the engine speed at 99.5%. At this point, the engine output power and turbine temperature simultaneously reached the target values. Example 2

[0073] Please see Figures 7-9 To verify the technical effectiveness of this invention, two engine samples were each subjected to a 150-hour endurance test. Engine A used the intake air heating method of this invention for state control, while engine B used the traditional bleed air and generator power extraction method for state control. Each engine test lasted approximately 30 days.

[0074] After the test, the engine was disassembled and inspected. The dimensions of the first-stage rotor blades of the gas turbine, which were subjected to the heaviest temperature load, were checked, and the creep values ​​of the blades before and after the test were measured. The results showed that the creep value of the gas turbine blades of engine A (using the method of this invention) was significantly smaller than that of engine B (using the conventional method).

[0075] Further scanning electron microscopy observation of the high-temperature zone in the middle of the blade revealed that the coarsening of the tissue in the middle of engine B blade was more severe, while the coarsening of the tissue in engine A blade was significantly less severe.

[0076] The above comparison results show that, for the two engines that have passed the test and achieved the same performance requirements, the engine using the intake air heating control method of this invention has effectively controlled the temperature load of the first-stage rotor blades of the gas turbine, significantly improved high-temperature sustained damage, and effectively extended the service life of hot-end components. Example 3

[0077] This example illustrates the impact of different performance adjustment amounts on control parameters.

[0078] Using the same method as in Example 1, only the power margin after performance adjustment in step two was changed. The measured power margin Psdb-Psd index was set to 50kW, 88kW, and 120kW respectively, and the corresponding control parameters were calculated.

[0079] The results show that when the power margin is 50kW, the calculated intake air heating temperature T0 is relatively low (approximately 20℃), the speed reduction is small, and the intake air heating effect is not significant. When the power margin is 120kW, the calculated intake air heating temperature T0 is relatively high (approximately 32℃), but the excessively high intake air temperature may exceed the engine's operating temperature limit. When the power margin is 88kW, the calculated T0 = 26℃ is within a reasonable range, which can fully utilize the intake air heating effect without exceeding the engine's operating temperature limit, making it the optimal implementation method. Example 4

[0080] This example illustrates the adaptability under different ambient temperatures.

[0081] In actual tests, the reference atmospheric temperature may deviate by 15℃. When the ambient temperature is 10℃, this method uses 10℃ as the reference temperature to record engine performance in step one, measures temperature characteristics at different heating temperatures in step three, and adjusts the calculations accordingly in step five. The results show that this method can adapt to different ambient temperature conditions; as long as the temperature characteristics measured in step three cover the actual operating temperature range, control parameters can be accurately calculated. Example 5

[0082] This example illustrates the applicability of different speed reduction ranges.

[0083] In this embodiment, step four involves measurements at four engine speeds: 99.5%, 99%, 98.5%, and 98% of the engine speed ng. Experiments show that within the 98% to 100% speed range, power and turbine temperature exhibit a good linear relationship with engine speed. When the speed is below 98%, the engine's operating state deviates significantly from the takeoff state, resulting in poorer linearity and increased measurement error. Therefore, selecting a speed range of 98% to 100% ensures the accuracy of the characteristic function, thereby guaranteeing the calculation precision of the control parameters.

[0084] The above embodiments demonstrate that the method of the present invention is standardized in operation, accurate in calculation, and has good repeatability. It can effectively achieve synchronous and precise control of takeoff power and turbine temperature during sustained test runs of aero-turboshaft engines, and can effectively reduce high-temperature sustained damage to hot-end components.

[0085] Compared with the prior art, the advantages and positive effects of the present invention are as follows: First, it achieves precise synchronization of power output and turbine temperature to meet the target. Through a combined control path of "performance adjustment - intake air heating to increase temperature and reduce power - speed reduction to decrease temperature and reduce power", and through precise calculation of two balance equations, the engine output power and turbine temperature can reach the target value simultaneously during sustained test run and takeoff. This solves the contradiction in traditional methods where "power meets the target but temperature does not, and temperature meets the target but power exceeds the test."

[0086] Second, it avoids localized overheating damage to hot-end components. By using intake air heating to increase turbine temperature without altering the internal flow field distribution of the engine, it avoids the problems of uneven combustion chamber outlet temperature distribution and localized high-temperature zones caused by engine bleed air methods. This effectively reduces the risk of high-temperature creep in the turbine rotor and extends the service life of hot-end components.

[0087] Third, the test conditions are highly controllable. By pre-recording the engine's temperature and speed characteristics and establishing an accurate mathematical model, personalized control parameters can be calculated for the specific performance state of each engine. This is unaffected by individual engine performance differences or performance degradation during the test, and offers good operability and repeatability.

[0088] Fourth, it has strong versatility. This invention is not only applicable to aircraft turboshaft engines, but can also be extended to the sustained test of other types of aircraft engines, and has broad application prospects.

[0089] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any other way. Any person skilled in the art may make changes or equivalent variations to the disclosed technical content and apply them to other fields. However, any simple modifications, equivalent variations, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention. For those skilled in the art, the specific meaning of the above terms in the present invention can be understood through specific circumstances.

Claims

1. A method for controlling the sustained test conditions of an aero-engine turboshaft engine using intake air heating, characterized in that: Includes the following steps: Step 1: Obtain the engine acceptance and delivery performance status: Under the reference atmospheric temperature conditions, obtain the actual output power Psda and turbine temperature T4a of the engine in the takeoff state. The actual output power Psda is higher than the target value Psd, and the actual turbine temperature T4a is lower than the target value T4. Step 2: Adjust the engine performance: Adjust the engine structural parameters so that the turbine temperature of the engine in the takeoff state reaches the specified index value T4, the output power increases to the measured Psda, and the measured Psdb > the Psd index. Record the measured output power Psda and the measured turbine temperature T4b in the takeoff state after the performance adjustment. Step 3: Obtain the engine temperature characteristics under intake air heating conditions: During takeoff, keep the engine speed constant, turn on the intake air heating device, and measure the engine output power and turbine temperature under multiple different intake air temperature T0 conditions to obtain the relationship function between intake air temperature and output power Psd(T0)=F1(T0) and the relationship function between intake air temperature and turbine temperature T4(T0)=F2(T0). Step 4: Obtain the engine speed characteristics near takeoff: In takeoff, reduce the fuel flow to lower the engine speed ng to multiple different speed points, measure the output power and turbine temperature at each speed point, and obtain the relationship function between speed and output power Psd(ng)=G1(ng) and the relationship function between speed and turbine temperature T4(ng)=G2(ng). Step 5: Determine the control parameters for sustained test run: Based on the measured Psdb and T4b data from Step 2, and the relationship functions obtained from Steps 3 and 4, calculate the intake air heating temperature T0 and engine control speed ng by simultaneously solving the following equations: Power balance equation: Psdb measured - F1(T0) + Psdb measured - G1(ng) = Psdb measured - Psd index; Temperature balance equation: F2(T0) - T4b measured = T4b measured - G2(ng); Step Six: Perform a sustained test run: After the engine reaches takeoff status, turn on the intake air heating device to make the intake air temperature reach the specified T0, and control the fuel supply to reduce the engine speed to the specified ng, so that the engine output power and turbine temperature reach the target value synchronously.

2. The method for controlling the sustained test state of an aero-turboshaft engine using intake air heating as described in claim 1, characterized in that: In step two, the engine structural parameters include at least one of the following: compressor guide vane angle, turbine throat area, and exhaust nozzle area.

3. The method for controlling the sustained test state of an aero-turboshaft engine using intake air heating as described in claim 2, characterized in that: In step two, when adjusting the performance by adjusting the turbine throat area as an example, the following steps are included: Within ±5% of the takeoff state, obtain the linear proportional relationship between the turbine throat area adjustment δAHP and the output power change δPsd and turbine temperature change δT4: δPsd=k1×δAHP, δT4=k2×δAHP, where k1 and k2 are proportionality coefficients. Based on the measured turbine temperature T4a in step one, calculate the required turbine temperature increase δT4 = T4 index - T4a measured. Calculate the turbine throat area adjustment amount δAHP=δT4 / k2; After adjusting the turbine throat area according to the δAHP, the engine performance was re-recorded to verify that the turbine temperature reached the T4 index and the output power reached the measured Psdb.

4. The method for controlling the sustained test state of an aero-turboshaft engine using intake air heating as described in claim 1, characterized in that: In step three, the temperature characteristic function Psd(T0) = F1(T0) is a monotonically decreasing function, and the temperature characteristic function T4(T0) = F2(T0) is a monotonically increasing function.

5. The method for controlling the sustained test state of an aero-turboshaft engine using intake air heating as described in claim 1, characterized in that: In step three, the multiple different intake temperatures T0 are multiple temperature points within the range of 16°C to 50°C. After each temperature point has been operating stably for 3 minutes, the power and turbine temperature are measured.

6. The method for controlling the sustained test state of an aero-turboshaft engine using intake air heating as described in claim 1, characterized in that: In step four, the speed characteristic functions Psd(ng) = G1(ng) and T4(ng) = G2(ng) are both monotonically increasing functions.

7. The method for controlling the sustained test state of an aero-turboshaft engine using intake air heating as described in claim 1, characterized in that: In step four, the multiple different speed points are 99.5%, 99%, 98.5%, and 98% of the engine speed ng. After each speed point has been running stably for 3 minutes, the power and turbine temperature are measured.

8. The method for controlling the sustained test state of an aero-engine with intake air heating as described in claim 1, characterized in that: In step two, the performance adjustment step can be repeated until the engine turbine temperature reaches the target value T4.

9. The method for controlling the sustained test state of an aero-engine with intake air heating as described in claim 1, characterized in that: The reference atmospheric temperature is 15°C.

10. The method for controlling the sustained test state of an aero-turboshaft engine using intake air heating according to any one of claims 1-9, characterized in that, The method is applicable to the dual-parameter synchronous control of takeoff power and turbine temperature during sustained test runs of aircraft turboshaft engines.

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