Method and device for determining aerodynamic instability boundary of compression system under whole machine environment

Abstract

A method and device for determining the aerodynamic instability boundary of a compression system in an overall engine environment, the method being applied to an engine test device, the engine test device comprising an engine body and a test modification turbine with a variable flow passage cross-sectional area, the engine body comprising a compression system, the method comprising: controlling the compression system to enter a surge state by adjusting the flow passage cross-sectional area of the test modification turbine in combination with a fuel step method, or, controlling the compression system to enter a surge state by adjusting the flow passage cross-sectional area of the test modification turbine in combination with a high pressure gas charging method; determining an instability boundary point of the engine test device, and determining the aerodynamic instability boundary of the compression system at a current rotational speed according to the instability boundary point. Thus, the aerodynamic instability boundary of the compression system in an overall engine environment is determined without increasing the additional burden of the turbine and the components of the compression system.

Description

Technical Field

[0001] This article relates to, but is not limited to, the field of engine technology, and in particular to a method and apparatus for determining the aerodynamic instability boundary of a compression system under whole-machine conditions. Background Technology

[0002] Compression systems are widely used in the power and energy industries. While high-load operation can improve performance, it also presents significant stability challenges, especially when operating near the instability boundary, where surge can easily occur, affecting performance and threatening safety. Accurately assessing this boundary is crucial for reducing development costs and improving reliability and performance. Since test results in a component environment may be inaccurate in the complete machine, it is usually necessary to determine the true instability boundary through a full-machine forced surge test after prototype fabrication.

[0003] In related technologies, the fuel step method is usually used to obtain the instability boundary of the compression system under whole machine conditions.

[0004] However, while the fuel step method can effectively trigger compression system instability, the resulting high combustion chamber temperature may pose a threat to the safety of the turbine structure. Summary of the Invention

[0005] This application provides a method and apparatus for determining the aerodynamic instability boundary of a compression system under whole-machine conditions. Without increasing the additional burden on the turbine and compression system components, it achieves the determination of the aerodynamic instability boundary of the compression system under whole-machine conditions.

[0006] This application provides a method for determining the aerodynamic instability boundary of a compression system under full-engine conditions, applied to an engine testing apparatus. The engine testing apparatus includes an engine body and a modified turbine for testing with a variable flow cross-sectional area. The engine body includes a compression system. The method includes:

[0007] The compression system is controlled to enter a surge state by adjusting the flow cross-sectional area of ​​the modified turbine used in the test and combining it with a fuel step method; or, the compression system is controlled to enter a surge state by adjusting the flow cross-sectional area of ​​the modified turbine used in the test and combining it with a high-pressure gas charging method.

[0008] Determine the instability boundary point of the engine test device, and determine the aerodynamic instability boundary of the compression system at the current speed based on the instability boundary point.

[0009] This application also provides an engine testing apparatus, including: a memory and a processor;

[0010] The memory is connected to the processor and is used to store programs;

[0011] The processor is used to implement the method for determining the aerodynamic instability boundary under the overall machine environment as described above by running the program in the memory.

[0012] This application embodiment includes controlling the compression system to enter a surge state by adjusting the flow cross-sectional area of ​​the modified turbine used for testing and combining it with a fuel step method, or by adjusting the flow cross-sectional area of ​​the modified turbine used for testing and combining it with a high-pressure gas charging method; determining the instability boundary point of the engine test device, and determining the aerodynamic instability boundary of the compression system at the current speed based on the instability boundary point. Therefore, without increasing the additional burden on the turbine and compression system components, the aerodynamic instability boundary of the compression system under the whole engine environment is determined.

[0013] Other features and advantages of this application will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the application. Other advantages of this application can be realized and obtained by means of the embodiments described in the description and the accompanying drawings. Attached Figure Description

[0014] The accompanying drawings are used to provide an understanding of the technical solutions of this application and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solutions of this application and do not constitute a limitation on the technical solutions of this application.

[0015] Figure 1 This is a flowchart illustrating a method for determining the aerodynamic instability boundary of a compression system under whole-machine conditions, according to an embodiment of this application.

[0016] Figure 2 This is a schematic diagram of a process for controlling a compression system to enter a surge state according to an embodiment of this application;

[0017] Figure 3 This is a schematic diagram of a process for forcing a compression system to surge until the compression system enters a surge state, according to an embodiment of this application.

[0018] Figure 4 This is a schematic diagram illustrating the process of adjusting the oil step coefficient according to an embodiment of this application;

[0019] Figure 5 This is a schematic diagram of another process for controlling a compression system to enter a surge state according to an embodiment of this application;

[0020] Figure 6 This is a schematic diagram of another process in an embodiment of this application for forcing a compression system to surge until the compression system enters a surge state;

[0021] Figure 7 This is a schematic diagram of the structure of an engine testing device provided in an embodiment of this application;

[0022] Figure 8 This is a schematic diagram of flow rate changes during a surge process according to one embodiment of this application;

[0023] Figure 9 This is a schematic diagram illustrating the slope change process of the flow rate change curve during a surge process in one embodiment.

[0024] Figure 10 A schematic diagram of a surge dynamic process according to an embodiment of this application;

[0025] Figure 11 This is a flowchart illustrating another method for determining the aerodynamic instability boundary of a compression system under a complete machine environment, according to an embodiment of this application.

[0026] Figure 12 This is a flowchart illustrating another method for determining the aerodynamic instability boundary of a compression system under whole-machine conditions, according to an embodiment of this application.

[0027] Figure 13 This is a schematic diagram of the structure of an engine testing device according to an embodiment of this application. Detailed Implementation

[0028] This application describes several embodiments, but these descriptions are exemplary and not limiting, and it will be apparent to those skilled in the art that many more embodiments and implementations are possible within the scope of the embodiments described herein. Although many possible combinations of features are shown in the drawings and discussed in the detailed description, many other combinations of the disclosed features are also possible. Unless specifically limited, any feature or element of any embodiment may be used in combination with, or may replace, any feature or element of any other embodiment.

[0029] This application includes and contemplates combinations of features and elements known to those skilled in the art. The embodiments, features, and elements disclosed in this application can also be combined with any conventional features or elements to form unique inventive solutions. Any feature or element of any embodiment can also be combined with features or elements from other inventive solutions to form another unique inventive solution. Therefore, it should be understood that any feature shown and / or discussed in this application can be implemented individually or in any suitable combination. Therefore, the embodiments are not limited except by the limitations imposed by the appended claims and their equivalents. Furthermore, various modifications and changes can be made within the scope of the appended claims.

[0030] Furthermore, in describing representative embodiments, the specification may have presented methods and / or processes as a specific sequence of steps. However, the method or process should not be limited to the specific order of steps described herein, to the extent that it does not depend on such a specific order. As will be understood by those skilled in the art, other sequences of steps are also possible. Therefore, the specific order of steps set forth in the specification should not be construed as a limitation of the claims. Moreover, the claims concerning the method and / or process should not be limited to the steps performed in the written order, and those skilled in the art will readily understand that these orders can be varied and still remain within the spirit and scope of the embodiments of this application.

[0031] Rotary compression components, such as compressors, are widely used in the aerospace and energy industries. Due to their inherent structure and performance requirements, compressors typically operate under high loads to achieve higher efficiency. However, under high load conditions, compressors are highly susceptible to aerodynamic instability. Once instability occurs, the compressor will experience severe vibrations, a sharp decline in performance, and may cause serious structural damage. The impact can extend to the entire power system and even the engine itself, thereby endangering the safety of the driven equipment and other related systems. Therefore, accurately determining the aerodynamic instability boundary of the compressor has always been a key research focus in the industry. Reducing the technical and economic costs of this process will significantly improve the R&D efficiency and engineering application level of related industries.

[0032] The aerodynamic instability boundary of a compressor differs significantly between ideal component environments and actual operating environments. During engine development, to obtain a compressor aerodynamic instability boundary that closely approximates reality, it is often necessary to conduct a full-engine surge test under full-system conditions. Full-engine surge tests typically employ either the fuel step method or the high-pressure gas method to obtain the compressor aerodynamic instability boundary. The fuel step method significantly increases the turbine inlet temperature, severely deteriorating the turbine operating environment and drastically reducing turbine life, potentially even causing turbine damage. The high-pressure gas method requires a stable gas supply, often necessitating substantial modifications to the engine test bench; both methods are costly.

[0033] Therefore, this disclosure provides a method for determining the aerodynamic instability boundary under whole-machine conditions, applied to an engine testing apparatus. The engine testing apparatus includes: an engine body and a modified turbine for testing with a variable flow cross-sectional area. The engine body includes a compression system, such as... Figure 1 As shown, the method includes:

[0034] Step 100: By adjusting the flow cross-sectional area of ​​the modified turbine used for testing and combining it with the fuel step method, the compression system is controlled to enter the surge state; or, by adjusting the flow cross-sectional area of ​​the modified turbine used for testing and combining it with the high-pressure gas charging method, the compression system is controlled to enter the surge state.

[0035] Step 110: Determine the instability boundary point of the engine test device, and determine the aerodynamic instability boundary of the compression system at the current speed based on the instability boundary point.

[0036] The experimental modified turbine with variable flow cross-sectional area in this embodiment can be obtained in any suitable manner. One implementation method can refer to the experimental turbine structure described in patent application number 2025103302586, which discloses in detail the relevant design and adjustment mechanism, which can be referenced and applied to the experimental modified turbine in this embodiment. In that patent document, the stator blades of the experimental turbine are configured as rotatable blades to reduce the flow cross-sectional area of ​​the experimental turbine by rotating the stator blades. The experimental turbine also includes an actuation device connected to the stator blades of the experimental turbine and configured to drive the stator blades to rotate. The actuation device includes: multiple rotating shafts and a drive mechanism; there are multiple stator blades, and the multiple rotating shafts are configured to correspond one-to-one with the multiple stator blades of the experimental turbine; each rotating shaft extends radially along the experimental turbine and is connected to the corresponding stator blade, configured to drive the corresponding stator blade to rotate around the rotating shaft; the drive mechanism is connected to the multiple rotating shafts and configured to drive the multiple rotating shafts to rotate synchronously, so as to synchronously adjust the working angle of the multiple stator blades.

[0037] The method for determining the aerodynamic instability boundary under whole-machine environment provided in this application embodiment uses a modified turbine for testing to replace the original turbine and install it in the corresponding position of the engine body, while the structure of the engine body is the original structure of the engine.

[0038] The method for determining the aerodynamic instability boundary under whole-engine conditions provided in this application embodiment controls the compression system into a surge state by adjusting the flow cross-sectional area of ​​the modified turbine used in the test and combining it with a fuel step method, or by adjusting the flow cross-sectional area of ​​the modified turbine used in the test and combining it with a high-pressure gas charging method; it determines the instability boundary point of the engine test device, and determines the aerodynamic instability boundary of the compression system at the current speed based on the instability boundary point. Therefore, without increasing the additional burden on the turbine and compression system components, the method achieves the determination of the aerodynamic instability boundary of the compression system under whole-engine conditions.

[0039] In related technologies, a single fuel step surge method is typically used to induce instability in the compression system. However, this method leads to a sharp rise in combustion chamber temperature, deteriorating the turbine's operating environment and potentially causing thermal damage to the engine structure, posing a significant safety risk. In contrast, the method for determining the aerodynamic instability boundary under whole-engine conditions provided in this application does not rely solely on the fuel step surge method. Instead, it controls the compression system into a surge state by adjusting the flow cross-sectional area of ​​the modified turbine used in the test and combining it with the fuel step method. Therefore, it does not require injecting a large amount of fuel into the combustion chamber to significantly increase its temperature and pressure; only a small amount of fuel is needed to trigger compression system instability. This effectively reduces the thermal load and structural damage risk during testing, significantly improving the safety and reliability of the test.

[0040] In related technologies, high-pressure gas is often used to induce instability in the compression system. However, this method requires a large amount of high-pressure gas, which is costly to obtain. In contrast, the method for determining the aerodynamic instability boundary under whole-machine conditions provided in this application adjusts the flow cross-sectional area of ​​the modified turbine used in the test and combines it with high-pressure gas to control the compression system into a surge state. Therefore, it is not necessary to inject a large amount of high-pressure gas into the combustion chamber to significantly increase its pressure. Only a small amount of high-pressure gas is needed to trigger the instability of the compression system, thereby effectively reducing the demand for high-pressure gas and thus reducing its acquisition cost.

[0041] The compression system includes a compressor, and may also include a fan and intake duct upstream of the compressor, as well as the matching piping system, if necessary.

[0042] In one exemplary instance, when the compression system is controlled to enter a surge state by adjusting the flow cross-sectional area of ​​a modified test turbine and combining it with a fuel step method, such as... Figure 2 As shown, by adjusting the flow cross-sectional area of ​​the modified turbine used in the test and combining it with the fuel step method, the compression system is controlled to enter a surge state, including:

[0043] Step 200: Rotate the stator blades of the modified turbine for the test to the calibrated initial position; at the initial position, the stator blades of the modified turbine for the test are in the same position as the stator blades of the unmodified turbine.

[0044] Step 210: Ignite and start the engine test device, and accelerate it to the set speed for the whole engine surge test;

[0045] Step 220: Control the stator blades of the modified turbine for testing to rotate gradually to reduce the flow cross-sectional area of ​​the modified turbine for testing, and combine this with the fuel step method to force the compression system to surge until the compression system enters the surge state.

[0046] In step 200, the stator position of the modified turbine (also known as the variable geometry turbine) for testing can be calibrated to 0° according to the original geometry of the engine so that the angle of the variable geometry turbine is comparable to the original geometry. The position of the actuating ring is repeatedly changed to calibrate the correspondence between the position of the actuating mechanism and the angle of the variable geometry turbine blades, and the calibrated angle of the variable geometry turbine is set to 0°.

[0047] In step 210, the engine can be started while ensuring that the variable geometry turbine is adjusted to 0°. The engine is started and pushed to idle speed using the engine start control law before modification. The variable geometry turbine angle is kept unchanged, and the engine is gradually accelerated using the engine acceleration control law before modification until the engine reaches the speed to be measured in this test.

[0048] In step 220, the engine can be kept at the speed at which surge testing is required. The variable geometry turbine angle of the engine can be gradually reduced in increments of 1°. During the process of reducing the variable geometry angle, the engine's operating state should be kept roughly unchanged. That is, after each adjustment of the variable geometry angle, a certain amount of time should be waited until the typical performance parameters of the engine, such as speed and total pressure ratio, no longer change significantly before proceeding with the next adjustment.

[0049] In one exemplary instance, such as Figure 3 As shown, the stator blades of the modified turbine used in the test are gradually rotated to reduce the flow cross-sectional area of ​​the modified turbine, and combined with the fuel step method, the compression system is forced to surge until the compression system enters the surge state, including:

[0050] Step 300: Continuously adjust the fuel step coefficient. b To make the fuel flow rate according to b The ratio changes abruptly, based on the finally determined fuel step coefficient. b Calculate the required flow cross-sectional area for the modified turbine used in the experiment, and control the stator blades of the modified turbine to rotate gradually to reduce the flow cross-sectional area of ​​the modified turbine to the calculated flow cross-sectional area; wherein, the fuel step coefficient adjusted at any time... b Less than the fuel step coefficient a , a The fuel step coefficient that causes the compression system to enter a surge state when the fuel step method is used alone;

[0051] Step 310: Once the flow cross-sectional area of ​​the modified turbocharger used in the test reaches the calculated flow cross-sectional area, use the finally determined fuel step coefficient. b After performing forced breathing, determine whether the compression system has entered a state of surge;

[0052] Step 320: In response to the judgment that the compression system has not entered a surge state, control the stator blades of the modified turbine used in the test to rotate gradually to continue to reduce the flow cross-sectional area, and after each reduction in the flow cross-sectional area, use the finally determined fuel step coefficient. b Perform a fuel step and determine whether the compression system has entered a surge state, until the compression system enters a surge state.

[0053] For the engine before and after the variable geometry adjustment, assuming that the engine before adjustment, if using fuel step injection to induce surge, has a fuel step coefficient (i.e., the ratio of fuel injection quantity before and after the fuel step injection) that would cause the engine to enter a surge state, the following is assumed: a The step coefficient of the fuel after the geometry change is b Therefore, the fuel step coefficient and the flow cross-sectional area (also known as the turbine throat area) can be approximately approximated as:

[0054]

[0055] In the formula, The turbine throat area before the geometry change. This refers to the turbine throat area after the geometry change. The relationship between the change in the turbine throat area and the geometry angle is usually calibrated specifically through simulation or experimentation for different cases. However, a relatively simple approximation formula can also be used, for example:

[0056]

[0057] in, This represents the change in turbine throat area; The chord length of the turbine stator blade; This represents the number of turbine stator blades; This represents the relative angle through which the turbine stator blades have rotated; The radius of the turbine stator blade flow channel centerline.

[0058] In one exemplary instance, the fuel step coefficient is continuously adjusted. b To make the fuel flow rate according to b A step change occurs in the ratio, including:

[0059] Set the initial fuel step coefficient for fuel flow. b and set the initial fuel step coefficient b As the current fuel step coefficient b Perform the following fuel step coefficient adjustment operation until the fuel flow rate is in accordance with... b The ratio changes abruptly by a factor of 1:

[0060] Oil step coefficient adjustment operation as follows Figure 4 As shown, it includes:

[0061] Step 400: Based on the current fuel step coefficient b Adjust the flow cross-sectional area of ​​the modified turbine used in the test and increase the amount of fuel supplied to the combustion chamber;

[0062] Step 410: Determine whether the oil supply system can operate within the adjusted flow cross-sectional area according to... b A step change in fuel flow can be achieved by multiplying the flow rate by a factor of two.

[0063] Step 420, if unable to follow b When a step change in fuel flow is achieved by a factor of 1, continue to adjust the fuel step coefficient. b And the adjusted fuel step coefficient b As an updated current fuel step coefficient b Continue with the fuel step coefficient adjustment operation.

[0064] When fuel flow is applied in a stepwise manner, the angle of the variable geometry turbine guide vanes should remain constant. The engine control system should then, within a short period, reduce the fuel flow from the initial normal operating level. Adjusted to The time to change fuel flow rate, referring to the difference between the actual fuel injector flow rate reaching the target flow rate and the time when the fuel injector flow rate begins to rise, not the time taken to issue the control command, should not exceed 1 second. If, within 1 second, the engine is unable to achieve the required flow rate due to limitations imposed by the engine control system or fuel supply system,... b For a fuel flow rate jump of 10 times, adjust the fuel flow rate step factor. b .

[0065] In one exemplary instance, when the compression system is controlled to enter a surge state by adjusting the flow cross-sectional area of ​​the modified turbine for testing and combining it with a high-pressure gas charging method, the engine testing apparatus further includes: a gas storage chamber and a heating device; the compression system includes: a compressor; and the engine body includes: a combustion chamber.

[0066] By adjusting the flow cross-sectional area of ​​the modified turbine used in the test and combining it with high-pressure air charging, the compression system was controlled to enter a surge state, such as... Figure 5 As shown, it includes:

[0067] Step 500: Rotate the stator blades of the modified turbine for the test to the calibrated initial position; at the initial position, the stator blades of the modified turbine for the test are in the same position as the stator blades of the unmodified turbine.

[0068] Step 510: Ignite and start the engine test device and accelerate it to the set speed for the whole engine surge test;

[0069] Step 520: Control the stator blades of the modified turbine for the test to rotate gradually to reduce the flow cross-sectional area of ​​the modified turbine for the test, and combine this with the high-pressure gas charging method to force the compression system to surge until the compression system enters the surge state; wherein, the high-pressure gas charging method is to use heating equipment to heat the high-pressure gas from the compressor in the gas storage chamber and output the high-heat, high-pressure gas to the combustion chamber.

[0070] In one exemplary instance, the outer wall of the flow channel at the compressor outlet is provided with multiple vent holes, and the air storage chamber is connected to the vent holes by a vent pipe, and a valve is provided on the vent pipe.

[0071] The stator blades of the modified turbine used in the test are gradually rotated to reduce the flow cross-sectional area of ​​the modified turbine. Combined with a high-pressure gas charging method, the compression system is forced into a surge state until it enters the surge condition. This includes:

[0072] Set the initial flow cross-sectional area required for the modified turbine used in the test, set the initial heating temperature for the heating equipment to heat the gas storage chamber, and use the set initial flow cross-sectional area as the current flow cross-sectional area and the set initial heating temperature as the current heating temperature. Then perform the following forced surge operation until the compression system enters the surge state.

[0073] Forcing breathing techniques such as Figure 6 The following are included:

[0074] Step 600: Close the valve and use the heating equipment to heat the high-pressure gas in the gas storage chamber at the current heating temperature to generate high-temperature and high-pressure gas;

[0075] Step 610: Open the valve to allow the high-temperature, high-pressure gas in the gas storage chamber to enter the combustion chamber and thus force the compression system to surge. During the surge process, determine whether the compression system has entered a surge state.

[0076] Step 620: In response to the judgment that the compression system has not entered the surge state, reduce the current flow cross-sectional area to obtain an updated current flow cross-sectional area and / or increase the current heating temperature to obtain an updated current heating temperature, and continue to perform the surge-forcing operation using the updated current flow cross-sectional area and / or the updated current heating temperature.

[0077] In the implementation of step 620, in response to the judgment result that the compression system has not entered the surge state, the current flow cross-sectional area can be reduced to obtain an updated current flow cross-sectional area, and the surge-forcing operation can be performed using the updated current flow cross-sectional area; or the current heating temperature can be increased to obtain an updated current heating temperature, and the surge-forcing operation can continue to be performed using the updated current heating temperature; or the current flow cross-sectional area can be reduced to obtain an updated current flow cross-sectional area, and the current heating temperature can be increased to obtain an updated current heating temperature, and the surge-forcing operation can continue to be performed using the current flow cross-sectional area and the updated current heating temperature.

[0078] In related technologies, using a high-pressure gas source method usually requires large-scale modifications to the test apparatus and its peripheral equipment, such as adding compressors to provide a suitable gas source. Such modifications are not only costly but also require a long implementation period, resulting in low overall feasibility. In contrast, the aerodynamic instability boundary determination method provided in this application embodiment uses multiple vent holes on the outer wall of the flow channel at the compressor outlet. The gas storage chamber is connected to these vent holes (also known as intake / exhaust interfaces) via a vent pipe. A valve is installed on the vent pipe, connecting the gas storage chamber to the vent holes. The engine test apparatus provided in this application embodiment can... Figure 7 As shown, the system includes: a gas storage chamber 11, a heating device 12, a vent 13 (only one is shown as an example), a modified test turbine 14 with a variable flow cross-sectional area, and an electrically controlled valve 15. After the high-pressure gas generated by the compressor enters the gas storage chamber, the heating device heats the gas in the storage chamber to generate high-temperature, high-pressure gas. When the valve is opened, the high-temperature, high-pressure gas enters the combustion chamber through the vent, thereby increasing the outlet back pressure of the compression system and achieving pressure control of the compression system. The method of this embodiment does not require large-scale modification of existing equipment; it only requires local structural optimization, offering advantages such as convenient modification, low cost, and short implementation cycle.

[0079] In this embodiment of the application, the valve installed on the ventilation pipeline is required to be able to open in a controlled manner during engine operation, and the valve's operating frequency should be no less than 10Hz.

[0080] The materials and structure of the gas storage chamber must be able to withstand high temperatures and pressures. The ventilation piping needs to accommodate both forward and reverse flow simultaneously. During gas storage, the stored gas should be able to be heated using heating equipment with the valves closed. However, since the airflow from the engine compressor outlet often already has a high initial temperature, the heating efficiency of the chosen heating method should be carefully considered. For engines with lower total pressure ratios, conventional resistance heating can be used; for high-pressure-ratio, high-performance compressors, high-performance heating methods such as arc heating are typically required.

[0081] In one exemplary instance, the minimum area of ​​a single vent is as follows:

[0082]

[0083] in, The minimum area of ​​a single vent. This refers to the outlet mass flow rate of the compressor when it is operating stably under test conditions. The outlet static temperature is the temperature at which the compressor is operating stably under test conditions. The outlet static pressure is the compressor's stable operating pressure at the test operating point. The correction factor is determined based on the selection of the valve and vent. The number of vents. For specific heat ratio, The gas constant is... This refers to the temperature of the gas inside the gas storage chamber.

[0084] For the vent, its size and number should be such that the mass flow rate of gas through the vent at the moment the valve is opened meets the mass flow rate required for the test engine to enter the gas flow. Generally speaking, this mass flow rate is 1 / 3 of the compressor outlet mass flow rate when the engine is operating stably at the test speed.

[0085] Simultaneously considering that the vent needs to maintain the flow rate for a certain period of time to allow the engine to surge, after determining the vent area, it is still necessary to ensure that there is sufficient air in the air storage chamber to guarantee that the device can maintain the compressor at the surge boundary for a certain period of time, thereby allowing the compressor to smoothly enter surge mode. Since the typical surge characteristic time is above 10Hz, an example is provided here, which requires the air charging device to maintain a certain flow rate within 1 second to meet the following conditions:

[0086]

[0087] in, The gas constant is... This refers to the volume of the gas storage chamber.

[0088] This formula requires a numerical method to solve for the gas storage chamber volume. In order to minimize the burden of heating the gas in the gas storage chamber, the gas storage chamber volume should be as large as possible, and it is recommended to be at least 10 times the equivalent volume of the engine combustion chamber.

[0089] In one exemplary instance, the heating temperature of the heating device as follows:

[0090] and ;

[0091] ;

[0092] in, The temperature of the gas storage chamber after heating. The inlet gas temperature of the combustion chamber. The combustion chamber inlet pressure, The inlet pressure of the combustion chamber when the aerodynamic instability boundary is reached during the gas expulsion process. It is the equivalent aerodynamic volume of the combustion chamber. It is the aerodynamic volume of the air storage chamber. The calorific value of the fuel. For the specific heat capacity of the gas, The fuel step coefficient is preset, and Less than a The fuel step coefficient, a The fuel step coefficient that enables the compression system to enter a surge state when the fuel step method is used alone; This represents the airflow rate at the compressor outlet. It is the fuel flow rate when the engine is operating stably.

[0093] In one exemplary instance, whether a surge state has been entered is determined based on whether the operating information of the engine test device meets the criteria for entering a surge state.

[0094] The operating information of the engine testing device includes: physical quantities used to characterize the performance of the compression system and signals used to characterize the operating status of the engine testing device.

[0095] The criteria for determining whether a surge state has been entered include at least one of the following: the physical quantity used to characterize the performance of the compression system meets the set surge condition, and the signal used to characterize the operating state of the engine test device shows a set surge signal.

[0096] The set instability conditions include at least one of the following: the curvature change of the physical quantity satisfies the first set instability boundary condition, and the frequency of the periodic signal extracted from the physical quantity satisfies the second set instability boundary condition;

[0097] The set gas surge signal includes at least one of an optical signal and an acoustic signal. The acoustic signal may include, but is not limited to: a low-frequency humming sound and / or a continuous popping sound that is different from the normal operating state. The optical signal may include, but is not limited to: a flash of light emerging from the outlet of the engine test device.

[0098] In some exemplary embodiments, data corresponding to a physical quantity (such as the compressor outlet pressure) is selected from data corresponding to physical quantities used to characterize the performance of the compression system to determine that physical quantity. P A curve that changes over time. For example... Figure 8As shown, taking flow rate as an example, the variation of this physical quantity during the surge process is illustrated. Its characteristic is a periodic fluctuation accompanied by alternating positive and negative values. The curvature calculation formula is used to calculate the curve at each moment. t The curvature at such a point, such as Figure 9 As shown.

[0099] For example: the average static pressure at the compressor outlet section is selected as... P The average static pressure is P The average static pressure can be obtained by: averaging the dynamic pressure signals collected by multiple outlet pressure probes circumferentially (i.e., summing and then averaging), and then filtering the signals using a filtering function (removing high-frequency and low-frequency signals). Based on this, the average static pressure can be obtained as follows: P The curve changes over time, and the curvature calculation formula can be used to calculate the curve at each moment. t The curvature at that point.

[0100] The formula for calculating curvature is:

[0101] ;

[0102] In the above formula, Representing physical quantities P The slope of the curve represents the physical quantity. P The speed of change; W The length of the window used to calculate the slope is a positive integer; Representing physical quantities P exist W The amount of change over a period of time; f Indicates the sampling frequency.

[0103] The first set of instability boundary conditions includes:

[0104] ;

[0105] In the above formula, Indicates time as N Time physical quantity P The slope is A , A This represents the threshold values ​​for compressor 11 with different configurations. This represents the compressor's flow rate. The physical meaning of this formula is: when the physical quantity... P The speed of the change process reaches A If the compressor flow rate is positive at this point, it is considered to have reached the instability boundary, and this operating condition is taken as the instability boundary point of the compressor. AThe value depends on the compressor configuration of the engine being calculated (such as axial compressor, centrifugal compressor, axial-centrifugal combined compressor, etc.), as well as the engine's size and power rating. In practical applications, it is usually selected based on existing cases of engines with similar configurations, sizes, and power ratings.

[0106] In some exemplary embodiments, the frequency of the periodic signal extracted from the physical quantity is denoted as... . The extraction method is as follows: Use real-time fast Fourier transform to extract the main periodic signal frequencies in the selected physical quantities.

[0107] For example: the average static pressure at the compressor outlet section is selected as... P The average static pressure is P This can be obtained by: averaging the dynamic pressure signals collected from multiple outlet pressure probes circumferentially (i.e., summing and then averaging), and then filtering the signals using a filtering function (removing high-frequency and low-frequency signals). Finally, using a real-time fast Fourier transform, the main periodic signal frequencies in the dynamic pressure signal are extracted, which is the... .

[0108] The second set of instability boundary conditions includes:

[0109] ;

[0110] In the above formula, constant ， The compressor is usually selected based on its specific configuration, size, and power rating. This is to predict the Helmholtz frequency of the engine test setup under the current conditions. The meaning of this formula is that when the main periodic frequency of the dynamic change in compressor outlet pressure approaches the Helmholtz frequency... When the frequency of the periodic signal extracted from the physical quantity satisfies the second set instability boundary condition, it is considered true.

[0111] The calculation formula is:

[0112]

[0113] In the above formula, The velocity of sound at the compressor outlet. This is the equivalent cross-sectional area of ​​the compressor outlet. This is the equivalent volume of the combustion chamber cavity. This is the equivalent length of the combustion chamber.

[0114] Figure 10The figure shows the overall machine instability boundary obtained by the method of the embodiments of this application. The black trajectory in the figure is the whole process of the compressor surge condition under the overall machine environment obtained by the method of the embodiments of this application, and the gray circle is the instability boundary point determined by this method.

[0115] This application also provides a method for determining the aerodynamic instability boundary under whole-engine conditions. This method employs a combined approach of variable geometry turbine and fuel step effect: by using a variable geometry turbine, the fuel step effect is enhanced, thereby reducing the requirement for combustion room temperature rise during the fuel step process, and thus reducing the damage of the fuel step to the engine. Figure 11 As shown, the specific process includes:

[0116] Step 700: Install the engine onto the test bench and set it to the initial position.

[0117] The modified engine was mounted on the test bench, and the external air storage chamber was fixed in place. The initial position of the variable geometry turbine was calibrated. Based on the original engine geometry, the 0° position of the stator of the modified variable geometry turbine was calibrated to ensure that the angle of the variable geometry turbine was equivalent to that of the original geometry. The position of the actuator ring was repeatedly changed to calibrate the correspondence between the position of the actuator mechanism and the angle of the variable geometry turbine blades. The calibrated angle of the variable geometry turbine was then set to 0°.

[0118] Step 710: Set the engine to the test speed.

[0119] Ensure the variable geometry turbocharger is adjusted to 0° and start the engine. Use the original engine start control program to ignite the engine and accelerate it to idle speed. Keeping the variable geometry turbocharger angle constant, use the original engine acceleration control program to gradually accelerate the engine until it reaches the speed required for this test.

[0120] Step 720: Adjust the variable geometry turbine angle to reduce the engine throat area.

[0121] Maintain the engine at the required surge test speed, and gradually decrease the engine's variable geometry turbine angle in 1° increments. During the decrease, keep the engine's operating state roughly constant; that is, after each complete adjustment, wait a certain amount of time until the engine's typical performance parameters, such as engine speed and total pressure ratio, no longer change significantly before proceeding with further adjustments. For the engine before and after the variable geometry adjustment, assuming that the engine before adjustment, if using fuel step injection to induce surge, would have a fuel step coefficient (i.e., the ratio of fuel injection quantity before and after the fuel step) that would induce surge is... a The step coefficient of the fuel after the geometry change is b Therefore, the fuel step coefficient and the turbine throat area can be approximately approximated as:

[0122]

[0123] In the formula, The turbine throat area before the geometry change. This refers to the turbine throat area after the geometry change. The relationship between the change in turbine throat area and the geometry angle usually requires extensive practical calculations and calibration, but a relatively simple approximation formula can also be used, for example:

[0124]

[0125] In the formula, This represents the change in turbine throat area; The chord length of the turbine stator blade; This represents the number of turbine stator blades; This represents the relative angle through which the turbine stator blades have rotated; The radius of the turbine stator blade flow channel centerline.

[0126] Step 730: Dynamically collect compressor outlet pressure parameters as a criterion for surge judgment.

[0127] like Figure 7 As shown, a dynamic pressure sensor 16 (also called a pressure probe) can be installed at the compressor outlet of the engine to determine whether the compressor has entered a surge state. The compressor outlet pressure parameters can be obtained through the dynamic pressure sensor. Considering that the engine is in normal operating condition during the test, a situation of high-temperature combustion gas backflow from the combustion chamber may occur at the engine end during the surge process. Therefore, special consideration must be given to the selection of the dynamic pressure sensor. The surge frequency is approximately 100Hz, and the frequencies of the pressure probe and the acquisition device are 20kHz and 200kHz, respectively, which meets the requirements for measuring the surge phenomenon. The dynamic pressure probe measurement and acquisition system is started synchronously when the engine is started. The results of the dynamic pressure acquisition system are monitored continuously.

[0128] Step 740, Fuel Step-by-Step Gasping

[0129] After completing the variable geometry angle adjustment, the engine is subjected to a step-force fuel injection. During step-force fuel injection, the angle of the variable geometry turbine guide vanes should remain constant. The engine control system should then rapidly increase the fuel flow rate from the initial normal operating level. Adjusted to The time to change fuel flow rate, referring to the difference between the actual fuel injector flow rate reaching the target flow rate and the time when the fuel injector flow rate begins to rise, not the time taken to issue the control command, should not exceed 1 second. If, within 1 second, the engine is unable to achieve the required flow rate due to limitations imposed by the engine control system or fuel supply system,... bIf the fuel flow rate increases by a factor of two, then return to step 720 and adjust the target fuel flow rate step factor. b And adjust the variable geometry turbine throat area according to the formula.

[0130] Step 750: Determine whether the engine is experiencing shortness of breath based on the following conditions.

[0131] If at least one of P1, P2, and P3 is satisfied, the engine is determined to have entered a surge state, and step 760 is executed. If none of P1, P2, and P3 is satisfied, the process returns to step 720 to continue reducing the variable geometry turbine angle and then continuing the fuel step surge. This cycle continues until the engine enters a surge state.

[0132] P1 condition:

[0133] The dynamic pressure signal measured at the compressor outlet is circumferentially averaged, and a filtering function is used to filter out high-frequency and low-frequency signals. The resulting processed dynamic pressure signal is denoted as... P Calculate based on this. P Curvature of the change process The process of change, in which:

[0134]

[0135] In the formula, Representing physical quantities P The slope of the curve represents the physical quantity. P The speed of change; W The length of the window used to calculate the slope is a positive integer; Representing physical quantities P exist W The amount of change over a period of time; f Indicates the sampling frequency.

[0136] To determine whether the stability boundary conditions are met, the following conditions must be met:

[0137]

[0138] In the formula, Indicates time as N Time physical quantity P The slope is A ,in A Indicates the threshold; This represents the compressor flow rate. The physical meaning of the above formula is that when the physical quantity... P The speed of the change process reaches A If the compressor flow rate is positive at a certain time, it is considered to have reached the surge boundary, and this operating condition is taken as the surge boundary point of the compressor. AThe value depends on the compressor configuration of the aero-engine being calculated (such as axial compressor, centrifugal compressor, axial-centrifugal combined compressor, etc.), as well as the engine's size and power rating. In practical applications, it is usually selected based on existing cases of engines with similar configurations, sizes, and power ratings.

[0139] P2 condition:

[0140] The dynamic pressure signal measured at the compressor outlet is circumferentially averaged, and a filtering function is used to remove higher and lower frequency signals. A real-time fast Fourier transform is then used to extract the main periodic signal frequencies from the dynamic pressure signal. .

[0141] Based on the engine's current operating status, and by combining parameters such as engine flow rate and pressure obtained through measurement or model calculation with the engine's own geometric characteristic parameters, the Helmholtz frequency at which the engine enters surge state is calculated and predicted. . The calculation method is as follows:

[0142]

[0143] in This represents the speed of sound at the compressor outlet. This is the equivalent cross-sectional area of ​​the compressor outlet. The equivalent volume of the combustion chamber cavity. This is the equivalent length of the combustion chamber.

[0144] Determine if the following relationship is satisfied:

[0145]

[0146] in, This is a constant, typically selected based on the specific configuration, size, and power rating of the engine compressor. The meaning of this formula is that the P2 condition holds when the main periodic frequency of the dynamic change in the compressor outlet pressure approaches the Helmholtz frequency.

[0147] P3 condition:

[0148] If the engine emits a low-frequency humming sound that is distinctly different from its normal operating state, or a continuous popping sound, or if a flash of light is observed leaping out of the engine outlet, then condition P3 is considered to be met.

[0149] During the test monitoring process, if any one of the collected parameters P1, P2, and P3 is satisfied, it is determined that the engine has reached the surge boundary, and step 750 is continued. If no two of P1, P2, and P3 are satisfied, the process returns to step 720 to continue reducing the variable geometry turbine angle until the engine compressor successfully enters the surge state.

[0150] Step 760: Collect surge boundary data and conduct surge boundary measurement tests at other speeds.

[0151] After determining that the engine has successfully entered surge mode, the fuel flow should be quickly reduced to its initial state while simultaneously increasing the variable geometry turbine angle until the original design angle, i.e., 0°, is reached. If the engine operating state still meets any of the above conditions P1, P2, and P3 at this point, continue increasing the variable geometry turbine angle while reducing the engine fuel injection quantity to the idle fuel flow, until the engine operating state no longer meets conditions P1, P2, and P3. Note that you should not directly shut off the fuel pump, as this will damage the engine.

[0152] In this method, a variable geometry turbine replaces part of the step fuel injection function. Together, they shift the compressor operating point to the aerodynamic instability boundary. The step fuel flow replaced by the variable geometry turbine reduces the combustion chamber outlet gas temperature, thereby reducing the turbine thermal load caused by the step fuel injection while maintaining the basic aerodynamic characteristics of the impact of the step fuel injection on the compressor. The portion of the step fuel injection replaced by the variable geometry turbine can also be converted using the formula in step 720 for standardized comparative analysis.

[0153] This application also provides a method for determining the aerodynamic instability boundary under whole-machine environment. This method employs a combined approach of variable geometry turbine and high-pressure gas charging. High-pressure gas charging simulates the dynamic pressure changes caused by fuel step changes, thus completely replacing fuel step changes. The surge-forcing method combining high-pressure gas charging and variable geometry turbine can further reduce the turbine thermal load during the surge-forcing process. Furthermore, compared to the fuel step surge-forcing method, the high-pressure gas charging method is more flexible and precise. Figure 12 As shown, the specific process includes:

[0154] Step 800: Place the engine on the platform and set it to the initial position.

[0155] The modified engine was mounted on the test bench, and the external air storage chamber was fixed in place. The initial position of the variable geometry turbine was calibrated. Based on the original engine geometry, the 0° position of the stator of the modified variable geometry turbine was calibrated to ensure that the angle of the variable geometry turbine was equivalent to that of the original geometry. The position of the actuator ring was repeatedly changed to calibrate the correspondence between the position of the actuator mechanism and the angle of the variable geometry turbine blades. The calibrated angle of the variable geometry turbine was set to 0°. The air storage chamber valve was opened to allow air to be compressed by the compressor and enter the air storage chamber.

[0156] Step 810: Set the engine to the test speed.

[0157] Ensure the variable geometry turbocharger is adjusted to 0° and start the engine. Use the original engine start control program to ignite the engine and accelerate it to idle speed. Keeping the variable geometry turbocharger angle constant, use the original engine acceleration control program to gradually accelerate the engine until it reaches the speed required for this test.

[0158] Step 820: Adjust the variable geometry turbine angle to reduce the engine throat area.

[0159] Maintain the engine at the required surge test speed, and gradually reduce the engine's variable geometry turbine angle in 1° increments. During the reduction of the variable geometry angle, the engine's operating state should remain largely unchanged; that is, after each complete adjustment of the variable geometry angle, wait for a period of time until the engine's typical performance parameters, such as engine speed and total pressure ratio, no longer change significantly before proceeding with the next adjustment. It is important to note that you should not force the engine to surge directly through variable geometry angle adjustments. A surge margin should still be maintained so that subsequent surge-inducing methods can simulate the dynamic process of a sudden pressure increase.

[0160] Step 830: Dynamically collect compressor outlet pressure parameters as a criterion for surge judgment.

[0161] A dynamic pressure sensor should be installed at the compressor outlet to determine if the compressor has entered a surge state. Considering that the engine is operating normally during the test, a backflow of high-temperature combustion gases from the combustion chamber may occur at the engine end during surge; therefore, the selection of the dynamic pressure sensor requires special consideration. The surge frequency is approximately 100Hz, and the probe and acquisition equipment frequencies are 20kHz and 200kHz respectively, meeting the requirements for measuring surge phenomena. The dynamic pressure probe measurement and acquisition system should be started synchronously when the engine is started. The results of the dynamic pressure acquisition system should be monitored continuously.

[0162] Step 840: Close the gas storage chamber valve and heat the gas storage chamber.

[0163] After the engine reaches its design speed, the pressure inside the gas reservoir should be equal to the pressure in the combustion chamber because the valve is open. At this point, the gas reservoir valve is closed, isolating the gas reservoir. Subsequently, the gas reservoir is heated using the heating equipment within it. To ensure that during charging, the gas in the gas reservoir can quickly raise the pressure in the combustion chamber to achieve a surging effect, the heating temperature of the gas reservoir should at least meet the following requirements:

[0164]

[0165] In the formula, The temperature of the gas storage chamber after heating. The inlet gas temperature of the combustion chamber. The combustion chamber inlet pressure, During the gas-induced breathing process, the inlet pressure of the combustion chamber at the point where aerodynamic instability is reached is... It is the equivalent aerodynamic volume of the combustion chamber. It is the aerodynamic volume of the air storage chamber.

[0166] To completely replace fuel-powered step coefficients with high-pressure gas exhalation, c If the fuel supply is rapidly increasing, the heating temperature of the gas storage chamber should meet the following requirements:

[0167]

[0168]

[0169] In the formula, The temperature of the gas storage chamber after heating. The inlet gas temperature of the combustion chamber. The combustion chamber inlet pressure, During the gas-induced breathing process, the inlet pressure of the combustion chamber at the point where aerodynamic instability is reached is... It is the equivalent aerodynamic volume of the combustion chamber. It is the aerodynamic volume of the air storage chamber. The calorific value of the fuel. For the specific heat capacity of the gas, The pre-set fuel step coefficient, Less than a , a The fuel step coefficient that enables the compression system to enter a surge state when the fuel step method is used alone; This represents the airflow rate at the compressor outlet. It is the fuel flow rate when the engine is operating stably.

[0170] In practice, a dynamic pressure monitoring probe is often added between the inflation / valve and the high-pressure chamber. During the heating of the high-pressure chamber and the inflation / breathing process, the pressure measured by this probe should be maintained at a constant level. Above.

[0171] The heating time of the gas storage chamber depends on the volume of the gas storage chamber and the performance of the heating equipment. If the heating time is too long, the engine can be stopped first, and after the gas storage chamber has been heated, the engine can be restarted and accelerated back to the test speed before continuing the test.

[0172] At low test speeds, the engine can be accelerated to the design speed first to establish a high gas pressure in the gas storage chamber, and then the speed can be reduced to a lower test speed to release the gas. This can reduce heating time or eliminate the heating process altogether.

[0173] Step 850: Release gas from the gas storage chamber to simulate a fuel step.

[0174] After heating the gas storage chamber, maintain the variable geometry turbine angle of the engine and adjust the valves to bleed the gas. The specific bleed procedure and selection of the bleed port should be determined based on the specific test plan. Bleeding the gas storage chamber will cause the compressor to enter a surge state.

[0175] Step 860: Determine engine surge based on the following conditions.

[0176] If at least one of P1, P2, and P3 is satisfied, the engine is determined to have entered a surge state, and step 870 is executed. If none of P1, P2, and P3 is satisfied, the process returns to step 820 to continue reducing the variable geometry turbine angle, or returns to step 840 to further heat the gas storage chamber before continuing the forced surge. This cycle continues until the engine enters a surge state.

[0177] After the engine enters a surge state, the variable geometry turbine angle should be opened quickly, the engine fuel supply should be reduced, and the charging valve should be closed after the data collection is completed, so that the engine can stop surging.

[0178] Step 870: Collect surge boundary data and conduct surge boundary measurement tests at other speeds.

[0179] In this method, a variable geometry turbine and a high-pressure gas injection method are used to partially replace the function of step fuel injection. Together, they shift the compressor operating point to the aerodynamic instability boundary. This further reduces the thermal load on the turbine components during the surge process while maintaining the basic aerodynamic processes during surge.

[0180] The following section uses a small turbojet engine equipped with a single-stage centrifugal compressor as an example to briefly describe the basic process of using the above-mentioned combined method of variable geometry turbine and high-pressure gas.

[0181] S1. First, assemble the engine and install the variable geometry turbine. Modify the engine casing to connect to the air reservoir. Adjust the variable geometry turbine to 0 degrees. Open the air reservoir valve.

[0182] S2. Ignite the engine and accelerate according to the normal test procedure until the required engine speed for the breather test is reached. Maintain the engine speed constant.

[0183] S3. Gradually reduce the angle of the variable geometry turbine in given steps. During the reduction process, the engine control system needs to automatically adjust the engine fuel injection quantity to ensure that the engine speed does not change.

[0184] S4. Close the air chamber valve and heat the air chamber to the set value. Then open the air chamber valve and force the engine to breathe.

[0185] S5. Collect dynamic pressure sensor parameters at the inlet and outlet positions of the engine compressor. Filter the collected pressure sensor parameters.

[0186] S6. Determine the engine's operating state based on criteria P1, P2, and P3. If the engine is experiencing turbocharging, use the compressor parameters obtained before the variable geometry turbine was shut down as the instability boundary of the compression component. If the engine is not experiencing turbocharging, repeat the shutdown operation from step S3.

[0187] S7. After completing the surge boundary measurement for one speed line, continue adjusting the engine operating state, exit the surge state, and accelerate to the second speed line to be measured. Repeat steps S3-S6 until the surge boundary of all planned speed lines has been measured.

[0188] This concludes the experimental measurement of the engine's overall aerodynamic instability boundary under this operating condition. The instability boundary under other operating conditions will be calculated using the same method.

[0189] The method for determining the aerodynamic instability boundary under a complete engine environment provided in this application embodiment can consider the transient effect of sudden pressure increase in both combined surge-inducing methods, thus better approximating the actual surge caused by rapid acceleration in a real engine operating environment. Compared to the fuel step surge-inducing method, which also considers the transient effect of sudden pressure increase, the fuel step-variable geometry turbine composite surge-inducing method provided in this application embodiment can use a variable geometry turbine to replace part of the fuel step function, thereby reducing the injected fuel flow rate, reducing the turbine thermal load during the surge-inducing process, and ultimately reducing test risks and costs. Compared to the traditional high-pressure gas surge-inducing method, which also does not cause additional thermal load, the high-pressure gas-variable geometry turbine composite surge-inducing method provided in this application embodiment can achieve self-sufficiency of high-pressure gas source without providing a high-temperature gas source or making large-scale modifications to the test bench, simply by modifying and expanding the test engine, and also reduces test costs and shortens test preparation time.

[0190] Corresponding to the method for determining the aerodynamic instability boundary under the above-mentioned whole-machine environment, this application embodiment also provides an engine testing device, such as... Figure 13 The device shown includes: an engine body 900, a test modified turbine 910 with a variable flow cross-sectional area, and a test control device 920, the test control device 920 including: a memory and a processor, the memory being configured to store executable programs;

[0191] The processor is configured to read and execute the executable program to perform the method for determining the aerodynamic instability boundary under the overall environment as described in any of the above embodiments.

[0192] In addition to the methods and devices described above, embodiments of this application may also be computer program products, which include computer program instructions that, when executed by a processor, cause the processor to perform the steps in the method for determining the aerodynamic instability boundary in a whole-machine environment according to various embodiments of this application as described in any of the above embodiments of this specification.

[0193] Computer program products can be written in any combination of one or more programming languages ​​to perform the operations of the embodiments of this application. The programming languages ​​include object-oriented programming languages ​​such as Java and C++, as well as conventional procedural programming languages ​​such as C or similar languages. The program code can be executed entirely on the user's computing device, partially on the user's computing device, as a standalone software package, partially on the user's computing device and partially on a remote computing device, or entirely on a remote computing device or server.

[0194] Furthermore, this application also provides a storage medium storing a computer program. When the computer program is run by a processor, it implements the method for determining the aerodynamic instability boundary under the overall machine environment described in any of the above embodiments.

[0195] It will be understood by those skilled in the art that all or some of the steps, systems, or apparatuses disclosed above, and their functional modules / units, can be implemented as software, firmware, hardware, or suitable combinations thereof. In hardware implementations, the division between functional modules / units mentioned above does not necessarily correspond to the division of physical components; for example, a physical component may have multiple functions, or a function or step may be performed collaboratively by several physical components. Some or all components may be implemented as software executed by a processor, such as a digital signal processor or microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit (ASIC). Such software may be distributed on a computer-readable medium, which may include computer storage media (or non-transitory media) and communication media (or transient media). As is known to those skilled in the art, the term "computer storage medium" includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data). Computer storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disc (DVD) or other optical disc storage, magnetic cartridges, magnetic tape, disk storage or other magnetic storage devices, or any other medium that can be used to store desired information and can be accessed by a computer. Furthermore, it is well known to those skilled in the art that communication media typically contain computer-readable instructions, data structures, program modules, or other data in modulated data signals such as carrier waves or other transmission mechanisms, and may include any information delivery medium.

Claims

1. A method for determining the aerodynamic instability boundary under whole-machine conditions, characterized in that, An engine testing apparatus, comprising an engine body and a modified turbine for testing with a variable flow cross-sectional area, the engine body including a compression system, the method comprising: The compression system is controlled to enter a surge state by adjusting the flow cross-sectional area of ​​the modified turbine used in the test and combining it with a fuel step method; or, the compression system is controlled to enter a surge state by adjusting the flow cross-sectional area of ​​the modified turbine used in the test and combining it with a high-pressure gas charging method. Determine the instability boundary point of the engine test device, and determine the aerodynamic instability boundary of the compression system at the current speed based on the instability boundary point; When the compression system is controlled to enter a surge state by adjusting the flow cross-sectional area of ​​the modified turbine for testing and combining it with a high-pressure gas charging method, the engine test device further includes: a gas storage chamber and a heating device; the compression system includes: a compressor; and the engine body includes: a combustion chamber. The method of controlling the compression system to enter a surge state by adjusting the flow cross-sectional area of ​​the modified turbine used in the test and combining it with a high-pressure gas charging method includes: The stator blades of the modified turbine for the test are rotated to the calibrated initial position; at the initial position, the stator blades of the modified turbine for the test are in the same position as the stator blades of the unmodified turbine. The engine test device is ignited and started, and accelerated to the set speed for the whole engine power surge test; The stator blades of the modified turbine for testing are gradually rotated to reduce the flow cross-sectional area of ​​the modified turbine for testing, and combined with the high-pressure gas charging method, the compression system is forced to surge until the compression system enters a surge state; wherein, the high-pressure gas charging method is a method of using the heating equipment to heat the high-pressure gas from the compressor in the gas storage chamber and outputting high-heat, high-pressure gas to the combustion chamber; The outer wall of the flow channel at the compressor outlet is provided with multiple vent holes, and the air storage chamber is connected to the vent holes by a vent pipe, and a valve is provided on the vent pipe; The minimum area of ​​a single vent is as follows: ； in, The minimum area of ​​a single vent hole. This refers to the outlet mass flow rate of the compressor when it is operating stably under test conditions. The outlet static temperature is the temperature at which the compressor is operating stably under test conditions. The outlet static pressure is the compressor's stable operating pressure at the test operating point. The correction factor is determined based on the selection of the valve and vent. The number of vents. For specific heat ratio, The gas constant is This refers to the temperature of the gas inside the gas storage chamber.

2. The method according to claim 1, characterized in that, When the compression system is controlled to enter a surge state by adjusting the flow cross-sectional area of ​​the modified test turbine and combining it with a fuel step method, the process of controlling the compression system to enter a surge state by adjusting the flow cross-sectional area of ​​the modified test turbine and combining it with a fuel step method includes: The stator blades of the modified turbine for the test are rotated to the calibrated initial position; at the initial position, the stator blades of the modified turbine for the test are in the same position as the stator blades of the unmodified turbine. The engine test device is ignited and started, and accelerated to the set speed for the whole engine power surge test; The stator blades of the modified turbine for testing are gradually rotated to reduce the flow cross-sectional area of ​​the modified turbine for testing, and combined with the fuel step method, the compression system is forced to surge until the compression system enters a surge state.

3. The method according to claim 2, characterized in that, The process of gradually rotating the stator blades of the modified turbine to reduce its flow cross-sectional area, combined with a fuel step method, to induce surge in the compression system until it enters a surge state includes: Continuously adjust the fuel step coefficient b So that the fuel supply system can meet the fuel flow rate according to b The ratio changes abruptly, based on the finally determined fuel step coefficient. b Calculate the required flow cross-sectional area for the modified turbine used in the experiment, and control the stator blades of the modified turbine to rotate gradually to reduce the flow cross-sectional area of ​​the modified turbine to the calculated flow cross-sectional area; wherein, the fuel step coefficient adjusted at any given time... b Less than the fuel step coefficient a , a The fuel step coefficient that causes the compression system to enter a surge state when the fuel step method is used alone; After the flow cross-sectional area of ​​the modified turbine used in the test reaches the calculated flow cross-sectional area, the finally determined fuel step coefficient is used. b Perform forced breathing and determine whether the compression system has entered a surge state; In response to the judgment that the compression system has not entered a surge state, the stator blades of the modified turbine for testing are controlled to rotate gradually to continue reducing the flow cross-sectional area, and after each reduction in the flow cross-sectional area, the finally determined fuel step coefficient is used. b Perform a fuel step and determine whether the compression system has entered a surge state, until the compression system enters a surge state.

4. The method according to claim 3, characterized in that, The continuous adjustment of the fuel step coefficient b To make the fuel flow rate according to b A step change occurs in the ratio, including: Set the initial fuel step coefficient for fuel flow. b and set the initial fuel step coefficient b As the current fuel step coefficient b Perform the following fuel step coefficient adjustment operation until the fuel flow rate is in accordance with... b The ratio changes abruptly by a factor of 1: The oil step coefficient adjustment operation includes: Based on the current fuel step coefficient b Adjust the flow cross-sectional area of ​​the modified turbine used in the test and increase the amount of fuel supplied to the combustion chamber; Determine whether the oil supply system can operate within the adjusted flow cross-sectional area. b A step change in fuel flow can be achieved by multiplying the flow rate by a factor of two. Unable to follow b When a step change in fuel flow is achieved by a factor of 1, continue to adjust the fuel step coefficient. b And the adjusted fuel step coefficient b As an updated current fuel step coefficient b Continue with the fuel step coefficient adjustment operation.

5. The method according to claim 1, characterized in that, Controlling the stator blades of the modified turbine for testing to gradually rotate to reduce the flow cross-sectional area of ​​the modified turbine for testing, and in conjunction with the high-pressure gas charging method, forcing the compression system to surge until the compression system enters a surge state, including: Set the initial flow cross-sectional area required for the modified turbine used in the test, set the initial heating temperature for the heating device to heat the gas storage chamber, and use the set initial flow cross-sectional area as the current flow cross-sectional area and the set initial heating temperature as the current heating temperature, and perform the following forced surge operation until the compression system enters the surge state. The breathing-inducing procedure includes: The valve is closed, and the heating device is used to heat the high-pressure gas in the gas storage chamber at the current heating temperature to generate high-temperature, high-pressure gas. The valve is opened to allow the high-temperature, high-pressure gas in the gas storage chamber to enter the combustion chamber, thereby forcing the compression system to surge. During the surge process, it is determined whether the compression system has entered a surge state. In response to the determination that the compression system has not entered a surge state, the current flow cross-sectional area is reduced to obtain an updated current flow cross-sectional area and / or the current heating temperature is increased to obtain an updated current heating temperature, and the surge-forcing operation is continued using the updated current flow cross-sectional area and / or the updated current heating temperature.

6. The method according to claim 1, characterized in that, The temperature of the gas inside the gas storage chamber as follows: and ; ； in, The temperature of the gas inside the gas storage chamber. The outlet static temperature is the temperature at which the compressor is operating stably under test conditions. The outlet static pressure is the compressor's stable operating pressure at the test operating point. This refers to the inlet pressure of the combustion chamber when the aerodynamic instability boundary is reached during the gas expulsion process. It is the equivalent aerodynamic volume of the combustion chamber. It is the aerodynamic volume of the air storage chamber. The calorific value of the fuel. For the specific heat capacity of the gas, The pre-set fuel step coefficient, Less than a , a The fuel step coefficient that causes the compression system to enter a surge state when the fuel step method is used alone; This represents the airflow rate at the compressor outlet. It is the fuel flow rate when the engine is operating stably.

7. The method according to claim 2, characterized in that, Whether the engine has entered a surge state is determined based on whether the operating information of the engine test device meets the criteria for entering a surge state. The operating information of the engine testing device includes: physical quantities used to characterize the performance of the compression system and signals used to characterize the operating status of the engine testing device; The criteria for determining the surge state include at least one of the following: the physical quantity characterizing the performance of the compression system meets the set surge condition, and the signal characterizing the operating state of the engine test device shows a set surge signal.

8. An engine testing apparatus, characterized in that, include: Engine body, modified turbine for testing with variable flow cross-sectional area, and test control device. The test control device includes a memory and a processor, wherein the memory is configured to store an executable program; The processor is configured to read and execute the executable program to perform the method for determining the aerodynamic instability boundary under the whole machine environment as described in any one of claims 1-7.

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