Aviation Engine Composite Supercharging Matching Evaluation and High-Altitude Performance Recovery Optimization Method

Abstract

The present invention discloses a method for evaluating the compound supercharging matching of an aeroengine and optimizing the recovery of high-altitude performance, which comprises the following steps: establishing a first series arrangement simulation model and a second series arrangement simulation model; running the two simulation models, changing the altitude environment, and obtaining the specific values of multiple system performance evaluation indexes at different altitudes; establishing multiple fuzzy evaluation membership functions, and substituting the specific values into the fuzzy evaluation membership functions correspondingly to obtain the membership function values; establishing a performance fuzzy evaluation matrix, assigning certain weights to the system performance evaluation indexes to obtain an evaluation matrix, and calculating to obtain the evaluation scores of the two simulation models; determining the optimal series arrangement simulation model according to the evaluation scores, and optimizing the high-altitude performance recovery parameters of the optimal series arrangement simulation model. The present invention makes up for the blank in the research on the supercharging matching evaluation of the overhead valve two-stroke aero piston engine under high-altitude conditions and the optimization of high-altitude performance recovery parameters.

Description

Technical Field

[0001] The present invention relates to the technical field of aviation piston engines, and particularly to a method for evaluating the matching of compound supercharging of an aeroengine and optimizing the high-altitude performance recovery. Background Technique

[0002] Aviation piston engines are widely used power devices for general aviation aircraft and unmanned aerial vehicles. Against the background of the general trend of electrification, at present, aviation piston engines still have advantages such as strong endurance and relatively high flight ceiling compared with pure electric power. Especially in the medium power range, they still have great development potential, and compared with aviation turbine engines, they have advantages such as good fuel economy, relatively low manufacturing and use costs, and convenient maintenance. The requirements for the long endurance and high load-carrying capacity of aircraft have put forward higher requirements for the lightweight and power-to-weight ratio of aviation piston engines.

[0003] Since the working frequency of a two-stroke engine is twice that of a four-stroke engine, the two-stroke aviation piston engine has obvious advantages in power per liter and power-to-weight ratio compared with the four-stroke engine. The overhead valve two-stroke is a new layout form of the two-stroke aviation piston engine. Its PV2S scavenging system structure is similar to that of the four-stroke engine and no longer has a port structure. Its intake valve and exhaust valve are both arranged on the cylinder head. Because it has the potential to reduce fuel consumption and carbon emissions and improve thermal efficiency, it has received more attention in various power fields. The application of the overhead valve two-stroke form to an aviation piston engine can not only retain the traditional advantages of the two-stroke engine such as high power per liter and good torque uniformity, but also has new advantages such as less lubricating oil consumption and flexible and controllable valve timing. Whether it is a gasoline piston or a diesel piston, it has broad prospects.

[0004] Supercharging is the main way to recover the intake pressure and power loss of a two-stroke aviation piston engine at high altitudes, including using a mechanical supercharger driven by a crankshaft or an electric motor and a turbocharger driven by exhaust gas, etc. Most two-stroke aviation piston engines use turbocharging, and two-stage turbocharging or a combination of a turbine and a mechanical supercharger is used at higher altitudes. High-altitude supercharging not only directly affects the cyclic intake air volume of the scavenging process, but also determines the intake and exhaust pressure and temperature boundaries of the scavenging, thus affecting the scavenging performance; conversely, the control of exhaust gas and exhaust temperature during the scavenging process has a greater impact on the efficiency and available work of the turbine of the turbocharger. Due to the strong coupling relationship between supercharging and scavenging, the performance of supercharging and scavenging is very sensitive to changes in engine operating parameters and environmental changes brought about by the working altitude. Good scavenging and supercharging matching is the key technology to ensure the high-altitude performance of a two-stroke engine.

[0005] For an overhead valve two-stroke aviation piston engine, a relatively large positive pressure difference needs to be established between the intake and exhaust ports to ensure sufficient intake air volume and high charging efficiency. Therefore, supercharging the overhead valve two-stroke aviation piston engine is a prerequisite for its normal operation. In current research, there are three types of supercharging systems that match the overhead valve two-stroke aviation piston engine: single-stage mechanical supercharging, single-stage turbocharging, and turbo-mechanical compound supercharging. It has been proven that single-stage turbocharging for an overhead valve two-stroke aviation piston engine has instability, especially at low engine speeds.

[0006] Compound supercharging for an overhead valve two-stroke aviation piston engine was proposed to overcome the shortcomings of matching single-stage mechanical or turbocharging. The layout schemes of compound supercharging can be divided into two forms: series and parallel. The parallel form (the intake air enters the compressors of mechanical and turbocharging simultaneously) has less requirement for the flow range of the supercharger, but the compressor is prone to surge at low loads. If the overhead valve two-stroke aviation piston engine adopts the parallel scheme, in the single-turbocharging mode, the engine's scavenging performance is low, and the surge problem cannot be avoided even under low-load conditions; in the single-mechanical supercharging mode, the mechanical work consumption is too large at high altitudes; in the compound supercharging mode, due to the shunt effect of the parallel connection, the flow range of the MAP diagrams of both compressors can be relatively small. However, if you want to increase the altitude ceiling of the aviation piston engine, a compressor with a relatively large pressure ratio must be designed, and the MAP diagram presents a narrow and high rectangular shape, increasing the design difficulty of the compressor impeller. Moreover, at high altitudes, the pressure and flow of the two incoming airflows are likely to be different, resulting in unstable air-flow convergence and engine operation, a reduction in the flow rate through the turbocharger, and more prone to surge. Therefore, the parallel layout scheme is not suitable for matching with the overhead valve two-stroke aviation piston engine. The series layout scheme has a low single-stage pressure ratio for turbocharging and mechanical supercharging, reducing the tendency of surge and being conducive to achieving a higher total pressure ratio. When the aviation piston engine operates at low speeds, the combined operation of turbocharging and mechanical supercharging can increase the pressure ratio and intake air volume, helping to improve the low-speed characteristics. When the engine operates at higher speeds or high altitudes, it can rely more on the turbocharger and reduce the work consumption of the mechanical supercharger. Therefore, it is more suitable for matching with the aviation piston engine. The series scheme is the key technology for the overhead valve two-stroke aviation piston engine to match with compound supercharging. The parallel layout scheme is only adopted when the layout conditions of the overhead valve two-stroke aviation piston engine are limited to this form.

[0007] The turbo-mechanical series compound supercharging scheme can combine the advantages of the two turbo-mechanical supercharging systems to improve the scavenging and power performance of the overhead valve two-stroke aviation piston engine. However, there is currently little research on this scheme, especially on the supercharging matching evaluation under high-altitude conditions of the overhead valve two-stroke aviation piston engine and the parameter optimization method for high-altitude performance recovery, which is currently relatively blank. Summary of the Invention

[0008] The present invention aims to solve at least one of the technical problems existing in the prior art. For this purpose, an object of the present invention is to provide a method for evaluating the composite supercharging matching of an aeroengine and optimizing the high-altitude performance recovery, which makes up for the research gap in the evaluation of the supercharging matching under high-altitude conditions and the optimization method of high-altitude performance recovery parameters for overhead valve two-stroke aero piston engines.

[0009] The method for evaluating the composite supercharging matching of an aeroengine and optimizing the high-altitude performance recovery according to the embodiment of the present invention includes the following steps:

[0010] S1: Establish a first series arrangement simulation model and a second series arrangement simulation model. Both the first series arrangement simulation model and the second series arrangement simulation model include an aeroengine, a composite supercharging system, and an environment module. The composite supercharging system is used to supercharge the aeroengine. The composite supercharging system includes a mechanically driven supercharger and a turbocharger arranged in series. The environment module is used to simulate environments at different altitudes;

[0011] S2: Run the first series arrangement simulation model and the second series arrangement simulation model, change the altitude environment, and obtain the specific values of multiple system performance evaluation indexes of the first series arrangement simulation model and the second series arrangement simulation model at different altitudes;

[0012] S3: According to the performance range of the aeroengine, establish multiple fuzzy evaluation membership functions corresponding one by one to the multiple system performance evaluation indexes, and substitute the specific values of the multiple system performance evaluation indexes of the obtained first series arrangement simulation model and the second series arrangement simulation model at different altitudes into the multiple fuzzy evaluation membership functions respectively to obtain the membership function values of the first series arrangement simulation model and the second series arrangement simulation model;

[0013] S4: Establish a performance fuzzy evaluation matrix including multiple fuzzy evaluation membership functions of the first series arrangement simulation model and the second series arrangement simulation model at different altitudes, conduct a comprehensive analysis on the importance degrees of the multiple system performance evaluation indexes, assign certain weights to the multiple system performance evaluation indexes, combine the corresponding weights of the multiple system performance evaluation indexes with the performance fuzzy evaluation matrix, and finally obtain multiple evaluation matrices at different altitudes. Substitute the obtained membership function values into the multiple evaluation matrices respectively, and calculate the evaluation scores of the first series arrangement simulation model and the second series arrangement simulation model at different altitudes;

[0014] S5: Determine the optimal series arrangement simulation model according to the evaluation scores, and optimize the high-altitude performance recovery parameters of the optimal series arrangement simulation model.

[0015] According to the aviation engine compound supercharging matching evaluation and high-altitude performance recovery optimization method of the embodiments of the present invention, on the one hand, by running the first series arrangement simulation model and the second series arrangement simulation model under the high-altitude simulation conditions at different altitudes, the influence of different series arrangement supercharging schemes on the system performance under high-altitude conditions is obtained, and the fuzzy evaluation membership function, the performance fuzzy evaluation matrix and the evaluation matrix are introduced in turn to comprehensively, synthetically and quantitatively evaluate the system performance of different series arrangement supercharging schemes under high-altitude conditions, so as to achieve the effect of quantitatively evaluating the differences between the first series arrangement simulation model and the second series arrangement simulation model, and an all-round and systematic evaluation system for the aviation piston engine compound supercharging scheme is established. On the other hand, by optimizing the high-altitude performance recovery parameters of the optimal series arrangement simulation model, it is beneficial to make the optimal series arrangement simulation model reach the optimal high-altitude operating state, filling the blank of the high-altitude parameter optimization of the current aviation piston engine under compound supercharging.

[0016] According to some embodiments of the present invention, the aviation engine is an overhead valve two-stroke aviation piston engine.

[0017] According to some embodiments of the present invention, the multiple system performance evaluation indexes include the effective fuel consumption rate, the charging efficiency of the scavenging process, the proportion of the work consumed by the mechanical supercharger in the effective power, the compressor efficiency of the mechanical supercharger, and the compressor efficiency of the turbocharger.

[0018] According to some embodiments of the present invention, the aviation engine compound supercharging matching evaluation and high-altitude performance recovery optimization method further includes changing the rotational speed of the aviation engine, and then cyclically performing steps S2, S3 and S4 to obtain the evaluation scores of the first series arrangement simulation model and the second series arrangement simulation model at different rotational speeds and different altitudes.

[0019] According to some embodiments of the present invention, the multiple fuzzy evaluation membership functions corresponding one-to-one to the multiple system performance evaluation indexes are all trapezoidal distribution functions.

[0020] According to some embodiments of the present invention, the optimization of the high-altitude performance recovery parameters of the optimal series arrangement simulation model in step S5 includes the following steps:

[0021] S501: Run the optimal series arrangement simulation model, and successively change the altitude environment, the supercharging ratio distribution ratio of the mechanical supercharger and the turbocharger, and the rotational speed of the aviation engine to obtain the mechanical supercharger compressor efficiency and turbocharger compressor efficiency data at different altitudes, different supercharging ratio distribution ratios and different engine rotational speeds;

[0022] S502: Considering that both the supercharger compressor and the turbocharger compressor should operate in the high-efficiency range far from the surge and choke boundaries, analyze the data of the supercharger compressor efficiency and the turbocharger compressor efficiency obtained in step S501 to obtain the most reasonable supercharging ratio distribution ratios in the low altitude range and the high altitude range.

[0023] According to some embodiments of the present invention, optimizing the high-altitude performance recovery parameters of the optimal series arrangement simulation model in step S5 further includes the following steps:

[0024] S503: Run the optimal series arrangement simulation model, sequentially change the altitude environment, the supercharging ratio distribution ratios of the supercharger and the turbocharger, and the rotational speed of the aero-engine, and measure the capture rate and the scavenging efficiency data of the aero-engine scavenging process at different altitudes, different supercharging ratio distribution ratios, and different engine rotational speeds;

[0025] S504: On the premise that both the supercharger compressor and the turbocharger compressor should operate in the high-efficiency range, considering that the capture rate and the scavenging efficiency of the aero-engine scavenging process need to be at a high level, analyze the capture rate and the scavenging efficiency data obtained in step S503 to obtain the most reasonable supercharging ratio distribution ratios in the low altitude range and the high altitude range.

[0026] According to some embodiments of the present invention, optimizing the high-altitude performance recovery parameters of the optimal series arrangement simulation model in step S5 further includes the following steps:

[0027] S505: Run the optimal series arrangement simulation model, sequentially change the valve timing of the aero-engine and the altitude environment, and obtain the capture rate and the scavenging efficiency data of the aero-engine scavenging process under different valve timings and different altitude environments;

[0028] S506: Taking the scavenging efficiency as the most important index, analyze the capture rate and the scavenging efficiency data of the scavenging process obtained in step S505 to determine the most suitable valve timing at different altitudes.

[0029] According to some embodiments of the present invention, optimizing the high-altitude performance recovery parameters of the optimal series arrangement simulation model in step S5 further includes the following steps:

[0030] S507: Optimize the length of the exhaust manifold and the volume of the exhaust chamber of the aero-engine to change the constant pressure turbocharging mode into the pulse turbocharging mode and make the charging efficiency and the capture rate of the aero-engine scavenging process both reach a high level.

[0031] According to some embodiments of the present invention, the method for evaluating the matching of aero-engine compound supercharging and optimizing the high-altitude performance recovery further includes calculating and comparing the optimized optimal series arrangement simulation model with the optimal series arrangement simulation model before optimization, and in practice, conducting a test bench experiment on the aero-engine and the compound supercharging system before and after optimizing the high-altitude performance recovery parameters.

[0032] Additional aspects and advantages of the present invention will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the description of the embodiments in conjunction with the following drawings, wherein:

[0034] Figure 1 is a flowchart of the method for evaluating the matching of aero-engine compound supercharging and optimizing the high-altitude performance recovery according to an embodiment of the present invention.

[0035] Figure 2 is a flowchart of optimizing the high-altitude performance recovery parameters of the optimal series arrangement simulation model according to an embodiment of the present invention.

[0036] Figure 3 is a schematic structural diagram of the aero-engine and the compound supercharging system in the first series arrangement simulation model according to an embodiment of the present invention.

[0037] Figure 4 is a schematic structural diagram of the aero-engine and the compound supercharging system in the second series arrangement simulation model according to an embodiment of the present invention.

[0038] Figure 5 is a data comparison chart of the evaluation scores of the first series arrangement simulation model (compound supercharging scheme A) and the second series arrangement simulation model (compound supercharging scheme B) according to an embodiment of the present invention at different altitude heights under the condition that the aero-engine speed is 2400 r / min.

[0039] Figure 6 is a data comparison chart of the evaluation scores of the first series arrangement simulation model (compound supercharging scheme A) and the second series arrangement simulation model (compound supercharging scheme B) according to an embodiment of the present invention at different altitude heights under the condition that the aero-engine speed is 2100 r / min.

[0040] Figure 7 is a data comparison chart of the evaluation scores of the first series arrangement simulation model (compound supercharging scheme A) and the second series arrangement simulation model (compound supercharging scheme B) according to an embodiment of the present invention at different altitude heights under the condition that the aero-engine speed is 1800 r / min.

[0041] Reference numerals:

[0042] Overhead valve two-stroke aero piston engine 1; mechanical supercharger 2; first control unit 201; bypass valve 202;

[0043] Turbocharger 3; waste gas valve 301; second control unit 302; intercooler 4. Detailed implementation manners

[0044] Embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary and are only used to explain the present invention and should not be construed as a limitation of the present invention.

[0045] The following combines Figures 1 to 7 to describe the aero engine compound supercharging matching evaluation and high-altitude performance recovery optimization method of the present invention.

[0046] As Figure 1 shown, the aero engine compound supercharging matching evaluation and high-altitude performance recovery optimization method according to an embodiment of the present invention includes the following steps:

[0047] S1: Establish a first series arrangement simulation model and a second series arrangement simulation model. Both the first series arrangement simulation model and the second series arrangement simulation model include an aero engine, a compound supercharging system, and an environment module. The compound supercharging system is used to supercharge the aero engine. The compound supercharging system includes a mechanically supercharger 2 and a turbocharger 3 arranged in series. The environment module is used to simulate different altitude environments;

[0048] S2: Run the first series arrangement simulation model and the second series arrangement simulation model, change the altitude environment, and obtain the specific values of multiple system performance evaluation indexes of the first series arrangement simulation model and the second series arrangement simulation model at different altitudes;

[0049] S3: According to the performance range of the aero engine, establish multiple fuzzy evaluation membership functions corresponding one by one to the multiple system performance evaluation indexes, and substitute the specific values of the multiple system performance evaluation indexes of the obtained first series arrangement simulation model and the second series arrangement simulation model at different altitudes into the multiple fuzzy evaluation membership functions respectively to obtain the membership function values of the first series arrangement simulation model and the second series arrangement simulation model;

[0050] S4: Establish a performance fuzzy evaluation matrix of multiple fuzzy evaluation membership functions including the first series - arrangement simulation model and the second series - arrangement simulation model at different altitudes, comprehensively analyze the importance of multiple system performance evaluation indicators, assign certain weights to multiple system performance evaluation indicators, combine the corresponding weights of multiple system performance evaluation indicators with the performance fuzzy evaluation matrix, finally obtain multiple evaluation matrices at different altitudes, substitute the obtained membership function values into the multiple evaluation matrices correspondingly, and calculate the evaluation scores of the first series - arrangement simulation model and the second series - arrangement simulation model at different altitudes;

[0051] S5: Determine the optimal series - arrangement simulation model according to the evaluation scores, and optimize the high - altitude performance recovery parameters of the optimal series - arrangement simulation model.

[0052] Specifically, establish the first series - arrangement simulation model and the second series - arrangement simulation model. Both the first series - arrangement simulation model and the second series - arrangement simulation model conform to the specific structure, system arrangement form, relevant power performance and requirements of the aviation piston engine. The first series - arrangement simulation model and the second series - arrangement simulation model can be established by using commercial software for engine performance analysis or self - written programs. Preferably, the widely used GT - Power software can be selected for establishment, and both the established first series - arrangement simulation model and the second series - arrangement simulation model are one - dimensional simulation models.

[0053] Both the first series - arrangement simulation model and the second series - arrangement simulation model include an aviation engine, a compound supercharging system and an environment module. The aviation engine is an aviation piston engine, which includes a cylinder system, a crank - connecting rod system and an exhaust system. The compound supercharging system includes a mechanically - driven supercharger 2 and a turbocharger 3 arranged in series. The compound supercharging system is used to supercharge the aviation engine, that is, to supercharge the intake air of the aviation engine to establish a relatively large positive pressure difference between the intake duct and the exhaust duct. The environment module is used for simulating environments at different altitudes. Environment modules are provided in both the compound supercharging system and the exhaust system. By inputting parameters such as pressure, temperature, humidity, etc. in the environment module at different altitude environments, the requirements for simulating the working conditions of the aviation piston engine at different altitudes can be met. It can be understood that the series - connection methods of the mechanically - driven supercharger 2 and the turbocharger 3 in the compound supercharging systems of the first series - arrangement simulation model and the second series - arrangement simulation model are different.

[0054] Figure 3 FIG. is a schematic structural diagram of the aviation engine and the compound supercharging system in the first series - arrangement simulation model in the embodiment of the present invention. Figure 4 FIG. is a schematic structural diagram of the aviation engine and the compound supercharging system in the second series - arrangement simulation model in the embodiment of the present invention. As Figure 3 and Figure 4As shown in the figure, the supercharger 2 is driven by the crankshaft of the aero piston engine, and the transmission ratio can be adjusted through the first control unit 201 to realize the adjustment of the rotational speed and boost ratio of the supercharger 2; the intercooler 4 is connected between the supercharger 2 and the turbocharger 3 to cool the temperature of the supercharged gas, so as to increase the intake air volume; the supercharger 2 and the bypass valve 202 are arranged in parallel. The supercharger 2 includes a supercharger compressor. The bypass valve 202 is used to assist in adjusting the flow rate and boost ratio of the supercharger 2. The boost ratio of the supercharger 2 is defined as the ratio of the pressure after the two-way gas of the bypass valve 202 and the supercharger 2 converges to the ambient pressure. The turbocharger 3 and the waste gas valve 301 are arranged in parallel. The turbocharger 3 includes a turbocharger compressor. The waste gas valve 301 is used to control the amount of waste gas flowing through the turbocharger 3. The waste gas valve 301 is controlled by the second control unit 302 to control the rotational speed and boost ratio of the turbocharger 3.

[0055] The structural parameters of each part in the first series arrangement simulation model and the second series arrangement simulation model are determined by referring to the design drawings of the specific prototype (physical machine) or taking their equivalent values. For example, in reality, the cross-section of the intake and exhaust ducts of the aero piston engine is not circular, so the diameters of the intake and exhaust ducts in the first series arrangement simulation model and the second series arrangement simulation model are taken as the values corresponding to the equivalent cross-section. In the cylinder system, the number and diameter values of the nozzle holes of the injector module are determined according to the actual injector, the cyclic fuel injection volume is determined according to the load of the aero engine, and the fuel injection advance angle is taken as the optimized value obtained from simulation and tests. The temperature values of each wall surface of the cylinder block, including the cylinder liner, piston crown and cylinder head, are measured by tests. The Woschni model is used to calculate the heat transfer of the high-temperature gas and scavenging flow to the cylinder wall and the piston, so that the calculated heat transfer amount has good consistency with the measured value. The Wiebe combustion model is used for the in-cylinder combustion model. It does not need to describe the spray process in detail. During the calculation, only the cyclic fuel injection volume needs to be provided to ensure the accuracy of the first series arrangement simulation model and the second series arrangement simulation model in the simulation of power performance, initial scavenging and compound supercharging boundary conditions. In the modeling of the crank connecting rod system, the weight and dimension data of components such as the crankshaft, connecting rod and piston are all from the measurement data of real components, and the piston motion law, effective compression ratio, etc. are also verified by tests on real aero engines.

[0056] Since the operating state of the aero piston engine is unstable when only the turbocharger 3 is working, the operating mode of the series scheme is that the supercharger 2 starts to work first, and then the turbocharger 3 runs.

[0057] Run the first series-arrangement simulation model and the second series-arrangement simulation model, change the altitude environment, that is, input parameters such as pressure, temperature, humidity, etc. under different altitude environments into the environment module, and obtain the specific values of multiple system performance evaluation indicators of the first series-arrangement simulation model and the second series-arrangement simulation model at different altitudes, so as to study the system performance of the first series-arrangement simulation model and the second series-arrangement simulation model in the high-altitude state. For example, make both the first series-arrangement simulation model and the second series-arrangement simulation model run at an altitude of 2000 m, record or calculate the specific values of multiple system performance evaluation indicators, and perform multiple simulation simulations in this way within the altitude range of 2000 m - 8000 m. At this time, the aero-engines in the first series-arrangement simulation model and the second series-arrangement simulation model operate at the same speed and load. For example, the speeds are all 2100 r / min or 2400 r / min or 1800 r / min, and the loads are all 100%, and the compound supercharging system operates at the same supercharging ratio distribution ratio, such as 5:5.

[0058] Multiple system performance evaluation indicators are determined according to the application characteristics of the compound supercharged aero-piston engine and the performance requirements at each altitude. Specifically, for example, multiple system performance evaluation indicators can be the effective fuel consumption rate / (g / kW·h), the proportion of the work consumed by the mechanical supercharger in the effective power / %, the charging efficiency during the scavenging process / -, the compressor efficiency of the turbocharger / %, and the compressor efficiency of the mechanical supercharger / %. Among them, the effective fuel consumption rate is used to evaluate the fuel economy of the high-altitude aero-piston engine after supercharging; the proportion of the work consumed by the mechanical supercharger in the effective power can not only reflect the energy consumption demand of the mechanical supercharger, but also reflect the degree of intervention of the turbocharging from the side. The smaller the proportion, the less work the compound supercharging system consumes and the greater the benefit of supercharging; the charging efficiency during the scavenging process is used to evaluate the comprehensive scavenging performance of the aero-piston engine at high altitude after the compound supercharging system is involved; the compressor efficiency of the turbocharger and the compressor efficiency of the mechanical supercharger evaluate the performance of the two compressors of the compound supercharging system and the high-altitude safety boundary respectively; therefore, the above five system performance evaluation indicators can comprehensively evaluate the compound supercharging system scheme of the overhead valve two-stroke aero-piston engine.

[0059] According to the performance range of an aero-engine, multiple fuzzy evaluation membership functions corresponding one by one to multiple system performance evaluation indexes are established, and the specific values of multiple system performance evaluation indexes of the obtained first series arrangement simulation model and second series arrangement simulation model at different altitudes are substituted into the multiple fuzzy evaluation membership functions correspondingly to obtain the membership function values of the first series arrangement simulation model and the second series arrangement simulation model. For example, let the set of system performance evaluation indexes be \(x = [x_1, x_2, x_3, x_4, x_5]=[\text{specific fuel consumption} / (g / kW\cdot h), \text{proportion of mechanical supercharger power consumption in effective power} / \%, \text{charging efficiency during scavenging process} / -, \text{compressor efficiency of turbocharger} / \%, \text{compressor efficiency of mechanical supercharger} / \%]\); for the set of system performance evaluation indexes, assuming that for any element \(x\) in the universe of discourse \(U\) (within the research range), there is a corresponding normalized evaluation index, then it is called a fuzzy set on \(U\), and \(f(x)\) is defined as the membership degree of \(x\) to \(f\). And when the value of \(x\) changes in the universe of discourse \(U\), \(f(x)\) becomes a function, which is called the fuzzy evaluation membership function of \(f\). The fuzzy evaluation membership function \(f(x)\) with a value range of \([0, 1]\) characterizes the degree. The closer its value is to 1, the greater the degree of \(f\), and the better the performance corresponding to the value of this system performance evaluation index. That is to say, the fuzzy evaluation membership function can normalize the specific value of each system performance evaluation index.

[0060] Establish a performance fuzzy evaluation matrix of multiple fuzzy evaluation membership functions including the first series arrangement simulation model and the second series arrangement simulation model at different altitudes. For example, the performance fuzzy evaluation matrix \(\alpha\) i , where \(i\) represents different altitudes. For example, when \(i = 2\), the altitude is 2000m, and when \(i = 8\), the altitude is 8000m. Conduct a comprehensive analysis of the importance of multiple system performance evaluation indexes and assign certain weights to multiple system performance evaluation indexes. For example, set the weight coefficient of the specific fuel consumption to 0.3, set the weight coefficient of the proportion of mechanical supercharger power consumption in effective power to 0.1, set the weight coefficient of the charging efficiency during scavenging process to 0.3, set the weight coefficient of the compressor efficiency of the turbocharger to 0.15, and set the weight coefficient of the compressor efficiency of the mechanical supercharger to 0.15.

[0061] Combine the corresponding weights of multiple system performance evaluation indexes with the performance fuzzy evaluation matrix to finally obtain multiple evaluation matrices at different altitudes. For example, the evaluation matrix \(R\) i =[0.3, 0.1, 0.3, 0.15, 0.15]\(\cdot\)\(\alpha\) iSubstitute the obtained membership function values into multiple evaluation matrices respectively to calculate the evaluation scores of the first series-arranged simulation model and the second series-arranged simulation model at different altitudes, and determine the optimal series-arranged simulation model according to the evaluation scores. Thus, the present invention can achieve the effect of quantitatively evaluating the differences between the first series-arranged simulation model and the second series-arranged simulation model, and establish an all-round and systematic evaluation system for the compound supercharging scheme of the aviation piston engine.

[0062] Optimize the high-altitude performance recovery parameters of the optimal series-arranged simulation model, which is beneficial to making the optimal series-arranged simulation model reach the optimal high-altitude operating state. By optimizing the high-altitude performance recovery parameters of the optimal series-arranged simulation model, the present invention fills the blank of the high-altitude parameter optimization of the current aviation piston engine under compound supercharging.

[0063] According to the aviation engine compound supercharging matching evaluation and high-altitude performance recovery optimization method of the embodiments of the present invention, on the one hand, by making the first series-arranged simulation model and the second series-arranged simulation model operate under the high-altitude simulation conditions at different altitudes, obtain the influence of different series-arranged supercharging schemes on the system performance under high-altitude conditions, and successively introduce the fuzzy evaluation membership function, the performance fuzzy evaluation matrix and the evaluation matrix to comprehensively, synthetically and quantitatively evaluate the system performance of different series-arranged supercharging schemes under high-altitude conditions, so as to achieve the effect of quantitatively evaluating the differences between the first series-arranged simulation model and the second series-arranged simulation model, and establish an all-round and systematic evaluation system for the compound supercharging scheme of the aviation piston engine. On the other hand, by optimizing the high-altitude performance recovery parameters of the optimal series-arranged simulation model, it is beneficial to making the optimal series-arranged simulation model reach the optimal high-altitude operating state, filling the blank of the high-altitude parameter optimization of the current aviation piston engine under compound supercharging.

[0064] According to some embodiments of the present invention, before quantitatively analyzing the first series-arranged simulation model and the second series-arranged simulation model, since there are differences between different aviation piston engines, such as two-cylinder four-cylinder, V-type arrangement, in-line arrangement, etc., it is necessary to draw up the preferred arrangement schemes of the components in the first series-arranged simulation model and the second series-arranged simulation model starting from the corresponding aviation piston engine structure, system arrangement form, etc.

[0065] According to some embodiments of the present invention, the aviation engine is an overhead valve two-stroke aviation piston engine 1. The present invention is beneficial to more objectively and comprehensively match the most suitable compound supercharging system scheme for the overhead valve two-stroke aviation piston engine 1, and optimize the high-altitude performance recovery parameters of the most suitable compound supercharging system scheme, laying a foundation for the practical application of the overhead valve two-stroke aviation piston engine 1.

[0066] According to some embodiments of the present invention, multiple system performance evaluation indicators include effective fuel consumption rate, charging efficiency during the scavenging process, the proportion of the work consumed by the mechanical supercharger in the effective power, the compressor efficiency of the mechanical supercharger, and the compressor efficiency of the turbocharger. The above five indicators can comprehensively evaluate the compound supercharging system scheme of the overhead valve two-stroke aero piston engine 1. Thus, the present invention establishes an all-round and systematic evaluation system for the overhead valve two-stroke aero piston engine 1.

[0067] According to some embodiments of the present invention, it further includes changing the speed of the aero engine, and then cyclically performing steps S2, S3, and S4 to obtain the evaluation scores of the first series arrangement simulation model and the second series arrangement simulation model at different speeds and different altitude levels. Thus, the present invention can not only obtain the influence of the first series arrangement scheme and the second series arrangement scheme on the system performance under different altitude conditions, but also obtain the influence of the first series arrangement scheme and the second series arrangement scheme on the system performance under different speed conditions, which is beneficial to more comprehensively evaluate the first series arrangement scheme and the second series arrangement scheme.

[0068] For example, the first series arrangement simulation model may include a structure as shown in Figure 3 , where the mechanical supercharger 2 is the low-pressure stage and the turbocharger 3 is the high-pressure stage; the second series arrangement simulation model may include a structure as shown in Figure 4 , where the turbocharger 3 is the low-pressure stage and the mechanical supercharger 2 is the high-pressure stage. Figures 5 - 7 Illustrates the evaluation scores of the first series arrangement simulation model and the second series arrangement simulation model under different altitude conditions and different speed conditions. Among them, the compound supercharging scheme A corresponds to the first series arrangement simulation model including the structure as shown in Figure 3 , and the compound supercharging scheme B corresponds to the second series arrangement simulation model including the structure as shown in Figure 4 .

[0069] According to some embodiments of the present invention, multiple fuzzy evaluation membership functions corresponding one-to-one to multiple system performance evaluation indicators are all trapezoidal distribution functions. Here, using the trapezoidal distribution function to establish the fuzzy evaluation membership function has good use effect and is convenient for calculation.

[0070] Specifically, the smaller the effective fuel consumption rate of the aero engine after compound supercharging, the better the fuel economy. Therefore, the fuzzy evaluation membership function of the effective fuel consumption rate selects a smaller trapezoidal distribution. For a certain overhead valve two-stroke aero piston engine 1, considering the fuel consumption range at all altitude levels, the fuzzy evaluation membership function of the effective fuel consumption rate x1 is established as follows:

[0071]

[0072] The smaller the proportion of the work consumed by the supercharger in the effective power, the greater the benefit of supercharging. Therefore, the fuzzy evaluation membership function of the proportion of the work consumed by the supercharger in the effective power also selects a trapezoidal distribution of the smaller type. For a certain overhead valve two-stroke aero piston engine 1, referring to the change of the proportion of the work consumed by the supercharger in the effective power x2 within the full altitude range, the fuzzy evaluation membership function of the proportion of the work consumed by the supercharger in the effective power x2 is established as follows:

[0073]

[0074] The greater the charging efficiency, the better the high-altitude air exchange performance of the overhead valve two-stroke aero piston engine 1 with compound supercharging matching. As a performance index that the greater the better, a trapezoidal distribution of the larger type should be selected. For a certain overhead valve two-stroke aero piston engine 1, referring to the change range of the charging efficiency at the full altitude, the fuzzy evaluation membership function of the charging efficiency x3 is established as follows:

[0075]

[0076] The greater the compressor efficiency of the turbocharger, the better the performance state of the compressor, and a trapezoidal distribution of the larger type should also be selected. For a certain overhead valve two-stroke aero piston engine 1, referring to the efficiency range of each altitude operating point on the MAP diagram, the fuzzy evaluation membership function of the compressor efficiency x4 of the turbocharger is established as follows:

[0077]

[0078] The greater the compressor efficiency of the supercharger, the better the performance state of the compressor, and a trapezoidal distribution of the larger type should also be selected. For a certain overhead valve two-stroke aero piston engine 1, referring to the efficiency range of each altitude operating point on the MAP diagram, the fuzzy evaluation membership function of the compressor efficiency x5 of the supercharger is established as follows:

[0079]

[0080] Substitute the specific numerical values of multiple system performance evaluation indexes of the obtained first series arrangement simulation model and the second series arrangement simulation model at different altitudes into the above multiple fuzzy evaluation membership functions to obtain the membership function values of the first series arrangement simulation model and the second series arrangement simulation model.

[0081] Correspondingly, establish a performance fuzzy evaluation matrix of multiple fuzzy evaluation membership functions including the first series arrangement simulation model and the second series arrangement simulation model at different altitudes. Specifically, for example, the performance fuzzy evaluation matrix α at a certain altitude i is as follows:

[0082]

[0083] Wherein, i represents the altitude. If i = 2, it represents the operating condition at an altitude of 2000 m. A represents the first series-arranged simulation model, and B represents the second series-arranged simulation model. Thus, the first column in the matrix represents the membership function values of multiple fuzzy evaluation membership functions corresponding to multiple system performance evaluation indicators of the first series-arranged simulation model under a certain altitude condition, and the second column in the matrix represents the membership function values of multiple fuzzy evaluation membership functions corresponding to multiple system performance evaluation indicators of the second series-arranged simulation model under a certain altitude condition.

[0084] According to some embodiments of the present invention, as Figure 2 shown, the optimization of the high-altitude performance recovery parameters of the optimal series-arranged simulation model in step S5 includes the following steps:

[0085] S501: Operate the optimal series-arranged simulation model, and successively change the altitude environment, the boost ratio distribution ratio of the mechanical supercharger 2 and the turbocharger 3, and the rotational speed of the aero-engine. For example, the altitude range can be 2000 m - 8000 m, the boost ratio distribution ratio can be 4:6, 4.5:5.5, 5:5, 5.5:4.5, 6:4, and the rotational speed can be 2100 r / min, 2400 r / min, and 1800 r / min, so as to obtain the mechanical supercharger compressor efficiency and turbocharger compressor efficiency data under different altitudes, different boost ratio distribution ratios, and different engine rotational speeds. Specifically, the boost ratio of the mechanical supercharger 2 is jointly controlled by the transmission ratio and the bypass valve 202, and the boost ratio of the turbocharger 3 is adjusted by the waste gas valve 301. Through the above adjustments, the boost ratio distribution of the turbocharger 3 and the mechanical supercharger 2 can be achieved. The overhead valve two-stroke aero-piston engine 1 can obtain less turbine work due to reasons such as low exhaust temperature. Generally, the waste gas valve 301 of the turbocharger 3 is opened less or not opened to ensure that the exhaust energy is sufficiently recovered, and the boost ratio distribution is mainly controlled by adjusting the boost ratio of the mechanical supercharger 2.

[0086] S502: Considering that both the mechanical supercharger compressor and the turbocharger compressor should operate in a high-efficiency range far from the surge and choke boundaries, analyze the mechanical supercharger compressor efficiency and turbocharger compressor efficiency data obtained in step S501 to obtain the most reasonable boost ratio distribution ratio in the low-altitude interval and the high-altitude interval. It can be understood that steps S501 and S502 are used to optimize the boost ratio distribution ratio of the mechanical supercharger 2 and the turbocharger 3 so that both the mechanical supercharger compressor and the turbocharger compressor operate with high efficiency.

[0087] By screening out the most reasonable supercharging ratio distribution ratios for the low-altitude range and the high-altitude range, the compressor of the mechanical supercharger and the compressor of the turbocharger can both operate in the high-efficiency range far from the surge and choke boundaries throughout the altitude range, thereby enabling the operation of the aviation piston engine to meet high safety requirements and airworthiness compliance.

[0088] According to some embodiments of the present invention, as Figure 2 shown, optimizing the high-altitude performance recovery parameters of the optimal series arrangement simulation model in step S5 further includes the following steps:

[0089] S503: Run the optimal series arrangement simulation model, and sequentially change the altitude environment, the supercharging ratio distribution ratios of the mechanical supercharger 2 and the turbocharger 3, and the rotational speed of the aviation engine. For example, the altitude range can be changed within the range of 2000m - 8000m, the supercharging ratio distribution ratios can be 4:6, 4.5:5.5, 5:5, 5.5:4.5, 6:4, and the rotational speed can be 2100r / min, 2400r / min, and 1800r / min, so as to measure the capture rate and scavenging efficiency data of the air exchange process of the aviation engine under different altitudes, different supercharging ratio distribution ratios, and different engine rotational speeds;

[0090] S504: On the premise that both the compressor of the mechanical supercharger and the compressor of the turbocharger should operate in the high-efficiency range, considering that the capture rate and scavenging efficiency of the air exchange process of the aviation engine need to be at a relatively high level, analyze the capture rate and scavenging efficiency data obtained in step S503 to obtain the most reasonable supercharging ratio distribution ratios for the low-altitude range and the high-altitude range. It can be understood that steps S503 and S504 are used to further optimize the supercharging ratio distribution ratio so that the aviation piston engine can obtain as good air exchange performance as possible. For the overhead valve two-stroke aviation piston engine 1, the main goal of supercharging ratio distribution should be the power performance recovery under various altitude conditions, and the high-altitude power recovery of the overhead valve two-stroke aviation piston engine 1 mainly comes from the recovery of air exchange performance. Therefore, optimizing the air exchange performance is one of the goals of supercharging ratio distribution.

[0091] According to some embodiments of the present invention, as Figure 2 shown, optimizing the high-altitude performance recovery parameters of the optimal series arrangement simulation model in step S5 further includes the following steps:

[0092] S505: Run the simulation model of the optimal series arrangement, and successively change the valve timing and altitude environment of the aero-engine to obtain the capture rate and scavenging efficiency data of the scavenging process of the aero-engine under different valve timings and different altitude environments. Specifically, for example, the valve timing can be In126 / 239, Ex101 / 208; In136 / 249, Ex101 / 208; In146 / 259, Ex101 / 208; In126 / 239, Ex111 / 218; In136 / 249, Ex111 / 218; In146 / 259, Ex111 / 218; In126 / 239, Ex121 / 228; In136 / 249, Ex121 / 228; In146 / 259, Ex121 / 228; where "In" represents the intake phase and "Ex" represents the exhaust phase, and the altitude range is 0 - 8000 m.

[0093] S506: Take the scavenging efficiency as the most important index, that is, the higher the scavenging efficiency, the better. Analyze the capture rate and scavenging efficiency data of the scavenging process obtained in step S505 to determine the most suitable valve timing at different altitudes. By optimizing the valve timing at different altitudes, the scavenging efficiency at different altitudes can reach the optimum, which is beneficial to the recovery of the high-altitude performance of the overhead valve two-stroke aero-piston engine 1. Compared with other two-stroke aero-piston engines, one of the characteristics of the overhead valve two-stroke aero-piston engine 1 is that its valve timing can be freely adjusted. Therefore, the optimization of the valve timing during high-altitude operation is also a key to the compound supercharging matching. The optimized value of the valve timing changes to a certain extent with the altitude, and the valve overlap angle has a significant impact on the high-altitude scavenging characteristics. Therefore, it is necessary to determine the most suitable valve timing at different altitudes. When the valve train cam profile of the overhead valve two-stroke aero-piston engine 1 is determined, the valve overlap angle can be changed by changing the reference position of the camshaft.

[0094] According to some embodiments of the present invention, as Figure 2 shown, the optimization of the high-altitude performance recovery parameters of the optimal series arrangement simulation model in step S5 further includes the following steps:

[0095] S507: Optimize the length of the exhaust manifold and the volume of the exhaust chamber of the aero-engine to change the constant pressure turbocharging mode to the pulse turbocharging mode and make the charging efficiency and capture rate of the scavenging process of the aero-engine reach a relatively high level.

[0096] Due to the intervention of the turbocharger 3, both the compound supercharging system and the scavenging process are more sensitive to the structural parameters of the exhaust system. For the application of the turbocharger 3 in the overhead valve two-stroke aviation piston engine 1, if the constant pressure turbocharging scheme is adopted, in order to maintain the stability of the pressure before the turbine, some exhaust energy will be lost, the utilization rate of the exhaust energy is low, and the increase in the short circuit under high-altitude conditions significantly reduces the temperature before the turbine, which is more disadvantageous for the relatively small turbine work corresponding to the scavenging of the overhead valve two-stroke aviation piston engine 1; however, if pulse turbocharging is adopted, that is, the volume of the exhaust system is reduced, so that the exhaust gas quickly enters the turbine to expand and do work to reduce the throttling loss. For the scavenging process of the overhead valve two-stroke aviation piston engine 1, the pulse energy in the free exhaust stage can be fully utilized, so that the comprehensive recovery and utilization rate of the exhaust energy is higher, thereby increasing part of the compressor work; on the other hand, adopting the pulse supercharging scheme, the pressure fluctuation in the exhaust manifold is large, and the control of the reflected compression wave of the pulse turbine system can be achieved by adjusting the structural parameters of the exhaust system. The short circuit in the scavenging process mainly occurs at the end of the scavenging stage. If the reflected wave can reach the exhaust port at the end of the scavenging stage, the instantaneous increase in the exhaust back pressure at this moment will effectively suppress the short circuit and increase the in-cylinder sealed amount of the fresh charge; therefore, under the condition of low high-altitude capture rate, the application of the pulse turbine scheme in the compound supercharging system is more meaningful than using it under ground conditions.

[0097] The main structural parameters of the exhaust system that affect the performance of the pulse turbine system and the arrival time of the reflected compression wave at the exhaust valve are the length of the exhaust manifold before the contraction section of the exhaust pipe and the volume of the exhaust chamber before the turbine. Inappropriate values of the structural parameters may cause the arrival time of the compression wave to advance. If it arrives at the moment when the exhaust valve is opened largely and efficient scavenging is in progress (around the bottom dead center), it will prevent the exhaust gas from being discharged and the fresh charge from entering the cylinder, resulting in a significant increase in the residual amount of exhaust gas in the cylinder.

[0098] Therefore, during the compound supercharging matching, optimizing the structural parameters of the exhaust system of the overhead valve two-stroke aviation piston engine 1 can control the reflected compression wave and improve the scavenging performance (charging efficiency and capture rate), which is beneficial to the recovery of the high-altitude performance of the overhead valve two-stroke aviation piston engine 1. In addition, adjusting the structural parameters of the exhaust system to the pulse supercharging state and taking appropriate values can achieve the simultaneous improvement of the scavenging performance of the overhead valve two-stroke aviation piston engine 1 and the performance of the compound supercharging system.

[0099] In the step of optimizing the high-altitude performance recovery parameters of the optimal series arrangement simulation model, the present invention gradually optimizes from the factors with greater influence to those with smaller influence by sequentially optimizing the supercharging ratio distribution ratio, valve timing, and structural parameters of the exhaust system, and finally forms a comprehensive optimization method for the overhead valve two-stroke aviation piston engine 1 with compound supercharging matching under high-altitude conditions, effectively overcoming the defects that the current aviation piston engines only have parameter performance analysis in the ground fixed state, the high-altitude performance recovery parameter optimization method is single, and there is a blank in the high-altitude parameter optimization under compound supercharging.

[0100] According to some embodiments of the present invention, the optimized optimal series arrangement simulation model is calculated and compared with the optimal series arrangement simulation model before optimization, and in practice, a test bench experiment is carried out on the aviation engine and the compound supercharging system before and after the optimization of the high-altitude performance recovery parameters. It can be understood that the structural parameters and operating parameters of the aviation engine and the compound supercharging system before and after the optimization of the high-altitude performance recovery parameters in practice are consistent with those of the optimal series arrangement simulation model before and after optimization, so that the data obtained from the test bench experiment in practice can be compared with the calculation data of the optimal series arrangement simulation model before and after optimization to verify the accuracy of the optimization method of the present invention.

[0101] In the description of this specification, the description of reference terms such as "one embodiment", "some embodiments", "schematic embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0102] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and purposes of the present invention, and the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A method for evaluating the matching of aero-engine composite supercharging and optimizing the high-altitude performance recovery, characterized in that It includes the following steps: S1: Establish a first series arrangement simulation model and a second series arrangement simulation model. Both the first series arrangement simulation model and the second series arrangement simulation model include an aeroengine, a compound supercharging system, and an environment module. The compound supercharging system is used to supercharge the aeroengine. The compound supercharging system includes a mechanically driven supercharger and a turbocharger arranged in series. The environment module is used to simulate environments at different altitudes; S2: Run the first series arrangement simulation model and the second series arrangement simulation model, change the altitude environment, and obtain the specific values of multiple system performance evaluation indexes of the first series arrangement simulation model and the second series arrangement simulation model at different altitudes; S3: According to the performance range of the aeroengine, establish multiple fuzzy evaluation membership functions corresponding one by one to the multiple system performance evaluation indexes, and substitute the specific values of the multiple system performance evaluation indexes of the obtained first series arrangement simulation model and second series arrangement simulation model at different altitudes into the multiple fuzzy evaluation membership functions respectively to obtain the membership function values of the first series arrangement simulation model and the second series arrangement simulation model; wherein, the multiple system performance evaluation indexes include the specific fuel consumption rate, the charging efficiency during the scavenging process, the proportion of the work consumed by the mechanically driven supercharger in the effective power, the compressor efficiency of the mechanically driven supercharger, and the compressor efficiency of the turbocharger. The multiple fuzzy evaluation membership functions corresponding one by one to the multiple system performance evaluation indexes are all trapezoidal distribution functions; S4: Establish a performance fuzzy evaluation matrix including the multiple fuzzy evaluation membership functions of the first series arrangement simulation model and the second series arrangement simulation model at different altitudes, conduct a comprehensive analysis on the importance degree of the multiple system performance evaluation indexes, assign certain weights to the multiple system performance evaluation indexes, combine the corresponding weights of the multiple system performance evaluation indexes with the performance fuzzy evaluation matrix, finally obtain multiple evaluation matrices at different altitudes, substitute the obtained membership function values into the multiple evaluation matrices respectively, and calculate to obtain the evaluation scores of the first series arrangement simulation model and the second series arrangement simulation model at different altitudes; S5: Determine the optimal series arrangement simulation model according to the evaluation scores, and optimize the high-altitude performance recovery parameters of the optimal series arrangement simulation model.

2. The method for evaluating the composite supercharging matching and optimizing the high-altitude performance recovery of an aero-engine according to claim 1, wherein The aeroengine is an overhead valve two-stroke aero piston engine.

3. The method for evaluating the matching of combined supercharging of an aeroengine and optimizing the high-altitude performance recovery according to claim 1, wherein It also includes changing the rotational speed of the aeroengine, and then cycling through steps S2, S3, and S4 to obtain the evaluation scores of the first series arrangement simulation model and the second series arrangement simulation model at different rotational speeds and different altitudes.

4. The method for evaluating the matching of compound supercharging of an aero-engine and optimizing the high-altitude performance recovery according to any one of claims 1 to 3, characterized in that, The optimization of the high-altitude performance recovery parameters of the optimal series arrangement simulation model in step S5 includes the following steps: S501: Run the optimal series arrangement simulation model, sequentially change the altitude environment, the supercharging ratio distribution ratio of the mechanically driven supercharger and the turbocharger, and the rotational speed of the aeroengine, and obtain the data of the compressor efficiency of the mechanically driven supercharger and the compressor efficiency of the turbocharger at different altitudes, different supercharging ratio distribution ratios, and different engine rotational speeds; S502: Considering that both the supercharger compressor and the turbocharger compressor should operate in the high-efficiency range far from the surge and choke boundaries, analyze the data of the supercharger compressor efficiency and the turbocharger compressor efficiency obtained in step S501 to obtain the most reasonable supercharging ratio distribution ratios in the low-altitude range and the high-altitude range.

5. The method for evaluating the matching of aero-engine compound supercharging and optimizing the high-altitude performance recovery according to claim 4, wherein The optimization of the high-altitude performance recovery parameters of the optimal series arrangement simulation model in step S5 further includes the following steps: S503: Run the optimal series arrangement simulation model, successively change the altitude environment, the supercharging ratio distribution ratios of the supercharger and the turbocharger, and the rotational speed of the aeroengine, and measure the capture rate and the scavenging efficiency data of the aeroengine scavenging process at different altitudes, different supercharging ratio distribution ratios, and different engine rotational speeds; S504: On the premise that both the supercharger compressor and the turbocharger compressor should operate in the high-efficiency range, considering that the capture rate and the scavenging efficiency of the aeroengine scavenging process need to be at a relatively high level, analyze the capture rate and the scavenging efficiency data obtained in step S503 to obtain the most reasonable supercharging ratio distribution ratios in the low-altitude range and the high-altitude range.

6. The aviation engine compound supercharging matching evaluation and high-altitude performance recovery optimization method according to claim 5, wherein The optimization of the high-altitude performance recovery parameters of the optimal series arrangement simulation model in step S5 further includes the following steps: S505: Run the optimal series arrangement simulation model, successively change the valve timing of the aeroengine and the altitude environment, and obtain the capture rate and the scavenging efficiency data of the aeroengine scavenging process under different valve timings and different altitude environments; S506: Taking the scavenging efficiency as the most important index, analyze the capture rate and the scavenging efficiency data of the scavenging process obtained in step S505 to determine the most suitable valve timing at different altitudes.

7. The method for evaluating the matching of an aero-engine's compound supercharging and optimizing the recovery of high-altitude performance according to claim 6, wherein The optimization of the high-altitude performance recovery parameters of the optimal series arrangement simulation model in step S5 further includes the following steps: S507: Optimize the length of the exhaust manifold and the volume of the exhaust chamber of the aeroengine to change the constant-pressure turbocharging mode into the pulse turbocharging mode and make both the charging efficiency and the capture rate of the aeroengine scavenging process reach a relatively high level.

8. The method for evaluating the matching of aero-engine compound supercharging and optimizing the high-altitude performance recovery according to claim 7, characterized in that, It also includes calculating and comparing the optimized optimal series arrangement simulation model with the non-optimized optimal series arrangement simulation model, and in practice, conducting a test bench experiment on the aeroengine and the compound supercharging system before and after the optimization of the high-altitude performance recovery parameters.

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