A steady-state performance calculation method for turbo hybrid electric propulsion engines

Abstract

The application provides a steady-state performance calculation method of a turbo hybrid electric propulsion engine. The turbo hybrid electric propulsion engine comprises an engine core, a free turbine and a generator, the generator generates power by using power from the engine core via the free turbine, and provides power to the motor. The steady-state performance calculation method of the turbo hybrid electric propulsion engine comprises the following steps: constructing component mathematical models of each component of the turbo hybrid electric propulsion engine, and listing power balance equations between each component of the turbo hybrid electric propulsion engine and flow balance equations between each component; calculating the loss of the generator under different working speeds and different output power conditions, obtaining the speed, power-efficiency characteristic of the generator; and solving the steady-state performance of the turbo hybrid electric propulsion engine according to the power balance equations and the flow balance equations and the speed, power-efficiency characteristic of the generator.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of engines, in particular to a steady-state performance calculation method of a turbo hybrid electric propulsion engine. BACKGROUND

[0002] The turbo hybrid electric propulsion engine generates electricity through a turbine engine to drive a high-speed, miniaturized generator, provides power for multiple electric motors distributed on a platform, and drives propulsion devices such as propellers, ducted fans, etc. to provide thrust for the flight platform. Compared with the traditional aviation power propulsion system, the turbo hybrid electric propulsion engine can decouple the engine and the propulsion device, effectively improve the aerodynamic layout of the original flight platform, and greatly improve the propulsion efficiency of the flight platform.

[0003] The development of the turbo hybrid electric propulsion engine is a complex system engineering, involving fluid mechanics, combustion science, power electronics, mechanics and many other disciplines. The development process is difficult, long and expensive. Establishing an engine mathematical model for performance design and optimization evaluation is an effective means to reduce engine test costs and improve development efficiency. It has become an extremely important technology and tool in the process of engine design, control, test and manufacturing. SUMMARY

[0004] Technical problems to be solved by the application

[0005] The prior art does not consider the working efficiency of the generator in different working states when developing the turbo hybrid electric propulsion engine, and only selects the working efficiency value of the generator in the design state as the working efficiency of the generator in different working states, thereby causing large calculation error of the steady-state performance of the engine and being difficult to be practical.

[0006] Technical means for solving the problem

[0007] The present application provides a steady-state performance calculation method of a turbo hybrid electric propulsion engine, characterized in that,

[0008] The turbo hybrid electric propulsion engine comprises an engine core, a free turbine and a generator, the generator generates electricity using power from the engine core via the free turbine, and provides power for the electric motor,

[0009] The steady-state performance calculation method of the turbo hybrid electric propulsion engine comprises the following steps:

[0010] Constructing component mathematical models of each component of the turbo hybrid electric propulsion engine, and listing power balance equations between each component of the turbo hybrid electric propulsion engine and flow balance equations between each component;

[0011] obtaining the speed-power-efficiency characteristics of the generator at different working speeds and different output powers; and

[0012] solving the steady-state performance of the turbo hybrid electric propulsion engine according to the power balance equation and the flow balance equation and the speed-power-efficiency characteristics of the generator.

[0013] In the method for calculating the steady-state performance of the turbo hybrid electric propulsion engine, preferably,

[0014] The turbo hybrid electric propulsion engine comprises an air inlet, a compressor, a combustion chamber, a high-pressure turbine, the free turbine and a nozzle, wherein the engine core is composed of the compressor, the combustion chamber and the high-pressure turbine.

[0015] In the method for calculating the steady-state performance of the turbo hybrid electric propulsion engine, preferably,

[0016] The power balance equation comprises:

[0017] P LGT ·η LGT -P Load / η Load =0; and

[0018] P HGT ·η HGT -P HPC =0,

[0019] wherein P LGT is the output power of the free turbine, η LGT is the mechanical efficiency of the connecting shaft of the free turbine and the generator, P Load is the power generated by the generator, η Load is the power generation efficiency of the generator; P HGT is the output power of the high-pressure turbine, η HGT is the mechanical efficiency of the connecting shaft of the high-pressure turbine and the compressor, i.e. the high-pressure shaft, and P HPC is the power consumed by the compressor.

[0020] In the method for calculating the steady-state performance of the turbo hybrid electric propulsion engine, preferably,

[0021] The flow balance equation comprises: the flow balance equation between the outlet of the combustion chamber and the inlet of the high-pressure turbine, the flow balance equation between the outlet of the high-pressure turbine and the inlet of the free turbine, and the flow balance equation between the outlet of the free turbine and the inlet of the nozzle.

[0022] In the method, preferably,

[0023] The step of obtaining the speed-power-efficiency characteristic of the generator comprises:

[0024] The step of obtaining the speed-power-efficiency characteristic of the generator comprises:

[0025] The step of obtaining the speed-power-efficiency characteristic of the generator comprises:

[0026] In the method, preferably,

[0027] The generator calculation model comprises a copper loss calculation model, a rotor wind abrasion loss calculation model, a silicon steel sheet core loss calculation model, and a permanent magnet and sheath eddy current loss calculation model.

[0028] In the method, preferably,

[0029] The obtained speed-power-efficiency characteristic of the generator comprises a speed-power-efficiency characteristic when the load is not zero and a speed-efficiency characteristic when the load is zero.

[0030] Effects of the Invention

[0031] According to the above scheme of the present application, a method for calculating the steady-state performance of a turbo hybrid electric propulsion engine considering the characteristics of a generator is provided, which can realize high-precision simulation of the steady-state performance of the turbo hybrid electric propulsion engine under multiple working conditions. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 is a component structure diagram of the turbo hybrid electric propulsion engine.

[0033] Figure 2 is a main step diagram of the method for calculating the steady-state performance of the turbo hybrid electric propulsion engine.

[0034] Figure 3 is a speed-power-efficiency characteristic curve diagram of the generator.

[0035] Figure 4 is a specific step diagram of obtaining the speed-power-efficiency characteristic.

[0036] Figure 5 is a comparison diagram of the model simulation data and the real test data obtained by the method for calculating the steady-state performance of the turbo hybrid electric propulsion engine. DETAILED DESCRIPTION

[0037] Embodiments of the present application will be described below with reference to the accompanying drawings.

[0038] The steady state performance calculation method of the turbo hybrid electric propulsion engine according to one embodiment of the present application is applied to the development process of the turbo hybrid electric propulsion engine 1.

[0039] As shown in Figure 1 , the turbo hybrid electric propulsion engine 1 comprises an air inlet 11, a compressor 12, a combustion chamber 13, a high pressure turbine 14, a free turbine 15, a generator 16, a tail nozzle 17, and an electric motor connected to the generator 16 to provide power for the flight platform. Among them, the compressor 12, the combustion chamber 13, and the high pressure turbine 14 constitute the engine core.

[0040] When the turbo hybrid electric propulsion engine 1 is working, the atmosphere enters the compressor 12 through the air inlet 11 and is compressed in the compressor 12, and then enters the combustion chamber 13. The fuel entering the combustion chamber 13 is mixed with the compressed air and burns, thereby driving the high pressure turbine 14 to rotate. The high pressure turbine 14 is connected to the compressor 12 through the connecting shaft, i.e. the high pressure shaft 18, on the one hand, and is connected to the free turbine 15, on the other hand, to drive the free turbine 15 to rotate. The exhaust gas and the like generated after the combustion enters the atmosphere through the tail nozzle.

[0041] In the turbo hybrid electric propulsion engine 1 of the present embodiment, the free turbine 15 is connected to the generator 16 to provide power for the generator 16. The flight platform using the turbo hybrid electric propulsion engine 1 is provided with a power-providing electric motor, which is supplied with power by the generator 16.

[0042] Through the above structure, the turbo engine and the electric motor as a propulsion device can be decoupled, the position of the electric motor can be freely designed according to the aerodynamic layout of the flight platform, and the propulsion efficiency of the flight platform can be greatly improved.

[0043] When designing the steady state performance of the turbo hybrid electric propulsion engine 1, as shown in Figure 2 , the steady state performance calculation method of the turbo hybrid electric propulsion engine of the present application comprises the following steps S1-S3:

[0044] Step S1: constructing a component mathematical model of each component of the turbo hybrid electric propulsion engine, and listing the power balance equations between each component of the turbo hybrid electric propulsion engine 1 and the flow balance equations between each component.

[0045] Specifically, based on C++, component mathematical models of the inlet passage 11, the compressor 12, the combustion chamber 13, the high-pressure turbine 14, the free turbine 15, the tail nozzle 17, and the generator 16 are built according to a power balance equation of the free turbine 15 and the generator 16 and a power balance equation of the high-pressure turbine 14 and the compressor 12. The mathematical models of the components are 0-dimensional models built from physical formulas and used for the whole-machine performance calculation.

[0046] The power balance equation of the free turbine 15 and the generator 16 can be expressed as:

[0047] P LGT ·η LGT -P Load / η Load =0;

[0048] where P LGT is the output power of the free turbine 15, η LGT is the mechanical efficiency of the connecting shaft of the free turbine 15 and the generator 16, P Load is the power generation power of the generator 16, and η Load is the power generation efficiency of the generator 16.

[0049] The power balance equation of the high-pressure turbine 14 and the compressor 12 can be expressed as:

[0050] P HGT ·η HGT -P HPC =0;

[0051] where P HGT is the output power of the high-pressure turbine 14, η HGT is the mechanical efficiency of the connecting shaft of the high-pressure turbine 14 and the compressor 12, i.e., the high-pressure shaft 18, and P HPC is the consumed power of the compressor 12.

[0052] The above-mentioned flow balance equations include:

[0053] A flow balance equation between the outlet of the combustion chamber 13 and the inlet of the high-pressure turbine 14: W a31 +W f =W g4 ;

[0054] A flow balance equation between the outlet of the high-pressure turbine 14 and the inlet of the free turbine 15: W g44 =W g48 ; and

[0055] A flow balance equation between the outlet of the free turbine 15 and the inlet of the tail nozzle 17: W g6 =W g8 .

[0056] Step S2: Calculate the loss of the generator 16 under different operating speeds and different output power conditions to obtain the speed, power-efficiency characteristics of the generator 16. The speed, power-efficiency characteristic curve of the generator 16 is as follows: Figure 3 As shown. Figure 3 In the figure, the percentage of the broken lines of different colors represents the percentage of the current speed to the design speed (usually the maximum speed).

[0057] Step S2 specifically includes:

[0058] S21: Obtaining structural parameters of the generator 16 and establishing a generator calculation model; and

[0059] S22: Calculating the speed and power-efficiency characteristics of the generator 16 according to the generator calculation model.

[0060] Moreover, although Figure 3 Only the speed and power-efficiency characteristic curves of the generator 16 under load are shown, but the speed and power-efficiency characteristics of the generator 16 obtained in step S2 also include speed-efficiency characteristics when the engine load is zero (no-load).

[0061] It should be noted that the generator calculation model is a three-dimensional simulation model created using commercial motor simulation software. The performance curves of the generator at different speeds and operating conditions are calculated based on the actual design dimensions of the motor. During the actual calculation, the mathematical model of the engine 16 components utilizes the motor characteristic curves pre-calculated by the generator calculation model. An interpolation program is used to obtain the generator operating state, which is then incorporated into the overall machine balance equations (flow balance equation and power balance equation) for solution.

[0062] In other words, if Figure 4 As shown, in step S2, after obtaining the main structural parameters of the generator and establishing the generator calculation model, depending on whether the engine is loaded, the speed-efficiency characteristic curve can be obtained when the engine is idling, and the speed and power-efficiency characteristic curves can be obtained when the engine is loaded.

[0063] Specifically, in step S2, Figure 4 As shown, the generator calculation model includes: copper loss calculation model, rotor wind friction loss calculation model, silicon steel core loss calculation model, and permanent magnet and sheath eddy current loss calculation model.

[0064] like Figure 4As shown, in calculating the speed-efficiency characteristic curve of the generator 16 at no load or the speed, power-efficiency characteristic of the generator 16 at load, first, the main structural parameters of the generator 16 are obtained to establish a generator calculation model (copper loss calculation model, rotor wind abrasion loss calculation model, silicon steel core loss calculation model, and permanent magnet and sheath eddy current loss calculation model), and then the speed-efficiency characteristic curve at no load and the speed, power-efficiency characteristic at load are obtained according to whether the load is carried.

[0065] Step S3: solving the steady-state performance of the turbine hybrid electric propulsion engine according to the power balance equation and the flow balance equation and the speed, power-efficiency characteristic of the generator.

[0066] In a specific embodiment, given the input variables H, Ma, nl, T4 (altitude, Mach number, free turbine working speed, turbine front temperature), the Newton-Raphson iterative algorithm is used to input the initial guess value to solve the power balance equation and the flow balance equation of the turbine hybrid electric propulsion engine 1.

[0067] Figure 5 The model simulation data obtained by the steady-state performance calculation method of the turbine hybrid electric propulsion engine of the present application is compared with the real test data. Among them, the black line represents the real test data, the blue line represents the engine steady-state performance obtained by selecting only the engine design state working efficiency value as the working efficiency of the generator, and the red line represents the engine steady-state performance obtained by the steady-state performance calculation method of the turbine hybrid electric propulsion engine of the present application. Compared with the simulation method of selecting only the engine design state working efficiency value as the working efficiency of the generator at different working states, the engine steady-state performance error decreases from an average of 3.33% to 0.76% without changing other modeling steps of the model, with a decrease of 77%, and the engine low state performance accuracy is obviously improved.

[0068] The above describes specific embodiments of the present application, but it can be understood that the present application is not limited to these embodiments, and the features of the above embodiments can be freely combined and changed within the scope claimed by the claims, and the obtained solutions still fall within the protection scope of the present application.

[0069] For example, in the above embodiment, the steps S1, S2 and S3 are described in sequence, but this does not mean that the embodiment of the present application limits the sequence of each step. Those skilled in the art can understand that in the steady-state performance calculation method of the turbo hybrid electric propulsion engine of the present application, the sequence of step S1 and step S2 can be exchanged. That is, step S2 "calculating the loss of the generator 16 under different working speeds and different output power conditions, and obtaining the speed, power-efficiency characteristics of the generator 16" can be performed first, and then step S1 "constructing the component mathematical model of each component according to the power balance equation between each component of the turbo hybrid electric propulsion engine 1 and the flow balance equation between each component" can be performed, which does not affect the technical effects of the present application.

[0070] Symbol explanation

[0071] 1 turbo hybrid electric propulsion engine

[0072] 11 includes an inlet channel

[0073] 12 compressor

[0074] 13 combustion chamber

[0075] 14 high-pressure turbine

[0076] 15 free turbine

[0077] 16 generator

[0078] 17 nozzle

Claims

1.A method for calculating steady-state performance of a turbo hybrid electric propulsion engine, characterized in that, the turbo hybrid electric propulsion engine comprises an engine core, a free turbine and a generator, the generator generates electricity by using power from the engine core via the free turbine and provides electricity to an electric machine, the method for calculating steady-state performance of the turbo hybrid electric propulsion engine comprises the following steps: constructing component mathematical models of components of the turbo hybrid electric propulsion engine and listing power balance equations between components of the turbo hybrid electric propulsion engine and flow balance equations between components; calculating losses of the generator under different working speeds and different output powers to obtain speed-power-efficiency characteristics of the generator; and solving steady-state performance of the turbo hybrid electric propulsion engine according to the power balance equations, the flow balance equations and the speed-power-efficiency characteristics of the generator, the turbo hybrid electric propulsion engine comprises an inlet channel, a compressor, a combustor, a high-pressure turbine, the free turbine and a nozzle, wherein the engine core is composed of the compressor, the combustor and the high-pressure turbine, the power balance equations comprise: the flow balance equation between the combustor and the high-pressure turbine, the flow balance equation between the high-pressure turbine and the free turbine and the flow balance equation between the free turbine and the nozzle. 2.The method for calculating steady-state performance of the turbo hybrid electric propulsion engine according to claim 1, characterized in that, the flow balance equations comprise: the flow balance equation between the combustor and the high-pressure turbine, the flow balance equation between the high-pressure turbine and the free turbine and the flow balance equation between the free turbine and the nozzle. 3.The method for calculating steady-state performance of the turbo hybrid electric propulsion engine according to claim 1 or 2, characterized in that, the step of calculating losses of the generator under different working speeds and different output powers to obtain speed-power-efficiency characteristics of the generator comprises: obtaining structural parameters of the generator to establish a generator calculation model; and calculating the speed-power-efficiency characteristics of the generator according to the generator calculation model. 4.The method for calculating steady-state performance of the turbo hybrid electric propulsion engine according to claim 3, characterized in that, the generator calculation model comprises: a copper loss calculation model, a rotor wind abrasion loss calculation model, a silicon steel core loss calculation model and a permanent magnet and sheath eddy current loss calculation model. 5.The method for calculating steady-state performance of the turbo hybrid electric propulsion engine according to claim 4, characterized in that, the obtained speed-power-efficiency characteristics of the generator comprise speed-power-efficiency characteristics when the load is not zero and speed-efficiency characteristics when the load is zero. ​ ​ ​ P LGT ·η LGT -P Load / η Load =0; and P HGT ·η HGT -P HPC =0, wherein P LGT is the output power of the free turbine, η LGT is the mechanical efficiency of the connecting shaft of the free turbine with the generator, P Load is the generated power of the generator, η Load is the generated efficiency of the generator; P HGT is the output power of the high-pressure turbine, η HGT is the mechanical efficiency of the connecting shaft of the high-pressure turbine with the compressor, i.e. the high-pressure shaft, P HPC is the consumed power of the compressor. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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