Variable cycle aeroengine mode switching transient reverse flow simulation method and simulation system

Abstract

The present application relates to a variable cycle aero-engine mode switching transient reverse flow simulation method and simulation system, belonging to the simulation technical field of variable cycle engine mode switching, solves the problem that the traditional component method needs to preset the flow direction and cannot perform reverse flow calculation in the prior art, comprising: step S1, a component method is used to establish a main flow path model of a variable cycle aero-engine; step S2, a network method is used to establish a mode switching local flow path model of the variable cycle aero-engine; step S3, a mode switching transient reverse flow simulation model is constructed, the main flow path model established by the component method is coupled with the mode switching local flow path model established by the network method to obtain the mode switching transient reverse flow simulation model; step S4, the mode switching transient reverse flow simulation model is used for simulation, an aero-engine control law and a mode selection valve regulation law are set therein, and simulation results are obtained and output.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of simulation of mode switching of variable cycle engines, and particularly relates to a method and system for simulating transient reverse flow during mode switching of variable cycle aero-engines. BACKGROUND

[0002] Variable cycle aero-engines can change thermal cycle parameters such as pressure ratio, bypass ratio, turbine inlet temperature, air flow, etc. by adjusting the geometry of components according to different task requirements of the aircraft, so that the engine has good performance in each state, and is an important development direction of future aviation power. Variable cycle engines generally have multiple ducts, and mode selection valves are needed to change the flow state of each duct to realize mode switching of the engine. However, during mode switching of the variable cycle engine, the flow direction of the gas between different ducts may change due to the pressure change caused by mode switching, and this transient reverse flow phenomenon will cause calculation divergence. The current methods for handling reverse flow during mode switching of variable cycle engines mainly include local cycle method and passive convergence method, etc. Limited by the need for sequential calculation in component-based modeling, the above methods cannot simulate the reverse flow phenomenon during the transient process of mode switching.

[0003] Therefore, there is a need in the technical field for a method for accurately simulating the mode switching process of variable cycle aero-engines with reverse flow phenomenon. SUMMARY

[0004] In view of the problem that the existing simulation methods cannot simulate the transient reverse flow phenomenon during mode switching of variable cycle aero-engines, the present application provides a method and system for simulating transient reverse flow during mode switching of variable cycle aero-engines, wherein the local flow path of mode switching is modeled by a network method, and the main flow path involving compression components, combustion components and turbine components is modeled by a component method. The network method is a zero-dimensional simulation model based on the flow characteristics of elements, which decomposes the flow path and chamber of the system into a network composed of corresponding elements and nodes, takes the gas parameters of each node as initial trial parameters, constructs a solution matrix of trial parameter correction values by calculating the balance equation at each node, and then iteratively calculates the converged solution. The network method does not need to calculate each element in the flow direction one by one, and after the boundary information of the fluid network is determined, iterative solution can be performed. Therefore, the network method can better accommodate the transient reverse flow process.

[0005] Further, the coupling of the main flow path and the network of the mode switching local flow path is realized by bleed air boundary nodes and converging boundary nodes with equation closure mechanism.

[0006] Further, the mode switching local flow path network is composed of bleed air boundary nodes, merging boundary nodes, internal nodes, and throttling elements connecting the bleed air boundary nodes, the merging boundary nodes, and the internal nodes, wherein the throttling areas of the throttling elements are given according to the geometric characteristics of the mode switching valve flow path.

[0007] According to one embodiment of the present application, a mode switching transient reverse flow simulation method for a variable cycle aero-engine is provided, comprising the following steps:

[0008] Step S1, a main flow path model of the variable cycle aero-engine is established by using a component method, wherein the main flow path model includes main functional components of the aero-engine, such as a compression system, a combustion system, a turbine system, a duct system, a casing, and a mixing chamber;

[0009] Step S2, a mode switching local flow path model of the variable cycle aero-engine is established by using a network method, wherein the mode switching local flow path model includes a mode selection valve, internal nodes of the mode selection valve, bleed air boundary nodes, merging boundary nodes, and connecting flow channels; wherein the bleed air boundary nodes include a mode selection valve inside flow path bleed air boundary node and a mode selection valve outside flow path bleed air boundary node; wherein the merging boundary nodes include a mode selection valve inside flow path merging boundary node and a mode selection valve outside flow path merging boundary node; and wherein the connecting flow channels include a flow channel connecting the mode selection valve inside flow path bleed air boundary node and the internal nodes of the mode selection valve, a flow channel connecting the mode selection valve outside flow path bleed air boundary node and the internal nodes of the mode selection valve, a flow channel connecting the mode selection valve outside flow path bleed air boundary node and the mode selection valve outside flow path merging boundary node, and a flow channel connecting the internal nodes of the mode selection valve and the mode selection valve inside flow path merging boundary node; wherein the mode selection valve is switched between a closed state and an open state, so as to adjust the area of the flow channel connecting the mode selection valve outside flow path bleed air boundary node and the internal nodes of the mode selection valve, and to adjust the area of the flow channel connecting the mode selection valve outside flow path bleed air boundary node and the mode selection valve outside flow path merging boundary node;

[0010] Step S3, a mode switching transient reverse flow simulation model is constructed, wherein the main flow path model established by the component method is coupled with the mode switching local flow path model established by the network method through the bleed air boundary nodes and the merging boundary nodes having an equation closure mechanism to obtain the mode switching transient reverse flow simulation model;

[0011] Step S4, simulation is performed by using the mode switching transient reverse flow simulation model, wherein an aero-engine control law and a mode selection valve adjustment law are set, a simulation result is obtained and output by the mode switching transient reverse flow simulation model, and a simulation chart is drawn according to the simulation result, which is used for analysis and optimization design of mode switching of the variable cycle aero-engine.

[0012] Optionally, step S3 further comprises:

[0013] The component method is coupled with the network method to establish the model switching valve local flow path model, specifically, by coupling the bleed air boundary node of the mode selection valve inside flow path, the bleed air boundary node of the mode selection valve outside flow path, the mode selection valve internal node, the mode selection valve inside flow path confluence boundary node, and the mode selection valve outside flow path confluence boundary node with the main flow path model to realize;

[0014] The corresponding mode selection valve inside flow path bleed air boundary node and the mode selection valve inside flow path confluence boundary node, the mode selection valve outside flow path bleed air boundary node and the mode selection valve outside flow path confluence boundary node are respectively composed of bleed air / confluence modules.

[0015] Optionally, in the main flow path model established in step S1: the bypass system comprises a first outer bypass, a second outer bypass and a third outer bypass arranged from inside to outside.

[0016] Optionally, the mode switching local flow path model established in step S2 further comprises: a core engine bleed air boundary node and a core engine confluence boundary node; and a medium-pressure turbine rear casing flow channel connecting the core engine bleed air boundary node and the core engine confluence boundary node, and an inner bypass combustion chamber shutter flow channel connecting the core engine confluence boundary node and the mode selection valve internal node.

[0017] Optionally, in the mode switching local flow path model established in step S2:

[0018] The mode selection valve inside flow path bleed air boundary node is a first outer bypass bleed air boundary node;

[0019] The mode selection valve outside flow path bleed air boundary node is a second outer bypass bleed air boundary node;

[0020] The mode selection valve inside flow path confluence boundary node is a first outer bypass confluence boundary node;

[0021] The mode selection valve outside flow path confluence boundary node is a second outer bypass confluence boundary node;

[0022] The flow channel connecting the mode selection valve inside flow path bleed air boundary node and the mode selection valve internal node is a first outer bypass to mode selection valve flow channel connecting the first outer bypass bleed air boundary node and the mode selection valve internal node;

[0023] The flow channel connecting the mode selection valve outside flow path bleed air boundary node and the mode selection valve internal node is a second outer bypass to mode selection valve flow channel connecting the second outer bypass bleed air boundary node and the mode selection valve internal node;

[0024] The flow channel connecting the mode selection valve internal node and the mode selection valve inner side flow path confluence boundary node is a mode selection valve to outer annulus combustion chamber flow channel connecting the mode selection valve internal node and the first outer annulus confluence boundary node.

[0025] The flow channel connecting the mode selection valve internal node and the mode selection valve inner side flow path confluence boundary node is a mode selection valve to outer annulus combustion chamber flow channel connecting the mode selection valve internal node and the first outer annulus confluence boundary node.

[0026] Optionally, step S3 further comprises:

[0027] The component method established main flow path model and the network method established mode switching valve local flow path model are coupled, specifically, by coupling the core engine bleed boundary node, the first outer annulus bleed boundary node, the second outer annulus bleed boundary node, and the core engine confluence boundary node, the first outer annulus confluence boundary node and the second outer annulus confluence boundary node with the equation closed mechanism core machine with the main flow path model to realize;

[0028] The core engine bleed boundary node and the core engine confluence boundary node, the first outer annulus bleed boundary node and the first outer annulus confluence boundary node, and the second outer annulus bleed boundary node and the second outer annulus confluence boundary node are respectively composed of three bleed / confluence modules.

[0029] Optionally, step S3 of constructing the mode switching transient reverse flow simulation model further comprises:

[0030] For any bleed boundary node in the core engine bleed boundary node, the first outer annulus bleed boundary node and the second outer annulus bleed boundary node, the total temperature T b1 * , total pressure p b1 * , flow W b1 , oil-gas ratio f b1 , humidity content D b1 of the upstream main flow component connected with the bleed boundary node are set, and the total temperature T b2 * , total pressure p b2 * , flow W b2 , oil-gas ratio f b2 , humidity content D b2 of the bleed boundary node are obtained.

[0031] The flow W b2 of any bleed boundary node and the flow W b of the adjacent M j branches satisfy the following relationship:

[0032]

[0033] wherein ε b represents the bleed air boundary node energy balance equation, W b2 represents the flow rate of the bleed air boundary node, b2 represents the number of the bleed air boundary node and b2 = 1, 2, 3, W j represents the flow rate of the jth branch adjacent to the bleed air boundary node, j represents the number of the branch adjacent to the bleed air boundary node and j = 1, 2, M b , M b represents the total number of the branches adjacent to the bleed air boundary node;

[0034] For any one of the core flow convergence boundary node, the first outer flow convergence boundary node and the second outer flow convergence boundary node, the total pressure, the total enthalpy, the flow rate, the oil-gas ratio and the moisture content of the any one of the flow convergence boundary nodes are set as the trial value, and the total enthalpy, the flow rate, the oil-gas ratio and the moisture content of the N M branches adjacent to the flow convergence boundary node satisfy the following relationship:

[0035]

[0036] wherein ε M.1 represents the flow convergence boundary node energy balance equation, ε M.2 represents the flow convergence boundary node flow balance equation, ε M.3 represents the flow convergence boundary node oil-gas ratio balance equation, ε M.4 represents the flow convergence boundary node moisture content balance equation, represents the total enthalpy of the flow convergence boundary node, W M represents the flow rate of the flow convergence boundary node, f M represents the oil-gas ratio of the flow convergence boundary node, D M represents the moisture content of the flow convergence boundary node, M represents the number of the flow convergence boundary node and M = 1, 2, 3, represents the total enthalpy of the kth branch adjacent to the flow convergence boundary node, W k represents the flow rate of the kth branch adjacent to the flow convergence boundary node, f k represents the oil-gas ratio of the kth branch adjacent to the flow convergence boundary node, D k represents the moisture content of the kth branch adjacent to the flow convergence boundary node, k represents the number of the branch adjacent to the flow convergence boundary node and k = 1, 2, N M , N M represents the total number of the branches adjacent to the flow convergence boundary node.

[0037] According to another embodiment of the present application, a variable cycle aero-engine mode switching transient reverse flow simulation system is provided, which comprises a mode switching transient reverse flow simulation model established by coupling a main flow path model and a mode switching local flow path model, wherein

[0038] The main flow path model is established by a component method and includes main functional components of the aero-engine, i.e., a compression system, a combustion system, a turbine system, a duct system, a casing and a mixing chamber;

[0039] The mode switching local flow path model is established by a network method and includes a mode selection valve, a mode selection valve internal node, a bleed air boundary node, a merging boundary node and a connecting flow channel; the bleed air boundary node includes a mode selection valve internal flow path bleed air boundary node and a mode selection valve external flow path bleed air boundary node; the merging boundary node includes a mode selection valve internal flow path merging boundary node and a mode selection valve external flow path merging boundary node; and the connecting flow channel includes a flow channel connecting the mode selection valve internal flow path bleed air boundary node and the mode selection valve internal node, a flow channel connecting the mode selection valve external flow path bleed air boundary node and the mode selection valve internal node, a flow channel connecting the mode selection valve external flow path bleed air boundary node and the mode selection valve external flow path merging boundary node, and a flow channel connecting the mode selection valve internal node and the mode selection valve internal flow path merging boundary node; the mode selection valve is switched between a closed state and an open state, so as to adjust the area of the flow channel connecting the mode selection valve external flow path bleed air boundary node and the mode selection valve internal node and the area of the flow channel connecting the mode selection valve external flow path bleed air boundary node and the mode selection valve external flow path merging boundary node;

[0040] The mode switching transient reverse flow simulation model is obtained by coupling the main flow path model established by the component method and the mode switching local flow path model established by the network method through the bleed air boundary node and the merging boundary node with an equation closure mechanism.

[0041] Compared with the prior art, the mode switching transient reverse flow simulation method and simulation system of the variable cycle aero-engine provided by the application have at least the following beneficial effects: the network method is used to process the reverse flow problem of the local flow path of the mode switching valve, thus overcoming the defect that the traditional component method needs to preset the flow direction and cannot perform reverse flow calculation; meanwhile, the component method is used to process the main flow path and describe the complex aerodynamic and thermal process in the compression component and the turbine component. The coupling of the component method and the network method realizes the simulation of the transient reverse flow of the mode selection valve of the variable cycle aero-engine, and high-precision resolution can be realized for the reverse flow phenomenon. BRIEF DESCRIPTION OF DRAWINGS

[0042] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the drawings needed in the embodiments will be briefly introduced as follows. The features and advantages of the application can be more clearly understood by referring to the drawings. The drawings are schematic and should not be considered as any limitation on the application. Other drawings can be obtained by those skilled in the art without any creative effort.

[0043] Figure 1 Flow chart of the variable cycle aero-engine mode switching transient reverse flow simulation method according to an embodiment of the present application.

[0044] Figure 2 Main flow path schematic diagram of the variable cycle aero-engine mode switching transient reverse flow simulation method according to an embodiment of the present application.

[0045] Figure 3 Coupling model of the main flow path model and the mode switching local flow path model of the variable cycle aero-engine mode switching transient reverse flow simulation system according to an embodiment of the present application.

[0046] Figure 4 Simulation result of the reverse flow phenomenon in the acceleration process of the inner bypass combustion chamber in the "double variable" cycle engine turbofan mode according to an embodiment of the variable cycle aero-engine mode switching transient reverse flow simulation method of the present application.

[0047] Figure 5 Mode selection valve angle control law in the mode switching process of the "double variable" cycle engine according to another embodiment of the variable cycle aero-engine mode switching transient reverse flow simulation method of the present application.

[0048] Figure 6 Simulation result of the reverse flow phenomenon in the second outer bypass to mode selection valve flow path (turbojet) in the mode switching process of the "double variable" cycle engine according to another embodiment of the variable cycle aero-engine mode switching transient reverse flow simulation method of the present application.

[0049] Explanation of reference signs:

[0050] 101, core fan

[0051] 102, high pressure compressor

[0052] 103, main combustion chamber

[0053] 104, high pressure turbine

[0054] 105, intermediate pressure turbine

[0055] 106, intermediate pressure turbine rear casing

[0056] 107, inner bypass combustion chamber shutter

[0057] 108, mode selection valve (closed state)

[0058] 109, mode selection valve (open state)

[0059] 110. third outer flow;

[0060] 111. second outer flow;

[0061] 112. first outer flow;

[0062] 113. core engine flow passage;

[0063] 114. inner flow combustion chamber;

[0064] 115. outer flow combustion chamber;

[0065] 116. fore-mixing chamber;

[0066] 117. mode selection valve adjustment mechanism;

[0067] 118. mid-pressure turbine aft casing flow passage;

[0068] 119. inner flow combustion chamber louver flow passage;

[0069] 120. first outer flow to mode selection valve flow passage;

[0070] 121. mode selection valve to outer flow combustion chamber flow passage;

[0071] 122. second outer flow to mode selection valve flow passage (turbojet);

[0072] 123. second outer flow to mode selection valve flow passage (turbofan);

[0073] 124. core engine bleed air boundary node;

[0074] 125. core engine confluence boundary node;

[0075] 126. first outer flow bleed air boundary node;

[0076] 127. mode selection valve internal node;

[0077] 128. first outer flow confluence boundary node;

[0078] 129. second outer flow bleed air boundary node;

[0079] 130. second outer flow confluence boundary node;

[0080] 131. main flow flowpath;

[0081] 132. mode switching local flowpath. DETAILED DESCRIPTION

[0082] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0083] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein. Therefore, the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0084] The following describes in detail, with reference to the accompanying drawings, the instantaneous reverse flow simulation method and simulation system for switching mode of a variable cycle aero-engine according to an embodiment of the present invention.

[0085] It should be noted that the instantaneous reverse flow simulation method and system for mode switching of variable cycle aero-engines disclosed in this invention can be used not only for simulating the instantaneous reverse flow process during mode switching of the engine type described in the specific embodiments, but also for simulating other engine types with similar instantaneous reverse flow characteristics. Furthermore, this invention can also be implemented in other ways different from those described herein; therefore, the scope of protection of this invention is not limited to the specific embodiments disclosed below.

[0086] like Figure 2 As shown, in a simulation method for instantaneous reverse flow during mode switching of a variable-cycle aero-engine according to one embodiment of the present invention, the main flow paths involved in mode switching in the variable-cycle aero-engine may include: core fan 101, high-pressure compressor 102, main combustion chamber 103, high-pressure turbine 104, intermediate-pressure turbine 105, intermediate-pressure turbine rear casing 106, inner combustion chamber louvers 107, mode selection valve (which may be in a closed state 108 or an open state 109), mode selection valve adjustment mechanism 117, third outer bypass 110, second outer bypass 111, first outer bypass 112, core engine flow channel 113, inner combustion chamber 114, and outer bypass... Combustion chamber 115, pre-mixing chamber 116, intermediate-pressure turbine rear casing flow channel 118, inner combustion chamber louver flow channel 119, first bypass to mode selection valve flow channel 120, mode selection valve to bypass combustion chamber flow channel 121, second bypass to mode selection valve flow channel (turbojet) 122, second bypass to mode selection valve flow channel (turbofan) 123, core engine bleed air boundary node 124, core engine confluence boundary node 125, first bypass bleed air boundary node 126, mode selection valve internal node 127, first bypass confluence boundary node 128, second bypass bleed air boundary node 129, second bypass confluence boundary node 130.

[0087] See Figures 1 to 3The method for simulating transient reverse flow during mode switching of a variable cycle aero-engine according to one embodiment of the present application comprises the following steps.

[0088] In step S1, a main flow path 131 model is established by using a component method, which includes main functional components of the aero-engine, such as a compression system, a combustion system, a turbine system, a duct system, a casing, and a mixing chamber. The component method performance model is a zero-dimensional simulation model based on the characteristics of the engine components. The model divides the aero-engine into several functional components according to the aerodynamic and thermodynamic processes of the engine. The working parameters or performance parameters of each component of the aero-engine are used as initial trial parameters. Each component is sequentially calculated in the flow direction, and the solving matrix of the trial parameter correction amount is established according to the common working conditions that must be met between components and the selected engine control law, to iteratively correct the initial trial parameters.

[0089] Optionally, the duct system specifically can include a first outer duct 112, a second outer duct 111, and a third outer duct 110 arranged from inside to outside. The compression system specifically can include a core fan 101 and a high-pressure compressor 102. The combustion system specifically can include a main combustion chamber 103, an inner duct combustion chamber 114, and an outer duct combustion chamber 115. The turbine system specifically can include a high-pressure turbine 104 and a medium-pressure turbine 105. The mixing chamber specifically can include a front mixing chamber 116. The casing specifically can include a medium-pressure turbine rear casing 106, a core engine flow passage 113, and a medium-pressure turbine rear casing flow passage 118.

[0090] In step S2, a mode switching local flow path 132 model is established by using a network method. The mode switching local flow path model includes a mode selection valve, a mode selection valve internal node 127, a bleed air boundary node, a confluence boundary node, and a connecting flow passage. The bleed air boundary node includes a mode selection valve inside flow path bleed air boundary node and a mode selection valve outside flow path bleed air boundary node. The confluence boundary node includes a mode selection valve inside flow path confluence boundary node and a mode selection valve outside flow path confluence boundary node. The connecting flow passage includes a flow passage connecting the mode selection valve inside flow path bleed air boundary node and the mode selection valve internal node 127, a flow passage connecting the mode selection valve outside flow path bleed air boundary node and the mode selection valve internal node 127, a flow passage connecting the mode selection valve outside flow path bleed air boundary node and the mode selection valve outside flow path confluence boundary node, and a flow passage connecting the mode selection valve internal node and the mode selection valve inside flow path confluence boundary node. The mode selection valve is switched between a closed state and an open state, so as to adjust the area of the flow passage connecting the mode selection valve outside flow path bleed air boundary node and the mode selection valve internal node 127, and to adjust the area of the flow passage connecting the mode selection valve outside flow path bleed air boundary node and the mode selection valve outside flow path confluence boundary node.

[0091] As Figure 3 shown, in the embodiment where the bypass system comprises first, second and third outer bypass ducts 112, 111 and 110 arranged from inner to outer, the mode selection valve inner side flowpath bleed boundary node is the first outer bypass bleed boundary node 126; the mode selection valve outer side flowpath bleed boundary node is the second outer bypass bleed boundary node 129; the mode selection valve inner side flowpath merge boundary node is the first outer bypass merge boundary node 128; and the mode selection valve outer side flowpath merge boundary node is the second outer bypass merge boundary node 130. In this embodiment, the mode switching local flowpath 132 specifically comprises the first outer bypass bleed boundary node 126, the second outer bypass bleed boundary node 129, the mode selection valve internal node 127, the first outer bypass merge boundary node 128 and the second outer bypass merge boundary node 130; and the first outer bypass to mode selection valve flowpath 120 connecting the first outer bypass bleed boundary node 126 and the mode selection valve internal node 127, the second outer bypass to mode selection valve flowpath (turbojet) 122 connecting the second outer bypass bleed boundary node 129 and the mode selection valve internal node 127, the second outer bypass to mode selection valve flowpath (turbofan) 123 connecting the second outer bypass bleed boundary node 129 and the second outer bypass merge boundary node 130, and the mode selection valve to outer bypass combustor flowpath 121 connecting the mode selection valve internal node 127 and the first outer bypass merge boundary node 128. In addition, the embodiment can also comprise the core engine bleed boundary node 124 and the core engine merge boundary node 125, and the intermediate pressure turbine aft casing flowpath 118 connecting the core engine bleed boundary node 124 and the core engine merge boundary node 125, and the inner bypass combustor shutter flowpath 119 connecting the core engine merge boundary node 125 and the mode selection valve internal node 127. The above nodes and flowpaths collectively form the network model of the mode switching local flowpath 132.

[0092] Step S3, a mode switching transient reverse flow simulation model is constructed, the main flow path 131 model established by the component method is coupled with the mode switching local flow path 132 model established by the network method through the bleed air boundary node and the confluence boundary node with equation closure mechanism to obtain the mode switching transient reverse flow simulation model. Specifically, the coupling can be realized by coupling the core engine bleed air boundary node 124, the first outer bypass bleed air boundary node 126, the second outer bypass bleed air boundary node 129, and the core engine confluence boundary node 125, the first outer bypass confluence boundary node 128 and the second outer bypass confluence boundary node 130 with the main flow path model. Among them, the core engine bleed air boundary node 124 and the core engine confluence boundary node 125, the first outer bypass bleed air boundary node 126 and the first outer bypass confluence boundary node 128, and the second outer bypass bleed air boundary node 129 and the second outer bypass confluence boundary node 130 are respectively composed of three bleed air / confluence modules, and each bleed air / confluence module satisfies the following conditions.

[0093] In step S3, the mode switching transient reverse flow simulation model can also include, for any bleed air boundary node of the core engine bleed air boundary node 124, the first outer bypass bleed air boundary node 126 and the second outer bypass bleed air boundary node 129, setting the total temperature T b1 * , the total pressure p b1 * , the flow rate W b1 , the oil-gas ratio f b1 , the moisture content D b1 of the bleed air boundary node based on the total temperature T b2 * , the total pressure p b2 * , the flow rate W b2 , the oil-gas ratio f b2 , the moisture content D b2 of the bleed air boundary node. The flow rate W b2 of the bleed air boundary node satisfies the following relationship with the flow rates W b of the adjacent M j branches:

[0094]

[0095] wherein ε b represents the bleed air boundary node flow balance equation, W b2 represents the flow rate of the bleed air boundary node, b2 represents the number of the bleed air boundary node and b2 = 1, …, 3, W j represents the flow rate of the jth branch adjacent to the bleed air boundary node, j represents the number of the branch adjacent to the bleed air boundary node and j = 1, …, M b , M bN represents the total number of branches adjacent to the bleed boundary node.

[0096] For any of the core flow boundary node 125, the first outer flow boundary node 128 and the second outer flow boundary node 130, the total pressure p M * , the total enthalpy h M * , the total pressure p M * , the flow rate W M , the oil-gas ratio f M and the humidity D M are given. The given values can be automatically given in the simulation process, and the final results are obtained through the balance equation.

[0097] The total enthalpy h M * , the flow rate W M , the oil-gas ratio f M and the humidity D M of any flow boundary node are given, and the total enthalpy h M k , the flow rate W * , the oil-gas ratio f k and the humidity D k of N k branches adjacent to the flow boundary node satisfy the following relationship:

[0098]

[0099] Wherein, ε M.1 represents the energy balance equation of the flow boundary node, ε M.2 represents the flow balance equation of the flow boundary node, ε M.3 represents the oil-gas ratio balance equation of the flow boundary node, ε M.4 represents the humidity balance equation of the flow boundary node, p M * represents the total pressure of the flow boundary node, represents the total enthalpy of the flow boundary node, W M represents the flow rate of the flow boundary node, f M represents the oil-gas ratio of the flow boundary node, D M represents the humidity of the flow boundary node, M represents the number of the flow boundary node and M = 1, 2, 3, represents the total enthalpy of the kth branch adjacent to the flow boundary node, W k represents the flow rate of the kth branch adjacent to the flow boundary node, f k represents the oil-gas ratio of the kth branch adjacent to the flow boundary node, D krepresents the humidity content of the kth branch adjacent to the merging boundary node, k represents the number of the branch adjacent to the merging boundary node and k = 1, …, N M , N M represents the total number of the branches adjacent to the merging boundary node.

[0100] In the mode switching transient reverse flow simulation model established above, in each bleed / merging module, there are 0 unknown variables and 1 balance equation in the bleed boundary node, and there are 5 unknown variables and 4 balance equations in the merging boundary node. Therefore, the number of unknown variables and balance equations of the bleed / merging module composed of the corresponding bleed boundary node and merging boundary node are equal, which ensures that the simulation method proposed in the present application has a perfect equation closure mechanism and can be solved.

[0101] Step S4, using the mode switching transient reverse flow simulation model for simulation, setting the engine control law and mode selection valve adjustment law, the controllable law can include the relative similar fuel supply flow of the combustion chamber, flight speed, etc., and the mode selection valve adjustment law can be the opening degree of the mode selection valve, etc.; then, the simulation results are obtained and output by the mode switching transient reverse flow simulation model, and the simulation results can include, for example, the transient reverse flow characteristics of mode switching. Finally, a simulation chart is drawn for the analysis and optimization design of the variable cycle aero-engine mode switching.

[0102] Reference Figure 2 and Figure 3 According to another embodiment of the present application, a variable cycle aero-engine mode switching transient reverse flow simulation system is provided, which comprises a mode switching transient reverse flow simulation model established by coupling a main flow path model and a mode switching local flow path model.

[0103] The main flow path model is established by the component method and comprises the functional components of the aero-engine: compression system, combustion system, turbine system, duct system, casing and mixing chamber.

[0104] The mode switching local flow path model is established by a network method, and comprises a mode selection valve, a mode selection valve internal node, a bleed air boundary node, a confluence boundary node, and a connecting flow channel; wherein the bleed air boundary node comprises a mode selection valve internal flow path bleed air boundary node and a mode selection valve external flow path bleed air boundary node; the confluence boundary node comprises a mode selection valve internal flow path confluence boundary node and a mode selection valve external flow path confluence boundary node; and the connecting flow channel comprises a flow channel connecting the mode selection valve internal flow path bleed air boundary node and the mode selection valve internal node, a flow channel connecting the mode selection valve external flow path bleed air boundary node and the mode selection valve internal node, a flow channel connecting the mode selection valve external flow path bleed air boundary node and the mode selection valve external flow path confluence boundary node, and a flow channel connecting the mode selection valve internal node and the mode selection valve internal flow path confluence boundary node; wherein the mode selection valve is switched between a closed state and an open state, so as to adjust the area of the flow channel connecting the mode selection valve external flow path bleed air boundary node and the mode selection valve internal node, and to adjust the area of the flow channel connecting the mode selection valve external flow path bleed air boundary node and the mode selection valve external flow path confluence boundary node.

[0105] The mode switching transient reverse flow simulation model is obtained by coupling the main flow path model established by a component method and the mode switching local flow path model established by a network method through the bleed air boundary node and the confluence boundary node with an equation closure mechanism.

[0106] The following continues to refer to Figure 2 and Figure 3 , and in combination with Figures 4 to 6 , two exemplary embodiments of the variable cycle aero-engine mode switching transient reverse flow simulation method provided by the embodiments of the present application are described, in which the transient reverse flow phenomenon in the mode switching valve of a "dual variable" cycle engine is simulated and analyzed. The results obtained can be used for further optimization design and analysis of the mode switching process regulation. In the following embodiments, the working mode of the "dual variable" cycle engine is adjusted by setting the mode selection valve to the closed state 108 for the turbofan mode, and setting the mode selection valve to the open state 109 for the turbojet mode.

[0107] Embodiment 1

[0108] Figure 4 The simulation results of the reverse flow phenomenon in the louver flow channel of the convection chamber in the acceleration process of the "dual variable" cycle engine in the turbofan mode of Embodiment 1 are shown.

[0109] In this embodiment, the mode switching transient reverse flow simulation model is established by the variable cycle aero-engine mode switching transient reverse flow simulation method provided by the embodiments of the present application, and it is set that when the flow direction of the flow channel is opposite to Figure 3The same direction of the arrow is positive, and vice versa. For example, when the flow direction of the inner combustion chamber shutter flow channel 119 is opposite to the flow direction of the second outer channel to the mode selection valve flow channel (the turbojet) 122, the flow direction of the inner combustion chamber shutter flow channel 119 is opposite to the flow direction of the second outer channel to the mode selection valve flow channel (the turbojet) 122. The same direction of the arrow is positive, and vice versa. For example, when the flow direction of the inner combustion chamber shutter flow channel 119 is opposite to the flow direction of the second outer channel to the mode selection valve flow channel (the turbojet) 122, the flow direction of the inner combustion chamber shutter flow channel 119 is opposite to the flow direction of the second outer channel to the mode selection valve flow channel (the turbojet) 122. Figure 3 The same direction of the arrow is positive, and vice versa. For example, when the flow direction of the inner combustion chamber shutter flow channel 119 is opposite to the flow direction of the second outer channel to the mode selection valve flow channel (the turbojet) 122, the flow direction of the inner combustion chamber shutter flow channel 119 is opposite to the flow direction of the second outer channel to the mode selection valve flow channel (the turbojet) 122.

[0110] In the initial state Ma=2.4, the flow direction of the inner combustion chamber shutter flow channel 119 is opposite, and the flow direction of the second outer channel to the mode selection valve flow channel (the turbojet) 122 is opposite. At present, the mode selection valve is in the closed state 108, and the inner combustion chamber shutter 107 is in the closed state, and most of the second outer channel 111 flows into the front mixing chamber 116, and a small part of the first outer channel 112 flows into the second outer channel 111 through the second outer channel to the mode selection valve flow channel (the turbojet) 122. The gas in the core channel 113 at the outlet of the medium-pressure turbine 105 flows reversely through the inner combustion chamber shutter flow channel 119, and leaks into the first outer channel 112.

[0111] Next, the Ma number increases, and when the Ma number rises to Ma=2.8, the inner combustion chamber shutter flow channel 119 appears to be reversed, and the second outer channel to the mode selection valve flow channel (the turbojet) 122 also appears to be reversed. The flow direction is converted to positive. This is because the core fan 101 and the high-pressure compressor 102 have reduced boost capability, and at this time the pressure of the first outer channel 112 and the outlet gas flow of the medium-pressure turbine 105 is reduced, and the inner combustion chamber shutter 107 is still in the closed state. The second outer channel 111 gas leaks into the first outer channel 112 through the second outer channel to the mode selection valve flow channel (the turbojet) 122, and the gas in the first outer channel 112 leaks into the core channel 113 through the inner combustion chamber shutter flow channel 119.

[0112] Figure 4 The simulation results of the simulation results generated in this embodiment are recorded in the chart, which shows that the flow direction of the gas flowing through the inner combustion chamber shutter flow channel 119 changes during this process, and the high-precision simulation of the instantaneous reverse flow process of the mode switching valve during the acceleration process is realized.

[0113] Embodiment 2

[0114] Figure 5 The simulation results of the mode selection valve angle control law in the mode switching process of the "dual variable" cycle engine of embodiment 2 are shown. Figure 6 The simulation results of the second outer channel to the mode selection valve flow channel (the turbojet) reverse flow phenomenon in the mode switching process of the "dual variable" cycle engine of embodiment 2 are shown.

[0115] In this embodiment, the variable cycle aero-engine mode switching transient reverse flow simulation method according to the embodiment of the application establishes a mode switching transient reverse flow simulation model, and sets that when the flow direction of the flow passage is the same as the arrow direction in the figure, the flow direction is positive, and vice versa. Figure 2 For example, when the flow direction of the fluid in the second outer bypass to mode selection valve flow passage (turbojet) 122 is the same as the arrow direction in the figure, the flow direction is positive, and vice versa. Figure 2 For example, when the flow direction of the fluid in the second outer bypass to mode selection valve flow passage (turbojet) 122 is the same as the arrow direction in the figure, the flow direction is positive, and vice versa.

[0116] In this embodiment, in the turbofan mode, the mode selection valve is in the closed state 108, and the inner bypass combustion chamber shutter 107 is in the closed state, the flow passage area of the second outer bypass to mode selection valve flow passage (turbojet) 122 is the minimum value, which is 565 mm 2 , and the flow passage area of the inner bypass combustion chamber shutter flow passage 119 is the minimum value, which is 283 mm 2 , and the flow passage area of the second outer bypass to mode selection valve flow passage (turbofan) 123 is the maximum value, which is 336464 mm 2 .

[0117] In the turbojet mode, the mode selection valve is in the open state 109, and the inner bypass combustion chamber shutter 107 is in the open state, the flow passage area of the second outer bypass to mode selection valve flow passage (turbojet) 122 is the maximum value, which is 336465 mm 2 , and the flow passage area of the inner bypass combustion chamber shutter flow passage 119 is the maximum value, which is 65973 mm 2 , and the flow passage area of the second outer bypass to mode selection valve flow passage (turbofan) 123 is the minimum value, which is 565 mm 2 The above values are determined based on the design of the variable cycle aero-engine.

[0118] The flow passage areas of the remaining flow passages are all fixed values determined by the structure of the variable cycle aero-engine, for example, the flow passage area of the intermediate pressure turbine rear casing flow passage 118 is 274889 mm 2 , the flow passage area of the first outer bypass to mode selection valve flow passage 120 is 515314 mm 2 , and the flow passage area of the mode selection valve to outer bypass combustion chamber flow passage 121 is 379282 mm 2 .

[0119] Figure 5 The valve angle control law of the mode selection valve in the mode switching process of the “dual variable” cycle engine in this embodiment is given. As the mode selection valve gradually changes from the closed state 108 to the open state 109, the valve angle gradually increases, so that the flow passage areas of the second outer bypass to mode selection valve flow passage (turbojet) 122 and the inner bypass combustion chamber gradually increase from 565 mm 2Increased to 336465mm 2 The flow area of the inner-duct combustion chamber shutter flow passage 119 is increased from 283mm 2 to 65973mm 2 The flow area of the second outer-duct to mode selection valve flow passage (turbojet) 123 is decreased from 336464mm 2 to 565mm 2 .

[0120] Figure 6 The simulation results of the reverse flow phenomenon of the second outer-duct to mode selection valve flow passage (turbojet) 122 in the mode switching process of the "dual variable" cycle engine in this embodiment are shown, and it is shown that the reverse flow of the second outer-duct to mode selection valve flow passage (turbojet) 122 occurs in the transition process of mode switching, and high-precision simulation of the instantaneous reverse flow of the mode switching valve in the mode switching transition process is achieved, and the time resolution can reach 0.1ms.

[0121] Through the above application of the embodiment of the variable cycle aero-engine mode switching instantaneous reverse flow simulation method provided by the application, it can be concluded that the variable cycle aero-engine mode switching instantaneous reverse flow simulation method and simulation system provided by the application realize the simulation of the instantaneous reverse flow of the mode selection valve of the variable cycle aero-engine, and realize high-precision resolution simulation of the reverse flow phenomenon, and provide support for the analysis and optimization design of the variable cycle aero-engine mode switching.

[0122] All the optional technical solutions described above can be combined to form optional embodiments of the application, and will not be described one by one here.

[0123] It should be understood that the size of the serial number of each step in the above embodiments does not mean the order of execution, and the execution order of each process should be determined according to its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiments of the application.

[0124] The above is only a preferred specific embodiment of the application, but the protection scope of the application is not limited to this, any person skilled in the art can easily think of changes or replacements within the technical scope disclosed by the application, which should be covered within the protection scope of the application.

Claims

1. A method for simulating reverse flow during mode switching of a variable cycle aeroengine, the method comprising: The method comprises the following steps: Step S1, a main flow path model of the variable cycle aero-engine is established by using a component method, the main flow path model comprising main functional components of the aero-engine: a compression system, a combustion system, a turbine system, a duct system, a nacelle and a mixing chamber; Step S2, a mode switching local flow path model of the variable cycle aero-engine is established by using a network method, the mode switching local flow path model comprising: a mode selection valve, an internal node of the mode selection valve, a bleed air boundary node, a merging boundary node, and a connecting flow channel; wherein the bleed air boundary node comprises a mode selection valve inside flow path bleed air boundary node and a mode selection valve outside flow path bleed air boundary node; wherein the merging boundary node comprises a mode selection valve inside flow path merging boundary node and a mode selection valve outside flow path merging boundary node; and wherein the connecting flow channel comprises a flow channel connecting the mode selection valve inside flow path bleed air boundary node and the internal node of the mode selection valve, a flow channel connecting the mode selection valve outside flow path bleed air boundary node and the internal node of the mode selection valve, a flow channel connecting the mode selection valve outside flow path bleed air boundary node and the mode selection valve outside flow path merging boundary node, and a flow channel connecting the internal node of the mode selection valve and the mode selection valve inside flow path merging boundary node; wherein the mode selection valve is switched between a closed state and an open state, so as to adjust the area of the flow channel connecting the mode selection valve outside flow path bleed air boundary node and the internal node of the mode selection valve, and to adjust the area of the flow channel connecting the mode selection valve outside flow path bleed air boundary node and the mode selection valve outside flow path merging boundary node; Step S3, a mode switching transient reverse flow simulation model is constructed, the mode switching transient reverse flow simulation model being obtained by coupling the main flow path model established by the component method and the mode switching local flow path model established by the network method through the bleed air boundary node and the merging boundary node having an equation closure mechanism; Step S4, simulation is performed by using the mode switching transient reverse flow simulation model, an aero-engine control law and a mode selection valve adjustment law being set in the simulation, a simulation result being obtained and output by the mode switching transient reverse flow simulation model, and a simulation chart being drawn according to the simulation result, for analysis and optimization design of mode switching of the variable cycle aero-engine.

2. The variable cycle aeroengine mode switching transient reverse flow simulation method of claim 1, wherein, Step S3 further comprises: The main flow path model established by the component method is coupled with the mode switching valve local flow path model established by the network method, specifically, the mode selection valve inside flow path bleed air boundary node, the mode selection valve outside flow path bleed air boundary node, the internal node of the mode selection valve, the mode selection valve inside flow path merging boundary node, and the mode selection valve outside flow path merging boundary node are coupled with the main flow path model by having an equation closure mechanism; The corresponding mode selection valve inside flow path bleed air boundary node and the mode selection valve inside flow path merging boundary node, and the mode selection valve outside flow path bleed air boundary node and the mode selection valve outside flow path merging boundary node are respectively composed into bleed air / merging modules.

3. The variable cycle aeroengine mode switching transient reverse flow simulation method of claim 1, wherein, In the main flow path model established in step S1: The duct system comprises a first outer duct, a second outer duct and a third outer duct arranged from inside to outside.

4. The variable cycle aeroengine mode switching transient reverse flow simulation method of claim 3, wherein, The mode switching local flow path model established in step S2 further comprises: a core engine bleed air boundary node and a core engine confluence boundary node; and a medium-pressure turbine rear nacelle flow channel connecting the core engine bleed air boundary node and the core engine confluence boundary node, and an inner-duct combustor shutter flow channel connecting the core engine confluence boundary node and an internal node of the mode selection valve.

5. The variable cycle aeroengine mode switching transient reverse flow simulation method of claim 4, wherein, In the mode switching local flow path model established in step S2: The mode selection valve internal flow path bleed air boundary node is a first outer-duct bleed air boundary node; The mode selection valve external flow path bleed air boundary node is a second outer-duct bleed air boundary node; The mode selection valve internal flow path confluence boundary node is a first outer-duct confluence boundary node; The mode selection valve external flow path confluence boundary node is a second outer-duct confluence boundary node; The flow channel connecting the mode selection valve internal flow path bleed air boundary node and the internal node of the mode selection valve is a first outer-duct to mode selection valve flow channel connecting the first outer-duct bleed air boundary node and the internal node of the mode selection valve; The flow channel connecting the mode selection valve external flow path bleed air boundary node and the internal node of the mode selection valve is a second outer-duct to mode selection valve flow channel connecting the second outer-duct bleed air boundary node and the internal node of the mode selection valve; The flow channel connecting the mode selection valve external flow path bleed air boundary node and the mode selection valve external flow path confluence boundary node is a second outer-duct to mode selection valve flow channel connecting the second outer-duct bleed air boundary node and the second outer-duct confluence boundary node; The flow channel connecting the internal node of the mode selection valve and the mode selection valve internal flow path confluence boundary node is a mode selection valve to outer-duct combustor flow channel connecting the internal node of the mode selection valve and the first outer-duct confluence boundary node.

6. The variable cycle aeroengine mode switching transient reverse flow simulation method of claim 5, wherein, Step S3 further comprises: The component method for establishing the main flow path model is coupled with the network method for establishing the mode switching valve local flow path model, specifically, by coupling the core engine bleed air boundary node, the first outer-duct bleed air boundary node, the second outer-duct bleed air boundary node, and the core engine confluence boundary node, the first outer-duct confluence boundary node, and the second outer-duct confluence boundary node with the main flow path model to achieve the coupling; The core engine bleed air boundary node and the core engine confluence boundary node, the first outer-duct bleed air boundary node and the first outer-duct confluence boundary node, and the second outer-duct bleed air boundary node and the second outer-duct confluence boundary node are respectively composed into three bleed air / confluence modules.

7. The variable cycle aeroengine mode switching transient reverse flow simulation method of claim 6, wherein, Step S3 of constructing the mode switching transient reverse flow simulation model further comprises: For any one of the core engine bleed air boundary nodes, the first bypass bleed air boundary node, and the second bypass bleed air boundary node, set a total temperature T based on the upstream mainstream component connected to that bleed air boundary node. b1 * Total pressure p b1 * Traffic W b1 Oil-to-gas ratio f b1 Moisture content D b1 The total temperature T at the air-drawing boundary node is obtained. b2 * Total pressure p b2 * Traffic W b2 Oil-to-gas ratio f b2 Moisture content D b2 ; Setting the flow W of any air entraining boundary node b2 W of the adjacent M b branches satisfies the following relationship: j W of the adjacent M where ε b represents the bleed air boundary node flow balance equation, W b2 represents the flow of the bleed air boundary node, b2 represents the number of the bleed air boundary node and b2 = 1, 3, W j represents the flow of the jth branch adjacent to the bleed air boundary node, j represents the number of the branch adjacent to the bleed air boundary node and j = 1, M b , M b represents the total number of branches adjacent to the bleed air boundary node; For any one of the core machine flow convergence boundary node, the first external flow convergence boundary node and the second external flow convergence boundary node, the total pressure, total enthalpy, flow, oil-gas ratio and humidity content of the any one flow convergence boundary node are set as trial values, and the total enthalpy, flow, oil-gas ratio and humidity content of N M adjacent branch nodes of the any one flow convergence boundary node satisfy the following relationship: Where, ε M.1 The energy balance equation for the confluence boundary node is given by ε. M.2 The flow balance equation for the confluence boundary node is given by ε. M.3 The equation representing the oil-gas ratio balance at the confluence boundary node, ε M.4 The equation representing the moisture content balance at the confluence boundary node is as follows: W represents the total enthalpy of the confluence boundary node. M f represents the flow at the confluence boundary node. M D represents the oil-gas ratio at the confluence boundary node. M The value represents the moisture content of the confluence boundary node, where M represents the node number and M = 1, ..., 3. W represents the total enthalpy of the k-th branch adjacent to the confluence boundary node. k f represents the flow rate of the k-th branch adjacent to the confluence boundary node. k D represents the oil-gas ratio of the k-th branch adjacent to the confluence boundary node. k This represents the moisture content of the k-th branch adjacent to the confluence boundary node, where k represents the branch number adjacent to the confluence boundary node and k = 1, ..., N. M N M This represents the total number of branches adjacent to the confluence boundary node.

8. A simulation system constructed based on the variable cycle aeroengine mode switching transient reverse flow simulation method according to any one of the preceding claims 1 to 7, characterized in that, The mode switching transient reverse flow simulation model established by coupling the main flow path model and the mode switching local flow path model; The main flow path model is established by the component method and comprises functional components of the aero-engine: a compression system, a combustion system, a turbine system, a duct system, a nacelle, and a mixing chamber; The mode switching local flow path model is established by a network method, and comprises a mode selection valve, a mode selection valve internal node, a bleed air boundary node, a confluence boundary node, and a connecting flow passage; the bleed air boundary node comprises a mode selection valve internal flow path bleed air boundary node and a mode selection valve external flow path bleed air boundary node; the confluence boundary node comprises a mode selection valve internal flow path confluence boundary node and a mode selection valve external flow path confluence boundary node; the connecting flow passage comprises a flow passage connecting the mode selection valve internal flow path bleed air boundary node and the mode selection valve internal node, a flow passage connecting the mode selection valve external flow path bleed air boundary node and the mode selection valve internal node, a flow passage connecting the mode selection valve external flow path bleed air boundary node and the mode selection valve external flow path confluence boundary node, and a flow passage connecting the mode selection valve internal node and the mode selection valve internal flow path confluence boundary node; the mode selection valve is switched between a closed state and an open state, so as to adjust the area of the flow passage connecting the mode selection valve external flow path bleed air boundary node and the mode selection valve internal node, and to adjust the area of the flow passage connecting the mode selection valve external flow path bleed air boundary node and the mode selection valve external flow path confluence boundary node. The mode switching transient reverse flow simulation model is obtained by coupling the main flow path model established by a component method and the mode switching local flow path model established by a network method through the bleed air boundary node and the confluence boundary node with an equation closure mechanism.

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