Method for controlling liquid hydrogen flow of liquid hydrogen heat exchange assembly for regenerative function nozzle and design method of inclined angle grid

Abstract

This invention provides a regenerative nozzle for hydrogen engines, a method for controlling liquid hydrogen flow, and a design method for angled grids, relating to the field of aero-engine intake and exhaust technology. It includes: a circular-to-square section, a straight section, a single-sided section, angled grids, and a liquid hydrogen heat exchange assembly. The circular-to-square section, straight section, and single-sided section are connected sequentially in the flight direction. Multiple angled grids are connected to the single-sided section in the flight direction and are spaced apart. The liquid hydrogen heat exchange assembly includes a liquid hydrogen heat exchange tube, a liquid hydrogen inlet, and a liquid hydrogen outlet. The liquid hydrogen heat exchange tube connects to the interior of the wall of each angled grid through the interior of the straight section and the single-sided section, forming a set of liquid hydrogen heat exchange loops within the wall of each angled grid. The liquid hydrogen inlet and outlet are connected to the supply port and recovery port of the liquid hydrogen supply flow path, respectively. Liquid hydrogen is injected from the liquid hydrogen inlet into the liquid hydrogen heat exchange tube, flows through each set of liquid hydrogen heat exchange loops, and then flows out from the liquid hydrogen outlet through the liquid hydrogen heat exchange tube. This effectively improves the stealth capability of the nozzle.

Description

Technical Field

[0001] This invention relates to the field of aero-engine intake and exhaust technology, specifically to a regenerative nozzle suitable for hydrogen engines, a method for controlling liquid hydrogen flow, and a design method for angled grilles. Background Technology

[0002] The nozzle is the exhaust device of an aircraft engine. High-temperature combustion gases expand and do work inside the nozzle, generating thrust. The nozzle is also known as the exhaust system.

[0003] Nozzles are classified into subsonic nozzles and supersonic nozzles according to their exhaust performance; into convergent nozzles and divergent nozzles according to their different structural forms; into fixed nozzles and adjustable nozzles according to their mechanism; and they can also be equipped with vectoring and stealth functions according to their usage requirements.

[0004] Aircraft emphasizing stealth capabilities typically employ fixed nozzles with flat exhaust tips. For example, the F-117 uses a rectangular exhaust tip with a high aspect ratio. To enhance stealth and rigidity, a directional grille is usually added to the exhaust tip. This grille effectively blocks infrared radiation from the inner side of the engine's rear chamber. The main problem is that, since the grille is located within the exhaust channel, the high-temperature exhaust gases cause it to heat up, generating new infrared radiation.

[0005] By placing a regenerator inside the nozzle, heat from the exhaust can be recovered, improving the engine's thermal cycle efficiency. Traditional regenerators are usually located inside the flow channel, which has a significant impact on nozzle performance. Summary of the Invention

[0006] In view of this, embodiments of this specification provide a regenerative nozzle for a hydrogen engine, a method for controlling the flow of liquid hydrogen, and a design method for an angled grid, so as to achieve heat recovery by exchanging heat between the liquid hydrogen heat exchanger and the high-temperature gas in the nozzle.

[0007] The embodiments in this specification provide the following technical solutions:

[0008] A regenerative nozzle suitable for hydrogen engines, comprising:

[0009] Circular-to-square sections, straight sections, single-sided sections, angled grids, and liquid hydrogen heat exchange components;

[0010] The round-to-square section, the straight section, and the single-sided section are connected sequentially in the direction of navigation, and multiple angled grilles are connected to the single-sided section in the direction of navigation and are spaced apart;

[0011] The liquid hydrogen heat exchange assembly includes a liquid hydrogen heat exchange tube, a liquid hydrogen inlet, and a liquid hydrogen outlet. The liquid hydrogen heat exchange tube connects to the interior of the wall of each angled grid through the interior of the straight section and the single-sided section, forming a set of liquid hydrogen heat exchange loops inside the wall of each angled grid. The liquid hydrogen inlet and liquid hydrogen outlet are connected to the supply port and recovery port of the liquid hydrogen supply flow path, respectively.

[0012] Liquid hydrogen is injected into the liquid hydrogen heat exchange tube from the liquid hydrogen inlet, flows through each set of liquid hydrogen heat exchange loops, and then flows out from the liquid hydrogen outlet through the liquid hydrogen heat exchange tube.

[0013] A method for controlling the flow rate of liquid hydrogen in a liquid hydrogen heat exchange component includes the following steps:

[0014] Real-time acquisition of total gas temperature T and gas flow rate Q at the nozzle inlet section 气 The wall temperature T of the angled grid wall And as a detection parameter, based on the current engine operating conditions or preset task profile, determine the current required regenerative load Q. 热 The maximum permissible wall temperature T required for infrared suppression max And as a requirement for judgment;

[0015] Based on the detection parameters and judgment requirements, a heat balance equation is constructed. Using the heat balance equation as the core constraint, the regenerative load Q is calculated to satisfy the requirements. 热 And the wall temperature T wall Not exceeding the maximum allowable wall temperature T max Minimum required liquid hydrogen flow rate Q 氢,req ;

[0016] Based on the minimum required liquid hydrogen flow rate Q 氢,req Generate control commands to adjust the opening of the control valve in the liquid hydrogen supply pipeline, so that the actual liquid hydrogen flow rate reaches the minimum required liquid hydrogen flow rate Q. 氢,req .

[0017] Furthermore, a heat balance equation is constructed based on the detection parameters and judgment requirements. Using the heat balance equation as the core constraint, the regenerative load Q is calculated. 热 And the wall temperature T wall Not exceeding the maximum allowable wall temperature T max Minimum required liquid hydrogen flow rate Q 氢,req ,include:

[0018] The heat Q absorbed by liquid hydrogen inside the heat exchanger tubes. 吸收 The calculation formula, where, ,in, The specific heat capacity of liquid hydrogen, This represents the temperature rise of liquid hydrogen during the heat exchange process;

[0019] Constructing the heat Q recovered from the gas 回收 The calculation formula, where, , For heat exchange efficiency, The specific heat capacity of liquid hydrogen, The total temperature of the combustion gas at the nozzle inlet section;

[0020] The heat Q absorbed by the liquid hydrogen inside the heat exchange tubes 吸收 With the heat Q recovered from the gas 回收 Equality is used as a condition to construct the heat balance equation;

[0021] Construct a system that meets the regenerative load Q 热 The objective equation is to recover the heat Q from the gas. 回收 ≥Regenerative load Q 热 ;

[0022] Based on the heat balance equation and the objective equation, the basic value of liquid hydrogen flow rate Q is calculated. 氢,base ;

[0023] Through the maximum allowable wall temperature T max For the basic value of liquid hydrogen flow rate Q 氢,base After correction, the minimum required liquid hydrogen flow rate Q is obtained. 氢,req .

[0024] Furthermore, by the maximum allowable wall temperature T max For the basic value of liquid hydrogen flow rate Q 氢,base After correction, the minimum required liquid hydrogen flow rate Q is obtained. 氢，req ,include:

[0025] The calculated basic value of liquid hydrogen flow rate Q 氢，base Substituting into the heat balance equation, the predicted steady-state wall temperature T is obtained by reverse calculation. wall_est ;

[0026] Compare steady-state wall temperatures T wall_est With the maximum allowable wall temperature T max ;

[0027] If T wall_est ≤T max Let the minimum required liquid hydrogen flow rate Q be 氢，req =Basic value of liquid hydrogen flow rate Q 氢,base ;

[0028] If T wall_est >T max Therefore, with the goal of increasing cooling intensity, the heat balance equation is resolved to satisfy T. wall_est ≤T max For the new constraints, the corrected minimum required liquid hydrogen flow rate Q was calculated. 氢，req .

[0029] A design method for an angled grille, comprising the following steps:

[0030] Obtain the design input parameters for the regenerative nozzle, including the nozzle's structure and dimensions, and the inlet gas flow rate Q. 气 The total gas temperature T at the nozzle inlet section, and the supply pressure and initial temperature of liquid hydrogen;

[0031] Based on the design input parameters, a coupled analysis model is constructed to predict the nozzle performance as a function of the grid length L of the angled grid. The coupled analysis model is used as the input for the nozzle inlet gas flow rate Q. 气 The total gas temperature T at the nozzle inlet section and the supply pressure and initial temperature of liquid hydrogen are used as variables, with the grid length L as the independent variable, to output the predicted total system heat transfer Q. rec (L) Predicted average grid wall temperature T wall (L) Predicted nozzle thrust coefficient C f (L) and the predicted grid subsystem quality M grid (L);

[0032] The core performance indicator constraints are determined based on the mission requirements of the aircraft. These constraints include the minimum required heat recovery rate Q. 热_min The maximum permissible wall temperature T of the grille wall_max and the minimum thrust coefficient C required to be guaranteed f_min ;

[0033] Q rec (L)≥Q 热_min And T wall (L)≤T wall_max And C f (L)≥C f_min As a constraint, the coupled analysis model is solved, and the final design grid length L is determined from the set of all grid length solutions that satisfy the constraints. design .

[0034] Furthermore, based on the design input parameters, a coupled analysis model is constructed to predict the nozzle performance as a function of the angled grid length L, including:

[0035] A regenerative and thermodynamic analysis sub-model is constructed to characterize the relationship between the grid length L and the total heat transfer Q of the system. rec (L), Average wall temperature of the grille T wall The quantitative relationship between (L) is established, and the average wall temperature T of the grid is output. wall (L) and total heat exchange of the system Q rec (L);

[0036] An aerodynamic performance analysis sub-model is constructed to characterize the relationship between the grid length L and the nozzle thrust coefficient C. f The quantitative relationship between (L) is given, and the nozzle thrust coefficient C is output. f (L);

[0037] A structural quality analysis sub-model is constructed to characterize the relationship between the grid length L and the grid subsystem mass M. grid The quantitative relationship between (L) is established, and the mass M of the grid subsystem is output. grid (L);

[0038] The regenerative and thermodynamic analysis sub-model, the aerodynamic performance analysis sub-model, and the structural quality analysis sub-model are coupled through data interaction to generate a coupled analysis model.

[0039] Furthermore, a regenerative and thermodynamic analysis sub-model is constructed, including:

[0040] The basic data are extracted and determined from the design input parameters. These basic data include the total gas temperature T at the nozzle inlet section and the gas flow rate Q at the nozzle inlet. 气 The supply pressure of liquid hydrogen is related to the initial temperature and the thermal conductivity λ of the angled grid material;

[0041] Using the grid length L as the driving variable, a parametric geometric expression for the regenerative nozzle is generated. Based on this parametric geometric expression, geometric feature quantities associated with the grid length L are calculated. These geometric feature quantities include the grid wetted area A. wet (L) and the hydraulic diameter of the internal flow channel D h (L);

[0042] Based on fundamental data and geometric features, a set of steady-state conjugate heat transfer control equations is constructed to characterize the convective heat transfer between the gas and the grid wall, the heat conduction inside the grid solid, and the convective heat transfer between the liquid hydrogen and the channel wall.

[0043] Numerical methods were used to solve the steady-state conjugate heat transfer control equations to obtain temperature field and heat flow field distribution data corresponding to the grid length L.

[0044] Post-processing of the temperature and heat flow field distribution data allows for the calculation of the total system heat transfer Q as a function of the grid length L through integration. rec (L), and the average wall temperature T of the grille as a function of the grille length L is obtained by area-weighted averaging. wall (L);

[0045] Total heat exchange of the output system Q rec (L) and average wall temperature of the grid T wall (L).

[0046] Furthermore, an aerodynamic performance analysis sub-model is constructed, including:

[0047] The gas physical properties and nozzle inlet flow conditions are extracted from the design input parameters and used as set parameters. The average wall temperature T of the grid output from the regenerative and thermodynamic analysis sub-model is then used. wall (L) serves as the wall thermal boundary condition for the angled grid;

[0048] Using the grid length L as the driving variable, a parametric geometric model of the internal flow channel containing the angled grid is generated;

[0049] Based on a parametric geometric model, a computational fluid dynamics (CFD) mesh is generated that updates with the grid length L. Then, aerodynamic geometric features associated with the grid length L are extracted from the CFD mesh. These aerodynamic geometric features include the grid wetted area A. wet (L) and grid wet area A wet (L) Projected area in the direction of flow;

[0050] Based on the set parameters, wall thermal boundary conditions, and aerodynamic geometric characteristics, a set of governing equations for viscous fluid dynamics, including the laws of conservation of mass, momentum, and energy, is constructed.

[0051] The governing equations of viscous fluid dynamics were solved using numerical methods to obtain convergent flow field data corresponding to the grid length L;

[0052] Post-processing of the convergent flow field data allows for the calculation of the nozzle thrust coefficient C as a function of the grid length L, using the momentum flux and pressure at the nozzle exit section. f (L);

[0053] Output nozzle thrust coefficient C f (L).

[0054] Furthermore, a sub-model for structural quality analysis is constructed, including:

[0055] The material density ρ, elastic modulus E, and coefficient of thermal expansion α of the grid structure are extracted from the design input parameters and used as material property data. The average wall temperature T of the grid output from the regenerative and thermodynamic analysis sub-model is then compared with this data. wall (L) is set as the thermal load condition acting on the angled grid;

[0056] A parametric structural geometric model of the oblique grille is generated using the grille length L as the driving variable.

[0057] Based on the parametric structural geometric model, a finite element analysis mesh updated with the grid length L is generated, and structural geometric property data associated with the grid length L are calculated. These structural geometric property data include the grid cross-sectional area A. cs(L) and the moment of inertia of the section I(L);

[0058] Based on material property data, thermal load conditions, and structural geometric property data, the predicted mass M of the grid subsystem is calculated according to the geometric volume V(L) corresponding to the material density ρ and the grid length L. grid (L);

[0059] Output grid subsystem mass M grid (L).

[0060] Furthermore, Q rec (L)≥Q 热_min And T wall (L)≤T wall_max And C f (L)≥C f_min As a constraint, the coupled analysis model is solved, and the final design grid length L is determined from the set of all grid length solutions that satisfy the constraints. design ,include:

[0061] Using a coupled analysis model, sampling or continuous analysis is performed within the domain of the grid length L to filter out all ranges of grid length L that satisfy the constraints, thus forming the feasible solution domain Ω.

[0062] A comprehensive evaluation function F(L) is constructed based on the feasible solution domain Ω. F(L) is used to quantify and evaluate the comprehensive performance of any feasible solution for grid length L, where L∈Ω. The comprehensive evaluation function F(L) is based on the total heat transfer Q of the system. rec (L), Average wall temperature of the grille T wall (L), Nozzle thrust coefficient C f (L) and the mass M of the grid system grid (L) After weighted combination, the total heat exchange of the system Q is constructed. rec (L) and nozzle thrust coefficient C f The weight of (L) is set to a positive weight, and the average wall temperature T of the grid is... wall (L) and the mass M of the grid system grid The weight of (L) is set to a negative weight;

[0063] Within the feasible solution domain Ω, a numerical optimization algorithm is executed to find the optimal solution that maximizes the comprehensive evaluation function F(L) within the feasible solution domain Ω. This optimal solution is then used as the final design grid length L. design .

[0064] Compared with the prior art, the beneficial effects that at least one technical solution adopted in the embodiments of this specification can achieve include at least:

[0065] By integrating liquid hydrogen heat exchange tubes into the interior of the angled grid wall, the grid is actively and efficiently cooled by cryogenic liquid hydrogen. This directly and effectively reduces the surface temperature of the grid, straight sections, and single-sided sections, thereby fundamentally suppressing its infrared radiation intensity. As a result, aircraft that use flat nozzles with a large aspect ratio to pursue stealth effects can retain the advantages of the grid structure while solving its inherent heat generation problem, thus effectively improving its stealth capabilities. Attached Figure Description

[0066] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0067] Figure 1 This is a schematic diagram of the overall structure of a regenerative nozzle for a hydrogen engine according to an embodiment of the present invention.

[0068] Figure 2 This is a schematic diagram of the liquid hydrogen heat exchanger tube according to an embodiment of the present invention;

[0069] Figure 3 This is a side sectional view of a regenerative nozzle for a hydrogen engine according to an embodiment of the present invention.

[0070] Figure 4 This is a schematic diagram of an oblique grille according to an embodiment of the present invention;

[0071] Figure 5 This is a schematic diagram of the extended angled grille according to an embodiment of the present invention.

[0072] The attached diagram is labeled as follows: 1. Round-to-square section; 2. Straight section; 3. Single-sided section; 4. Angled grid; 5. Liquid hydrogen heat exchange tube; 6. Liquid hydrogen inlet; 7. Liquid hydrogen outlet. Detailed Implementation

[0073] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0074] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0075] like Figures 1 to 4 As shown in the figure, this embodiment of the invention provides a regenerative nozzle suitable for hydrogen-powered aircraft engines. The nozzle mainly includes a round-to-square section 1, a straight section 2, a single-sided section 3, an angled grid 4, and a liquid hydrogen heat exchange assembly.

[0076] The circular-to-square section 1, the straight section 2, and the single-sided section 3 are connected sequentially along the flight direction to form the basic nozzle flow channel. Multiple angled grids 4 are connected along the flight direction at the exit end of the single-sided section 3 and are evenly distributed. The main function of the angled grids 4 is to effectively shield the nozzle exit, improving stealth performance. Simultaneously, as a supporting structure, they enhance the overall rigidity of the nozzle's rear end.

[0077] The liquid hydrogen heat exchange assembly is the core component of this invention, enabling heat recovery and infrared suppression. The assembly includes liquid hydrogen heat exchange tubes 5, a liquid hydrogen inlet 6, and a liquid hydrogen outlet 7. The liquid hydrogen heat exchange tubes 5 are arranged within the wall thickness of the straight section 2, the single-sided section 3, and each angled grid 4, forming a complex internal flow channel network. Specifically, the liquid hydrogen heat exchange tubes 5 form an independent liquid hydrogen heat exchange loop within the wall surface of each angled grid 4. The liquid hydrogen inlet 6 and the liquid hydrogen outlet 7 are located outside the nozzle, typically in the connection area between the round-to-square section 1 and the straight section 2, and are respectively connected to the supply port and recovery port of the external liquid hydrogen supply system.

[0078] During operation, liquid hydrogen, serving as the cooling medium, is injected into the liquid hydrogen heat exchange tube 5 through the liquid hydrogen inlet 6. After flowing through the inner channels of the straight section 2 and the single-sided section 3, it is diverted into the heat exchange loops inside each angled grid 4. Inside the angled grid 4, the liquid hydrogen exchanges heat with the high-temperature combustion gas flowing through the nozzle via the wall surface, absorbing heat from the combustion gas and increasing its temperature. Finally, it collects and flows out from the liquid hydrogen outlet 7, completing one cooling cycle. This process achieves two key effects:

[0079] Firstly, it recovers some of the waste heat from the exhaust gases, which can be returned to the engine for recycling, thus improving thermal efficiency.

[0080] Secondly, it effectively reduces the wall temperature of the angled grille 4, straight section 2 and single-sided section 3 exposed to the combustion gases, significantly suppressing their infrared radiation intensity, thereby enhancing the infrared stealth performance of the aircraft.

[0081] This invention also provides an intelligent control method for controlling the liquid hydrogen flow rate in the aforementioned liquid hydrogen heat exchange assembly, aiming to achieve precise heat recovery and efficient cooling, and avoid insufficient cooling or waste of liquid hydrogen. The method includes the following steps:

[0082] First, parameter monitoring and demand assessment are conducted. The total gas temperature T and gas flow rate Q at the nozzle inlet section are acquired in real time. 气 and the wall temperature T of the angled grille 4 wall This serves as a real-time monitoring parameter. Simultaneously, based on the engine's current operating state (e.g., takeoff, cruise, dogfight) or a preset flight mission profile, the required regenerative load Q for the current phase is determined. 热 And the maximum permissible grid wall temperature T to meet infrared stealth requirements. max .

[0083] Secondly, the liquid hydrogen flow rate is calculated based on heat balance. The core heat balance equation is constructed as follows: the heat Q absorbed by the liquid hydrogen within the heat exchanger tube. 吸收 Equal to the heat Q recovered from the gas. 回收 .in, ,in, The specific heat capacity of liquid hydrogen, The temperature rise of liquid hydrogen during the heat exchange process is denoted as , where , For heat exchange efficiency, For the specific heat capacity of the gas, The total gas temperature at the nozzle inlet section. The primary goal is to meet the regenerative requirements, i.e., to make Q... 回收 ≥ Q 热 By combining the heat balance equation, a basic value for the liquid hydrogen flow rate Q can be calculated. 氢,base .

[0084] Then, infrared constraint verification and flow correction are performed. The calculated Q is then... 氢,base Substituting into the heat balance equation, we can deduce the estimated steady-state wall temperature T that can be achieved at this flow rate. wall_est .

[0085] T wall_est With the maximum allowable wall temperature T max Comparison: If T wall_est ≤T max This indicates that the requirements for both heat recovery and infrared suppression are met, thus determining the minimum required liquid hydrogen flow rate Q. 氢,req = Q 氢,base If T wall_est >T max This indicates that cooling needs to be strengthened. In this case, the cooling intensity should be increased to ensure T. wall_est ≤ T max For the new constraints, the heat balance equation is solved again, and a larger corrected flow rate is obtained as Q. 氢,req .

[0086] Finally, flow regulation is performed. The minimum required liquid hydrogen flow rate Q is determined based on calculations. 氢,req Generate control commands to adjust the opening of the control valve in the liquid hydrogen supply pipeline, so that the actual supplied liquid hydrogen flow rate precisely matches Q. 氢,req This enables on-demand, efficient closed-loop control.

[0087] like Figure 5 As shown, in another embodiment of the present invention, the angled grid 4 can be extended within the straight section of the nozzle. The extended angled grid 4 can achieve more heat exchange area and more rigidity support, but it will result in increased structural weight and increased aerodynamic losses.

[0088] Therefore, embodiments of the present invention also provide a systematic design method for optimizing the length of the oblique grille 4. This method transforms engineering experience into a quantifiable and computable model-driven process, specifically including:

[0089] The first step is to obtain the design inputs and constraints.

[0090] The design input parameters are determined, including the specific structure and dimensions of the nozzle, the gas flow rate Q and total temperature T at the design point, and the supply pressure and initial temperature of liquid hydrogen. Simultaneously, based on the overall mission requirements of the spacecraft, the constraint values ​​for core performance indicators are derived, including the minimum achievable heat recovery Q. 热_min The maximum permissible wall temperature T of the grille wall_max (Based on stealth performance indicators), and the minimum thrust coefficient C that must be guaranteed. f_min .

[0091] The second step is to construct a multi-performance coupling analysis model.

[0092] The multi-performance coupling analysis model aims to establish a mathematical model capable of predicting multiple key performance characteristics of nozzles under different grille lengths L. This coupling analysis model is formed by integrating three specialized sub-models and coupling them through data interaction:

[0093] Regeneration and thermodynamic analysis sub-model:

[0094] Used to establish the relationship between the grid length L and the total heat exchange of the system Q rec (L), Average wall temperature of the grille T wall The quantitative relationship of (L) was established. The construction process included: extracting parameters and material properties of the fuel gas and liquid hydrogen; using the grid length L as the driving variable, establishing a parametric geometric model and calculating the grid wetted area A. wet (L) and other characteristic quantities; construct and solve the conjugate heat transfer control equations describing the gas-solid-liquid hydrogen heat exchange; obtain Q through post-processing integration and averaging. rec (L) and T wall (L).

[0095] Aerodynamic performance analysis sub-model:

[0096] Used to establish the relationship between grid length L and nozzle thrust coefficient C f The quantitative relationship of (L) is established. Its construction process includes: extracting the fuel gas properties and inlet conditions, and receiving the T output from the regenerative sub-model. wall (L) serves as the wall thermal boundary condition; a parameterized flow channel model and computational mesh are generated driven by the grid length L; the fluid dynamics governing equations considering viscosity and wall friction effects are constructed and solved; C is calculated by integrating the outlet momentum and pressure. f (L).

[0097] Structural quality analysis sub-model:

[0098] Used to establish the relationship between grid length L and grid subsystem mass M grid The quantitative relationship of (L) is established. Its construction process includes: extracting material properties such as density and elastic modulus, and receiving T... wall (L) is used as the thermal load condition; a parametric structural finite element model is generated driven by the grid length L; the mass M is calculated. grid (L), optionally, the thermal stress σ can also be obtained through thermal-structural coupling analysis. max (L) and deformation δ max (L) to verify structural integrity.

[0099] The third step is to perform constraint optimization and decision-making.

[0100] Q rec (L) ≥Q 热_min T wall (L)≤ T wall_max C f (L)≥C f_min As a hard constraint, a coupled analysis model is used to search within the domain of length L, selecting all grid lengths L values ​​that satisfy the constraint to form a feasible solution domain Ω. Then, a comprehensive evaluation function F(L) is constructed, which is usually Q. rec (L), C f (L) (positive contribution) and T wall (L), M grid The weighted sum of (L) (negative contributions) is used to quantitatively evaluate the overall merits of each feasible solution. Finally, within the feasible solution domain Ω, a numerical optimization algorithm is applied to maximize F(L) to determine the optimal design grid length L that achieves the best overall performance. design Design the grille length L design It can be used directly to guide the manufacturing of fixed-length angled grids, or as a benchmark value to develop adjustment control laws for adjustable-length grids under different working conditions.

[0101] As can be seen from the above specific embodiments, the present invention combines an innovative nozzle structure, an intelligent liquid hydrogen control method, and a systematic design method based on a multi-physics coupling model, effectively solving the problems of strong infrared radiation, large flow resistance and heavy weight of traditional grid nozzles, and achieving efficient coordination and optimization of heat recovery, stealth, thrust and structural weight.

[0102] In this embodiment of the invention, taking a typical state parameter as an example, a 10% increase in the length of the angled grid 4 corresponds to a 0.8% increase in nozzle weight, a 0.5% decrease in total pressure recovery coefficient, and a 0.1% decrease in thrust coefficient. For different nozzle configurations and different operating states, the above parameter values ​​will differ, but the qualitative analysis will not change.

[0103] Beneficial effects of the embodiments of the present invention:

[0104] This invention integrates liquid hydrogen heat exchange tubes into the interior of the angled grid wall, utilizing cryogenic liquid hydrogen for active and efficient cooling of the grid. This directly and effectively reduces the surface temperature of the grid, straight sections, and single-sided sections, fundamentally suppressing its infrared radiation intensity. This allows aircraft employing high aspect ratio flat nozzles for stealth purposes to retain the advantages of the grid structure (shielding the engine cavity, enhancing rigidity) while solving the inherent problem of self-heating, thus effectively improving stealth capabilities. Furthermore, by combining the regenerator (liquid hydrogen heat exchange tubes) with the supporting grid, the liquid hydrogen cools the grid while simultaneously recovering high-quality waste heat from the exhaust gases. This recovered heat can be returned to the engine for recycling, improving the performance of the Brayton Navier-Stokes engine. The thermal efficiency of the cycle or related thermodynamic cycle helps reduce fuel consumption or increase available power, which is of great significance for hydrogen-powered aero engines that pursue long flight time and high economy. Compared with the traditional regenerator arranged separately in the flow channel, the embodiment of this invention integrates the heat exchange function into the support grid structure that is already required. This integrated design significantly reduces the projected area and volume of the heat exchange structure in the gas flow channel, thereby greatly reducing the additional aerodynamic drag (manifested as a higher total pressure recovery coefficient and thrust coefficient), while avoiding the weight cost of additional support structures and cantilever arrangements, achieving a high degree of structural integration and lightweighting. The proposed liquid hydrogen flow control method is based on real-time monitoring parameters (T, Q). 气 , T wall ) and dynamic task requirements (Q 热 , T max By solving the heat balance equation, the minimum required flow rate (Q) that satisfies both the regeneration and cooling constraints is calculated. 氢,req This ensures that the grid temperature does not exceed the stealth allowable limit under any operating condition, avoids providing excessive and unnecessary coolant hydrogen under low heat load conditions, improves the utilization efficiency of valuable liquid hydrogen fuel, and can automatically adjust the control strategy according to changes in engine operating conditions and flight profile; through data interaction of three sub-models (T... wall(L) transmission), truly reflects the coupling effect between heat-fluid-solid, making the prediction results more accurate; by constructing a comprehensive evaluation function, it is possible to simultaneously and quantitatively weigh the four key indicators of regenerative capacity, stealth performance (wall temperature), thrust performance and structural weight, find the global optimal solution at the system level, rather than the local optimal of a single performance, reduce the number of physical prototype trials and test rounds, reduce R&D costs, and avoid performance conflicts in the early stages of design, shorten the development cycle of high-performance nozzles, and improve design quality and reliability. This design method can provide a theoretical basis and control law design basis for active variable length / adjustable grids. By optimizing different optimal lengths for different typical flight stages (such as high-speed cruise emphasizing efficiency and dogfight maneuver emphasizing thrust) and achieving adaptive adjustment in flight, the nozzle can always maintain the optimal comprehensive performance throughout the entire flight envelope.

[0105] The above description is merely a specific embodiment of the present invention and should not be construed as limiting the scope of the invention. Therefore, substitutions of equivalent components, or equivalent changes and modifications made within the scope of protection of the present invention, should still fall within the scope of the present invention. Furthermore, the technical features, technical features and technical solutions, and technical solutions in the present invention can be freely combined and used.

Claims

1. A method for controlling the liquid hydrogen flow rate in a liquid hydrogen heat exchange assembly for a regenerative nozzle, characterized in that, The regenerative nozzle includes: The components include a circular-to-square section (1), a straight section (2), a single-sided section (3), an angled grid (4), and a liquid hydrogen heat exchange assembly. The round-to-square section (1), the straight section (2), and the single-sided section (3) are connected sequentially in the direction of navigation, and multiple angled grilles (4) are connected to the single-sided section (3) in the direction of navigation and are spaced apart; The liquid hydrogen heat exchange assembly includes a liquid hydrogen heat exchange tube (5), a liquid hydrogen inlet (6), and a liquid hydrogen outlet (7). The liquid hydrogen heat exchange tube (5) is connected to the interior of the wall of each angled grid (4) through the interior of the straight section (2) and the single-sided section (3), and forms a set of liquid hydrogen heat exchange loops inside the wall of each angled grid (4). The liquid hydrogen inlet (6) and the liquid hydrogen outlet (7) are respectively connected to the supply port and the recovery port of the liquid hydrogen supply flow path. Liquid hydrogen is injected into the liquid hydrogen heat exchange tube (5) from the liquid hydrogen inlet (6), and flows through each set of liquid hydrogen heat exchange circuits before flowing out from the liquid hydrogen outlet (7) through the liquid hydrogen heat exchange tube (5); The control method includes the following steps: Real-time acquisition of total gas temperature T and gas flow rate Q at the nozzle inlet section 气 and the wall temperature T of the angled grid (4) wall And as a detection parameter, based on the current engine operating conditions or preset task profile, determine the current required regenerative load Q. 热 The maximum permissible wall temperature T required for infrared suppression max And as a requirement for judgment; Based on the detection parameters and the determination requirements, a heat balance equation is constructed. Using the heat balance equation as the core constraint, the regenerative load Q that satisfies the requirement is calculated. 热 And the wall temperature T wall Not exceeding the maximum permissible wall temperature T max Minimum required liquid hydrogen flow rate Q 氢,req ; According to the minimum required liquid hydrogen flow rate Q 氢,req A control command is generated, which is used to adjust the opening of the control valve in the liquid hydrogen supply pipeline so that the actual liquid hydrogen flow rate reaches the minimum required liquid hydrogen flow rate Q. 氢,req .

2. The control method according to claim 1, characterized in that, Based on the detection parameters and the determination requirements, a heat balance equation is constructed. Using the heat balance equation as the core constraint, the regenerative load Q that satisfies the requirement is calculated. 热 And the wall temperature T wall Not exceeding the maximum permissible wall temperature T max Minimum required liquid hydrogen flow rate Q 氢,req ,include: The heat Q absorbed by liquid hydrogen inside the heat exchanger tubes. 吸收 The calculation formula, where, ,in, The specific heat capacity of liquid hydrogen, This represents the temperature rise of liquid hydrogen during the heat exchange process; Constructing the heat Q recovered from the gas 回收 The calculation formula, where, , For heat exchange efficiency, For the specific heat capacity of the gas, The total temperature of the combustion gas at the nozzle inlet section; The heat Q absorbed by the liquid hydrogen inside the heat exchange tubes 吸收 With the heat Q recovered from the gas 回收 Equality is used as a condition to construct the heat balance equation; Construct a system that satisfies the regenerative load Q 热 The objective equation is to make the heat Q recovered from the gas combustion gas... 回收 ≥The regenerative load Q 热 ; Based on the aforementioned heat balance equation and the objective equation, the fundamental value of liquid hydrogen flow rate Q is calculated. 氢,base ; The maximum permissible wall temperature T max The basic value of liquid hydrogen flow rate Q 氢,base After correction, the minimum required liquid hydrogen flow rate Q is obtained. 氢,req .

3. The control method according to claim 2, characterized in that, The maximum permissible wall temperature T max The basic value of liquid hydrogen flow rate Q 氢,base After correction, the minimum required liquid hydrogen flow rate Q is obtained. 氢,req ,include: The calculated basic value of liquid hydrogen flow rate Q 氢,base Substituting into the aforementioned heat balance equation, the predicted steady-state wall temperature T is obtained by reverse calculation. wall_est ; Compare the steady-state wall temperature T wall_est With the maximum allowable wall temperature T max Size; If T wall_est ≤T max Let the minimum required liquid hydrogen flow rate Q be 氢,req Equal to the basic value of liquid hydrogen flow rate Q 氢,base ; If T wall_est >T max Therefore, with the goal of increasing cooling intensity, the heat balance equation is resolved to satisfy T. wall_est ≤T max The base value of liquid hydrogen flow rate Q is adjusted to meet the new constraints. 氢,base The minimum required liquid hydrogen flow rate Q is obtained. 氢,req .

4. A design method for an angled grille, wherein the grille length L of the angled grille (4) according to claim 1 is designed using the design method, characterized in that, Includes the following steps: Obtain the design input parameters for the regenerative nozzle, wherein the design input parameters include the structure and dimensions of the regenerative nozzle and the inlet gas flow rate Q. 气 The total gas temperature T at the nozzle inlet section, and the supply pressure and initial temperature of liquid hydrogen; Based on the design input parameters, a coupled analysis model is constructed to predict the change of nozzle performance with the grid length L of the angled grid (4), wherein the coupled analysis model is used to input the inlet gas flow rate Q of the nozzle. 气 The total gas temperature T at the nozzle inlet section and the supply pressure and initial temperature of the liquid hydrogen are used as variables, with the grid length L as the independent variable, to output the predicted total system heat transfer Q. rec (L) Predicted average grid wall temperature T wall (L) Predicted nozzle thrust coefficient C f (L) and the predicted grid subsystem quality M grid (L); The core performance indicator constraints are determined based on the mission requirements of the aircraft. These constraints include the minimum required heat recovery rate Q. 热_min The maximum permissible wall temperature T of the grille wall_max and the minimum thrust coefficient C required to be guaranteed f_min ; Q rec (L)≥Q 热_min And T wall (L)≤T wall_max And C f (L)≥C f_min As a constraint, the coupled analysis model is solved, and the final design grid length L is determined from the set of all grid length solutions that satisfy the constraints. design .

5. The design method according to claim 4, characterized in that, Based on the design input parameters, a coupled analysis model is constructed to predict the nozzle performance as a function of the grid length L of the angled grid (4), including: A regenerative and thermodynamic analysis sub-model is constructed, which is used to characterize the relationship between the grid length L and the total heat transfer Q of the system. rec (L), Average wall temperature of the grille T wall The quantitative relationship between (L) is established, and the average wall temperature T of the grid is output. wall (L) and the total heat exchange of the system Q rec (L); An aerodynamic performance analysis sub-model is constructed, which is used to characterize the relationship between the grid length L and the nozzle thrust coefficient C. f The quantitative relationship between (L) is given, and the nozzle thrust coefficient C is output. f (L); A structural quality analysis sub-model is constructed, which is used to characterize the relationship between the grid length L and the grid subsystem mass M. grid The quantitative relationship between (L) is established, and the mass M of the grid subsystem is output. grid (L); The regeneration and thermodynamic analysis sub-model, the aerodynamic performance analysis sub-model, and the structural quality analysis sub-model are coupled by data interaction to generate a coupled analysis model.

6. The design method according to claim 5, characterized in that, Constructing a regenerative and thermodynamic analysis sub-model, including: Basic data is extracted and obtained from the design input parameters, including the total gas temperature T at the nozzle inlet section and the gas flow rate Q at the nozzle inlet. 气 The supply pressure and initial temperature of the liquid hydrogen and the thermal conductivity λ of the material of the angled grid (4); Using the grid length L as the driving variable, a parametric geometric expression for the regenerative nozzle is generated. Based on this parametric geometric expression, geometric feature quantities associated with the grid length L are calculated, wherein the geometric feature quantities include the grid wetted area A. wet (L) and the hydraulic diameter of the internal flow channel D h (L); Based on the aforementioned basic data and geometric features, a set of steady-state conjugate heat transfer control equations is constructed to characterize the convective heat transfer between the gas and the grid wall, the internal heat conduction of the grid solid, and the convective heat transfer between the liquid hydrogen and the channel wall. The steady-state conjugate heat transfer control equations are solved using numerical methods to obtain temperature field and heat flow field distribution data corresponding to the grid length L; The temperature field and heat flow field distribution data are post-processed, and the total heat transfer Q of the system is obtained by integration calculation. rec (L), and the average wall temperature T of the grid is obtained by area-weighted averaging. wall (L); Output the total heat exchange of the system, Q rec (L) and the average wall temperature T of the grille wall (L).

7. The design method according to claim 5, characterized in that, Constructing a sub-model for aerodynamic performance analysis, including: The gas physical properties and nozzle inlet flow conditions are extracted from the design input parameters and used as set parameters. The average wall temperature T of the grid output by the regenerative and thermodynamic analysis sub-model is then used. wall (L) serves as the wall thermal boundary condition for the angled grid (4); Using the grid length L as the driving variable, a parametric geometric model of the internal flow channel containing the angled grid (4) is generated; Based on the parametric geometric model, a computational fluid dynamics mesh is generated that updates with the grid length L. Then, aerodynamic geometric features associated with the grid length L are extracted from the computational fluid dynamics mesh. These aerodynamic geometric features include the grid wetted area A. wet (L) and grid wet area A wet (L) Projected area in the direction of flow; Based on the set parameters, the wall thermal boundary conditions, and the aerodynamic geometric characteristics, a set of viscous fluid dynamics control equations including the laws of conservation of mass, momentum, and energy is constructed. The viscous fluid dynamics control equations are solved using numerical methods to obtain convergent flow field data corresponding to the grid length L; The convergent flow field data is post-processed, and the nozzle thrust coefficient C, as a function of the grid length L, is calculated using the momentum flux and pressure at the nozzle exit section. f (L); Output the nozzle thrust coefficient C f (L).

8. The design method according to claim 5, characterized in that, Construct a sub-model for structural quality analysis, including: The material density ρ, elastic modulus E, and coefficient of thermal expansion α of the grid structure are extracted from the design input parameters and used as material property data. The average wall temperature T of the grid output by the regenerative and thermodynamic analysis sub-model is then used. wall (L) is set as the thermal load condition acting on the angled grid (4); Using the grid length L as the driving variable, a parameterized structural geometric model of the oblique grid (4) is generated; Based on the parametric structural geometry model, a finite element analysis mesh is generated that updates with the grid length L, and structural geometric attribute data associated with the grid length L is calculated. The structural geometric attribute data includes the grid cross-sectional area A. cs (L) and the moment of inertia of the section I(L); Based on the material property data, the thermal load conditions, and the structural geometric property data, and according to the geometric volume V(L) corresponding to the material density ρ and the grid length L, the predicted mass M of the grid subsystem is calculated. grid (L); Output the mass M of the grid subsystem grid (L).

9. The design method according to claim 4, characterized in that, Q rec (L)≥Q 热_min And T wall (L)≤T wall_max And C f (L)≥C f_min As a constraint, the coupled analysis model is solved, and the final design grid length L is determined from the set of all grid length solutions that satisfy the constraints. design ,include: Using the coupling analysis model, sampling or continuous analysis is performed within the domain of the grid length L to filter out all the ranges of values ​​of the grid length L that satisfy the constraints, thus forming a feasible solution domain Ω. A comprehensive evaluation function F(L) is constructed based on the feasible solution domain Ω. This function F(L) is used to quantitatively evaluate the comprehensive performance of any feasible solution for the grid length L, where L∈Ω. The comprehensive evaluation function F(L) is based on the total heat transfer Q of the system. rec (L), the average wall temperature T of the grille wall (L), the nozzle thrust coefficient C f (L) and the mass M of the grid system grid (L) After weighted combination, the total heat exchange of the system Q is constructed. rec (L) and the nozzle thrust coefficient C f The weight of (L) is set to a positive weight, and the average wall temperature T of the grid is... wall (L) and the mass M of the grid system grid The weight of (L) is set to a negative weight; Within the feasible solution domain Ω, a numerical optimization algorithm is executed to maximize the value of the comprehensive evaluation function F(L) within the domain Ω. This algorithm yields the optimal solution that maximizes the comprehensive evaluation function F(L), and the optimal solution is used as the final design grid length L. design .

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