Water mist phase change cooling method applied to turbine blade of hydrogen combustion gas turbine

Abstract

The invention discloses a water mist phase change cooling method applied to turbine blades of a hydrogen-fired gas turbine, which comprises the following steps of: modifying hole pattern parameters of film holes to obtain different structures of the turbine blades of the hydrogen-fired gas turbine, and carrying out geometric modeling and grid division; meanwhile, on the basis of continuous phase and discrete phase control equations and a Lagrange trajectory calculation method, gas, liquid, grain and heat multi-physical field mathematical models coupled to the two sides of the blade are built, different water mist droplet diameters and water mist droplet concentrations are set at a secondary flow inlet, and solving is conducted on the basis of the mathematical models; and obtaining the comprehensive cooling efficiency and the total pressure loss coefficient of the middle section of the turbine blade of the hydrogen-fired gas turbine under different sample points. According to the invention, the problem of overlarge resistance loss caused by unreasonable structural design of the air film holes can be effectively avoided, effective utilization of cooling air is ensured, unnecessary energy loss is reduced, and the efficiency loss of the turbine is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of aviation engines, and in particular relates to a water mist phase change cooling method for turbine blades of hydrogen-fired gas turbines. Background Art

[0002] Increasing the gas temperature before the turbine is a direct and effective means of improving gas turbine efficiency and output power. Currently, the gas temperature before the turbine of advanced G / H-class gas turbines exceeds 1773K. Based on gas turbine development trends, this temperature is expected to rise further. In the future, the gas temperature of advanced, high-efficiency, zero-emission hydrogen-fired gas turbines will reach 2000K. Because the gas temperature far exceeds the melting point of the metal material of the turbine blades (1223K), efficient cooling measures are necessary to ensure sufficient safety, reliability, and service life of the turbine blades in high-temperature service environments.

[0003] Numerous numerical simulations and experimental studies have been conducted on the cooling characteristics of future hydrogen-fired gas turbines. The effects of parameters such as mainstream gas temperature, film hole angle, blowing ratio, blade curvature spray volume, and droplet diameter on film cooling efficiency were analyzed under laboratory and typical gas turbine operating conditions. The results show that under actual turbine operating conditions, the application of water mist cooling technology can improve film cooling efficiency by 20%. This is a highly efficient cooling technology that uses water vapor as the coolant at the combustion chamber outlet. Water mist / water vapor phase change cooling technology improves the heat transfer capacity of water vapor by adding water mist to the cooling steam to form a two-phase flow of air and mist. Compared with traditional cooling, it can significantly reduce cooling air consumption. Professor Wang Ting and others from the Center for Energy Conversion and Conservation at the University of New Orleans have conducted basic research on water mist / air film cooling, water mist / water vapor convection cooling, impingement cooling and convection-air film cooling. Professor Shi Xiaojun's team from the Jiaotong University has also conducted basic research on steam mist and steam dual-fluid turbine blade cooling technology, and has achieved remarkable research results. However, the theoretical model of phase change cooling for the application of water mist cooling technology in the field of turbine blades is still relatively lacking, and it is still some distance away from engineering application. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the present invention provides a water mist phase change cooling method for hydrogen-fired gas turbine blades. A test point sample space is constructed based on the structural parameters and water mist parameters of the hydrogen-fired gas turbine blades. Different hydrogen-fired gas turbine blade structures are obtained by modifying the hole parameters of the film hole, and geometric modeling and meshing are performed. Simultaneously, a mathematical model of coupled gas, liquid, particle, and thermal multi-physics fields on both sides of the blade is constructed based on the continuous phase and discrete phase control equations and the Lagrangian trajectory calculation method. Different water mist droplet diameters and concentrations are set at the secondary flow inlet, and a solution is performed based on this mathematical model to obtain the mid-section comprehensive cooling efficiency and total pressure loss coefficient of the hydrogen-fired gas turbine blade at different sample points. A proxy model is established between the mid-section comprehensive cooling efficiency and total pressure loss coefficient of the hydrogen-fired gas turbine blade structure and the film hole parameters and water mist parameters. The numerical simulation is then repeated with additional test sample points, which are then compared against the proxy model's predictions. If the proxy model's accuracy falls short of the set target, the number of sample points in the sample space is increased and the proxy model is rebuilt until the proxy model's accuracy meets the design requirements. This invention effectively avoids the problem of excessive drag losses caused by improperly designed film pore structures, ensuring efficient use of cooling air, reducing unnecessary energy losses, and minimizing turbine efficiency losses.

[0005] The technical solutions adopted by the present invention to solve the technical problems are as follows:

[0006] Step 1: Construct a test point sample space based on the structural parameters and water spray parameters of hydrogen-fired gas turbine blades;

[0007] Step 2: Modify the hole parameters of the film hole to obtain different hydrogen-fired gas turbine blade structures, and perform geometric modeling and meshing.

[0008] Step 3: Construct a mathematical model of the coupled gas, liquid, particle, and thermal multi-physics fields on both sides of the blade based on the continuous phase and discrete phase governing equations and the Lagrangian trajectory calculation method;

[0009] Step 4: Different water mist droplet diameters and concentrations are set at the secondary flow inlet and solved based on the multi-physics mathematical model to obtain the mid-section comprehensive cooling efficiency and total pressure loss coefficient of the hydrogen-fired gas turbine turbine blade at different sample points;

[0010] Step 5: Establish a proxy model between the cross-section comprehensive cooling effect and total pressure loss coefficient of the hydrogen-fired gas turbine blade structure and the film hole parameters and water mist parameters;

[0011] Step 6: Add test sample points for numerical simulation and verify them with the prediction results of the proxy model. If the accuracy of the proxy model is less than the set index, increase the number of sample points in the sample space and rebuild the proxy model until the accuracy of the proxy model meets the design requirements.

[0012] Step 7: Taking the total pressure loss coefficient greater than or equal to the limit value and the highest comprehensive cooling efficiency as the final optimization goals, a multi-objective optimization algorithm is used to find the optimal solution to obtain the design values ​​of the film hole parameters of the hydrogen-fired gas turbine turbine blade structure and the design values ​​of the water mist droplet parameters adapted to the structure that meet the optimization goals.

[0013] Preferably, the step 1 is specifically:

[0014] Step 1-1: Obtain the film hole type, hole diameter, and hole inclination parameters of the hydrogen-fired gas turbine blade structure;

[0015] Step 1-2: Based on the parameters obtained in step 1 and the actual size of the hydrogen-fired gas turbine blade, a three-dimensional model of the hydrogen-fired gas turbine blade is established;

[0016] Step 1-3: The diameter of the water mist droplets in the cooling air, the concentration of the water mist droplets in the cooling air, and the pore type, pore diameter, and pore inclination of the air film hole are used as the optimized design variables, and the upper and lower ranges of the design variables are given.

[0017] Step 1-4: Determine the heat transfer characteristics of the hydrogen-fired gas turbine blades and the flow resistance loss characteristics of the cooling structure as the optimization objectives, change the optimized design variables and the upper and lower ranges of the design variables selected in step 1-3, and construct the experimental sample space.

[0018] Preferably, the comprehensive cooling efficiency is defined as:

[0019]

[0020] Among them, T ∞ is the mainstream gas temperature, T w is the wall temperature, T c The air conditioning temperature.

[0021] Preferably, the total pressure loss coefficient is defined as:

[0022]

[0023] in, is the total pressure at the turbine guide vane inlet, is the total pressure at the turbine guide vane outlet, and P2 is the static pressure at the turbine guide vane outlet.

[0024] Preferably, the step 5 is specifically as follows:

[0025] The channel model established based on the film hole type, pore size, and hole inclination parameters of each test point was numerically calculated to adapt different water mist droplet parameters at the cooling air inlet, and the multi-objective optimization parameter values ​​at different sample points were obtained. Based on the sample space, a proxy model was established between the multi-objective optimization parameter values ​​and the diameter of the water mist droplets in the cooling air, the concentration of the water mist droplets in the cooling air, and the film hole type, pore size, and hole inclination parameters.

[0026] Preferably, the multi-objective optimization algorithm is NSGA-II non-dominated genetic algorithm.

[0027] Preferably, the multi-objective optimization parameter values ​​obtained at different sample points are specifically:

[0028] Step 5-1: Model the structure and geometry of the hydrogen-fired gas turbine blades.

[0029] According to the design geometric parameters of the film holes, the film hole structure was generated using the 3D modeling software NX12.0, and then the film hole structure was arranged on the blade surface of the hydrogen-fired gas turbine turbine blade structure.

[0030] Step 5-2: Meshing the cascade flow field fluid domain and the structural solid domain of the hydrogen-fired gas turbine blade structure, performing local meshing near the wall of the fluid domain, and setting a boundary layer;

[0031] Step 5-3: Use the Reynolds average method and couple the turbulence model to solve the mass, momentum, and energy conservation equations for the continuous and discrete phases, thereby obtaining the flow field and blade temperature field characteristics of the hydrogen-fired gas turbine blade cascade under different characteristic geometric parameters;

[0032] Step 5-4: Post-process the obtained numerical calculation results to obtain multi-objective optimization parameter values ​​of the hydrogen-fired gas turbine turbine blade structure at different sample points.

[0033] The beneficial effects of the present invention are as follows:

[0034] 1. By optimizing the water mist phase change cooling method, specifically parameters such as droplet size and concentration, more complete and uniform cooling of hydrogen-fired gas turbine blades is achieved, resolving the issues of insufficient and uneven cooling found in existing cooling methods. Smaller droplets, due to their larger surface area, evaporate more quickly, removing more heat and thus improving cooling efficiency.

[0035] 2. By adjusting structural parameters such as the inclination angle of the air film hole and finely controlling the diameter and concentration of the water mist droplets, the present invention can effectively avoid the problem of excessive resistance loss caused by unreasonable design of the air film hole structure while ensuring the cooling effect, thereby ensuring the effective use of cooling air, reducing unnecessary energy loss, and reducing the efficiency loss of the turbine. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The present invention provides a display model of a hydrogen-fired gas turbine turbine blade.

[0037] Figure 2 The present invention provides a cross-sectional display model of a hydrogen-fired gas turbine turbine blade.

[0038] Figure 3 The present invention is a flow chart of a water mist phase change cooling method for hydrogen-fired gas turbine blades.

[0039] Figure 4 It is the comprehensive cooling efficiency value of different water mist concentration (DC) and water mist diameter (DSD) when the hole type in the present invention is a forward-inclined fan-shaped hole, the air film hole inclination angle is 300, and the hole diameter is 2.7mm. DETAILED DESCRIPTION

[0040] The present invention will be further described below with reference to the accompanying drawings and examples.

[0041] The present invention provides a water mist phase change cooling method for hydrogen-fired gas turbine blades, relates to the technical field of turbine blade cooling of aircraft engines, and solves the problems of insufficient and uneven cooling of existing gas turbine blades.

[0042] In the application of water mist phase change cooling methods, droplet size and droplet concentration are key parameters affecting cooling efficiency. Droplet size determines its trajectory in the air, residence time, and evaporation rate, which in turn affects the effectiveness of heat transfer. Smaller droplets, due to their larger specific surface area, generally evaporate faster and remove more heat. However, an excessively small particle size may cause some droplets to escape with the airflow without contacting the heated surface, thereby reducing the overall cooling effect. Droplet concentration, on the other hand, refers to the number of droplets per unit volume—that is, the ratio of the mass flow rate of water mist droplets to the mass flow rate of the secondary flow. It is directly related to the contact frequency and contact area between the cooling medium and the cooled object, and is crucial to improving cooling capacity. Furthermore, the pore shape parameters of the film hole also have some influence. For example, different pore shapes, pore sizes, and pore inclination angles can all lead to variations in the film coverage effect.

[0043] like Figure 1The heat transfer and flow resistance characteristics of hydrogen-fired gas turbine blades are mainly expressed by the comprehensive cooling effect and total pressure loss coefficient of the mid-section. The comprehensive cooling effect and total pressure loss coefficient are closely related to the water mist droplet diameter, water mist droplet concentration and the hole type parameters of the film hole. In order to make full use of the water mist phase change method to improve the surface convection heat transfer effect of the turbine blades, and at the same time to avoid the problems of excessive resistance loss, lack of cold air outflow and secondary flow blowing caused by unreasonable setting of the geometric parameters and number of the film hole structure, the main cooling structure in the turbine blade, a water mist phase change cooling method applied to hydrogen-fired gas turbine blades needs to be proposed.

[0044] A water mist phase change cooling method for hydrogen-fired gas turbine blades is implemented as follows: first, a test point sample space is constructed based on the structural parameters and water mist parameters of the hydrogen-fired gas turbine blades. Different hydrogen-fired gas turbine blade structures are obtained by modifying the hole parameters of the air film holes, and geometric modeling and meshing are performed. At the same time, a mathematical model of the coupled gas, liquid, particle, and thermal multi-physics fields on both sides of the blade is constructed based on the continuous phase and discrete phase control equations and the Lagrangian trajectory calculation method. Different water mist droplet diameters and water mist droplet concentrations are set at the secondary flow inlet and solved based on this mathematical model to obtain the comprehensive cooling effect and total pressure loss coefficient of the mid-section of the hydrogen-fired gas turbine blade at different sample points.

[0045] A proxy model is established to correlate the cross-sectional comprehensive cooling efficiency and total pressure loss coefficient with the film hole parameters and water mist parameters for hydrogen-fired gas turbine blade structures. Numerical simulations are then performed with additional test sample points, and the results are verified against the proxy model's predictions. If the proxy model's accuracy falls short of the specified threshold, the number of sample points is increased and the proxy model is rebuilt until its accuracy meets the design requirements. Furthermore, with the total pressure loss coefficient being greater than or equal to a limit and the comprehensive cooling efficiency being maximized as the ultimate optimization goals, a multi-objective optimization algorithm is employed to determine the film hole parameter design values ​​and water mist droplet parameter design values ​​that meet these optimization objectives. This method maximizes the advantages of water mist phase change cooling in hydrogen-fired gas turbine blade structures, enhancing overall convective heat transfer and thermal conductivity, and achieving efficient water mist phase change cooling design and efficient utilization of cooling air for hydrogen-fired gas turbine blade structures.

[0046] Example:

[0047] This embodiment is a specific implementation step for a water mist phase change cooling method applied to hydrogen-fired gas turbine blades, that is, by adjusting the diameter of the water mist droplets in the cold air, the concentration of the water mist droplets in the cold air, and the parameters of the air film holes, etc. The air film holes are located in the second and third rows of holes on the pressure side of the blade and the second and third rows of holes on the suction side. The implementation flow chart of a water mist phase change cooling method applied to hydrogen-fired gas turbine blades is shown as follows: Figure 3 As shown, the following steps are included:

[0048] Step 1: Obtain basic geometric parameters: Obtain the film hole type, aperture, and inclination parameters of the hydrogen-fired gas turbine blade structure. Build a three-dimensional model of the hydrogen-fired gas turbine blade based on these geometric parameters and the actual dimensions of the hydrogen-fired gas turbine blade. Use the diameter and concentration of water mist droplets in the cooling air, as well as the film hole type, aperture, and inclination, as optimization design variables, and assign upper and lower ranges to these design variables. Determine the heat transfer characteristics and cooling structure flow resistance loss characteristics of the hydrogen-fired gas turbine blade as the optimization objectives. By varying the selected design variables and the range of variation for the water mist droplet-related parameters, a test sample space is constructed.

[0049] Step 2: Use the comprehensive cooling efficiency and total pressure loss coefficient of the cross-section of the hydrogen-fired gas turbine blade as the multi-objective optimization function.

[0050] The overall cooling efficiency is defined as:

[0051]

[0052] Among them, T ∞ is the mainstream gas temperature, T w is the wall temperature, T c The air conditioning temperature.

[0053] The total pressure loss coefficient is defined as:

[0054]

[0055] in, is the total pressure at the turbine guide vane inlet, is the total pressure at the turbine guide vane outlet, and P2 is the static pressure at the turbine guide vane outlet.

[0056] Step 3: Numerical calculations are performed on the channel model established based on the film hole type, pore diameter, and hole inclination parameters at each test point to adapt different water mist droplet parameters at the cold air inlet, and the multi-objective optimization parameter values ​​at different sample points are obtained. Based on the sample space, a proxy model is established between the multi-objective optimization parameter values ​​and the diameter of the water mist droplets in the cold air, the concentration of the water mist droplets in the cold air, and the film hole type, pore diameter, and hole inclination parameters;

[0057] (1) Geometric modeling of the turbine blade structure of hydrogen-fired gas turbine.

[0058] According to the design geometric parameters of the film hole, the film hole structure is generated using the 3D modeling software NX12.0, and then the structure array is arranged on the blade surface of the hydrogen gas turbine turbine blade structure (such as Figure 2 shown).

[0059] (2) The fluid domain and structural solid domain of the cascade flow field of the hydrogen-fired gas turbine turbine blade structure are meshed, and local encryption is performed in the near-wall area of ​​the fluid domain and a boundary layer is set.

[0060] (3) The Reynolds average-based method and coupled turbulence model are used to solve the mass, momentum, and energy conservation equations of the continuous and discrete phases, thereby obtaining the flow field and blade temperature field characteristics of the hydrogen-fired gas turbine blade cascade under different characteristic geometric parameters (sample points).

[0061] (4) The numerical calculation results are post-processed to obtain the multi-objective optimization parameter values ​​of the hydrogen-fired gas turbine blade structure at different sample points (including the comprehensive cooling efficiency of the mid-section and the total pressure loss coefficient).

[0062] Step 4: By adding test sample points, performing numerical simulation and comparing the results with those predicted by the proxy model, the numerical accuracy of the proxy model is verified;

[0063] If the calculation result of the proxy model does not reach the set accuracy, the number of sample points is increased and the proxy model is rebuilt until the accuracy of the proxy model meets the design requirements.

[0064] Step 5: When the total pressure loss coefficient is greater than or equal to the limit value and the comprehensive cooling efficiency of the mid-section reaches the highest optimization goal, the agent model and multi-objective optimization algorithm (such as the NSGA-II non-dominated genetic algorithm) are used to search for the optimal film hole parameter design values ​​and water mist droplet parameter values ​​of the hydrogen-fired gas turbine turbine blade that meet the optimization goals.

[0065] like Figure 4 It is the comprehensive cooling efficiency value of different water mist concentration (DC) and water mist diameter (DSD) when the hole type in the present invention is a forward-inclined fan-shaped hole, the air film hole inclination angle is 300, and the hole diameter is 2.7mm.

Claims

1. A water mist phase change cooling method for hydrogen-fired gas turbine blades, characterized in that: The steps include: Step 1: Construct a test point sample space based on the structural parameters and water spray parameters of hydrogen-fired gas turbine blades; Step 2: Modify the hole parameters of the film hole to obtain different hydrogen-fired gas turbine blade structures, and perform geometric modeling and meshing. Step 3: Construct a mathematical model of the coupled gas, liquid, particle, and thermal multi-physics fields on both sides of the blade based on the continuous phase and discrete phase governing equations and the Lagrangian trajectory calculation method; Step 4: Different water mist droplet diameters and concentrations are set at the secondary flow inlet and solved based on the multi-physics mathematical model to obtain the mid-section comprehensive cooling efficiency and total pressure loss coefficient of the hydrogen-fired gas turbine turbine blade at different sample points; Step 5: Establish a proxy model between the cross-section comprehensive cooling effect and total pressure loss coefficient of the hydrogen-fired gas turbine blade structure and the film hole parameters and water mist parameters; Step 6: Add test sample points for numerical simulation and verify them with the prediction results of the proxy model. If the accuracy of the proxy model is less than the set index, increase the number of sample points in the sample space and rebuild the proxy model until the accuracy of the proxy model meets the design requirements; Step 7: Taking the total pressure loss coefficient greater than or equal to the limit value and the highest comprehensive cooling efficiency as the final optimization goals, a multi-objective optimization algorithm is used to find the optimal solution to obtain the design values ​​of the film hole parameters of the hydrogen-fired gas turbine turbine blade structure and the design values ​​of the water mist droplet parameters adapted to the structure that meet the optimization goals.

2. The water mist phase change cooling method for hydrogen-fired gas turbine blades according to claim 1, characterized in that: The step 1 is specifically as follows: Step 1-1: Obtain the film hole type, hole diameter, and hole inclination parameters of the hydrogen-fired gas turbine blade structure; Step 1-2: Based on the parameters obtained in step 1 and the actual size of the hydrogen-fired gas turbine blade, a three-dimensional model of the hydrogen-fired gas turbine blade is established; Step 1-3: The diameter of the water mist droplets in the cooling air, the concentration of the water mist droplets in the cooling air, and the air film hole shape, hole diameter, and hole inclination are used as the optimization design variables, and the upper and lower ranges of the design variables are given; Step 1-4: Determine the heat transfer characteristics of the hydrogen-fired gas turbine blades and the flow resistance loss characteristics of the cooling structure as the optimization objectives, change the optimized design variables and the upper and lower ranges of the design variables selected in step 1-3, and construct the experimental sample space.

3. The water mist phase change cooling method for hydrogen-fired gas turbine blades according to claim 2, characterized in that: The comprehensive cooling efficiency is defined as: Among them, T ∞ is the mainstream gas temperature, T w is the wall temperature, T c The air conditioning temperature.

4. The water mist phase change cooling method for hydrogen-fired gas turbine blades according to claim 3, characterized in that: The total pressure loss coefficient is defined as: in, is the total pressure at the turbine guide vane inlet, is the total pressure at the turbine guide vane outlet, and P2 is the static pressure at the turbine guide vane outlet.

5. The water mist phase change cooling method for hydrogen-fired gas turbine blades according to claim 4, characterized in that: The step 5 is specifically as follows: The channel model established based on the film hole type, hole diameter, and hole inclination parameters of each test point is numerically calculated to adapt to different water mist droplet parameters at the cold air inlet, and the multi-objective optimization parameter values ​​at different sample points are obtained; According to the sample space, a proxy model is established between the multi-objective optimization parameter values ​​and the diameter of water mist droplets in the cooling air, the concentration of water mist droplets in the cooling air and the air film hole shape, hole diameter and hole inclination parameters.

6. The water mist phase change cooling method for hydrogen-fired gas turbine blades according to claim 5, characterized in that: The multi-objective optimization algorithm is the NSGA-II non-dominated genetic algorithm.

7. The water mist phase change cooling method for hydrogen-fired gas turbine blades according to claim 6, characterized in that: The multi-objective optimization parameter values ​​obtained at different sample points are specifically: Step 5-1: Conduct geometric modeling of the hydrogen-fired gas turbine blade structure; According to the design geometric parameters of the film holes, the film hole structure was generated using the 3D modeling software NX12.0, and then the film hole structure was arranged on the blade surface of the hydrogen-fired gas turbine turbine blade structure. Step 5-2: Meshing the cascade flow field fluid domain and the structural solid domain of the hydrogen-fired gas turbine blade structure, performing local meshing near the wall of the fluid domain, and setting a boundary layer; Step 5-3: Use the Reynolds average method and couple the turbulence model to solve the mass, momentum, and energy conservation equations for the continuous and discrete phases, thereby obtaining the flow field and blade temperature field characteristics of the hydrogen-fired gas turbine blade cascade under different characteristic geometric parameters; Step 5-4: Post-process the obtained numerical calculation results to obtain multi-objective optimization parameter values ​​of the hydrogen-fired gas turbine turbine blade structure at different sample points.

Images