Porous air film cooling meshless calculation method

Abstract

The invention belongs to the technical field of numerical calculation of porous air film cooling, and provides a porous air film cooling meshless calculation method, which comprises the following steps of: processing an air film hole inlet into a pressure outlet boundary condition, processing an air film hole outlet into a flow inlet boundary condition, and giving a negative heat source to a wall surface near the air film hole inlet and outlet; the heat absorption amount is equal to the total heat exchange amount of cold air passing through the wall surface of the air film hole; the hot side wall surface and the cold side wall surface of the air film hole are coupling heat exchange boundaries; the air film hole inlet and outlet flow field parameters are obtained through an air film hole in-hole flow heat exchange simplified algorithm, and the air film hole inlet and outlet flow parameters and the three-dimensional flow field are subjected to coupling iteration solution. According to the method, no grid is drawn for the flow field in the air film hole and the interior of the solid wall surface, only wall surface grids are drawn for the inlet and the outlet of the air film hole, the grid quantity and the calculation resource consumption are greatly reduced, and meanwhile, the prediction precision of the flow characteristic and the air film cooling heat exchange characteristic of the air film hole is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of numerical calculation of porous air film cooling, and in particular relates to a gridless calculation method for porous air film cooling. Background Art

[0002] Film cooling technology with high cooling effect is widely used in the cooling technology of high-temperature components in modern aircraft engines, gas turbines and other equipment. Film cooling achieves the effect of cooling the wall surface by heat exchange in the film holes and forming a cooling film on the blade surface. Although the diameter and depth of the film holes are both in the order of millimeters, the flow inside them is very complex. The flow separation and reattachment at the inlet and the series of vortex structures formed by the mixing of the outlet cooling airflow and the mainstream all require very fine computational grids to make more accurate predictions, otherwise even the calculation of the flow of small holes will be very different from the actual. However, the number of film holes in high-temperature components using film cooling often reaches thousands. Fine mesh division and simulation calculation for each small hole not only greatly increases the calculation amount of the entire flow field, but also greatly increases the difficulty of drawing the grid and reduces the overall grid quality. Therefore, the numerical simulation of film cooling of high-temperature components faces the challenge of solving the small-scale flow disturbances and interactions of a large number of cooling holes. The latest trend in numerical simulation of film cooling flows is to develop towards higher-fidelity grids and more complex geometries. The rapid growth of computing power available to researchers has made this trend possible. However, fast turnaround times are required in design calculations, so faster calculation methods need to be developed for porous film cooling.

[0003] At present, the main methods for simulating the heat transfer in porous air film holes in engineering are the wall function method and the source term method. Both methods require a large number of simulation examples as a database. If the structural parameters of the air film hole are changed, such as the inclination angle and shape of the air film hole, it is necessary to re-construct a new database by numerical simulation. In addition, the flow coefficient of the cooling hole in the empirical relationship used is only related to the pressure and Reynolds number, and the influence of complex cross flow cannot be considered. The mass source used cannot simulate the attached jet, and the changes in the inlet and outlet pressure and temperature of the air film hole caused by the friction of the air film hole wall and the heat transfer of the hole wall are not considered. The above two methods are not the most effective methods for evaluating the air film cooling effect of high-temperature components, and cannot have the characteristics of small modeling workload and high calculation accuracy. Therefore, this field needs to develop an efficient and high-precision simulation method for simulating the surface temperature distribution of air film cooling of high-temperature components, so as to improve the design cycle and design efficiency. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a gridless calculation method for porous film cooling to solve the problem that the current engineering simulation of film cooling of high-temperature components cannot take into account the influence of complex cross flows and the influence of simulated attached jets, and the previous methods need to be based on a large number of simulation examples as a database; the method of the present invention can greatly reduce the amount of grids, and there is no need to build a database based on a large number of simulation examples, and can achieve efficient and high-precision simulation of the porous film cooling flow field and temperature field distribution of high-temperature components.

[0005] The present invention solves the above technical problems through the following technical solutions:

[0006] A gridless calculation method for porous film cooling, the calculation method steps are as follows:

[0007] S1. Model the high-temperature components and other related components at the inlet and outlet of the air film hole. The air film hole wall does not need to be modeled.

[0008] S2. Grid the computational model. Do not draw grids for the flow field inside the air film hole and inside the solid wall. Only draw wall grids for the inlet and outlet of the air film hole.

[0009] S3. Open ANSYS Fluent software, import the mesh file, set up the example for the mesh drawn in step S2, and compile and run the porous film cooling meshless simplified algorithm calculation program.

[0010] S4. Couple the flow fields inside and outside the air film hole to obtain the flow field and temperature field distribution of the high-temperature component.

[0011] According to an embodiment of the present invention, step S3 also includes: the porous film cooling gridless simplification algorithm UDF simplifies the flow and heat transfer in the film hole into a one-dimensional steady compressible pipe flow, and based on the differential form of the flow parameters of the one-dimensional friction heating pipe flow, the relationship between the inlet and outlet parameters of the film hole is obtained.

[0012] According to an embodiment of the present invention, step S4 specifically includes the following steps:

[0013] S41. Treat the inlet of the air film hole as the pressure outlet boundary condition, and give the static pressure P1 at the outlet of the air film hole;

[0014] S42. The film hole outlet is treated as a flow inlet boundary condition, and the film hole inlet flow m2, inlet static pressure P2, inlet total temperature T2* and incident angle θ are given;

[0015] S43. A negative heat source is given on the wall near the inlet and outlet of the air film hole, and its heat absorption is equal to the total heat exchange Q of the cold air passing through the wall of the air film hole;

[0016] S44. The hot side wall and the cold side wall of the film hole are coupled heat exchange boundaries, and the solid thermal resistance of the actual wall thickness is added;

[0017] S45. The flow field parameters at the inlet and outlet of the film hole are obtained by the simplified algorithm UDF for flow and heat transfer inside the film hole. The flow parameters at the inlet and outlet of the film hole are coupled with the three-dimensional flow field and solved iteratively until the calculation is fully converged.

[0018] According to an embodiment of the present invention, step S45 specifically includes the following steps:

[0019] 1) Read in the geometric parameters of the air film hole.

[0020] 2) Give the initial boundary conditions for the inlet and outlet of the air film hole.

[0021] 3) Given other boundary conditions of the computational domain, the three-dimensional computational domain is initialized.

[0022] 4) Perform iterative calculation and solution on the flow field in the three-dimensional computational domain until the flow field in the computational domain approaches a convergent state.

[0023] 5) Extract the relevant parameters of the air film hole inlet and outlet from the flow field iterative calculation results of the previous step.

[0024] 6) According to the simplified algorithm of flow heat transfer in the film hole, the static pressure P1 at the film hole inlet, Ma2 at the film hole outlet, total temperature T2*, static pressure P2, flow rate m2, and heat transfer Q on the film hole wall are obtained.

[0025] 7) Update the inlet and outlet boundary conditions of the film hole according to the inlet and outlet parameters of the film hole obtained by the simplified algorithm of flow and heat transfer in the film hole.

[0026] 8) Perform iterative calculation on the flow field outside the air film hole.

[0027] 9) Determine whether the three-dimensional flow field in the calculation domain converges, including the film hole inlet and outlet parameters, mainstream parameters, film hole wall temperature, etc. If not, repeat steps 5 to 8. If converged, end the calculation.

[0028] As a further improvement of the present technology, the step 1) specifically includes: the geometric parameters of the air film holes include the number of air film holes, the inclination angle of the air film holes, the pore diameter of the air film holes, the wall thickness of the air film holes and the average friction coefficient of the air film holes.

[0029] As a further improvement of the present technology, the step 2) specifically includes: treating the air film hole inlet as a pressure outlet boundary condition, giving the initial air film hole outlet static pressure P1; treating the air film hole outlet as a flow inlet boundary condition, giving the initial air film hole inlet flow m2, the initial inlet static pressure P2, the initial inlet total temperature T2* and the incident angle θ.

[0030] As a further improvement of the present technology, the step 5) specifically includes: extracting the film hole inlet and outlet related parameters from the flow field iterative calculation results of the previous step, including the film hole inlet flow m1, velocity V1, total temperature T1*, Mach number Ma1, film hole outlet static pressure P2, and solid wall temperature T near the film inlet and outlet w1 、T w2 .

[0031] As a further improvement of the present technology, the step 7) specifically includes: updating the inlet and outlet boundary conditions of the air film hole, assigning the outlet static pressure P1 to the inlet boundary of the air film hole; assigning the inlet static pressure P2, the inlet total temperature T2*, the inlet flow rate m2, and the incident angle θ to the outlet boundary of the air film hole; and assigning the heat absorption Q to the wall grid cells near the air film hole mouth.

[0032] Compared with the prior art, the gridless calculation method for porous film cooling described in the present invention has the following advantages:

[0033] (1) This inventive method does not need to be based on existing film cooling simulation examples as a database, and does not predict the flow characteristics of the small hole based on the flow coefficient. It only obtains the relationship between the inlet and outlet parameters of the film hole based on the differential form of the flow parameters of the one-dimensional friction heating pipe flow to predict the flow characteristics of the film hole. Therefore, it overcomes the problems that traditional methods cannot simulate attached jets and consider the influence of complex cross flows. The prediction accuracy of the flow characteristics of the film hole is improved, and the applicability and versatility of simplified calculations for film cooling are also greatly improved.

[0034] (2) This inventive method takes into account the changes in the inlet and outlet pressures and temperatures of the air film holes caused by the friction of the air film hole wall and the heat exchange of the hole wall, as well as the influence of the heat exchange of the air film hole on the hot and cold side wall temperatures of the air film, thereby improving the prediction accuracy of the wall temperature of high-temperature components.

[0035] (3) This inventive method realizes that there is no need to draw grids on the air film holes and solid wall surfaces. Only the inlet and outlet of the air film holes need to be gridded, which greatly reduces the number of grids. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a microelement control volume diagram inside the air film hole provided by an embodiment of the present invention.

[0037] Figure 2 It is a schematic diagram of a method for calculating the coupling of the flow fields inside and outside the air film hole according to an embodiment of the present invention.

[0038] Figure 3 It is a schematic diagram of a gridless calculation method for the air film hole interior and the air film hole wall according to an embodiment of the present invention.

[0039] Figure 4 This is a grid division diagram of porous air film cooling according to an embodiment of the present invention.

[0040] Figure 5 This is a grid division diagram of the non-porous air film cooling according to an embodiment of the present invention.

[0041] Figure 6 It is a mid-section wall temperature distribution diagram of the pressure surface of a turbine blade according to the method of the embodiment of the present invention and the method with air film holes simulation. DETAILED DESCRIPTION

[0042] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples or drawings are used to illustrate the present invention, but are not used to limit the scope of protection of the present invention.

[0043] A gridless calculation method for porous film cooling, the main steps of the calculation method are as follows:

[0044] S1.Use Ug modeling software to model the high-temperature components and other related components containing the inlet and outlet of the air film hole. The air film hole tube wall does not need to be modeled, but the inlet and outlet of the air film hole need to be modeled.

[0045] S2. The meshing software ICEM is used to mesh the calculation model. No mesh is drawn inside the air film hole flow field and the solid wall. Only the wall mesh is drawn at the inlet and outlet of the air film hole.

[0046] S3. Open ANSYS Fluent software, import the mesh file, use the fluid simulation software Fluent to set up the example for the mesh drawn in step S2, and compile and run the porous film cooling meshless simplified algorithm calculation program UDF.

[0047] S4. Couple the flow fields inside and outside the air film hole to obtain the flow field and temperature field distribution of the high-temperature component.

[0048] Through steps S1-S4, the coupled calculation of the flow fields inside and outside the multiple air film holes is realized, thereby obtaining the wall temperature distribution of the high-temperature component and the flow field distribution outside the air film holes.

[0049] In a further embodiment, Figure 1 As shown, the mesh-free simplified algorithm calculation procedure of porous air film cooling in step S3 above is based on the differential form of the flow parameters of the one-dimensional friction heating pipe flow, and the relationship between the inlet and outlet parameters of the air film hole is obtained. The following are the steps of the simplified algorithm for flow and heat transfer in the air film hole:

[0050] The flow and heat transfer process of cold air flowing through the air film hole can be simplified as a one-dimensional steady compressible pipe flow, ignoring chemical reactions and changes in cross-sectional area. Heat transfer and friction are the main factors affecting the pressure and temperature along the process. In order to simplify the calculation process, the following reasonable assumptions are made for the flow and heat transfer process in the air film hole:

[0051] 1) The flow is a one-dimensional steady-state flow.

[0052] 2) The gas properties change continuously during the flow process.

[0053] 3) The gas is an ideal gas and its specific heat is constant within the temperature range involved.

[0054] 4) No chemical reaction or phase change occurs during the flow process.

[0055] 5) Pipes with equal cross-sections.

[0056] 6) There is no exchange of mechanical work between the gas and the outside world.

[0057] 7) Since the flow velocity in the film hole is high and the length of the film hole is short, the effect of heat exchange between the air flow in the hole and the solid wall of the film hole on the Mach number of the air flow at the inlet and outlet of the film hole is ignored, and it is believed that the factor affecting the Mach number at the inlet and outlet of the film hole is the wall friction.

[0058] For the flow and heat transfer process in the air film hole, the microelement control body is taken to establish the basic equation in differential form as follows. The gas in the tube satisfies the following equation:

[0059] Continuity equation:

[0060]

[0061] Momentum equation:

[0062] -Adp-τ w dA w =ρAVdV (2)

[0063] A w is the contact area between the airflow and the inside of the tube,

[0064] Energy equation:

[0065]

[0066] Ideal gas state equation:

[0067]

[0068] The differential form of the Mach number definition is:

[0069]

[0070] Stagnation temperature:

[0071]

[0072] From the above formulas, we can conclude:

[0073]

[0074] In a film hole with an inclination angle of θ, a thickness of d, and a length of L, the above formulas are integrated between the inlet and outlet cross sections to obtain the relationship between the inlet and outlet parameters. Rewriting formula (8) in the form of velocity factor λ gives:

[0075]

[0076] Integrating the above formula, we can get:

[0077]

[0078] In the formula, is the friction coefficient averaged over the length L, that is:

[0079]

[0080] Therefore, if the Mach number Ma1 at the inlet of the film hole is known, the Mach number Ma2 at the outlet can be calculated based on the relationship between the speed factors of the inlet and outlet. It should be noted that this paper ignores the influence of heat exchange between the airflow in the hole and the solid wall of the film hole on the Mach number of the airflow at the inlet and outlet of the film hole, and believes that the factor affecting the Mach number of the inlet and outlet of the film hole is wall friction.

[0081] Integrating other equations from the air film hole entrance to the air film hole exit, we can get:

[0082]

[0083] In the above formula, T1 * , From the heat transfer energy equation we get:

[0084]

[0085] The heat transfer Q is determined according to the Nu number flow heat transfer correlation and heat transfer coefficient formula:

[0086]

[0087] Where m is the flow rate in the hole, λ is the thermal conductivity of the fluid, and D h is the hydraulic diameter of the hole entrance, T f is the average temperature of the fluid, T w is the average temperature of the tube wall, and A is the heat exchange area of ​​the tube wall.

[0088] The Nu number in the hole is obtained according to the Nusselt number correlation formula in the inclined hole obtained by Mills through experimental research:

[0089] Nu=0.023×Re 0.8 ×Pr 0.33×R Nu (twenty two)

[0090] In the formula R Nu is the correction coefficient of the Nu number in the hole, which is related to the aspect ratio of the small hole:

[0091]

[0092] Obviously, the relationship between the hole length and the air film hole inclination angle is as follows:

[0093]

[0094] For the flow and heat transfer process in the air film cooling air film hole, there is a local pressure loss at the inlet and outlet of the air film hole, and the local pressure loss cannot be ignored compared with the loss along the way. Therefore, C f The calculation of needs to consider the local loss at the entrance of the air film hole and the loss along the way. The literature gives the calculation formula of the apparent friction coefficient, which is used to characterize the friction coefficient when considering the friction effect and the change of the velocity type. The formula is as follows:

[0095]

[0096] When the velocity distribution of the axial section is the same,

[0097] For the flow in the film hole, it is assumed that the velocity profiles along the axial direction of the film hole are the same.

[0098] It can be deduced

[0099] For the along-the-line loss coefficient in the tube, ignoring the compressibility of the gas, the experimental correlation formula for the along-the-line loss in the Nicolaz circular tube is used to obtain λ=f(Re,△ / d), where Re is calculated according to the average velocity at the entrance of the air film hole.

[0100] For the local loss coefficient at the inlet of the air film hole, it can be considered that the fluid flows in a pipe with a sudden reduction in the pipe interface. For the suddenly reduced pipe, there is a relevant empirical formula to determine the local loss coefficient:

[0101]

[0102] For the inlet of the film hole, it can be considered that the fluid flows into the pipe from a large container and has a sharp edge at the inlet, A2 / A1→0, so the local loss coefficient at the inlet of the film hole ξ=0.5.

[0103] Therefore, the average friction coefficient can be obtained based on the along-the-line loss coefficient and the local loss coefficient.

[0104] Based on the differential form of the flow parameters of the one-dimensional friction heating pipe flow, the relationship between the inlet and outlet parameters of the air film hole is obtained through step S3. In a further embodiment, step S4 specifically includes the following steps:

[0105] S41. Treat the inlet of the air film hole as the pressure outlet boundary condition, and give the static pressure P1 at the outlet of the air film hole;

[0106] S42. The film hole outlet is treated as a flow inlet boundary condition, and the film hole inlet flow m2, inlet static pressure P2, inlet total temperature T2* and incident angle θ are given;

[0107] S43. A negative heat source is given on the wall near the inlet and outlet of the air film hole, and its heat absorption is equal to the total heat exchange Q of the cold air passing through the wall of the air film hole;

[0108] S44. The hot side wall and the cold side wall of the film hole are coupled heat exchange boundaries, and the solid thermal resistance of the actual wall thickness is added;

[0109] S45. The flow field parameters at the inlet and outlet of the film hole are obtained by the simplified algorithm UDF for flow and heat transfer inside the film hole. The flow parameters at the inlet and outlet of the film hole are coupled with the three-dimensional flow field and solved iteratively until the calculation is fully converged.

[0110] In a further embodiment, the step S45 is as follows Figure 2 The figure is a schematic diagram of the calculation method for coupling the flow field inside and outside the air film hole according to an embodiment of the present invention. Specifically, the following steps are included:

[0111] In the coupled calculation of the flow field inside and outside the air film hole, no mesh is drawn for the flow field inside the air film hole and the inside of the solid wall, and only the wall mesh is drawn for the inlet and outlet of the air film hole. Figure 3 As shown, the inlet of the film hole is treated as a pressure outlet boundary condition, and the static pressure P1 of the film hole outlet is given; the outlet of the film hole is treated as a flow inlet boundary condition, and the inlet flow rate m2, the inlet static pressure P2, the inlet total temperature T2* and the incident angle θ of the film hole are given; a negative heat source is given on the wall near the inlet and outlet of the film hole, and its heat absorption is equal to the total heat exchange Q of the cold air passing through the wall of the film hole; the hot side wall and the cold side wall of the film hole are coupled heat exchange boundaries, and the solid thermal resistance of the actual wall thickness is added; the inlet and outlet flow field parameters of the film hole are obtained by the simplified algorithm of flow heat transfer in the film hole above, and the inlet and outlet flow parameters of the film hole are coupled with the three-dimensional flow field and iteratively solved until the calculation is fully converged. The following are the detailed calculation steps:

[0112] (1) The geometric parameters of the air film holes read in include the number of air film holes, the inclination angle of the air film holes, the diameter of the air film holes, the thickness of the air film holes wall and the average friction coefficient of the air film holes.

[0113] (2) The initial boundary conditions are given for the inlet and outlet of the air film hole. The inlet of the air film hole is treated as the pressure outlet boundary condition, and the initial static pressure P1 of the air film hole outlet is given; the outlet of the air film hole is treated as the flow inlet boundary condition, and the initial inlet flow m2, the initial inlet static pressure P2, the initial inlet total temperature T2* and the incident angle θ of the air film hole are given.

[0114] (3) Given other boundary conditions of the computational domain, the three-dimensional computational domain is initialized.

[0115] (4) Perform iterative calculations on the flow field in the three-dimensional computational domain until the flow field in the computational domain approaches a convergent state.

[0116] (5) Extract the flow rate m1, velocity V1, total temperature T1*, Mach number Ma1, static pressure P2 at the film hole outlet, and solid wall temperature T near the film inlet and outlet from the flow field iterative calculation results in the previous step. w1 、T w2 , it is considered that the average temperature of the film hole wall

[0117] (6) According to the simplified algorithm of flow heat transfer in the air film hole, the static pressure P1 at the air film hole inlet, Ma2 at the air film hole outlet, total temperature T2*, static pressure P2, flow rate m2, and heat transfer Q on the air film hole wall are obtained.

[0118] (7) Based on the simplified algorithm for heat transfer in the air film hole, the inlet and outlet boundary conditions of the air film hole are updated. The outlet static pressure P1 is assigned to the inlet boundary of the air film hole. The inlet static pressure P2, inlet total temperature T2*, inlet flow rate m2, and incident angle θ are assigned to the outlet boundary of the air film hole. The heat absorption Q is assigned to the wall grid cells near the air film hole mouth.

[0119] (8) Perform iterative calculation on the flow field outside the air film hole.

[0120] (9) Determine whether the three-dimensional flow field in the calculation domain converges, including the film hole inlet and outlet parameters, mainstream parameters, film hole wall temperature, etc. If not, repeat steps 5 to 8. If converged, end the calculation.

[0121] According to the above description, in order to reduce the amount of grids and the amount of calculation consumption, and at the same time ensure high calculation accuracy, the gridless calculation method for porous film cooling of the present invention is established based on the user-defined function (UDF) in the ANSYS Fluent software. The inlet of the film hole is treated as a pressure outlet boundary condition, and the static pressure P1 at the outlet of the film hole is given; the outlet of the film hole is treated as a flow inlet boundary condition, and the inlet flow m2, the inlet static pressure P2, the inlet total temperature T2* and the incident angle θ of the film hole are given; a negative heat source is given on the wall near the inlet and outlet of the film hole, and its heat absorption is equal to the total heat exchange Q of the cold air passing through the wall of the film hole. No grid is drawn for the flow field inside the film hole and the inside of the solid wall, and only the wall grid is drawn for the inlet and outlet of the film hole, so the amount of grids is greatly reduced, and the more the number of film holes, the more the amount of grids is reduced.

[0122] This example establishes a turbine blade film cooling structure and performs structured meshing, including a porous structure ( Figure 4 , enlarged image of a single air film hole) and a non-porous structure ( Figure 5 , enlarged image of a single film hole), based on the user-defined function (UDF) in ANSYS Fluent software, CFD calculations were performed through ANSYS Fluent to verify the accuracy of the calculation method. Under the condition of subsonic mainstream, this method and the method of drawing grids inside the film hole were compared and analyzed on the wall temperature distribution of the middle section of the blade pressure surface, such as Figure 6 As shown in the figure, the calculation accuracy and feasibility of this method are verified.

[0123] Compared with the prior art, the gridless calculation method for porous film cooling described in the present invention has the following advantages:

[0124] (1) This inventive method does not need to be based on existing film cooling simulation examples as a database, and does not predict the flow characteristics of the small hole based on the flow coefficient. It only obtains the relationship between the inlet and outlet parameters of the film hole based on the differential form of the flow parameters of the one-dimensional friction heating pipe flow to predict the flow characteristics of the film hole. Therefore, it overcomes the problems that traditional methods cannot simulate attached jets and consider the influence of complex cross flows. The prediction accuracy of the flow characteristics of the film hole is improved, and the applicability and versatility of simplified calculations for film cooling are also greatly improved.

[0125] (2) This inventive method takes into account the changes in the inlet and outlet pressures and temperatures of the air film holes caused by the friction of the air film hole wall and the heat exchange of the hole wall, as well as the influence of the heat exchange of the air film hole on the hot and cold side wall temperatures of the air film, thereby improving the prediction of the wall temperature.

[0126] (3) This inventive method realizes that there is no need to draw grids on the air film holes and solid wall surfaces. Only the inlet and outlet of the air film holes need to be gridded, which greatly reduces the number of grids.

[0127] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A gridless calculation method for porous film cooling, characterized in that: The calculation method steps are as follows: S1. Model the high-temperature components and other related components of the gas film hole inlet and outlet, and the gas film hole wall does not need to be modeled; S2. Grid the computational model. Do not draw grids for the flow field inside the air film hole and the solid wall. Only draw wall grids for the inlet and outlet of the air film hole. S3. Open ANSYS Fluent software, import the mesh file, set up the example for the mesh drawn in step S2, compile and run the porous film cooling meshless simplified algorithm calculation program; S4. Couple the flow fields inside and outside the air film hole to obtain the flow field and temperature field distribution of the high-temperature component.

2. A gridless calculation method for porous film cooling according to claim 1, characterized in that: The step S3 also includes: the porous film cooling gridless simplification algorithm UDF simplifies the flow and heat transfer in the film hole into a one-dimensional steady compressible pipe flow, and based on the differential form of the flow parameters of the one-dimensional friction heating pipe flow, the relationship between the inlet and outlet parameters of the film hole is obtained.

3. A gridless calculation method for porous film cooling according to claim 1, characterized in that: The step S4 specifically comprises the following steps: S41. Treat the inlet of the air film hole as the pressure outlet boundary condition, and give the static pressure P1 at the outlet of the air film hole; S42. The film hole outlet is treated as a flow inlet boundary condition, and the film hole inlet flow m2, inlet static pressure P2, inlet total temperature T2* and incident angle θ are given; S43. A negative heat source is given on the wall near the inlet and outlet of the air film hole, and its heat absorption is equal to the total heat exchange Q of the cold air passing through the wall of the air film hole; S44. The hot side wall and the cold side wall of the film hole are coupled heat exchange boundaries, and the solid thermal resistance of the actual wall thickness is added; S45. The flow field parameters at the inlet and outlet of the film hole are obtained by the simplified algorithm UDF for flow and heat transfer inside the film hole. The flow parameters at the inlet and outlet of the film hole are coupled with the three-dimensional flow field and solved iteratively until the calculation is fully converged.

4. A gridless calculation method for porous film cooling according to claim 3, characterized in that: The step S45 specifically includes the following steps: 1) Read in the geometric parameters of the air film hole; 2) Give the initial boundary conditions for the inlet and outlet of the air film hole; 3) Given other boundary conditions of the computational domain, the three-dimensional computational domain is initialized; 4) Iteratively calculate and solve the flow field in the three-dimensional computational domain until the flow field in the computational domain is close to a convergent state; 5) Extract the relevant parameters of the air film hole inlet and outlet from the flow field iterative calculation results in the previous step; 6) According to the simplified algorithm of flow heat transfer in the air film hole, the static pressure P1 at the air film hole inlet, Ma2 at the air film hole outlet, total temperature T2*, static pressure P2, flow rate m2, and heat transfer Q on the air film hole wall are obtained; 7) Update the inlet and outlet boundary conditions of the air film hole according to the air film hole inlet and outlet parameters obtained by the simplified algorithm of flow and heat transfer in the air film hole; 8) Iterative calculation of the flow field outside the air film hole; 9) Determine whether the three-dimensional flow field in the calculation domain converges, including the film hole inlet and outlet parameters, mainstream parameters, film hole wall temperature, etc.; if not, repeat steps 5 to 8, if converged, end the calculation.

5. A gridless calculation method for porous film cooling according to claim 4, characterized in that: The step 1) specifically includes: the geometric parameters of the air film holes include the number of air film holes, the inclination angle of the air film holes, the diameter of the air film holes, the thickness of the air film holes wall and the average friction coefficient of the air film holes.

6. A gridless calculation method for porous film cooling according to claim 4, characterized in that: The step 2) specifically includes: treating the air film hole inlet as a pressure outlet boundary condition, and giving the initial air film hole outlet static pressure P1; treating the air film hole outlet as a flow inlet boundary condition, and giving the initial air film hole inlet flow m2, the initial inlet static pressure P2, the initial inlet total temperature T2* and the incident angle θ.

7. A gridless calculation method for porous film cooling according to claim 4, characterized in that: The step 5) specifically includes: extracting the film hole inlet and outlet related parameters from the flow field iterative calculation results of the previous step, including the film hole inlet flow m1, velocity V1, total temperature T1*, Mach number Ma1, film hole outlet static pressure P2, and solid wall temperature T near the film inlet and outlet w1 , T w2 .

8. A gridless calculation method for porous film cooling according to claim 4, characterized in that: The step 7) specifically includes: updating the inlet and outlet boundary conditions of the air film hole, assigning the outlet static pressure P1 to the inlet boundary of the air film hole; assigning the inlet static pressure P2, the inlet total temperature T2*, the inlet flow rate m2, and the incident angle θ to the outlet boundary of the air film hole; and assigning the heat absorption Q to the wall grid cells near the air film hole.

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