Numerical simulation method for air film cooling modeling

Abstract

The invention discloses a numerical simulation method for air film cooling modeling, and relates to the technical field of aero-engine combustion chamber numerical calculation. Comprising the following steps: carrying out porous flat plate numerical calculation under different flow parameters and pore structure parameters to obtain simulation data under different working conditions; establishing a mathematical equation by using the simulation data of the perforated flat plate, and describing the flow characteristics of the jet flow in a small volume; removing small holes in the wall surface of the combustion chamber, performing numerical calculation to obtain internal and external pressure difference distribution of the wall surface of the combustion chamber, and obtaining mass flow of each position according to the pressure difference distribution; small-hole jet flow is introduced into numerical calculation software in a source item mode, and the mass flow rate, the momentum and the temperature are defined in the small volume of the jet flow; and performing hole-free geometric simulation calculation according to the small hole jet flow model to obtain temperature field, pressure field and wall surface temperature distribution information in the combustion chamber. According to the method, the small holes in the wall surface are removed, so that the grid division difficulty of the model is reduced, the grid quality is improved, and calculation resources occupied in numerical calculation are reduced.

Description

Technical Field

[0001] The invention relates to the technical field of numerical calculation of aero-engine combustion chambers, and more particularly to a numerical simulation method for air film cooling modeling. Background Art

[0002] The aircraft engine is the "heart" of the aircraft, providing the aircraft with the power to move forward. With the advancement of aviation technology, aircraft engines need to operate under higher temperature and pressure conditions to achieve higher combustion efficiency and thrust-to-weight ratio. In order to obtain a higher thrust-to-weight ratio and reduce fuel consumption, the operating temperature of aircraft engines has gradually increased, especially the temperature of the combustion chamber and turbine blades. From 1960 to the present, the operating temperature of aircraft engines has increased by almost 15K every year. From the first to the fourth generation of aircraft engines, the turbine inlet temperature has also increased significantly. Although material technology has made great progress, such as the application of high-temperature resistant alloys and ceramic-based composites, the heat resistance of the combustion chamber wall and turbine blades has been improved, but it is still difficult to meet the temperature requirements of the new generation of engines. It is expected that the turbine inlet temperature of the fifth-generation aircraft engine will reach 2300K, which is far higher than the maximum operating temperature of most combustion chamber and turbine blade materials. This extreme temperature will cause cracks in the material, which will lead to thermal failure of the combustion chamber and turbine blades, affecting the safety and life of the engine.

[0003] Full-coverage film cooling technology has been widely used in the cooling of combustion chambers. Its main principle is to drill thousands of tiny holes on the combustion chamber liner through laser technology, and use the pressure difference to make the coolant spray microjets at each small hole. These microjets interact with each other to form a consistent airflow, which mixes with the high-temperature heat flow in the combustion chamber, and at the same time forms a cooling film on the combustion chamber wall, thereby effectively protecting the combustion chamber wall. Aircraft engines operate under high temperature and high pressure working environment, and the experimental conditions are very harsh. Therefore, computational fluid dynamics technology is widely used in the numerical simulation of aircraft engines to predict and optimize engine performance in the design stage. Fluid simulation calculations can simulate the complex flow and heat transfer process in the combustion chamber, helping engineers understand the working mechanism of the cooling system. However, when numerically simulating real engines, due to the large number of cooling holes and the sub-millimeter aperture, accurate modeling of these holes will lead to a sharp increase in the number of grids. This not only greatly increases the consumption of computing resources, but also prolongs the calculation time.

[0004] In the numerical simulation of the cooling holes on the combustion chamber wall, the commonly used method is to directly model and mesh the holes, which will result in a huge number of meshes and significantly increase the calculation time. At the same time, due to the existence of the holes, it is difficult to mesh the boundary layer near the wall, which reduces the analytical accuracy of the wall flow and makes it difficult to accurately simulate the flow characteristics near the wall. In summary, it is necessary to develop a film cooling modeling method to simplify the mesh processing of the cooling holes and accurately simulate the influence of the hole jet on the internal flow field and wall temperature field of the combustion chamber.

[0005] Therefore, it is an urgent problem for those skilled in the art to propose a numerical simulation method for film cooling modeling to solve the difficulties existing in the prior art. Summary of the invention

[0006] In view of this, the present invention provides a numerical simulation method for film cooling modeling to solve the problems of difficult meshing and large loss of computing resources caused by the presence of small holes on the wall; this method can restore the small hole jet without modeling the small holes and ensure sufficient accuracy.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] A numerical simulation method for film cooling modeling includes the following steps:

[0009] Numerical calculations of the plate with holes were performed under different flow parameters and hole structure parameters to obtain simulation data under different working conditions;

[0010] The simulation data of the plate with holes is used to establish mathematical equations to describe the flow characteristics in a small volume of the jet;

[0011] Remove the small holes on the combustion chamber wall, perform numerical calculations, obtain the pressure difference distribution inside and outside the combustion chamber wall, and obtain the mass flow rate at each position based on the pressure difference distribution;

[0012] The small hole jet is introduced into the numerical calculation software as a source term, and the mass flow rate, momentum and temperature are defined in the small volume of the jet;

[0013] Based on the small hole jet model, simulation calculation of non-hole geometry is carried out to obtain the temperature field, pressure field and wall temperature distribution information in the combustion chamber.

[0014] Optionally, numerical calculations of a plate with holes are performed under different typical flow parameters and hole structure parameters, and the specific contents of the data obtained under different working conditions are as follows:

[0015] According to the working conditions of the aircraft engine, the flow parameters are set, the hole structure parameters are selected, and numerical simulation is performed on the flat plate wall to obtain simulation data under different working conditions, providing a numerical basis for the modeling of small hole jets;

[0016] The flow parameters include the velocity ratio, density ratio, blowing ratio, and momentum ratio of the small hole jet to the mainstream; the hole structure parameters include the hole geometry, hole inclination, deflection angle, and aspect ratio.

[0017] Optionally, a mathematical equation is established using simulation data of a plate with holes to describe the flow characteristics in a small volume of the jet:

[0018] The mathematical equations describe the flow characteristics in a small volume of the jet, including: flow trajectory, flow shape, momentum distribution and temperature distribution;

[0019] The generalized solution based on the force balance on the infinitesimal volume of the jet is used to describe the penetration height of the jet into the mainstream. The specific expression is:

[0020]

[0021] Assuming that the jet is a flat plate flow, the upper and lower parts of the flat plate are respectively the mainstream and cooling air flow channels, the jet enters the mainstream from the outlet surface, the origin is the center of the outlet surface, the x-axis points to the direction of the mainstream, the y-axis is the span direction of the flat plate, and the z-axis is perpendicular to the orifice outlet plane, then x is the x-coordinate; ψ, when the equation is solved for the y-coordinate of the trajectory, it represents y, and when the equation is solved for the z-coordinate of the trajectory, it represents z; x0 / D, when the y-coordinate of the trajectory is solved, it is the relative offset Y, and when the z-coordinate of the trajectory is solved, it is 0; ψ0 / D, when the y-coordinate of the trajectory is solved, it is the relative reference Y', and when the z-coordinate of the trajectory is solved, it is the relative reference Z; A ψ , when solving for the y coordinate of the trajectory, it is the coefficient A Y , when solving for the z coordinate of the trajectory, it is the coefficient A Z ; B ψ , which is the coefficient B when solving the coordinates of the trajectory Y , which is the coefficient B when solving for the z coordinate of the trajectory Z θ real is the effective azimuth angle, which is 0 when solving for the y coordinate of the trajectory and is the effective elevation angle when solving for the z coordinate of the trajectory, as the angle in the local xz plane; D is the aperture; IR is the momentum ratio; cot 2 is the cotangent trigonometric function;

[0022] The flow shape of the jet is expressed by a truncated Fourier series:

[0023]

[0024] in, a is the radius of a point on the cross-sectional shape in the direction of the jet, and the cross-sectional shape is always perpendicular to the direction of the jet; i 、b iare the coefficients of the Fourier series; assuming that the orifice outlet surface is a horizontal plane, set the local coordinate system that moves with the jet, and the origin of the coordinate is always at the center of the jet cross section, x s The y axis always points to the direction of the jet flow. s The axis is always parallel to the orifice outlet surface, then α s is the local y s -z s The angle of the plane, from y s The axis starts measuring;

[0025] According to the continuity theorem, the velocity of the small hole jet is obtained:

[0026]

[0027] Where v is the jet velocity of the small hole, m is the mass flow rate per unit time of each small hole, ρ is the density of the cooling jet, and D is the aperture;

[0028] The temperature distribution on the orthogonal section of the trajectory is given in the form of a quadratic function:

[0029]

[0030] Among them, A, B, C are coefficients, r s is the radius at a point on the orthogonal section of the trajectory, and T is the jet temperature at a point on the orthogonal section of the trajectory.

[0031] Optionally, the small holes on the combustion chamber wall are removed, and numerical calculations are performed to obtain the pressure difference distribution inside and outside the combustion chamber wall. The specific content of the mass flow rate at each position is obtained according to the pressure difference distribution:

[0032] Assuming that the inner wall pressure at the orifice outlet is P, and the corresponding outer wall pressure is P0, the formula for mass flow is:

[0033]

[0034] Among them, C D is the flow coefficient, γ is the specific heat capacity, R is the gas constant, T0 is the outer wall temperature, and D is the pore diameter.

[0035] Optionally, the small hole jet is introduced into the numerical calculation software as a source term, and the specific contents of mass flow rate, momentum and temperature in the small volume of the jet are defined as:

[0036] The mass source is defined in a finite volume near the hole outlet. By applying velocity and temperature values, the three-dimensional velocity field and temperature field are simulated in the source volume. After the source term is introduced, the continuity equation, momentum equation, and energy equation are:

[0037]

[0038]

[0039]

[0040] Among them, S MS is the mass source, u MS,i is the velocity component of the mass source, E MS is the total energy of the mass source, ρ is the density of the cooling jet, t is the time, u is the velocity, x is the coordinate, τ is the shear stress, E is the total energy, is the heat flux, i, j are directions;

[0041] The formulas for total energy and specific internal energy are as follows:

[0042]

[0043] e=(c p -R)T

[0044] Among them, c p is the specific heat capacity at constant pressure, ρ is the density of the cooling jet, e is the specific internal energy, u is the velocity, i is the direction, and E is the total energy.

[0045] Optionally, the simulation calculation of the non-porous geometry is performed according to the small hole jet model to obtain the temperature field, pressure field and wall temperature distribution information in the combustion chamber as follows:

[0046] The non-porous geometry is meshed, the small holes are removed and the small hole circular surface is retained, and the small hole circular surface is encrypted. The encryption coefficient R' is defined as follows:

[0047]

[0048] Among them, dx is the encrypted size of the circular surface of the small hole, and D is the hole diameter;

[0049] For the combustion chamber model without the small holes, the parameters input to the film cooling model include:

[0050] Basic parameters: small hole coordinates, small hole inclination angle, small hole deflection angle, aperture, porosity, cooling air flow temperature, cooling air flow density;

[0051] Flow trajectory parameters: relative offset Y, relative reference Y', relative reference Z, coefficient A Y , A Z , B Y , B Z 、Effective azimuth angle θ real ;

[0052] Flow shape parameters: Fourier coefficients a0, a1, a2, b1, b2;

[0053] Temperature distribution parameters: coefficients A, B;

[0054] Mass flow parameters: inner wall pressure P at the orifice outlet, outer wall pressure P0, flow coefficient C D , specific heat capacity γ, gas constant R, outer wall temperature T0;

[0055] Perform numerical simulation of non-porous geometry and obtain the flow field and temperature field information of the non-porous geometry in post-processing.

[0056] It can be seen from the above technical solutions that, compared with the prior art, the present invention discloses a numerical simulation method for film cooling modeling, which has the following beneficial effects:

[0057] The flow information of the cooling jet is described based on the basic parameters of film cooling, flow trajectory parameters, flow parameters, etc., and this method is integrated into the numerical calculation software. The numerical simulation of the small hole jet can be achieved without modeling the cooling holes, thereby greatly reducing the time cost required for calculation. This method is suitable for related research and early design optimization of combustion chambers, and can effectively deal with the technical difficulties caused by small hole modeling in numerical simulation of aero-engines, and provide efficient numerical simulation support for aero-engine design. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0059] Figure 1 A flow chart of a numerical simulation method for film cooling modeling provided by the present invention;

[0060] Figure 2 A schematic diagram showing a comparison of the cooling efficiency distribution of the experimental device, the geometry with holes and the geometry without holes in the porous plate model provided in the embodiment of the present invention;

[0061] Figure 3 A schematic diagram showing a comparison of the center temperature fields of a geometry with holes and a geometry without holes in a combustion chamber model provided in an embodiment of the present invention;

[0062] Figure 4 A schematic diagram showing a comparison of the outlet temperature fields of the combustion chamber model with holes and without holes in the embodiment of the present invention;

[0063] Figure 5 A comparison of the average temperature distribution along the wall of a combustion chamber model with holes and without holes, and a relative error curve diagram in the combustion chamber model provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0064] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0065] See also Figure 1 As shown, the present invention discloses a numerical simulation method for film cooling modeling, comprising the following steps:

[0066] Numerical calculations of the plate with holes were performed under different flow parameters and hole structure parameters to obtain simulation data under different working conditions;

[0067] The simulation data of the plate with holes is used to establish mathematical equations to describe the flow characteristics in a small volume of the jet;

[0068] Remove the small holes on the combustion chamber wall, perform numerical calculations, obtain the pressure difference distribution inside and outside the combustion chamber wall, and obtain the mass flow rate at each position based on the pressure difference distribution;

[0069] The small hole jet is introduced into the numerical calculation software as a source term, and the mass flow rate, momentum and temperature are defined in the small volume of the jet;

[0070] Based on the small hole jet model, simulation calculation of non-hole geometry is carried out to obtain the temperature field, pressure field and wall temperature distribution information in the combustion chamber.

[0071] Furthermore, numerical calculations of the plate with holes were performed under different typical flow parameters and hole structure parameters, and the specific contents of the data obtained under different working conditions are as follows:

[0072] According to the working conditions of the aircraft engine, the flow parameters are set, the hole structure parameters are selected, and numerical simulation is performed on the flat plate wall to obtain simulation data under different working conditions, providing a numerical basis for the modeling of small hole jets;

[0073] The flow parameters include the velocity ratio, density ratio, blowing ratio, and momentum ratio of the small hole jet to the mainstream; the hole structure parameters include the hole geometry, hole inclination, deflection angle, and aspect ratio.

[0074] Specifically, in film cooling, the cooling effect is mainly affected by two parameters: pore structure parameters and flow parameters.

[0075] Furthermore, the mathematical equation is established using the simulation data of the plate with holes to describe the flow characteristics in a small volume of the jet:

[0076] The mathematical equations describe the flow characteristics in a small volume of the jet, including: flow trajectory, flow shape, momentum distribution and temperature distribution;

[0077] The generalized solution based on the force balance on the infinitesimal volume of the jet is used to describe the penetration height of the jet into the mainstream. The specific expression is:

[0078]

[0079] Assuming that the jet is a flat plate flow, the upper and lower parts of the flat plate are respectively the mainstream and cooling air flow channels, the jet enters the mainstream from the outlet surface, the origin is the center of the outlet surface, the x-axis points to the direction of the mainstream, the y-axis is the span direction of the flat plate, and the z-axis is perpendicular to the orifice outlet plane, then x is the x-coordinate; ψ, when the equation is solved for the y-coordinate of the trajectory, it represents y, and when the equation is solved for the z-coordinate of the trajectory, it represents z; x0 / D, when the y-coordinate of the trajectory is solved, it is the relative offset Y, and when the z-coordinate of the trajectory is solved, it is 0; ψ0 / D, when the y-coordinate of the trajectory is solved, it is the relative reference Y', and when the z-coordinate of the trajectory is solved, it is the relative reference Z; A ψ , when solving for the y coordinate of the trajectory, it is the coefficient A Y , when solving for the z coordinate of the trajectory, it is the coefficient A Z ; B ψ , which is the coefficient B when solving the coordinates of the trajectory Y , which is the coefficient B when solving for the z coordinate of the trajectory Z θ real is the effective azimuth angle, which is 0 when solving for the y coordinate of the trajectory and is the effective elevation angle when solving for the z coordinate of the trajectory, as the angle in the local xz plane; D is the aperture; IR is the momentum ratio; cot 2 is the cotangent trigonometric function;

[0080] The flow shape of the jet is expressed by a truncated Fourier series:

[0081]

[0082] in, a is the radius of a point on the cross-sectional shape in the direction of the jet, and the cross-sectional shape is always perpendicular to the direction of the jet; i 、b i are the coefficients of the Fourier series; assuming that the orifice outlet surface is a horizontal plane, set the local coordinate system that moves with the jet, and the origin of the coordinate is always at the center of the jet cross section, x s The y axis always points to the direction of the jet. s The axis is always parallel to the orifice outlet surface, then α s is the local y s -z s The angle of the plane, from y s The axis starts measuring;

[0083] According to the continuity theorem, the velocity of the small hole jet is obtained:

[0084]

[0085] Where v is the jet velocity of the small hole, m is the mass flow rate per unit time of each small hole, ρ is the density of the cooling jet, and D is the aperture;

[0086] The temperature distribution on the orthogonal section of the trajectory is given in the form of a quadratic function:

[0087]

[0088] Among them, A, B, C are coefficients, r s is the radius at a point on the orthogonal section of the trajectory, and T is the jet temperature at a point on the orthogonal section of the trajectory.

[0089] Furthermore, the small holes on the combustion chamber wall are removed, and numerical calculations are performed to obtain the pressure difference distribution inside and outside the combustion chamber wall. The specific content of the mass flow at each position is obtained according to the pressure difference distribution:

[0090] Assuming that the inner wall pressure at the orifice outlet is P, and the corresponding outer wall pressure is P0, the formula for mass flow is:

[0091]

[0092] Among them, C D is the flow coefficient, γ is the specific heat capacity, R is the gas constant, T0 is the outer wall temperature, and D is the pore diameter.

[0093] Furthermore, the small hole jet is introduced into the numerical calculation software as a source term, and the specific contents of mass flow rate, momentum and temperature in the small volume of the jet are defined as follows:

[0094] The mass source is defined in a finite volume near the hole outlet. By applying velocity and temperature values, the three-dimensional velocity field and temperature field are simulated in the source volume. After the source term is introduced, the continuity equation, momentum equation, and energy equation are:

[0095]

[0096]

[0097]

[0098] Among them, S MS is the mass source, u MS,i is the velocity component of the mass source, E MS is the total energy of the mass source, ρ is the density of the cooling jet, t is the time, u is the velocity, x is the coordinate, τ is the shear stress, E is the total energy, is the heat flux, i, j are directions;

[0099] The formulas for total energy and specific internal energy are as follows:

[0100]

[0101] e=(c p -R)T

[0102] Among them, c p is the specific heat capacity at constant pressure, ρ is the density of the cooling jet, e is the specific internal energy, u is the velocity, i is the direction, and E is the total energy.

[0103] Furthermore, the simulation calculation of the non-porous geometry is carried out according to the small hole jet model, and the specific contents of the temperature field, pressure field and wall temperature distribution information in the combustion chamber are obtained as follows:

[0104] The non-porous geometry is meshed, the small holes are removed and the small hole circular surface is retained, and the small hole circular surface is encrypted. The encryption coefficient R' is defined as follows:

[0105]

[0106] Among them, dx is the encrypted size of the circular surface of the small hole, and D is the hole diameter;

[0107] For the combustion chamber model without the small holes, the parameters input to the film cooling model include:

[0108] Basic parameters: small hole coordinates, small hole inclination angle, small hole deflection angle, aperture, porosity, cooling air flow temperature, cooling air flow density;

[0109] Flow trajectory parameters: relative offset Y, relative reference Y', relative reference Z, coefficient A Y , A Z , B Y , B Z 、Effective azimuth angle θ real ;

[0110] Flow shape parameters: Fourier coefficients a0, a1, a2, b1, b2;

[0111] Temperature distribution parameters: coefficients A, B;

[0112] Mass flow parameters: inner wall pressure P at the orifice outlet, outer wall pressure P0, flow coefficient C D , specific heat capacity γ, gas constant R, outer wall temperature T0;

[0113] Perform numerical simulation of non-porous geometry and obtain the flow field and temperature field information of the non-porous geometry in post-processing.

[0114] See the following examples:

[0115] Embodiment 1:

[0116] The calculation was carried out with reference to the experimental device parameters and working conditions in the public literature. The air film cooling modeling method was used in this embodiment. The geometry consists of the main flow channel, the secondary flow channel and the side wall of the small hole. First, the unstructured grid is divided for the geometry with holes. Through the grid independence verification, the geometry with holes is 3.35 million grids. The small holes and the secondary flow channel are removed, and the rest are divided into grids of the same size. The encryption coefficient is R'=3, and the geometry without holes is 1.05 million grids. Simulation calculations are performed. Figure 2 The results show that there is a significant error between the experimental and simulation values ​​when x / D≤30, which may be due to the influence of the experimental conditions not being completely adiabatic. When x / D>30, the simulation results are in good agreement with the experimental results, and the cooling efficiency of the non-porous geometry and the porous geometry also maintains good consistency.

[0117] Embodiment 2:

[0118] Numerical calculations were performed on the working conditions of a combustion chamber of an engine. The combustion chamber in this embodiment contains 870 cooling holes with a hole diameter of 1 mm. Unstructured grids were divided for the combustion chamber fluid domain. Through grid independence verification, the number of grids for the complete hole geometry was 10.49 million. For the non-porous geometry, the small holes on the wall were removed, and the rest of the grids were divided into grids of the same size. The encryption coefficients were R'=2, 3, and 4, and the number of grids was 5.56 million, 7.44 million, and 9.5 million, respectively. Simulation calculations were performed. Figure 3 , Figure 4 The results show that the hole-free geometry basically restores the internal temperature field and outlet temperature field of the combustion chamber, and the density coefficient has no obvious effect. Figure 5 The results show that the non-porous geometry can restore the temperature distribution trend along the wall, but because the combustion degree in the second half of the non-porous combustion chamber is more intense, there are no cooling holes at the front end of the combustion chamber, so the wall temperature of the non-porous geometry in the front area of ​​the porous wall is slightly higher than that of the complete hole geometry. In general, the results of the non-porous geometry are well consistent with those of the porous geometry, and this method is a good modeling of the film cooling of the combustion chamber wall.

[0119] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0120] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A numerical simulation method for film cooling modeling, characterized in that: The following steps are involved: Numerical calculations of the plate with holes were performed under different flow parameters and hole structure parameters to obtain simulation data under different working conditions; The simulation data of the plate with holes is used to establish mathematical equations to describe the flow characteristics in a small volume of the jet; Remove the small holes on the combustion chamber wall, perform numerical calculations, obtain the pressure difference distribution inside and outside the combustion chamber wall, and obtain the mass flow rate at each position based on the pressure difference distribution; The small hole jet is introduced into the numerical calculation software as a source term, and the mass flow rate, momentum and temperature are defined in the small volume of the jet; Based on the small hole jet model, simulation calculation of non-hole geometry is carried out to obtain the temperature field, pressure field and wall temperature distribution information in the combustion chamber.

2. A numerical simulation method for film cooling modeling according to claim 1, characterized in that: The numerical calculation of the plate with holes is carried out under different typical flow parameters and hole structure parameters, and the specific contents of the data obtained under different working conditions are as follows: According to the working conditions of the aircraft engine, the flow parameters are set, and the hole structure parameters are selected. Numerical simulation is performed on the flat plate wall to obtain simulation data under different working conditions, providing a numerical basis for the modeling of small hole jets. The flow parameters include the velocity ratio, density ratio, blowing ratio, and momentum ratio of the small hole jet to the mainstream; the hole structure parameters include the hole geometry, hole inclination angle, deflection angle, and aspect ratio.

3. The numerical simulation method for film cooling modeling according to claim 1 is characterized in that: The mathematical equations are established using the simulation data of the plate with holes to describe the flow characteristics in a small volume of the jet: The mathematical equations describe the flow characteristics in a small volume of the jet, including: flow trajectory, flow shape, momentum distribution and temperature distribution; The generalized solution based on the force balance on the infinitesimal volume of the jet is used to describe the penetration height of the jet into the mainstream. The specific expression is: Assuming that the jet is a flat plate flow, the upper and lower parts of the flat plate are respectively the mainstream and cooling air flow channels, the jet enters the mainstream from the outlet surface, the origin is the center of the outlet surface, the x-axis points to the direction of the mainstream, the y-axis direction is the span direction of the flat plate, and the z-axis is perpendicular to the orifice outlet plane, then x is the x-coordinate; ψ, when the equation is solved for the y-coordinate of the trajectory, it represents y, and when the equation is solved for the z-coordinate of the trajectory, it represents z; x0 / D, when the y-coordinate of the trajectory is solved, it is the relative offset Y, and when the z-coordinate of the trajectory is solved, it is 0; ψ0 / D, when the y-coordinate of the trajectory is solved, it is the relative reference Y', and when the z-coordinate of the trajectory is solved, it is the relative reference Z; A ψ , when solving for the y coordinate of the trajectory, it is the coefficient A Y , when solving for the z coordinate of the trajectory, it is the coefficient A Z ; B ψ , which is the coefficient B when solving the coordinates of the trajectory Y , which is the coefficient B when solving for the z coordinate of the trajectory Z θ real is the effective azimuth angle, which is 0 when solving for the y coordinate of the trajectory and is the effective elevation angle when solving for the z coordinate of the trajectory, as the angle in the local xz plane; D is the aperture; IR is the momentum ratio; cot 2 is the cotangent trigonometric function; The flow shape of the jet is expressed by a truncated Fourier series: in, a is the radius of a point on the cross-sectional shape in the direction of the jet, and the cross-sectional shape is always perpendicular to the direction of the jet; i , b i are the coefficients of the Fourier series; assuming that the orifice outlet surface is a horizontal plane, set the local coordinate system that moves with the jet, and the origin of the coordinate is always at the center of the jet cross section, x s The y axis always points to the direction of the jet. s The axis is always parallel to the orifice outlet surface, then α s is the local y s -z s The angle of the plane, from y s The axis starts measuring; According to the continuity theorem, the velocity of the small hole jet is obtained: Among them, v is the small hole jet velocity, m is the mass flow rate of each small hole per unit time, ρ is the density of the cooling jet, and D is the aperture; The temperature distribution on the orthogonal section of the trajectory is given in the form of a quadratic function: Among them, A, B, C are coefficients, r s is the radius at a point on the orthogonal section of the trajectory, and T is the jet temperature at a point on the orthogonal section of the trajectory.

4. The numerical simulation method for film cooling modeling according to claim 1 is characterized in that: Remove the small holes on the combustion chamber wall, perform numerical calculations, and obtain the pressure difference distribution inside and outside the combustion chamber wall. The specific content of the mass flow at each position is obtained based on the pressure difference distribution: Assuming that the inner wall pressure at the orifice outlet is P, and the corresponding outer wall pressure is P0, the formula for mass flow is: Among them, C D is the flow coefficient, γ is the specific heat capacity, R is the gas constant, T0 is the outer wall temperature, and D is the pore diameter.

5. The numerical simulation method for film cooling modeling according to claim 1 is characterized in that: The small hole jet is introduced into the numerical calculation software as a source term, and the specific contents of mass flow rate, momentum and temperature in the small volume of the jet are defined as follows: The mass source is defined in a finite volume near the hole outlet. By applying velocity and temperature values, the three-dimensional velocity field and temperature field are simulated in the source volume. After the source term is introduced, the continuity equation, momentum equation, and energy equation are: in, is the mass source, u MS,i is the velocity component of the mass source, E MS is the total energy of the mass source, ρ is the density of the cooling jet, t is the time, u is the velocity, x is the coordinate, τ is the shear stress, E is the total energy, is the heat flux, i, j are directions; The formulas for total energy and specific internal energy are as follows: e=(c p -R)T Among them, c p is the specific heat capacity at constant pressure, ρ is the density of the cooling jet, e is the specific internal energy, u is the velocity, i is the direction, and E is the total energy.

6. The numerical simulation method for film cooling modeling according to claim 1, characterized in that: According to the small hole jet model, the simulation calculation of the non-hole geometry is carried out to obtain the temperature field, pressure field and wall temperature distribution information in the combustion chamber: The non-porous geometry is meshed, the small holes are removed and the small hole circular surface is retained, and the small hole circular surface is encrypted. The encryption coefficient R' is defined as follows: Among them, dx is the encrypted size of the circular surface of the small hole, and D is the hole diameter; For the combustion chamber model without the small holes, the parameters input to the film cooling model include: Basic parameters: small hole coordinates, small hole inclination angle, small hole deflection angle, aperture, porosity, cooling air flow temperature, cooling air flow density; Flow trajectory parameters: relative offset Y, relative reference Y', relative reference Z, coefficient A Y , A Z , B Y , B Z 、Effective azimuth angle θ real ; Flow shape parameters: Fourier coefficients a0, a1, a2, b1, b2; Temperature distribution parameters: coefficients A, B; Mass flow parameters: inner wall pressure P at the orifice outlet, outer wall pressure P0, flow coefficient C D , specific heat capacity γ, gas constant R, outer wall temperature T0; Perform numerical simulation of non-porous geometry and obtain the flow field and temperature field information of the non-porous geometry in post-processing.

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