A flow coefficient calculation method suitable for turbine blade expansion type film holes

Abstract

The application provides a flow coefficient calculation method suitable for turbine blade expansion type film holes, and belongs to the technical field of turbine blade cooling of an aero-engine. The geometric characteristics of a theoretical expansion type film hole are processed by combining the actual expansion type film hole of a turbine blade, the geometric characteristics of the film hole for theoretical flow calculation are obtained, the flow field parameters of the actual film hole inlet and outlet are combined, the isentropic theoretical flow field parameters at the joint surface of the film hole are obtained through theoretical formula derivation, the theoretical flow of the expansion type film hole cylindrical section is obtained, the theoretical flow of the theoretical expansion type film hole is replaced by the theoretical flow of the actual expansion type film hole, and the flow coefficient of the more accurate expansion type film hole is obtained.

Description

Technical Field

[0001] This application relates to the field of cooling turbine blades for aero-engines, and in particular to a method for calculating the flow coefficient of an expansion film orifice for turbine blades. Background Technology

[0002] In the design of aero-engines, increasing the inlet gas temperature is a crucial way to improve engine performance. Currently, the allowable temperature of turbine blade materials in advanced aero-engines is lower than the turbine inlet gas temperature, and the rate of increase in turbine inlet gas temperature far exceeds the rate of increase in material temperature resistance. Therefore, advanced and efficient cooling design is essential for the safe and reliable operation of turbine blades. Film cooling (FSK) is a widely used and highly efficient cooling technology for the exterior of turbine blades. It works by jetting cooler gas from film orifices to form a thin film of cooling air covering the turbine blade surface, isolating the high-temperature gas stream from convective cooling of the blade. Over time, FSD technology has evolved from simple, easily machined cylindrical orifices to more complex and sophisticated profiles. One type of FSD with an expanding outlet is widely used in current turbine blade cooling designs. This type of FSD includes interconnected cylindrical and expanding sections. This complex orifice design allows for better control of the cooling airflow trajectory and coverage, improving cooling efficiency and reducing aerodynamic losses.

[0003] During the actual flow of cold air through the film gas vents, flow losses cause the actual flow rate of the cold air to be lower than the theoretical flow rate under the same operating conditions. This leads to the formula for calculating the flow coefficient: ,in, For flow coefficient, This represents the actual traffic volume. This is the isentropic theoretical flow rate.

[0004] The flow coefficient directly reflects the strength of the film cooling capacity of the orifice. During the film cooling orifice design phase, the flow coefficient serves as an auxiliary parameter. While ensuring film cooling efficiency, selecting an orifice structure with a high flow coefficient can help reduce aerodynamic losses and outflow resistance of the cooled air. Furthermore, the flow coefficient is related to the actual flow rate of the film jet. Under real turbine blade operating conditions, the actual cooled air flow rate directly determines the actual blowing ratio and momentum ratio of the film cooling orifice, thus affecting the film cooling effect under actual operating conditions. Therefore, accurately obtaining the flow coefficient of the film cooling orifice is of great significance for film cooling design research.

[0005] Existing technologies, such as Chinese patent application No. CN2023102549012 and publication No. CN116296330A, disclose a method for measuring the flow coefficient of a single exhaust film cooling hole on a turbine blade profile and its application. In the test process, according to the total number of single exhaust film holes to be measured, corresponding pressure and temperature detection points are arranged at the inlet and outlet positions of the film holes. The test data are weighted and averaged, and the actual flow rate of the single exhaust film hole is obtained by a cold air thermal flow meter. Combined with the geometric parameters of the single exhaust film hole to be measured, the required flow coefficient of the single exhaust film hole is obtained. However, this method of measuring and calculating the flow coefficient is mainly applicable to traditional cylindrical film holes. When facing the widely used and researched expanding film holes, it will lead to inaccurate flow coefficient calculation results, excessive deviation of theoretical flow rate, and even the actual flow rate being higher than the theoretical isentropic flow rate.

[0006] For example, the prior art Chinese patent application document with patent number CN2023108074801 and publication number CN116522826A discloses a method and system for predicting the state flow of a turbine blade engine. Based on the characteristics of the airflow in the blade, the turbine blade is divided into multiple regions. The relationship between the flow test and the state flow of the engine is established through each region, thereby calculating the first actual flow of each region. Then, the one-dimensional internal flow calculation model is corrected based on the first actual flow and the theoretical flow to obtain the corrected one-dimensional internal flow prediction model of the state flow of the engine in each region. However, the method for calculating the flow coefficient of the film orifice is mainly for traditional cylindrical film orifices and cannot solve the problems encountered in calculating the flow coefficient of the new expansion film orifice. Summary of the Invention

[0007] In view of this, this application provides a method for calculating the flow coefficient of an expanding film orifice for turbine blades, which solves the problems in the prior art and improves the calculation accuracy of the flow coefficient of the expanding film orifice.

[0008] The flow coefficient calculation method for expanded film gas holes in turbine blades provided in this application adopts the following technical solution:

[0009] A method for calculating the flow coefficient of an expanded film gas orifice for turbine blades includes the following steps:

[0010] Obtain the geometric design structure of the theoretically expanded film pore;

[0011] Based on the geometric design structure of the theoretical expansion film orifice, determine the inlet section b1 corresponding to the inlet position of the actual expansion film orifice and the outlet section c1 corresponding to the outlet position of the actual expansion film orifice. The inlet section b1 and the outlet section c1 are perpendicular to the axial direction of the cylindrical section of the theoretical expansion film orifice.

[0012] Determine the theoretical interface a1 between the cylindrical section and the expansion section of the theoretically expanded film pore;

[0013] Calculate the area of ​​inlet section b1. A in Area of ​​the outlet section c1 A out Area of ​​the theoretical interface a1 A mid ,in, A in = A mid ;

[0014] The total inlet pressure of the actual expanded film vent was measured under preset operating conditions through experiments. Actual total inlet temperature of the expanded film gas vent Actual expansion film orifice outlet static pressure value P and the actual cooling air flow rate of the expanded film vent. ;

[0015] Based on the laws of mass conservation and isentropic theory, and combined with the area of ​​the exit section c1... A out Area of ​​the interface a1 with the theory A mid The static pressure value at the theoretical interface a1 position was calculated. P mid ;

[0016] Based on the isentropic theory, the geometric parameters of the theoretical interface a1, and the static pressure value P mid Calculate the theoretical flow rate of the cylindrical section of the theoretically expanded film gas orifice. ;

[0017] The theoretical flow rate of the cylindrical section of the theoretically expanded film orifice The theoretical flow rate of the actual expanding film pore is used to calculate the flow coefficient. .

[0018] Optionally, the method for determining the inlet cross-section b1 corresponding to the actual inlet position of the expanding film gas hole based on the geometric design structure of the theoretical expanding film gas hole is as follows:

[0019] Determine the actual central axis L of the actual expanding film orifice cylindrical section, the actual contact surface a between the actual expanding film orifice cylindrical section and the expanding section, the inlet surface b of the actual expanding film orifice cylindrical section, the intersection point B of the actual central axis L and the inlet surface b, and the intersection point A of the actual central axis L and the contact surface a.

[0020] Calculate the distance between intersection point A and intersection point B;

[0021] Determine the theoretical central axis L1 of the cylindrical segment of the theoretical expansion-type air film aperture, and the intersection point A1 of the theoretical central axis L1 and the theoretical contact surface a1;

[0022] Determine point B1 on the theoretical central axis L1 on the cylindrical segment of the theoretical expansion film orifice. The distance between the intersection point A1 and point B1 is equal to the distance between the intersection point A and the intersection point B.

[0023] The section on the cylindrical segment of the theoretically expanded film air hole that passes through point B1 and is perpendicular to the central axis L1 is the inlet section b1.

[0024] Optionally, the inlet surface b of the actual expanding film gas hole cylindrical section is the design profile of the turbine blade inner wall at the inlet position of the film gas hole.

[0025] Optionally, the method for determining the outlet section c1 corresponding to the actual outlet position of the expanding film gas hole based on the geometric design structure of the theoretical expanding film gas hole is as follows:

[0026] Determine the actual central axis L of the cylindrical section of the expanding film orifice, the actual contact surface a between the actual cylindrical section and the expansion section of the expanding film orifice, the outlet surface c of the expansion section of the actual expanding film orifice, the intersection point C of the actual central axis L and the outlet surface c, and the intersection point A of the actual central axis L and the actual contact surface a.

[0027] Calculate the distance between intersection point A and intersection point C;

[0028] Determine the theoretical central axis L1 of the cylindrical segment of the theoretical expansion-type air film aperture, and the intersection point A1 of the theoretical central axis L1 and the theoretical contact surface a1;

[0029] Determine point C1 on the theoretical central axis L1 on the expansion section of the theoretical expansion-type film pore, and the distance between intersection points A1 and C1 is equal to the distance between intersection points A and C;

[0030] The cross section passing through point C1 and perpendicular to the central axis L on the expansion section of the theoretical expansion-type film vent is the outlet cross section c1.

[0031] Optionally, the outlet surface c of the actual expanding film perforation expansion section is the design profile on the outer wall of the turbine blade at the outlet position of the film perforation.

[0032] Optionally, the static pressure value at the theoretical contact surface a1 can be calculated. P mid Specific methods include:

[0033] Based on the theoretical cold air flow rate at the outlet section c1 of the theoretical expansion film orifice being equal to the theoretical cold air flow rate at the theoretical contact surface a1 of the theoretical expansion film orifice, and the measured total inlet pressure of the actual expansion film orifice, the following calculations are made. The total pressure at the outlet section c1 and the theoretical interface a1 of the theoretical expanding film orifice, and the measured total inlet temperature of the actual expanding film orifice. The first formula is established based on the total temperature at the outlet section c1 of the theoretically expanded film pore and the theoretical interface a1:

[0034] ;

[0035] Based on the total pressure and static pressure values ​​at the outlet section c1 of the theoretically expanded film orifice. P out Establish the second formula:

[0036] ;

[0037] Based on the total pressure and static pressure values ​​at the theoretical interface a1 position of the theoretically expanded film pore. P mid Establish the third formula:

[0038] ;

[0039] in, It is a constant. , The Mach number at position a1, the theoretical contact surface of the theoretically expanded film pore. The Mach number at the outlet section c1 of the theoretically expanded film gas orifice. , , A mid Let a1 be the area of ​​the theoretical contact surface. Let c1 be the area of ​​the outlet section. k It is the specific heat capacity ratio. R It is the gas constant. Z It is the gas compressibility factor under the imported gas parameters. P out Equal to the actual static pressure value at the outlet of the expanding film orifice P ;

[0040] The theoretical static pressure value of the theoretical interface a1 is calculated by combining the first, second, and third formulas. P mid .

[0041] Optionally, calculate the theoretical flow rate of the theoretically expanded film orifice. The formula is:

[0042] ;

[0043] In the formula, A mid Let a1 be the area of ​​the theoretical contact surface.P mid This represents the static pressure at position a1, the theoretical interface of the theoretically expanded film gas pore. This represents the total inlet pressure of the actual expanding film gas vent. This represents the actual total inlet temperature of the expanded film gas vent. k It is the specific heat capacity ratio. R It is the gas constant. Z It is the gas compressibility factor under the parameters of the imported gas.

[0044] In summary, this application includes the following beneficial technical effects:

[0045] The flow coefficient calculation method for expanded film orifices of turbine blades proposed in this application improves the calculation method by combining the geometric feature processing of theoretical expanded film orifices with the actual expanded film orifices of turbine blades, thereby increasing the calculation accuracy of the flow coefficient of expanded film orifices and solving the problem that the actual flow rate is higher than the theoretical flow rate due to excessive deviation in the calculation of theoretical isentropic flow rate. This supports the refined design of expanded film orifices of turbine blades. Attached Figure Description

[0046] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0047] Figure 1 A schematic diagram of the structure of an expanded film cooling hole in a turbine blade;

[0048] Figure 2 This is a schematic diagram of the actual expansion film orifice profile;

[0049] Figure 3 This is a schematic diagram showing the relevant geometric parameters of the theoretical and actual expanding film pores.

[0050] Explanation of reference numerals in the attached diagram: 2. Blade; 3. Actual expanding film vent; 31. Cylindrical section; 32. Expanding section. Detailed Implementation

[0051] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0052] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0053] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this application, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0054] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this application. The illustrations only show the components related to this application and are not drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0055] Furthermore, specific details are provided in the following description to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that the described aspects can be practiced without these specific details.

[0056] like Figure 1 and Figure 2 As shown, this application provides a method for calculating the flow coefficient of an expanding film gas hole for turbine blades. The actual expanding film gas hole 3 of the turbine blade 2 includes a cylindrical section 31 and an expanding section 32, which are distributed sequentially along the outer side of the inner side of the blade 2.

[0057] A method for calculating the flow coefficient of an expanded film gas orifice for turbine blades includes the following steps:

[0058] Obtain the geometric design structure of the theoretical expansion film orifice; in the process of designing the expansion film orifice of turbine blade 2, a combined geometric structure of interconnected cylindrical and expansion sections is first designed. Generally, the two ends of this geometric structure will penetrate the inner and outer walls of turbine blade 2, and the two ends of the theoretical geometric structure will intersect and not be flush with the inner and outer walls of turbine blade 2. Then, the relative positional relationship between the geometric structure and turbine blade 2 is adjusted according to the specific film orifice design on turbine blade 2. Finally, the profiles of the inner and outer walls of turbine blade 2 are cut from the geometric structure, and the part of the geometric structure corresponding to the profiles of the inner and outer walls of turbine blade 2 is taken as the actual structure of the film orifice. The inlet surface of the actual film orifice matches the profile of the inner wall of turbine blade 2, and the outlet surface of the actual film orifice matches the profile of the outer wall of turbine blade 2. Therefore, the actual expanding film pore 3 is cut from the geometric structure of the theoretical expanding film pore, which is a pre-designed complete geometric structure of the actual expanding film pore 3.

[0059] like Figure 3 As shown, based on the geometric design structure of the theoretical expansion film orifice, the inlet section b1 corresponding to the inlet position of the actual expansion film orifice 3 and the outlet section c1 corresponding to the outlet position of the actual expansion film orifice 3 are determined. The inlet section b1 and the outlet section c1 are perpendicular to the axial direction of the cylindrical section of the theoretical expansion film orifice.

[0060] Determine the theoretical interface a1 between the cylindrical section and the expansion section of the theoretically expanded film pore.

[0061] Calculate the area of ​​inlet section b1. A in Area of ​​the outlet section c1 A out Area of ​​the theoretical interface a1 A mid ,in, A in = A mid .

[0062] The total inlet pressure of the actual expanded film orifice 3 under preset operating conditions was measured by experiment. Actual total inlet temperature of the expanded film gas vent 3 Actual expansion film gas outlet static pressure value P and the actual cooling air flow rate of the expanded film vent. .

[0063] Based on the laws of mass conservation and isentropic theory, and combined with the area of ​​the exit section c1... A out Area of ​​the interface a1 with the theory Amid The static pressure value at the theoretical interface a1 position was calculated. P mid .

[0064] Based on the isentropic theory, the geometric parameters of the theoretical interface a1, and the static pressure value P mid Calculate the theoretical flow rate of the cylindrical section of the theoretically expanded film gas orifice. .

[0065] The theoretical flow rate of the cylindrical section of the theoretically expanded film orifice The flow coefficient was calculated based on the theoretical flow rate of the actual expanding film orifice 3. .

[0066] When the expanded film orifice is actually applied to turbine blade 2, considering the installation tilt angle and guide angle of the film orifice, the inlet and outlet of the expanded film orifice will exhibit irregular geometric shapes, making it difficult to perform direct theoretical analysis and calculation. Moreover, in the experimental measurement of the flow coefficient of the traditional cylindrical film orifice, the flow field parameters at the outlet and inlet of the film orifice are relatively easy to obtain. According to the flow coefficient calculation formula, during the experiment, only the total temperature of the cold air at the inlet of the film orifice needs to be obtained. Imported air conditioning total pressure Mainstream export static pressure P Combined with the measured air film pore flow area A This allows us to calculate the theoretical flow rate of the film air vent. Then, based on the actual flow rate measured in the experiment... The actual flow coefficient of the film gas can be calculated. However, this calculation method will produce a large deviation from the theoretical flow rate for expanding film gas, and may even result in the actual flow rate being higher than the theoretical isentropic flow rate, leading to low accuracy of the flow coefficient. This is mainly because, under the isentropic theory, the expansion section of the expanding film gas will cause a change in the pressure field of the jet cooling gas.

[0067] This application calculates the flow coefficient of an expanding film orifice for the cylindrical section, thereby avoiding the problem of actual flow rate exceeding theoretical isentropic flow rate and improving the accuracy of flow coefficient calculation. Typically, when experimentally measuring the flow field parameters of a film orifice, it is easy to obtain values ​​at the inlet and outlet positions. However, if experimental measurements are performed on the cylindrical section of an expanding film orifice, it becomes difficult to directly obtain the flow field parameters at the outlet position of the cylindrical section. This is because the actual internal dimensions of the film orifice are too small, making it difficult to arrange a measuring probe inside, and the measuring device would significantly affect the original flow field within the film orifice. Therefore, this application obtains the geometric features of the film orifice for theoretical flow rate calculation by projecting the positions of the inlet and outlet surfaces of the theoretical expanding film orifice 3 corresponding to those of the actual expanding film orifice 3 onto a plane perpendicular to the central axis. Combined with the flow field parameters of the inlet and outlet of the actual film orifice, the isentropic theoretical flow field parameters at the interface of the film orifice are derived through theoretical formulas. This yields the theoretical flow rate of the cylindrical section of the expanding film orifice. The theoretical flow rate of the theoretical expanding film orifice is then used to replace the theoretical flow rate of the actual expanding film orifice 3 to obtain a more accurate flow coefficient for the expanding film orifice.

[0068] Specifically: In order to determine the inlet section b1 and the outlet section c1, first determine the actual central axis L of the actual expanding film orifice 3 cylindrical section 31, the actual contact surface a of the actual expanding film orifice 3 cylindrical section 31 and the expansion section 32; determine the theoretical central axis L1 of the theoretical expanding film orifice cylindrical section, and the intersection point A1 of the theoretical central axis L1 and the theoretical contact surface a1.

[0069] The method for determining the inlet section b1 is as follows:

[0070] Determine the intersection point B of the inlet face b of the actual expansion-type film air hole 3 cylindrical section 31, the actual central axis L and the inlet face b, and the intersection point A of the actual central axis L and the contact surface a; calculate the distance between intersection point A and intersection point B;

[0071] Determine point B1 on the theoretical expansion film orifice cylindrical section located on the theoretical central axis L1. The distance between intersection point A1 and point B1 is equal to the distance between intersection point A and intersection point B. The section on the theoretical expansion film orifice cylindrical section passing through point B1 and perpendicular to the central axis L1 is the inlet section b1.

[0072] Among them, the inlet surface b of the cylindrical section 31 of the actual expansion film orifice 3 is the design surface of the inner wall of the turbine blade 2 at the inlet position of the film orifice.

[0073] The method for determining the outlet section c1 is as follows:

[0074] Determine the intersection point C of the actual expansion section 32 of the expansion-type film air hole 3, the actual central axis L, and the actual contact surface a; calculate the distance between intersection point A and intersection point C.

[0075] Point C1 on the theoretical central axis L1 of the expansion section of the theoretical expansion-type film cooling orifice is determined. The distance between intersection points A1 and C1 is equal to the distance between intersection points A and C. The cross section on the expansion section of the theoretical expansion-type film cooling orifice, passing through point C1 and perpendicular to the central axis L, is the outlet cross section c1. The outlet surface c of the actual expansion section 32 of the film cooling orifice 3 is the design profile on the outer wall of the turbine blade 2 at the outlet position of the film cooling orifice.

[0076] The static pressure value at the theoretical interface a1 position was calculated. P mid Specific methods include:

[0077] Based on the theoretical cold air flow rate at the outlet section c1 of the theoretical expansion film orifice being equal to the theoretical cold air flow rate at the theoretical contact surface a1 of the theoretical expansion film orifice, and the measured total inlet pressure of the actual expansion film orifice 3, the following calculations are made. The total pressure at the outlet section c1 and the theoretical interface a1 of the theoretically expanded film orifice, and the measured total inlet temperature of the actual expanded film orifice 3, will be used as the basis for this measurement. The first formula is established based on the total temperature at the outlet section c1 of the theoretically expanded film pore and the theoretical interface a1:

[0078] ;

[0079] Based on the total pressure and static pressure values ​​at the outlet section c1 of the theoretically expanded film orifice. P out Establish the second formula:

[0080] ;

[0081] Based on the total pressure and static pressure values ​​at the theoretical interface a1 position of the theoretically expanded film pore. P mid Establish the third formula:

[0082] ;

[0083] in, It is a constant. , The Mach number at position a1, the theoretical contact surface of the theoretically expanded film pore. The Mach number at the outlet section c1 of the theoretically expanded film gas orifice. , , A mid Let a1 be the area of ​​the theoretical contact surface. Let c1 be the area of ​​the outlet section. k It is the specific heat capacity ratio. R It is the gas constant. ZIt is the gas compressibility factor under the imported gas parameters. P out Equal to the actual static pressure value at the outlet of the expanding film orifice P ;

[0084] The theoretical static pressure value of the theoretical interface a1 is calculated by combining the first, second, and third formulas. P mid .

[0085] in, H According to k, R The calculated constant value, , and P This was obtained from actual measurements. and This will be eliminated in the calculation; therefore, by combining the first, second, and third formulas, the theoretical static pressure value of the theoretical interface a1 can be calculated. P mid .

[0086] Calculate the theoretical flow rate of the theoretically expanded film orifice. The formula is:

[0087] ;

[0088] In the formula, A mid Let a1 be the area of ​​the theoretical contact surface. P mid This represents the static pressure at position a1, the theoretical interface of the theoretically expanded film gas pore. This represents the total inlet pressure of the actual expanding film gas vent. This represents the actual total inlet temperature of the expanded film gas vent. k It is the specific heat capacity ratio. R It is the gas constant. Z It is the gas compressibility factor under the parameters of the imported gas.

[0089] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for calculating the flow coefficient of an expanding film gas orifice for turbine blades, characterized in that, Includes the following steps: Obtain the geometric design structure of the theoretically expanded film pore; Based on the geometric design structure of the theoretical expansion film orifice, determine the inlet section b1 corresponding to the inlet position of the actual expansion film orifice and the outlet section c1 corresponding to the outlet position of the actual expansion film orifice. The inlet section b1 and the outlet section c1 are perpendicular to the axial direction of the cylindrical section of the theoretical expansion film orifice. Determine the theoretical interface a1 between the cylindrical section and the expansion section of the theoretically expanded film pore; Calculate the area of ​​inlet section b1. A in Area of ​​the outlet section c1 A out The area of ​​the theoretical interface a1 A mid ,in, A in = A mid ; The total inlet pressure of the actual expanded film vent was measured under preset operating conditions through experiments. Actual total inlet temperature of the expanded film gas vent Actual expansion film orifice outlet static pressure value P and the actual cooling air flow rate of the expanded film vent. ; Based on the laws of mass conservation and isentropic theory, and combined with the area of ​​the exit section c1... A out Area of ​​the interface a1 with the theory A mid The static pressure value at the theoretical interface a1 position was calculated. P mid ; Based on the isentropic theory, the geometric parameters of the theoretical interface a1, and the static pressure value P mid Calculate the theoretical flow rate of the cylindrical section of the theoretically expanded film gas orifice. ; The theoretical flow rate of the cylindrical section of the theoretically expanded film orifice The theoretical flow rate of the actual expanding film pore is used to calculate the flow coefficient. ; The static pressure value at the theoretical interface a1 position was calculated. P mid Specific methods include: Based on the theoretical cold air flow rate at the outlet section c1 of the theoretical expansion film orifice being equal to the theoretical cold air flow rate at the theoretical contact surface a1 of the theoretical expansion film orifice, and the measured total inlet pressure of the actual expansion film orifice, the following calculations are made. The total pressure at the outlet section c1 and the theoretical interface a1 of the theoretical expanding film orifice, and the measured total inlet temperature of the actual expanding film orifice. The first formula is established based on the total temperature at the outlet section c1 of the theoretically expanded film pore and the theoretical interface a1: ； Based on the total pressure and static pressure values ​​at the outlet section c1 of the theoretically expanded film orifice. P out Establish the second formula: ； Based on the total pressure and static pressure values ​​at the theoretical interface a1 position of the theoretically expanded film pore. P mid Establish the third formula: ； in, It is a constant. , The Mach number at position a1, the theoretical contact surface of the theoretically expanded film pore. The Mach number at the outlet section c1 of the theoretically expanded film gas orifice. , , A mid Let a1 be the area of ​​the theoretical contact surface. Let c1 be the area of ​​the outlet section. k It is the specific heat capacity ratio. R It is the gas constant. Z It is the gas compressibility factor under the imported gas parameters. P out Equal to the actual static pressure value at the outlet of the expanding film orifice P ; The theoretical static pressure value of the theoretical interface a1 is calculated by combining the first, second, and third formulas. P mid .

2. The method for calculating the flow coefficient of an expanding film gas orifice for turbine blades according to claim 1, characterized in that, The method for determining the inlet cross section b1 corresponding to the actual inlet position of the theoretically expandable film orifice based on the geometric design structure of the orifice is as follows: Determine the actual central axis L of the actual expanding film orifice cylindrical section, the actual contact surface a between the actual expanding film orifice cylindrical section and the expanding section, the inlet surface b of the actual expanding film orifice cylindrical section, the intersection point B of the actual central axis L and the inlet surface b, and the intersection point A of the actual central axis L and the contact surface a. Calculate the distance between intersection point A and intersection point B; Determine the theoretical central axis L1 of the cylindrical segment of the theoretical expansion-type air film aperture, and the intersection point A1 of the theoretical central axis L1 and the theoretical contact surface a1; Determine point B1 on the theoretical central axis L1 on the cylindrical segment of the theoretical expansion film orifice. The distance between the intersection point A1 and point B1 is equal to the distance between the intersection point A and the intersection point B. The section on the cylindrical segment of the theoretically expanded film air hole that passes through point B1 and is perpendicular to the central axis L1 is the inlet section b1.

3. The method for calculating the flow coefficient of an expanding film gas orifice for turbine blades according to claim 2, characterized in that, The inlet surface b of the actual expanded film gas hole cylindrical section is the design profile of the inner wall of the turbine blade at the inlet position of the film gas hole.

4. The method for calculating the flow coefficient of an expanding film gas orifice for turbine blades according to claim 1, characterized in that, The method for determining the outlet section c1 corresponding to the actual outlet position of the theoretically expandable film air hole based on its geometric design is as follows: Determine the actual central axis L of the cylindrical section of the expanding film orifice, the actual contact surface a between the actual cylindrical section and the expansion section of the expanding film orifice, the outlet surface c of the expansion section of the actual expanding film orifice, the intersection point C of the actual central axis L and the outlet surface c, and the intersection point A of the actual central axis L and the actual contact surface a. Calculate the distance between intersection point A and intersection point C; Determine the theoretical central axis L1 of the cylindrical segment of the theoretical expansion-type air film aperture, and the intersection point A1 of the theoretical central axis L1 and the theoretical contact surface a1; Determine point C1 on the theoretical central axis L1 on the expansion section of the theoretical expansion-type film pore, and the distance between intersection points A1 and C1 is equal to the distance between intersection points A and C; The cross section passing through point C1 and perpendicular to the central axis L on the expansion section of the theoretical expansion-type film vent is the outlet cross section c1.

5. The method for calculating the flow coefficient of an expanding film gas orifice for turbine blades according to claim 4, characterized in that, The actual expansion section of the film gas hole, c, is the design profile on the outer wall of the turbine blade at the outlet position of the film gas hole.

6. The method for calculating the flow coefficient of an expanding film gas orifice for turbine blades according to claim 1, characterized in that, Calculate the theoretical flow rate of the theoretically expanded film orifice. The formula is: ； In the formula, A mid Let a1 be the area of ​​the theoretical contact surface. P mid This represents the static pressure at position a1, the theoretical interface of the theoretically expanded film gas pore. This represents the total inlet pressure of the actual expanding film gas vent. This represents the actual total inlet temperature of the expanded film gas vent. k It is the specific heat capacity ratio. R It is the gas constant. Z It is the gas compressibility factor under the parameters of the imported gas.

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