Gas film cooling efficiency measuring method and system based on parallel line light source scanning

Abstract

The invention discloses an air film cooling efficiency measurement method and system based on parallel line light source scanning, and relates to the technical field of aero-engine hot end component cooling characteristic measurement, and the method comprises the steps: obtaining a relational expression between light intensity and oxygen partial pressure after pressure sensitive paint is excited through calibration; spraying pressure sensitive paint to the surface of the model to be measured, constructing four specific scenes, scanning the surface of the model to be measured by using a parallel line light source in three of the scenes, and shooting by using a scientific camera to obtain a series of images; processing the series of images to obtain light intensity values of fluorescence emitted by the pressure sensitive paint under the four scenes; and calculating the surface air film cooling efficiency of the to-be-measured model based on the light intensity value and the relational expression. By means of parallel light source scanning and image processing, surrounding pressure-sensitive paint can be prevented from emitting fluorescent light, the influence of fluorescent light reflection on light intensity when a scientific camera is used for shooting is eliminated, and the deviation of measuring the cooling efficiency of the gas film through the pressure-sensitive paint is corrected.

Description

Technical Field

[0001] The invention belongs to the technical field of cooling characteristic measurement of hot end components of aircraft engines, and in particular relates to a method and system for measuring air film cooling efficiency based on parallel line light source scanning. Background Art

[0002] Turbine engines include ground gas turbines and aircraft engines, which have the advantages of high cycle efficiency. The working principle of turbine engines is based on the actual Brayton cycle, which determines that increasing the temperature before the turbine can directly improve the cycle efficiency. In current advanced aircraft engines, the temperature before the turbine far exceeds the temperature limit of the turbine blades for long-term operation, so efficient cooling technology is one of the important technologies of turbine engines. Among them, film cooling technology is widely used. It means opening discrete film holes on the solid surface to guide the cooling gas from the inner cavity to the outer wall surface in direct contact with the high-temperature combustion gas. Under the action of the mainstream high-temperature combustion gas, the cooling gas forms a thin film on the solid surface. The film temperature is lower than the mainstream combustion gas temperature, thereby isolating the high temperature.

[0003] Adiabatic film cooling efficiency, referred to as film cooling efficiency, is a dimensionless form of the temperature of the mixture of mainstream gas and cold air under the assumption that the solid wall is insulated. The film cooling efficiency directly represents the effectiveness of the film in isolating high temperatures and is an important parameter for evaluating the film cooling effect. A value of 1 indicates that the temperature of the insulation layer is equal to the cooling gas temperature, and the cooling effect is the best; a value of 0 indicates that the temperature of the insulation layer is equal to the mainstream temperature, and there is no cooling effect.

[0004] The measurement methods of air film cooling efficiency are mainly divided into heat transfer measurement method and mass transfer analogy method. Heat transfer measurement methods include steady-state and transient measurement methods. The measurement scenario is the solid surface temperature under heat exchange conditions, so it will inevitably be affected by heat conduction. The mass transfer analogy method uses the consistency of the mass transfer equation and the heat transfer equation, and uses the dimensionless results of material exchange instead of the dimensionless results of heat exchange, so the influence of heat conduction can be eliminated. Among them, pressure sensitive paint (PSP), referred to as pressure sensitive paint, can measure the oxygen partial pressure, so it can measure the mass transfer results, and is widely used in the measurement of air film cooling efficiency. Pressure sensitive paint is based on the oxygen quenching effect. After being irradiated with excited light, the surrounding oxygen partial pressure can be obtained by measuring the fluorescence intensity it emits. The pressure sensitive paint air film cooling efficiency measurement method based on mass transfer analogy heat transfer theory was first proposed by Zhang et al. in "Flat Plate Film Cooling Measurements using PSP Gas Chromatograph Techniques". The principle of using pressure sensitive paint to measure the efficiency of adiabatic film cooling can be briefly summarized as follows: use air as the mainstream, use a heterogeneous gas without oxygen as the jet, and use pressure sensitive paint to measure the mass fraction of the jet after the mainstream and the jet are mixed.

[0005] In the actual test process, four specific scenarios need to be constructed: The first scenario: turn off the excitation light, there is no flow, that is, a dark environment. The purpose is to eliminate the influence of the surrounding ambient light and obtain more accurate light intensity data. The second scenario: irradiate the excitation light, there is no flow. This condition is called the reference condition. Its purpose is to make the light intensity result dimensionless. The dimensionless light intensity has a certain relationship with the dimensionless oxygen partial pressure. The relationship between the two is obtained in the calibration test. The third scenario: irradiate the excitation light, set the mainstream to air and the jet to air. Its purpose is to obtain the local static pressure. The fourth scenario: irradiate the excitation light, set the mainstream to air and the jet to a heterogeneous gas without oxygen. Its purpose is to obtain the local oxygen partial pressure.

[0006] In all four scenes, the surface of the model to be tested sprayed with pressure-sensitive paint is photographed by a scientific camera to obtain a light intensity image. The two-dimensional image can be understood as a light intensity matrix, and two oxygen partial pressure matrices are obtained from the four light intensity matrices of the four groups of images, thereby calculating the film cooling efficiency result matrix. Therefore, for any point in the image, whether the light intensity result obtained by shooting is the true value of the fluorescence emitted by the pressure-sensitive paint becomes one of the decisive factors for whether the film cooling efficiency measurement result is accurate.

[0007] In the use scenarios of film cooling, there are some concave surfaces, including the pressure surface of the turbine blade and the inner surface of the outer casing; there are also some scenarios where multiple surfaces are relative, such as the turbine blade body and the turbine blade end wall, the turbine blade tip and the outer casing. In these scenarios, when the fluorescence intensity of the pressure-sensitive paint at a certain point is measured by a scientific camera, the fluorescence emitted by the pressure-sensitive paint at other locations will be diffusely reflected at that location and enter the scientific camera lens. The result obtained by the scientific camera is not the actual intensity of the fluorescence emitted by the local pressure-sensitive paint, which will cause measurement deviation.

[0008] In summary, in the process of measuring film cooling efficiency using pressure sensitive paint, the light intensity measurement deviation caused by fluorescence reflection will cause the film cooling efficiency result deviation, so the measurement method needs to be improved. Summary of the invention

[0009] The present invention aims to solve the deficiencies of the prior art and provides the following solutions:

[0010] A method for measuring film cooling efficiency based on parallel line light source scanning comprises the following steps:

[0011] The relationship between the light intensity and oxygen partial pressure of the pressure sensitive paint after being excited is obtained through calibration;

[0012] The pressure-sensitive paint is sprayed onto the surface of the model to be measured, and four specific scenes are constructed. In three of the scenes, a parallel line light source is used to scan the surface of the model to be measured, and a scientific camera is used to shoot to obtain a series of images; the four specific scenes include: a first scene: turning off the excitation light, no gas flow, corresponding to a dark environment; a second scene: irradiating the excitation light, no gas flow, corresponding to a reference condition; a third scene: irradiating the excitation light, setting the mainstream to air and the jet to air; a fourth scene: irradiating the excitation light, setting the mainstream to air and the jet to a heterogeneous gas without oxygen.

[0013] Processing the series of images to obtain light intensity values ​​of the fluorescence emitted by the pressure sensitive paint in four scenes;

[0014] Based on the light intensity value and the relationship, the surface film cooling efficiency of the model to be measured is calculated.

[0015] Preferably, the method for obtaining the relationship includes:

[0016] In the closed chamber, the pressure sensitive paint is irradiated with excitation light and the oxygen partial pressure in the closed chamber is continuously changed. The light intensity value and the oxygen partial pressure value are recorded to obtain the relationship:

[0017]

[0018] Among them, I ref Indicates the light intensity value under reference conditions, Indicates the oxygen partial pressure value under reference conditions, T ref represents the temperature value under reference conditions, I1 represents the light intensity value in a dark environment, x represents the conditions at a certain moment in the calibration process, and I x Indicates the light intensity value during the calibration process. It represents the oxygen partial pressure value during the calibration process, and f represents the functional relationship among the light intensity value, partial pressure value and temperature value.

[0019] Preferably, in the second scene, the third scene and the fourth scene, the parallel line light source is used to scan the surface of the model to be measured, the parallel line light source is scanned along the surface, and a scientific camera is used to take pictures during the scanning process to obtain a series of images.

[0020] Preferably, the method for processing the series of images includes:

[0021] Recording the light intensity results of the fluorescent area of ​​a single picture in the series of images;

[0022] The light intensity results of the series of images are spliced, the positions of the light intensity results are repeatedly recorded, and an average value of the light intensity results is taken to obtain the light intensity value.

[0023] Preferably, the method for calculating the surface film cooling efficiency includes:

[0024] The light intensity matrix captured in the first scene is used as the light intensity value I1 in the dark environment, and the light intensity matrix captured in the second scene is used as the light intensity value I1 under the reference condition. ref The light intensity matrix captured in the third scene is used as the light intensity value I3 in the third calibration process, the light intensity matrix captured in the fourth scene is used as the light intensity value I4 in the fourth calibration process, and the oxygen partial pressure matrix set under the reference condition is used as the oxygen partial pressure value Using the relationship to solve the oxygen partial pressure matrix under the third scenario The oxygen partial pressure matrix under the fourth scenario

[0025] Get the molecular weight W of the heterogeneous gas fg and the molecular weight W of the air air , and based on the oxygen partial pressure matrix under the third scenario And the oxygen partial pressure matrix under the fourth scenario Calculate the surface film cooling efficiency:

[0026]

[0027] Where η represents the surface film cooling efficiency.

[0028] The present invention also provides a film cooling efficiency measurement system based on parallel line light source scanning, wherein the measurement system applies any of the above-mentioned measurement methods and comprises: a calibration module, an image acquisition module, an image processing module and an efficiency calculation module;

[0029] The calibration module obtains the relationship between the light intensity and the oxygen partial pressure of the pressure sensitive paint after being excited by calibration;

[0030] The image acquisition module sprays the pressure-sensitive paint onto the surface of the model to be measured, and constructs four specific scenes, in which a parallel line light source is used to scan the surface of the model to be measured, and a scientific camera is used to shoot to obtain a series of images; the four specific scenes include: a first scene: turning off the excitation light, no gas flow, corresponding to a dark environment; a second scene: irradiating the excitation light, no gas flow, corresponding to a reference condition; a third scene: irradiating the excitation light, setting the mainstream to air and the jet to air; a fourth scene: irradiating the excitation light, setting the mainstream to air and the jet to a heterogeneous gas without oxygen;

[0031] The image processing module is used to process the series of images to obtain the light intensity values ​​of the fluorescence emitted by the pressure sensitive paint in four scenes;

[0032] The efficiency calculation module calculates the surface film cooling efficiency of the model to be measured based on the light intensity value and the relationship.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] The present invention utilizes parallel light source scanning and image processing to avoid the fluorescence of surrounding pressure-sensitive paint, eliminates the influence of fluorescence reflection on light intensity when shooting with a scientific camera, and corrects the deviation in measuring air film cooling efficiency using pressure-sensitive paint. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0036] Figure 1 A schematic diagram of a method flow of an embodiment of the present invention;

[0037] Figure 2 A schematic diagram of an experimental device according to an embodiment of the present invention;

[0038] Figure 3 A schematic diagram of processing an image obtained during a scanning process according to an embodiment of the present invention;

[0039] Figure 4 A schematic diagram of the system structure of an embodiment of the present invention;

[0040] Description of reference numerals:

[0041] 1. Un-irradiated area to be measured, 2. Excitation light irradiated area, 3. Non-measurement area, 4. Excitation light, 5. Main stream, 6. Scientific camera, 7. Air film hole, 8. Jet, 9. Excitation light source, 10. Light source scanning drive mechanism, 11. Measurement area. DETAILED DESCRIPTION

[0042] 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.

[0043] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0044] Embodiment 1

[0045] In this embodiment, if Figure 1 As shown, a method for measuring film cooling efficiency based on parallel line light source scanning includes the following steps:

[0046] S1. The relationship between the light intensity and oxygen partial pressure of the pressure sensitive paint after being excited is obtained through calibration.

[0047] The method for obtaining the relationship includes: in a closed chamber, using the excitation light 4 to illuminate the pressure sensitive paint and continuously changing the oxygen partial pressure in the closed chamber, recording the light intensity value and the oxygen partial pressure value, and obtaining the relationship:

[0048]

[0049] The calibration will set the reference conditions, which are usually atmospheric pressure conditions. ref Indicates the light intensity value under reference conditions, Indicates the oxygen partial pressure value under reference conditions, T ref represents the temperature value under reference conditions, I1 represents the light intensity value in a dark environment, x represents the conditions at a certain moment in the calibration process, and I x Indicates the light intensity value during the calibration process. It represents the oxygen partial pressure value during the calibration process, and f represents the functional relationship among the light intensity value, partial pressure value and temperature value.

[0050] S2. Spray pressure-sensitive paint onto the surface of the model to be measured, construct four specific scenes, use a parallel line light source to scan the surface of the model to be measured in three of the scenes, and use a scientific camera 6 to shoot to obtain a series of images; the four specific scenes include: the first scene: turn off the excitation light 4, there is no gas flow, corresponding to a dark environment; the second scene: irradiate the excitation light 4, there is no gas flow, corresponding to the reference condition; the third scene: irradiate the excitation light 4, set the mainstream 5 to air, and the jet 8 to air; the fourth scene: irradiate the excitation light 4, set the mainstream 5 to air, and the jet 8 to a heterogeneous gas without oxygen.

[0051] In the second scene, the third scene and the fourth scene, a parallel line light source is used to scan the measurement area 11 of the model to be measured, and the excitation light irradiation area 2 is the area in the measurement area 11 that is irradiated by the excitation light 4 and emits fluorescence. The unirradiated area 1 to be measured is the area in the measurement area 11 that is not irradiated by the excitation light 4 and does not emit fluorescence. During the scanning process, the scientific camera 6 at a fixed position is continuously used to take pictures until the scanning is completed to obtain a series of images.

[0052] S3. Process the series of images to obtain the light intensity values ​​of the fluorescence emitted by the pressure-sensitive paint in four scenes.

[0053] Methods for processing series of images include: Figure 3As shown, the light intensity results of the excitation light irradiation area 2 of a single picture in the series of images are recorded; the light intensity results of the series of images are spliced, the positions of the light intensity results are repeatedly recorded and the average value of the light intensity results is taken to obtain the light intensity value of the fluorescence emitted by the pressure sensitive paint in the measurement area 11 after being excited.

[0054] S4. Based on the light intensity value and the relationship, the surface film cooling efficiency of the model to be measured is calculated.

[0055] The method for calculating the surface film cooling efficiency includes: taking the light intensity matrix captured in the first scene as the light intensity value I1 in the dark environment, and taking the light intensity matrix captured in the second scene as the light intensity value I under the reference condition. ref The light intensity matrix captured in the third scene is used as the light intensity value I3 in the third calibration process, the light intensity matrix captured in the fourth scene is used as the light intensity value I4 in the fourth calibration process, and the oxygen partial pressure matrix set under the reference conditions is used as the oxygen partial pressure value Use the relationship to solve the oxygen partial pressure matrix in the third scenario Oxygen partial pressure matrix for scenario 4 Get the molecular weight W of the heterogeneous gas fg and the molecular weight of air W air , and based on the oxygen partial pressure matrix in the third scenario And the oxygen partial pressure matrix under the fourth scenario Calculate the surface film cooling efficiency:

[0056]

[0057] Where η represents the surface film cooling efficiency.

[0058] Embodiment 2

[0059] In this embodiment, if Figure 2 As shown, a device for measuring film cooling efficiency based on parallel line light source scanning is provided, comprising: an un-irradiated area to be measured 1, an excitation light irradiation area 2, a non-measurement area 3, an excitation light 4, a mainstream 5, a scientific camera 6, an air film hole 7, a jet 8, an excitation light source 9, a light source scanning drive mechanism 10, and a measurement area 11, wherein the measurement area 11 is an area where pressure sensitive paint is sprayed, and the un-irradiated area to be measured 1 and the excitation light irradiation area 2 together constitute the measurement area 11. The mainstream 5 is air, and the jet 8 is a heterogeneous gas or air.

[0060] Its workflow is:

[0061] (1) Before measurement, the relationship between the fluorescence intensity emitted by the pressure sensitive paint after being excited by the excitation light 4 and the oxygen partial pressure is obtained by calibration:

[0062]

[0063] The calibration will set the reference conditions, which are usually atmospheric pressure conditions. ref Indicates the light intensity value under reference conditions, Indicates the oxygen partial pressure value under reference conditions, T ref represents the temperature value under reference conditions, I1 represents the light intensity value in a dark environment, x represents the conditions at a certain moment in the calibration process, and I x Indicates the light intensity value during the calibration process. It represents the oxygen partial pressure value during the calibration process, and f represents the functional relationship among the light intensity value, partial pressure value and temperature value.

[0064] (2) Spray pressure-sensitive paint onto the measurement area 11 on the model surface, and spray black paint onto the non-measurement area 3.

[0065] (3) Construct four specific scenarios:

[0066] The first scene: turn off the excitation light 4, turn off the mainstream 5 and the jet 8, get the ambient light, and use the fixed position scientific camera 6 to take pictures;

[0067] The second scene: turn off the mainstream 5 and the jet 8, turn on the excitation light source 9, use the light source scanning drive mechanism 10 to make the excitation light 4 scan along the measurement area 11, and use the fixed position scientific camera 6 to take pictures during the process. The shooting results of this scene correspond to the reference conditions;

[0068] The third scene: the mainstream 5 is set to be air, the jet 8 is set to be air, the mainstream 5 is passed, the jet 8 is passed, the jet 8 flows out through the air film hole 7, the excitation light source 9 is turned on, and the light source scanning drive mechanism 10 is used to make the excitation light 4 scan along the measurement area 11, and the fixed position scientific camera 6 is used to take pictures during the process;

[0069] The fourth scene: set the mainstream 5 to air and the jet 8 to a heterogeneous gas, pass the mainstream 5 and the jet 8, and the jet 8 flows out through the air film hole 7, turn on the excitation light source 9, and use the light source scanning drive mechanism 10 to make the excitation light 4 scan along the measurement area 11. During the process, use a fixed-position scientific camera 6 to take pictures.

[0070] (4) Figure 3As shown, the series of images obtained in the second, third, and fourth scenes in step (3) are processed. Among them, the non-measurement area 3 is not sprayed with pressure-sensitive paint and does not emit fluorescence. The excitation light irradiation area 2 is the area in the measurement area 11 that is irradiated by the excitation light 4 and emits fluorescence. The unirradiated area to be measured 1 is the area in the measurement area 11 that is not irradiated by the excitation light 4 and does not emit fluorescence. Therefore, the excitation light irradiation area 2 in the series of images taken by the scientific camera 6 is spliced, and the average value is taken at the position where the data is repeatedly recorded, and finally the light intensity result of the pressure-sensitive paint in the measurement area 11 that emits fluorescence after being excited is obtained.

[0071] (5) According to the light intensity result, combined with the relationship between light intensity and oxygen partial pressure, the oxygen partial pressure results of the measurement area 11 in the third and fourth scenes are obtained. When using the relationship, the light intensity matrix captured in the first scene is used as the light intensity value I1 in the dark environment, and the light intensity matrix captured in the second scene is used as the light intensity value I1 under the reference condition. ref The light intensity matrix captured in the third scene is used as the light intensity value I3 in the third calibration process, the light intensity matrix captured in the fourth scene is used as the light intensity value I4 in the fourth calibration process, and the oxygen partial pressure matrix set under the reference conditions is used as the oxygen partial pressure value Use the relationship to solve the oxygen partial pressure matrix in the third scenario Oxygen partial pressure matrix for scenario 4

[0072] (6) According to the oxygen partial pressure matrix under the third scenario obtained in step (5) Oxygen partial pressure matrix for scenario 4 Use the molecular weight W of the heterogeneous gas fg and the molecular weight of air W air The film cooling efficiency is calculated as:

[0073]

[0074] Where η represents the surface film cooling efficiency.

[0075] Embodiment 3

[0076] In this embodiment, if Figure 4 As shown, a film cooling efficiency measurement system based on parallel line light source scanning includes: a calibration module, an image acquisition module, an image processing module and an efficiency calculation module.

[0077] The calibration module obtains the relationship between the light intensity and oxygen partial pressure of the pressure sensitive paint after being excited through calibration; the image acquisition module sprays the pressure sensitive paint onto the surface of the model to be measured, and constructs four specific scenes, in three of which a parallel line light source is used to scan the surface of the model to be measured, and a scientific camera 6 is used to shoot to obtain a series of images; the four specific scenes include: the first scene: turning off the excitation light 4, no gas flow, corresponding to a dark environment; the second scene: irradiating the excitation light 4, no gas flow, corresponding to the reference condition; the third scene: irradiating the excitation light 4, setting the mainstream 5 to air and the jet 8 to air; the fourth scene: irradiating the excitation light 4, setting the mainstream 5 to air and the jet 8 to a heterogeneous gas without oxygen; the image processing module is used to process the series of images to obtain the light intensity values ​​of the fluorescence emitted by the pressure sensitive paint in the four scenes; the efficiency calculation module calculates the surface air film cooling efficiency of the model to be measured based on the light intensity value and the relationship.

[0078] The embodiments described above are only descriptions of the preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for measuring film cooling efficiency based on parallel line light source scanning, characterized in that: The following steps are involved: The relationship between the light intensity and oxygen partial pressure of the pressure sensitive paint after being excited is obtained through calibration; The pressure-sensitive paint is sprayed onto the surface of the model to be measured, and four specific scenes are constructed. In three of the scenes, a parallel line light source is used to scan the surface of the model to be measured, and a scientific camera is used to take pictures to obtain a series of images. The four specific scenes include: the first scene: turning off the excitation light, no gas flow, corresponding to a dark environment; the second scene: irradiating the excitation light, no gas flow, corresponding to the reference condition; the third scene: irradiating the excitation light, setting the mainstream to air and the jet to air; the fourth scene: irradiating the excitation light, setting the mainstream to air and the jet to a heterogeneous gas without oxygen; Processing the series of images to obtain light intensity values ​​of the fluorescence emitted by the pressure sensitive paint in four scenes; Based on the light intensity value and the relationship, the surface film cooling efficiency of the model to be measured is calculated.

2. According to claim 1, a method for measuring film cooling efficiency based on parallel line light source scanning is characterized in that: Methods for obtaining the relationship include: In the closed chamber, the pressure sensitive paint is irradiated with excitation light and the oxygen partial pressure in the closed chamber is continuously changed. The light intensity value and the oxygen partial pressure value are recorded to obtain the relationship: Among them, I ref Indicates the light intensity value under reference conditions, Indicates the oxygen partial pressure value under reference conditions, T ref represents the temperature value under reference conditions, I1 represents the light intensity value in a dark environment, x represents the conditions at a certain moment in the calibration process, and I x Indicates the light intensity value during the calibration process. It represents the oxygen partial pressure value during the calibration process, and f represents the functional relationship among the light intensity value, partial pressure value and temperature value.

3. The method for measuring film cooling efficiency based on parallel line light source scanning according to claim 1, characterized in that: In the second scene, the third scene and the fourth scene, the parallel line light source is used to scan the surface of the model to be measured, the parallel line light source is scanned along the surface, and a scientific camera is used to take pictures during the scanning process to obtain a series of images.

4. The method for measuring film cooling efficiency based on parallel line light source scanning according to claim 1, characterized in that: The method for processing the series of images comprises: Recording the light intensity results of the fluorescent area of ​​a single picture in the series of images; The light intensity results of the series of images are spliced, the positions of the light intensity results are repeatedly recorded, and an average value of the light intensity results is taken to obtain the light intensity value.

5. The method for measuring film cooling efficiency based on parallel line light source scanning according to claim 1, characterized in that: The method for calculating the surface film cooling efficiency includes: The light intensity matrix captured in the first scene is used as the light intensity value I1 in the dark environment, and the light intensity matrix captured in the second scene is used as the light intensity value I1 under the reference condition. ref The light intensity matrix captured in the third scene is used as the light intensity value I3 in the third calibration process, the light intensity matrix captured in the fourth scene is used as the light intensity value I4 in the fourth calibration process, and the oxygen partial pressure matrix set under the reference condition is used as the oxygen partial pressure value Using the relationship to solve the oxygen partial pressure matrix under the third scenario The oxygen partial pressure matrix under the fourth scenario Get the molecular weight W of the heterogeneous gas fg and the molecular weight W of the air air , and based on the oxygen partial pressure matrix under the third scenario And the oxygen partial pressure matrix under the fourth scenario Calculate the surface film cooling efficiency: Where η represents the surface film cooling efficiency.

6. A film cooling efficiency measurement system based on parallel line light source scanning, the measurement system applying the measurement method according to any one of claims 1 to 5, characterized in that: include: Calibration module, image acquisition module, image processing module and efficiency calculation module; The calibration module obtains the relationship between the light intensity and the oxygen partial pressure of the pressure sensitive paint after being excited by calibration; The image acquisition module sprays the pressure-sensitive paint onto the surface of the model to be measured, and constructs four specific scenes, in which a parallel line light source is used to scan the surface of the model to be measured, and a scientific camera is used to shoot to obtain a series of images; the four specific scenes include: a first scene: turning off the excitation light, no gas flow, corresponding to a dark environment; a second scene: irradiating the excitation light, no gas flow, corresponding to a reference condition; a third scene: irradiating the excitation light, setting the mainstream to air and the jet to air; a fourth scene: irradiating the excitation light, setting the mainstream to air and the jet to a heterogeneous gas without oxygen; The image processing module is used to process the series of images to obtain the light intensity values ​​of the fluorescence emitted by the pressure sensitive paint in four scenes; The efficiency calculation module calculates the surface film cooling efficiency of the model to be measured based on the light intensity value and the relationship.

Images