CN113738451B - Test system for measuring cooling characteristics of cascade air film - Google Patents

Test system for measuring cooling characteristics of cascade air film Download PDF

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Publication number
CN113738451B
CN113738451B CN202111077874.3A CN202111077874A CN113738451B CN 113738451 B CN113738451 B CN 113738451B CN 202111077874 A CN202111077874 A CN 202111077874A CN 113738451 B CN113738451 B CN 113738451B
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blade
air
film
pressure
flow channel
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CN113738451A (en
Inventor
刘钊
王海锋
张韦馨
李冯
贾哲
谢晔航
丰镇平
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Xian Jiaotong University
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Xian Jiaotong University
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D5/00—Blades; Blade-carrying members; Heating, heat-insulating, cooling or antivibration means on the blades or the members
    • F01D5/12—Blades
    • F01D5/14—Form or construction
    • F01D5/18—Hollow blades, i.e. blades with cooling or heating channels or cavities; Heating, heat-insulating or cooling means on blades
    • F01D5/186—Film cooling
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D11/00—Preventing or minimising internal leakage of working-fluid, e.g. between stages
    • F01D11/003—Preventing or minimising internal leakage of working-fluid, e.g. between stages by packing rings; Mechanical seals
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D21/00—Shutting-down of machines or engines, e.g. in emergency; Regulating, controlling, or safety means not otherwise provided for
    • F01D21/003—Arrangements for testing or measuring
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D25/00—Component parts, details, or accessories, not provided for in, or of interest apart from, other groups
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E20/00—Combustion technologies with mitigation potential
    • Y02E20/16—Combined cycle power plant [CCPP], or combined cycle gas turbine [CCGT]

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Investigating Or Analyzing Materials Using Thermal Means (AREA)

Abstract

A test system for measuring cascade air film cooling characteristics, comprising: the test section model is used for simulating a turbine blade cascade flow channel, a blade test piece and the CO of the blade test piece are fixedly arranged at the turning angle position of the blade in the flow channel2The air inlet extends out of the flow passage along the radial direction, a plurality of blade air film holes are respectively arranged on the pressure surface and the suction surface of the blade of the air inlet, and the pressure surface and the suction surface of the blade are provided with blade pressure guiding holes at equal intervals along the contour line; the main flow system is connected with the inlet of the flow channel and sends main flow air to the flow channel; CO 22Cooling system connected to CO2An air inlet for feeding CO into the air supply cavity inside the blade test piece2Cold air is ejected from the air film hole of the blade to form an air film for cooling; and the measuring system is used for measuring the pressure and temperature distribution inside the flow channel, wherein the temperature distribution is obtained by shooting through an infrared camera. The invention realizes the measurement of the cooling efficiency and the heat exchange coefficient of the surface of the blade cascade and solves the difficulty that the surface of the blade cannot be measured due to overlarge curvature change.

Description

Test system for measuring cooling characteristic of cascade air film
Technical Field
The invention belongs to the technical field of cascade characteristic research, and particularly relates to a test system for measuring cascade air film cooling characteristics.
Background
The gas turbine as a power device has the advantages of wide power range, large power density, flexible starting and the like, and is widely applied to a plurality of fields of industrial driving such as aviation power propulsion, ground heavy-duty gas turbine power generation, chemical energy and the like. With the increasing inlet temperature of the gas turbine, the temperature far exceeds the limit temperature which can be endured by the blade material. Therefore, advanced cooling techniques are urgently required to secure safe and stable operation of the blade. Film cooling is an important cooling method in external cooling, and how to improve the film cooling efficiency and reduce the cooling air supply amount plays a significant role in improving the internal efficiency of the gas turbine.
At present, the existing research at home and abroad mainly focuses on air film cooling on a flat plate, and few experimental researches on air film cooling on a large-curvature profile with the characteristics of a turbine blade are as follows: the reliability of the turbine blade cooling design is difficult to guarantee due to the lack of an applicable calculation model; the change of the curvature of the surface of the blade is large, the measurement of the temperature distribution of the surface of the blade is difficult, and a reasonable temperature measurement window is particularly important; the number of the blade air film holes is large, the number of the corresponding blade test pieces is large, a reasonable assembly scheme needs to be designed, and installation and measurement of the different hole type blade test pieces are facilitated.
The blade cascade air film cooling efficiency is related to the axial position of the air film holes on the blade body, the air film hole pattern and the like, and a reasonable blade cascade air film cooling test system needs to be designed, so that the blade cascade air film cooling efficiency corresponding to the air film holes at different axial positions and different hole patterns can be conveniently measured, and the blade cascade air film cooling and heat exchange results can be obtained.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to provide a test system for measuring the cooling characteristics of a cascade air film, which is used for testing air film holes at different axial positions of a blade body for cooling the cascade air film, different hole patterns and other working conditions to obtain a corresponding shot temperature cloud chart, and further obtaining the cooling efficiency and the heat exchange coefficient of the air film holes through formula analysis and calculation.
In order to achieve the purpose, the invention adopts the technical scheme that:
a test system for measuring cascade air film cooling characteristics, comprising:
the test section model is used for simulating a turbine blade cascade flow channel, a blade test piece and the CO of the blade test piece are fixedly arranged at the turning angle position of the blade in the flow channel2The air inlet extends out of the flow passage along the radial direction, and the blade pressure surface and the blade suction surface of the blade test pieceA plurality of blade air film holes are respectively arranged on the blade, and blade pressure guiding holes with equal intervals are arranged on the pressure surface and the suction surface of the blade along contour lines;
the main flow system is connected with the inlet of the flow channel and sends main flow air into the flow channel;
CO2a cooling system connected to the CO2An air inlet for feeding CO into the air supply cavity inside the blade test piece2Cold air is ejected from the air film hole of the blade to form an air film for cooling;
and the measuring system is used for measuring the pressure and the temperature distribution inside the flow channel, wherein the temperature distribution is obtained by shooting through an infrared camera.
Furthermore, a plurality of measuring holes are arranged at the front end of the flow channel and used for measuring the incoming flow pressure, temperature and turbulence degree of a measuring system and controlling the incoming flow pressure, temperature and turbulence degree within the range of the given conditions of the test.
Furthermore, the suction surface side wall and the pressure surface side wall of the flow channel are respectively provided with an equal amount of pressure guiding holes, and the corresponding periodicity is observed by comparing the pressure distribution on the two side walls with the pressure distribution on the pressure surface and the suction surface of the blade.
Furthermore, the two sides of the tail edge section of the flow channel are respectively provided with a tail edge plate, and the flow of the flow channel on the two sides is adjusted by adjusting the angle of the tail edge plate, so that the periodic effect on the two sides is adjusted.
Furthermore, a plurality of infrared shooting windows facing the pressure surface and the suction surface of the blade are arranged on the side wall of the suction surface and the side wall of the pressure surface of the flow channel, so that the measuring system can shoot a blade surface temperature distribution cloud picture by utilizing an infrared camera.
Further, the infrared shooting window is composed of a window W1, a window W2 and a window W3, wherein the window W1 substantially covers the shooting area of the pressure surface of the blade, and the window W2 and the window W3 substantially cover the shooting area of the suction surface of the blade, so that the infrared camera can completely cover the shooting areas downstream of the air film holes of the pressure surface and the suction surface of the blade.
Further, the runner is made by organic glass, and its suction side lateral wall and pressure side lateral wall adopt aluminum alloy material simulation both sides blade wall, infrared shooting window department infrared glass adopts the BaF2 material.
Further, the cooling efficiency and the heat exchange coefficient of the blade heat insulation air film are separately measured, and the cooling efficiency of the blade air film is measured as follows: attaching a 0.02mm steel film on the surface of a blade test piece, and spraying uniform black matte paint on the surface of the 0.02mm steel film for infrared measurement; for heat transfer test measurements: the heat exchange coefficient is measured by adopting a constant current method, a thin-layer heating film is attached to the surface of a blade test piece, a 0.1mm copper film is attached to the thin-layer heating film to provide constant heat flow, and a 0.02mm steel film is attached to the surface of the 0.1mm copper film, so that when the surface temperature of the 0.1mm copper film is uniform, the transverse heat conduction is reduced through the 0.02mm steel film, and the surface of the 0.02mm steel film is sprayed with uniform black matte paint.
Furthermore, thermocouples are respectively arranged in the turning angle position of the blade and the air supply cavity in the blade test piece in the flow channel.
Furthermore, the main flow system comprises an air compressor unit consisting of a plurality of air compressors, the outlet of each air compressor is sequentially connected with a cold dryer, an air storage tank and a butterfly valve, and then the air compressors are collected and divided into a bypass and a main flow, the bypass is provided with a bypass valve, the main flow is connected with a steady flow expansion section through a main air valve, and is connected with a variable diameter pipeline after passing through a honeycomb rectification section, and finally the main flow is connected into a flow channel;
the CO is2The cold air system comprises CO consisting of a plurality of gas cylinders connected in parallel2Gas cylinder group, CO2An outlet of the gas cylinder group is sequentially connected with a ball valve, a first pressure reducing valve, a filter, a flowmeter and a second pressure reducing valve, and then the gas cylinder group passes through a heat exchanger and enters a blade test piece after reaching the required temperature.
Compared with the prior art, the invention has the beneficial effects that:
1) the invention adopts the infrared camera to shoot, adopts a non-contact mode to measure the temperature distribution on the surface of the blade, and reduces the influence of the measurement on the internal flow field as much as possible.
2) According to the invention, the infrared shooting window is arranged on the side wall surface of the flow channel so as to achieve the purpose of shooting the temperature distribution condition of the surface of the blade, and simultaneously, the good periodicity of the blade grid channel is ensured.
3) According to the invention, the tail edge plates are uniformly arranged on two sides of the tail edge of the flow channel, and the flow rate of the channels on two sides is adjusted by adjusting the angle of the tail edge plates, so that the periodicity is further adjusted.
4) According to the invention, the infrared shooting window is reasonably arranged at the suction surface, so that temperature data acquisition can be conveniently carried out on the suction surface of the blade with large curvature change.
5) According to the invention, the high-precision 3D printing technology is adopted to print the blade material, the pressure-leading hole with a small aperture is generated, and the accuracy of blade body static pressure measurement is improved.
6) The root of the blade is matched on the organic glass plate, the top of the blade is fixed on the organic glass plate of the blade top channel through the bolt, and the bolt connection mode is adopted, so that the flexibility of assembling and disassembling the blade test piece is greatly improved.
7) The joint of the blade and the organic glass plate surface is sealed by adopting sealing silicone grease, so that the air flow in the blade grid channel is prevented from leaking outwards from the root part and the top part.
8) The invention adopts the mode that the surface of the blade test piece is covered with the black steel film, and the steel film is used for covering the non-measuring hole rows, thereby realizing the independent single-row air film hole cold efficiency measurement test of the air film hole rows at different axial positions on the same blade without mutual interference.
Drawings
FIG. 1 is a schematic view of the overall testing system of the present invention.
Fig. 2 is a schematic view of a middle section of the test segment model.
Fig. 3 is a left front view (the arrow direction of the right figure is the view direction) of the pressure surface direction of the test piece, and the right figure is a middle section top view of the test piece.
Fig. 4 is a three-dimensional view of the experimental section assembly.
FIG. 5 is a schematic view of the surface attachment material of the blade test piece.
Detailed Description
The embodiments of the present invention will be described in detail below with reference to the drawings and examples.
As shown in FIG. 1, the invention relates to a test system for measuring the cooling characteristics of a cascade air film, which comprises a test section model, a main flow system, CO2A cooling system and a measuring system, anda heat exchange system can be additionally arranged as required. According to the invention, the infrared shooting windows are reasonably arranged on the periodic side wall, so that the cooling efficiency and the heat exchange coefficient of the surface of the blade cascade are measured. The difficulty that the surface of the blade cannot be measured due to overlarge curvature change is solved. And the blade grid test section enables the blade test piece to be replaced more conveniently and quickly by aiming at the design of the blade test piece pressing cover plate type. And obtaining the cooling efficiency within a certain range at the downstream of the air film hole outlet by using the data acquired by the infrared camera.
The test section model is used for simulating a turbine blade cascade flow passage and can simulate the flow condition of the actual flow passage in the cascade, and as shown in fig. 2, a blade test piece 24 is fixedly arranged at the turning angle position of the blade in the flow passage in a bolt mode and the like and can be sealed by sealing silicone grease.
CO of the blade test piece 24, as shown in FIGS. 3 and 42The air inlet 27 extends out of the flow passage along the radial direction, and a plurality of blade air film holes 29 are respectively arranged on the blade pressure surface 25 and the blade suction surface 26 of the blade test piece 24, wherein the blade air film holes 29 can be fan-shaped, and the row number of the blade pressure surface 25 and the row number of the blade suction surface 26 are generally different. And the pressure surface 25 and the suction surface 26 of the blade are provided with blade pressure guiding holes 28 at equal intervals along the contour line for measuring the surface pressure distribution.
In one embodiment of the present invention, the blade trial 24 may be rapidly formed using a 3D printing technique using a photosensitive resin material, and printed with high precision.
In one embodiment of the invention, the flow channel is made of plexiglass.
The main flow system is connected with the inlet of the flow channel and is used for feeding main flow air into the flow channel.
In one embodiment of the invention, as shown in fig. 1, the air compressor unit comprises an air compressor unit composed of a plurality of air compressors 1, wherein the outlet of each air compressor 1 is respectively connected with a refrigeration dryer 2, an air storage tank 3 and a butterfly valve 4 in sequence, then the air compressors are collected and divided into a bypass and a main path, the bypass is provided with a bypass valve 5, the main path is connected with a steady flow expansion section 7 through a main air valve 6, and is connected with a reducing pipeline after passing through a honeycomb rectifying section 8, and finally the main path is connected into a flow channel. The cold dryer 2 can enable compressed air to maintain a low temperature and humidity, the bypass valve 5 controls the flow of the main flow to enable the main flow to reach a specified Mach number, and the main flow compressed air enters the steady flow expansion section 7 to be stabilized and then flows through the honeycomb rectifying section 8 to be rectified, so that the turbulence degree of the main flow is improved, and the test requirements are met. Wherein the mainstream flow rate can be collected by pressure transmitter 16.
CO2Air conditioning system connected with CO2An air inlet 27 for feeding CO into the air supply chamber inside the blade test piece 242The cold air is ejected from the blade film holes 29 to form film cooling.
In one embodiment of the invention, as shown in fig. 1, it comprises a CO consisting of several cylinders in parallel2Gas cylinder group 9, CO2The outlet of the gas cylinder group 9 is sequentially connected with a ball valve 10, a first pressure reducing valve 11, a filter 12, a flowmeter 13 and a second pressure reducing valve 14, and then enters an internal gas supply cavity of the blade test piece 24 through a heat exchanger 15 after reaching the required temperature, and is sprayed outwards from a blade gas film hole 29 to form gas film cooling.
The measuring system is used for measuring the pressure and temperature distribution inside the flow channel, wherein the temperature distribution is obtained through shooting by the infrared camera 18, and the planar image can be converted into temperature data on the curved surface of the blade through post-programming data processing, so that the air film cooling efficiency is obtained.
The measuring system mainly comprises: temperature measurement system, pressure measurement system and cloud picture shooting system, wherein:
in one embodiment of the present invention, a plurality of measuring holes 20 are arranged at the front end of the flow channel, and the measuring system measures parameters such as incoming flow pressure (total pressure, static pressure), temperature, turbulence degree and the like through the measuring holes 20 and controls the parameters within the range of the conditions given in the test. For example, the pressure transmitter 16 may collect the pressure and transmit the pressure to the computer acquisition system 17 through the IMP data collection board, so as to obtain the internal pressure distribution of the test section according to the pressure data.
In one embodiment of the present invention, thermocouples are disposed in the flow channel at least at the turning angle position of the blade and in the air supply cavity inside the blade test piece 24, and the corresponding temperature data is transmitted to the data acquisition system through the KRYPTON 8X temperature acquisition system 19, so as to obtain the temperature data inside the flow channel and inside the air supply cavity. Illustratively, the thermocouple may be a T-type thermocouple.
In one embodiment of the invention, the suction side wall 21 and the pressure side wall 22 of the flow channel are provided with infrared camera windows facing the pressure side 25 and the suction side 26 of the blade for the measurement system to use the infrared camera 18 to take a cloud picture of the temperature distribution on the surface of the blade.
Illustratively, the infrared photographing window is composed of a window W1, a window W2, and a window W3, wherein the window W1 substantially covers the blade pressure surface 25 photographing region, and the window W2 and the window W3 substantially cover the blade suction surface 26 photographing region, thereby enabling the infrared camera to completely cover the blade pressure surface 25, the blade suction surface 26, and the downstream photographing region of the blade film hole 29. Under the condition of not influencing the periodicity of the blade cascade flow channel, the infrared shooting window can accurately acquire a blade surface temperature distribution cloud picture; because of the great curvature change of the suction surface 26 of the blade, two infrared shooting windows are arranged on the side of the suction surface 26 of the blade, a more complete cloud picture of the temperature distribution on the surface of the blade can be obtained, and the experimental measurement error is reduced.
In one embodiment of the invention, the flow channel is made of organic glass, the suction side wall 21 and the pressure side wall 22 of the flow channel are made of aluminum alloy materials to simulate the wall surfaces of the blades on two sides, and the infrared glass at the infrared shooting window is made of BaF2 materials. Exemplarily, the blade test piece 24 is designed to be convenient to disassemble and assemble, and the blade root platform is pressed on the surface of organic glass at the test section through sealing silicone grease to play a sealing role; the top of the blade is fastened on organic glass at the upper end test section in a bolt mode, and the joints are coated with sealing silicone grease to play a role in sealing.
When blade gas film hole 29 cold efficiency, heat transfer are measured, need measure blade gas film hole 29 that the independent pore row of different axial positions department and the blade gas film hole 29 that porous row respectively, blade test piece 24 takes the mode at the attached steel film of blade surface, when measuring to single row gas film hole, the steel film covers other pore row department gas film holes, remains and need measuring pore row department gas film hole. When measuring to different hole rows, only need to change and correspond different hole row steel films, save the figure that 3D printed blade testpieces 24.
The surface of the blade needs to be heated when the heat exchange coefficient is measured, the heat conduction of the blade material under the condition of high temperature difference influences the measurement accuracy of the heat exchange coefficient, and the 3D printing resin material with relatively small heat conduction coefficient is selected, so that the experimental reliability is improved.
As shown in FIG. 5, the present invention can separately measure the cooling efficiency and the heat exchange coefficient of the blade heat insulation air film, and the cooling efficiency of the blade air film is measured as follows: attaching a 0.02mm steel film 32 to the surface of the blade test piece 24, and spraying uniform black matte paint on the surface of the 0.02mm steel film 32 for infrared measurement; by the method, the influence of the transverse heat conduction of the blade surface on the blade grid air film cold effect measurement is reduced. For heat transfer test measurements: adopt the constant current method to measure heat transfer coefficient, at 24 surperficial attached thin-layer heating film 30 of blade test pieces, provide stable heat flux density, the attached 0.1mm copper film 31 provides invariable heat flux on the thin-layer heating film 30, it is more even to make blade surface temperature distribution, the attached 0.02mm steel film 32 again on the copper film surface, when making 0.1mm copper film 31 surface temperature even, reduce horizontal heat conduction through 0.02mm steel film 32, reduce the influence of horizontal heat conduction to gas film hole low reaches heat transfer coefficient measurement. The surface of the 0.02mm steel film 32 can be sprayed with uniform black matte paint, so that the reflectivity can be enhanced, and a more accurate experimental measurement result can be obtained when infrared shooting is utilized.
In one embodiment of the present invention, equal pressure guiding holes are respectively arranged on the suction side wall 21 and the pressure side wall 22 of the flow channel, and the positions of the pressure guiding holes are basically kept corresponding to the positions of the blade pressure guiding holes 28, and the periodicity of the flow channel is observed, analyzed and compared by comparing the pressure distribution on the two side walls with the pressure distribution on the pressure side 25 and the suction side 26 of the blade.
In an embodiment of the present invention, the two sides of the trailing edge section of the flow channel are respectively provided with the trailing edge plates 23, and the flow rate of the flow channel on the two sides is adjusted by adjusting the angle of the trailing edge plates 23, so as to adjust the periodic effect on the two sides to achieve the best effect.
The working principle of the invention is as follows:
the periodicity of the cascade flow channels is adjusted by adjusting the angle of the tail edge plate 23, and the measurement is carried out through the pressure surface side wall 22 and the suction surface side wall 21 and the measurement is carried out through the pressure measuring holes corresponding to the surfaces of the blades; the blade test piece 24 is assembled on the test section in a bolt mode, so that the assembling and disassembling flexibility of the blade test piece 24 is improved, and the replacement is convenient; in the heat exchange test, a 0.1mm copper film 31 is attached to the surface of the flexible thin-layer heating film 30, so that the temperature distribution of the surface of the blade is uniform, and a 0.02mm steel film 32 is attached to the surface of the 0.1mm copper film 31, so that the transverse heat conduction of the surface of the blade is reduced, and the test measurement is more accurate; the attached 0.02mm steel membrane 32 in blade surface reduces the horizontal heat conduction in blade surface, also does benefit to respectively to the different hole exhaust membrane holes carry out independent cold test, has greatly saved the blade testpieces and has printed the figure.
The experimental measurement process of the invention is as follows:
installing a blade test piece 24 at the blade turning angle position of the test section, and smearing sealing silicone grease to ensure that the test section has good air tightness;
in order to prevent the infrared glass from being damaged due to instantaneous and large fluctuation of the main flow pressure, before the compressor is started in each test, the inlet valve of the test section is closed, all the bypass valves are opened, after the pressure in the gas storage tank is stable, the gas inlet valve of the test section is slowly opened, and then the opening of the bypass valve is remotely controlled through a computer according to the test requirements.
On the basis, a pressure transmitter or a pressure scanning valve is adopted to measure the static pressure distribution of the surface and the periodic side wall of the blade test piece 24, and the flow distribution in the two channels is adjusted by adjusting the tail edge plate 23, so that the two channels in the test section meet the periodic requirement.
During test measurement, the whole test section needs to reach a stable state of flow and heat transfer to acquire test data. For the measurement of the effectiveness of the adiabatic air film cooling, after the temperature and pressure of the main stream and the cool air are stabilized, the temperature of the main stream and the temperature of the cool air are measured by a thermocouple, and the temperature of the wall surface is photographed by an infrared camera 18. For the measurement of the heat exchange coefficient, the refrigeration temperature of the refrigerator is adjusted to ensure that the temperature of cold air is almost consistent with the temperature of main flow, and the thermal boundary condition of the wall surface needs to be changed under the condition of ensuring the identical flow for carrying out shooting measurement twice.
The above contents are only for illustrating the technical idea of the present invention, and the protection scope of the present invention should not be limited thereby, and any modification made on the basis of the technical idea proposed by the present invention falls within the protection scope of the claims of the present invention.

Claims (9)

1. A test system for measuring cascade air film cooling characteristics, comprising:
the test section model is used for simulating a turbine blade cascade flow passage, a blade test piece (24) is fixedly arranged at the turning angle position of the blade in the flow passage, and CO of the blade test piece (24)2The air inlet (27) extends out of the flow channel along the radial direction, a plurality of blade air film holes (29) are respectively arranged on a blade pressure surface (25) and a blade suction surface (26) of the blade test piece (24), and blade pressure guiding holes (28) with equal intervals are arranged on the blade pressure surface (25) and the blade suction surface (26) along contour lines;
the main flow system is connected with the inlet of the flow channel and sends main flow air to the flow channel;
CO2a cooling system connected to the CO2An air inlet (27) for feeding CO into the air supply chamber inside the blade test piece (24)2Cold air is ejected from the blade air film hole (29) to form air film cooling;
the measuring system is used for measuring the pressure and temperature distribution inside the flow channel, wherein the temperature distribution is shot by an infrared camera (18);
the device is characterized in that equal pressure guiding holes are respectively arranged on the suction surface side wall (21) and the pressure surface side wall (22) of the flow channel, and the corresponding periodicity is observed by comparing the pressure distribution on the two side walls with the pressure distribution on the blade pressure surface (25) and the blade suction surface (26).
2. The test system for measuring the cascade gas film cooling characteristics according to the claim 1, wherein a plurality of measuring holes (20) are arranged at the front end of the flow channel, and are used for measuring the incoming flow pressure, temperature and turbulence degree of the system and controlling the system within the given condition range of the test.
3. The test system for measuring the cascade gas film cooling characteristics according to claim 1, wherein the two sides of the trailing edge section of the flow channel are respectively provided with a trailing edge plate (23), and the flow rate of the flow channel on the two sides is adjusted by adjusting the angle of the trailing edge plate (23), so as to adjust the periodic effect on the two sides.
4. The test system for measuring the cooling characteristics of the blade cascade air film according to claim 1, wherein the suction side wall (21) and the pressure side wall (22) of the flow passage are provided with a plurality of infrared shooting windows facing the pressure side (25) and the suction side (26) of the blade, so that the infrared camera (18) can shoot a temperature distribution cloud picture of the surface of the blade.
5. The test system for measuring the cooling characteristics of the blade cascade air film according to claim 4, wherein the infrared shooting window is composed of a window W1, a window W2 and a window W3, wherein the window W1 substantially covers the shooting area of the pressure surface (25) of the blade, and the window W2 and the window W3 substantially cover the shooting area of the suction surface (26) of the blade, so that the infrared camera can completely cover the shooting areas of the pressure surface (25) of the blade and the downstream of the blade air film hole (29) of the suction surface (26) of the blade.
6. The test system for measuring the air film cooling characteristic of the blade cascade according to claim 4, wherein the flow channel is made of organic glass, the suction side wall (21) and the pressure side wall (22) of the flow channel are made of aluminum alloy materials to simulate the wall surfaces of the blades on two sides, and the infrared glass at the position of the infrared shooting window is made of BaF2 materials.
7. The test system for measuring the cooling characteristics of the cascade air film according to claim 6, wherein the cooling efficiency and the heat exchange coefficient of the blade adiabatic air film are measured separately, and the cooling efficiency of the blade air film is measured by: attaching a 0.02mm steel film (32) to the surface of the blade test piece (24), and spraying uniform black matte paint on the surface of the 0.02mm steel film (32) for infrared measurement; for heat transfer test measurements: the heat exchange coefficient is measured by adopting a constant current method, a thin-layer heating film (30) is attached to the surface of a blade test piece (24), a 0.1mm copper film (31) is attached to the thin-layer heating film (30) to provide constant heat flow, and a 0.02mm steel film (32) is attached to the surface of the 0.1mm copper film (31), so that the surface temperature of the 0.1mm copper film (31) is uniform, the transverse heat conduction is reduced through the 0.02mm steel film (32), and the surface of the 0.02mm steel film (32) is sprayed with uniform black matte paint.
8. The test system for measuring the cooling characteristic of the cascade air film as claimed in claim 1, wherein thermocouples are arranged in the flow channel at the turning angle position of the blade and in the air supply cavity inside the blade test piece (24).
9. The test system for measuring the cooling characteristics of the cascade air film according to claim 1, wherein the main flow system comprises an air compressor unit consisting of a plurality of air compressors (1), the outlet of each air compressor (1) is sequentially connected with a cold dryer (2), an air storage tank (3) and a butterfly valve (4), and then is collected and divided into a bypass and a main flow, the bypass is provided with a bypass valve (5), the main flow is connected with a steady flow expansion section (7) through a main air valve (6), and is connected with a reducing pipeline after passing through a honeycomb rectifying section (8) and finally is connected into a flow channel;
the CO is2The cold air system comprises CO consisting of a plurality of gas cylinders connected in parallel2Gas cylinder group (9), CO2An outlet of the gas cylinder group (9) is sequentially connected with a ball valve (10), a first reducing valve (11), a filter (12), a flowmeter (13) and a second reducing valve (14), and then the gas cylinder group enters a blade test piece (24) after reaching the required temperature through a heat exchanger (15).
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