Double-degree-of-freedom clamp for adjusting magnitude and direction of turbine blade bending moment and test method

Abstract

The application discloses a double-freedom-degree clamp capable of adjusting the size and direction of a bending moment of a turbine blade and a test method, comprising a blade clamping component, an upper adjustable U-shaped head and a lower adjustable U-shaped head, an upper clamping rod and a lower clamping rod. The blade clamping component is threadedly connected with the upper adjustable U-shaped head and the lower adjustable U-shaped head respectively, the other ends of the upper adjustable U-shaped head and the lower adjustable U-shaped head are connected with the upper clamping rod and the lower clamping rod respectively, and the other ends of the upper clamping rod and the lower clamping rod are connected with upper and lower clamping heads of a fatigue testing machine respectively. The upper clamping rod and the upper adjustable U-shaped head are adjustably connected with each other along a transverse direction intersecting with a vertical axis to adjust the eccentricity of a turbine blade load. The eccentric angle of the blade load can be adjusted by adjusting the rotation degree of the blade clamping component. The clamp can realize different bending moment directions and relative sizes of different sections of the turbine blade during the turbine blade test by adjusting the eccentricity and the eccentric angle of the turbine blade during the test, so that the real load can be simulated.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of turbine blade stress loading test fixture, in particular, to a double-freedom fixture capable of adjusting the size and direction of turbine blade bending moment. BACKGROUND

[0002] Turbine blade is one of the important components of an aero-engine, and the creep and fatigue failure under high temperature are the main factors leading to its damage. In order to evaluate the service life of the turbine blade, it is necessary to carry out life test under different failure modes according to the actual service conditions of the turbine blade. Since the cost of carrying out blade life test under real conditions with the whole machine test is high, and once the structure fails, it will lead to unpredictable consequences. Therefore, it is of great significance to simulate the real service conditions of the blade and carry out life test under laboratory conditions.

[0003] For the fatigue failure mode, the examination unit of the dangerous position is usually several minimum fatigue life points, and for the creep failure mode, due to the stress relaxation effect, the examination unit of the dangerous position is usually the section perpendicular to the blade height direction. Therefore, in order to carry out turbine blade life test under laboratory conditions, it is necessary to simulate the stress and temperature distribution on different blade height sections.

[0004] Under the working condition of high-speed rotation, centrifugal force is one of the main mechanical loads borne by the turbine blade. In order to achieve high aerodynamic efficiency, the advanced turbine blade usually has a complex bending and torsion structure, which leads to uneven centrifugal load distribution on the blade height section. At the same time, the blade has a complex cooling structure inside and on the surface, which leads to complex temperature distribution on the section. Therefore, a corresponding fixture system must be designed to realize the simulation of stress and temperature distribution on the examination section.

[0005] The existing conventional test fixture can continuously change the angle between the blade and the main shaft of the tensile fatigue testing machine after clamping the blade, so as to realize the simulation of the interface stress distribution of the turbine blade by using a single-axis tensile fatigue testing machine. However, although the bending moment of the blade during loading is considered during the test, the direction of the bending moment on the blade section is not considered. In addition, since there is a complex stress and temperature gradient near the examination section, the loading result also needs to be accurately calibrated. In the existing conventional test method, the calibration step is completed only by measuring the surface strain and temperature distribution, the internal load state cannot be obtained, and the complete calibration result cannot be formed. SUMMARY

[0006] The present application provides a double-freedom fixture capable of adjusting the size and direction of turbine blade bending moment and a test method, to solve the technical problem that although the bending moment of the blade during loading is considered during the existing test, the direction of the bending moment on the blade section is not considered, and the purpose of simulating the real load cannot be achieved.

[0007] The technical scheme adopted by the present application is as follows:

[0008] A double-degree-of-freedom clamp capable of adjusting the size and direction of the bending moment of a turbine blade comprises blade clamping members for clamping and fixing the turbine blade at both ends along the height direction of the turbine blade to be tested, an upper adjustable U-shaped head and a lower adjustable U-shaped head, an upper clamping rod and a lower clamping rod; the upper and lower ends of the blade clamping members along the height direction are respectively threadedly connected with the upper adjustable U-shaped head and the lower adjustable U-shaped head, the other ends of the upper adjustable U-shaped head and the lower adjustable U-shaped head are respectively connected with the upper clamping rod and the lower clamping rod, and the other ends of the upper clamping rod and the lower clamping rod are respectively connected with the upper chuck and the lower chuck of a fatigue testing machine, so that the upper clamping rod, the upper adjustable U-shaped head, the blade clamping members, the lower adjustable U-shaped head and the lower clamping rod are sequentially connected along a vertical axis between the upper chuck and the lower chuck of the fatigue testing machine; the upper clamping rod and the upper adjustable U-shaped head, and / or the lower clamping rod and the lower adjustable U-shaped head are adjustably connected with each other along a horizontal direction intersecting the vertical axis, so as to adjust the eccentricity of the turbine blade load; and the rotation degree of the blade clamping members is adjusted to adjust the eccentric angle of the turbine blade load.

[0009] Further, the blade clamping members comprise a blade body chuck for clamping and fixing the upper end of the turbine blade, a fixed chuck connected with the blade body chuck, and a tenon groove chuck for clamping and fixing the lower end of the turbine blade; the fixed chuck is threadedly connected with the lower end of the upper adjustable U-shaped head, and an upper locking ring for locking the fixed chuck is further sleeved at the threadedly connected position; the lower end of the tenon groove chuck is threadedly connected with the upper end of the lower adjustable U-shaped head, and a lower locking ring for locking the tenon groove chuck is further sleeved at the threadedly connected position.

[0010] Further, the blade body chuck comprises left and right chucks oppositely arranged and having an "L" shaped cross section, locking bolts and fixed bolts; the fixed chuck is arranged between the upper ends of the left and right chucks, and the fixed bolts are arranged through the left and right chucks and the fixed chuck to lock and fix the blade body chuck and the fixed chuck; the blade body of the upper end of the turbine blade is arranged between the lower ends of the left and right chucks, and the locking bolts are arranged through the left and right chucks to relatively clamp the left and right chucks to fix the blade body, or the locking bolts are arranged through the left and right chucks and the blade body to integrally fix the blade body chuck and the blade body of the turbine blade.

[0011] Further, the two inner sides of the left and right chucks oppositely arranged are respectively provided with positioning profiles matched with the two sides of the blade body of the turbine blade, so that the blade body is positioned in the blade body chuck through the matching of the positioning profiles and the side surfaces of the blade body.

[0012] Further, the upper end of the mortise chuck is provided with a mortise cavity matched with the tenon of the turbine blade, the front and rear ends of the mortise cavity extend through the mortise chuck, so that the tenon is slidably installed into the mortise cavity along the extending direction; the upper end of the mortise cavity extends through the top of the mortise chuck, so that the blade body extends upwardly out of the mortise chuck.

[0013] Further, the side wall of the mortise chuck is further provided with an air inlet hole extending through the wall surface and communicating with the mortise cavity; the wall surface of the left chuck or the right chuck is further provided with an air outlet hole extending through the wall surface and communicating with the cavity between the left chuck and the right chuck, so that the external cold air machine for supplying cooling air, the mortise chuck, the tenon, the blade body and the blade body chuck are communicated to form a cooling air loop.

[0014] Further, the double-freedom-degree clamp for adjusting the bending moment size and direction of the turbine blade further comprises a heating coil for heating the turbine blade, which is arranged on the outer circle of the blade body of the turbine blade between the blade body chuck and the mortise chuck.

[0015] Further, the upper clamping rod and the lower clamping rod are of the same structure, and the upper adjustable U-shaped head and the lower adjustable U-shaped head are of the same structure; the upper adjustable U-shaped head comprises a U-shaped connecting head in U shape at the upper end thereof, and a connecting screw rod connecting the lower closed end of the U-shaped connecting head; the two sides of the lower end of the upper clamping rod are respectively cut to form plate-shaped connecting portions, the connecting portions extend into the U-shaped connecting head, and the upper clamping rod is adjustably connected with the upper adjustable U-shaped head by the upper connecting bolts penetrating the U-shaped connecting head and the connecting portions, and the eccentricity of the turbine blade load can be adjusted by adjusting the position of the connecting portions in the width direction of the U-shaped connecting head; the connecting screw rod is threadedly connected with the lower fixed chuck, so that the eccentric angle of the blade load can be adjusted by rotating the fixed chuck.

[0016] Further, the upper cooling water pipe is vertically arranged on the upper clamping rod, the lower cooling water pipe is vertically arranged on the lower clamping rod, and the upper cooling water pipe, the lower cooling water pipe and the external cold water machine for supplying cooling water are communicated to form a cooling water loop.

[0017] According to another aspect of the present application, there is also provided a test method using the double-freedom fixture for adjusting the magnitude and direction of the bending moment of a turbine blade according to any one of the above, the test method comprising the following steps: test fixture assembly: clamping and fixing the turbine blade to be tested to the double-freedom fixture, and clamping and connecting the double-freedom fixture to the fatigue testing machine; blade bending moment load setting: adjusting the eccentricity and eccentric angle of the blade load applied to the turbine blade according to the simulation results to simulate the service load of the turbine blade; blade temperature load setting: determining the geometry and installation position of the heating coil according to the simulation software, and then adjusting the geometry and position of the heating coil on the turbine blade to make the temperature field of the blade test section conform to the actual working state of the turbine blade; pre-test stress and temperature load calibration: calibrating the inner and outer stresses of the test section on the turbine blade using strain gauges, and calibrating the inner and outer temperatures of the test section on the turbine blade using thermocouples; pre-test setting: connecting the double-freedom fixture to the external air cooler and water cooler respectively to open the cooling air circuit and cooling water circuit; start the test.

[0018] The present application has the following beneficial effects:

[0019] The present application discloses a double-freedom fixture for adjusting the magnitude and direction of the bending moment of a turbine blade, which can be used for fatigue, creep and other tests of turbine blades. In the life test of turbine blades, it is necessary to simulate different bending moment sizes and directions on different sections of the turbine blade. Therefore, the present application designs a double-freedom fixture to realize the simulation of stress distribution on a specific turbine blade height section. The following scheme is adopted: the upper and lower ends of the double-freedom fixture (hereinafter referred to as "fixture") are connected to the upper chuck and lower chuck of the fatigue testing machine through the upper clamping rod and the lower clamping rod respectively, and when the upper clamping rod and the upper adjustable U-shaped head are adjustably connected along the transverse direction intersecting the vertical axis, the eccentricity of the blade load can be adjusted by changing the transverse connection position of the upper clamping rod and the upper adjustable U-shaped head. When the lower clamping rod and the lower adjustable U-shaped head are adjustably connected along the transverse direction intersecting the vertical axis, the eccentricity of the blade load can also be adjusted by changing the transverse connection position of the lower clamping rod and the lower adjustable U-shaped head. On the other hand, the upper and lower ends of the blade clamping member in the blade height direction are threadedly connected to the upper adjustable U-shaped head and the lower adjustable U-shaped head respectively, so that the eccentric angle of the blade load can be adjusted by rotating the blade clamping member.

[0020] Therefore, in the clamp, the eccentricity and eccentric angle of the turbine blade during the test can be adjusted, the bending moment direction and relative size of different sections of the turbine blade during the test can be realized, and the purpose of simulating the real load is achieved. Meanwhile, the design of the clamp considers the simplicity and practicability of operation, and the size and direction of the bending moment can be quickly adjusted by the operator through simple operation, so that the requirement of rapid test is met. The design of the clamp also considers the convenience of maintenance and replacement, and the main components of the clamp are designed as modules, so that the clamp is convenient to disassemble and replace. The design reduces the maintenance time and cost, and improves the service life of the clamp.

[0021] In addition to the purposes, features and advantages described above, the present application has other purposes, features and advantages. The present application will be further described below with reference to the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0022] The accompanying drawings, which form a part of this application, are included to provide a further understanding of the application, illustrate the preferred embodiments of the application and assist in

[0023] Figure 1 A front view of a double-freedom-degree clamp capable of adjusting the size and direction of a turbine blade bending moment according to a preferred embodiment of the present application;

[0024] Figure 2 A front view of a double-freedom-degree clamp capable of adjusting the size and direction of a turbine blade bending moment according to a preferred embodiment of the present application; Figure 1 A front view of a double-freedom-degree clamp capable of adjusting the size and direction of a turbine blade bending moment according to a preferred embodiment of the present application;

[0025] Figure 3 A front view of a double-freedom-degree clamp capable of adjusting the size and direction of a turbine blade bending moment according to a preferred embodiment of the present application; Figure 1 A front view of a double-freedom-degree clamp capable of adjusting the size and direction of a turbine blade bending moment according to a preferred embodiment of the present application;

[0026] Figure 4 A front view of a double-freedom-degree clamp capable of adjusting the size and direction of a turbine blade bending moment according to a preferred embodiment of the present application; Figure 1 A front view of a double-freedom-degree clamp capable of adjusting the size and direction of a turbine blade bending moment according to a preferred embodiment of the present application;

[0027] Figure 5 A front view of a double-freedom-degree clamp capable of adjusting the size and direction of a turbine blade bending moment according to a preferred embodiment of the present application; Figure 1 A front view of a double-freedom-degree clamp capable of adjusting the size and direction of a turbine blade bending moment according to a preferred embodiment of the present application;

[0028] LEGEND

[0029] 1, upper clamping rod; 2, upper cooling water pipe; 3, upper connecting bolt; 4, upper adjustable U-shaped head; 5, upper locking ring; 6, fixed clamp; 7, fixed bolt; 8, blade clamp; 81, exhaust hole; 9, locking bolt; 10, heating coil; 11, turbine blade;

[0030] 12, mortise clamp; 121, air inlet hole; 13, lower locking ring; 14, lower adjustable U-shaped head; 15, lower connecting bolt; 16, lower clamping rod; 17, lower cooling water pipe. DETAILED DESCRIPTION

[0031] The embodiments of the present application will be described in detail below with reference to the accompanying drawings, but the present application can be implemented in various different ways as defined and covered by the following description.

[0032] Reference Figure 1 and Figure 5 The preferred embodiment of the present application provides a double-freedom fixture for adjusting the magnitude and direction of the bending moment of a turbine blade, comprising: blade clamping members for clamping and fixing the turbine blade 11 at both ends along the height direction of the turbine blade 11 to be tested, an upper adjustable U-shaped head 4 and a lower adjustable U-shaped head 14, an upper clamping rod 1 and a lower clamping rod 16. The upper and lower ends of the blade clamping members along the height direction are respectively threadedly connected to the upper adjustable U-shaped head 4 and the lower adjustable U-shaped head 14, and the other ends of the upper adjustable U-shaped head 4 and the lower adjustable U-shaped head 14 are respectively connected to the upper clamping rod 1 and the lower clamping rod 16. The other ends of the upper clamping rod 1 and the lower clamping rod 16 are respectively connected to the upper chuck and the lower chuck of the fatigue testing machine, so that the upper clamping rod 1, the upper adjustable U-shaped head 4, the blade clamping members, the lower adjustable U-shaped head 14 and the lower clamping rod 16 are connected in sequence along the vertical axis between the upper chuck and the lower chuck of the fatigue testing machine. The upper clamping rod 1 and the upper adjustable U-shaped head 4, and / or the lower clamping rod 16 and the lower adjustable U-shaped head 14 are adjustably connected in pairs along the transverse direction intersecting the vertical axis to adjust the eccentricity of the turbine blade 11 load. The rotation of the blade clamping members can adjust the eccentric angle of the blade load.

[0033] The present application discloses a double-freedom fixture for adjusting the magnitude and direction of the bending moment of a turbine blade, which can be used for fatigue, creep and other tests of turbine blades. In the life test of turbine blades, it is necessary to simulate different bending moment sizes and directions on different sections of turbine blades. Therefore, the present application designs a double-freedom fixture to achieve stress distribution simulation on a specific turbine blade height section. The following solutions are adopted: the upper and lower ends of the double-freedom fixture (hereinafter referred to as "fixture") are respectively connected to the upper chuck and the lower chuck of the fatigue testing machine through the upper clamping rod 1 and the lower clamping rod 16. When the upper clamping rod 1 and the upper adjustable U-shaped head 4 are adjustably connected in the transverse direction intersecting the vertical axis, the eccentricity of the blade load can be adjusted by changing the transverse connection position of the upper clamping rod 1 and the upper adjustable U-shaped head 4. When the lower clamping rod 16 and the lower adjustable U-shaped head 14 are adjustably connected in the transverse direction intersecting the vertical axis, the eccentricity of the blade load can also be adjusted by changing the transverse connection position of the lower clamping rod 16 and the lower adjustable U-shaped head 14. On the other hand, the upper and lower ends of the blade clamping members along the height direction are respectively threadedly connected to the upper adjustable U-shaped head 4 and the lower adjustable U-shaped head 14. Therefore, the eccentric angle of the blade load can be adjusted by rotating the blade clamping members.

[0034] Therefore, in the clamp of the present application, by adjusting the eccentricity and the eccentric angle of the turbine blade 11 during the test, the bending moment direction and the relative size of different sections of the turbine blade 11 during the test can be realized, so as to achieve the purpose of simulating the real load. At the same time, the design of the clamp considers the simplicity and practicability of the operation. Through simple operation, the operator can quickly adjust the size and direction of the bending moment to meet the demand of rapid test. The design of the clamp also considers the convenience of maintenance and replacement. The main components of the clamp are designed as modularization, which is convenient for disassembly and replacement. This design reduces the maintenance time and cost, and improves the service life of the clamp.

[0035] Alternatively, as shown in Figure 1 and Figure 2 , the blade clamping component includes a blade head 8 for clamping and fixing the upper end blade of the turbine blade 11, a fixed head 6 connected to the blade head 8, and a mortise head 12 for clamping and fixing the lower end tenon of the turbine blade 11. The fixed head 6 is threadedly connected to the lower end of the upper adjustable U-shaped head 4, and the threaded connection part is further sleeved with an upper locking ring 5 for locking the fixed head 6. The lower end of the mortise head 12 is threadedly connected to the upper end of the lower adjustable U-shaped head 14, and the threaded connection part is further sleeved with a lower locking ring 13 for locking the mortise head 12. In this optional scheme, the eccentric angle of the blade load can be adjusted by relatively rotating the upper adjustable U-shaped head 4 and the fixed head 6, or relatively rotating the mortise head 12 and the lower adjustable U-shaped head. The adjustment operation is simple, and can be adjusted steplessly in the circumferential direction. After adjustment, the fixed head 6 can be locked and fixed by the corresponding upper locking ring 5, or the mortise head 12 can be locked and fixed by the lower locking ring 13.

[0036] In this optional scheme, as shown in Figure 1 and Figure 3 , the blade head 8 includes a left head and a right head which are oppositely arranged and have an "L" shaped cross section, a locking bolt 9, and a fixing bolt 7. The fixed head 6 is arranged between the upper ends of the left head and the right head. The fixing bolt 7 is arranged through the left head, the right head, and the fixed head 6 to lock and fix the blade head 8 and the fixed head 6. The upper end of the fixed head 6 is threadedly connected to the lower end of the upper adjustable U-shaped head. In this optional scheme, the number of the fixing bolts 7 is multiple to increase the stability of the connection and locking. The blade of the upper end of the turbine blade 11 is arranged between the lower ends of the left head and the right head. The locking bolt 9 is arranged through the left head and the right head to relatively clamp the left head and the right head to fix the blade, or the locking bolt 9 is arranged through the left head, the right head, and the blade to fixedly connect the blade head 8 and the blade of the turbine blade 11 into an integral whole. In this optional scheme, the number of the locking bolts 9 is multiple to increase the stability of the connection and locking.

[0037] Preferably, the left and right clamps are respectively provided with positioning profiles on the two opposite inner sides, which are matched with the two sides of the turbine blade 11, so as to position the position of the blade in the blade clamp 8 through the matching of the positioning profiles and the blade side, so as to achieve accurate positioning and loading. When different sizes and different models of turbine blades 11 are replaced for testing, the configuration of the blade clamp 8 and the tenon and slot clamp 12 is first determined according to the structural characteristics and test requirements of the turbine blade 11, and then the blade clamp 8 and the tenon and slot clamp 12 matched with the turbine blade 11 are processed, and if there is a small gap, it can be fixed by adding a gasket.

[0038] Optionally, as shown in Figure 1 and Figure 4 , the upper end of the tenon and slot clamp 12 is provided with a tenon and slot cavity matched with the tenon of the turbine blade 11, and the front and rear ends of the tenon and slot cavity extend through the tenon and slot clamp 12 respectively, so that the tenon is slidably installed in the tenon and slot cavity along the extension direction. The upper end of the tenon and slot cavity extends through the top of the tenon and slot clamp 12, so that the blade extends upward out of the tenon and slot clamp 12.

[0039] Preferably, as shown in Figure 3 and Figure 4 , the side wall of the tenon and slot clamp 12 is also provided with an air inlet hole 121 extending through the wall surface, and the air inlet hole 121 communicates with the tenon and slot cavity. The wall surface of the left clamp or the right clamp is also provided with an air outlet hole extending through the wall surface, and the air outlet hole communicates with the cavity between the left clamp and the right clamp, so that the external cooling gas machine, the tenon and slot clamp 12, the tenon, the blade and the blade clamp 8 are communicated to form a cooling gas circuit, which is used to provide cooling gas for the internal passage of the blade, so as to simulate the real running environment and improve the test accuracy.

[0040] Optionally, as shown in Figure 1 and Figure 2 , the two-degree-of-freedom clamp for adjusting the size and direction of the turbine blade bending moment also includes a heating coil 10 for heating the turbine blade 11. The heating coil 10 is arranged on the outer circle of the blade of the turbine blade 11 between the blade clamp 8 and the tenon and slot clamp 12. The clamp of the present application is used for fatigue, creep and other tests of turbine blades. In the life test of the turbine blade, in addition to the need to simulate different bending moment sizes and directions on different sections of the turbine blade 11, the temperature distribution on different sections also needs to be simulated. Therefore, the clamp of the present application is provided with a heating coil 10 connected with external heating equipment to realize the temperature distribution simulation on the specific turbine blade 11 high section.

[0041] Optionally, as shown in Figure 1 and Figure 2As shown, the upper clamping rod 1 and the lower clamping rod 16 are of the same structure, and the upper adjustable U-shaped head 4 and the lower adjustable U-shaped head 14 are of the same structure. The upper adjustable U-shaped head 4 comprises a U-shaped connector at its upper end and a connecting screw rod connecting the lower closed end of the U-shaped connector. The upper end of the upper clamping rod 1 is cut to form a plate-shaped connecting part, which extends into the U-shaped connector, and the upper clamping rod 1 is adjustably connected with the upper adjustable U-shaped head 4 through the upper connecting bolt 3 penetrating the U-shaped connector and the connecting part, and the eccentricity of the turbine blade 11 load can be adjusted by adjusting the position of the connecting part in the width direction of the U-shaped connector, as shown in Figure 5 The connecting screw rod is screwed with the fixed clamp 6 below to adjust the eccentricity of the blade load by rotating the fixed clamp 6. Similarly, the lower adjustable U-shaped head 14 comprises a U-shaped connector at its lower end and a connecting screw rod connecting the upper closed end of the U-shaped connector, and the upper end of the lower clamping rod 16 is cut to form a connecting part which extends into the U-shaped connector above, and the U-shaped connector and the upper end of the lower clamping rod 16 are connected through the lower connecting bolt 15, and the eccentricity of the blade load can also be adjusted by adjusting the position of the connecting part in the width direction of the U-shaped connector.

[0042] Preferably, as shown in Figure 1 and Figure 2 The upper cooling water pipe 2 is vertically provided through the upper clamping rod 1, and the lower cooling water pipe 17 is vertically provided through the lower clamping rod 16, and the upper cooling water pipe 2, the lower cooling water pipe 17 and the external cooling water machine for supplying cooling water are connected to form a cooling water circuit for cooling the clamp to adapt to high temperature loading test.

[0043] The clamp of the present application is used for fatigue, creep and other tests of turbine blades. In the life test of turbine blades, in addition to the need to simulate different bending moment sizes and directions on different sections of turbine blades 11, the temperature distribution on different sections also needs to be simulated. Therefore, the clamp of the present application adopts the following scheme to realize the simulation of stress and temperature distribution on a specific high section of turbine blades 11:

[0044] Stress distribution: the upper and lower parts of the clamp are respectively connected with the fatigue testing machine, and each contains two groups of devices which can independently adjust the eccentricity and eccentricity of the blade load. By adjusting the two degrees of freedom of the upper and lower parts of the clamp, the size and direction of the bending moment can be freely adjusted according to the loading requirements of the turbine blade 11, and the simulation of different stress distributions can be realized.

[0045] Temperature distribution: the clamp of the present application also uses the heating coil 10 to heat the specific section of the turbine blade 11, and the clamp cooling water channel is designed at the upper and lower ends of the clamp; at the same time, the inlet and outlet of the internal cooling gas of the turbine blade are designed in the middle part of the clamp to simulate the internal cooling state of the blade in service.

[0046] The preferred embodiment of the present application also provides a test method using the double-freedom adjustable turbine blade bending moment size and direction clamp of any one of the above, the test method comprising the following steps:

[0047] S10: test clamp assembly: clamp and fix the turbine blade 11 to be tested on the double-freedom clamp, and clamp and connect the double-freedom clamp to the fatigue testing machine;

[0048] S20: blade bending moment load setting: according to the simulation results, adjust the eccentricity and eccentric angle of the blade load applied to the turbine blade 11 to simulate the service load of the turbine blade 11;

[0049] S30: blade temperature load setting: determine the geometry and installation position of the heating coil 10 according to the simulation software, and then adjust the geometry of the heating coil 10 on the turbine blade 11 and the position relative to the turbine blade 11, so that the temperature field of the blade test section conforms to the real working state of the turbine blade 11;

[0050] S40: pre-test stress and temperature load calibration: use strain gauges to calibrate the internal and external stresses of the test section on the turbine blade 11, and use thermocouples to calibrate the internal and external temperatures of the test section on the turbine blade 11;

[0051] S50: pre-test setting: connect the double-freedom clamp to the external air cooler and water cooler respectively to open the cooling circuit and cooling water circuit;

[0052] S60: start test.

[0053] Specifically, the step "S10: test clamp assembly" specifically comprises: first, clamp the upper end of the upper clamping rod 1 with the upper chuck of the fatigue testing machine, clamp the other end of the upper clamping rod 1 with the upper adjustable U-shaped head 4 through the upper connecting bolt 3, and fix it with a gasket, the upper adjustable U-shaped head 4 is connected with the fixed chuck 6 through threads, and is fixedly connected through the upper lock ring 5, the fixed chuck 6 is clamped with the blade chuck 8 through the fixed bolt 7; clamp the lower end of the lower clamping rod 16 with the lower chuck of the fatigue testing machine, clamp the other end of the lower clamping rod 16 with the lower adjustable U-shaped head 14 through the lower connecting bolt 15, the lower adjustable U-shaped head 14 is connected with the mortise chuck 12 through threads, and is also fixed with the lower lock ring 13; then put the turbine blade 11 around the heating coil 10 into the mortise cavity of the mortise chuck 12, adjust the height position of the clamp through the fatigue testing machine, so that the upper part of the turbine blade 11 is matched with the blade chuck 8, and then fix the upper part of the turbine blade 11 through the locking bolt 9; finally, check to ensure that each contact surface is in good contact and each bolt connection is tight and stable, and the test clamp assembly is completed.

[0054] Specifically, the step "S20: blade bending moment load setting" specifically includes: according to the simulation results, simulating the service load of the turbine blade 11, adjusting the eccentricity of the blade load by changing the transverse relative position of the upper clamping rod 1 and the upper adjustable U-shaped head 4, or changing the transverse relative angle of the lower adjustable U-shaped head 14 and the lower clamping rod 16. The eccentric angle of the blade load is adjusted by the screw rotation between the upper adjustable U-shaped head 4 and the fixed clamp head 4, or the screw rotation between the mortise clamp 12 and the lower adjustable U-shaped head 14.

[0055] Specifically, the step "S30: blade temperature load setting" specifically includes: first, using the COMSOL commercial electromagnetic simulation software to carry out full three-dimensional thermal-solid-flow simulation, considering coil heating, internal cooling and external atmospheric natural cooling, determining the geometry of the heating coil 10 and processing it; then connecting the heating coil 10 installed on the outside of the turbine blade 11 with the high-frequency induction heating furnace, opening the high-frequency induction heating furnace to adjust the test temperature before loading the stress load, and adjusting the size, number, shape of the heating coil 10 and the relative position of the test site of the turbine blade 11, so that the temperature field of the blade test site conforms to the real situation of the working state of the turbine blade 11.

[0056] Specifically, the step "S40: stress and temperature load calibration before test" specifically includes: for each test group, the stress and temperature loading state of the test section is calibrated. Since stress is difficult to measure directly, strain measurement results are used instead, by uniformly arranging multiple strain gauges on the test section, combining the 3D-DIC method to obtain the surface stress distribution on the blade body test section, and comparing with the finite element results, and fine-tuning the fixture degrees of freedom until the measured distribution is within the tolerance range of the design distribution, if necessary, the blade can be cut vertically along the blade height at a position away from the test section, strain gauges are attached to the inner wall of the test section, and the blade body is re-welded to obtain the inner wall strain data of the test section. After stress calibration, the blade is cut vertically along the blade height at a position away from the test section, a thermocouple filament with a diameter of 0.6mm is welded at the test section by nickel-based brazing, and then the blade body is welded complete; then several thermocouples are welded at the blade test section, and the inner and outer temperatures of the test section in the thermal stable state are measured by using the thermocouple combined with the thermal imager, and the heating power, cooling gas flow and coil position are adjusted to make the temperature distribution near the section within the design tolerance.

[0057] Specifically, the step "S50: test preparation" specifically includes: connecting the cooling water pipes 2 and 17 to the upper and lower cooling water pipes 2 and 17 respectively, and starting the cooling water pump before the test; the inlet and outlet of the cooling gas pipeline of the cooling gas machine are connected with the exhaust hole 81 in the middle of the blade body clamp 8 and the air inlet hole 121 on the side of the mortise clamp 12 respectively, and the cooling gas is ready to be introduced.

[0058] Specifically, the step "S60: start test" specifically includes: setting stress load in the control module of the fatigue testing machine according to the test load spectrum, setting temperature load in the control module of the high-frequency induction heating furnace, recording the surface image of the blade in real time using a video extensometer, analyzing displacement changes combined with DIC technology, and monitoring the test state in real time; during the test, the turbine blade 11 is first loaded to a certain temperature, and then the fatigue load is applied to the test site of the turbine blade 11 to realize high-temperature load loading test of the blade; when the test load spectrum is loaded or damage occurs, the test is completed.

[0059] According to the above embodiment, it can be found that the present application can apply mechanical load and thermal load to the turbine blade 11 as much as possible, and auxiliary equipment such as a fatigue testing machine, a cold water machine, a cold air machine, a high-frequency induction heating furnace, and a heating coil 10 can meet the needs of thermal mechanical fatigue, low cycle fatigue, creep, and other tests on various turbine blades 11.

[0060] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A two-degree-of-freedom clamp for adjusting the magnitude and direction of the bending moment of turbine blades, characterized in that, include: The blade clamping components, upper adjustable U-head (4) and lower adjustable U-head (14), upper clamping rod (1) and lower clamping rod (16) are used to clamp and fix the turbine blade (11) at both ends along the blade height direction of the turbine blade (11) to be tested. The blade clamping component is threaded to the upper adjustable U-head (4) and the lower adjustable U-head (14) at its upper and lower ends along the blade height direction, respectively. The other ends of the upper adjustable U-head (4) and the lower adjustable U-head (14) are then connected to the upper clamping rod (1) and the lower clamping rod (16), respectively. The other ends of the upper clamping rod (1) and the lower clamping rod (16) are then used to connect to the upper chuck and the lower chuck of the fatigue testing machine, so that the upper clamping rod (1), the upper adjustable U-head (4), the blade clamping component, the lower adjustable U-head (14) and the lower clamping rod (16) are connected in sequence along the vertical axis between the upper chuck and the lower chuck on the fatigue testing machine. Furthermore, the upper clamping rod (1) and the upper adjustable U-head (4), and the lower clamping rod (16) and the lower adjustable U-head (14) are connected in a transversely adjustable manner along the vertical axis to adjust the eccentricity of the load on the turbine blade (11). Furthermore, adjusting the rotation circumference of the blade clamping component can adjust the eccentricity angle of the blade load; The side wall of the tenon chuck (12) is also provided with an air inlet (121) that penetrates the wall surface and connects to the tenon cavity; the wall of the left chuck or the right chuck is also provided with an exhaust hole that penetrates the wall surface and connects to the cavity between the left chuck and the right chuck, thereby connecting the external air cooler, the tenon chuck (12), the tenon, the blade and the blade chuck (8) to form a cooling air circuit; The dual-degree-of-freedom fixture that can adjust the magnitude and direction of the turbine blade bending moment also includes a heating coil (10) for heating the turbine blade (11), the heating coil (10) being mounted on the outer circle of the turbine blade (11) between the blade clamp (8) and the tenon clamp (12); The upper clamping rod (1) and the lower clamping rod (16) have the same structure, and the upper adjustable U-head (4) and the lower adjustable U-head (14) have the same structure. The upper adjustable U-head (4) includes a U-shaped connector located at its upper end and a connecting screw connecting the lower closed end of the U-shaped connector. The two sides of the lower end of the upper clamping rod (1) are cut to form a plate-shaped connecting part. The connecting part extends into the U-shaped connector. The upper clamping rod (1) and the upper adjustable U-head (4) are connected in an adjustable manner by the upper connecting bolt (3) passing through the U-shaped connector and the connecting part. The eccentricity of the turbine blade (11) load can be adjusted by adjusting the position of the connecting part in the width direction of the U-shaped connector. The connecting screw is threaded to the lower fixed chuck (6) so that the eccentricity angle of the blade load can be adjusted by rotating the fixed chuck (6). The upper clamping rod (1) is vertically connected to the upper cooling water pipe (2), and the lower clamping rod (16) is vertically connected to the lower cooling water pipe (17). The upper cooling water pipe (2), the lower cooling water pipe (17) and the external chiller used to supply cooling water are connected to form a cooling water circuit.

2. The dual-degree-of-freedom fixture for adjusting the magnitude and direction of turbine blade bending moment according to claim 1, characterized in that, The blade clamping component includes a blade clamp (8) for clamping and fixing the upper blade body of the turbine blade (11), a fixing clamp (6) for connecting the blade clamp (8), and a tenon clamp (12) for clamping and fixing the lower tenon of the turbine blade (11). The fixed chuck (6) is threaded to the lower end of the upper adjustable U-head (4), and an upper locking ring (5) for locking the fixed chuck (6) is also fitted at the threaded connection between the two. The lower end of the tenon chuck (12) is threaded to the upper end of the lower adjustable U-head (14), and a lower locking ring (13) for locking the tenon chuck (12) is also fitted at the threaded connection between the two.

3. The dual-degree-of-freedom fixture for adjusting the magnitude and direction of turbine blade bending moment according to claim 2, characterized in that, The blade chuck (8) includes a left chuck and a right chuck arranged opposite each other and having an "L" shaped cross section, a locking bolt (9), and a fixing bolt (7); The fixed chuck (6) is installed between the upper ends of the left chuck and the right chuck, and the fixing bolt (7) passes through the left chuck, the right chuck and the fixed chuck (6) to lock and fix the blade chuck (8) and the fixed chuck (6); The blade body at the upper end of the turbine blade (11) is installed between the lower ends of the left and right chucks. The locking bolt (9) passes through the left and right chucks to clamp the left and right chucks together to fix the blade body, or the locking bolt (9) passes through the left and right chucks and the blade body to fix the blade body chuck (8) and the blade body of the turbine blade (11) into a whole.

4. The dual-degree-of-freedom fixture for adjusting the magnitude and direction of turbine blade bending moment according to claim 3, characterized in that, The left and right chucks have positioning surfaces on their two inner sides that are opposite to each other, which are adapted to the sides of the turbine blade (11) so that the blade can be positioned in the blade chuck (8) by adapting the positioning surfaces to the sides of the blade.

5. The dual-degree-of-freedom fixture for adjusting the magnitude and direction of turbine blade bending moment according to claim 3, characterized in that, The upper end of the tenon chuck (12) is provided with a tenon cavity that is adapted to the tenon of the turbine blade (11). The front and rear ends of the tenon cavity extend through the tenon chuck (12) respectively, so that the tenon can slide into the tenon cavity along its extension direction. The upper end of the mortise cavity passes through the top of the mortise clamp (12) so that the blade extends upward out of the mortise clamp (12).

6. A test method, characterized in that, Using a two-degree-of-freedom fixture with adjustable turbine blade bending moment magnitude and direction as described in any one of claims 1-5, the test method includes the following steps: Test fixture assembly: clamp and fix the turbine blade (11) to be tested onto the two-degree-of-freedom fixture, and clamp and connect the two-degree-of-freedom fixture to the fatigue testing machine; Blade bending moment load setting: Based on the simulation results, the eccentricity and eccentricity angle of the blade load applied to the turbine blade (11) are adjusted to simulate the service load of the turbine blade (11); Blade temperature load setting: The geometry and installation position of the heating coil (10) are determined according to the simulation software, and then the geometry and position of the heating coil (10) on the turbine blade (11) relative to the turbine blade (11) are adjusted so that the temperature field of the blade test section conforms to the actual working state of the turbine blade (11). Stress and temperature load calibration before the test: strain gauges were used to calibrate the internal and external stresses of the test section on the turbine blade (11), and thermocouples were used to calibrate the internal and external temperatures of the test section on the turbine blade (11). Pre-test setup: Connect the two-degree-of-freedom fixture to the external air conditioner and water conditioner respectively to connect the cooling air circuit and the cooling water circuit; Begin the experiment.

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