Equivalent loading device and method for aerodynamic load of rotating blade

Abstract

The invention discloses an equivalent loading device and method for aerodynamic loads of rotating blades, and belongs to the field of rotating machinery. The device comprises test blades, a test wheel disc, a switching section, a motor, a pneumatic nozzle, an air guide pipe, an air guide slip ring, a flow control valve and an air source. The N test blades are uniformly assembled on the test wheel disc and are connected with the motor through the switching section and the air guide slip ring; the pneumatic nozzle is mounted on the test blade; high-pressure gas passes through the flow control valve, the gas guide sliding ring and the gas guide pipe from the gas source and reaches the pneumatic nozzle to be jetted. Equivalent loading of the pneumatic vibration load on the rotating blade is achieved through the pneumatic nozzle. The device has the advantages of simplicity, low energy consumption, simplicity and convenience in operation, high precision and the like. The limitation that only concentrated centrifugal load can be applied in a traditional test is broken through, and the distribution characteristic of the centrifugal load changing in the axial direction during actual operation of the engine is accurately represented. And meanwhile, the problem that an aerodynamic load cannot be applied to the rotating blade in an existing test method is solved, so that the compound vibration environment is simulated more accurately.

Description

Technical Field

[0001] The invention belongs to the field of rotary machinery, relates to blade test technology and tester design, and specifically relates to an equivalent loading device and method for aerodynamic loads of rotary blades. Background Art

[0002] In rotating machinery such as aircraft engines, steam turbines, and compressors, blades are core rotating components that undertake the key task of converting energy. These blades operate for a long time in a complex environment of high pressure and high speed, facing the combined action and continuous impact of multiple loads, which is directly related to the service life of mechanical equipment. With the continuous improvement of the thrust-to-weight ratio of modern rotating machinery and equipment, the design stress level of blades has also increased significantly. Therefore, it is particularly important to conduct research on the dynamic behavior and fatigue life of rotating blades under the action of complex load coupling.

[0003] Rotating blades are mainly subjected to centrifugal loads and aerodynamic loads during normal operation. When the blades rotate at high speed, centrifugal force distributed along the axial direction will be generated, and it will change with the increase or decrease of the speed. Especially in the stages of mechanical equipment startup, shutdown or other non-continuous operation, the centrifugal load changes significantly, which belongs to low-cycle load. At the same time, in the working environment inside the turbine, the blades will vibrate at high frequencies under the action of aerodynamic loads, and vibration loads belong to high-cycle loads. The combined action of these two loads can easily cause the rotating blades to fail due to creep and fatigue coupling, thereby affecting the overall service life of the mechanical equipment. Therefore, in order to gain a deeper understanding of the dynamic characteristics and composite fatigue mechanism of the blades, and to seek ways to improve their fatigue life, it is crucial to conduct composite fatigue life analysis and experimental verification of rotating blades.

[0004] Regarding the load-loading test technology for rotating blades, the most well-known one is that Weser in Germany used a tensile fatigue tester and an exciter in the PREMECCY program to conduct a high- and low-cycle composite fatigue test on blade simulation parts in an airflow environment [1]. However, there are few public reports on this type of test technology. Domestically, Beijing University of Aeronautics and Astronautics used a fatigue tester and an electromagnetic exciter to achieve centrifugal and vibration load loading [2]. The China Aircraft Strength Research Institute independently loaded centrifugal loads through Moog controllers and hydraulic actuators, and loaded vibration loads through electromagnetic vibration tables. It used the method of nesting internal and external fixtures to decouple orthogonal loads and successfully completed the fatigue life test of a ducted tail rotor and reproduced its fatigue damage failure mode [3][4]. However, existing centrifugal load mechanical tests (such as low-cycle fatigue tests) are usually carried out based on the method of loading a stationary blade with concentrated centrifugal force. When applying a tensile load, the theoretically calculated centrifugal load is used to clamp the theoretical dangerous section of the blade at the top to apply the tensile load. Since the centrifugal loads on the radial section of the blade vary in practice, this method cannot fully reproduce the centrifugal load characteristics of the actual rotating blade under working conditions. In addition, existing traditional research is usually unable to simultaneously apply real centrifugal loads and aerodynamic loads on the same blade, making it difficult to accurately simulate the complex vibration environment in actual operation. The main difficulty lies in the difficulty of applying aerodynamic loads on rotating blades.

[0005] References

[0006] [1]Weser S, Gampe U, Raddatz M, et al. Advanced experimental and analytical investigations on combined cycle fatigue (CCF) of conventional cast and single-crystal gas turbine blades[C] / / Turbo Expo: Power for Land, Sea, and Air. 2011,54662:19-28.

[0007] [2]hi D, Li Z, Yang

[0008] [3] Zhang Wei, You Yu, Xu Jian. High-low cycle combined load test and analysis[J]. Engineering and Test, 2020, 60(1): 100-101,127.

[0009] [4] Yu, Zhang, Wei, Yan, Qun, et al. Blade failure reproduction based on high- and low-cycle combined fatigue test technology[J]. Propulsion Technology, 2020, 41(5): 1130-1137. Summary of the invention

[0010] In view of these problems existing in the background technology, the present invention proposes an equivalent loading device and method for the aerodynamic load of rotating blades. This technology realizes the equivalent loading of the aerodynamic load on the rotating blades through a pneumatic nozzle. This innovative loading method solves two main problems in the prior art: first, the traditional test method can usually only apply concentrated centrifugal force when conducting centrifugal load tests, and cannot truly reproduce the distributed characteristics of the centrifugal load along the axial direction under the actual operating state of the engine; second, the existing method cannot apply aerodynamic loads on the rotating blades, so it is difficult to accurately simulate the complex vibration environment in actual operation.

[0011] The present invention applies aerodynamic loads equivalently on rotating blades, providing important technical support for the safe design of blades. The application of the present invention can effectively improve the authenticity and reliability of blade tests in the field of rotating machinery such as aircraft engines, steam turbines, and compressors, and will be helpful for the dynamics and vibration control, high- and low-cycle composite fatigue, and fatigue life prediction of blades in the field of rotating machinery such as aircraft engines, steam turbines, and compressors. Test and verification work.

[0012] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0013] An equivalent loading device for aerodynamic loads of rotating blades, the loading device comprising a test blade, a test wheel, a transfer section, a motor, a pneumatic nozzle, an air guide pipe, an air guide slip ring, a flow control valve and an air source;

[0014] N test blades are evenly assembled on the test wheel and connected to the motor through the adapter section and the air guide slip ring; the pneumatic nozzle is installed on the test blade; the high-pressure gas is ejected from the pneumatic nozzle through the flow control valve, the air guide slip ring and the air guide pipe from the gas source.

[0015] The air-guiding slip ring comprises a rotating mover and a stationary stator, the stator is fixed on a foundation, and the mover is connected to a motor; one end of the transition section is connected to the mover of the air-guiding slip ring, and the other end is connected to a wheel disc.

[0016] The gas comes out from the gas guide slip ring and reaches the pneumatic nozzle through the gas guide pipe, and the gas guide pipe is fixed on the surface of the test wheel and the test blade.

[0017] A method for equivalent loading of aerodynamic loads on rotating blades using the above device is disclosed, wherein a motor drives a test wheel and a test blade to rotate so as to apply a real centrifugal load to the test blade; an air guide ring is responsible for transmitting high-pressure gas to a high-speed rotating pneumatic nozzle, and the high-pressure gas injection generates a reaction force, thereby equivalently simulating the aerodynamic load borne by the rotating blade.

[0018] Furthermore, the size of the pneumatic load is adjusted by a flow control valve.

[0019] Furthermore, the number of aerodynamic nozzles on each test blade depends on the blade size and specific operating conditions.

[0020] The strength and tongue and groove design of the test wheel are consistent with those of the wheel actually in use to ensure the test's close-to-service characteristics and reliability.

[0021] The beneficial effects of the present invention compared to the prior art are as follows: the present invention realizes equivalent loading of aerodynamic vibration loads on rotating blades through pneumatic nozzles. It has the advantages of simple device, low energy consumption, easy operation and high precision. This technology breaks through the limitation that only concentrated centrifugal loads can be applied in traditional tests, and accurately reproduces the distribution characteristics of centrifugal loads along the axial direction when the engine is actually running. At the same time, it also overcomes the problem that existing test methods cannot apply aerodynamic loads on rotating blades, thereby more accurately simulating complex vibration environments. The implementation of the present invention not only improves the authenticity and reliability of the test, but also has important practical significance and broad application prospects for the design and testing of blades in the field of rotating machinery such as aircraft engines, steam turbines, and compressors. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic side view of the structural arrangement of the present invention;

[0023] Figure 2 It is a front view schematic diagram of the structural arrangement of the present invention and a partial view thereof;

[0024] Among them, 1-test blade, 2-test wheel, 3-transfer section, 4-motor, 5-pneumatic nozzle, 6-air guide pipe, 7-air guide slip ring, 8-flow control valve, 9-air source. DETAILED DESCRIPTION

[0025] The specific implementation of the present invention is described in detail below, but it should be understood that the protection scope of the present invention is not limited by the specific implementation. 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.

[0026] Embodiment 1:

[0027] like Figures 1-2 The equivalent loading device and method of the aerodynamic load of a rotating blade shown in the figure mainly comprises a test blade 1, a test wheel disc 2, a switching section 3, a motor 4, a pneumatic nozzle 5, an air guide pipe 6, an air guide slip ring 7, a flow control valve 8 and an air source 9. N test blades 1 are evenly mounted on the test wheel disc 2 and connected to the motor 4 through the switching section 3 and the air guide slip ring 7. A pneumatic nozzle 5 is mounted on each test blade 1; high-pressure gas is ejected from the air source 9 through the air guide pipe 6, the flow control valve 8 and the air guide slip ring 7 to the pneumatic nozzle 5.

[0028] Specifically, the motor (4) drives the test wheel disc (2) and the test blade (1) to rotate, providing a real distributed centrifugal load; the pneumatic nozzle 5 is used to spray high-pressure gas to provide equivalent aerodynamic force to simulate the aerodynamic vibration load. Furthermore, the size of the aerodynamic equivalent load can be adjusted by the flow control valve 8; the strength and the tongue and groove design of the test wheel disc 2 are consistent with those of the actual wheel disc in use, so as to ensure the accuracy and reliability of the test.

[0029] The present invention can accurately realize the equivalent loading of the aerodynamic load of the rotating blade, construct more realistic experiments on the dynamics and vibration control of the rotating blade, high- and low-cycle combined fatigue, and fatigue life prediction, and provide verification and guidance for the design and safe use of advanced rotating mechanical equipment.

[0030] As in Example 1, by using the device and method proposed in the present invention, it is possible to more accurately achieve equivalent loading of the aerodynamic load of the rotating blades, construct a near-service environment for the rotating blades, and carry out experimental studies on dynamics and vibration control, high- and low-cycle combined fatigue, and fatigue life prediction.

Claims

1. An equivalent loading device for aerodynamic loads of rotating blades, characterized in that: The loading device comprises a test blade (1), a test wheel disc (2), a transfer section (3), a motor (4), a pneumatic nozzle (5), an air guide pipe (6), an air guide slip ring (7), a flow control valve (8) and an air source (9); N test blades (1) are evenly mounted on a test wheel (2) and connected to a motor (4) via a transition section (3) and an air guide slip ring (7); a pneumatic nozzle (5) is mounted on the test blade (1); high-pressure gas is ejected from a gas source (9) through a flow control valve (8), an air guide slip ring (7) and an air guide pipe (6) to the pneumatic nozzle (5).

2. A method for equivalent loading of aerodynamic loads on rotating blades using the device of claim 1, characterized in that: The method comprises the following steps: a motor (4) drives a test wheel (2) and a test blade (1) to rotate, so as to apply a real centrifugal load to the test blade (1); an air guide ring (7) is responsible for transmitting high-pressure gas to a high-speed rotating pneumatic nozzle (5), and the high-pressure gas jet generates a reaction force, thereby equivalently simulating the pneumatic load borne by the rotating blade.

3. The equivalent loading method for aerodynamic loads of rotating blades according to claim 2, characterized in that: The size of the pneumatic load is adjusted by a flow control valve.

4. The equivalent loading method for aerodynamic loads of rotating blades according to claim 2, characterized in that: The number of pneumatic nozzles (5) on each test blade (1) depends on the blade size and specific working conditions.

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