Method for acquiring temperature gradient of specimen examination section in wall thickness direction in TGMF (thermal gradient mechanical fatigue) test

Abstract

The invention relates to a method for acquiring temperature gradient of a specimen examination section in the wall thickness direction in a TGMF (thermal gradient mechanical fatigue) test. The methodis implemented by steps as follows: (1) completing assembly of a hollow circular tube test piece with an upper clamp, and clamping an upper clamp head on a fatigue test machine; (2) providing dry compressed air with constant pressure and mass flow through an air compressor, a pneumatic triplet and a mass flow controller, and introducing the air into an upper clamp air nozzle; (3) manufacturing twovortex induction heating coils with different turns, adjusting the turns and radii of the coils to ensure uniformity of the temperature field on the outer wall surface of the specimen examination section, and measuring the temperature of the outer wall surface of the specimen examination section by a thermocouple; (4) performing temperature circulation in the zero stress state, enabling the thermocouple and a pitot tube to go deep into an inlet and an outlet in the specimen examination section of through an air flow channel below a specimen, and measuring air flow temperature, total pressureand static pressure at the inlet and outlet respectively; (5) performing fluid-solid coupling calculation by using finite element software to obtain the temperature gradient of the examination sectionin the wall thickness direction.

Description

technical field [0001] The invention relates to a method for obtaining the temperature gradient in the wall thickness direction of a test piece in a TGMF test. The TGMF test (i.e. temperature gradient thermomechanical fatigue test) can be used to study the effects of flow and heat exchange process inside a hollow air-cooled turbine blade on thermomechanical fatigue damage It belongs to the field of material high-temperature mechanical property test and aerospace engine technology. Background technique [0002] Thermomechanical fatigue is the main failure mode of hollow air-cooled turbine blades. Compared with traditional failure modes such as low cycle fatigue, creep and creep-fatigue, thermomechanical fatigue can more accurately describe fatigue, creep, oxidation, etc. Coupling effects of damage factors on turbine blades. With the continuous improvement of the performance of aero-engines, the temperature in front of the turbine is getting higher and higher, and the turbine...

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Problems solved by technology

[0010] The technical problem solved by the present invention is: to provide a method for obtaining the temperature gradient in the wall thickness direction of the test piece in the TGMF test, which overcomes the difficulty in uniform heating of the outer wall of the hollow circular tube test piece in the process of temperature gradient thermomechanical fatigue test, and the Difficult to measure the temperature of the inner surface, and difficult to accurately reflect the temperature of the inner surface of the entire assessment section, it has realized the uniform heating of the outer wall surface of the assessment section of the hollow tube test piece, and accurately obtained the airflow temperature and total pressure at the entrance and exit of the assessment section. In the case of static pressure and fluid-solid coupling calculation combined with finite element software, the temperature gradient in the wall thickness direction of the examination section is obtained, which is used to study the influence of temperature gradient on the thermomechanical fatigue performance of materials

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