Study on applicability simulation of blade thermal shock test conditions and the consistency of life

Spray cooling is commonly used in thermal shock tests of turbine blades to accelerate the testing process by creating high-temperature and low-temperature cycling conditions. Although spray cooling can improve efficiency and reduce costs, it significantly reduces the thermal fatigue resistance of the blades. Moreover, the life assessment under spray cooling conditions differs from the actual operating conditions of aeroengines, making it difficult to quantify its impact on blade life. This paper establishes a multi-field coupling simulation model under thermal shock conditions. Based on the Manson-Coffin formula, it proposes a modified life prediction model for predicting the thermal fatigue life of a typical turbine blade with K417G material suffered to thermal shock. The reliability of the model is validated with thermal fatigue test data, and the impact of spray cooling on the thermal fatigue life of the blades is quantitatively evaluated. The simulation results show that during spray cooling, the blade trailing edge experiences an abrupt temperature gradient change, leading to localized thermal stress concentration. The maximum thermal strain reaches 2.88 × 10⁻³, and the peak thermal stress reaches 540.84 MPa. Using the modified life prediction model, the thermal fatigue life under this working condition is calculated to be 4714 cycles, which is consistent with the test results. The study validates the feasibility of spray cooling in simulating engine thermal cycle cooling process, providing theoretical support for accelerating thermal shock test design and life assessment.