A ROUGHNESS PREDICTION METHOD BY PARTICLE DEPOSITION AND ITS EFFECT ON FLOW AND HEAT TRANSFER IN HIGH-PRESSURE TURBINE CASCADE

Particulate pollutants deposited on the blade surface alter the roughness and profile of the blade, leading to a decrease in the performance of the gas turbine. This paper proposes a method for predicting local roughness and integrates it with a critical velocity model to create a time-stepping calculation framework for particle deposition. This framework may be utilized to compute the alterations in flow and heat transfer caused by particle deposition. The framework was utilized to perform a steady-state numerical simulation on a high-pressure turbine cascade. The findings indicated that particles larger than 2 μm are primarily deposited on the pressure side, whereas smaller particles are mainly deposited on the suction side. As the diameter of the injected particles increases, the capture efficiency exhibits a trend of initially increasing and then decreasing, regardless of whether it is on the pressure or suction side. With the increase in operating time, particle deposition leads to a gradual rise in the surface roughness of the blade, although the extent of the increase gradually diminishes. Moreover, the roughness variations on the pressure side are more pronounced than those on the suction side. Changes in the blade surface roughness significantly impact the heat transfer coefficient on the blade surface. An increase in roughness at the blade's leading edge results in a decrease in the heat transfer coefficient, while an increase in roughness elsewhere on the blade leads to an increase in the heat transfer coefficient. Furthermore, as operating time increases, the magnitude of the increase or decrease in the heat transfer coefficient gradually diminishes.