Micro particle inertial separation mechanism of turbine blade dirt purge holes

Purpose The results indicate that micron-scale particles undergo multiple collisions during their transport through the cooling channels. Micron-sized particles under 5 µm rarely collide with the blade tip, whereas those larger than 5 µm are mainly concentrated in impacting the leading-edge region. According to the law governing collision between particles and the blade tip, cylindrical and conical dirt purge holes (0.3 mm in diameter) are designed 1.5–3 mm from the leading edge. Design/methodology/approach Numerical simulations were conducted to investigate the transport characteristics and inertial separation dirt purging mechanism of 1–100 µm particles in the U-shaped cooling channels of turbine blades. Findings The dirt purge ratio of particles increases with particle size but shows little change for particles above 28 µm. The distance from the leading edge has a significant effect on the dirt purge ratio, particularly for conical holes. The maximum dirt purge ratio of the cylindrical holes is approximately 3%, whereas that of the conical dirt purge holes reaches about 12%. The corresponding mass flow loss ratios are approximately 0.6% and 0.9% of the inlet mass flow rates for cylindrical and conical holes, respectively. Originality/value This paper provides a detailed analysis of the particle separation mechanism of the blade dirt purge holes, based on the transport simulation of micro particles in the cooling channel. The transport characteristics of micro particles in the cooling channel are described. The dirt purge holes promote particle separation. This paper discusses the dirt purge rate of cylindrical and conical dirt purge rate holes. Meanwhile, this paper also investigates the dirt purge ratio of conical holes in various dust environments, with a specific case analyzed in detail.