Particle deposition patterns on high-pressure turbine vanes with aggressive inlet swirl

Abstract

Characteristics of particle migration and deposition were numerically investigated in presence of aggressive swirl at the turbine inlet. The isolated effects of the inlet swirl were considered in detail by shifting the circumferential position of the swirl and by implementing positive and negative swirling directions. Particles were released from the turbine inlet and the resulting deposition on the vanes was determined by using the critical velocity model in a range of particle diameters from 1 to 25 μm. Results show that the particles are more likely to move outwards to the boundary walls of the passage by the action of the swirling flow. However, this could be relieved by increasing the particle size. An imbalance problem of the deposition is found between the adjacent vanes, which could introduce additional inlet non-uniformities towards the downstream rotor and thus accelerate performance degradation of the turbine stage. Overall, the negative swirl case has higher overall capture efficiency within the entire turbine than the positive swirl case for larger particles, and when the inlet swirl is shifted to the mid-passage of the turbine, more deposits could be produced in comparison with the case in which the swirl aims at the vane leading edge.