A method for identifying and visualizing foreign particle motion using time-resolved particle tracking velocimetry

Gas turbines for aircraft are designed for operation with a clean inlet air flow. This ideal operational condition is often violated during take-off and landing, where the probability of particle ingestion is high, with sand and dirt being the most commonly observed foreign particles. Current research on particle ingestion has identified several mechanisms that contribute to performance degradation in the turbine: erosion of internal and external surfaces, and flow blockages of film-cooling holes and internal cooling passages. The focus of the study given in this paper is to present a method that identifies the motion of foreign particles within an internal ribbed passage. The method uses a high-resolution, flow field interrogation method known as time-resolved digital particle image velocimetry (TRDPIV). Observations from the two-phase flows showed that particle collisions occurred more frequently on the upstream surface of the ribs, especially in the inlet region. Results from these collisions included substantial particle breakup, and a particle rebounding phenomenon between the upper and lower walls. Comparisons are made to large eddy simulation predicted particle trajectories indicating some agreement, as well as phenomena that are not predicted due to the inherent assumption of the modeling.