Effects of sand ingestion on the blockage of film-cooling holes

Gas turbines are often subjected to conditions where dirt and sand are ingested into the engine during takeoffs and landings. Given most aero engines do not have filtration systems, particulates can be present in both the main gas path and coolant streams. Particulates can block coolant passages and film-cooling holes that lead to increased airfoil temperatures caused by reduced coolant available for a given pressure ratio across the cooling holes. This study investigated the effects of sand blockage on film-cooling holes placed in a leading edge coupon. The coupon was tested to determine the reduction in flow parameter for a range of pressure ratios, coolant temperatures, metal temperatures, number of cooling holes, sand amounts, and sand diameters. Depending upon conditions, blockages characterized by reduced coolant flow can be as high as 10%.