Considerations of a double-wall cooling design to reduce sand blockage

Gas turbine engines use innovative cooling techniques to keep metal temperatures down while pushing the main gas temperature as high as possible. Cooling technologies such as film-cooling and impingement-cooling are generally used to reduce metal temperatures of the various components in the combustor and turbine sections. As cooling passages become more complicated, ingested particles can block these passages and greatly reduce the life of hot section components. This study investigates a double-walled cooling geometry with impingement- and film-cooling. A number of parameters were simulated to investigate the success of using impingement jets to reduce the size of particles in the cooling passages. Pressure ratios typically ranged between those used for combustor liner cooling and for blade outer air seal cooling whereby both these locations typically use double-walled liners. The results obtained in this study are applicable to more intricate geometries where the need to promote particle breakup exists. Results indicated that ingested sand had a large distribution of particle sizes where particles greater than 150 μm are primarily responsible for blocking the cooling passages. Results also showed that the blockage from these large particles was significantly influenced and can be significantly reduced by controlling the spacing between the film-cooling and impingement-cooling plates.