Seal assembly including grooves in an aft facing side of a platform in a gas turbine engine

A seal assembly between a disc cavity and a hot gas path in a gas turbine engine includes a stationary vane assembly and a rotating blade assembly axially upstream from the vane assembly. A platform of the blade assembly has a radially outwardly facing first surface, an axially downstream facing second surface defining an aft plane, and a plurality of grooves extending into the second surface such that the grooves are recessed from the aft plane. The grooves are arranged such that a circumferential space is defined between adjacent grooves. During operation of the engine, the grooves impart a circumferential velocity component to purge air flowing out of a disc cavity through the grooves to guide the purge air toward a hot gas path such that the purge air flows in a desired direction with reference to a direction of hot gas flow through the hot gas path. 种在燃气涡轮发动机中位于盘腔和热气体路径之间的密封组件包括固定轮叶组件和旋转叶片组件，旋转叶片组件位于轮叶组件的轴向上游。叶片组件的平台具有：径向向外面向的第表面；轴向下游面向的第二表面，其限定后部平面；以及多个凹槽，其延伸至第二表面中使得凹槽从后部平面凹入。凹槽布置成使得在相邻凹槽之间限定周向空间。在发动机的操