A Comparison of Single-Entry and Multiple-Entry Casing Impingement Manifolds for Active Thermal Tip Clearance Control

In this paper, we compare using computational fluid dynamics the aero-thermal performance of two candidate casing manifolds for supplying an impingement-actuated active tip clearance control system aero-engine high-pressure turbine. The geometries are (a) single-entry: annular manifold fed at one circumferential location; (b) multiple-entry: a split into four sectors, with each sector supplied separately from ring main. Both single-entry and multiple-entry systems analysed in paper idealised versions current production engines. Aero-thermal is quantitatively assessed on basis heat transfer coefficient distribution, driving temperature difference between jet wall total pressure loss within turbine system. We predict that mean (defined respect to inlet local temperature) 77% greater than system, primarily because coolant case picks up approximately 40 K main walls, secondarily average Reynolds number impingement holes 1.2 times exhibits many hot cold spots, depending position boxes, while has more predictable field across feed uses 20% available drop, geometry only 2% drop. From results study, consideration holistic design factors, conclude closer optimal solution