An Investigation of Ingress for a Simple Shrouded Rotating Disc System With a Radial Outflow of Coolant

Abstract

A plane rotating disc and a plane stator with a cylindrical shroud are used to model the more complex geometry of an air-cooled gas turbine rotor. “Cooling” air, which is supplied to the center of the stator, leaves radially through the clearance between the rotating disc and a stationary shroud, and flow visualization and pressure measurements are used to determine the minimum dimensionless mass flow rate, Cw,min, of cooling air necessary to prevent the ingress of external fluid at the periphery of the system. From theoretical considerations, the results are correlated (for a gap ratio of G = 0.1, shroud clearance ratio between Gc = 0.0025 and Gc = 0.04, and rotational Reynolds numbers between Reθ = 2 × 105 and Reθ = 106) by Cw,min = cGcnReθ