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

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, C_w,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 G_c = 0.0025 and G_c = 0.04, and rotational Reynolds numbers between Re_θ = 2 × 10⁵ and Re_θ = 10⁶) by C_w,min = cG_cⁿRe_θ