An Investigation of Ingress for an “Air-Cooled” Shrouded Rotating Disk System With Radial-Clearance Seals

Abstract

In order to model the flow between an air-cooled gas turbine rotor and its stationary casing, a simple isothermal plane rotating disk and stator are used. In tests reported earlier, the cavity between the rotor and stator was sealed by a stationary cylindrical shroud, and the dimensionless minimum amount of “coolant,” Cw, min, necessary to prevent a radial inflow (or ingress) of “hot gas” through the axial clearance between the shroud and the rotor, was determined. In the current tests, a number of seals with a radial clearance between the cylindrical shroud and the rotor are tested. Unlike their axial-clearance counterparts, radial-clearance seals can exhibit a pressure-inversion effect, where the pressure inside the cavity increases, rather than decreases, with increasing rotational speed. Using pressure measurements and flow visualization, correlations showing the variation of Cw, min with clearance ratio and rotational Reynolds number are presented, and it is shown that — under equivalent conditions — a seal with a radial clearance can be much more effective than one with an axial clearance.

Experimental and Numerical Investigations of Aerodynamic Aspects of Hot Gas Ingestion in Rotor-Stator Systems With Superimposed Cooling Mass Flow

“…They were operating with no mainstream flow above the rim seal and they give a correlation for the minimum coolant flow rate necessary to prevent the ingress of hot gas. Phadke and Owen (1983) extended this correlation with a variety of radial clearance rim seals again in a test rig without mainstream flow. They showed that the minimum coolant flow was directly proportional to the rotational Reynolds number.…”

Investigation on Thrust and Moment Coefficients of a Centrifugal Turbomachine

“…Daily et al [4], Bayley and Owen [5], Haynes and Owen [6] studied the flow structure theoretically and experimentally in an unshrouded rotor-stator cavity with centrifugal through-flow. By pressure measurements, Phadke and Owen [7] tested the impact of radial-clearance seals on the cavity flow in an air-cooled rotor-stator cavity with centrifugal through-flow. Launder et al [8] investigated the instability patterns of the turbulent flow in a rotor-stator cavity.…”

Interactive Development of Seals, Bearings, andSecondary Flow Systems with the Power Stream

“…25). Daily and Nece 1960] enclosed-cavity flows and Prof. Owen's (Bayley and Owen [1970], Phadke and Owen [1983], and Gin et al [1993]) cavity flow and rim seal measurements provide basic checks for codes. The resuits of Daily and Nece [1960] [1987]; the generic cavity and parametric definitions are given in Figure 26.…”