On the Design of High-Temperature Gas Turbine Blade Water-Cooling Channels

Abstract

Centrifugal and Coriolis accelerations have a strong impact on the fluid dynamics and heat transfer in the various schemes of water cooling being actively considered for rotating blades in very high temperature gas turbines. Analytical studies of a thin water film in a rotating rectangular channel open to ambient pressure are presented. First, the dynamics of a thin rotating film indicate that for a certain flow rate it thins out into a stable film under the action of the Coriolis force only for a flow depth below a critical thickness. The value of the critical thickness is a function of the tilt angle between the axis of the cooling passage and the radial. Criteria for nucleation and burnout in high speed liquid films are proposed. These criteria are used to estimate the coolant requirements for representative heat fluxes at different ambient pressures. They suggest that coolant demand increases drastically with pressure. The maximum coolant demand at a fixed heat flux would occur in the neighborhood of five bars.