Theory and analysis of the flow in a cooling air delivery system of turbine blade

Аuthors

Didenko R. A.^1*, Piralishvili S. A.^2**, Vinogradov K. A.^1***

1. United Engine Corporation “Saturn”, 163, Lenin av., Rybinsk, Yaroslavl region, 152903, Russia
2. ,

*e-mail: roman.didenko@npo-saturn.ru
**e-mail: piral@list.ru
***e-mail: kirill.vinogradov@uec-saturn.ru,

Abstract

This paper provides an initial theory observation and analysis of the flow characteristics in

basic components of a cooling air supply system of turbine blade — stationary pre-swirl nozzles, mixing cavity, coverplate receiver holes and rotor-rotor rotating cavity. After leaving the preswirl nozzles, the cooling air flows through a mixing cavity to the rotor-rotor rotating cavity formed by the turbine disk and cover-plate and onto the turbine blade. Pre-swirl nozzles, as first component, were characterized by their discharge and velocity coefficients calculated in stationary and relative frames of reference, total pressure and temperature reduction occurring in a mixing cavity at the coverplate receiver holes inlet. Recommendations of discharge and velocity coefficients calculation are presented. The flow in rotor-rotor rotating cavity could be characterized by rotational Reynolds number Reφ , nondimensional mass flow rate Cw, turbulent flow parameter λT and nondimensional initial swirl ratio β. There are three regions in rotor-rotor rotating cavity: the initial or source region — the area of strong inertial flow; the middle — the area of developed interior core with Ekman-type layers on the walls; the outlet region, where the flow is formed at the blade cooling rim slot inlet. In the interior core the flow structure is close to that of a free vortex. Interaction of the interior core with boundary layers depends upon the rotor-rotor rotating cavity geometry, mass flow rate and swirl ratio. Due to the flow circumferential deceleration and the centrifugal force, recovery of the total pressure and temperature take place in the rotor-rotor rotating cavity in relative motion.

Keywords:

cooling air delivery system, pre-swirl nozzle, mixing cavity, coverplate receiver