A TWO-DIMENSIONAL ANALYTICAL METHOD FOR TURBINE BLADE COOLING DESIGN

摘要

Turbine blade cooling design involves many complex fluid-thermal coupling issues. Using complete 3D CFD and FEA method would increase the cost of computing; on the other hand, the simplified 1D analytical method would lose too much important blade geometric information when employed in preliminary cooling design. In order to shorten design period and improve the design efficiency, the current 2D analytical method has been developed from a conceptual design that stacking a series of 2D radial sections to shape a quasi-3D blade model attached with the internal fluid flow network. Each of those 2D radial sections could maximally retain the actual blade profile, thus making it more authentic for accomplishing the numerical calculations of turbine cascade flow and heat transfer. For the gas side, methods for calculating external heat transfer coefficients have been investigated, and a simple method for considering the effect of thermal barrier coating on 2D conduction model is proposed. For internal cooling channels, a general calculation method of compressible pipe flow under rotating condition has been derived for fast solving coolant mass flow rates and internal heat transfer coefficients supported by empirical correlations of Darcy resistance coefficient and Nusselt number. Those work are significant to achieve the parametric cooling design by means of modifying and controlling geometric parameters and boundary conditions. Consequently, a real turbine blade case by applying the current 2D analytical method to obtain a quasi-3D blade temperature distribution is presented, demonstrating that this 2D analytical method is effective for turbine cooling design.