Coupled flow network model and CFD analysis for a combined impingement and film cooled gas turbine nozzle guide vane

Abstract

The nozzle guide vane (NGV) of a gas turbine engine possesses complex cooling passages, with inherent thermo-fluid dynamic interactions between the vane and the main stream. The present paper is an attempt to make use of the Computational Fluid Dynamics(CFD) tools as well as the flow network analysis tools, in combination, for analyzing typical cooled NGV flow passages. CFD results containing the static and total pressure contours are presented in the paper and are summarized as simple correlating relations; these in turn are used to generate the discharge coefficients as input to the flow network. The pressure conditions at different boundary nodes are further input to the flow network analysis. The mass flow rate and pressure drop values through the impingement and film holes are obtained as output from the flow network model. Comparison of the results from one-dimensional approach coupled with three-dimensional CFD analysis with the available literature by Jin et al. [7] shows a good agreement for the operating pressure ratio in the range of 1.2 to 1.5 at pressure surface rows of the film cooling holes in the leading edge region of the vane. The accuracy of the calculated total pressure ratio on the pressure surface rows of the leading edge circuit has been found satisfactory.The coolant from FIT and AIT are 25.5% and 74.5% respectively. The secondary fluid flows from FIT is 24.3% fed to the leading edge film holes, while 51.9% of coolant is fed to the mid-chord region through the film holes, 22.5% coolant flows out of the trailing edge film holes and the remaining 1.3% flows through trailing edge slot