Study on flow and heat transfer performance of X-type truss array cooling channel

Abstract

In this study, an innovative cooling channel filled with a novel X-type truss array structure was proposed to improve the cooling effect of turbine blade mid-chord region. The flow and heat transfer characteristics of the X-type truss array cooling channel were analyzed numerically. The influences of Reynolds number (ReH = 10,000–60,000), truss rod diameter ratio (d/H = 0.1–0.3), transverse spacing ratio (Xs/C = 1-3) and streamwise spacing ratio (Zs/C = 1-3) on the cooling performance of X-type truss array channel were investigated. Then the empirical correlations of heat transfer coefficient and friction factor were obtained by nonlinear regression method for the X-type truss array cooling channel. The results show that horseshoe vortexes form around each truss rod of truss elements. The high heat transfer regions mainly appear in the downstream of each truss rod on the channel wall as well as the windward side of truss rod surface. Increasing ReH can effectively enhance the heat transfer coefficient of the X-type truss array cooling channel, but has little influence on the friction factor of the channel. When d/H increases from 0.1 to 0.3, the friction factors of the X-type truss array channel increases about 3.5–4.4 times, and the average Nusselt numbers of the channel increase by 57.5%–87.9%. When Xs/C increases from 1 to 3, the friction factors and the average Nusselt numbers of the channel decrease by 83.9%–85.1% and 44.9%–57.7% respectively. The friction factor and average Nusselt number of X-type truss array cooling channel both first increase and then decrease with the increase of Zs/C. The moderate values of d/H, Xs/C and Zs/C can make the comprehensive thermal performance of X-type truss array cooling channel better. The results may provide a guidance and reference for the application of X-type truss array structure in the internal cooling channel of advanced gas turbine blades.