Numerical Investigation on Cooling Performance of Rectangular Channels Filled with X-Shaped Truss Array Structures

Abstract

In this study, different layout schemes for an X-shaped truss array channel are designed to explore the application of an X-shaped truss array structure in the mid-chord region of turbine blades. The flow and heat transfer performance of X-shaped truss array channels for three layout schemes are numerically investigated. The influence laws of the subchannel height ratio (h/H, 0.2 to 0.4) regarding the cooling performance of the channel with three subchannels are also analyzed. Then, the corresponding heat transfer and friction correlations are obtained. The results show that the layout scheme has significant effects on the flow performance, heat transfer performance and comprehensive thermal performance of X-shaped truss array channels. Among the three layout schemes of X-shaped truss array channels, the single channel has the best flow performance, while the channel with three subchannels has the best heat transfer performance and a comprehensive thermal performance. At different Reynolds numbers, the average Nusselt numbers and comprehensive thermal coefficients of the X-shaped truss array channel with three subchannels range from 38.94% to 63.49% and 27.74% to 46.49% higher than those of a single channel, respectively, and from 5.68% to 18.65% and 11.61% to 21.96% higher than those of the channel with two subchannels, respectively. For the channel with three subchannels, the subchannel height ratio has a great influence on the flow performance, but has a relatively small influence on the heat transfer performance and comprehensive thermal performance of the channel. With the increase in subchannel height ratio, the friction coefficient and average Nusselt number of the channel with three subchannels both show a trend of first increasing and then decreasing, while the comprehensive thermal coefficient shows a slow decreasing trend at higher Reynolds numbers. As a result of comprehensive consideration, the channel with three subchannels at a subchannel height ratio of 0.25 has a better overall cooling performance and is more suitable for cooling the mid-chord region of gas turbine blades. The results may provide a reference for the application of truss array structures in the internal cooling of advanced high-temperature turbine blades in the future.