Computational Investigations of Effect of Reynolds Number on Secondary Losses and Flow Behavior in Linear Turbine Cascade

Abstract

Abstract Secondary losses in modern gas turbines are one of the challenging factors among turbine designers and manufacturers which significantly impact the overall gas turbine performance. This study is aimed to provide an insight of the mechanism underlying the secondary loss contribution with the variation of Reynolds Numbers. Firstly, the baseline secondary flow losses are investigated for the 2nd stage low-pressure turbine (LPT) vane root profile of the energy efficient engine (E3) developed by Pratt & Whitney using numerical simulations. Then, the effect of various vane exit Reynolds Numbers ranging from 0.7 × 105 to 6 × 105 on the end wall secondary losses are investigated. The results indicate that the total pressure loss of the linear turbine vane cascade increases with the lower operating Reynolds Number. At higher Reynolds number, the passage vortex and wall-vortex induced by passage vortex shows span-wise extension and limits the passage extension which results in lower secondary loss. Compared to the baseline case, the study showed an increase of approximately 1.5 times for Re = 0.7 × 105 and a reduction of 4% for Re = 6 × 105 in the total pressure loss coefficient at the measured plane downstream of the trailing edge.