The numerical study on flow and heat transfer performance of convergent swirl cooling chamber roughed with different dimples in turbine blade leading edge

Abstract

This paper focuses on the internal cooling structure of the gas turbine blade leading edge, aiming to promote the heat transfer performance of the swirl cooling channel (SCC) inner walls by adding dimple structures to those walls. The study compares and analyzes the flow and heat transfer characteristics of the straight smooth swirl cooling channel, the smooth converging swirl cooling channel and the converging swirl cooling channels with spherical dimples, 45° oblique dimples as well as 60° oblique dimples. Numerical simulations were conducted to investigate the impact of different wall temperatures, inlet Reynolds numbers and channel wall structures on the heat transfer performance of the internal swirl cooling channel of the blade leading edge. The computational results indicate that among all dimple structures studied in this work, spherical dimples exhibit superior heat transfer performance, with an average wall Nusselt number 21.16 % higher than that of the converging swirl cooling channel without dimples. For different swirl cooling channels in this work, the front surface average Nusselt number tends to ascend with an increasing inlet $\mathrm{Re}$, and the rate of ascent diminishes as the $\mathrm{Re}$ increases. As the inlet Reynolds number increases from 10,000 to 100,000, for these 5 different swirl cooling channels, the front surface average Nusselt number increases by 508.29 %, 442.58 %, 478.75 %, 472.48 %, and 483.41 %, respectively. As the wall temperature is increased from 30 °C to 70 °C, the heat transfer effect is only enhanced by 4.22 %. Although we newly proposed decorating the convergent swirl cooling channel with the oblique dimple to try to achieve higher heat transfer performance, the overall results show that the spherical dimple roughed swirl cooling channel shows higher heat transfer performance and lower pressure loss than the 45° and 60° oblique dimples. When designing the internal cooling channels of the turbine blade leading edge, if a converging swirl cooling structure is adopted, it is recommended to consider decorating the spherical dimples to the swirl channel wall as heat transfer enhancement structures.