关键词: 凹陷, 涡发生器, 燃气轮机冷却, 传热, 摩擦因子

Abstract:

Abstract： Dimples are very effective structures to enhance heat transfer. Based on numerical simulations, this paper investigated the heat transfer and friction factor of sphere, eliptical, inclined eliptical and teardrop dimple. Comparisons of the heat transfer and friction factor results obtained by using the Relizable k-ε, SST, and Standard k-ω models with the experimental results indicate that the Standard k-ω model can best predict the flow and heat transfer in the dimpled channels. The heat transfer and flow structure characteristics in the four dimpled channels have been obtained and compared with each other for the Reynolds numbers of 8 500 to 60 000.The Matlab software is used in this paper to process the numerical data to get the heat transfer distribution along the streamwise direction. The study shows that compared to the flat channel, the sphere dimple enhances the heat transfer by 40% and the friction factor by 70%; the eliptical dimple enhances the heat transfer by 30% and the friction factor by 60%;the inclined eliptical dimple enhances the heat transfer by 40% and the friction factor by 60%; and the teardrop dimple enhances the heat transfer by 70% and the friction factor by 100%. Generally speaking, the teardrop dimple has the best heat transfer and overall performance.

Key words: dimple, vortex generator, gas turbine cooling, heat transfer, friction factor