燃气透平叶片尾缘内部冷却通道流动与换热特性研究

Study on Flow and Heat Transfer Characteristics in the Trailing Edge Cooling Channel of Gas Turbine Blade

针对更为接近于真实叶片尾缘段的楔形内部冷却通道的流动与换热特性开展了数值研究,分析了不同冷却工质应用在楔形冷却通道中的性能表现以及不同扰流柱结构、柱肋组合冷却结构对尾缘内部冷却通道中的热力特性的影响。研究表明:区别于矩形内部冷却通道,楔形通道中壁面传热系数沿流动方向呈现逐渐升高的趋势;冷却工质对换热性能影响明显,蒸汽的冷却效果优于空气,而在主流冷气中加入少量的微小液滴可明显改善内部通道的换热效果,并且对压力损失几乎不带来负面影响;3种扰流柱结构中圆顶间断型扰流柱结构具有最佳的换热性能,相较于传统扰流柱,其综合换热因子的最大提升可达15.3%;肋片的引入可使壁面传热系数提高24.9%~32.5%,但会造成压力损失的增加;相较于单一的扰流柱阵列冷却方式其综合换热因子仅可提升2%,一定程度改善壁面传热的均匀性。

A numerical investigation on the flow and heat transfer characteristics in a wedged internal cooling channel more close to the real blade trailing edge section was carried out.The performance of different cooling medium used in wedged cooling channel,and the influence of different pin-fin structures and fin rib composite cooling structures on the thermal property of the trailing edge cooling channel were analyzed.The research results show that distinguished from rectangular internal cooling channel,the heat transfer coefficient of the wall surface in wedged channel tends to increase gradually along the streamwise direction.The cooling medium has a significant effect on the heat transfer performance,and the cooling effect of steam is better than that of air.Adding a small amount of micro droplets into the main air conditioner can obviously improve the heat transfer effect of the internal channel,and has almost no negative effect on the pressure loss.Among the three kinds of turbulence pin-fin structures,the dome-shaped discontinuous structure has the best heat transfer performance,and the maximum comprehensive heat transfer factor can be improved up to 15.3%compared with the traditional one.The heat transfer coefficient of the wall surface can be increased by 24.9%to 32.5%with the introduction of ribs,but the pressure loss will be increased.Compared with the single turbulence pin-fin array cooling mode,the comprehensive heat transfer factor can only bring about an increase of 2%,and the uniformity of heat transfer of the wall surface can be improved to a certain extent.