【作者】 吕敏；

【导师】 李少华；

【作者基本信息】 东北电力大学 ， 工程热物理， 2012， 硕士

【摘要】 气膜冷却作为一种有效的保护手段被越来越多的应用在燃气轮机叶片上。由于燃气透平内部流场的复杂性，使得气膜冷却效果受到许多因素不同程度的影响，其中一个主要因素是来自上游静叶的尾迹传播。静叶尾迹导致自由流产生周期性变化的不稳定速度场和温度场，进而影响下游动叶气膜冷却效果，因此研究非定常尾迹对动叶气膜冷却效果的影响具有重要的意义。本文采用SST k-ω紊流模型，在SIMPLE算法基础上，利用有限体积法对控制方程进行离散。首先研究了不同吹风比、不同转速时非定常尾迹对动叶前缘气膜冷却和叶片传热以及周围流场的影响，得到了各工况下的冷却射流流线图、气膜冷却效率分布图、努赛尔数分布图和流场瞬时湍动能图，经过比较分析发现：吹风比的增大将改变出流状况，使射流发生旋转并偏向叶顶方向流动，提高转速将加剧射流的旋转，甚至改变出流方向；气膜孔附近的冷却效率随着吹风比的增大而增大，但吸力面孔下游的冷却效率有所降低，转速的增大加速了射流与主流的扰动，提高了气膜孔周围的冷却效率，但在n=2000rpm时，第三排孔附近的冷却效果减弱；吹风比增大使得叶片表面整体换热增强，但转速对换热的影响比较复杂，M=1.0时压力面的换热较好，n=500rpm时吸力面的换热较好；吹风比的增大导致气膜孔附近流场的紊流加剧，转速增大则导致动静间叶栅通道的紊流急剧，气动损失较大。由于上游尾迹以一定的频率扫过动叶前缘，导致流场和叶片周围的物理参数发生周期性的变化。通过研究一个周期内不同时刻动叶周围流场的瞬时等温图、湍动能图、马赫数图和传热系数图，得到如下结论：0.5T（T为周期）时刻到1.0T时刻期间气膜温度较低且覆盖较广，0.9T时刻的冷却效果最为理想；整个周期里湍动能、马赫数和传热系数的变化不是很大，湍动能较大值集中在第一排射流附近和动叶尾缘处，在0.7T时刻，动静叶栅间通道的马赫数较大，动叶压力面侧射流孔附近的换热系数较大，吸力面侧中部的换热系数较高，但在尾缘处有所下降。更多还原

【Abstract】 The film cooling gas as a kind of protection means were widely used in gasturbine blade. Because of the complexity of the internal flow field of the gas turbine,many factors influence the effect of gas film-cooling, one major factor is the trail ofstatic leaves from spread. Static leaves make the freedom trail produce not stable flowvelocity and temperature fields periodically, and then to effect film-cooling of blade.,so the unsteady wake to move leaves film cooling effect of the gas has importantsignificance.This paper adopts SST k-ω turbulence model based on SIMPLE algorithm anddiscretizes the control equation using finite volume method. Firstly, the influence ofunsteady wake on film-cooling of blade, heat transfer and flow field around of bladehave been studied, got the path chart of cooling, gas jet film cooling efficiency map,Nusselt number distribution and flow field instantaneous turbulent kinetic energyfigure, through comparison analysis, we found that：The increasing of blow ratio willchange the flow condition, make jet occurred to the blade tip rotation and direction,improving speed will heighten jet spinning, and even change the flow direction；Withthe increasing of blow ratio, film-cooling efficiency nearby jet hole increases, butfilm-cooling efficiency of downstream film hole reduces, the speed increaseaccelerated mixing of jet and the mainstream, improve the gas film hole around thecooling efficiency, but in n=2000rpm, the area around of the third row-cooling holeeffect weakens, blow ratio increasing makes the surface heat transfer enhancementoverall, but the effect of speed on heat exchange is more complicated, heat transfer ofpressure surface is better when M=1.0, and suction surface’s heat transfer is betterwhen n=500rpm；The increasing of blow ratio enhances the turbulence of flow fieldnearby film hole, speed increasing leads to turbulence aggravate in the channelbetween blade sharp, and pneumatic loss bigger. Upstream wake swept blade at a certain frequency, so physical parameters offlow field and blade surface change periodically. Through the study of isothermalfigure、turbulent kinetic energy instantaneous map、Mach number and heat transfercoefficient graph figure in different time of a period, got a conclusion：During thetime from0.5T to1.0T, gas film cooling temperature is lower and covers a wide area,cooling effect at0.9T is best；The changing of turbulent kinetic energy、 the Machnumber and the heat transfer coefficient is not great in the whole periodic, turbulentkinetic energy larger value is in the first row of concentrated near the jet and leavestrailing edge place of blade, the Mach number is larger at0.7T time between thechannel rotating blade and static blade, the heat transfer coefficient near jet hole ofpressure side is higher, and the heat coefficient at the middle suction face is bigger,but reduced in the trailing edge.更多还原