Experimental Investigation of Gas Turbine Aerodynamics using Planar Laser-Induced Fluorescence (PLIF).

为了研究燃气轮机内的空气动力学，特别是吹扫流动对主流流动空气动力学的影响，将进行一个实验性的PHD计划。由于在涡轮机中发现的高温，任何流入盘腔的热空气，即涡轮机的静止部件和旋转部件之间的空间，都会对涡轮机造成严重损害，还会导致效率损失，这种流动被称为入口。为了抵消这种冷却空气/吹扫气流通过阀瓣空腔冷却入口气流，这被称为出口气流。当出口气流进入主流流动时，会造成气动损失，从而降低涡轮效率。在现代燃气轮机中，改变静、动叶间静压力场的端壁轮廓(EWC)设计技术近年来得到了多位研究者的研究，其中马丁·G·罗斯博士最多。如果正确使用EWC，理论上可以通过减少在转子叶片周围形成的涡流和横流来更有效地重新引入出口流。此外，EWC还可以通过减小定子和转子之间的静压差来减少出口流量，从而降低吹扫气流的压力，从而降低流量。这将通过使用巴斯大学新建造的大型环形钻机(LAR)和使用平面激光诱导荧光(PLIF)技术来检测流动轨迹来进行研究。这将是对PIV(三分量体积测速仪)测量速度场的补充，以清楚地了解吹扫流动对主流流动空气动力学的影响。该项目将调查不同的EWC剖面，以确定它们在减少出口气流、减少吹扫气流与主流混合造成的气动损失以及二次流动损失方面的有效性。该项目的总体目标是通过轮缘密封出口几何形状和EWC的组合设计来提高燃气轮机的气动效率。该项目还与西门子合作，将借鉴他们的丰富经验。

An experimental PhD programme will be conducted with the aim of investigating the aerodynamics in a gas turbine, specifically the effect of purge flow on the mainstream flow aerodynamics. Due to the high temperatures found in turbines any hot air that flows into the disc cavity, the space between the stationary components and rotating components of the turbine, can cause serious damage to the turbine and also results in a loss of efficiency, this flow is called ingress. To counteract this cooling air/purge flow is introduced through the disc cavity to cool the ingress flow, this is called egress flow. Egress flow causes aerodynamic losses when introduced into the mainstream flow resulting in a reduced turbine efficiency. The design technique in modern gas turbines of end wall contouring (EWC) which alters the static pressure field between the stator vanes and rotor blades has been investigated by several researchers in recent years mainly by Dr Martin G Rose. EWC if done correctly could theoretically be used to reintroduce egress flow more efficiently by reducing the vortices and crossflow formed around the rotor blades. Also EWC could reduce the amount of egress flow by reducing the static pressure difference across the stator and rotor, resulting in a lower pressure of the purge flow and as a result a lower flowrate. This will be researched by using the newly constructed large annulus rig (LAR) at the University of Bath and using planar laser-induced fluorescence (PLIF) techniques to examine the flow trajectory. This will complement the PIV (three component Volumetric Velocimetry) measurements which examine the velocity field, to give a clear picture of the effect of the purge flow on the mainstream flow aerodynamics. The project will investigate different EWC profiles to determine their effectiveness at reducing egress flow, reducing the aerodynamic losses from the mixing of the purge flow with the mainstream flow and the secondary flow losses. The overall aim of the project is to improve the aerodynamic efficiency in a gas turbine by a combined design of rim seal exit geometry and EWC. The project is also in association with Siemens and will draw on their extensive experience.