【作者】 李文；

【导师】 谭春青；

【作者基本信息】 中国科学院研究生院（工程热物理研究所） ， 动力机械及工程， 2011， 博士

【摘要】 低压涡轮是航空发动机的重要部件,其效率变化对发动机推(功)重比、耗油率有显著的影响,因此,为提高航空发动机性能、推动先进技术的研发,有必要对低压涡轮内部流动及换热特性进行全面细致的研究。本文利用CFD技术对低压涡轮内部气动流动结构、高空低雷诺数(Re数)下内部流动及冷却特性、轮盘盘腔内部换热规律和流动损失机理进行了深入研究,并为下一步的低压涡轮流动及冷却特性实验研究工作开展了相关的实验装置研制及改造工作,主要研究内容如下：1.详细研究了某航空发动机涡轮不同工况气动特性。在总结其流动特性和流场结构的基础上进行了优化改型,效率提高0.8%,流量增加2.7%,低压涡轮输出功增加10.4%,证明所采用优化改型方法对发动机性能提升作用显著。2.采用气热耦合计算方法,对某航空发动机低压涡轮高空低Re数下的流动及冷却特性进行了深入研究,仔细分析了Re数对低压涡轮效率、流动和换热特性的影响。随着Re数(<2×105)的增加,附面层分离损失不断降低使得低压涡轮效率单调增加；而Re数的降低导致换热系数降低,对比发现在地面高Re数工况下低压涡轮叶片冷却效果最好。3.对低压涡轮动叶叶顶冷却射流的研究表明射流能够减小泄漏量、增加泄漏涡强度、促进射流与主流掺混,从而明显提高了涡轮效率,且存在一个最优射流强度πj使得低压涡轮性能达到最优。4.在前人实验工作的基础上,对发动机涡轮盘腔内部的流动和换热特性进行深入分析研究,发现在不同的湍流参数λT、预旋比βP和旋转雷诺数Re,工况下,惯性力和离心力占不同的主导地位,从而导致流场结构呈现出规律性变化；Nu数随Re。的增加而增加,低射流强度时Nu数沿径向是递增的,而高射流强度时Nu数沿径向是递减的。5.详细介绍为开展低压涡轮内部流动及冷却特性实验研究而对IET短周期涡轮实验台进行的适应性研制改造工作,测试结果表明各实验装置均能满足实验研究工况要求,可以开展相关实验工作。更多还原

【Abstract】 Low Pressure Turbine (LPT) is an important component of aeroengine. The performance of LPT greatly influences the thrust-weight ratio and specific fuel consumption of aeroengine. It is of imperative to investigate the flow and heat transfer characteristics in LPT for improving the aeroengine performance and advanced technology research.The performance of LPT, including the aerodynamic flow features, the flow and cooling characteristics under the condition of altitude low Reynolds number(ALRN), and the flow and heat transfer in rotor-stator cavity are investigated by advanced computional fluid dynamics(CFD) in the thesis. The redesign and improvement work of the short duration turbine rig has also been carried out for further experimental investigation. The main contents of the thesis are listed as follows:1. The aerodynamic characteristics of an aeroengine turbine under various working conditions are investigated in detail. The component optimization is, moreover, carried out on the basis of the flow features and flowfield structures of the turbine. The efficiency of the optimized turbine is0.8%higher than the original one. Furthermore, the mass flow is improved by2.7%and the power of the LPT is increased by10.4%. It is concluded that the optimization work can increase the performance of the turbine remarkably.2. Flow and cooling characteristics of an aeroengine LPT under ALRN are investigated by conjugate heat transfer methodology, meanwhile the effects of Reynolds number on the LPT efficiency and characteristics of flow and cooling are discussed in detail. With the increasing of Reynolds number (<2x105), the efficiency of the LPT is increasing monotonically because of the decrease of boundary layer separation loss. The heat transfer coefficient is decreasing with the decreasing of Reynolds number.3. The research of tip injection of the LPT rotor indicates that the tip injection improves the efficiency apparently, and the turbine efficiency can be best with optimal jet intensity πj. The tip leakage mass flow is decreased and the tip leakage vortex is enhanced by the tip injection, meanwhile the tip injection accelerates the injection flow and main flow to mix together.4. Based on the previous experimental results in literatures, the flow and heat transfer characteristics in a pre-swirl rotor-stator cavity are further investigated. The result indicates that the flow features and flowfield structures are mainly influenced by centrifugal force and apparent force with different turbulent flow parameter λr, pre-swirl ratio βρ, and rotational Reynolds number Re. The nusselt number on the rotor surface increases with Re? increasing. Furthermore, the Nusselt number is progressively increasing along with the radial direction when the jet intensity of the rotor-stator cavity is low, however the nusselt number is degressive along with the radial direction when the jet intensity is high.5. The development and improvement of IET short duration experiment rig for further experiment study of flow and cooling characteristics is presented. The test results indicate that experiment facilities are well prepared for further experimental study.更多还原