航空燃气轮机涡轮叶栅烧蚀问题的数值研究

发布时间：2018-06-05 12:05

本文选题：涡轮叶片 + 无网格方法　；参考：《中国工程物理研究院》2016年硕士论文

【摘要】：随着现代航空发动机的快速发展,为了追求高推重比和高热效率,现代先进涡轮的进口温度越来越高。在持久的高温环境下涡轮叶栅必然会出现一定范围的烧蚀现象,严重影响其寿命和可靠性,烧蚀对发动机运行工况造成的影响在实验难以开展的情况下不易评估,因此利用数值模拟工具对涡轮叶栅的烧蚀现象进行研究,探讨不同的运行工况下叶片烧蚀特点和规律,进而有效预防叶片烧蚀引起的发动机故障,对于实现我国航空发动机和燃气轮机的可靠、安全运行来说具有非常重要的意义。本文围绕如何准确预测航空发动机中涡轮等热端部件的烧蚀这一核心问题,采用无网格SPH数值模拟方法进行研究。在马智博研究员的指导下,基于物质团无网格方法的理论和面向对象的程序设计技术,对已有的无网格程序框架继续开发,添加了湍流、转捩、气固两相流以及烧蚀模块,并完善了流/固/热耦合和边界条件模块。针对航空发动机涡轮内的复杂流动、传热和烧蚀现象,基于飞行器再入烧蚀模型,引入边界层厚度将叶片表面热边界层边界条件替换远场自由来流边界条件,建立了适用于内流问题的涡轮叶片气动热力烧蚀模型。此外,在充分调研国内外最新无网格SPH方法研究成果的基础上,给出了以下3部分改进工作：(1).基于小波分析和多尺度再生核函数理论研究了初始光滑长度的最优选取准则并讨论了计算过程中光滑长度的自适应方法。(2).基于近似黎曼求解器改善了传统的Monaghan人工粘性,构造了随流场自适应的无人工参数的人工粘性,在此基础上,采用类比方法构造了NS能量方程离散形式中的耗散项。(3).基于文献中关于NS动量方程的守恒型SPH离散格式的研究成果,采用类比粘性项离散的方法统一了传质、传热方程中扩散项的数值离散格式。利用该程序对一个较为复杂的内冷高压涡轮叶片进行了烧蚀问题的数值模拟,研究结果表明：(1).叶片压力面和吸力面主要发生小尺度烧蚀,造成的材料流失很小可以忽略不计,仅改变叶片表面的粗糙度；发生在叶片前/尾缘的大尺度烧蚀造成材料的流失较多,甚至出现掉块等现象,带来涡轮叶片形状的显著变化。(2).离心力和哥氏力的作用造成了动叶表面换热和烧蚀特点与静叶存在一定的差异。随后,将研究对象由单个叶片扩展到涡轮级环境,研究了动静干涉下涡轮叶栅的烧蚀特点,研究结果表明：(1).不同动叶转速下,导叶吸、压力面之间横向压差发生了变化从而改变了导叶通道中马蹄涡压力面分支的传播规律,进而影响了导叶压力面的传热和烧蚀特点。(2).在中等转速情形下动叶前缘烧蚀较低；当转速很高时,由于相对运动牵引的流场变化比较剧烈,动叶前缘的通道涡和马蹄涡从动静之间的大变形流场中吸收能量不断壮大,强化前缘换热,烧蚀程度增加；转速很低时,导叶尾缘激波的持续作用导致动叶前缘烧蚀同样相对严重。最后,本文针对不同的主流参数研究了不同工况下涡轮叶片的烧蚀特点,并展望了后续烧蚀研究需要开展的研究内容。
[Abstract]:With the rapid development of modern aviation engine , in order to pursue high - weight ratio and high thermal efficiency , the inlet temperature of modern advanced turbine is getting higher and higher . Based on the approximate Riemann solver , the traditional Monaghan artificial viscosity is improved , and the artificial viscosity of the artificial parameters with self - adaptation of the flow field is constructed . On the basis of this , the dissipation term in the discrete form of NS energy equation is constructed by analogy method . Based on the research results of the conserved SPH discrete form of NS momentum equation in literature , the numerical simulation of diffusion term in mass transfer and heat transfer equation is unified by means of discrete method of analogy viscous term . The numerical simulation of the ablation problem of a complicated internal cooling high pressure turbine blade is carried out by using the program . The results show that : ( 1 ) The blade pressure surface and the suction surface mainly occur small - scale ablation , and the loss of material is negligible , only the roughness of the surface of the blade is changed ;
Large - scale ablation occurs at the front / trailing edge of the blade , resulting in more loss of material , even falling out of the block , resulting in a significant change in turbine blade shape . The effects of centrifugal force and Coriolis force on the surface heat transfer and ablation characteristics of the rotor blade are different from that of the stator blade . Then , the research object is extended from a single blade to the turbine stage environment . The experimental results show that : ( 1 ) the transverse pressure difference between the guide vane and the pressure surface changes under different moving blade rotating speeds , which changes the propagation law of the branch of the horseshoe vortex pressure surface in the guide vane passage , and then the heat transfer and ablation characteristics of the guide vane pressure surface are affected . in that case of moderate rotate speed , the ablation of the leading edge of the rotor blade is low ;
When the rotating speed is very high , due to the violent change of the flow field drawn by the relative motion , the channel vortex and the horseshoe vortex in the leading edge of the moving blade absorb energy continuously from the large deformation flow field between the dynamic and static , so as to strengthen the heat exchange of the leading edge and increase the ablation degree ;
In the end , the ablation characteristics of turbine blades under different working conditions are studied for different main flow parameters , and the research contents of subsequent ablation research are forecasted .
【学位授予单位】：中国工程物理研究院
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：V235.1

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