【作者】 贺晓亮；

【导师】 冯永明；

【作者基本信息】 哈尔滨工程大学 ， 动力机械及工程， 2010， 硕士

【摘要】 压气机的失速与喘振是两种既有密切联系又互相区别的非稳定流动现象。喘振会导致压气机叶片发生剧烈的震荡,严重时会损害压气机本身,而旋转失速是喘振发生前的先兆,深入分析旋转失速是控制压气机喘振的重要前提和基础。本文采用三维数值模拟的方法,利用CFD技术仿真某离心式压气机。利用NASA文献提供的压气机和扩压器叶片数据建立计算模型,并用解析几何的方法处理压气机叶片前缘的圆弧,建立压气机和扩压器的几何模型,并建立高、中、低三种不同网格密度的计算域模型,分别在80%和100%工况下对三种网格密度的计算模型,进行稳态数值计算。通过对比三种网格密度在高低工况下的流场分布特性、压力分布特性、压气机整机性能和数值仿真结果误差,发现三种网格密度模型的计算结果相差不大,压气机特性也相同,由此证明低密度网格能够满足压气机特性仿真计算的要求。利用低密度网格建立压气机和扩压器的全周计算模型,进行压气机近喘振点三维非定常计算。本文主要研究压气机在近喘振点附近的旋转失速现象。通过计算发现,压气机在发生旋转失速前,扩压器流道内部已经出现了流场分布不对称的现象,而且这些不均匀的流场分布在计算的不同时刻,也发生变化。在失速发生之前扩压器叶片的压力面和吸力面都出现气体分离,发生气体分离的位置从叶根处随时间变化向叶顶方向发展。通过计算,压气机在高工况下运行时,旋转失速发生的速度较快,失速频率为26.5Hz,并且失速发生对应压气机特性图上的范围非常窄,失速发生后紧接着压气机进入喘振状态,在计算到第13圈时,压气机进入深度喘振,这与实际压气机特性符合。本文的研究为进一步采取主动流动控制技术,如扩压器机匣或轮毂射流主动控制离心压气机喘振,奠定了基础。更多还原

【Abstract】 Compressor stall and surge which tie up and discriminative with each other are two difference non-steady flow phenomena. Compressor surge can lead dramatic fluctuations in impeller, even destroy the compressor. Rotating stall is a precursor to the pre-surge, depth analysis of the rotating stall is an important prerequisite and foundation to control compressor surge.In this paper, adopt three-dimensional numerical simulation method, using CFD technology to simulation some centrifugal compressor. One literature of NASA provided the compressor and diffuser blade computing model data set and use analytic geometry approach to process the arc of compressor blade leading edge. Then establish the compressor and the diffuser geometry model, and build three different mesh density of high, medium and low of the computational domain model, respectively, calculate 80% and 100% working condition of the three kinds of mesh density model for steady-state numerical calculation. By comparing three kinds of mesh density in the high and low operating conditions of the flow field characteristics, the pressure distribution properties, compressor performance, and numerical simulation results of machine errors, found that three kinds of mesh density model results more or less, compressor characteristics also the same, thus proving that low-density grid to fulfill the requirements of the compressor characteristic simulation.Use low-density grid to establish the compressor and diffuser calculation model for the entire machine to carry out three-dimensional unsteady calculations nearly the compressor surge point. This paper mainly studies the compressor stall phenomenon near the surge point. From calculation found that the event of compressor rotating stall has emerged asymmetry at the diffuser flow channel before it happens, and this non-uniform flow field distribution in the calculation of different moments also change. Before the stall occurs in the diffuser blade pressure surface and suction surface have emerged out of gas separation, and the location of gas separation change over time expand from the root to the tip of the blade.By calculating, when the compressor is running at high operating conditions, the rotating stall occurs faster, the stall frequency is 26.5Hz, and the range of compressor stall occurs in the compressor characteristics map corresponds to a very narrow range, the compressor surge immediately occurs after the rotate stall, in the calculation of 13th round, the compressor get into the deep surge, this coincide with the actual characteristics of the compressor. This study laid the theoretical foundation and pre requisite for further using active flow control technologies, such as diffuser hub or shroud jet active control the centrifugal compressor surge.更多还原