入口压强对离心式压缩机性能影响的数值研究  

Numerical study on the effect of the inlet pressure on centrifugal compressor performance

作　　者：黄东洋 周文必 姜东君[1] 潘建雄 HUANG Dongyang;ZHOU Wenbi;JIANG Dongjun;PAN Jianxiong(Department of Engineering Physics,Tsinghua University,Beijing 100084,China)

机构地区：[1]清华大学工程物理系,北京100084

出　　处：《清华大学学报（自然科学版）》2024年第9期1666-1676,共11页Journal of Tsinghua University(Science and Technology)

摘　　要：为探究入口压强小于1个标准大气压时对离心压缩机性能及流动结构的影响,该文以Krain离心式叶轮为研究对象,采用Spalart-Allmaras(S-A)方程湍流模型的有限体积法求解Reynolds时均Navier-Stokes(Reynolds time-averaged Navier-Stokes, RANS)方程组,得到入口体积流量恒定时入口压强400~101 325 Pa条件下离心叶轮的性能及内部流场结构。结果表明:随着入口压强减小,Krain叶轮总压比和总等熵效率先缓慢减小再急剧减小;相比于在101 325 Pa压强下,当压强为400 Pa时,Krain叶轮总压比和总等熵效率减小幅度超过10%。入口压强减小使叶轮及无叶扩压器内气体比熵增增加,其中由叶轮出口处反流、无叶扩压器轮盘侧边界层导致的比熵增显著增加。入口压强在1 333~101 325 Pa变化时,叶轮及扩压器内流场特征差异性较小,但轮盘侧边界层厚度随压强减小而增加,当入口压强减小至400 Pa时,叶轮出口处反流速度增大、区域扩大,扩压器内轮盘侧边界层厚度显著增加,使流动损失增加。故在负压压缩机初始设计阶段中采用基于正压的一维模型预测性能时,应考虑对性能进行负修正,且修正程度随入口压强减小而增加。[Objective]A centrifugal compressor is a key equipment in the gas diffusion isotope separation cascade at pressures below 5 ooo Pa,and its performance affects the economics of the separation cascade.Currently,only a few studies have focused on the performance and internal flow characteristics of centrifugal compressors under negative pressure conditions(inlet pressure≤101325 Pa),especially when the inlet pressure is as low as 400 Pa.Additionally,in our experiments with the designed centrifugal compressor,an increase in inlet pressure improved the pressure ratio for the same inlet volume flow rate.Therefore,investigating the impact of the inlet pressure on the performance of centrifugal compressors is necessary.[Methods] Taking the Krain centrifugal impeller as the research object,the finite volume method is used to solve the three-dimensional Reynolds time-averaged Navier-Stokes(RANS)equations,and the ideal gas state and Spalart-Allmaras turbulence model equations are substituted into the RANS equations.A single flow channel calculation model,including the inducer,impeller,and vaneless diffuser,is meshed by 1.88 million hexahedral structural grids.The thickness of the first layer of the grid near the walls is 6μm,and the y*value in most calculation domains is set to be less 1o,satisfying the grid independence verification.The boundary conditions are as follows:total pressure,total temperature,and velocity along the axis direction are given at the inlet,while the mass flow rate is provided at the outlet;all walls are no-slip adiabatic boundaries.The relative deviation between the calculated values of the verification case and experimental values is approximately 3%,indicating the accuracy and reliability of the calculation method.[Results]The numerical results were summarized as follows.(1)As the inlet pressure decreased,the total pressure ratio and total isentropic efficiency of the compressor first decreased slowly and then decreased rapidly.When the pressure was 4oo Pa,performance was reduced by 10%compared

关 键 词：离心压缩机性能 入口压强 比熵增 速度 

分 类 号：TH452[机械工程—机械制造及自动化]