低温地热源有机朗肯循环系统匹配向心透平数值分析及优化

Numerical Analysis and Optimization of Radial Inflow Turbine for Organic Rankine Cycle System of Low-temperature Geothermal Power

为了更好的利用低品位热能,研发了与低温地热源有机朗肯循环匹配的向心透平的两种叶轮结构形式:90°进气和后掠式进气,并对其进行了数值模拟。结果表明,在相同进口压力温度条件、相同出口压力条件及相同流量条件下,相对于90°进气向心透平,后掠式进气向心透平具有更高的效率。为了进一步提高两台向心透平的效率,通过均匀试验的手段对两台向心透平的叶轮进行了优化并采用单向流固耦合方法对优化叶轮叶片进行了强度的校核。结果表明,90°进气向心透平和后掠式向心透平最后获得最大等熵效率分别是86.9%和87.9%,较原型分别提高1.9%和1.4%。优化后叶轮内流动得到改善,叶轮做功能力增强。强度校核结果表明优化后的叶轮叶片最大变形量均小于设计叶顶间隙,最大等效应力远小于材料屈服强度,叶轮满足安全运行要求。

For better use of low-grade heat,the structure of two kinds of impeller,90°IFR and IFG,of the radial inflow turbine suitable for organic Rankine cycle system(ORC)of low-temperature geothermal power was self-designed and developed.And the numerical simulation is carried out.The results show that under diverse working conditions for the same inlet pressure and temperature,the same outlet pressure and the same flow rate,comparing with the turbine with 90°IFR,the turbine with IFG has higher efficiency.In order to further improve the efficiency of two radial inflow turbines,the impeller of two radial inflow turbines has been optimized by using the uniform test.And the one-way fluid solid coupling method is used to check the strength of the optimized impeller blade.The results show that the maximum isentropic efficiency is 86.9%and 87.9%,increased by 1.9%and 1.4%respectively.After optimization,the flow in the impeller is improved and the performance of impeller is enhanced.The strength check results show that the strength of the impeller blades of the maximum deformation of the optimized design was less than the tip clearance,and the maximum equivalent stress is far less than the yield strength of the material.The impeller meets the requirements of safe operation.