涡轮机械转子在CO2工质中风摩损耗的数值分析

Numerical analysis of windage loss of turbomachinery rotor in CO2

在超临界CO2布雷顿循环系统设计中,为提高系统能量转换效率,需要准确预测风摩损耗.风摩损耗与转子转速、转子几何结构、工质状态密切相关.该文针对2 MPa CO2工质中,高转速(23 kr/min)转子的风摩损耗特性进行数值计算分析.研究结果表明:转子-定子壁面粗糙度对超临界CO2布雷顿循环系统中高转速以及可能出现的较高压强工况下的风摩损耗具有显著影响.已有风摩损耗经验关系式未考虑壁面粗糙度的影响,直接使用可能带来较大误差.风摩损耗随壁面粗糙度和转子转速的增加而增加,气腔宽度的变化对风摩损耗不会造成明显影响.

In order to improve the energy conversion efficiency of the supercritical CO2 Brayton cycle system,it is necessary to accurately predict the windage loss during the system design.Windage loss is closely related to rotor rotation speed,rotor geometry and the state of the working fluid.In this paper,the numerical calculation analysis of high-speed(23 kr/min)rotor windage loss characteristics in 2 MPa CO2 working fluid is carried out.The results show that rotor-stator wall roughness has a significant effect on the windage loss of the supercritical CO2 Brayton cycle under high rotation speed and high pressure conditions.The existing empirical relation of windage loss does not consider the influence of wall roughness,the direct use of which may cause considerable errors.The windage loss increases with both the wall roughness and rotor rotation speed.The cavity width between the rotor and stator does not have obvious influence on the windage loss.