轮背空腔-密封气对CAES向心涡轮变工况流动损失的影响

本文以国内首套MW级压缩空气储能(CAES)系统末级向心涡轮为研究对象,通过数值模拟分析了变工况条件下轮背空腔-密封气对等熵效率和流场结构的影响.结果表明:在求解中考虑轮背空腔-密封气结构能够使等熵效率数值解的偏差减小0.7%;随涡轮进口压力增加,轮背空腔泄漏流由叶片吸力面中部叶高区域逐渐向轮毂转移,流动损失先增加后减小;合理降低轮背空腔泄漏气体的轴向速度,能够减弱轮背空腔-密封气结构对等熵效率的负面影响,使向心涡轮在较宽的变工况范围内都保持高效运行.

Effect of Back Cavity-Seal Gas on Flow Loss of CAES Radial Inflow Turbine Under Variable Operation Conditions

In present study,the last stage of a multistage radial inflow turbine in a MW-scale compressed air energy storage(CAES) system is selected as a research object.The influence of back cavity-seal gas on the isentropic efficiency and flow structure of the radial inflow turbine under variable operating conditions is investigated.The results illustrate that the deviation of isentropic efficiency can be decreased by 0.7% if the back cavity and seal gas are included in the model.With the increase of inlet total pressure,the back cavity leakage flow gradually migrated from the region near middle height of blade at suction surface to the hub of rotor.The flow loss is thus increased firstly and then decreased.With the increase of inlet total temperature,the influence degree of back cavity and seal gas on isentropic efficiency of radial inflow turbine is decreased gradually.Lower axial velocity of the back cavity leakage flow can weaken the negative influence of the back cavity and seal gas and increases the isentropic efficiency of radial inflow turbine under variable operating conditions.