叶轮顶部间隙对向心透平总体性能影响的研究

对微型燃机向心透平叶轮顶部间隙流动在级环境下进行了全三维粘性数值模拟．研究结果表明:顶部间隙小于 2％时,间隙每增加1％,级效率降低1．5％,而级通流能力有所降低;径向与轴向间隙变化对级性能影响有很大差别, 径向间隙增加对级效率降低的影响是轴向间隙增加的8．3倍,径向间隙增加使通流能力增强的程度是轴向间隙增加使通流能力减弱的4．2倍。此外,将间隙流场与文献报道试验结果进行了比较,差别主要在工作轮顶部区域。

EFFECTS OF ROTOR BLADE TIP CLEARANCE ON TOTAL AERODYNAMIC PERFORMANCE IN A RADIAL INFLOW TURBINE

Tip clearance flow in a radial inflow turbine rotor blade under stage environment was investigated by 3-dimensional viscous flow simulation. The results indicate that for tip uniform clearance less than 2 percent of the rotor blade exit height, a decrease of 1.5 percent in stage efficiency and a slight reduction of the flow rate occur for each percent increase in the rotor blade tip uniform clearance. There is a notable difference of the stage aerodynamic performance affected by radial clearance at the rotor exit and axial clearance at the rotor entrance, respectively. Radial clearance increases at the rotor exit have about 8.3 times the effect on stage efficiency decrease as axial clearance increases at the rotor entrance, while the flow rate enlarged by radial clearance increase is 4.2 times greater than that reduced by axial clearance increase. Moreover, the distinction is mainly at the top region of the rotor exducer when the tip clearance flow field was compared with experimental results documented.