大涵道比风扇/增压级叶尖间隙影响研究

以某大涵道比风扇/增压级为例,分析风扇转子叶尖间隙对风扇/增压级性能的影响。通过风扇外涵计算及试验结果对比,表明在各转速流量、压比下吻合良好,其中高转速试验效率略高于计算结果,失速裕度基本相当;当转速降低时试验效率偏高更为明显,失速裕度略高于计算结果。分别分析1.0转速、0.85转速以及0.6转速风扇叶尖间隙对风扇/增压级性能的影响,结果表明当转速较高时,随着间隙的增加,激波-边界层干涉与间隙泄漏流掺混导致了大间隙状态二次流损失增加,外涵设计点压比、流量、效率均有所降低,当间隙增加到一定程度时,失速裕度迅速降低;对低转速状态的分析结果表明,随着间隙的增加,设计点效率下降幅度相比高转速状态有所降低,失速裕度随着间隙的增加而增大,风扇外涵特性对间隙的敏感性降低。在各转速下风扇转子叶尖间隙的大小对内涵性能影响不大。

Influence of tip clearance on high-bypass-ratio fan/booster

An analytical study of tip clearance flows in the high-bypass-ratio fan/booster is presented.The results reveal that for all kinds of corrected rotating speed,the flow and the total pressure ratio predicted by CFD is very close to the experiment result;for the high corrected rotating speed,the efficiency is lower in CFD and stall margin is almost equal to the experiment results;for the decreased corrected rotating speed,the efficiency of the experiment is obviously higher,and stall margin of the experiment is lower.Evaluations are conducted under 1.0,0.85 and 0.6 corrected rotating speed conditions for multiple fan tip clearance levels to obtain clearance sensitivities.When the tip clearance increases,the shock wave-boundary interaction and tip leakage flow mixing lead to secondary flow loss at high corrected rotating speed,and the performance decreases at the design point.Stall margin will rapidly fall when the tip clearance rises to a certain level.Similar results are obtained at low corrected rotating speed while the decline of efficiency is slower and stall margin rises as tip clearance increases,revealing the reduction of tip sensitivity as the corrected rotating speed reduces.There is little influence of tip clearance on the core flow at all kinds of corrected rotating speed.