某三级低压风扇不同工况叶尖间隙的变化规律及气动影响

通过模型分析结合数值模拟,对某三级低压风扇不同工况叶尖间隙变化规律及其对风扇气动性能的影响展开研究.根据叶尖间隙预估模型计算发现,三级低压风扇叶尖间隙变化具有主要与转速相关,同一转速下从堵塞点到近失速点叶尖间隙的变化并不大的特点.针对这一特征,提出了评估叶尖间隙变化对稳定裕度影响的方案.通过对使用冷态装配间隙和模型预估运行间隙分别进行全工况特性线数值仿真,结果发现:转速越大,叶尖间隙变化导致的影响也增大.在该三级低压风扇100%设计转速,叶尖间隙变化会带来0.5%进口流量、0.5%最大绝热效率以及5%稳定裕度的差异. 

Tip clearance variation and its influence on a 3-stage low pressure fan performance in different operating conditions

Tip clearance variation and its influence on a 3-stage low pressure fan performance in different operating conditions were studied using model and numerical simulation method. According to prediction results of tip clearance prediction model, the tip clearance variation of the 3-stage low pressure fan was mainly associated with the rotating speed, and the tip clearance variation from choke condition to near stall condition was small at the same rotating speed. Based on these characteristics, an evaluation method about the influence on the stability margin with tip clearance variation was found. The performance of a 3-stage low pressure fan was simulated in different operating conditions to allow a comparison by using the predicted tip clearance or not. The results show that the influence with tip clearance variation increases along with the growing rotating speed, and the tip clearance variations has a 0.5% impact on the calculated mass flow rate at inlet, 0.5% impact on the calculated maximum efficiency and 5% impact on the calculated stability margin at the 100% design rotating speed.