前后可调变弯度导叶在高负荷风扇中的应用

针对某高负荷双级风扇非设计转速裕度不足的问题，通过NUMECA三维(CFD)数值模拟软件，对比分析了可变弯度导叶(VIGV)前后可偏转调节对导叶气动性能的影响，以及导叶大角度范围内变弯度调节对提高风扇中低转速性能的作用。结果表明:可变弯度导叶偏转调节后的叶型实际弯角是影响导叶气动损失的重要因素之一；通过导叶前段适当变角度调节能减小导叶的实际弯角，推迟了导叶吸力面气流分离的出现，拓宽了变弯度导叶低损失可调角度范围；同时导叶适当的前后偏转调节能够降低导叶对缝隙位置的敏感性；此外前后可调变弯度导叶能够使高负荷风扇非设计工况实现更高的绝热效率，在90%转速、80%转速、70%转速和60%转速下的风扇绝热效率分别提高了2.04%、5.48%、6.18%和6.82%；且由于风扇喘振边界进一步远离风扇阀门线，使得风扇中低转速的稳定工作范围显著拓展。 

Application of variable inlet guide vane with adjustable front and back vane parts in highly loaded fan

A highly loaded fan with the insufficiency of the stall margin in the states of off-design speed was studied. After numerical simulation of three dimensional flow using commercially available CFD code NUMECA, the change of aerodynamic performance of a variable inlet guide vane (VIGV), and the improvement method of low-speed performance of the fan were investigated, when the VIGVs front and back vane parts can be rotated in large range of angle. Results of numerical simulation indicated that the camber angel of the VIGV was one of the most important influential factors to the performance of the VIGV. The front vane part of the VIGV was rotated at some angle, the actual camber angle of the vane was reduced, helping to delay flow separation on the vanes suction surface, and broaden the VIGVs adjustable angle with a low-loss level. Besides, the VIGV was not sensitive to the position of a slot between the two vane parts, if both of the vane parts were rotated with proper angles. The VIGV improved the adiabatic efficiency of the highly loaded fan under the off-designed conditions, the adiabatic efficiencies were improved by 2.04%, 5.48%, 6.18% and 6.82% at 90% speed, 80% speed, 70% speed and 60% speed. Because the throat line of the fan was further away from the throttle line, the fans surge margin was expanded obviously at off-speed.