基于表面粗糙度的超高负荷低压涡轮叶片附面层控制

实验研究了表面粗糙度对PACKD-A低压涡轮叶型损失及附面层特性的影响.实验分别在定常来流与非定常条件下进行,非定常条件下的上游尾迹通过运动的圆棒来模拟.粗糙叶片通过在光洁叶片表面切槽,埋入砂纸制作成型.叶型损失与吸力面载荷使用气动探针与壁面静压孔结合压差传感器来测量,附面层流场使用热线探针来测量.结果表明:覆盖5.2%吸力面弦长(起始于44.3%吸力面弦长,终止于49.5%吸力面弦长),粗糙高度为8.82μm的控制方案在非定常条件下效果最佳,该方案可在整个考察雷诺数范围内(3×104~12×104)降低叶型损失;覆盖19.5%吸力面弦长(起始于30%吸力面弦长,终止于49.5%吸力面弦长),粗糙高度为20.91μm的控制方案在定常条件下效果最佳,该方案可在低雷诺数范围内(小于8×104)降低叶型损失、扩大叶型正常工作雷诺数范围,但在高雷诺数下(大于8×104),却带来了一定的额外损失. 

Boundary layer control of ultra-high-lift low pressure turbine blade with surface roughness

The effects of surface roughness on the aerodynamic performance and boundary layer condition of low pressure turbine blade PACKD-A were investigated experimentally under steady state and unsteady state. The upstream wakes were simulated by the rotating bars, thus, an unsteady environment state was formed. To produce the roughness blades, the sandpaper was stuck into the slot, which was incised on the smooth blade. The profile loss and the loading of the suction side were measured by aerodynamic probes and static pressure holes associated with the pressure transducer. And the details of the boundary layer were measured with a single hotwire probe. Result shows that the roughness strips covering 5.2% suction surface length (starting at 44.3% suction surface length, stopping at 49.5% suction surface length) and with 8.82μm roughness height have a better performance than others in the unsteady state. The profile loss is reduced with this roughness strip with the whole tested Reynolds number(3×104~12×104). In addition, the roughness strips covering 19.5% suction surface length (starting at 30% suction surface length, stopping at 49.5% suction surface length) and with 20.91μm roughness height reduce the profile loss and extended the operating margin of the turbine blade with low Reynolds number(less than 8×104) under steady state. However, some additional profile loss is produced with this type of roughness with high Reynolds number(more than 8×104).