叶片表面粗糙度对高负荷低压涡轮的流动影响

Effects of Surface Roughness on the Flow of High-Lift Low-Pressure Turbine

为了得到不同工况下表面粗糙度对涡轮叶片叶型损失的影响规律,采用数值模拟的方法对某前加载叶型在不同攻角和不同雷诺数下的流动进行了详细的分析。结果表明,当攻角i=0°、10°时,叶片表面并无明显的分离现象出现,当i=20°、25°、30°时,叶片表面都出现了不同程度的分离,且攻角越大分离越严重。当攻角一定时,增大雷诺数对抑制分离泡的出现有促进作用;当雷诺数也一定时,增大叶片表面粗糙度对抑制附面层的分离有明显的效果,且雷诺数越大抑制分离所需的粗糙度值就越低。攻角为20°,雷诺数分别等于25000、50000、100000、150000、200000时,抑制分离所需的最佳粗糙度值依次为38、14、5.1、2.5、1.7mm;攻角为25°,相同雷诺数下抑制分离所需的最佳粗糙度值依次为230、50、11、4、2.2mm;攻角为30°,雷诺数分别等于50000、100000、150000、200000时,抑制分离所需的最佳粗糙度值依次为3200、800、120、29mm。最后,建立了一套不同攻角下抑制分离的最佳粗糙度-雷诺数关系模型,并编写了相应的C语言程序。通过该程序,只要得知叶片工作的攻角与雷诺数大小,便可直接算出抑制附面层分离的最佳粗糙度值。

In order to get the effects of surface roughness on turbine profile loss in different working conditions, the flow of a front-loaded blade at different incidences and different Reynolds number was analyzed in detail by numerical simulation. The results show that when the incidence i =0° and 10°, there are no obvious separation on the blade surface. When i =20°, 25° and 30°, the boundary layer on blade surface are separated and the incidence is more serious. When the incidence is certain, the increasing of Reynolds number on the suppression of separation bubble appears to have a role in promoting;when the Reynolds number also is certain, increase the blade surface roughness of suppression of boundary layer separation have obvious effect, and Reynolds number greater suppression required to separate the roughness value is lower. When i =20° and the Reynolds number is 25 000, 50 000, 100 000, 150 000, 200 000, the optimal roughness value of suppressing separation is 38 mm,14 mm,5.1 mm,2.5 mm,1.7 mm, When i =25°, the optimal roughness value of suppressing separation is 230 mm,50 mm,11 mm, 4 mm,2.2 mm to the same Reynolds number, When i =30° and the Reynolds number is 50 000, 100 000, 150 000, 200 000, the optimal roughness value of suppressing separation is 3 200 mm,800 mm,120 mm,29 mm. Finally, a modal of optimal roughness vs. Reynolds number was built for suppressing separation in different incidences, and a C language program was written by the model. By using the program, the optimal roughness value of suppressing boundary layer separation can be calculated directly from the certain incidence and Reynolds number.