热气防冰系统内表面弦向传热性能衰减规律

利用反向热流法实验研究了弦向3排射流喷口,且中央喷口正对前缘驻点结构下射流冲击热气防冰系统前缘内表面的局部传热特性。重点研究了喷孔射流出口雷诺数Re_j、笛形管相对于前缘的距离与孔径比Z_n/d、射流冲击驻点区弦向弧长与孔径比r/d对冲击前缘靶面的局部传热性能分布的影响。实验中Re_j范围为2.5×104~1×105,Z_n/d范围为1.736~27.5,r/d范围为13.21~61.5。结果表明,局部传热性能分布曲线为从驻点开始向两侧衰减的钟形曲线,包括稳定段、下降段和结束段3部分,其中稳定段只受参数r/d的影响,而参数Re_j、Z_n/d和r/d均能够明显影响下降段的下降速率,参数r/d则几乎不会改变下降段的总下降幅度。总结了此类喷口结构下射流冲击前缘换热性能衰减分布曲线的通用实验关联式,以指导防冰系统的设计和热性能的评估。 

Chordwise attenuation of heat transfer performance on inner surface of hot-air anti-icing system

The local heat transfer performance on the inner surface of the airfoil leading in jet impingement hot-air anti-icing system is experimentally studied through inverse flux technique using a piccolo which has 3 rows of orifices chordwisely, among which the middle orifice is exactly facing the stagnation point. The jet Reynolds number, Re_j, the relative piccolo tube to surface distance, Z_n/d, and the relative chordwise arc length in the jet impingement zone, r/d, are studied as the factors of local jet impingement heat transfer performance. The range of Re_j, Z_n/d and r/d are 2.5×10⁴-1×10⁵, 1.736-27.5, 13.21-61.5, respectively. The local heat transfer performance curve looks like a bell, meaning it is high around the stagnation point and decreases as the position goes aside. This curve consists of 3 parts: the stable zone, the decline zone and the ending zone.Stable zone is only dependent on r/d. All of Re_j, Z_n/d and r/d significantly affect the declining rate of decline zone. However, the amount of decrease is nearly independent of r/d. The experimental correlation equation of the heat transfer performance attenuation under the circumstances of applying this kind of piccolo structure is developed, which would be helpful for future design of anti-icing system and evaluation of its thermal performance.