单排突片激励热射流作用下楔形凹腔表面对流换热研究

Investigation of Convective Heat Transfer on a Wedge-Shaped Concave Surface Subjected to a Row of Tab-Excited Hot Jets

为了改善发动机整流支板凹腔防冰结构热气射流冲击换热效果,在常规圆形射流孔上采取了突片激励,通过三维内外流耦合数值模拟的方法研究了突片数量、突片穿透比(l/d)以及射流冲击间距(H/d)对楔形凹腔表面换热的影响。研究结果表明:突片能够提高射流核心区的速度和湍流动能,使得冲击换热效果增强;相对于圆形射流孔,4-tabs,6-tabs和8-tabs所对应的的楔形凹腔表面温度和Nu数分别提高了1.2K,2.3K,2.8K和17%,28%,33%;凹腔表面温度随着突片穿透比的增大而有所提高;射流冲击间距(H/d)对凹腔内部对流换热有很大的影响,无突片激励作用时,H/d=6的凹腔表面最高温度和Nu数比H/d=12提高了7.2K和67%;在突片激励作用下,H/d=6时的凹腔表面最高温度和Nu数分别比H/d=12时提高了8.5K和90%。突片数量和突片穿透比的增大都会引起次流总压损失的增加。

To improve impingement heat transfer used by the hot-air jets which act on the wedge-shaped concave surface of aero-engine anti-icing inlet strut,the tabbed excitation was adopted for the conventional round jet. Three-dimensional inner-flow and outer-flow conjugate heat transfer simulations were conducted to investigate the effects of tab number,tab penetration ratio（l/d） and jet impinging distance（H/d） on the heat transfer performance of the wedge-shaped concave surface. The results show that the tabs increase the core velocity and turbulent kinetic energy of the jet,and improve the convective heat transfer of jet impingement. In relative to the conventional impinging jet without tabs,the temperature of the wedge-shaped concave surface on the condition of 4-tabs,6-tabs and 8-tabs increased by 1.2K,2.3K,2.8K and the Nusselt numbers increased by17%,28%,33%,respectively. The temperature of concave surface also increased with the tab penetration ratio. The impingement distance has a significant influence on the convective heat transfer of the concave surface.The surface temperature and Nusselt numbers of H/d=6 increased 7.2K and 67%,respectively,compared with H/d=12 without the effects of tabbed excitation. On the other hand,the surface temperature and Nusselt numbers of H/d=6 increased 8.5K and 90%,respectively,compared with H/d=12 with the effects of tabbed excitation.Total pressure loss of second flow increases with the increasing of the tab numbers and tab penetration length ratio.