Abstract

An impinging jet heat transfer in cross-flow within and without influence of a vortex generator pair (VGP) is studied using the unsteady Reynolds averaged Navier-Stokes (URANS) and the large-eddy simulation (LES). The jet Reynolds number is 15,000 and the cross-flow Reynolds number is 30,000. The elliptic-blending Reynolds stress model (EBRSM) is implemented and adapted to capture the effect of the jet close to the wall. A v² − f model is also implemented to study the ability in predicting such a benchmark. Both models benefit from the elliptic relaxation equation in the entire computational domain. The URANS results are compared with the accurate results of the LES method and also the experimental data. The URANS method successfully presents the flow features of the impinging jet while underpredicts the enhancing heat transfer over the channel bottom wall. The URANS method fails to correctly predict the flow structures forming around the impinging region, because the method is more diffusive than the LES method. When manipulating VGP, a rectangular winglet vortex generator pair is placed in the cross-flow channel and upstream of the jet nozzle to enhance the impinging heat transfer. The VGP increases the Nusselt number at the impingement region. The structures generated by the VGP alter the effects of the cross-flow on the impinging heat transfer. There are Kelvin-Helmholtz instabilities at the shear layer of the jet and the cross-flow in the base flow (the flow without VGP). These instabilities are altered in the flow with VGP. A swirl component is added in the jet to study the effects on the heat transfer. The result shows that for a high or moderate level of swirl, the jet is diffused before the impinging.

中文翻译：

---

涡流发生器结构内和不影响传热的横流冲击射流的数值研究

摘要

使用非稳态雷诺平均纳维-斯托克斯（URANS）和大涡模拟（LES）研究了涡流发生器对（VGP）内部和不受涡流发生器对（VGP）影响的射流传热。喷射雷诺数为15,000，横流雷诺数为30,000。椭圆混合雷诺应力模型（EBRSM）已实现并适用于捕获靠近壁面的射流的影响。甲v ² - ˚F还实施了模型以研究预测此类基准的能力。两种模型都受益于整个计算域中的椭圆松弛方程。将URANS结果与LES方法的准确结果以及实验数据进行比较。URANS方法成功地展示了撞击射流的流动特征，同时低估了通道底壁上传热的增强。URANS方法无法正确预测撞击区域周围形成的流动结构，因为该方法比LES方法具有更大的扩散性。操纵VGP时，将矩形小翼涡流发生器对放置在横流通道中并位于喷嘴的上游，以增强碰撞传热。VGP增加了撞击区域的Nusselt数。VGP产生的结构改变了横流对撞击传热的影响。在射流的剪切层和基流中的错流（无VGP的流）中存在Kelvin-Helmholtz不稳定性。这些不稳定性在使用VGP的流程中已更改。在射流中增加了涡流成分，以研究对传热的影响。结果表明，对于高水平或中等水平的旋涡，射流会在撞击之前扩散。