Heat transfer and flow structures for round jet impingement over rough surfaces have been investigated using the shear stress transport model (SST) with transition model. This model is first evaluated against the experimental data and other numerical results for the smooth surface with Reynolds number Re = 23,000 for the nozzle-plate spacing of 2. Based on the above evaluation, the effects of rough surfaces on the mean velocity, turbulence field, skin friction and heat transfer are investigated with equivalent sand grain roughness heights k_s of 50, 100, 250 and 500 μm. Two trends of the effects of roughness on the velocity field are found. First, the mean velocity over rough surfaces becomes steeper than that over the smooth surface in very near the wall. However, for k_s ≥ 250 μm, the velocity gradient in the axial direction does not increase with an increase of k_s. Second, the decay of the mean velocity is found in the deceleration region, but minimal in the acceleration zone. In addition, it is observed that the increase of roughness height leads to the reduction of the wall shear stress in the stagnation region. On the contrary, downstream, large k_s usually contributes to an augmentation of wall shear stress. For heat transfer, the enhancement of heat transfer due to roughness varies from 2.53% to 6.08% compared with the case of smooth surface. However, this enhancement is non-monotonic due to the change of the second peak of heat transfer which is believed to be the key factor.

使用带有过渡模型的剪切应力传递模型（SST），研究了粗糙表面上的圆形射流撞击的传热和流动结构。对于喷嘴板间距为2的模型，首先针对雷诺数Re = 23,000的光滑表面的实验数据和其他数值结果对该模型进行评估。基于上述评估，粗糙表面对平均速度，湍流场的影响，在等效砂粒粗糙度高度k _s为50、100、250和500μm的情况下研究了皮肤摩擦和热传递。发现了粗糙度对速度场影响的两个趋势。首先，在非常靠近墙的地方，粗糙表面上的平均速度变得比光滑表面上的平均速度陡。但是，对于k _s ≥250μm时，轴向速度梯度不会随k _s的增加而增加。其次，在减速区域发现平均速度的衰减，而在加速区域则最小。另外，观察到粗糙度高度的增加导致停滞区域中的壁切应力的减小。相反，在下游，较大的k _s通常会导致壁切应力的增加。对于热传递，与光滑表面相比，由于粗糙度引起的热传递增强在2.53％至6.08％之间变化。但是，由于传热的第二个峰的变化，这种增强是非单调的，这被认为是关键因素。