出口雷诺数对平面射流自保持性的影响

通过实验研究出口雷诺数对平面湍流射流自保持性的影响. 测量的射流来自相同的喷嘴但不同的雷诺数Re（≡U_jh/ν，其中U_j是出口平均速度、h是窄缝出口的厚度和ν是黏性系数），其变化范围是Re=4582—57735.所得的数据包括沿轴线的平均速度、湍流强度、积分尺度、高阶矩和能谱. 实验发现，随着Re的增大，平面射流发展减慢，平均速度和湍流强关键词：平面射流雷诺数自保持性

Effect of exit Reynolds number on self-preservation of a plane jet

We investigated in experiment the effect of exit Reynolds number on self-preservation of a turbulent plane jet. Centerline velocity statistics were measured in plane jets issuing from the same nozzle but, respectively, with seven Reynolds numbers varying between Re = 4,582 and Re = 57,735, where Re ≡U_j h/v,(U_j being the momentum-averaged exit mean velocity, h the slot height and v the kinematic viscosity). All measurements were conducted using single hot-wire anemometry and over an axial distance (x) of 40 h. These measurements revealed a significant Re-dependence of either the mean or turbulent flow field. As Re increases, the pace of the jet development decreases and, as a result, both the mean and turbulent properties reach their self-preserving states over a longer downstream distance (x). The centerline integral scale L for all jets grows linearly with x and the growth rate decreases as Re is increased. It is also found that the local Reynolds number Re_L scales with x as Re_L ∝ x~(1/2).The study suggests that differences of the self-preserving states observed may be related to the differences in the underlying turbulence structures in the near field of the seven jets.