摘要
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(≡Ujh/ν,其中Uj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,平均速度和湍流强度更难达到自保持状态.沿轴线的积分尺度随轴向距离成线性增长但随雷诺数的增大增长速度减慢.同时发现,平面射流的局部雷诺数会随轴向距离的增大而增大.最后,通过对比湍流能谱并结合以往发表的结果,对不同雷诺数的射流所表现出的不同的统计学行为给出了解释.
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/ν（U_j being the momentum-averaged exit mean velocity, h the slot height and ν 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∝x1/2. 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.
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2009年第11期7756-7764,共9页
Acta Physica Sinica
基金
国家自然科学基金(批准号:10772006)资助的课题~~
关键词
平面射流
雷诺数
自保持性
plane jet
Reynolds number
self-preservation
