Velocity Statistics of Plane Self-Preserving Buoyant Turbulent Adiabatic Wall Plumes
Velocity Statistics of Plane Self-Preserving Buoyant Turbulent Adiabatic Wall Plumes
复制标题
平面自守浮力湍流绝热壁羽流的速度统计
作者：
R. Sangras;Z. Dai;G. Faeth
测量的速度特性的平面浮力湍流绝热壁羽流（绝热壁羽流）的描述，强调远离源的条件下，自我保护的行为近似。实验涉及氦气/空气混合物沿沿着光滑、平面和垂直的壁面上升。使用激光测速仪测量平均和波动的流向和横向流速度。在距离源92-156个源宽度处观察到自我保护行为，与靠近源的流动发展区域内的观察结果相比，产生较小的归一化羽流宽度和较大的近壁平均速度。与早期的浓度波动强度，这是异常大，由于流向浮力不稳定性的影响，速度波动强度相比，在非浮力湍流壁射流观察到的值。尽管壁面边界层继续发展，但本流的卷吸特性近似于自保持特性。测量的时间功率谱和时间和空间积分尺度的速度波动也有报道。
Measurements of the velocity properties of plane buoyant turbulent adiabatic wall plumes (adiabatic wall plumes) are described, emphasizing conditions far from the source where self-preserving behavior is approximated. The experiments involved helium/air mixtures rising along a smooth, plane and vertical wall. Mean and fluctuating streamwise and cross stream velocities were measured using laser velocimetry. Self-preserving behavior was observed 92–156 source widths from the source, yielding smaller normalized plume widths and larger near-wall mean velocities than observations within the flow development region nearer to the source. Unlike earlier observations of concentration fluctuation intensities, which are unusually large due to effects of streamwise buoyant instabilities, velocity fluctuation intensities were comparable to values observed in nonbuoyant turbulent wall jets. The entrainment properties of the present flows approximated self-preserving behavior in spite of continued development of the wall boundary layer. Measurements of temporal power spectra and temporal and spatial integral scales of velocity fluctuations are also reported.