DIRECT RESONANCE OF TURBULENT BOUNDARY LAVER OVER COMPLIANT WALLS

１．　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｍａｉｎｇｏａｌｏｆｔｈｉｓｐａｐｅｒｉｓｔｏｅｘｐｌｏｒｅｔｈｅｐｏｓｓｉｂｉｌｉｔｙｔｏｌｅａｒｎｍｏｒｅａｂｏｕｔｔｈｅｍｅｃｈａｎｉｓｍｏｆｔｕｒｂｕｌｅｎｔｂｏｕｎｄａｒｙｌａｙｅｒｆｌｏｗｉｎｔｅｒａｃｔｉｏｎｓａｎｄｉｔｓｅｆｆｅｃｔｓｏｎｃｏｍｐｌｉａｎｔｗａｌｌｐｅｒｆｏｒｍａｎｃｅ．Ｔｈｅｒｅａｒｅｃｅｒｔａｉｎｐｒｅｒｅｑｕｉｓｉｔｅｃｏｎｄｉｔｉｏｎｓｔｏｆｕｒｔｈｅｒｔｈｅｓｔｕｄｙｏｎｔｈｅｍｅｃｈａｎｉｓｍ，ｉ．ｅ．ｔｈｅｃｏ…     

EXPERIMENTAL STUDIES AND NUMERICAL CALCULATION ON TURBULENT BOUNDARY LAYER OF WATER FLOW ALONG CURVED SURFACE

This paper will introduce experimental studies and numerical calculation onturbulent boundary layer of water flow along curved surface in our country in recent years.Onthe basis of the experimental studies,the effects of curvature and roughness on velocitydistribution and pressure distribution and the change of turbulent flow boundary layer onoverflow bucket concave surface is discussed.We proposed the empirical formula of velocity,pressure and the change of turbulent flow boundary layer on outlet bucket concave.According tothe momentum principle,we have deduced the momentum integral equation full water depthboundary layer and using the element as control unit inside the boundary layer on concavesurface of bucket.Combining with continuity equation,we have computed the boundary layerdevelopment on the bucket of a spillway.Compared with the field experimental data,thecalculation results are available.Under polar coordinates,a mathematical model for simulatingtime-averaged flow characteristics in concave surface of bucket is established.The turbulent flowfield on concave surface of bucket is calculated by SIMPLE method and this mathematicalmodel.The flow velocity field,pressure field,distribution of turbulent kinetic energy,distribution of turbulent energy dissipating rate and distribution of shear stress are available.Thecalculation value is consistent with measured test data.     

EXPERIMENTAL INVESTIGATIONS ON DIFFUSION CHARACTERISTICS OF HIGH CONCENTRATION JET FLOW IN NEAR REGION

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｒｅｓｅａｒｃｈｏｆｊｅｔｉｓａｎｉｍｐｏｒｔａｎｔｆｉｅｌｄｉｎｆｌｕｉｄｍｅｃｈａｎｉｃｓ.Ｉｔａｌｓｏｈａｓｍａｎｙａｐｐｌｉｃａｔｉｏｎｓｉｎｅｎｇｉｎｅｅｒｉｎｇ ,ｆｏｒｅｘａｍｐｌｅ ,ｔｈｅｄｉｓｃｈａｒｇｅｏｆｐｏｌｌｕｔａｎｔａｎｄｃｏｏｌｉｎｇｗａｔｅｒｉｎｉｎｄｕｓｔｒｉｅｓ .Ｗｈｅｎｔｈｅｉｎｉｔｉａｌｄｅｎｓｉｔｙｏｆｔｈｅｊｅｔｉｓｄｉｆｆｅｒｅｎｔｆｒｏｍｔｈａｔｏｆｔｈｅａｍｂｉｅｎｔｗａｔｅｒｂｏｄｙ ,ｔｈｅｊｅｔｗｉｌｌｂｅａｆ…     

挑坎型掺气减蚀设施过流掺气特性研究

采用一维激光测速系统，对掺气减蚀工程中常用的直线型挑坎的流场特性进行试验研究．通过测量挑坎上及空腔区水流的流速分布及紊动特性，探讨通气量与紊动强度的关系．同时在深入研究流场特性和掺气机理的基础上，通过分析影响掺气的因素，从理论上探求临界掺气流速的计算，重点分析挑坎型掺气过流在空腔负压较大的情况下，临界掺气条件的理论预测，并通过试验资料验证了该计算方法．在此基础上，还进一步研究了掺气量的计算公式及其变化规律．     

泄水建筑物下游冲刷坑二维数值模拟

对巨亭水电站泄水建筑物下游局部冲刷过程进行了二维数值模拟。采用RNG k-ε湍流模型封闭N-S方程、有限体积法在计算网格上离散求解、VOF方法追踪自由水面;采用C语言编写用户自定义函数,以泥沙起动切应力作为床面泥沙起动判别标准,通过分析比较水流剪切力与泥沙起动切应力大小,用以控制冲刷坑底部边界变化;采用局部重构模型和弹簧光顺模型更新计算区域和网格质量,藉以模拟和追踪局部冲刷坑边界变化。研究表明,模拟结果与实测资料符合良好。在冲刷坑的冲刷过程中,床面剪切应力随着冲刷的进程急剧减小,湍动能随着冲刷的进程减小缓慢;床面剪切应力和湍动能沿程变化均较为剧烈,床面剪切应力沿程先增大后减小,床面湍动能则沿程减小。冲刷坑的纵向平衡形态或床面泥沙起动主要决定于床面剪切应力,床面湍动能对泥沙起动也具有重要影响。     

跌坎型底流消能工的跌坎最小深度研究

跌坎型底流消能工消力池内的水力特性受到跌坎深度的影响。应用平面紊动射流理论,以消力池内允许的最大时均动水压强为控制目标,对于跌坎最小深度的确定方法进行了初步分析,建立了计算跌坎最小深度值的理论公式。通过水力学试验方法,得到消力池底板时均动水压强与跌坎最小深度之间的关系,同时与跌坎最小深度试验值进行了比对,对本文建立的理论公式进行了验证。     

The inception cavitating flows over an axisymmetric body with a blunt head-form

The inception cavitating flows around a blunt body are studied based on flow visualizations and velocity field measurements. The main purpose of the present work is to study the incipient cavity evolution and the interplay between the inception cavitation and the local turbulent flows. A high-speed video camera is used to visualize the cavitating flow structures, and the particle image velocimetry(PIV) technique is used to measure the velocity field, the vorticity, and the Reynolds stresses under non-cavitating and inception cavitating flow conditions. It is found that the appearance of visible cavities is preceded by the formation of a cluster of micro-bubbles not attached to the body surface and in a hairpin-shaped vortex structure. During its evolution, the cavity moves downstream with a lower speed. The effect of the incipient cavity is significant on the local vortical structures but slight on the timeaveraged velocity distribution. The mean Reynolds stress distributions in the turbulent shear flow can be substantially altered by the incipient cavities. The presence of the incipient cavities can lead to the production of turbulent fluctuations.