AN EXPERIMENTAL STUDY ON TURBULENCE CHARACTERISTICS OF FLOWS OVER SMOOTH SPILLWAY DAM  

作　　者：陈长植 董曾南 

机构地区：[1]Department of Hydraulic Engineering, Tsinghua University, Beijing 100084, PRC

出　　处：《Science China Mathematics》1991年第8期977-990,共14页中国科学：数学（英文版）

基　　金：Project supported by the National Natural Science Foundation of China.

摘　　要：Precise measurements of turbulence characteristics of flows over a spillway dam weretaken in a flume model. A laboratory-made 1-dimensional laser-Doppler anemometer (LDA)system was used to measure the x-direction (paralell to local mean streamlines) turbulenceintensity, (u^(12))^(1/2/u_(eo). Particular emphasis was attached to the flow over the bucket of themodel spillway dam and additional measurements of the y-direction (normal to the surfaceof the spillway dam) turbulence intensity, (v^(12))^(1/2)/u_(eo), were taken by using a 2-dimension-al LDA system. From the observed profiles of (u^(12))^(1/2)/u_(eo) and (v^(12))^(1/2)/u_(eo). along the x- and y-directions, we can see the different characteristics of distributions of turbulence inten-sity over the flow depth in different sections of the spillway dam and different regionsinside and outside the boundary layer. In the bucket section, both components of turbulenceintensity increase abruptly in the outer region of the boundary layer and outside the boundarylayer (potential flow region) due to the concavity of that section. The turbulence intensity,either (u^(12))^(1/2)/u_(eo) or (v^(12))^(1/2)/u_(eo) will no longer keep constant along the water depth in the outerregion (potential flow region). The fluctuation of the flow quantities presents a tendency ofdiffusion from the boundary layer to the free surface. The turbulence intensity of the outerregion of the boundary layer and the potential flow region changes abruptly before and afterthe bucket center. The turbulence intensity is larger in the downstream parts.Precise measurements of turbulence characteristics of flows over a spillway dam weretaken in a flume model. A laboratory-made 1-dimensional laser-Doppler anemometer （LDA）system was used to measure the x-direction （paralell to local mean streamlines） turbulenceintensity, (u¹²)⁽1/2/u_eo. Particular emphasis was attached to the flow over the bucket of themodel spillway dam and additional measurements of the y-direction （normal to the surfaceof the spillway dam） turbulence intensity, (v¹²)^1/2/u_eo, were taken by using a 2-dimension-al LDA system. From the observed profiles of (u¹²)^1/2/u_eo and (v¹²)^1/2/u_eo. along the x- and y-directions, we can see the different characteristics of distributions of turbulence inten-sity over the flow depth in different sections of the spillway dam and different regionsinside and outside the boundary layer. In the bucket section, both components of turbulenceintensity increase abruptly in the outer region of the boundary layer and outside the boundarylayer （potential flow region） due to the concavity of that section. The turbulence intensity,either (u¹²)^1/2/u_eo or (v¹²)^1/2/u_eo will no longer keep constant along the water depth in the outerregion （potential flow region）. The fluctuation of the flow quantities presents a tendency ofdiffusion from the boundary layer to the free surface. The turbulence intensity of the outerregion of the boundary layer and the potential flow region changes abruptly before and afterthe bucket center. The turbulence intensity is larger in the downstream parts.

关 键 词：SPILLWAY DAM boundary layer TURBULENCE intensity. 

分 类 号：N[自然科学总论]