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 (par...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.展开更多
基金Project supported by the National Natural Science Foundation of China.
文摘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.
