出水口位置对异重流运动及泥沙分布的影响
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摘要
在实验室小环境下模拟大型水库及水库的分层环境,在水库温度分层条件下进行异重流实验,研究不同出水口位置条件下由水温分层引起的间层流现象,并探究分层环境下,出水口不同位置水库异重流运动的普遍规律及泥沙分布特性。结果表明:当入流泥沙浓度确定,出水口分别位于上、中、下层时,异重流的厚度、分离点深度、水跃高度和行进时间等参数数值差异较小;当入流泥沙浓度确定,上层出水口形成的间层流厚度基本沿程不变,中、下层出水口的间层流会因卷吸作用而卷吸周围清水导致间层流厚度局部增加;出水口位置确定,入流泥沙浓度基本不影响排沙比;入流泥沙浓度确定,上层出水口的排沙比远远大于中层和下层的排沙比。
The large reservoir and its stratified water environment could be simulated in a small laboratory environment. The density currents experiments were carried out under the condition of reservoir temperature stratification. The phenomenon of laminar density currents caused by water temperature stratification under different outlet positions was studied. Besides,exploration has been done about the universal law of the density currents movement and the sediment distribution characteristics in the stratified environment. As it turned out,when the influent sediment concentration was determined and the outlet position was located at the upper,middle and lower levels respectively,the parameters' numerical difference was small in terms of the thickness of the density current,the depth of the separation point,the hydraulic jump height and the travel time. When the sediment concentration was determined,the thickness of the laminar density currents was almost constant along the way in the upper outlet position; and the thickness of the same would increase partially due to the sucking effect from clear water in the middle and bottom outlet positions. When the water outlet position was set unchanged,the influent sediment concentration basically did not affect sedimentation ratio. When the sediment concentration was determined,the sedimentation ratio at the upper outlet position was much larger than that at the middle and bottom outlet positions.
The large reservoir and its stratified water environment could be simulated in a small laboratory environment. The density currents experiments were carried out under the condition of reservoir temperature stratification. The phenomenon of laminar density currents caused by water temperature stratification under different outlet positions was studied. Besides,exploration has been done about the universal law of the density currents movement and the sediment distribution characteristics in the stratified environment. As it turned out,when the influent sediment concentration was determined and the outlet position was located at the upper,middle and lower levels respectively,the parameters' numerical difference was small in terms of the thickness of the density current,the depth of the separation point,the hydraulic jump height and the travel time. When the sediment concentration was determined,the thickness of the laminar density currents was almost constant along the way in the upper outlet position; and the thickness of the same would increase partially due to the sucking effect from clear water in the middle and bottom outlet positions. When the water outlet position was set unchanged,the influent sediment concentration basically did not affect sedimentation ratio. When the sediment concentration was determined,the sedimentation ratio at the upper outlet position was much larger than that at the middle and bottom outlet positions.
引文
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[19]PAKER G,GARCIA M,FUKUSHIMA Y,YU W.Experiments on turbidity currents over an erodible bed[J].Journal of Hydraulic Research,1987,25(1):123-147.
[2]DORREL R M,DARBY S E,PEAKALL J,et al.The critical role of stratification in submarine channels:implications for channelization and long runout of flows[J].Journal of Geophysical Research Oceans,2014,119(4):2620-2641.
[3]范家骅.异重流交界面波动失稳条件[J].水利学报,2010,41(7):849-855.(FAN Jiahua.Interfacial instability in density currents[J].Journal of Hydraulic Engineering,2010,41(7):849-855.(in Chinese))
[4]BENJAMIN T B.Gravity currents:in the environment and laboratory[M].Cambridge:Cambridge University Press,1999.
[5]KASSEM A,IMRAN J.Simulation of turbid underflow generated by the plunging of a river[J].Geology,2001,29(29):655-658.
[6]FEMANDEZ R,IMBER G J.Time-varying underflow into a continuous stratification with bottom slope[J].Journal of Hydraulic Engineering,2008,134(9):1191-1198.
[7]中国科学院水利电力部水利水电科学研究院河渠研究所.异重流的研究和应用[M].北京:水利电力出版社,1959.
[8]WANG Z,YU G,HUANG H,et al.Gender of large river deltas and parasitizing river[J].International Journal of Sediment Research,2012,27(1):18-36.
[9]HUANG H,IMRAN J,PIRMEZ C.Numercial modeling of poorly sorted depositional turbidity currents[J].Journal of Geophysical Research,2007,112(C1):1-15.
[10]UNGARISH M.On gravity currents in a linearly stratified ambient:a generalization of Benjamin stesdy-state propagation results[J].Journal of Fluid Mechanics,2006,548:49-68.
[11]BAINES P G Mixing in flows down gentle slopes into stratified environments[J].Journal of Fluid Mechanics,2001,443:237-270.
[12]DAI A.Experiments on gravity currents prapagating on different bottom slopes[J].Journal of Fluid Mechanics,2013,731:117-141.
[13]贺治国,林挺,赵亮,等.异重流在层结与非层结水体中沿斜坡运动的实验研究[J].中国科学:技术科学,2016,46(6):570-578.(HE Zhiguo,LIN Ting,ZHAO Liang,et al.Experiments on gravity currents down a ramp in unstratified and linearly stratified salt water environments[J].Science China Technological Sciences,2016,46(6):570-578.(in Chinese))
[14]KATE S,SUTHERLAND B R.Particle-laden flow down a slope in uniform stratifition[J].Journal of Fluid Mechanics,2014,755:251-273.
[15]SIMPSON J E.Gravity currents in the labortatory,atmosphere,and ocean[J].Annual Review of Fluid Mechanics,2003,14(1):213-234.
[16]SAMOTHRAKIS P,COTEL A J.Propagation of a gravity current in a tuo-layer stratified environment[J].Journal of Geophysical Research,2006,111(C1):281-291.
[17]范家骅.浑水异重流水量掺混系数的研究[J].水利学报,2011,42(1):19-26.(FAN Jiahua.Studies on water entrainment coefficient of turbid density currents[J].Journal of Hydraulic Engineering,2011,42(1):19-26.(in Chinese))
[18]王睿禹,GARCIA M,PARKER G.异重流卷吸系数和运行距离的初步探讨[J].泥沙研究,2015(6):6-13.(WANG Ruiyu,GARCIA M,PARKER G.Study on water entrainment coefficient and travel distance of density current[J].Journal of Sediment Research,2015(6):6-13.(in Chinese))
[19]PAKER G,GARCIA M,FUKUSHIMA Y,YU W.Experiments on turbidity currents over an erodible bed[J].Journal of Hydraulic Research,1987,25(1):123-147.