挟沙水流试验研究

通过开展挟沙水流试验,对河槽断面的纵向时均流速横向与垂向分布、瞬时流速频率分布、紊动强度垂向分布规律进行了研究,最后分析了断面宽深比对张瑞瑾公式的影响.得出如下结论:在相同横断面面积、流量情况下,随着断面宽深比的减小,准二维流动的中心区所占河宽比例减小,断面流速分布更加趋中;挟沙水流主流区流速垂向分布基本上仍然符合对数分布,随着含沙量的增大,卡门常数k有减小的趋势;中垂线上各点瞬时流速频率分布基本上符合正态分布;靠近水面处紊动强度最弱,紊动强度随相对水深的减小而增大,随后紊动强度随相对水深的减小而减小;随着断面宽深比的减小,张瑞瑾公式中的系数呈增加的趋势,流量幂指数呈减小的趋势.

Experimental research of sediment load flow

Through the test of sediment load flow,the longitudinal time average velocity horizontal and vertical distribution,the instantaneous velocity distribution,the turbulence intensity distribution are studied; and the impaction of ratio of width to depth of riverbed cross-section on Zhang Ruijin formula is analyzed.The main conclusions are as follows: with the decreasing of ratio of width to depth of the riverbed cross-section,the ratio of the central quasi-two-dimension flow decrease; the longitudinal time average velocity vertical distribution conforms to the logarithmic formula; with the increasing of the critical sediment concentration,the Kaman constant k decrease; the instantaneous velocity distribution conforms to the normal distribution; with the decreasing of the relative water depth,the turbulence intensity firstly increases then decreases; with the decreasing of the ratio of width to depth of the riverbed cross-section the coefficient in the Zhang Ruijin formula increases and the power index of discharge decreases.