EFFECTS OF SUSPENDED SEDIMENTS ON TURBULENT OPEN CHANNEL FLOWS

摘要

Accurate information on sediment and velocity profiles is very important to fully understand the turbulent characteristics of sediment-laden flows in open channels. Measurements have been carried out in this study to investigate the effects of suspended sediments on open channel turbulent flows. The study was conducted at laboratory scale in a sediment flume under steady, uniform flow conditions for various flow rates. Firstly clear-water flow conditions were studied before the research was extended to suspended sediment-laden flows for various concentrations ranging from non-capacity to capacity conditions. Acoustic Doppler Velocimeter (ADV) was utilised to measure the 3-dimensional velocity components and an infra-red sediment sensor was deployed to continuously record the concentration of suspended sediments. Results from preliminary observations have been reported in this paper. Vertical velocity profiles for clear-water and sediment-laden flows are compared for various flow rates and the effects of sediment concentrations on velocity distribution are discussed. Sediment profiles are also presented to explore the effects of concentration and flow rate on suspended sediment-laden flows.