A Study of the Turbulent Flows in Sloping and Adversely Sloping Rectangular Culverts

Abstract

In this paper, an experimental investigation was carried out to study the turbulent flows and flow characteristics through sloping and adversely sloping rectangular culverts in a rectangular channel of constant width using Laser Doppler Velocimetry (LDV). Also, experimental study was carried out to investigate the characteristics of the hydraulic jump occurring in a sloping and adversely sloping rectangular culvert with pressurized flow downstream from the jump and a submerged culvert outlet. Experiments were conducted on a culvert with relatively small slopes to study the variation of the relative tailwater depth with the main parameters affecting the jump in sloping and adversely sloping culverts. These parameters include the channel bottom slope, the initial Froude number and the ratio of the initial depth to culvert height. To study the turbulence characteristics, precise and accurate measurements of the mean fluctuating flow quantities such as streamwise and vertical mean velocity components, and streamwise and vertical turbulence intensity components and turbulence shear stress were carried out. Also, this paper presents the results of a Laser Doppler Velocimetry study of hydraulic jumps in a culvert with different relative tailwater depths and different initial Froude numbers. The characteristics of hydraulic jumps were discussed and analyzed. Non– dimensional design curves were provided to relate the jump characteristics. The maximum vertical velocity in the recirculating zone for all jumps is about 6% of the initial velocity. The results show that the maximum streamwise velocity near the center plane was smaller than that near the side wall. The turbulence shear stress near the center was about (35-45)% higher than that near the side wall. After the jump, the flow will recover into a two-dimensional flow.