Experimental Study And Numerical Simulation On Hydraulic Characteristics Of Culvert-type Sluice Outflow

Culvert-type sluices are common infrastructures in hydraulic engineering, which play an important role in irrigation, drainage, flood control, and so on. Comparing with ordinary sluices, more factors need to be considered for culvert-type sluices in the hydraulic and structural calculation. Therefore, the studies on hydraulic characteristics of culvert-type sluice outflow are of great importance in the design, operation and scientific management as well as bringing them into normal performances. The hydraulic model test was conducted to observe and analyze the flow patterns in the culvert-type sluice, the energy dissipating basin and the downstream river. Based on computational fluid dynamics and commercial software FLUENT, RNG κ-ε turbulence model and VOF method was adopted to simulate the hydraulic characteristics of the culvert-type sluice outflow.The main research contents and achievements of this paper are as follows:(1) Through hydraulic model test, the operational control parameters of sluice gate and flow-rate characteristics are obtained. The model test results indicate that there is an approximate linear relationship between the flow-rate of sluice gate and its relative opening.(2) Since the bottom slope of the culvert is comparatively large, the flow in culvert belongs to open channel flow under many combinations of the water level and gate opening, and the location of hydraulic jump in the culvert depends on the downstream water level and the flow rate through the sluice. The test result shows that when the downstream water level is lowered or the flow rate is increased, the location of hydraulic jump will be away from the outlet of culvert. At large and medium flow rate and under low downstream water level, the bias flow and backflow are easier to generate in the energy-dissipating basin, which will affect the flow patterns in the river after the energy-dissipating sill. Until to the straight section of river downstream, the velocity distribution gradually tends to be even and the flow becomes basically stable.(3) Through optimal design, a bottom sill was set up in the culvert. Thus, the water depth in the culvert was increased effectively and the flowing velocity decreased, and the location of hydraulic jump was regulated, making the flow patterns inside the culvert and outflow conditions improved.(4) The comparison of computed results from numerical simulation with the model test results of culvert-type sluice shows that the velocity and pressure distribution are generally coincident in tendency. Through the calculation on the relevant parameters of hydraulic jump and comparing with the values obtained the model test, errors exist between the calculated values and the test ones, but the differences are relatively small.