Flow Characteristics of Large Hydropower Bifurcation Under Structure Rounding Optimization

Abstract

The reinforced concrete bifurcation in hydropower station is consistently under high internal water pressure, and its diameter is usually larger than common duct junctions. To diminish or to decrease the heavy plastic zone and stress concentration, structure rounding is commonly used on bifurcation. This will bring some changes to the flow characteristic of bifurcation, and it is an interesting attempt to figure out the influence of structure rounding optimization. The realizable k–e model was employed in computational fluid dynamics numerical simulation. The water pressure distribution was compared quantitatively at several certain sections. Furthermore, uneven pressure is analyzed by relative standard deviation. Hydraulic characteristics are discussed as well, including flow pattern, excavation volume and head loss in different working conditions. The results indicate that the pressure of the pipe wall is uneven, and the maximum and minimum pressure value has a differential of 0.3–1.2 % compared to the relative static water pressure. The pressure unevenness will increase after structure rounding, and it has a positive correlation with structure rounding radius. At the same time, it is more reasonable for structure rounding in the obtuse angle region than that in the acute angle region, on account of well-distributed flow conditions and better economic benefit.