Author(s): Junhu Nan; Zhengming Niu; Di Hong
Linked Author(s):
Keywords: Horizontal gyrating flow; Prototype; Hydraulic characteristics; Contrast and analysis; Scale effect
Abstract: The horizontal gyrating discharge tunnel is one of the most efficient internal dissipation technology from the view point of ecological environment and economic benefit. Based on the prototype and model tests of Gongboxia hydropower station, the hydraulic characteristics of horizontal gyrating flow, such as flow pattern, pressure, velocity, ventilation and energy dissipation ratio, were analyzed and compared The results indicated that the flow pattern of prototype and models in weir section are fundamentally similar, and the discharge conform to basic law of pressure orifice outflow and gravity similarity principle. In vertical shaft, the annular cavity length differences between prototype and models are greater, therefore, the velocity near the wall, pressure change process, negative pressure value and ventilation of models are not similar to prototype and have obvious scale effect, the strength of scale effect is proportional to the scale. For 1: 40 or the model with a greater scale, the relative ventilation ratio approaches 1. 0 in the starting rotation device ventilating shaft. The energy dissipation ratio of horizontal gyrating discharge tunnel is up to 84% and the ratios between prototype and models are basically consistent.
Year: 2013