Abstract:

Based on the mechanism experiments conducted for the spillway of the Lianghekou hydropower station, this study investigates the variations tendencies of the flow regime, dynamic pressure, air vent cavities, wind speed, and aeration concentration under three types of aeration thresholds. The applicability of formulas for calculating cavity length, aeration rate, and aerated water depth are analyzed, and the derived conclusions could be employed for further investigation on Lianghekou hydropower station and other similar hydraulic engineering. The research findings indicate that the aeration phenomena in the water flow become more pronounced with the increasing of the discharge of the spillway, and several hydraulic indicators are increasing simultaneously, including the root mean square of the pulsating pressure, air entrainment degree, cavity pressure, cavity length and other hydraulic parameters. For certain discharge, the air concentration increases along the spillway, and the vertical distribution of aeration concentration appears successively as "C"-shaped, "S"-shaped, and "I"-shaped patterns. For certain location of the spillway, the air concentration increases with the increasing of the discharge, and the vertical distribution of aeration concentration follows successively as "I"-shaped, "S"-shaped, and "C"-shaped patterns. According to the research founding of this study, it is recommended that the Shiqisui formula, Chenzhaohe formular, and HALL formular are most suitable for the estimations of the cavity length, aeration rate, and aerated water depth, respectively.

Key words: cavity length, depth of aerated water, aeration concentration, amount of aeration