Research On The Properties Of Air Entrainment In The Spillway Tunnel Of Jinping-1 Hydropower Station

With the increasing number of constructing dams,high-speed flow issues are also increasingly prominent,improper handling would seriously affect the safe operation.Jinping-1 hydropower station has the typical spillway of high arch dam,spillway tunnel is a major way of the station,with characteristics such as the high head,large discharge volume,flow conditions,the in-depth study about the two phase flow which formed during the water discharging program has important significance.This paper combines Jinping-1 prototype observation of the spillway tunnel test with numerical simulation to study the ventilation characteristics and aerated flow characteristics,the main contents of the study and conclusions include:(1)By the prototype observation test of the spillway tunnel of Jinping-1 hydropower station,the amount and distribution of the wind speed and the noise of the spillway tunnel hole to aeration,the wind speed and noise of spillway tunnel export,and the fluid with air entrainment are analyzed,and this paper analyses the pulsating pressure of the fluid in spillway tunnel and the speed of wind in the ventilating shaft in time domain and frequency domain characteristics.(2)Using the prototype observation of the spillway tunnel test in Jinping-1 hydropower station and the numerical simulation,this paper studies the air entrainment flow downstream of an aerator,spillway tunnel total intake air distribution ratio,the spillway tunnel intake air and fluid relations,and the flood process noise and other related characteristics.The results of the above research: getting a empirical formula about the capacity of the air entrainment flow downstream of an aerator and the fluid required aeration in about 30 percent of the total volume of intake air in the spillway tunnel,and with the total intake air increasing,the Froude number of the flow is reducing,and the space on the fluid also is a factor to influent the aeration capacity in the spillway tunnel,proposing a formula to convert the wind speed pulsations to noise.(3)Through the research and analysis of the decay rate of the air entrainment and the calculation of aerated fluid depth,this paper gets the results that the rate of decay of the air entrainment is not suitable for other projects referenced directly.By comparing the main aeration fluid depth calculation formula,basing on the prototype observation on Jinping-1 hydroprower station,this paper finds that Hall formula,Lakshmano formula and diesel-Christine pure formula is more suitable for the actual situation.