Study On The Orifice Characteristics Of Impedance Surge Chamber

For the pressure diversior of the long diersion tunnel,the large water hammer pressure will be caused by the long pipeline,which have an adverse effect on the operation of the hydropower station.In order to ensure the safe and stable operation of pepeline and hydraulic units,That means surge chamber needs to be set to achieve the purpose of reducing the water hammer pressure.Based on previous research results and engineering practice,this paper jointly calculates the water hammer pressure of the hydropower station and the surge of the surge tank by establisions were obtained:(1)Under large fluctuation conditions,there is a certain relatinship between the impedance hole and the cross-sectional area ratio of the water intake channel.When the interval is 28-46%,the adjustment guarantee parameters can meet the sctual requirements,and there is a certain safety margin.Considering the overcurrent characteristics of the impedance hole,the flow coefficient of the impedance hole and the increase of the diameter can both decrease has a greater influence than the flow coeffcient.The choice is mainly based on the economic and excavation difficulty,and has little effect an the adjustment parameters.The larger the area of the surge tank,the smaller the surge level of the surge chamber.(2)Under small fluctuation conditions,the ratio of the impedance hole to the attenuation decreases,the overshoot increases,and the adjustment quality deteriorates.When the impedance orifice area and flow coefficient decrease,the regulating quality becomes better,which indicates that the area of surge tank is positively correlated with the change of the regulating quality of the unit.(3)Under the condition of hydraulic interference,the ratio of the impedance hole water intake area increases continuously,and the output of the disterbed unit increases.The impedance hole area or flow coefficient increases,and the output swing also increases.The area of the surge chamber increases,and the output swing of the unit reduces.And the ideal output of the large power grid is greater than the limited power grid.Whether it is an ideal large power grid or a limited power grid,the output swing of the disturbed units of multiple units under load rejection is greater than that of one unit when the load is unloaded.The change trend of the output swing of the unit is consistent with the change process of the surge in the surge chamber,and the surge of the surge chamber has a great influence on the output swing of the unit.