Analysis of Waterhammer in Case the Water Level of Reservoir Fluctuates

Abstract

For waterhammer analysis, the water level of reservoir has been hitherto generally assumed to be constant. But, in the case of surge tank, the water level as a rule fluctuates so widely that it is indispensable to investigate its effects. If the reservoir water level is expressed as H=H_L (t), that is, a function of time, the waterhammer equation can be derived as follows : H_i-H₀=a/g (V₀-V_i)-2Σ^^(i-1)__(i=1)(H_i-H₀)+2Σ^^i__(i=1){(H_L)_i-(1/2)-H₀} Applying this equation instead of the usual one, and using equations concerning surge tank together, waterhammer in pumping plant with surge tank is computed in consideration of level fluctuation. In practice, however, the conventional method, by which the flow and pressure transition is first calculated under the assumption that surge tank level remains constant, then level fluctuation is computed under the flow condition that is obtained above, and the pressure is modified, will give satisfactory results.