Chapter 8, Problem 79P

Reconsider Prob. 8-78. In order to drain the tank faster, a pump is installed near the tank exit as in Fig. 8-79. Determine how much pump power input is necessary to establish an average water velocity of 4 m/s when the tank is full at z = 2 In. Also, assuming the discharge velocity to remain constant, estimate the time required to drain the tank.
Someone suggests that it makes no difference whether the pump is located at the begining or at the end of the pipe, and that the performance will be the same in either, case, but another person argues that placing the pump near the end of the pipe may cause cavitation. The water temperature is 30CC. so the water vapor pressure is P1. 4.236 kPa 0.43 m H₂O, and the system is located at sea level. Investigate if there is the possibility of cavitation and if we should be concerned about the location of the plump.