Question

Water flows from an upper reservoir to a lower reservoir through a 150-m long 350-mm diameter tunnel that feeds a turbine. The tunnel has an estimated roughness height of 1 mm and the turbine is expected to extract energy from the water at a minimum rate 60 kW. The entrance and exit loss coefficients are 0.8 and 1.0, respectively. What is the minimum flow rate through the tunnel that is required to accomplish this objective? (The height between upper and lower reservoir is 45m)