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Week5 Recitations

Descriptions In this Week 5 recitation for Water Resources Engineering 222, we covered two major topics in pipeline hydraulics. We began with the water hammer phenomenon, exploring how sudden changes in flow velocity — such as rapid valve closure — generate pressure waves in pipelines. We discussed the role of the bulk modulus of elasticity, derived the wave celerity (C), and applied the water hammer equation ΔH = V₀C/g to calculate pressure head rise. We then transitioned to pump power and efficiency, breaking down the power cascade from motor input to fluid output, applying motor and pump efficiencies, and using the pump output power formula P_o = γQH_p. Finally, we worked through the energy equation with a pump (H_A + H_p = H_B + h_L) to determine the required pump head in pipeline systems accounting for elevation differences and friction losses. Problem 1: Water Hammer in a Concrete Pipeline 02:49 This section covers how to determine the pressure head rise for an instantaneous valve closure and includes a conceptual discussion on how fluid density (slurry vs. water) affects water hammer severity Problem 2: Pump Flow Rate and Efficiency 07:39 This problem involves calculating the flow rate for a water pump by chaining together motor and pump efficiencies using a "power cascade" model Problem 3: Dam Drawdown and Volume Balance 11:53 This section combines pump power analysis with a volume balance to estimate how many centimeters a lake's water level will drop over a two-hour period Problem 4: Pump Power Requirement with Friction Losses 16:05 The final problem calculates the total power required for a pump system, accounting for elevation changes and frictional losses using the energy equation and the Moody chart