Question

3. (a) For the flow of a real fluid (p, u) in a rough (e measures losses lead to a pressure gradient along the pipe - Ap/L. Determine an expression for the pressure roughness) horizontal pipe energy Ap ( L pV2 gradient for a pipe of diameter - d, flowing with a mean velocity - V. pVd'd d (b) If for a 75mm diameter pipe flowing with water at 0.25m/s the measured pressure drop is 120Pa/m What will be the pressure drop/unit length and flow velocity in a 225mm diameter pipe flowing with SAE10W oil (p 870kg/m3, u 0.036kg/ms)? Assume the pipes have the same relative roughness. 4. Water flows from a large 4m detention basin (100m by 50m) along a 200mm diameter pipe for a distance of 100m at a slope of 1:200. The pipe centerline is 300mm above the base of the basin and it drains freely to a nearby channel. Calculate the steady flow rate if: (a) the flow is assumed ideal, (b) the pipe is considered smooth for the purposes of the Moody Diagram (c) the pipe has a relative roughness of 0.006 (d) the time to empty the basin for case (c) 5. A pump draws water froma well whose surface is 4m below its centerline through 9m of 150mm diameter pipe. It delivers freely at 20m above the pump centerline through 100m of 100mm diameter pipe. Both pipes are "smooth" (a) What are the pressures at the pump inlet and outlet when the flow is 20L/s. (b) What energy is added to the flow by the pump (c) What power is required to drive the pump at this flow rate if the pump efficiency is 60%.

Answer 1

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