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QUESTIONS

QUESTIONS. Practice. Water flows through a 2-inch diameter pipe at 200 lbm/min. Its temperature is 60 o F. Find the velocity of water flow (fps). Practice.

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QUESTIONS

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  1. QUESTIONS

  2. Practice • Water flows through a 2-inch diameter pipe at 200 lbm/min. Its temperature is 60oF. Find the velocity of water flow (fps).

  3. Practice • Water from a pipe line is diverted into weigh tank for exactly 9 minutes. Tank weight increases 4765 lbf. Water temperature is 60oF. Find the flow rate (gpm).

  4. Practice • Steady flow of gas through a pipe whose diameter decreases from 1.0 meter to 60cm. The gas density decreases from 2 kg/m3 to 1.6 kg/m3. The entering velocity is 25 m/s. What is exit velocity (m/s)?

  5. Example 60 cm diameter How long will it take for level to drop from h = 3m to h = 30cm? 3 cm diameter

  6. Energy equation • Comparable to First Law of Thermodynamics – conservation of energy • Bernoulli Equation limited by assumptions & missing terms • General energy equation – expanded factors

  7. General energy equation • Terms: energy per weight of flowing fluid • Units: length • Convention: head

  8. General energy equation • Equations: • Pump head: hp = [(V22 – V12)/ 2g] + ( z2 – z1) + hf + ( P2 – P1)/ • hT omitted from this equation • Power added to water: Ẃp = hp Q Where Q represents the volumetric flow rate of the water • Pump efficiency p = [(power added to water)/ (power supplied to motor)] 100

  9. Example • Water flows from a large reservoir at the rate of 1.20 ft3/s through a pipe system. See Figure. Calculate the friction losses.

  10. Homework • At the maximum rate of power generation, this hydroelectric plant takes a discharge of 141 m3/s. The head loss through the penstock and outlet is 1.52 m. What is the power generation (MW)?

  11. Elevation = 610m Penstock Powerhouse Elevation = 0 Turbine

  12. Homework • The pump supplies energy to the flow causing the upstream pressure in the 12 in. pipe to be 10psi. The downstream pressure in the 6 in. pipe is 30psi. The water flow rate is 3.92 cfs. What horsepower is delivered to the flow?

  13. PB PA PUMP

  14. Fluid flow • No-slip concept • Reynolds Number (Re) • Dye experiment • Laminar flow • Turbulent flow • Dimensional analysis – dimensionless parameter

  15. Head loss • General energy equation • Pipe friction • Hagen-Poisuelle – laminar flow • Darcy-Weisbach – laminar & turbulent flows • f : friction factor

  16. References • Images & examples • Applied Fluid Mechanics, 6th Edition, Mott, Prentice Hall • Engineering Fluid Mechanics, 5th Edition Crowe, & Roberson, Wiley • Which of the examples were helpful? • Why?

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