PipeFlow_PracticeProblems

PipeFlow_PracticeProblems - Practice Problems on Pipe Flows...

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Practice Problems on Pipe Flows C. Wassgren, Purdue University Page 1 of 23 Last Updated: 2010 Oct 15 pipe_02 A homeowner plans to pump water from a stream in their backyard to water their lawn. A schematic of the pipe system is shown in the figure. Details of the system are given in the following table. The design flow rate for the system is 2.5*10 -4 m 3 /s. Item Value water density 1000 kg/m 3 water dynamic viscosity 1*10 -3 kg/(m.s) inlet pipe length 2 m inlet pipe diameter 2.5 cm inlet pipe material drawn tubing hose length two 15.25 m lengths hose diameter 1.3 cm hose roughness smooth pipe inlet loss coefficient 0.8 inlet pipe-to-pump coupling loss coefficient 0.1 pump-to-hose coupling loss coefficient 0.2 hose-to-hose coupling loss coefficient 0.5 pressure drop across the sprinkler 210 kPa at 2.5*10 -4 m 3 /s flow rate sprinkler nozzle exit diameter 4 mm 1. What is the loss coefficient for the sprinkler at design conditions? Base the sprinkler loss coefficient on the velocity just upstream of the sprinkler. sprinkler 2. What is the friction factor for the hose? hose 3. What is the velocity head, including the kinetic energy correction factor, at the sprinkler exit? 2 sprinkler exit 20.2 m 2 V g For the next two questions, assume that the loss coefficient for the sprinkler is 100 and the friction factor for the hose is 0.01. 4. What is the total minor head loss in the system? L ,minor 5. What is the total major head loss in the system? L ,major For the next question, assume that the velocity head at the sprinkler exit, including the kinetic energy correction factor, is 10 m and the total head loss is 10 m. 6. What is the shaft head required to operate the system at the design flow rate? S For the next question, assume that the shaft head required to operate the system at the design flow rate is 100 m. 7. What power must be supplied to the pump if the pump is 65% efficient? into pump 35 W W sprinkler hose-to-hose coupling pump stream re-entrant pipe inlet 3 m 1 m 2 m of 2.5 cm diameter drawn tubing two 15.25 m lengths of 1.3 cm diameter garden hose pump-to-hose coupling inlet pipe-to-pump coupling
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Practice Problems on Pipe Flows C. Wassgren, Purdue University Page 2 of 23 Last Updated: 2010 Oct 15 pipe_03 It rains during the construction of a building and water fills a recently excavated pit to a depth, h =0.5m. In order to continue construction, the water must first be pumped out of the pit. A hose with a length of L =50m, a diameter of D =2.5*10 -2 m, and a surface roughness of =5.0*10 -5 m is attached to a pump. Note that the kinematic viscosity of the water is =1.005*10 -6 m 2 /s and the density is =1000 kg/m 3 . a. If the pump is placed at the pit’s surface (figure a), what is the maximum depth of the pit, H , for which water can be pumped out at a velocity of V =1 m/s without causing cavitation in the pipe? The vapor pressure of water for the current temperature is p v =2.337 kPa (absolute pressure) and atmospheric pressure is p atm =101 kPa (absolute pressure).
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This note was uploaded on 10/01/2011 for the course ME 509 taught by Professor Wereley during the Spring '11 term at Purdue University-West Lafayette.

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PipeFlow_PracticeProblems - Practice Problems on Pipe Flows...

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