ME 331-HW-5 - Re= 501 523 From Moody diagram (or...

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Solution for HW5 Spring 2009 ME331 a) Surface roughness for a new commercial steel pipe: ε =0.00015 m b) Minor and major losses a. For the suction side: Nominal size: 300mm => inner diameter: 304 mm => Area= 0.0725 m2 => u=1.378 m/s Re= 418 912 From Moody diagram (or correlations in the book) : f( ε /D, Re)=0.0177 Major loss: hsuction,major= g G ± ² ³ ´µ = 0.01858 m Minor losses: - Entrance: Assume a bell mouth entrance: K=0.05 - 2 regular and flanged 90 o elbows: K= 0.3 - a fully open globe valve: K= 10 - Minor losses: hsuction,minor= u¶ U ² ³ ´µ = (0.05+2 · 0.3+10)u 2 /2g= 1.03 m b. For the discharge side: Nominal size: 250mm => inner diameter: 254 mm => u=1.975 m/s
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Unformatted text preview: Re= 501 523 From Moody diagram (or correlations in the book) : f( ε /D, Re)=0.01813 Major loss: hsuction,major= g G ± ² ³ ´µ = 0.6752 m Minor losses: -Exit: Assume a bell mouthed outlet: K=0.2 -3 regular and threaded 90 o elbows: K= 1.5 -a ½ closed gate valve: K= 2.1 -Minor losses: hsuction,minor= u¶ U ² ³ ´µ = (0.2+3 · 1.5+2.1)u 2 /2g= 1.35 m c) Power delivered to water: Δ P pump = ρ g(H stat + all losses) = ρ g(14+0.01858+1.03+0.6752+1.35)=167 493 Pa P delivered = Q · Δ P pump =16.7 kW d) η = P delivered /Power input to pump=0.73...
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