Losses in Pipe FlowsMajor Losses: due to friction, significant head loss is associated with the straight portions of pipe flows. This loss can be calculated using the Moody chart or Colebrook equation.Minor Losses: Additional components (valves, bends, tees, contractions, etc) inpipe flows also contribute to the total head loss of the system. Their contributionsare generally termed minor losses.The head losses and pressure drops can be characterized by using the loss coefficient,KL, which is defined asOne of the example of minor losses is the entrance flow loss. A typical flow pattern for flow entering a sharp-edged entrance is shown in the following page. A vena contracta region if formed at the inlet because the fluid can not turn a sharp corner.Flow separation and associated viscous effects will tend to decrease the flow energyand the phenomenon is complicated. To simplify the analysis, a head loss and the associated loss coefficient are used in the extended Bernoulli’s equation to take intoconsideration of this effect as described in the next page.KhV gpp K VLLLV= = =2 2122212/,∆∆ρρ so that 12 03 72 51f fD= − +FHGIKJ. log..Re,ε valid for nonlaminar rangeMinor Loss through flow entranceV2V3V1(1/2)ρV22(1/2)ρV32KL(1/2)ρV32p→p∞ghKzzgKVVpppgVKhzgVphzgVpLLLLL+=−+=≈===++=−++∞12)(2(11,0,2,22:Equation sBernoulli' Extended3131312332331211γγgzVp
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