流體力學英文版課后習題答案-資料下載頁
2025-06-20 08:49本頁面
【正文】 ow rate ，m179。/h 26Total heads，m Shaft power ，kW Efficiency ，% Water is transported by a pump from reactor, which has 200 mm Hg vacuum, to the tank, in which the gauge pressure is kgf/cm2, as shown in Fig. The total equivalent length of pipe is 200 m including all local frictional loss. The pipeline is f57 mm , the orifice coefficient of Co and orifice diameter do are and 25 mm, respectively. Frictional coefficient l is . Calculate: Developed head H of pump, in m (the reading R of U pressure gauge in orifice meter is 168 mm Hg)Solution:Equation()Mass flow rate2) Fluid flow through the pipe from the reactor to tank, the Bernoulli equation is as followsfor V1=V2Dz=10m Dp/rg=The relation between the hole velocity and velocity of pipeFriction lossso H=+10+=Hg . A centrifugal pump is to be used to extract water from a condenser in which the vacuum is 640 mm of mercury, as shown in figure. At the rated discharge, the net positive suction head must be at least 3m above the cavitation vapor pressure of 710mm mercury vacuum. If losses in the suction pipe accounted for a head of . What must be the least height of the liquid level in the condenser above the pump inlet?Solution:From an energy balance,Where Po=760640=120mmHgPv=760710=50mmHgUse of the equation will give the minimum height Hg as Sulphuric acid is pumped at 3 kg/s through a 60m length of smooth 25 mm pipe. Calculate the drop in pressure. If the pressure drop falls by one half, what will the new flowrate be ? ? Density of acid 1840kg/m3? Viscosity of acid 25103 PasSolution:Velocity of acid in the pipe:Reynolds number:from for a smooth pipe when Re=6109, f=pressure drop is calculated from equation or friction factor is calculated from if the pressure drop falls to sonew mass flowrate==1840= Sulphuric acid is pumped at 3 kg/s through a 60m length of smooth 25 mm pipe. Calculate the drop in pressure. If the pressure drop falls by one half on assumption that the change of friction factor is negligible, what will the new flowrate be ? Density of acid 1840kg/m3 Viscosity of acid 25103 PaFriction factor for hydraulically smooth pipeSolution:Write energy balance equation:Δp=1840= The fluid is pumped through the horizontal pipe from section A to B with the diameter and length of 30 meters, shown as figure. The orifice meter of diameter is used to measure the flow rate. Orifice coefficient Co＝. the permanent loss in pressure is 104N/m2, the friction coefficient λ=. find: (1) What is the pressure drop along the pipe AB? (2)What is the ratio of power obliterated in pipe AB to total power supplied to the fluid when the shaft work is 500W, 60%efficiency? (The density of fluid is 870kg/m3 ) solution：∴u= ()2=∴(2)sothe ratio of power obliterated in friction losses in AB to total power supplied to the fluid 歡迎您的光臨，！希望您提出您寶貴的意見，你的意見是我進步的動力。贈語； 如果我們做與不做都會有人笑，如果做不好與做得好還會有人笑，那么我們索性就做得更好，來給人笑吧！ 現(xiàn)在你不玩命的學，以后命玩你。我不知道年少輕狂，我只知道勝者為王。不要做金錢、權利的奴隸；應學會做“金錢、權利”的主人。什么時候離光明最近？那就是你覺得黑暗太黑的時候。最值得欣賞的風景，是自己奮斗的足跡。壓力不是有人比你努力，而是那些比你牛幾倍的人依然比你努力。 參考
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