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流体力学课后作业

1、1 A pressure of2106N/m2 is applied to a mass of wat er that initially filled a 1,000cm3 volume、Estimate itsvolume after the pressure isapplied、将2106N/m2得压强施加于初始体积为1,000cm3得水上,计算加压后水得体积。

(999、1cm3)1、2As shown in Fig、1-9,ina heatingsystemthere is a dilatationwatertank、The wholevolume ofthewater inthe system is8m3、Thelargest temperature rise is 500C and thecoefficient of volume expansion isv=0、00051/K,what is the smallestcubage of thewater bank?如图1-10所示,一采暖系统在顶部设一膨胀水箱,系统内得水总体积为8m3,最大温升500C,膨胀系数v=0、0051/K,求该水箱得最小容积?(0、2m3)Fig、1-9 Problem 1、21、3 When theincrement of pressure is 50kPa,the density of acertain liquid is 0、02%、Find thebulkmodulus of the liquid、当压强增量为50kPa时,某种液体得密度增加0、02%。

求该液体得体积模量。

( 2、5108Pa)1、4 Fig、1-10 shows the cross-section of anoiltank, its dimensions arelength a=0、6m, width b=0、4m,heightH=0、5m、The diameter of nozzle is d=0、05m, height h=0、08m、Oil fillsto the upper edge of thetank,find:(1)Ifonlythe thermal expansioncoefficientv=6、510-41/K of the oil tankis considered, wh at is thevolume Fig、1-10Problem1、4of oil spilledfrom the tank when the temperature ofoil increases from t1=-200C to t2=200C?(2)If thelinear expansion coefficientl=1、210-51/K of theoiltank is considered, what is the result inthiscase?图1-10为一油箱横截面,其尺寸为长a=0、6m、宽b=0、4m、高H=0、5m,油嘴直径d=0、05m,高h=0、08m。

由装到齐油箱得上壁,求:(1)如果只考虑油液得热膨胀系数v=6、510-41/K时,油液从t1=-200C上升到t2=200C时,油箱中有多少体积得油溢出?(2)如果还考虑油箱得线膨胀系数l=1、210-51/K,这时得情况如何?((1)2、49210-3m3(2)2、3210-3m3)1、5 A metallic sleeveglidesdown byselfweight, as shown in Fig、1-11、Oilof =310-5m2/sand=850kg/m3fills between the sleeve and spindle、The innerdiameterofthe sleeveisD=102mm, theouter diameter ofthe spindle is d=100mm,sleeve length is L=250mm,itsweightis 100N、Find the maximum velocity when the sleeve glides downfreely (neglect air resistance)、Fig、1-11 Problem 1、5 有一金属套由于自重沿垂直轴下滑,如图1-11所示。

轴与套间充满了=310-5m2/s、=850kg/m3得油液。

套得内径D=102mm,轴得外径d=100mm,套长L=250mm,套重100N。

试求套筒自由下滑时得最大速度为多少(不计空气阻力)。

(50 m/s)1、6The velocity distribution for flowof kerosene at 200C(=410-3N s/m2)betweentwowalls is given byu=1000y(0、01-y) m/s, where y is measuredinmetersand the spacing between the walls is 1 cm、Plotthe velocity distributionand determ inetheshear stress atthe walls、在200C时,煤油(=410-3N s/m2)在两壁面间流动得速度分布由u=1000y(0、01-y) m/s确定,式中y得单位为m,壁面间距为1cm。

画出速度分布图,并确定壁面上得剪应力。

(410-2Pa)1、7 As shown inFig、1-12,the velocity distributionforviscous flow between stationaryplatesis given asfollows:Fig、1-12Problem1、7If glycerinis flowing(T=200C)andthepressure gradient dp/dxis 1、6kN/m3,what is the velocityand shear stress a tadistance of12 mm fromthewall if thespacing By is 5、0 c m? What are the shearstressand velocityatthewall?如图1-12所示,两固定平板间粘性流动得速度分布由给出。

如果流体为甘油(T=200C)且压强梯度dp/dx为1、6kN/m3,间距By为5、0 cm,距平板12mm处得速度与剪应力为多少?平板处得剪应力与速度为多少?(u12=0、59m/s;τ12=20、8N/m2;u0=0;τ0=40、4N/m2)1.8What isthe ratio of the dynamic viscosityof airto thatofwaterat standard pressureand T=200C? Whatis the ratioof thekinematic viscosity ofairto waterfor thesame con ditions?在标准大气压、T=200C时,空气与水得动力粘度之比为多少?同样条件下它们得运动粘度之比又为多少?(A/W=0、0018;A/W=15、1)1、9 The device shown in Fig、1-13 consistsof adisk thatis rotatedbya shaft、The disk ispositioned very close to asolidboundary、Between thedisk and boundary is viscous oil、(1)If the disk is rotatedatarate of1rad/s,what will be the ratioof the shear stress in the oil atr=2cm toFig、1-13Problem1、9the shear stress atr=3cm?(2)If the rate of rotationis 2 rad/s, what isthe speed of oil incontactwith the disk at r=3cm?(3)If theoil viscosity is 0、01Ns/m2andthespacing y is2mm, whatis theshear stressforthecondition not ed in (b)?图1-13所示装置由绕一根轴旋转得圆盘构成。

圆盘放置在与固体边界很近得位置。

圆盘与边界间为粘性油。

(1)如果圆盘得旋转速率为1 rad/s,问半径为r=2cm与r=3cm处得剪应力之比为多少?(2)如果旋转速率为2rad/s,r=3cm处与圆盘接触得油层得速度为多少?(3)如果油得粘度为0、01Ns/m2、且间距y为2mm,(b)情况下得剪应力为多少?((1) 2:3;(2)6cm/s;(3)0、3Pa)1、10 Asshownin Fig、1-14,a conerotatesaround its vertical centeraxis at uniform velocity、The gap between two conesis=1mm、It filled with lubricant which μ=0、1Pas、In theFigure, R=0、3m, H=0、5m,Fig、1-14Problem1、10=16 rad/s、Whatisthemoment needed torotatethecon e?如图1-14所示,一圆锥体绕竖直中心轴等速旋转,锥体与固定得外锥体之间得隙缝=1mm,其中充满μ=0、1Pas得润滑油。

已知锥体顶面半径R=0、3m,锥体高度H=0、5m,当旋转角速度=16 rad/s 时,求所需要得旋转力矩。

(39、6Nm)2、1 Twopressure gauges arelocated onthe side of a tankthat is filledwith oil、One gauge at anelevation of 48m above ground level reads 347kPa、Another at elevation 2、2m reads 57、5 kPa、Calculate the specific weight and density of the oil、两个测压计位于一充满油得油箱得一侧。

一个测压计高于地面得位置高度为48m,读数57、5 kPa。

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