武汉大学流体机械期末考试历年试卷

武汉大学流体机械期末考试历年试卷(Examinationpapersforthe

finalexaminationoffluidmachineryinwuhanuniversity)

Collegeofdynamicsandmechanicsofwuhanuniversity

Collegeofdynamicsandmechanics,wuhanuniversity,wuhan

university

''Fluidmachineryandengineering”,wuhanuniversity,schoolof

dynamicandmechanicalengineering,2006-thefinal

examination(examA)classoflastterm(exampaperA):student

number:name:gradeone,two,three,fourandfive

Scorea

Onebyone

A,

，，，

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Fillintheblanks

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Everyemptyempty

Everyempty1minute,

hoping

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1.Fluidmachineryreferstofluid

Withmechanicalequipment,pressenergy

Thetransmissiondirectionofthefluidcanbedividedinto

machineandmachine.

2.Flowofwaterturbinereferstounittimeflowthroughthe

turbine

Theamountofsectionfluid.3.Axialflowlineisthe

intersectionofsurfaceandsurface.4.RelativeflowAngle

betaistheAnglebetweenrelativevelocityandvelocity.

5.Absolutespeedcanbebrokendowninto

Speedandspeed.

6.Thedensityofthecascadeis

Andtheratioofthe.

7.Whenestablishingthebasicequationsofvanefluidmachines,

fourbasicassumptionsareintroduced,andthefourbasic

hypothesesare,,and,respectively

And.

8.Therearethreesidesofthevelocitytriangleoftheblade

typefluidmechanism,andthesethreesidescorrespondtothree

vectors

It'sthesamethingasthevector.

Thesecond

Second,

Singlechoicequestion

Asinglechoicequestion

Singleitemselection(

((

(eachitem

Everylittleproblem

Twopointsperproblem

hoping

Points,

,，

,atotalof

Atotalofatotalof

Atotalof20points

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1.TheflowrateofacertainwaterpumpisQ,andtheleakage

flowrateisQ,andtheflowintheimpellerisTQ,andits

volumetricefficiencyQetais(

).

A.Q

QQ?;B.TQ

Q;C.Q

Q.1.()lossofthedisccausedbyfrictionbetweenthefluid

andtherotatingimpeller.

2.(

Theconcavesideofthebladeistheworkingfaceandtheconvex

surfaceistheback.

3.(

Thepressureontheworksurfaceisstrongerthanthepressure

ontheback.

4.(

Therotationdirectionofaxialvortexesinafinitenumberof

bladeslotsisoppositetothatoftheimpeller.

5.(

)similarfluidmachines,whichareequivalenttorotational

speed;Inturn,theschoolofdynamicsandmechanicsofwuhan

university,whichisequivalenttotherotationspeed

Collegeofdynamicsandmechanics,wuhanuniversity,wuhan

university

''Fluidmachineryandengineering”,wuhanuniversity,schoolof

dynamicandmechanicalengineering,2006-thefinal

examination(examinationpaperB)classof2007:studentno.:

name:gradeone,two,three,fourandfive

Scorea

Onebyone

A,

，，，

Andfillsupthetopic

Fillintheblanks

Fillsupthetopic,

((

(everyempty

Everyemptyempty

Everyempty1minute,

hoping

Points,

，，

,atotalof

Atotalofatotalof

Atotalof20points

hoping

Points)

))

1.Waterflowattheunitweightbeforeandafterthewheel

Whetheritisequal,bladetypefluidmachineisok

It'sdividedintocounter-attack.2.Thecounter-typefluid

machinecanbedividedinto

Andthreekinds

Type.

3.Theflowofthemachinereferstotheflowthroughit

Theflowofthesection,theflowoftheoriginalmotivemeans

Theflowofthecrosssection.

4.BladeplacementAngley

Betaisthelineatanypointinthebladethat'sgoinginthe

oppositedirection

TheAngle.Whenthefluidismovingalongthebladeprofile

(i.e.

Alphabeta=y.

5.Thedirectionoftheaxialvortexmotionisinthedirection

oftheimpellerrotation

Itis.

6.Whentheratiobetweenthemodelandtheprototypeisscaled

upordown,thepowerofthemodelcanbemade

1=sH,powerkW1=sP,therotatingspeedofthemodelis

called.

Thewingtypemidline(skeleton1ineorboneline)isthe

airfoil

Intheattachment.

8.Thecorrespondingpointsofeachwinginthecascadeare

called

Itis.

9.Reaction?Theintervalis[

10,whenreaction?When=0.5,forblade;

Whenthereactionis?>0.5,for

Leafblade;Reaction?For<0.5

Leafblade.

10.ImpactAnglereferstoflow

TheAnglebetweenthespeedandthebladeprofileattheinlet.

11.Therearetwoformsoftheimpellerflowchart,whichare

projectedandprojected.

Thesecond

Second,

，，，

Singlechoicequestion

Asinglechoicequestion

Singleitemselection(

((

(eachitem

Everylittleproblem

Twopointsperproblem

hoping

Points,

,atotalof

Atotalofatotalof

Atotalof20points

hoping

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1.Whenawaterturbineworks,itsinletflowispQ,andthe

outletflowissQ,theflowintheimpeller

ThevolumeisTQ,anditsvolumeefficiencyisq

Etais().

Amypolumbo

TQ

Q；

P-

sQ

Q;

C.T

sQ

Q

Itis.

2.TheheadofawaterpumpisH,andthetheoryofthework

oftheimpellerontheflowofwateristheTH,theflowinthe

pump

Lossofh

?,theflowefficiencyhetais().

A.

H.

HT.

B.TH

H.

C.

)(hH

HT

T?

+

Itis.

3.ShaftpowerP(

).

A.theoutputpowerofAgenerator;B.Istheoutputworkof

thewaterturbine

Rate;

CisequaltogQHrho.

4.Thesign"p'oftheimpeller'shighpressuresideindicates

thatthe"s'ofthelowpressuresideindicatesthatgis

accelerationofgravity

Degree,rhoisfluiddensity,dp

g

Hp

s.

1stJ=uprho

1,infinityTHisthetotalenergyhead,andit'sfor

compressibleandno

Compressiblefluid,thereactiondegreeofbladetypefluid

machinerycanbeexpressedas().

A.up

up

st

THH.B.upup?TstH

H.

1;C.up

up

T

stH

H.

5.Reactionofvanetypefluidmachinery5

0=?,therotorbladeofthemachineis()

Leafblade.

A.Forwardbending;B.Radial;C.backbend.6.Theunitspeed

ofwaterturbineislln().A.H

ND;

B.H

ND;

c.

D

N.7.By4/5h

ThePn

Ns=knowthatawaterturbineworksatacertainspeed,and

asitsflowdecreases,

It'sgoingtobethespeedofsn.

A.increase;B.Decrease;C.constant.

8.Astheflowofthepumpincreases,theresidualamountof

thecavitationisrh

?The0.

A.increase;B.C.Uncertaintyaboutitstrends.

9.Cavitationcoefficientofwaterturbine

Hr?

Sigmaandsigma.

A.thesuctiondeviceofAturbineisconcerned;

B.Geometricparametersandmovementparametersofturbine

impellerinlet;

C.Geometricparametersandmovementparametersofturbine

impellerexits.

10.Onlyreducetherotationspeedofcentrifugalpump.

(QfH=curve().

A.B.Lowerleft;C.Nodisplacementoccurs.

three

Threethree

Three,

Trueorfalse,

I'mgoingtodoit

Trueorfalse,

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(correcttype)

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〃XV〃and1〃x〃

〃x〃，

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)

1.(

Disklossisanexternalmechanicalloss.

2.(

Theconvexsurfaceoftheleavesistheworkingfaceandthe

concavesurfaceistheback.

3.(

Thepressureontheworksurfaceissmallerthanthepressure

ontheback.

4.(

Therotationdirectionofaxialvortexesinafinitenumberof

bladeslotsisoppositetothatoftheimpeller.

5.(

)similarfluidmachines,whichareequivalenttorotational

speed;Inturn,afluidmachinethatisequivalenttoarotating

speed,

Theperformanceisnotnecessarilysimilar.

6.(

)thelargerthespeedsn,thewidertheefficientarea.

7.(

)thecavitationratioislargerthanthespeedC,andits

anti-cavitationperformanceisbetter.

8.(

)allbladetypefluidmachinery,whenitspositionisgreater

thantheAngleofflow,theAngleofimpactispositive.

9.(

)thethrustAngleofallbladetypefluidmachineryisthe

relativeflowAngleoftheinletoftheblade

Poor.10.(

)relativeparameters,dimensionlessparametersandunit

parametersarerelativetothewaterpumpsdrawnbyvariables

Thecurveoftheenergycurve,thedimensionlesscharacteristic

curveofthefanandthecomprehensivecharacteristiccurveof

theturbinearechangedwiththespeedofthespeedofrotation,

four

Theunevenness

Four,

Short-answerquestions,

Shortanswerquestions

Short-answerquestions,

((

(eachitem

Everylittleproblem

Tenpointsforeverylittlequestion

hoping

Points,

，，

,atotalof

Atotalofatotalof

Atotalof20points

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)

Whydowaterturbineshavetailpipes?

2.Thespecificspeedofthefluidmachineshouldbeuniqueas

acomprehensivesimilaritytest.Pleasespecifytherelevant

regulations.Twoturbinesaresimilar,aretheyequaltospeed?

Why?

five

4

Five,

，，，

,calculationproblem

Solet'sdothemath

Math(

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15pointsforeverylittlequestion

hoping

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)

Waterturbineflowvq=30m3/s

Theinletpressuregaugeofthehydraulicturbineis510234.3

x=dp

N/m2,thewaterturbineexportvacuumgaugereads510

392.0x=sp

N/m2,thedifferencebetweenthetwotablecentersisZ

?=3m,thediameteroftheintake(pressuregauge)andthe

drainpipe(thevacuumgauge)arethesameasthegenerator

ThepowermeterreadingisdP

=9200kW,thegeneratorefficiencyis92

.0=deta,findtheaxisoftheturbine

Efficiencyofpower,inputpowerandwaterturbine(ignore

transmissionlossbetweenturbineandgenerator,9800

Rho=gN/m3).

2.Pump20atatmosphericpressure?Croomtemperatureclear

water(m

24.0=

g

Pvrho),weknowthatthepumpis960

=nr/min,thehydrauliclossofwaterabsorptionpipelineis

0.6m,andthetestisinwuhan(m32.10=

g

Parho)andLhasa

(m

64.6=

g

pa

Rho)theallowableheightofthepumpinbothplaces

Therhoftheprototypepump

?Bysize

Themodelpumpiscalculatedbythemodelpump,andthespeed

ofthemodelpumpis1450=MNR/min,m

1.2=?RMH

,take

Thecavitationsafetymarginoftheprototypepumpis5

0=Km).

Dean:theanswertotheprincipleoffluidmechanicsin2006

Avolume

1.Fillintheblanks

1.Originalworkofenergycarrierofworkmedium

2,import

3,axialflow

Circumferentialreaction

5.Thecircumferenceoftheaxialplane

6,thelengthofthestring

7.Axisymmetricconstantflow;Theflowisindependentofflow;

Thebladeisinfiniteandinfinite;Idealfluid(bladeinfinite

numberofbladesinfiniteidealfluidconstantflow

unpressurized)

8.Thevelocityoftheabsolutevelocityrelativetothe

velocity(implicationvelocity)

2.Singleitemselection

1,B

2,A3,B4,B5,A6,A7,D8,C9,C10,B3,1

,x

2,x

3,x

4,squareroot

5,squareroot

6,squareroot

7,x

8x.

9,x,

10,x

4.Shortanswer1,

1)request:602

The2d

n

UPI=,(determinethebaseofthetriangle);

2)2

2bybetabeta=,(assumingthattherelativeflowAngleisequal

tothesettingAngleofthebladeundertheinfinitenumberof

assumedconditions

-identifyanAngleatthebottomofthetriangle;3)

calculation222

2bits

PIDb

Q

Computedtomography(cT)

M=,(determinetheheightofthetriangle).

Sothreeconditionsareavailable,triangleisdetermined.

2,

1)Strouhal,asimilarrule,counts0

0

0t

c

L

Sr=equal:

mm

m

PP

Pt

c

L

tc

LO

0

0

00

0=;m

m

m

m

p

p

p

Thepn

D

Q

D

n

D

Q

D

one

12

2

2

2

2

2=

Sothereare:?

?

?

?

?

?

?

?

?

?

?

?

?

9

?

9

=m.

P

m

P

m

Thepn

n

D

D

Q

Q3

2

2

2)eulernumber2bysimilarcriteria

2u

P

TheEu

Rho=equal:22

2

22

2mm

m

PP

Thepn

D

gH

nD

gH

=thenthereare:2

2

2

2?

?

?

?

?

?

9

?

?

?

?

?

9

9

9

9

=m.

P

m

P

m

Thepn

n

D

D

H.

H5,calculation

1,9

89.

8.18

98.1690

50

36.114504

/34/3materialmaterial==

H.

qn

nv

Q0634

.0

50

17.3

9

H.

HCR

cr

Columnofwaterandpumpinletsectionw

ss

g

eh

g

Thecp

H.

P

?+=?22gammagamma

Definitionofcavitationallowance[]口63.6

3.06.0)5.017.3(10

22=

?++?二

?+??=

?+?=

?十二？gamma

gamma

Gammagammagammagammav

W.

e

g

v

wg

evss

ap

hh

P

H.

P

hH

PP

g

Thecp

H.

2,1.

loEEH?=theh

g

P

Z

g

V

g

p

ZEo

Oo?

=++=rho

Alpha.

Rho22

00into-

hZ

g

v

g

p

ZEiii

li?

++==

22alpha.

Rho25

3

9.811000

1000196.2

2=+

x

X

?+?+

+

?

，，

=into

Thehh

g

P

ZZHrho(2H.

g

P

g

P

g

p

g

p

Hi

o

10+

?=rho

rho

Rhorho6

3138.9256.68=x++==gHppiokPa

B

1.Fillintheblanks

1.Pressurepotentialenergyimpact

2.Radialflowtypeaxialflowtype

3.Exportimport

4.Tangentcircumference

5,

6.Specificspeed

Thecircleoftheinnercircle

8.Cascadeline(frontalline)

9.