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Pcpe 1\ic I NEW SCHEME I ME45Reg . No. U-'----'---L-'- [ . - ~ . . 1 - - l - . . L - . . J

Fourth Semester B.E. Degree Examination, January/February 2006Mechan ical Engineering

Fluid MechanicsJim 3 hrs! (Max. Marks: 100

Note: A n ~ w . , any FIVE fuN questions.1. Give reasons f{)r the following

i) The mlniscus of water Is concave upwards wt111e lhe rniniscus of mereury ISconvex upwards.u) V scos!ty of liquids decrease on heating whereas viscosity at goses Increaseon 11eating.i) Rain drops and tiny dew drops ore spherical 1r. ~ 1 c p e . (6 Marks)

(b) 1wo !lites o f petrol weighs ldN. Calculate specific weigh t mass densliy, specificvolume and specific graving of petrol (2 Marko) Derrve tne expressions for surface tensoon on a lqu-d dropiet and soap bubble.(4 Marko}(dl A vortrcolgap 22mmW1de o f infinite extension con lalns a fluid ofviscosity 2.0 N.S/m2end specific gravity 0 9. A metallic p lo le J .2m x 1.2'171 x 0.2cm Is to be lifted upwilh a constant velocity ofO.lS m/s. lnrougnlhe gop. 1flhe p la te 1s assumed to beoi 11o middle of the gap. determine the fcrcc roqt..ired The weight of th e plate

2. nt 'he monomoter contains'n;;l

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Poge No . 2 ME45(c) An inclined rectangular sluice gcte AB 11inged at A or size l .2m x 1m. os show .In the figure Is t o l l e to control ltle discharge of wato1 Deterrnlne tl1o normalIoree to be oppl1ed a t B to open the gate (6 Marks)

" .

4. (a) Explain Lagrangian and Eulerian approaches of fluid flow study.(b) Define

I) Path lineIii) Streak t.ne

/1) Stream linetv) Streak tube

(6 Marks)(4 Marks)

(c) Does the stream function if> = 2:ey represent a physically possible ffow? If so.determine ff'le velocity ot point (I 1)andsketch the stream function Atso determ1nethe velocity potencial funcrion. (1 0 Marks)

5. (a) lhe pressure difference t:.P 1n o pipe of diameter D and length L due lo rurbulent now depends on the velocity V, v1scoslty ,,, density p and roughness Kusing Buckingham's 11 theorem. obtain on expression for tlP In lhe form ofDorcy-Welsboch equation (10 Marks)

(b ) Stole Bernoulli's theorem for an Incompressible flow stating all tho assump tionsWrite Bernoulli's equonon applied between 2 Points on a stream ~ n e 10 on Idealnuld and 1n a real fluid, (4 Marks)

(c) A pipe of 300mm diameter conveying 300 litres/sec of water has a nghl angledbend In a horizonrol plano. Find the resultant force exerted on the bend If thepressllfe at Inlet and ou ttol of ltle bend ore 245.25kPo and 235.44 kPo respectively.

(6 Marks)6. (a) Stole lt lo working p rincip le of pilo t tube. (2 Marks)

(b) A horiZontal venturmeter with 30cm diameter inlet and 10Cm throat JS used formeasuring the flow of wclor through o pipeline. If the pressure in pipe IS 150 kPoand the vacuum pressure at the throat Is 40cm of mercury. cotcufate ttw roteof foow Assume 57' or (Jolerenhal head is lost between the prpe rnoin o11d rhethroat section r1nd the s c h a r ~ J O coefflcrent Take specific woluht of w

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rVIC . .O7. (a) Explain ~ " l e concept ol the total energy line an d hydraulic grcdlont linn foi fluid

flow (4 Marks)(b ) Two p;pns of dlomeler 0 and a With equal ienglh L Cl iOconsdeted If the p ipes ore

(Wonged In parallel. the oss of haoo tor OithCr ptpe when a tolol quantity of waterliows through them Is h If ft)a pipes ore arranged In SOiies and the some quonlrtyQ !lows through 1hom lho Joss of hood is H. If d 0.5D. find the percentageot total ow through eocn pipe whon p laced In parallel and the ratio of H to h'\Jeglucl minor lossos and ossume fnc llon coefticionts to be consronls. (10 Ma1ksl

(c) F.nn th diSplacement II iCkness and momentum thickness(1tstr 01. !too in the boundary Ioyer grven by 1'j 2(!) (f)2

(a) Explain lrte terms .i) tric lion drag 11) prosswe drag in) :itt

for the velocity(6 Marks)

(6 Marks}(b) Descnbo the Mach cone and Mach angle wi lh the help of neat sl