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! IIJTIJFourth Semester B.E. Degree Ex:unination, Dcc.08/ .Jan .0

Fluid MechanicsMax. Ma

f'iote : I. Answer Oil) ' FlVEfu/1 questio11s.2. NtJ tahles, charts, data book are permitted.

a. Fxpluiu c o m p r c ~ s i b i l i t y Derive :m equation for compressibility lor an ideal gisentropic p r o c e s ~ (0

b. A n:locity distnbut10n for flow over a flat plate IS gtven by u = y - y ~ i whereveluclly m m!s at a d1stance of y meters abo\c tho: plate. determine the sheary 0.09 m.:tre. Talo.c dynamic viscosity of the lluid as 8 poise. (O

c. A cnrillary tube of dianu:tcr 1.5 nun b dipped in i) water ii) mercury. Find the rise J(tr each case.

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a. Explain i) Stream line ii) Path line iii) Streak line.b. Do the following velocity component represent physically possible flow?i) u=x 2 H.2+5;v=y 2 +z2 ;w=4xyz ii) U=5xi+(3y+ty 2)i

Y3 2 x3 y2iii) u= - +2x x2y; v = xy -zy- tv) u = xy; v = x 23 3 2

(06 ll&(08 M

c. Plot the flow field defined by = x2 - y 2 , calculate the velocity at a point P(l, 2).(06 Ma

a. Prmc that the supersonic air drag FD of a rocket is given by ,:0 , p ~ V . where L is the length t)f rocket, V its velocity, P shock angle, p Air den)l - Viscosity of air. and K bulk modulus of air. (08 M

b. Explain Raleigh ' s method and similitude. (06 Mc. A ptpc carT)ing crude oil of sp.gr 0.84 is of 25 em diameter at section I and 50diameter at section 2. The rate of flow is 450 Ips. Section I is at an dcvation of 2above the section 2. If the pressures of 11uid at the two sections arc 55 kPa at section I320 kPa at section 2. find the direction of flow and head loss between the sections.

(06 \ la. Sht)W that for n venturi meter.;\;\Q- Cd r: 21 2 ~ 2 g l l with usual nutmion.\ /At - / \ !

(OH l \ l

b. 5000 Ips of petrol of sp.gr 0.79 f l O \ \ ~ through a IS em diameter by 7.5 em dtamvertical ventunmeter. The flow is in the upward direction, Cd of the meter is 0.98.leng01 of the ~ : u n v e r g i n g cone of the 1111.:tcr is 30 em. Compute the pressure differbetween the inlet and throat sections and the deflection that would be recordedmercury differential U-tubc manometer connected between these sections. (08 .\1

c. Explain i) Energy line ii) I lydraulic gradient line. ( 0 ~ Ma. For a laminar tlow through a circular pipe. derive Hagen-Poiscuillc equation for head

. . . . 32tuLdu't lncuon gtvcn b) h = (OH Illr gD2b. Expluin Coucttc llow. (04 Mac. Carbon dioxide flows through a diffuser. The pressure velocity and temperature

sectton where the area of section is 50 cm 2 arc 85 kPa (abs). 250 m/s and -sc (268What ~ h o u l d be the area at another down stream section to give a pressure of 120(abs)'l What is the temperature at this section? Calculate the Mach numbers at the sections. Assume isentropic flow with R- 287 J/kgK andy= 1.28. (08 M8 a. Fxplain i) Boundary layer thickness o il) Displacement thickness li* iii) \tomenthickness 0. (06 M o rb. If the velocity prolile in a laminar boundary layer is approximated by paraboltc prolile,

\!.'here u is the velocity at y and u-+v as y-+S. Calculate the d i ~ p l a c e m e n t th1cknessthe momennun thickness. (06 Mac. Calculate the drag and the power required to tow a smooth flat plate 2 m wide 20 m