West Bengal Institute of Technology (WBIT) 2008-2nd Sem B.Tech Computer Science and Engineering Computer Science - Thermodynamics & Fluid Mechanics - Question Paper
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" INGIFTBE-IKH J & MANAGEMENT EXAMINAT' O l - 2008
I Full Marks : 70
Time : 3 Hours )
GROUP - A (M ultiple Choice Type Questions}
10 x 1 * 10
C hjcse the ccn'ccc alternatives for the following :
ij Which Ci tiiC follow mg is an intensive thermodyn. or u property ?
a) VtivuTja b) Temperature
c) M;:ss d) Energy.
ii) For i ;i lii cv. rsible process, change in entropy is
a} greater than dQ/T b) less than dQ/T
c) zero d) equal to cQ/T,
ill) Durii;g ihrouiing, which of the following quantity dec... not change ?
a) Internal energy b) Entrc-jy
c) Prussia e d) Enthalpy
iv)
Woi k di aic in a free expansion is .
a) Positive b) Negatm*
c) Zero d) Maxa.-Um.
A cycle v/ith constant volume heat addition and constant volume heat rejectic i is
v)
Diesel cycle
vl)
b)
c)
d)
b)
c) Joule cycle d) Rankuie cycle,
Triple point of a pure substance is a point at which a) liquid and vapour coexist so: id and vapour coexist dOiid u.a liquid coexist all tiixee phases coexist.
a) , Otio vycle
H-222833 (3)
vii) BanouL s equation deals with the conservation of
* : ' ' * ' ' * -VI -
Ci Energy ;d) Work,
C jntinuity aquation is based on the principle of conservation of 4 Mass b) Momentum
o) Energy , d)
' o * * ? A . -
A. Pitot tube is used for measuring
' .. v ..v.4 i : A.I.' .
tj rStacc: of fluid a)
c) Density 6f fluid d)
Dynamic viscosity has dimensions of
a) MWf2 *?)
c) ML1T-2 ti)
GROUP - a ( Short Answer Type Qutetim* ) Answer any three of the followin '.
vtL
r
Entropy.
VelcMy offtuid Viscosity of fluid.
c :2 j.
iT-i
M- i L- i T-i.
3 Y
2, Statw the first law of thermodynamics for a closed system undergoing e cycL 15
' p-i'ccess.. . ., . . .
3, l&rplain thrmodynunic eqi
4, riic fluid flow is given by V= x2 yi + y 2z - ( 2 xyz + yz 2 ) k. Show that tliis 3 a > oi possible steady incompressible flow. Calculate ilie velocity ano acceltr x lo*.
1 2, 1, 3 ).
5, Di'&w a block digram of vapour compression xeirigeration cycle and also l: c v to responding P-V and T-S plots.
b. D .iive B raoullis equation form first priiicipies, stating ti e assumptions.
V. ii plain PMl1-1 and PMM-2.
GROUP-C (Long Answer Type Questions)
Answer any three of the following, 3 x 15 - *5
8. a) Which is a more effective way of increasing the efUciency of a Carnot engine to increase source temperatue ( T y ), keeping sins temperature ( T% ) constant or
to decrease T2 keeping Tr constant.
b) State Clausius inequality.
c) A mass of m kg of liquid ( specific heat * Cp) at a temperature T j is mixed with an equai iwuss of the same liquid at a temperature T2 ( Tj > Tu ) and the system is thermally insulated. Show that the entropy charge of th-.i vaJverse is given by
i , + T o 2mC I i --1
p pf T
\ 1 1 1 2 )
and prove that this is necessarily positive. 3 + 2 + 10
9. a) Derive the expression for efficiency of an Otto cycle and show the process on
p-V and T-s planes.
b) For the same compression ratio, explain why the efficiency of Otto cycle is greater than that of Diesel cycle.
c) In a diesai engine the compression ratio is 13 : 1 and fuel is cut off at 8% of f h stroke. Find the air standard efficiency of the engine. Take y for ir 1.4
. . 5 + 3 + 2 + 5
10. a) A gas occupies 0.024 m3 at 700 kPa and 95C, Ic is expanded in the non-flow
process according to the law pv 12 = constant to a pressure of 70 kPa after which it is heated at a constant pressure back to its original temperature. Sketch the process on the p-V and T-s diagrams and calculate for the whole process the work done and the heat transferred. Take Cp =1.047 and C u = 0.775 kJ/kg K for the gas.
b) A rigici closed tank of volume 3m3 contains 5 kg of wet l e un at a pressure oS 200 kPa The tank is heated until the steam become* dry saturated. Determine the pressure and the heat transfer to the tank. 8 t 7
C8/B T A/8 JL i/ME-201/08 6
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11. it) Write the steady flow eni&rgyySLWon for a singlfc ateam entering and sUgie
sUaia-leaving a control tae varum terms.
h) ;vt the inlet to a nozzle, C5, enthalpy c: t.e ;lujd pacing is 3000 kJ/tg .uva velocity is 60 m/s. At the exit, the euiaalpy is 2762 teJ/kg. The m/iz-I- ti ho/teontal andthereis negligible heatlos
I) Find the velocity at tMfe nozzle exit
ii) The inlet area is 0.1 m 2 aind the siieciflc volume tit inle H 187 if. Find the mass flow rate. ' ,
ill) If the specific volume at the nozzle exit is 0.498 m 3/kg, find :: *> e-nt urge, of the nozzle.
12. u) Derive Euler's equation, of motion along a gtreamliae
b) A venturimeter has inlet sund throat diameters of 300 mm and 150 nnr. V /.-flows through it at the rate of O.Q65ni3/ and the differential gauge is defies.. by 1.2 m. The specific gravity of the ra&iiometric liquid is 1.6. Determine ih*; coefficient of discharge of the venturimeter.
o) A Jet of water from a 25 mm diameter nozzle is directed vertically upw rds Assuming that the jet remains circular Sind neglecting any loss of energy, wlu will be the diameter of the jet at a point 4.5 m above the nozzle, if the jet U \
&e nozzle with a velocity of 12 m/s ?' ; 5 t :'* y
13. a) A circular disk of diameter d is slowvy rotated la a liquid of viscosity at a n'iu
distance h from a fixed surface. Derive an expression for the lorqu necessary to maintain an angular velocity a),
b) Distinguish between the follow :
laminar and turbulent flow
4
it) compressible and incompressible fluid
ia) static pressure and stagnation pressure
iv) viscous and inviscid fluid, 7 + 3
14, Write short notes on any three of the following : 3x5
a) Pitot tube , *
L] Orifice meter
c) Point function and path function
aj S-reamline. streakline and pathline.
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(jt'32?3i3 W\ K
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