Hello, here I am providing you the solved paper of the ISRO for the Mechanical field as under:

1. The critical value of Reynolds number for transition from laminar to turbulent boundary layer in external flows is taken as

(a) 2300 - Answer
(b) 4000
(c) 5 x 105
(d) 3 X 106
(Expl : Critical value of Reynolds number for transition from laminar to turbulant layer in external flows is taken as 2300.)

2. The by-pass factor of single coil in an air-conditioner is 0.7. The by-pass factor, if three such cooling coils with the same appartus dew point are kept one behind the other will be
(a) 0.210
(b) 0.292
(c) 0.343 - Answer
(d) 0.412

3. Which one of the following statements is true for air conditioning duct design ?
(a) Static regain method is used, when the duct work is extensive, total pressure drop is low and flow is balanced
(b) Static regain method is used, when the duct work is extensive, total pressure drop is high and flow is unbalanced
(c) Equal friction method is used, when the duct work is extensive, total pressure drop is low and flow is balanced - Answer
(d) Equal friction method is used, when duct work is extensive, total pressure drop is low and flow is unbalanced.

4. For an-conditioned space, RTH = 100 kW; RSHF = 0.75, volume flow rate is equal to 100 m3/minute and indoor design specific humidity is 0.01 kg/(kg of dry air). The specific humidity of supply air is
(a) 0.010
(b) 0.0075
(c) 0.005 - Answer
(d) 0.0025

5. For an air-conditioning system, the outdoor and indoor design dry bulb temperature are 45o C and 25oC respectively. The space to be air-conditioned is 20 m X 30m X 5 m and infiltration is estimated to be one air change. If the density and specific heat of air are 1.2 (kg of dry air)/m3 and 1.02 kJ/(Kg of dry air)oC, then the sensible heat load due to infiltration is nearly
(a) 122.4 kW
(b) 61.2 kW
(c) 12.24 kW
(d) 20.4 kW - Answer

6. Match List -I and List ii and select the correct answer using the codes given below the lists:
(hm - mass transfer coefficient, D - molecular diffusion coefficient
L - characteristic length dimension k - thermal conductivity , p - density
Cp - specific heat at constant pressure u - dynamic viscosity )


Codes :
A B C D
(a) 4 3 2 1
(b) 3 4 2 1 - Ans
(c) 4 3 1 2
(d) 3 4 1 2

7. In the operation of four-stroke diesel engines, the term 'squish' refers to the
(a) injection of fuel ! in the precombustion chamber - Ans
(b) discharge of gases from the precombustion chamber
(c) entry of air into the combustion chamber
(d) stripping of fuel from the core

8. Consider the following statements regarding the advantages of fuel injection over carburetion in S.I. engines :
1. Higher power output and increased volumetric efficiency
2. Simple and inexpensive injection equipment
3. Longer life of injection equipment
4. Less knocking and reduced tendency for back-fire
Select the correct answer using the codes given below :
Codes :
(a) 1, 2 and 3
(b) 1, 2 and 4
(c) 2 and 3
(d) 1 and 4 - Ans

9. Match List -I(Performance Parameter Y) with List-II (Curves labelled 1,2,3,4 and 5 BHP vs. Y) regarding a C.I. engine run at constant speed and select the correct answer using the codes given below the lists:


Codes :
A B C D
(a) 5 3 4 2 - Ans
(b) 1 3 4 2
(c) 5 4 2 3
(d) 1 4 2 3

10. Match List -I with List -II(Use) and select the correct answer using the codes given below the list:
List - I List - II
A. Supercharging 1. Multicylinder engine
B. Morse test 2. C.I. engine
C. Heterogeneous combustion 3. Calorific value
D. Ignition quality of petrol 4. Aircraft engine
5. Octane number
6. Single cylinder S.I. engine

Codes :
A B C D
(a) 4 1 2 5 - Ans
(b) 6 3 2 5
(c) 6 1 5 2
(d) 4 3 5 2

11. With reference to Turbojet and Rocker engines, consider the following statements :
1. Efficiency of Rocket engines is higher than that of Jet engines
2. Exit velocities of exhaust gases in Rocker engines are much higher than those in Jet engines
3. Stagnation conditions exist at the combustion chamber in Rocket engines
4. Rocket engines are air-breathing engines
Which of these statements are correct ?
(a) 1 and 2 - Ans
(b) 1, 3 and 4
(c) 2,3 and 4
(d) 1, 2 and 3

12. With respect to I.C. engine emission, consider the following statements :
1. Evaporative emissions have no carbon monoxide and oxides of nitrogen
2. Blow by emission are essentially carbon monoxide and suspended particulate matter
3. Exhaust emissions contain 100% of carbon monoxide , 100 % of oxides of nitrogen and around 50-55% of hydrocarbons emitted by the engine.
4. There are no suspended particulates in the exhaust.
Of these statements
(a) 1 and 4 are correct
(b) 1 and 3 are correct
(c) 2 and 3 are correct - Ans
(d) 1,2,3 and 4 are correct

13. A hydrocarbon fuel was burnt with air and the Orsat analysis of the dry products of combustion yielded the following data :
__________________________________________________ __
Initial volume of dry gas sample --- 100 cc
Volume after absorption in pipette 1 containing --- 89 cc
potassium hydroxide solution
Volume after absorption in pipette 2 containing --- 84 cc
solution of pyrogallic acid and potassium hydroxide
Volume after absorption in pipette 3 containing --- 82 cc
cuprous chloride solution
__________________________________________________ __
The percentage (by volume) of CO2 in the dry product was
(a) 2%
(b) 5%
(c) 11% - Ans
(d) 18%

14. Match List -I with List -II(Use) and select the correct answer using the codes given below the list:
List -I (Material) List-II (Use)
A. Graphic 1. Coolant
B. Thorium-233 2. Moderator
C. Molten Sodium 3. Fissionable material
D. Plutonium-239 4. Fissile material
Codes :
A B C D
(a) 1 4 2 3
(b) 2 4 1 3 - Ans
(c) 2 3 1 4
(d) 1 3 2 4

15. The data given in the table refers to an engine based on Carnot cycle, where
Q1 = Heat received (kJ/min), Q2=Hear rejected (kJ/s), W=Work output (kW)
_______________________________________________
S. No. Q1 Q2 W
_______________________________________________
1. 1500 16.80 8.20
2. 1600 17.92 8.75
3. 1700 19.03 9.30
4. 1800 20.15 9.85
If heat received by the engine is 2000 kJ/minute the work output will be, nearly,
(a) 9.98
(b) 10.39
(c) 11.54
(d) 10.95 - Ans


Here I am providing you the paper as under:

Attached Files

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