Fluid Mechanics and Thermal Sciences - Online Test
Q1. Water has a critical specific volume of 0.003155 / m3 kg. A closed and rigid steel
tank of volume 0.025 m3 contains a mixture of water and steam at 0.1MPa. The
mass of the mixture is 10 kg. The tank is now slowly heated. The liquid level
inside the tank
Answer : Option A
Explaination / Solution:
No Explaination.
Q2. Consider an incompressible laminar boundary layer flow over a flat plate of length L, aligned with the direction of an incoming uniform free stream. If F is the ratio of the drag force on the front half of the plate to the drag force on the rear half,
then
Answer : Option D
Explaination / Solution:
No Explaination.
Q3. In a steady flow through a nozzle, the flow velocity on the nozzle axis is given
by v = u0(1 + 3x/L), where
x is the distance along the axis of the nozzle from its
inlet plane and
L is the length of the nozzle. The time required for a fluid particle
on the axis to travel from the inlet to the exit plane of the nozzle is
Answer : Option B
Explaination / Solution:
No Explaination.
Q4. Consider steady laminar incompressible anti-symmetric fully developed viscous
flow through a straight circular pipe of constant cross-sectional area at a Reynolds
number of 5. The ratio of inertia force to viscous force on a fluid particle is
Answer : Option A
Explaination / Solution:
No Explaination.
Q5. A steel rod of length L and diameter D, fixed at both ends, is uniformly heated to a temperature rise of ΔT . The Young’s modulus is E and the co-efficient of linear expansion is α. The thermal stress in the rod is
Answer : Option C
Explaination / Solution:
No Explaination.
Q6. For an under damped harmonic oscillator, resonance
Answer : Option C
Explaination / Solution:
No Explaination.
Q7. The inlet angle of runner blades of a Francis turbine is 90o. The blades are so
shaped that the tangential component of velocity at blade outlet is zero. The flow
velocity remains constant throughout the blade passage and is equal to half of the
blade velocity at runner inlet. The blade efficiency of the runner is
Answer : Option C
Explaination / Solution:
No Explaination.
Q8. The temperature distribution within the thermal boundary layer over a heated
isothermal flat plate is given by 
where
Tw and
T∞ are
the temperature of plate and free stream respectively, and
y is the normal
distance measured from the plate. The local Nusselt number based on the thermal
boundary layer thickness δt is given by
where
Tw and
T∞ are
the temperature of plate and free stream respectively, and
y is the normal
distance measured from the plate. The local Nusselt number based on the thermal
boundary layer thickness δt is given by
Answer : Option B
Explaination / Solution:
No Explaination.
Q9. In a counter flow heat exchanger, hot fluid enters at 60oC and cold fluid leaves
at 30oC. Mass flow rate of the fluid is 1 kg/s and that of the cold fluid is 2 kg/s.
Specific heat of the hot fluid is 10 kJ/kgK and that of the cold fluid is 5 kJ/kgK.
The Log Mean Temperature Difference (LMTD) for the heat exchanger in oC is
Answer : Option B
Explaination / Solution:
No Explaination.
Q10. The average heat transfer co-efficient on a thin hot vertical plate suspended in still
air can be determined from observations of the change in plate temperature with
time as it cools. Assume the plate temperature to be uniform at any instant of
time and radiation heat exchange with the surroundings negligible. The ambient
temperature is 25oC, the plat has a total surface area of 0.1m2 and a mass of
4 kg. The specific heat of the plate material is 2.5 kJ/kgK. The convective heat
transfer co-efficient in W/m2K, at the instant when the plate temperature is
225oC and the change in plate temperature with time dT/dt = -0.02 K/s, is
Answer : Option D
Explaination / Solution:
No Explaination.
