JNTU
JNTU B.Tech II CHEMICAL ENGINEERING FLUID MECHANICS Previous Question Paper (November/December - 2020 - R13)
Answer any Five Questions. All Questions Carry Equal Marks.
Main
What is Rheology? Explain about Newtonian fluids.
Answer
Rheology is the science dealing with the deformation and flow of matter, specifically studying the relationship between stress, strain, and time for materials under applied forces. It characterizes how fluids respond to shear stress.
A Newtonian fluid is a fluid whose viscosity remains constant regardless of the shear rate applied to it. These fluids obey Newton's Law of Viscosity, which states that the shear stress is directly proportional to the velocity gradient (shear rate).
In this equation, τ is the shear stress, μ is the dynamic viscosity (a constant for Newtonian fluids), and du/dy is the velocity gradient. Common examples include water, air, and most low-molecular-weight liquids.
A pipeline tapers from 8 cm diameter to 4 cm diameter. If the discharge through the pipe is 100 lit/sec, find the average velocities at the two sections?
Answer
Given:
Diameter at section 1 (d1) = 8 cm = 0.08 m
Diameter at section 2 (d2) = 4 cm = 0.04 m
Discharge (Q) = 100 lit/sec = 0.1 m³/sec
The area of the pipe sections are calculated as:
Using the continuity equation (Q = A × V), the average velocities are:
Velocity at section 1 (V1):
Velocity at section 2 (V2):
For the following situations of steady flow, determine whether flow is laminar or turbulent?
Water at 10°C flowing at an average velocity of 2 m/s in a 100 mm pipe
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Air at 2 atm pressure and 180°F flowing at 50 ft/sec in 12-in duct
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Oil with a specific gravity of 0.78 and a viscosity of 20 cP flowing at 5 ft/s in a 2 inch pipe?
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Explain the variation of friction factor with Reynold’s number for turbulent flow in smooth and rough pipes.
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Find the loss of head due to friction in pipe of 1m diameter and 15 km long. The velocity of water in the pipe is 1m/sec. Take friction factor (f) = 0.005.
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Show by the method of dimensions that the resistance R to the motion of a sphere of diameter d moving with uniform velocity V through a fluid having density ρ and viscosity µ may be expressed as:
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What is isothermal frictional flow? Derive the equations for isothermal frictional flow.
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Derive the equations for one-dimensional motion of a particle through a fluid by writing the force balance on the particle.
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Explain different applications of fluidization.
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Explain about venturi meter with neat diagram.
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