JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech II CHEMICAL ENGINEERING FLUID MECHANICS Previous Question Paper (September/October - 2023 - R13)
Note: i) Question paper consists of Part A, Part B. ii) Part A is compulsory, which carries 25 marks. In Part A, answer all questions. iii) In Part B, Answer any one question from each unit. Each question carries 10 marks and may have a, b as sub questions.
Part A
What is barometric equation? Mention the applications in fluid mechanics.
Answer
The barometric equation describes the variation of atmospheric pressure with altitude in an isothermal atmosphere, expressed as:
where P is the pressure at altitude z, P₀ is the sea-level pressure, M is the molar mass of air, g is the acceleration due to gravity, R is the universal gas constant, and T is the absolute temperature. In fluid mechanics, it is applied to determine pressure variations in compressible fluids, calculate air density at different elevations, and calibrate pressure-measuring instruments like barometers and altimeters.
What are Bingham plastics and dilatant fluids? Give examples and mention their rheological properties.
Answer
Bingham plastics are time-independent non-Newtonian fluids that require a finite yield stress to initiate flow. Below this yield stress, they behave as solids, but once exceeded, the shear stress is linearly proportional to the shear rate. Their rheological behavior is described by the equation:
where τ₀ is the yield stress and μₚ is the plastic viscosity. A common example is toothpaste or drilling mud.
Dilatant fluids (shear-thickening fluids) are non-Newtonian fluids whose apparent viscosity increases as the shear rate increases. This occurs because the particles in the fluid rearrange under stress to occupy more volume, leading to increased resistance to flow. An example is a concentrated suspension of cornstarch in water (oobleck).
Write notes on shear stress distribution for the flow of incompressible fluid in pipes.
Answer
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State and explain Buckingham π Theorem.
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Differentiate between subsonic flow and supersonic flow in compressible fluid flow.
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What is “asterisk condition” and stagnation temperature in the flow of compressible fluid?
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Define drag coefficient. Mention the importance of drag coefficient in flow past immersed bodies.
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Differentiate between particulate fluidization and bubbling fluidization.
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What is the working mechanism of gate valve and check valve?
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What is the working principle and uses of orificemeter?
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Part B
Explain the forces on static element of fluid and show that the pressure at any point is independent of direction in a static mass of fluid.
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What are Non – Newtonian fluids? State and explain Ostwald – de Waele equation for Non – Newtonian fluids.
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Discuss the equation of continuity for steady state fluid flow through a cylindrical pipe.
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Derive expression for average velocity and mass velocity for fluid flow through stream tube.
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Derive expression for shear stress distribution for steady state fluid flow through a horizontal cylindrical tube.
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Define Fanning friction factor and Darcy friction factor. Mention the importance in fluid flow.
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Derive Hagen – Poiseuille equation using average velocity expression for laminar flow in pipes. Mention the uses of Hagen – Poiseuille equation.
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Explain the calculation of average velocity for turbulent flow in smooth round pipes.
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Define Mach number. Mention the importance of Mach number in the flow of compressible fluids.
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Derive the total energy balance equation and mechanical energy balance equation for the analysis of compressible fluid flow.
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What are nozzles? Explain the variation of pressure ratio and mass flow rate for isentropic expansion of gas in convergent-divergent nozzle.
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Write the expression to calculate pressure ratio and temperature ratio in adiabatic frictional flow of gases and explain the variables.
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Explain the conditions for creeping flow and wake formation in flow past single sphere.
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Derive expression for the acceleration of particle for one dimensional motion of particle through fluid.
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Derive the Ergun equation to calculate pressure drop per unit length for flow through packed bed of solids.
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Define minimum fluidization velocity. Write the equation to calculate minimum fluidization velocity and explain the variables.
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Explain the working principle and uses of rotameter.
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With neat sketch, discuss the working conditions and uses of rotary positive displacement compressor.
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With neat sketch, discuss the construction and working principle of venturi meter.
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Write notes on two major classes of fluid-moving machineries.
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