Jawaharlal Nehru Technological University Hyderabad
Jawaharlal Nehru Technological University Hyderabad B.Tech II AERODYNAMICS I Previous Question Paper (April - 2018 - R13)
Note: This question paper contains two parts A and B. Part A is compulsory which carries 25 marks. Answer all questions in Part A. Part B consists of 5 Units. Answer any one full question from each unit.
Part A
Define and explain Reynolds Number and Mach Number.
Answer
Reynolds Number (Re) is the ratio of inertial forces to viscous forces, defined as Re = ρvL/μ, indicating the flow regime (laminar or turbulent). Mach Number (M) is the ratio of flow velocity to the local speed of sound, M = v/a, determining the compressibility effects of the flow.
Explain the difference between compressible and incompressible flows.
Answer
In incompressible flow, fluid density remains constant (ρ = constant), typically valid for Mach numbers below 0.3. In compressible flow, density changes significantly with pressure and temperature variations, which is critical for high-speed aerodynamic analysis where M > 0.3.
State and explain D’Alembert’s paradox.
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Explain Kutta condition.
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Explain the role of viscosity in fluid flow.
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Describe a turbulent boundary layer.
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Define vortex filament.
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Describe and explain the trailing vortices of wings.
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Define critical Mach number.
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Define vortex.
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Part B
Define viscosity and discuss equation required.
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Derive Navier – Stokes equations.
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What is the physical significance of continuity equation?
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Derive the Momentum equation of a flow and explain how it varies for steady flow, iniviscid flow and a steady inviscid flow.
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Define, write the expressions and explain, uniform flow, source flow, sink flow and doublet.
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Derive an expression for a non-lifting flow over a circular cylinder.
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Define vortex flow, and circulation.
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State and explain Kutta – Joukowski theorem.
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State and explain Blasius solution for the flow over a flat plate.
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Explain the differences between laminar and turbulent boundary layers and the factors that influence these.
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Explain adverse pressure gradient and its effect on air flow over a body.
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Define skin friction drag and displacement thickness.
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Consider a thin flat plate at 7 degree angle of attack. Calculate a) the lift coefficient, b) the moment coefficient about the leading edge, c) moment coefficient about the quarter chord point, d) moment coefficient about the trailing edge.
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Consider an NACA 23012 airfoil. The mean camber line for this airfoil is given by
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Explain the phenomenon of drag divergence.
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Explain the designs of surfaces that augment the lift of a wing and the mechanisms by which the lift gets augmented.
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State and explain the actuator disk theory of Rankine and Froude and derive expressions for the performance of a propeller.
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