Jawaharlal Nehru Technological University Hyderabad
Jawaharlal Nehru Technological University Hyderabad B.Tech II AERODYNAMICS I Previous Question Paper (December - 2017 - 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
Write short notes on Variation of Reynolds number on the lift coefficient.
Answer
The lift coefficient (CL) is generally dependent on the Reynolds number (Re) due to viscous effects. As the Reynolds number increases, the boundary layer becomes thinner and more resistant to separation, typically leading to a slight increase in the lift slope and a delay in the stall angle, thereby increasing the maximum lift coefficient (CL,max).
List out all fundamental variables of aerodynamics.
Answer
The fundamental variables defining the state of a fluid in aerodynamics are:
- Pressure (p)
- Density (ρ)
- Temperature (T)
- Velocity (V or u, v, w components)
Define Kelvin's Circulation theorem.
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Define incompressible flow conditions.
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Write expressions for wall boundary conditions.
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What factors influencing the boundary layer separation?
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State the equation of Helmholtz theorem with neat sketch.
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Give a short notes on Horse Shoe vortex.
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Define Critical Mach number.
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What do you mean by advance ratio?
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Part B
Derive the continuity equation for a fluid flow in the form of a partial differential equation.
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Consider an airfoil in a flow with free stream velocity 150m/s. The velocity at a given point is 225 m/s. Calculate the pressure coefficient at that point.
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Derive the energy equation for a fluid flow in the integral form.
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Consider an airfoil at 120 AOA. The normal and axial force coefficients are 1.2 and 0.03, respectively. Calculate the lift and drag coefficients.
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For a particular airfoil section, the pitching moment coefficient about an axis one third of the chord of behind the leading edge various with the lift coefficient. Find the aerodynamic center and CMo.
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Prove that the streamline equation passing through the stagnation point in Non-lifting flow over cylinder is Ψ=0.
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Derive the stream function and potential functions for the combination of uniform and doublet flow.
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Define Circulation and Vorticity. Establish the relationship between the two in a flow.
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Compare the inviscid, incompressible flow and real flow over a sphere. Draw neat sketches wherever necessary.
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Derive skin friction drag by integration of tangential and pressure drag by integration of normal stresses respectively.
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Compare, with the help of sketches the laminar and turbulent boundary layers. Discuss flow separation and boundary layer approximation.
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Discuss the effect of transition and surface roughness on airfoil.
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Using Prandtl lifting line theory obtain the expression for induced velocity and induce angle of attack as a function of circulation ‘Г’.
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Explain elliptic loading and wings of elliptic platforms. Derive the expression for minimum induced drag for Elliptic platform.
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Consider a semi-infinite vortex filament. Find the velocity induced by this semi-infinite vortex filament at a point p from this filament according to Helmholtz theorem.
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Explain starting, bound and trailing vortices of wings and explain formation of them.
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What is the significance of propeller chart? Explain how the size and shape of the propeller can be selected.
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What is lift augmentation? Explain in detail how sweep, winglets and flaps are used for lift augmentation.
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Describe the phenomenon of slip stream with only axial velocity.
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Explain the actuator disk theory due to Rankine and Froude power.
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