Jawaharlal Nehru Technological University Hyderabad
Jawaharlal Nehru Technological University Hyderabad B.Tech II AERODYNAMICS I Previous Question Paper (May - 2019 - R15)
Note: This question paper contains two parts A and B. Part A is compulsory which carries 25 marks. Part B consists of 5 Units. Answer any one full question from each unit.
Part A
What do you mean by dimensionless similarity?
Answer
Dimensionless similarity refers to the condition where two flow fields are geometrically, kinematically, and dynamically similar, such that their governing non-dimensional parameters (like Reynolds number, Mach number, or Froude number) are identical. This allows experimental results from a small-scale model to be scaled and applied to a full-scale prototype.
State Buckingham π – theorem.
Answer
Buckingham π-theorem states that if a physical process involves n variables with m fundamental dimensions, it can be described by (n - m) independent dimensionless groups (π-terms). This theorem provides a systematic method for reducing the number of variables in a physical problem.
Explain the physical significance of Magnus effect.
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What is vorticity? State the Kelvin’s circulation theorem.
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What is the main reason for flow separation?
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Explain in brief about the different types of boundary layer thickness.
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How induced drag and downwash are co-related with each other?
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Explain about the Biot Savart’s law with suitable expression.
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Define advance ratio and torque coefficient.
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What is drag divergence Mach number?
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Part B
An aircraft flies at a Mach number of 0.85 at 18300 m where the pressure is 7160 N/m2 and the temperature is -56.5 0C. A model of l/l0th scale is to be tested in a high speed wind-tunnel. Calculate the total pressure of the tunnel stream necessary to give dynamic similarity, if the total temperature is 50 0C. It may be assumed that the dynamic viscosity is related to the temperature as:
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Justify the statement “Reynolds number may be used as the only criterion of dynamic similarity.’’
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Derive an expression of continuity equation for inviscid incompressible flow in differential form.
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The velocity of sound in air is a function of air pressure, density and coefficient viscosity. Determine an expression of speed of sound relating to these parameters using Rayleigh’s formula.
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What do you understand by D’Alembert’s Paradox? With the help of expression explain about source and sink flow.
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Explain in brief about the Kutta condition with neat sketches.
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Derive an expression of tangential and normal component of velocity for flow around a circular cylinder.
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What do you mean by stream function? Explain in brief about the assumptions of thin aerofoil theory.
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Write about the boundary layer equations.
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What are the different method to control boundary layer separation? Explain with neat sketches.
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Derive an expression for Von Karman’s momentum integral equation.
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Explain the effect of transition and surface roughness on aerofoil.
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A straight finite wing of AR=8. Calculate the coefficient of lift and coefficient of induced drag at an angle of attack of 4 0. Assuming the wing is thin and symmetrical.
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Derive an expression of induced velocity for finite lifting wing.
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Derive an expression of Induced velocity for Lifting Surface Theory. Consider the necessary assumptions.
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Explain in brief about the influence of downwash on tail plane.
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Explain by deriving relevant equations, how a propeller generates thrust.
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What do you mean by lift augmentation? Explain critical Mach number with neat sketches.
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Derive the expression for the non-dimensional inflow factor in terms of the thrust of the propeller.
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Why does it become necessary to employ a variable pitch blade in propeller? What is its advantage?
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