Jawaharlal Nehru Technological University Hyderabad
Jawaharlal Nehru Technological University Hyderabad B.Tech II AERODYNAMICS I Previous Question Paper (December - 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. Each question carries 10 marks and may have a, b, c as sub questions.
Part A
Define Mach number and write its physical significance.
Answer
The Mach number (M) is defined as the ratio of the flow velocity (V) to the local speed of sound (a), expressed as M = V/a. Its physical significance lies in characterizing the compressibility effects of the flow; it determines whether the flow is subsonic (M < 1), sonic (M = 1), supersonic (M > 1), or hypersonic (M > 5).
What are the fundamental aerodynamic variables? Write the formulae for computing them.
Answer
The fundamental aerodynamic variables are pressure (p), density (ρ), temperature (T), and velocity (V). They are related by the equation of state for a perfect gas: p = ρRT, where R is the specific gas constant. Velocity is typically determined via the continuity equation (ρAV = constant) and the momentum equation (Euler's or Navier-Stokes equations).
What is the significance of large Reynolds number flows?
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Write the boundary conditions at infinity and wall for a potential flow.
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What is a boundary layer flow?
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Define displacement thickness, momentum thickness and energy thickness of a boundary layer.
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What are the advantages of wings having elliptic platforms?
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State Helmholtz’s vortex theorems.
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What is critical Mach number?
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Why the propeller is twisted by blade element analysis?
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Part B
Derive the continuity equation in differential form for an incompressible flow.
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Show the implantation of Buckingham’s theorem with an example.
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Derive the stream function for the flow resulting from super imposition of uniform flow with doublet flow.
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What is the significance of Kutta condition?
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Explain the concept of starting vortex.
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A plate of 700mm length and 100mm wide is immersed in a fluid of Sp. Gr. 0.9 and kinematic viscosity = 10-5 m2/s. The fluid is moving with a velocity of 6 m/s. Determine a) boundary layer thickness b) Shear stress at the end of the plate, and c) drag force on one side of the plate.
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Sketch and compare the boundary layer growth for laminar and turbulent conditions. Also explain when boundary layer changes from laminar to turbulent.
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Explain Prandtl’s lifting line theory for a finite wing.
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Explain the vortex panel method for computing flow an airfoil.
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What are the different types of flaps and slats? Write the application of each.
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Explain the concept of slip stream with only axial velocity in detail.
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