JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech II AERODYNAMICS-I Previous Question Paper (February - 2024 - R15)
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
Differentiate between compressible and incompressible flows.
Answer
In incompressible flow, the density of the fluid remains constant throughout the flow field, typically assumed when the Mach number is less than 0.3. In contrast, compressible flow involves significant variations in fluid density, which must be accounted for when the Mach number exceeds 0.3, as the fluid's pressure and temperature changes significantly affect its density.
State the criteria for two or more flows to be dynamically similar.
Answer
Two or more flows are considered dynamically similar if they satisfy the following criteria:
- Geometric Similarity: The bodies involved in the flows must have the same shape, and the ratio of all corresponding linear dimensions must be equal.
- Kinematic Similarity: The flow patterns must be geometrically similar, meaning the ratios of velocity components at corresponding points in the flows must be constant.
- Dynamic Similarity: The ratios of all corresponding forces acting on the fluid particles (such as inertial, viscous, pressure, and gravitational forces) must be equal at corresponding points. This is typically achieved when dimensionless parameters like the Reynolds number, Mach number, and Froude number are identical for both flow systems.
Distinguish between path lines and streamlines in a fluid flow.
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State and explain Kelvin’s circulation theorem with a diagram.
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Define displacement thickness of a boundary layer.
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Define skin friction drag and pressure drag.
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Describe the horse shoe vortex system for a wing with a sketch.
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State Helmholtz’s vortex theorems.
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Define drag divergence Mach number with a sketch.
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What are the limitations of Froude’s momentum theory of a propeller?
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Part B
Using dimensional analysis, show that aerodynamic force is a function of Reynolds number and Mach number.
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Derive the continuity equation for an incompressible flow using a suitable flow model.
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What is doublet flow? Derive the expressions for velocity potential and stream function for a doublet flow with a neat sketch.
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Consider the velocity field given by u= y/(x2+y2), v= -x/(x2+y2). Calculate the equation for streamline passing through the point (0,5). Calculate vorticity and identify what type of flow it is.
Consider the velocity field given by u= y/(x2+y2), v= -x/(x2+y2). Calculate the equation for streamline passing through the point (0,5). Calculate vorticity and identify what type of flow it is.
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State Kutta-Zukowsky theorem and explain its physical significance with a neat sketch.
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Explain the concept of a boundary layer. Derive the boundary layer equations for a steady two-dimensional incompressible flow.
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Define momentum thickness of a boundary layer. Derive Von Karman Momentum integral equation.
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Explain Prandtl lifting line theory for a finite wing of an aircraft with neat sketches and derive the fundamental equation representing that theory.
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Describe the source panel method for prediction of non-lifting flow over an airfoil and derive the expression for pressure coefficient.
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Explain the function of winglets and swept wings in drag control of an aircraft.
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Derive the expressions for thrust and efficiency produced by a propeller using Froude’s momentum theory stating the assumptions made.
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