JNTU
JNTU B.Tech III AERODYNAMICS II Previous Question Paper (May/June - 2019 - R13)
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.
Part A
Why is an isentropic process not necessarily an adiabatic process?
Answer
An isentropic process is defined as both adiabatic and reversible. While an adiabatic process involves no heat transfer, it may be irreversible due to effects like friction or turbulence. Therefore, an adiabatic process is not necessarily isentropic, and an isentropic process requires the additional condition of reversibility.
A cyclic heat engine operates between a source temperature of 800°C and a sink temperature of 30°C. What is the heat rejection per kW net output of the engine?
Answer
The maximum thermal efficiency of a heat engine is given by the Carnot efficiency: η = 1 - (Tsink / Tsource). Converting temperatures to Kelvin: Tsource = 800 + 273.15 = 1073.15 K and Tsink = 30 + 273.15 = 303.15 K. η = 1 - (303.15 / 1073.15) = 0.7175. Since η = W / Qin and Qin = W + Qout, the heat rejection per unit work is Qout / W = (1 / η) - 1 = (1 / 0.7175) - 1 = 0.3937 kW per kW net output.
Write the Bernoulli equation for a compressible flow?
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Does entropy rises across a normal shock? If so, how is it possible?
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What is the difference between a Mach wave and Shock wave?
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Explain the concept of wave drag in brief.
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What is critical Mach number?
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Using linearized theory, calculate the lift and drag coefficients for a flat plate at a 5° angle of attack in a Mach 3 flow.
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What is the advantage of method of characteristics? Explain.
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Consider a flat plate at α = 15° in a Mach 18 free stream. Using straight Newtonian theory, calculate lift and wave drag coefficients.
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Part B
A fluid is confined in a cylinder by a spring loaded, frictionless piston so that the pressure in the fluid is a linear function of volume (p = a + bV). The internal energy of the fluid is given by the following equation U = 45 + 3.15 pV where U is in kJ, p in kPa, and V in m³. If the fluid changes from an initial state of 170 kPa, 0.03 m³ to a final state of 400 kPa, 0.06 m³, with no work other than that done on the piston, find the direction and magnitude of the work and heat transfer.
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One kg of water at 283 K is brought into contact with a heat reservoir at 383 K. When the water has reached 383 K, find the entropy change of the water, of the heat reservoir, and of the universe.
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Derive the Area-Mach number relation for the conduit.
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The flow just upstream of a normal shock wave is given by p1 = 1 atm, T1 = 288 K, and M1 = 2.6. Calculate the following properties just downstream of the shock: p2, T2, ρ2, M2, P02, T02, and the change in entropy across the shock.
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Derive the expressions for stagnation pressure, stagnation density and stagnation temperature. What is the use of these in the context of compressible flows?
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Derive an expression for θ-β-M relation. How is it important for the analysis of oblique shocks?
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Using shock expansion theory, calculate the flow Mach numbers assuming the slip stream deflection to be negligible for the flat plate.
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A convergent nozzle has an exit area of 0.0625 m². Air enters the nozzle with a stagnation pressure of 0.7 MPa and stagnation temperature of 950°C. Determine the mass flow rate per unit area for a back pressure of a) 0.56 MPa b) 0.2 MPa. Assume isentropic flow.
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Derive the linearized velocity potential equation for a two dimensional, irrotational, isentropic flow.
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Derive the governing equations of linearized supersonic flow.
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Explain the principle of limited upstream influence in supersonic flow.
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