B.TECH - Semester 7 gas dynamics Question Paper 2013 (dec)
Practice authentic previous year university questions for better exam preparation.
- Explain choking in Fanno flow.
- What are the assumptions of Rayleigh flow?
- Discuss the effect of Mach number on compressibility.
- Explain impulse function.
- (b) The conditions of a gas in a combustor at entry are: pressure 0.343 bar, temperature 310 K , velocity $60 \mathrm{~m} / \mathrm{s}$. Determine the Mach number, pressure, temperature and velocity at the exit if the increase in stagnation enthalpy of the gas between entry and exit is $1172.5 \math...
- Explain the working of a wedge probe.
- (b) A convergent divergent nozzle having a throat diameter of 7.5 mm supplies air to an insulated duct of diameter 15 mm . The stagnation properties of air at entry to the nozzle arc 7.5 bar and 300 K . The flow though the nozzle is isentropic. The mean friction factor for the duct is 0.005 . Calcul...
- Explain Mach angle and Mach cone.
- (b) Derive the expression for stagnation pressure to static pressure ratio in an isentropic flow.
- Define $M^{*}$ and write its significance.
- What is the difference between supersonic and subsonic nozzles and diffusers?
- State the differences between interferometer and shadowgraph.
- Write note on temperature recovery factor. ( $\mathbf{1 0} \boldsymbol{\times} \mathbf{2} \boldsymbol{=} \mathbf{2 0}$ Marks) P.T.O.
- (a) Derive the law of conservation of mass as applicable to control volume. State all the assumptions.
- (b) Air ( $\gamma=1.4, \mathrm{R}=287.43 \mathrm{~J} / \mathrm{kg} \mathrm{K}$ ) enters a straight axisymmetric duct at $300 \mathrm{~K}, 3.45 \mathrm{bar}$ and $150 \mathrm{~m} / \mathrm{s}$ and leaves it at $277 \mathrm{~K}, 2.058 \mathrm{bar}$ and $260 \mathrm{~m} / \mathrm{s}$. The area of cross...
- (a) Starting from fundamentals derive the expression for velocity of sound through a fluid.
- (a) Derive $\frac{d A}{A}=\left(\frac{d p}{\rho c^{2}}\right)\left(1-M^{2}\right)$ for one dimensional isentropic flow.
- (a) Derive Prandtl-Meyer relation for a normal shock in a perfect gas.
- (a) Prove that the Mach numbers at maximum enthalpy and maximum entropy points on a Rayleigh line are $\frac{1}{\sqrt{\gamma}}$ and 1 respectively.
- (b) Explain open circuit wind tunnel with suitable sketches. OR
- (a) Describe working of a constant temperature hot wire anemometer.
- (b) How is it possible to employ the Pitot tube for measurement in a supersonic stream? Derive Rayleigh supersonic Pitot formula.
- (i) stagnation temperature (ii) maximum velocity (iii) mass flow rate, and (iv) area of cross section at exit. OR
- (b) An aircraft employs a subsonic inlet diffuser of area ratio 4. Free stream air at a total pressure and temperature of $10^{5} \mathrm{~Pa}$ and 570 K approaches the diffuser with a Mach number 2.2. A shock wave stands just outside the diffuser inlet. Determine the Mach number, pressure and tempe...
- (b) A certain diffuser has an area ratio of 2:1. If the air enters the diffuser with a Mach number of 0.8 , pressure $0.5 \mathrm{MN} / \mathrm{m}^{2}$ and a temperature of $60^{\circ} \mathrm{C}$. Compute the exit Mach number, exit velocity, exit temperature and percentage change in impulse functio...
- (a) Derive an expression for change in entropy of a Fanno flow. With the help of second law of thermodynamics explain the direction of the process.
- (a) With the help of neat sketch explain the working of Schileren apparatus.
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