Download GTU BE/B.Tech 2018 Winter 7th Sem New 2171914 Gas Dynamics Question Paper

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Subject Code: 2171914

GUJARAT TECHNOLOGICAL UNIVERSITY

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BE - SEMESTER-VII (NEW) EXAMINATION - WINTER 2018

Subject Name: Gas Dynamics

Time: 10:30 AM TO 01:00 PM

Instructions:

1. Attempt all questions.

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2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
4. Use of gas tables and steam tables is permitted.

Q.1

1. (a) Define the following terms: (a) Stagnation temperature (c) Stagnation velocity of sound (c) Mach number. [03]

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2. (b) Explain Mach number and its significance. [04]
3. (c) Define Gas dynamics state various laws applied in the study of gas dynamics. [07]

Q.2

1. (a) State assumptions made in deriving equations for Fanno flow. State two engineering fluid flow conditions which can be analyzed as Fanno flow [03]
2. (b) Show Rayleigh heating and Rayleigh cooling process on A-s diagram. [04]

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3. (c) Write a short on reference velocities. [07]

OR

1. Air enters the combustion chamber at 60kPa, 350K and 75m/s. the gasses leave the combustion chamber at a mach number of 0.75. for a mass flow rate of air of 30kg/s. Find mach number and stagnation temperature at inlet, the exit stagnation temperature, the rate of heat transfer and rate of fuel burnet of C.V. of 44 MJ/kg. [07]

Q.3

1. (a) Discuss concept of formation of normal shock waves. [03]

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2. (b) State the assumptions in the analysis of Rayleigh flow and give applications of Rayleigh flow. [04]
3. (c) Discuss the following terms with help of sketch (a) Mach angle (b) Zone of Silence (c) zone of action)(d) Mach cone. [07]

OR

1. (a) Explain (a) stagnation pressure (b) stagnation temperature [03]
2. (b) Define fanno flow process and state its governing equations. [04]

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3. (c) Derive the expression for the pressure ratio across normal shock in terms of density ratio [07]

Q.4

1. (a) What is strength of shock wave? Explain. [03]
2. (b) Derive following form of Prandtl-mayer equation ViV2=a* [04]
3. (c) State and explain the practical application of wind tunnel [07]

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OR

1. (a) Define critical state? Calculate the ratio of stagnation density to critical density for mono-atomic ideal gas [03]
2. (b) What are various types of wind tunnels used for low and high speed testing of models? [04]
3. (c) Draw the Fanno curve on h-s diagram and discuss the effect of friction in case of subsonic and supersonic flow. What is the limiting value of Mach number? [07]

Q.5

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1. (a) Define coefficient of compressibility and bulk modulus. [03]
2. (b) continues beyond maximum enthalpy point? [04]
3. (c) A circular duct passes 8.25 kg/s of air at an exit Mach number of 0.5. The entry pressure and temperature are 3.5bar and 38°C respectively and coefficient of friction is 0.005. if the Mach number at entry is 0.15, determine: (1) diameter of duct (2) length of duct (3) pressure and temperature at exit. [07]

OR

1. (a) Derive expression for pressure ratio, temperature ratio and velocity ratio for the Fanno flow of a perfect gas. [03]

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2. (b) Explain the phenomenon of choking in isentropic flow. [04]
3. (c) A Mach -2 aircraft engine employs a subsonic inlet diffuser of area ratio 3. A normal shock is formed just upstream of the diffuser inlet. The free stream conditions upstream of the diffuser are: p= 0.10 bar, T= 300 K. Determine (a) Mach number, pressure and temperature at the diffuser exit. (b) Diffuser efficiency including the shock. Assume isentropic flow in the diffuser downstream of the shock. [07]

Date: 15/11/2018

Total Marks: 70

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