Reg. No. 'LI --'----'----'----'----'----'----'----'----'----'-----'

Question Paper Code 11116

B.E./B.Tech. DEGREE EXAMINATION, APR1L/MAY 2011

Fifth Semester

Aeronautical Engineering

AE 2303 - AERODYNAMICS - II

(Regulation 2008)

Time: Three hours Maximum: 100 marks

Gas Tables Permitted

Answer ALL questions

PART A - (10 II 2 - 20 marks)

1. Estimate the velocity of sound in air which is at a pressure of l.013" lO s

N/m2 and density of 0.85 kgjm3.

2. Why convergent divergent nozzle is needed for producing supersonic flow?

3. What is Prandtl relation for Normal shocks? Explain its significance.

4. What is the maximum and minimum possible value of shock angle for oblique shocks?

5 . A wedge of variable half angle is kept in a su~rson ic stream of Mach 2 . Determine the maximum half angle up to which attached shock is possible.

6. What is the maximum possible turning angle when a supersonic stream

flows over an expansion corner? Give appropriate reason.

7 What is meant by Rayleigh flow?

8. What is Prandtl-Glauert Rule?

9. What IS drag divergence Mach number?

10. How shock induced separation occurs?

II . (a)

(b)

(i)

PART B - (5 JI 16"" 80 marks)

Obtain the Isothermal compressibility of air 2' 10 ' N/m2.

at a pressure of (8)

(ii) From the fundamentals derive an expression for velocity of sound in air and show that it is proportional to the square root of absolute temperature of air.

ti)

0,

Derive the Area-Velocity-Mach significance.

number relatIOn and explain ItS (6)

(Ii) Air flows from a large reservOir through a convergent divergent noule, the pressure and temperature m the reservoir being 600 kPa and 40 deg C respectIVely. The throat area of the nozzle i, 10~ ml and the pressure on the nozzle exit plane is 130 kPa and temperature IS 20 deg C. Assummg the flow through the noule to be Isentropic, steady and one dimensional estimate

(I) the mass flow rate through the nozzle and

(2) the eXit area of the nozzle. (10)

12. (a) Wnte a bridnote on

(I) shock polar In non dimensional form

Iii) Rankine-Hugoniot relation.

(iii) Raleigh Pitot formula for supersomc flow.

0,

(6)

(6)

(4)

(bl A supersomc mlet IS designed to operate at Mach J. Two possibiliues are considered as shown m figure.

" In case I, the compreSSiOn and deceleration of the flow lakes place through a single nonna] shock In case II a wedge shaped central body IS used and the deceleratiOn IS through two weak obhque shocks followed by a nonnal shock The wedge turnmg angles are 8 - each Estimate the loss m total pressure in both cases.

2 11116

J 3, (a) Discuss in detail the principle and methodology adopted in Method of Cha racteristics deriving the necessary equations.

0,

(b) Ai r nows in a duct of square cross section of s ide 5 cm. The air enters at M - 3.0 and it IS to leave at M - 2.0. Estimate the pipe length needed. Also obtain the extra length required to have Mach 1.0 at the exit. Assume the now to be frictional and adiabatic. The friction factor is 0.003.

14. (a) Air enters a combustion chamber with a certain Mach number. Sufficient heat is added to obtain a stagnation temperature ratio of 3 and a final Mach number of 0.8. Determme Ii) the Mach number at entry and (ii) the % loss in total pressure a lso estimate (iii) the ratiO of static pressure.

Ib) I.)

0,

A uniform now at Mach 1.5, static pressure of 90 kPa and static temperature of 5 degree C passes over an expansion corner with wall inclination of 8 degree. Estimate the Mach number, static pressure and static temperature downstream of the expansion fan .

16)

(ii) Based on the small perturbation theory obtain the compressible potential equation in hnearised form. State the assumptions clearly. (10)

15. (a) (i) A thin nat plate is kept at a positive angle of attack of 3 degree in a uniform stream of Mach 3 and static pressure of 50 kPa . Based on linearised theory estimate the static pressures on the upper and bottom surfaces of the plate.

(ii) Explain the terms Mach cone, Mach angle, Zone of action and Zone of silence. (5)

(iii) Discuss the relative merits and demerits of forward swept and swept back wings, (5)

0,

(bl Write short notes on the following:

(i) Super c ritical Aerofoils.

(ii) Transonic Area Rule .

(ii i) Acrofoils for supersonic nows.

3

IS)

16)

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16)

IS)