Question

Fundamentals-of-Compressible-Fluid-Dynamics Balachandran

CHAPTER 4

6. A conical diffuser of 15 cm has an area ratio of 4. If the pressure, temperature and velocity at the inlet section are 0.69 bar, 340 K and 180 m/s, estimate the exit pressure and exit velocity. What will be the change in impulse function.
[Ans. p2 = 0.8074 bar; V2 = 45 m/s; F2 - F1 = 4167.5 N]

7. The Mach number at inlet and exit of a supersonic diffuser are 3 and 1.5 respectively. The air at inlet has a pressure of 70 kPa and a temperature of -7°C. If the mass flow rate of air is 125 kg/s, find (0 stagnation conditions (ii ) exit area (iii ) static conditions of air at exit.
[Ans. p0 = 3573.53 kPa; T0 = 745.1 K; Ae = 3.86 x 10-2 m2; p2 = 700 kPa; T2 = 513.4 K; V2 = 681.26 m/s] .

8. A nozzle in a wind tunnel gives a test section Mach number of 3.5. Heated air enters the nozzle from a large source at 300kPa and 240C. If the mass flow rate through the test section is 3.5 kg/s, find the pressure, temperature, velocity and area at the throat and exit sections of the nozzle. Assume the one-dimensional isentropic flow.
[ANS p1= 4224 kPa; T1= 427.8 K; V1 = - 4I4.6 m/s; A1= 0.245 x I 0^-2m2 ; pe=10.48 kPa; Te= 148.26 K. Ve=854.25m/s , Ae= 1.6635 x 10^-2m2|
9. Air enters a nozzle having a throut area of 930 cm2 and attains a Mach number of 2.5 at the exit. The supply air is at a pressure of 1.05 bar and a temperature of 21"C and is having negligible velocity find the mass flow rate, area and fluid properties at the exit of the nozzle.
(Ans. m = 23.02 kg/s; Ar = 0.245 m2; pe = 0.0614 bar. Te= 130.54 K; Ve= 572.55 m/s)
10. A perfectly designed convergent divergent diffuser is directly fitted to the exit of a duct of uniform cross-section 0.001 m2. The air at the exit of the duct is at 0.105 MPa and 75°C and is having a velocity of 600 m/s. Estimate the pressure of air at the exit of the diffuser, if the area of the diffuser at exit is same as the area at inlet. Also, find the throat area and the mass flow rate. Assume isentropic flow.

[ Ans. pe =0.3624 MPa; A,= 8 x 10^-4 m2 ; m = 0.6308 kg/s)

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Answer 1

ANS- 6

T34 Vi RT 180 mo,486 Since n diffusen shope of diffuse is divenging 午 , , al mt= 0.4-86 1.3595

fi. Pe 0,848 с. 0 886 To 340 054 To Te = 356,31 K A,IA 4 3595 Po 5.438

2 fn 2. 3255 fs

2.- 23255 2361b

ANS--10

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