Download GTU (Gujarat Technological University) BE/BTech (Bachelor of Engineering / Bachelor of Technology) 2019 Summer 7th Sem New 2171914 Gas Dynamics Previous Question Paper
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ?VII(NEW) EXAMINATION ? SUMMER 2019
Subject Code:2171914 Date:10/05/2019
Subject Name:Gas Dynamics
Time:02:30 PM TO 05:00 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
MARKS
Q.1 (a) Define Mach Number. Classify compressible flow on the basis of
Mach Number.
03
(b) An aircraft is flying at an altitude of 8 km where the ambient
temperature is 250 K. Find the Mach number and classify as
subsonic or supersonic when the speed of the aircraft is
a) 30 m/s
b) 300 m/s.
04
(c) Air flows through a duct at a pressure of 0.196 MPa with a velocity
350 m/s. The temperature of the air is 40?C. Determine the
isentropic Stagnation pressure, Stagnation temperature and
Stagnation density.
07
Q.2 (a)
Prove that (
?? ?? ?? ?
) =
(?? +?? )
??
03
(b) Draw the shape of subsonic and supersonic nozzle and diffuser and
mention the varying properties.
04
(c) Derive following expression for area ratio in terms of Mach number
?? ?? ?
=
?? ?? [
?? ?? + ?? +
?? ? ?? ?? + ?? ?? ?? ]
(?? +?? )
?? (?? ??? )
?
07
OR
(c) Air expands isentropically from 20 bar and 100?C to 12 bar.
Determine the temperature and density at the final state. Also find
the ratio if initial to final acoustic velocity.
07
Q.3 (a) Write general characteristic of normal shock. 03
(b) The pressure and Mach number upstream of a normal shock are 0.1
MPa and 2.0 respectively. Determine the Mach number and pressure
downstream of the shock.
04
(c)
Derive the following relation for normal shock ?? ?? ?? ?? = ?? ?
?? .
07
OR
Q.3 (a) Write three governing equations which satisfy the state before and
after a normal shock.
03
(b) Define strength of a shock wave. Find the strength of a shock wave
when normal shock appears at M = 2.
04
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Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ?VII(NEW) EXAMINATION ? SUMMER 2019
Subject Code:2171914 Date:10/05/2019
Subject Name:Gas Dynamics
Time:02:30 PM TO 05:00 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
MARKS
Q.1 (a) Define Mach Number. Classify compressible flow on the basis of
Mach Number.
03
(b) An aircraft is flying at an altitude of 8 km where the ambient
temperature is 250 K. Find the Mach number and classify as
subsonic or supersonic when the speed of the aircraft is
a) 30 m/s
b) 300 m/s.
04
(c) Air flows through a duct at a pressure of 0.196 MPa with a velocity
350 m/s. The temperature of the air is 40?C. Determine the
isentropic Stagnation pressure, Stagnation temperature and
Stagnation density.
07
Q.2 (a)
Prove that (
?? ?? ?? ?
) =
(?? +?? )
??
03
(b) Draw the shape of subsonic and supersonic nozzle and diffuser and
mention the varying properties.
04
(c) Derive following expression for area ratio in terms of Mach number
?? ?? ?
=
?? ?? [
?? ?? + ?? +
?? ? ?? ?? + ?? ?? ?? ]
(?? +?? )
?? (?? ??? )
?
07
OR
(c) Air expands isentropically from 20 bar and 100?C to 12 bar.
Determine the temperature and density at the final state. Also find
the ratio if initial to final acoustic velocity.
07
Q.3 (a) Write general characteristic of normal shock. 03
(b) The pressure and Mach number upstream of a normal shock are 0.1
MPa and 2.0 respectively. Determine the Mach number and pressure
downstream of the shock.
04
(c)
Derive the following relation for normal shock ?? ?? ?? ?? = ?? ?
?? .
07
OR
Q.3 (a) Write three governing equations which satisfy the state before and
after a normal shock.
03
(b) Define strength of a shock wave. Find the strength of a shock wave
when normal shock appears at M = 2.
04
2
(c) A normal shock wave moves through a duct of constant cross-
section with a velocity of 500 m/s. The air in the duct is stationary
and is a pressure and temperature of 0.1 MPa and 200 K
respectively. Determine the velocity of air after the passage of the
shock. Also find the pressure, temperature, Mach number and
stagnation temperature imparted upstream of the wave.
Normal Shock table:
M1 M2 P02/P01 P2/P1 T2/T1
1.46 0.71 .941 2.33 1.29
Isentropic table:
M T/T0 P/P0 ?/ ?0
0.56 0.940 0.808 0.858
0.58 0.936 0.796 0.849
07
Q.4 (a) Differentiate Fanno flow and Isothermal flow. 03
(b) Draw Fanno line on h-s diagram and discuss the effect of friction in
subsonic and supersonic flow.
04
(c) The average friction of a 25 mm diameter 12 meter long pipe is
0.004. The condition of air at the entry are 2 bar and 300 K.
Determine the mass flow rate, pressure, temperature and the mach
number at exit, if the mach number at inlet is 0.25.
07
OR
Q.4 (a) Define dimensionless Critical Mach number. Give its uses. 03
(b) Explain phenomenon of chocking in Isentropic flow. 04
(c) Air flows through an insulated circular pipe at a rate of 495
kg/minute. The pressure, temperature and Mach number of air at
entrance to the pipe are 0.3 MPa, 300 K and 0.15 respectively. The
coefficient of friction for the pipe is assumed constant and its value
is 0.005. if the Mach number at exit is 0.5, determine:
a) The diameter of the pipe
b) The length of the pipe.
07
Q.5 (a) Define fanning?s coefficient of friction and hydraulic diameter. 03
(b) Air flow in a duct with a velocity of 215 m/s. The temperature of air
measured at a point along the duct is 30?C and the air pressure is 5
bar. Determine the stagnation pressure.
04
(c) Show that the Mach number corresponds to the maximum entropy
point of a Fanno curve is unity.
07
OR
Q.5 (a) Air enters in a pipe of 0.05 m diameter at stagnation condition of 10
bar and 400 K at Mach number of 2.8. Find the mass flow rate in
pipe the pipe.
03
(b) Show graphically that zone of silence is greater than zone of action
when object is moving with speed more than the velocity of sound.
04
(c) Explain the characteristics of Rayleigh flow with suitable graphs. 07
Fanno Flow Table (for air):
M =0.14 M= 0.16 M =0.24 M= 0.26 M= 0.50 M= 0.52 M= 0.54
4?? ?? ?????? ??
32.511 24.197 9.38 7.68 1.069 0.917 0.786
P/P* 7.80 6.829 4.538 4.185 2.138 2.051 1.971
T/T* 1.195 1.193 1.186 1.183 1.142 1.138 1.133
*************
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This post was last modified on 20 February 2020