velocities at the nozzle exit, how would it affect the mass
flow rate through the nozzle?
17–49C How does the parameter Ma* differ from the Mach
number Ma?
17–50C What would happen if we attempted to decelerate
a supersonic fluid with a diverging diffuser?
17–51C What would happen if we tried to further acceler-
ate a supersonic fluid with a diverging diffuser?
17–52C Consider the isentropic flow of a fluid through a
converging–diverging nozzle with a subsonic velocity at the
throat. How does the diverging section affect (a) the velocity,
(b) the pressure, and (c) the mass flow rate of the fluid?
17–53C Is it possible to accelerate a fluid to supersonic
velocities with a velocity other than the sonic velocity at the
throat? Explain.
17–54 Explain why the maximum flow rate per unit area
for a given gas depends only on P 0 /. For an ideal gas
with k1.4 and R0.287 kJ/ kg ·K, find the constant a
such that m.
/A* aP 0 /.
17–55 For an ideal gas obtain an expression for the ratio of
the velocity of sound where Ma 1 to the speed of sound
based on the stagnation temperature,c*/c 0.
17–56 An ideal gas flows through a passage that first con-
verges and then diverges during an adiabatic, reversible,
steady-flow process. For subsonic flow at the inlet, sketch the
variation of pressure, velocity, and Mach number along the
length of the nozzle when the Mach number at the minimum
flow area is equal to unity.
17–57 Repeat Prob. 17–56 for supersonic flow at the inlet.
17–58 Air enters a nozzle at 0.2 MPa, 350 K, and a veloc-
ity of 150 m/s. Assuming isentropic flow, determine the pres-
sure and temperature of air at a location where the air
velocity equals the speed of sound. What is the ratio of the
area at this location to the entrance area?
Answers:0.118 MPa, 301 K, 0.629
17–59 Repeat Prob. 17–58 assuming the entrance velocity
is negligible.
17–60E Air enters a nozzle at 30 psia, 630 R, and a veloc-
ity of 450 ft/s. Assuming isentropic flow, determine the pres-
sure and temperature of air at a location where the air
velocity equals the speed of sound. What is the ratio of the
area at this location to the entrance area?
Answers:17.4 psia, 539 R, 0.574
17–61 Air enters a converging–diverging nozzle at 0.5 MPa
with a negligible velocity. Assuming the flow to be isen-
tropic, determine the back pressure that will result in an exit
Mach number of 1.8. Answer:0.087 MPa
17–62 Nitrogen enters a converging–diverging nozzle at 700
kPa and 450 K with a negligible velocity. Determine the criti-
cal velocity, pressure, temperature, and density in the nozzle.1 T 01 T 0876 | Thermodynamics17–63 An ideal gas with k1.4 is flowing through a noz-
zle such that the Mach number is 2.4 where the flow area is
25 cm^2. Assuming the flow to be isentropic, determine the
flow area at the location where the Mach number is 1.2.
17–64 Repeat Prob. 17–63 for an ideal gas with k1.33.
17–65 Air at 900 kPa and 400 K enters a converging
nozzle with a negligible velocity. The throat area
of the nozzle is 10 cm^2. Assuming isentropic flow, calculate
and plot the exit pressure, the exit velocity, and the mass flow
rate versus the back pressure Pbfor 0.9 Pb0.1 MPa.
17–66 Reconsider Prob. 17–65. Using EES (or other)
software, solve the problem for the inlet condi-
tions of 1 MPa and 1000 K.
17–67E Air enters a converging–diverging nozzle of a
supersonic wind tunnel at 150 psia and 100°F with a low
velocity. The flow area of the test section is equal to the exit
area of the nozzle, which is 5 ft^2. Calculate the pressure, tem-
perature, velocity, and mass flow rate in the test section for a
Mach number Ma 2. Explain why the air must be very dry
for this application. Answers:19.1 psia, 311 R, 1729 ft/s,
1435 lbm/sShock Waves and Expansion Waves
17–68C Can a shock wave develop in the converging sec-
tion of a converging–diverging nozzle? Explain.
17–69C What do the states on the Fanno line and the
Rayleigh line represent? What do the intersection points of
these two curves represent?
17–70C Can the Mach number of a fluid be greater than 1
after a shock wave? Explain.
17–71C How does the normal shock affect (a) the fluid
velocity, (b) the static temperature, (c) the stagnation temper-
ature, (d) the static pressure, and (e) the stagnation pressure?
17–72C How do oblique shocks occur? How do oblique
shocks differ from normal shocks?
17–73C For an oblique shock to occur, does the upstream
flow have to be supersonic? Does the flow downstream of an
oblique shock have to be subsonic?
17–74C It is claimed that an oblique shock can be analyzed
like a normal shock provided that the normal component of
velocity (normal to the shock surface) is used in the analysis.
Do you agree with this claim?
17–75C Consider supersonic airflow approaching the nose
of a two-dimensional wedge and experiencing an oblique
shock. Under what conditions does an oblique shock detach
from the nose of the wedge and form a bow wave? What is
the numerical value of the shock angle of the detached shock
at the nose?
17–76C Consider supersonic flow impinging on the rounded
nose of an aircraft. Will the oblique shock that forms in front
of the nose be an attached or detached shock? Explain.cen84959_ch17.qxd 4/21/05 11:08 AM Page 876