Page 171 - 48Fundamentals of Compressible Fluid Mechanics

8.7. EXAMPLES 133

To check whether the flow rate is satisfied the requirement

& 1

%(

the mass flow rate requirements is satisfied.
# #
#
should be replaced by in the calculations. If

'%*

#
not see below The speed of sound at the entrance is

It should be noted that
Since

and the density is
%!(

!( 1
# #

The velocity at the entrance should be # 3

%!(
#

The diameter should be

'% %
!( 1

3

Nevertheless, for sake of the exercise the other parameters will be calculated. This
3

#
situation is reversed question. The flow rate is given with the diameter of the pipe.
# #
It should be noted that the flow isn’t chocked.
,

(
3
Example 8.3:
A flow of gas from a station (a) with pressure of 20[bar] through a pipe with 0.4[m]
diameter and 4000 [m] length to a different station (b). The pressure at the exit
(station (b)) is 2[bar]. The gas and the sounding temperature can be assumed
to be 300 K. Assume that the flow is isothermal, k=1.4, and the average friction
f=0.01. Calculate the Mach number at the entrance to pipe and the flow rate.
SOLUTION
First, the information whether the flow is choked needed to be found. Therefore, at
first it will be assumed that the whole length is the maximum length.

with

the following can be written

# #