142
4 Mine Ventilation Networks
Qa = 150
Qs = 150
N 1
Q 12
N 2
Q 23
N 3
90
60
Mesh 1
Mesh 2
Q 24 30
Q 14 60
N 4
Q 34
N 4
-90
Airflow rates in each branch:
Iteration 1.
Iteration
(n°)
Mesh
(M)
Branch
( ij )
Q ij (m 3 s −1 ) Resistance
(R ij )
P ij = R ij
Q 2
ij (with the
sign of the
airflow rate)
ij /Q ij Correction
(
1
M 1
14
−60
0.4
−1440
24
−11.4
12
90
0.3
2430
27
24
30
0.8
720
24
1710
75
M 2
34
−90
0.2
−1620
18
20.625
23
60
0.1
360
6
24
−30
0.8
−720
24
−1980
48
The values obtained for ij in each mesh are applied to correct the flows in the
following calculation:
Example for Q 14
Initial airflow rate: −60 m
3 s
−1
Correction for M 1 : 1 = −11.4 m
3 s
−1
Corrected flow rate for the following calculation: −60.0 m
3 s
−1
+ (−11.4) m
3
s
−1
= −71.4 m
3 s
−1
Note that since Q 14 belongs only to M 1 , only the correction calculated for this
mesh need be used.
For the branches that are common to two meshes, airflow rates must be corrected
using the values of found for both meshes as follows: