8.16 Friction Losses in Ducts
349
Flow rate (m
3 min
-1 )
Pressure loss (Pa m
-1
)
Fig. 8.16 Nomogram for the determination of friction losses as a function of airflow rate, speed
and duct diameter. Modified from the Flexadux sales catalogue
Exercise 8.14 An airflow rate of 4 m
3 min
−1 (0.067 m
3 s
−1 ) traverses a 100 mm
diameter duct. You are asked to:
(a) Estimate the pressure loss within the duct (Pa m
−1 ).
(b) Estimate the speed at which the air circulates under these conditions.
(c) Calculate the pressure loss by means of the Atkinson equation (with K 1.2 =
0.007
N s
2
m 4 ).
(d) Calculate the speed at which the air moves in the duct.
Solution
(a)
Using the nomogram in Fig. 8.16, above: 20 Pa m
−1
349
Flow rate (m
3 min
-1 )
Pressure loss (Pa m
-1
)
Fig. 8.16 Nomogram for the determination of friction losses as a function of airflow rate, speed
and duct diameter. Modified from the Flexadux sales catalogue
Exercise 8.14 An airflow rate of 4 m
3 min
−1 (0.067 m
3 s
−1 ) traverses a 100 mm
diameter duct. You are asked to:
(a) Estimate the pressure loss within the duct (Pa m
−1 ).
(b) Estimate the speed at which the air circulates under these conditions.
(c) Calculate the pressure loss by means of the Atkinson equation (with K 1.2 =
0.007
N s
2
m 4 ).
(d) Calculate the speed at which the air moves in the duct.
Solution
(a)
Using the nomogram in Fig. 8.16, above: 20 Pa m
−1