12
1 Fundamental Concepts of Fluid Mechanics for Mine Ventilation
P s
P v
P T
Fig. 1.8 Various arrangements for measuring the three types of pressures: static (P s ), dynamic (P v )
and total (P T )
Exercise 1.3 Indicate the types of pressures measured in the figure. Bearing in mind
that the heights are in cm of water column, transform these units to Pa.
1.1 cm
2.6 cm
3.7 cm
Not to scale
Solution
The pressure indicated by each metre can be calculated either by the hydrostatic
column expression (P = ρgh) or through the equivalence of Table 1.1, 1 mmwc =
9.807 Pa. Therefore:
Static pressure:
1.1 · 10 mmwc ·
9.807 Pa
1 mmwc
= 107.88 Pa
Total pressure:
3.7 · 10 mmwc ·
9.807 Pa
1 mmwc
= 362.86 Pa
Dynamic pressure:
2.6 · 10 mmwc ·
9.807 Pa
1 mmwc
= 254.98 Pa
1 Fundamental Concepts of Fluid Mechanics for Mine Ventilation
P s
P v
P T
Fig. 1.8 Various arrangements for measuring the three types of pressures: static (P s ), dynamic (P v )
and total (P T )
Exercise 1.3 Indicate the types of pressures measured in the figure. Bearing in mind
that the heights are in cm of water column, transform these units to Pa.
1.1 cm
2.6 cm
3.7 cm
Not to scale
Solution
The pressure indicated by each metre can be calculated either by the hydrostatic
column expression (P = ρgh) or through the equivalence of Table 1.1, 1 mmwc =
9.807 Pa. Therefore:
Static pressure:
1.1 · 10 mmwc ·
9.807 Pa
1 mmwc
= 107.88 Pa
Total pressure:
3.7 · 10 mmwc ·
9.807 Pa
1 mmwc
= 362.86 Pa
Dynamic pressure:
2.6 · 10 mmwc ·
9.807 Pa
1 mmwc
= 254.98 Pa