\[Vexit=\frac{Qgas}{Astack}\]
Variables
Vexitstack exit velocity (m/s)
Qgasstack gas volumetric flow rate (m³/s)
Astackstack cross-sectional area (m²)
Description
What is this formula?
This formula calculates the exit velocity of gases leaving a stack or chimney from the volumetric flow rate and stack cross-sectional area.
When to use it
Use it when designing stacks, evaluating emission dispersion, estimating plume rise, or analyzing industrial exhaust systems.
Example
Data:
Q = 12 m³/s
A = 0.80 m²
Formula:
v = Q / A
Substitution:
v = 12 / 0.80
Result:
v = 15 m/s
Applications
Stack design, emission monitoring, atmospheric dispersion studies, plume rise calculations, industrial ventilation, and environmental permitting.
Note
This formula assumes a uniform velocity profile across the stack cross section. Actual gas velocity may vary spatially and may require correction factors depending on measurement methodology and stack geometry.