Abstract
The article presents a review of the literature for the calculation of velocities in the vicinity of local exhaust hoods (centerline velocities and velocities outside the axis). The effects of parameters related to the opening (shape, length to width ratio, presence of a flange, transition angle) and to environmental conditions (suction in open field or in presence of obstacles) on the velocity field are studied. Formulas for the calculation of the centerline velocity in front of free-standing openings are compared, and a choice from among these formulas is proposed.