EFFECT OF FLANGES ON THE VELOCITY IN FRONT OF EXHAUST VENTILATION HOODS*

摘要

The addition of a flange to a local exhaust ventilation hood can produce a large increase in velocity in front of the hood. It is shown that an optimum flange width exists beyond which there is little further increase in velocity; this flange width isA½where A is the area of the hood. As hood aspect ratio increases, the effect of flanges increases and the addition of even small flanges to slots can have an appreciable effect. Velocity increases of over 55have been measured in front of hoods of aspect ratio 16:1