EXPERIMEHTAL STUDY OH THREE DIMENSIONAL FLOW FIELDS OF LATERAL EXHAUST HOOD WITH A MANNEQUIN

摘要

Using a hot wire/film probe to study the characteristics of air flow fields is a new trend in recent developments.In this paper,the author used a three-dimensional hot film probe in the industrial ventilation to study the three-dimensional flow fields of local exhaust hoods.In order to know the effect of the operator in the flow fields.a mannequin was put in front of the opening to simulate an active person. From our experiments,three important conclusions were obtained.they were: Near to the edge of the opening.the turbulent intensity was higher than other place because of the edge effect.The farther from the opening.the more well-distributed flow field performed. If there was a mannequin standing or sitting before the exhaust hood,great changes took place in the flow field.Comparing with the free exhaust hood,the velocities in the vicinity of the mannequin became smaller .turbulent intensity became bigger and a big turbulent region was formed because of mannequin hindering. When the exhaust hood was installed on the working platform before the mannequin.the effective suction scope of the hood was increased on account of the working platform.so the velocities within the measurement range became bigger.