Experiment determining pressure loss reduction using a shaped round exhaust hood

Abstract

In this study, we experimentally determined the local drag coefficient (LDC) of a round exhaust hood that was improved with different shaped inlet sections along the boundaries of the vortex zones occurring in the flow at the inlet of an exhaust hood. The LDC measurements were performed using two methods. The first method used a micromanometer and pneumometric tube to determine the LDC with and without considering frictional losses. Meanwhile, the second method determined the LDCs using the pressure and velocity distributions in the boundary layer with specially designed pressure miniprobes. The experimental and numerical results show that it is possible to achieve a drag reduction of more than 90% by shaping the inlet edges of the exhaust hood. This increases the range of contaminant capture, reduces noise, and prevents contaminants from escaping from the exhaust hood by eliminating the vortex zones and reducing the fan power.