RP-524 -- Development of Loss Coefficient Data for Compound Exhaust Hoods Using Slots for Air Distribution PDF

Experimental exhaust hoods were designed \/hich allowed many variations to be made on two basic types of hood that use slots for air distribution: 90 degree takeoff and straight takeoff. A test and data acquisition facility was designed and set up where tests were performed on 40 different exhaust hood configurations. Experimental data on air distribution, hood loss, slot loss, and duct entry loss were collected at three flowrates for each hood. Detailed velocity profile data for the exhausted area in front of the hoods were also collected for three of the hood configurations. These data showed that the hood loss coefficient varied significantly with hood configuration but was insensitive to changes in slot velocity. Straight takeoff hoods tended to have lower loss coefficients and better air distribution than 90 degree takeoff hoods. Baffles were shown to raise air velocities in front of the hood.' Theoretical hood loss coefficients, calculated by current methods, were shown to be accurate for some simple exhaust hood configurations but significantly in error for others.