Experimental validation of potential and turbulent flow models for a two-dimensional jet enhanced exhaust hood

A two-dimensional jet-reinforced slot exhaust hood was modeled using a mathematical model based on potential flow theory and with a computational fluid dynamics (CFD) model using the standard k-∊ model for turbulence closure. The accuracy of the calculations was verified by air velocity and capture efficiency measurements. The comparisons show that, for normal operating conditions, both the models predicted the mean airflows in front of the hood well. However, the CFD model gave more realistic results in the jet flow region and also of the short-circuiting flow. Both models became increasingly inaccurate when the ratio of the supply jet momentum to the exhaust flow rate increased. The jet enhancement proved to be a very efficient way to increase the effective control range of exhaust hoods. Controlled air movements can be created at distances that are two to three times larger than with conventional suction alone without increasing the exhaust flow rate.