Subsonic Venturi Interaction With Free-Stream Flow

Numerical and experimental investigations of a venturi flow into a cross flow have been performed. The numerical analyses were performed using the CD-Adapco CCM+ commercial software with non-uniform mesh and the standard k-ε turbulence model. The analyses were performed for the venturi outlet directly connected to the bottom surface of the wind tunnel and for the venturi connected to the wind tunnel bottom surface with a 15.24 cm long tube extension of the same diameter. The experimental investigations were carried out in a subsonic open-circuit wind tunnel facility of the Center for Energy and Environmental Research and Services (CEERS) in conjunction with a single hot wire sensor and a LabView-National Instrument data acquisition system. For the experimental investigations, the venturi was connected to the bottom surface of the wind tunnel without the extension tube. For the numerical investigations, the ratios of the venturi flow momentum to the cross flow momentum, r, were 0.25, 0.5, 0.75, and 1.0. For the experimental investigations, the momentum ratios were 0.5, 0.85, and 1.0. For all analyses, isothermal condition is assumed. Results indicate when r = 0.25 and 0.5, the venturi flow is confined to an area near the wind tunnel surface with high static pressure within the venturi and the extension tube. However, for momentum ratios higher than 0.5, the venturi flow penetrates into the cross flow, before being tilted into the cross flow. For high r values, there is a counter-rotating vortex pair which grows in downstream direction. The adverse pressure gradient upstream of the venturi flow affects the flow characteristics inside the venturi at low momentum ratios. However, there were no indications of flow separation or flow recirculation within the venturi or the extension tube.