Velocity measurements in confined dual coaxial jets behind an axisymmetric bluff body: Isothermal and combusting flows

Measurements were made of the axial component of the flowfield in an Air Force combustion tunnel facility at Wright-Patterson Air Force Base. The tunnel is characterized by a bluff body, centered in the airflow duct, through which fuel can flow. The annular air flow around the centerbody creates a recirculation zone in the wake behind the bluff body. The recirculating flow interacts with the fuel jet and five distinct regimes of operation are delineated. Radial and axial profiles of the flowfield were made in isothermal and combusting flows. The free-jet behavior is that anticipated from other studies. A distinction from previous workers' data is the report herein of the existence of distinct modes in the velocity probability density functions. With both annular and fuel jets flowing, measurements were made of the fuel and air stagnation points along the centerline, in both isothermal and combusting flows.