COAXIAL JETS FROM LOBED-MIXER NOZZLES

Experiments were conducted to study the jet dynamics of unconfined and confined coaxial high-speed flows from radially lobed nozzles. The sh ear-layer growth rate of the lobed nozzles was found to be considerabl y higher than that of a conical nozzle, Pressure profiles indicated in creased radial uniformity and transport of properties between flows. I ncreases in lobe height and number of lobes were associated with enhan ced mixing and larger total pressure drops. The thrust loss observed w as due primarily to divergent nozzle flow and duct friction losses. Us e of a confining duct forced interaction of the Bows and enhanced mixi ng. Compression of the primary flow produced intense compression-expan sion regions in the flowfield. Another advance over earlier studies is the visualization of the axial vortices generated by lobed nozzles. T hese vortices can be linked to the observed cross-plane transport of p roperties.