Scaling of Fully Pulsed Jets in Crossflow

TLDR: In this article, a classification scheme for fully pulsed jets in uniform crossflow is proposed based on the stroke ratio of the jet pulse and the duty cycle of the pulse train.

Abstract: There is recent interest in the dynamics of pulsed jets in uniform crossflow. A classification scheme for fully pulsed Jets in crossflow is proposed based on the stroke ratio of the jet pulse and the duty cycle of the pulse train. Scaling relations for penetration and dilution of fully pulsed jets'in crossflow are derived from the self-similar scaling of turbulent vortex rings and puffs in quiescent media. Individual turbulent structures are assumed to drift freely with the crossflow in the proposed scaling. The penetration of fully pulsed jets scales with the fourth root of the velocity ratio, stroke ratio, and axial distance. The decay of mean concentration scales with the velocity ratio and axial distance to the -3/4th power. These scaling relations apply to distinct turbulent structures before any interaction between successive structures. The criteria for interaction among flow structures near the nozzle and in the far field are also presented.