Visualization and scaling of charged droplet transport in gas jet crossflows at near- and sub-atmospheric pressures are presented to describe the physics of droplet-gas interactions and predict when gas jets can redirect droplet trajectories. Laser scattering of electrospray and schlieren photography of gas jet expansion are employed to assess charged droplet-gas interactions in variable pressure environments. Experimental results reveal that the greatest gas influence on droplet trajectories occurs at intermediate pressures ($P/P_{\mathrm{atm}}=2.1\times {10}^{-2}$), when gas jets achieve supersonic velocities and exert substantial drag before rarefaction effects become significant. A fundamental understanding of the underlying physics is gained through a scaling analysis for an individual charged droplet's transport that introduces a dimensionless parameter, representing the ratio of gas drag to the maximum of the electric or inertial force, to predict droplet deflection in a gas crossflow. This dimensionless parameter that can be predicted analytically using the experimentally controlled inputs is shown to effectively capture the behavior without the need for complex and computationally expensive multiphysics simulations. Comparisons with experimental results and computational fluid dynamics and electrostatic simulations validate the scaling framework while identifying limitations of continuum models at high Knudsen numbers. These results delineate distinct regimes of droplet transport and provide a predictive foundation for droplet control strategies by gas jets for numerous engineering applications.

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• Compressible flows
• Drop interactions
• Electrohydrodynamic effects
• Flow control
• Rarefied flows