The effect of background air turbulence on liquid spray

The properties and behavior of spray droplets are crucially affected by background turbulence. While this has far-reaching consequences e.g. in combustion systems, the effect of background turbulence on liquid spray has not been systematically studied and is not well understood. We experimentally investigate the properties of a liquid spray produced by a hollow-cone nozzle and injected into a large air chamber. The latter contains two planar arrays of individually actuated jets that can be fired in randomized sequence to produce a large region of homogeneous turbulence. We characterize the properties of the spray issued in quiescent and turbulent air, and in particular: the spray penetration, its mixing with the surrounding air, and the droplet size distribution. To this end, we perform planar imaging over a range of spatial and temporal resolutions. Focusing on a window in the far field, we perform particle tracking velocimetry using a high-speed laser and camera system, and droplet sizing by shadowgraphy using a high-resolution camera mounted on a long-range microscope and synchronized with a pulsed LED. We characterize droplet size, local concentration, and velocity, gaining insight on the spray dynamics and its interaction with turbulence.