Effects of nanoparticles on the instability of liquid jets in a gaseous crossflow

Abstract

Nanofluids have attracted interest for their high performance in enhancing heat transfer and improving combustion. However, few studies have investigated the influences of nanoparticles on spray processes. In this study, the surface waves, liquid column oscillation, and droplet size distribution of a nanofluid transverse jet were investigated at low gas Weber number. A new statistical image-processing method was proposed to identify the surface wavelength and jet oscillation amplitude. A new power index parameter was proposed to account for the effect of nanoparticles, and then introduced to correlate with the upwind wavelength and Sauter mean diameter (SMD) of nanofluid droplets in the far field. The results show that in bag breakup and multimode breakup, the wavelengths decrease along the jet flow direction while the amplitudes gradually increase in the initial stage. The characteristic wavelength and SMD diminish with the increase of nanoparticle concentration, and the oscillation angle of liquid column increases correspondingly. The nanoparticle additive at low concentration obviously enhances the flow instability and cavitation inside the jet. Therefore, the fineness and uniformity of nanofluid atomization in the far field are significantly improved.