Experimental investigation of the interaction between a water droplet and a shock wave above Mach 4

Abstract

Experimental results on the interactions between a single water droplet and a shock wave propagating at Mach number above 4 are presented in this paper. A detonation-driven shock-tube test facility is used to work within a Mach range at \({M}=4.3\) (high-supersonic regime) and \({M}=10.6\) (hypersonic regime), for which the maximum studied dimensionless times T are up to 9.4 and 5.5, respectively. For both Mach ranges, the initial droplet diameters typically vary between 430 and 860 \(\upmu \hbox {m}\) and the associated Weber numbers vary from \(5 \times 10^{4}\) to \(11 \times 10^{4}\). Ultra-high-speed cameras are used to record the evolution of the water droplet when the shock wave impacts it. Until \({T} \approx 2.5\), the qualitative and quantitative analyses of our frames show that the initial diameter as well as the Mach number studied have an apparent weak influence on the droplet dimensionless displacement. Beyond this time, the results for \({M}=10.6\) are more dispersed than the data for \({M}=4.3\) revealing a possible effect of the droplet size. One of the main results of this paper is that the droplet disappearance occurs at \({T}=[4.5\)–5.5] for \({M}=10.6\), while some mist is still present at \({T}>9\) for \({M}=4.3\). We note also that the droplet is always supersonic for \({M}=10.6\) whereas it becomes subsonic at \({T}\approx 3.5\) for \({M}=4.3\).