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This study is devoted to experimental and theoretical investigation of splash produced by spray impact onto a smooth, rigid target under microgravity conditions. In particular, the formation of a film by the deposited liquid, the propagation and breakup of uprising sheets created by drop impacts, and the creation of secondary droplets have been observed. Three scenarios of splash have been identified during the experiments: (i) cusp formation and jetting due to the rim transverse instability, (ii) sheet destruction and the consequent rapid axisymmetric capillary breakup of a free rim, and (iii) the rim merging. Experimental data for various geometrical parameters of splash have been collected. Next, in order to predict the typical length scales of the interjet distance, a linear stability analysis of the rim in relation to transverse disturbances has been performed. The influence of the sheet stretching has been investigated and shown to be significant. The experimentally measured average values of the interjet distances agree well with the theoretical predictions. The sheet stretching is responsible for the appearance of the relatively long interjet distances.

This study examines the flow field in three axisymmetric expansions having diffuser half-angles of 14, 18, and 90 deg, respectively. Velocity measurements were performed at a Reynolds number of Re = 1.56 × 104 using a single component LDA operated in forward scatter. The test facility was refractive index matched, allowing measurement of the velocities U, V, W, u2, v2, w2, uv and uw upstream of, and throughout the entire recirculation region. The results indicate that the diffuser geometry influences the separated shear layer appreciably over the entire length of the diffuser section. The production of turbulence immediately after separation is much higher in the case of the 14 and 18 deg diffuser compared to the 90 deg expansion, leading to higher diffusion rates in the separated shear layer, and hence earlier reattachment of the shear layer.