Experimental investigation of a supersonic close-coupled atomizer employing the phase Doppler measurement technique

Along with the growing economic importance of metal additive manufacturing by means of laser powder bed fusion, the demand for high-quality metal powders as the corresponding raw material is also increasing. However, the physics involved in supersonic close-coupled gas atomization, which is often employed for the production of these powders, are not well understood and extensive experimental data is scarce, leading to a lack of reliable predictive modeling capabilities.

In this experimental study, local particle size and velocity distributions for the spray produced by a generic supersonic close-coupled atomizer are obtained using the phase Doppler measurement technique. The gas stagnation pressure and the liquid mass flow rate are varied systematically and independently. Three working liquids are considered, investigating the influence of the liquid dynamic viscosity on the atomization result.

The particle size is shown to be sensitive to changes in both the gas stagnation pressure and the liquid mass flow rate. Notably, it is not an unambiguous function of the gas-to-liquid ratio. Furthermore, the effect of the liquid dynamic viscosity appears to be negligible. In conclusion, these are important insights for formulating physics-based models for the supersonic close-coupled atomization process.