High-speed astigmatic dual-beam interferometric particle imaging for direct depth displacement and velocity measurement of metal droplet

Abstract

High-speed astigmatic dual-beam interferometric particle imaging (HADIPI) is adopted to simultaneously measure the three-dimensional (3D) position, velocity and size of spherical metal droplets. We propose to infer the depth displacement of the droplet directly from the angle shift of the interference fringe. Angular cross power spectral density is used to detect the angular shifts of the interference fringe. The depth displacements and velocities can be further obtained from the obtained angular shifts. Proof-of-concept experiments are conducted on micron-sized gallium droplets, demonstrating that the 3D trajectories of the droplets can be accurately obtained, with depth displacement accuracy of tens of microns, improving accuracy in depth position measurement compared to the traditional Lagrangian framework. Different from traditional imaging methods, HADIPI can directly display the 3D movement of droplets, including in the depth direction. In the combustion measurements of the solid rocket motor, the motion state of metal droplets can be precisely determined, demonstrating the feasibility and practicality.