Visualization of Muzzle Flow and Projectile in Flight Flow Using the Background Oriented Schlieren Technique

Abstract

The present paper focuses on the development of a non-intrusive measurement technique and the implementation of a quantitative flow visualization method based on Background Oriented Schlieren (BOS). The gun muzzle flow, the aerodynamics, and the ambient airprojectile interaction are visualized. In BOS, the experimental set-up of conventional Schlieren (mirrors, lenses, and knife-edge) is replaced by a background pattern and a single digital camera. The proposed measurement technique and the implemented algorithm are first validated through the temperature measurement of a flame-induced distorted flow field. An acceptable accuracy is recorded, the measurement error being less than 3-5% of the full scale. Second, the muzzle flow and the flow field around a 5.56 mm projectile in free flight was captured and analyzed. The captured structures such as vortex, barrel shock, Mach disk, and blast wave show a good agreement with those issued from the conventional Schlieren set-up