3D reconstruction of transparent gaseous jet flow using BOS tomography reconstruction technique

Abstract This study presents a 3D reconstruction method for transparent gaseous jet flows using Background Oriented Schlieren (BOS) tomography combined with the Algebraic Reconstruction Technique (ART) and Tikhonov regularization. The approach aims to provide a diagnostic and visualization tool for the gas flow fields generated by hydrogen injectors in internal combustion engines. The BOS technique, which analyses background pattern displacements caused by refractive index gradients in the flow, is extended here to three dimensions using ART to directly reconstruct the refractive index field. This enables the characterization of complex, asymmetric gas jet flows, even in simplified experimental setups. The results demonstrate that the method can effectively reconstruct the 3D mole fraction distribution of the jet, which is useful for analyzing the mixing characteristics of the flow. Experimental validation, conducted using helium jets, confirms the feasibility of the proposed method for 3D diagnostics of transparent gas flow fields, with potential applications in optimizing hydrogen combustion in internal combustion engines.