When considering the flow of a two-phase mixture, the complete characterization of its behavior requires not only the evaluation of its temperature and pressure evolutions, but also the description of the distribution of the phases (the so-called "flow structure"). This is of great importance in problems concerning the analysis of the solicitations undergone by the containing ducts, both from a mechanical point of view and even more important when heat transfer at fixed power is involved. In the present paper some methodologies are presented, which proved to be very useful in the description and quantitative visualization of the structure of a two-phase flow: for liquid gas mixtures, they are based on relatively simple experimental acquisitions of a single quantity and allow a detailed visualization of the flow structure without requiring visual observation of the same.