Despite the recognized importance of streamwise vortices in the enhancement of fuel/air mixing processes in scramjet combustors, the effects of their interactions and dynamics on mixing and associated total pressure losses are still relatively unexplored. This work presents the first systematic effort to find answers to fundamental questions such as: can selected vortex interactions be identified and effectively used in an injection system for scramjets? Is the increase of streamwise vorticity content, regardless of its spatial distribution in the flow, always beneficial for entrainment and molecular mixing? Is it possible to apply vortex dynamics concepts in reacting flows? For this reason the dissertation covers the study of selected vortex interaction scenarios both in cold and high enthalpy reacting flows. Specifically, the experimental results and the analysis of the flowfields resulting from two selected supersonic vortex interaction modes in a Mach 2.5 cold flow are presented. Additionally, the experiment design based on vortex dynamics concepts and the reacting plume survey of two pylon injectors in a Mach 2.4 high enthalpy flow are shown. The cold flow experiments were conducted in the supersonic wind tunnel of the Aerodynamics Research Center at the University of Texas at Arlington. A strut injector equipped with specified ramp configurations was designed and used to produce the flowfields of interest. The reacting flow experiments were conducted in the Expansion Tube Facility located in the High Temperature Gasdynamics Laboratory of Stanford University. A detailed description of the supersonic wind tunnel, the instrumentation, the strut injector and the supersonic wake flow downstream is shown as part of the characterization of the facility. As stereoscopic particle image velocimetry was the principal flow measurement technique used in this work to probe the streamwise vortices shed from ramps mounted on the strut, this dissertation provides a deep overview of the challenges and the application of the aforementioned technique to the survey of vortical flows. Moreover, the dissertation provides a new and comprehensive analysis of the flow physics associated with these complex supersonic vortical interactions. The mean and fluctuating velocity flowfields of two selected vortex dynamics scenarios, chosen based on the outcomes of the simulations of an inviscid reduced order model developed in the research group, are presented. The same streamwise vortices (strength, size and Reynolds number) were used experimentally to investigate both a case in which the resulting dynamics evolve in a vortex merging scenario and a case in which the merging process is voluntarily avoided in order to focus the analysis on the fundamental differences associated with the amalgamation processes alone. The results from the mean flow highlight major differences between the two cases and corroborate the use of an inviscid model for the prediction of the main flow physics in the times scales considered. The analysis is also extended to turbulence quantities and concepts borrowed from incompressible turbulence theory (i.e., fluctuating Mach numbers “ 1) appear to explain interesting features of the fluctuating flowfields. Once the interactions among the vortical structures in cold flow were assessed, these vortex dynamics concepts were probed in a reacting environment. The dissertation describes the design phase of two pylon injectors based on the prediction capabilities of the aforementioned model. Then, the results of a set of combustion experiments conducted utilizing hydrogen fuel injected into a Mach 2.4, high-enthalpy (2.8 MJ/kg) air flow are discussed. The results show that, for the heat release levels considered in this study, the morphology of the plume and its evolution are remarkably close to the results produced by the model, enabling an interpretation based on vortex dynamics considerations. The persistence of the streamwise vortical structures created by the selected ramp configurations is shown together with the effectiveness of the coherent structures in successfully anchoring the flame very close to the injection point. The work shows the possibility of a new approach in the design of injection strategies (not limited to injection devices) suitable for adoption in scramjet combustors based on the ability to predict, with basic vortex dynamics concepts and a highly reduced computational cost, the main features of flows of technological interest.