Vortex dynamics studies in supersonic flow: Merging of co-rotating streamwise vortices

Abstract

For air-breathing propulsion systems intended for flight at very high Mach numbers, combustion is carried out at supersonic velocities and the process is mixing limited. Substantial increase in mixing rates can be obtained by fuel injection strategies centered on generating selected modes of supersonic, streamwise vortex interactions. Despite the recognized importance, and potential of the role of streamwise vortices for supersonic mixing enhancement, only few fundamental studies on their dynamics and interactions have been conducted, leaving the field largely unexplored. A reduced order model that allows the dynamics of complex, interacting, supersonic vortical structures to be investigated, is presented in this work. The prediction of the evolution of mutually interacting streamwise vortices represents an enabling element for the initiation of an effective, systematic experimental study of selected cases of interest, and is an important step toward the design of new fuel injection strategies for supersonic combustors. The case presented in this work is centered on a merging process of co-rotating vortices, and the subsequent evolution of a system composed of two counter-rotating vortex pairs. This interaction was studied, initially, with the proposed model, and was chosen for the peculiarity of the resulting morphology of the vorticity field. These results were used to design an experimental investigation with the intent to target the same specific complex flow physics. The experiment revealed the same peculiar features encountered in the simulation.

Experimental and Numerical Investigation of the Flow Characteristics of a Strut Injector for Scramjets

“…A detailed description of the theory, assumptions, and implementation of the model is found in Ref. 13. In brief, VorTx relies upon the slender body approximation and the hypersonic equivalence principle to transform the 3D steady flow to a 2D unsteady flow in which the behavior and evolution of the vortical system is calculated using a vortex filament model based upon supersonic lifting line theory where the induced velocities of each filament upon the others, within their respective domains of influence (Mach cone), are calculated.…”

Supersonic Combustion of Pylon-Injected Hydrogen in High-Enthalpy Flow with Imposed Vortex Dynamics

“…With this model, the flowfield can be computed once the Mach number of the flow in which the vortices are shed, the convective velocity, the initial relative position of the vortices, and an estimation of the circulation of the large-scale structures are known. A detailed description of the model is provided in [20].…”

“…The reduced-order model developed by the University of Texas at Arlington group [20] has been used to produce the simulation of two distinct vortical systems. In the first case, a symmetric disposition of the vortices in the flowfield was chosen; the second case was meant to emphasize the effect of the dynamics of the vortical structures in an asymmetric configuration.…”

Experimental Study of Strut Injectors for Scramjet Combustors: Total Pressure Losses in a Selected<br /> Supersonic Streamwise Vortex Interaction Mode

“…The interaction capability of supersonic streamwise vortices has been well-documented in the combined theoretical and experimental effort of Maddalena et al, 12 where an inviscid reduced order model suitable for the prediction of their complex dynamics was described. The simulations resulting from the code in which the model was implemented (VorTx) were used to design an experimental campaign aimed at studying the merging of co-rotating vortices in supersonic flow.…”