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Papers by Marios Soteriou

APS Division of Fluid Dynamics Meeting Abstracts, Nov 1, 2015

Journal of Propulsion and Power, 2013

AIAA SCITECH 2022 Forum, Jan 3, 2022

ABSTRACT We examine the effect of time-dependent forcing on jet-in-crossflow atomization in the c... more ABSTRACT We examine the effect of time-dependent forcing on jet-in-crossflow atomization in the case of pulsed liquid injection and uniform crossflow. The dynamics of the jet is captured by a numerical approach that blends interface tracking of the liquid surface with an empirical description of the atomization process. The unsteady Reynolds-Averaged Navier-Stokes equations for the gas and the continuous (i.e., preceding breakup) liquid phase are solved simultaneously with the Lagrangian equations for the droplet trajectories. This approach captures the near field transient due to the opening (closing) of the fuel valve, as well as the convective delay of the spray in the far field. Validation is carried out with Phase Doppler Interferometry (PDI) and Mie scattering measurements at standard conditions for pulsed jets of water and ethanol in crossflow air. The discussion is focused on the shape of the convecting spray pulse and on the trends due to variations in crossflow and jet velocities.

Combustion and Flame, Dec 1, 2011

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1993.Inc... more Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1993.Includes bibliographical references (p. 223-226).by Marios C. Soteriou.Ph.D

We study the role of jet-induced wake and vortical structures on the transport of drops formed by... more We study the role of jet-induced wake and vortical structures on the transport of drops formed by mass stripping and jet breakup due to crossflowing gas. Gas and liquid phases are computed as a single-fluid Eulerian continuum by tracking the gas-liquid interface with a Volume of Fluid (VOF) methodology. Droplets (numerically treated as parcels) are injected at fixed locations near the jet, based on near-field experimental observations. Their trajectories are evolved in time so that patterns of volumetric flux, axial velocity and Sauter Mean Diameter (SMD) can be compared with experimental measurements in the far field. We find that vortical structures due to aerodynamic blockage are maintained up to several orifice diameters downstream of the jet, affecting the droplet trajectories and ultimately the spray distribution. We also demonstrate that an interface-tracking algorithm for capturing the jet bulk features allows the prediction of far field spray characteristics when coupled to a simple set of rules for spray distribution after primary breakup.

Combustion and Flame, 2015

AIAA Scitech 2019 Forum, 2019

36th AIAA Aerospace Sciences Meeting and Exhibit, 1998

The impact of the inlet conditions on particle/droplet dispersion in a post-transitional shear la... more The impact of the inlet conditions on particle/droplet dispersion in a post-transitional shear layer is investigated using two-dimensional numerical simulations. The flow inlet conditions are varied between a monotonically changing inlet velocity profile (errorfunction) and one that exhibits a wake deficit reminiscent of the presence of the upstream splitter plate. The particle field inlet conditions are varied by altering the particle inlet location. Monodisperse dilute particle fields of various diameters are considered. The numerical models for both the time-dependent and un-averaged flow and particle fields are Lagrangian yielding a totally grid-free approach. The well known relationship between the particle Stokes number and dispersion is verified. Results also indicate that, under most conditions, dispersion is increased if particles are introduced from the fast stream side and as close as possible to the layer centerline. This trend is more pronounced for the wake-modified than the error-function inlet profile flow. The impact of the Stokes number on this trend is secondary. This suggests that the origin of this behavior lies in the flow dynamics which is known to favor entrainment from the fast stream. For the error-function case the dispersion trend is reversed if particles are introduced far enough from the shear layer so that they do not get entrained into the rotational flow. This is due to the tendency of the shear layer to tilt towards the slow stream. For the wake-modified case, however, this reversal does not occur. This, and the above noted enhanced asymmetry in the dispersion patterns for this case are attributed to the presence of positive vorticity on the slow speed side of the shear layer. This vorticity, which is counter-rotating with respect to the overall vorticity field has its origin in the inlet condition. While its effect on the large scale flow structure is secondary, it tends to weaken the entrainment patterns locally and thus diminishes the entrainment and subsequent dispersion of particles. Copyright © 1998 by M. C. Soteriou. Published by the American Institute of Aeronautics and Astronautics, Inc. with permission. T Assistant Professor, member AIAA. ? Graduate Student.

Bulletin of the American Physical Society, 2011

ABSTRACT High fidelity, first principles simulation of atomization of a liquid jet by a fast cros... more ABSTRACT High fidelity, first principles simulation of atomization of a liquid jet by a fast cross-flowing gas can help reveal the controlling physics of this complicated two-phase flow of engineering interest. The turn-around execution time of such a simulation is prohibitively long using typically available computational resources today (i.e. parallel systems with ˜O(100) CPUs). This is due to multiscale nature of the problem which requires the use of fine grids and time steps. In this work we present results from such a simulation performed on a state of the art massively parallel system available at Oakridge Leadership Computing Facility (OLCF). Scalability of the computational algorithm to ˜2000 CPUs is demonstrated on grids of up to 200 million nodes. As a result, a simulation at intermediate Weber number becomes possible on this system. Results are in agreement with detailed experiment measurements of liquid column trajectory, breakup location, surface wavelength, onset of surface stripping as well as droplet size and velocity after primary breakup. Moreover, this uniform grid simulation is used as a base case for further code enhancement by evaluating the feasibility of employing Adaptive Mesh Refinement (AMR) near the liquid-gas interface as a means of mitigating computational cost.

ABSTRACT Atomizing liquids by injecting them into crossflows is a common approach to generate fue... more ABSTRACT Atomizing liquids by injecting them into crossflows is a common approach to generate fuel sprays in gas turbines and augmentors. The mechanisms by which the liquid jet initially breaks up, however, are not well understood. To analyze the instability mechanism of the liquid column, we perform proper orthogonal decomposition of side view images extracted from detailed simulations of the near injector primary atomization region. This analysis shows a single dominant wavelength with the associated interface corrugation traveling downstream with the jet. Using consistent temporal averaging of the simulation data we extract mean interface geometries and boundary layer velocity profiles. These are used to calculate the most unstable wavelength of the shear layer instability following the procedure of Boeck & Zaleski (2005). The theoretical wavelengths are comparable to those extracted from the simulation data. In addition to shear layer instability we analyze Rayleigh-Taylor as a potential instability mechanism of the liquid column.

Physics of Fluids, 2016

Recent advances in numerical methods coupled with the substantial enhancements in computing power... more Recent advances in numerical methods coupled with the substantial enhancements in computing power and the advent of high performance computing have presented first principle, high fidelity simulation as a viable tool in the prediction and analysis of spray atomization processes. The credibility and potential impact of such simulations, however, has been hampered by the relative absence of detailed validation against experimental evidence. The numerical stability and accuracy challenges arising from the need to simulate the high liquid-gas density ratio across the sharp interfaces encountered in these flows are key reasons for this. In this work we challenge this status quo by presenting a numerical model able to deal with these challenges, employing it in simulations of liquid jet in crossflow atomization and performing extensive validation of its results against a carefully executed experiment with detailed measurements in the atomization region. We then proceed to the detailed analysis of the flow physi...

Atomization and Sprays, 2013

Bulletin of the American Physical Society, 2017

Submitted for the DFD17 Meeting of The American Physical Society High Fidelity Simulation of Tran... more Submitted for the DFD17 Meeting of The American Physical Society High Fidelity Simulation of Transcritical Liquid Jet in Crossflow XIAOYI LI, MARIOS SOTERIOU, United Technologies Research Center — Transcritical injection of liquid fuel occurs in many practical applications such as diesel, rocket and gas turbine engines. In these applications, the liquid fuel, with a supercritical pressure and a subcritical temperature, is introduced into an environment where both the pressure and temperature exceeds the critical point of the fuel. The convoluted physics of the transition from subcritical to supercritical conditions poses great challenges for both experimental and numerical investigations. In this work, numerical simulation of a binary system of a subcritical liquid injecting into a supercritical gaseous crossflow is performed. The spatially varying fluid thermodynamic and transport properties are evaluated using established cubic equation of state and extended corresponding state pr...

ABSTRACT A numerical model of dilute evaporating sprays in which both the gas and liquid phases a... more ABSTRACT A numerical model of dilute evaporating sprays in which both the gas and liquid phases are tracked in a Lagrangian frame of reference, is presented. The model uses high order integration schemes for the treatment of the transport of the phases and deals with the phase interaction in a fundamental way. It is validated by contrasting results from it with analytical solutions obtained for various canonical flows such as the stagnation point flow and the point vortex flow. The analytical solutions are obtained by imposing additional simplifying assumptions to the governing equations. A comparison is performed between the proposed Lagrangian-Lagrangian modeling approach and the more traditional Eulerian-Lagrangian approach. In this latter approach the gas phase is treated in a Eulerian frame of reference. It is shown that irrespective of which approach is used the modeling of sprays suffers from ambiguities inherent in the governing equations. In addition, however, the Eulerian-Lagrangian approach is constrained by limitations that do not exist in the Lagrangian-Lagrangian approach. Numerical treatments that limit the impact of these limitations in the Eulerian-Lagrangian approach are proposed. Finally, the Lagrangian-Lagrangian model is demonstrated in a more complex flow, namely the shear layer between two streams of fluids of different velocities in which one of the streams is seeded with evaporating liquid droplets. Results indicate that the model effectively captures the dynamics of the two-phase flow.