About

Owen Smith is a Professor Emeritus in the Department of Mechanical and Aerospace Engineering at UCLA Samueli School of Engineering. His research interests include combustion and combustion-generated air pollutants, hydrodynamics and chemical kinetics of combustion systems, and semiconductor chemical vapor deposition. His work focuses on understanding the fundamental processes involved in combustion and related phenomena, contributing to advancements in environmental and materials engineering.

Research topics

• Chemistry
• Mechanics
• Materials science
• Environmental science
• Physics

Selected publications

• Structural and stability characteristics of jets in crossflow – CORRIGENDUM

  Journal of Fluid Mechanics · 2020-03-20

  erratumOpen access

  An abstract is not available for this content. As you have access to this content, full HTML content is provided on this page. A PDF of this content is also available in through the ‘Save PDF’ action button.

  PublisherOA PDFDOI

• Effects of Inert and Energetic Nanoparticles on Burning Liquid Ethanol Droplets

  Combustion Science and Technology · 2018-08-21 · 24 citations

  article

  The effect of nanoscale energetic aluminum (nAl) and inert silicon dioxide (nSiO2) particulate additives on ethanol droplet combustion was studied under atmospheric conditions. Three different types of droplet experiments were performed to study the influence of the experiment itself on combustion behavior. Simultaneous visible and intensified ultraviolet (UV) images were taken to determine the burning rate constant (K) as well as flame dynamics via OH* chemiluminescence imaging. The addition of nAl appeared to yield a systematic increase in K, by up to 13%, and increasing loading concentrations led to changes in droplet combustion dynamics. Flow instabilities, including liquid jetting and altered droplet deformation, were observed, creating unsteady combustion when the nAl-laden droplet was continuously fed via a quartz capillary. In contrast, the addition of nSiO2 showed relatively small changes in K, possibly only as large an increase as 5%, with a lack of consistent trends for increasing nSiO2 concentration for different fuel delivery methods, in part due to the formation of large residual shell-like structures in the later stages of combustion. A simple droplet combustion model suggests that possible enhancement mechanisms for K are related to alterations in thermal conductivity as well as flame temperature with the nAl additive. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images of particulate residue revealed further differences in morphology and residue constituents after combustion.

  PublisherDOI

• Periodic partial extinction in acoustically coupled fuel droplet combustion

  Combustion and Flame · 2017-11-06 · 46 citations

  articleOpen access
  PublisherOA PDFDOI

• Transverse jet mixing characteristics

  Journal of Fluid Mechanics · 2016-02-02 · 61 citations

  article

  This experimental study explores and quantifies mixing characteristics associated with a gaseous round jet injected perpendicularly into cross-flow for a range of flow and injection conditions. The study utilizes acetone planar laser-induced fluorescence imaging to determine mixing metrics in both centreplane and cross-sectional planes of the jet, for a range of jet-to-cross-flow momentum flux ratios ( $2\leqslant J\leqslant 41$ ), density ratios ( $0.35\leqslant S\leqslant 1.0$ ) and injector configurations (flush nozzle, flush pipe and elevated nozzle), all at a fixed jet Reynolds number of 1900. For the majority of conditions explored, there is a direct correspondence between the nature of the jet’s upstream shear layer instabilities and structure, as documented in detail in Getsinger et al. ( J. Fluid Mech. , vol. 760, 2014, pp. 342–367), and the jet’s mixing characteristics, consistent with diffusion-dominated processes, but with a few notable exceptions. When quantified as a function of distance along the jet trajectory, mixing metrics for jets in cross-flow with an absolutely unstable upstream shear layer and relatively symmetric counter-rotating vortex pair cross-sectional structure tend to show better local molecular mixing than for jets with convectively unstable upstream shear layers and generally asymmetric cross-sectional structures. Yet the spatial evolution of mixing with downstream distance can be greater for a few specific convectively unstable conditions, apparently associated with the initiation and nature of shear layer rollup as a trigger for improved mixing. A notable exception to these trends concerns conditions where the equidensity jet in cross-flow has an upstream shear layer that is already absolutely unstable, and the jet density is then reduced in comparison with that of the cross-flow. Here, density ratios below unity tend to mix less well than for equidensity conditions, demonstrated to result from differences in the nature of higher-density cross-flow entrainment into lower-density shear layer vortices.

  PublisherDOI

• Structural and stability characteristics of jets in crossflow

  Journal of Fluid Mechanics · 2014-11-07 · 78 citations

  article

  Abstract This experimental study examines the relationship between transverse jet structural characteristics and the shear layer instabilities forming on the upstream side of the jet column. Jets composed of mixtures of helium and nitrogen were introduced perpendicularly into a low-speed wind tunnel using several alternative injectors: convergent circular nozzles mounted either flush with or elevated above the tunnel floor, and a flush-mounted circular pipe. Both non-intrusive optical diagnostics (planar laser-induced fluorescence (PLIF) and particle image velocimetry (PIV)) and intrusive probe-based (hot-wire anemometry) measurements were used to explore a range of jet-to-crossflow momentum flux ratios and density ratios for which previous studies have identified upstream shear layer transition from convective to absolute instability. Remarkable correspondences were identified between formation of the well-known counter-rotating vortex pair (CVP) associated with the jet cross-section and conditions producing strong upstream shear layer vorticity rollup, arising typically from absolute instability in the shear layer. In contrast, asymmetries in the jet mean cross-sectional shape and/or lack of a clear CVP were observed to correspond to weaker, convectively unstable jet shear layers.

  PublisherDOI

• Droplet combustion in the presence of acoustic excitation

  Combustion and Flame · 2014-01-14 · 30 citations

  article
  PublisherDOI

• Structural and Stability Characteristics of Jets in Crossflow

  52nd Aerospace Sciences Meeting · 2014-01-10

  article
  PublisherDOI

• Shear-Coaxial Jets in a Transverse Acoustic Field at High Pressures

  2009-06-01

  reportSenior author

  Abstract : The goal of this research effort has been to perform experiments on and explore the physics associated with a non-reactive, cryogenic, shear coaxial jet interacting with high pressure, high amplitude acoustic waves. These experiments have been conducted in the AFRL cryogenic supercritical laboratory facility at Edwards AFB by a UCLA graduate student Juan Rodriguezas part of his Ph.D. dissertation. The flow configuration, which is similar to that, typically used in cyrogenic liquid rocket systems, allows exploration of the effect of phase and amplitude on chamber acoustic interactions with a shear coaxial jet operating under subcritical, relevance of the observed jet response to phenomena associated with self excitation in liquid rocket combustion instabilities. The effects of magnitude and phase of the acoustic field generated within the chamber on non-reactive coaxial jet dark core lengths and spreading angles have been explored in detail for two alternative injector geometries.

  PublisherDOI

• Acoustic excitation of droplet combustion in microgravity and normal gravity

  Combustion and Flame · 2005-09-24 · 29 citations

  article
  PublisherDOI

• Passive Fuel-Air Mixing and Emissions Control Via Lobed Injectors

  AIAA Journal · 2004-01-01 · 13 citations

  article

  This experimental study examined the effects of differing levels of passive fuel-air premixing on flame structures and their associated NO x and CO emissions. Four alternative fuel injector geometries were explored, three of which had lobed shapes. Prior experimental studies of two of these lobed injector flowfields focused on nonreactive mixing characteristics (Smith, L. L., Majamaki, A. J., Lam, I. T., Delabroy, O., Karagozian, A. R., Marble, F. E., and Smith, O. I., Mixing Enhancement in a Lobed Injector, Physics of Fluids, Vol. 9, No. 3, 1997, pp. 667-678) and emissions measurements in the absence of air confinement [Mitchell, M. G., Smith, L. L., Karagozian, A. R., and Smith, O.I., Burner Emissions Associated with Lobed and Non-Lobed Fuel Injectors, Twenty-Seventh Symposium (International) on Combustion, The Combustion Inst., Pittsburgh, PA, 1998, pp. 1825-1831]. The present studies examined the effects of confinement of the crossflow to reduce the local equivalence ratio as well as the effects of altering the geometry and position of the flameholders to further influence passive fuel-air premixing. NO x and CO emissions as well as flame photographs and planar laser-induced fluorescence imaging of seeded acetone were used to characterize injector performance and fuel and flame evolution. It was found that, with significant air confinement, forcing a more intimate mixing between fuel and air before ignition and flameholding, both NO x and CO emissions could be simultaneously reduced under the same operating conditions via this passive flow control technique.

  PublisherDOI

Frequent coauthors

• Ann Karagozian

  University of California, Los Angeles

  29 shared

• Spyros I. Tseregounis

  6 shared

• Mark G. Mitchell

  5 shared

• Christopher Cadou

  5 shared

• J.W. Willis

  University of California, Los Angeles

  5 shared

• Roy Marchant

  4 shared

• Pamela Logan

  University of California, Los Angeles

  4 shared

• Levon Gevorkyan

  University of California, Los Angeles

  3 shared