Development and Application of High-Speed Laser Visualization Techniques in Combustion Research

2017 ◽  
pp. 241-259
Author(s):  
Marcus Aldén ◽  
Mattias Richter
Keyword(s):  
High Speed ◽  
Laser Visualization ◽  
Visualization Techniques

Experimental Characterization of Intrinsic Properties Associated With Air-Assisted Liquid Jet and Liquid Sheet

2018 ◽  
Vol 140 (5) ◽  
Author(s):  
K. Balaji ◽  
V. Sivadas ◽  
Vishnu Radhakrishna ◽  
Khushal Ashok Bhatija ◽  
K. Sai Charan
Keyword(s):  
High Speed ◽  
Liquid Sheet ◽  
Interfacial Instability ◽  
Wave Number ◽  
Liquid Jets ◽  
Liquid Jet ◽  
Experimental Characterization ◽  
Interfacial Wave ◽  
Visualization Techniques

The present study focuses on experimental characterization of interfacial instability pertinent to liquid jet and liquid sheet in the first wind-induced zone. To accomplish this objective, the interfacial wave growth rate, critical wave number, and breakup frequency associated with air-assisted atomizer systems were extracted by utilizing high-speed flow visualization techniques. For a range of liquid to gas velocities tested, nondimensionalization with appropriate variables generates the corresponding correlation functions. These functions enable to make an effective comparison between interfacial wave developments for liquid jet and sheet configurations. It exhibits liquid sheets superiority over liquid jets in the breakup processes leading to efficient atomization.

A Study of Aerodynamics Around Rotating Blades in a Lawnmower Deck

2002 ◽  
Author(s):  
P. A. Hagen ◽  
W. Chon ◽  
R. S. Amano
Keyword(s):  
High Speed ◽  
Flow Behavior ◽  
Video Camera ◽  
Element Analysis ◽  
Pressure Transducers ◽  
Discharge Velocity ◽  
Vapor Injection ◽  
High Speed Video Camera ◽  
Particle Feeding ◽  
Visualization Techniques

The objective of this study is to investigate the flow behavior within a triple-blade lawnmower deck. The test section was constructed for velocity measurement with an open bottom and side-discharge. Velocity measurements were collected at several different tangential and axial sections inside the deck. The flow behaviors are observed using Laser Doppler Velocimetry (LDV) and a high-speed video camera capturing 2000 frames per second. Several different visualization techniques have been attempted: particle feeding, water vapor injection, tuft method, and others. To further enhance the experimental accuracy, fresh sod was fed into the system simulating normal cutting conditions. Along with the extensive velocity analysis, strain and static pressure were also examined at various surface locations along the blade using linear strain gages, piezoresistive pressure transducers, and Finite Element Analysis (FEA) methods. Validation of the above analyses was performed using Computational Fluid Dynamics (CFD) investigation. It has been observed that the deck and blade configurations share equal significance in the resultant flow profiles.

Flow Visualization Techniques for the Evaluation of Non-Contact Trace Contraband Detectors

2010 ◽  
Author(s):  
Matthew Staymates ◽  
Greg Gillen ◽  
Wayne Smith ◽  
Richard Lareau ◽  
Robert Fletcher
Keyword(s):  
High Speed ◽  
Trace Detection ◽  
Confined Space ◽  
Screening Process ◽  
Detection Systems ◽  
Air Jets ◽  
Heating And Cooling ◽  
Lift Off ◽  
Visualization Techniques ◽  
Chemical Analyzer

Efforts are underway in the Surface and Microanalysis Science Division at the National Institute of Standards and Technology to study trace aerodynamic sampling of contraband materials (explosives or narcotics) in non-contact trace detection systems. Trace detection systems are designed to screen people, personal items, and cargo for particles that have contaminated surfaces. In a typical implementation of people screening, a human subject walks into a confined space where they are interrogated by a series of pulsed air jets and are screened for contraband materials by a chemical analyzer. The screening process requires particle and vapor removal, transport, collection, desorption, and detection. Aerodynamic sampling is the critical front-end process for effective detection. In this paper, a number of visualization techniques are employed to study non-contact aerodynamic sampling in detail. Particle lift-off and removal is visualized using high-speed videography, transport of air and particles by laser light scattering, and desorption surface heating and cooling patterns by infrared thermography. These tools are used to identify sampling inefficiencies and may be used to study next-generation screening approaches for aerodynamic sampling of particles and vapors.

Experimental Characterization of a Liquid Jet Emanating From An Effervescent Atomizer

2020 ◽  
Vol 142 (6) ◽  
Author(s):  
V. Sivadas ◽  
K. Balaji ◽  
Antriksha Vishwakarma ◽  
Sundar Ram Manikandan
Keyword(s):  
High Speed ◽  
Flow Direction ◽  
Low Frequency ◽  
Intrinsic Property ◽  
Liquid Jet ◽  
Experimental Characterization ◽  
Jet Breakup ◽  
Effervescent Atomizer ◽  
Visualization Techniques

Abstract The study focuses on experimental characterization of the primary atomization associated with an effervescent atomizer. Unlike the existing designs available in the literature that inject air perpendicular to the liquid flow direction, the present atomizer design utilizes coflowing air configuration. In doing so, the aerodynamic shear at the liquid–gas interface create instability and enhance the subsequent jet breakup. Both integrated and intrinsic properties of the liquid jet were extracted by utilizing high-speed flow visualization techniques. The integrated property consists of breakup length, while the intrinsic property involves primary and intermediate breakup frequencies. The primary instability is characterized by low-frequency sinusoidal mode, whereas the intermediate instability consists of high-frequency dilatational mode. Dimensionless plots of these parameters with Weber number ratio leads to a better collapse of data, thereby generating appropriate universal functions. The combined diagram of frequencies converge with increasing relative velocity. This may be due to the dominance of energy consuming sinusoidal wave as the aerodynamic shear increases.

Low-Turbulence High-Speed Wind Tunnel for the Determination of Cascade Shock Losses

1979 ◽  
Author(s):  
J. A. Slovisky ◽  
W. B. Roberts ◽  
D. M. Sandercock
Keyword(s):  
Wind Tunnel ◽  
High Speed ◽  
Axial Compressor ◽  
Pressure Probe ◽  
Supersonic Wind Tunnel ◽  
Smoke Flow ◽  
Contraction Ratio ◽  
Curved Shock Waves ◽  
Visualization Techniques

A low turbulence high-speed wind tunnel, using anti-turbulence screening and a 100:1 contraction ratio, has been found suitable for high-speed smoke flow visualization. The location and strength of normal, oblique, and curved shock waves generated by transonic or supersonic wind tunnel flow over airfoils or through axial compressor cascades is determined by combined shadowgraph and smokelines visualization techniques without the interference effects caused by intrusive probes. The Reynolds number based on chord varied between 50,000 and 106. Preliminary results are compared with the relevant theory and data gathered using a total pressure probe.

Experimental Study of Aerodynamics Around Rotating Blades in a Lawnmower Deck

2002 ◽  
Author(s):  
P. A. Hagen ◽  
W. Chon ◽  
R. S. Amano
Keyword(s):  
High Speed ◽  
Flow Behavior ◽  
Video Camera ◽  
Strain Gages ◽  
Velocity Measurements ◽  
Discharge Velocity ◽  
Vapor Injection ◽  
High Speed Video Camera ◽  
Particle Feeding ◽  
Visualization Techniques

The objective of this study is to investigate the flow behavior within a triple-blade lawnmower deck by means of experimental techniques. The test section was constructed for velocity measurement with an open bottom and side-discharge. Velocity measurements were collected at several different tangential and axial sections inside the deck. The flow behaviors are observed using both a Laser Doppler Velocimetry (LDV) and a high-speed video camera capturing 2000 frames per second. Several different visualization techniques have been attempted: particle feeding, water vapor injection, tuft method, and others. To further enhance the experimental accuracy, fresh sod was fed into the system simulating normal cutting conditions. Along with the extensive velocity analysis, strain and static pressure were also examined at various surface locations along the blade using linear strain gages and a piezoresistive pressure transducer. It has been observed that the deck and blade configurations share equal significance in the resultant flow profiles.

Analysis of voice quality parameters in patients with vestibular voice

2019 ◽  
Vol 73 (3) ◽  
pp. 11-15
Author(s):  
Bożena Kosztyła-Hojna ◽  
Anna Łobaczuk-Sitnik ◽  
Maciej Zdrojkowski ◽  
Emilia Duchnowska ◽  
Diana Moskal-Jasińska ◽  
...  
Keyword(s):  
Digital Imaging ◽  
High Speed ◽  
Voice Quality ◽  
Vocal Folds ◽  
Quality Parameters ◽  
Physiological Process ◽  
Acoustic Evaluation ◽  
Perceptual Assessment ◽  
Visualization Techniques

Abstract Vestibular voice includes participation of larynx structures which are absent in physiological process. Vestibular phonation may be desired when vocal folds are damaged as in paralytic dysphonia, or undesired in marginal hyperfunction. Vestibular voice may result from psychogenic dysphonia – phononeurosis. The aim of the study is perceptive evaluation of vestibular voice, objective larynx visualization, acoustic and aerodynamic examination. The study included 40 patients: 20 with vestibular voice, 20 with euphonic voice. Voice quality has been evaluated using perceptual GRBAS scale. Endoscopic and stroboscopic larynx examination used Endo-STROB-EL-Xion GmbH with visual tract. High-Speed Digital Imaging (HSDI) and High Speed (HS) camera registered true vocal folds vibrations. Acoustic evaluation of voice with DiagnoScope Specjalista, DiagNova Technologies included analysis of F0, Jitter, Shimmer, NHR, nonharmonic components. MPT has been analyzed. In examined group, hoarseness (95%), roughness (75%) and voice strain (55%) have been recorded. Endoscopy revealed edema of vestibular folds with dilation of vessels covering glottis. Stroboscopy and HSDI confirmed coexistence of hyperfunctional (95%) or paralytic (5%) dysphonia. Acoustic assessment revealed increase in Jitter, Shimmer, NHR and decrease in F0 and MPT. The vestibular voice is observed most frequently in women with hyperfunctional dysphonia (phononeuroses) or in paralytic dysphonia. Visualization techniques confirm the coexistence of vestibular folds hypertrophy and edema with vibration disorders. In the perceptual assessment, vestibular voice was hoarse, rough and strained. Acoustic examination showed increase of Jitter, Shimmer, NHR, presence of nonharmonic components and decrease of F0 and MPT.

High-speed laser visualization of particles thrown by detonation waves

1983 ◽  
Vol 19 (3) ◽  
pp. 363-369 ◽  
Author(s):  
V. M. Boiko ◽  
T. P. Gavrilenko ◽  
V. V. Grigor'ev ◽  
A. A. Karnaukhov ◽  
Yu. A. Nikolaev ◽  
...  
Keyword(s):  
High Speed ◽  
Detonation Waves ◽  
Laser Visualization

Computational and Experimental Characterization of Single Bubble Dynamics in Isothermal Liquid Pools

2007 ◽  
Author(s):  
A. Subramani ◽  
S. K. Kasimsetty ◽  
R. M. Manglik ◽  
M. A. Jog
Keyword(s):  
Surface Tension ◽  
Bubble Growth ◽  
High Speed ◽  
Bubble Dynamics ◽  
Great Influence ◽  
Growth Dynamics ◽  
Equivalent Diameter ◽  
Parametric Effects ◽  
Liquid Pools ◽  
Visualization Techniques

The process of bubble growth is of great influence on the bubble volume and bubble rise velocity. The overall behavior of bubbles at fluid interfaces depends strongly on bubble growth and the closely linked process of bubble detachment. In the present study, the dynamics of a single gas bubble emanating from an orifice submerged in isothermal liquid pools is investigated computationally and experimentally. The parametric effects of liquid properties, capillary diameters and air flow rates on the bubble shape, equivalent diameter, and growth times on the dynamic behavior (incipience, growth and necking) of air bubbles, in fluids of varying surface tension and viscosity, as it grows from a tip of a sub-millimeter-scale capillary orifice have been studied. Computational solutions have been obtained by solving the complete set of governing equations using Volume of Fluid (VOF) interface tracking method. The CFD model has been verified experimentally using optical high speed micro-scale flow visualization techniques. The results were analyzed in a theoretical stand point considering the various forces acting on the bubble such as forces due to buoyancy, viscosity, surface tension, liquid inertia, and gas momentum transport, and the consequent motion of the gas-liquid interface. The results obtained ascertain the role of liquid-gas interfacial forces as well as the fluid properties on the bubble growth dynamics.

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