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.

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.

Experimental Investigation of Liquid Jet Breakup in a Cross Flow of a Swirling Air Stream

2014 ◽  
Vol 136 (6) ◽  
Author(s):  
Tushar Sikroria ◽  
Abhijit Kushari ◽  
Saadat Syed ◽  
Jeffery A. Lovett
Keyword(s):  
Experimental Investigation ◽  
Momentum Flux ◽  
High Speed ◽  
Cross Flow ◽  
Flux Ratio ◽  
Liquid Jet ◽  
Breakup Process ◽  
Breakup Length ◽  
Jet Breakup ◽  
Penetration Behavior

This paper presents the results of an experimental investigation of liquid jet breakup in a cross flow of air under the influence of swirl (swirl numbers 0 and 0.2) at a fixed air flow Mach number 0.12 (typical gas turbine conditions). The experiments have been conducted for various liquid to air momentum flux ratios (q) in the range of 1 to 25. High speed (@ 500 fps) images of the jet breakup process are captured and those images are processed using matlab to obtain the variation of breakup length and penetration height with momentum flux ratio. Using the high speed images, an attempt has been made to understand the physics of the jet breakup process by identification of breakup modes—bag breakup, column breakup, shear breakup, and surface breakup. The results show unique breakup and penetration behavior which departs from the continuous correlations typically used. Furthermore, the images show a substantial spatial fluctuation of the emerging jet resulting in a wavy nature related to effects of instability waves. The results with 15 deg swirl show reduced breakup length and penetration related to the nonuniform distribution of velocity that offers enhanced fuel atomization in swirling fuel nozzles.

Single-Nozzle Micropumps

2009 ◽  
Author(s):  
X. Y. Huang ◽  
S. S. Wang ◽  
C. Yang
Keyword(s):  
Numerical Simulation ◽  
Flow Direction ◽  
Low Frequency ◽  
Pressure Head ◽  
Acoustic Resonator ◽  
Planar Channel ◽  
Experimental Characterization ◽  
Valveless Micropump ◽  
Dry Adhesives ◽  
Piezoelectric Disk

We demonstrate a new design of valveless micropump with a single nozzle and driven by piezoelectric disk. The nozzle is formed by a planar channel with an acoustic resonator profile, and the pump is fabricated by lamination of layers made of polymethyl-methacrylate (PMMA) and dry adhesives. Both experimental characterization and numerical simulation show that pump works well at low frequency in terms of relatively high pressure head and flowrate. Moreover, the pumping flow direction can be altered by simply adding buffer areas at the inlet and outlet. The pump is suitable for microfluidic integrations.

Experimental Characterization of Losses in Bladeless Turbine Prototype

2021 ◽  
Author(s):  
Avinash Renuke ◽  
Federico Reggio ◽  
Alberto Traverso ◽  
Matteo Pascenti
Keyword(s):  
High Speed ◽  
Electrical Power ◽  
Working Fluid ◽  
Small Scale ◽  
Experimental Characterization ◽  
Scaling Effects ◽  
Low Performance ◽  
Low Sensitivity ◽  
First Time

Abstract Multi-disk bladeless turbines, also known as Tesla turbines, are promising in the field of small-scale power generation and energy harvesting due to their low sensitivity to down-scaling effects, retaining high rotor efficiency. However, low (less than 40%) overall isentropic efficiency has been recorded in the experimental literature. This article aims for the first time to a systematic experimental characterization of loss mechanisms in a 3-kW Tesla expander using compressed air as working fluid and producing electrical power through a high speed generator (40krpm). The sources of losses discussed are: stator losses, stator-rotor peripheral viscous losses, end wall ventilation losses and leakage losses. After description of experimental prototype, methodology and assessment of measurement accuracy, the article discusses such losses aiming at separating the effects that each loss has on the overall performance. Once effects are separated, their individual impact on the overall efficiency curves is presented. This experimental investigation, for the first time, gives the insight into the actual reasons of low performance of Tesla turbines, highlighting critical areas of improvement, and paving the way to next generation Tesla turbines, competitive with state of the art bladed expanders.

Satellite formation and merging in liquid jet breakup

1991 ◽  
Vol 433 (1888) ◽  
pp. 269-286 ◽  
Keyword(s):  
Weber Number ◽  
High Speed ◽  
Drop Size ◽  
Liquid Jet ◽  
Number Range ◽  
Satellite Formation ◽  
Long Wavelength ◽  
Breakup Mechanism ◽  
Jet Breakup ◽  
New Type

An experimental investigation of the breakup of a liquid jet using high-speed motion pictures has revealed many different breakup mechanisms. The influence of disturbance amplitude and frequency on the breakup mechanism for a Weber number range of 25 to 160 is considered. The jet breakup is grouped into several distinct regions, depending on the disturbance wavelength ( λ ), and the undisturbed jet diameter ( D ). These include the random breakup region for λ/D < 3, short wavelength Rayleigh breakup region for 3 < λ/D < 5.5, medium wavelength Rayleigh breakup region for 5.5 < λ/D < 11, and long wavelength Rayleigh breakup region for λ/D > 11. Except for the random region ( λ/D < 3), all the other regions show repeatable patterns of breakup. The boundaries between some of the distinct patterns are obtained for various Weber numbers and disturbance amplitudes. A new type of satellite merge is also discovered which is referred to as the reflexive merging satellite. Other features of the jet breakup, such as satellite/drop size ratio and breakup times, are also considered in detail.

scholarly journals Characterization of Liquid Jet Atomization across a High-Speed Airstream.

1994 ◽  
Vol 37 (4) ◽  
pp. 937-944 ◽  
Author(s):  
Tetsuya Oda ◽  
Hiroyuki Hiroyasu ◽  
Masataka Arai ◽  
Keiya Nishida
Keyword(s):  
High Speed ◽  
Liquid Jet ◽  
Liquid Jet Atomization

scholarly journals Experimental characterization of speech aerosol dispersion dynamics

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Zu Puayen Tan ◽  
Lokesh Silwal ◽  
Surya P. Bhatt ◽  
Vrishank Raghav
Keyword(s):  
High Speed ◽  
Particle Image ◽  
Experimental Characterization ◽  
Production Rates ◽  
Plume Front ◽  
Fidelity Assessment ◽  
Image Velocimetry ◽  
Aerosol Dispersion ◽  
Primary Transmission

AbstractContact and inhalation of virions-carrying human aerosols represent the primary transmission pathway for airborne diseases including the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Relative to sneezing and coughing, non-symptomatic aerosol-producing activities such as speaking are highly understudied. The dispersions of aerosols from vocalization by a human subject are hereby quantified using high-speed particle image velocimetry. Syllables of different aerosol production rates were tested and compared to coughing. Results indicate aerosol productions and penetrations are not correlated. E.g. ‘ti’ and ‘ma’ have similar production rates but only ‘ti’ penetrated as far as coughs. All cases exhibited a rapidly penetrating “jet phase” followed by a slow “puff phase.” Immediate dilution of aerosols was prevented by vortex ring flow structures that concentrated particles toward the plume-front. A high-fidelity assessment of risks to exposure must account for aerosol production rate, penetration, plume direction and the prevailing air current.

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