High-speed voltage buffers for the experimental characterization of CMOS transconductance operational amplifiers

1999 ◽  
Vol 48 (1) ◽  
pp. 31-33 ◽  
Author(s):  
G. di Cataldo ◽  
G. Palmisano ◽  
G. Palumbo ◽  
S. Pennisi
Keyword(s):  
High Speed ◽  
Operational Amplifiers ◽  
Experimental Characterization

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 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 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.

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.

Identification of Cavitation Instabilities on a Three-Bladed Inducer by Means of Strain Gages

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Ruzbeh Hadavandi ◽  
Giovanni Pace ◽  
Dario Valentini ◽  
Angelo Pasini ◽  
Luca d'Agostino
Keyword(s):  
High Speed ◽  
Strain Gages ◽  
Experimental Characterization ◽  
Mechanism Of Formation ◽  
Pressure Transducers ◽  
Cavitation Region ◽  
Rotating Frames ◽  
Induced Flow ◽  
High Head

Abstract This paper reports the experimental characterization of the cavitation-induced flow instabilities of a high head three-bladed inducer at design condition detected simultaneously by means of piezoelectric pressure transducers located at different axial and azimuthal stations on the casing of the pump and strain gages mounted on the pressure side of each blade. The simultaneous analysis performed in the stationary and rotating frames, supported by high-speed movies, suggests that the mechanism of formation of the detected subsynchronous rotating cavitation resembles that of modal stall in compressors, being the cavitation region the source of compliance. In fact, at decreasing cavitation number, a strong attached cavitation, developed preferentially on one blade and capable of completely surrounding and unloading the following blade, starts to be destabilized as consequence of the progressive intensification of a modal oscillation. The developed complex instability, consisting in a strong oscillation of the attached cavitation, is detected in both the frames as the simultaneous presence of a subsynchronous rotating cavitation and a cavitation surge.

Whipping instability characterization of an electrified visco-capillary jet

2011 ◽  
Vol 671 ◽  
pp. 226-253 ◽  
Author(s):  
GUILLAUME RIBOUX ◽  
ÁLVARO G. MARÍN ◽  
IGNACIO G. LOSCERTALES ◽  
ANTONIO BARRERO
Keyword(s):  
High Speed ◽  
Dielectric Liquid ◽  
Taylor Cone ◽  
The Other ◽  
Experimental Characterization ◽  
Dimensionless Numbers ◽  
Host Medium ◽  
Set Up ◽  
Axisymmetric Instability

The charged liquid micro-jet issued from a Taylor cone may develop a special type of non-axisymmetric instability, usually referred to in the literature as a whipping mode. This instability usually manifests itself as a series of fast and violent lashes of the charged jet, which makes its characterization in the laboratory difficult. Recently, we have found that this instability may also develop when the host medium surrounding the Taylor cone and the jet is a dielectric liquid instead of air. When the oscillations of the jet occur inside a dielectric liquid, their frequency and amplitude are much lower than those of the oscillations taking place in air. Taking advantage of this fact, we have performed a detailed experimental characterization of the whipping instability of a charged micro-jet within a dielectric liquid by recording the jet motion with a high-speed camera. Appropriate image processing yields the frequency and wavelength, among the other important characteristics, of the jet whipping as a function of the governing parameters of the experimental set-up (flow rate and applied electric field) and liquid properties. Alternatively, the results can be also written as a function of three dimensionless numbers: the capillary and electrical Bond numbers and the ratio between an electrical relaxation and residence time.

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