Experimental Investigations of Transfer Phenomena in a Confined Plane Turbulent Impinging Water Jet

2011 ◽  
Vol 133 (6) ◽  
Author(s):  
Amine Koched ◽  
Michel Pavageau ◽  
Fethi Aloui
Keyword(s):  
Time Scales ◽  
High Speed ◽  
Impinging Jets ◽  
Industrial Applications ◽  
Experimental Investigations ◽  
Confined Water ◽  
Wide Range ◽  
Plane Jets ◽  
Component Velocity ◽  
Lagrangian Tracking

In this study, we are interested in the hydrodynamics of impinging plane jets. Plane jets are widely used in ambience separation in HVAC, fire safety, food process engineering, cooling of electronic components etc. Despite their important industrial applications, plane jets have not been studied as extensively as axisymmetric jets. Plane jets exhibit different kind of instabilities stemming from either streamlines with strong curvature in the impingement region or inflection points in the transverse profile of the streamwise component velocity in the lateral mixing layers. Previous works in the GEPEA laboratory were performed on these flows. These works and the majority of the studies reported in the literature deal with turbulent air jets in various configurations. Very little studies have been done on water impinging jets. Taking into account the fact that the viscosity of water is smaller than air, at the same Reynolds number, it is easier to detect phenomena such as vortices. Phenomena can be observed at lower velocities making it possible to record signals with standard frequency bandwidths. This makes it easier also to do a Lagrangian tracking of vortices. We specially focused our study on the impinging zone of the jet. The dynamics of the impinging zone has not formed the subject of numerous studies. There were no studies that characterize the vortices at the impinging region of water jets in terms of size, centre position, vortex intensity, convection velocities, eccentricity, statistical distribution and turbulent length and time scales. Consequently, a confined water plane jet impinging a flat plate was studied using standard and high speed PIV (Particle Image Velocimetry). We used POD decomposition for filtering PIV data. Then, we applied the λ2 criterion to the recorded velocity fields to detect and characterize the vortices at the impingement. A statistical analysis was then performed. Turbulent length scales, time scales and convection velocities of eddies occurring at the impingement were determined using two point space time correlations. The obtained results were correlated to the dynamics and geometric properties of the jet. A wide range of Reynolds numbers is considered: 3000, 6000, 11000 and 16000. The corresponding results are presented in this paper.

Experimental Investigations of Transfer Phenomena in a Confined Plane Turbulent Impinging Water Jet

2010 ◽  
Author(s):  
Amine Koched ◽  
Michel Pavageau ◽  
Fethi Aloui
Keyword(s):  
Impinging Jets ◽  
Industrial Applications ◽  
Experimental Investigations ◽  
Confined Water ◽  
Air Jets ◽  
Wide Range ◽  
Plane Jets ◽  
Component Velocity ◽  
Lagrangian Tracking ◽  
Plane Jet

In this study, we are interested in the hydrodynamics of impinging plane jets. Plane jets are widely used in ambience separation in HVAC, fire safety, food process engineering, cooling of electronic components etc. Despite their important industrial applications, plane jets have not been studied as extensively as axisymmetric jets. Plane jet exhibit different kind of instabilities stemming from either streamlines with strong curvature in the impingement region or inflection points in the transverse profile of the streamwise component velocity in the lateral mixing layers. Previous works in the GEPEA laboratory were performed on these flows. These works and the majority of the studies reported in the literature deal with turbulent air jets in various configurations. Very little studies have been done on water impinging jets. Taking into account the fact that the viscosity of water is smaller than air, at the same Reynolds number, it is easier to detect phenomena such as vortices. Phenomena can be observed at lower velocities making it possible to record signals with standard frequency bandwidths. This makes it easier also to do a Lagrangian tracking of vortices. We specially focused our study on the impinging zone of the jet. The dynamics of the impinging zone has not formed the subject of numerous studies. There were no studies that characterize the vortices at the impinging region of water jets in terms of size, center positions, vortex intensity, eccentricity, statistical distribution and interaction with the impinging wall. Consequently, a confined water plane jet impinging a flat plate was studied using PIV (Particle Image Velocimetry). We used POD decomposition for filtering PIV data. Then, we applied the λ2 criterion to the recorded velocity fields to detect and characterize the vortices at the impingement. A statistical analysis was then performed. A wide range of Reynolds numbers is considered: 3000, 6000, 11000 and 16000. The corresponding results will be presented.

scholarly journals MEASURING DISPLACEMENT AND VELOCITY OF A STRIKER USING A RADIO-INTERFEROMETER

2019 ◽  
Vol 81 (1) ◽  
pp. 118-128
Author(s):  
V. V. Balandin ◽  
V. V. Balandin ◽  
V. V. Parkhachev
Keyword(s):  
High Speed ◽  
Radio Interferometer ◽  
Experimental Investigations ◽  
X Ray ◽  
Gas Gun ◽  
Impact Interaction ◽  
Ballistic Experiment ◽  
Wide Range ◽  
Series Of Experiments ◽  
Error Of Measurement

Investigating impact interaction of solid and deformed bodies with obstacles of various physical natures requires developing experimental methodologies of registering the parameters of the interaction process. In experimental investigations of impact interaction of solids, it is common practice to measure displacement of strikers as a function of time, as well as their velocity and deceleration. To determine the displacement and velocity of a striker, a radio-interferometric methodology of registering the displacement of its rear end is proposed. In contrast with the registration methods based on high-speed filming and pulsed X-ray photography, the method using a millimeter-range radio-interferometer provides continuous high-accuracy registering of the displacement of the rear end of a striker in a wide range of displacement values. To test the effectiveness of the methodology, a series of experiments have been conducted on registering the motion of a cylindrical striker of an aluminum alloy, fired from a 20mm-dia gas gun. The displacement of the striker was also monitored using high-speed filming. The results of measuring using the two methodologies differ within the limits of the error of measurement. Based on the results of the above experiments, it has been concluded that the methodology of determining the displacement and velocity of strikers in a ballistic experiment using a mm-range radio-interferometer makes it possible to measure practically continuously large displacements (100 mm and larger) to a safe accuracy. The present methodology can be used for measuring the displacement and velocity of the rear end of a striker interacting with obstacles of various physical natures (metals, ceramics, soils, concretes, etc.).

Aerodynamic Investigations of a Variable Inlet Guide Vane With Symmetric Profile

2014 ◽  
Author(s):  
David Händel ◽  
Reinhard Niehuis ◽  
Uwe Rockstroh
Keyword(s):  
Boundary Layer ◽  
High Speed ◽  
Guide Vane ◽  
Reynolds Numbers ◽  
Boundary Layer Transition ◽  
Inlet Guide Vane ◽  
Experimental Investigations ◽  
Wide Range ◽  
Variable Inlet Guide Vane ◽  
Symmetric Profile

In order to determine the aerodynamic behavior of a Variable Inlet Guide Vane as used in multishaft compressors, extensive experimental investigations with a 2D linear cascade have been conducted. All the experiments were performed at the High-Speed Cascade Wind Tunnel at the Institute of Jet Propulsion. They covered a wide range of Reynolds numbers and stagger angles as they occur in realistic turbomachines. Within this work at first the observed basic flow phenomena (loss development, overturning) will be explained. For the present special case of a symmetric profile and a constant decreasing chord length along the vane height, statements about different spanwise position can be made by investigating different Reynolds numbers. The focus of this paper is on the outflow of the VIGV along the vane height. Results for an open flow separation on the suction side are presented, too. Stall condition can be delayed by boundary layer control. This is done using a wire to trigger an early boundary layer transition. The outcomes of the trip wire measurement are finally discussed. The objective of this work is to evaluate the influence of the stagger angle and Reynolds number on the total pressure losses and the deviation angle. The results of the work presented here, gives a better insight of the efficient use of a VIGV.

scholarly journals Impinging jets – a short review on strategies for heat transfer enhancement

2018 ◽  
Vol 32 ◽  
pp. 01013
Author(s):  
Ilinca Nastase ◽  
Florin Bode
Keyword(s):  
Heat Transfer ◽  
Large Scale ◽  
Short Review ◽  
Great Difficulty ◽  
Impinging Jets ◽  
Industrial Applications ◽  
Experimental Investigations ◽  
Small Scale ◽  
Strong Shear ◽  
Flow Phenomena

In industrial applications, heat and mass transfer can be considerably increased using impinging jets. A large number of flow phenomena will be generated by the impinging flow, such as: large scale structures, large curvature involving strong shear and normal stresses, stagnation in the wall boundary layers, heat transfer with the impinged wall, small scale turbulent mixing. All these phenomena are highly unsteady and even if nowadays a substantial number of studies in the literature are dedicated, the impinging jets are still not fully understood due to the highly unsteady nature and more over due to great difficulty of performing detailed numerical and experimental investigations.

scholarly journals High-speed force spectroscopy: microsecond force measurements using ultrashort cantilevers

2019 ◽  
Vol 11 (5) ◽  
pp. 689-699 ◽  
Author(s):  
Claire Valotteau ◽  
Fidan Sumbul ◽  
Felix Rico
Keyword(s):  
Time Scales ◽  
High Speed ◽  
Protein Unfolding ◽  
Deep Understanding ◽  
Force Spectroscopy ◽  
Md Simulations ◽  
Living Cells ◽  
Force Measurements ◽  
Cellular Mechanics ◽  
Wide Range

Abstract Complete understanding of the role of mechanical forces in biological processes requires knowledge of the mechanical properties of individual proteins and living cells. Moreover, the dynamic response of biological systems at the nano- and microscales span over several orders of magnitude in time, from sub-microseconds to several minutes. Thus, access to force measurements over a wide range of length and time scales is required. High-speed atomic force microscopy (HS-AFM) using ultrashort cantilevers has emerged as a tool to study the dynamics of biomolecules and cells at video rates. The adaptation of HS-AFM to perform high-speed force spectroscopy (HS-FS) allows probing protein unfolding and receptor/ligand unbinding up to the velocity of molecular dynamics (MD) simulations with sub-microsecond time resolution. Moreover, application of HS-FS on living cells allows probing the viscoelastic response at short time scales providing deep understanding of cytoskeleton dynamics. In this mini-review, we assess the principles and recent developments and applications of HS-FS using ultrashort cantilevers to probe molecular and cellular mechanics.

Initial tool wear behavior in high-speed turning of Inconel 718

2020 ◽  
Vol 44 (3) ◽  
pp. 395-404
Author(s):  
Morvarid Memarianpour ◽  
Seyed Ali Niknam ◽  
Sylvain Turenne ◽  
Marek Balazinski
Keyword(s):  
Steady State ◽  
Tool Wear ◽  
Inconel 718 ◽  
High Speed ◽  
Wear Behavior ◽  
Cutting Speed ◽  
Cutting Parameters ◽  
Industrial Applications ◽  
Wide Range ◽  
Tool Wear Mechanism

Three distinctive regions of tool wear, known as initial wear, steady-state wear, and accelerated wear, are well understood. However, the effects of cutting parameters on the initial tool wear mechanism, morphology, and size have received less attention as compared to the other two regions. Knowing that adequate control of initial tool wear may lead to extended tool life, in particular in hard-to-cut metals such as superalloys, this topic has become a source of attention. Amongst superalloys, Inconel 718 is considered as one of the most difficult to cut materials, which has a wide range of industrial applications. This study intends to evaluate the effects of cutting parameters on initial tool wear, as well as tool wear progression, when turning Inconel 718. Therefore, microstructural evaluation of the initial tool wear mode under various cutting conditions, as well as tool wear measurements, were conducted. It was observed that certain elements of the workpieces were migrated to the insert flank face. This is evidence of adhesion at the initial moments of the cutting process. In contrast to many other easy-to-cut materials, the steady-state wear period when turning Inconel 718 is significantly short under a higher level of cutting speed and feed rate.

High Speed Shape Memory Alloy Activation

2012 ◽  
Author(s):  
Alexander Czechowicz ◽  
Jonas Böttcher ◽  
Sebastian Mojrzisch ◽  
Sven Langbein
Keyword(s):  
Shape Memory ◽  
Smart Materials ◽  
High Speed ◽  
Industrial Applications ◽  
Feedback Signal ◽  
Sma Actuators ◽  
Wide Range ◽  
Current Activation ◽  
Actual Shape ◽  
Control Feedback

Due to their ability to change into a previously imprinted actual shape through the means of thermal and electrical activation, shape memory alloys (SMA) are suitable as actuators. To apply these smart materials to a wide range of high-speed applications like valves or safety systems, an analysis of the application potential is required. The detection of inner electrical resistance of SMA actuators allows gauging the actuator’s stroke. By usage of a microcontroller a smart system without any hardware sensors can be realized which protects the system from overheating during high-current activation. The publication concentrates on different experimental data on high-speed actuation under 20ms and the potentials in the field of industrial applications. The paper gives an overview about different controlling methods for SMA-actuators, experiments concerning the resistance behavior of SMA and the development of systems using a resistance control feedback signal during high-speed activation.

Dynamics of Planar, Elastic, High-Speed Mechanisms Considering Three-Dimensional Offset Geometry: Analytical and Experimental Investigations

1983 ◽  
Vol 105 (3) ◽  
pp. 498-510 ◽  
Author(s):  
F. R. Stamps ◽  
C. Bagci
Keyword(s):  
High Speed ◽  
Critical Speed ◽  
Shock Loading ◽  
Dynamic Stress ◽  
Three Dimensional ◽  
Industrial Applications ◽  
Experimental Investigations ◽  
Planar Mechanisms ◽  
Elastic Systems ◽  
Stress Levels

Mechanisms in industrial applications in general operate as three-dimensional elastic systems, including planar mechanisms due to offsets between the planes of motion of links. This article investigates dynamic behaviors of planar mechanisms with offset geometry analytically and experimentally for dynamic stress and critical speed levels. Three-dimensional line element with irregular freedoms is used and generalized digital computer programs are prepared to perform kineto-elasto-static, dynamic stress, frequency, and critical speed analyses of three-dimensional mechanisms including the planar mechanisms with three-dimensional offsets. An experimental planar four-bar mechanism was tested for critical speed and elastodynamic stress levels with three levels of offsets. It has been determined that a mechanism experiences integer divisions of the integrated average of the three-dimensional fundamental natural frequency, ωinavg, within a cycle of the mechanism as critical speeds as well as its multiples. Recommended operating speeds of a mechanism are those in between two integer divisions of ωinavg at lower levels. Elastodynamic stress levels at these recommended speed levels are predicted analytically by kineto-elasto-static analysis and very conservatively even in the shock loading zones of the mechanism. The validity of the highly economical CGKES (Critical Geometry Kineto-Elasto-Statics) method for mechanisms having three-dimensional geometry is also verified by the experimental results.

scholarly journals Microcontroller Based High Voltage, High Speed Trigger Control Circuit for SMARTEX-C

2021 ◽  
Vol 12 ◽  
pp. 100-105
Author(s):  
Minsha Shah ◽  
Hitesh Mandaliya ◽  
Lavkesh Lachhvani ◽  
Manu Bajpai ◽  
Rachana Rajpal
Keyword(s):  
Time Scales ◽  
High Voltage ◽  
High Speed ◽  
Electron Plasma ◽  
Control Circuit ◽  
Switching Speed ◽  
Fast Switching ◽  
Electrode Potentials ◽  
Dc Power ◽  
Wide Range

Microcontroller based trigger control circuit for fast pulsing of electrode potentials on wide range of time scales has been designed, installed, and tested for electron plasma experiments which are carried out in partial toroidal trap SMall Aspect Ratio Toroidal Electron plasma EXperiment in C – shaped geometry (SMARTEX – C), a device to create and confine non-neutral plasma (electron plasma). The sequence of trap operation is inject-hold-dump for which electrodes need to be pulsed with applied voltages at a high switching speed of few nanoseconds. Also this sequence of operation needs to be controlled over a very wide range of time scales from few microseconds to few seconds. As the available COTS (Commercial-Off-The-Shelf) high voltage DC power supplies generally do not provide this feature of fast switching at nanosecond time scale, MOSFET based circuit is developed which provides fast switching in the range of 20 – 100 nanoseconds of high voltages (200Vdc - 500Vdc) of multiple electrodes. The timing pulse widths of these trigger pulses are controlled using a microcontroller-based circuit. This experimental set-up also requires the triggering of a high current dc power supply used for an Electro-magnet (Toroidal Field Coil) to generate a toroidal magnetic field, at the start of this experiment. For this purpose, a Silicon Controlled Rectifier (SCR) based circuit is used. The gate pulse to trigger the SCR circuit is also generated from this microcontroller-based circuit. National Instrument’s LabVIEW software based Graphical User Interface (GUI) is developed for triggering the SCR and electrodes with a programmable time period through the serial link.

scholarly journals Extended Joint Sparsity Reconstruction for Spatial and Temporal ERT Imaging

Sensors ◽  
2018 ◽  
Vol 18 (11) ◽  
pp. 4014 ◽  
Author(s):  
Bo Chen ◽  
Juan Abascal ◽  
Manuchehr Soleimani
Keyword(s):  
Temporal Resolution ◽  
High Speed ◽  
Low Cost ◽  
Control Process ◽  
Industrial Applications ◽  
High Temporal Resolution ◽  
Conductivity Distribution ◽  
Dynamic Movement ◽  
Wide Range ◽  
The Time Domain

Electrical resistance tomography (ERT) is an imaging technique to recover the conductivity distribution with boundary measurements via attached electrodes. There are a wide range of applications using ERT for image reconstruction or parameter calculation due to high speed data collection, low cost, and the advantages of being non-invasive and portable. Although ERT is considered a high temporal resolution method, a temporally regularized method can greatly enhance such a temporal resolution compared to frame-by-frame reconstruction. In some of the cases, especially in the industrial applications, dynamic movement of an object is critical. In practice, it is desirable for monitoring and controlling the dynamic process. ERT can determine the spatial conductivity distribution based on previous work, and ERT potentially shows good performance in exploiting temporal information as well. Many ERT algorithms reconstruct images frame by frame, which is not optimal and would assume that the target is static during collection of each data frame, which is inconsistent with the real case. Although spatiotemporal-based algorithms can account for the temporal effect of dynamic movement and can generate better results, there is not that much work aimed at analyzing the performance in the time domain. In this paper, we discuss the performance of a novel spatiotemporal total variation (STTV) algorithm in both the spatial and temporal domain, and Temporal One-Step Tikhonov-based algorithms were also employed for comparison. The experimental results show that the STTV has a faster response time for temporal variation of the moving object. This robust time response can contribute to a much better control process which is the main aim of the new generation of process tomography systems.

Sign in / Sign up

Export Citation Format

Share Document