Investigation On Swirl Instability in a Vane-Type Separator with Tomographic PIV

2021 ◽  
Author(s):  
Tingting Zhang ◽  
Guangyuan Huang ◽  
Junlian Yin ◽  
Zekai Zhang ◽  
Dezhong Wang ◽  
...  
Keyword(s):  
Axial Velocity ◽  
Pressure Difference ◽  
Separation Efficiency ◽  
Double Helix ◽  
Bubbly Flow ◽  
Underlying Mechanism ◽  
Swirl Flow ◽  
Whole Process ◽  
Straight Line ◽  
Image Velocimetry

Abstract The separation efficiency of a vane-type separator is greatly affected by swirl instability. The separator consists of a swirling vane, a recovery vane and a main pipe. Driven by centrifugal force, the bubbly flow tends to develop into stratified flow with a continuous gas core floating in the central axis of the separator and facilitating the separation. Yet, the straight gas core can turn into a double helix under some circumstances for example if the pressure difference across the orifices of recovery vane falls below the critical value, and swirl instability occurs. In order to reveal the underlying mechanism, a device with adjustable operating pres-sure was introduced to reproduce the dynamic process of gas core transform between stable and unstable. With the increase of pressure difference, the gas core morphology near the recovery vane will turn from double-helix to straight-line within several seconds. The whole process was investigated further by using the tomographic particle image velocimetry. Results show that the development of vorticity structures in the swirl flow gives rise to the evolution of gas core morphology and keeps it stable. Furthermore, the direction of axial velocity, which becomes negative by low pressure differences, is found to be crucial in controlling the formation of inner forced vortex and hence leading to the occurrence of swirl instability. In addition, the magnitude of positive axial velocity is identified to be of great significance in vorticity enhancement.

Flame image velocimetry analysis of reacting jet flow fields with a variation of injection pressure in a small-bore diesel engine

2020 ◽  
pp. 146808742096061
Author(s):  
Jinxin Yang ◽  
Lingzhe Rao ◽  
Yilong Zhang ◽  
Charitha de Silva ◽  
Sanghoon Kook
Keyword(s):  
Diesel Engine ◽  
Injection Pressure ◽  
Jet Flow ◽  
Flow Fields ◽  
Swirl Flow ◽  
Wall Jet ◽  
Jet Interaction ◽  
Image Velocimetry ◽  
Cyclic Variations ◽  
Flow Vectors

This study measures in-flame flow fields in a single-cylinder small-bore optical diesel engine using Flame Image Velocimetry (FIV) applied to high-speed soot luminosity movies. Three injection pressures were tested for a two-hole nozzle injector to cause jet-wall interaction and a significant jet-jet interaction within 45° inter-jet spacing. The high-pressure fuel jets were also under the strong influence of a swirl flow. For each test condition, soot luminosity signals were recorded at a high framing rate of 45 kHz with which the time-resolved, two-dimensional FIV post-processing was performed based on the image contrast variations associated with flame structure evolution and internal pattern change. A total of 100 combustion events for each injection pressure were recorded and processed to address the inherent cyclic variations. The ensemble-averaged flow fields were used for detailed flow structure discussion, and Reynolds decomposition using a spatial filtering method was applied to obtain high-frequency fluctuations that were found to be primarily turbulence. The detailed analysis of flow fields suggested that increased injection pressure leads to enhanced jet flow travelling along the bowl wall and higher flow vectors penetrating back towards the nozzle upon the impingement on the wall. Within the jet-jet interaction region, the flow vectors tend to follow the swirl direction, which increases with increasing injection pressure. The FIV also captured a turbulent ring vortex formed in the wall-jet head, which becomes larger and clearer at higher injection pressure. A vortex generated in the centre of combustion chamber was due to the swirl flow with its position being shifted at higher injection pressure. The bulk flow magnitude indicated significant cyclic variations, which increases with injection pressure. The turbulence intensity is also enhanced due to higher injection pressure, which primarily occurs in the wall-jet head region and the jet-jet interaction region.

Computational Fluid Dynamics and Particle Image Velocimetry Supported Examination of Bidirectional Velocity Probes for Measurements in Flames

2013 ◽  
Vol 6 (1) ◽  
Author(s):  
Nadir Yilmaz ◽  
Brian C. Hogan ◽  
Humberto Bocanegra ◽  
A. Burl Donaldson ◽  
Walt Gill
Keyword(s):  
Fluid Dynamics ◽  
Experimental Study ◽  
Reynolds Number ◽  
Wind Tunnel ◽  
Pressure Difference ◽  
Particle Image ◽  
Amplification Factor ◽  
Local Velocity ◽  
Bernoulli’S Equation ◽  
Image Velocimetry

The bidirectional velocity probe has been used in various flames to measure local velocity. The device is based on the pressure difference between a closed forward facing cavity and a closed rearward facing cavity. The probes have been noted to indicate a pressure difference greater than that which would be predicted based on Bernoulli's equation. Each device must be experimentally calibrated in a wind tunnel at similar Reynolds number to determine its “amplification factor.” This study uses PIV, flow visualization and CFD to examine the flow field around the probe, as well as an experimental study which compares various probe configurations for measurement of velocity by pressure differential. The conclusion is that the amplification factor is indeed greater than unity but use of the wind tunnel for calibration is questionable.

Particle image velocimetry investigation on air distribution of surface-source buoyancy plume changing heating intensity and structure size in a thermostatic chamber

2020 ◽  
pp. 1420326X2092624
Author(s):  
Xin Wang ◽  
Yukun Xu ◽  
Yinchen Yang ◽  
Bingyan Song
Keyword(s):  
Particle Image Velocimetry ◽  
Flow Field ◽  
Axial Velocity ◽  
Particle Image ◽  
Source Parameters ◽  
Air Distribution ◽  
Particle Image Velocimetry System ◽  
Surface Source ◽  
Large Space ◽  
Image Velocimetry

For large space buildings like industrial plants with huge heat generation, the role that surface-source plumes play becomes more crucial. To study the air distribution and movement of plumes, the first step is to quantify how the airflow gets distributed in chambers. The experiment was carried out in a thermostatic chamber where there was no ventilation. Four hundred flow field snapshots (in each region) were measured by a two-dimensional particle image velocimetry system at a sampling frequency of 3 Hz, and the time-average flow field was processed by the adaptive correlation algorithm to quantify the air distribution of the plume. According to the measured data, the variation law of the axial velocity of the surface-source plume under different heat source parameters was analysed. The formula coefficients of the axial velocity, the extended radius and the mass flow of the plume were discussed, and the coefficients from current two mainstream methods and those obtained in this paper were compared. The results of this study will be useful to predict motion of surface-plumes and optimize airflow patterns in large spaces.

scholarly journals Experimental and Numerical Study of Blood Flow in μ-vessels: Influence of the Fahraeus–Lindqvist Effect

Fluids ◽  
2019 ◽  
Vol 4 (3) ◽  
pp. 143
Author(s):  
Yorgos G. Stergiou ◽  
Aggelos T. Keramydas ◽  
Antonios D. Anastasiou ◽  
Aikaterini A. Mouza ◽  
Spiros V. Paras
Keyword(s):  
Blood Flow ◽  
Axial Velocity ◽  
Particle Image ◽  
Numerical Study ◽  
Implantable Devices ◽  
Cfd Simulations ◽  
Micro Particle Image Velocimetry ◽  
Image Velocimetry ◽  
Computational Fluid Dynamics Cfd ◽  
Cell Free Layer

The study of hemodynamics is particularly important in medicine and biomedical engineering as it is crucial for the design of new implantable devices and for understanding the mechanism of various diseases related to blood flow. In this study, we experimentally identify the cell free layer (CFL) width, which is the result of the Fahraeus–Lindqvist effect, as well as the axial velocity distribution of blood flow in microvessels. The CFL extent was determined using microscopic photography, while the blood velocity was measured by micro-particle image velocimetry (μ-PIV). Based on the experimental results, we formulated a correlation for the prediction of the CFL width in small caliber (D < 300 μm) vessels as a function of a modified Reynolds number (Re∞) and the hematocrit (Hct). This correlation along with the lateral distribution of blood viscosity were used as input to a “two-regions” computational model. The reliability of the code was checked by comparing the experimentally obtained axial velocity profiles with those calculated by the computational fluid dynamics (CFD) simulations. We propose a methodology for calculating the friction loses during blood flow in μ-vessels, where the Fahraeus–Lindqvist effect plays a prominent role, and show that the pressure drop may be overestimated by 80% to 150% if the CFL is neglected.

Analysis of Two-Phase Air/Water Bubbly Flow Experiment

2002 ◽  
Author(s):  
Donald R. Todd ◽  
Yassin A. Hassan ◽  
Javier Ortiz-Villafuerte
Keyword(s):  
Particle Image ◽  
Bubbly Flow ◽  
Continuous Phase ◽  
Three Dimensions ◽  
Dispersed Phase ◽  
Two Dimensional ◽  
Two Phase ◽  
Image Velocimetry ◽  
Flow Experiment ◽  
Shadow Image Velocimetry

Two different techniques, the Particle Image Velocimetry (PIV) and the Shadow-Image Velocimetry (SIV) techniques have been used to capture detailed two-phase bubbly flow experimental data. The PIV has provided a two-dimensional velocity field of the liquid phase for analysis of the continuous phase. The SIV has utilized to reconstruct the bubble shape and velocity of the dispersed phase in three-dimensions.

A Swirl Cooling Flow Experimental Investigation on a Circular Chamber Using Three-Dimensional Stereo-Particle Imaging Velocimetry

2019 ◽  
Vol 142 (4) ◽  
Author(s):  
Daisy Galeana ◽  
Asfaw Beyene
Keyword(s):  
Experimental Investigation ◽  
Axial Velocity ◽  
Three Dimensional ◽  
Swirl Flow ◽  
Internal Cooling ◽  
Swirl Number ◽  
Cooling Flow ◽  
Downstream Distance ◽  
Flow Phenomena ◽  
Particle Imaging

Abstract An experimental investigation is presented using three-dimensional (3-D) stereo-particle image velocimetry (stereo-PIV) of a swirl flow that models a gas turbine blade internal cooling configuration. The study is intended to provide an evaluation of the developments of the swirl cooling flow methodology utilizing the 3-D stereo-PIV. The objective is to determine the critical swirl number that has the potential to deliver the maximum axial velocity results. The swirl cooling flow methodology comprises cooling air channeling through the blade’s internal passages lowering the temperature; therefore, the experimental circular chamber is made of acrylic allowing detailed measurements and includes seven discrete tangential jets designed to create the swirl flow. An oil particle seeder (LAVision) is used to provide the particles for velocity measurements while the clear acrylic chamber allows visualization of the flow phenomena. The post-processed data are completed using davis, velocity calculations are conducted in matlab, and techplot is used for data visualization. The focus of this investigation is on the continuous swirl flow that must be sustained via continuous injection of tangential flow at three different Reynolds number, 7000, 14,000, and 21,000, where the swirl flow is generated with seven inlets. Important variations in the swirl number are present near the air inlets and decreases with downstream distance as predicted, since the second half of the chamber has no more inlets. The axial velocity reaches the maximum downstream in the second half of the chamber. The circumferential velocity decreases the downstream distance and reaches the highest toward the center of the chamber.

BUBBLY FLOW DYNAMICS STRUCTURE USING PARTICLE IMAGE VELOCIMETRY

1996 ◽  
Vol 3 (4) ◽  
pp. 311-318
Author(s):  
Yassin A. Hassan ◽  
William D. Schmidt ◽  
Javier Ortiz-Villafuerte
Keyword(s):  
Particle Image Velocimetry ◽  
Particle Image ◽  
Bubbly Flow ◽  
Flow Dynamics ◽  
Image Velocimetry

Dynamic Performance of the LeBlanc Balancer for Automatic Washing Machines

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Leonardo Urbiola-Soto ◽  
Marcelo Lopez-Parra
Keyword(s):  
High Speed ◽  
Dynamic Performance ◽  
Swirl Flow ◽  
Body Motion ◽  
Piv Technique ◽  
Washing Machines ◽  
Image Velocimetry ◽  
Modes Of Vibration ◽  
Transparent Liquid ◽  
Damping Capability

The paper describes a high-speed camera and a particle image velocimetry (PIV) technique used on a transparent liquid balancing device for washing machines. Experimental results indicate that the baffle-liquid interaction renders fluid modes of vibration of circumferential and axial types. This complex swirl flow is comprised of two inertial waves; one of such waves is synchronous with the rigid body motion, while the other is a fluid backward traveling wave, thus enhancing the system damping capability. This damping phenomenon was revealed by the fluid flow visualization and PIV technique employed.

A Study about Optimal Design for Preform Injection Mold for 3-Stage Injection Blowing System Using Finite Element Method

2013 ◽  
Vol 753-755 ◽  
pp. 249-252
Author(s):  
Tae Il Seo ◽  
Byeong Uk Song ◽  
Yong Seok Lim
Keyword(s):  
Process Efficiency ◽  
Injection Mold ◽  
Cooling Channels ◽  
Whole Process ◽  
Injection Process ◽  
Straight Line ◽  
Different Types ◽  
Process Simulations ◽  
Conventional Cooling

This paper presents a series of injection process simulations for blow molding preforms by using MoldFlow. The injection-blowing system was used and this consists 3 stages on the same machine; (1) preform injection, (2) blowing and (3) ejection. The quality of preform injection process is an important factor that can dominate the whole process efficiency. The injection mold system consists of 10 cavities and a hot runner system. The hot runner system has 10 cavities and temperature of each cavity can be independently controlled. Through several filling analyses, suitable temperature of each gate was determined so that all cavities could be simultaneously filled. Weld lines on the bottom of preforms were predicted. This fact can be an important aspect because preforms will be blown. To improve cooling efficiency, ''Floody Cooling Type" channels were applied. Conventional cooling channels were straight-line types and then distances between cooling channels and cavities cannot be uniformed. Floody cooling type channels were uniformly placed around cavities as far as possible. To compare two different types of cooling channels, cooling tests of MoldFlow were carried out and certain advantages of floody cooling type channels were evaluated.

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