Investigation of the effect of viscosity on slug flow in airlift tubular membranes in search of a sludge surrogate

2010 ◽  
Vol 61 (7) ◽  
pp. 1801-1809 ◽  
Author(s):  
N. Ratkovich ◽  
C. C. V. Chan ◽  
P. R. Bérubé ◽  
I. Nopens
Keyword(s):  
Activated Sludge ◽  
Carboxymethyl Cellulose ◽  
Slug Flow ◽  
High Speed ◽  
Vertical Tube ◽  
High Speed Camera ◽  
Flow Rates ◽  
The Difference ◽  
Newtonian Liquids ◽  
Tubular Membranes

The behaviour of three different liquid-gas slug flows (water, carboxymethyl cellulose and activated sludge) in a vertical tube was studied using a high speed camera (HSC). Experiments were performed using different flow rates and two tube diameters (6.3 and 9.9 mm). The observed difference in behaviour of the ascending gas slugs can be explained by the difference in viscosity of the fluids (Newtonian and non-Newtonian). Moreover, it was observed that the degree of coalescence of gas slugs is lower for non-Newtonian liquids and they behave like a succession of slugs without actually coalescing into a single larger gas slug. Finally, gas slug rising velocities were also extracted, but no subsequent difference in the rising velocities of the different fluids was found.

Film Thickness for Two Phase Flow in a Microchannel

2006 ◽  
Author(s):  
Ronan Grimes ◽  
Colin King ◽  
Edmond Walsh
Keyword(s):  
High Speed ◽  
Channel Wall ◽  
Experimental Program ◽  
Successful Implementation ◽  
Phase Flow ◽  
High Speed Camera ◽  
Micro Channel ◽  
Two Phase ◽  
Flow Rates ◽  
Carrier Fluid

The issue of contamination of micro channel surfaces by bio fluids is a significant impediment to the development of many biomedical devices. A solution to this problem is the use of a carrier fluid, which segments the bio fluid and forms a thin film between the bio fluid and the channel wall. A number of issues need to be addressed for the successful implementation of such a solution. Amongst these is the prediction of the thickness of the film of carrier fluid which forms between the bio sample and the channel wall. The Bretherton and Taylor laws relate the capillary number to the thickness of this film. This paper investigates the validity of these laws through an extensive experimental program in which a number of potential carrier fluids were used to segment aqueous droplets over a range of flow rates. The aqueous plugs were imaged using a high speed camera and their velocities were measured. Film thicknesses were calculated from the ratio of the velocity of the carrier fluid to the velocity of the aqueous plug. The paper concludes that significant discrepancies exist between measured film thicknesses and those predicted by the Bretherton and Taylor laws.

A Study on Gap Influence on Slamming Experiment

2012 ◽  
Author(s):  
C. W. Park ◽  
J. Y. Shin ◽  
S. H. Kwon ◽  
J. Y. Chung ◽  
S. B. Lee ◽  
...  
Keyword(s):  
Flow Field ◽  
High Speed ◽  
Gap Effect ◽  
High Speed Camera ◽  
Tank Wall ◽  
Central Location ◽  
The Difference

This study presents an investigation of gap effect on slamming experiment. Two gaps were considered; a gap between transverse side of a model and tank wall and a gap between longitudinal end and end of a model. The deadrise angle was fixed 0°. The pressure was measured at the central location and compared. Three different drop heights were chosen to see the difference. A High speed camera was used to record the flow field. Therefore pressure at the center, and flow field around corner of the specimen were analyzed to investigate the gap effect in slamming experiment. The results showed that there was clear influence of the gap in slamming experiment.

scholarly journals Boiling Synchronization in Two Parallel Minichannels—Image Analysis

Energies ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1409 ◽  
Author(s):  
Gabriela Rafałko ◽  
Iwona Zaborowska ◽  
Hubert Grzybowski ◽  
Romuald Mosdorf
Keyword(s):  
Image Analysis ◽  
Liquid Flow ◽  
Slug Flow ◽  
High Speed ◽  
Annular Flow ◽  
Bubble Flow ◽  
Phase Flow ◽  
High Speed Camera ◽  
Two Phase ◽  
Time Period

In this paper, the boiling synchronization of two-phase flow patterns in two parallel minichannels of 1 mm in diameter with connected compressible volumes was analyzed. The analysis was performed using images recorded with a high-speed camera. The degree of synchronization between channels was evaluated by assessing the presence of liquid flow in the small part of the minichannels. It can be concluded that boiling is synchronized when small bubble flow or wavy annular flow occur in neighboring channels. The occurrence of slug flow in one channel causes the boiling in neighboring channels to become unsynchronized. The result of the image analysis shows that the correlation coefficient based on the evaluation of the presence of liquid flow in the small part of the minichannels over a long enough time period allows for the detection of boiling synchronization.

THE KINEMATIC DIFFERENCES OF THREE TYPES OF CROUCHED POSITIONS DURING A SPRINT START

2016 ◽  
Vol 16 (07) ◽  
pp. 1650099 ◽  
Author(s):  
YO CHEN ◽  
KUANG-YA WU ◽  
YU-JU TSAI ◽  
WEN-TIEN YANG ◽  
JIA-HAO CHANG
Keyword(s):  
Repeated Measures ◽  
High Speed ◽  
Sagittal Plane ◽  
Center Of Mass ◽  
Step Length ◽  
Linear Velocity ◽  
High Speed Camera ◽  
Starting Position ◽  
The Difference ◽  
The Ideal

This study identifies the optimal crouched starting positions (elongated, medium, or bunched) from push-off to the first two steps. Seven elite sprinters were recruited as participants in this study (aged: 21[Formula: see text][Formula: see text][Formula: see text]2 years). A high-speed camera (250[Formula: see text]Hz) was used to collect motion-based images on a sagittal plane. Kwon3D (software) was used to analyze the center of mass (COM) movement, step length, foot linear velocity, take-off angle, and trunk angle. Participants were tested in a 60[Formula: see text]m sprint for bunched, medium, and elongated starting positions. A one-way analysis of variance (ANOVA) ([Formula: see text]) with repeated measures was performed to determine the difference in kinematics in the three crouched starting positions. The LSD comparison was applied to examine differences among pairs of means. Our results indicated that the medium starting position demonstrated a greater first step length and foot linear velocity when compared to the bunched starting position. In the first step toe-off, a lower COM vertical velocity was observed in the medium starting position when compared with the elongated starting position. This study concluded that the medium starting position was the ideal starting position.

scholarly journals Pengaruh Liquid Hold-Up terhadap Transisi Pola Aliran 2 Fasa Air-Udara dari Stratified Ke Slug pada Pipa 50 mm

2020 ◽  
Vol 4 (2) ◽  
pp. 75
Author(s):  
Andinusa Rahmandhika ◽  
Ali Saifullah ◽  
Pathur Razi Ansyah ◽  
Ali Mokhtar
Keyword(s):  
Film Thickness ◽  
Flow Pattern ◽  
Slug Flow ◽  
High Speed ◽  
Current Method ◽  
High Speed Camera ◽  
Visual Data ◽  
Liquid Slug ◽  
Pattern Change ◽  
Piping Systems

The slug flow pattern is one of the most avoiding factors in piping systems due to its destructive characteristics. Research on the criteria of the slug formation is still the concern. The present study focused on finding out the influence of liquid hold-up toward the transition of the flow pattern from stratified to slug pattern. It was conducted on a 50 mm-diameter horizontal acrylic pipe. The visual data was obtained from a fully developed area (180-210 D) by variations of liquid superficial rate (JL) of 0,03-0,3 m/s and gas superficial rate (JG) from 0,7 to 3,77 m/s. The high-speed camera with 2000 fps recording speed was the instrument to obtain the visual data. The measurement of the liquid hold-up is made by Constant Electric Current Method (CECM). The drastic decrement of liquid hold-up value on the wave growth mechanism (JG ≤ 1,88 m/s) indicated the changes in flow patterns from the stratified to the slug pattern, while on the wave coalescence mechanism (JG > 1,88 m/s) the liquid hold-up remains increases. The pattern change from pseudo slug to the slug pattern was not decreasing on its film thickness, yet, it tends to increase the frequency and the liquid slug length.

scholarly journals Polarity symmetry of leaders in moist air

2021 ◽  
Author(s):  
Shengxin Huang ◽  
Weijiang Chen ◽  
Zhong Fu ◽  
Weidong Shi ◽  
Nianwen Xiang ◽  
...  
Keyword(s):  
Temporal Resolution ◽  
High Speed ◽  
High Speed Camera ◽  
Moist Air ◽  
Macroscopic Behavior ◽  
Outstanding Problem ◽  
The Difference ◽  
Insight Into ◽  
Bidirectional Development

Abstract The most important physics underlying lightning is the leader discharge. The presence or absence of space stems/leaders in leader steps is the key to the polarity asymmetry of leaders, which describes the difference in macroscopic behavior between positive and negative leaders and is a long-term consensus among lightning physicists. It is generally believed that negative leader steps are led by space stem, and there is no space stem/leader in positive leader discharges. Here we report the emergence of the space stem and the bidirectional development of the space leader in positive leader steps in moist air, using a high-speed camera with unprecedented spatial-temporal resolution. The lifetime of space stem/leader in positive leader steps is shorter than that in negative leader steps, causing the uncover of space stem/leader in previous studies. The bidirectional development of space leaders in positive leader steps may be an important source for VHF radiations, illuminating insight into the outstanding problem that how positive lightning leaders produce VHF radiation.

Case study: Prediction and field tests of railway noise and effects of a low-height noise barrier

2020 ◽  
Vol 68 (4) ◽  
pp. 303-314
Author(s):  
Yuna Park ◽  
Hyo-In Koh ◽  
University of Science and Technology, Transpo ◽  
University of Science and Technology, Transpo ◽  
University of Science and Technology, Transpo ◽  
...  
Keyword(s):  
High Speed ◽  
Field Tests ◽  
Residential Areas ◽  
Railway Systems ◽  
Railway Noise ◽  
Sound Levels ◽  
Noise Barrier ◽  
The Difference ◽  
Reduction Effect ◽  
The Impact

Railway noise is calculated to predict the impact of new or reconstructed railway tracks on nearby residential areas. The results are used to prepare adequate counter- measures, and the calculation results are directly related to the cost of the action plans. The calculated values were used to produce noise maps for each area of inter- est. The Schall 03 2012 is one of the most frequently used methods for the production of noise maps. The latest version was released in 2012 and uses various input para- meters associated with the latest rail vehicles and track systems in Germany. This version has not been sufficiently used in South Korea, and there is a lack of standard guidelines and a precise manual for Korean railway systems. Thus, it is not clear what input parameters will match specific local cases. This study investigates the modeling procedure for Korean railway systems and the differences between calcu- lated railway sound levels and measured values obtained using the Schall 03 2012 model. Depending on the location of sound receivers, the difference between the cal- culated and measured values was within approximately 4 dB for various train types. In the case of high-speed trains, the value was approximately 7 dB. A noise-reducing measure was also modeled. The noise reduction effect of a low-height noise barrier system was predicted and evaluated for operating railway sites within the frame- work of a national research project in Korea. The comparison of calculated and measured values showed differences within 2.5 dB.

Activated Sludge Exocellular Material Extraction Methods and Problems

1974 ◽  
Vol 9 (1) ◽  
pp. 250-261
Author(s):  
D.F. Carr ◽  
J. Ganczarczyk
Keyword(s):  
Activated Sludge ◽  
High Speed ◽  
Sewage Treatment ◽  
Dry Weight ◽  
Extraction Methods ◽  
Volatile Material ◽  
Bacterial Cultures ◽  
Volatile Solids ◽  
Pure Bacterial Cultures ◽  
Material Extraction

Abstract Activated sludge samples from two Toronto sewage treatment plants were subjected to the extraction of exocellular material by means of 9 different methods suggested for this purpose. Some of those methods, originally developed for pure bacterial cultures, were modified for the application to activated sludge. The amount of exocellular material obtained varied for Lakeview sludges from 0.4 to 3.2% of their dry volatile solids, and for Humber sludges from 0.3 to 5.3%. It has been found that extractions by the use of sulphuric acid, high-speed centrifugation and sodium hydroxide, were not suitable for the studied material. Especially surprising was the ineffectiveness of high-speed centrifugation to yield any measurable amounts of extract. The boiling water extraction is recommended for further studies on activated sludge exocellular material. The material extracted from activated sludge is very complex in nature. Generally more polysaccharide than protein was extracted, but the remaining volatile material may form up to 70% of the dry weight.

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