scholarly journals Development of micro soap bubble generator for PIV tracer using home stereolithography 3D printer

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Shu Shibata ◽  
Takumi Yamazaki ◽  
Hisashi Matsuda
Keyword(s):  
Particle Size ◽  
Flow Velocity ◽  
Wall Thickness ◽  
Soap Bubble ◽  
3D Printer ◽  
Piv Measurement ◽  
Mainstream Flow ◽  
Inner Diameter ◽  
Nozzle Head ◽  
Central Pipe

A micro soap bubble generator for tracers for PIV measurement was developed using a home stereolithography 3D printer. The nozzle has a coaxial triple pipe structure, and an orifice cap is attached to the nozzle head. The inner diameter of the central pipe is 0.7 mm, and the wall thickness of the central pipe is 0.7 mm. From the comparison of the smoke wire visualization result of the flow around the cylinder placed under the mainstream flow velocity of 3 m/s and the PIV measurement result, it was confirmed that the generated micro soap bubbles have good followability to the flow. Generated bubbles’ particle size was estimated to be Φ0.2 mm at the minimum and Φ6.3 mm at the maximum. The most common was Φ0.9 mm ± 0.1 mm, accounting for more than 50% of the total.

scholarly journals The Hydrodynamic Dispersion Characteristics of Coral Sands

2019 ◽  
Vol 7 (9) ◽  
pp. 291 ◽  
Author(s):  
Xiang Cui ◽  
Changqi Zhu ◽  
Mingjian Hu ◽  
Xinzhi Wang ◽  
Haifeng Liu
Keyword(s):  
Particle Size ◽  
Porous Media ◽  
Flow Velocity ◽  
Molecular Diffusion ◽  
Dispersion Coefficient ◽  
Hydrodynamic Dispersion ◽  
Dispersion Characteristics ◽  
Factors Affecting ◽  
Mechanical Dispersion ◽  
Freshwater Aquifers

Dispersion characteristics are important factors affecting groundwater solute transport in porous media. In marine environments, solute dispersion leads to the formation of freshwater aquifers under islands. In this study, a series of model tests were designed to explore the relationship between the dispersion characteristics of solute in calcareous sands and the particle size, degree of compactness, and gradation of porous media, with a discussion of the types of dispersion mechanisms in coral sands. It was found that the particle size of coral sands was an important parameter affecting the dispersion coefficient, with the dispersion coefficient increasing with particle size. Gradation was also an important factor affecting the dispersion coefficient of coral sands, with the dispersion coefficient increasing with increasing d10. The dispersion coefficient of coral sands decreased approximately linearly with increasing compactness. The rate of decrease was −0.7244 for single-grained coral sands of particle size 0.25–0.5 mm. When the solute concentrations and particle sizes increased, the limiting concentration gradients at equilibrium decreased. In this study, based on the relative weights of molecular diffusion versus mechanical dispersion under different flow velocity conditions, the dispersion mechanisms were classified into five types, and for each type, a corresponding flow velocity limit was derived.

Controllability Over Wall Thickness of Tubular Structures and Encapsulation During Co-Axial Extrusion of a Thermal-Crosslinking Hydrogel

2020 ◽  
Vol 142 (8) ◽  
Author(s):  
Ilhan Yu ◽  
Samantha Grindrod ◽  
Roland Chen
Keyword(s):  
Flow Velocity ◽  
Wall Thickness ◽  
Dynamic Viscosity ◽  
Element Model ◽  
Extrusion Process ◽  
Tubular Structures ◽  
Needle Size ◽  
Thermal Crosslinking ◽  
Outer Needle ◽  
Phosphate Buffered Saline

Abstract Tubular structures of the hydrogel are used in a variety of applications such as delivering nutrient supplies for 3D cell culturing. The wall thickness of the tube determines the delivery rate. In this study, we used the coaxial extrusion process to fabricate tubular structures with varying wall thicknesses using a thermal-crosslinking hydrogel, gellan gum (GG). The objectives of this study are to investigate the thermal extrusion process of GG to form tubular structures, the range of achievable wall thickness, and a possibility to form tubular structures with closed ends to encapsulate fluid or drug inside the tube. The wall thickness is controlled by changing the relative flow velocity of the inner needle (phosphate-buffered saline, PBS) to the outer needle, while keeping the velocity of outer needles (GG) constant. Two pairs of coaxial needles were used which are 18-12 gauge (G) and 20-12G. The controllable wall thickness ranges from 0.618 mm (100% relative velocity) to 0.499 mm (250%) for 18-12G and from 0.77 mm (80%) to 0.69 (200%) for 20-12G. Encapsulation is possible in a smaller range of flow velocities in both needle combinations. A finite element model was developed to estimate the temperature distribution and the wall thickness. The model is found to be accurate. The dynamic viscosity of GG determines the pressure equilibrium and the range of achievable wall thickness. Changing the inner needle size or the flow velocity both affect the heat exchange and thus the temperature-dependent dynamic viscosity.

Effect of Development-Zone Restrictions on the Turbulent Characteristics of Impinging Jet Flow

2011 ◽  
Author(s):  
Takefumi Kawaguchi ◽  
Chandra Shekhar ◽  
Koichi Nishino
Keyword(s):  
Impinging Jet ◽  
Jet Flow ◽  
Stagnation Region ◽  
Development Zone ◽  
Potential Core ◽  
Turbulent Statistics ◽  
Piv Measurement ◽  
Turbulent Characteristics ◽  
Inner Diameter ◽  
Solid Block

This study is to examine the turbulent characteristics of an axisymmetric impinging jet flow in the stagnation region. The flow measurement is carried out using a standard PIV technique. The changes of the turbulent characteristics of the jet with various levels of the development-zone restriction are examined. The restrictions are imposed by putting an annular, concentric, solid block around the jet, and then varying its inner diameter. The PIV measurement of the flow field is carried out for each case. The height of the block is kept constant for all the cases, with the Reynolds number of 5000, which falls well within the turbulent range. The instantaneous velocity data obtained from the PIV measurement is used to calculate the turbulent statistics. The results are compared for all of the cases. In consequence, it is found that the turbulent statistics do not change much for the block’s inner diameter larger than a critical value, which is found to be three times the inlet diameter of the jet. However, if it is smaller, the turbulent statistics vary significantly, as the inner wall of the block damages the development of the potential core of the jet.

Unsteady Simulations for an Advanced-Louver Cooling Scheme

2008 ◽  
Author(s):  
Chad X.-Z. Zhang ◽  
Sung In Kim ◽  
Ibrahim G. Hassan
Keyword(s):  
Reynolds Number ◽  
Wind Tunnel ◽  
Flat Plate ◽  
Flow Velocity ◽  
Detached Eddy Simulation ◽  
Computer Cluster ◽  
Vortical Structures ◽  
Eddy Simulation ◽  
Mainstream Flow ◽  
Adiabatic Effectiveness

The performance of a louver cooling scheme on a flat plate was analyzed using Detached Eddy Simulation. It was assumed that the louver cooling scheme was tested in a wind tunnel with the mainstream flow velocity of 20 m/s, equivalent to a Reynolds number of 16200 based on the jet diameter. Turbulence closure was achieved by a Realizable k-ε based DES turbulence model. Solutions of two blowing ratios of 0.5 and 1 were successfully obtained by running parallel on 16 nodes on a computer cluster. The instantaneous flow fields were found to be highly unsteady and oscillatory in nature. It is shown that the fluctuations in the adiabatic effectiveness are mainly caused by the spanwise fluctuation of the coolant jet and the unsteady vortical structures created by the interaction of the jet and the mainstream.

Under Pressure Operations on Dense Phase CO2 Pipelines: Issues for the Operator

2014 ◽  
Author(s):  
Julian Barnett ◽  
Richard Wilkinson ◽  
Alan Kirkham ◽  
Keith Armstrong
Keyword(s):  
Natural Gas ◽  
Flow Velocity ◽  
Wall Thickness ◽  
Gaseous Phase ◽  
Operating Conditions ◽  
Cooling Time ◽  
Phase Behaviour ◽  
Pipeline System ◽  
Dense Phase ◽  
Pressure Welding

National Grid, in the United Kingdom (UK), has extensive experience in the management and execution of under pressure operations on its natural gas pipelines. These under pressure operations include welding, ‘hot tap’ and ‘stopple’ operations, and the installation of sleeve repairs. National Grid Carbon is pursuing plans to develop a pipeline network in the Humber and North Yorkshire areas of the UK to transport dense phase Carbon Dioxide (CO2) from major industrial emitters in the area to saline aquifers off the Yorkshire coast. One of the issues that needed to be resolved is the requirement to modify and/or repair dense phase CO2 pipeline system. Existing under pressure experience and procedures for natural gas systems have been proven to be applicable for gaseous phase CO2 pipelines; however, dense phase CO2 pipeline systems require further consideration due to their higher pressures and different phase behaviour. Consequently, there is a need to develop procedures and define requirements for dense phase CO2 pipelines. This development required an experimental programme of under pressure welding trials using a flow loop to simulate real dense phase CO2 pipeline operating conditions. This paper describes the experiments which involved: • Heat decay trials which demonstrated that the practical limitation for under pressure welding on dense phase CO2 systems will be maintaining a sufficient level of heat to achieve the cooling time from 250 °C to 150 °C (T250–150) above the generally accepted 40 second limit. • A successful welding qualification trial with a welded full encirclement split sleeve arrangement. The work found that for the same pipe wall thickness, flow velocity and pressure, dense phase CO2 has the fastest cooling time when compared with gaseous phase CO2 and natural gas. The major practical conclusion of the study is that for dense phase CO2 pipelines with a wall thickness of 19.0 mm or above, safe and practical under pressure welding is possible in accordance with the existing National Grid specification (i.e. T/SP/P/9) up to a flow velocity of around 0.9 m/s. The paper also outlines the work conducted into the use of the Manual Phased Array (MPA) inspection technique on under pressure welding applications. Finally, the paper identifies and considers the additional development work needed to ensure that a comprehensive suite of under pressure operations and procedures are available for the pipeline operator.

scholarly journals The Rule of Carrying Cuttings in Horizontal Well Drilling of Marine Natural Gas Hydrate

Energies ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1129 ◽  
Author(s):  
Na Wei ◽  
Yang Liu ◽  
Zhenjun Cui ◽  
Lin Jiang ◽  
Wantong Sun ◽  
...  
Keyword(s):  
Particle Size ◽  
Flow Velocity ◽  
Gas Hydrate ◽  
Horizontal Well ◽  
Drilling Fluid ◽  
Test Method ◽  
Critical Flow ◽  
Fluid Density ◽  
Critical Flow Velocity ◽  
Orthogonal Test Method

Horizontal well drilling is a highly effective way to develop marine gas hydrate. During the drilling of horizontal wells in the marine gas hydrate layer, hydrate particles and cutting particles will migrate with the drilling fluid in the horizontal annulus. The gravity of cuttings is easy to deposit in the horizontal section, leading to the accumulation of cuttings. Then, a cuttings bed will be formed, which is not beneficial to bring up cuttings and results in the decrease of wellbore purification ability. Then the extended capability of the horizontal well will be restricted and the friction torque of the drilling tool will increase, which may cause blockage of the wellbore in severe cases. Therefore, this paper establishes geometric models of different hole enlargement ways: right-angle expansion, 45-degree angle expansion, and arc expanding. The critical velocity of carrying rock plates are obtained by EDEM and FLUENT coupling simulation in different hydrate abundance, different hydrate-cuttings particle sizes and different drilling fluid density. Then, the effects of hole enlargement way, particle size, hydrate abundance and drilling fluid density on rock carrying capacity are analyzed by utilizing an orthogonal test method. Simulation results show that: the critical flow velocity required for carrying cuttings increases with the increase of the particle size of the hydrate-cuttings particle when the hydrate abundance is constant. The critical flow velocity decreases with the increase of drilling fluid density, the critical flow velocity carrying cuttings decreases with the increase of hydrate abundance when the density of the drilling fluid is constant. Orthogonal test method was used to evaluate the influence of various factors on rock carrying capacity: hydrate-cuttings particle size > hole enlargement way > hydrate abundance > drilling fluid density. This study provides an early technical support for the construction parameter optimization and well safety control of horizontal well exploitation models in a marine natural gas hydrate reservoir.

The Effect of Sound Pressure on the Aeroacoustic Sources Around Two Ducted Tandem Cylinders

2010 ◽  
Author(s):  
Shane Leslie Finnegan ◽  
Craig Meskell ◽  
Samir Ziada
Keyword(s):  
Flow Velocity ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Acoustic Resonance ◽  
Pressure Level ◽  
Acoustic Energy ◽  
Source Distribution ◽  
Main Stream ◽  
Tandem Cylinders ◽  
Mainstream Flow

An empirical investigation of the spatial distribution of aeroacoustic sources around two tandem cylinders subject to ducted flow and forced transverse acoustic resonance is described. The work builds on a previous investigation by the authors and utilises Howe’s theory of aerodynamic sound. The influence of the sound pressure level in the duct on the strength and location of the aeroacoustic sources in the flow was the main focus of the investigation and experiments to resolve the aeroacoustic source distribution were concentrated at a low main-stream flow velocity (before acoustic-Strouhal coincidence), at a medium mainstream flow velocity (just after acoustic-Strouhal coincidence) and at a high mainstream flow velocity (substantially higher than acoustic-Strouhal coincidence). The sound pressure level was found to have a considerable effect on the “lock-in”’ range of the cylinders which widened as the sound pressure level increased. A proposed normalisation of the net acoustic energy transfer per spanwise location appears to show good metric for the distribution of the aeroacoustic sources in the flow field. Using this, it was found that the amplitude of the sound pressure had a negligible influence on the aeroacoustic sources in the wake and the gap region for all the tested cases apart from the lowest flow velocity. This particular case showed indications that the aeroacoustic source strength and location could be altered for certain changes in sound pressure level.

Equidirectional Umbrella Diameter Changing Mechanism for Ultrasonic Inspection of Seabed Pipelines

2010 ◽  
Vol 163-167 ◽  
pp. 2927-2933
Author(s):  
Chong Zhen Cao ◽  
Feng Qin Wang ◽  
Qi Fa Tian ◽  
Jia Lan Zhuang ◽  
Feng Chun Li
Keyword(s):  
Wall Thickness ◽  
Ultrasonic Inspection ◽  
Machine Experiment ◽  
Oil Pipelines ◽  
Inner Diameter

Ultrasonic inspection is a key method of inspecting wall thickness flaw of seabed oil pipelines. How to lay out ultrasonic probes to fit for three inner diameter pipelines of Φ195mm, Φ247mm and Φ297mm was analyzed detailed. Diameter changing principle feasibility of ultrasonic inspection adopting 10 parallelogram mechanisms was discussed, and the key parts of structure of equidirection umbrella diameter changing mechanism were analyzed. In the end model machine experiment verified that equidirection umbrella diameter changing technology is feasible.

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