scholarly journals Measurement of Circumferential Liquid Film Based on LIF and Virtual Stereo Vision Sensor

2016 ◽  
Vol 2016 ◽  
pp. 1-5 ◽  
Author(s):  
Ting Xue ◽  
Xiaokang Lin ◽  
Liuxiangzi Yang
Keyword(s):  
Liquid Film ◽  
Stereo Vision ◽  
High Speed ◽  
Annular Flow ◽  
Flow Characteristic ◽  
Thickness Distribution ◽  
Flow Characteristics ◽  
Industrial Applications ◽  
Vision Sensor ◽  
Feature Parameters

Gas-liquid annular flow is widely used in many industrial applications such as petroleum, chemical, and nuclear engineering. The feature parameters of liquid film in the annular flow are of great significance to understand the flow characteristics and measure the flow precisely. For the annular flow, the circumferential features of liquid film are more important than the axial features to acquire abundant flow structures and reveal the flow mechanism. In the paper, a measurement platform based on the laser-induced fluorescence (LIF) and virtual stereo vision sensor is presented. The virtual stereo vision sensor comprises a high-speed camera and two optical reflection sets, which can acquire the liquid film from two views simultaneously and reconstruct the features of liquid film. Image processing techniques are proceeded with to extract the feature parameters of liquid film; then the circumferential flow characteristic can be reconstructed by views transformation and fusion. The flow characteristic based on the thickness distribution is analysed. The experimental results show that the method is valid and effective, which can give a more detailed and accurate description for the liquid film in annular flows.

scholarly journals Experimental study of wavy-annular flow in a rectangular microchannel using LIF method

2021 ◽  
Vol 2119 (1) ◽  
pp. 012061
Author(s):  
G V Bartkus ◽  
V V Kuznetsov
Keyword(s):  
Film Thickness ◽  
Liquid Film ◽  
High Speed ◽  
Annular Flow ◽  
Flow Characteristics ◽  
Superficial Velocity ◽  
Graphical Form ◽  
Rectangular Microchannel ◽  
Gas Phases ◽  
Average Film Thickness

Abstract This article aims at studying gas-liquid flow in a rectangular microchannel with a high aspect ratio (200 × 2045 μm). Liquid and gas phases were 95% ethanol and nitrogen mixture. Experimental flow characteristics are obtained using high-speed visualization and laser-induced fluorescence (LIF) methods. Using the LIF method for wavy-annular flow, the average film thickness, liquid film distribution, and liquid film width were measured. The dependences of the liquid film width and the average film thickness on gas superficial velocity are presented in graphical form and analyzed. An increase in gas superficial velocity causes growth of the liquid film width and thickness of the liquid film, which indicates the process of liquid transfer from the menisci area to the liquid film. For different liquid velocities and the same gas superficial velocities, close values of averaged liquid film thickness were observed for flow with 2D waves and 3D waves on liquid film.

Liquid Film Thickness Prediction in Elbows for Annular Flows

2017 ◽  
Author(s):  
Peyman Zahedi ◽  
Hadi Arabnejad Khanouki ◽  
Brenton S. McLaury ◽  
Siamack A. Shirazi
Keyword(s):  
Experimental Data ◽  
Film Thickness ◽  
Liquid Film ◽  
Annular Flow ◽  
Control Volume ◽  
Thickness Distribution ◽  
Current Model ◽  
Industrial Applications ◽  
Gas Production ◽  
Liquid Film Thickness

In many industrial applications such as oil and gas production systems and heat exchangers, annular flow is a frequently observed flow regime. A lot of experiments and analysis have been carried out in the last decades in order to determine the thickness of the liquid film in annular flow and in straight pipes; however, published liquid film thickness models and experimental data in bends are scare. This paper presents a model for predicting average liquid film thickness in bends according to the correlations obtained for calculating dimensionless interfacial friction factor as well as dimensionless liquid film thickness in bends. Correlations were obtained based on analysis carried out using a control volume of gas core and utilizing experimental data available in the literature for liquid film thickness in bends. Furthermore, liquid film thickness distribution at the inner and outer bends of elbows were investigated, and a simple analytical model has been developed for predicting film thickness at the outer and inner radii of a bend. It is shown that, the average film thickness calculations from the current model agree with experimental data and results show that the model can predict the film thickness changes based on the flowrates and properties of liquid and gas phases.

Study on Flow Characteristics inside a Spillway Tunnel of Hydropower Station

2014 ◽  
Vol 716-717 ◽  
pp. 219-222
Author(s):  
Hong Qing Zhang ◽  
Bing Cao ◽  
Yi Long Lou ◽  
Wei Kai Tan
Keyword(s):  
Flow Velocity ◽  
High Speed ◽  
Flow Characteristic ◽  
Flow Characteristics ◽  
Hydropower Station ◽  
Turbulent Model ◽  
Cross Sectional ◽  
Vof Model ◽  
Spillway Tunnel ◽  
The Right

VOF model and turbulent model were used in this paper to study on flow characteristic inside a certain spillway tunnel of hydropower station, which includes cross sectional distributions of flow velocity in pressure section and non-pressure section. The results show that flow velocity distribution in the pressure section of the spillway tunnel is basically symmetrical. After turning, flow velocity is well-distributed and move ahead; flow velocity in the right side of non-pressure section in the spillway tunnel is 1m/s faster than that in the left side. When two high-speed water flow come together after passing through the central division pier, flow velocity distributions in the both sides of the spillway tunnel are all uniform. The conclusions obtained can improve the design of the spillway tunnel.

scholarly journals Experimental Investigation of Annular Flow Behaviour in Horizontal Pipe

2021 ◽  
Vol 13 (6) ◽  
Author(s):  
Osokogwu Osokogwu ◽  
◽  
Uche Uche ◽  
Keyword(s):  
Film Thickness ◽  
Liquid Film ◽  
Slug Flow ◽  
High Speed ◽  
Annular Flow ◽  
Flow Behavior ◽  
Liquid Film Thickness ◽  
Experimental Investigations ◽  
Internal Diameter ◽  
Horizontal Pipe

The experimental investigations of annular flow were conducted in horizontal pipe using water/air in a 0.0504m internal diameter pipe loop with a total length of 28.68m. To understand annular flow behaviors, conductivity ring sensors, conductance probe sensors and Olympia high speed digital camera were used. In all the experiments, emphasis were on annular flow behavior, phase distribution and liquid film thickness. Liquid film thickness was observed to be thicker mostly when the superficial gas velocities were within 8.2699 m/s to 12.0675 m/s. Above the aforementioned superficial gas velocities, the flow became uniformly distributed on the walls of the internal pipe diameter hence reducing the thicker liquid film at the bottom with gas core at the center of the pipe. More so, annular-slug flow was discovered in the investigation. At superficial liquid velocity of 0.0505 m/s-0.1355 m/s on superficial gas velocities of 8.2699 m/s – 12.0675 m/s, annular-slug flow was prominent. Also discovered was at superficial liquid velocities of 0.0903 m/s - 0.1355 m/s with respect to superficial gas velocities of 13.1692 m/s – 23.4575 m/s, the pipe walls are fully covered with liquid film at very high speed at the entire walls (upper walls and bottom). Also discovered in this experiment is the wavy flow of the upper walls. The liquid film thickness that flows at the upper pipe walls, creeps in a wavy flow. Therefore, the entire flow behavior in an annular flow could be grouped into; wavy-flow at the upper walls, annular-slug flow and thicker liquid film at the bottom with gas core at the center.

A Mechanistic Model of Liquid Film Movements in Pipe Elbows for Annular Flow

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Mingyang Liu ◽  
Haixiao Liu
Keyword(s):  
Film Thickness ◽  
Liquid Film ◽  
Cross Section ◽  
Annular Flow ◽  
Initial Conditions ◽  
Mechanistic Model ◽  
Thickness Distribution ◽  
Film Surface ◽  
Axial Distance ◽  
Cross Sectional

A mechanistic model of film movements is developed based on the treatments on the annular flow field. The initial conditions at the inlet are determined by adopting a validated film thickness correlation of fully developed upward annular flow in vertical pipes. The overall pressure gradient is assumed to be uniform all along the axial distance within the elbow and the static pressure is also uniform on every cross section. The axial velocities of the liquid film and the core region are both uniform on the cross-sectional plane. The droplets are assumed to travel in straight lines normal to the inlet plane until colliding on and absorbed by the liquid film surface. The liquid film motion is divided into the axial and radial directions. Energy conservation law and Newton's second law are, respectively, used in the two directions. The film motion calculation is executed by using a discrete method with an explicit solution. The average film thickness and the circumferential thickness distribution on an arbitrary cross section can be obtained for the given flow conditions. The mechanistic model is verified by comparing the predicted circumferential distribution of film thickness with three series of experimental data from the literature. Parametric studies are also conducted to investigate the parameter effects and the range of application. The present work proves that the variation and distribution of film thickness within the elbows can be efficiently described by the mechanistic model.

The Flow of Slugs in Horizontal, Two-Phase Pipelines

1990 ◽  
Vol 112 (1) ◽  
pp. 20-24 ◽  
Author(s):  
G. E. Kouba ◽  
W. P. Jepson
Keyword(s):  
Liquid Film ◽  
Froude Number ◽  
High Speed ◽  
Liquid Fraction ◽  
Flow Characteristics ◽  
Translational Velocity ◽  
Two Phase ◽  
Different Types ◽  
Channel Hydraulics ◽  
Mixture Velocity

The flow characteristics in horizontal slug flow are studied experimentally in the Harwell Laboratory 150-mm-dia pipeline. If a frame of reference is taken as moving with the translational velocity of the slug, measurements of the Froude number in the liquid film ahead of the slug were always greater than unity while the Froude number within the slug was in general less than unity. This illustrates a change in flow from super to subcritical flow and the presence of a hydraulic jump. Different types of flow are noticed using high-speed video equipment and these types closely resemble those reported by open-channel hydraulics tests. The distribution of gas in the slug body is only homogeneous at high-mixture velocities and the effect of buoyancy on the gas is more noticeable at low gas velocities. The liquid fraction in the slug is shown to be directly dependent on the Froude number in the liquid film. The ratio of the translational velocity of the slug to the mixture velocity decreases continuously from 2.0 at low-mixture velocities to 1.25 and a mixture velocity of approximately 3m/s. After this point, it remains constant at 1.25.

scholarly journals Analysis of the possibility of using high-speed pneumatic directional valves to regulate the flow of compressed air

2019 ◽  
Vol 213 ◽  
pp. 02084
Author(s):  
Jakub Takosoglu
Keyword(s):  
Flow Rate ◽  
High Speed ◽  
Flow Characteristic ◽  
Position Control ◽  
Experimental Studies ◽  
Flow Characteristics ◽  
Control Signal ◽  
Compressed Air ◽  
Flow Parameters ◽  
Proportional Flow

Most often, proportional flow valves or flow servovalves are used for position control of pneumatic drives. In case of this type of valves, flow characteristic of the valve represents a dependence of flow rate upon analogue control signal (voltage or current). The paper presents experimental studies of two high-speed pneumatic 3/2 directional valves (3-way 2-position) in order to determine the flow characteristics and flow parameters. One has analysed the option to use the directional valves to control the flow rate of compressed air using frequency-based signals.

Physics of Transition to Annular Flow in Microchannel Flow Boiling Process

2018 ◽  
Author(s):  
Meisam Matin ◽  
Abdy Fazeli ◽  
Saeed Moghaddam
Keyword(s):  
Liquid Film ◽  
Flow Regime ◽  
High Speed ◽  
Annular Flow ◽  
Flow Boiling ◽  
Thermal Characteristics ◽  
Transitional Region ◽  
Boiling Process ◽  
The Difference ◽  
Complex Phenomena

Transition to annular flow regime in microchannels is arguably one of the most complex phenomena in the flow boiling process. The instability of the vapor-liquid interface in this interstitial regime presents an intricate situation in which the interface pattern rapidly changes with the mass flow rate and surface heat flux. Although a few past studies have reported observing this regime, thermohydraulics of the process and flow and boundary conditions under which this transition occurs have remained largely unknown. The main obstacle in deciphering the physics of this process is lack of measurement tools to characterize hydrodynamics and thermal characteristics of this flow regime at microscales. The present study benefits from implementation of a novel test device that enables measuring the liquid film thickness and its rapid variations with micrometer and microseconds spatial and temporal resolutions. It is determined that each flow regime has a unique surface temperature signature that enables its clear distinction without need for high-speed visualization. Based on the dynamics of the flow, we identified that the transitional region is comprised of two regimes coalescing bubbles (CB) and semi-annular flow conditions. The difference between these two flow regimes emanates from motion of liquid film beneath the bubble.

Visualization of the near Field Microscopic Spray Structure in Diesel Engine

2014 ◽  
Vol 1078 ◽  
pp. 276-279
Author(s):  
Zhi Sheng Gao ◽  
Qian Wang ◽  
Yu Qiang Wu ◽  
Zhi Xia He ◽  
Li Ming Dai
Keyword(s):  
High Speed ◽  
Flow Characteristic ◽  
Near Field ◽  
Flow Characteristics ◽  
Injection Pressure ◽  
Helical Flow ◽  
High Speed Camera ◽  
Spray Structure ◽  
Fuel Jet ◽  
Periodical Structure

Based on the high speed camera combined with a microscopic lens the near-nozzle spray surface structure and flow characteristics of the high pressure diesel fuel jet were investigated. During the steady period of the spray development, the periodically undulatory structure was observed at the circular direction of the jet at the near nozzle area at the injection pressure of 5MPa. The atomization of the spray improved and the periodical structure was veiled by fine droplets at higher injection pressure of 40MPa. During the closing period of the nozzle lift, the spiraling shape was also observed along the surface of the fuel jet which indicates the internal helical flow characteristic.

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