A Fast Electrical Resistivity-Based Algorithm to Measure and Visualize Two-Phase Swirling Flows

Electrical Resistance Tomography (ERT) has been used in the literature to monitor the gas-liquid separation. However, the image reconstruction algorithms used in the studies take a considerable amount of time to generate the tomograms, which is far above the time scales of the flow inside the inline separator and, as a consequence, the technique is not fast enough to capture all the rele-vant dynamics of the process, vital for control applications. This article proposes a new strategy based on the physics behind the measurement and simple logics to monitor the separation with a high temporal resolution by minimizing both the amount of data and the calculations required to reconstruct one frame of the flow. To demonstrate its potential, the electronics of an ERT system are used together with a high-speed camera to measure the flow inside an inline swirl separator. For the 16-electrode system used in this study, only 12 measurements are required to reconstruct the whole flow distribution with the proposed algorithm, 10x less than the minimum number of measurements of ERT (120). In terms of computational effort, the technique was shown to be 1000x faster than solving the inverse problem non-iteratively via the Gauss-Newton approach, one of the computationally cheapest techniques available. Therefore, this novel algorithm has the potential to achieve measurement speeds in the order of 104 times the ERT speed in the context of inline swirl separation, pointing to flow measurements at around 10kHz while keeping the aver-age estimation error below 6 mm in the worst case scenario.

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Simultaneous two-phase flow measurements in a high-speed particle-laden under-expanded jet

14th International Symposium on Particle Image Velocimetry ◽

10.18409/ispiv.v1i1.171 ◽

2021 ◽

Vol 1 (1) ◽

Author(s):

Miguel Xavier Diaz-Lopez ◽

Juan Sebastian Rubio ◽

Rui Ni

Keyword(s):

Pulse Width ◽

High Speed ◽

Aerodynamic Drag ◽

Inertial Particles ◽

Two Phase ◽

Flow Measurements ◽

Future Studies ◽

Two Phases ◽

Image Pairs ◽

Particle Laden Flow

The objective of this study is to understand the dynamics of a high-speed particle-laden under-expanded jet, motivated by landings on extraterrestrial bodies. In this setup, inertial particles are entrained and accelerated by an under-expanded jet. But, due to their inertia, the particle velocity is significantly lower than that of the surrounding gas close to the nozzle, so the two phases are coupled through aerodynamic drag. Sub-micron oil droplets are dispensed upstream to serve as tracers, whose velocity is determined through a PIV system; inertial particles, after image segmenting is performed to separate them from PIV data, will be tracked over time with a PTV system. This was accomplished with a single laser pulse and the camera straddle time to produce image pairs and shorten the pulse width. The results will help to understand particle-laden flow in a new regime where the background flow is compressible and the Mach number based on the slip velocity is not negligible, which may help to pave a foundation for future studies in compressible multiphase flows.

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Effect of Calibration Error on Bone Tracking Accuracy With Fluoroscopy

Journal of Biomechanical Engineering ◽

10.1115/1.4027058 ◽

2014 ◽

Vol 136 (5) ◽

Cited By ~ 3

Author(s):

Luca Tersi ◽

Rita Stagni

Keyword(s):

Pose Estimation ◽

Linear Trend ◽

Estimation Error ◽

Image Plane ◽

Joint Kinematics ◽

Estimation Accuracy ◽

Calibration Error ◽

Tracking Accuracy ◽

Case Scenario ◽

Worst Case

Model-based 3D-fluoroscopy can quantify joint kinematics with 1 mm and 1 deg accuracy level. A calibration based on the acquisition of devices of known geometry is usually applied to size the system. This study aimed at quantifying the sensitivity of the fluoroscopic pose estimation accuracy specifically to errors in the calibration process, excluding other sources of error. X-ray focus calibration error was quantified for different calibration setups, and its propagation to the pose estimation was characterized in-silico. Focus reference position influenced the calibration error dispersion, while calibration cage pose affected its bias. In the worst-case scenario, the estimation error of the principal point and of the focus distance was lower than 1 mm and 2 mm, respectively. The consequent estimation of joint angles was scarcely influenced by calibration errors. A linear trend was highlighted for joint translations, with a sensitivity proportional to the distance between the model and the image plane, resulting in a submillimeter error for realistic calibration errors. The biased component of the error is compensated when computing relative joint kinematics between two segments.

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Performance improvement of communication based high speed train control system with packet drops during handover under worst case scenario

2017 7th International Conference on Cloud Computing, Data Science & Engineering - Confluence ◽

10.1109/confluence.2017.7943185 ◽

2017 ◽

Cited By ~ 2

Author(s):

Rajesh Mishra ◽

Bhupendra Singh ◽

Shobhna Tiwari

Keyword(s):

Control System ◽

Performance Improvement ◽

High Speed ◽

High Speed Train ◽

Case Scenario ◽

Worst Case ◽

Train Control ◽

Worst Case Scenario ◽

Train Control System

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Images Analysis of Horizontal Two-Phase Slug Flows

Volume 6: Fluids and Thermal Systems; Advances for Process Industries, Parts A and B ◽

10.1115/imece2011-62483 ◽

2011 ◽

Cited By ~ 1

Author(s):

R. E. M. Morales ◽

M. J. da Silva ◽

E. N. Santos ◽

L. Dorini ◽

C. E. F. do Amaral ◽

...

Keyword(s):

High Speed ◽

Oil And Gas Industry ◽

Industrial Applications ◽

Wire Mesh ◽

Bubble Velocity ◽

Internal Diameter ◽

Two Phase ◽

Experimental Conditions ◽

Flow Measurements ◽

Slug Flows

Multi-phase flow measurements are very common in industrial applications especially of the oil and gas industry. In order to study such pattern one can apply many different techniques such as capacitive probes, X-ray and gamma ray tomography, ultrasound transducers, wire-mesh sensors and high speed videometry. This article describes experimental study of water-air slug in horizontal pipes through non-intrusive image analysis technique. A flow test section comprising of a pipe of 26 mm internal diameter and 9 m long was employed to generate slug flows under controlled conditions. The behavior of the flow was studied using gas and liquid velocities between 0.3 m/s and 2 m/s with 6000 images (500×232 pixels) for each case. The algorithm comprises the automatic analysis of a sequence of frames in MatLab to measure flow characteristics such as Taylor bubble velocity and frequency applying morphological treatment. Finally, the parameters measured through the high speed videometry were compared with theoretical predictions showing that such method can be used to validate other types of sensors in experimental conditions.

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Experimental Analysis of a Liquid-Gas Two-Phase Flow in a Flow Distributor

Volume 4: Fluid Measurement and Instrumentation; Micro and Nano Fluid Dynamics ◽

10.1115/ajkfluids2019-5443 ◽

2019 ◽

Author(s):

Luiz H. M. Lino ◽

Henrique K. Eidt ◽

Carolina C. Rodrigues ◽

Cesar Y. Ofuchi ◽

Paulo H. D. Santos ◽

...

Keyword(s):

Distribution System ◽

High Speed ◽

Two Phase Flow ◽

Flow Distribution ◽

Experimental Tests ◽

Wire Mesh ◽

Liquid Volume ◽

Phase Flow ◽

Two Phase ◽

Operational Conditions

Abstract The main goal of this work is to analyze the efficiency of a two-phase flow distribution system for different operational conditions, which was designed and built by the Multiphase Flow Research Center (NUEM). The distribution system is composed of a two tangential inlets, a cyclonic chamber, and four outlets. The working principle of this apparatus is based on the combined action of centrifugal and gravitational forces, which causes the development of a liquid film, facilitating the flow distribution. Four outlets are located perpendicularly to the cyclonic chamber in order to distribute the flow equally to some extent. Experimental tests were performed using water and air in a vertical 52-mm ID acrylic pipe. Two flow patterns (bubble and slug) at the input of the inlets were visually identified through the use of a high-speed camera. To verify the flow distribution, wire-mesh sensors were installed at each outlet and graduated beakers and a timer was used in order to estimate the liquid volume flowing at the outlets. The results showed that the flow distribution system has a satisfactory efficiency of distribution.

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Identification of Two-Phase Flow Patterns Using Support Vector Classification

Volume 4: Fluid-Structure Interaction ◽

10.1115/pvp2017-65179 ◽

2017 ◽

Author(s):

Ines Benito ◽

Njuki W. Mureithi

Keyword(s):

High Speed ◽

Two Phase Flow ◽

Flow Patterns ◽

Support Vector ◽

Svm Classifier ◽

Phase Flow ◽

Two Phase Flows ◽

Two Phase ◽

Flow Measurements ◽

Tube Arrays

Two-phase flows are preponderant in industrial components. The present work deals with external two-phase flows across tube banks commonly found in heat exchangers, boilers and steam generators. The flows are generally highly complex and remain theoretically intractable in most cases. The two-phase flow patterns provide a convenient albeit qualitative means for describing and classifying two phase flows. The flow patterns are also closely correlated to fluid-structure interaction dynamics and thus provide a practically useful basis for the study of two-phase flow-induced vibrations. For internal two-phase flows, maps by Taitel et al. (1980) and others have led to detailed and well defined maps. For transverse flows in tube bundles, there is significantly less agreement on the flow patterns and governing parameters. The complexity of flow in tube arrays is an obvious challenge. A second difficulty is the definition of distinct flow patterns and the identification of parameters uniquely identifying the flow patterns. The present work addresses the problem of two-phase flow pattern identification in tube arrays. Flow measurements using optical as well as flow visualization via high-speed videos and photography have been conducted. To identify the flow patterns, an artificial intelligence machine learning approach was taken. Pattern classification was achieved by designing a support vector machine (SVM) classifier. The SVM achieves quantitative and non-subjective classification by mapping the flow patterns in a high dimensional mathematical space in which the different flow patterns have unique characteristics. Details of the flow measurement, parameter definition and SVM design are presented in the paper. Flow patterns identified using the SVM are presented and compared with previously identified flow patterns.

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A FORMULA PROPOSED FOR ESTIMATING THE LONGITUDINAL EXTENT OF RAKING DAMAGE TO THE HULL OF A HIGH-SPEED VESSEL

10.3940/rina.ijsct.2015.b2.168 ◽

2015 ◽

Vol 157 (B2) ◽

Author(s):

O O Kanifolskyi

Keyword(s):

Kinetic Energy ◽

High Speed ◽

Case Scenario ◽

Worst Case ◽

Small Vessels ◽

Worst Case Scenario ◽

Ship Grounding ◽

Hull Damage ◽

Large Vessels

The old and new requirements of the High Speed Craft Code, and the methods used by some researchers for calculating the damage length for a ship’s hull, are considered in this paper. Damage occurs more often in small vessels than in large vessels. Collisions between ships and ship grounding are two of the main reasons for the loss of ships. The damage to a vessel is determined for the worst case scenario. Long and narrow ("raking") damage, which absorbs the kinetic energy of the vessel, is the worst-case scenario. Small high speed craft were selected for analysis. This paper describes the requirements of the High Speed Craft Code related to high-speed vessels. Small semi planing vessels are a category of high-speed vessels, operated at volume Froude numbers between 1 and 3. The formula for calculating the length of the possible hull damage should take into account the material, the thickness of the plating, the width of the damage, the vessel's speed and its displacement. This paper proposes such a formula for the maximum possible length of the hull damage, which has been calculated using different methods. The formula is proposed for small high speed vessels, but it is possible to use the same formula for other types of ships.

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