scholarly journals Effect of Prefilmer Edge Thickness on Breakup Phenomena of Liquid Film in Prefilming Airblast Atomizer

2017 ◽  
Author(s):  
Takahiro Okabe ◽  
Naoki Katagata ◽  
Toshihiro Sakaki ◽  
Takao Inamura ◽  
Koji Fumoto
Keyword(s):  
Liquid Film ◽  
Fourier Transformation ◽  
High Speed ◽  
Processing Technique ◽  
Image Processing Technique ◽  
Fast Fourier Transformation ◽  
Maximal Power ◽  
Breakup Length ◽  
Length Increase ◽  
Fft Analysis

This paper describes the investigation of the effect of a prefilmer edge thickness on the breakup phenomena of aliquid film in a prefilmer airblast atomizer. The breakup phenomena of the liquid film at five prefilmer edge thicknesses (160, 500, 1250, 2000, and 3000 μm) under various conditions was observed using a high-speed camera. The breakup length of the liquid film was calculated by an image processing technique developed in this study. In order to quantitatively evaluate the effect of the prefilmer edge thickness on the breakup frequency, the Fast Fourier Transformation (FFT) analysis was conducted based on the time evolution of the breakup length. The results indicated that the breakup length increase and the breakup frequency decreases by increasing prefilmer edge thickness due to a larger volume of a liquid accumulation attaching to the prefilmer edge. The FFT analysis showed that the increase in prefilmer edge thickness causes the transition of the maximal power spectrum to a lower frequency (i.e. less than 100 Hz) due to the increase in the liquid accumulation at the edge as well. Finally, adimensionless correlation has been proposed for the breakup length of a liquid film.DOI: http://dx.doi.org/10.4995/ILASS2017.2017.4931 

Computational Estimation of Bubble Gas Velocity for Slug Flow Pattern in Horizontal Pipes Using Image Processing Technique

2012 ◽  
Author(s):  
María T. Valecillos ◽  
Carlos H. Romero ◽  
María A. Márquez ◽  
Sissi D. Vergara
Keyword(s):  
Image Processing ◽  
Flow Pattern ◽  
Slug Flow ◽  
High Speed ◽  
Processing Technique ◽  
Image Processing Technique ◽  
Gas Velocity ◽  
Two Phase ◽  
Horizontal Pipes ◽  
Computational Estimation

Two-phase slug flow pattern is one of the most common flow patterns present in many industries, therefore its study becomes relevant. The aim of this work was to develop an automated computational program to determine the bubble gas velocity associated to gas-liquid two-phase slug flow by using video digital image processing technique. In order to obtain the images for the analysis, experiments were carried out using a pipe bench for air-water two-phase flow. The experimental facility is located in Simon Bolivar University, in Venezuela. The system has three pipes with different internal diameters and can be rotated around its axis and fixed at any inclination angle from horizontal to vertical flow. The tests were run in a horizontal pipeline of 0.03175m of internal pipe diameter and 8m long. For slug flow visualization a high speed camera Kodak Ektapro 4540mx imager was used. The camera was located in an x/D relation corresponding to 249 from the pipe inlet, ensuring the complete development of the flow. The camera allowed a maximum acquisition velocity of 4500 frames per second. The superficial velocity range was 0.16–1.79m/s and 0.16–1.26m/s for air and water, respectively. To summarize, 165 tests were performed and 1320000 images were analyzed with 20 flow rate combinations. The computational application was validated by comparing it with the velocities measured manually over selected images. Results obtained were compared to several correlations such as Bendiksen [1], Cook & Behnia [2] and Wang et al. [3].

Determination of Two-Phase Flow Void Fraction of R600a in a Horizontal Smooth Tube

2012 ◽  
Author(s):  
Özden Ağra ◽  
Hakan Demir ◽  
Ş. Özgür Atayılmaz ◽  
Ahmet Yurtseven ◽  
A. Selim Dalkılıç ◽  
...  
Keyword(s):  
Neural Network ◽  
Void Fraction ◽  
High Speed ◽  
Saturation Temperature ◽  
Horizontal Tube ◽  
Processing Technique ◽  
Image Processing Technique ◽  
Two Phase ◽  
Void Fractions

In this paper, the void fraction of alternative refrigerant R600a flowing inside horizontal tube is determined by means of an experimental technique, well known correlations in the literature and a generalized neural network analysis. The horizontal tube is made from smooth glass tubing of 4 mm inner diameter. The test runs are done at average saturated condensing temperatures between 30 and 40 °C while the average qualities and the mass fluxes are between 0.45–0.91 and 68.5–138.1 kg m-2s-1 respectively. The flow regime determination inside the tube is performed by means of sight glasses placed at the inlet and outlet sections of the test section, used for in-tube condensation tests, virtually. An image processing technique, performed by means of a high speed camera, is used to determine the void fractions of stratified and annular condensing flow of R600a experimentally. The void fractions are determined using relevant measured data together with 11 different void fraction models and correlations reported in the open literature analytically. Artificial neural network (ANN) analysis is developed to determine the void fractions numerically. For this aim, mass flow rate, average vapor quality, saturation temperature, liquid and vapor densities, liquid and vapor dynamic viscosities and surface tension are selected as the input parameters, while the void fraction is selected as the output. Three-layer network is used for predicting the void fraction. The number of the neurons in the hidden layer was determined by a trial and error process evaluating the performance of the network and standard sensitivity analysis. The measured void fraction values are found to be in good agreement with those from ANN analysis and correlations in the literature. It is also seen that the trained network are more predictive on the determination of void fraction than most of the investigated correlations.

611 Can Fast Fourier Transformation (FFT) analysis of graft flow predict 1 year graft failure after CABG?

2011 ◽  
Vol 27 (5) ◽  
pp. S284 ◽  
Author(s):  
D. Une ◽  
G. Chikazawa ◽  
R. Karkhanis ◽  
J. Vincent ◽  
J. Sever ◽  
...  
Keyword(s):  
Fourier Transformation ◽  
Graft Failure ◽  
Fast Fourier Transformation ◽  
Graft Flow ◽  
Fft Analysis

Research on Length Measurement of Workpiece Based on Digital Image Processing Technique

2013 ◽  
Vol 655-657 ◽  
pp. 859-867
Author(s):  
Bin Luo ◽  
Wei Liu ◽  
Yun Luo
Keyword(s):  
Image Processing ◽  
Digital Image Processing ◽  
Digital Image ◽  
High Speed ◽  
Vision System ◽  
Measuring Method ◽  
Processing Technique ◽  
Image Processing Technique ◽  
Measuring Accuracy ◽  
Machine Speed

Aiming at the problems such as slow speed and low measuring accuracy existing in measuring length precision of pin parts in mass production, a new approach of high speed and precise measurement is proposed based on the research of the length measuring methods such as parallel laser length measuring method and area array CCD measuring method, etc. Application of (machine vision system and computer measurement & control technology) digital image processing technology can perform automatic high speed measurement and separation of workpiece effectively and accurately. The experimental results show that the machine speed could reach 4-5 pieces/second, with length measuring accuracy of around 10 microns, indicating that the approach proposed in this paper has important practical value.

scholarly journals Fire Detection Using Multi Criteria Image Processing Technique in Video Sequences

2015 ◽  
Vol 16 (1) ◽  
pp. 136
Author(s):  
Behrouz Memarzadeh ◽  
Mohammad Ali Mohammadi
Keyword(s):  
High Speed ◽  
Fire Detection ◽  
Detection Algorithm ◽  
Processing Technique ◽  
Video Data ◽  
Image Processing Technique ◽  
Video Sequences ◽  
False Alarms ◽  
Surveillance Systems ◽  
Gray Level

Vision-based flame detection has drawn significant attention in the past decade with camera surveillance systems becoming ubiquitous. This paper proposes a multi criterion method to detect fire or flames by processing the video data generated by a high speed camera. Since flame images are special class of images, some of the unique features of a flame may be used to identify flame. There are some differences between flame images and other general images. By using these features we are able to detect fire correctly with least false alarm. In this paper we present an algorithm which can detect fire and reduce number of false alarms by counting number of identified pixels. In the algorithm, we preprocess the images to have better results. So first we adjust the gray level of a flame image according to its statistical distribution to have better processing. After that we try to extract fire features in images. First by using color characteristics, the ratio of red to green, we can identify probable fire-like or fire like pixels. Second, to highlight the regions with high gray level contrast at their edges, we use the extended prewitt filter. We use AND operation on two above processing images to remove unrelated pixels, at last by using flicker frequency, the oscillating change in the number of identified pixels over time is transformed into the frequency domain to complete detection algorithm. Simulation proves the algorithm ability to detect fire in different situations in video sequences.

scholarly journals An Effective Model to Alert a Drowsy Driver using Eye Closure Rate

2020 ◽  
Vol 9 (5) ◽  
pp. 2409-2412
Keyword(s):  
Network Architecture ◽  
High Speed ◽  
Processing Technique ◽  
Image Processing Technique ◽  
Road Accidents ◽  
Prevention Measures ◽  
Drowsy Driving ◽  
Closure Rate ◽  
The Road ◽  
Eye Closure

Transportation plays a major role in today’s world. To move from one place to another place (long distances) which cannot be covered by walk, we use vehicles which consumes less time to reach destination. According to statistics, by 2050 the urban population will increase by 68% which leads to an increase in transportation that causes pollution and increase in the rate of road accidents. There are many methods and prevention measures to control pollution. The road accidents are caused due to distracted driving, high speed, drowsy driving and disobeying traffic rules. Among these, drowsy driving has been a cause for 20% of road accidents which is because of fatigue driving. In this article, a model is proposed based on image processing technique which is segmentation and a deep convolutional neural network architecture to improve the performance of the model when compared to the existing models. The proposed model works with better performance in different lighting conditions.

Hydrodynamic Cavitation Downstream a Micropillar Entrained Inside a Microchannel—A Parametric Study

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Arash Nayebzadeh ◽  
Hanieh Tabkhi ◽  
Yoav Peles
Keyword(s):  
Vortex Shedding ◽  
Fourier Transformation ◽  
Cavity Length ◽  
Hydrodynamic Cavitation ◽  
Fast Fourier Transformation ◽  
Cavitation Inception ◽  
Lower Cavity ◽  
Helium Gas ◽  
Cavity Shedding ◽  
Fft Analysis

Hydrodynamic cavitation downstream a range of micropillar geometries entrenched in a microchannel were studied experimentally. Pressurized helium gas at the inlet tank and vacuum pressure at the outlet propelled distilled water through the device and trigger cavitation. The entire process from cavitation inception to the development of elongated attached cavity was recorded. Three modes of cavitation inception were observed and key parameters of cavitation processes, such as cavity length and angle of attachment, were compared among various micropillar geometries. Cavitation downstream of a triangular micropillar was found to have a distinct inception mode with relatively high cavitation inception numbers. After reaching its full elongated form, it prevailed through a larger system pressures and possessed the longest attached cavity. Cavity angle of attachments was predominantly related to the shape of the micropillar. Micropillars with sharp vertex led to lower cavity attachment angles close to the flow separation point, while circular micropillars resulted in higher angles. Twin circular micropillars have a unique cavitation pattern that was affected by vortex shedding. Fast Fourier transformation (FFT) analysis of the cavity image intensity revealed transverse cavity shedding frequencies in various geometries and provided an estimation for vortex shedding frequencies.

Design of Solid Rocket Engine

2015 ◽  
Author(s):  
Ryoichi S. Amano ◽  
Yi-Hsin Yen
Keyword(s):  
Liquid Film ◽  
High Speed ◽  
Gas Flow ◽  
Volume Fraction ◽  
Length Scale ◽  
Breakup Process ◽  
Flow Conditions ◽  
Solid Rocket Motor ◽  
Breakup Length ◽  
Solid Rocket

This paper presents both experiment and simulation of alumina molten flow in a solid rocket motor (SRM), when the propellant combusts, the aluminum is oxidized into alumina (Al2O3) which, under the right flow conditions, tends to agglomerate into molten droplets, impinge on the chamber walls, and then flow along the nozzle wall. Such agglomerates can cause erosive damage. The goal of the present study is to characterize the agglomerate flow within the nozzle section by studying the breakup process of a liquid film that flows along the wall of a straight channel while a high-speed gas moves over it. We have used an unsteady-flow Reynolds-Averaged Navier-Stokes code (URANS) to investigate the interaction of the liquid film flow with the gas flow, and analyzed the breakup process for different flow conditions. The rate of the wave breakup was characterized by introducing a breakup-length-scale for various flow conditions based on the Volume Fraction (VF) of the liquid, which is an indicator of a two-phase flow liquid breakup level. A smaller breakup-length-scale means that smaller drops have been created during the breakup process. The study covers the breakup and fluid behaviors based on different gas-liquid momentum flux ratios, different surface tension and viscosity settings, different Ohnesorge numbers (Oh), and different Weber numbers. Both water and molten aluminum flows were considered in the simulation studies. The analysis demonstrates an effective method of correlating the liquid breakup with the main flow conditions in the nozzle channel path.

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