Experimental Investigation of the Velocity Field in Buoyant Diffusion Flames Using PIV and TPIV Algorithm

We investigated a simultaneous temporally and spatially resolved 2-D velocity field above a burning circular pan of alcohol using particle image velocimetry (PIV). The results obtained from PIV were used to assess a thermal particle image velocimetry (TPIV) algorithm previously developed to approximate the velocity field using the temperature field, simultaneously captured by an infrared (IR) thermal camera. By tracing “thermal particles,” which were assumed to be virtual particles that corresponded to pixels of temperature values in successive IR images, the TPIV algorithm estimated a larger scale instantaneous velocity field than either a single-point velocity measurement (e.g., LDV) or the area velocity measurement such as PIV. Instantaneous velocity fields obtained from both methods are presented. Time series vertical velocity profiles and time-averaged velocity vector fields are compared. The comparison demonstrates the applicability and performance of the TPIV algorithm in wildfire research

Fire Behavior of Some Southern California Live Chaparral Fuels

Wildfire spread in living vegetation, such as chaparral in southern California, often causes significant damage to infrastructure and ecosystems. In order to study wildfire spread in living vegetation, four of the most common chaparral in southern California, chamise, manzanita, scrub oak and ceanothus, were burned and compared. The observed fire behavior included mass loss rate, flame height, temperature structure and velocity field above the burning fuel bed. It was observed that flame height increases mainly with heat release rate. By using successive images of the temperature field, a recently developed thermal particle image velocity (TPIV) algorithm was applied to estimate flow velocities in the vicinity of the flame. The results are generally in agreement with other experimental results obtained on gas and liquid fuels

IR-Based Estimation of Velocities Above Flames Spreading over Different Fuels

Wildfire spread in living vegetation such as chaparral in California and eucalyptus forests in Australia often causes significant damage to infrastructure and ecosystems. A physically based empirical model to predict fire spread rate is used in the United States to assist in a variety of fire management operations. The spread model does not adequately describe the chemical processes of combustion in live fuels. Prior to describing and modeling the chemical processes of combustion in wildland fuels using computational fluid dynamics, we are investigating a technique to non-intrusively measure flame gas velocities using thermal imagery. By tracing hot pixels through successive digital images, we estimate velocity field using gradient-based algorithms. We also explore techniques established in digital particle image velocimetry (DPIV) to estimate fluid velocities. The images are acquired by a thermal camera with uncooled microbolometer 320x240 pixel focal plane array in the 7.5 - 13 um spectral range. We estimated fluid velocities in flames spreading above isopropyl alcohol and shredded aspen wood (excelsior). Results from excelsior fires are presented. Finally, results obtained from computational modeling were used to validate the velocity field estimated from the gradient-based algorithm. Preliminary results using a DPIV-based algorithm appear promising

Numerical Simulation of Live Chaparral Fire Behavior Using FIRETEC

Fire spread through chaparral fuels is a significant feature of wildland fire in southern California. In order to study the detailed physical processes involved during fire spread, FIRETEC, a coupled atmosphere/wildfire behavior model was refined to examine chaparral fire behavior. FIRETEC combines a sophisticated fine-scale model to simulate a three- dimensional wildfire, moving over a terrain-following finite volume grid, with the motions of the local atmosphere. It accounts for the microscopic details of a fire with macroscopic resolution by dividing quantities into mean and fluctuating parts and the resulting transport equations are solved by using a finite difference method. In this paper, fire spread through live chaparral fuels under different burning conditions was studied. Specifically, the effect of varying environmental variables and physical characteristics of fuels on fire spread was examined. Results from four simulations are presented. They demonstrate the effects of wind speed in enhancing heat transfer from the fire to unignited fuel ahead of the fire front. Increased fuel loading and packing ratio resulted in decreased rate of spread; while increased fuel moisture reduced the predicted rate of spread, consisted with our laboratory scale experiments

Multicomponent Domino Synthesis, Anticancer Activity and Molecular Modeling Simulation of Complex Dispirooxindolopyrrolidines

A series of spirooxindolopyrrolidine fused N -styrylpiperidone heterocyclic hybrids has been synthesized in excellent yield via a domino multicomponent protocol that involves one-pot three component 1,3-dipolar cycloaddition and concomitant enamine reactions performed in an inexpensive ionic liquid, namely 1-butyl-3-methylimidazolium bromide ([bmim]Br). Compounds thus synthesized were evaluated for their cytotoxicity against U-937 tumor cells. Interestingly; compounds 5i and 5m exhibited a better cytotoxicity than the anticancer drug bleomycin. In ddition; the effect of the synthesized compounds on the nuclear morphology of U937 FaDu cells revealed that treatment with compounds 5a–m led to their apoptotic cell death

Effect of hydrogen addition on criteria and greenhouse gas emissions for a marine diesel engine

Hydrogen remains an attractive alternative fuel to petroleum and a number of investigators claim that adding hydrogen to the air intake manifold of a diesel engine will reduce criteria emissions and diesel fuel consumption. Such claims are appealing when trying to simultaneously reduce petroleum consumption, greenhouse gases and criteria pollutants. The goal of this research was to measure the change in criteria emissions (CO, NOx, and PM 2.5) and greenhouse gases such as carbon dioxide (CO2), using standard test methods for a wide range of hydrogen addition rates. A two-stroke Detroit Diesel Corporation 12V-71TI marine diesel engine was mounted on an engine dynamometer and tested at three out of the four loads specified in the ISO 8178-4 E3 emission test cycle and at idle. The engine operated on CARB ultra-low sulfur #2 diesel with hydrogen added at flow rates of 0, 22 and 220 SLPM. As compared with the base case without hydrogen, measurements showed that hydrogen injection at 22 and 220 SLPM had negligible influence on the overall carbon dioxide specific emission, EFCO2. However, in examining data at each load the data revealed that at idle EFCO2 was reduced by 21% at 22 SLPM (6.9% of the added fuel energy was from hydrogen) and 37.3% at 220 SLPM (103.1% of the added fuel energy was from hydrogen). At all other loads, the influence of added hydrogen was insignificant. Specific emissions for nitrogen oxides, EFNOx, and fine particulate matters, EFPM 2.5, showed a trade-off relationship at idle. At idle, EFNO x was reduced by 28% and 41% with increasing hydrogen flow rates, whilst EFPM2.5 increased by 41% and 86% respectively. For other engine loads, EFNOx and EFPM2.5 did not change significantly with varying hydrogen flow rates. One of the main reasons for the greater impact of hydrogen at idle is that the contribution of hydrogen to the total fuel energy is much higher at idle as compared to the other loads. The final examination in this paper was the system energy balance when hydrogen is produced by an on-board electrolysis unit. An analysis at 75% engine load showed that hydrogen production increased the overall equivalent fuel consumption by 2.6% at 22 SLPM and 17.7% at 220 SLPM. © 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved

Finite-rate chemistry and transient effects in direct numerical simulations of turbulent nonpremixed flames

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International Conference on Signal Processing, Embedded System and Communication Technologies and their applications for Sustainable and Renewable Energy (ICSECSRE '14) Novel Bi-Orthogonal Filter Coefficient Wavelet Transform for Image Compression

ABSTRACT: This thesis implements the TDM method and presents performance results for orthogonal and biorthogonal wavelets using both periodic and symmetric extension techniques . Our results for symmetric extension indicate a slight performance advantage for biorthogonal wavelets (particularly for low frequency images); this advantage is significantly smaller than recently published results. Our analysis also demonstrates the importance of linear phase filters on image compression performance INTRODUCTION The discrete wavelet transform (DWT) has been applied extensively to digital image processing, especially transform coding of digital images and digital image sequences. Since images are mostly smooth (except for occasional edges), it seems appropriate that the wavelets should be reasonably smooth, which requires the associated filters to be long enough to obtain smoothness and energy compaction capability. However this will increase the computational cost of the corresponding transformation. On the other hand, it is desirable that the finite impulse response (FIR) filter bank (FB) be linear phase (corresponding to symmetry for wavelets and scaling functions). Unfortunately, it has been shown that orthogonality and symmetry are conflict properties for design of compactly supported nontrivial wavelets