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Full-Text Articles in Engineering

Determining Kinetic Parameters Of Cellulose And Lignin Pyrolysis By Gaussian Process Regression (Gpr) Method, Pichayaporn Viriya-Amornkij, Kazunori Kuwana Dec 2022

Determining Kinetic Parameters Of Cellulose And Lignin Pyrolysis By Gaussian Process Regression (Gpr) Method, Pichayaporn Viriya-Amornkij, Kazunori Kuwana

Progress in Scale Modeling, an International Journal

The ignition and flame-spread processes in the forest and urban fires involve the pyrolysis reactions of biomass materials. One of the most common methods for estimating the fire performance of a material is the evaluation of kinetic parameters, i.e., activation energy (𝐸), pre-exponential factor (𝐴), and reaction model (𝑓(𝛼)), from thermogravimetric analysis (TG) data. Typically, 𝐸 is estimated based on an Arrhenius-type equation such as Kissinger, Kissinger-Akahira-Sunose (KAS), and Friedman equations. Then, its value is adjusted along with other parameters by assuming a reaction model, e.g., the 𝑛-order model. This study proposes a Gaussian process regression (GPR) method to determine …


Scale Modeling Of An Appearance Of Downwash Pattern Of Hot Smoke Ejected From Chimney In The Turbulent Cross Flow, Xangpheuak Inthavideth, Nobumasa Sekishita, Sounthisack Phommachanh, Yuji Nakamura Nov 2022

Scale Modeling Of An Appearance Of Downwash Pattern Of Hot Smoke Ejected From Chimney In The Turbulent Cross Flow, Xangpheuak Inthavideth, Nobumasa Sekishita, Sounthisack Phommachanh, Yuji Nakamura

Progress in Scale Modeling, an International Journal

This study aims to elucidate the scaling law to provide the critical condition on appearance of the downwash pattern of the hot smoke ejected from a chimney in a turbulent cross flow. A specially designed wind tunnel with an active turbulence generator developed by Makita was adopted to offer a quasi-isotropic turbulence field in a lab-scale test facility. A heated jet with smoke is issued into the cross flow from the vertically oriented chimney placed in the test section of the wind tunnel. In this study, the experimental parameters considered are temperature of the heated jet (smoke), jet ejected velocity, …


A Cfd-Based Scaling Analysis On Liquid And Paint Droplets Moving Through A Weak Concurrent Airflow Stream, Masoud Arabghahestani, Nelson Akafuah, Tianxiang Li, Kozo Saito Sep 2022

A Cfd-Based Scaling Analysis On Liquid And Paint Droplets Moving Through A Weak Concurrent Airflow Stream, Masoud Arabghahestani, Nelson Akafuah, Tianxiang Li, Kozo Saito

Progress in Scale Modeling, an International Journal

We conducted volume of fluids (VOF) multiphase model numerical simulations to obtain the interaction among all the major governing forces identified in our previous paper. Our numerical experiments are intended to assess the droplet generation process and the jetting behavior by providing specific input conditions, offering CFD as a tool to study scaling correlations instead of physical experiments. Water droplets that can represent waterborne paints were generated by piezo-generated sinusoidal waveforms at the inlet of the nozzle. The governing forces included the external piezo-based wave-generation force, the inertial force of droplets, the inertial force of air, the viscose force of …


A Simplified Model For The Intermediate Structure Of Strong Fire Whirls, Forman A. Williams Jun 2022

A Simplified Model For The Intermediate Structure Of Strong Fire Whirls, Forman A. Williams

Progress in Scale Modeling, an International Journal

A model is described for the overall structure of intense fire whirls, based on a spatially evolving vortex, with circulation enhancement driven by the axial acceleration of low-density gas in the core through the axial pressure gradient. The axial acceleration increases the entrainment rate into the core which, through mass conservation, increases the circulation if the angle between the tangential and radial velocity components remains fixed. The two-zone model employs general balance equations for regions inside and outside a cylinder of fixed radius, each inviscid, the inside region being presumed to have a constant density small compared with the (constant) …


Reduced-Scale Experiments And Numerical Simulations Of Informal Settlement Dwelling Fires, Vigneshwaran Narayanan, Antonio Cicicone, Ayden D. Botha, Richard Shaun Walls Jun 2022

Reduced-Scale Experiments And Numerical Simulations Of Informal Settlement Dwelling Fires, Vigneshwaran Narayanan, Antonio Cicicone, Ayden D. Botha, Richard Shaun Walls

Progress in Scale Modeling, an International Journal

Informal settlement dwellings (ISDs) house approximately one billion people in the developing world and this number is expected to double by the year 2030. Contemporary research on ISD fires has focused on understanding the fire dynamics within individual dwellings (micro-scale) and fire spread in settlements consisting of multiple dwellings (macro-scale). This paper aims to do two primary things: investigate if scaling methods that were derived for compartments with thermally thick boundaries can be applied to ISDs (compartments with thermally thin boundaries), and if they can adequately represent the most important phenomena associated with full-scale ISD fires; and demonstrate Fire Dynamics …