Field Modeling: Computational Fluid Dynamics - Research Proposal Example

Declaration I declare am aware of regulation concerning plagiarism and collusion and that the research study is my original hasn’t been presented to any other institution for the award of any credited courses of study. This paper has been awarded in partial fulfillment of degree in Acknowledgments I express my sincere gratitude to my school for allowing me to conduct the research. My sincere thanks go to my professor for his guidance and suggestions in the completion of this project. Finally, I would like to convey my special regards to my parents and all my friends who helped me in carrying out this task by giving me their unlimited support. Abstract Various researchers have attempted methods of preventing and control of fire in the buildings by understanding their behaviors. With increased population and many buildings built the theory of fire dynamics has been known to explain how fire conditions are affected by the wind direction and the height building, this led to studying all these variables by use of FDS (Fire dynamic simulator) on a compartment. These factors affect the HRR, MLR, temperature of the fire and the fire duration similarly to all types of fire from those burning slowly to those burning rapidly. In large buildings especially multi-story it is very essential to consider the fire direction and speed and wind direction to come up with the best strategy to deal with the fire .In this research FDS was used to show the effect of wind speed and ventilation on fire dynamics, it assisted in understanding the fire spread and determine the best method to contain fire and effect of smoke on the combustion process. The experiment involved the use of one and two openings in analyzing the effect of wind with variation of speed from 0, 2,4,6 and 8 m/s in single opening and 1,2 and 3 m/s in double opening. The results of the experiment have shown that the main finding that were supported by all the fire behavior parameters like heat release rate, mass loss rate, temperature recorded, temperature slices and visibility slices was that the wind had no any important effect on single opening cases but has observable effect on double opening case due to double opening facilitated movement of air in with oxygen for combustion and smoke out of the compartment. That is to say increase or decrease in wind velocity for single opening case do not have any effect on compartment fire, in the meantime, for double opening case the effect of change in wind speed is significant. CHAPTER 3: RESEARCH METHODOLOGY Introduction This chapter of the study shows the method used to achieve the dissertation hypothesis. It will focus on the on the best method to be used in the research by discussing the advantages and disadvantages of the method to be used. The methodology was chosen; the first aim is to find out the needed solutions to assist in providing solutions to the objectives of the study. It should ensure the data collection stage, and data analysis can provide results that can pass reliability test and validated by other researchers in the similar area of study. Description of the Methodology A study carried out Lönnermark (2007), by concluded that in the study of fire behavior there two major techniques to be used in predicting these include theory and practical statements. Use of practical and experiment are very useful tools as they assist to study and measure the behavior and fire process whereas theories are used to explain the fire behavior, process, and factors that affect the fire ignition process by the use of scientific formulas and calculations. In choice of any of the above methods has its advantage and disadvantage, use of practical method it is preferred if the researcher to use less labor and is willing to spend are they are expensive, use of theory method is chosen in case the researcher can spend time on the project and want the project to be cheap. In developing involve the use of analytical and numerical methods that are difficult to use due to complex calculations. Use of computerized programs and software has led to natural modeling and simulation. In this study paper, I have used Computational Fluid Dynamics (CFD) to examine my objectives. The main reason of using this research method is that it is very cheap and less time consuming. CFD method apart from being fast it is accurate and a powerful method used in the fire engineering studies to come up with correct readings. A Fire Dynamic Simulator (FDS) was used in this study also to simulate the CFD as the method can measure the gas temperature and other wide range of data in a more detailed context (Yang,2010). According to Lee, he compared the gas temperature using the FDS and came up with the graph below. Field Modeling: Computational Fluid Dynamics Similar kind of simulation programs such as CFD is very common in the engineering areas such as fire safety, mechanical and electrical engineering as well as other areas. CFD is a modeling technique that applies many numerical modes and algorithms to come up with solutions and assist in the understanding fluid movements. Many researchers prefer CFD models as they capitalize on fundamental conservation law that is very fundamental in every research this study consist of fundamental laws such as mass momentum and energy that are considered very important in studying the movement of fluid. CFD involves a three dimension and a time-dependent solution by adding calculations such as Navier-stokes equations. In this research study, I have chosen CFD as it allows for the integration of other fire related simulation programs hence have a wide code, and it includes all fluid movement and heat transfers’ scenarios (Quintiere, 1998) Fire related can be put together by using various methods and simulated using different codes that is important in sub processes such as modeling the turbulence, radiation and combustion process in the experiment. This study involves study effect of the wind speed on fire by studying the changes related to heat discharged mass lost, visibility and temperature changes as wind speed changed on a one ventilation and two ventilation will be used in the compartment. Fire Dynamics Simulator (FDS) FDS is a program that assists in solving Naiver- Stokes equations in relation to wind speed, fluid movements by allowing to visualize the results obtained. This method uses a Smoke view program that uses traditional methods such as Tracer particle to show wind movement shadowy contours in both two dimensional and three dimensional to explain the changes in the variables under study such as temperature, visibility HRR, and MLR. Smoke view with use of translucent panes shows both flows and with the use of scale statics data can be collected to be analyzed to come with conclusions (Buchanan, 2001) In this study, FDS has aimed at providing the solution to fire calamities encountered in safety and safety engineering. FDS features such as LES and hydrodynamic model has increased the accuracy of the experiment. In this multiple mashes was used in testing the data (Rehm,1978).In this study data will be collected to compare two cases of one and two opening effect of wind velocity by comparing HRR,MLR, visibility, Temperature slice and temperature behavior. Sensitivity analysis According to Borg, (2015)It explains how the parameters in the models input interact and influence the output in this study we will make small changes on the parameter to determine the probability occurrence of the situation under study to assist in understanding the fire modeling. Sensitivity analyzes assist in avoiding errors that are very common in modeling engineering and it assist in verifying the conditions under consideration by comparing the expected results and tests the variables to check the robustness of the output. Summary of objective function During the fire ignition process of fire, the HRR and MLR are affected by the fuel burnt in the experiment but all this is affected by the supply of oxygen that is determined by how the compartment used is ventilated. Ventilation, however, been associated with two theories of blowing supporting combustion or reducing combustion that all are dependent on wind speed. Changes in wind velocity have however resulted to change in temperature and the burning rate of the fuel (Thompson, 1995). On past studies on fire modeling methodology has never changed and has based on two equations that aim at utilizing the gaseous phase temperature change in thin and thick material to describe the surface radiation by use following equation: In this study a simulation of a three story building, a compartment of with one and two ventilation were designed to represent the scenarios, a timer and five devices to measure the temperature that were located separately and planned in the use of computation method to solve and come up with a solution as it is more reliable. The materials used were used were wood and concrete as extracted from the SFPE Handbook. The fire source was set to ignite a fuel material of (C=3.4, H=6.2, O=2.5). The wind velocity was varied from 0, 1, 2, 4, 6 and 8 m/sin the singlr opening experiment and the wind speed in double opening was 1, 2, and 3 m/s. During the experiment temperature, HRR, MLR and visibility were investigated, and the following results were collected on sensitivity analysis by testing the condition on cross ventilation. Regardless of small errors, the FDS results were almost similar. In conclusion, from the figure above an average temperature and time in the compartment show a relationship in that as temperature increases to the maximum and start to decrease. It also shows how the fire takes the time to burn the material as the temperature changes. From these results, it was evident that FDS was a good model as it produced similar results to what was expected. It resolved the computational grid and could be used as a predictive tool as it was noticed it was more user-friendly to be used in our model. (Babrauskas, 1991). References lee, X. Zhang, P. Williams, B. Hume, A. Heise and A. Jowsey, “Multi-story Fire Analysis for HighRise Buildings,” Edinburgh Research Archive, London , 2007. Lönnermark and H. I. Ingason, “The Effect of Cross-sectional Area and Air Velocity on the Conditions in a Tunnel during a Fire,” SP Technical Research Institute of Sweden, BORÅS, 2007. M. Hurley, SFPE Handbook of Fire Protection Engineering, USA: NFPA, 2008. D. e. a. Yang, “Comparison of FDS predictions by different combustion models with measured data for enclosure fires,” Fire Safety Journal, vol. 45, no. 5, pp. 298-313, 2010. J. G. Quintiere, Principles of fire behavior, Albany N.Y: Delmar Publishers, 1998. Buchanan, Andrew Hamilton. Structural design for fire safety. Vol. 273. New York: Wiley, 2001. Babrauskas, Vytenis. Heat release in fires. Taylor & Francis, 1990. Rehm, R. C., and K. B. McGrattan. "Baum, HR." Journal of Research of the Nat. Bar. of Standards 83 (1978): 297-308. Thompson, Peter A., and Eric W. Marchant. "A computer model for the evacuation of large building populations." Fire safety journal 24.2 (1995): 131-148. Borg, Audun, Ove Njå, and José L. Torero. "A Framework for Selecting Design Fires in Performance Based Fire Safety Engineering." Fire Technology (2015): 1-23. Read More