Investigation of sunshading elements on vertical fire spread in enclosed fire by numerical simulation

Usually interstorey flooring prevents spread of fire between the floors. If the flames reach upper floors for several reasons, flooring would not provide this quality. During a fire, façade openings have extremely significance for the spread of flames. Heat flow and density often reach upper floors and this causes the spread of fire. Spreading of fire in the vertical direction can occurs with openings (such as windows or doors) or vertical circulation spaces. Its can be summarized as two possible scenarios. The first scenario is that the flames go out through the openings on the facade. As a result, flames run upwards along the facade, which threatens neighboring buildings. The second scenario is that the flames spread rapidly between the floors through the gaps in the building. During an enclosure fire, ejected flames and smoke from windows leak out of unprotected openings in the upper floors. In this stage, flames spread along facade. Depending on the nature of the facade material, fire can spread through the upper floors quickly. This is called facade fire. The factors affecting flame spread on facade are openings, facade geometry and materials. The openings (window, door, culvert, etc.) have an effect on the behavior of the enclosure fire even in the first stage of the fire. After a flaming fire phase, the fire is oxygen dependent for grow. Even fires in small enclosures with adequate fuel tend to self-extinguish if there is not enough oxygen available for burning continuity. However, openings play an important role in controlling the rate of fire growth and the indoor temperature. Facade geometry is an other important factor for fire spread. Horizontal and vertical architectural applications can take place in facade geometry for aesthetic or comfort purposes. Overhangs, spandlers, horizontal sunshading systems are examples of horizontal architectural applications. Vertical architectural applications can be exemplified by side walls which can be caused by movement on the facade, masonry applications or vertical sunshading systems used for comfort. In addition, horizontal and vertical elements can be used for limit spread of fire. Horizontal element applications used for this purpose may be a shade or balcony that is applied to above the window. Vertical applications include non-flammable and non-cellular structure, parallel to opening applications. Achieving thermal comfort in the buildings is made easier with the developing technology. However, it should not be overlooked that the non-renewable sources of energy on the earth are rapidly decreasing day by day. For this reason, the use of sunshading systems is increasing rapidly to minimize energy consumption in buildings especially in recent years. Solar control systems are effective in adjusting daylight level and limit the amount of energy spent on the building's lighting, heating and cooling processes by limiting the annual solar achievements of the building. In addition, sunshading systems help to provide thermal and visual comfort conditions for users. In addition to all these features, the sunshading systems can determine the characteristics of ejected flame and smoke from window, as they are located above or front of the windows on the façade. For this reason, it is important to examine the effects of the sunshading systems used in energy efficient building design on flame and smoke motion. In the first chapter, scope and boundaries of the thesis is given. There was not any research about the effects of sunshading systems on flame and smoke spread during fire in the literature review. Similarly, there were not any related information about facade overhang or side wall dimensions and compositions in Turkish fire code "Binaların Yangından Korunması Hakkında Yönetmelik" (BYKHY). However, there are researchs about the effects of vertical and horizontal facade elements effects on fire and smoke spread. In this study the effects of sunshading systems on flame and smoke spread during fire are investigated with respect to different sunshading systems and different opening dimensions. In this context, the aim of this study is exhibition of different sunshading systems guiding and protection effect types and levels of upper storey openings in terms of flame and smoke spread. In the second chapter of the thesis, enclosured volume fires are mentioned in general. In this section, the development of enclosured volume fires, its effecting factors, the spread of enclosured volume fires and façades are mentioned. In addition, mathematical formulas are used to calculate possible behaviors and sizes of flames in façade fires. In the third chapter of the thesis, commonly used solar control systems are discussed. For this purpose, the solar control elements are classified in terms of figural features, used materials and mechanism. Possible effects of these systems on flame and smoke spread during fire are discussed. In the fourth chapter, numerical models that have been done in the scope of thesis are discussed. The method used in this context is explained and case studies are explained in the numerical model.Experimental and numerical modelling methods are frequently used, to investigate fire scenarios. Experimental studies have many advantages, however they are less preferred due to time and high costs. In view of they are validated CFD based softwares, numerical modelling methods which are separated from these disadvantages are widely used. For this purpose, the effects of various sunshading systems on the flame and smoke spread were investigated by numerical modeling method and the accuracy of the results was checked by mathematical calculations. The fire scenario was prepared since the glass on the floor where the fire source is broken and start of the flame and smoke exits. The case studies are enclosed volumes with an opening adjacent to the exterior. It is assumed that the generated fire scenario lasts for 1200 seconds and is an office type fire. The solid wood table is selected as the fire source and the source is positioned in the middle of the closed volume. In addition, the heat release rate (HRR) used in the fire is designed to be 1156 kW / m2 and in accordance with the standard fire curve. In the case studies developed within the scope of the scenario, the fire source floor and two upper floors are modeled. The closed volume dimensions are 3,6 x 3,6 x 3,6 m. The wall thickness is 0,2 m. In the case studies, 5 different sunshading systems are applied to 3 enclosed volumes which has same properties however different opening sizes. In order to investigate the reactions of the systems in the event of fire, reference models have been developed which do not have any sunshading system for 3 different opening sizes. A total of 18 different case studies were prepared with reference models. Within the scope of the study, wind effect and material and fire resistance features of sunshading systems are excluded. When the results of the study are examined it is shown that different width openings and different types of sunshading elements used around the openings are effective in the flame and smoke spread during the fire. Openings with same height but different width, the ventilation rate and the burning rate are also increased depending on the opening area. Accordingly, in closed volumes with equal amount of fuel, the fire lasts longer in volumes with narrow openings. For this reason, the average fire temperature expected in the closed volume during the fire is higher in the models with narrow opening than in the other models. This result is mathematically proved in addition to numerical modeling. Sunshading systems play an active role in the direction of flame and smoke during a fire. The design of the sunshading systems must take into account the fire issue, not just the solar control. With proper design and material selection, it is possible to control fire spread as well as control solar effects.