Avlulu binalarda doğal havalandırma ve soğutma açısından rüzgar etkisi ile oluşacak hava akımlarına yüzey açıklıklarının etkisinin deneysel incelenmesi
A Wind tunnel investigation of the effects of the surface's apertures on wind velocity and air-flow in the courtyards from the point of view of the natural ventilation and passive cooling
Yazar: ENES YAŞA
Danışman: PROF. DR. VİLDAN OK
İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü / Mimarlık Ana Bilim Dalı / Çevre Kontrolü ve Yapı Teknoloji Bilim Dalı
Derece: Yüksek Lisans, 2004
Konu: Mimarlık = Architecture

Özet:
Rüzgâr, yerleşme ve bina tasarımında eski çağlardan beri önemli bir çevresel faktör olmuştur. Rüzgârın, yapıların soğutma yüküne etkisi, bu etkilerin bilimsel yöntemlerle ortaya konması, tasarım ve uygulama alanlarına zaman geçirilmeden yansıtılması enerji tasarrufunun her zamankinden daha fazla gereksinim duyulan günümüzde, çok büyük önem taşımaktadır. Bu bağlamda, avlulu binalarda rüzgâr etkisi ile oluşacak hava hareketinin etkinliğini değiştirebilecek binaya ait diğer açıklıkların da göz önünde bulundurulması, dikkatlice incelenmesi gerekmektedir. Bu gerekçe ile çalışmada yapılacak olan, rüzgârın, atrium ve avlulu yapılar üzerinde soğutma yüküne etkisi ve bu yapıların yüzeylerindeki açıklıklarda oluşacak hava akımlarının önceden tahminin yapılmasını sağlayacak bilgilerin üretilmesi amacına yönelik olarak öncelikle deneysel yolların geliştirilip araştırılmasıdır. Bu nedenle yapılacak çalışmanın amacı, rüzgâr tünelinde gerekli koşullar sağlanarak binaların soğutulması için harcanan enerjinin en aza indirgenmesi için avlu ve atrium yapılanılın yüzeylerindeki açıklıklarından geçen hava akımının deneysel olarak incelenmesidir. Çalışmanın birinci aşaması; bilgi toplama, mevcut örneklerin irdelenmesi, mevcut tünelin değerlendirilip gerekli değişikliklerin tasarlanması; îkinci aşaması; gerekli deney düzeneklerinin kurulması, tünelin karakteristiklerinin ortaya konulması; Üçüncü aşama; örnek olarak seçilmiş avlu modelleri üzerinde ölçümlerin yapılması, sonuçların değerlendirilmesi, teknik raporun hazırlanması adamlarından oluşmaktadır.

Abstract:
Wind is one of the important environmental factor in design of buildings and settlements. It becomes the main theme of the societies especially temperature of the comfort in the hot-dry climates zones. Owing to the technological development in recent years, performance research can be done with quantitative and experimental workings preparing artificial environment in advance. Today, its important that the influence of the wind on the cooling effect of the buildings and to bring this effects with scientific method. In context the surface of the courtyard's apertures might effect the wind velocity and air flow in the courtyards and it should be consider and attentively investigate. The aim of the study is researching the cooling effect on the courtyards and atrium by the wind. At first we have to envisage the air flow which occurs on the surface of the courtyards; when we have obtained Ibis envisage we have to research and develop the experimental data. The wind, indispensable element of architectural aerodinamics, has been explained in the first chapter of this research and different effects of the wind in various regions have been noted. Generally, the air movement, from high pressure area to low pressure area, is called the wind. The wind is one of the most important parameters which effects the occurence of the air movements on the earth and it effects differently in various regions because of geomorphological structure. For this reason, the effects of the emptiness ratios on velocity distributions have been examined by considering buildings, plants, topographical properties which hindered the wind. To examine the effects of the emptiness ratios on velocity distributions, firstly natural ventilation should be examined. Therefore, in the second chapter, the structure of the wind and wind types has been explained. The development of the xxvarchitectural aerodinamics and courtyards in different cultures has been explained by giving some examples, in third chapter. Air measurement tools which is used to obtain numerical results, explained in the further part of this chapter. After working principle of the anemometers, which is helped us to measure the velocity of the wind, was examined; some definitions has been done about the wind tunnel types Mankind has researched the wind and its effects until these days, and developed new techniques to constitute environment which is suitable for physical comfort conditions. Anemometers and wind tunnels are used being examined the air movements. The tools which are used to measure the velocity of the wind are called as " Anemometer". The wind tunnel tests are done to develop the design of the buildings to examine the effects of the air movements which is around the building models. " What kind of effects do air movements in ground surface of the buildings create in artificial environment? " or " How do soot atoms flying from chimney move around the buildings?" The answer of the questions like these, can be learned owing to the experimental workings doing in tunnels. The design of the buildings are done by examining the results of these experimental workings. Criterions which is used to compare the measurement results obtained from experimental workings doing in the wind tunnels are examined in three groups; Similarity, "Section - Model Connection and doing Atmospherical Border Layer. Working to supply the harmony between the model which is used in the experimental working and the actual building is called as the "Similarity ". But, it is impossible to supply the similarity perfectly. Because, material used for the model, shows differences in the physical and Chemical properties, density and its composition. Especially, supplying the similarity in workings of the high coated buildings, bridges, transmitter antenna towers effects performance of the design, too much. When doing model in the wind tunnels, there are some rules to be attended. Surface roughness of the inside of the tunnel, effects the current model directly. So, xxvinot to create different dinamic effects, the empty measurement must be done before doing actual measurement. After the model was inserted in the tunnel, current model supplying as uniform may breakdown because of the change of the pressure distribution in the tunnel. Especially, if the ceiling of the tunnel is not suitable for the experiment, there will additional pressures on the model in the observation room. This will effect the results of the observation and cause the deviation on the current speed. If one of the apperance techniques is applied, there will be different deviations in the current traces. The deviations must be maximum % 5 in the tunnel observations. If deviations is greater than % 5, new arrengements in the tunnel must be done. The atmospherical boundary layer is the last criteria which is used to compare the results of the experiment obtaining in wind tunnels. In the experiments done for the building designs, which has the scale between 1/200 and 1/1000, the boundary layer may be applied. This expression can be defined by Reynolds number which is the most important criteria in the tunnel observations. Current apperance techniques except the wind tunnels have been developed to understand the experiment results visually. The change in the wind speed and current types in the observation room may be established by the help of these techniques. These techniques are examined in four groups as Smoke tecnique, Sand technique, Liquid technique and Computer supported apperance techniques. The importance of the smoke tecnique is, not to change the prob temperature because of the cold smoke when hot wire anemometer is used. This helps to supply the measurement value much more healthy. It must be take into consideration to control the current apperance time by extending the smoke exit time. Sand technique is not a practical method to be used in the wind tunnel, it is impossible to use this technique in many laboratories. Because, special precautions must be taken not to effect human health and the calibration of the tools that are used. Liquid technique is used to view the currents that are in the horizantal plane. This system helps to view the current apperance by using liquid mixture which xxvndepends on chemical spoilt time. Chemical properties of used liquids, effects the formation time of the cunrent lines and the view time of the current lines. Generally, the mixture of chemical materials of yellow pigment and kerosene with white alcohol is used in the experiments. The developing technology, helped us to speed up the workings about the computer supported apperance. Software producers, first studied about 2D drawings and then progressed 3D drawings. Among the devoloping technology, the studies about the computerized visuality, became faster. At the beginning soft - ware produces, basicly studied on two dimensional drawing programs, but today they were able to produce programs which could give three dimensional visuality in two dimensional drawings, the measured values recorded in the computer or they measured by the help of visuality program. In this method, the calculation made by excepting the velocity values on the tie point were constant. The occurring vectoral lines, decreased the inverse ratio of the air velocity and then visuality could be made according to the boundary of velocity. These measurements could be revaluated for some instant. Especially, recognizing the three dimensional visuality which are made by computurized equipments that are supported by laser optic systems give very effective results. As well as technological development the studies on wind tunnel can warn the engineers and architects the missing points about the projects so they could get much more correct results. The results of the wind tunnel experiments, could be idendified by mathematical and statistical methods. And so the physical and statistical behaves of the wind could be explained as turbulance, heaviness and velocity spills. With same reasons the momentarily changes in the velocity, efficiency and the direction of the wind is called as turbulance. These momentarily changes could be seen as surface roughness and vertical unstability. As a function of the surface visuality, the heaviness is occured as topografic speciality and it is a general name which identifies the turbulance. xxvniFor this reason, the aim of the study is to develop the experimental method in order to minimizing the use of the energy for cooling of the buildings and to investigate the air-flow which consists of the surface in the courtyards and atrium buildings. The stages of these works are planned as follows; Stage 1: To examine the existing literature and facilities, to modify the existing wind tunnel, to set up the enstrumentation Stage 2: To carry out the experiments using some special models. Stage 3: Measurements for the sample buildings and settlement models, comparison of the results with the previous studies performed in other countries, to evaluate the results and to prepare the technical reports.