ÖLÇEKLENDİRİLMİŞ BİR METRO İSTASYONUNDA KÜÇÜK ÖLÇEKLİ SIVI HAVUZ YANGINLARININ YANGIN TASARIM EĞRİSİ SEÇİMİ

Abstract

n-heptan havuz yangını 1:100 ölçekli bir metro istasyonunda sayısal ve deneysel olarak incelenmiştir. Fire Dynamics Simulator (FDS v6.7.5) yazılımı ile istasyonda farklı tasarım eğrileri uygulanarak duman ve sıcaklık dağılımı araştırılmıştır. Sıfır piston etkisi altında 10 ml n-heptan yakıt için deneysel ve sayısal çalışmalar yapılmıştır. Performansa dayalı tasarımı geliştirmek ve yapılar için güvenilir yangın simülasyon sonuçları elde etmek için sayısal çalışmalarda güvenilir girdiler tanımlamak gerekmektedir. Çalışmanın amacı, küçük ölçekli hidrokarbon havuz yangınları için en uygun yangın tasarım eğrisini seçmek ve sayısal çalışmayı deneysel sonuçlardan bağımsız hale getirmektir. Bu çalışmada, t2, tanh, Eurocode 1 (BS EN 1991-1-2), eksponansiyel ve ikinci dereceden yangın eğrileri incelenmiş ve deneysel sonuçlarla doğrulanmıştır. FDS kullanılarak elde edilen sayısal sonuçlar deneysel verilerle doğrulanmış ve ikinci dereceden hariç tüm yangın tasarım eğrileri ile uyumlu olduğu gözlenmiştir. Yangın süresi boyunca büyüme, tam gelişme ve bozunma aşamalarını içeren eksponansiyel yangın tasarımı eğrisinin deneysel verilere daha yakın sonuçlar verdiği gözlemlenmiştir. Deneysel sonuçlardan bağımsız olarak, eksponansiyel yangın tasarım eğrisi kullanılarak yapılan sayısal çalışmadan elde edilen sıcaklık dağılım sonuçları ile literatürden elde edilen radyasyon/türbülans parametrelerinin deneysel sonuçlarla ortalama %5 farklılık gösterdiği görülmüştür. Ayrıca t2 ve tanh yangın tasarım eğrilerinin de deneysel sonuçlarla %6.92 ve %9.02 gibi kabul edilebilir farklılıklar gösterdiği, Eurocode HC’nin ise %12.17’lik fark ile daha uzak olduğu gözlenmiştir. Bu nedenle küçük ölçekli hidrokarbon havuz yangınlarında eksponansiyel tasarım eğrisi kullanılarak yangın tasarımının yapılabileceği söylenebilir.

Keywords

• Yangın gelişimi
• Yangın tasarım eğrisi
• Havuz yangını
• N-heptan
• Fire dynamics simulator (FDS)

DESIGN FIRE CURVE SELECTION OF SMALL SCALE POOL FIRES IN A SCALED METRO STATION

Abstract

n-heptane pool fire was numerically and experimentally investigated in a 1:100 scaled metro station. Fire Dynamics Simulator (FDS v6.7.5) has been applied to investigate smoke and temperature distribution by implementing different design curves in the station. Experimental and numerical studies were performed for 10 ml n-heptane fuel under zero piston effect. To develop performance-based design and to obtain reliable fire simulation results for structures, reasonable input conditions are essential for numerical studies. The aim of the study is to select most suitable fire design curve and make the numerical study independent of the experimental results for small scale hydrocarbon pool fires. In this study, t2, tanh, Eurocode 1 (BS EN 1991-1-2), exponential, and quadratic fire curves were investigated and validated with experimental results. The numerical results obtained using FDS were validated with experimental data and good agreement was observed for all design fire curves except quadratic one. It was observed that the exponential design fire curve predicted more similarly to the experimental data over the fire duration including growth, fully developed and decay phases. Regardless of the experimental results, it was seen that the temperature distribution results obtained from the numerical study using exponential fire design curve and the radiation / turbulence parameters obtained from the literature were found to have an average of 5% difference with the experimental results. It was also seen that the t2 and tanh curves have acceptable differences of 6.92% and 9.02%, respectively, and the Eurocode HC is less suitable than the other curves with a difference of 12.17%. Therefore, it can be said that in small scale hydrocarbon pool fires, fire design can be done using exponential design curve.

Keywords

• Fire development
• Design fire curve
• Pool fire
• N-heptane
• Fire dynamics simulator (FDS)

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