Yol tüneli yangınında duvar kaplamasının ısıl etkisinin sayısal incelenmesi

Bu çalışmada 1:100 ölçekli doğal havalandırmalı bir yol tüneli yangınında duvar kaplamasının ısıl etkisi sayısal olarak incelenmiştir. Dış yüzeyi toprak kaplı beton tünel modelinin iç yüzeyine Alüminyum, Nikel ve Kalsiyum-silikat kaplama kullanılarak üç katmanlı yapı oluşturulmuştur. Modelleme bir yol tünel içerisinde yanma sonucunda oluşan gaz çıkışına bağlı sabit ısı akısında yapılmıştır. Gazın çıkış sıcaklığı 950 K, ısı salınım oranı 50 MW ve kütlesel debisi 48.6 kg/s olarak seçilmiştir. Model tasarımı ve akış alanının çözümü hem zamana bağlı ve hem de geçici rejimde ANSYS/FLUENT programı ile yapılmış ve analizlerde standart k-ɛ türbülans modeli kullanılmıştır. Sonuçlar bir yol tüneli yangınındaki sıcaklık dağılımının beton duvarlar üzerine eklenecek üçüncü bir katmandan etkilendiğini göstermiştir. Üçüncü katman olarak Alüminyum ve Nikel tabaka kullanılan modellerde ısı transferi iki katmanlı modele göre daha fazla iken, Kalsiyum-silikat tabakası kullanılan modelde farkın çok az olduğu tespit edilmiştir.

Anahtar Kelimeler:

Yol tüneli yangını, Duvar kaplaması, Hesaplamalı akışkanlar dinamiği, Isı iletimi

Numerical investigation of the thermal effect of wall coating in road tunnel fire

In this study, the thermal effect of the wall coating in a 1:100 scale natural ventilated road tunnel fire was numerically investigated. A three-layer structure was formed by using Aluminum, Nickel and Calcium-silicate coating on the inner surface of the concrete tunnel model, the outer surface of which was covered with soil. The modeling was carried out at a constant heat flux depending on the gas output formed as a result of combustion in a road tunnel. The outlet temperature of the gas is 950 K, the heat release rate is 50 MW and the mass flow rate is 48.6 kg/s. The model design and solution of the flow field were made with the ANSYS/FLUENT program both in time dependent and transient regime, and the standard k-ɛ turbulence model was used in the analyses. The results showed that the temperature distribution in a road tunnel fire is affected by a third layer to be added over the concrete walls. In the models using Aluminum and Nickel layer as the third layer, the heat transfer was higher than the two-layer structure, while the difference was found to be very small in the model using the Calcium-silicate layer.

Keywords:

Road tunnel fire, Wall layer, Computational fluid dynamics, Heat conduction,

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