以泛用型熱流場分析軟體建構數值模式探討隧道火災流場問題屬於現代重要工程技術之一。惟數理模式仍難免包含一些假設，這些假設在模式中以參數的形式存在，其值將隨問題而異。若要正確使用此工具於輔助設計通風系統或分析相關問題，則必須正確掌握數理模式中的諸多參數。有鑑於此，本研究乃以Memorial Tunnel Fire Ventilation Test Program (MTFVTP)之全尺度火災案例實測數據為依據，探討隧道火災流場數理模式之參數效應。研究發現只要隧道環境條件完整(環境條件是指隧道出入口之大氣條件、隧道對氣流總阻力、隧道壁的熱傳狀況、風機運作狀況、火源熱釋放率等)和數理模式參數合宜(數理模式參數是指除了紊流模式中的標準參數外，尚包含風機出口氣流的紊動強度、火源紊動量產生率、火源新生物質量產生率、火源新生物溫度和紊動強度、浮力紊動係數、隧道壁外之熱傳係數等)，則數理模式對隧道火災案例的分析結果可以與實測數據高度吻合。本研究獲得之經驗與成果有助於正確使用模擬軟體於隧道通風系統的設計與分析工作。
Using a general-purpose CFD code to set up a mathematical model for analyzing tunnel fire problems is one of the important modern technologies. However, mathematical model inevitably includes assumptions that are transformed into problem-dependent parameters in the model. To employ CFD code on analysis of tunnel ventilation problems, values of the parameters in the model must be specified appropriately. In this study, the full-scale experimental data provided by Memorial Tunnel Fire Ventilation Test Program (MTFVTP)were relied on as we searched appropriate parameter values for tunnel-fire model. After study of test cases, we found that mathematical model came out with results in very good agreement with experimental ones, when the environmental conditions of the flow were well defined and the major parameters were specified appropriately. The environmental conditions include the atmospheric conditions at portals, the distribution of obstacles in the flow, the thermal condition outside the tunnel wall, the operational status of jet fans, and the fire size etc. The primary parameters include common coefficients in turbulence models, turbulence intensity at jet-fan outlets, the turbulence generation rate of the fire, the rate of mass transferred to the flow from materials burned, the temperature and turbulence intensity of these new mass added to the flow in the fire, the coefficient regarding to the generation or suppression of turbulence due to density gradient, and the heat transfer coefficient outside the tunnel wall etc. These findings may help better application of CFD technology on tunnel ventilation system design and problem analysis。
