Real-Time Measurment of the Neutral Plane and Strategy of Smoke Control System in Compartment Fires by Schlieren Photography

[[abstract]]中性面是在室內火災流出高溫氣流和流入新鮮空氣之間的接觸面。在火災的發展階段時，中性面的位置是非常重要。尤其對排煙系統設計和有效性。本研究利用紋影法作為量測中性面高度變化的方式。由於光線通過不同密度的流體會產生折射現象，可以將氣流的流動現象可視化。本研究以模型實驗進行測試，在模型內以蠟燭燃燒。依據比例縮小。實驗過程以FDS模擬軟體模擬實體的溫度、速度、壓力等參數，同時使用熱電偶線量測模型開口的溫度。利用色彩的幻燈片，可以清楚判斷流出開口的高溫氣流位置及變化情形。由研究結果證明，溫度、速度、壓力等參數呈現的中性面高度，與利用紋影法量測的高度相同。至目前為止，以紋影法判斷中性面高度的變化確實為可行的技術。[[abstract]]The neutral plane in a compartment fire is the interface between the high temperature outflow and fresh inflow airs and is related to the spread of smoke. This study presents results on measuring the height of the neutral plane with the Schlieren Photography, which is one visualization technique of fluid flow and utilizes the refraction phenomenon when light passing through different densities of air. The Schlieren Photography is highly sensitive, nonintrusive, optical, and remote. It can visualize clearly the positions and variations of high-temperature outflow air at an opening. This study conducted a scale modeling experiment by burning candles inside the model with a opening as its door. Thermocouples distributed at the opening were used to measure temperatures simultaneously. FDS simulations were performed to calculate the data of temperature, velocity, and pressure at the opening. The locations of the neutral planes in experiments and simulations matched those observed with the Schlieren Photography.[[note]]NSC102-2221-E327-039-MY