Study On Early Smoke Detection Of Fire Hazard And The Interference Factors In Cushioned Sleeping Berth Of Train

Spreading fast and being difficult to control and put out, train fire hazard can not only bring enormous property loss, but also threat the passengers' lives. Therefore, the fire prot -ection on train is very important.Being one of the very important factors of early fire warning, the research on smoke detection at smoldering combustion stage of train fire hazard and the interference factors can provide references for the train fire protection and the design of train AC system.According to the sleeping berth of a cushioned sleeper, the physical model and mathematical model of the smoke flowing field have been built. Based on FLUENT, the smoke flowing field has been simulated. The reliability and validity of the model have been verified by the corresponding experiment. On the basis of the verified model, a three-dimension numerical simulation is carried out to simulate and analyse the smoke concentration. The influence rule from different interference factors is studied and analysed as follows:1. The spread speed of smoke was strengthened by air supply. Under different air supply volume, the ability of smoke exhausting was different and the change rate of smoke concentration is different.2. Different smoke concentration fields at the ceiling region and outlets were archived in the sleeping berth by different smoke source positions. However, the change trends of smoke concentration at the ceiling region were similar and the concentration stays at a high level. The smoke concentration contrast between the two air outlets has a direct proportion with the contrast between the distances of outlets and smoke source position.3. The smoke concentration at the ceiling region was different when downward air supply and sideward air supply were respectively used. When sideward air supply was adopted, the smoke concentration at the ceiling region was lower than that of downward air supply, and the smoke concentration contrast of the two air outlets was smaller.4. The open/close status of the door had a significant impact on the smoke concentration at the ceiling region and outlets. When the door was open, most of the smoke was exhausted out of the sleeping berth through the door which consequently led a low smoke concentration at the ceiling region and outlets.5. The ON/OFF status of AHU played an important role in affecting the smoke concentration at the ceiling region and outlets. Compared to the OFF status, the smoke concentration of the ON status at the ceiling region was lower but higher at outlets. The AHU running can accelerate the smoke spread inside and outside the sleeping berth.