Research On Fire Detecting System For Vehicle Section Of Urban Rail Transit

Vehicle section of Urban Rail Transit is an important facility of the rail transit network, once fire occurred, the train scheduling would be severely influenced. It is obviously important to select the proper type of the fire detection system in the early designing stage.In this thesis, full-scale fire experiment and numerical simulation are adopted to study the fire detection system inside vehicle section. Based on that, suggestions are proposed for type selection and position arrangement of fire detectors used in vehicle section of urban rail transit.In full-scale fire experiment, influences caused by various types of fire and different positions on open-area smoke imaging detector, aspirating smoke detector,image fire detector, infrared beam smoke detector and light beam image smoke detector are analyzed.For the smoldering fire, aspirating smoke detector is more sensitive for small-scale smoke. Beam smoke detector is more sensitive for large-scale smoke which can rise directly to the location of the detector,of which, light beam image smoke detector can achieve early detection and alarm capability which is not susceptible to fire source location.Fore the polyurethanes fire, image fire detector’s response is fastest, beam smoke detector is faster than aspirating smoke detector, of which, Light beam image smoke detector is fastest; When the ignition source is located in the sidewall position, the detector response time is faster than the others.FDS numerical simulation discusses if the detector’s arrangement of height,space,optical distance and different external environment affect its response time. For the smoldering fire, the arrangement of height,space and different external environment have a great impact on the response time. Fore the polyurethanes fire, the arrangements of height and optical distance have a great impact on the response time.Accounting for the characteristics and various fire of vehicle section, We recommend a detection method which light beam image smoke detector combines image fire detector for the vehicle section, When setting up light beam image smoke detector,two staggered layer of detectors on the height which the early fire smoldering smoke can gather,spread and is 0.5～1m away from the ceiling, horizontal space isn’t more than 14m,which should be minimized as much as possible if conditions allowed.