The Research Of The Dusting Pneumatic Fire Extinguisher Using On Grassland

China had been carrying on lots of grassland fire disasters, on which portable pneumatic fire extinguisher was now mostly using as an individual equipment. However the portable pneumatic fire extinguisher had lower fire putting out efficiency, and the fired area was easy to reburn after putting out. This article designed 3 kinds of new dusting extinguisher basing on the current portable pneumatic fire extinguisher, which were portable dusting fire extinguisher, hand-rotated dusting fire extinguisher, and middle-sized dusting fire extinguisher. This reseach concluded several following aspects.1. After literature reviewing and investigating, analyse the diasadvatage and deficiency of portable pneumatic fire extinguisher, summarized the simulating optimizing methods of pneumatic fire extinguisher, especially reseach on gas-solid ejector by using gas-solid two-phase model. The researching route of this article was determined.2. Designed the portable dusting fire extinguisher. Proposed 2 extinguishing agent adding methods and made comparision between them. Develop the new-type Pitot tube wind meter using to measure the wind speed and wind pressure of portable dusting fire extinguisher when working. Using CFD-DEM coupling method to build model of funnel equipped on the portable dusting fire extinguisher, and verified by actual experiment.3. Precede the optimal experiments about the portable dusting fire extinguisher. The funnel throat angle, fire extinguishing agent adding position, and the funnel length were selected as the factor, the Quadratic orthogonal rotation design was introduced by the simulation model. The max virtual pellet velocity, the average axial direction velocity of air on funnel exit and the amount of fire extinguishing agent pellets detained in the funnel when extinguisher working. All experiments were done by the computer. After variance analyzed by SAS, weighting method and response surface method were also used to optimize. It was concluded that when the throat was angle 20°, the fire extinguishing agent adding position was 140mm from the air entrance, and the length of funnel was 700mm, the efficient of ejecting pneumatic fire extinguisher was mostly improved. The virtual experiment indicated that by using the optomized funnel, the fire extinguishing agent pellets velocity on funnel exit was increased to 41.24m/s, and the number of fire extinguishing agent pellets detained in the funnel was decrease to 209. The verify test held by physical prototype indicated that the optimized parameter group could improved working effect of ejecting pneumatic fire extinguisher, featured in amplifying the outfire range, reducing possibility of reburn and shorting the outfire time.4. Basing on existing hand-rotated dusting equipement, design 2 types of new hand-rotated dusting fire extinguisher, which were vertical type and portable type. Used Fluent 12.0 to analyze the fluid geometry of the vertical type when working; determine the improving scheme, and veryfied the working efficiency by the CFD-DEM coupling method. The working porcess of portable type was also analyzed by Fluentl2.0 and veryfied by the CFD-DEM coupling method. It could be conclude that portable type was better than vertical type in aspects of extinguishing agent pellets velocity and wind speed. So we made prototype of portable hand-rotated dusting equipement, and also test was done to verify its dusting ability.5. Basing on the fire ouput equipment using on grassland developed in recent years, designed a type of middle-sized dusting fire extinguisher. The engine was directively connected to the combustion blower by the driving system, and extinguishing agent was continually fed into combustion blower when it working. By increase the power of engine and enlarge the size parameter of combustion blower, the fire putting out distance and efficiency were both increased. This equipment was vehicular and easy to operate, included engin system, combustion blower system, driving system, extinguishing agent adding system, and funnel operating system. The effects of funnel length and throat angle were estimated by the CFD-DEM coupling method. When making the prototype, The Dongfanghong YTR4108G54 produced by Yituo China was adopted as the engine,9-26-63 combustion blower produced by Gaobeidian central factory, Hebei Province was adopted as executive unit. Prototype was also been tested by fire putting out experiment. The effects of lengthening funnel and converging funnel were estimated by the CFD-DEM coupling method. It could be concluded that the lengthening funnel could increase the jet velocity of fire extinguishing agent pellets, and the converging funnel could increase both the jet velocity of fire extinguishing agent pellets and the air speed on funnel exit.