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| Dry powder spraying experiment of gas-solid ejector and size of nozzle-throat distance |
| XIANG Qingjiang, DU Chunwei*, ZHANG Gonghe, WANG Xikun |
| National Research Center of Pumps, Jiangsu University, Zhenjiang, Jiangsu 212013, China |
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Abstract In order to study the characteristics of gas-solid ejectors when it is applied to dry powder fire extinguishing systems, the dry powder spraying experiment of gas-solid ejector was carried out on the small model dry powder spraying test bench and using the discrete phase DPM model to track dry power particle trajectory. The influence of three nozzle-throat distances of the ejector on the spraying performance was mainly analyzed. The results show that under the case of the average particle size d50=24.3 μm and the supply amount of 2 kg/min of the dry powder, the distribution uniformity of dry powder on the ground is mainly affected by the working pressure of the supply gas. With the increase of the gas working pressure, the distribution of dry powder is more concentrated. The change of the nozzle-throat distance has an obvious influence on the distribution characteristic curves of dry powder on the central axis, and the highest distribution curve is under the appropriate nozzle-throat distance. The numerical simulation results show that there are backflow zones in the inhalation chamber of the ejector. The residence time of dry powder particles in the inhalation chamber is affected by the nozzle-throat. According to the tracked particle size, dry powder tends to be deposited at the lower end of the nozzle with a short nozzle-throat distance. The conclusions provide a reference for the application of gas-solid ejectors in fire extinguishing.
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Received: 07 March 2022
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