【摘要】 为了研究超细微粒灭火剂的粒径与全淹没状态的关系,采用离散相模型和喷射速率模型对灭火剂颗粒的释放和流动过程进行数值模拟。分析粒径为1~12μm的超细微粒灭火剂在障碍物下的运动特点,并引入参考值R(t)和评估值A来定量评估1~12μm超细微粒灭火剂的运动特性。结果表明,1μm和4μm超细微粒灭火剂的运动特性相当,2μm超细微粒灭火剂的运动特性远好于其他级别微粒。粒径为6~8μm的超细微粒灭火剂的运动特性差别不大。粒径为2~6μm和8~12μm的灭火剂颗粒直径越小运动特性越好。综合评价得出2μm的灭火剂颗粒达到全淹没状态效果最好。更多还原

【Abstract】 The purpose of this study is to present the results of our numerical simulation of injection and movementof the fine particles in hoping to quantify the maximum stamping capability of the superfine fire powder(SFFEP), commonly used to put off the confined room fire. For this purpose, we have conducted a numerical simulation of injectionwith the particle movements conducted by using a discrete phase model and the injection velocity model. And, simultaneously,we have simulated the movement process of the SFFEP through astochastic tracking model of the discrete phase while considering the impact of the turbulence on the particles’ movement manner and the non-spherical drag. At the same time, it is necessary to include the Saffman lift force and shear stress into account. Since the particles tend tomove unsteady,itis necessary to take the nonlinearprocess of injection into account. In addition,we have chosen the UDF(UserDefined Function) to represent the nonlinear time-varying releasing rate.In implementing our testing of the flowing velocity of the SFFEP in a space range from 1μm to 12μm, we have managed to stablish two-dimensional 3.5 m× 4 m(height× width)roomwith a release device of SFFEP hanging on the top of the centre in the middle,with two barriers set along the moving path of the SFFEP, in comparison with the traditional dry chemical of 40μm.Furthermore,we have also introduced the reference value R(t)and the assessment value A for evaluating the flowing ability of 1-12μm SFFEP. The evaluation results indicate that smaller size particles of SPEAtend to demonstrate better gas characteristic behaviors with 1μm being a special case.Whereas the flow ability of 1μm and 4μm SFFEP tend to behave similar, thatof 2μmSFFEP provesmuchmore advantageous than the particles of the other sizes.At the same time,while the flowing abilities of SFFEPwith their particle sizes ranging from 6μm to 8μm behave almost alike, those of 6μm to 2μm and 8μm to 12μm tend to show their flow abilities exponentially either in decrease or in increase.Nevertheless, the flowing ability of 2μm SFFEP proves to be the optimal. Therefore, itwould be possible to divide the micro-level SFFEP into three classes: 6-8μm is of intermediate level, 1-6μm is of gaseous level and 8- 12μm can be thought to be of quasi-gaseous level.更多还原