基于CFD管道三氟甲烷灭火剂流动相态研究

Study on the pipe fluid phase of trifluoromethane(CHF_3) extinguishing agents based on CFD

为研究三氟甲烷灭火剂在管道内的相变规律,在分析和研究相关理论和试验的基础上,提出了分段研究三氟甲烷管道流动相态的思想和模型;并利用Fluent前处理软件,基于实际试验管网系统建立了基于CFD的三维几何模型。在研究模型适用性的基础上,对管道内三氟甲烷灭火剂流动相态进行了分段模拟,并对模拟结果进行分析,得到了三氟甲烷灭火剂在管道内的相态变化规律。结果表明,该模型能较为准确地模拟出管道内三氟甲烷灭火剂流动的相态及变化规律。

This paper aims at exploring the phase changing regulation of the trifluoromethane gas extinguishing agent in the pipeline.As is known,the clean gas extinguishing system has been developed as early as a new fare-extinguishing system in recent 20 years. Due to its complicated nature of the liquid movement in the pipe network,it is hard to obtain the fluid phase results in the direct manner through experiments. In order to solve this problem,we have worked out a new method and multi-section model of trifluoromethane fluid phase change based on the related theory and existing experimental data given in this topic. Furthermore,we have established a new method known as a three-dimensional geometric model by using a pro-processing software named Fluent. In order to make the model applicable enough,we have investigated a multi-section simulation model and summarized the simulation results in a highly detailed manner. The simulation results not only show the function of the fluid phase of trifluoromethane fire-extinguishing agent but also include the basic characteristics of its changing regulations in the pipeline work. For example,when the agents flow both under the gas and liquid phases in the pipes,they tend to experience the gasification process. From the container valve to the ninety degree elbow,they are mainly existing in the liquid phase（ the ratio of liquid phase to gas phase is 79%）. And from the said elbow to Tee valve,they may go on with their flowing movement in double-state coexisting form till its end. From the Tee valve to the discharging nozzle,they are mainly existing under the gas phase（ the ratio of gas phase to liquid phase is 80%）. Thus,it is necessary for us to turn to the computational fluid dynamics to describe accurately and simulate intuitively the physical phenomena of the gas-fluid movement,which makes it difficult to evaluate our method and high cost of the experiments concerned. However,the slightly difference of pressure drop-down between the simulation results and experiment data shows that the simulation results are reliable,which helps to make our method and model a valuable theoretical reference and decision support for further applications of the trifluoromethane fire-extinguishing system.