初始温度对管道内预混火焰传播特性影响的数值模拟研究

发布时间：2018-08-16 10:14

【摘要】：目前,气体能源管道事故频发且后果严重。为了辅助安全从业人员针对不同环境温度条件,制定相应的预防及控制管道火灾事故的措施,本文利用CFD软件,研究不同条件下,初始温度对管道内预混火焰传播特性影响的规律。本文利用ANSYS Fluent建立了长方体管道几何模型,将数值模拟所得数据与前人实验所得数据进行对比。在验证模型的准确度的基础上,利用该模型研究了甲烷-空气预混气体和丙烷-空气预混气体在240K~320K的温度范围内,初始温度对于预混气体火焰传播特性的影响,然后以甲烷-空气预混气体为例,研究在不同体积分数和不同初始压力下,在240K~320K的温度范围内,初始温度对于预混气体火焰传播特性的影响。研究发现,初始温度对于不同预混气体的火焰传播特性的影响的规律大体相同,火焰速度和火焰温度都是随着初始温度的升高而升高,管道内最大压力随着初始温度的升高而降低,但是在相同时间点的管道内的压力随初始温度的升高而升高,这说明在尖端火焰阶段及Tulip火焰阶段,管道内压力的上升速度均随初始温度的升高而升高。模拟结果发现,在不同的体积分数下,管道内预混气体火焰传播过程中,尖端火焰阶段及Tulip火焰阶段的火焰速度,均随着初始温度的增加而增加。随着体积分数的增大,初始温度对于火焰温度及管道内压力上升速度的影响越来越小。在不同的初始压力条件下,火焰传播的速度是随着初始温度的升高而升高的,但是当初始压力升高到0.5MPa以上时,预混火焰温度的最高值及Tulip火焰阶段火焰温度的平均值都不随初始温度的变化而变化。在不同初始压力的条件下,管道内压力的最大值,随着初始温度的升高而降低。可以看出尖端火焰阶段的管道内压力的上升速度随着初始温度的升高而升高,但是在不同压力条件下,Tulip火焰阶段管道内压力的上升速度变化规律是不同的,初始压力在0.1MPa~0.5MPa的范围时,Tulip火焰阶段管道内压力的上升速度随初始温度的增加而增加,初始压力在0.5MPa~1MPa的范围时,Tulip火焰阶段管道内压力的上升速度随初始温度的增加而降低。
[Abstract]:At present, gas energy pipeline accidents occur frequently and the consequences are serious. In order to assist safety workers to work out the corresponding measures to prevent and control pipeline fire accidents according to different environmental temperature conditions, this paper makes use of CFD software to study the different conditions. The effect of initial temperature on the propagation characteristics of premixed flame in pipeline. In this paper, the geometric model of cuboid pipe is established by ANSYS Fluent, and the data obtained by numerical simulation are compared with those obtained by previous experiments. Based on the accuracy of the model, the effects of the initial temperature on the flame propagation characteristics of the premixed gas in the temperature range of 240K~320K were studied by using the model, in which the methane air premixed gas and propane air premixed gas were premixed at the temperature range of 240K~320K. Then taking methane air premixed gas as an example, the effect of initial temperature on flame propagation characteristics of premixed gas is studied under different volume fraction and different initial pressure in the temperature range of 240K~320K. It is found that the effect of the initial temperature on the flame propagation characteristics of different premixed gases is approximately the same, and the flame velocity and flame temperature increase with the increase of the initial temperature. The maximum pressure in the pipeline decreases with the increase of the initial temperature, but the pressure in the pipeline at the same time point increases with the increase of the initial temperature, which indicates that in the tip flame stage and the Tulip flame stage, The increasing velocity of the pressure in the pipeline increases with the increase of the initial temperature. The simulation results show that the flame velocities of the tip flame stage and the Tulip flame stage increase with the increase of the initial temperature during the flame propagation of premixed gas in the pipeline under different volume fraction. With the increase of volume fraction, the effect of initial temperature on flame temperature and pressure rise rate is smaller and smaller. Under different initial pressure conditions, the velocity of flame propagation increases with the increase of initial temperature, but when the initial pressure rises above 0.5MPa, The maximum temperature of the premixed flame and the average of the flame temperature in the Tulip flame stage do not change with the change of the initial temperature. Under different initial pressures, the maximum pressure decreases with the increase of initial temperature. It can be seen that the rising rate of pressure in the pipeline in the tip flame stage increases with the increase of the initial temperature, but the variation law of the pressure rising velocity in the tulip flame stage is different under different pressure conditions. When the initial pressure is in the range of 0.1MPa~0.5MPa, the increase rate of the pressure in the tube increases with the increase of the initial temperature, and the increase rate of the pressure in the initial pressure is decreased with the increase of the initial temperature when the initial pressure is in the range of 0.5MPa~1MPa.
【学位授予单位】：中国石油大学(华东)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE88

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