层流火焰淬熄电学特性的实验研究及数值模拟

发布时间：2018-01-22 03:42

  本文关键词： 火焰淬熄 电学特性 控制变量 数值模拟　出处：《哈尔滨工业大学》2016年硕士论文　论文类型：学位论文

【摘要】：随着微型机电系统的快速发展,人们对于结构尺寸更小,功率密度更大的微型能源系统的需求愈加迫切。微尺度燃烧动力系统由于能量密度高的特点而受到了广泛的关注。然而微尺度燃烧与常规燃烧相比会产生很多新的问题。微尺度燃烧不能维持稳定,会发生淬熄即熄火。由于火焰本身是一种弱电离的等离子体,碳氢燃料的火焰中含有许多诸如CHO+、H3O+、e、OH-等直接与化学反应相关的带电的粒子,淬熄发生时火焰速度降低,最终停止向壁面传播,会引起上述带电粒子数量与分布的变化。因此,对于火焰淬熄的电学特性研究十分必要。本课题从理论分析、实验研究两方面对层流稳态火焰淬熄电学特性进行了研究,利用数值模拟方法对层流火焰淬熄时的燃烧特性进行了分析,对层流火焰淬熄时参数的变化规律进行了探讨。本课题研究结果如下:设计并搭建了层流火焰淬熄的电学特性实验台。本课题采用控制变量法进行实验。理论方面从分子动理论角度得到了粒子近碰撞的频率值,并且从等离子角度得到了直流小电场条件下火焰的电导率的数量级为10-8。采用控制变量法,只改变燃烧器与淬熄平面之间的电压值。电压值取20V、40V、60V、80V,发现电压加载方向影响电流大小,燃烧器上为负电压时电流较大。电流值随着电压值的增大而增大。在一定范围内,同一高度处火焰的电阻值保持不变,不随着电压大小的变化而变化。淬熄平面的材质对于火焰淬熄的电学特性影响较小。淬熄时,随着距离的减小,火焰向上的传播受到了阻碍,火焰的高温区向着燃烧器左右两侧移动,并且反应区域内最高温度降低。CO2的含量先增加后减小,CO的含量先增加后减小。距离50mm条件下,随着空气量的增加,火焰淬熄时的温度最大值逐渐升高。火焰的高温区域随着空气量的增加逐渐向着中间区域集中;轴向速度逐渐升高;CO的质量分数逐渐减小,并且CO质量分数的最高值的位置呈下降趋势;CO2的质量分数最大值逐渐下降,火焰的CO2的质量分数较大的区域随着空气量的增加逐渐向着中间区域集中。
[Abstract]:With the rapid development of MEMS, the size of structure is smaller. The demand of micro-energy system with higher power density is becoming more and more urgent. The micro-scale combustion power system has attracted wide attention because of its high energy density. However, micro-scale combustion will produce many new ones compared with conventional combustion. Microscale combustion cannot be maintained stable. Since the flame itself is a weakly dissociated plasma, the flame of hydrocarbon fuel contains many such as CHO H3O OE. OH- and other charged particles directly related to chemical reactions will cause changes in the number and distribution of charged particles when quenching occurs and the flame velocity decreases and eventually stops propagating to the wall. It is necessary to study the electrical properties of flame quenching. In this paper, the electrical properties of laminar steady flame quenching are studied from two aspects: theoretical analysis and experimental study. The combustion characteristics of laminar flame quenching were analyzed by numerical simulation. The variation of the parameters of laminar flame quenching is discussed. The results are as follows:. The electrical characteristics of laminar flame quenching were designed and built. The control variable method was used in the experiment. In theory, the frequency of particle near collision was obtained from the viewpoint of molecular kinetic theory. The order of magnitude of the flame conductivity under the condition of a small DC electric field is obtained from the plasma angle. By using the control variable method, only the voltage between the burner and the quenching plane is changed, and the voltage value is 20V. It is found that the voltage loading direction affects the current size, and the current is larger when the burner is negative voltage. The current value increases with the increase of the voltage value, and within a certain range. The resistance of flame at the same height remains constant and does not change with the change of voltage. The material of quenching plane has little effect on the electrical properties of flame quenching. The upward propagation of the flame is hindered, the high temperature region of the flame moves to the right and left sides of the burner, and the maximum temperature in the reaction region decreases. The content of CO2 increases first and then decreases. The content of CO increased first and then decreased. At the distance of 50mm, the content of CO increased with the increase of air volume. When the flame quenched, the maximum temperature gradually increased. The high temperature region of the flame gradually concentrated towards the middle region with the increase of the air volume. Axial velocity increased gradually; The mass fraction of CO gradually decreased, and the position of the highest value of the mass fraction of CO decreased. The maximum mass fraction of CO2 decreases gradually, and the region with higher mass fraction of CO2 in flame is gradually concentrated in the middle region with the increase of air volume.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TK16
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本文编号：1453536