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液滴自点火延迟的简化模型

发表时间:2009-04-30  浏览量:1663  下载量:764
全部作者: 陈君,彭晓峰
作者单位: 清华大学机械工程学院
摘 要: 燃料液滴突然进入高温空气环境后,会发生自点火现象,液滴进入与自点火发生之间的时间间隔称为液滴自点火延迟时间。通过分析当量比等于1的气体微团升温及反应历程,给出一种确定液滴自点火延迟时间的简化模型。该模型明确地区分了液滴自点火延迟的物理和化学因素,可以较好地预测液滴自点火过程,给出与实验及数值模拟相当的自点火延迟时间。利用此简化模型,详细分析了环境温度和液滴大小对自点火延迟的影响:环境温度越低,气体微团温度也越低,自点火延迟时间越长,物理延迟部分所占比重越大;液滴初始半径越小,自点火延迟时间越短,化学延迟部分所占比重越大。
关 键 词: 工程热物理;燃料液滴;自点火延迟;液滴自点火延迟时间
Title: A simplfied model of droplet ignition delay time
Author: CHEN Jun, PENG Xiaofeng
Organization: School of Mechanical Engineer, Tsinghua University
Abstract: When a droplet is suddenly injected into high temperature environment, the droplet self-ignition phenomenon occurs. And this time period between the droplet injection and self-ignition occurrence is termed droplet ignition delay time. A simple model, based on the temperature increasing history of target gas mixture of which the equivalence ratio is equal to 1, was proposed to predict the droplet ignition delay time in this paper. This model clearly divides the droplet self-ignition delay into two parts, the physical delay and the chemical delay. And the predicted droplet ignition times agree well with the experimental data and the numerical simulation results. Using this approach, the influences of environmental temperature and droplet diameter on the droplet ignition delay were discussed. The droplet ignition delay time increases with the decreasing environmental temperature. The physical delay plays a more important role at lower environmental temperature. With decreasing droplet diameter, the droplet ignition delay time decreases, and the chemical delay plays a more important role.
Key words: engineering thermophysics; fuel droplets; self-ignition; droplet ignition delay time
发表期数: 2009年4月第8期
引用格式: 陈君,彭晓峰. 液滴自点火延迟的简化模型[J]. 中国科技论文在线精品论文,2009,2(8):768-774.
 
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