喷雾壁面复合引导LPG直喷增压发动机燃烧过程的数值模拟

发布时间：2018-02-03 02:27

本文关键词： LPG 喷雾壁面复合引导均质分层数值模拟简化　出处：《山东建筑大学》2016年硕士论文　论文类型：学位论文

【摘要】：近年来人们生活水平不断提高,汽车的大量普及也带动了汽车行业的快速发展但也给人们带来了一系列能源紧张和环境污染等问题。因此人们开始试图寻找新型可替代汽车能源,液化石油气(L,PG)就是其中最具代表的新型能源之一。它具有储运方便、辛烷值高、排放有害污染物少等传统燃料无法比拟的优点。本文采用本课题组提出的复合引导燃烧系统,数值模拟了LPG增压发动机在大负荷工况下的均质当量比燃烧和部分负荷工况下的分层稀薄燃烧过程。本文采用AVL FIRE软件分别建立了双进气道和单进气道动网格模型,来模拟发动机在不同工况下的混合气形成和燃烧过程。在计算过程中,我们需要把L,PG的化学动力学机理耦合在FIRE软件中。若直接把详细的化学动力学反应机理与FIRE软件耦合来进行数值模拟对计算机的配置要求高且耗费的计算时间长,为此本文把详细的化学动力学机理进行简化最终包含32个组分和69个化学反应的简化模型,并对其有效性进行了验证。分别对大负荷工况的均质燃烧和部分负荷工况的分层稀薄燃烧的混合气形成和燃烧过程进行了数值模拟。结果表明：在均质当量比下选取喷油定时为70°CA ATDC时可在上止点前20°CA在缸内形成较好的均质混合气。通过选取不同点火正时来研究燃烧过程结果表明,点火时刻越早即25。CA BTDC点火燃烧特性最好对外有效做功多但CO和NO的排放也随之升高,其最大爆发压力对应的相位角在上止点后5～15°CA。数值模拟了单进气道四冲程LPG发动机部分负荷工况下的分层稀薄燃烧过程。在分层燃烧模式下,喷油定时设在上止点前40。CA时,可以在上止点前形成较好的分层混合气。然后在发动机转速为2000r/min和3000r/min两种情况下对不同点火时刻的燃烧过程进行了对比分析。转速为3000r/min时LPG发动机在燃烧过程的放热率峰值和缸内最高爆发压力更高且CO排放更少,有较好的燃烧特性,但其NO的排放有所升高。
[Abstract]:In recent years, people's living standards have been improving. The popularity of automobile has also brought the rapid development of automobile industry, but also brought a series of problems such as energy tension and environmental pollution, so people began to try to find new alternative automobile energy. Liquefied petroleum gas (LPG) is one of the most representative new energy sources. It has convenient storage and transportation and high octane number. The advantages of traditional fuels such as low emission of harmful pollutants are incomparable. In this paper, the compound guided combustion system proposed by our team is adopted. The homogeneous equivalent ratio combustion of LPG turbocharged engine and the stratified rarefied combustion process under partial load condition are numerically simulated. AVL is used in this paper. The dynamic grid models of double inlet and single inlet are established by FIRE software. In order to simulate the mixture formation and combustion process of the engine under different operating conditions. The chemical kinetic mechanism of PG is coupled to the FIRE software. If the detailed chemical kinetic reaction mechanism is coupled directly with the FIRE software to carry out the numerical simulation, the computer configuration is required and the calculation cost is high. Interiors. In this paper, the detailed chemical kinetic mechanism is simplified and the simplified model of 32 components and 69 chemical reactions is included. The numerical simulation of the mixture formation and combustion process of homogeneous combustion under high load condition and stratified lean combustion under partial load condition has been carried out. The results show that: 1. Selecting injection timing of 70 掳CA under homogeneous equivalent ratio. A better homogeneous mixture can be formed in the cylinder at 20 掳CA before the up-and-down point at ATDC. The combustion process results show that different ignition timing can be selected to study the combustion process. The earlier the ignition time is, the better the burning characteristic of 25.CA BTDC is, but the CO and no emission is also increased. The phase angle corresponding to the maximum burst pressure is 5 ~ 15 掳CA. the stratified rarefied combustion process of a single-port four-stroke LPG engine under partial load condition is numerically simulated. The injection time was set at 40. CA before the upper check point. A better stratified mixture can be formed before the top and down point, and then the combustion process at different ignition times is compared and analyzed at the engine speed of 2000r / min and 3000r / min respectively. The peak heat release rate of the LPG engine during combustion and the maximum burst pressure in the cylinder are higher and the CO emission is less when the speed is 3 000 r / min. It has good combustion characteristics, but its no emission is increased.
【学位授予单位】：山东建筑大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U464.114

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