预混燃烧汽油机原排放的关键控制参数及共性规律研究

发布时间：2018-03-29 04:10

本文选题：预混燃烧　切入点：检测　出处：《湖南大学》2016年硕士论文

【摘要】：发动机排放作为发动机性能研究的一个重要组成部分,研究内燃机排放的共性规律,对该类型发动机正向开发的概念设计和校正、发动机台架标定等都具有十分重要的指导意义。文章侧重研究了点燃式预混燃烧发动机原排放的关键控制参数以及共性规律,力图建立预混汽油机排放、模型设计以及运行参数之间的内在联系。以一台单缸汽油机的燃烧试验数据、排放试验数据以及运行参数为基础,通过与三台先进的增压直喷发动机的试验数据做对比,研究点燃式预混燃烧发动机原排放的共性规律,可为同类发动机的正向开发提供目标,为其逆向开发提供评价体系。首先进行了理论方面的研究。一方面,探索了预混燃烧发动机混合气的形成过程以及发动机排放物CO、HC、NO_X的生成机理。另一方面,研究了主要排放物的检测方法及检测方面存在的不足。其次,进行了相关的试验。第一步,以一台预混燃烧单缸机为基础,进行系统的研究。为了了解单一控制参数对排放的影响,每次试验只变动一个控制参数以达到试验目的。第二步,对三台先进的增压直喷多缸机进行万有特性试验,试验过程中每次变动几个不同的控制参数,记录相关数据。最后,对实验的相关数据进行了处理。以单缸机试验数据为基础,结合多缸机各参数的变化,对多参数同时变化时发动机排放共性规律进行总结。单缸机的研究结果表明:EGR较小时,滚流比的减弱可以有效降低NO_X排放,最大可降低20%;随着EGR的逐步增大,滚流比对NO_X排放的影响逐步降低。当点火提前角变化时,HC排放与排气温度成反比例关系;在点火提前角较小时,滚流比对HC排放的影响较大;而在点火提前角较大时,滚流比对NO_X排放的影响较大。当过量空气系数处于1.0~1.6之间时,滚流比对HC与CO排放影响不大,而在过量空气系数较低区段,滚流比对NO_X排放的影响较大,可达40%。多缸机试验数据表明:能够引起缸内氧气浓度变化的参数对CO排放都会产生影响,如:过量空气系数、RGF等参数,其中过量空气系数对CO排放影响最大。过量空气系数、缸内压力、排气温度、进气温度、转速等都能够影响HC排放。按照影响程度大小,影响NO_X排放的主要因素分别为EGR、扭矩与过量空气系数等。
[Abstract]:Engine emissions, as an important part of engine performance research, study the common laws of engine emissions, and design and correct the concept of forward development of this type of engine. The calibration of engine bench has very important guiding significance. In this paper, the key control parameters and common rules of the original emission of ignition premixed combustion engine are studied, and the emission of premixed gasoline engine is established. Based on the combustion test data, emission test data and operating parameters of a single cylinder gasoline engine, the model design is compared with the experimental data of three advanced turbocharged direct injection engines. The study of the common rules of the original emission of the ignition premixed combustion engine can provide a target for the positive development of the same kind of engine and an evaluation system for the reverse development. The formation process of premixed combustion engine mixture and the formation mechanism of engine emission COHCOHCOHCOHCONO X are explored. On the other hand, the detection methods of main emissions and the shortcomings in detection are studied. In order to understand the effect of single control parameter on emission, only one control parameter is changed in each test to achieve the purpose of the test. In this paper, three advanced turbocharged direct injection multi-cylinder machines are tested with universal characteristics. During the test, several different control parameters are changed each time, and the relevant data are recorded. Finally, the relevant data of the experiment are processed, and based on the test data of single cylinder machine, Combined with the variation of multi-cylinder engine parameters, the common rules of engine emission are summarized when the multi-parameters change simultaneously. The results of single-cylinder engine research show that the decrease of roll flow ratio can effectively reduce NO_X emissions when the ratio of NO_X is small. With the increase of EGR, the effect of rolling flow ratio on NO_X emission decreases gradually. When the ignition advance angle changes, the HC emission is inversely proportional to the exhaust temperature, and when the ignition advance angle is small, the effect of rolling flow ratio on HC emission is greater. When the excess air coefficient is between 1.0 and 1.6, the effect of roll ratio on HC and CO emissions is not significant, but in the lower range of excess air coefficient, the effect of rolling flow ratio on NO_X emission is greater when the ignition advance angle is larger, and the effect of rolling flow ratio on CO emission is lower when the excess air coefficient is between 1.0 and 1.6. The effect of rolling flow ratio on NO_X emission can reach 40. The experimental data of multi-cylinder machine show that the parameters that can cause the change of oxygen concentration in the cylinder will affect the CO emission, such as the excess air coefficient and the other parameters, such as the excess air coefficient and so on. The excess air coefficient, pressure in cylinder, exhaust temperature, inlet air temperature, speed and so on can all affect HC emissions. The main factors affecting NO_X emission are EGR, torque and excess air coefficient.
【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TK411

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