摘 要

为了缓解能源危机和环境污染问题给内燃机行业造成的冲击，很多学者开始研究新型燃烧方式以减少油耗、降低排放，均质压燃（HCCI）、预混合充量压燃（PCCI）、预混合分层压燃（PSCCI）、反应可控压燃（RCCI）等燃烧模式随之产生。随着研究深入，很多学者发现各种新型燃烧模式存在负荷难以拓展或燃烧过程不能有效控制等问题。基于此，高预混可控压燃（HPCCI）模式被提出，为解决燃烧调控和负荷拓展问题提供了新的方向。

本文目的为探究不同参数对柴油/乙醇双燃料HPCCI燃烧模式的影响，从而找到有效的控制方法，实现清洁高效燃烧。HPCCI燃烧模式基本思想为：在进气道喷射低活性燃料，缸内预喷高活性燃料，二者形成较低活性的预混合气，在上止点附近主喷微量高活性燃料形成微火源，引燃预混合气，从而实现着火时刻和燃烧过程的可控。本文实验探究依托可视化发动机试验台，使用Mie散射法和高速摄像机拍摄图像，并对图像进行相关处理，研究了主喷柴油量、预混合气活性对柴油/乙醇双燃料HPCCI燃烧模式的影响；基于AVL Boost仿真软件建立了柴油/乙醇双燃料HPCCI燃烧模式的一维模型，并探究了主喷柴油正时和进气道进气温度对燃烧过程的调控作用。

经实验探究发现，HPCCI 燃烧模式的放热表现为三个过程：在-10°CA前后开始的放热阶段，主喷柴油形成微火源的扩散燃烧阶段，预混合气被引燃之后的主放热阶段。随着主喷柴油量的增加，着火始点的变化不大，但微火源的燃烧情况及后续的预混燃料燃烧都得到改善；低活性预混合气的活性大小对HPCCI燃烧模式的各阶段都产生了影响，改变预混合气的活性可以对燃烧过程进行一定的调控。

仿真结果表明：在其它参数相同的情况下，随主喷柴油正时的提前，着火时刻和燃烧相位随之提前，放热率和缸内爆发压力都有一定的提高；随着进气温度的提高，缸内热氛围提升，燃料的蒸发与雾化条件变好，燃烧过程得到改善。

从以上研究可以得出，主喷油量和进气温度对HPCCI燃烧模式都有较大的影响，适当提高主喷油量和进气温度可以改善燃烧过程；主喷时刻和预混合气活性调控HPCCI燃烧模式燃烧过程的作用明显。

关键词：高预混可控压燃；双燃料；乙醇/柴油；AVL Boost

Abstract

In order to alleviate the impact of the energy crisis and environmental pollution on the internal combustion engine industry, many scholars have begun to study new combustion methods to reduce fuel consumption and emissions, homogeneous compression ignition (HCCI), premixed charge compression ignition (PCCI), premixed stratified charge compression ignition (PSCCI), reactive controllable compression ignition (RCCI) and other combustion modes came into being. With the development of research, many scholars find that the new combustion mode has some problems, such as the load is difficult to expand or the combustion process can^＇t be effectively controlled. Based on this, the high premixed controlled compression ignition (HPCCI) model is proposed, which provides a new direction for solving the problems of combustion regulation and load expansion.

The purpose of this paper is to explore the effect of different parameters on the ethanol / diesel dual fuel HPCCI combustion mode, so as to find effective control methods to achieve efficient and clean combustion. The basic idea of ​​the HPCCI combustion mode is: inject low-activity fuel in the intake port, pre-inject high-activity fuel in the cylinder, the two form a lower-activity premix, and micro fire source is formed by injecting micro active fuel near the top dead center, ignite the premixed gas, so as to realize the control of the ignition moment and combustion process. In this paper, we explored the effects of the main injection diesel volume and premixed gas activity on the ethanol / diesel dual fuel HPCCI combustion mode based on the visual engine test bed system, using the Mie scattering method to assist the high-speed camera to capture images, and combining image processing technology; AVL Boost simulation software establishes a one-dimensional model of ethanol / diesel dual-fuel HPCCI combustion mode, and explores the regulation effects of the main injection diesel timing and intake temperature on the combustion process.

Through experimental investigation, it is found that the HPCCI combustion mode has three main exothermic stages: the low-temperature exothermic stage starting near -10 ° CA, the main injection of diesel fuel forms the diffusion combustion stage of the micro-fire source, and the main heat release stage after the premixed gas is ignited. With the increase of the amount of diesel fuel, the change of ignition starting point was not significant, but the combustion condition of micro ignition source and the subsequent premixed fuel combustion were improved; the activity of the low-activity premixed gas affects all stages of the HPCCI combustion mode, changing the activity of premixed gas can regulate the combustion process to a certain extent.

The simulation results show that when other parameters are the same, with the advance of timing of main diesel injection, the ignition time and combustion phase are also advanced, and the heat release rate and cylinder burst pressure are improved to some extent; with the increase of the intake temperature, the thermal atmosphere in the cylinder increases, the evaporation and atomization conditions of the fuel become better, and the combustion process is improved.

From the above research, it can be concluded that the main injection quantity and intake air temperature have a greater impact on the HPCCI combustion mode. The combustion process can be improved by increasing the main fuel injection and inlet temperature; The main injection timing and premixed gas activity have a significant effect on the combustion process regulation of HPCCI combustion mode.

Key Words：high premixed controllable compression ignition；dual fuel；ethanol/diesel；AVL Boost

目 录

第1章 绪论 1

1.1 引言 1

1.2 低温燃烧实现方法 1

1.3 不同参数对燃料分层的影响 3

1.3.1 喷油策略影响 3

1.3.2 燃料组合影响 5

1.3.3 发动机结构的影响 6

1.4 光学测量技术在内燃机研究中的应用 7

1.4.1 化学发光法的研究现状 7

1.4.2 激光诱导炽光法的发展及其相关研究 8

1.4.3 激光诱导荧光技术的研究与应用 9

1.4.4 Mie 散射法的国内外研究 10

1.5本文研究内容 10

第2章 试验装置及研究方法 12

2.1 试验装置 12

2.1.1 试验台架基本构成 12

2.1.2 单缸发动机介绍 13

2.1.3 燃油供给及控制系统 15

2.1.4 润滑油循环系统 17

2.1.5 实验所用主要设备 18

2.2 实验方法 18

2.2.1 试验所用光学研究方法 18

2.2.2 图像处理方法 19

2.3 本章小节 20

第3章 乙醇/柴油高预混可控压缩燃烧实验探究 21

3.1 乙醇/柴油 HPCCI 燃烧模式介绍 21

3.2 实验研究工况设置 23

3.3 主喷燃料对HPCCI燃烧模式的影响 25

3.4 预混合气活性对HPCCI燃烧模式的影响 27

3.5 本章小节 29

第4章 乙醇/柴油高预混可控压缩燃烧仿真模拟 30

4.1 AVL boost软件介绍 30

4.2 仿真模拟方法及模型的建立 30

4.2.1仿真模拟方法 30

4.2.2 模型建立 31

4.3计算结果分析与模型验证 35