摘 要
基于低碳、低排放是未來船用發(fā)動(dòng)機(jī)技術(shù)的發(fā)展方向，本文以某艇用柴油發(fā)動(dòng)機(jī)作為研究對(duì)象。主要做了如下幾方面工作：
1．綜合缸徑、壓縮比、燃料物性等相關(guān)因素，對(duì)該艇用發(fā)動(dòng)機(jī)燃燒室結(jié)構(gòu)進(jìn)行了適當(dāng)?shù)馗倪M(jìn)，并建立了燃燒室改進(jìn)前后的三維幾何模型。
2．在LINUX系統(tǒng)下，基于Es-ice軟件建立了該艇用發(fā)動(dòng)機(jī)燃燒室改進(jìn)前后的動(dòng)網(wǎng)格模型。
3．運(yùn)用湍流控制渦團(tuán)破碎燃燒模型，即EBU模型對(duì)其燃燒室改進(jìn)前后燃用DME的性能、缸內(nèi)氣體流動(dòng)狀況、混合氣形成狀況、主要污染物分布情況、及其排放特性等均進(jìn)行了數(shù)值摸擬計(jì)算，并相應(yīng)地作了對(duì)比與分析。
4．本文還對(duì)燃燒室改進(jìn)后艇用DME發(fā)動(dòng)機(jī)的噴油提前角與渦流轉(zhuǎn)速兩個(gè)性能參數(shù)進(jìn)行了優(yōu)化分析，對(duì)其燃燒室改進(jìn)前后不同噴油提前角與渦流轉(zhuǎn)速下燃用DME的性能、排放特性及缸內(nèi)主要污染物分布情況分別進(jìn)行了仿真研究。
通過對(duì)數(shù)值計(jì)算結(jié)果的對(duì)比與分析，得出主要結(jié)論如下：
1．發(fā)動(dòng)機(jī)燃燒室改進(jìn)后，改善了缸內(nèi)氣體后期的流動(dòng)狀況，有利于DME的霧化，促進(jìn)了燃燒的進(jìn)行，且發(fā)動(dòng)機(jī)功率未受影響，工作卻更加柔和；
2．NOX與CO2較改進(jìn)前分別下降約7.3626% 和2.641%；
3．燃燒開始后，NOX與CO2均先在燃燒室中上部產(chǎn)生，然后逐漸向兩側(cè)擴(kuò)散，且兩者中心區(qū)域的質(zhì)量分率都較低；
4．燃燒室改進(jìn)后的DME發(fā)動(dòng)機(jī)，其噴油提前角與渦流轉(zhuǎn)速分別選為BTDC -9°CA和5040 r/min時(shí)較為理想。
上述結(jié)論為艇用DME發(fā)動(dòng)機(jī)燃燒室的改進(jìn)及其性能參數(shù)的優(yōu)化提供了參考依據(jù)，對(duì)未來船用發(fā)動(dòng)機(jī)的發(fā)展具有很好地指導(dǎo)意義。

關(guān)鍵詞：艇用DME發(fā)動(dòng)機(jī)、燃燒室改進(jìn)、噴油提前角、渦流轉(zhuǎn)速、污染物





ABSTRACT
The future direction of development in marine engine technology will be low-carbon and low emission. One yacht diesel engine is studied in this paper. The main tasks were completed as follows:
1. The structure of combustion chamber was properly improved based on cylinder diameter, compression ratio, fuel properties and other related factors. Besides, the three-dimensional geometric models before and after the combustion chamber improved were built.
2. The dynamic mesh models were established respectively before and after the combustion chamber improved by Es-ice in LINUX system.
3. The engine performance, gas flow condition, mixture formative situation, major pollutants distribution and emission characteristics were numerically calculated when the engine fueled with DME based on combustion model of turbulence-controlled eddy break-up (that is EBU model) before and after the combustion chamber improved. Besides, these calculations were compared and analyzed.
4. Two performance parameters of fuel injection advance angle and swirl rate were optimally analyzed after the combustion chamber improved on the DME yacht engine. The engine performance, emission characteristics and major pollutants distribution in cylinder in different fuel injection advance angles and swirl rates when fueled with DME before and after the combustion chamber improved were numerically studied.
Comparison and analysis on the results of numerical calculation, main conclusions were gained as follows:
1. The later gas flows in cylinder was perfected, but also DME atomization and combustion were promoted after the combustion chamber improved. Besides, the engine power was not affected, on the contrary, the work of the engine was more gentle.
2. NOX and CO2 emissions were declined approximately 7.3626% and 2.641% respectively compared with the previous engine.
3. Both NOX and CO2 were first produced in the middle and upper part of the combustion chamber after burning, then spread to the sides gradually, and the mass fraction in center was low.
4. The fuel injection advance angle and swirl rate after the combustion chamber improved on the DME engine were selected BTDC -9 °CA and 5040 r/min to be ideal.
Above all, these will be provided a reference basis for improving the combustion chamber and optimization performance parameters of the DME yacht engine, besides, these also have a great significance for the development of future marine engines.
Key words: DME yacht engine; combustion chamber improved; fuel injection advance
angle; swirl rate; pollutant





























目 錄
摘 要 I
ABSTRACT III
注釋表-縮寫詞 IX
第一章 緒 論 - 1 -
1.1 選題背景及意義 - 1 -
1.2 二甲醚的化學(xué)結(jié)構(gòu)與理化性質(zhì)分析 - 2 -
1.2.1 二甲醚的化學(xué)結(jié)構(gòu) - 2 -
1.2.2 二甲醚的理化性質(zhì) - 3 -
1.3 國(guó)內(nèi)外二甲醚制取技術(shù)簡(jiǎn)介 - 4 -
1.4 發(fā)動(dòng)機(jī)燃用二甲醚的研究現(xiàn)狀 - 4 -
1.4.1 國(guó)外研究現(xiàn)狀 - 4 -
1.4.2 國(guó)內(nèi)研究現(xiàn)狀 - 7 -
1.5 本文的主要工作內(nèi)容 - 8 -
1.6 本章小結(jié) - 10 -
第二章 建立數(shù)學(xué)模型與改進(jìn)燃燒室結(jié)構(gòu) - 11 -
2.1 本文選用的數(shù)學(xué)模型 - 11 -
2.1.1 缸內(nèi)氣體湍流擴(kuò)散模型 - 11 -
2.1.2 噴霧與著火模型 - 12 -
2.1.3 燃燒模型 - 13 -
2.1.4 NOX生成模型 - 15 -
2.2 樣機(jī)的基本參數(shù)與初始、邊界條件的確定 - 15 -
2.2.1 樣機(jī)的基本參數(shù) - 15 -
2.2.2 初始、邊界條件的確定 - 16 -
2.3 燃燒室改進(jìn)的依據(jù)及其物理模型的建立 - 17 -
2.4 燃燒室改進(jìn)前后氣缸網(wǎng)格的劃分 - 19 -
2.5 本章小結(jié) - 21 -
第三章 燃燒室改進(jìn)前后數(shù)值計(jì)算結(jié)果的對(duì)比與分析 - ..