潔淨節能而且可靠的引擎系統必須仰賴燃燒室中燃料噴注、點火、燃料/空氣混合過程的精確控制，本論文所進行的研究係以光陽機車股份有限公司目前量產之商用500c.c.單缸四閥歧管噴射引擎為平台，其缸徑與衝程分別為92mm與75mm。本研利用上述的引擎平台並將之修改成光學透明引擎，運用石英汽缸取代原有的汽缸套，使雷射光頁可以進出燃燒室以進行相關研究，該光學透明引擎亦設置一透明石英視窗於延伸活塞中，此設計將可以讓吾人觀察水平切面的流場特徵。另外一方面，吾人進行引擎潤滑系統的修改、雷射系統及攝影機與該引擎系統的同步控制，和粒子植入裝置以完善本研究之相關所需週邊配置。燃燒室中的流場特徵主要是利用視流法與粒子影像測速技術加以量測，其所量得之二維速度流場、平均速度、旋轉比與滾轉比之成果將成為汽油引擎缸內定量分析重要的數據。

A reliable, clean, and energy-saving engine system deeply depends on a large degree of the optimal control of fuel injection, ignition, and fuel/air mixing process in the combustion chamber. Investigations in the present study are carried out in a cylinder of a mass-production 500c.c single-cylinder four valve PFI engine supplied by Kymco. The bore and stroke is 92mm and 75 mm respectively. The engine is modified to facilitate optical access by the placement of a quartz liner for laser beam entrance and exit and one quartz window with a diameter of 50 mm into the elongated piston for the detection of Mie-scattering. Furthermore, the modified lubrication system, electronic control system for laser and CCD synchronization, and a seeding system are also developed for optical access engine. The flow characteristics in the combustion chamber are measured by using flow visualization technique and digital particle image velocimetry. The measured 2-D velocity information, average velocity graph, swirl ratio, and tumble ratio can provide the basis for quantitative analysis of in-cylinder flow field of gasoline engine.

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