Study of Mastering Tefhnology on Internal-Combustion-Engine power Systems-Study and Development of Gasoline Direct Injection System(1)

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Project title

Code/計畫編號

NSC89-EPA-Z019-002

Translated Name/計畫中文名

內燃機動力系統關鍵技術研究─汽油直噴系統(GDI)研究與開發(I)

Project Coordinator/計畫主持人

Yuan-Liang Jeng

Funding Organization/主管機關

National Science and Technology Council

Department/Unit

Department of Mechanical and Mechatronic Engineering

Website

https://www.grb.gov.tw/search/planDetail?id=548468

Year

2000

Start date/計畫起

01-07-1999

Expected Completion/計畫迄

01-12-2000

Bugetid/研究經費

967千元

ResearchField/研究領域

機械工程

減少燃油消耗率、降低污染物排放及提高各項操作性能參數，實為汽車工業之一大挑戰。引擎為提供空氣與燃料混合燃燒場所，並將燃料燃燒後之熱能轉換成動能進而驅駛車子移動，但須藉由適當的進氣流場與燃燒室幾何形狀，才能讓油滴在引擎內完全燃燒。本研究即以直接噴射汽油引擎(GDI engine)為基本構思，把一具單氣缸柴油引擎加以改裝成測試引擎，並將氣缸頭上的進氣道形狀設計為能在缸內產生逆滾轉流場，並設置透明球面活塞凹穴使其能協助逆滾轉流場持續而不致削弱。運用流場可視化以相互交關PTV方式，於進氣及壓縮行程期間擷取氣缸內整個二維流場的速度結構，以分析引擎氣缸內所產生流場之循環變異性，與不同轉速不同曲柄角度之總體平均流場。結果顯示引擎於較高轉速時，由於氣流受到活塞快速移動之影響而具有較之高速梯度。由於氣缸頭設有兩個進氣閥，使得進氣行程中位於兩氣閥之間的高速氣流間相互剪切，因而造成大尺度滾轉運動受到破壞。氣缸內流場的擾動加劇，促使氣流往三維空間流動之情況更加明顯。 It is of a great challenge to reduce engine fuel consumption and exhaust emissions, as well as to improve engine performance. The combustion chamber of an engine allows air and fuel mixture to burn and transform heat into work, and provide vehicle with driving power. By appropriate geometric design of combustion chamber, favorable flow structure may be attained to achieve complete combustion in the cylinder. In this study, based on the concept of GDI engines, a single cylinder engine is modified to generate reverse tumble flow within cylinder by geometric design of intake port. On the other hand, a transparent piston with a spherical bowl is used to keep the reverse tumble motion. Optically accessible test section and cross-correlation PIV has been used to measure the 2D cylinder flow velocity distributions on the plane parallel to the cylinder axis. The instantaneous flow fields at different crank angles and engine speeds are studied to analyze the ensemble-average mean velocity and the cycle-to-cycle variations of instantaneous velocity. The results show that 2D reverse tumbling motion is observed at low engine speed, while strong indications of 3D cylinder flow occur at high engine speed. Caused by the double-intake valve design of cylinder head, the high-speed in-cylinder flow between the two intake valves during intake stroke creates shear layers to deform the large-scale rotating motion. The in-cylinder planar flow motion is therefore charged to spatially 3D flow.

Keyword(s)

汽油直接噴射系統
內燃機
逆滾轉運動
柴油引擎
曲柄角度
Gasoline direct injection system
Internal combustion engine
Reverse tumbling motion
Diesel engine
Crank angle

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Study of Mastering Tefhnology on Internal-Combustion-Engine power Systems-Study and Development of Gasoline Direct Injection System(1)

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