應用排氣壓力進行引擎增壓進氣之CFD計算

Using CFD to Calculate the Supercharged Flow of IC Engine Through Exhaust Pressure

何俊輝(Jun-Hui He)

指導教授 ： 周賢福

國立臺灣大學/工學院/機械工程學研究所/碩士(2004年)

https://doi.org/10.6342/NTU.2004.10155

摘要

二行程機車排氣污染較嚴重，已將被淘汰，但是50 c.c. 機車如果使用四行程引擎，會有馬力不足的問題，需要設法提升其馬力。而引擎燃燒所產生的能量，大約三分之一以廢氣的型態排放到大氣，如果能利用引擎的廢氣來推動進氣增壓裝置來增加容積效率，可將引擎的性能提升，同時可間接的在引擎排放的廢氣污染上作有效的控制。
由各種進氣增壓法的發展歷史看來，大部分都是用於汽車或是卡車上，鮮少用於機車上。所以要設計出一使用的機車進氣增壓設備則是一個可以研究的課題。
本研究設備利用活塞運動的原理，圓管內部有一固體滑塊，將中間的圓管分為新鮮氣室與廢氣室。圓管兩側分別接上兩直徑較小的圓管，其分別和進氣節流閥門前端及引擎廢氣排出端相接。利用圓管內滑塊兩側的壓力不同，使滑塊在圓管內水平滑動來擠壓新鮮氣室內的新鮮空氣進入引擎氣缸內來增加容積效率以提升引擎效能。
本文利用計算流體力學套裝軟體CFD-RC來模擬一進氣增壓設備，分析在不同的引擎轉速下，此進氣增壓設備的增壓效果及新鮮氣輸出量。

關鍵字

CFD-RC ； 進氣增壓 ； 引擎廢氣

並列摘要

The exhaust emission of two-stroke motorcycle engine is more serious than that of four-stroke engine, so it will be eliminated. But most of 50 c.c. motorcycles use two-stroke engines. The four-stroke 50 c.c. motorcycle will have the problem of lower power output, so we have to increase the power output of the engine. About one-third of input energy of internal combustion engine is released to ambient by exhaust gas. If we use the exhaust gas of engine to drive a supercharger that will increase the performance of engine, and can further reduce the exhaust emission.
By reviewing the history of supercharged internal combustion engine; we found out that almost all of supercharged methods have been developed was used for car or truck, none of them can be used for motorcycle. So designing a supercharger for motorcycles will be a subject that is worthy of studying.
This research used the principle of piston motion. There is a slider in the cylinder that is separated to exhaust chamber and fresh air chamber by this slider. Two small pipes were attached at the ends of cylinder. The fresh air chamber attached to the region in front of inlet throttle, and the exhaust chamber attached to the exhaust pipe of engine. The pressure difference between two sides of slider makes the slider to move in the cylinder that can boost the fresh air in the fresh air chamber to flow into the engine cylinder. That can increase the volumetric efficiency, and hence improve the engine performance.
This research used the computational fluid dynamic software “CFD-RC” to simulate the said supercharger. In the different operation condition, we analyze the supercharging pressure and the mass flow rate of this supercharger.

並列關鍵字

Supercharging ； Exhaust Gas ； CFD-RC

參考文獻

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