Flow and Port Injection Characteristics of a Two-valve, Four-stoke, Motorcycle Engine:Computational and Experimental Analyses

• Main Authors: Cheng-yen Lin, 林政諺
• Other Authors: Rong-fung Huang
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/71732649064357837547

碩士 === 國立臺灣科技大學 === 機械工程系 === 100 === A two-valve, four-stroke, port-injection motorcycle engine was studied by using the experimental and computational methods. The experimental investigation employed a particle image velocimeter (PIV) to measure the in-cylinder tumble flow motion in the symmetry and offset planes. The results was used to evaluate the appropriation of the strength of the in-cylinder tumble motion and to validate the computational results. The computational analyses used the commercial code STAR-CD to calculate the in-cylinder flow as well as the distributions of the fuel droplet diameter and fuel concentration. The computational results of flow evolution process in the cylinder were quite resemble to those measured by experiments. While the calculated tumble ratios on symmetry plane were significantly deviated from the measurement results by about 81 %, and offset plane were about 232 %. However, the computational results could be used for relative evaluation when the design mechanisms for tumble motion were conduced. The engine speed did not cause apparent flow evolution difference. But the calculated tumble ratio at high engine speed presented larger value than the low speed did. The calculation results of port injection showed that injection at advanced crank angle caused the fuel droplet diameter finer and the fuel concentration more uniform.