四行程機車引擎三維進排氣閥道之流場數值分析

• Main Author: 汪大綱
• Other Authors: 張錦裕
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/43013951531507276627

碩士 === 國立成功大學 === 機械工程學系 === 85 === The purpose of this paper is to numerically analyze the intake and exhaust port flow in a four-stroke spark ignition engine. The computational grids are constructed by the multi-block method. The flow is assumed quasi-steady state and 3-D k-ε turbulent model is employed. Numerical results at two different pressure difference (762 mmH2O and 1016 mmH2O) for the following engine performance parameters are presented: such as air flow rate, flow coefficient, swirl ratio and tumble ratio. 　For the flow through an intake valve-port assembly, due to the sudden change area between the valve and cylinder wall, there is a separation occurs. Both the swirl and tumble will gradually decrease with increase of distance from the top dead center. For the flow through an exhaust valve-port assembly, the flow inside cylinder is almost uniform. Flow structure is nearly the same at different exhaust valve lifts but a large recirculation flow is observed near the exhaust port wall at smaller exhaust valve lift (Lv＝1 mm). The numerical predictions of air flow rate and flow coefficient are in good agreement with available experimental data.