| Summary: | 碩士 === 國立雲林科技大學 === 機械工程系碩士班 === 101 === This research wants to study the spray dynamics inside a Kymco Xcitin 500c.c. gasoline engine. The high speed optical technology is applied for observing the 100barG injection at piston varied temperature (303、363、423K), impingement angle (0、30、45deg), and cylinder pressure (0bar、3.5bar、7bar). The PIV(Particle Image Velocimetry) is used for the droplet velocity acquisition. The results can be used for better engine spray srtategy.
Results show that the increased plate temperature reduced the fuel viscosity so that the splash range is increased by 10%. If the plate is inclined, the increment can be up to 35%. The high incline plate angle pushes the splash range increased by about 40~55%. When the cylinder pressure is increased, the spray angle, spray splash range (by 30~50%), and the droplet velocity are reduced. When the inclined angle increased, the rebounding droplet tangential velocity increased, the vortex if formed, which is better for fuel-air mixing and combustion inside the cylinder.
The research finds the increased plate temperature and inclined impingement angle will increased the droplet velocity after rebounding and allows better fuel distribution inside the combustion chamber. The increased cylinder pressure is no good for droplet breakup and vaporization,; however, the adjustment of the cylinder and piston geometry, spark plug, nozzle position, and the surface temperature can improve these problems.
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