Analysis of Diesel Spray Evaporation Process in High Density and High Temperature Atmosphere

概要

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Diesel engines, in recent years, come to apply high pressure charging and high EGR to improve engine performance. In this situation, it is important to study on diesel spray behavior and mixture formation under those kinds of condition. This study investigates diesel spray development and micro-scale characteristics of droplets evaporation including atomization under high density and high temperature atmosphere. Experiment was carried out by shadowgraph photography method. Our system has a nano-spark light source to illuminate spray injected into spray chamber. The image analysis can reveal droplets size-distribution and droplets dynamic behavior at spray boundary. Results indicate that, at early stage of injection, high atmospheric density accompanied with high temperature greatly affects droplets atomization and evaporation at spray boundary. High density atmosphere produces small-size droplets. Evaporation of large-size droplets is improved with high density and high temperature atmosphere.