柴油机缸内环境下碰壁喷雾的蒸发特性研究

Investigation into Evaporation Characteristics of Spray Impinged on Flat-Wall in Diesel-Like Ambient Gas

在高温高压定容弹内基于紫外/可见光两波长激光吸收与散射法测得的柴油模拟燃料碰壁喷雾的气液两相浓度分布、贯穿距、平均粒径等数据,并由此研究碰壁喷雾蒸发模型的准确性,提出了碰壁喷雾的标定方法,最后用标定好的模型对不同喷油量条件下的喷雾进行预测并用实测数据进行验证。由此揭示了主要标定参数对蒸发特性的影响规律,如回弹韦伯数越大蒸发量及蒸发速率下降越明显等,并提出了蒸发碰壁模型的主要标定参数的确定方法。

A calibration method for an evaporating impingement spray model was presented. First, spray penetration, SMD and mass distributions of vapor/liquid phases in sprays, which were impinged on the flat-walls of a high temperature and high pressure bomb that could simulate the actual in-cylinder ambient condition of a diesel engine, were measured using laser-based approaches. Then a breakup model, a wall interaction model and a vaporization model were developed, verified and calibrated by the above measured parameters. Next, the prediction of spray under different conditions was made using these calibrated models and verified by the measured data, revealing the influences of main calibration parameters on evaporation characteristics, such as the effect of rebound Weber number on vaporization. Finally, the method was proposed to select the major calibration parameters for the evaporating impingement spray model.