生物油雾化特性的数值研究

NUMERICAL SIMULATION OF BIO-OIL ATOMIZATION CHARACTERISTICS

基于两相界面追踪方法 VOF(volume of fluid)研究生物油在离心式喷嘴内的雾化特性,考察喷射流量对流量系数、雾化锥角和液膜厚度的影响,并与生物油/甲醇混合燃料的雾化特性进行对比。结果表明:喷射流量对雾化锥角及液膜厚度有较大影响,对流量系数影响较小。喷射流量从0.03 kg/s增至0.12 kg/s,流量系数增大3.4%,雾化锥角增大30.6%,而液膜厚度减小22.3%;雾化锥角随甲醇含量的增大呈线性递增,而液膜厚度随甲醇含量的增大呈线性递减;利用数值结果拟合得到生物油液膜厚度的经验公式,拟合值和数值计算值吻合较好。

The atomization characteristics of bio-oil in centrifugal nozzle for combustion were investigated by using the Ansys Fluent two-phase flow numerical method VOF model. The effect of jet flow rate on the flow coefficient,film thickness and atomization cone angle was investigated and compared with that of the bio-oil/methanol blended fuel. The results show that the jet flow rate has a great influence on the atomization cone angle and the film thickness,and has little effect on the flow coefficient. As the jet flow rate increased from 0.03 kg/s to 0.12 kg/s,the flow coefficient increased by 3.4%,the spray angle increased by 22.1%,and the film thickness decreased by 22.3%.By adding methanol to the bio-oil,the atomizing quality was improved. The cone angle of the atomization increases linearly with the increase of the methanol content,while the film thickness decreases linearly. The empirical equation for the film thickness was derived. The predicted results were found to be in a good agreement with the experiment results,which can predict the atomization characteristics of the nozzle.