航空煤油/乙醇混合燃油雾化特性数值模拟研究

Numerical simulation of kerosene/ethanol blends atomization characteristics

为了深入探究乙醇浓度对航空煤油/乙醇混合燃油雾化特性的影响,采用两相界面追踪方法中的VOF(Volume of Fluid)法对离心式喷嘴的雾化特性进行数值模拟,研究不同压降下,混合燃油中乙醇浓度对喷嘴流量系数C_(d)、液膜厚度t_(f)和雾化锥角θ的影响。研究结果表明:当压降从0.01 MPa增加到0.642 MPa时,C_(d)从0.723减小到了0.707,t_(f)从0.748 mm减小到了0.619 mm,θ从75.2°增加到了86.1°;当压降增加到0.2 MPa时,C_(d)保持不变,当压降继续增大到0.3 MPa时,θ和t_(f)保持不变;当混合燃油的乙醇浓度从0增加到30%时,C_(d)和t_(f)分别平均减小了0.88%和2.44%,而θ平均增加了1.13%,且乙醇浓度对喷嘴雾化特性的影响随压降的增加而变弱。最后,通过雾化锥角的模拟结果,拟合得到了雾化锥角和工质物性参数及压力之间的关联式。

In order to explore the influence of ethanol proportion on the atomization characteristics of kerosene/ethanol blends in-depth,interface-tracking method volume of fluid(VOF)was employed to simulate the atomization characteristics of pressure-swirl nozzle.The influence of the ethanol concentration in the kerosene/ethanol blends on the discharge coefficient C_(d),film thickness at the outlet t_(f),and spray cone angle θ of the nozzle were analyzed under different pressure drops.The results show that the nozzle C_(d) decreases from 0.723 to 0.707,t_(f) decreases from0.748 mm to 0.619 mm,andθincreases from 75.2°to 86.1°when the pressure drops from 0.01 MPa to 0.642 MPa.The nozzle discharge coefficient remains unchanged when the pressure drop increases to 0.2 MPa,and the cone angle and the film thickness at the outlet remain unchanged when the pressure drop continues to increase to 0.3 MPa.The discharge coefficient decreases by0.88%,the film thickness at the nozzle outlet decreases by 2.44%and the spray cone angle increases by 1.05%,when the ethanol concentration in kerosene/ethanol blends increases from 0 to30%.The effect of ethanol concentration on nozzle atomization characteristics become weak with the increase of pressure drop.Finally,based on the numerical results of spray cone angle,the correlation equation between the spray cone angle,the fuel physical parameters,and pressure drop was obtained by fitting.