摘要
为研究航空煤油凝胶液滴在横向气流中的二次雾化特性,建立了二次雾化实验台,制备了3种胶凝剂含量下的航空煤油凝胶,在不同实验条件下(82<We<691,9.6×10-4<Oh<3.77)对液滴二次雾化过程进行了拍摄。测量了液滴变形、破碎模态、破碎时间、剥离速度及R-T(Rayleigh-Taylor)不稳定波波长等特征参数,并与航空煤油液滴进行了对比。结果表明:在实验条件,煤油和煤油凝胶液滴无量纲变形率在0.5~2.0,胶凝剂含量增加,液滴粘性效应增强,平均无量纲变形率降低;航空煤油和凝胶液滴具有两种破碎模态,同种破碎模态下,煤油和煤油凝胶的破碎过程相同;煤油和煤油凝胶液滴初始和总破碎时间随We数变化规律基本相同。不同Oh数下,3%煤油凝胶初始和总破碎时间与文献计算值相差较大,而其余3种材料液滴则吻合较好;液滴剥离速度随We数逐渐增加。We数低于200时,煤油剥离速度高于煤油凝胶,但继续增大We数时则相差不大;R-T不稳定波波长随We数增加而减小。煤油、1%和2%煤油凝胶波长实验值和理论值基本吻合,而对3%煤油凝胶,理论值则高于实验值。
In order to study the characteristics of secondary atomization for gelled kerosene droplet in air crossflow,a secondary atomization platform is established and three kerosene gels are prepared with different concentrations of gellant. Atomization process of droplet is photographed under different experimental conditions（82We691,9.6×10-4Oh3.77）. Deformation,breakup mode,breakup time,shear-stripping rate and R-T wavelength of the droplet are measured and compared with kerosene droplet. Results indicate that dimensionless deformation rates of kerosene and gelled kerosene droplet are between 0.5 and 2.0. Mean dimensionless deformation rate decreases as gellant increased with increasing viscous effects. Two breakup modes are identified at present experimental conditions,and gelled kerosene droplet has the same atomization process as kerosene droplet in the same mode. Under different We numbers,the change trend of initial and total breakup time are the same for all the droplets. For different Oh numbers,initial and total breakup time of 3% gelled kerosene droplet differ the calculated values from relative literature but have a good accordance for the other three materials. Shear-stripping rate for all the droplets is improved with increasing We number. Kerosene droplet has a higher shear-stripping rate than gelled kerosene droplets when We number is less than 200. However,when continuing enhancing We number,the rates for all the droplets have similar values. R-T wavelength decreases with We number raised. Experimental R-T wavelengths of kerosene,1% and 2% gelled kerosene agree well with the theoretical values. But the theory shows an overestimation for 3% gelled kerosene.
出处
《推进技术》
EI
CAS
CSCD
北大核心
2017年第12期2658-2666,共9页
Journal of Propulsion Technology
基金
航天科技创新基金(CASC03-02)
中央高校基本科研业务费专项基金(30920140112001)
关键词
凝胶液滴
二次雾化
破碎模态
液滴变形
破碎时间
R-T不稳定波
Gelled droplet
Secondary atomization
Breakup mode
Droplet deformation
Breakuptime
R-T instability wave
