幂律流体撞击射流破碎机理的实验

Experiment on breakup mechanism of impinging jet of power-law liquid

通过自行研制的撞击射流系统,采用高速摄像技术,对4种不同卡波姆质量分数剪切变稀的卡波姆凝胶非牛顿幂律流体在不同射流条件下撞击液膜的破碎模式、喷雾锥角、破碎长度进行实验与分析.结果表明:不同流变特性的幂律流体出现的破碎模式不同,黏度越高,破碎模式越复杂;4种卡波姆凝胶在韦伯数为8 000左右时,达到完全发展模式,并在韦伯数为8 000左右时表现出相似的破碎特性;随着韦伯数的增大,喷雾锥角逐渐增大并趋于稳定,稳定值小于撞击角度,当卡波姆质量分数增大时,最大喷雾锥角逐渐减小,最终收敛于60°;随着韦伯数的增大,4种卡波姆凝胶的破碎长度先小幅变大然后减小,理论结果与实验结果整体趋势相似.

High-speed photography technology was used to investigate four kinds of shear-thinning Carbopol gel non-Newtonian power-law fluids with different Carbopol mass fractions by self-developed impinging jet system,the breakup pattern,spray cone angle and breakup length of liquid sheet of impinging jet were experimented and analyzed under different jet conditions.Results show that power-law fluids with different rheological properties have different breakup pattern,the higher viscosity means the more complex breakup pattern,when Weber number is about 8 000,four kinds of Carbopol gel achieve to fully developed pattern,and show the similar breakup pattern;as Weber number increases,the spray cone angle increases gradually and tends to be a stable value less than the impinging angle.with increasing of the Carbopol mass fraction,the biggest spray cone angle decreases,eventually converging to 60°,the breakup length slightly increases first and then decreases of four kinds of Carbopol gel,but the theoretical results agree well with the experimental results in trend.