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针对后燃期柴油机颗粒物的碰撞过程,结合气溶胶颗粒的受力分析和基于弹性形变力、范德华力的非完全弹性碰撞运动方程,探讨了等径颗粒平面非完全弹性碰撞过程的两个特征-压缩、恢复和影响压缩恢复的主要特征参数.进一步研究了入射角、碰撞频率、压缩距离、恢复系数和凝并效率等特征参数相互之间的关系及其在碰撞过程中的作用.研究结果表明,任意粒径下,随着压缩过程的进行,范德华力均增强;对于相同粒径颗粒,在压缩过程中,弹性形变力始终大于范德华力,且两者差距逐渐增大.颗粒粒径分散性越大,颗粒间碰撞频率越大.15,45 nm颗粒分别与50 nm颗粒碰撞频率的比值约为1.9倍.等粒径颗粒碰撞过程中,初始相对速度保持不变时,入射角增大,压缩距离增大,对心碰撞时,压缩距离最宽;相同入射角下,压缩距离随着初始相对速度的增加而逐渐增大.随着恢复系数的增大,临界速度逐渐减小,凝并效率呈逐渐减小趋势.当恢复系数等于0.026时,凝并效率约为50.05%,能够实现较高效的碰撞和较快地促进颗粒凝并,当恢复系数大于0.063时,凝并效率接近于零,极大部分颗粒碰撞之后发生分离,阻碍了颗粒凝并.
Combining with the analysis of the aerosol particles and the van der Waals forces’ incomplete elastic collision equation of motion, the two characteristics of the non-complete elastic collision of equal-diameter particles are discussed. Compression, recovery and influence of compression and restoration.The relationship between the characteristic parameters of incident angle, collision frequency, compression distance, recovery coefficient and coagulation efficiency and their role in the collision process are further studied.The results show that , The van der Waals forces are enhanced with the compression process at any particle size. For the same particle size, the elastic deformation force is always greater than the Van der Waal’s force during compression, and the gap between the two is gradually increased. Particle size dispersion The larger the collision frequency between the particles, the ratio of collision frequency of the 15 and 45 nm particles to the 50 nm particles is about 1.9 times, and the incident angle increases when the initial relative velocity remains unchanged during the particle collision of the same particle size, The compression distance increases and the center of gravity collides with the widest compression distance. With the same incident angle, the compression distance gradually increases with the initial relative velocity. With the recovery coefficient , The critical speed decreases gradually, and the coagulation efficiency decreases gradually.When the recovery coefficient is equal to 0.026, the coagulation efficiency is about 50.05%, which can achieve more efficient collisions and promote the coagulation of particles faster When the recovery coefficient is more than 0.063, the condensing efficiency is close to zero, and the separation of most of the particles after the collision hinder the condensation of the particles.