The ultrasonic spray technology is studied by the method of theoretical derivation,CFD simulation,spray particle diameter detection and analysis,and experimental analysis. And the ultrasonic spray process for the coating of vascular stent is also optimized. Firstly,the ultrasonic atomization physical model is established and the equation of atomization particle diameter is derived. Secondly,the ultrasonic atomization process is simulated by the CFD method,and shows three atomization patterns:incomplete atomization pattern,critical atomization pattern and jet atomization pattern. The critical amplitude and power equation for ultrasonic atomization is derived. Thirdly,experiment is conducted to study the influence of parameters including power,gas pressure,and surface tension. The results show that the spray is stable though few particles are likely to collide each other during spray moving,and the droplet diameter is about 10-m. The Rosin-Rammler distribution equation for ultrasonic spray is created,and the uniform index number is between 7.11 and 11.48. The uniformity of spray particle diameter,the efficiency of adjustment and the energy consumption are better than traditional spray technology. Lastly,the ultrasonic spray process parameters for stent coating are optimized to eliminate the common defects and obtain fine coating.
According to the equivalent circuit model(ECM),finite element model(FEM) and physical experiment,the LIDEP force induced by the spatial variations of the phase of AC electric fields produced by the bright and dark regions on the photoconductive layer was demonstrated.Besides,the phenomenon of the light-induced electro-rotation(LIER) caused by the light-induced rotating electric field was confirmed numerically and experimentally for the first time.It may be helpful to go out of the dilemma that only the dipole moment model,based on the effect of light-induced partial potentials,can be used for LIDEP theoretical calculation currently.Through the FEM simulation and the electro-rotating experiment of yeast cells,it was found that the direction of yeast's LIER is relevant to the distance between its location and the edge of optical electrode,and the spin velocity of LIER is inversely proportional to that distance.Nevertheless,the LIER torques in the three-electrode mode show a non-uniform distribution where the LIDEP forces are harmful for a particle spinning stably around a fixed axis.Moreover,a four-electrode double-layer mode was proposed for the first time and the finite element simulation results agreed with the expected design,suggesting a new way for the dielectric spectrum measurement based on LIER.
