We study here effects of nozzle layout on the droplet ejection of a micro atomizer, which was fabricated with the arrayed nozzles by the MEMS technology and actuated by a piezoelectric disc. A theoretical model was fi...We study here effects of nozzle layout on the droplet ejection of a micro atomizer, which was fabricated with the arrayed nozzles by the MEMS technology and actuated by a piezoelectric disc. A theoretical model was first built for this piezoelectric-liquid-structure coupling system to characterize the acoustic wave propagation in the liquid chamber, which determined the droplet formation out of nozzles. The modal analysis was carried out numerically to predict resonant frequencies and simulate the corresponding pressure wave field. By comparing the amplitude contours of pressure wave on the liquid-solid interface at nozzle inlets with the designed nozzle layout, behaviors of the device under different vibration modes can be predicted. Experimentally, an impedance analyzer was used to measure the resonant frequencies of the system. Three types of atomizers with different nozzle layouts were fabricated for measuring the effect of nozzle distribution on the ejection performance. The visualization experiment of droplet generation was carried out and volume flow rates of these devices were measured. The good agreement between the experiment and the prediction proved that only the increase of nozzles may not enhance the droplet generation and a design of nozzle distribution from a view-point of frequency is necessary for a resonant related atomizer.展开更多
飞翼布局因其独特的翼身融合的气动外形,大大提高了飞行器的有效升力面积,外形优化问题和布局优化对于此类构型气动性能的提升同样重要。本文为解决飞翼布局无人机气动外形优化问题,建立了高效的参数化建模方法,实现了适应复杂外形的几...飞翼布局因其独特的翼身融合的气动外形,大大提高了飞行器的有效升力面积,外形优化问题和布局优化对于此类构型气动性能的提升同样重要。本文为解决飞翼布局无人机气动外形优化问题,建立了高效的参数化建模方法,实现了适应复杂外形的几何参数化变形控制,将基于梯度的优化算法、离散伴随方法与基于RANS(Reynolds average Navier-Stokes)方程的计算流体力学(Computational fluid dynamics,CFD)方法相结合,对飞翼布局无人机完成了气动外形的优化减阻设计,升阻比提升了7.17%。优化结果表明,在满足约束要求的前提下,基于上述技术的气动优化设计方法对翼身融合类构型具有良好的适应性,能有效改善无人机的气动性能。展开更多
基金the National Natural Science Foundation of China(50405001).
文摘We study here effects of nozzle layout on the droplet ejection of a micro atomizer, which was fabricated with the arrayed nozzles by the MEMS technology and actuated by a piezoelectric disc. A theoretical model was first built for this piezoelectric-liquid-structure coupling system to characterize the acoustic wave propagation in the liquid chamber, which determined the droplet formation out of nozzles. The modal analysis was carried out numerically to predict resonant frequencies and simulate the corresponding pressure wave field. By comparing the amplitude contours of pressure wave on the liquid-solid interface at nozzle inlets with the designed nozzle layout, behaviors of the device under different vibration modes can be predicted. Experimentally, an impedance analyzer was used to measure the resonant frequencies of the system. Three types of atomizers with different nozzle layouts were fabricated for measuring the effect of nozzle distribution on the ejection performance. The visualization experiment of droplet generation was carried out and volume flow rates of these devices were measured. The good agreement between the experiment and the prediction proved that only the increase of nozzles may not enhance the droplet generation and a design of nozzle distribution from a view-point of frequency is necessary for a resonant related atomizer.
基金supported in part by the National Natural Science Foundation of China(No.11972180)。
文摘飞翼布局因其独特的翼身融合的气动外形,大大提高了飞行器的有效升力面积,外形优化问题和布局优化对于此类构型气动性能的提升同样重要。本文为解决飞翼布局无人机气动外形优化问题,建立了高效的参数化建模方法,实现了适应复杂外形的几何参数化变形控制,将基于梯度的优化算法、离散伴随方法与基于RANS(Reynolds average Navier-Stokes)方程的计算流体力学(Computational fluid dynamics,CFD)方法相结合,对飞翼布局无人机完成了气动外形的优化减阻设计,升阻比提升了7.17%。优化结果表明,在满足约束要求的前提下,基于上述技术的气动优化设计方法对翼身融合类构型具有良好的适应性,能有效改善无人机的气动性能。
