Cavitation is the determining mechanism for the atomization of high-viscosity liquid.

Piezoelectric atomization is becoming mainstream in the field of inhalation therapy due to its significant advantages. With the rapid development of high-viscosity gene therapy drugs, the demand for piezoelectric atomization devices is increasing. However, conventional piezoelectric atomizers with a single-dimensional energy supply are unable to provide the energy required to atomize high-viscosity liquids. To address this problem, our team has designed a flow tube internal cavitation atomizer (FTICA). This study focuses on dissecting the atomization mechanism of FTICA. In contrast to the widely supported capillary wave hypothesis, our study provides evidence in favor of the cavitation hypothesis, proving that cavitation is the key to atomizing high-viscosity liquids with FTICA. In order to prove that the cavitation is the key to atomizing in the structure of FTICA, the performance of atomization is experimented after changing the cavitation conditions by heating and stirring of the liquids.

Piezoelectric atomization of liquids with dynamic viscosities up to 175 cP at room temperature.

Piezoelectric atomization has been applied in the field of respiratory medicine delivery and chemistry. However, the wider application of this technique is limited by the viscosity of the liquid. High-viscosity liquid atomization has great potential for applications in aerospace, medicine, solid-state batteries and engines, but the actual development of atomization is behind expectations. In this study, instead of the traditional model of single-dimensional vibration as a power supply, we propose a novel atomization mechanism that uses two coupled vibrations to induce micro-amplitude elliptical motion of the particles on the surface of the liquid carrier, which produces a similar effect as localized traveling waves to push the liquid forward and induce cavitation to achieve atomization. To achieve this, a flow tube internal cavitation atomizer (FTICA) consisting of a vibration source, a connecting block and a liquid carrier is designed. The prototype can atomize liquids with dynamic viscosities up to 175 cP at room temperature with a driving frequency of 507 kHz and a voltage of 85 V. The maximum atomization rate in the experiment is 56.35 mg/min, and the average atomized particle diameter is 10 µm. Vibration models for the three parts of the proposed FTICA are established, and the vibration characteristics and atomization mechanism of the prototype were verified using the vibration displacement measurement experiment and the spectroscopic experiment. This study offers new possibilities for transpulmonary inhalation therapy, engine fuel supply, solid-state battery processing and other areas where high-viscosity microparticle atomization is needed.

Design and Analysis of a Cardioid Flow Tube Valveless Piezoelectric Pump for Medical Applications.

Piezoelectric pumps play an important role in modern medical technology. To improve the flow rate of valveless piezoelectric pumps with flow tube structures and promote the miniaturization and integration of their designs, a cardioid flow tube valveless piezoelectric pump (CFTVPP) is proposed in this study. The symmetric dual-bend tube design of CFTVPP holds great potential in applications such as fluid mixing and heat dissipation systems. The structure and working principle of the CFTVPP are analyzed, and flow resistance and velocity equations are established. Furthermore, the flow characteristics of the cardioid flow tube (CFT) are investigated through computational fluid dynamics, and the output performance of valveless piezoelectric pumps with different bend radii is studied. Experimental results demonstrate that CFTVPP exhibits the pumping effect, with a maximum vibration amplitude of 182.5 µm (at 22 Hz, 100 V) and a maximum output flow rate of 5.69 mL/min (at 25 Hz, 100 V). The results indicate that a smaller bend radius of the converging bend leads to a higher output flow rate, while the performance of valveless piezoelectric pumps with different diverging bends shows insignificant differences. The CFTVPP offers advantages such as a high output flow rate, low cost, small size for easy integration, and ease of manufacturing.

Design and Experimental Study of a Tetragonal Rotor Pump Based on Wankel Geometry.

Wankel pump designs have not been fully established, with existing designs limited to bicornous rotor pumps and triangular rotor pumps. Here, on the basis of Wankel geometry, we present a tetragonal rotor pump with a three-lobe epicycloid and its conjugate envelope as chamber and rotor profile. First, the design method and basic working principle of the pump are introduced. Four groups of prototypes with different shape factors were manufactured, and their flow and pressure characteristics were experimentally studied. Numerical study showed that the flow rate irregularity of the pump is lower than that of existing Wankel pumps. Finally, the feasibility the pump for mixing applications was verified by a flow field observation experiment. The work in this paper provides a new type of rotary displacement pump design, representing an study of reverse application of a Wankel engine structure.