This paper investigated the influence of both deflector angle u03B81 and cutting teeth arrangement angle u03B82 on the aeration performance of a cyclone aerator by using the CFD-PBM coupling model. The aeration performance of the cyclone aerator is evaluated by the proposed bubble breakage rate u03B7. Specifically, five different u03B81 values (30u00B0, 45u00B0, 60u00B0, 75u00B0, and 90u00B0) and five different u03B82 values (6u00B0, 12u00B0, 18u00B0, 24u00B0, and 30u00B0) are selected. Thus, two factors with five levels result in 25 simulation cases. Meanwhile, two-factor variance analysis is performed with SPSS software; as a result, both the intersubject factor and the results of the intersubject effect testing are analyzed. The simulation results show that the cyclone aerator has a maximum u03B7 in the cases of u03B81 = 90u00B0 and u03B82 = 30u00B0. Furthermore, u03B7 of the optimal cyclone aerator structure model with u03B81 = 90u00B0 and u03B82 = 30u00B0 is increased by 12.5% compared with that of the original model. To verify the correctness of the simulated results, clear water aeration and oxygenation experiments were performed by analyzing KLas and SOTR. The experimental results show that compared with the original model, the KLas of the optimal cyclone aerator structure model is increased by 27.1%, while the SOTR of the optimal cyclone aerator structure model is increased by 27.7%. Additionally, after using ImageJ software to deal with the experimental images, it is clear that the optimized cyclone aerator has smaller and denser bubbles. Therefore, the aeration performance of the cyclone aerator can be largely improved in the cases of the optimal u03B81 = 90u00B0 and u03B82 = 30u00B0.
Pebble-bed high-temperature gas-cooled reactors (HTGRs) generate micron-sized graphite dust particles during their operation. These dust particles are deposited on the inner surface of the reactor’s primary loop and could become resuspended by the gas flow in the event of a breach, increasing the risk of radioactive dispersion. Therefore, studying the resuspension behavior of graphite dust particles is important for the safety of HTGRs. During the process of graphite dust resuspension, the particle-particle, particle-wall, and particle-gas flow interactions play decisive roles that are closely related to the particle shape and the structure of particle deposition. In this study, atomic force microscopy is used to investigate the interaction forces between particles and the particle-wall interface. Based on adhesion force data, numerical simulations of particle resuspension are carried out using the discrete element method, and the resuspension process is studied for the case of multilayer deposition structures. The results indicate that the particle-wall adhesion force is greater than the particle-particle adhesion force. The deposition structures formed by nonspherical rod-like particles are significantly larger than those formed by spherical particles. During particle resuspension, the particles move in a rolling regime, and particle clusters deform, stretch, break, and become suspended under the influence of near-wall shear flows, leaving a wake region at the trailing end of the particle cluster. With an increase in the particle deposition height, the resuspension rate rises, and rod-like particles generally exhibit higher resuspension rates than spherical and ellipsoidal particles.
Helium–oxygen mixtures (HeliOx) have been proposed to enhance aerosol drug delivery by reducing airflow turbulence and facilitating deeper penetration of medications into the respiratory tract. However, previous studies on HeliOx efficacy have yielded mixed results, often limited by unrealistic anatomical models and steady-state assumptions, and focus on restricted sections of the airway. This study aims to address these limitations by investigating the transport and deposition of pharmaceutical aerosols in HeliOx compared to atmospheric air using a realistic, computed tomography-based nose-to-lung respiratory tract model that extends from a face mask to the 13th generation of tracheobronchial airways. Experimentally measured, dynamic breathing profiles were incorporated to simulate realistic inhalation conditions. Pharmaceutical aerosols with diameters ranging from 1 to 100 µm were released under two conditions: ambient air and HeliOx. Computational fluid–particle dynamics simulations were performed to model and visualize the transport and deposition patterns of aerosols throughout the respiratory tract during inhalation. The simulation results indicate that HeliOx promotes more steady airflow with reduced turbulence, facilitating a deeper delivery of drug aerosols compared to ambient air. Specifically, HeliOx reduced turbulence intensity in the nasal cavity, larynx, and upper trachea regions, and enhanced aerosol penetration to the lower respiratory tract, increasing the deposition fraction in the deeper lung regions. These findings suggest that utilizing HeliOx as a carrier gas can improve deep lung-targeted drug delivery, potentially enhancing therapeutic outcomes for pulmonary diseases.
