Abstract: Cavitation jet technology, due to its strong impact and cleaning capabilities, is widely used in cleaning and surface treatment fields. As a key component for inducing cavitation jets, the design of the cavitation nozzle is crucial. However, some researchers have focused on optimizing the central body at the axial position to improve cavitation effects, while neglecting the role of fluid near the axis. To address this issue, this study proposes a novel annular central body nozzle based on the traditional organ-pipe nozzle. The annular central body is divided into three structures: forward, reverse, and square. The variations in cavitation volume fraction, pressure, velocity, and turbulent kinetic energy are analyzed to investigate the cavitation characteristics of each new structure. Additionally, the annular central body is combined with an axial central body to further study the cavitation characteristics of the nozzle. The results show that, compared to nozzles without an annular central body, the reverse structure generates the largest cavitation area, while the square structure has the second-largest cavitation area and the highest velocity along the axis. The forward structure, due to the contraction of the jet toward the axis, reduces the overall flow velocity in the inner flow path, and the lower velocity near the wall causes a smaller low-pressure zone, leading to weaker cavitation near the wall. The inlet velocity has little impact on the shape of the cavitation cloud in the flow field but is positively correlated with the cavitation volume. Furthermore, the combination of the annular central body and the axial central body increases the cavitation cloud length, enhancing the cavitation effect behind the central body. These findings provide new theoretical support for the design and optimization of cavitation nozzles.

Key words: cavitation nozzles, phase transition model, cavitation jets, numerical simulation, surface cleaning

摘要： 空化射流由于其强大的冲击力和清洗能力，被广泛应用于清洗和表面处理等领域。作为诱发空化射流的关键部件，空化喷嘴的设计至关重要，而部分学者在提高空化效果的研究中，集中于轴线位置中心体的优化，忽略了轴线附近流体的作用。针对这一问题，本工作基于传统风琴管喷嘴提出一种新型环形中心体喷嘴。将环形中心体分成正向、反向和方形三种结构，通过分析空化体积分数、压力、速度以及湍动能等参数，考察了各种新型结构空化喷嘴的空化特性。同时还将环形中心体以及轴线位置放置的中心体搭配使用，进一步研究喷嘴的空化特性。结果表明，相较于未加装环形中心体的喷嘴，反向结构能产生最大面积的空化，方形结构空化面积仅次于反向结构且轴线上的速度最大，正向结构由于收缩至轴线的射流对内流道流体产生冲击，降低了内流道的整体流速，由于其靠近壁面的流速较低，导致低压区变小，使其壁面附近的空化效果相对较差；入口速度对空化流场中空化云的形状影响不大，但与空化体积成正相关；环形中心体搭配轴线中心体使用可以使空化云长度延长，增强了中心体后方的空化效果。本研究结果可为空化喷嘴的设计与优化提供新的理论依据。

关键词: 空化喷嘴, 相变模型, 空化射流, 数值模拟, 表面清洗