Tip vortex cavitation is typically the first type of cavitation in real ship propellers due to the scale effect. To lessen or eliminate propeller cavitation noise, it is necessary to effectively identify and predict the tip vortex cavitation initiation of the propeller and run the propeller as far as possible in the “non-cavitation area.” However, for the current numerical computation, it is impossible to determine the minimum pressure at the vortex core directly and correctly, making it difficult to anticipate the cavitation initiation of the propeller tip vortex. In this paper, based on computational fluid dynamics (CFD) numerical calculations and the tip vortex model proposed by Xin [Proceedings of 2013 Ship Hydrodynamics Conference (2013), pp. 211–218], we propose a new prediction method for propeller tip vortex cavitation initiation—“the tip vortex model method.” The propeller tip vortex is solved by CFD calculation in this model, and the minimum pressure at the downstream vortex core is examined based on the tip vortex model to determine the initiation of propeller cavitation. We examine the cavitation inception using the tip vortex model method and compare it to the results obtained using the minimum pressure coefficient method and the minimum vapor volume method. It is discovered that the cavitation inception number obtained by the tip vortex model method is closer to the experimental results. Furthermore, the effects of different turbulence models and grid settings on the prediction of tip vortex cavitation initiation are investigated, providing an effective reference for the prediction of propeller tip vortex cavitation initiation.
Timber is a typical orthotropic material, of which the accurate measurement of elasticity modulus and Poisson ratio is important. In this article, the test samples are manufactured according to GB 1943-1991 and 1935-1991. An electronic testing machine is employed to add longitudinal load on samples and the longitudinal and transverse strains are measured via Wheatstone bridge. Then, the compressible elasticity modulus and Poisson ratio of Ziziphus montana wood in three directions is obtained. The results show that the elasticity modulus measured is of similar magnitude to those with similar dry density and of great importance to finite element calculation.
The cylinder for experiment has been excited by steady sinusoidal and random white noise excitation forces and the acceleration responses are measured. The frequency response functions of two excitation ways agree well. The reciprocity law and the linearity are certified by exchanging the excitation and measurement spots and increasing input voltage continuously respectively. The influence of mesh size to calculated time and precision of vacuum vibration mean square velocity and underwater vibration mean square velocity and acoustic radiation are investigated. Results show that time consumed mounts with the mesh size gets smaller, and the vibroacoustic results is less influenced at lower frequencies but much more at higher frequencies.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.