The aerodynamic noise and the wake flow field in a cooling fan under actual operating conditions are studied with and without winglets on the fan blades. In order to understand the influence of the winglet, the aerodynamic noise and the wake velocity distribution are measured. The results indicated that overall noise level decreased and the noise spectrum was changed in a low frequency range when the winglet was installed. It was found from the flow visualization and PIV measurement that the influence of the winglet appeared in the traces of the tip vortices and the magnitude of vorticity was reduced in the near wake region, which suggest the observed reduction in aerodynamic noise.
SummaryChoosing four Panamax-size bulk carriers and four Aframax-size oil tankers designed by different criteria in different times, reliability analysis has been performed to compare their safety levels from the viewpoint of ultimate hull girder strength in longitudinal bending. For evaluation of the ultimate hull girder strength and its sensitivities with respect to design parameters, a series of progressive collapse analysis is performed applying the Smith's Method. On the other hand, applying the nonlinear Strip Method, time-dependent nonlinear ship motion analysis is performed to estimate wave-induced bending moment. On the basis of the obtained time history of wave bending moment, statistic characteristics of the extreme bending moment is estimated. Utilising the calculated results, reliability index and failure probability are calculated applying the First Order Reliability Method (FORM). Investigating into the obtained results, it has been found that in general the safety level becomes higher with the times depending on the design criteria.
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.