Investigation on Turbulence Stimulators for Full Ship Models

Abstract

In resistance tests of full ship models, the values of model resistance sometimes become inconsistent at low Froude numbers, and it becomes difficult to determine the form factors out of the resistance curves at the low Froude numbers. The reason of this inconsistency was supposed to be due to the fact that laminar boundary layers were apt to be sustained beyond the turbulence stimulators of the routine process at the Akashi Ship Model Basin. Iterative resistance tests were carried out with full ship models fitted with four kinds of turbulence stimulators shown in Fig.1. Flow visualization tests by means of dye injection and turbulence measurements with a flash type hot-film probe were employed to examine the effects of the various stimulators. The results of the investigations are summarized as follows : (1) The routine stimulator at ASMB was found insufficient for turbulence stimulation particularly with full ship models. (2) No.3 stud condition shown in Fig.1 has been found the most superior because of having a sufficient effect for stimulation and less additional resistance than No.2 stud condition.