Series Experimemt of Stern Forms in Circulating Water Tunnel

Abstract

The main purposes of this paper are ; (1) to obtain the relations between stern forms with relatively simple frame lines and their viscous resistance, (2) to observe flow fields about various sterns. We chose four kinds of simple stern frame lines, named R, S. R-S and M, and their C_B and B/d were changed systematically. Experiments were made for about 60 model ships (Table1. Figs. 3and4) in circulating water tunnel having test section of L×B×d=2×1.2×0.8m. The results of resistance test are shown in Fig. 5. From the curves in Fig. 5 and an empirical formula shown below, we determined so called Form Factor "k" (Fig. 6) with Hughes basic friction line. The empirical formula is, k=k(circulating water tunnel)×const., where the constant was determined from experiments of mother model ship (N type, Fig. 1) both in towing tank and in circulating water tunnel (Fig. 2). Observations of flow fields are shown in Fig. 7. In the Figure, stream lines calculated by Dr. Junnaka's method and trailing vortices oberved by Dr. Tagori's method are also shown. The computer programme of calculating stream lines is in Table2. written in FORTRAN II.