Comparison of Flow Characteristics of Wake Regions of Single and Lined up in a Row Torpedo-Like Geometries at Uniform Flow Conditions

Abstract

In this study, the comparison of the flow characteristics in the wake of two identical torpedo-like geometries having an elliptical nose and conical stern lined up in a row with a single model for a length-diameter ratio L/D = 5 was investigated using the Particle Image Velocimetry (PIV), method in a closed-loop open water channel. The Reynolds number calculated based on the characteristic length (L = 200 mm) of the model is Re = 20x10³. The experiments were carried out under uniform flow conditions. The uniform flow velocity is 100 mm/s. The space between the two models is denoted by G. The dimensionless space ratio between the models is taken as G/L = 0.15. In comparisons, instantaneous velocity field (V), time-averaged streamline topologies <Ψ>, pointwise variations of streamwise velocity component <u/U_ꝏ>, cross-streamwise velocity contours <v/U_ꝏ>, velocity fluctuations in cross-streamwise <v_rms/U_∞> and instantaneous vorticity contours wL/U_∞ were found to be different significantly from the single-torpedo-like geometry. It has been observed that the flow separations in the torpedo-like geometry wake region at G/L = 0.15 are delayed and move toward the end of the geometry stern section. In addition, it has been observed that the rotational flow regions areas covered by the contours get smaller and approach the geometry.