Last modified: 2012-09-12
Abstract
This paper presents the ongoing experimental and numerical investigations on the hydrodynamic performance of a high-speed catamaran model. This catamaran is a Delft model 372, designed and already tested at the Technical University of Delft; the main features are reported in Figure 1. The work has been done in the framework of a NICOP collaboration project between the Istituto Nazionale per Studi ed Esperienze di Architettura Navale (CNR-INSEAN) and the Iowa Institute of Hydraulic Research (IIHR). The focus is on the characterization of the hydrodynamic behavior of the catamaran advancing in steady drift by means of a combined experimental and numerical activities. In particular, the aim of the present study is two-fold: to investigate the effects of drift angle on the flow field of a multi-hull vessel, with emphasis on the strong vortical structures generated along the keel of each demi-hull and to provide a valuable data base for CFD benchmarking.
To these aims, experimental Stereo-PIV measurements have been provided for different drift angles and on several cross planes; velocity measurements have been acquired in the region between the demi-hulls, as well as on the external region of the leeward hull by using the CNR-INSEAN underwater stereo PIV system [1], Figure 2. In addition, resistance, lateral force and yaw moment have been measured.
A numerical simulation campaign have been carried out at the same test conditions of the velocity measurements. Numerical simulations have been conducted using an home-developed code, χnavis [2], [3]. Preliminary simulations have been already performed on a grid not refined enough to capture the vortical structure detached from the hull surface. Nevertheless, from these simulations a rough idea of the main features of the flow field around the catamaran advancing in steady drift can be observed in Figure 3.