Wind Loads Simulator for Free-Running Model Ship Test

Abstract

The authors have developed a wind loads simulator (WiLS) that enables us to carry out free-running model tests for investigating wind effects on ship performance. WiLS provides a free-running model ship with simulated wind loads taking account of supposed true wind speed and direction, and instantaneous model ship speed, drift angle, and heading angle. It does not generate environmental wind but exerts forces and moment on a model ship using three pairs of duct fans. A control PC calculates time varying longitudinal and lateral wind forces and yaw moment using wind loads coefficients estimated beforehand and ship motion data, and distribute them to the three pairs of duct fans. Feedback control ensures the intended wind loads using data from load cells on which the duct fans are mounted and those from accelerometers for correcting inertia forces of the duct fans. This paper reports the concept, configuration, and control procedure of WiLS, and presents tank test data, which confirms effectiveness and usefulness of WiLS as a device in free-running model tests to evaluate ship performance at actual seas.