Abstract

The "System for Predicting the Operation of Unmanned Aerial Vehicles on Naval Platforms" (SPOVENT) project aims to determine the studies and developments necessary to obtain and characterise the data required to predict ship movements in waves in real time and, therefore, to be able to predict the optimum windows for recovering/landing UAVs. The project was developed in two phases: the objective of the first one was the identification of the available technology applicable to the prediction of the 3D vessel motions during its operation plus the determination of maximum vessel motion limits in order to carry out the capture of UAVs in safe conditions; then came the development of two algorithms to predict the movements of the vessel depending on the waves that it will encounter during its navigation. After the completion of these initial phases, the validation and evaluation of the algorithms developed is carried out, followed by the development of the SPOVENT demonstrator, implementing the algorithm with best results. To determine the algorithm which best predicts the time windows in which the UAV will be able to operate, the following evaluation and validation criteria are established: accuracy of the prediction of the operation windows, range of application, input data required for its correct operation, possibility of adaptation to different types of vessels and required calculation time. Once the algorithm to be implemented in the demonstrator has been selected, a computer application is developed that shows the user the time windows to perform these operations with adequate safety. The design of the application ensures that user intervention is minimal, considering the operating conditions on a ship, including easy-to-read indicators and easily accessible buttons. Additionally, the demonstrator will be a tool to evaluate the operational criteria (STANAG) of different missions during navigation, by means of the ship's movement variables registered by an IMU sensor

Abstract

An enhanced direct forcing immersed boundary method implemented in the open-source hydrodynamic framework REEF3D::CFD is used to simulate six-degrees-of-freedom (6DOF) motion response of a 1:30 scale point-absorber wave energy converter(WEC) under extreme wave conditions. The enhancement of the method is achieved with a new density interpolation method that removes unphysical spurious phenomena. The governing equations are solved on a staggered rectilinear grid. REEF3D::CFD uses the level set function to represent the free surface. A ray casting algorithm is employed to get inside-outside information in the vicinity of the body with the underlying Cartesian grid. The enhanced method is tested and validated based on the experimental data from the experimental wave tank campaign carried out in the Ocean and Coastal Engineering Laboratory, at Aalborg University, in Denmark.