This week, we would like to highlight the launch of the latest edition of the Royal Institution of Naval Architects’ International Journal of Maritime Engineering (IJME). A long-standing quarterly journal, the IJME provides a forum for the reporting and discussion on technical and scientific issues associated with the design and construction of commercial marine vessels.
The IJME is published four times a year and is available on subscription to members, and non-members.
This newest edition features sixteen articles written by maritime experts from around the world and we’d like to take this opportunity to highlight three abstracts from this fascinating title.
For more information on this title, please click here.
Comparison of Experimental Towing Test and CFD Analysis of a Bare Hull Model Submarine on the Surface by Thu Han Tun, Ye Thet Htun and Aung Khaing Min
In designing submarines, hull form selection, resistance, and powering are key aspects. The bare hull form of a submarine can be considered according to five parameters. Surface resistance is important should it be necessary to operate at relatively high Froude Numbers. Due to the complex nature of the flow around the hull, model experiments are still the most reliable approach to determining surface resistance. CFD simulations enable surface condition analysis using FINEMarine. The towing mechanism must be taken into account and so this was designed to fix the pitch motion and measure the hydrodynamic forces. This paper outlines the towing method, comparing the model test and the CFD results, as well as providing a comparison of wave formation from the towing test and the CFD results. The results show that resistance increased significantly above a model speed of 1.4 m/s. Furthermore, above this speed, as the resistance of the model rose, the downforce gradually decreased.
Leader Follower Formation Control for Underwater Transportation Using Multiple Autonomous Underwater Vehicles by F U Rehman, E Anderlini and G Thomas
The successful ability to conduct underwater transportation using multiple autonomous underwater vehicles (AUVs) is important for the commercial sector to undertake precise underwater installations on large modules, whilst for the military sector it has the added advantage of improved secrecy for clandestine operations. The technical requirements are the stability of the payload and internal collision avoidance while keeping track of the desired trajectory considering the underwater effects. Here, a leader-follower formation control strategy was developed and implemented on the transportation system of AUVs. PID controllers were used for the vehicles and a linear feedback controller for maintaining the formation. A Kalman Filter (KF) was designed to estimate the full state of the leader under disturbance, noise and limited sensor readings. The results demonstrate that though the technical requirements are met, the thrust oscillations under disturbance and noise produce the undesired heading angles.
Air-Wake Prediction Based Air-Vehicle Recovery Aids by M R Belmont, J Christmas, B Ferrier, J D Duncan and J Duncan
This report demonstrates the capability of the forward prediction of the properties of the arriving wind at a vessel for time intervals adequate to significantly aid in the recovery of a wide range of air vehicles onto vessels. For craft with flight decks sited in the fore part of the vessel it is adequate to simply predict the arriving wind. For the more difficult task of recovery to stern areas behind superstructure it is also necessary to predict either the explicit properties of the turbulent air-wake or else to predict some quality measure for the aid of recovery under the prevailing conditions. The approach is able to relate the trends in the short-term statistical properties of fluctuating airflow over the flight deck to the trends in the predicted arriving wind.