Offshore Renewable Energy Engineering

An analytical model founded on geometric and potential energy principles for kink band deformation in laminated composite struts is presented. It is adapted from an earlier successful study on confined layered structures that was formulated to model kink band formation in the folding of geological layers. This study's principal aim was to explore the underlying mechanisms governing the kinking response of flat, laminated components comprising unidirectional composite laminae. A pilot parametric study indicates that the key features of the mechanical response are captured well and that quantitative comparisons with experiments presented in the literature are highly encouraging.

With the recent third round of site allocations for offshore wind farms in extended UK waters, new challenges for efficient operation and maintenance require new solutions to be provided for technician and equipment transfer out to 200 nm from shore. Based on the ongoing work at Cranfield University, a representative methodology for the design of an innovative Aerodynamically Alleviated Marine Vehicle (AAMV) is demonstrated. This process builds upon previous work including theoretical and experimental models, culminating with the summary of a preliminary design for a vessel of similar capability.

Utilising aerodynamic efficiencies of wing-in-ground effect (WIG) craft, it is shown how a vessel can be equipped with lifting surfaces in order to alleviate the weight of the vehicle, leading to a lower effective displacement, drag and required power. The design spiral of conventional marine craft is modified to include the relevant considerations to equilibrate the aerodynamic forces and moments. Some areas of current and future work are discussed, with experimental results presented.

The issue of the longitudinal stability of a WIG vehicle has been a very critical design factor since the first experimental WIG vehicle has been built. A series of studies had been performed and focused on the longitudinal stability analysis. However, most studies focused on the longitudinal stability of WIG vehicle in cruise phase, and less is available on the longitudinal static stability requirement of WIG vehicle when hydrodynamics are considered: WIG vehicle usually take off from water. The present work focuses on stability requirement for longitudinal motion from taking off to landing. The model of dynamics for a WIG vehicle was developed taking into account the aerodynamic, hydro-static and hydrodynamic forces, and then was analyzed. Following with the longitudinal static stability analysis, effect of hydrofoil was discussed. Locations of CG, aerodynamic center in pitch, aerodynamic center in height and hydrodyna-mic center in heave were illustrated for a stabilized WIG vehicle. The present work will further improve the longitudinal static stability theory for WIG vehicle.

As high performance marine vessels with improved performance characteristics are being requested by international governments and commercial operators, the Aerodynamically Alleviated Marine Vehicle (AAMV) provides a solution that combines typical speeds of rotary-wing and light fixed-wing aircraft with payload and loitering ability found in current high speed craft. The innovative AAMV hybrid aero-marine platform utilises an alternative implementation of wing-in-ground effect (WIG), a proven technology with a fascinating history of high speed marine operation.

Based on the ongoing research at Cranfield University, a representative methodology for the design of an AAMV is presented, building upon previous work including theoretical models and experimental programmes. Utilising aerodynamic ground effect efficiencies, it is shown how a vessel can be equipped with lifting surfaces that alleviate the weight of the vehicle, leading to a lower effective displacement, drag and required power. The design spiral of a conventional marine craft is modified to include the relevant considerations to equilibrate the applied aerodynamic forces and moments. A representative design is compared to existing marine and aircraft, indicating favourable performance and powering requirements.

The AAMV architecture can be applied across a range of traditional maritime applications, both military and commercial, advancing functionality and expanding the performance envelope of maritime craft.