Maurizio Collu

Publications

• Marine Vessel (Trim Control Mechanism)

  M Collu, M H Patel

  Ref. No: GB2472266A

  Year: 01/2011

  Download

• A Multi-Criteria Decision Making Method to Compare Available Support Structures for Offshore Wind Turbines

  M Collu, A J Kolios, A Chahardehi, F Brennan, M H Patel

  European Wind Energy Conference and Exhibition 2010, Warsaw, Poland; 04/2010

  Wind farms provide a serious source of clean, renewable energy and will play an essential role in meeting the EU's target for 20% renewable energy by 2020. The number of wind power installations is rapidly increasing, and more than 40% of all new electricity generation capacity added to the Euro... [more] Wind farms provide a serious source of clean, renewable energy and will play an essential role in meeting the EU's target for 20% renewable energy by 2020. The number of wind power installations is rapidly increasing, and more than 40% of all new electricity generation capacity added to the European grid in 2007 was wind [1]; offshore wind farms are an essential part of this development and certain EU territories e.g. the UK, can not met the agreed 2020 targets without significant expansion of offshore wind power. A report on offshore wind construction by the British Wind Energy Association (BWEA) suggests that 9GW of wind power capacity will be built in the UK by 2015, with wind overtaking nuclear in terms of installed capacity in the next four to five years [2]. One of the challenging aspects of offshore wind farms is the foundation and the support structures required to cope with the sometimes severe environmental conditions at sea. This paper provides a systematic methodology for classification and evaluation of the different available support structures for offshore wind turbines. This paper provides a methodology for the systematic classification and evaluation of the different available support structures for offshore wind turbines.

• A comparative preliminary design study between a fixed and a floating support structure for a 5 MW offshore wind turbine, in North Sea

  M Collu, A J Kolios, A Chahardehi, F Brennan

  MARINE & OFFSHORE RENEWABLE ENERGY - Developments in Wind, Wave, Tidal and Current Technology, London, UK; 04/2010

  It is widely recognized that offshore wind farms are a key factor to fulfill renewable energy targets set in Europe : for example, in UK, the target is to have 15% of final energy consumption coming from renewable sources by 2020. In general, with respect to onshore, offshore wind farms have several... [more] It is widely recognized that offshore wind farms are a key factor to fulfill renewable energy targets set in Europe : for example, in UK, the target is to have 15% of final energy consumption coming from renewable sources by 2020. In general, with respect to onshore, offshore wind farms have several advantages, like the availability of larger areas and a higher energy potential, due to greater wind velocities and lower turbulence levels. On the other hand, one of the major drawback is the higher cost of the marine foundations, together with their higher installation cost. Interestingly, the offshore oil & gas industry already managed to fulfill a similar opportunity: as drilling in deeper waters became both technically feasible and economically advantageous, several kind of offshore support structures for oil rigs have been developed. Starting from this experience, the present work focus on the preliminary design of two support structures suitable for medium to deep waters (depth > 30-40 m): a fixed structure, a jacket, and a waterplane- ballast stabilized floating structure. The two structures are designed for the same 5 MW offshore wind turbine , and the design methodology is presented step by step. As a result, a technical and economical comparison analysis is presented.

  Download

• Aerodynamic lift forces on multihulled marine vehicles

  Williams, A G W, M Collu, M H Patel

  Trans RINA (and also Int J Maritime Eng., Apr-Jun 2010). 01/2010; 152:A-41, A-50.

  The need for high-speed high-payload craft has led to considerable efforts within the marine transport industry towards a vehicle capable of bridging the gap between conventional ships and aircraft. One such concept uses the forward motion of the craft to create aerodynamic lift forces on a wing-lik... [more] The need for high-speed high-payload craft has led to considerable efforts within the marine transport industry towards a vehicle capable of bridging the gap between conventional ships and aircraft. One such concept uses the forward motion of the craft to create aerodynamic lift forces on a wing-like superstructure and hence, reduce the displacement and skin friction. This paper addresses the specific aerodynamic design of multihull for optimal lift production and shows that significant efficiency can be achieved through careful shaping of a ducted hull, with lift-to-drag ratios of nearly 50 for a complete aerodynamic hull configuration. Further analysis is carried out using a hybrid vehicle stability model to determine the effect of such aerodynamic alleviation on a theoretical planing hull. It is found that the resistance can be halved for a fifty metre, three hundred tonne vehicle with aerodynamic alleviation travelling at 70 knots. Results are presented for a candidate vessel.

• Reliability of floating foundation concepts for vertical axis wind turbines

  A J Kolios, M Collu, F P Brennan

  The 11th International Symposium on Practical Design of Ships and Other Floating Structures – PRADS 2010, Rio De Janeiro, Brazil; 01/2010

  Offshore wind turbines are developing at a rapid pace. By far the most common turbine configuration is the HAWT (Horizontal Axis Wind Turbine) and development of these machines is largely centered about drive train and blade issues with some work concerning foundations/supporting structures. Several... [more] Offshore wind turbines are developing at a rapid pace. By far the most common turbine configuration is the HAWT (Horizontal Axis Wind Turbine) and development of these machines is largely centered about drive train and blade issues with some work concerning foundations/supporting structures. Several teams around the world are developing floating supporting structures for HAWT, mainly for deep water deployment. This paper describes the development of a floating support structure for Vertical Axis Wind Turbines (VAWT) with particular focus on structural/survival risk and reliability. Unlike Oil & Gas floating support structures, wind turbine floaters need to resist significant dynamic wind and machine loading in addition to wave excitation. Coupling of dynamic response modes can be difficult and consideration of these within a reliability framework presents several challenges. The paper describes a simplified procedure for risk assessment so that potential areas of concern can be quickly identified and uses a VAWT to illustrate the methods and reasoning employed.

• The Longitudinal Static Stability of an Aerodynamically Alleviated Marine Vehicle, a Mathematical Model

  M Collu, MH Patel, F Trarieux

  Proceedings A of the Royal Society. 12/2009; At the moment published online.

  An assessment of the relative speeds and payload capacities of airborne and waterborne vehicles highlights a gap that can be usefully filled by a new vehicle concept, utilizing both hydrodynamic and aerodynamic forces. A high-speed marine vehicle equipped with aerodynamic surfaces is one such concep... [more] An assessment of the relative speeds and payload capacities of airborne and waterborne vehicles highlights a gap that can be usefully filled by a new vehicle concept, utilizing both hydrodynamic and aerodynamic forces. A high-speed marine vehicle equipped with aerodynamic surfaces is one such concept. In 1904, Bryan & Williams (Bryan & Williams 1904 Proc. R. Soc. Lond. 73, 100–116 (doi:10.1098/rspl.1904.0017)) published an— article on the longitudinal dynamics of aerial gliders, and this approach remains the foundation of all the mathematical models studying the dynamics of airborne vehicles. In 1932, Perring & Glauert (Perring & Glauert 1932 Reports and Memoranda no. 1493) presented a mathematical approach to study the dynamics of seaplanes experiencing the planing effect. From this work, planing theory has developed. The authors propose a unified mathematical model to study the longitudinal stability of a high-speed planing marine vehicle with aerodynamic surfaces. A kinematics framework is developed. Then, taking into account the aerodynamic, hydrostatic and hydrodynamic forces, the full equations of motion, using a small perturbation assumption, are derived and solved specifically for this concept. This technique reveals a new static stability criterion that can be used to characterize the longitudinal stability of high-speed planing vehicles with aerodynamic surfaces.

• AERODYNAMICALLY ALLEVIATED MARINE VEHICLES (AAMV): DEVELOPMENT OF A MATHEMATICAL FRAMEWORK TO DESIGN HIGH SPEED MARINE VEHICLES WITH AERODYNAMIC SURFACES

  M Collu, Williams, A G W, M H Patel, F Trarieux

  High Performance Marine Vessels 2009, Shanghai, China; 04/2009

  In the last few decades, interest in high speed marine vehicles, both in civil and military marine transportation, has motivated the marine engineering community to develop new configurations [1]. Among these, the ‘aerodynamic alleviation concept’ [2] consists of using one or more aerodynamic surfac... [more] In the last few decades, interest in high speed marine vehicles, both in civil and military marine transportation, has motivated the marine engineering community to develop new configurations [1]. Among these, the ‘aerodynamic alleviation concept’ [2] consists of using one or more aerodynamic surfaces to alleviate the weight of marine vehicles. The advantages are: lower hydrodynamic drag better damping of heave and pitch accelerations. At Cranfield University a research programme to study AAMV started five years ago. Firstly, an AAMV equilibrium attitude model has been developed and implemented in MATLAB [3]. Similar to the Savitsky model for planing craft [4], this model is able to estimate the attitude of a given AAMV. Secondly, the vehicle stability has been studied by developing a specific system of equations of motion, using a small disturbances assumption [5]. This article presents a possible AAMV configuration that illustrates the potential of such configurations and how mathematical models can be used as design tools. 1. MEYER, J. R., CLARK, D. J., ELLSWORTH, W. M., ‘The Quest for Speed at Sea’, Naval Surface Center, Carderock Division, Technical Digest, 2004 2. DOCTORS, L. J., ‘Analysis of the Efficiency of an Ekranocat: A Very High Speed Catamaran with Aerodynamic Alleviation’, RINA, International Conference on Wing in Ground Effect Craft (WIGs ’97), 1997 3. COLLU, M., PATEL, M. H., TRARIEUX, F., ‘A Mathematical Model to Analyze the Static Stability of Hybrid (Aero-Hydrodynamically supported) Vehicles’, Royal Institution of Naval Architects - 8th Symposium on High Speed Marine Vehicles (HSMV 08), pp. 148- 161, 2008 4. SAVITSKY, D., ‘Hydrodynamic Design of Planing Hulls’, Journal of Marine Technology, Vol. 1, pp. 71- 95, 1964 5. COLLU, M., PATEL, M. H., TRARIEUX, F., ‘A Unified Mathematical Model for High Speed Hybrid (Air and Water-borne) Vehicles’, 2nd International Conference on Marine Research and Transportation (ICMRT 07), 2007

• Dynamics of Marine Vehicles with Aerodynamic Surfaces

  Maurizio Collu

  03/2009

  Degree: PhD

  Supervisor: Patel, M H

• High Speed Marine Vehicles with Aerodynamic Surfaces: Development of a Dynamic Model for a Novel Configuration

  M Collu, M Patel, F Trarieux

  Cranfield Multi Strand Conference, Cranfield University, Cranfield, UK; 05/2008

  A research programme on high speed marine vehicles fitted with aerodynamic surfaces started in Cranfield University in 2005. One of the configurations analyzed is a high speed prismatic planing hull with one or more aerodynamic surfaces; it is called a hybrid vehicle (HV). Two mathematical models ha... [more] A research programme on high speed marine vehicles fitted with aerodynamic surfaces started in Cranfield University in 2005. One of the configurations analyzed is a high speed prismatic planing hull with one or more aerodynamic surfaces; it is called a hybrid vehicle (HV). Two mathematical models have been developed for the dynamic behavior which is a combination of the very different behaviors of aircraft and ships. The first model estimates the equilibrium attitude of the HV at a certain speed. A parametric analysis for the influence of the configuration on the performance of the HV has been conducted (1). With the second model, the authors propose a set of ordinary differential equations of motion, derived in the frame of small-disturbance stability theory which has been used to investigate the longitudinal dynamic stability of the HV (2). Ref. (1) and (2) present a complete description of the mathematical models, while this article summarizes the methodology adopted to develop these dynamic models and gives a brief summary of the results. (1). COLLU, M., PATEL, M. H., TRARIEUX, F., A Mathematical Model to analyze the Static Stability of Hybrid (Aerohydrodynamically supported) vehicles., 8th Symposium on High Speed Marine Vehicles 2008 (HSMV08), Naples, Italy, 2008. (2). COLLU, M., PATEL, M. H., TRARIEUX, F., A Unified Mathematical Model for High Speed Hybrid (Air and Waterborne) Vehicles., 2nd International Conference on Marine Research and Transportation, 2007.

• A Mathematical Model to Analyze the Static Stability of Hybrid (Aero-Hydrodynamically Supported) Vehicles

  M Collu, M Patel, F Trarieux

  8th Symposium on High Speed Marine Vehicles, Naples, Italy; 05/2008

  Among the new concepts developed for high speed marine vehicles over the last two decades [1], the ‘aerodynamic alleviation’ [2] approach consists in using an aerodynamic surface to ‘alleviate’ the weight sustained by the hydrodynamic lift. Such vehicle experiences aerodynamic and hydrodynamic force... [more] Among the new concepts developed for high speed marine vehicles over the last two decades [1], the ‘aerodynamic alleviation’ [2] approach consists in using an aerodynamic surface to ‘alleviate’ the weight sustained by the hydrodynamic lift. Such vehicle experiences aerodynamic and hydrodynamic forces of the same order of magnitude, therefore the dynamic models developed for airborne and waterborne vehicles are not suitable. Considering a vehicle having a high-speed prismatic planing hull and one or more aerodynamic surfaces, the authors propose two mathematical methods. The first one calculates the equilibrium attitude of the vehicle at a given speed and its numerical implementation has been used to undertake a parametric analysis of the influence of some configuration characteristics on performances. The second method analyzes the static stability of the HV. Starting from the dynamic analysis previously proposed by the authors [3], the characteristic polynomial of the HV dynamics is derived and a static stability criterion is proposed. [1]. MEYER, J. R., CLARK, D. J., ELLSWORTH, W. M., ‘The Quest for Speed at Sea’, Naval Surface Center, Carderock Division, Technical Digest, 2004 [2]. DOCTORS, L. J., ‘Analysis of the Efficiency of an Ekranocat: A Very High Speed Catamaran with Aerodynamic Alleviation’, RINA, International Conference on Wing in Ground Effect Craft (WIGs ’97), 1997 [3] COLLU, M., PATEL, M. H., TRARIEUX, F., ‘A Unified Mathematical Model for High Speed Hybrid (Air and Water-borne) Vehicles’, 2nd International Conference on Marine Research and Transportation (ICMRT 07), 2007

• A Unified Mathematical Model for High Speed Hybrid (Air and Water-borne) Vehicles

  M Collu, M Patel, F Trarieux

  2nd International Conference on Marine Research and Transportation, Ischia (Naples), Italy; 06/2007

  During the last two decades, the interest in civil and military high speed marine vehicles has lead to several new configurations. Some of them exploit a combination of aerodynamic and hydrodynamic forces to sustain part of the weight of the craft, leading to a hybrid vehicle (HV). This paper focuse... [more] During the last two decades, the interest in civil and military high speed marine vehicles has lead to several new configurations. Some of them exploit a combination of aerodynamic and hydrodynamic forces to sustain part of the weight of the craft, leading to a hybrid vehicle (HV). This paper focuses on the study of the longitudinal high-speed dynamics of such hybrid vehicles. Since airborne and waterborne vehicles belong to two distinct areas of research, they have been investigated with a rather different approach. The authors propose a unified mathematical model to represent the kinematics suitable for hybrid vehicles, including a detailed analysis of the aerodynamic and hydrodynamic forces acting on the vehicle. Then a set of ordinary differential equations of motion is derived in the frame of small-disturbance stability theory, leading to the Cauchy standard form. An illustrative example of a hybrid vehicle (KUDU II) is analyzed with the proposed method.

• Development of a mathematical model of combustion for a novel solid propellant for space propulsion systems

  Maurizio Collu

  12/2004

  Degree: Master Degree in Aerospace Engineering

  Supervisor: Luciano Galfetti