R & D Activities
NAVANTIA-CEHIPAR
R&D JOINT ACTIVITIES OF NAVANTIA, CEHIPAR AND SISTEMAR
In 1997 a strong co-operation among Astilleros Españoles, CEHIPAR and SISTEMAR started with the R&D project entitled “OPTIMIZATION OF SHIP PROPULSION BY MEANS OF INNOVATIVE SOLUTIONS INCLUDING TIP PLATED PROPELLERS” (1997-1999). At such time IZAR and NAVANTIA were not yet created.
One of the goals obtained was to develop a procedure to extrapolate at full scale model test results with CLT propeller models. The necessary empirical know-how was deduced in such a way that nowadays CEHIPAR and SISTEMAR can extrapolate at full scale model test results with CLT propellers with the same degree of accuracy than in the extrapolation at full scale of model test results with conventional propellers.
The extrapolation procedure developed is almost the same than the ITTC’78 extrapolation procedure for conventional propellers but with the introduction of some special correlation coefficients on the scaling of the CLT propeller open water curves. The procedure was presented at The Motor Ship Conference 2005 (“Scale effects in model tests with CLT propellers”. 27th Motor Ship Marine Propulsion Conference. Bilbao, January 2005).
Another important goal of this R&D effort has been to stand out the scale effect existing in the epsilon coefficient, that defines the balance between the overpressure and underpressure forces acting on the blades of a CLT propeller.
At full scale the water flow is fully turbulent and there si not separation of the laminar boundary layer and hence the water leaves the cascade of profiles with direction tangent to the mean lines of the profile. However, the laminar flow separation produced at model field affects not only to the viscous forces acting on the blades (leading to higher CD values) but also to the pressure distribution on the blades and hence to the lift forces (leading to lower CL values).
Because of the above, scale effects not only on viscous forces but also on lift forces have to be taken into account to correct the influence of the laminar separation produced at model field with CLT propellers.
Due to the higher CD values of model field and the lower CL values, the epsilon coefficient at model field is higher than at full scale and therefore the propeller open water efficiency is lower at model field than at full scale and furthermore, the cavitation performance at model field is worse than at full scale.
A new R&D project was carried out during 2001-2003 among IZAR, CEHIPAR and SISTEMAR: “Research on the cavitation performance of CLT propellers, on the influence of new types of propeller blades annular sections and the potential application to POD’s”, with the following objectives:
- To develop a new procedure to conduct cavitation test with CLT propellers, in order to assure that inside of cavitation tunnel a phenomenon similar to the one corresponding to full scale be developed.
- To study the advantages that may be derived from the use in the design of the CLT propellers of a new type of mean line developed by SISTEMAR, looking for a maximum increase of the momentum that the cascades of the propeller blades annular section gives to the water.
- To compare the pressure pulses induced on the hull by a conventional propeller with those induced by a standard CLT propeller and a new CLT propeller designed using the new mean line.
With the new type of mean line the following improvements were confirmed:
- A reduction of the underpressure existing on the suction side of the CLT propellers/blades and also, a higher decrease of the volume of sheet cavitation, and consequently the levels of hull pressure pulses.
- An increase of the overpressure existing on the pressure side of the CLT propeller/blades that leads to an increase in the propeller open water efficiency of the actual CLT propellers.
A new R&D project was carried out during 2003-2005 among IZAR, CEHIPAR and SISTEMAR, with the participation also of ACCIONA TRASMEDITERRANEA and TSI, with the aim to validate at full scale the achievements of the previous programs: “Research on the performance of high loaded propellers for high speed conventional ferries”.
CLT blades were installed on the ferry “Fortuny” replacing the existing conventional blades. The ship speed in ideal trials conditions is close to 24 kn, and there were not significant problems of vibrations operating under combinator mode; however, operating under constant rpm mode in off-design with pitch settings below the design pitch the noise and vibration levels were very high becoming non acceptable in certain spaces.
When the pitch decreases and the rpm remains constant the radial loading distribution of the conventional blades decreases even more at the tip and negative loads are achieved at the upper sections of the blade. As a consequence, face cavitation is developed at the pressure side of the conventional blade and the noise and vibration levels increase because of the higher excitation of the pressure pulses. The situation is not the same with the CLT blades because there is not face cavitation at lower pitch settings.
Both from the cavitation tunnel and the full scale measurements it has been deduced that the non acceptable noise and vibration levels are produced as a consequence of the broad band energy spectra detected in the case of the conventional blades that does not exist in the case of CLT blades. This phenomena explains the vibration problems existing with the conventional blades.
The random excitation or broad band between the excitation harmonics corresponding to 2 and 3xBPF facilitates the appearing of local resonance phenomena that are clearly predominant for all the spectra both of noise and vibrations all along the vessel. The structural noise of low frequency is very difficult to reduce with conventional acoustic dampers and because of that the noise and vibration levels increase for lower pitch settings with conventional blades.
Comparative full scale trials were performed before and after the installation of the CLT blades. Results of these trials have shown that the fuel consumption has been reduced for all the range of ship speeds after the installation of the CLT blades and also that the non acceptable noise and vibration levels produced with the conventional blades operating at constant rpm with pitch settings below the design pitch have been totally eliminated.
SUPERPROP
EUROPEAN FP6 EU R&D PROJECT “SUPERPROP”
The consortium has been formed by:
- CEHINAV-ETSIN-UPM (Spain)
- PESCANOVA (Spain)
- C.N. P. FREIRE (Spain)
- SISTEMAR (Spain)
- INSEAN (Italy)
- FUNDILUSA (Portugal)
- VTT (Finland)
- MARINTEK (Norway)
The test cases for the study have been the trawler “ILA” from PESCANOVA and the Italian tug “VAL” from OCEAN. SISTEMAR designed a CLT propeller for the trawler and the improvement obtained in the efficiency over the former conventional propeller has been in the range of 5%.
The project is focussed in obtaining the optimum method for updating old ship propellers from technological and economic points of view, in order to improve the fuel consumption rates and reduce the maintenance costs. The objectives of SUPERPROP are:
- Most fixed pitch propellers installed on fishing vessels are Marin B-series. Results from methods for recovering shaft speed to the whole B-series calculated using CFD codes and model tests will be obtained, as well as cavitation predictions.
- Development of an economic strategy to predict the profitability of propulsion updating in old fleets.
- Improvement of the knowledge about the state of the art in old ships propulsion and their ageing.
- Thrust the knowledge in correlation methods to extrapolate results obtained from model testing to full scale.
- To apply CFD codes to predict propeller behaviour, to collate computational and model testing results and to estimate prediction accuracy of both methods.
The main innovative features of SUPERPROP are:
- To study economic profitability of old fleets and the saving that could be reached in fuel consumption, machining maintaining and contaminant gases emission.
- To use extensively full scale measurement for improving propulsion efficiency.
- Development of a strategy to reuse old propellers with low cost by means of machining or deforming to readjust it to new working conditions.
- Scientific and Technological Prospects :
- SUPERPROP addresses important research aspects in the areas of economic impact of ageing effect in old ships, marine propeller design, CFD modelling of propeller flow and scaling of propeller model test performance data to full-scale predictions. All these research achievements will be transferred into design tools, procedures and databases that can directly be applied in practical propeller design.
SILENV
EUROPEAN FP7 EU R&D PROJECT “SILENV”
SISTEMAR participates as subcontractor of CEHIPAR in the 4 years EU R&D project SILENV with the objective to study the reduction of noise and vibrations in ships with the goal to create a green label of quiet ships.
The consortium is formed up by : TSI, CEHIPAR, ACCIONA TRASMEDITERRANEA, UNIVERSIDAD DE CATALUÑA, BUREAU VERITAS, CETENA, INSEAN, SSPA, VTT, TNO, DCNS, VARNA UNIVERSITY, GLASGOW UNIVERSITY and GENOA UNIVERSITY.
SISTEMAR has performed a new design of CLT blades for the ferry “Fortuny”, already installed with CLT blades, introducing several new items in the design as for instance the use of a new developed mean line of the annular sections. Model tests already performed at CEHIPAR with the new CLT blades design have shown improvements both in efficiency and also in the level of pressure pulses.
TRIPOD
EUROPEAN FP7 EU R&D PROJECT “TRIPOD”
Within the Framework Program 7th of the EU, call FP7-SST-2010-RTD-1, the 30 months duration project “TRIple Energy Saving by Use of CRP, CLT and PODded Propulsion” (TRIPOD) has been approved and started on 1st November 2010. The main objective of this project is the development and validation of a new propulsion concept for improved energy efficiency of ships through the advance combination of three existing propulsion technologies: podded propulsion (POD), CLT tip loaded end plate propellers and counter-rotating propeller (CRP) principle.
The members of the consortium that develop TRIPOD project are ABB and VTT from Finland, AP MOLLER MAERSK from Denmark and CEHIPAR, CINTRANAVAL-DEFCAR and SISTEMAR from Spain. VTT is coordinating the project.
The two companies that have been leading the research and development of POD (ABB) and CLT (SISTEMAR) technologies during the past years are responsible for the design of the alternative propulsive system.
Numerical calculations are being performed by VTT while model tests are being carried out by CEHIPAR. Both institutions have already a long experience on projects involving CLT propellers.
The consulting company CINTRANAVAL-DEFCAR takes care of the ship design modifications and optimisation and will evaluate the technical feasibility of the innovative CRP-CLT-POD propulsion system.
The economical evaluation of the system will be performed by AP MOLLER-MAERSK, one of the largest ship operators in the world who has supplied the reference ship and operational data: 8.500 TEU’s container vessel “Gudrun Maersk”.
All along the project different propulsion configurations will be analysed. For the reference hull without pod with a conventional propeller an alternative CLT propeller has been designed and compared to the reference propulsion system. In a second stage, the reference hull has been modified by removing the rudder and all the relating parts and a pod system has been installed in a CRP configuration. Different driving propeller combinations (conventional and CLT) will be analysed and compared to the reference propulsion system.
Once finished both numerical analysis and model tests for different propulsion arrangements, a concept validation will be performed with the objective to estimate energy savings and noise reduction on the CRP-CLT-POD concept as compared to the conventional propulsion. A feasibility study for the introduction of the novel propulsion concept on new ship designs and for retrofitting on existing vessels from technical point of view will be performed as well as an economic analysis of the viability of the new propulsion concept for retrofitting and for new ship designs.
Large energy savings and consequently, CO2, SOx and NOx emission reductions as well as environmentally harmful noise mitigation are expected with the innovative CRP-CLT-POD propulsion system. Elaborated procedures on how to determine yearly fuel savings and emission reductions based on the vessels operational profiles will be applied and then the cost-benefit will be assessed through a total cost of ownership analysis.
AQUO
EUROPEAN FP7 EU R&D PROJECT “AQUO”
The project AQUO (Achieve QUiter Oceans by shipping noise footprint reduction) has the main goal of suppling to the EU a tool to manage the submarine acoustic contamination enabling to adopt decisions on the maritime traffic regulation and also to provide guidelines for the reduction of the footprint of ships.
The project is coordinated by the French shipyard DCNS and the members of the consortium are BUREAU VERITAS (France), SSPA (Sweden), UNIVERSITY OF GENOA (Italy), UNIVERSITY OF STRATHCLYDE (United Kingdom), QUIET-OCEANS (France), SHIP DESIGN AND RESEARCH CENTER (Poland), IMARES (Netherlands), FOI (Sweden), CESA (Belgium), CEHIPAR (Spain), UPC CATALUÑA (Spain) and TSI (Spain).
SISTEMAR participates as subcontractor of CEHIPAR.
ONR-NICOP
NICOP-ONR R&D PROJECT “Energy Efficient Contracted-Loaded Tip (CLT) Propellers for Naval Ships”
SISTEMAR has received a grant from the OFFICE OF NAVAL RESEARCH of the U.S. NAVY (ONR) to perform a two years R&D project on CLT propellers within the framework of the NICOP (National International Cooperative Opportunities in Science and Technology Program).
There are renewed worldwide interests in the energy-efficient contracted loaded tip (CLT) propellers due to steadily increasing oil cost and uncertain future of the oil supply. Reducing fuel consumption through increased propeller efficiency is an obvious means to reduce life cycle cost of ships. Propellers are designed to satisfy a host of requirements, including efficiency, cavitation inception, thrust breakdown, radiated noise, hull vibration, structural integrity, weight, and maintainability. Improving one performance metric, such as propeller efficiency, typically must be traded off against one or more other metrics, such as cavitation and noise.
One propeller concept which shows promise in increasing efficiency without sacrificing cavitation performance is the contracted loaded tip (CLT) propeller. The application of CLT propellers for naval ships would pose major challenges to the propeller designers due to different performance requirements. For example, naval ships may have more stringent cavitation performance requirements.
The objectives of this NICOP project are two-fold: (1) develop and demonstrate CLT-type propellers for naval ships that would improve efficiency by the comparable range demonstrated for commercial ships (i.e., 4-8%) over conventional open propellers without sacrificing cavitation performance, and (2) develop a scaling method for full-scale CLT propeller performance based on model-scale testing in the water tunnel.
Through collaborative efforts, SISTEMAR and NSWCCD will develop a set of design requirements for a new propeller design for a naval ship. These requirements will address tip vortex, suction side and root cavitation inception, required thrust coefficient, diameter, and pressure pulse severity. Once these requirements are set and agreed upon, engineers at SISTEMAR will develop a CLT design which meets these requirements using their standard practices while engineers at NSWCCD will do the same, using standard USN practices for propeller design.
SISTEMAR will act as project coordinator and will subcontract the work performed at CEHIPAR; both propeller models will be manufactured and tested in the variable pressure cavitation tunnel at CEHIPAR. Computations will be made both by NSWCCD and SISTEMAR/CEHIPAR for the two propeller designs using RANS methods at model and full-scale Reynolds numbers. Computational results obtained by two organizations will be compared in detail to understand the physics of tip flow of CLT-type propellers and the scale effects.
The US Navy has never built the CLT-type propellers. The NICOP efforts will provide the US Navy with an energy-efficient propeller concept for their consideration for retrofit or for new construction.
Contact
SISTEMAR S.A.
Social address:
Plaza de las Salesas 7, 2ª izda.
28004 Madrid, España.
Postal address:
Alvaro Caballero 28,
28023 El Plantío, Madrid, España.
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