QED Naval are pleased to welcome Thomas Nevalainen to the team. Thomas joins QED Naval from Strathclyde University where he is about to complete his Ph.D. His thesis entitled “The effect of unsteady sea conditions on tidal stream turbine loads and durability” allows QED Naval to extend its wave and tidal loading capabilities and add BEMT methods to calculating turbine loads as part of a more streamlined optimisation process for QED’s Subhub foundation structure. CFD methods can then be used to assess the finalised design.
Thomas will take over the management of access to the Hartree supercomputer which is used to improve turnaround times on large models and increase the speed of learning from weeks to days. QED Naval have access to ANSYS Fluent and X-Flow on the Hartree supercomputer. Fluent is a sophisticated CFD package that provides access to a large number of turbulence models and mesh developments such as polyhedral meshes that streamline the size of the model and improve accuracy. However, despite its sophistication it tends to be sensitive cell quality so a great deal of time is spent generating good conformant meshes both in pre and post processing results.
Thomas also takes over responsibilities for utilising the other enhanced capability using X-Flow provided by FlowHD. It allows QED Naval to reduce the pre/post processing time using Lattice Boltzman cells domain that is self-adaptive and easily controlled by the user in terms of vorticity in the model in the areas of interest. It combines this with fully transient, LES turbulent model which resolves the largest turbulence fluctuations in the flow while the smallest eddies are approximated for increased efficiency. The self-adaptive cell capability makes it much easier to conduct rigid body motions such as assessing tidal turbine performance characteristics. From the work conducted to date the tools were well validated using the Subhub performance model tank testing results and assessment of Tocardo’s T1 tidal turbine against their specified performance data.
QED Naval offer these capabilities to other marine renewable companies at competitive rates. The main advantage of this work is it can be used to determine what the design loads are on full scale structures without having to go to the expense of building a prototype. Hence, these assessments can minimise the technical and commercial risks of developing marine renewable structures and turbines.
QED Naval commissioned renewable energy consultancy, SgurrEnergy, to undertake an independent technical and commercial due diligence design review of the Subhub tidal turbine transport, installation and foundation system. It encompassed a review of analysis reports that had been produced as part of the feasibility and R&D studies supported by Scottish Enterprise. These include an analysis of all the tank testing results and the calculations of extreme loads, together with an assessment of the assumptions that have been used in scaling up to anticipated loads in larger device iterations. SgurrEnergy has also reviewed the tidal and wave loading numerical modelling reports that were based upon the tank testing campaign. This forms part of QED Naval’s detailed design process of the 1:4 scale technology demonstrator to be tested at Strangford Lough”.
The report also reviews the status of the tidal market and makes recommendations for QED Naval’s testing programme to validate the suggested performance and operation of the Subhub. These include a requirement to provide clear evidence to support the claimed reduction in CAPEX and OPEX costs compared to other transport and installation solutions, to demonstrate the potential increase in power density by accelerating the flow into the turbines, and to consider means of reducing the effects of tidal shear, veer and turbulence on the turbines installed on the Subhub.
The latest community scale version of the Subhub has now been frozen ready for build. Manufacturing outputs have been completed for the new modularised version of the Subhub. This allows the bare hull to be fabricated on the quayside and lifted into the water by a smaller, more available and lower cost crane.
After launch the newly designed modular solid ballast blocks can be easily lifted slotted into the bottom of the hull to provide the impressive stability characteristics of the Subhub during transit and installation.
The pressure cabinets to support the 3 x Tocardo T1 turbines have also been modularised to allow them to be slotted into the top of the hull once the main hull has been launched. This allows the cabinets to be quickly connected up to the generators whilst afloat. Access panels allow simple maintenance operations to be completed at sea.
Successful Installation & Retrieval Trials in Real Tidal Conditions
Recent testing of the Subhub operations model in high tidal flow conditions proved its ballast system capabilities and installation and retrieval methodology with great success. QED Naval were able to install the model on the seabed safely and in a controlled manner within minutes. The model was then secured on the seabed overnight before being recovered to the surface gracefully within an equally short time period and control.
Despite onerous wind, wave and current conditions experienced during testing, the Subhub coped admirably during the installation and retrieval trials. Scaling these extreme conditions to the prototype size, based on a 4.0m diameter turbine, would be equivalent to over 2m/s or 4 knots with a significant wave heights over 1.0m
Frontal profiles of turbine blades were added to the cross beam to simulate three turbines being installed on the Subhub; the blades acting against the current presented no issues.
QED Naval have teamed up with Offler Marine Services Group (OMSG) to provide offshore expertise with the selection of installation and recovery methods, to help de-risk and reduce cost exposure of the Subhub project and its payload of tidal turbines.
QED Naval received a real boost to their plans to reduce the costs of deployment of the commercial scale (multi MW devices) from OMSG. They received a report this week from OSMG produced by the team who have significant experience within the tidal, wave and offshore wind power industry. Steve Offler lent his weight and credibility behind the Subhub project when it was recognised that the feasibility to install Subhub in 30-60 minute time scalesandat a fraction of the typical installation costs currently influencing the industry were achievable.
Recommendations from OMSG’s report are currently being implemented into the prototype structuredesign, based on a 4.0m diameter tidal turbine, tofurther fine tune the offshoreinstallation and recoveryprocess.
Jeremy Smith, Managing Director of QED Naval said, “This is a really exciting development for QED Subhub since the basis of our design is to remove the need for complex, large and hi tech installation vessels with equally high day rates and availability issues. This report along with what we have learned from our ballasting trials at Forth Estuary Engineering are the positive indicators that significant reductions in the costs of deployment of commercial scale devices are not too far away. We are steadily moving towards offering our customers and their investors a generic deployment solution no matter what the location, environment or turbine used“.
Steve Offler, MD at OMSG said “Marine Installation costs and risks are high, QED have identified this and sought to engage installation design expertise early to ensure costs and risks are mitigated, this is an extremely important part of the development process and one that will add significant value to Subhubs future success”
QED Naval have move their main office to satisfy their growing requirements. Their new city centre location on Castle Street is within Edinburgh’s ‘golden triangle’ (EH2 3AH) and provides improved access to transport links for their customers and clients.
The new accommodation was formally part of the old Northern Rock buildings and allows us to plug straight into the excellent IT facilities and office network which was left in place. The dedicated server room also allows QED Naval to upgrade their cluster to make best use of their High Performance Computing (HPC) capabilities provided by ANSYS HPC which provides a significant boost to the performance large fluid loading (CFD) and mechanical (FEA) models.
QED Naval launched the Subhub Operational model last week at Forth Estuary Engineering’s (FEE) dock in Leith. The last few weeks has been a hive of activity finalising the setup of the ballast systems, instrumentation, and the dock access and testing arrangements.
FEE have provided outstanding support during the preparation and will to be on hand through the testing phase. The Subhub will now be put through its passes to test the stability during installation, ballast system control and installation/retrieval methods.
The Director of QED Naval was on site to witness the launch and initial testing and has stated, “A lot of hard work has gone into getting the Subhub project to this point which is a credit to the team and supporting companies. The Operations model represents a big step forward for the Subhub project de-risking the ballast system and installation/retrieval methods which is a key selling point used to reduce the cost of deployment and overall the cost of energy”.
The Subhub Operations Model continues it fit-out and setup for the testing at Forth Estuaries Engineering’s (FEE’s) dock in Leith. An essential part of that was the “weigh-in” to check against our design calculations to ensure she is correctly ballasted for her initial trials.
The operations model is based on a 1.0m tidal turbine rotor diameter. It is designed to accommodate 3 of the heaviest tidal turbines on the market. The Operations Model has been built to the same mass proportions of the prototype so its motions will be accurately modeled.
The “Operations Model” is the 3rd in a series of models with very specific objectives. It has been developed to test the ballasting system and conduct installation/retrieval trials.
QED Naval selected ANSYS Spaceclaim as their advanced CAD design tool after a review of other products on the market. Spaceclaim is a direct modeler which means any line, curve surface or solid element of the CAD geometry can be modified and updated in an instant using simple tools.
Spaceclaim integrates seamlessly with the rest of the ANSYS suite through Workbench into Fluent and Mechanical. It can import geometry from the majority of CAD formats. It is particularly good at fixing errors in geometry really quickly and intuitively by using the main pull tools. This is particularly useful for CFD fluid modelling and FEA structural analysis.
Spaceclaim provides a significant increase in performance in producing manufacturing outputs drawings which has allowed us to transfer our design to our suppliers and subcontractors quickly and easily.
Fabrication has been completed on the operational model of the Subhub at Pentland Precision Engineering allowing QED Naval to begin the pre-testing setup of the device. The Subhub looked magnificent in the Edinburgh Sun as weeks of work culminated in a device that will be tested to the limit by QED Naval. Over the next week the team at QED will be carrying out pre-testing preparations fitting extensive instrumentation and ballast systems to gain the most out of the coming testing phase.
Project team at Pentland Precision Engineering Gordon Hardman (left) Grant Middleton (centre) and Chris Scott (right).
Marine renewable engineering and design consultants