Doktorgradsstipendiat i offshore teknologi

The University of Stavanger invites applications for a doctorate scholarship in Offshore Technology at Department of Mechanics, Construction and Material Technology, Faculty of Science and Technology.

This is a trainee position that will give promising researchers an opportunity for academic development leading to a doctoral degree.

Appointment is for three years. The position is vacant from November 1, 2017.

Project title: ?Impact of refined metocean conditions on the offshore wind turbine loads and wind energy production". (Description below)

The position is funded by Ministry of Education and Research.

Applicants must have a strong academic background with a five-year master degree within civil engineering, mechanical engineering or marine engineering, preferably recently, or possess corresponding qualifications which could provide a basis for successfully completing a doctorate. Both the grade for the master's thesis and the weighted average grade of the master's degree must individually be equivalent to or better than a B grade.

The candidate is further required to have:
?A solid knowledge within structural dynamics of offshore structures.
?Developed skills in structural modelling.
?A good understanding of environmental loads in the offshore marine environment.

Furthermore it is an advantage:
?To have knowledge and experience of using Matlab.
?Experience using aero-hydro-servo-elastic structural models of wind turbines such HAWC2, SIMA, and FAST.

In evaluating the applicants, emhasis will be placed on their potential for research in the field. The appointee must be able to work independently and as a member of a team, be creative and innovative.

The research fellow must have a good command of both oral and written English.

The resulting PhD degree will qualify for research and teaching positions at University level.

The appointee will be based at the University of Stavanger, with the exception of a stay abroad at a relevant centre of research.

The research fellow is salaried according to the State Salary Code, l.pl 17.515, code 1017, LR 20, of NOK 436 900 per annum.

The position provides for automatic membership in the Norwegian Public Service Pension Fund, which guarantees favourable retirement benefits. Members may also apply for home investment loans at favourable interest rates.

Project description and further information about the position can be obtained from Associate Professor Dr. Charlotte Obhrai, telephone +47 51832164, email charlotte.obhrai@uis.no.

Information about the appointment procedures can be obtained from Senior HR Consultant Kathrine Molde, telephone +47 51831744, email kathrine.molde@uis.no.

The University is committed to a policy of equal opportunity in its employment practices. The University currently employs few female Research Fellows within this academic field and women ev men) are therefore particularly encouraged to apply.

Please register your application in an electronic form on jobbnorge.no. Relevant education and experience must be registered on the form. Certificates/diplomas, references, list of publications and other documentation that you consider relevant, should be submitted as attachments to the application as separate files. If the attachments exceed 30 MB alltogether, they will have to be compressed before uploading.

Project description:
Representative models of the environmental actions are of prime importance for the assessment of fatigue and extreme loads on an offshore wind turbine, as well as the wind energy production. The present study investigates the sensitivity of the dynamic loading of the large floating offshore wind turbines (FOWT) to different turbulence models provided in the current standards, as well as the turbulence characteristics deduced from the state-of-the-art measurement data of the marine atmospheric boundary layer. Yaw motions and mooring line tensions of a wind turbine on a spar buoy support have been found to be highly sensitive to the spatial characteristics of the turbulence applied over the rotor area. This variation in spatial distribution of turbulence especially in the lateral direction will be more significant for larger rotor sizes and floating wind concepts. The current models given in the standards have not been validated for lateral coherence of turbulence or for non-neutral conditions which we see more frequently offshore. If the design of large offshore wind turbines is to be optimized in the future, it is therefore essential that uncertainty due to turbulence modelling of the free wind and the wakes be reduced.

Current wind turbine standards allow for two different approaches to model the free wind field used for engineering estimates: The Mann turbulence model and the Kaimal wind spectra combined with a coherence function. The point wind spectra generated, using the recommended parameters, are similar, but there is a difference in the spatial distribution of the turbulence, especially at larger separation distances. As the offshore wind turbines continue to increase in rotor size, it is getting more important to model correctly the spatial distribution across the rotor area in order to calculate the extreme response and the fatigue damage. The dynamics of a floating offshore wind turbine (FOWT) is very different from a bottom fixed wind turbine and the low frequency wind coherence is especially important for the mooring line response of a FOWT, as well as the tower top yaw moment. Another factor significant for the turbulence characterization is the heat flux between the sea surface and the air. Offshore measurements indicate that the neutral conditions, considered in standards, are far from dominant. For non-neutral stability conditions, the buoyancy effects modify the turbulence structure, with the largest impact at lower frequencies. Beside the heat fluxes, other aspects of the sea-air interaction, such as e.g. different alignment of the swell waves and wind, may also modify the wind characteristics provided for land-based wind turbines.

The state-of-the-art measurement data on the marine atmospheric boundary layer acquired during NORCOWEs OBLEX measurement campaign will provide new insight into boundary layer stability and turbulence in offshore conditions. This unique data will be used to validate the turbulence models currently given in the standards and potentially provide new parameters that are valid for the offshore marine boundary layer. Aero-hydro-servo-elastic simulations will be performed to investigate the sensitivity of extreme and fatigue loading for fixed large rotor wind turbines (6MW and above) to variations in wind turbulence modelling. An extensive parametric study will also investigate impact of variations in water depth, mooring, and rotor size when using optimized and standard turbulence models.