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Job Record #15408
TitlePostdoctoral position in fluid dynamics of hydropower transient
CategoryPostDoc Position
EmployerChalmers university of technology
LocationSweden, Västra Götaland, Göteborg
InternationalYes, international applications are welcome
Closure DateSunday, November 18, 2018
Project background
Due to the new intermittent electric energy sources, hydropower is forced to 
run more and more at off-design conditions and to regulate the operating 
conditions. This causes flow instabilities with pressure fluctuations, and 
load variations that may deteriorate the machine. We have previously assessed 
state-of-the-art unsteady turbulence modeling (URANS, PANS, hybrid models and 
LES) for the use in hydro power applications under steady operating 
conditions. We have shown that it is possible to accurately predict the 
unsteady flow features under such conditions. The next step is to include the 
transients when continuously regulating the electric grid, when changing from 
one operating condition to another, during start-up/shut-down, or at a sudden 
load rejection. Another situation is when the turbines are running at speed 
no-load, ready to connect to the electric grid at very short notice. Numerical 
simulations of such situations require further research on turbulence 
modeling, wall functions, and coupling to the entire hydraulic system. In most 
cases the transients involve changes in blade angles that must be taken into 
account. That requires developments in mesh generation, mesh morphing, special 
treatment of small gaps, mapping of intermediate results, etc.

The numerical results will help gaining new knowledge on the flow physics 
during unsteady flow and transients in hydraulic turbines. The unsteady forces 
on the machine may be predicted and their origin may be understood. Such 
knowledge is beneficial for an expanded knowledge of the rotor dynamics of the 
machines. It is increasingly important to investigate the dynamic loads and 
transient response of new, refurbished and existing turbines and its impact on 
the rotating system which often results in strong vibrations with increased 
wear and decreased lifetime as consequence. Eventually, a coupling between 
rotor dynamic models and efficient unsteady flow modeling may be accomplished. 
With increasing demands on turbine flexibility the parameters that lead to 
damage from vibrations and dynamic load variations need to be investigated. To 
answer these questions new and improved computational tools are needed.

Special notes regarding the project
It should be recognized by anyone applying for the position that this is 
applied research, which to a very large extent depends on methods that are 
needed for the feasibility of the studies. Those methods need to be developed 
during the initial part of the project. There are already some implementations 
available, but they are far from ready to just use for the present 
application. Once those methods are working for the present kind of 
applications the project opens up for more detailed studies of the turbulent 
flow. Still, such simulations will be very challenging, not the least due to 
inherent practical problems related to mesh rotation and deformation.

Major responsibilities
Develop, in OpenFOAM, the required methods that are needed to study transients 
in hydro turbines. That particularly/initially involves the simultaneous mesh 
deformation due to guide vanes that change their angle at the same time as a 
part of the computatinal domain is rotating. Once the methods are working 
efficiently they should be used to do in-depth studies of the turbulent flow 
features encountered during transient operation of hydraulic turbines.

Your major responsibility as postdoc is to perform your own research in a 
research group. The position may also include teaching on undergraduate and 
master's levels as well as supervising master's and/or PhD students to a 
certain extent. Another important aspect involves collaboration within 
academia and with society at large. The position is meritorious for future 
research duties within academia as well as industry/the public sector.

Full text ad:
Contact Information:
Please mention the CFD Jobs Database, record #15408 when responding to this ad.
NameProfessor Håkan Nilsson
Email ApplicationNo
Record Data:
Last Modified06:53:46, Monday, October 22, 2018

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