CFD Jobs Database - Job Record #15651
Job Record #15651 |
Title | Postdoc in fluid dynamics of fan blades in electric generators |
Category | PostDoc Position |
Employer | Chalmers University of Technology, Dept. M2, Div. Fluid Dynamic |
Location | Sweden, Gothenburg |
International | Yes, international applications are welcome |
Closure Date | Sunday, March 17, 2019 |
Description: |
Axial ventilation by use of axial fans was the most common cooling concept for
hydropower generators in Sweden during the 50-70’s when the main part of the
Swedish hydropower plants where built. It is still used for new produced
machines especially for high speed machines where the small diameter limits the
choice of ventilation concept. Axial fans are also common after renovation of
old machines when the rotating parts are reused. The design of the fans which is
used in the main part of hydropower generators are made by bended plates which
are welded on a fan ring or segments.
The working principle of an axial fan blade is very similar as an airplane wing
profile where a high pressure side occurs below the fan blade and a low pressure
side occurs above the fan blade. Vortex separations may occur at the low
pressure side which under some circumstances can results in vibration problem of
the fan blades (stalling). Such effects are most likely more severe under some
conditions that will more frequently be passed due to an increase in regulation
of the electric grid. Cracks and broken fan blades due to fatigue can be a
consequence of the vibration which may cause serious damages of the machine due
the fact that the fans are located close to the rotating poles and the stator
winding.
In order to prevent this kind of problems a frequency analysis of the fan blades
is carried out during the design phase. It is very important that the flow-
induced frequencies of the forces acting on the fan blades, due to e.g. vortex
separation, do not coincide with the eigenfrequency of the blades. That requires
a detailed understanding of the flow around fan blades with designs particularly
used in axially cooled hydropower generators.
Both numerical and experimental studies will be conducted in the present
project. CFD with highly resolved Large-Eddy Simulation (LES), or possibly
Detached Eddy Simulations (DES), turbulence modeling is the most suitable
technique for detailed studies of vortex separation and other unsteady
behaviour. The numerical results will primarily be validated with experimental
results in our linear cascade rig, for which the present post-doc position will
design appropriate experiments and analyse the results. The actual measurements
will be conducted in close collaboration with our experimental specialists. The
possible impact of rotation should be evaluated numerically, and possibly used
to design complementary experiments. For the structural analysis employed in the
electric generator design stage it is important to determine the time-averaged
and unsteady pressure distributions and the frequency distribution over the fan
blades. The experimental and numerical results will complement each other in the
final analysis of those and other aspects. Fluid-structure-interaction analysis
may be employed if it is considered necessary to get accurate results.
Read more at http://www.chalmers.se/en/about-chalmers/Working-at-
Chalmers/Vacancies/Pages/default.aspx?rmpage=job&rmjob=7213&rmlang=UK
|
Contact Information: |
Please mention the CFD Jobs Database, record #15651 when responding to this ad. |
Name | Håkan Nilsson |
Email | hakan.nilsson@gmail.com |
Email Application | No |
URL | http://www.chalmers.se/en/about-chalmers/Working-at-Chalmers/Vacancies/Pages/default.aspx?rmpage=job&rmjob=7213&rmlang=UK |
Record Data: |
Last Modified | 10:11:09, Monday, February 11, 2019 |
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