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MHK Turbine Simulation for Floating Platform
Dear Forum Members,
I understand that QBlade currently has the capability of modelling Marine Hydrokinetic (MHK) turbines with good accuracy.
Upon reading the documentation, it appears that one of the steps required for simulation of MHK turbines is setting the Turbine Environment to Onshore Installation. Could someone clarify if analysis of MHK Turbine on Floating Platform is possible at current version of QBlade?
Otherwise, if such feature is not available, would someone be so kind as to share some idea on how simulation of MHK Turbine on floating platform could be performed on QBlade?
Hi Andhi,
there are various MHK turbine concepts, each with distinct requirements for the modeling approach.
Some MHK systems are fixed to the seabed, while others are suspended from floating platforms or vessels. The choice of modeling approach depends on the focus of your investigation.
The method recommended in the documentation involves modeling the entire environment as “submerged in water.” This is done by adjusting the fluid density and related parameters to those of salt water. In this configuration, only the MHK device is modeled – excluding any floating platform it may be attached to. A key advantage of this approach is the ability to define a turbulent inflow, which directly affects the turbine’s performance.
Alternatively, it is possible to model a floating platform with an MHK turbine attached to its bottom. This setup allows for the simulation of the combined dynamics of the platform, its mooring system, and the turbine. However, the main limitation of this approach is that it currently does not support the definition of a turbulent inflow for the MHK rotor. In this case, the rotor is influenced solely by the velocities induced by ocean currents and waves.
Best regards,
David
Hi David,
Thank you for your insightful reply.
Could you advise how a floating platform with submerged MHK turbine could be simulated in QBlade?
Is this achieved by simply inputting negative tower height in the structural input file? I attempted this in one of the sample projects (NREL_5MW_ITI_Barge_v1.0) and saw that the tower structure appears to be missing from the 3D view as shown in the attachments. I am hoping this is purely cosmetic issue.
Warmest regards,
Andhi
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Hi Andhi,
the orientation of the tower, attached to a substructure, is controlled by the orientation of the transition piece (TP).
https://docs.qblade.org/src/user/turbine/substructure.html#the-transition-piece
To orient the tower along the negative z-axis, you can apply a 180° rotation around the x-axis.
If a negative or zero value is specified for the tower height in the structural main file (as you have done), a rigid constraint is applied between the rotor-nacelle assembly (RNA) and the transition piece (TP). In this case, the tower is not modeled as a flexible beam, which is why you’re observing the current behavior in your example.
BR,
David
Hi David,
Thank you for your guidance. As you suggested, the model appears to be correct with the rotated transition piece.
Could you comment on the ability of QBlade to simulate multiple tidal turbines (up to 3 turbines on a single floater) and whether the interactions between the multiple tidal turbines would be accurately captured?
Thanks & regards,
Andhi
Hi Andhi,
great to hear that things are wokring out.
Multiple (tidal) turbines can be simulated using the Enterprise Edition of QBlade (QBlade-EE).
This feature also accounts for the mutual wake and induction interactions between the turbines!
BR,
David
Hi David,
For multiple tidal turbines and a floating platform, would mutual wake and induction interactions between the turbines be accounted for? Are there any demo models available for tidal turbine?
Regards
Salem
Hi Salem,
QBlade-EE is capable of accounting for mutual wake interactions between turbines, whether they are land-based or marine hydrokinetic (MHK) systems.
Currently, there is no default MHK turbine model included with QBlade. However, if you – or anyone else in the community- have created a model, we’d be happy to host it in the Downloads section for others to use.
Best regards,
David
