I am writing you to ask some advice about the mooring system of the OC4 floating platform.
My desire is to run FAST with this support platform, for a water depth different from the default one (200 m).
How can I change then the mooring system (depth is 55 m for my case)?
I was thinking to keep the mooring line mass and structural properties (axial stiffness, diameter, mass per unit length), and then to find the anchor position and line unstretched length which give the same vertical force and line angle at the fairlead, that the system has for a depth of 200 m, at rest (in absence of waves and wind).
Honestly, I am not sure whether this approach is correct or not.
I am looking forward to receive your suggestions and opinions.
All the best,
I’m not sure that the change you propose would work because the pretension of a catenary mooring system is dictated by the weight of mooring system hanging in the water, which would change if you kept the mooring properties identical, changing only the line lengths, water depth, and anchor positions.
My guess is for a such a drastic change in water depth a complete redesign of the mooring system would be warranted–that is, selection of mooring line cross sections, lengths, and anchor positions to obtain the desired response characteristics and stay within the load envelope.
I want to have the extreme load envelope for the full-scale test of the wind turbine blades. How can these loads be obtained through the FAST software?
I’m not sure I really understand your question. Are you referring to IEC design load cases or something else?
Yes both IEC and DNV-GL 0376 extreme loads for full-scale test of wind turbine blade
Sorry, but I’m still not understanding. I’m not familiar with DNV-GL 0376. Are you referring to the static strength (pull) test of a standalone blade in laboratory?
I want to get a graph like the second image from FAST software
Are you trying to get the plot of “design load cases from load simulation”? This appears to be a plot of the minimum and maximum flapwise bending moment and the associated edgewise bending moment derived from various load case simulations, as well as plots of the minimum and maximum edgewise bending moment and the associated flapwise bending moment derived from various load case simulations, plotted together on the same graph. You can certainly derive such a plot via post-processing of FAST/OpenFAST results based on the extreme event table data derived from MExtremes or the like.