Say I’m using TurbSim in a graduate level engineering wind energy course and was wondering if anyone has any good ideas on appropriate homework problems that I can assign that make use of turbsim. My goal is to have the students (and myself) gain a better understanding of turbulence intensity, prob density functions, autocorrelation, power spectral density and integral scaling as they apply to wind. I also intend to utilize FAST later in the semester to have the students design, build and then test a rotor blade set.
I would suggest the following to use as tool to understand the characteristics of turbulent inflows using TurbSim. Ask the students to:
(1) Examing the flow characteristic differences as described by the parameters you mentioned that are generated by the different spectral models available in TurbSim; i.e. the IEC-Kaimal, IEC-Von Karman, and the SMOOTH, Wind Farm UPWIND, Wind Farm with 7D turbine spacing, Wind Farm with 10D spacing, and NWTC models with and without the coherent structures option. Do this say for a nominal hub-height wind speed of 12.5 m/s at a hub height of 85 m which is near rated for many large turbines. Repeat the exercise varying the stability (Richardson numbers including -1, -.25, 0, +0.05, +0.25, 1) and varying the shear exponent ( 0.1, 0.143 (1/7), 0.2 (IEC), 0.5, 1.0). It is possible that some of these combinations may not work on some of the models because they generate non-physical flowfields but that should be up to the students to determine and document as to what may be the cause.
(2) If there is time, repeat above sequence for hub-height wind speeds 6, 8, 16, and 20 m/s.
(3) Compare the IEC-Kaimal & IEC-Von Karman models with a 12.5 m/s hub-height wind speed and the remainder as specified by the IEC with the KHTEST function.
(4) Repeat (3) Using the FAST model of the WindPACT 1.5MW virtual turbine. Examine the simulated loads and compare the impact of inflow turbulence characteristics. Use Marshall Buhl’s CRUNCH or GPP post-processors to analyze the results
I think this will give your students (and perhaps yourself) a great pedagogical experience in the role of inflow turbulence on wind turbines.