As part of the National Rotor Testbed (NRT), new capability has been incorporated into the Sandia developed wind-turbine free-wake vortex code, CACTUS. Previously, only revolution-averaged velocity data could be output from the simulation. Now, the vortex elements and the induced velocity can be output as time series, enabling the calculation of turbulence statistics. This new capability gives better insight into the wake stability for rotors being designed in support of the NRT project.
In addition, turbulence statistics are being compared to an actuator line large eddy simulation (AL-LES). These comparisons will highlight the differences between the codes in captured flow physics and ultimately, the effects of these differences on future rotor designs. An example of a CACTUS-generated wake simulation is presented in the figure. A more detailed description of the system is here past newsletters