Correlated forcing with an active grid to control turbulence

Abstract eng:
Research on classical turbulence theory has benefited from the use of active grids that allow a wider range of flow conditions to be generated than their passive counterparts [1]. We used a new type of active grid with 129 independently rotating paddles to imprint different correlations into wind tunnel turbulence. The grid’s control over the RMS fluctuation velocity and integral length scale allowed the turbulence Reynolds number Re; to be held constant and isotropy to be controlled. We then imposed correlations into the otherwise random motions of the paddles through convolution with kernels of different shape. At constant Res, the velocity correlation functions collapsed into different families based on kernel shape when scaled by the integral length scale, regardless of flow anisotropy. This suggested that the active grid could change the structures in the flow. The exceptional degree of control over flow properties offered by these methods could allow hypotheses about the influence of large-scale structure on the various properties of turbulence to be tested more precisely and extensively.

• Export as: BibTeX | MARC | MARCXML | DC | EndNote | NLM | RefWorks
• Add to your basket