Numerical investigation of the unsteadiness of a fan tip-leakage vortex

Jérôme Boudet (1)

1 LMFA - Laboratoire de Mecanique des Fluides et d'Acoustique

The movement of the tip-leakage vortex in a fan flow is investigated, from data of an existing zonal large-eddy simulation. A methodology is presented to analyze the motion of the vortex, using low-pass filtering and integral-based vortex identification functions. This approach permits to focus on the largest vortices of the flow at each instant, through normalized criteria. In the present fan flow, the velocity spectra are characterized by a peak frequency associated with a natural un-steadiness, in the casing region downstream of the rotor blades. Using the present methodology, in a plane just downstream of the blade trailing edge, a significant wandering motion of the vortex is shown. Further downstream, where the vortex interacts with the adjacent blade wake, the vortex movement is much more disordered. This is interpreted as a vortex splitting phenomenon. But when only the mean flow and the peak frequency are retained in the analysis, a wandering motion is observed again.

Mots clés: fan; tip-leakage; vortex wandering; vortex identification functions

Domaines: Mécanique des fluides [physics.class-ph]

Jérôme Boudet. Numerical investigation of the unsteadiness of a fan tip-leakage vortex. 2017. ⟨hal-01576613⟩