Transition to turbulence in the rotor boundary layer - Archive ouverte HAL
Communication Dans Un Congrès Année : 2017

Transition to turbulence in the rotor boundary layer

Résumé

This work brings new insights on the way that turbulence occurs in the rotating disk boundary layer. It takes part in the debate initiated by the pioneering work of Lingwood in the ninetees, suggesting the possibility of a direct route to turbulence. The rotating disk boundary-layer of a closed cylindrical rotor-stator cavity is investigated using via direct numerical simulation and linear stability analysis. The mean flow along the rotor matches the von Kàrmàn self-similarity solution, except at the edge where finite-size effects make the flow more unstable, with shear and centrifugal effects, eventually leading to a strong source of perturbations. DNS shows that the transition scenario is governed by edge driven global modes at moderate rotation rates, below the c/a transition, and by self-sustained rotor layer global modes at larger rotation rates. These latter are the superposition of several elephant global modes that leads to a gentler front than expected theoretically for a single elephant global mode. This result could explain the gap observed in the growth rate values between sector DNS and LSA on one side, and experiments and present simulations on the other side. Furthermore, these results show that fully nonlinear simulations are mandatory to reproduce experimental observations. [no other pdf]
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hal-01682997 , version 1 (12-01-2018)

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  • HAL Id : hal-01682997 , version 1

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Eric Serre, Eunok Yim, Denis Martinand, Jean-Marc Chomaz. Transition to turbulence in the rotor boundary layer. 70th annual meeting of the APS DFD, Nov 2017, Denver, United States. ⟨hal-01682997⟩
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