ETD system

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Tesi etd-02032016-083655


Thesis type
Tesi di laurea magistrale
Author
PEZZICA, ERICA
URN
etd-02032016-083655
Title
Lagrangian-based sensitivity analyses of swirling wakes instabilities: application to wind turbine hub vortices.
Struttura
INGEGNERIA CIVILE E INDUSTRIALE
Corso di studi
INGEGNERIA AEROSPAZIALE
Supervisors
relatore Prof. Camarri, Simone
relatore Prof. Gallaire, Francois
relatore Prof. Iungo, Giacomo Valerio
relatore Viola, Francesco
Parole chiave
  • vortex
  • fluid instabilities
  • sensitivity
  • Lagrange problem
  • control
  • optimization
  • turbine wake
Data inizio appello
23/02/2016;
Consultabilità
Completa
Riassunto analitico
In this thesis the sensitivity of flow instabilities in swirling wakes is investigated. In particular, the present work aims to understand how the instability of the hub-vortex of the wake of a wind turbine is affected by a modification of the near-wake conditions. A sensitivity model is formulated and first applied to the case of the laminar Batchelor vortex and then to the turbulent hub-vortex of a wind turbine wake.
In particular, an adjoint based method is proposed to study how a mean-flow modification at a given section in the near-wake affects the stability of the overall wake. The sensitivity of the flow is obtained by means of a lagragian analysis. Leveraging on boundary layer assumptions, an alternative lagrangian formulation, based on a set of quasi-cylindrical flow equations, is then presented.
A main result obtained are the sensitivity maps which prescribe the shape and the magnitude of the optimal mean-flow disturbances to be applied in the near wake so as to damp or enhance the hub-vortex instability. The sensitivity maps can be interpreted as the first step towards the design of a control strategy in the near-wake.
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