Reducing drag is a vital objective for the future of flight and other fields that has to deal in some way with moving fluids. Many techniques to reduce turbulent skin friction drag has been proposed over the years. Compliant structures and coatings show several benefits with respect to other drag reduction techniques, and so represent an appealing solution worth investigating. These techniques consist in covering with compliant materials the surface bounding a turbulent flow. If correctly designed, these materials are thought to be able to reduce the turbulent skin friction drag. Luo and Bewely proposed a tensegrity fabric class of structures as a possible candidate for usage in such techniques. The idea was presented in two conference papers • Haoxiang Luo and Thomas R. Bewley. Design, modeling, and optimiza- tion of compliant tensegrity fabrics for the reduction of turbulent skin friction. In Smart Structures and Materials 2003: Modeling, Signal Pro- cessing, and Control, volume 5049, pages 460–470. SPIE, August 2003. • H. Luo and T.R. Bewley. Accurate simulation of near-wall turbulence over a compliant tensegrity fabric. In SPIE Paper 5757-17., 2005. that up to today remain the only attempts in exploring this possibility. Tensegrity structures are a very old concept, exploited many times in architec- ture, engineering and arts. They are structures in which the loads are carried by members that experience compressive loads (bars) and tensile loads (tendons), and they possess many interesting properties. The objective of this work is to develop a tool that can be used to investi- gate this interesting class of techniques in the framework of turbulent skin drag reduction, starting from the work presented by Luo and Bewely. A solver to advance in time the equations of motion for the tensegrity fabric structure is developed from scratch. This code is then coupled with an existing immersed boundary solver for the flow field in order to have a complete tool needed for further studies. This fully-coupled code is then tested and some very prelimi- nary results are presented, not aimed at finding drag reduction, but at verifying the developed code.
Ridurre la resistenza aerodinamica è un obiettivo fondamentale per il futuro del volo e degli altri campi i quali devono affrontare in qualche modo la presenza di fluidi in movimento. Negli anni sono state proposte molte tecniche per ridurre lo la resistenza dovuta ad effetti viscosi. Tra queste, le strutture e i rivestimenti cedevoli offrono diversi vantaggi rispetto alle altre, e rappresentano quindi una soluzione interessante da approfondire. Queste tecniche consistono nel rivestire con materiali compliant la superficie a contatto con un flusso turbolento. Se pro- gettati correttamente, si ritiene che questi materiali possano ridurre resistenza dovuta ad effetti viscosi. Luo e Bewley hanno proposto una classe di strutture di tensegrità a tessuto come possibile candidata per l’utilizzo in tali tecniche. L’idea è stata presentata in due articoli da conferenza • Haoxiang Luo and Thomas R. Bewley. Design, modeling, and optimiza- tion of compliant tensegrity fabrics for the reduction of turbulent skin friction. In Smart Structures and Materials 2003: Modeling, Signal Pro- cessing, and Control, volume 5049, pages 460–470. SPIE, August 2003. • H. Luo and T.R. Bewley. Accurate simulation of near-wall turbulence over a compliant tensegrity fabric. In SPIE Paper 5757-17., 2005. che ad oggi rimangono gli unici tentativi di esplorare questa possibilità. Le strutture di tensegrità sono un concetto ormai noto, sfruttato molte volte in architettura, ingegneria e nell’arte. Sono strutture in cui i carichi sono sostenuti da elementi che sopportano carichi di compressione (aste) e carichi di trazione (tendini), e possiedono molte interessanti proprietà. L’obiettivo di questo lavoro è sviluppare uno strumento che possa essere uti- lizzato per studiare questa interessante classe di tecniche nel contesto della riduzione della resistenza dovuta ad effetti viscosi, partendo dal lavoro di Luo e Bewley. Viene sviluppato da zero un solver per avanzare nel tempo le equazioni del moto per tali strutture di tensegrità. Questo codice viene poi accoppiato con un solver immersed boundary esistente per flusso turbolento, in modo da ottenere uno strumento completo necessario per ulteriori studi. Questo codice completamente accoppiato viene quindi testato per ottenere alcuni risultati pre- liminari, non finalizzati a trovare una riduzione della resistenza, ma a verificare il codice sviluppato.
Turbulent skin-friction drag reduction by tensegrity fabric
Pionetti, Lorenzo
2023/2024
Abstract
Reducing drag is a vital objective for the future of flight and other fields that has to deal in some way with moving fluids. Many techniques to reduce turbulent skin friction drag has been proposed over the years. Compliant structures and coatings show several benefits with respect to other drag reduction techniques, and so represent an appealing solution worth investigating. These techniques consist in covering with compliant materials the surface bounding a turbulent flow. If correctly designed, these materials are thought to be able to reduce the turbulent skin friction drag. Luo and Bewely proposed a tensegrity fabric class of structures as a possible candidate for usage in such techniques. The idea was presented in two conference papers • Haoxiang Luo and Thomas R. Bewley. Design, modeling, and optimiza- tion of compliant tensegrity fabrics for the reduction of turbulent skin friction. In Smart Structures and Materials 2003: Modeling, Signal Pro- cessing, and Control, volume 5049, pages 460–470. SPIE, August 2003. • H. Luo and T.R. Bewley. Accurate simulation of near-wall turbulence over a compliant tensegrity fabric. In SPIE Paper 5757-17., 2005. that up to today remain the only attempts in exploring this possibility. Tensegrity structures are a very old concept, exploited many times in architec- ture, engineering and arts. They are structures in which the loads are carried by members that experience compressive loads (bars) and tensile loads (tendons), and they possess many interesting properties. The objective of this work is to develop a tool that can be used to investi- gate this interesting class of techniques in the framework of turbulent skin drag reduction, starting from the work presented by Luo and Bewely. A solver to advance in time the equations of motion for the tensegrity fabric structure is developed from scratch. This code is then coupled with an existing immersed boundary solver for the flow field in order to have a complete tool needed for further studies. This fully-coupled code is then tested and some very prelimi- nary results are presented, not aimed at finding drag reduction, but at verifying the developed code.| File | Dimensione | Formato | |
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https://hdl.handle.net/10589/230488