报告时间：2017年9月28日(周四)下午4:00

报告地点：北航流体所214会议室

报告摘要：Themain applications of 2D dynamics of helical vortices embedded in flows withhelical symmetry are addressed.

The fundamentals of the 2D helical vortex dynamics lie in

(i) 2D algebraical expression of Biot-Savart law forhelical filament;

(ii) analytical solution for self-inducedmotion of the helical vortex cores;

(iii) Goldstein’s solution for circulation of equilibriumof helical vortex sheets;

(iv) Generalization of Kelvin’s problem on point vortexN-gon stability to helix etc.

The primary assumption of the 2D theory is the hypothesisof helical symmetry that has been carefully tested in swirling flows indifferent kinds of swirlers and vortex generators. Both right- and left-handedhelical symmetries were found in these real flows and hypothesis of existenceof possible transitions between the different types of the vortex structureshave been put forward. The change in axial velocity distribution from ajet-like profile to a wake-like during vortex breakdown has been investigatedfrom this point of view and the associated transition from right- toleft-handed helical symmetry of the vorticity field has been confirmed fromexperimental data and numerical simulations. Various vortex models for farwakes behind rotors are analyzed.

报告人简介：

Prof.Valery Okulov works in DTU, Denmark more than 10 years but before that heworked long time in Institute of Thermophysics, SB RAS, Russia. He obtained hisdegrees of D.Sc. (1994) and PhD (1985) in Fluid Dynamics. His research area isfocused on aerodynamic and acoustic of turbo machines and wind turbines;hydrodynamics and physical processes in swirl flows; vortex dynamic, resonancesand hydrodynamics instability in power-engineering devices. His scientificworks are awarded diplomas and prizes: JSPS invitation fellowships (Japan),Diploma of TsAGI, Medal of G.I. Petrov for outstanding results inhydrodynamical stability and turbulence, Diploma of the Russian Academy ofSciences for outstanding scientific results, Otto Mønsted professorships (Denmark),Fellowship for young D.Sc. granted by the President of the Russian Federationetc.

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