国家大型科学仪器中心系列学术报告
上海市地面交通工具空气动力与热环境模拟
重点实验室学术报告
RoadVehicles: an open challenge problem for Active Flow Control
JacquesBorée
Professor at Ecole Nationale Supérieure de Mécaniqueet d’Aérotechnique (ENSMA)
AssociateEditor “Experiments In Fluids” (since 2004)
DeputyDirector dept Institut Pprime (2018-)
ENSMA-CNRS-Universitéde Poitiers
报告时间：2019年9月7日星期六，10:00-11:00
报告地点：嘉定校区上海地面交通工具风洞中心212会议室
联系人；杨志刚教授，电话69589240
个人简介：
Dr. Jacques Borée is aProfessor at ENSMA (Fluid mechanics, Turbulence) in France, Deputy Director ofInstitut Pprime in Poitiers. Dr. Borée received his Eng. degree in AerospaceEngineering from "Ecole Nationale Supérieure de l'Aéronautique et del'espace" (SUP'AERO) in France, and a PhD degree in Mechanical Engineeringfrom "Institut Polytechnique de Toulouse" in France. His recentresearch interests include:
• External turbulent aerodynamics of Bluff body with massivelyseparated flows.
• Drag reduction using wake active control.
• Detection of unsteady flow structures using topological/Lagrangian approaches or statistical methods (POD, LSE).
• Internal aerodynamics of internal combustion engines.
Further information about Dr. Borée’s recent researchactivities is available at: https://www.researchgate.net/profile/Boree_Jacques
报告摘要：
Drag reduction of ground vehicles hasbecome a major challenge for the transport industry due to increasing need forreducing fuel consumption and carbon pollution. Flows around such bluff bodies correspond to locallyor massively separated flows and our aim is both to develop techniques forbluff body wake manipulation (actuation methods, Active Flow Control – AFC –approaches) and to understand the origins of wake and drag changes. Dragreduction and driving stability are key problems for terrestrial transportationin order to cope with design, functionality and aerodynamics. Even forAeronautics, helicopter or airplane transport may have large, flat loadingramps and poor aerodynamics of the aft body. Fuselage drag reduction andunsteady load alleviation are then key challenges.
A fascinating aspect of these turbulent aerodynamicsat significant Reynolds number (≈106) is the wide range of lengthand time scales. At the scale of the body, vortex shedding, an absoluteinstability, is responsible for self-sustained oscillations. ReflexionalSymmetry Breaking, leading to random switching with a long time dynamics, is alsoobserved. Specific flow structures, namely turbulent shear layers surroundingthe near wake and 3D conical vortices of trailing type for slanted geometries,have very important contributions.
Two geometries will bediscussed in the talk. Experimental models, accompanying metrologies, actuationstrategies and physical mechanisms will be presented. For a square back wake,aligned with the flow or having a moderate yaw angle, our goal is to obtain arobust AFC strategy by driving the wake toward an unsteady symmetric state andby preventing the slow organization dynamic of the asymmetric state. For aslanted and smoothed aft geometry, one has to deal with introduction oflongitudinal vorticity in the near wake and to address interactions of flowstructures and near wake properties.
