Drag optimization of bluff bodies using cfd for aerodynamic. In this context, the higherorder spectral approach is utilized to identify nonlinearity in bluff body aerodynamics observed in windtunnel experiments. The parameter characterizing the effects of compressibility is then the mach number. Clearly bluff body aerodynamics and bluff body hydrodynamics are closely related but in the naval context the presence of an airwater interface and surface. Therefore, bluff body aerodynamics has always lain at the heart of wind engineering. Bluff body aerodynamics and application how is bluff body. The application range from flows around generic bluff bodies such as a finite cylinder to flows around simplified road vehicles, trains and landing gears. Lecture 44 implications of linearized supersonic flow on airfoil lift and drag pdf lecture 45 oblique shock waves pdf lecture 46 prandtlmeyer expansion waves pdf lecture 47 computational methods for the euler equations pdf lecture 48 structured vs. Aerodynamic drag mechanisms of bluff bodies and road vehicles. Jenkins2 1centre for fluid mechanics and computational science cran. The influence of the wind on vehicle flows is investigated and it is found that vehicle mean flows are sensitive to the turbulence level in the relative wind. Bluffbody aerodynamics as applied to vehicles sciencedirect. Aerodynamic drag of bluff body shapes characteristic of hatchback cars 780267 the flow around a bluff body with a slanted rear surface is influenced very dramatically by changing the angle of the rear surface slant and at some slant angles an excessively high drag is generated.
Bluff body drag manipulation using pulsed jets and coanda effect. Im trying to match experimental datas on forces acting on a bluff body transversal section of a vehicle. Bluff body aerodynamics and application how is bluff. Apr 30, 20 the aerodynamic characteristics of bluff bodies differ substantially from streamlined bodies, and an understanding of bluff body aerodynamics is essential to make progress in understanding wind engineering. To learn more about this critical behavior a series of detailed experiments was conducted on a vehi. Conceptual overview of laminar and turbulent flows past smooth and rough circular cylinders m. This work focuses on the aerodynamics of the rearend and underbody of bluff bodies in general, but also applied to passenger cars. Bluffbody aerodynamics and turbulence sciencedirect.
A main physical source of nonlinearity in bluff body aerodynamics and aero elasticity is due to flow separation from the structure. Bluffbody aerodynamics influence on transport and diffusion r. This boundary layer separation results in a large increase in the drag on the body. Holmes basic bluffbody aerodynamics streamlined body flow follows contours of body. Classical fluid dynamics is based on the assumption that. As both blunt and bluff represent the same idea, that of a body that causes high drag. For air at the pressure of one atmosphere and t 15c standard conditions, we have a. Bluff body aerodynamics cfd online discussion forums. Both series have a piezo sensor with multiple elements to register the measured signals and additionally the pipe vibrations with which the. Using the aero components body mounting and rake mounting the body correctly is very important. The effect of slanting the base of a bluff body is discussed and the two main flow regimes that result are described. In most situations it is inevitable that the boundary layer becomes detached from a solid body. The fidelity with which the proposed approaches are able to simulate nonlinear bluffbody aerodynamics and aeroelasticity is verified through windtunnel or cfdbased data. Aerodynamics of bluff body stabilized confined turbulent premixed flames gt1991 mapping the density fluctuations in a pulsed airmethane flame using laservibrometry.
A model for flows with a wake splitter plate is proposed. Pans was previously used for flows such as the flow around a rudimentary landing gear 2 and the flow around a cuboid. Fitting the body so the tires have good clearance no rubbing and centered over the tires is the first step to proper handling. Bluff body hydrodynamics twentyfirst symposium on naval. Journal of wind engineering and industrial aerodynamics. Wardlaw for application in bridge structures 9 one can conclude.
Fluid flow is defined by means of various characteristics like. When the effective angle of the diffuser was increased with an increase of the bluff body nosedown pitch, the vortices moved forward and strengthened due to the induced inflow, preventing the formation of a separation bubble on the diffuser ramp. Aerodynamics of bluffbody stabilized confined turbulent. In aerodynamics, a bluff body is one which has a length in the.
Furthermore, we are making the critical evaluation of the pans technique for bluff body. Subcritical regime most windtunnel tests separation at about 90o from the windward generator. Industrial aerodynamics free download as powerpoint presentation. These vortices are shed from the surfaces of the body and are then carried downstream. A selection of papers presented at the international colloquium on bluff body aerodynamics and its app m. While the measurement principle of the swirlmaster is based on concentric swirls that create pressure fluctuations in the medium, the vortexmaster works according to the karman vortex principle with turbulences generated by a bluff body. Bluff body aerodynamics and application listed as bbaa. The book has been revised to include the latest developments in flow control and boundary layers, and their. Complexity due to interacting effects of surface roughness, reynolds number and turbulence in the approach flow. Reviewbluff body flows applicable to vehicle aerodynamics. Pdf bluff body aerodynamics and wake control researchgate. Perspectives on bluff body aerodynamics caltechauthors. Bluff body aerodynamics and application how is bluff body aerodynamics and application abbreviated.
This work focuses on the aerodynamics of the rearend and under body of bluff bodies in general, but also applied to passenger cars. The variations of drag and base suction of circular cylinders and bluff plates over the range of reynolds number from 10 to 107 is discussed, with emphasis on the importance of the separated shear layers. Aerodynamic stabilization of several suspension bridges recently built in china is introduced hereafter, and followed by aerodynamic feasibility study of a 5000mspan suspension bridge. An alternate way is to utilize computational fluids dynamics.
When a bluff body is embedded in a fluid flow it may cause a wake forming behind the body. Unstructured grids pdf lecture 49 solution convergence pdf. Streamlined bodies like aircraft wings have a rounded nose, a thin profile, and a sharp trailing edge. Sep 10, 2015 bluffbody aerodynamics department of mechanics aerodynamic loads induced by the wind on civil structures, in the following the fluid will always be fig. Aerodynamic drag of bluff body shapes characteristic of. Aerodynamics johnson space center jsc offers technical leadership in the engineering disciplines of aerodynamics, aerothermodynamics, and fluid dynamics. Ahsan kareem department of civil engineering university of houston iscussion on paper by professors n. Journal of wind engineering and industrial aerodynamics, 49. The present results encourage the development of fluidic control in road vehicles aerodynamics as well as provide a complement to our current understanding of bluff body drag and its manipulation. The term downforce in racing is used to described the downward force of the air on the body surface as air passes over it at speed. Journal of wind engineering and industrial aerodynamics, 49 1993 122 1 elsevier bluffbody aerodynamics as applied to vehicles if.
High resolution schemes in bluff body aerodynamics. Aerodynamics for engineers international edition download. High resolution schemes in bluff body aerodynamics core. Dear conference participants, it is our great pleasure to announce that the 8th international bbaa colloquium will be held at northeastern university on june 7 11, 2016. Perspectives on bluff body aerodynamics sciencedirect. In this paper we are exploring the usefullnes of this technique for application in vehicle aerodynamics.
Study materials aerodynamics aeronautics and astronautics. Bluff body aerodynamics and wake control intechopen. Bluff body aerodynamics of interest in structural engineering applications is associated with atmospheric flows, which are incompressible owing to their relatively low speeds. For streamlined sections like an airfoil or a wind turbine blade, flow separation results from the large angle of attack dynamic stall or in the case of high flight speed of an aircraft shock motions in the. Journal of wind engineering and industrial aerodynamics, 49 1993 122 1 elsevier bluff body aerodynamics as applied to vehicles if. The variations of drag and base suction of circular cylinders and bluff plates over the range of reynolds number from 10 to 107 is discussed, with emphasis on. Bluff body article about bluff body by the free dictionary. We can understand this by returning to the flow of a nonviscous fluid around a cylinder. Bluff body aerodynamics in wind engineering sciencedirect. Im using segeregated solver, first order discretization for all quantites, simple pressurevelocity coupling, and a user defined velocity profile at the inlet. With this bluff body, positioned in a uniform crossflow, the vortex shedding frequency and other flow characteristics could be manipulated. Apply this understanding to improve flight performance and stability predictions. Bluff body aerodynamics and application international colloquium bbaa. Physical sources of aerodynamic nonlinearities are investigated by analyzing the aerodynamic forces on a suite of crosssections obtained through computational fluid dynamics cfd.
Holmes basic bluff body aerodynamics streamlined body flow follows contours of body. Welcome to the 8th international colloquium on bluff body aerodynamics and applications. The flow around a bluff body with a slanted rear surface is influenced very dramatically by changing the angle of the rear surface slant and at some slant angles an excessively high drag is generated. Shedding is erratic and multimodal, but strouhal numbers are typically in the range 0. Bluff body aerodynamics in wind engineering peter a. Bluff body aerodynamics and wake control, applied aerodynamics, jorge colman lerner and ulfilas boldes, intechopen, doi. Bluff body drag manipulation using pulsed jets and coanda. For juniorsenior and graduatelevel courses in aerodynamics, mechanical engineering, and aerospace engineering revised to reflect the technological advances and modern application in aerodynamics, the sixth edition. Jsc maintains a highly skilled and experienced workforce, premier laboratories and test facilities, and stateoftheart analysis tools and databases. Status of pans for bluff body aerodynamics of engineering. This being the main objective, optimisation of body aerodynamics i.
Request pdf bluff body aerodynamics bluff body aerodynamics of interest in structural engineering applications is associated with atmospheric flows, which. The use of a bluff body wake generator for wind tunnel. High resolution schemes for bluff body aerodynamics. View notes chapter 5 bluff body aerodynamics from ces 5587 at florida international university. Aerodynamic drag of bluff body shapes characteristic of hatch. Aerodynamics for engineering students, fifth edition, is the leading course text on aerodynamics. Efstathios konstantinidis and demetri bouris may 11th 2012. One of the fascinations of wind engineering is the great variety of bluff body aerodynamic problems that are. Chapter 5 bluff body aerodynamics 5 bluff body aerodynamics. Applied aerodynamics by bairstow, leonard, 1880publication date 1920 topics aerodynamics, aeronautics.
In the wake the flow is turbulent but a distinguished pattern of vortices can usually be seen. Flow around bluff bodies is of great importance today not only in automotive industry, but in every industrial department or product that is associated with any kind. The use of a bluff body wake generator for wind tunnel studies of nascar drafting aerodynamics 2008012990 it is well documented that the aerodynamic downforce that is developed by a nascar race car is degraded when closely following another car. Some effects of freestream turbulence on the flow past a cantilevered circular cylinder y. One of the fascinations of wind engineering is the great variety of bluff body aerodynamic problems that are encountered.
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