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- Marklund, Ture Jesper, 1970, et al.
(författare)
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Drag Reduction of a Simple Bluff Body by Changing The Rear End
- 2009
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Ingår i: 2009 ASME Fluids Engineering Division Summer Conference, FEDSM2009; Vail, CO; United States; 2 August 2009 through 6 August 2009. - 9780791843734 ; 2, s. 291-296
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Konferensbidrag (refereegranskat)abstract
- The flow field around bluff bodies constitutes a classic areawithin fluid dynamics and has been the topic for much researchthrough the years. However, in the use for road vehicles withthe effect of the ground, the behavior is changed very muchfrom more classical aviation usage. In this paper we areinvestigating the drag force reduction on a vehicle likesimplified model with rear open diffuser when stationaryground simulation is considered.The objective with this work was to study the rear end of abluff body and optimize it for drag with ground vehicle likeboundaries. Here the testing contains two common bodyvariants, square back, boat tailed/fastback in generic forms.Scale model testing combined with simulations is used toexplain behavior and flow field. The model testing isperformed in the L2 scale model wind tunnel at ChalmersUniversity of Technology in Gothenburg, Sweden. Simulationsare done with the commercial CFD code Fluent.A diffuser on a car is normally used to create down forcebut here it is tested to see if the energy in the flow can be usedto optimize reduction of drag. One part of the study is to showthe potential in optimizing the rear end underbody for drag, byvarying the diffuser angle.The results show a potential in drag reduction by using adiffuser and varying effect depending on other rear endgeometries.
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| 2. |
- Marklund, Ture Jesper, 1970, et al.
(författare)
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FLOW FIELD AROUND AND IN A SAAB 9-3 CONVERTIBLE
- 2009
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Ingår i: EUROMECH COLLOQUIUM 509,External aerodynamics of Railway Vehicles Trucks Buses and Cars, Berlin, Germany, March 24--25, 2009. ; , s. 144-157
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Konferensbidrag (refereegranskat)abstract
- The aerodynamic comfort in a four seated convertible with open roof is not as goodas many would like it to be. This job was initiated to look at what should be done to improvethis. The car used for this study was a Saab 9-3 convertible. Most of the work was done inCFD in the commercial code Fluent.The flow field in the cockpit was first of all analyzed and evaluated. The problem with convertiblesis the large recirculation bubble that occurs around the passenger compartment. Therear seat passengers are located in an area of this zone with very high wind speeds comparedto the front seat passengers. The flow field was analyzed by several pressure and velocityplots and a method to evaluate comfort grading was developed. The selected main variable tocompare cases was the mean velocity that the passengers head is exposed to. This was foundto be the most affecting parameter because it affects not only the dynamic pressure, but alsothe temperature discomfort. Geometry optimizations of windows, wind shield and wind blockershave been simulated and evaluated. Height and length of the side windows and a numberof different wind deflectors on the wind shield, plus wind blockers inside and behind cockpitwas tested. The results show that the biggest potential of improvement is the wind deflector onthe windshield and some of the wind blockers.
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