VTI National Transport Research Database

Korrelation av kylflöden mellan modell-och fullskalemätningar av motståndskoefficienten (Correlation of cooling and air intake flows in modell and full scale measurements of drag coefficients)

  • Chalmers tekniska högskola AB, Universitet eller högskola, 556479-5598
Sponsors, duration, budget: Energimyndigheten ; 2007-01-01 -- 2008-12-31 ; 1880000 kronorRegistration number:
  • Energimyndigheten 200604756
Abstract: Avsikten med projektet är att bestämma korrelationer för hur olika kylluftflöden och luftintag skalar mellan modell och fullskala med hänsyn tagen till både Reynoldstalseffekter och luftintag. Projektet kommer att generera en ökad kunskap och insikt i de bakomliggande strömningstekniska orsakerna till kylluftflödets bidrag till luftmotståndet hos fordon. Detta ger möjlighet att utan kostnadsökningar optimera såväl kylluftintagens design som packningen av motorrummets komponenter och underredets utformning avseende strömningsförluster.Abstract: In the development of new car models, but also in the modification of existing models, scale models are commonly used. Normally 1/5 scale models are used, and a central issue in this context is the value of the model drag coefficient as compared to that of a real vehicle. When Reynolds number independence is reached, it is today fairly well known how the drag coefficient scales between model and full scale. However, the accuracy of the predictions is far from satisfactory since all cooling flows as well as influence from different air intakes are neglected. This implies that a significant amount of information is lost because about 15 % of the total drag can be derived to originate from flows in air intakes/outlets. The objective of the here proposed project is to determine correlations between model and full scale considering the influence of Reynolds number effects and the scaling of flows in air intakes. First, the drag coefficients will be determined in the model scale for different configurations of air intakes and cooling flows, and then compared to corresponding full scale data. In order to obtain the correct boundary conditions, all measurements will be conducted in a wind tunnel equipped with a moving ground facility. Based on the measurements a theoretical model will be developed in order to generalize the results. The project is a collaboration between Chalmers (Applied Mechanics), Volvo Cars and SAAB Automobile.
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