Hot-wire measurements on the Ahmed body turbulent wake in a low-speed wind tunnel

Abstract

The Ahmed body is a standard model proposed for the study of road vehicles, serving as a reference point for calibrating wind tunnels, computer codes, and for extrapolating results for design or industrial purposes. Even though the model is a simple geometry, it reproduces the turbulent flow of the wake, boundary layer separations and flow re-entries, in a similar way to those found in real ground vehicles. Particularly, the study of turbulent wakes is of interest to evaluate possible effects of instability due to dynamic loads introduced by the wind, aiming to reduce fuel consumption. In this paper, measurements of the Ahmed body’s wake are reported. The experiments have been carried out in the wind tunnel “Jacek Gorecki” of the Universidad Nacional del Nordeste (UNNE), Argentina. The measurements were performed with a DANTEC hot wire anemometer. A previous calibration of a single probe was carried out within the range of speed measurements, and then time velocity series were obtained at the wake turbulent flow. The preliminary mean velocity results are evaluated and compared with a Laser Doppler Anemometry (LDA) experiment from specific literature. Spectral analysis of the velocity fluctuations for relevant measurement points is also presented.