Abstract
To deepen our understanding of the flow field and flow mechanism of a car-like model, in this paper, an experimental investigation of the flow field of MIRA notchback 1/8 scale model is carried out using Particle Image Velocimetry (PIV) method. The tests are conducted in an open circuit wind tunnel at a Reynolds number of 9.16×105. In order to obtain the detailed flow field structure of the notchback model, the PIV method was used to capture the flow field images from three orthogonal directions. By studying the vorticity and velocity vector figures of both the time-averaged and instantaneous states, a three-dimensional flow field schematic of the notchback model is summarized, and the formation mechanism and development process of the vortices are analyzed. This study not only provides an intuitive display of the three-dimensional flow field structure of the MIRA notchback model but, more importantly, it provides a reference for the development of automobile aerodynamic drag reduction by analyzing the flow mechanism, which is beneficial to energy conservation.
Highlights
Work towards energy saving and emission reduction has highlighted the importance of drag reduction research for vehicles
It should be pointed out that a comprehensive understanding of flow around automobiles is necessary, due to the close relationships between the flow structure and aerodynamic drag. It was demonstrated in a number of studies that the pressure drag contributes predominantly to the aerodynamic drag, in particular at a high speed
The wake field of vehicle models has attracted considerable attention in the drag reduction research, and a large number of experimental and numerical investigations have been performed in the simplified geometries [2]
Summary
Work towards energy saving and emission reduction has highlighted the importance of drag reduction research for vehicles. Showed that the unsteady characteristics of the wake of notchback were directly related to aerodynamic drag through their experiments and numerical results with an unsteady wake analysis of a notchback vehicle model [5] They found that the arch vortex exhibited a characteristic frequency consistent with the shedding one. Bearman measured the wake of a 1/8 scale fastback vehicle with the method of PIV and noted a significant difference between time-averaged and instantaneous flow structures around the rear auto-body [14]. The instantaneous flow field showed that small scale vortex structures were random in space and time, which had a great influence on the characteristics of vehicle wakes It was more complicated than the time-averaged flow field that showed a well-defined counter-rotating vortex pair. The instantaneous and time-averaged characteristics of the flow field are analyzed by processing the data
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