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Investigating the effects of aerodynamic characteristics in the automotive segment has been one of the thrust areas of research in the recent years. Extensive research had been carried out earlier in minimizing the aerodynamic drag of the car body and to study the effects using passive air flow deflectors. Little work has been conducted on semi-active or actively controlled air flow modification techniques. In order to contribute new knowledge in the chosen area and to draw the attention of current researchers the present work focuses on the study of aerodynamic characteristics of a typical sedan car model equipped with three numbers of delta shaped vortex generators (VGs) as an aerodynamic add-on device to delay the early flow separation of air from the vehicle body. The yaw angles of the VGs are semi actively controlled using mini stepper motors. The middle VG is kept stationary, whereas the other two VGs orientation has been modified and the results have been studied. The aerodynamic property of a car model mounted with four distinct yaw angle configurations obtained by means of mini stepper motor has been quantitatively evaluated by sub-sonic wind tunnel tests and computational analysis. From the experiments the peak drag and lift coefficient reduction rates of 4.53% and 2.55% respectively have been observed in the case of car model with vortex generators having leading edges facing the rear end and the mid plane of the car respectively when compared with the car model without vortex generators. Numerical simulation using realizable (k-ε) model predicted the drag and lift coefficient reduction rates closer to the experimental values and also it predicted the existence of magnitude of turbulent kinetic energy variation in the roof portion of the car model with four dissimilar configurations of vortex generators relative to the case of car model without vortex generators.

Nanosize B 4 C and/or MoS 2 particles reinforced AA2219 alloy composites were prepared using the stir casting process. The wear properties were evaluated for several speed (3.14-5.65 m s −1 ), load (10-50 N) and distance (0-2500 m) conditions. The nanoparticles dispersion, density, wear resistance, morphology of the worn surface and loose wear debris were discussed in detail. The wear resistance improvement results by nanoparticle addition correspond well with the hardness. Between the nanocomposites, hybrid composites show significantly higher wear resistance for all load, speed and sliding distance conditions. The better wear resistance is attributed to the matrix strengthening by nanoparticles and the lubricant-rich tribolayer controlled wear in the hybrid composites. The intensity of abrasive, oxidation and delamination wear mechanisms decide the wear rate at any particular wear testing condition.