Aerodynamic investigation into the underbody drag reduction of truck model by adapting active and passive flow control techniques

Abstract

With the world moving towards clean vehicle and fuel technologies, increase in price of fossil fuel accompanied by the degradation of environment due to the tailpipe pollutants emitted from heavy vehicle have spearheaded the manufacturers to develop fuel efficient vehicles thereby minimizing the emission of harmful pollutants to the environment. The challenges for reducing tailpipe pollutants in trucks continue to grow with the non-engine losses such as rolling resistance, air resistance and braking in heavy vehicle accounting about 45% of the total decrease in fuel efficiency. The wind resistance, being the main contributor for decreased fuel efficiency has to be minimized by curtailing the aerodynamic drag for better propulsion of the vehicle without going for other technologies like better transmission, better tyres, downsizing of engine and hybrid technologies. The impact on the curtailing of aerodynamic drag to the increased fuel efficiency is deemphasized and the exploration for retrofitting devices to curtail aerodynamic drag on a truck has gained importance. The present investigation has taken into account the drag minimization at the underbody region of a truck, as the aerodynamic development of the underbody region has been downplayed even though it has the most prominent influence on the fuel consumption of trucks. The investigation incorporates the implementation of flow control techniques for minimizing the pressure difference between the stagnation pressure and base pressure. The retrofitting Active (AFCD) and Passive Side Skirt (PFCD) were developed based on the active and passive flow control techniques. The truck model without any flow control devices was empirically investigated in a wind tunnel for aerodynamic drag and further was numerically simulated inANSYS-FLUENT using realizable (and#119896; and#8722; and#120576;) model. Three distinct designs of Passive Side Skirt namely Bent Arc, Bent Flap, and Bent Hole Side Skirt were assessed on a scaled truck model both by experimentally in a wind tunnel followed by numerical analysis. The bent flap angle (and#945;) and the height of Side skirt (HS) were varied to generate 27 configurations of Passive Side Skirt.The truck model with BF 81-1 configuration of Bent Flap Side Skirt and BA 81-1 configuration of Bent Arc Side Skirt displayed a maximum drag coefficient reduction rate of 10.77 % and 12.29 %, compared to the model without side skirt at 30 m/s (108 km/h). The BH 81-3 configuration of Bent Hole Side skirt achieved a maximum drag reduction of 14% , compared to the model without side skirt which aids to an average fuel savings of 21 kilolitres per year. The empirical values were supported with the numerical values with an error percentage of less than 3 % newline