Experimental and numerical studies on improvement of drag force of a bus model using different spoiler models

Abstract

The purpose of this paper is to reduce the drag force of a bus model by using four different spoiler models. The tests carried out at six different free stream velocities and in the range of 3.8 ×105 - 7.9 ×105 Reynolds numbers. The drag coefficient (CD) of the bus model was determined as 0.633 in a wind tunnel and 0.645 in Fluent® package program. The first spoiler model consists of a combination of airfoil and vortex generator mounted at five different locations (L/H) on bus model to improve the drag force. The drag reduction was obtained in the range of 12.25-4.35% in five different L/H rates by using spoiler 1 model. The spoiler 2 model has airfoil shape and maximum drag coefficient was improved by 3.34% experimentally. A 23.49% reduction was obtained by using spoiler 3 in L/H = 0.1 and 18.49% reduction by using spoiler 4 in L/H = 0.15. The numerical flow analyses were performed at the same wind tunnel conditions at six free stream velocities for the base model and best results for each spoiler model. The drag coefficients of best models were reduced by 11.48% and 8.59%, 15.90% and 19.05% respectively in Fluent®.