INTERNATIONAL RESEARCH JOURNAL OF AUTOMOTIVE TECHNOLOGY (IRJAT) http://www.mapletreejournals.com/index.php/IRJAT Received 22 June 2018 ISSN 2581-5865 Accepted 29 July 2018 2018; 1(4);85-90 Published online 30 July 2018 Aerodynamic Design Improvement for an Intercity Bus J.Vasanthe Roy 1* ,T.Santhosh Kumar 2 ,R.Ashish Kumar 2 ,S.Jeeva 2 ,V.Vinoth Kumar 2 1 Assistant Professor, Department of Mechanical Engg, Velammal Institute of Technology, Chennai-601204. 2 UG Students, Department of Mechanical Engineering, Velammal Institute of Technology, Chennai-601204. . *Corresponding author E-Mail ID: vasantheroy18@gmail.com ABSTRACT Intercity buses travel about 250 to 350 km in a stretch and usually are of sleeper coach mode. The exterior styling, sleeper comfort and aerodynamically efficient design for reduced fuel consumption are the three essential factors for a successful operation in the competitive world. The bus body building companies prioritizes the exterior looks of the bus and ignore the aerodynamic aspect. Scientific design of sleepers for increased comfort of the passengers is seldom seen. The overall aim of this project was to redesign an intercity bus with enhanced exterior styling, reduced aerodynamic drag and increased comfort for the passengers. Principles of product design were used to analyze the styling and comfort. The benchmarked high floor bus was redesigned with low - floor for reduced aerodynamic drag. The exterior was redesigned with emphasis on improvised aerodynamic performance and appealing looks. The interior was modified to meet aspirations of the commuters. The results of the redesigned exterior body showed a reduction of about 45% in coefficient of drag and overall aerodynamic drag reduction by 60% due to combined effect of reduced coefficient of drag and frontal area. Keywords— Aerodynamics, CFD, Conceptual Bus, Drag Reduction, Comfort. 1. INTRODUCTION Buses are the major mode of mass transportation all over the globe, despite of the rail network. Buses are inefficient in term of fuel consumption, thus in order to decrease the fuel consumption of vehicles, improvement in the aerodynamics of bus shapes will add to the value. It becomes essential to thoroughly design a vehicle for its aerodynamics, as it directly relates to the fuel economy and resisting forces, which further this, become a parameter for mankind to purchase the vehicle. More precisely the reduction of their drag coefficient becomes one of the main topics of the automotive research. Decreased resistance to forward motion allows higher speeds for the same power output or lower power output for the same speeds. Aerodynamics being the aid to form a body shape that maximizes the down force, the negative lifts and minimizes the force that opposes the forward movement and the drag forces. The aerodynamically efficient design of the bus reduces the drag force improving the fuel efficiency. In a moving vehicle, the engine power is used to overcome tractive resistance, which is the combination of rolling and aerodynamic resistance. The rolling resistance will be dominant over the aerodynamic resistance at lower speeds. Aerodynamic resistance (drag) amounts for more than three fourth of total engine power while operating at higher speeds, since the drag increases as the square of the speed. Thus the maximum power generated by the engine is utilized to overcome the aerodynamic resistance. Due to this the engine load increases substantially which further raises the fuel consumption rate.