The aerodynamic drag of cars, trucks and buses have been closely examined over the years. Many of them focus on the front end and to some extent on rear end of the vehicles [1]. Of course these are the two surfaces that contribute to more than 85 % of the total drag. This is because these surfaces are almost normal to the direction of air flow and hence create enormous pressure differences and hence drag. A lot of optimization has also gone into these, by way of reducing the sharp corners at ‘A’ pillars, introducing aerodynamic dome and even ‘boat tail flap plates’ [2-3] for some trailers.However, part of the vehicle that has not received sufficient attention in aerodynamic drag considerations is the ‘transverse outer profile’ of vehicle. This transverse outer profile is nothing but the cross sectional profile formed by the vehicle's sides, roof and their integration. This has a considerable impact on aerodynamic drag, especially in buses travelling on highways at considerably high speeds. In buses the roof and sides constitute 75 to 87% (considered for bus lengths of 7 to 12 meters) of the overall outer surface area of the vehicle.This paper discusses the effect of this ‘transverse outer profile’ on the overall aerodynamic drag of the vehicle. CFD (Computational Fluid Dynamics) is used as a tool to understand the skin friction, vortices and hence drag, created by the transverse outer profile. Consequently ways of reducing this drag component, by optimizing the transverse outer profile is evaluated. The variables in this evaluation include - roof curvature, side panel profile and the cant rail cross-section. On the other hand the constraints include various regulatory and ergonomic requirements that define the boundaries of interior saloon space that is enveloped by the outer profile. Within this narrow space, various options of outer profile are tested in CFD, to arrive at the profile that has the lowest drag coefficient, popularly known as Cd.


    Access

    Check access

    Check availability in my library

    Order at Subito €


    Export, share and cite



    Title :

    A Holistic Approach to Aerodynamics of Intercity and Interurban Buses


    Additional title:

    Sae Technical Papers


    Contributors:

    Conference:

    SAE 2014 World Congress & Exhibition ; 2014



    Publication date :

    2014-04-01




    Type of media :

    Conference paper


    Type of material :

    Print


    Language :

    English




    A holistic approach to aerodynamics in intercity and interurban buses

    Shekar,V.T. / Thuraimoni,A. / Reddy,S. et al. | Automotive engineering | 2014


    A Holistic Approach to Aerodynamics of Intercity and Interurban Buses

    Shekar, V.T. / ThuraiMoni, A. / Reddy, S. et al. | British Library Conference Proceedings | 2014


    Urban and interurban buses

    Budd, B.I. | Engineering Index Backfile | 1927


    1946 buses for intercity work

    Engineering Index Backfile | 1946


    Aerodynamic Drag Reduction of Intercity Buses

    McDonald, Alan T. / Palmer, George M. | SAE Technical Papers | 1980