Design and analysis of an aerodynamic kit for a two wheeled race motorcycle

Abstract

In this paper we discuss on what causes the limitations in aerodynamics of a two wheeled motorcycle & try to overcome them by changing its shape & altering it overall weight by adding & subtracting some of the essential & non-essential equipment in it, with considering both the rider on the vehicle as well as off it. The size and shape of a motorcycle together with the rider and any aerodynamic aids such as fairing, windscreen or leg shield induce the drag, lift, hence reduces it power capabilities. Drag is a force trying to prevent rapid movement of a motorcycle through the air. This force is generated through a difference in pressure between the front and rear of the machine. This ultimately helps to enhance the performance of the vehicle. The prototypes of the fairings are designed using 3D CAD modelling software and are compared with each other and the stock variant. Designs are refined through research using CFD (Computational Fluid Dynamics). The goal is to find the most efficient compromise between the drag values for the best handling at the highest possible speeds. Firstly, a naked version of a typical 150 cc motorcycle is used as a base to start the design of the fairings. The 2D sketch of the base motorcycle frame is traced along the outline to draw a visual teardrop structure. A teardrop is the most streamlined structure and has minimum drag coefficient. Cross sections of the motorcycle are obtained front cowl, side fairings and rear cowl are made and analysed using Ansys Fluent. These sets of designs are then compared based on Cd (co-efficient of drag) value and the best design is selected. These cross sections are used to create a wire frame model to create a 3D model using CAD software. The 3D model is then simulated using a CFD tool to study the airflow around it and the results are compared with the naked version of the motorcycle.