Aerodynamic Analysis of Electric Cargo Scooter with Unified Modelling and Simulation

Abstract

<div class="section abstract"><div class="htmlview paragraph">Aerodynamic analysis is a primary requirement in the development of electric scooters to predict the impact of air flow around the vehicle on critical performance parameters including the overall range, vehicle stability due to wind loads, air cooling of electric motor and battery. Any new design of vehicle requires an aerodynamic evaluation to estimate the variations in drag forces with speed. It is prohibitively expensive and time consuming to perform full-scale model wind tunnel tests on each variant of the vehicle configuration for wide range of driving scenarios. Physics-based 3D simulation is the preferred approach in the present context and the use of Computational Fluid Dynamics (CFD) for such cases has been well understood and established. Although only the external shape changes make a difference to external aerodynamics, sometimes even a small variation in shape could trigger unwanted flow behavior leading to large drag forces, or enhance the vehicle performance by reducing the drag, with less aggressive design changes. In the present work, we study aerodynamics of world’s first Compact Logistics Vehicle (CLV) – a purpose-built electric cargo scooter that can accommodate a rider and a pillion along with a significant amount of dedicated cargo space. We already established the methodology and best practice for a variant of the present vehicle which could accommodate only the rider and have implemented the same in the current study. A total of 15 different scenarios including three different vehicle and rider combinations across a range of velocities (6 m/s or 21.6 km/h, 8 m/s or 28.8 km/h, 11 m/s or 39.6 km/h, 16 m/s or 57.6 km/h and 22 m/s or 79.2 km/h), have been studied, by placing the vehicle in a virtual wind tunnel and simulating the velocity and pressure distribution, and most importantly total drag force for each scenario. The three cases comprise the stand-alone vehicle, vehicle with the rider, and vehicle including the rider and the passenger (pillion). The result of this study indicates only a slight variation in the drag due to the presence of a rider along with the passenger (pillion). We are able to capture the aerodynamic characteristics of the recirculation zones in all of these cases. In addition to the variations in the inlet velocities, we also studied the effect of the turbulence intensities (5%, 10%, and 20%) on the over-all drag coefficient.</div></div>