A Numerical Study of Vehicle Mounted Wind Energy Generator for Electric Vehicles’ Aerodynamic Properties and Driving Range

Abstract

Electric vehicles (EVs) are the major contributors to the reduction of emissions from road vehicles. From previous studies, this attribute of EVs can further be strengthened by using vehicle-mounted energy recovery systems. This study investigated the implementation of a wind energy recovery system employing a 190mm horizontal axis wind turbine (Model – 1), and a 208mm diameter Savonius rotor vertical axis wind turbine (Model – 2) with an aspect ratio of 1.00 mounted at vehicle front. Computational fluid dynamics (CFD) simulations were performed on a model generated from SOLIDWORKS 2017 in ANSYS 2021 R2. The CFD simulations were performed to study the flow patterns around the designed models, and compute the improvements to the drag coefficients of model – 1 and Model – 2 for comparison with the baseline model which is without an energy recovery system (ERS) onboard. Compared to the baseline drag coefficient value of 0.3463876, model – 1 had a 2.01% improvement while model – 2 had a 3.914% improvement. Physical models were constructed in Simulink® software for the baseline EV and ERS integrated models operating under the Highway Fuel Economy Test (HWFET), and custom driving schedules to estimate the energy recovery potential of the ERS, and the extended driving range of the baseline EV model. The performance of the baseline physical model was assessed from reference speed tracking efficiency, and the model’s response to varying drag coefficients. From the conducted physical model simulations battery state of charge (SOC), and battery voltage levels were used to evaluate the energy recovery potential of the system. For simulations under the HWFET the final battery SOC values for the baseline model, model – 1, and model – 2 were 95.37%, 97.8%, and 97.98% respectively; while for simulation under the custom cycle were 87.11%, 93.4%, and 93.65% respectively. To improve the model accuracy preliminary control simulation were performed for model efficiency corrections, and compute the actual battery SOC levels. From subsequent analysis the increased baseline SOC levels for model – 1, and model – 2 simulated under the HWFET cycle were +0.044%, and +0.18% respectively; while for models simulated under custom cycle were 0.1163%, and 0.35% respectively. Extended model driving ranges for model – 1, and model – 2 simulated under the HWFET were 0.157km and 0.643km respectively; while for models simulated under the custom cycle were 0.397km, and 1.216km respectively. The final values obtained showed that energy recoveries were possible for the designed model.