Research on the influence of splitter plates on the aerodynamic drag reduction and energy-saving performance of express boxcars

Express boxcars are the most widely used type of vehicle in various express railway freight transportation. However, their typical blunt body configuration leads to poor aerodynamic performance and high energy consumption. This study seeks to explore the possibility of reducing drag and subsequently reducing energy consumption by adding splitter plates with three different gaps (Case 1: 0.21H width and 0.34H height; Case 2: 0.30H width and 0.43H height; Case 3: 0.39H width and 0.51H height, where H is the locomotive height) at the front end of the boxcar body, taking inspiration from drag-reduction solutions used in heavy vehicles. Based on the IDDES method, this study simulates the impact mechanism of splitter plates on the aerodynamic characteristics of the express boxcar, including aerodynamic drag, pressure distribution, slipstream, and Reynolds stress. The results demonstrate that the addition of splitter plates can significantly reduce the overall vehicle drag, with the locomotive and the first boxcar exhibiting the most prominent drag reduction effects. Furthermore, based on the limited three cases in this study, smaller gaps between the splitter plates result in better drag reduction. Compared to the baseline case, the drag of the locomotive and the first boxcar can be reduced by up to 7.1 % and 38.0 %, respectively. Additionally, the inclusion of splitter plates significantly decreases the strength and spatial influence of the slipstream around the first boxcar. This effect is evident from the streamline patterns, which demonstrate that the splitter plates modify the distribution of vortex structures between the locomotive and Boxcar 1. Furthermore, the predicted results of Reynolds stress further support this observation, indicating that the splitter plates effectively reduce turbulent flow in the streamwise direction. The results can effectively guide the engineering design of express boxcars and provide valuable insights for designers during the decision-making process.