Considerations for CFD Simulations of a Refueling Pump Nozzle with Application to the Computer Aided Engineering of a Vehicle Refueling System

A vehicle’s refueling system including components, which make up the onboard refueling vapor recovery (ORVR) system, must be designed to meet federally set evaporative hydrocarbon emission regulations and other performance issues inherent to the refueling process, such as premature click-off and spit-back. A Computational Fluid Dynamics (CFD) model able to predict the performance of a vehicle’s refueling system could be a valuable tool towards the development of future designs, saving the Original Equipment Manufacturer’s (OEM) time and money in the research and development phases. To create an adequate model required for Computer Aided Engineering (CAE) of a modern refueling system, it is paramount to accurately predict the fluid dynamics through and out of a gasoline refueling nozzle, as this is a key inlet condition of any refueling system. This study aims to validate CFD simulations, which predict the fluid dynamics through a refueling gasoline pump nozzle. The commercial CFD software Star-CCM+ was used to model gasoline flow through two gasoline nozzle geometries. The CFD domain for a Husky X1 and an OPW 11B were created using PTC Creo Parametric. Computer Aided Drafting (CAD) models created from physical measurements taken of the deconstructed nozzles. Experiments were conducted and compared to the CFD results. It was found that the OPW 11B produced a divergent/fanning spray pattern, whereas the Husky X1 delivered a narrow jet-like fuel spray. It was found that modeling of the fluid dynamics through the air entrainment and shut-off port geometries within the nozzles were needed to accurately capture fuel spray behavior as demonstrated by experiments. Mesh independence and time independence studies were conducted, as well as different inlet techniques to simulate air entrainment present in the nozzles. The study acts as a guide for future simulations involving fuel filling necks and tanks, and serves to suggest mesh, time step, and solver settings to achieve the highest quality simulation.