Development And Application Of A Numerical Simulation Platform For Engine Design And Operating Parameters Optimization

Numerical simulation is an important tool for modern automotive related researchand development. It has been widely used in all aspects of the vehicle and itssub-systems’ development and design. As the basis of the National Science andTechnology Support Program2009BAG13B04，in view of Chinese current status in theengine R&D activities which are often separated from the vehicle development and thedilemma that the key technologies cannot be mastered through “reverse” engineering, anew approach, derived from the vehicle performance requirements, is proposed in thispaper for “forward” engineering of engine design and operating parameters’ selectionand optimization through numerical simulation. A software platform is developed,utilizing the high-level programming language Excel-VBA, and combined with theadvanced and well proven numerical simulation tool GT-Power and DOE optimizationscheme, for vehicle and engine performance prediction, as well as engine design andoperating parameter optimization.Firstly, based on the vehicle dynamics and kinematics theory, a vehicle’sperformance requirements are decoupled, step by step, into the powertrain, and then tothe engine’s performance requirements. Secondly, based on the determined engineperformance targets from the first step, an in-depth study is performed based on theunderstanding to the inner relationships between the engines’ performance parameterswith the design and operating parameters. The engine’s major design parameters arechosen in this way for detailed gas dynamics and thermodynamics simulation. Basedon the gas dynamics similarity criteria across different engines, a baseline engineperformance simulation model is established and a DOE optimization scheme isdetermined. The model and the DOE scheme are then fed into GT-Power software forautomatic optimization.A brief introduction is given for the concept of the platform, followed by adetailed description of the functionality and its sub-models, fundamental relationshipsbetween the performance, design and operating parameters. The seamless coupling ofthis platform with GT-Power, as well as the DOE scheme is also described.Finally, the functionality and the accumulated fuel economy modeling accuracy ofthe developed platform are verified and compared to the measurement data of twotypical passenger cars. The vehicle dynamic simulation results, such as0-100km/h full load acceleration process, as well as the instant fuel consumption rate when drivingalong the National Fuel Economy Driving Cycle, are benchmarked to the widely usedGT-Drive simulation tool, very good agreement is shown.It can be concluded that the integrity and simulation accuracy of the softwareplatform is in full compliance with the requirements of engineering applications, it canprovide guidance for the preliminary conceptual design, to improve the efficiency ofthe vehicle and engine R&D activities, to shorten the development cycles and save R&D costs for the forward engineering of an engine.