Development of a Fast, Robust Numerical Tool for the Design, Optimization, and Control of IC Engines

Abstract

This paper discusses the development of an integrated tool for the design, optimization, and real-time control of engines from a performance and emissions standpoint. Our objectives are threefold: (1) develop a tool that computes the engine performance and emissions on the order of a typical engine cycle (25-50 milliseconds); (2) enable the use of the tool for a wide variety of engine geometries, operating conditions, and fuels with minimal user changes; and (3) couple the engine module to an efficient optimization module to enable real-time control and optimization. The design tool consists of two coupled modules: an engine module and an optimization module. The engine module consists of three components: a two-zone quasi-dimensional engine model to compute the temporal variation of temperature and pressure during the compression and power stroke, a thermal model to compute the cyclic variation of the engine wall temperature, and a reaction-rate-controlled emission model to compute engine-out NO and CO. The optimization solver is an extension of the model-based, derivative-free POUNDER and is designed to limit the number of engine model evaluations. The outputs of the engine model, thermal model, and emissions model can be used for optimizations under various design constraints. By more thoroughly using the output from the simulations, our optimization scheme reduces the number of simulation evaluations by two orders of magnitude compared with parameter sweeps and one order of magnitude compared with the standard black-box optimizer in MATLAB. These results highlight the proposed tool's potential for use in design, optimization, and real-time control of engines.

Development of a Reduced-Order Design/Optimization Tool for Automotive Engines Using Massively Parallel Computing

“…The capabilities of pMODES can be used as one "closes the loop" between the simulation and analysis for purposes of simulation-based design optimization [2] or optimal experimental design to determine configurations that should be tested on a dyno. Furthermore, pMODES can be used to generate input configurations in order to optimize a design objective of interest.…”

“…Several quasi-dimensional models have been developed since the early 1980s to study both gasoline and diesel engines (see, e.g., [1][2][3][4][5][6][7][8][9][10][11]) with varying degrees of fidelity. With few exceptions (e.g., [1,6,10]), however, these studies do not discuss the wall-clock time required for the computation of an engine cycle (a single compression and expansion stroke).…”

“…This information is used to compute emissions (e.g., NO, CO, soot) and ion current using reduced-order models. Optionally, the engine wall temperature can also be computed as described in [2]. Furthermore, the computed cylinder pressure can be used to evaluate engine performance metrics such as BMEP, torque, and power.…”

“…Furthermore, the computed cylinder pressure can be used to evaluate engine performance metrics such as BMEP, torque, and power. Details of the solution procedure for obtaining the cylinder state variables along with emissions, wall temperature and ion current (or voltage) and are described in [1,2,14,15]. Detailed validation of the ion-current sub-models used in this work have been discussed in [14,15] and hence will not be presented here.…”