Towards multiobjective Nelder-Mead optimization of a HSDI diesel engine: Application of Latin hypercube design-explorer with SVM modeling approach

Abstract

Optimization process of energy-related devices is gaining an undivided attention of industrial sectors due to cost effectiveness and practicality attributes. Diesel engines are the most efficient in producing power, although there is a great capacity that has not been fully exploited. Therefore the simplex-based optimization is addressed to enhance the indicated torque (IT), combustion noise (CN), and swirl ratio (SR) of the engine at the same time. The optimum solution is reached at RunID 27, which demonstrates 7.7% increase in IT, 0.19% decrease in CN, and 21.98% increase in SR compared to those of baseline mode. In the present study, IT and CN vary inversely, thus the modification in injection schemes and chamber geometry have to be considered without putting a penalty on another. It was indicated that Min. swirl and torque cases have significantly reduced bowl volume, however, the case with the lowest swirl has lower centerline depth. In addition, it is determined that Max. torque and swirl are obtainable with a big bowl segment, although it was observed that a shallow combustion chamber is expected to induce higher torque. The higher torque is associated with more uniformity of mixture (0.8484) and pressure peak (13.98MPa) that is plausible with a fitted spray injection with chamber walls coordination, reducing the spray-wall impingement.