Effects of Nozzle Hole Arrangement on Combustion Characteristics and Energy Distribution in a DISI Methanol Engine

The direct-injection spark-ignition methanol engines face challenges such as complex air-fuel mixture formation and severe wall heat transfer losses. A feasible solution is to adopt a spatial optimization approach using three-dimensional computational fluid dynamics (CFD) simulation. This paper utilizes a three-dimensional CFD full-cycle simulation model of a methanol engine with a complete spray and SAGE combustion coupling process. It conducts a comparative optimization based on the controlled variables, such as the spatial target point distributions of three different nozzle hole arrangements (AR1, AR2, and AR3). Through detailed numerical simulation, it obtains the optimized injector structural parameters. In the three-dimensional CFD simulation, compared with the highly centralized AR2 scheme, the indicated thermal efficiency of the AR1 and AR3 schemes was increased to 38.6% and 38.3%, respectively, and the heat transfer losses were significantly reduced to 17.7% and 20.4%, respectively, from 23.0%. Ultimately, the AR1 scheme achieved the optimal thermodynamic energy distribution. Moreover, its near-wall heat transfer loss was significantly less than that of the AR2 scheme.