Influence of Inlet Charge Swirl on Fuel-Economic and Environmental Indicators of a Gas-Piston Engine

The paper introduces the results of studying the influence of intake ports shape on turbulization and charge swirl in the combustion chamber, combustion rate, ecological and indicator values of the engine. The study was carried out using mathematical simulation of physicochemical processes occurring in the combustion chamber of a piston engine during gas fuel combustion. The turbulent flow of the mixture, spark ignition and combustion of gas fuel are simulated. To simulate the turbulent flow, the RNG (k--ε)-model was used, to simulate the combustion of natural gas in the combustion chamber a model based on the specific surface area of the flame, the so-called G-equation model, was used. When simulating spark ignition, the model of discrete particles of the ignition kernel DPIK (Discrete Particle Ignition Kernel) was applied. As a result of simulation, we found that replacing one inlet channel with a tangential channel allows creating a vortex motion and increasing the turbulence of the mixture in the combustion chamber. An increase in the kinetic energy of the mixture before the spark is applied leads to a decrease in the combustion time. The use of swirling the charge on inlet by replacing one filling channel with a tangential one can significantly improve the environmental performance of the engine while maintaining fuel and economic indicators. The ANSYS Forte program was used to simulate the physicochemical processes in the combustion chamber

The quantitative characterization of the ignition process for a lean staged injector: Influence of the air split between pilot swirlers

The ignition of a lean staged injector aimed at aeronautical application is a transient and complex phenomenon, which involves fluid dynamics, turbulent mixing, chemical kinetics, as well as their mutual interactions. In the present research, a staged injector, designed based on stratified partially premixed combustion concept, is introduced. The ignition performance of stratified partially premixed injectors with different air split ratios between pilot swirlers are experimentally acquired, which exhibits apparent distinctions. In order to make quantitative analyses, the classical physical ignition model is improved, in which the flame propagation process is further divided into the axial and radial propagation sub-processes. Nonreacting flow field and discrete phase simulations, validated by experiment results, are utilized to obtain the velocity and spray distributions. Physical parameters characterizing the ignition sub-processes are defined and calculated based on the numerical simulation results. Conclusions are made by comparing the physical parameters of the ignition sub-processes. The radial propagation of the ignition kernel is responsible for the ignition performance difference between the two injectors with different pilot air split ratios (PASR) in that the average equivalence ratio along the radial propagation route of PASR = 7:3 is one order richer than that of PASR = 2:8. The present ignition analysis and model can be further extended and developed for the optimization of ignition performance of lean staged injector.