development of a zero-dimensional turbulence model for the flow field of spark-ignition engines, considering vortex motions, based on a new approach

In this paper, a novel zero-dimensional (0-d) in-cylinder turbulence model has been developed to account for vortex motions in spark-ignition (si) engines. the flow’s mean kinetic energy is decomposed into two distinct components: directional and non-directional flows. to enhance the physical integrity of the model, a directional production term is introduced based on the principles of in-cylinder rotational energy and angular momentum. the traditional production term associated with tumble kinetic energy is replaced by a non-directional production term. it is postulated that the production of turbulent kinetic energy can be linked to the loss of rotational energy through this directional production term, encompassing the energy changes in vortices when the valves are closed and the angular momentum of intake flow when the valves are open. additionally, the mass flow rate within the cylinder is derived through a one-dimensional (1-d) isentropic flow analysis. to validate the model, experimental investigations are conducted on a natural gas-fueled si engine, which serves as a reference for model development. the developed model demonstrates the ability to predict the key characteristics of turbulent flow and accurately reproduce the variation of related parameters when compared to the results obtained from three-dimensional (3-d) simulations. notably, the model requires only a minimal number of tuning constants that are case-insensitive. furthermore, the results exhibit a high degree of precision near top dead center (tdc) in the compression stroke across all operational cycles.

development of a zero-dimensional turbulence model for the flow field of spark-ignition engines, considering vortex motions, based on a new approach

in this paper, a novel zero-dimensional (0-d) in-cylinder turbulence model has been developed to account for vortex motions in spark-ignition (si) engines. the flow’s mean kinetic energy is decomposed into two distinct components: directional and non-directional flows. to enhance the physical integrity of the model, a directional production term is introduced based on the principles of in-cylinder rotational energy and angular momentum. the traditional production term associated with tumble kinetic energy is replaced by a non-directional production term. it is postulated that the production of turbulent kinetic energy can be linked to the loss of rotational energy through this directional production term, encompassing the energy changes in vortices when the valves are closed and the angular momentum of intake flow when the valves are open. additionally, the mass flow rate within the cylinder is derived through a one-dimensional (1-d) isentropic flow analysis. to validate the model, experimental investigations are conducted on a natural gas-fueled si engine, which serves as a reference for model development. the developed model demonstrates the ability to predict the key characteristics of turbulent flow and accurately reproduce the variation of related parameters when compared to the results obtained from three-dimensional (3-d) simulations. notably, the model requires only a minimal number of tuning constants that are case-insensitive. furthermore, the results exhibit a high degree of precision near top dead center (tdc) in the compression stroke across all operational cycles.