Performance Comparison of Commercial CFD Codes for Steady-State Internal Flow Simulation of Gasoline Direct Injection

Abstract

A performance comparison of commercial CFD codes used for single-phase steady-state simulation of the internal flow within gasoline direct injection (GDI) nozzles has been undertaken. The CFD software codes used include AVL Fire 7.3, AVL Fire 8.01 and CFX-TASCflow 2.11. This presents a mix of segregated and coupled solver technology. High-pressure multi-hole and swirl injector models were analyzed at constant needle-lift values. The comparison focused on software capability, quality and steadiness of solution, calculation time taken, and the ability to streamline the problem solving methodology. Quantitative experimental results were not considered in the analysis due to the numerical nature of the investigation. It was seen that each CFD code produced similar flow fields and overall mass-flows. Results indicated that the steady-state solvers (Fire 8.01 and TASCflow 2.11) were able to decrease computation time significantly, by factors of 2 to 10 compared with the transient time-marching solver Fire 7.3. Further, TASCflow 2.11 was seen to be most appropriate for steady-state internal flow GDI simulations as it resolved the flow fields much quicker than the other codes due to a coupled solver. The multi-hole injector was seen to exhibit steady behavior using each CFD code, while the swirl injector presented some oscillations in the flow field, particularly for TASCflow 2.11. However, the use of single-phase steady-state solvers were found to be highly useful for engineering development of GDI, as it provides engineers with a quick parametric snapshot of the flow behavior, and can aid in the prediction of fuel spray patterns.