Turbulent flow investigation inside and outside plain-orifice atomizers with rounded orifice inlets

摘要

The performances of three linear eddy viscosity models (LEVM) and one algebraic Reynolds stress model (ARSM) on the simulation of the internal and external flows in the plain-orifice atomizers with rounded orifice inlets are evaluated. The validity of the computational model is first assessed through the testing of a backward facing step flow, a sudden expansion pipe flow and a liquid column collapsing problem. Then the atomizer internal and external flows are analyzed by comparing the computed discharge coefficients with available experimental data and by comparing the turbulence intensity profiles at the orifice exit. The results are also illustrated by the fluid/air interface plot. It is found that the turbulence models investigated exhibit zonal behaviors, i.e., none of the models investigated performs well throughout the entire flow field. It is worthwhile to note that the standard k-∈ model is not necessarily the worst among the models investigated. In average, the ARSM model gives better results as compared to the standard k-∈ model and the low Reynolds number models. The turbulence strength has a significant influence on the global characteristics of the flow field. The models with better predictions of the turbulence kinetic energy, such as Gatski-Speziale's ARSM model and Nagano-Hishida's low Reynolds number model, can yield better predictions of the global characteristics of the flow field, e.g., the reattachment lengths for the backward-facing step flow and the sudden expansion pipe flow, and the discharge coefficient for the atomizer flow.