ID 168

Co-Field Simulation of the Internal Flow Field and Jet Spray Characteristics of an Internal Oscillating Nozzle

 

Abstract:

Nozzle internal structure has been well proven to be a key influence factor of the jet spray characteristics. In this paper, a numerical investigation is performed based on a low pressure internal oscillating nozzle which simultaneously considers the internal flow field and the jet spray part within the same computational field. A co-field simulation model has been proposed and validated, and the simulation accuracy is proven to be sensitive to the grid setup. The numerical results have shown excellent consistency with experimental data captured with Schlieren photography. Both the numerical and experimental results have shown that the spatial flow distribution of the spray presents a bi-modal distribution form due to its fixed-frequency jet oscillation. The investigation indicates that the jet oscillation phenomenon is caused by Coanda effect that generated by the intentionally designed nozzle internal structure. Parameter analysis has been conducted to determine the relationship between the spray characteristics and some key influence factors. The results demonstrate that there is a linear relationship between the nozzle exit mass flow rate m ̇ and the injection pressure P (m ̇ =2.8193P+3.0452), and the oscillating frequency f is also proportional to the injection pressure P (f = 46.969P + 103.42). An increase in flow passage wall angle will increase the oscillation amplitude and period, and therefore lead to a decrease of the oscillation frequency. When wall angle increases from 25° to 29°, the mass flow ratio of the middle low flow area rises from 38% to 52%.