‌Experimental and image processing study on the effect of the cavitation phenomenon in a nozzle injector on the hydrodynamic behavior of the spray

Document Type : Research Article

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Department of Mechanical Engineering, University of Tabriz, Tabriz, Iran

Abstract

The hydrodynamic behavior of liquid spray is influenced by the geometry of the injector nozzle, which has a significant impact on the combustion process and quality of fuel atomization. As a result, this has a consequential impact on the decrease of pollutant emissions. In this survey, transparent and visible nozzles were fabricated from Plexiglas to facilitate experimental visualization of the nozzle interior and enhance the accuracy of liquid spray investigation. To achieve this, three types of nozzles with varying orifice coefficients were prepared. Results showed that at a certain pressure, the nozzle with k factor equal with -0.25 (divergent conical nozzle) the intensity of cavitation increases and it’s very prone to cavitation. Conversely, the nozzle with k factor equal with 0.25 (convergent conical nozzle) suppresses cavitation. As the pressure of fluid injection rises within nozzles, cavitation bubbles persist until reaching the orifice's end, resulting in super-cavitation phenomenon. Further increasing of injection pressure triggers the hydraulic flip phenomenon. The occurrence of the super-cavitation phenomenon causes uniform droplet distribution of the resulting spray. At a certain injection pressure with decreasing k factor outlet volume flow rate of the nozzle decreases and the spray cone angle increases. Therefore, the desired macroscopic characteristic of the spray could be determined by specifying the k factor.

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AUT Journal of Mechanical Engineering
Volume 8, Issue 1
March 2024
Pages 6-6

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