Experimental Study on Jet Breakup Morphologies and Jet Characteristic Parameters of Non-circular Nozzles under Low-intermediate Pressures

Abstract

Abstract. A High-Speed Photography (HSP) technique was used to investigate the breakup process and flow behavior of low-intermediate pressure water jets issued from square and triangular shaped nozzles. The non-circular orifices were designed based on the principle of equal flowrate with the same pressure in relation to the circular orifice. The breakup morphologies and boundary structures of the jets were studied under different nozzles and working pressures. Two forms of droplet formation and the process of droplet formation, in addition to the jet breakup lengths, initial amplitudes of surface waves and jet diffusion angles of different nozzles were evaluated. It was found that the jet presented a good continuity and fluidity in the initial section, and the fluid bands gradually appeared due to the air resistance and the jet break up as the disturbance intensifies. The degree of jet breakup was enhanced with the increase of pressure and cone nozzle angle. The random appearance of the fluid band structures and the dactylitic textures near the nozzles for non-circular jets appeared earlier than those produced by the circular jets. The small satellite droplets with different shapes and sizes were seen inside and outside the jet interface. Triangular jets exhibited the shortest breakup length, the initial amplitude of surface wave, and the diffusion angle of the jet at the same pressure were largest compared with square and circular jets. Two index equations of jet characteristic lengths and equivalent diameters of both circular and non-circular nozzles were fitted with a relative error of less than 10%, which means the fitting formulas are accurate. Keywords: Breakup length, High-speed photography, MATLAB simulation, Non-circular nozzle, Surface wave amplitude.

A Spraying Model of Non-atomizing Sprinkler based on Jet Fragmentation

“…Different values of Lb are used to determine the landing position of water droplets and the resulting wetting patterns (Jiang et al 2018). Lb is measured through laser-induced fluorescence (LIF) (Charalampous et al 2009a,b) or is estimated photographically (Jiang et al 2019;Sridhara and Raghunandan 2010). There are several prediction equations for Lb presented in literature based on experimental investigations (Broumand et al 2017;Engelbert et al 1995;Eroglu et al 1991;Lasheras et al 1998;Leroux et al 2007;Porcheron et al 2002).…”

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“…For a given nozzle, the VMD of the droplets was related to the spray pressure and flowrate of the liquid (Jiang Y. et al, 2019). Based on this information, Kang obtained the relationship between the average VMD of the atomization field and spray pressure (Kang F et al, 2018).…”