Effect of Low Ambient Pressure on Spray Cone Angle of Pressure Swirl Atomizer

Zhengyan Guo,Xiaomin He,Di Wu,Yunbiao Wang,Kanghong Yao,Yi Jin,Mei Zheng,Kai Zhang,Jiaqiang E

doi:10.1155/2021/5539231

Abstract

Pressure swirl atomizers are widely used in gas turbine combustor; this paper is aimed at researching the effect of low ambient pressure (0.1 MPa to 0.01 MPa, lower than an atmosphere) on the spray cone angle of pressure swirl atomizer. The spray angle is captured by high-speed photography; then, an image post program is used to process the spray angle magnitude. A mathematical model of a single droplet’s movement and trajectory based on force analysis is proposed to validate the spray angle variation. The maximum variation of the spray cone angle, which is observed when fuel supply pressure drop through the atomizer is 1 MPa as the ambient pressure decreases from 0.1 MPa to 0.01 MPa, is found to be 23.9%. The experimental results show that the spray cone angle is expected to increase with the ambient pressure decrease; meanwhile, mathematical results agree well with this trend.

Highlights

Pressure swirl atomizers are widely used in liquid rocket engines, internal combustion engines, and aircraft engines; it has unique advantages over other atomizers
Chen et al [5] studied the initial tip structure evolution of diesel fuel spray under various injection and ambient pressures experimentally and numerically; the results show that (1) the ambient pressure exhibited a significant impact on the maximum size of the observable droplets and (2) the spray penetration decreased by approximately 10% with the increment of 0.5 MPa in ambient pressure, while increased by about 9% with 10 MPa injection pressure increment
Chen et al [12] studied the spray characteristics of swirl atomizer by using a high-speed shadowgraph system under high ambient pressure; the results show that spray is suppressed by ambient pressure, a critical pressure value was found at which the spray structure converts from a wide hollow cone to a narrow contracting bell, and the discharge coefficient increases while the spray cone angle decreases

Summary

Introduction

Pressure swirl atomizers are widely used in liquid rocket engines, internal combustion engines, and aircraft engines; it has unique advantages over other atomizers. There are two parts affecting the spray angle: one is the geometry of the atomizer self; another is the ambient pressure that fuel is injected into [2]. A large number of works have been conducted focusing on the spray cone angle of pressure swirl atomizers about those parts. About the influence of the geometry structure, Rizk and Lefebvre [3] studied the effect of different structural parameters on the spray cone angle for a single swirl atomizer, within which the influence of ambient gas pressure on the spray cone angle is not involved. Shim et al [4] conducted a numerical and experimental study of the spray characteristics of a high-pressure swirl injector at ambient pressures. The spray cone angle, discharge coefficient, breakup length, and velocity distribution were

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