The present work experimentally investigates the near and far-field centricity dynamics of a hollow cone spray in an un-confined,co-annular isothermal swirling air jet environment.A Particle/Droplet imaging analysis(PDIA)technique was employed to study the underlying physical mechanisms involved in variation of centricity as function of swirl strength.The experiments were conducted using an axial-flow hollow cone spray nozzle having a 0.5 mm orifice.The nozzle injection pressure was maintained at PN = 1 bar,corresponding to a Reynolds number ReN = 7500.At this setting,the operating Reynolds number of the co-annular swirling air stream(ReS)was increased progressively in the range 1600-5600.Swirl was imparted to the co-axial flow using a guided vane swirler with blade angle of Ф=45°(corresponding geometric swirl number SG = 0.8).The spray is subdivided into two zones axially:(1)near-field(y=4 cm)where liquid sheet just starts to break into ligament or eccentric droplets and(2)far-field locations(y= 10 cm)zone that starts immediately after complete primary atomization has been accomplished.Measurements were made in the spray in both axial(near-field and far-field)and radial directions indicates that,both average centricity(χ)of the droplets and overall droplet distribution in radial direction is highly reliant on swirl strength.The analysis shows that,at near-field location non-spherical droplets formed because of aerodynamic shear between liquid-gas interfaces whereas at far-field variation in the average centricity is predominantly due to dispersion and collision of the droplets.