Effect of Liquid/Gas Density Ratio on Primary Jet Breakup of Pressure Swirl Atomizer: Experimental and Numerical Study

Abstract

This work reports experimental and numerical study of primary jet breakup of a pressure swirl atomizer. Experiments were performed in a constant volume spray chamber and the spray pattern was characterized as a function of different liquid/gas density ratios which was achieved by changing the ambient pressure. The liquid/gas density ratio was varied between ≈ 102 to 103 and the axial Reynold number was maintained at 6 × 103. Diffused backlight imaging in conjunction with high speed videography was used to visualize the spray. Parameters like spray cone angle, spray breakup length and flapping frequency was estimated. Additionally, POD analysis was performed to find the sheet instability modes. A corresponding numerical study using Coupled Level Set VOF method was performed keeping the liquid/gas density ratio of 10 and 102 to simulate the primary jet breakup using an in-house two-phase solver developed using OpenFOAM libraries. The solver was validated by following the numerical work of Fuster et al. Effect of computational mesh size on parameters like spray cone angle, breakup length was estimated.

Assessment of Primary Breakup of Liquid Sheet Emanating from a Pressure Swirl Atomizer for Non-Newtonian Fluids

“…The base case test matrix is shown in Table 4 which is defined by 8 independent parameters of which 7 are altered and discussed in the later sections. The chosen parameters are based on a commercially available PSA nozzle and used in a previous experimental study [17]. The mesh is generated with nonuniform cells with an expansion ratio of 5 and /∆ = 60 such that for the first cell width at ~10 ~0.5.…”

“…The reduction in dissipation energy by reducing viscosity of liquid for shear thinning fluid also increases the spray cone angle and breakup length and vice versa for shear thickening fluid. Breakup length and spray cone angle are calculated from the post processing tools which utilizes the similar techniques as described in [17]. Orifice data are extracted for more than 100 time steps to estimate film thickness and orifice velocity.…”