Atomization Mechanism of Internally Mixing Twin-Fluid Y-Jet Atomizer

Abstract

The atomization mechanism of the gas-liquid multiphase flow through internally mixing twin-fluid Yjet atomizer has been studied by examining both the internal and external flow patterns. Superheated steam and Light Fuel Oil (LFO) are used as working fluids. The flow is numerically modeled using the compressible Navier-Stokes equations; hybrid Large Eddy Simulation approach through Wall Modeled Large Eddy Simulations (WMLES) is used to resolve the turbulence with the Large Eddy Simulations, whereas the Prandtl Mixing Length Model is used for modeling the subgrid-scale structures, which are affected by operational parameters. VOF-to-DPM transition mechanism is utilized along with dynamic solution-adaptive mesh refinement to predict the initial development and fragmentation of the gas-liquid interface through Volume-of-Fluid (VOF) formulations on a sufficiently fine mesh, while Discrete Phase Model (DPM) is used to predict the dispersed part of the spray on the coarser grid. Two operational parameters, namely gas-to-liquid mass flow rate ratio (GLR) and liquid-to-gas momentum ratio are compared; the latter is found to be an appropriate operational parameter to describe both the internal flow and atomization characteristics. It is confirmed that the variation in the flow patterns within the mixing-port of the atomizer coincides with the variation of the spatial distribution of the spray drops.

Asymmetric Spray Characteristics According to Y-Jet Nozzle Orifice Shape and Spray Conditions

“…Nazeer et al 21 the GLR. 22 Zhou et al 23 conducted an experimental study on a Y-jet nozzle and reported a better internal flow pattern by predicting the droplet size distribution according to the GLR. It is essential to consider the internal flow mechanism of the fluids since a twin-fluid nozzle has a two-phase flow.…”

Investigation of Oil Droplet Breakup during Atomization of Emulsions: Comparison of Pressure Swirl and Twin-Fluid Atomizers

“…In this case, the kinetic energy of the gas is transferred to the slowly moving liquid [13]. In twin fluid nozzles the air-to-liquid mass flow ratio (ALR) is used to characterize the energy input [18,19]. In contrast to PS nozzles, the process conditions of the atomization gas can be used to control the resulting spray droplet size independently from the liquid throughput.…”

“…In the IM configuration, a high-velocity gas and the liquid are mixed inside the nozzle before the discharge orifice [16,18]. In IM atomizers, energy is transferred from the gas to the liquid in form of shear stresses, which induces instabilities in the liquid stream leading to dispersion of the liquid [18,19,21].…”

“…In the IM configuration, a high-velocity gas and the liquid are mixed inside the nozzle before the discharge orifice [16,18]. In IM atomizers, energy is transferred from the gas to the liquid in form of shear stresses, which induces instabilities in the liquid stream leading to dispersion of the liquid [18,19,21]. An example of IM atomizer is the air-core-liquid-ring (ACLR) nozzle [22], in which an air core is established, surrounded by an annular liquid ring within the exit orifice of the nozzle (Figure 1c).…”

“…An example of IM atomizer is the air-core-liquid-ring (ACLR) nozzle [22], in which an air core is established, surrounded by an annular liquid ring within the exit orifice of the nozzle (Figure 1c). Recent studies have demonstrated that internal flow patterns and specifically the circumferential liquid film thickness within the mixing chamber are determinant for the spray characteristics in film-forming IM nozzles [18,23]. In contrast to the vast variety of internal mixing nozzles, the ACLR nozzle allows controlling the liquid lamella thickness at the nozzle outlet [22,24].…”