Mass Flow Scaling of Gas-Assisted Coaxial Atomizers

Abstract

This study aims to derive basic principles for liquid mass flow scaling of gas-assisted coaxial nozzles. Four liquid mass flow steps were investigated in the range of M˙liq = 20–500 kg · h−1, applying four atomizers with similar geometry designed at Weaero= const. High-speed camera and phase Doppler anemometer were utilized to detect the local droplet size distribution. To estimate a reliable measurement plane, a detection method and determination according to the free jet theory was used. The resulting droplet size was analyzed, applying the aerodynamic Weber number, as well as the gas momentum flow. An empirical model was derived out of the measured data, which allows for liquid mass flow scaling when process parameters such as GLR, liquid mass flow, and required Sauter mean diameter are specified. The model was developed as a first step towards liquid mass flow scaling of gas-assisted coaxial atomizers within the investigated range of operating conditions.

Optimizing the Auxiliary Air Channels of a Vortex Atomizer by 3D Printing Using the Taguchi Method

“…For comparion, the simulated spray patterns of the atomizers of Case 1 and the optimum case are shown in Figure 12, together with that of the experiment of the optimum atomizer. Figure 12a In comparison, the results of Li et al (2019) [8] give the opening angles of about 32 • (experiment) and 26 • (simulation by Euler-Lagrange method), respectively, and are smaller than the present corresponding findings of 45 • (simulation) and 42 • (experiment). This is expected because the gravity in their case is parallel to the jet axis; hence, the opening angle will be reduced due to down pulling of the gravity.…”

“…Ochowiak et al (2020) [4], for their two-phase conical swirl atomizers, found that the discharge coefficient and spray angle are affected by the Reynolds number, flow rate, and atomizer geometry; Yadav et al (2011) [5] showed that the droplets could be varied by changing the mass ratio of the air to liquid for their internally mixed atomizer; Chinn et al (2015) [6] observed wave patterns in the liquid film of their air-core atomizers, whereas Wang et al (2008) [7] observed flow branching and focusing in their air-assist micro-atomizer. Additionally, Wachter et al (2022) [8] developed a model to scale the liquid mass flow in gas-assisted coaxial nozzles.…”