Author(s): Anton Kulyakhtin; Laszlo Kollar; Sveinung Loset; Masoud Farzaneh
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Abstract: This paper presents a 3D air-dispersed water flow model developed to simulate the spray flow that is responsible for ice accretion when water reaches a cold surface. Modelling the spray dynamics and the processes inside the cloud to determine such spray characteristics as the droplet size distribution (DSD) and liquid water content (LWC), is essential for predicting ice accretion in nature and in laboratory. The model used in this study is constructed in ANSYS FLUENT using built-in tools. It includes airflow field simulation using the Eulerian approach and the Lagrangian simulation of droplet flow. The applied model neglects the thermodynamics of the spray but considers the influence of the flow field on the spray and the interdroplet interactions based on O'Rourke's algorithm. O'Rourke's algorithm is a stochastic computationally efficient, but mesh- and discretisation-dependent, approach. The model is applied to simulate spray flows produced in the CIGELE atmospheric icing research wind tunnel of the University of Quebec at Chicoutimi, Canada. The application of O'Rourke's algorithm is discussed for the particular case of droplet flow in this wind tunnel. The modelled spray had a median volume diameter (MVD) of approximately 30 um and an LWC of approximately 1 g/m3 in the test section of the tunnel. The modelled processes also include spray focusing in the tunnel contraction. The simulation results are compared with available experimental data that include the DSD and the LWC of the spray in a few points in the same tunnel. Sensitivity studies are also carried out to investigate the influence of the flow field properties, initial spray conditions and their uncertainty on the spray DSD and LWC. The investigation focuses on the variation of initial spray patterns and the accuracy of the velocity and turbulence simulations.
Year: 2012