Methodology to Analyse Three Dimensional Droplet Dispersion Applicable to Icing Wind Tunnels PDF Download

Author: Sebastiano Sorato
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Languages : en
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Book Description
This dissertation presents a methodology to simulate the dispersion of water droplets inthe air flow typical of an Icing Tunnel. It is based on the understanding the physicalparameters that influence the uniformity and the distribution of cloud of droplets in theairflow and to connect them with analytical parameters which may be used to describethe dispersion process. Specifically it investigates the main geometrical and physicalparameters contributing to the droplets dispersion at different tunnel operativeconditions, finding a consistent numerical approach to reproduce the local dropletsdynamic, quantifying the possible limits of commercial CFD methods, pulling out theempirical parameters/constant needing to simulate properly the local conditions andvalidating the results with calibrated experiment. An overview of the turbulence and multiphase flow theories, considered relevant to theIcing Tunnel environment, is presented as well as basic concepts and terminology ofparticle dispersion. Taylor?s theory of particle dispersion has been taken as startingpoint to explain further historical development of discrete phase dispersion. Commonmethods incorporated in commercial CFD software are explained and relativeshortcomings underlined. The local aerodynamic condition within tunnel, which arerequired to perform the calculation with the Lagrangian particle equation of motions, are generated numerically using different turbulent models and are compared to thehistorical K-? model. Verification of the calculation is performed with gridindependency studies. Stochastic Separated Flow methods are applied to compute theparticle trajectories. The Discrete Random Walk, as described in the literature, has beenused to perform particle dispersion analysis. Numerical settings in the code are relatedto the characteristics of the local turbulent condition such as turbulence intensity andlength scales. Cont/d.