Numerical Simulation of Supercooled Large Droplet Icing Phenomenon: A Review
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ORIGINAL PAPER
Numerical Simulation of Supercooled Large Droplet Icing Phenomenon: A Review Yihua Cao1 · Miao Xin1 Received: 28 January 2019 / Accepted: 25 June 2019 © CIMNE, Barcelona, Spain 2019
Abstract The impingement and ice accretion of supercooled large droplets (SLD) on the aircraft surface is one of the crucial factors threatening flight safety. The movement and impingement of SLD have many unique characteristics that conventional small droplets do not own. Therefore, a large number of experimental and numerical studies about SLD have been carried out to explore its physical properties and simulation method. The distribution and motion characteristics of supercooled large droplet during the process of approaching to the aircraft are first reviewed in this paper. Then the governing equations of SLD under the framework of Lagrangian and Eulerian methods are analyzed and established. The unique phenomena of SLD such as water droplet deformation and breakup, droplet–wall interaction and re-impingement in the literature are analyzed. The research development and results of the droplet–wall interaction phenomenon have been discussed particularly, which is summarized and classified from three aspects: droplet splashing threshold, splashing model and the method of modification of governing equation. Finally, the establishment process and the corresponding modification of the icing model in SLD condition is given, and the related calculation results are exhibited to validate the numerical simulation methods of SLD. Some shortcomings in current research are presented and the aspects needed to be developed further in future studies for the acquisition of more accurate simulated results are also recommended. List of Symbols Re Reynolds number; 𝜌Vd∕𝜇 (−) Red Droplet Reynolds number (−) Res Splashing Reynolds number (−) We Weber number; 𝜌V 2 d∕𝜎 (−) Web Breakup Weber number (−) Wecrit Critical Weber number (−) Wes Splashing Weber number √ (−) √ Oh Ohnesorge number; 𝜇∕ 𝜌𝜎d = We∕Re (−) Ga Galilean number (−) Ca Capillary number (−) La Laplace number (−) V Velocity vector (m/s) d Diameter of droplet (μm) g Acceleration of gravity (m/s2) Vt Terminal speed (m/s) Vslip Slip velocity of the droplet (m/s) CD Drag coefficient (−)
* Miao Xin [email protected] 1
School of Aeronautic Science and Engineering, Beihang University, Beijing 100191, China
CDsphere Drag coefficient of non-deforming spherical droplet (−) CDsteady Drag coefficient for a solid sphere in steady state flow (−) u Velocity component in the x direction of the coordinate system (m/s) v Velocity component in the y direction of the coordinate system (m/s) w Velocity component in the z direction of the coordinate system (m/s) md Mass of droplet (kg) Ad Cross section area of droplet (m2) f Eccentricity function (−) F External force (N) x1 Displacement of the droplet from its equilibrium position (m) y1 Dimensionless displacement of the droplet from its equilibrium position (−) Cb Dimensional constants in TAB model (−) K1 Ratio
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