Multi-Stepping Ice Prediction on Cylinders and Other Relevant Geometries

Abstract

Predicted ice shapes obtained with a fully automated multi-stepping procedure implemented in the ice prediction code ICECREMO2 are discussed in this paper. Several multi-step algorithms are used to generate ice layers on cylinders in rime and glaze ice conditions. Although all multi-step algorithms produce acceptable rime ice results, a multi-step approach based on an ice height criterion appears as the most efficient method for glaze ice predictions. The outcome is compared with results obtained for a NACA0012 airfoil geometry. The influence of the un-iced substrate shape is investigated, general restart criteria for multi-step height-based icing codes are presented and discussed.= ice layer thickness, m b max = maximum ice thickness allowed per step, m c = chord or diameter length, m c i = specific heat capacity of ice, J · kg −1 · K −1 d d = droplet diameter, m g = acceleration due to gravity, m · s −2 h = water layer thickness, m L = typical length of the geometry, m LWC = cloud liquid water content of air, kg · m −3 n step = number of steps P a = ambient pressure, Pa Q x = x component of the water flux, m −2 · s −1 Q y = y component of the water flux, m 2 · s −1 T = temperature in the ice layer, K T ∞ = freestream temperature, K t = time, s t exp = exposure time, s V ∞ = freestream velocity, m · s −1 X = ratio of ice height to chord length β = collection efficiency θ = temperature in the water layer, K κ i = thermal conductivity of ice, W · m −1 · K −1 κ w = thermal conductivity of water, W · m −1 · K −1 μ i = dynamic viscosity of ice, kg · m −1 · s −1 μ ω = dynamic viscosity of water, kg · m −1 · s −1 ρ i = density of ice, kg · m −3 ρ w = density of water, kg · m −3 τ x = x component of shear stress, Pa τ y = y component of shear stress, Pa

Numerical simulation of ice accretion under mixed-phase conditions

“…A film will be present on the surface of the ice layer, and ice crystals can adhere to it. _ m imp,cryremain is determined using the impinging model, then _ m ice,c can be obtained using equations (5), (7), and (8). (c) If F d 4 0, the film will appear, and the iced mass flux ( _ m ice,c ) is obtained from equations (5), (7), and (9).…”

“…Methods to simulate icing for water droplets have been developed for ice accretion on an airfoil, windward, and other frontal components. 6–9 However, mixed-phase icing is different from water droplet icing. First, the ice crystals have a greater mean volume diameter (MVD), which may be up to 200 µm.…”

Numerical and experimental investigations into protection net icing at the helicopter engine inlet

“…Compared with the icing wind tunnel experiment, icing simulation has the advantages of lower cost and faster speed. Numerical simulation on icing have been widely studied for many years (Du et al , 2010; Verdin and Charpin, 2013; Pouryoussefi et al ,2016; Raj et al , 2019). With the machine learning theory, the icing on the NACA0012 two-dimensional (2D) wing surface with the combination method of wavelet packet transform and artificial neural networks was calculated by using neural network and wavelet transfer (Chang et al , 2016).…”