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This paper presents experimental ice accretion measurements alongside numerical simulations, using the National Research Council Canada’s morphogenetic approach, on a pitot probe geometry at varying icing conditions. In previous publications, the morphogenetic approach for the numerical simulation of ice accretion has shown promise for pitot probe applications, potentially reducing the number of wind tunnel entries, and therefore cost, of the development cycle. An experimental campaign has been completed, providing ice shapes on a representative pitot probe model. Comparison of the experimental and numerical ice shapes indicate that the morphogenetic model is able to generate the complex ice shapes seen experimentally for real-world icing conditions on a fully 3D geometry, closely matching both ice features and total ice thicknesses.

We have developed an original, three-dimensional icing modelling capability, called the “morphogenetic” approach, based on a discrete formulation and simulation of ice formation physics. Morphogenetic icing modelling improves on existing ice accretion models, in that it is capable of predicting simultaneous rime and glaze ice accretions and ice accretions with variable density and complex geometries. The objective of this paper is to show preliminary results of simulating complex three-dimensional features such as lobster tails and rime feathers forming on a swept wing. The results are encouraging. They show that the morphogenetic approach can predict realistically both the overall size and detailed structure of the ice accretion forming on a swept wing. Under cold ambient conditions, when drops freeze instantly upon impingement, the numerical ice structure has voids, which reduce its density.

The intensive deployment of UAVs for surveillance and reconnaissance missions during the last couple of decades has revealed their vulnerability to icing conditions. At present, a common icing avoidance strategy is simply not to fly when icing is forecast. Consequently, UAV missions in cold seasons and cold regions can be delayed for days when icing conditions persist. While this approach limits substantially the failure of UAV missions as a result of icing, there is obviously a need to develop all-weather capabilities. A key step in accomplishing this objective is to understand better the influence of a smaller geometry and a lower speed on the ice accretion process, relative to the extensively researched area of in-flight icing for traditional aircraft configurations characterized by high Reynolds number. Our analysis of the influence of Reynolds number on the ice accretion process is performed for the NACA0012 airfoil.

Over the past few years, we have developed a unique approach to simulate aircraft icing numerically; we call this method morphogenetic modelling. Previously, we developed a successful two-dimensional version of the model; the objective of our present research is to show that the morphogenetic modelling approach can be extended to three-dimensional in-flight icing. In this paper, we focus on the simulation of three-dimensional, discrete rime structures forming on the fuselage of a helicopter. The numerical model consists of three components: an airflow solver, a drop trajectory solver, and a morphogenetic ice growth model. The velocity field of the flow is computed using the Euler equations, while the drop trajectories are computed using a Lagrangian approach. Computation of drop impact locations determines the local collision efficiency distribution. The morphogenetic model deals with the processes occurring on the impinging surface.

This paper discusses, illustrates and validates a novel modeling approach capable of predicting two-dimensional ice accretion on airfoils. The external flow field around a NACA 0012 airfoil is computed using a potential approach with a panel code. In addition to calculating droplet trajectories and impingement locations on the airfoil, the model tracks the behaviour and motion of individual fluid elements on the icing surface. While the envelope of possible behaviour and motion of the elements is constrained by the macroscopic environmental and flight conditions, an intrinsic stochastic variability is present in the model, even under constant external conditions. A partial validation of the model has been successfully accomplished.