Numerical Simulation of the Anti-Icing Performance of Electric Heaters for Icing on the NACA 0012 Airfoil

Abstract

Ice accretion is a phenomenon whereby super-cooled water droplets impinge and accrete on wall surfaces. It is well known that the icing may cause severe accidents via the deformation of airfoil shape and the shedding of the growing adhered ice. To prevent ice accretion, electro-thermal heaters have recently been implemented as a de- and anti-icing device for aircraft wings. In this study, an icing simulation method for a two-dimensional airfoil with a heating surface was developed by modifying the extended Messinger model. The main modification is the computation of heat transfer from the airfoil wall and the run-back water temperature achieved by the heater. A numerical simulation is conducted based on an Euler–Lagrange method: a flow field around the airfoil is computed by an Eulerian method and droplet trajectories are computed by a Lagrangian method. The wall temperature distribution was validated by experiment. The results of the numerical and practical experiments were in reasonable agreement. The ice shape and aerodynamic performance of a NACA 0012 airfoil with a heater on the leading-edge surface were computed. The heating area changed from 1% to 10% of the chord length with a four-degree angle of attack. The simulation results reveal that the lift coefficient varies significantly with the heating area: when the heating area was 1.0% of the chord length, the lift coefficient was improved by up to 15%, owing to the flow separation instigated by the ice edge; increasing the heating area, the lift coefficient deteriorated, because the suction peak on the suction surface was attenuated by the ice formed. When the heating area exceeded 4.0% of the chord length, the lift coefficient recovered by up to 4%, because the large ice near the heater vanished. In contrast, the drag coefficient gradually decreased as the heating area increased. The present simulation method using the modified extended Messinger model is more suitable for de-icing simulations of both rime and glaze ice conditions, because it reproduces the thin ice layer formed behind the heater due to the runback phenomenon.

Evaluation of Anti-Icing Performance for an NACA0012 Airfoil with an Asymmetric Heating Surface

“…In addition, we confirmed a reasonable agreement of the ice shape between the present simulation and the experiment [36]. The bump shape was confirmed against our previous study [29] Figure 10 shows the streamline around the airfoil in the heating case of x hs = 16 and x hp = 16. The flow separation is observed downstream of the bump ice on both sides, and it is significant on the suction side.…”

“…In the present study, we perform icing simulations for the NACA0012 airfoil with surface heating, aiming to improve the heating effect further and extending the result of our previous work [29]. To prevent icing, the airfoil surface maintains a constant temperature, which is higher than the freezing temperature.…”

“…We note that the computational grid is regenerated without smoothing the ice shape because smoothing affects the icing location. The numerical procedure is explained in detail in a previous paper by the authors of this paper [29]; nonetheless, here we provide a brief outline of it as follows.…”

“…In our previous study [29], we employed a heater to prevent icing from occurring on a NACA0012 airfoil and investigated the effect of the heating area on the ice shape and aerodynamic performance via numerical simulations. To consider the heat flux from the heater, we modified the extended Messinger model (referred to as modified EMM; MEMM) to compute the ice growth.…”

Experimental Heat Loads for Electrothermal Anti-Icing and De-Icing on UAVs

“…An IPS can generally be operated in two different modes [11]: anti-icing and de-icing. In anti-icing mode, the surface of the airfoil is heated continuously to avoid any ice accretion at any time [12]. In de-icing mode, the surface is heated periodically, allowing for ice to build up in between the heating cycles.…”