Numerical simulation of aircraft icing with an adaptive thermodynamic model considering ice accretion

Abstract

The icing phenomenon is one of the most undesirable events in aircraft. We may see this phenomenon from different points of view. The safety of flight is undoubtedly the biggest concern of designers, nowadays. The icing causes the malfunctioning or even failure of the pressure and speed measurement devices, and consequently make difficulties for controllability of the flight. Icing in rudder, ailerons, and elevators can also make control of aircraft even impossible. During landing, the icing on the pilot window along with possible failures in the landing gears may cause major catastrophes. Besides, detachment of ice particles can cause serious mechanical damage to the aircraft when they collide with the body or sometimes with internal parts such as compressor blades. The other point of view is the degradation of the performance of aircraft, and consequently the increase of fuel consumption because of icing. Icing affects the aerodynamics of an airplane in an undesirable way and puts the aircraft in a situation that is far from what the aircraft is designed for. Therefore, it is necessary to study aircraft icing to provide a safer and more efficient flight. Since the icing in aircraft is of great importance, a precision analysis of this phenomenon should be performed. Tests in the wind tunnel and during the flight are very expensive. On contrary, the numerical-computational simulations can be cost-effective for studying aircraft icing. In the present study, the numerical-computational simulation of aircraft icing has been performed by writing a computer-code via FORTRAN. The computational simulation of aircraft icing is a modular procedure consisting of the grid generation, air solver, droplet solver and ice accretion modules. First, the computational domain is generated via elliptic grid generation. The differential methods based on the solution of the elliptic equations are commonly used for generating of the mesh for a geometry with arbitrary boundaries. Elliptic equations are also utilized for the unstructured grids. The most popular elliptic equation is the Poisson equation, which gives the wonderful possibility to satisfy smoothness, fine spacing, and orthogonality on the body surface by means of the controlling terms. Then, the velocity and pressure distributions of airflow around the wing have been found, and the convective heat transfer coefficient on the body will be calculated. The inviscid flow model has been selected in our simulation because it needs less effort and time in comparison with the Navier-Stokes codes. The two-dimensional, steady-state, inviscid, incompressible, irrotational flow (potential flow) model has been applied for solving airflow.