Abstract

Ice accretion on aeroplane surfaces is one of the most severe weather threats to aviation safety. By changing the gross shape of the airfoil and adding surface roughness, ice accretion leads to increased drag and reduced lift at a constant angle of attack. Typically, an Ice Protection System (IPS) protects the critical aerodynamic surfaces. However, ice accreted on unprotected surfaces affects aircraft performance and flight characteristics in some flight phases. Since the formation of different phenomena like rivulets, water runback, and ice ridges is probable, a better understanding of the underlying physics of these complex phenomena is highly desired for both safe and efficient aircraft operation, and better design approaches. Therefore, having an advanced experimental technique capable of quantifying and characterising the amount of water or ice will be of high interest.
In the present study, a novel Colour-Coded Point Projection (CCPP) method is proposed. Using a multi-colour pattern has never been reported in the literature. After calibration and validation, the limitations and characteristics of the proposed method were defined. It can provide three times thickness measurement range at the same planar resolution, in comparison with other similar methods. Various experiments were conducted to investigate the rivulet and ice formation over a NACA 0012 airfoil in the icing wind tunnel available at Concordia University at controlled conditions. The thickness profiles of rivulets and accreted ice were measured successfully and, therefore, the capability of the proposed method was proved. Different criteria, like chord-wise thickness, ice growth rate, advancement speed of ice limit, and the rate of water collection, were defined to compare the effect of working conditions, like velocity, temperature and surface, on the behaviour of rivulets and ice accretion. The results showed that the proposed method is a valuable tool for on-line ice thickness measurements in an icing wind tunnel.