Investigation of the physical processes underlying the ice accretion phenomena

Abstract

The objective of the present paper is to describe the lessons learned from three icing tests undertaken by Canadair at the NASA-Lewis icing tunnel. The ice accretion characteristics were calculated for the Global Express wing section (slats and flaps retracted) at three angles of attack representing light, medium and heavy weights for holding configuration and two droplet sizes corresponding to the lower and upper limits from conditions specified in Appendix C of FAR-25. The model design procedure has several unique features due to the interdisciplinary character of the problem. A detailed description of the process which leads to the selection and instrumentation of a wing section model is presented. The ice prediction code used, CANICE, was validated through comparison with experimental results and the NASA-Lewice Beta version of the code. The experimental measurement methods used in the icing tunnel are described as well as the icing conditions that can be established in the NASA-Lewis icing tunnel, and its limitations on a typical icing test for a real aircraft. Details of a typical ice catch test are discussed in terms of expected accuracy and repeatability of a test point. Ice density measurements in the icing tunnel are presented and compared to natural ice densities. Observations and measurements pertinent to the character of rime, glaze and mixed type ice are reported that could benefit modeling ice accretion. The use of ice catch and thermodynamic analysis in anti-icing system design and certification is discussed.