Aircraft icing aerodynamics: relevant length scales for LES of real and artificial ice shapes
Air Force Research Laboratory
Abstract
Predicting the aerodynamic performance of aircraft in icing conditions is crucial for ensuring flight safety. Modeling icing and its effect on aerodynamics has recently garnered attention in academia and industry due to the changes to the Code of Federal Regulations (CRF) in 2007. These changes require transport-category airplanes to demonstrate equivalent handling and performance in both icing and non-icing conditions. This has motivated airplane designers to include icing effects in the first stage of the design process.
Encouraged by recent studies using LES that demonstrate the ability to predict stall characteristics on full aircraft with smooth wings at an affordable cost (Goc et al. FLOW, 2021), this study seeks to apply this methodology to icing conditions. Using laser-scanned, detailed representations of the icing geometries, as well as artificially generated surfaces, wall-modeled LES calculations are conducted to compare integrated loads against experimental measurements in a variety of icing conditions, including glaze, rime, and scallop ice formations. This lecture will examine the necessary length scales for simulating iced airfoils, emphasizing the importance of resolving key ice shape features for accurate aerodynamic predictions. We will explore scenarios where resolving large-scale features is sufficient, as well as modeling approaches for situations where roughness length scales are sub-grid. The implications of removing some or all roughness scales, as is common with artificial ice shapes, will also be discussed. These modeling efforts provide a roadmap for the application of WMLES in the aircraft icing community and highlight its ability to predict the complex effects of ice shapes on aerodynamic performance.
About the speaker
Dr. Brett Bornhoft is a Research Aerospace Engineer at the Air Force Research Laboratory’s High-Speed Systems Division where he has led efforts on code credibility and compressible multiphase flow modeling. He received his B.S. in Aerospace Engineering Technology from Middle Tennessee State University, his M.S. in Aerospace Engineering from North Carolina State University, and his Ph.D. in Mechanical Engineering from Stanford University working at the Center for Turbulence. He is a recipient of a Department of Defense SMART scholarship. His research focuses on computational fluid dynamics for various applications including compressible multiphase flows, high-speed air-breathing propulsion, aircraft icing, and rough-wall turbulent flows.
