Computational Methods for Rotorcraft Icing

Download or read book Computational Methods for Rotorcraft Icing written by Habibollah Fouladi and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Modern helicopter operations may require flying in icing conditions for long periods, resulting in performance degradation and exposing the aircraft to severe vibration or damage. Computational icing tools are not only useful in the IPS design of a rotorcraft, but also in icing certification process; however, the rotorcraft icing lags in development over its counterpart, the fixed-wing aircraft icing, since it poses additional significant challenges. One of the main objectives of the current study is to bring the rotorcraft aerodynamics and icing CFD tools to develop and validate high-fidelity multidisciplinary numerical methodologies for the prediction of ice accretion on different part of rotorcraft. First, a quasi-3D and -steady method is proposed to predict ice accumulation on a rotor blade for a helicopter hovering in an icing cloud. This approach is applied to the UH-1H helicopter, exposed to the icing condition of the Helicopter Icing Flight Test Program. Second, a quasi-unsteady simulation methodology for prediction of ice accretion on oscillating airfoils with varying angles of attack is proposed, as required for forward flight condition. Unlike the quasi-steady approach, this methodology can largely improve the prediction of unsteady ice shapes and better preserve the unsteady characteristics of air, droplet and ice accretion, in the absence of a truly unsteady simulation with prohibitive computational cost. This approach has been tested on the oscillating airfoils from the icing tests on oscillating SC2110 airfoil in NASA Glenn IRT. Third, a methodology for the steady state simulation of helicopter fuselage icing is introduced. An actuator disk rotor model is employed, representing the actual rotor effects on the airflow around fuselage. This methodology is much more affordable than a fully unsteady simulation, and is shown to be practical, reliable, and versatile for predicting the location and thickness distributions of accreted ice on a helicopter fuselage. For all three abovementioned methodologies, the results have good agreement with experimental data. Another main objective of this research is to study the effect of important parameters on rotorcraft icing and the resultant aerodynamic performance degradation. Using the methodologies introduced in this dissertation, the effect of different parameters such as forward flight velocity, local incident velocity, angle of attack, ambient temperature, liquid water content, median volumetric diameter, ice density, and surface roughness on droplet impingement and ice accretion on different parts of helicopter (rotor blade and fuselage) in hovering and forward flight conditions are investigated, and corresponding aerodynamic performance degradations (loss of lift, drag increase, decrease of stall angle) are calculated and discussed. " --