積冰現象之空氣動力特性分析-以ATR-72 為例

Abstract

The Trans Asia Airway flight GE-791, an ATR-72 airplane encountered ice accretion to crash at Peng Hu Island, Taiwan, December 21, 2002, was the first ice accretion accident case ever in Taiwan. This thesis is based on Aviation Safety Council accident report, and taking GE791 as the case for numerically simulating aerodynamic coefficients of main wing and horizontal tail under several two-dimensional icing conditions. This study uses existing CFD method to predict the ice accretion on airfoil. First step is the generation of unstructured grid on the wing and tail configurations. Secondly, solve Navier-Stokes equation with finite volume method. Finally, the equation of motion for supercooled water droplets is implemented for ice accumulation production on the airfoil leading edge locations. Considering the ATR-72 has distinctive T-tail shape, it is assumed that the tail will not influenced by the main wing trailing vortices, thus the glaze ice and clear ice can be simulated under proper atmospheric conditions. The two-dimensional iced airfoil shapes are achieved, and the results are extended to three-dimensional and then IV use the flight mechanics software DATCOM to analyze the aircraft performance behavior. According to the above research, in two-dimensional the airfoil ice shape is more anomalous; their lift coefficients will hastily decreasing and drag coefficient will increase. In addition, the ice accretion phenomenon will cause the horizontal tail to stall ahead of time. When tail stalls, this downward force is lessened or removed, and nose of the airplane can severely pitch down, this leads to threaten of flight safety and is the major cause of ATR-72 accident. On the other hand the DATCOM is an aircraft preliminary design tool, so it has error in analyzing complicated ice shapes. There are still major rooms for improvement in prediction of actual airplane flight performance through this software.