面向自然结冰试飞评估的冰形增长规律

飞机自然结冰试飞是民机适航取证中的关键点之一。由于试飞的高风险和成本,掌握冰形积聚的规律对指导试飞开展及飞行安全研究有重要意义。本文通过数值模拟研究了不同环境条件下二维翼型的冰形生长过程,重点分析了结冰环境水滴粒径和温度对冰形高度增长规律的影响,并结合水滴收集率随积冰高度的变化趋势分析了冰高增长速度变化的机制。结果表明,飞机二维冰形高度的增长有线性和减速两种基本状态：线性增长状态对应着霜冰形态；减速增长状态对应着角冰形态。在大水滴粒径和低温条件下下则会出现略微的加速增长。因此,试飞时为了在最短时间内获得足够的冰高度,需要尽量选择水滴直径较大而温度较低的环境,而这是航线飞行需要避免的情况。

Investigation of growth law of ice shape on aircraft for the evaluation of icing flight test

The natural icing flight test is the key step of civil aircraft icing certification. Due to the high cost and risk of the flight test, the growth of ice shape is important to the planning of flight test and flight safety researches. In this paper, the ice-shaped growth process of two-dimensional airfoil under different environmental conditions is studied by numerical simulation. The influence of water droplet diameter and temperature on the ice growth law are focused on. The mechanism of ice growth speed change is analysed based on the change trend of water droplet collection rate with ice growth. The results show that the growth of the two-dimensional ice height of the aircraft has two basic states: linear and decelerating, the linear growth state corresponds to the frost ice shape; the decelerating growth state corresponds to the angular ice shape. There is a slight acceleration in growth under large water droplet diameter and low temperature conditions. Therefore, in order to obtain a sufficient ice height in the shortest time during the flight test, it is necessary to select an environment with a large water diameter and a low temperature, which is a situation that the route flight needs to avoid.