Abstract: With the development of aircraft electrification, distributed electric propulsion technology has become an important aspect of future aviation power systems. However, the nacelle lips of distributed propulsion systems are highly susceptible to icing, which poses a potential threat to aircraft performance and flight safety. To investigate the icing of the nacelle square-shaped lip in distributed propulsion systems, a three-dimensional numerical method for ice simulation was developed based on a user-defined function of the commercial software FLUENT. A body force model was developed to simulate the forces exerted by fan blades on airflow. The effects of ducted fans, liquid water content, and droplet diameter on the characteristics of the ice shapes at the nacelle lip were analyzed. The fan suction effect significantly altered the collection of supercooled droplets by accelerating the airflow around the lip, thereby affecting the thickness distribution and outlines of the ice shape. When considering the suction effect of the distributed duct fans, the ice shape at the upper wall of the nacelle lip exhibited a wavy distribution with a distinct ice ridge at the leading edge, and the ice shape on the outer side wall of the nacelle was deflected toward the inner side. When the liquid water content increased from 0.5g/m3 to 1.5g/m3, the deflection angle of the ice shape on the outer side wall increased by approximately 11 times. In addition, the deflection angle increased by approximately two times when the droplet diameter increased from 10μm to 40μm. These findings can provide useful guidance for the design and optimization of anti-icing/de-icing systems for distributed propulsion nacelles.

Key words: distributed propulsion, ducted fan, square-shaped lip, ice shape characteristic, liquid water content, droplet diameter