Numerical investigation of performance improvement of the co-flow jet electric airplane

The Co-Flow Jet (CFJ) flow control is a promising technology that can achieve high wing loading and aerodynamic efficiency at cruise and ultra-high lift coefficient at takeoff/landing. A conceptual electric airplane design utilizing CFJ flow control (CFJ-EA) was designed by Lefebvre and Zha [1]. Recently, the super lift coefficient (SLC) of CFJ airfoil that exceeds theoretical lift coefficient limit was achieved at ultra-high angle of attack (AoA) [2]. The purpose of this paper is to present an improved design of CFJ-EA (CFJ-EA2) with the performance improvement in takeoff/landing lift coefficient and cruise efficiency. The wings of CFJ-EA2 utilize a super-lifting CFJ airfoil and a modified high-efficiency CFJ cruise airfoil for takeoff/landing and cruise respectively. The CFJ-EA2 wings are designed to be pivotable to achieve ultra-high lift coefficient at high AoAs for takeoff/landing and high aerodynamic efficiency at lower AoAs for cruise. For the takeoff/landing condition, the 3D steady RANS simulations are performed at the AoAs of 30°, 40°, and 50°with the C_µvarying from 0.2 to 0.6. It indicates that using the super-lifting airfoil, the CFJ-EA2 can achieve a maximum lift coefficient of 6.9 at a high AoA of 50°. For the cruise condition, an improved CFJ cruise airfoil is utilized on the CFJ-EA2 to have a higher wing loading and better cruise efficiency. The lift coefficient of CFJ-EA2 wings is 1.59 and the wing loading is increased to 214 kg/m²The aerodynamic efficiency (L/D)_cis increased to 31 and the productivity efficiency (C_L ²/C_D)_cis 50, which is 51% higher than the previous design. The gross weight of CFJ-EA2 is 2289 kg because of its high wing loading; and the range is extended to 531 nm due to higher cruise efficiency and more batteries installed.