High efficiency integrated propeller-coflow jet airfoil in cruise

This paper presents the study of propeller-CoFlow Jet (CFJ) active flow control airfoil in cruise flight. The propeller-CFJ system is an integrated system with propellers mounted above the CFJ wing suction surface. Differing from the conventional configurations that separate the propeller and the airfoil, the propeller-CFJ system is designed together to enhance cruise efficiency via interaction between the CFJ and the propeller. The propeller pulls more flow toward the airfoil suction surface and the CFJ take advantage of the flow to achieve better aerodynamic performance. The simulations employ 3D RANS solver with Spalart-Allmaras (S-A) turbulence model, 3rd order WENO scheme for the inviscid fluxes, and 2nd order central differencing for the viscous terms. The aerodynamic performance, energy expenditure, and flow field are compared between airfoils with and without CFJ/propeller, including different propeller strength. The 2D simulation results show that the cruise efficiency is increased by 46.86% for case with CFJ only, and by 20.62% for case with propeller only compare to the baseline airfoil with no flow control. However, for the cases with both the CFJ and the actuator, the cruise efficiency improvement can be even larger due to the interaction of the CFJ and the actuator. The parametric study on the actuator strength shows that the cruise efficiency gains are around 80% for all cases and have a tenancy of increase with the increase of the propeller strength. The 3D full aircraft simulations show that the aerodynamic efficiency increases 7.11% and the productivity efficiency increases 11.17% with the help of the propeller actuator.