| Popis: |
Anovelsubsonicairfoilcirculationaugmenttechniqueusingco-∞owjet(CFJ)toachievesuperioraerodynamicperformanceforsubsonicaircraftisprovednumericallybyCFDsimulation. Theadvantagesofco-∞owjetairfoilincludehighliftathighangleofattack,ultrahigh Cl=Cdat cruise point, and low penalty to the overall cycle e‐ciency of the airframe-propulsion system. Unlike the conventional circulation control (CC) airfoil which is only suitable for landing and taking ofi, the CFJ airfoil can be used for the whole ∞ying mission. No blunt leading and trailing edge is required so that the pressure drag is small. No moving parts are needed and make it easy to be implemented and weight less. The jet to enhance the circulation will be recirculated. Compared with the CC airfoil, the recirculating CFJ airfoil will signiflcantly save fuel consumption because: 1) the power required to energize the jet is less; 2) no penalty to the jet engine thrust and e‐ciency due to the disposed jet mass ∞ow since the jet mass ∞ow is recirculated. For the NACA2415 airfoil studied, at low AOA with moderate momentum jet coe‐cient, the co∞ow jet airfoil will not only signiflcantly enhance the lift, but also dramatically reduce the drag, or even generate the negative drag (thrust). The mechanism is that the co∞ow jet can control the pressure drag by fllling the wake, and could generate negative pressure drag greaterthanthefrictiondrag. Thismayallowtheaircrafttocruisewithveryhighaerodynamic e‐ciency. AthighAOA,boththeliftandthedragaresigniflcantlyhigherthantheairfoilwith no ∞ow control, which may enhance the performance of taking ofi and landing within short distance. |
