Study of super-lift coefficient of co-flow jet airfoil and its power consumption

Yang Wang, Yunchao Yang, Gecheng Zha

Research output: Chapter in Book/Report/Conference proceedingConference contribution

12 Scopus citations


This paper studies the super-lift coefficient of Co-Flow Jet (CFJ) airfoil and its power consumption. An optimized CFJ airfoil (CFJ6421-SST150-SUC247-INJ117) for cruise with enlarged injection slot size can achieve higher maximum lift coefficient than the baseline CFJ airfoil (CFJ6421-SST016-SUC053-INJ009), but at substantially lower power consumption. The reason is that the CFJ power consumption is determined linearly by the mass flow rate, but exponentially by the total pressure ratio. The larger injection slot size yields greater Cµ, higher mass flow rate, and lower injection jet velocity, which generate much smaller flow energy loss, lower total pressure ratio, and hence substantially reduces the CFJ power consumption. For example, at a CLmax of 9, the total pressure ratio is reduced from 4.2 to 1.3 while the injection slot size is increased from 0.09%C to 1.17%C. The power coefficient is reduced by 5 times. Such phenomenon applies to all active flow control using fluidic actuators. The flow vortex structures are studied by comparing the flow from AoA of 30 to 80 . The flows are all attached. At an AoA below 60, the vortex structures on the CFJ airfoil suction surface are primarily three layers, 1) a clockwise layer due to the wall boundary layer; 2) a counter-clockwise layer due to the high speed jet; and 3) the second clockwise vortex layer shed from the leading wall boundary layer, which is dissipated quickly downstream of the injection slot. However, when the flow reaches the stall AoA of 65 with the maximum lift coefficient and adverse pressure gradient, the second clockwise vortex layer is erupted with a substantially enlarged area, which contributes significantly to the ultra-high lift generation. The vortex structures become four counter-rotating vortex layers as previously observed by Yang and Zha. The overall conclusion is that a CFJ airfoil with a large injection slot size is preferred. It is as effective to enhance lift, generate thrust, and increase stall AoA, but at a substantially lower power consumption. It makes the same CFJ airfoil with fixed geometry applicable to the whole flight envelop from takeoff/landing to cruise.

Original languageEnglish (US)
Title of host publicationAIAA Aviation 2019 Forum
PublisherAmerican Institute of Aeronautics and Astronautics Inc, AIAA
Number of pages18
ISBN (Print)9781624105890
StatePublished - 2019
EventAIAA Aviation 2019 Forum - Dallas, United States
Duration: Jun 17 2019Jun 21 2019

Publication series

NameAIAA Aviation 2019 Forum


ConferenceAIAA Aviation 2019 Forum
Country/TerritoryUnited States

ASJC Scopus subject areas

  • Computer Science Applications
  • Electrical and Electronic Engineering
  • Aerospace Engineering


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