ACTA AERONAUTICAET ASTRONAUTICA SINICA >
Aerodynamic characteristics and flow control on a rectangular wing at low Reynolds number
Received date: 2015-05-18
Revised date: 2015-07-18
Online published: 2015-07-30
Supported by
A Project Funded by the Priority Academic Progran Development of Jiangsu Higher Education Institutions
It is found that the flight environment in thin atmosphere and at low Reynolds number leads to the drop of high-altitude long-endurance unmanned aerial vehicles (HALE UAV) aerodynamic performance, and as a result, how to improve it with flow control has drawn greater attention of researchers. An experimental investigation on the aerodynamic characteristics and flow control of a NACA 633-421 rectangular wing at low Reynolds number is conducted in a low-speed wind tunnel with force measurement,pressure measurement and boundary layer test. It is shown from force measurement result that a sharp deterioration of aerodynamic characteristics of NACA 633-421 wing occurs with the Reynolds number decreasing(Re<1.4×105), which includes severe losses of the maximum lift coefficient with respect to higher Reynolds numbers and the sharp decrease of stall angle. Pressure distribution on upper surface reveals that the emergence and development process of a laminar separation bubble (LSB), which moves forward to the wing leading edge, becomes shorter in length with increasing angles of attack and bursts at the stall angle, finally cause the sharp deterioration of aerodynamic characteristics. The micro synthetic jet (Micro-SJ) is used to control the flow structure of laminar separation bubbles, as a result of which the maximum lift coefficient increases from 0.59 to 1.10, the stall is delayed by 11° and the maximum lift-drag ratio is improved by 13.6% meanwhile. The active flow control of Micro-SJ possesses frequency selectivity, in which case the Micro-SJ at the frequencies between 200 Hz to 400 Hz have the best flow control effects to promote the transition of the separated shear layer and to shorten the length of laminar separation bubbles.
ZUO Wei , GU Yunsong , WANG Qite , ZHENG Yueyang , LIU Yuan . Aerodynamic characteristics and flow control on a rectangular wing at low Reynolds number[J]. ACTA AERONAUTICAET ASTRONAUTICA SINICA, 2016 , 37(4) : 1139 -1147 . DOI: 10.7527/S1000-6893.2015.0208
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