Mechanisms of surface pressure distribution within a laminar separation bubble at different Reynolds numbers

8th AIAA Flow Control Conference

et al. 2016

Self Cite

We have conducted large-eddy simulations of the airfoil flow at a cruise condition controlled by a DBD plasma actuator. The NACA0015 is used as the airfoil. The Reynolds number and angle of attack are set to be 63000 and 4 deg., respectively. In this condition, the flow is almost attached, except for the separation bubble region, over the airfoil. The lift-to-drag ratio is improved by the flow control with the burst mode actuation. The most effective burst frequency becomes F + ≃ 6 and the normal mode actuation is not effective. The delay of the turbulent transition is one of the key mechanism for the effective flow control at the cruise condition, differently from the separation control case. The flow feature and aerodynamic performance are compared between the controlled flow and "Ishii airfoil" flow, which is developed as a low-Reynolds-number airfoil. The lift-to-drag ratio attained by the flow control is comparable to that of the Ishii airfoil. Moreover, it can be said that the flow control by the plasma actuator on the simple shape airfoil has the capability to emulate the flow feature of the sophisticated airfoil.

Section: Ivb Comparison With Sophisticated Low-reynolds-number Airfoilmentioning

confidence: 90%

“…These pressure distributions in the burst mode cases are observed in the very low-Reynolds number flow. 34 In the research, the pressure recovery without separation bubble occurs at Reynolds number range of Re = 10 3 . Next, we focus on the pressure distributions with respect to z/c.…”

Section: Iva1 Aerodynamic Performancementioning

confidence: 99%

Control of Airfoil Flow at Cruise Condition by DBD Plasma Actuator - Sophisticated Airfoil vs. Simple Airfoil with Flow Control -

Asano

Sato

8th AIAA Flow Control Conference

et al. 2016

Self Cite

“…Those points should be addressed in the near future. It is noted that the fluid dynamic solver used in this study has been validated for flows around several wings 8,54,55) and the flat plate 56) in similar Re ranges. Figure 3 shows temporal and span-averaged C l and C d as a function of ¡.…”

Section: Verification and Validation Analysismentioning

confidence: 99%

Aerodynamics of Owl-like Wing Model at Low Reynolds Numbers

Aono

Kondo

Trans. Japan Soc. Aero. S Sci.

et al. 2020

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Aerodynamics of an owl-like wing model at low Reynolds numbers (Re = O(10 4-5)) are investigated using largeeddy simulations with high-resolution computational schemes. The airfoil shape of the owl-like wing model is constructed based on a cross-sectional geometry of the owl wing at 40% wingspan from the root. The chord-based Re ranges from 1.0 © 10 4 to 5.0 © 10 4 and the angle of attack (¡) varies from 0 to 14 deg. The time-averaged lift (C l) and drag coefficients computed are in reasonable agreement with the results of force measurement. The results computed clarify a nonlinear change in the C l curve slope, which is due to an increase in the suction peaks in conjunction with the change in type of separation, the formation of a laminar separation bubble (LSB), and pressure recovery on the pressure side. The generation of the LSB on the suction and/or pressure sides at the Re of 2.3 © 10 4 and 4.6 © 10 4 are seen, while reattachments are observed only on the pressure side at the Re of 1.0 © 10 4 due to the camber of the wing. Furthermore, the owl-like wing model demonstrates favorable aerodynamic performance in terms of a maximum lift-to-drag ratio in comparison with several airfoils at the Re range considered. This is due to the strong suction peaks and distribution of surface pressure on the pressure side. It is emphasized that the concave lower surface enhances the time-averaged aerodynamic performance at all of the ¡ even though the LSB is generated and fluctuation in lift history is induced at low ¡.

“…Japanese researchers have studied the feasibility of a Mars exploration mission using a propeller-driven Mars airplane. 6) Kojima et al, 7) Anyoji et al, 8) and Lee et al 9) studied the aerodynamics of the main wing of this Mars airplane under the flight conditions it would likely encounter (Re ranging from 10,000 to 100,000). The remaining issue is the aerodynamics of the propeller blade for the propulsion system.…”

Section: Introductionmentioning

confidence: 99%

Effect of Mach Number on Airfoil Characteristics at Reynolds Number of 3,000

Morizawa

Trans. Japan Soc. Aero. S Sci.

Oyama

et al. 2018

Self Cite

The effects of Mach number at Re = 3,000 for different airfoils (NACA0012, NACA0002, NACA4412, NACA4402) with thickness and camber geometries are investigated for the propeller blade design of a Mars airplane. The present study shows that thin and cambered airfoils have larger variations in C l than symmetric airfoils. As for thin airfoils, C l at higher ¡ has rapid increases when the M¨is low. This is because the flow separation occurs at the leading edge, and the flow is reattached on the airfoil surface. However, the rapid increase in C l disappear as M¨increases because the flow reattachment does not occurs. As for cambered airfoils, the decrease in C l becomes larger than that on the symmetric airfoils when M¨is higher. This is because C p near the leading edge on the lower surface is smaller than that on the upper surface and the high-speed region on the lower side of the leading edge is enlarged as M¨increases. Then, the M cr at Re = 3,000 tends to be larger than that predicted by linear theory.