- 著者
- Hikaru AONO Satoshi SEKIMOTO Makoto SATO Aiko YAKENO Taku NONOMURA Kozo FUJII
- 出版者
- The Japan Society of Mechanical Engineers
- 雑誌
- Mechanical Engineering Journal (ISSN:21879745)
- 巻号頁・発行日
- vol.2, no.4, pp.15-00233, 2015 (Released:2015-08-15)
- 参考文献数
- 42
- 被引用文献数
- 23 32
Characteristics of flow fields produced by a dielectric barrier discharge plasma actuator in quiescent air are numerically investigated. A time-dependent localized body-force distribution is utilized to mimic the effect of the plasma actuator with modulated bursts. The computed time-averaged and instantaneous flow fields are compared with the experimental results by using high-speed schlieren photography and particle image velocimetry. The computed flow fields are in good agreement with the experimental results when the nondimensional parameter (Dc) is within the appropriate range. With an appropriate choice of Dc, the location and size of the induced flow structures, computed with respect to the maximum flow velocity parallel to the wall, are quantitatively in agreement with the experimental results. Also considered are the effects of the burst frequency (non-dimensionalized by the chord length and the free-stream velocity of assumed separated flow control experiment) on the induced flow. The results show that changes in the burst frequency cause insignificant changes in the magnitude of the time-averaged flow parallel to the wall, but they cause significant fluctuations in the amplitude and power spectral densities of that flow.
- 著者
- Hikaru AONO Katsutoshi KONDO Taku NONOMURA Masayuki ANYOJI Akira OYAMA Kozo FUJII Makoto YAMAMOTO
- 出版者
- THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES
- 雑誌
- TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES (ISSN:05493811)
- 巻号頁・発行日
- vol.63, no.1, pp.8-17, 2020 (Released:2020-01-04)
- 参考文献数
- 63
- 被引用文献数
- 7
Aerodynamics of an owl-like wing model at low Reynolds numbers (Re = O(104–5)) are investigated using large-eddy 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 × 104 to 5.0 × 104 and the angle of attack (α) varies from 0 to 14 deg. The time-averaged lift (Cl) and drag coefficients computed are in reasonable agreement with the results of force measurement. The results computed clarify a nonlinear change in the Cl 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 × 104 and 4.6 × 104 are seen, while reattachments are observed only on the pressure side at the Re of 1.0 × 104 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 α even though the LSB is generated and fluctuation in lift history is induced at low α.
- 著者
- Seiichiro MORIZAWA Taku NONOMURA Akira OYAMA Kozo FUJII Shigeru OBAYASHI
- 出版者
- THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES
- 雑誌
- TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES (ISSN:05493811)
- 巻号頁・発行日
- vol.61, no.6, pp.258-267, 2018 (Released:2018-11-04)
- 参考文献数
- 27
- 被引用文献数
- 8
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 Cl than symmetric airfoils. As for thin airfoils, Cl at higher α 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 Cl disappear as M∞ increases because the flow reattachment does not occurs. As for cambered airfoils, the decrease in Cl becomes larger than that on the symmetric airfoils when M∞ is higher. This is because Cp 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 Mcr at Re = 3,000 tends to be larger than that predicted by linear theory.