All issues
Volume 30 (2010)
- Issue 119 Pages 03-
- Issue 118 Pages 01-
- Issue 117 Pages 1-
- Issue 116 Pages 2-
Volume 30, Issue 119
Displaying 1-6 of 6 articles from this issue
- |<
- <
- 1
- >
- >|
-
Masaki Fuchiwaki2010 Volume 30 Issue 119 Pages 03
Published: 2010
Released on J-STAGE: April 14, 2012
JOURNAL FREE ACCESSDownload PDF (151K) -
Shigeru Sunada2010 Volume 30 Issue 119 Pages 4
Published: 2010
Released on J-STAGE: April 14, 2012
JOURNAL FREE ACCESSA lot of studies were made to make clear the mechanism of high lift generation by an insect during a hovering flight. It was found that the high lift is caused by a separated vortex. The present subject in a study of insect flight is to estimate the aerodynamic force generated by an insect precisely. In an analysis, effects of wings' deformation and body's motion on an aerodynamic force are estimated. An insect can fly with high stability and agility. To make clear a reason for stability and agility of an insect will be a new subject from now on. Recently, micro aerial vehicles are developed. Comparing their flights with insects' flights, we will find superiority of insects to them.View full abstractDownload PDF (2251K) -
Hiroto Nagai, Koji Isogai, Tatsumi Fujimoto2010 Volume 30 Issue 119 Pages 10
Published: 2010
Released on J-STAGE: April 14, 2012
JOURNAL FREE ACCESSWe experimentally investigate unsteady aerodynamic mechanisms of insect flapping wings. Measurements of unsteady aerodynamic forces and flow visualization around the flapping wing using PIV are conducted with dynamically scaled mechanical models in a water tunnel, which simulates hovering and forward flapping flights. We experimentally clarify the effects of three unsteady aerodynamics on the aerodynamic characteristics of a flapping wing: delayed stall, rotational circulation, and wake capture. The contribution of delayed stall to the total lift accounts for about 90%. The feathering rotation during the flapping translation contributes to an increase of power rather than lift. The wake capture is dependent on the reduced frequency and the timing of feathering rotation. In addition, we investigate the flow interaction between fore- and hindwings like a dragonfly. The phase difference between the fore- and hindwings are effective on the aerodynamic characteristics of the tandem wings.View full abstractDownload PDF (4232K) -
Koju Hiraki, Kazuki Fujii, Naoki Ogata2010 Volume 30 Issue 119 Pages 16
Published: 2010
Released on J-STAGE: April 14, 2012
JOURNAL FREE ACCESSInspired by a dragonfly, which sometimes appears to quit wing-beating, a possibility of a flight with either fore-wing or hind-wing beating of our four-winged flapping vehicle in order to achieve the more efficient flight. The wind-tunnel tests were carried out to determine which wing was appropriate to quit, by measuring the lift force on the fixed wing, which was placed in front of or behind the flapping wing. It revealed that the generated lift on the fixed fore-wing showed the dependency inversely to the flapping of the hind-wing. The visualized flow indicated that the flow separation over the upper surface of the fore-wing was suppressed by the flapping of the hind-wing. The prototype of the hind-wing flapping vehicle with the fore-wing fixed, successfully exhibited the steady flight, as well as saving 70 percents of the required energy for a flight of the four-winged flapping one.View full abstractDownload PDF (2653K) -
Itsuro Honda, Osamu Kawanami, Yosuke Kawashima2010 Volume 30 Issue 119 Pages 22
Published: 2010
Released on J-STAGE: April 14, 2012
JOURNAL FREE ACCESSThe hydrodynamics and undulating propulsion of were studied using a newly developed two-dimensional finite difference method. The mechanism of thrust generation associated with the oscillating caudal fin is discussed. In this paper, the equations of motion are solved together with the incompressible flow to simulate the flow field induced by the undulate motions. In order to investigate flow/structure interaction varies with time, the analysis is performed on the moving meshes. The arbitrary Lagrangian–Eulerian (ALE) method is applied to the Navier-Stokes equations. Grid points are generated along with the fish camber line by using algebraic method at each time step. The results of these computation shows that the kinematics of oscillating caudal fin produces a jet-stream propulsion between inverse Karman vortex with high propulsive efficiency. Investigation of the effect of Reynolds number indicates that the turning radius increases with increasing Reynolds number with no ceiling in generating the jet-stream propulsion.View full abstractDownload PDF (1166K) -
Osamu Mochizuki, Kenji Kikuchi2010 Volume 30 Issue 119 Pages 028
Published: 2010
Released on J-STAGE: April 14, 2012
JOURNAL FREE ACCESSWe explained the reason why a water strider can be on a water surface according to experimental results. We analyzed force balance of a floating circular cylinder as a leg of a water strider. To check the analysis we investigated experimentally the floating state of the circular cylinder with various diameters and the legs of a water strider. We showed that the surface property of a thin circular cylinder must be hydrophobic to take advantage of surface tension as a lifting force. Function of hydrophobic setae of the leg seems to be for retaining the air layer around the leg for increasing contact angle rather than an increment of length of contact line with water surface.View full abstractDownload PDF (4060K)
- |<
- <
- 1
- >
- >|