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Volume 24, Issue 270
Displaying 1-5 of 5 articles from this issue
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Akira AZUMA1976 Volume 24 Issue 270 Pages 309-323
Published: July 05, 1976
Released on J-STAGE: May 25, 2009
JOURNAL FREE ACCESSDownload PDF (1592K) -
Makoto NAGATOMO1976 Volume 24 Issue 270 Pages 323-332
Published: July 05, 1976
Released on J-STAGE: May 25, 2009
JOURNAL FREE ACCESSDownload PDF (2597K) -
Eiji KATO, Tsutomu ADACHI1976 Volume 24 Issue 270 Pages 333-341
Published: July 05, 1976
Released on J-STAGE: May 25, 2009
JOURNAL FREE ACCESSThe experiments described in this paper are intended to clarify the effect of velocity gradient on the wake of a circular cylinder in corss linear shear flow with four various velocity gradients at Reynolds numbers in the range of 2.67×103 to 1.07×104.
Wake and vortex street develop in the downstream unsymmetrically about the wake center line. The developments are greater in the lower velocity side than in the higher. With an increase of velocity gradient the position of vortex generation approaches to the cylinder. The vortex shedding frequency of both sides is equal. This is the same as that of uniform flow.
The spacing between the longitudinal vortex centers and the ratio of the spacing of the longitudinal to the lateral increase with increasing the velocity gradient.
The decay of the vortices and the instability of the vortex streets in shear flow are remarkably than in the uniform flow. These become greater as the velocity gradient is increasing. The following facts associated with these phenomena are observed.
i) The lateral spacing between the vortex centers in the higher velocity side is greater than in the lower.
ii) The strength of the vortices of both sides is not equal and reverses in the course of the downstream.
iii) Turbulence in main flow becomes progressively greater as the velocity gradient is raised.View full abstractDownload PDF (568K) -
Syuzo OKAZAKI, Masahito NISHIMURA, Hiroshi MAEDA1976 Volume 24 Issue 270 Pages 342-351
Published: July 05, 1976
Released on J-STAGE: May 25, 2009
JOURNAL FREE ACCESSStatic characteristics of an ACV (Air Cushion Vehicle) over irregular ground are investigated theoretically and experimentally. The exponential theory is developed for this purpose. Calculations are made for the case of two and three dimensional models, and the results are compared with experimental ones.
Theoretical results show good agreement with those of experiments except the particular cases such as the hover height is very low, or the higher portions of ground roughness is close to the peripheral nozzle.
The effects of the partition on lift and moment characteristics are also studied. Calculations show that partition equipped on the base affects the lift augmentation ratio especially at large d/D, but there exist little effects on experimental results. On the other hand, moment characteristics calculated agree with the measured values qualitatively.View full abstractDownload PDF (529K) -
Ryuhei KUMAZAWA, Itsuro KIMURA1976 Volume 24 Issue 270 Pages 351-358
Published: July 05, 1976
Released on J-STAGE: May 25, 2009
JOURNAL FREE ACCESSThis report is concerned with the developement of a simple low-thrust plasma thruster, composed of a Duoplasmatron-type plasma source and a magnetic nozzle. The results of the experiment with various kind of propellants showed moderate thrust efficiencies (up to 31%) in wide range of specific impulse (400-8, 000sec), and high ionization efficiency. Such experimental results demonstrate its capability as a low-thrust plasma thruster. On the present device, in which a diverging magnetic field (magnetic nozzle) is applied to the discharge and exhaust region, there are several possible plasma acceleration mechanisms. The results of diagnostics of plasma beams in this device suggested that the prevailing acceleration mechanisms are (1) acceleration by magnetic expansion process and (2) acceleration by converting rotational kinetic energy to directed kinetic energy.View full abstractDownload PDF (504K)
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