| Budget Amount *help |
¥3,050,000 (Direct Cost: ¥2,900,000、Indirect Cost: ¥150,000)
Fiscal Year 2007: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000)
Fiscal Year 2006: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2005: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Research Abstract |
Since aerodynamic drag reduction is closely related to energy saving, during the last few decades, modem vehicles are characterized by streamlined forms and there are few flow separations from the vehicle surfaces due to the effects of the vehicle manufacturers. However, various bluff shapes that are added to the vehicle body, such as door mirrors, roofracks and front pillar, exhibit aerodynamically generated drag, noise and vibration. Therefore, the extensive effective analysis and control of flow around these external bluff bodies has been becoming a greater concern and an important theme. The aim of this project is to develop the of drag reduction technique by imitating the shape of Mars' dune. The following three aspects were experimentally studied.
(1) PIV technique is used to measure the instantaneous and time-averaged velocity and vorticity fields over a dune model of Mars. Three-dimensional vortices and complex reverse flow structures behind a dune are visualized and extracted f
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rom the side and top views.
(2) The PIV and wavelet multi-resolution technique were applied to analyze the instantaneous multi-scale turbulent structures of the mirror wake. It is indicated that the vorticity strength of small-scale vortices originated from the end portion of the mirror are higher than that of large-scale vortices. The large-scale turbulent structure makes the largest contribution to the Reynolds stress in the range of separation shear layer behind the separation region. The small-scale structure, however, makes more contribution to the Reynolds stress in the separation shear layer near the mirror.
(3) In order to reduce power consumption, pipe wear and conveying velocity, a pneumatic conveying system that a dune model is installed in pipeline were proposed. An experimental study focused on the effect of installed dune model in the horizontal pneumatic conveying system in terms of the pressure drop and particle flow patterns. Results indicated that in the lower air velocity range, the pressure drop of the pneumatic conveying with an installed dune model is lower than that of the conventional pneumatic conveying system. The reduction rate of the lower pressure drop in the case of dune models is apparently large for high solids mass flow rate. The case fixing the dune model on the bottom of pipe at the inlet of particle feed is more effective for saving-energy conveying. The particle flow patterns also show that the dune model reduced the deposition of particles and result in the reduction of the pressure drop. Less
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