1998 Fiscal Year Final Research Report Summary
Investigation of fully dispersed shock wave in droplets-gas mixture
| Project/Area Number |
09450073
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Fluid engineering
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| Research Institution | Saitama University |
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Principal Investigator |
HIRAHARA Hiroyuki Saitama University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (20201733)
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| Co-Investigator(Kenkyū-buntansha) |
KAWAHASHI Masaaki Saitama University, Faculty of Engineering, Professor, 工学部, 教授 (70008853)
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| Project Period (FY) |
1997 – 1998
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| Keywords | Dispersed Shock Wave / Droplets / Shock Tube / Relaxation / Momentum relaxation / Mie Scattering / TVD Scheme / Image Processing |
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| Research Abstract |
An experimental and numerical investigation was carried out for the dispersion of shock waves in droplet-gas mixture flows. The droplet size and number density were measured by means of Mie scattering technique behind the shock wave. Two-dimensional image of test field was obtained in the experiment and the image was analyzed in digital by personal computer. Under the assumption that the droplet size should not be changed in the region not far from the shock front, the distribution of number density is proportional to the extinction rate of incident light beam intensity, Since the density ratio of droplet is proportional to the reciprocal of velocity ratio which is valid from the mass conservation, finally, we can obtain the velocty slip ratio between the droplet and gas flow from number density distribution of droplet. The momentum relaxation length is determined from these results. Experimental result show that the relaxation region increases as the relative velocity decreases. The v
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alue is much higher than theoretically predicted one. It is concluded that the model equation of drag coefficient should be modified for the crowd particles and unsteady motion. On the other hand, the pressure distribution behind the shock wave was measured in detail in order to investigate the dispersion of shock wave, When the incident shock Mach number is 1.4, the pressure profile shows a partly discontinuous distribution just behind the shock front. Viscous effect between the droplets and gas flow plays a significant dissipation function in this region. The typical length of this region is about 15 mm for Ms=1.4. The thermal relaxation length is much more long and 10 times of this length. This is attributed that the momentum relaxation and thermal relaxation is dispersed. The pressure profile of weak shock wave is close to that predicted by Young and Guha(1991). Otherwise, the numerical prediction did not show such dispersion on the pressure profile. It is concluded that the viscous effect should be accounted in the calculation with more valid physical model against the nonlinear wave steepenning. Less
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Research Products
(8 results)
