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Volume 35 (2015)
- Issue 139 Pages 3-
- Issue 138 Pages 1-
- Issue 137 Pages 1-
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Volume 35, Issue 137
Displaying 1-6 of 6 articles from this issue
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Reviews
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Masaya MUTO, Ryoichi KUROSE2015 Volume 35 Issue 137 Pages 1
Published: 2015
Released on J-STAGE: April 01, 2016
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Fumiteru AKAMATSU2015 Volume 35 Issue 137 Pages 2-7
Published: 2015
Released on J-STAGE: April 01, 2016
JOURNAL FREE ACCESS
Supplementary materialTo elucidate detailed combustion mechanism of droplet clusters, that is, group combustion behavior, simultaneous time-series measurements of OH chemiluminescence, CH-band light emission, and Mie scattering from droplets illuminated by laser light detected by using a Cassegrain optics named MICRO (Multi-Color Integrated Cassegrain Optics), the droplet diameter and velocity measured by using PDA are applied to a premixed spray flame. In addition, time-series planar images of droplet clusters are obtained simultaneously with these 5 quantities mentioned above to observe the combustion process of droplet clusters. The high data rate and high validation rate of PDA measurement accomplished by the optimized design of optics enabled us to distinguish instantaneous characteristics of individual droplet clusters in the flame. Thus, we estimated the modified group combustion number GC for individual droplet clusters using the cross-section area, the measured mean separation distance between droplet centers, the total number of droplets for each droplet cluster.View full abstractDownload PDF (1588K) -
―For the elucidation of physics behind the beauty―Chihiro INOUE2015 Volume 35 Issue 137 Pages 8-13
Published: 2015
Released on J-STAGE: April 01, 2016
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Supplementary materialSparkling fireworks are composed of black powder containing no metal wrapped in a twisted paper. The fireworks have their unique beauty. However, physics behind the beauty of sparkling fireworks is a 400-year mystery. There are four seasons in a life of the fireworks, and the beautiful streaks of light scatter from the fireball with soothing sounds in the mid seasons. By the high-speed visualization, we have elucidated that the beautiful streaks of light, which result from a tiny droplet reacting with surrounding oxygen, are produced by bursting bubbles on the fireball. Unsteady temperature measurement are also carried out by two color temperature radiometry method. It is clarified that fireball temperature is decided by the melting points of K2S and K2CO3, and highest droplet temperature is determined by melting point of K2SO4. As the production mechanism of the light streaks as pine-like needles, the microexplosion due to gas generation inside the droplet can be an essential phenomenon.View full abstractDownload PDF (2009K) -
Yuichiro NAGATSU2015 Volume 35 Issue 137 Pages 14-19
Published: 2015
Released on J-STAGE: April 01, 2016
JOURNAL FREE ACCESS
Supplementary materialFlows with chemical reactions (chemically reacting fflows) are relatively complicated phenomena. This is because they are multicomponent system, in addition they include chemical reaction and physics (flow). It can considered that visualization is one of the powerful tools to elucidate complicated phenomena such as reaction flows. The author has studied reacting flows in liquid since 1998. In this article, the author introduces our findings of liquid reacting flows elucidated by visualization. These include (1) experimental study on reacting flows in which the product distribution significantly depends on initial reactant concentrations, (2) numerical simulation on a reacting flow involving changes in viscosity, and (3) experimental and numerical study on a reacting flow with precipitation.View full abstractDownload PDF (1694K) -
Takenobu MICHIOKA2015 Volume 35 Issue 137 Pages 20-25
Published: 2015
Released on J-STAGE: April 01, 2016
JOURNAL FREE ACCESS
Supplementary materialIn order to visualize a turbulent concentration field by numerical simulation or laboratory experiment, the spatial resolution smaller than the smallest length scales of concentration field (the Batchelor scale) is required. The Bathelor scale is much smaller in a liquid flow with a high Schmidt number than the smallest velocity scale (the Kolmogorov scale). It is, therefore, very difficult to visualize the concentration field in liquid flows by the conventional methods. In this manuscript, direct numerical simulation and planar laser-induced fluorescence measurement technique in a laboratory experiment in order to visualize the liquid turbulent flows is explained with examples based on my research.View full abstractDownload PDF (1173K) -
―Application to multi-scale combustion fields―Hiroaki WATANABE2015 Volume 35 Issue 137 Pages 26-31
Published: 2015
Released on J-STAGE: April 01, 2016
JOURNAL FREE ACCESS
Supplementary materialA large-eddy simulation (LES) is performed to predict characteristics of NOx formation in pulverized coal combustion field. A laboratory-scale open-type pulverized coal flame generated by a triple stream co-axial swirl burner and a large-scale combustion test furnace with practical complex burners are targeted to apply the LES to investigate the NOx formation. Results of the computation on the lab-scale burner show that NO is rapidly formed due to the oxidation reaction of nitrogen from volatile matter of coal and NO rapidly decreases just downstream of the region where the peak value appears due to the reduction reaction. The trend becomes marked with increasing O2 concentration. Results of the large-scale furnace show that the gas temperature, O2 and NO concentrations are precisely captured by the present LES. Present study shows the usefulness of the LES for predicting the characteristics of NOx formation in coal flames.View full abstractDownload PDF (1526K)
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