This paper proposes the strategy or methodology how to achieve a scaling of flames; that is, the law to attain the ratio of flame size to flame thickness remains as constant in variety size of flame (thus, a larger flame has thicker flame zone while a smaller flame has thinner flame zone, yet the overall geometric similarity is sustained). Considering simple analysis the possible strategy to fulfill this requirement is discussed. It turns out that the combination with low-gravity and dilution would be key factors to attain the geometric similarity of the flame including its structure. We will verify this issue in future by means of low-gravity test facility (experimental approach) and numerical simulation with multi-step kinetics model (numerical approach).

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   Smoldering is based on the slow, low-temperature, flameless combustion of a condensed fuel. The propagation velocity of downward smoldering is dominated by the rate of transfer of oxygen to the reaction zone. Regarding as this point, Kinbara et al. (1976) have revealed that the smoldering velocity of rod fuel; V_sml [mm/s], clearly increased as the diameter of the rod was reduced. The purpose of this study is to reveal the characteristics of smoldering in small-scale. We examined the smoldering characteristics of the rod-shaped solid combustibles whose width is d_s [mm] under various conditions (d_s=0.3~3.0 mm, porosity Φ=0.41~0.65). Based on the consideration that oxygen supply is dominated by diffusion, a theoretical smoldering velocity is found to be inversely correlated to the scale parameter ;d_s(1-Φ) [mm]. The theoretical smoldering velocity is in good agreement with available experimental data especially in small-scale, where the previous works has never been examined.

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   A micro laminar premixed flame formed on a burner with pilot flame is observed. The flame is stabilized even on the burner whose diameter is 0.4 mm. However, the shape of the flame formed on the burner whose diameter is less than 1mm and at around the lowermost flow rate is near spherical. It is similar to the appearance of micro diffusion flames. On the other hand, the flame formed on the burner whose diameter is less than 0.6 mm is not considered as propagating flame, because typical laminar propagating flame has a structure more than 0.6 mm thickness at this condition. We observed the flame structure variation and the uppermost and the lowermost flow rates which the flame could be formed stably. It is, consequently, supposed that the flame formed on the burner whose diameter is submillimeter is dominated by the diffusion mixing of oxygen and methane from the premixture and high temperature heat flux from the pilot gas flow. We, further, examined the flame structure and the extinction mechanism of the premixed microflame and tried to explain scale effects on the extinction limit and the flame structure variation.

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   A number of studies about flame spread over solid combustibles have been reported over the past few decades. However, there are only a few studies about flame spread in a cylindrical enclosure. Especially, the static characteristics, such as flame height and width, have never been clarified. To reveal a geometrical similarity condition of flame spread in tube, we performed experiments in various conditions. The flame height increased as inner diameter, ambient pressure and oxidizer velocity increased. The non-dimensional flame height, determined as the flame height divided by the inner diameter, was proportional to Reynolds number. The flame spreading in different directions were compared and the shapes were almost similar to each other. It suggested that gravity effect on the flame shape was small. Meanwhile, the flame width did not depend on the flow field, and thus a quenching distance between the flame and the fuel surface was constant. From these results, it was found that the geometrical similarity condition was given by Reynolds number. In addition, considering the heat transfer from the flame to unburned fuel surface, we showed the similarity condition of the dynamic characteristic, i.e., non-dimensional flame spread rate. Also, the condition which can simultaneously satisfy both the static and the dynamic similarity was discussed in this paper.

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   Diffusion microflames has potentials to be utilized as a point-symmetric one-dimensional flame to unveil detail structures of diffusion flame and as a heat source with high heat release density. The way to elevate those potentials is investigated in the present study. Thus, a microflame is established in the oxygen fraction controlled ambient coflow, where methane issues from the inner tube with 0.7 mm ID, whereas the coflow mixture of oxygen and nitrogen from the outer coaxial tube with 6.0 mm or 2.9 mm ID. The results show that increase of oxygen mole fraction in ambient flow makes a microflame close to the perfect point-symmetric one-dimensional flame. Specifically, increase of oxygen mole fraction from 0.21 to 0.49 reduces the difference from the perfect point-symmetric shape into half; this is considered because molecular diffusion becomes dominant owing to the decrease of Pe number resulting from the reduction of flame size. Increase of oxygen fraction is found to be quite effective to increase heat release density as it becomes 7 times larger by the increase of oxygen fraction from 0.21 to 0.49.

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   Primarily, Japan has very little sources of coal, oil, and natural gas. As a result these primary energy sources are imported from other countries. The development of Japan's domestic primary energy sources is necessary to reduce its dependency on foreign energy import. Above all, energy derived from biomass sources are sustainable energy resources. In this study, various sizes of high-density biomass briquette named ‘Bio-coke,' whose technology was based on our patent (PAT.-No.4088933), were produced from green tea grounds. The physical properties at high temperature of each size of Bio-coke were studied, and their maximum compressive strength and Young's modulus were estimated by a compression test at a temperature of 973K. From the results obtained, the relationship between the size of Bio-coke and the maximum compressive strength or Young's modulus could be approximated by a linear function or an exponential function.

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   In order to overcome the difficulties of conventional methods for measuring concentration of solid-phase in the solid-liquid two-phase flow in micro-devices, a unique measuring technique using electromagnetic induction with diluted magnetic fluid is applied to measure the solid-liquid two-phase flow in a micro-tube. In this method, 5 wt.% magnetic fluid diluted by distilled water was used. In order to verify the validity of the technique for measuring solid-liquid two-phase flow, experiments in actual solid-liquid two-phase flow with horizontal flow micro-channel were performed. The present method has demonstrated a promising capability of measuring concentration with good accuracy.

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   Study for accurate flowrate measurement for complicated flow like just after double bent is examined using Ultrasonic Velocity Profile (UVP) method. The characteristics of velocity profiles from the radial measurement lines to the center of pipe are investigated to form the three-dimensional sound field measurement system to obtain accurate flowrate. Multiple transducers and radial measurement lines are necessary to reproduce three-dimensional velocity profiles of complicated flow. In the case of measurements just after simple double bent, flowrate measurement about 3% error is realized using three transducers at the distance of as short as 3 D in the condition of Re~40,000. However, another analytical optimization study for number of transducers and distance from the bent is also executed adopting sampling theory and signal analytical method using FFT. 36 measured velocity profiles are accumulated to obtain velocity profiles along circumferential measuring circles, and Fourier amplitude of those velocity profiles along the measuring circles suggest the largest wave number for each distance. Analytical optimal number for transducer for each distance is given from the results. Both experimental optimizations are confirmed by numerical method using CFD code.

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