From the passage geometry, noncircular channel can be divided into two categories-a single channel and a multiple channel consisting of subchannels. This exposition covers some of the principal properties of both single-phase and two-phase flows in these channels. Frictional pressure drop, bubble rising velocity, void fraction and flow distributions to each subchannel are considered.

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The premises of the two-phase theory of fluidization were examined with a combined probe of the light transmission and the differential pressure methods developed by the authors.
The light transmission method composed of Ift, light emitting diode and phototransistor linked up with a bubble elimination circuit can extract the bubble free signal of emulsion phase e_eml, from which its solid concentration and thus its local porosity ε_eml was determined from the intensity of e_eml by assuming Lambert-Beer law.
The differential pressure method is a pair of pressure taps connected to a pressure transducer which gives the local pressure drop Δp. When those two probes are combined together, the interstitial gas velocity u_e in fluidized beds can be estimated by Kozeny-Carman equation since both ε_eml and Δp are given simultaneously.
The premises chosen are as follows:
i) ε_eml should be uniform and be ε_mf', the porosity at minimum fluidization velocity u_mf.
ii) u_e should be uniform and be u_mf/ε_mf (or u_z should be uniform and be u_mf, in superficial form since u_z=u_eε_eml).
The combined probe method revealed that both ε_eml and u_z were not so uniform as might be expected but distributed axially as well as radially in the bed of solids of two kinds. As a whole, the average ε_eml at the lower part was larger than ε_mf and the average u_z there was also larger than that at the upper part of the bed.
In the bed of cracking catalyst, the decreasing trends of the average ε_eml, and average u_z against the bed height were slightly more obvious than those in the bed of silica sand.

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The previous works on high-velocity circulating fluidized beds have been reviewed focusing our attention on how the essential categories and concepts relevant to the flow regime mapping have been molded and how the unsolved problems should be organized.
Based on the laboratory scale experiments the detection methodology for phase transitions has been discussed. It has been shown that the characteristic values of bubbling-to-turbulent transition can be clearly determined by using the power spectrum of pressure fluctuation. In regard to the turbulent-to-fast transition the probability density distribution of light reflection from the bed has been found to be a powerful tool of quantitative detection method for turbulent-to-fast and fast-to-dilute phase transitions.
After the evaluation of the pattern necessary for a global flow regime map the Ar-Re_p diagram has been derived based on the data from previous inverstigations.

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This paper presents the characteristics of the pressure fluctuation in the entrance region in solid-liquid flow. To investigate an axial developing process of the pressure fluctuation, six pressure transducers were set at intervals of 2m in the test pipe.
It was found from the experiment that in the range of higher velocities, the maximum pressure fluctuation decreased as the distance from the feeder increased. That is, the maximum pressure fluctuation decreased as the flow developed. On the other hand, in the range of lower velocities, little effect of distance from the feeder on the maximum pressure fluctuation was obtained.
Furthermore, it was confirmed that the periodicity in the auto-correlation function was not obtained in the entrance region, but as the flow developed, the obvious periodicity in the auto-correlation function was obtained in the range of lower velocities and higher solid concentration at the measuring point far from the feeder. This periodicity results in the movement of dune formed in the pipe.
And it was found that in the entrance region, the maximum pressure fluctuation increased as the particle diameter increased, but the rate of increase of the maximum pressure fluctuation decreased as the distance from the feeder increased. When the flow developed fully, the maximum pressure fluctuation was not effected by the particle diameter.

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