Performance testing and detailed flow measurements were made in an axial compressor rotor with various tip clearances. The experiments were conducted on the condition of the same incidence angle at midspan. Thus, the effect of tip clearance distinguished from that of incidence angle was investigated on the overall performance, work-done factor, blockage factor, and increases in displacement, momentum, and blade-force-deficit thicknesses of the casing wall boundary layer, The phase-locked flow patterns obtained by the multisampling technique show clear evidence of a leakage vortex core behind the rotor. Behavior of the leakage vortex was clarified for various tip clearances by examining loci of the vortex center, decay characteristics of the vorticity at the center, and the total amount of vorticity shed from the blade tip. These results were compared with the leakage vortex model presented by Lakshminarayana.

No abstract

calcium silicates such as C3S, βT‐C2S, and γgM‐C2S† were carbonated under saturated humidity at room temperature. Carbonation products were examined by DT‐TGA, gasphase mass spectroscopy, and XRD. Two types of carbonate were produced: one type, which was rather poorly crystallized, was decarbonated at a very low temperature, below 600°C; the other type was a crystalline phase such as calcite, aragonite, and/or vaterite which was decarbonated above 600°C. The data were compared to existing data for calcium carbonates and basic calcium carbonates. The results suggest that an amorphous calcium silicate hydrocarbonate was one of the carbonation products which formed during the hydration/carbonation reaction.

In the course of our study on a Japanese traditional stoneware called “Bizen”, we have found that ϵ-Fe2O3, which has been classically known but recently limelighted for its magnetic potentiality, crystallizes epitaxially on needlelike crystals of mullite, 3(Al,Fe)2O3·2SiO2. This interesting reaction occurred when a pellet of Bizen clay powder was covered with rice straw and then heated to 1250 °C in a stream of nitrogen containing 1−2 vol % of oxygen. It is known that mullite forms from the clay on heating and that the rice straw provides potassium to induce partial melting in the pellet surface to a depth of ∼50 µm. The ϵ-Fe2O3-on-mullite particles formed in this molten region, changing their morphology with the oxygen partial pressure. Square-columnar single-crystalline particles with prismatic ends grew to ∼0.1 × 0.1 × 0.5 µm3 at N2/O2 = 99/1, while dendritic finlike crystals of ∼0.3 × 0.1 × 0.8 µm3, which was then the biggest size ever reported, grew at N2/O2 = 98/2. The relative ϵ-Fe2O3-to-mullite orientation also changed with the oxygen partial pressure. This discovery suggests morphological controllability of this metastable but magnetically interesting iron oxide as a function of the oxygen partial pressure.