Binary Correlation Method for 2D・PTDand its Application to Two Cylinder Interaction Flow

This study deals with fluctuating interaction flows around two circular cylinders arrayed in tandem arrangement. After the flows are visualized by a hydrogen bubble tracer technique，the two-dimensional particle tracking velocimetry (2D-PTV) based on binary correlation method is applied to measure the flow velocities of the whole field. Using the results of instantaneous and time mean velocity vectors，vorticity contours, streamlines and root mean square values of the fluctuating velocities，the analysis and discussions on the flow fields are made

Instability Phenomena at Bath Surface Induced by Top Lance Gas Injection

Top lance gas injection processes are extensively used in metallurgical engineering. When the exit of the top lance is placed near the bath surface, a downward bubbling jet is generated in the bath. The flow patterns of the downward bubbling jet are classified into seven categories mainly with gas flow rate. Instability phenomena of the bubbling jet appear when the gas flow rate is higher than a certain critical value. The phenomena are strongly dependent on the penetration depth of the bubbling jet into the bath, and hence, an empirical relation is proposed for the penetration depth as a function of the gas flow rate, nozzle diameter and vessel diameter

Bonding Strengths of Interfaces between Cast Mg-Al Alloy and Cast-In Inserted Transition Metal Cores

The structures and strengths of the joining interfaces between Mg-10mass%Al alloy and cast-in inserted transition metal cores have been investigated. Three kinds of core materials were examined: S20C carbon steel, SUS304 stainless steel and titanium. The Mg-Al alloy specimen had higher shear strength than the pure Mg specimen for every core material. Molten Mg does not react with these core materials. On the other hand, molten Mg-Al alloy reacts with each core material and produces metallurgical joint with the core. The Ti core provided highest shear strength

Filtration of Ni-Al Alloy Containing By-Product Alumina in Centrifugal Combustion Synthesis

The centrifugal combustion synthesis (CCS) process with a thermite-type combustion synthesis reaction can produce a joint of a cast Ni3Al member and a dissimilar material. We verify effectiveness of filtration of the combustion-synthesized Ni-Al alloy on the distribution of by-product alumina inclusions in the cast member. In the specimen produced without filtration, coarse alumina inclusions were distributed. In contrast, no such a fatal defect was observed in the filtrated specimen

Formation Mechanism of Microchannels and Lining Layers in Sintered Iron Powder Compacts with Copper Sacrificial Cores

The formation mechanism of microchannels with Fe-Cu alloy lining layers in iron bodies produced by a powder-metallurgical microchanneling process has been investigated. Copper wire was used as a sacrificial core that gives the shape of the microchannel and supplies the alloying element for the lining layer. An iron powder compact containing the sacrificial core was heated and sintered at temperatures between the melting points of copper and iron. Quenching experiments showed that the microchannel was produced just after melting of copper. In a quenched specimen with a newly-formed microchannel, fine copper-rich regions were observed between the iron powder particles in the lining layer. These results established that infiltration of molten copper into the iron powder is the dominant mechanism for the Fe-Cu microchanneling process. It was also found that the liquid copper infiltrated via preferential flow pathways between the iron powder particles

Effects of Channel Gap and Channel Attitude on Flow Pattern of Air-water Two-phase Flow in Rectangular Millimeter-scale Channels

Effects of channel gap and channel attitude on the flow pattern of gas-liquid two-phase flow in rectangular millimeter-scale gap channels are investigated. The channel gap is varied from 0.5mm to 10.0mm. The observed flow patterns in horizontally placed channels are classified into three categories: bubbly flow, slug flow and annular flow. As the gap becomes small, the bubbly flow regime shifts to the slug flow regime. The boundary between the slug flow regime and the annular flow regime is hardly dependent on the gap. In the bubbly flow regime, the so-called channeling phenomenon of bubbles takes place. Concerning the effects of channel attitude on the flow pattern, a channel with a gap of 1.0mm is mainly used. The inclination angle of the channel is varied from 0° to 90° . The observed flow patterns for a vertically wide channel with an inclination angle of 0° are classified into three categories: bubbly flow, slug flow and stratified wavy flow. Those for an inclination angle of 90° are classified into bubbly flow, slug flow and annular flow. As the inclination angle increases form 0 to about 30°, the bubbly flow regime becomes wide. With a further increase in the inclination angle from about 30° to 90°, it becomes narrow. The slug flow regime changes with an increase in the inclination angle in a complicated manner