高レイノルズ数領域における水-微細固体粒子懸濁液中の球の抗力 (<小特集>混相流の数値シミュレーションと新技術)

抄録

We have measured the velocity of an accelerating sphere as it falls in water/fine-solid-particle suspensions by means of four ultrasonic transducers. The fluids tested were silicon dioxide suspensions and carbon black suspensions. The concentrations of silicon dioxide suspensions were 0.3, 0.5 and 1.0wt% and those of carbon black suspensions were 0.3 and 0.5wt%. Four spheres between 57.1 and 152.4mm in diameter were tested. From the experimental results, it was shown that although the fall velocity of a sphere in suspensions is higher than that in tap water within a certain range of Reynolds numbers, drag reduction does not occur above the critical Reynolds number.