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Numerical Simulation of Mixing by Interaction of a Vortex Ring with a Density Interface

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Journal of Energy and Power Engineering 2018年第12期12卷 565-577页

作者： tomohiro degawa Tomomi Uchiyama Institute of Materials and Systems for Sustainability Nagoya UniversityFuro-choChikusa-kuNagoya 464-8603Japan

This study numerically explores the mixing caused by a vortex ring launched upward into a two-layer density-stratified fluid in a rectangular tank so as to search for a highly efficient mixing method.The upper and lower fluid layers are an aqueous glycerol solution and an aqueous solution of potassium dihydrogen phosphate(KH2PO4),respectively.The phenomena of vortex rings with Reynolds numbers of 4000,6000,and 8000 were simulated.The vortex-in-cell method is used to calculate the dynamics of the upper and lower fluids,and the CIP method is used to trace the concentration of the lower fluid.The simulations reproduce the mixing process successfully and elucidate the relationship between mixing efficiency and the Reynolds number of the vortex ring.

关键词： Density-stratified fluid mixing vortex ring numerical simulation vortex method

Mixing of Density-Stratified Fluid in a Cylindrical Tank by a Diagonal Jet

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Journal of Energy and Power Engineering 2018年第9期12卷 436-443页

作者： tomohiro degawa Kota Uno Tomomi Uchiyama Institute of Materials and Systems for Sustainability Nagoya UniversityNagoya 464-8603Japan Nippon Steel&Sumitomo Metal Corporation Tokyo 100-8071Japan

This study experimentally investigates the mixing of two-layer density-stratified fluid in a cylindrical tank by a diagonal jet.The upper and lower fluids are water and an aqueous solution of sodium chloride(NaCl),respectively,and the lower fluid issues from a nozzle on the tank bottom.The angle between the jet centerline and the tank bottom is 60°,and the mass concentration of the NaCl solution is 0.02.The mixing in cases that the Reynolds numbers of the jets are 713,2319,and 3565 is investigated.The velocity fields in the central vertical cross-section are measured with a PIV(particle imaging velocimetry)system by tracing nylon particles with the diameter of 80μm.The concentration fields in the section are visualized using Rhodamine B as the fluorescent dye.They are also measured using PLIF(planer laser induced fluorescence)from visualized images and the progresses of the mixing are evaluated quantitatively.The investigation clarifies the relationship between the mixing phenomena and the Reynolds number of the jet.

关键词： Jet density-stratified fluid mixing PLIF PIV

Numerical Simulation of Jet Issuing Diagonally Upward into Density-Stratified Fluid in Cylindrical Tank

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Journal of Power and Energy Engineering 2018年第3期6卷 38-52页

作者： tomohiro degawa Tomomi Uchiyama Isao Aozasa Akira Ishikawa Koji Motoyama Institute of Materials and Systems for Sustainability Nagoya University Nagoya Japan Mitsubishi Electric Co. Tokyo Japan Chubu Electric Power Co. Inc. Nagoya Japan

This study simulates the behavior of a jet issuing into a two-layer density-stratified fluid in a cylindrical tank and the resulting mixing phenomena. The upper and lower fluids are water and an aqueous solution of sodium chloride (NaCl), respectively, with the lower fluid issuing diagonally upward from a nozzle on the bottom of the tank. The angle between the centerline of the jet and the tank bottom is 60°. The phenomena when the Reynolds number Re of the jet is 475, 1426, and 2614 are simulated. The mass concentration of the aqueous solution of NaCl is 0.02. The simulation successfully grasps the jet behavior and the resulting mixing, which agree with the authors’ experimental results at the corresponding Re value. The secondary flows that appear in the horizontal cross-sections consist of a pair of vortices and flows along the tank wall. The secondary flow at the density interface represents the intrusion of an internal density current, which gives rise to mixing along the interface.

关键词： Jet Density-Stratified Fluid Mixing Secondary Flow Density Current

Behavior of a Jet Issuing Diagonally Upward into Two-Layer Density-Stratified Fluid in a Cylindrical Tank

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Journal of Flow Control, Measurement & Visualization 2017年第3期5卷 51-64页

作者： tomohiro degawa Shota Fukue Tomomi Uchiyama Akira Ishikawa Koji Motoyama Institute of Materials and Systems for Sustainability Nagoya University Nagoya Japan Mitsubishi Electric Co. Tokyo Japan Chubu Electric Power Co. Inc. Nagoya Japan

This study is concerned with the experimental investigation of a jet issuing diagonally upward into a two-layer density-stratified fluid in a cylindrical tank and the resulting mixing phenomena. The upper and lower fluids are water and an aqueous solution of sodium chloride (NaCl), respectively, and the lower fluid issues from a nozzle on the bottom of the tank. The angle between the centerline of the jet and the bottom of the tank is 60o, and the mass concentration of the NaCl solution is 0.02. The investigation reveals that secondary flow is caused by the jet in the horizontal cross-sections of the tank and that it is composed of a pair of vortices. It confirms that the secondary flow at the density interface corresponds to an internal density current. The investigation also clarifies the effect of the Reynolds number of the jet on mixing between the lower and upper fluids.

关键词： Jet Density-Stratified Fluid Mixing Secondary Flow Density Current