A New Impinging Jet Device for Corrosion Studies

• Published in: Corrosion (Houston, Tex.) Vol. 60; no. 5; pp. 455 - 464
• Main Authors: Demoz, A., Dabros, T., Michaelian, K., Papavinasam, S., Revie, W.
• Format: Journal Article
• Language: English
• Published: Houston, TX NACE International 01.05.2004; NACE
• Subjects: Applied sciences; Chemical reduction; Corrosion; Corrosion environments; Corrosion inhibitors; Corrosion mechanisms; Cylinders; Diameters; Electrochemistry; Exact sciences and technology; Flow characteristics; Fluid dynamics; Fluid flow; High temperature; Jet nozzles; Laminar flow; Metals. Metallurgy; Microelectrodes; Polytetrafluoroethylene; Potassium; Potassium ferricyanide; Reynolds number; Rotating cylinders; Shear stress; Stagnation point; Steady flow; Tubes; Turbulent flow; Wall jets; Wall shear stresses; Turbulent flow; Corrosion; turbulent flow. wall shear stress; stagnation region; Shear stress; Sherwood number; limiting current; impinging jet; Mass transfer
• DOI: 10.5006/1.3299241
• ISSN: 0010-9312

ABSTRACTA new high-pressure, high-temperature submerged impinging jet device is described. The experimental results of its flow characteristics are summarized. The device generates welldeveloped steady flow in the jet tubes with laminar flow up to Reynolds numbers (Re) of 1,980 and turbulent flow above Re = 2,800. Local mass transfers were measured on a polytetrafluoroethylene (PTFE) disc normal to the jet using eight 1-mm-diameter microelectrodes located at 0 < x/r < 3.8, where x is the distance from the stagnation point on the disc and r is the jet nozzle radius. Measurements were made using the limiting current of potassium ferricyanide (K3Fe[CN]6) solution electrochemical reduction for 50 Re 4,500 at H/r = 10, where H is the height of the jet nozzle exit above the PTFE disc. Flow transition from laminar to turbulent flow at the flat disc occurred at Re 800. The dependence of the local Sherwood number (Sh) on x/r gave three flow regions: x/r < 1; 1 x/r 2; and x/r > 2. This correlation further indicated that the flow from x/r = 2 and beyond was in the wall jet region. The empirical relation between Sh and Re in the stagnation region and developing wall jet region gave two segmented linear correlations. The device is scalable and can generate a wide range of Re. The empirical wall shear stress of the impinging jet was found to be more than 90 times that calculated for the rotating cylinder electrode (RCE) at comparable size and Re. This new device, therefore, is well suited for inhibitor and corrosion studies at high wall shear stress.