Experimental investigation of the effect of 90° standard elbow on horizontal gas–liquid stratified and annular flow characteristics using dual wire-mesh sensors

Data on pressure drop were obtained in stainless steel, sanitary fittings and valves during laminar and turbulent flow of aqueous solutions of sucrose and xanthan gum, which were selected as model fluids. The rheological properties of these solutions were determined and the power-law model provided the best fit for experimental data. Friction losses were measured in fully and partially open butterfly and plug valves, bends and unions. Values of loss coefficients (kf) were calculated and correlated as a function of the generalized Reynolds number by the two-k method. The model adjustment was satisfactory and was better in the laminar flow range (0.976 < r2 < 0.999) than in the turbulent flow range (0.774 < r2 < 0.989). In order to test the adequacy of the results for predicting loss coefficients during flow of real fluids, experiments were conducted with coffee extract. Comparison between experimental and predicted loss coefficients showed very good agreement.

http://www.scielo.br/pdf/bjce/v20n4/a12v20n4.pdf

Friction losses in valves and fittings for power-law fluids

Non-Newtonian pseudoplastic liquid flow through small diameter piping components

Publisher Summary Newtonian fluids exhibit a direct proportionality between shear stress and shear rate in the laminar flow region. Non-Newtonian fluids exhibit non linear shear stress-shear rate dependence. A majority of the non-Newtonian fluids are to be found as pseudoplastic in nature, such as rubber solutions, adhesives, polymer solutions, or melts. It displays, on arithmetic coordinates, the concave downward flow curve relationship; on logarithmic coordinates these materials exhibit flow curves having slopes between zero and unity. In the turbulent flow drag reduction phenomena is observed and is due to two different mechanisms. One affects the logarithmic portion of the velocity profile and the other the thickness of the viscous sub-layer. The first type is associated with the action of gravity on a cross-flow density gradient due to either temperature gradient or by varying concentration of suspended particles. The thickening of the viscous sub-layer is obtained in aqueous flows by addition of small quantities of certain long-chain molecules, and these substances act by increasing the size of the smallest, dissipative, turbulent eddies.

Non‐newtonian liquid flow through globe and gate valves

Computational Fluid Dynamics (CFD) analysis for the flow of non-Newtonian and gas-non-Newtonian liquid through elbows is presented. The commercial software Fluent 6.3 has been used for the simulation. Laminar non-Newtonian pseudoplastic power law model has been used for the simulation of non-Newtonian liquid flow through elbows. For twophase flow Elurian-Elurian approach has been used for simulation. The CFD analysis have been tested from our previously published experimental results, Bandyopadhyay and Das (2007), Bandyopadhyay et al. (2000).

https://jafmonline.net/JournalArchive/download?file_ID=26983

Sudip Kumar Das

Papers

Non-newtonian liquid flow in bends