scholarly journals On the use of continuous spectrum and discrete-mode differential models to predict contraction-flow pressure drops for Boger fluids

2017 ◽  
Vol 29 (12) ◽  
pp. 121613 ◽  
Author(s):  
J. E. López-Aguilar ◽  
M. F. Webster ◽  
H. R. Tamaddon-Jahromi ◽  
O. Manero ◽  
D. M. Binding ◽  
...  
Keyword(s):  
Continuous Spectrum ◽  
Contraction Flow ◽  
Pressure Drops ◽  
Discrete Mode ◽  
Boger Fluids ◽  
Flow Pressure

scholarly journals Computational Predictions for Boger Fluids and Circular Contraction Flow under Various Aspect Ratios

Fluids ◽  
2020 ◽  
Vol 5 (2) ◽  
pp. 85 ◽  
Author(s):  
J. Esteban López-Aguilar ◽  
Hamid R. Tamaddon-Jahromi
Keyword(s):  
Stress Response ◽  
Normal Stress ◽  
Contraction Flow ◽  
Pressure Drops ◽  
Aspect Ratios ◽  
Model Variant ◽  
Evolution Characteristics ◽  
Contraction Ratio ◽  
Boger Fluids ◽  
Experimental Findings

This work puts forward a modeling study contrasted against experimental, with focus on abrupt circular contraction flow of two highly-elastic constant shear-viscosity Boger fluids, i.e., a polyacrylamide dissolved in corn-syrup PAA/CS (Fluid-1) and a polyisobutylene dissolved in polybutene PIB/PB (Fluid-2), in various contraction-ratio geometries. Moreover, this work goes hand-in-hand with the counterpart matching of experimental pressure-drops observed in such 4:1 and 8:1 aspect-ratio contraction flows, as described experimentally in the literature. In this study, the experimental findings, for Boger fluids with severe strain-hardening features, reveal significant vortex-evolution characteristics, correlated with enhanced pressure-drop phasing and normal-stress response in the corner region. It is shown how such behavior may be replicated through simulation and the rheological dependencies that are necessary to bring this about. Predictive solutions with an advanced hybrid finite-element/volume (fe/fv) algorithm are able to elucidate the rheological properties (extensional viscosity and normal-stress response) that rule such vortex-enhancement evolution. This is accomplished by employing the novel swanINNFM(q) family of fluids, through the swIM model-variant, with its strong and efficient control on elongational properties.

scholarly journals Numerical vs experimental pressure drops for Boger fluids in sharp-corner contraction flow

2016 ◽  
Vol 28 (10) ◽  
pp. 103104 ◽  
Author(s):  
J. E. López-Aguilar ◽  
H. R. Tamaddon-Jahromi ◽  
M. F. Webster ◽  
K. Walters
Keyword(s):  
Sharp Corner ◽  
Contraction Flow ◽  
Pressure Drops ◽  
Boger Fluids ◽  
Experimental Pressure

An investigation of two phase flow pressure drops in a reduced acceleration environment

1993 ◽  
Author(s):  
Montgomery W. Wheeler ◽  
Frederick R. Best ◽  
Thomas R. Reinarts
Keyword(s):  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Pressure Drops ◽  
Flow Pressure

Enhanced Liquid Water Removal From PEM Fuel Cell Flow Channels by Superimposing Acoustic Pressure Wave on Air Flow

2019 ◽  
Author(s):  
Mehdi Mortazavi ◽  
Anthony D. Santamaria ◽  
Jingru Benner ◽  
Vedang Chauhan
Keyword(s):  
Acoustic Pressure ◽  
Air Flow ◽  
Acoustic Vibration ◽  
Flow Channel ◽  
Water Removal ◽  
Two Phase ◽  
Pressure Drops ◽  
Acoustic Pressure Wave ◽  
Water Accumulation ◽  
Flow Pressure

Abstract Enhanced water removal from the flow channel of an ex-situ PEM fuel cell test section is obtained by superimposing acoustic pressure wave on air flow prior to entering into the flow channel. Water accumulation within the flow channel was visualized with a CCD camera and liquid-gas two-phase flow pressure drop was measured along the flow channel. Acoustic pressure waves were superimposed in sine waves at different frequencies between 20 and 120 Hz with a 20-Hz interval. Results indicated that water accumulation in the flow channel was lowest when acoustic pressure waves were superimposed at 80 Hz on air flow. For experiments with no acoustic vibration, the average water slug cumulative area for three runs was obtained at 288.6 mm2 while this average was as low as 43.9 mm2 for experiments conducted at 80 Hz. For other frequencies tested (20, 40, 60, 100, and 120 Hz), water accumulation within the flow channel was less than that for experiments with no vibration but the accumulation of water was still greater than experiments conducted at 80 Hz. The two-phase flow pressure drops were also lowest for experiments conducted at 80 Hz while the highest pressure drops were obtained in experiments with no acoustic vibration. Droplets were also visualized from a side-view angle in a goniometer in order to obtain contact angles. Images showed droplet oscillation under the influence of acoustic vibration. For the three superficial air velocities tested in this study (1.30, 1.82, and 2.30 m/s) the contact angle hysteresis were almost identical with an average value around 40°.

Two-Phase Flow Pressure Drop Measurement in PEM Fuel Cell Flow Channels

2014 ◽  
Author(s):  
Mehdi Mortazavi ◽  
Kazuya Tajiri
Keyword(s):  
Fuel Cell ◽  
Pressure Drop ◽  
Two Phase Flow ◽  
Pem Fuel Cell ◽  
Phase Flow ◽  
Two Phase ◽  
Pressure Drops ◽  
Flow Channels ◽  
Mass Fluxes ◽  
Flow Pressure

Proton exchange membrane (PEM) fuel cells produce power with water and heat as inevitable byproducts. Accumulated liquid water within gas channel blocks the reactant flow and cause pressure drop along the gas channel. It is of extreme importance to accurately predict the liquid and gas two-phase flow pressure drop in PEM fuel cell flow channels. This pressure drop can be considered as an in-situ diagnostic tool that reveals information about the amount of liquid water accumulated within the flow channels. In this paper, the two-phase flow pressure drops are measured in ex-situ PEM fuel cell parallel flow channels. The pressure drops were measured for air mass fluxes of 2.4–6.3kg/m2s and water mass fluxes of 0.0071–1.28kg/m2s. These mass fluxes correspond to 2–5.33m/s and 7.14 × 10−6 – 0.0012m/s air and water superficial velocities, respectively. The measured two-phase flow pressure drops are then compared with different two-phase flow pressure drop models. Qualitative and quantitative comparison between the experimental results and existing models is provided in this work.

scholarly journals Study Pressure Drop for Two-Phase Flow in a Large Diameter Tube

2019 ◽  
Vol 17 (72) ◽  
pp. 101-109
Author(s):  
Muhsen Koli Nahi
Keyword(s):  
Pressure Drop ◽  
Two Phase Flow ◽  
Homogeneous Model ◽  
Large Diameter ◽  
Horizontal Tube ◽  
Phase Flow ◽  
Water Mixture ◽  
Two Phase ◽  
Pressure Drops ◽  
Flow Pressure

The aim of this study is to discover the deviation of two phase flow correlations. A comparsion was made between the expermital values of two-phase flow pressure drops data were obtained experimentally by Al-Jumaily (1999) by using air-water mixture in a horizontal tube of (132 mm) nominal diameter and a test section of (32 m) long at pressure and temperature close to atmospheric and those predicted by three correlations well-used in the literature, which show that the homogeneous model was the best

scholarly journals Experimental Investigation of the Vertical Upward Single- and Two-Phase Flow Pressure Drops Through Gate and Ball Valves

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Ammar Zeghloul ◽  
Hiba Bouyahiaoui ◽  
Abdelwahid Azzi ◽  
Abbas H. Hasan ◽  
Abdelsalam Al-sarkhi
Keyword(s):  
Experimental Investigation ◽  
Pressure Drop ◽  
Single Phase ◽  
Gate Valve ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Flow Conditions ◽  
Two Phase ◽  
Pressure Drops ◽  
Flow Pressure

Abstract This paper presents an experimental investigation of the pressure drop (DP) through valves in vertical upward flows. Experiments were carried out using a 1¼″ (DN 32) ball and gate valve. Five opening areas have been investigated from fully open to the nearly fully closed valve, using air with a superficial velocity of 0–3.5 m/s and water 0.05–0.91 m/s. These ranges cover single-phase and the bubbly, slug and churn two-phase flow regimes. It was found that for the single-phase flow experiments, the valve coefficient increases with the valve opening and is the same, in both valves, for the openings smaller than 40%. The single-phase pressure drop increases with the liquid flowrate and decreases with the opening area. The two-phase flow pressure drop was found considerably increased by reducing the opening area for both valves. It reaches its maximum values at 20% opening for the ball valve and 19% opening for the gate valve. It was also inferred that at fully opening condition, the two-phase flow multiplier, for both valves, has been found close to unity for most of the tested flow conditions. For 40 and 20% valve openings the two-phase multiplier decreases in the power-law with liquid holdup for the studied flow conditions. Models proposed originally for evaluating the pressure drop through an orifice in single-phase and two-phase flows were also applied and assessed in the present experimental data.

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