Pressure Drop of Liquid-Liquid Taylor Flow in Mini-Scale Tubing

2016 ◽  
Author(s):  
W. Adrugi ◽  
Y. S. Muzychka ◽  
K. Pope
Keyword(s):  
Experimental Data ◽  
Theoretical Model ◽  
Pressure Drop ◽  
Flow Rate ◽  
Small Scale ◽  
Flow Rates ◽  
Constant Flow Rate ◽  
Taylor Flow ◽  
Low Viscosity ◽  
Wide Range

In this paper, the pressure drop of liquid-liquid segmented flow in small-scale tubing is investigated with experimental and analytical methods. A theoretical model is developed for describing the total pressure drop as a function of slug length and Capillary number. The experiments are conducted with low Reynolds number flows in horizontal, straight mini-scale tubes. A segmented (Taylor) flow is created using several low viscosity silicone oils (1, 3, 5 cSt) and water with a wide range of flow rates. The experimental setup allows the independent variation of liquid slug lengths. The liquids are injected into the mini-scale tubes at a variable (pulsed) flow rate for one liquid, and a constant flow rate for another liquid. The variation of liquid types and flow rates causes numerous combinations of Prandtl, Reynolds, and Capillary numbers to be tested. The theoretical and experimental data is presented in terms of the dimensionless groups fRe or ΔP* and Le* to predict pressure drop in liquid-liquid Taylor flow. The new experimental data agrees well with the new theoretical model of Taylor flow in miniscale tubes. The results of this paper indicate the pressure drop for Taylor flow is higher than in single-phase flow, likely due to the interfacial effects in liquid slugs.

Heat Transfer in Liquid-Liquid Taylor Flow in a Mini-Scale Tube With Constant Wall Temperature

2015 ◽  
Author(s):  
W. M. Adrugi ◽  
Y. S. Muzychka ◽  
K. Pope
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Wall Temperature ◽  
Silicone Oil ◽  
Transfer Enhancement ◽  
Constant Wall Temperature ◽  
Flow Rates ◽  
Taylor Flow ◽  
Low Viscosity ◽  
Wide Range

In this paper, heat transfer enhancement using liquid-liquid Taylor flow is examined. The experiments are conducted in mini-scale tubes with constant wall temperature. The segmented flow is created using several fractions of low viscosity silicone oil (1 cSt) and water for a wide range of flow rates and segment lengths. The variety of liquids and flow rates change the Prandtl, Reynolds, and capillary numbers. The dimensionless mean wall flux and the dimensionless thermal flow length are used to analyze the experimental heat transfer data. The comparison shows the heat transfer rate for Taylor flow is higher than in single-phase flow. The heat transfer enhancement occurs due to internal circulation in the fluid segments.

scholarly journals Hydraulic characteristic of collagen

2016 ◽  
Vol 33 (No. 5) ◽  
pp. 479-485 ◽  
Author(s):  
R. Žitný ◽  
A. Landfeld ◽  
J. Skočilas ◽  
J. Stancl ◽  
V. Flegl ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Flow Rate ◽  
Limited Range ◽  
Hydraulic Characteristic ◽  
Hydraulic Characteristics ◽  
Flow Rates ◽  
Transient Flows ◽  
Wide Range ◽  
On Line ◽  
Collagenous Material

Hydraulic characteristic of collagen. Czech J. Food Sci., 33: 479–485. The hysteresis of a hydraulic characteristic while pumping an aqueous solution of collagen through a pipe at gradually increasing and decreasing flow rates (hysteresis means that the pressure drop curve during increased flow rate is above the pressure drop during decreasing flow rate) was observed. The problem was initiated by industry and by demand for an on-line recording of rheological properties of collagenous material used for extrusion of collagen casings. The Herschel-Bulkley rheological model was capable to describe rheograms in a wide range of deformation rates; however it was not able to describe and explain the hysteresis. As a possible reason thixotropic properties were identified and the hydraulic characteristic was calculated using a thixotropic generalisation of the Herschel-Bulkley model. The developed 1D numerical model can be applied for on-line modelling of transient flows of incompressible thixotropic food materials (startup flow) and at a limited range of flow rates it is also capable to describe the hysteresis of hydraulic characteristics.

scholarly journals Flow Rate Dependence of Ventilation

1987 ◽  
Vol 14 (1) ◽  
pp. 11-19
Author(s):  
DE Mathis
Keyword(s):  
Pressure Drop ◽  
Flow Rate ◽  
Continuous Flow ◽  
Quantitative Model ◽  
Rate Dependence ◽  
Experimental Measurements ◽  
Flow Rates ◽  
Flow Dependence ◽  
Wide Range ◽  
Flow Pressure

AbstractA quantitative model describing the effects of puffing conditions on the level of filter ventilation was developed and evaluated. The development of the model was based on a quadratic flow-pressure drop relationship which was validated with experimental measurements for numerous plug wraps, tipping papers, and combinations of the two. This relationship was used to derive an equation describing the level of filter ventilation as a function of the flow rate of air exiting the filter. This equation was shown to accurately predict the measured ventilations of six brands of commercial cigarettes over a range of continuous flow rates. The instantaneous ventilation values predicted by the equation were utilized to model ventilation during a puff by integrating the equation with respect to flow rate over the duration of the puff. This method for predicting the effects of specific puffing conditions on ventilation was demonstrated for sinusoidally shaped puffs spanning a wide range of volume and duration. Finally, the effects on the flow dependence of ventilation of different combinations of plug wrap and tipping papers were described qualitatively based on experimental measurements of paper flow-pressure drop linearity.

Permeability Testing of Ceramic Foam Filters

2015 ◽  
Author(s):  
Halsey Ostergaard ◽  
Patrick Dailey ◽  
Mahabub Alam ◽  
John Parmigiani
Keyword(s):  
Pressure Drop ◽  
Flow Rate ◽  
Surface Defects ◽  
Analytical Formula ◽  
Ceramic Foam ◽  
Low Flow ◽  
Quadratic Model ◽  
Working Fluid ◽  
Flow Rates ◽  
Constant Flow Rate

The construction and validation of an apparatus for measuring the permeability of ceramic foam filters (CFFs) at varying water flow rates is presented here. Commercially available CFFs are specified by pores per inch, which does not uniquely determine the flow characteristics of CFFs. Permeability, the pressure drop per unit filter thickness as a function of velocity, is desired for modeling and quality control purposes. Permeability is typically described with the Forchheimer equation, which can be broken into linear (Darcy) and quadratic (non-Darcy) components. Linear dependence comes from laminar flow at low flow rates, and is scaled by viscosity, while the square dependence dominates at high flow rates, and is scaled by fluid density. CFF measurement systems are not commercially available, and while several examples are found in literature, they are expensive and labor intensive to operate, and are usually limited to specific sizes of filter. The methodology, apparatus, and verification work presented here aims to reduce the cost, time, and complexity of measuring the permeability of commercially available CFFs of different sizes and porosities. Water is used as the working fluid, which is pumped through a CFF held in a modular cartridge. Pressure transducers are mounted close to the filter on either side. For testing different diameters of commercially available CFFs, different inlet and outlet pipe sizes are used to approximately match the diameter of the filter. This approach avoids the need for computational modeling of an effective filter diameter when the pipe and filter diameters do not match. Long, straight rigid pipe runs are used on the inlet to ensure fully developed flow profiles. Flow is measured with a magnetic flow meter. Pressure drop and flow rate are recorded at discrete flow rates after allowing the system to settle to a constant flow rate. A continuously variable methodology was evaluated and rejected. During testing, it was found that the decreased viscosity of water heated by the pump during long testing runs affected the measured permeability. To compensate, water temperature is measured during each run, and the viscosity is calculated for each run. The linear and quadratic permeability coefficients are determined by fitting a quadratic model through pressure drop data as a function of flow rate. In order to verify the accuracy of the device, a validation disc was created. A 49.6 mm disc of aluminum was drilled with 1,467 evenly spaced holes. An analytical formula from literature was used to calculate the theoretical permeability of the array. The measured permeability was below the calculated value, but surface defects in the disk were shown to have a large impact on measured permeability.

Simultaneous Measuring Method for Both Volumetric Flow Rates of Air-Water Mixture Using a Turbine Flowmeter

1996 ◽  
Vol 118 (1) ◽  
pp. 29-35 ◽  
Author(s):  
K. Minemura ◽  
K. Egashira ◽  
K. Ihara ◽  
H. Furuta ◽  
K. Yamamoto
Keyword(s):  
Pressure Drop ◽  
Flow Rate ◽  
Volumetric Flow Rate ◽  
Oil Field ◽  
Liquid Density ◽  
Water Mixture ◽  
Rotor Speed ◽  
Flow Rates ◽  
Field Development ◽  
Turbine Flowmeter

A turbine flowmeter is employed in this study in connection with offshore oil field development, in order to measure simultaneously both the volumetric flow rates of air-water two-phase mixture. Though a conventional turbine flowmeter is generally used to measure the single-phase volumetric flow rate by obtaining the rotational rotor speed, the method proposed additionally reads the pressure drop across the meter. After the pressure drop and rotor speed measured are correlated as functions of the volumetric flow ratio of the air to the whole fluid and the total volumetric flow rate, both the flow rates are iteratively evaluated with the functions on the premise that the liquid density is known. The evaluated flow rates are confirmed to have adequate accuracy, and thus the applicability of the method to oil fields.

Subsynchronous Vibration Patterns Under Reduced Oil Supply Flow Rates

2017 ◽  
Author(s):  
B. R. Nichols ◽  
R. L. Fittro ◽  
C. P. Goyne
Keyword(s):  
Flow Rate ◽  
High Speed ◽  
Operating Conditions ◽  
System Stability ◽  
Supporting Evidence ◽  
Test Rig ◽  
Flow Rates ◽  
Oil Supply ◽  
Bending Mode ◽  
Wide Range

Many high-speed, rotating machines across a wide range of industrial applications depend on fluid film bearings to provide both static support of the rotor and to introduce stabilizing damping forces into the system through a developed hydrodynamic film wedge. Reduced oil supply flow rate to the bearings can cause cavitation, or a lack of a fully developed film layer, at the leading edge of the bearing pads. Reducing oil flow has the well-documented effects of higher bearing operating temperatures and decreased power losses due to shear forces. While machine efficiency may be improved with reduced lubricant flow, little experimental data on its effects on system stability and performance can be found in the literature. This study looks at overall system performance of a test rig operating under reduced oil supply flow rates by observing steady-state bearing performance indicators and baseline vibrational response of the shaft. The test rig used in this study was designed to be dynamically similar to a high-speed industrial compressor. It consists of a 1.55 m long, flexible rotor supported by two tilting pad bearings with a nominal diameter of 70 mm and a span of 1.2 m. The first bending mode is located at approximately 5,000 rpm. The tiling-pad bearings consist of five pads in a vintage, flooded bearing housing with a length to diameter ratio of 0.75, preload of 0.3, and a load-between-pad configuration. Tests were conducted over a number of operating speeds, ranging from 8,000 to 12,000 rpm, and bearing loads, while systematically reducing the oil supply flow rates provided to the bearings under each condition. For nearly all operating conditions, a low amplitude, broadband subsynchronous vibration pattern was observed in the frequency domain from approximately 0–75 Hz. When the test rig was operated at running speeds above its first bending mode, a distinctive subsynchronous peak emerged from the broadband pattern at approximately half of the running speed and at the first bending mode of the shaft. This vibration signature is often considered a classic sign of rotordynamic instability attributed to oil whip and shaft whirl phenomena. For low and moderate load conditions, the amplitude of this 0.5x subsynchronous peak increased with decreasing oil supply flow rate at all operating speeds. Under the high load condition, the subsynchronous peak was largely attenuated. A discussion on the possible sources of this subsynchronous vibration including self-excited instability and pad flutter forced vibration is provided with supporting evidence from thermoelastohydrodynamic (TEHD) bearing modeling results. Implications of reduced oil supply flow rate on system stability and operational limits are also discussed.

Two-Phase Flow Behavior in Channels With Sudden Area Change Using Experimental and Computational Approach

2017 ◽  
Author(s):  
Ashish Kotwal ◽  
Che-Hao Yang ◽  
Clement Tang
Keyword(s):  
Experimental Data ◽  
Pressure Drop ◽  
Experimental Analysis ◽  
Single Phase ◽  
Computational Analysis ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Two Phase ◽  
Flow Rates ◽  
Area Change

The current study shows computational and experimental analysis of multiphase flows (gas-liquid two-phase flow) in channels with sudden area change. Four test sections used for sudden contraction and expansion of area in experiments and computational analysis. These are 0.5–0.375, 0.5–0.315, 0.5–0.19, 0.5–0.14, inversely true for expansion channels. Liquid Flow rates ranging from 0.005 kg/s to 0.03 kg/s employed, while gas flow rates ranging from 0.00049 kg/s to 0.029 kg/s implemented. First, single-phase flow consists of only water, and second two-phase Nitrogen-Water mixture flow analyzed experimentally and computationally. For Single-phase flow, two mathematical models used for comparison: the two transport equations k-epsilon turbulence model (K-Epsilon), and the five transport equations Reynolds stress turbulence interaction model (RSM). A Eulerian-Eulerian multiphase approach and the RSM mathematical model developed for two-phase gas-liquid flows based on current experimental data. As area changes, the pressure drop observed, which is directly proportional to the Reynolds number. The computational analysis can show precise prediction and a good agreement with experimental data when area ratio and pressure differences are smaller for laminar and turbulent flows in circular geometries. During two-phase flows, the pressure drop generated shows reasonable dependence on void fraction parameter, regardless of numerical analysis and experimental analysis.

Determinants of flow across isolated gastroduodenal junctions of cats and rabbits

1983 ◽  
Vol 245 (2) ◽  
pp. G257-G264 ◽  
Author(s):  
K. Schulze-Delrieu ◽  
J. P. Wall
Keyword(s):  
Flow Rate ◽  
High Yield ◽  
Pressure Waves ◽  
Base Line ◽  
Tonic Activity ◽  
Flow Rates ◽  
Wide Range ◽  
Line Flow ◽  
Pressure Resistance ◽  
Unidirectional Valve

The resistance generated by the gastroduodenal junction was measured in isolated cat and rabbit preparations. Cannulas were tied into the antrum and duodenum. Yield pressures were determined by increasing the pressure in one of the cannulas until flow occurred. The junctional segment of the cat maintained a high yield pressure. Yield pressures were similar in the antroduodenal and the duodenogastric direction (12.5 +/- 5.7 vs. 14.8 5.8 cmH2O) and increased on both sides to the same degree following exposure of the preparation to 100 mM [K+] and to 10(-6) M carbachol. These experimental manipulations also led to the occurrence of pressure waves in the antral cannula. Yield pressures were diminished but not abolished by exposure of the preparation to 0 [Ca2+] solution or 10(-6) M isoproterenol. Junctional segments from the rabbit did not maintain a yield pressure. Resistance across the junctional segment of both species was also measured by channeling the outflow of one of the cannulas to a flowmeter. Over a wide range of pressures, flow rates across the junctional segment of the rabbit exceeded those across the junctional segment of the cat. Carbachol and 100 mM [K+] decreased the base-line flow and increased the amplitude of intermittent decreases of flow. Isoproterenol and 0 [Ca2+] had opposite effects. Inflation of a balloon decreased the flow rate across the rabbit but not the cat junctional segment. Flow rates across the junctional segment did not differ in the antroduodenal and duodenogastric direction. The gastroduodenal junction does not act as an unidirectional valve. Pyloric resistance relates to the structure of the pyloric segment and to phasic and tonic activity of its musculature.

An Experimental Study of the Flow of R-407C in an Adiabatic Spiral Capillary Tube

2009 ◽  
Vol 1 (4) ◽  
Author(s):  
M. K. Mittal ◽  
R. Kumar ◽  
A. Gupta
Keyword(s):  
Experimental Data ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Capillary Tube ◽  
Flow Characteristics ◽  
Flow Rates ◽  
Tube Test ◽  
Mass Flow Rates ◽  
R 134A

The objective of this study is to investigate the effect of coiling on the flow characteristics of R-407C in an adiabatic spiral capillary tube. The characteristic coiling parameter for a spiral capillary tube is the coil pitch; hence, the effect of the coil pitch on the mass flow rate of R-407C was studied on several capillary tube test sections. It was observed that the coiling of the capillary tube significantly reduced the mass flow rate of R-407C in the adiabatic spiral capillary tube. In order to quantify the effect of coiling, the experiments were also conducted for straight a capillary tube, and it was observed that the coiling of the capillary tube reduced the mass flow rate in the spiral tube in the range of 9–18% as compared with that in the straight capillary tube. A generalized nondimensional correlation for the prediction of the mass flow rates of various refrigerants was developed for the straight capillary tube on the basis of the experimental data of R-407C of the present study, and the data of R-134a, R-22, and R-410A measured by other researchers. Additionally, a refrigerant-specific correlation for the spiral capillary was also proposed on the basis of the experimental data of R-407C of the present study.

Prediction of Ingestion Through Turbine Rim Seals—Part II: Externally Induced and Combined Ingress

2010 ◽  
Vol 133 (3) ◽  
Author(s):  
J. Michael Owen
Keyword(s):  
Experimental Data ◽  
Flow Rate ◽  
Gas Turbines ◽  
Swirling Flows ◽  
Published Data ◽  
Flow Rates ◽  
Hot Gas ◽  
Predicted Values ◽  
Good Agreement

Ingress of hot gas through the rim seals of gas turbines can be modeled theoretically using the so-called orifice equations. In Part I of this two-part paper, the orifice equations were derived for compressible and incompressible swirling flows, and the incompressible equations were solved for axisymmetric rotationally induced (RI) ingress. In Part II, the incompressible equations are solved for nonaxisymmetric externally induced (EI) ingress and for combined EI and RI ingress. The solutions show how the nondimensional ingress and egress flow rates vary with Θ0, the ratio of the flow rate of sealing air to the flow rate necessary to prevent ingress. For EI ingress, a “saw-tooth model” is used for the circumferential variation of pressure in the external annulus, and it is shown that ε, the sealing effectiveness, depends principally on Θ0; the theoretical variation of ε with Θ0 is similar to that found in Part I for RI ingress. For combined ingress, the solution of the orifice equations shows the transition from RI to EI ingress as the amplitude of the circumferential variation of pressure increases. The predicted values of ε for EI ingress are in good agreement with the available experimental data, but there are insufficient published data to validate the theory for combined ingress.

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