Capabilities and Challenges of CFD in Multiphase Simulation of Hydraulic Tanks

2014 ◽  
Author(s):  
Thees Vollmer ◽  
Johannes Untch
Keyword(s):  
Multiphase Flow ◽  
Single Phase ◽  
Test Bench ◽  
Cfd Simulation ◽  
Air Flow ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Major Purpose ◽  
Flow Models ◽  
Multiphase Models

A major purpose of hydraulic tanks is the segregation of air, which can be supported by different design measures. To improve these measures CFD multiphase simulation can be used, as it is capable to assess the air flow within the oil. The different possibilities of CFD simulation are presented. Here single-phase flow models, simplified multiphase models as well as full multiphase flow models are discussed and evaluated. An example of each presented method is given and the results are compared. Last the capabilities of validating the simulations on a test bench are briefly discussed.

Study on Cooling of Hot Water by Air Flow With Evaporation

2011 ◽  
Author(s):  
Yasuo Koizumi ◽  
Yutaka Ebihara ◽  
Michio Murase
Keyword(s):  
Heat Transfer ◽  
Transfer Coefficient ◽  
Water Temperature ◽  
Single Phase ◽  
Air Flow ◽  
Convection Heat Transfer ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Air Velocity ◽  
Evaporation Heat

Evaporation heat transfer from the hot water flow to the cold air flow in a horizontal and rectangular flow channel was examined. The water temperature was 35°C ∼ 65°C. The air velocity was 0.02 m/s ∼2.57 m/s. The heat transfer rate from the water flow to the air flow became large with an increase in the air velocity and the water temperature. The evaporation heat transfer was much larger than the convection heat transfer and dominant in the heat transfer. The ratio of the evaporation heat transfer rate to the total heat transfer rate was approximately 0.9 ∼ 0.7 in the present experimental conditions. It showed the slightly decreasing tendency for the air velocity. The evaporation heat transfer coefficient showed strong dependency on the air velocity in both the laminar and the turbulent flow region of the air flow. The convection heat transfer coefficient showed the same tendency for the Reynolds number of the air flow as that for the air single-phase flow in the turbulent flow region although the value was much larger than that of the single-phase flow. In the laminar flow region, the convection heat transfer coefficient was constant as in the single-phase flow when the water temperature was low, although the value itself was much larger than that of the single-phase flow. As the water temperature became high, the convection heat transfer coefficient became large and showing dependency on the Reynolds number of the air flow. As the Reynolds number of the air flow became further small, the convection heart transfer coefficient greatly decreased irrespective of the water temperature.

scholarly journals Simulation of Drag Reducer Polymer (DRP) for Single and Annular Two Phase Flow in Horizontal Pipe

2018 ◽  
Vol 13 (2) ◽  
pp. 154-164
Author(s):  
Cindy Dianita ◽  
Asep Handaya Saputra ◽  
Puteri Amelia Khairunissa
Keyword(s):  
Drag Reduction ◽  
Annular Flow ◽  
Single Phase ◽  
Cfd Simulation ◽  
Fluid Velocity ◽  
Flow Equation ◽  
Equation Model ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Two Phase

Drag reducing polymers (DRP) is one of drag reducer types that is widely used in industry as an additive to improve fluid flow efficiency in pipes. This study is conducted to analyze the parameters that influence the efficiency of DRP through developing equation model, and to see the phenomenon of drag reduction that occurs in fluid flow through computational fluid dynamic (CFD) simulation. The data used are obtained from experiments by Vancko (1997) for a single phase flow of water. As for two-phase annular flow, four experiments data are used namely by Vancko (1997), Al-Sarkhi and Hanratty (2001a,b) and Fernandes et al. (2004). Parameters such as fluid velocity and pipe diameter are analyzed based on the model equations proposed in this study. The final single phase flow equation model as the output of this study gives a value for onset drag reduction i.e 4.00 with an error up to 18%. While the proposed annular flow equation with and without drag reduction effect is only suitable when the condition of fluid film distribution is uniform and symmetrical with the error around 20%, i.e. for smaller diameter pipes. The CFD simulation results shows a change in the fluid velocity profile; becoming more parabolic, indicating an increase in the mean fluid velocity up to 0.43%, as the effect of DRP.

Prediction of Solid Particle Erosive Wear of Elbows in Multiphase Annular Flow-Model Development and Experimental Validations

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Quamrul H. Mazumder ◽  
Siamack A. Shirazi ◽  
Brenton S. McLaury
Keyword(s):  
Multiphase Flow ◽  
Solid Particle ◽  
Single Phase ◽  
Solid Particles ◽  
Phase Flow ◽  
Operating Pressure ◽  
Single Phase Flow ◽  
Repeated Impact ◽  
Gas Phases ◽  
Erosion Rates

Erosion damage in the pipe wall due to solid particle impact can cause severe problems in fluid handling industries. Repeated impact of the suspended small solid particles to the inner wall of process equipment and piping removes material from the metal surface. The reduced wall thickness of high pressure equipment and piping can no longer withstand the operating pressure that they were originally designed for and may cause premature failure of the system components. This results in production downtime, safety, and environmental hazards with significant loss to the industry and economy. Prediction of erosion in single-phase flow with sand is a difficult problem due to the effect of different parameters and their interactions that cause erosion. The complexity of the problem increases significantly in multiphase flow where the spatial distribution of the liquid and gas phases and their corresponding velocities change continuously. Most of the currently available erosion prediction models are developed for single-phase flow using empirical data with limited accuracy. A mechanistic model has been developed for predicting erosion in elbows in annular multiphase flow (gas-liquid-solid) considering the effects of particle velocities in gas and liquid phases of the flow. Local fluid phase velocities in multiphase flow are used to calculate erosion rates. The effects of erosion due to impacts of solid particles entrained in the liquid and gas phases are computed separately to determine the total erosion rate. Erosion experiments were conducted to evaluate the model predictions. Comparing the model predicted erosion rates with experimental erosion data showed reasonably good agreement validating the model.

Investigation of Paraffin Deposition During Multiphase Flow in Pipelines and Wellbores—Part 1: Experiments

2002 ◽  
Vol 124 (3) ◽  
pp. 180-186 ◽  
Author(s):  
Ahmadbazlee Matzain ◽  
Mandar S. Apte ◽  
Hong-Quan Zhang ◽  
Michael Volk ◽  
James P. Brill ◽  
...  
Keyword(s):  
Multiphase Flow ◽  
Single Phase ◽  
Liquid Velocity ◽  
Test Facility ◽  
Intermittent Flow ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Wax Deposition ◽  
Two Phase ◽  
Superficial Liquid Velocity

Results are presented from two-phase flow wax deposition tests using a state-of-the-art, high-pressure, multiphase flow test facility. Wax deposition was found to be flow pattern specific and dependent on the flow velocities of the two-phase fluids. Wax deposition occurs only along the pipe wall in contact with a waxy crude oil. An increase in mixture velocity results in harder deposits, but with a lower deposit thickness. The wax buildup trend at low mixture velocities is similar to that observed in laminar single-phase flow tests. The wax buildup trend at high mixture velocities is similar to that observed in turbulent single-phase flow tests. Thinner and harder deposits at the bottom than at the top of the pipe were observed in horizontal and near-horizontal intermittent flow tests. For annular flow tests, thicker and harder deposits were observed at low superficial liquid velocity than at high superficial liquid velocity. In stratified flow tests, no wax deposition was observed along the upper portion of the pipe.

Acoustical Characteristics of Single and Two-Phase Horizontal Pipe Flow Through an Orifice

2017 ◽  
Author(s):  
S. P. C. Belfroid
Keyword(s):  
Multiphase Flow ◽  
Single Phase ◽  
Two Phase Flow ◽  
Jet Noise ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Two Phase ◽  
Horizontal Pipe ◽  
Choked Flow ◽  
Flow Through

In this work, the acoustic effects of horizontal air-water flow through an orifice are investigated experimentally. Single phase flow (air) and two-phase flow (air and water) tests are performed for two sets of orifices. One set of straight edged and one set of upstream rounded orifices. For each set, the diameters of the orifices were 2, 5, and 10mm, with a thickness of 5 mm. The two-phase flow is generated by injecting water at a rate of 0 to 40 g/s to air in a pipe with diameter of 25 mm. The air rate is fixed in the range from 5.8 to 14 g/s, where the upstream pressure varies from 1.5 to 4 bar at ambient temperature. Unsteady pressure fluctuations are recorded at two upstream and two downstream position. The valve noise standard NEN-EN-IEC (60534-8-3, 2011) for dry gas is assessed by means of experimental data in dry conditions at fixed air mass flow rate. Predictions of sound power spectra by means of the standard are found to be more accurate compared to those obtained following Reethof & Ward (1986), also in conditions of a choked orifice. In case of multiphase flow already at very low liquid fractions of much less than 1%, the standard is no longer valid. The frequency spectrum is no longer determined by the jet noise but starts to be dominated by low frequency general multiphase flow. The Strouhal number based on the jet conditions is an order lower than Sr = 0.2 indicating process variations rather than jet noise. Furthermore, at choking conditions the further expansion which occurs in single phase flow is likely different at multiphase flow. For non-choked flow, the standard can be adapted using multiphase mixture properties. This does lead to a good prediction. However at choked conditions, this method fails.

Multiphase Flow Wax Deposition Modeling

2001 ◽  
Author(s):  
Ahmadbazlee Matzain ◽  
Mandar S. Apte ◽  
Hong-Quan Zhang ◽  
Michael Volk ◽  
Clifford L. Redus ◽  
...  
Keyword(s):  
Kinetic Model ◽  
Multiphase Flow ◽  
Single Phase ◽  
Superficial Velocity ◽  
Test Facility ◽  
Intermittent Flow ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Wax Deposition ◽  
Semi Empirical

Abstract Results are presented from two-phase flow wax deposition tests using a state-of-the-art, high pressure, multiphase flow test facility. Wax deposition was found to be flow pattern dependent and occurs only along the pipe wall in contact with the waxy crude oil. The deposition buildup trend at low mixture velocities is similar to that observed in laminar single-phase flow tests. The buildup trend at high mixture velocities is similar to that observed in turbulent single-phase flow tests. Thinner and harder deposits at the bottom than at the top of the pipe were observed in horizontal intermittent flow tests. Thicker and harder deposits were observed at low liquid superficial velocity than at high liquid superficial velocity annular flow tests. No wax deposition was observed along the upper portion of the pipe in stratified flow tests. A semi-empirical kinetic model tailored for the wax deposition tests predicted wax thickness with an acceptable accuracy, especially at high oil superficial velocity. Deposition rate reduction due to shear stripping and rate enhancement due to entrapment of oil and other mechanisms not accounted for by the classical Fick’s mass diffusion theory were incorporated through the use of dimensionless variables and empirical constants derived from the wax deposition data. The kinetic model, although semi-empirical, provides an insight for future model development.

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