scholarly journals The Influence of Inflow Swirl on Cavitating and Mixing Processes in a Venturi Tube

Fluids ◽  
2020 ◽  
Vol 5 (4) ◽  
pp. 170
Author(s):  
Hongbo Shi ◽  
Petr Nikrityuk
Keyword(s):  
Pressure Drop ◽  
Volume Fraction ◽  
Pure Water ◽  
Swirl Flow ◽  
Linear Increase ◽  
Venturi Tube ◽  
Fluid Viscosity ◽  
Multiphase Model ◽  
Mixing Processes ◽  
Ansys Fluent

A study of the mixing flows (Schmidt number = 103) in a cavitating Venturi tube that feature linear and swirling flows is presented in this paper. The Large Eddy Simulation (LES) turbulence model, the Schnerr–Sauer cavitation model, and the mixture multiphase model, as implemented in the commercial CFD ANSYS FLUENT 16.2, were employed. The main emphasis is spending on the influence of different inlet swirling ratios on the generation of cavitation and mixing behaviors in a Venturi tube. Four different inflow regimes were investigated for the Reynolds number Re = 19,044, 19,250, 19,622, 21,276: zero swirl, 15% swirl, 25% swirl and 50% swirl velocity relative to the transverse inflow velocity, respectively. The computed velocity and pressure profiles were shown in good agreement with the experiment data from the literature. The predicted results indicate that the imposed swirl flow moves the cavitation bubbles away from throat surfaces toward the throat axis. The rapid mixing between two volumetric components is promoted in the divergent section when the intense swirl is introduced. Additionally, the increase in the swirl ratio from 0.15 to 0.5 leads to a linear increase in the static pressure drop and a nonlinear increase in the vapor production. The reduction in the fluid viscosity ratio from μ2μ1=10 to μ2μ1=1 generates a high cavitation intensity in the throat of the Venturi tube. However, the changes in the pressure drop and vapor volume fraction are significantly small of pure water flow.

On the Computational Modeling of Unfluidized and Fluidized Bed Dynamics

2014 ◽  
Vol 136 (10) ◽  
Author(s):  
Lindsey C. Teaters ◽  
Francine Battaglia
Keyword(s):  
Experimental Data ◽  
Pressure Drop ◽  
Multiphase Flow ◽  
Fluidized Bed ◽  
Void Fraction ◽  
Volume Fraction ◽  
Flow Modeling ◽  
Ansys Fluent ◽  
Minimum Fluidization Velocity ◽  
Two Factors

Two factors of great importance when considering gas–solid fluidized bed dynamics are pressure drop and void fraction, which is the volume fraction of the gas phase. It is, of course, possible to obtain pressure drop and void fraction data through experiments, but this tends to be costly and time consuming. It is much preferable to be able to efficiently computationally model fluidized bed dynamics. In the present work, ANSYS Fluent® is used to simulate fluidized bed dynamics using an Eulerian–Eulerian multiphase flow model. By comparing the simulations using Fluent to experimental data as well as to data from other fluidized bed codes such as Multiphase Flow with Interphase eXchanges (MFIX), it is possible to show the strengths and limitations with respect to multiphase flow modeling. The simulations described herein will present modeling beds in the unfluidized regime, where the inlet gas velocity is less than the minimum fluidization velocity, and will deem to shed some light on the discrepancies between experimental data and simulations. In addition, this paper will also include comparisons between experiments and simulations in the fluidized regime using void fraction.

scholarly journals Numerical simulation and comparative analysis of pressure drop estimation in horizontal and vertical slurry pipeline

2020 ◽  
Vol 14 (2) ◽  
pp. 6610-6624 ◽  
Author(s):  
Om Parkash Verma ◽  
Arvind Kumar ◽  
Basant Singh Sikarwar
Keyword(s):  
Numerical Simulation ◽  
Pressure Drop ◽  
Power Plants ◽  
Flow Behavior ◽  
Three Dimensional ◽  
Multiphase Model ◽  
Solid Concentration ◽  
Mean Flow ◽  
Ansys Fluent ◽  
Spherical Diameter

Transportation of solids with water as a carrier in the form of slurry through long length pipelines is widely used by many industries and power plants. The transportation of slurry through vertical pipeline is a challenging task and require modification to overcome the pressure loss and power consumption requirements. In this perspective, numerical simulation of three-dimensional horizontal slurry pipeline (HSPL) and vertical slurry pipeline (VSPL) carrying glass beads solid particulates of spherical diameter 440 µm and density 2,470 kg/m3 is carried out. The 3D computational model for horizontal and vertical slurry pipeline is developed for a pipe of 0.0549 m diameter and analyzed in available commercial software ANSYS Fluent 16. The simulation is conducted by using Eulerian multiphase model with RNG k-ɛ turbulence closure at solid concentration range 10 – 20% (by volume) for mean flow velocities ranging from 1-4 ms-1. It is found that the pressure drop rises for both HSPL and VSPL with escalation in mean flow velocity and solid concentration. The predicted pressure drop in VSPL is found to follow the same pattern as with HSPL but higher in magnitude for all chosen velocity and solid concentration range. The obtained results of predicted pressure drop in HSPL are validated with the available experimental data in the literature. A parametric study is conducted with the aim of visualizing and understanding the slurry flow behavior in HSPL and VSPL. Finally, the results of solid concentration contour, velocity contour, solid concentration profiles, velocity profiles and pressure drop are predicted for both the slurry pipelines.

scholarly journals Thermal Performance of Nanofluid Flow Inside Evacuated Tube Solar Collector

2021 ◽  
Vol 39 (4) ◽  
pp. 1262-1270
Author(s):  
Mohammad H. Yazdi ◽  
Evgeny Solomin ◽  
Ahmad Fudholi ◽  
Ghasem Divandari ◽  
Kamaruzzaman Sopian ◽  
...  
Keyword(s):  
Thermal Efficiency ◽  
Solar Collector ◽  
Volume Fraction ◽  
Flow Behavior ◽  
Pure Water ◽  
Radiant Energy ◽  
Solar Collectors ◽  
Nanofluid Flow ◽  
Ansys Fluent ◽  
Solar Radiation Incident

Solar collectors are systems for absorbing the sun's radiant energy and converting it into heat. The working principle of solar collectors are relying on the solar radiation incident upon the transparent surface, and the collected radiation heat is stored within the operating fluid. However, the conventional operating fluid is less than satisfactory in term of promoting the thermal efficiency of solar collector. Consequently, the aim of this paper is to investigate the use of nanofluid as an operating fluid in a single end evacuated solar collector. The expectation is that the flow behavior of nanofluid can lead to the improvement of thermal efficiency of solar collector. The design of solar collector is carried out using Gambit software and the heat transfer characteristics are simulated by nanofluid flow with 1%, 3% and 5% volumes by ANSYS Fluent software. The results demonstrate good agreement with existing experimental results. The numerical analysis shows the improvement of collector performance compared to pure water fluid. The results show that by increasing the nanoparticles volume fraction the efficiency of the collector improves significantly.

Numerical investigation of the effect of water/Al2O3 nanofluid on heat transfer in trapezoidal, sinusoidal and stepped microchannels

2019 ◽  
Vol 30 (5) ◽  
pp. 2439-2465 ◽  
Author(s):  
Vahid Jaferian ◽  
Davood Toghraie ◽  
Farzad Pourfattah ◽  
Omid Ali Akbari ◽  
Pouyan Talebizadehsardari
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Cross Section ◽  
Cross Sections ◽  
Volume Fraction ◽  
Pure Water ◽  
Circular Cross Section ◽  
Reynolds Numbers ◽  
Two Phase ◽  
Content Type

Purpose The purpose of this study is three-dimensional flow and heat transfer investigation of water/Al2O3 nanofluid inside a microchannel with different cross-sections in two-phase mode. Design/methodology/approach The effect of microchannel walls geometry (trapezoidal, sinusoidal and stepped microchannels) on flow characteristics and also changing circular cross section to trapezoidal cross section in laminar flow at Reynolds numbers of 50, 100, 300 and 600 were investigated. In this study, two-phase water/Al2O3 nanofluid is simulated by the mixture model, and the effect of volume fraction of nanoparticles on performance evaluation criterion (PEC) is studied. The accuracy of obtained results was compared with the experimental and numerical results of other similar papers. Findings Results show that in flow at lower Reynolds numbers, sinusoidal walls create a pressure drop in pure water flow which improves heat transfer to obtain PEC < 1. However, in sinusoidal and stepped microchannel with higher Reynolds numbers, PEC > 1. Results showed that the stepped microchannel had higher pressure drop, better thermal performance and higher PEC than other microchannels. Originality/value Review of previous studies showed that existing papers have not compared and investigated nanofluid in a two-phase mode in inhomogeneous circular, stepped and sinusoidal cross and trapezoidal cross-sections by considering the effect of changing channel shape, which is the aim of the present paper.

CFD Study the Influence of Solid Phase on the Pump Performance

2014 ◽  
Author(s):  
Mikhail P. Strongin
Keyword(s):  
Flow Rate ◽  
Volume Fraction ◽  
Solid Phase ◽  
Pure Water ◽  
Solid Particles ◽  
Spherical Particles ◽  
Multiphase Model ◽  
Solid Mixture ◽  
Water Transportation ◽  
Pump Head

In the water transportation applications of the liquid-solid mixture pumping is very common. Among these applications the submersible well pumps, dewatering, drainage, and irrigation could be mentioned. In this work, CFD study of influence of amount of solid phase in the solid-liquid mixture on the pump parameters is presented. Two stages vertical mixed flow pump was modeled. Fluent 14.5.7 commercial code was used for simulations. Mixer multiphase model can be used to model multiphase flows where the phases move at different velocities, but assume local equilibrium over short spatial length scales. Therefore, it was chosen for mixture model. SST k-ω model for turbulence was selected. Multi-reference frame approach was used for rotation domains. All mixtures in the presented work have water as their primary phase; the secondary phase is assumed to be a continuum of solid spherical particles of silicon with diameters that range from 0.1 mm to 0.4 mm. The load of the solid particles ranges from 0.5% to 10% of volume fraction of the mixture on the pump inlet. The total number of the mesh cells was 9 million. Calculations of the pump head for mixture and for pure water were done using the same water flow rate. Comparison of the results shows that they are close within ∼1% difference. It needs to be emphasized that the pump head is determined by the liquid phase. On the other hand, the efficiency of the pump with high solid phase load was much lower in comparison with the same flow rate of water for pure water case. These results may help in designing pumps for transporting liquid-solid mixture.

On the Computational Modeling of Unfluidized and Fluidized Bed Dynamics

2012 ◽  
Author(s):  
Lindsey C. Teaters ◽  
Francine Battaglia
Keyword(s):  
Experimental Data ◽  
Pressure Drop ◽  
Multiphase Flow ◽  
Fluidized Bed ◽  
Void Fraction ◽  
Volume Fraction ◽  
Flow Modeling ◽  
Ansys Fluent ◽  
Minimum Fluidization Velocity ◽  
Two Factors

Two factors of great importance when considering gas-solid fluidized bed dynamics are pressure drop and void fraction, which is the volume fraction of the gas phase. It is, of course, possible to obtain pressure drop and void fraction data through experimentation, but this tends to be costly and time consuming. It is much preferable to be able to efficiently computationally model fluidized bed dynamics. In the present work, ANSYS FLUENT is used to simulate fluidized bed dynamics using an Eulerian-Eulerian multiphase flow model. By comparing the simulations using FLUENT to experimental data as well as to data from other fluidized bed codes such as Multiphase Flow with Interphase eXchanges (MFIX), it is possible to show the strengths and limitations of FLUENT with respect to multiphase flow modeling. The simulations described herein will focus on modeling of beds in the unfluidized regime, where the inlet gas velocity is less than the minimum fluidization velocity, and will deem to shed some light on the discrepancies between experimental data and FLUENT results. In addition, this paper will also include comparisons between experimental data and simulation data in the fluidized regime based on void fraction contours and profiles.

Study on the Flow Characteristics of Shengli Oilfield Super Heavy Oil

2017 ◽  
Vol 10 (1) ◽  
pp. 69-78 ◽  
Author(s):  
Wang Shou-long ◽  
Li Ai-fen ◽  
Peng Rui-gang ◽  
Yu Miao ◽  
Fu Shuai-shi
Keyword(s):  
Pressure Drop ◽  
Pressure Gradient ◽  
Heavy Oil ◽  
Flow Characteristics ◽  
Fluid Viscosity ◽  
Linear Flow ◽  
Start Up ◽  
Non Linear ◽  
Core Permeability ◽  
Velocity Pressure

Objective:The rheological properties of oil severely affect the determination of percolation theory, development program, production technology and oil-gathering and transferring process, especially for super heavy oil reservoirs. This paper illustrated the basic seepage morphology of super heavy oil in micro pores based on its rheological characteristics.Methods:The non-linear flow law and start-up pressure gradient of super heavy oil under irreducible water saturation at different temperatures were performed with different permeable sand packs. Meanwhile, the empirical formulas between start-up pressure gradient, the parameters describing the velocity-pressure drop curve and the ratio of gas permeability of a core to fluid viscosity were established.Results:The results demonstrate that temperature and core permeability have significant effect on the non-linear flow characteristics of super heavy oil. The relationship between start-up pressure gradient of oil, the parameters representing the velocity-pressure drop curve and the ratio of core permeability to fluid viscosity could be described as a power function.Conclusion:Above all, the quantitative description of the seepage law of super heavy oil reservoir was proposed in this paper, and finally the empirical diagram for determining the minimum and maximum start-up pressure of heavy oil with different viscosity in different permeable formations was obtained.

scholarly journals Simulation approach on turbulent thermal performance factor of Al2O3-Cu/water hybrid nanofluid in circular and non-circular ducts

2021 ◽  
Vol 3 (3) ◽  
Author(s):  
Ing Jiat Kendrick Wong ◽  
Ngieng Tze Angnes Tiong
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Pressure Drop ◽  
Thermal Performance ◽  
Heat Transfer Performance ◽  
Pure Water ◽  
Hybrid Nanofluid ◽  
Performance Factor ◽  
Thermal Performance Factor ◽  
The Heat Transfer Coefficient

AbstractThis paper presents the numerical study of thermal performance factor of Al2O3-Cu/water hybrid nanofluid in circular and non-circular ducts (square and rectangular). Turbulent regime is studied with the Reynolds number ranges from 10000 to 100000. The heat transfer performance and flow behaviour of hybrid nanofluid are investigated, considering the nanofluid volume concentration between 0.1 and 2%. The thermal performance factor of hybrid nanofluid is evaluated in terms of performance evaluation criteria (PEC). This present numerical results are successfully validated with the data from the literature. The results indicate that the heat transfer coefficient and Nusselt number of Al2O3-Cu/water hybrid nanofluid are higher than those of Al2O3/water nanofluid and pure water. However, this heat transfer enhancement is achieved at the expense of an increased pressure drop. The heat transfer coefficient of 2% hybrid nanofluid is approximately 58.6% larger than the value of pure water at the Reynolds number of 10000. For the same concentration and Reynolds number, the pressure drop of hybrid nanofluid is 4.79 times higher than the pressure drop of water. The heat transfer performance is the best in the circular pipe compared to the non-circular ducts, but its pressure drop increment is also the largest. The hybrid nanofluid helps to improve the problem of low heat transfer characteristic in the non-circular ducts. In overall, the hybrid nanofluid flow in circular and non-circular ducts are reported to possess better thermal performance factor than that of water. The maximum attainable PEC is obtained by 2% hybrid nanofluid in the square duct at the Reynolds Number of 60000. This study can help to determine which geometry is efficient for the heat transfer application of hybrid nanofluid.

scholarly journals The Influence of Different Types of Nanofluid on Thermal and Fluid Flow Performance of Liquid Cold Plate

2018 ◽  
Vol 7 (4.35) ◽  
pp. 148 ◽  
Author(s):  
Nur Irmawati Om ◽  
Rozli Zulkifli ◽  
P. Gunnasegaran
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Steady State ◽  
Pressure Drop ◽  
Volume Fraction ◽  
Cold Plate ◽  
Governing Equations ◽  
Flow And Heat Transfer ◽  
Different Types ◽  
Volume Method

The influence of utilizing different nanofluids types on the liquid cold plate (LCP) is numerically investigated. The thermal and fluid flow performance of LCP is examined by using pure ethylene glycol (EG), Al2O3-EG and CuO-EG. The volume fraction of the nanoparticle for both nanofluid is 2%. The finite volume method (FVM) has been used to solved 3-D steady state, laminar flow and heat transfer governing equations. The presented results indicate that Al2O3-EG able to provide the lowest surface temperature of the heater block followed by CuO-EG and EG, respectively. It is also found that the pressure drop and friction factor are higher for Al2O3-EG and CuO-EG compared to the pure EG.

Genetic Programming based Drag Model with Improved Prediction Accuracy for Fluidization Systems

2017 ◽  
Vol 15 (2) ◽  
Author(s):  
R. R. Sonolikar ◽  
M. P. Patil ◽  
R. B. Mankar ◽  
S. S. Tambe ◽  
B. D. Kulkarni
Keyword(s):  
Pressure Drop ◽  
Genetic Programming ◽  
Drag Coefficient ◽  
Prediction Accuracy ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Superior Performance ◽  
Momentum Exchange ◽  
Drag Model ◽  
Parameter Ranges

Abstract The drag coefficient plays a vital role in the modeling of gas-solid flows. Its knowledge is essential for understanding the momentum exchange between the gas and solid phases of a fluidization system, and correctly predicting the related hydrodynamics. There exists a number of models for predicting the magnitude of the drag coefficient. However, their major limitation is that they predict widely differing drag coefficient values over same parameter ranges. The parameter ranges over which models possess a good drag prediction accuracy are also not specified explicitly. Accordingly, the present investigation employs Geldart’s group B particles fluidization data from various studies covering wide ranges of Re and εs to propose a new unified drag coefficient model. A novel artificial intelligence based formalism namely genetic programming (GP) has been used to obtain this model. It is developed using the pressure drop approach, and its performance has been assessed rigorously for predicting the bed height, pressure drop, and solid volume fraction at different magnitudes of Reynolds number, by simulating a 3D bubbling fluidized bed. The new drag model has been found to possess better prediction accuracy and applicability over a much wider range of Re and εs than a number of existing models. Owing to the superior performance of the new drag model, it has a potential to gainfully replace the existing drag models in predicting the hydrodynamic behavior of fluidized beds.

Sign in / Sign up

Export Citation Format

Share Document