scholarly journals Computational fluid dynamics analysis of a high-throughput viscous heater to process feces and a fecal simulant using temperature and shear rate-dependent viscosity model

2017 ◽  
Vol 8 (1) ◽  
pp. 27-32
Author(s):  
C. L. German ◽  
J. T. Podichetty ◽  
A. Muzhingi ◽  
B. Makununika ◽  
J. Smay ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Shear Rate ◽  
Operating Conditions ◽  
Rate Dependent ◽  
Annular Gap ◽  
Computational Fluid Dynamics Analysis ◽  
Fecal Sludge ◽  
Dependent Viscosity

Abstract Open defecation and poor fecal management facilitates the spread of disease. Viscous heating can pasteurize fecal sludge by creating a high shear field in the annular gap between a stationary, cylindrical outer shell and a rotating inner core. As sludge flows axially through the annular gap, thorough mixing and frictional heating eliminate cool spots where microbes may survive. A viscous heater (VH) compares favorably to a conventional heat exchanger, where cool slugs may occur. Computational fluid dynamics (CFD) was used to determine the effects of geometry and fluid rheology on VH performance over a range of conditions. A shear-rate and temperature-dependent rheological model was developed from experimental data, using a sludge simulant. CFD of an existing VH used the model to improve the original naïve design by including temperature and shear rate-dependent viscosity. CFD results were compared to experimental data at 132 and 200 L/hr to predict design and operating conditions for 1,000 L/hr. Subsequent experimentation with fecal sludge indicated that the CFD approach was valid for design and operation.

Computational Fluid Dynamics Analysis of a Hydrokinetic Turbine Based on Oscillating Hydrofoils

2012 ◽  
Vol 134 (2) ◽  
Author(s):  
Thomas Kinsey ◽  
Guy Dumas
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Numerical Simulations ◽  
Spatial Configuration ◽  
Operating Conditions ◽  
Power Extraction ◽  
Numerical Predictions ◽  
Hydrokinetic Turbine ◽  
Computational Fluid Dynamics Analysis

The performance of a new concept of hydrokinetic turbine using oscillating hydrofoils to extract energy from water currents (tidal or gravitational) is investigated using URANS numerical simulations. The numerical predictions are compared with experimental data from a 2 kW prototype, composed of two rectangular oscillating hydrofoils of aspect ratio 7 in a tandem spatial configuration. 3D computational fluid dynamics (CFD) predictions are found to compare favorably with experimental data especially for the case of a single-hydrofoil turbine. The validity of approximating the actual arc-circle trajectory of each hydrofoil by an idealized vertical plunging motion is also addressed by numerical simulations. Furthermore, a sensitivity study of the turbine’s performance in relation to fluctuating operating conditions is performed by feeding the simulations with the actual time-varying experimentally recorded conditions. It is found that cycle-averaged values, as the power-extraction efficiency, are little sensitive to perturbations in the foil kinematics and upstream velocity.

scholarly journals Computational fluid dynamics analysis of the influence of injection nozzle lateral outflow on the performance of Ranque-Hilsch vortex tube

2014 ◽  
Vol 18 (4) ◽  
pp. 1191-1201 ◽  
Author(s):  
Nader Pourmahmoud ◽  
Alireza Izadi ◽  
Amir Hassanzadeh ◽  
Ashkan Jahangiramini
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Field ◽  
Vortex Tube ◽  
Operating Conditions ◽  
Energy Separation ◽  
Physical Parameters ◽  
Dynamics Analysis ◽  
Computational Domain ◽  
Computational Fluid Dynamics Analysis

In this article computational fluid dynamics analysis of a three-dimensional compressible and turbulent flow has been carried out through a vortex tube. The standard k-? turbulence model is utilized in order to simulate an axisymmetric computational domain. The numerical simulation has focused on the energy separation and flow field patterns of a somewhat nonconventional vortex tube, which is on the basis of creating an external hole at the end of each nozzle. According to the selected nozzles geometry, some of unfavorable phenomena such as shock wave, high pressure regions and appearing of unsymmetrical rotating flow patterns in the vortex chamber would be recovered significantly. In this way the physical parameters of flow field are derived under different both inlet mass flow rates and outlet pressures of nozzles hole (OPH). The results show that increasing OPH value enhanced the cooling capacity of machine in the most of operating conditions.

Computational Fluid Dynamics Analysis of a Steam Power Plant Low-Pressure Turbine Downward Exhaust Hood

1996 ◽  
Vol 118 (1) ◽  
pp. 214-224 ◽  
Author(s):  
R. H. Tindell ◽  
T. M. Alston ◽  
C. A. Sarro ◽  
G. C. Stegmann ◽  
L. Gray ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Integrated Approach ◽  
Low Pressure ◽  
Operating Conditions ◽  
Exhaust Hood ◽  
Steam Power ◽  
Low Pressure Turbine ◽  
Computational Fluid Dynamics Analysis ◽  
Turbine Exhaust

Computational fluid dynamics (CFD) methods are applied to the analysis of a low-pressure turbine exhaust hood at a typical steam power generating station. A Navier-Stokes solver, capable of modeling all the viscous terms, in a Reynolds-averaged formulation, was used. The work had two major goals. The first was to develop a comprehensive understanding of the complex three-dimensional flow fields that exist in the exhaust hood at representative operating conditions. The second was to evaluate the relative benefits of a flow guide modification to optimize performance at a selected operating condition. Also, the influence of simulated turbine discharge characteristics, relative to uniform hood entrance conditions, was evaluated. The calculations show several interesting and possibly unique results. They support use of an integrated approach to the design of turbine exhaust stage blading and hood geometry for optimum efficiency.

Annular Gap Bubble Column: Experimental Investigation and Computational Fluid Dynamics Modeling

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Giorgio Besagni ◽  
Gaël Raymond Guédon ◽  
Fabio Inzoli
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Regime ◽  
Bubble Column ◽  
Gas Holdup ◽  
Operating Conditions ◽  
Optical Probes ◽  
Annular Gap ◽  
Fiber Optical ◽  
Flow Visualizations

This paper investigates the countercurrent gas–liquid flow in an annular gap bubble column with a 0.24 m inner diameter by using experimental and numerical investigations. The two-phase flow is studied experimentally using flow visualizations, gas holdup measurements, and double fiber optical probes in the following range of operating conditions: superficial air velocities up to 0.23 m/s and superficial water velocities up to −0.11 m/s, corresponding to gas holdups up to 29%. The flow visualizations were used to observe the flow patterns and to obtain the bubble size distribution (BSD). The gas holdup measurements were used for investigating the flow regime transitions, and the double fiber optical probes were used to study the local flow phenomena. A computational fluid dynamics (CFD) Eulerian two-fluid modeling of the column operating in the bubbly flow regime is proposed using the commercial software ansys fluent. The three-dimensional (3D) transient simulations have been performed considering a set of nondrag forces and polydispersity. It is shown that the errors in the global holdup and in the local properties are below 7% and 16%, respectively, in the range considered.

Analysis and Modeling of Liquid Holdup in Low Liquid Loading Two-Phase Flow Using Computational Fluid Dynamics and Experimental Data

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Miguel Ballesteros ◽  
Nicolás Ratkovich ◽  
Eduardo Pereyra
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Oil And Gas ◽  
Operating Conditions ◽  
Liquid Holdup ◽  
Liquid Loading ◽  
Two Phase ◽  
Acceptable Error ◽  
Pharmaceutical Industries

Abstract Low liquid loading flow occurs very commonly in the transport of any kind of wet gas, such as in the oil and gas, the food, and the pharmaceutical industries. However, most studies that analyze this type of flow do not cover actual industry fluids and operating conditions. This study focused then on modeling this type of flow in medium-sized (6-in [DN 150] and 10-in [DN 250]) pipes, using computational fluid dynamics (CFD) simulations. When comparing with experimental data from the University of Tulsa, the differences observed between experimental and CFD data for the liquid holdup and the pressure drop seemed to fall within acceptable error, around 20%. Additionally, different pipe sections from a Colombian gas pipeline were simulated with a natural gas-condensate mixture to analyze the effect of pipe inclination and operation variables on liquid holdup, in real industry conditions. It was noticed that downward pipe inclinations favored smooth stratified flow and decreased liquid holdup in an almost linear fashion, while upward inclinations generated unsteady wavy flows, or even a possible annular flow, and increased liquid holdup and liquid entrainment into the gas phase.

scholarly journals CFD Analysis of Shrouded Diffuser Wind Turbine

2019 ◽  
Vol 8 (6S3) ◽  
pp. 2100-2104
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wind Turbine ◽  
Wind Velocity ◽  
Experimental Testing ◽  
Flow Characteristics ◽  
Operating Conditions ◽  
Computational Fluid Dynamics Analysis ◽  
Cfd Analyses ◽  
Physical Dimensions

The power in the wind is well known to be proportional to the cubic power of the wind velocity approaching a wind turbine. This means that even small amount of its acceleration gives large increase in the power output. Brimmed diffuser shrouds for small wind turbines are being used to accelerate the wind velocity in small wind regimes. The objective of the Paper is to analyze the flow characteristics of brimmed diffuser shroud and to optimize the physical dimensions. CFD analyses are carried out by varying its physical dimensions with the aim of achieving augmented velocity. The effect of flow parameters with the presence of diffuser is analyzed by comparing it with bare wind turbine. The physical dimensions of brimmed diffusers are the parameters considered in this study. The study has been carried with proposed splitted diffuser design. The power yield of the turbine for shifting speeds is gotten and analyzed.The CFD tool CFX would be used to anlayse the flow field around the diffuser. Performance of wind turbine under various operating conditions is generally obtained through an experimental testing and could be cost prohibitive. In this case the computational fluid dynamics analysis provides better results. The capability of using computational fluid dynamics is a test to determine its viability for determining its performance parameters

Experimental and Numerical Investigations of Aerodynamic Behavior of a Three-Stage HP-Turbine at Different Operating Conditions

2010 ◽  
Author(s):  
S. A. Abdelfattah ◽  
M. T. Schobeiri
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Numerical Simulation ◽  
Computational Fluid Dynamics ◽  
High Pressure ◽  
Operating Conditions ◽  
Numerical Investigations ◽  
Turbine Performance ◽  
Speed Range ◽  
Three Stages

This paper describes experimental and numerical investigations of a three-stage high pressure research turbine which incorporates fully 3-D bowed blades at various operating conditions. Experimental data were obtained using interstage aerodynamic measurements at three measurement stations, namely, downstream of the first rotor row, the second stator row and the second rotor row. Measurements were conducted through the use of five-hole probes traversed in both circumferential and radial directions to create a measurement window. Aerodynamics measurements were carried out within a rotational speed range of 1800 to 2800 RPM. Numerical simulation of the aforementioned turbine was performed through the use of a commercial computational fluid dynamics code. A detailed mesh of the three-stages was created and used to simulate the corresponding operating conditions and a comparison was made between experimentally and numerically determined aerodynamics and turbine performance.

scholarly journals Modeling of H2 Permeation through Electroless Pore-Plated Composite Pd Membranes Using Computational Fluid Dynamics

Membranes ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 123
Author(s):  
Alberto Fernández ◽  
Cintia Casado ◽  
David Alique ◽  
José Antonio Calles ◽  
Javier Marugán
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Hydrogen Permeation ◽  
Membrane Surface ◽  
Molar Fraction ◽  
Operating Conditions ◽  
Cfd Modeling ◽  
Wide Range ◽  
The Impact

This work focused on the computational fluid dynamics (CFD) modeling of H2/N2 separation in a membrane permeator module containing a supported dense Pd-based membrane that was prepared using electroless pore-plating (ELP-PP). An easy-to-implement model was developed based on a source–sink pair formulation of the species transport and continuity equations. The model also included the Darcy–Forcheimer formulation for modeling the porous stainless steel (PSS) membrane support and Sieverts’ law for computing the H2 permeation flow through the dense palladium film. Two different reactor configurations were studied, which involved varying the hydrogen flow permeation direction (in–out or out–in). A wide range of experimental data was simulated by considering the impact of the operating conditions on the H2 separation, such as the feed pressure and the H2 concentration in the inlet stream. Simulations of the membrane permeator device showed an excellent agreement between the predicted and experimental data (measured as permeate and retentate flows and H2 separation). Molar fraction profiles inside the permeator device for both configurations showed that concentration polarization near the membrane surface was not a limit for the hydrogen permeation but could be useful information for membrane reactor design, as it showed the optimal length of the reactor.

Development and Validation of a Three-Dimensional Multiphase Flow Computational Fluid Dynamics Analysis for Journal Bearings in Steam and Heavy Duty Gas Turbines

2012 ◽  
Vol 134 (10) ◽  
Author(s):  
Stephan Uhkoetter ◽  
Stefan aus der Wiesche ◽  
Michael Kursch ◽  
Christian Beck
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Multiphase Flow ◽  
Gas Turbines ◽  
Three Dimensional ◽  
Air Entrainment ◽  
Journal Bearings ◽  
Heavy Duty ◽  
Computational Fluid Dynamics Analysis

The traditional method for hydrodynamic journal bearing analysis usually applies the lubrication theory based on the Reynolds equation and suitable empirical modifications to cover turbulence, heat transfer, and cavitation. In cases of complex bearing geometries for steam and heavy-duty gas turbines, this approach has its obvious restrictions in regard to detail flow recirculation, mixing, mass balance, and filling level phenomena. These limitations could be circumvented by applying a computational fluid dynamics (CFD) approach, resting closer to the fundamental physical laws. The present contribution reports about the state of the art of such a fully three-dimensional multiphase-flow CFD approach, including cavitation and air entrainment for high-speed turbomachinery journal bearings. It has been developed and validated using experimental data. Due to the high ambient shear rates in bearings, the multiphase-flow model for journal bearings requires substantial modifications in comparison to common two-phase flow simulations. Based on experimental data, it is found, that particular cavitation phenomena are essential for the understanding of steam and heavy-duty-type gas turbine journal bearings.

Computational Fluid Dynamics Analysis of 3D Hot Metal Flow Characteristics in a Blast Furnace Hearth

2010 ◽  
Vol 2 (1) ◽  
Author(s):  
Chenn Q. Zhou ◽  
D. (Frank) Huang ◽  
Yongfu Zhao ◽  
Pinakin Chaubal
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Blast Furnace ◽  
Metal Flow ◽  
Measurement Data ◽  
Operating Conditions ◽  
Hot Metal ◽  
Furnace Hearth ◽  
Blast Furnace Hearth ◽  
Computational Fluid Dynamics Analysis

The campaign life of an iron blast furnace depends on hearth wear. Distributions of liquid iron flow and refractory temperatures have a significant influence on hearth wear. A 3D comprehensive computational fluid dynamics model has been developed specifically for simulating the blast furnace hearth. It includes both the hot metal flow and the conjugate heat transfer through the refractories. The model has been extensively validated using measurement data from Mittal Steel old, new IH7 blast furnace and U.S. Steel 13 blast furnace. Good agreements between measured and calculated refractory temperature profiles have been achieved. It has been used to analyze the velocity and temperature distributions and wear patterns of different furnaces and operating conditions. The results can be used to predict the inner profile of hearth and to provide guidance for protecting the hearth.

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