Two-Phase Flow Model Applied in the Oxidation Ditch

2013 ◽  
Vol 838-841 ◽  
pp. 1659-1662
Author(s):  
Lin Chen ◽  
Qian Feng
Keyword(s):  
Close Relation ◽  
Phase Model ◽  
Hydrodynamic Performance ◽  
Oxidation Ditch ◽  
Two Phase ◽  
Good Correspondence ◽  
Design And Optimization ◽  
Numerical Tools ◽  
Computational Fluid Dynamics Cfd

The unique hydraulic characteristics in oxidation ditch have a close relation with the quality of treated water, the design and optimization of the oxidation ditch. The experimentally validated numerical tools, based on computational fluid dynamics(CFD), were proposed. Sewage- sludge two-phase model and liquid-gas two-phase model of an oxidation ditch were built through CFD numerical method. Meanwhile, a velocity field measurement was enforced on the ditch by Acoustic Doppler Velocimeter(ADV). The simulated results and experimental data were in good correspondence, which verify the simulation methods are reasonable and the simulation results are acceptable. The combination of simulation and experimrntal measurement has profound influence on the hydraulic optimization of oxidation ditch. 3D simulation could be a good supplement for improving the hydrodynamic performance in oxidation ditch designs.

scholarly journals A Two-Phase Model of Air Shock Wave Induced by Rock-Fall in Closed Goaf

2017 ◽  
Author(s):  
Fengyu Ren ◽  
Yang Liu ◽  
Jianli Cao ◽  
Rongxing He ◽  
Yuan Xu ◽  
...  
Keyword(s):  
Shock Wave ◽  
Theoretical Analysis ◽  
Phase Model ◽  
Rock Fall ◽  
Uniform Motion ◽  
Two Phase ◽  
Protective Measures ◽  
Computational Fluid Dynamics Cfd ◽  
Series Of Experiments ◽  
Wave Induced

In this paper, a two-phase model of air shock wave induced by rock-fall was described. The model was made up of the uniform motion phase (velocity was close to 0 m·s-1) and the acceleration movement phase. The uniform motion phase was determined by experience, meanwhile the acceleration movement phase was derived by the theoretical analysis. A series of experiments were performed to verify the two-phase model and obtained the law of the uniform motion phase. The acceleration movement phase was taking a larger portion when height of rock-fall was higher with the observations. Experimental results of different falling heights showed good agreements with theoretical analysis values. Computational fluid dynamics (CFD) numerical simulation had been carried out to study the variation velocity with different falling height. As a result of this, the two-phase model could accurately and convenient estimating the velocity of air shock wave induced by rock-fall. The two-phase model could provide a reference and basis for estimating the air shock waves' velocity and designing the protective measures.

A Critical Comparison of Numerical and Experimental Results for the Examination of a Cascade Consisting of NACA 65-010 1% Profiles

2017 ◽  
Author(s):  
Andreas Baum ◽  
Constantin Berger ◽  
Christian Landfester ◽  
Martin Böhle
Keyword(s):  
Historical Data ◽  
Rotor Blades ◽  
Experimental Investigations ◽  
Good Correspondence ◽  
Singularity Method ◽  
Sst Turbulence Model ◽  
Computational Fluid Dynamics Cfd ◽  
2D And 3D ◽  
Aerodynamic Quality

Numerical and experimental investigations through different spans of the rotor are a common approach in turbo machinery design. As the aerodynamic quality of rotor blades is crucial for turbo machinery’s efficiency, mass-averaged loss coefficients ζ and turning angles Δβ are of particular interest. Using the example of commonly used NACA-65 profiles, a comparison between the results obtained by those methods should investigate whether Computational Fluid Dynamics (CFD) applying the Transition SST turbulence model delivers sufficiently accurate results regarding both 2D and 3D modeling approaches. The comparison is supplemented by the singularity method based on the potential theory as well as historical data provided by NACA. While CFD produced a noticeable offset for some angle configurations, the 2D results of Δβ were in good agreement for singularity method, historical data and experimental investigations on the center line of the cascade supporting the validity of the measurement. Although significant deviations were also found for ζ, it can be stated that CFD reproduced the qualitative course sufficiently for both variables considered. A similar picture emerges from the 3D comparison: Despite noticeable deviations in quantitative terms, a good correspondence was found for both variables regarding local and mass-averaged values.

On Some Relevant Effects in the Simulation of Flow Stability With Fluids at Supercritical Pressure

2016 ◽  
Vol 2 (3) ◽  
Author(s):  
Walter Ambrosini
Keyword(s):  
Single Channel ◽  
Natural Circulation ◽  
Flow Stability ◽  
Supercritical Pressure ◽  
Two Phase ◽  
Natural Circulation Loop ◽  
Numerical Tools ◽  
Computational Fluid Dynamics Cfd ◽  
System Configurations ◽  
Realistic Prediction

The paper collects and discusses findings emerging from the analysis of systems operating with fluids at supercritical pressure, with reference to flow stability. In particular, the influence of heating structures and numerical diffusion on the predicted dynamic behavior is highlighted, clarifying that results obtained paying little attention to the presence of these effects should be reconsidered for a better realistic prediction of stability characteristics. Examples of applications in which truncation error and the presence of heating structures play an important role are reported, in order to warn about a tendency to underestimate these effects on the basis of the knowledge of similar phenomena (e.g., in two-phase flow) or system configurations in which they might play a lesser role. The use of a computational fluid dynamics (CFD) code in the analysis of a simple single-tube stability problem shows that models more complex than the usual one-dimensional (1D) ones also show similar effects. The results obtained by 1D numerical tools developed for the analysis of natural circulation with supercritical pressure fluids, equipped with the capability to simulate linear and nonlinear stability with first- and second-order explicit schemes, are then reported. The discussion of the eigenvalues and the eigenvectors calculated for an existing natural circulation loop and a single channel highlight interesting aspects that can be helpful in understanding the results of stability analyses. The CFD code analysis adds additional aspects of interest for the discussion.

The Hydrodynamic Performance of a Twin-Hull FLNG Concept

2014 ◽  
Author(s):  
Xavier Schut ◽  
Wim de Boom
Keyword(s):  
Numerical Data ◽  
Hydrodynamic Performance ◽  
Green Water ◽  
Scale Model ◽  
Innovative Design ◽  
Numerical Predictions ◽  
Computational Fluid Dynamics Cfd ◽  
Wave Drift Forces ◽  
And Storage

This paper presents the results of a numerical and experimental study concerning the hydrodynamic performance of the SBM midscale Twin-Hull FLNG concept. SBM’s innovative design consists of two LNG carriers joined together, and converted into a single FLNG facility. This option provides both sufficient deck space and storage capacity while having the benefit of a conversion project, being reduced delivery schedule and lower costs. This results in an unusually wide vessel for which only very limited number of precedents exist. Important hydrodynamic performance indicators such as first order motions, green water and bottom slamming are investigated by means of sea keeping tests. In these tests the scale model of the FLNG is subjected to moderate and harsh environmental conditions from various headings. The results are used to verify the numerical predictions of the global motions, wave drift forces and internal loads and to assess green water and bottom slamming loads. Current coefficients were calculated by computational fluid dynamics (CFD) and validated with wind tunnel experiments. All load components (wind, wave, current) are then used to evaluate the ability of the vessel to weathervane. This paper presents the investigation of the quality of numeric predictions by comparing model test data against numerical data and hence it summarizes the hydrodynamic performance of the Twin-Hull.

scholarly journals A Two-phase Model of Air Shock Wave Induced by Rock-fall in Closed Goaf

2016 ◽  
Author(s):  
Fengyu Ren ◽  
Yang Liu ◽  
Jianli Cao ◽  
Rongxing He ◽  
Yuan Xu ◽  
...  
Keyword(s):  
Shock Wave ◽  
Theoretical Analysis ◽  
Phase Model ◽  
Rock Fall ◽  
Uniform Motion ◽  
Two Phase ◽  
Protective Measures ◽  
Computational Fluid Dynamics Cfd ◽  
Series Of Experiments ◽  
Wave Induced

In this paper, a two-phase model of air shock wave induced by rock-fall in closed goaf was proposed. The model was made up of the uniform motion phase (velocity was close to 0 m•s-1) and the acceleration movement phase. The uniform motion phase was determined by experience and the acceleration movement phase was derived by the theoretical analysis. After this, a series of experiments were performed to verify the two-phase model and obtained the law of the uniform motion phase. By observing, the acceleration movement phase was taking a larger portion and the uniform motion phase was smaller when height of rock-fall was higher. By comparison, experimental results of different falling heights showed good agreements with theoretical analysis, which verifies the effectiveness of the two-phase model. Finally, the model was tested with computational fluid dynamics (CFD) numerical simulation by three groups of different falling height. The two-phase model could provide a reference and basis for estimating the air shock waves' velocity and design the protective measures.

Two-phase model for human classical conditioning.

1968 ◽  
Vol 78 (3, Pt.1) ◽  
pp. 359-368 ◽  
Author(s):  
William F. Prokasy ◽  
Martha A. Harsanyi
Keyword(s):  
Classical Conditioning ◽  
Phase Model ◽  
Two Phase

Transport of organochlorine pesticides in soil columns enhanced by dissolved organic carbon

1997 ◽  
Vol 35 (7) ◽  
pp. 139-145 ◽  
Author(s):  
Jiann-Yuan Ding ◽  
Shian-Chee Wu
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Organochlorine Pesticides ◽  
Transport Model ◽  
Phase Model ◽  
Soil Columns ◽  
Two Phase ◽  
Three Phase ◽  
Phase Transport ◽  
Remediation Of Soil

The objective of this study is to quantify the effects of humic acid solution infiltration on the transport of organochlorine pesticides (OCPs) in soil columns using a three-phase transport model. From experimental results, it is found that the dissolved organic carbon enhances the transport of OCPs in the soil columns. In the OCPs-only column, the concentration profiles of OCPs can be simulated well using a two-phase transport model with numerical method or analytical solution. In the OCPs-DOC column, the migrations of aldrin, DDT and its daughter compounds are faster than those in the OCPs-only column. The simulation with the three-phase model is more accurate than that with the two-phase model. In addition, significant decrease of the fluid pore velocities of the OCPs-DOC column was found. When DOC leachate is applied for remediation of soil or groundwater pollution, the decrease of mean pore velocities will be a crucial affecting factor.

Investigation of two-dimensional nonstationary processes of outflow a gas-saturated liquid from axisymmetric vessels

2012 ◽  
Vol 9 (1) ◽  
pp. 47-52
Author(s):  
R.Kh. Bolotnova ◽  
V.A. Buzina
Keyword(s):  
Comparative Analysis ◽  
Numerical Model ◽  
Liquid Mixture ◽  
Phase Model ◽  
Test Problems ◽  
Two Dimensional ◽  
Nonstationary Processes ◽  
Saturated Liquid ◽  
Two Phase ◽  
One Dimensional

The two-dimensional and two-phase model of the gas-liquid mixture is constructed. The validity of numerical model realization is justified by using a comparative analysis of test problems solution with one-dimensional calculations. The regularities of gas-saturated liquid outflow from axisymmetric vessels for different geometries are established.

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