Flow field prediction in full-scale Carrousel oxidation ditch by using computational fluid dynamics

2010 ◽  
Vol 62 (2) ◽  
pp. 256-265 ◽  
Author(s):  
Yin Yang ◽  
Yingying Wu ◽  
Xiao Yang ◽  
Kai Zhang ◽  
Jiakuan Yang
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Field ◽  
Full Scale ◽  
Hydrodynamic Performance ◽  
Cfd Modeling ◽  
Oxidation Ditch ◽  
Wall Model ◽  
Moving Wall ◽  
Carrousel Oxidation Ditch

In order to optimize the flow field in a full-scale Carrousel oxidation ditch with many sets of disc aerators operating simultaneously, an experimentally validated numerical tool, based on computational fluid dynamics (CFD), was proposed. A full-scale, closed-loop bioreactor (Carrousel oxidation ditch) in Ping Dingshan Sewage Treatment Plant in Ping Dingshan City, a medium-sized city in Henan Province of China, was evaluated using CFD. Moving wall model was created to simulate many sets of disc aerators which created fluid motion in the ditch. The simulated results were acceptable compared with the experimental data and the following results were obtained: (1) a new method called moving wall model could simulate the flow field in Carrousel oxidation ditch with many sets of disc aerators operating simultaneously. The whole number of cells of grids decreased significantly, thus the calculation amount decreased, and (2) CFD modeling generally characterized the flow pattern in the full-scale tank. 3D simulation could be a good supplement for improving the hydrodynamic performance in oxidation ditch designs.

Optimization design of submerged propeller in oxidation ditch by computational fluid dynamics and comparison with experiments

2016 ◽  
Vol 74 (3) ◽  
pp. 681-690 ◽  
Author(s):  
Yuquan Zhang ◽  
Yuan Zheng ◽  
E. Fernandez-Rodriguez ◽  
Chunxia Yang ◽  
Yantao Zhu ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Energy Consumption ◽  
Flow Field ◽  
Flow Pattern ◽  
Operating Conditions ◽  
Oxidation Ditch ◽  
Actual Measurement ◽  
Operating Condition ◽  
Rotating Speed

The operating condition of a submerged propeller has a significant impact on flow field and energy consumption of the oxidation ditch. An experimentally validated numerical model, based on the computational fluid dynamics (CFD) tool, is presented to optimize the operating condition by considering two important factors: flow field and energy consumption. Performance demonstration and comparison of different operating conditions were carried out in a Carrousel oxidation ditch at the Yingtang wastewater treatment plants in Anhui Province, China. By adjusting the position and rotating speed together with the number of submerged propellers, problems of sludge deposit and the low velocity in the bend could be solved in a most cost-effective way. The simulated results were acceptable compared with the experimental data and the following results were obtained. The CFD model characterized flow pattern and energy consumption in the full-scale oxidation ditch. The predicted flow field values were within −1.28 ± 7.14% difference from the measured values. By determining three sets of propellers under the rotating speed of 6.50 rad/s with one located 5 m from the first curved wall, after numerical simulation and actual measurement, not only the least power density but also the requirement of the flow pattern could be realized.

Modelling of wastewater treatment plants – how far shall we go with sophisticated modelling tools?

2006 ◽  
Vol 53 (3) ◽  
pp. 79-89 ◽  
Author(s):  
G.C. Glover ◽  
C. Printemps ◽  
K. Essemiani ◽  
J. Meinhold
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wastewater Treatment ◽  
Activated Sludge ◽  
Wastewater Treatment Plants ◽  
Pilot Scale ◽  
Full Scale ◽  
Structure Identification ◽  
Oxidation Ditch ◽  
Computational Fluid Dynamics Analysis

Several levels of complexity are available for modelling of wastewater treatment plants. Modelling local effects rely on computational fluid dynamics (CFD) approaches whereas activated sludge models (ASM) represent the global methodology. By applying both modelling approaches to pilot plant and full scale systems, this paper evaluates the value of each method and especially their potential combination. Model structure identification for ASM is discussed based on a full-scale closed loop oxidation ditch modelling. It is illustrated how and for what circumstances information obtained via CFD (computational fluid dynamics) analysis, residence time distribution (RTD) and other experimental means can be used. Furthermore, CFD analysis of the multiphase flow mechanisms is employed to obtain a correct description of the oxygenation capacity of the system studied, including an easy implementation of this information in the classical ASM modelling (e.g. oxygen transfer). The combination of CFD and activated sludge modelling of wastewater treatment processes is applied to three reactor configurations, a perfectly mixed reactor, a pilot scale activated sludge basin (ASB) and a real scale ASB. The application of the biological models to the CFD model is validated against experimentation for the pilot scale ASB and against a classical global ASM model response. A first step in the evaluation of the potential of the combined CFD-ASM model is performed using a full scale oxidation ditch system as testing scenario.

Effect of Intake Port Bend Angle on Flow Field Inside the Cylinder of a DI Diesel Engine

2007 ◽  
Author(s):  
B. Jayashankara ◽  
V. Ganesan
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Diesel Engine ◽  
Flow Field ◽  
Design Tool ◽  
Turbulent Intensity ◽  
Cfd Modeling ◽  
Bend Angle ◽  
Intake Port ◽  
Di Diesel Engine

This paper presents the computational fluid dynamics (CFD) modeling to study the effect of intake port bend angle on the flow field inside the cylinder of a direct injection (DI) diesel engine under motoring conditions. The flow characteristics of the engine are investigated under transient conditions. A single cylinder DI diesel engine with two direct intake ports whose outlet is tangential to the wall of the cylinder and two exhaust ports has been taken up for the study. Effect of intake port bend angle (20°, 30°, and 40°) on the flow field inside the cylinder has been investigated at an engine speed of 1000 rpm. The pre-processor GAMBIT is used for model preparation and commercial computational fluid dynamics code STAR-CD has been used for solution of governing equations and post processing the results. CFD results during both intake and compression strokes have been compared with experimental results of Payri et-al [7, 8]. The predicted swirl ratio, radial velocity and turbulent intensity variations at different crank angles and at different locations are discussed. Distribution of velocity and turbulence intensity inside the cylinder is also discussed. It is observed that the intake ports with 20° bend angle produce maximum swirl and also results in a slight decrease in volumetric efficiency compared to intake ports with 30° and 40° bend angles and there is no appreciable variation in turbulent intensity. Hence, for the better performance of a DI diesel engine, it is concluded that the intake ports with 20° bend angle is most appropriate and CFD is an effective design tool to develop more efficient DI diesel engines.

Hydrodynamic Performance Study on Flow Field in Rod Bundles With Spacer Grids

2014 ◽  
Author(s):  
Li-feng Song ◽  
Rui-feng Tian ◽  
Lan-xin Sun ◽  
Cong Shi ◽  
Peng Li
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Field ◽  
Nuclear Reactor ◽  
Cross Flow ◽  
Hydrodynamic Performance ◽  
Performance Study ◽  
Rod Bundles ◽  
Spacer Grids ◽  
Computational Fluid Dynamics Cfd

With the dramatic progress in the computational fluid dynamics (CFD) methodology, this technology can be used in researching the knowledge of thermal–hydraulic characteristics in the rod bundles, particularly with the spacer grids. These characteristics, including fluid flow, turbulence, and heat transfer and so on, all of this information can be applied in design and the improvement of rod bundles. This paper calculated the single-phase flow field in rod bundles with different spacer grids respectively by numerical method, which was based on the experiment performed by Korea Atomic Energy Research Institute (KAERI). Two types of grid designs are used, including the Split-type and Swirl-type, respectively. By analyzing the calculated results, discussing the feasibility of computational fluid dynamics (CFD) methodology in thermal-hydraulic analysis of nuclear reactor, and obtaining the hydrodynamic performance of the two different types of spacer grids. The result showed that both of the two spacer grids led to intense cross-flow in the channel, and the cross-flow intensity decayed with the increasing of downstream distance after the spacer grids. Axial velocities were distributed uniformly in the channel.

scholarly journals Computational Fluid Dynamics Analysis of Alternative Ventilation Schemes in Cage-Free Poultry Housing

Animals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 2352
Author(s):  
Long Chen ◽  
Eileen E. Fabian-Wheeler ◽  
John M. Cimbala ◽  
Dan Hofstetter ◽  
Paul Patterson
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Ventilation System ◽  
Airflow Obstruction ◽  
Three Dimensional ◽  
Ventilation Rate ◽  
Full Scale ◽  
Cold Weather ◽  
Cfd Modeling ◽  
Computational Fluid Dynamics Analysis

This work investigated alternative ventilation schemes to help define a proper ventilation system design in cage-free hen houses with the goal of assuring bird welfare through comfortable conditions. Computational fluid dynamics (CFD) modeling was employed to simulate indoor and outdoor airflows to quantify the effectiveness of ventilation systems in maintaining suitable and uniform living conditions at the hen level. Four three-dimensional CFD models were developed based on a full-scale floor-raised layer house, corresponding to ventilation schemes of the standard top-wall inlet, sidewall exhaust, and three alternatives: mid-wall inlet, ceiling exhaust; mid-wall inlet, ridge exhaust; and mid-wall inlet, attic exhaust with potential for pre-treatment of exhaust air. In a sophisticated and powerful achievement of the analysis, 2365 birds were individually modeled with simplified bird-shapes to represent a realistic number, body heat, and airflow obstruction of hens housed. The simulated ventilation rate for the layer house models was 1.9–2.0 m3/s (4100 ft3/min) in the desired range for cold weather (0 °C). Simulation results and subsequent analyses demonstrated that these alternative models had the capacity to create satisfactory comfortable temperature and air velocity at the hen level. A full-scale CFD model with individual hen models presented robustness in evaluating bird welfare conditions.

scholarly journals Computational Fluid Dynamics Modeling of Rotating Annular VUV/UV Photoreactor for Water Treatment

Processes ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 79
Author(s):  
Minghan Luo ◽  
Wenjie Xu ◽  
Xiaorong Kang ◽  
Keqiang Ding ◽  
Taeseop Jeong
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Water Treatment ◽  
Cfd Modeling ◽  
Flow Mode ◽  
Oh Radicals ◽  
Dynamics Modeling ◽  
Rotational Movement ◽  
Contaminant Degradation ◽  
Wide Range

The ultraviolet photochemical degradation process is widely recognized as a low-cost, environmentally friendly, and sustainable technology for water treatment. This study integrated computational fluid dynamics (CFD) and a photoreactive kinetic model to investigate the effects of flow characteristics on the contaminant degradation performance of a rotating annular photoreactor with a vacuum-UV (VUV)/UV process performed in continuous flow mode. The results demonstrated that the introduced fluid remained in intensive rotational movement inside the reactor for a wide range of inflow rates, and the rotational movement was enhanced with increasing influent speed within the studied velocity range. The CFD modeling results were consistent with the experimental abatement of methylene blue (MB), although the model slightly overestimated MB degradation because it did not fully account for the consumption of OH radicals from byproducts generated in the MB decomposition processes. The OH radical generation and contaminant degradation efficiency of the VUV/UV process showed strong correlation with the mixing level in a photoreactor, which confirmed the promising potential of the developed rotating annular VUV reactor in water treatment.

Sign in / Sign up

Export Citation Format

Share Document