Determining the spill flow discharge of combined sewer overflows using rating curves based on computational fluid dynamics instead of the standard weir equation

2009 ◽  
Vol 60 (12) ◽  
pp. 3035-3043 ◽  
Author(s):  
S. Fach ◽  
R. Sitzenfrei ◽  
W. Rauch
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Cfd Simulation ◽  
Water Levels ◽  
Wide Spread ◽  
Flow Conditions ◽  
Flow Discharge ◽  
Combined Sewer ◽  
Rating Curves ◽  
Simulation Results

It is state of the art to evaluate and optimise sewer systems with urban drainage models. Since spill flow data is essential in the calibration process of conceptual models it is important to enhance the quality of such data. A wide spread approach is to calculate the spill flow volume by using standard weir equations together with measured water levels. However, these equations are only applicable to combined sewer overflow (CSO) structures, whose weir constructions correspond with the standard weir layout. The objective of this work is to outline an alternative approach to obtain spill flow discharge data based on measurements with a sonic depth finder. The idea is to determine the relation between water level and rate of spill flow by running a detailed 3D computational fluid dynamics (CFD) model. Two real world CSO structures have been chosen due to their complex structure, especially with respect to the weir construction. In a first step the simulation results were analysed to identify flow conditions for discrete steady states. It will be shown that the flow conditions in the CSO structure change after the spill flow pipe acts as a controlled outflow and therefore the spill flow discharge cannot be described with a standard weir equation. In a second step the CFD results will be used to derive rating curves which can be easily applied in everyday practice. Therefore the rating curves are developed on basis of the standard weir equation and the equation for orifice-type outlets. Because the intersection of both equations is not known, the coefficients of discharge are regressed from CFD simulation results. Furthermore, the regression of the CFD simulation results are compared with the one of the standard weir equation by using historic water levels and hydrographs generated with a hydrodynamic model. The uncertainties resulting of the wide spread use of the standard weir equation are demonstrated.

Optimal Hardware Placement in a Minitower Computer Enclosure System

2011 ◽  
Author(s):  
M. Alfaro Cano ◽  
A. Hernandez-Guerrero ◽  
C. Rubio Arana ◽  
Aristotel Popescu
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Cfd Simulation ◽  
Operating Temperature ◽  
Optimal Placement ◽  
Cfd Analysis ◽  
Computational Fluid Dynamics Cfd ◽  
Simulation Results ◽  
The Relationship ◽  
Key Questions

One of the requirements for existing personal computers, PCs, is that the hardware inside must maintain an operating temperature as low as possible. One way to achieve that is to place the hardware components at locations with enough airflow around it. However, the relationship between the airflow and temperature of the components is unknown before they are placed at specific locations inside a PC. In this work a Computational Fluid Dynamics (CFD) analysis is coupled to a Design of Experiment (DOE) methodology to answer typical minitower key questions: a) how do the possible positions of hardware components affect their temperature?, and b) is it possible to get an optimal placement for these hardware components using the data collected by the CFD simulation results? The DOE methodology is used to optimize the analysis for a very large number of possible configurations. The results help in identifying where the efforts need to be placed in order to optimize the positioning of the hardware components for similar configurations at the designing stage. Somehow the results show that general conclusions could be drawn, but that there are not specific rules that could be applied to every configuration.

scholarly journals Performance Prediction and Validation of a Small-Capacity Twisted Savonius Wind Turbine

Energies ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1721 ◽  
Author(s):  
Hyeonmu Jang ◽  
Insu Paek ◽  
Seungjoo Kim ◽  
Deockjin Jeong
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wind Turbine ◽  
Performance Test ◽  
Cfd Simulation ◽  
Power Production ◽  
Maximum Power ◽  
Power Coefficient ◽  
Speed Ratio ◽  
Simulation Results

In this study, an off-grid–type small wind turbine for street lighting was designed and analyzed. Its performance was predicted using a computational fluid dynamics model. The proposed wind turbine has two blades with a radius of 0.29 m and a height of 1.30 m. Ansys Fluent, a commercial computational fluid dynamics solver, was used to predict the performance, and the k-omega SST model was used as the turbulence model. The simulation result revealed a tip-speed ratio of 0.54 with a maximum power coefficient, or an aerodynamic rotor efficiency of 0.17. A wind turbine was installed at a measurement site to validate the simulation, and a performance test was used to measure the power production. To compare the simulation results obtained from the CFD simulation with the measured electrical power performance, the efficiencies of the generator and the controller were measured using a motor-generator testbed. Also, the control strategy of the controller was found from the field test and applied to the simulation results. Comparing the results of the numerical simulation with the experiment, the maximum power-production error at the same wind speed was found to be 4.32%.

The Performance of a Generic Non-Axisymmetric End Wall in a Single Stage, Rotating Turbine at On and Off-Design Conditions

2010 ◽  
Author(s):  
Glen Snedden ◽  
Dwain Dunn ◽  
Grant Ingram ◽  
David Gregory-Smith
Keyword(s):  
Fluid Dynamics ◽  
Power Generation ◽  
Computational Fluid Dynamics ◽  
Secondary Flows ◽  
Design Flow ◽  
Wide Spread ◽  
Flow Conditions ◽  
Detailed Understanding ◽  
End Wall ◽  
Probe Measurements

The application of non-axisymmetric end walls in turbine stages has gained wide spread acceptance as a means to improve the performance of turbines in both power generation and aero-derivative applications. Non-axisymmetric end walls are aimed at the control of secondary flows and to a large extent have been developed through the use of computational fluid dynamics and detailed measurements in linear and annular cascades and proven in full scale engine tests. Little or no literature is available describing their performance at conditions other than design. This study utilises 5-hole probe measurements in a low speed, model turbine in conjunction with computational fluid dynamics to gain a more detailed understanding of the influence of a generic end wall design on the structure of secondary flows at both on and off-design flow conditions. Results indicate a 0.4% improvement in rotor efficiency at design but this was reduced at off design and at higher loading the rotor efficiency was reduced by 0.5%. Stage efficiencies were improved for all conditions but with a declining trend as load was increased. Experimental and CFD results are examined to investigate these findings further.

scholarly journals How Does Your Fluid Flow?

2003 ◽  
Vol 125 (12) ◽  
pp. 35-37
Author(s):  
Jean Thilmany
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Fluid Flow ◽  
Cfd Simulation ◽  
Flow Simulations ◽  
Computational Fluid Dynamics Cfd ◽  
Advanced Analysis ◽  
Simulation Results

This article reviews the method of analyzing fluid flow in structures and designs, which is enjoying a burst of interest. Twenty years later, manufacturers across a myriad of industries are licensing the technology from a pool of vendors who now market computational fluid dynamics (CFD) packages of many stripes. Engineers use CFD to predict how fluids will flow and to predict the quantitative effects of the fluid on the solids with which they are in contact. Airflow is commonly studied with the software. Many mechanical engineers do not need access to all the bells and whistles an advanced CFD program can provide. Advanced analysis programs are usually the purview of a user trained on a particular CFD package. Engineers used CFD to determine how to best position the fans so that air flowed inside the refrigerator and the freezer in the most efficient way. After studying fluid flow simulations, they made prototypes of the most promising modeled designs to see if the prototypes matched CFD simulation results.

Modeling a New Rotational Reciprocating Plate Impeller Using Computational Fluid Dynamics

2012 ◽  
Vol 10 (1) ◽  
Author(s):  
Yun Lin ◽  
Jules Thibault ◽  
Zisheng Zhang
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Cfd Simulation ◽  
Liquid Velocity ◽  
Fermentation Broth ◽  
Velocity Shear ◽  
Multiphase Model ◽  
Rushton Turbine ◽  
Simulation Results

A new impeller, the rotational reciprocating plate impeller (RRPI), designed to handle highly viscous fermentation broth, was modeled using computational fluid dynamics (CFD) to gain more insight into its performance. A standard Rushton turbine was first simulated using CFD software Fluent(r) for validation purposes. Under experimental conditions, the prediction of the power number obtained from CFD simulation agrees qualitatively with the experimental data. Multiphase simulation was used to better represent the gas-liquid interactions using Eulerian multiphase model. The rotational reciprocating movement of the RRPI was approximated using small time steps, each of which has a different rotation speed. Water and carboxymethyl cellulose (CMC) solutions were used as model fluids to represent the different stages of a typical fermentation with a rheologically-evolving broth. By comparing the simulation results to experimental data, the efficiency of the toothed belt used to drive the Rushton turbine impeller was confirmed to be high as expected, while the efficiency of the three-arm linkage system used to achieve the rotational reciprocation of the RRPI was estimated to be around 80%. The uniformity of mixing with the 3-Rushton impeller and the RRPI was compared to each other by investigating the distribution of liquid velocity, shear rate, and broth viscosity. The simulation results proved that the RRPI eliminated the dead zones that usually form when the Rushton turbines are used in viscous medium.

scholarly journals Computational Fluid Dynamics (CFD) Simulation on Mixing in T-Shaped Micromixer

2020 ◽  
Vol 932 ◽  
pp. 012006
Author(s):  
S N A Ahmad Termizi ◽  
C Y Khor ◽  
M A M Nawi ◽  
Nurlela Ahmad ◽  
Muhammad Ikman Ishak ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Cfd Simulation ◽  
Computational Fluid Dynamics Cfd

scholarly journals Effect of Doppler flow meter position on discharge measurement in surcharged manholes

2017 ◽  
Vol 77 (3) ◽  
pp. 647-654 ◽  
Author(s):  
Haoming Yang ◽  
David Z. Zhu ◽  
Yanchen Liu
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Field ◽  
Flow Regimes ◽  
Flow Meter ◽  
Flow Meters ◽  
Flow Discharge ◽  
Doppler Flow ◽  
Sewer Systems ◽  
Computational Fluid Dynamics Cfd

Abstract Determining the proper installation location of flow meters is important for accurate measurement of discharge in sewer systems. In this study, flow field and flow regimes in two types of manholes under surcharged flow were investigated using a commercial computational fluid dynamics (CFD) code. The error in measuring the flow discharge using a Doppler flow meter (based on the velocity in a Doppler beam) was then estimated. The values of the corrective coefficient were obtained for the Doppler flow meter at different locations under various conditions. Suggestions for selecting installation positions are provided.

A Study on the Performance of Stratified Air Conditioning Design in Assembly Halls – A Case Study at the Dazhi Cultural Center in Taiwan

2013 ◽  
Vol 368-370 ◽  
pp. 599-602 ◽  
Author(s):  
Ian Hung ◽  
Hsien Te Lin ◽  
Yu Chung Wang
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Indoor Air ◽  
Air Conditioning ◽  
Cfd Simulation ◽  
Indoor Temperature ◽  
Cultural Center ◽  
Computational Fluid Dynamics Cfd

This study focuses on the performance of air conditioning design at the Dazhi Cultural Center and uses a computational fluid dynamics (CFD) simulation to discuss the differences in wind velocity and ambient indoor temperature between all-zone air conditioning design and stratified air conditioning design. The results have strong implications for air conditioning design and can improve the indoor air quality of assembly halls.

The Effect of Different Turbulence Models on the Emitter Discharge by Using Computational Fluid Dynamics

2013 ◽  
Vol 662 ◽  
pp. 586-590
Author(s):  
Gang Lu ◽  
Qing Song Yan ◽  
Bai Ping Lu ◽  
Shuai Xu ◽  
Kang Li
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Field ◽  
Turbulence Models ◽  
Experimental Results ◽  
Turbulent Model ◽  
Simulation Results ◽  
Rsm Model ◽  
Dynamics Method ◽  
Emitter Discharge

Four types of Super Typhoon drip emitter with trapezoidal channel were selected out for the investigation of the flow field of the channel, and the CFD (Computational Fluid Dynamics) method was applied to simulate the micro-field inside the channel. The simulation results showed that the emitter discharge of different turbulent model is 4%-14% bigger than that of the experimental results, the average discharge deviation of κ-ω and RSM model is 5, 4.5 respectively, but the solving efficiency of the κ-ω model is obviously higher than that of the RSM model.

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