scholarly journals Investigation on Dynamics of Sediment and Water Flow in a Sand Trap

2020 ◽  
Vol 14 ◽  
Keyword(s):  
Flow Behavior ◽  
Vertical Component ◽  
Low Flow ◽  
Hydropower Project ◽  
Cfd Model ◽  
Critical Flow Velocity ◽  
Settling Basin ◽  
Sediment Removal ◽  
Sand Trap ◽  
Computational Fluid Dynamics Cfd

Sediment and flow dynamics in a sand trap of Golen Gol hydropower project in Pakistan was evaluated using a Computational Fluid Dynamics (CFD) model. Sediment Simulation in Intakes with Multi Block Options (SSIIM) CFD model was used to simulate the sediment and flow behavior in the sand trap. Numerical simulation results demonstrated that the horizontal and vertical component of velocities at any region of settling basin was less than the designed critical flow velocity of the sand trap. The design with respect to dimensions and proportioning of the sand trap were found appropriate for inducing low flow velocities throughout the settling basin of the sand trap supporting the deposition of sediments. The results obtained from simulation further presented the 100% removal of the desired sediments (particle size class ≥ 0.205 mm diameter) could be achieved in the sand trap. All this verify the design of sand trap is in accordance with the desired designed sediment removal efficiency of the sand trap.

scholarly journals Design and CFD Simulation of Knockout Drum

2020 ◽  
Vol 10 (4) ◽  
pp. 181-198
Author(s):  
Yazen Munaf Ali ◽  
Dr Saad Nahi Saleh ◽  
Wameed Abdulhassan Ayash ◽  
Saramd Zaki Ghani ◽  
Sudad Adil Salih
Keyword(s):  
Cfd Simulation ◽  
Flow Behavior ◽  
Local Area ◽  
Cfd Model ◽  
Two Phase ◽  
Fluid Mixture ◽  
Ansys Fluent ◽  
Black Smoke ◽  
The North ◽  
Computational Fluid Dynamics Cfd

Recently, the emission of black smoke over local area of Basra Oil Company from flare system represents a big problem facing the company and causing huge pollution in the surrounding environment. The main reason of emission black smoke is carryover of droplets of the rest hydrocarbons such as condensate and droplets of crude oil by gases which are came from degassing stations facility in the north Rumelia field, southern Iraq.  In this study, a design methodology was developed for designing the knockout drum, and different design criteria were used in sizing and selecting the drum based on the specification of the inlet fluid mixture. Three designs of knockout drums with respect to the gas conditions were performed. The horizontal knockout drum with a diameter of 2.5 m and length of 5.5 m was simulated using a Computational Fluid Dynamics (CFD) model (ANSYS FLUENT 15.0). The CFD model predicted very well the two-phase flow behavior and proved the need for a vortex breaker at the liquid outlet. The CFD simulation revealed quantitatively that the design configuration of the knockout drum performed the separation of condensate droplets from natural gas with excellent efficiency.

Effects of Over Fire Air on the Combustion and NOx Emission Characteristics of a 600 MW Opposed Swirling Fired Boiler

2012 ◽  
Vol 512-515 ◽  
pp. 2135-2142 ◽  
Author(s):  
Yu Peng Wu ◽  
Zhi Yong Wen ◽  
Yue Liang Shen ◽  
Qing Yan Fang ◽  
Cheng Zhang ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Empirical Method ◽  
Nox Emission ◽  
Emission Characteristics ◽  
Cfd Model ◽  
Nitrogen Release ◽  
Computational Fluid Dynamics Cfd ◽  
Low Nox Emission

A computational fluid dynamics (CFD) model of a 600 MW opposed swirling coal-fired utility boiler has been established. The chemical percolation devolatilization (CPD) model, instead of an empirical method, has been adapted to predict the nitrogen release during the devolatilization. The current CFD model has been validated by comparing the simulated results with the experimental data obtained from the boiler for case study. The validated CFD model is then applied to study the effects of ratio of over fire air (OFA) on the combustion and nitrogen oxides (NOx) emission characteristics. It is found that, with increasing the ratio of OFA, the carbon content in fly ash increases linearly, and the NOx emission reduces largely. The OFA ratio of 30% is optimal for both high burnout of pulverized coal and low NOx emission. The present study provides helpful information for understanding and optimizing the combustion of the studied boiler

scholarly journals The Problem of Accounting for Heat Exchange between the Flow and the Flow Part Surfaces When Modeling a Viscous Flow in Low-Flow Stages of a Centrifugal Compressor

2020 ◽  
Vol 10 (24) ◽  
pp. 9138
Author(s):  
Sergey Kartashov ◽  
Yuri Kozhukhov ◽  
Vycheslav Ivanov ◽  
Aleksei Danilishin ◽  
Aleksey Yablokov ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Centrifugal Compressor ◽  
Calculation Model ◽  
Flow Coefficient ◽  
Low Flow ◽  
Relative Width ◽  
Adiabatic Wall ◽  
Flow Part ◽  
Computational Fluid Dynamics Cfd

In this paper, we review the problem of accounting for heat exchange between the flow and the flow part surfaces when creating a calculation model for modeling the workflow process of low-flow stages of a centrifugal compressor using computational fluid dynamics (CFD). The objective selected for this study was a low-flow intermediate type stage with the conditional flow coefficient Փ = 0.008 and the relative width at the impeller exit b2/D2 = 0.0133. We show that, in the case of modeling with widespread adiabatic wall simplification, the calculated temperature in the gaps between the impeller and the stator elements is significantly overestimated. Modeling of the working process in the flow part was carried out with a coupled heat exchanger, as well as with simplified accounting for heat transfer by setting the temperatures of the walls. The gas-dynamic characteristics of the stage were compared with the experimental data, the heat transfer influence on the disks friction coefficient was estimated, and the temperature distributions in the gaps between disks and in the flow part of the stage were analyzed. It is shown that the main principle when modeling the flow in low-flow stage is to ensure correct temperature distribution in the gaps.

Artificially Ventilated Cavities: Evaluating the Constant-Pressure Approximation

2017 ◽  
Author(s):  
Melissa A. Fronzeo ◽  
Michael Kinzel ◽  
Jules Lindau
Keyword(s):  
Constant Pressure ◽  
Flow Behavior ◽  
Internal Cavity ◽  
Common Assumption ◽  
Ventilated Cavity ◽  
Physical Insight ◽  
Circulatory Flow ◽  
Computational Fluid Dynamics Cfd ◽  
The Common ◽  
Semi Empirical

Computational Fluid Dynamics (CFD) is employed to study the fundamental aspects of the internal pressure within artificially ventilated, gaseous cavities in both twin- and toroidal-vortex closure modes. The results show that several pressure regions develop within the cavities, indicating that the common assumption that the cavity has a constant pressure breaks down when evaluated in high detail. The internal cavity pressure is evaluated using a probability density function (PDF). The resulting PDF plots show a clusters with multiple peaks. A mixture-of-Gaussians (MOG) method is employed to better understand the distributions of these peaks. These peaks are then mapped to the simulation results, where it is observed that these peaks correlate to distinct cavity regions (which vary depending on cavity type). Moreover, these varying pressure regions appear to align with cavity-radius growth and reduction and appear to be the driving force of the internal, circulatory flow. Lastly, the importance of these pressure regions are investigated with respect to predictions from semi-empirical theory of the cavity shape, showing a moderate impact depending on where the cavity is probed. Overall, these results provide physical insight into ventilated cavity flow behavior that is often ignored.

The Dynamics of a Cantilevered Pipe Aspirating Fluid Studied by Experimental, Numerical and Analytical Methods

2010 ◽  
Author(s):  
Dana Giacobbi ◽  
Stephanie Rinaldi ◽  
Christian Semler ◽  
Michael P. Pai¨doussis
Keyword(s):  
Analytical Model ◽  
Low Flow ◽  
Computational Fluid Dynamics Cfd ◽  
Computational Structural Mechanics ◽  
Cantilevered Pipe ◽  
The Galerkin Method ◽  
Csm Model ◽  
Ocean Mining ◽  
Flow Experiments ◽  
Flow Velocities

This paper investigates the dynamics of a slender, flexible, aspirating cantilevered pipe, ingesting fluid at its free end and conveying it towards its clamped end. The problem is interesting not only from a fundamental perspective, but also because applications exist, notably in ocean mining [1]. First, the need for the present work is demonstrated through a review of previous research into the topic — spanning many years and yielding often contradictory results — most recently concluding that the system loses stability by flutter at relatively low flow velocities [2]. In the current paper, that conclusion is refined and expanded upon by exploring the problem in three ways: experimentally, numerically and analytically. First, air-flow experiments, in which the flow velocity of the fluid was varied and the frequency and amplitude of oscillation of the pipe were measured, were conducted using different elastomer pipes and intake shapes. Second, a fully-coupled Computational Fluid Dynamics (CFD) and Computational Structural Mechanics (CSM) model was developed in ANSYS in order to simulate experiments and corroborate experimental results. Finally, using an analytical approach, the existing linear equation of motion describing the system was significantly improved upon, and then solved via the Galerkin method in order to determine its stability characteristics. Heavily influenced by a CFD analysis, the proposed analytical model is different from previous ones, most notably because of the inclusion of a two-part fluid depressurization at the intake. In general, both the actual and numerical experiments suggest a first-mode loss of stability by flutter at relatively low flow velocities, which agrees with the results from the new analytical model.

An Integrated Ship Re-Design/Modification Strategy

2019 ◽  
Vol 161 (A1) ◽  
Keyword(s):  
Computer Aided Design ◽  
Modular Design ◽  
Ship Hull ◽  
Cfd Model ◽  
Hull Form ◽  
Design Modification ◽  
Technical Parameters ◽  
Computational Fluid Dynamics Cfd ◽  
Bulbous Bow ◽  
Aided Design

Herein, we present an integrated ship re-design/modification strategy that integrates the ‘Computer-Aided Design (CAD)’ and ‘Computational Fluid Dynamics (CFD)’ to modify the ship hull form for better performance in resistance. We assume a modular design and the ship hull form modification focuses on the forward module (e.g. bulbous bow) and aft module (e.g. stern bulb) only. The ship hull form CAD model is implemented with NAPA*TM and CFD model is implemented with Shipflow**TM. The basic ship hull form parameters are not changed and the modifications in some of the technical parameters because of re-designed bulbous bow and stern bulb are kept at very minimum. The bulbous bow is re-designed by extending an earlier method (Sharma and Sha (2005b)) and stern bulb parameters for re-design are computed from the experience gained from literature survey. The re-designed hull form is modeled in CAD and is integrated and analyzed with Shipflow**TM. The CAD and CFD integrated model is validated and verified with the ITTC approved recommendations and guidelines. The proposed numerical methodology is implemented on the ship hull form modification of a benchmark ship, i.e. KRISO container ship (KCS). The presented results show that the modified ship hull form of KCS - with only bow and stern modifications - using the present strategy, results into resistance and propulsive improvement.

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