Investigation of Vortex Formation in Water Intake Structures by Computational Fluid Dynamics

2021 ◽  
Author(s):  
Nihat Kaya ◽  
Mustafa Tunc ◽  
Osman Bedreddin Evranos
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Water Intake ◽  
Vortex Formation

Investigation of Air Entrainment: A Numerical Approach

2003 ◽  
Author(s):  
J. T. Kshirsagar ◽  
S. G. Joshi
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Vortex Formation ◽  
Flow Analysis ◽  
Air Entrainment ◽  
Numerical Approach ◽  
Test Cases ◽  
Two Phase ◽  
Root Cause ◽  
Model Study

The air entrainment in sumps (Pump Intake) is a commonly observed phenomenon at low water level and high Froude number corresponding to flow rates higher than the rated flow. The air entrainment initiates with the formation of small vortex like structure on the surface with its position varying in the vicinity of Pump intake portion. Normally it calls for two-phase flow analysis (and possibly transient also) to correctly predict the air entrainment phenomenon using computational fluid dynamics approach. We at CRED, Kirloskar Brothers Limited could predict the root cause for air entrainment by studying the vortex formation well within the flow. A single-phase steady state flow was analyzed. Two test cases were studied. IOWA University had published a sump case with results from computational fluid dynamics studies. The other case was the actual sump model study carried out using experimental setup wherein the air entrainment was observed. The paper presents the comparison of the predictions with results from these two test cases.

scholarly journals A New Device used in Selective Withdrawal from Reservoirs and its Effectiveness Verified in Computational Fluid Dynamics

2018 ◽  
Vol 14 (03) ◽  
pp. 142
Author(s):  
Jinsuo Lu ◽  
Wei Zhang ◽  
Dengyu Wang ◽  
Xiaoyi Wang
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Layer Thickness ◽  
Water Intake ◽  
Flow Distribution ◽  
Water Layer ◽  
Cfd Model ◽  
Selective Withdrawal ◽  
New Device ◽  
Computational Fluid Dynamics Cfd

<p class="16">Water intake with fixed height limits the application of selective withdrawal technology in a certain degree. This study proposes a technological idea to install baffles on water intake. Through the rotation of upper and lower baffle, poor water layer can be blocked. A Computational Fluid Dynamics (CFD) model for the upper baffle on water intake is constructed. The results show that the baffle installed on the upper part of orifice can reduce the withdrawal layer thickness and flow on the upper part of orifice centre. Thereby, the withdrawal flow on lower part can be indirectly increased. While, baffle length and inclining angle are the important factors to influence the withdrawal layer thickness and flow distribution. Therefore, the adjusting range of selective withdrawal can be economically enhanced by installing baffles on water intake.</p>

scholarly journals 3D Flow Modeling of the First Trifurcation Made in Nepal

1970 ◽  
Vol 5 ◽  
pp. 56-61 ◽  
Author(s):  
R K Malik ◽  
Paras Paudel
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Vortex Formation ◽  
Maximum Flow ◽  
Flow Modeling ◽  
Zone Formation ◽  
Physical Constraints ◽  
3 Dimensional ◽  
Dimensional Flow ◽  
Computational Fluid Dynamics Cfd

The foremost objective of the study was to find out the most efficient profile of trifurcation in given constraints of pressure, velocity and layout of the overall geometry. The study was done for the 3.2 MW Madi Khola Hydropower Project of Gandaki Hydropower Development Co. Pvt. Ltd. The 3 Dimensional Flow modeling of the trifurcation was based on the application of Computational Fluid Dynamics (CFD).The loss in the Trifurcation greatly depends upon its geometrical configuration. The research started with a general profi le and the flow pattern generated inside it was studied with the help of 3 Dimensional Flow modeling. The extent of vortex zone formation inside the trifurcation indicates the loss inside trifurcation. The profile of the trifurcation was hence changed to reduce the vortex formation as far as possible, till we get minimum possible loss. The profile under study should meet maximum flow efficiency under the physical constraints of fabrication. The flow efficient profile was then analyzed to capture the stress amplifi cation near junction. The reinforcing element in the form of steel T-section was added of different sectional values till the stress was within allowable limits under severe conditions.Key words: Symmetrical Trifuraction; Trifurcation; Computational fluid dynamics; Hydropower; NepalDOI: 10.3126/hn.v5i0.2493Hydro Nepal Vol. 5, July 2009 Page:56-61

Computational Fluid Dynamics Simulations of Intracranial Aneurysms at Varying Heart Rates: A “Patient-Specific” Study

2009 ◽  
Vol 131 (9) ◽  
Author(s):  
Jingfeng Jiang ◽  
Charles Strother
Keyword(s):  
Fluid Dynamics ◽  
Heart Rate ◽  
Computational Fluid Dynamics ◽  
Intracranial Aneurysms ◽  
Vortex Formation ◽  
Experimental Studies ◽  
Physical Exertion ◽  
Patient Specific ◽  
Heart Rates ◽  
The Impact

Rupture of an intracranial aneurysm (IA) is frequently associated with intense physical exertion and/or emotional excitement, events that are typically also accompanied by sudden significant changes in both heart rate and blood pressure. Very few experimental studies of aneurysm hemodynamics have examined the impact on hemodynamic parameters in and around an aneurysm resulting from changes in heart rate. In order to further understanding these changes, as they relate to hemodynamic features that may contribute to rupture of an IA, we examined the characteristics of pulsatile flow in and around two “patient-specific” intracranial aneurysms at three different cardiac frequencies. Three dimensional X-ray angiographic data (3D-DSA) were used to reconstruct accurate and patient-specific aneurysm geometries. Then, computational fluid dynamics techniques were utilized to analyze the characteristics of blood flow in and around the two aneurysms. Physiologically realistic flow conditions, as measured by transcranial Doppler ultrasound, were used in the simulations. Our results showed that there were significant changes in the overall flow patterns (e.g., vortex formation and translation) associated with the changes of heart rates. In both aneurysms, the calculated wall shear stress exhibited substantial increases with an increase in heart rate. Our results suggest that the changes in local hemodynamic forces associated with variations in heart rate are dependent not only on the heart rate but also on the aneurysm geometry. This thus precludes applying our observations about the impact of variations in cardiac rate to aneurysms in general.

scholarly journals Vortex Prediction in a Pump Intake System Using Computational Fluid Dynamics

2019 ◽  
Vol 8 (10) ◽  
pp. 3158-3163 ◽  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Vortex Formation ◽  
Flow Conditions ◽  
Velocity Change ◽  
Velocity Fluctuations ◽  
Intake System ◽  
Model Studies ◽  
Physical Experiments ◽  
3D Geometry

A pump intake system consists of forebay, pumpbay and pipeline arrangements through which water flows in order to meet its demand. Vortices and velocity fluctuations affects the performance of a pump intake system. This paper presents the vortex prediction in a pump sump for varying flow conditions across the pump bay and the bellmouth section, using computational fluid dynamics (CFD) code Flow 3D. Geometry of rectangular type sump was chosen for comparing the physical experimentation with the computational model. The velocity fluctuations, location of vortex formation and its profiles predicted by CFD code was compared with that of the physically observed experiments. The velocity and fluid flow profiles predicted by CFD correlated well with the flow conditions observed during the physical experiments. Further, characteristics of vortex were also studied with respect to the velocity change. Increase in the wobbling phenomenon of the vortex with increase in the flow velocity was also identified with the computational studies. CFD can be used as a tool to study the preliminary design of a hydraulic system for a particular field condition, thus complementing the physical model studies to facilitate the construction of an optimized and effective pump intake system

Computational Fluid Dynamics and Heat Transfer Analysis of Vortex Formation in a Solar Reactor

2015 ◽  
Vol 7 (4) ◽  
Author(s):  
Min-Hsiu Chien ◽  
Nesrin Ozalp ◽  
Gerald Morrison
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Room Temperature ◽  
Vortex Flow ◽  
Vortex Formation ◽  
Flow Dynamics ◽  
Experimental Results ◽  
Heat Transfer Analysis ◽  
Solar Reactor

A hydrogen-producing solar reactor was experimentally tested to study the cyclone flow dynamics of the gas–particle two-phase phenomenon. Two-dimensional particle image velocimetry (PIV) was used to observe the flow and to quantify the vortex formation inside the solar reactor. The vortex flow structure in the reactor was reconstructed by capturing images from orientations perpendicular and parallel to the geometrical axis of the reactor, respectively. The experimental results showed that the tangential components of the fluid velocity formed a Rankine-vortex profile. The free vortex portions of the Rankine profile were synchronized and independent of the axial position. The axial components showed a vortex funnel of higher speed fluid supplied by a reversing secondary flow. According to the inlet channel design, the geometry dominates the flow dynamics. A stable processing vortex line was observed. As the vortex flow evolves toward the exit, the vortex funnel expands radially with decreasing tangential velocity magnitude peak as a result of the vortex stretching. An optimal residence time of the flow was found by changing the cyclone flow inlet conditions. The swirl number versus the main flow rate change was obtained. Upon completion of the experimental studies, a thorough numerical analysis was conducted to model the flow dynamics inside the solar reactor and to verify the results by comparison to the experimental results. Three turbulence models including the standard k–ϵ, k–ϵ renormalization groups (RNG), and Reynolds stress transport models were used. Computational fluid dynamics (CFD) simulations were coupled with heat transfer analysis via discrete ordinate (DO) model. Particle tracing in Lagrange frame was applied to simulate the particle trajectory. A comparison between the turbulence modeling results for the room temperature and high temperature cases, as well as the experimental results for room temperature cases is presented.

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