Helmholtz-Like Resonator Self-Sustained Oscillations, Part 2: Detailed Flow Measurements and Numerical Simulations

AIAA Journal ◽  
2003 ◽  
Vol 41 (3) ◽  
pp. 416-423 ◽  
Author(s):  
S. Dequand ◽  
S. Hulshoff ◽  
H. van Kuijk ◽  
J. Willems ◽  
A. Hirschberg
Keyword(s):  
Numerical Simulations ◽  
Flow Measurements ◽  
Sustained Oscillations

scholarly journals Performances and Flow Analysis in the Centrifugal Vortex Pump

2013 ◽  
Vol 135 (1) ◽  
Author(s):  
Tihomir Mihalić ◽  
Zvonimir Guzović ◽  
Andrej Predin
Keyword(s):  
Numerical Simulations ◽  
Centrifugal Pump ◽  
Fluid Dynamic ◽  
Flow Analysis ◽  
Physical Models ◽  
Back Side ◽  
Additional Energy ◽  
Flow Measurements ◽  
Vortex Pump ◽  
Fluid Particles

Improvements to the characteristics of a centrifugal pump through the addition of a vortex rotor were investigated both experimentally and with computational fluid dynamic (CFD) analysis. The idea behind that improvement is in creating so-called coherent structures of eddies and turbulence in the peripheral area of the vortex rotor mounted at the back side of centrifugal rotor. Research on the energy transformations in the centrifugal vortex pump in this work was carried out using numerical simulations of the flow in the centrifugal and the centrifugal vortex pump. Measurements of relevant parameters that describe the performance of pumps, at their physical models, were gained from experiments. The measurement results were used as experimental validation of numerical simulations. In contrast, flow visualization derived from the numerical simulation was used to interpret measurements. In deriving the experimental procedure, special care was taken with the flow measurements. The reason for this is in the fact that the flow measurements had the biggest influence on the overall measurement uncertainty. However, flow measurements were the most demanding with regards to the experiment design and in taking the measurement readings. This experimental-CFD research made it possible to undertake an assessment of vortex rotor contribution on the head of the centrifugal vortex pump. The influence of the vortex rotor on the efficiency of the centrifugal vortex pump was investigated by comparing it with the efficiency of the centrifugal pump with the same geometry. An analysis of the flow structure was conducted in order to better understand the energy transformations that are the result of the interaction between the flow from the channels of the centrifugal part of the centrifugal vortex rotor and vortices formed at the vortex part of the centrifugal vortex rotor as well as their interactions with the stator. It was shown that this additional energy significantly increases pump head while increasing pump stability. This synergetic work has demonstrated that while vortex rotor gives additional energy to the fluid particles, that did not enter stator due to the energy lack by changing their momentum; at the same time, some of the kinetic energy contained in the vortex rotor induced vortices is also added to those fluid particles.

scholarly journals Numerical and experimental investigations on vibration of simulated CANDU fuel bundles subjected to turbulent fluid flow

2021 ◽  
Author(s):  
Xuan Zhang
Keyword(s):  
Numerical Simulations ◽  
Nuclear Reactor ◽  
Plate Theory ◽  
Three Dimensional ◽  
Element Model ◽  
Experimental Investigations ◽  
Flow Induced Vibration ◽  
Flow Measurements ◽  
Eddy Simulation ◽  
Fuel Bundle

Vibration of simulated CANDU fuel bundles induced by coolant flow is investigated in this thesis through experiments and numerical simulations. Two simulated bundles and a hydraulic loop are built to mimic the situation of the fuel bundles located at the inlet of a fuel channel in a CANDU nuclear reactor. Fuel bundle vibration mechanism is investigated through experiments and numerical simulations. The three-dimensional turbulent flow that passes through the simulated bundles is modeled using the large eddy simulation (LES) and solved with parallel processing. The local cross flows induced by the presence of endplates at the inlet location and bundle interface location are investigated. The fluid forces are obtained as excitations for the fuel bundle vibration analysis. A finite element model of the fuel bundles is developed with the endplates modeled using the 3rd order thick plate theory. The response of the inlet fuel bundle to the fluid excitations is solved in the time and the frequency domain. The added mass and the fluid damping are approximated with the theory on the flow-induced vibration of slender bodies in a parallel flow. Measurements are obtained and used to validate the numerical prediction under various operating flow conditions.

scholarly journals Numerical and experimental investigations on vibration of simulated CANDU fuel bundles subjected to turbulent fluid flow

2021 ◽  
Author(s):  
Xuan Zhang
Keyword(s):  
Numerical Simulations ◽  
Nuclear Reactor ◽  
Plate Theory ◽  
Three Dimensional ◽  
Element Model ◽  
Experimental Investigations ◽  
Flow Induced Vibration ◽  
Flow Measurements ◽  
Eddy Simulation ◽  
Fuel Bundle

Vibration of simulated CANDU fuel bundles induced by coolant flow is investigated in this thesis through experiments and numerical simulations. Two simulated bundles and a hydraulic loop are built to mimic the situation of the fuel bundles located at the inlet of a fuel channel in a CANDU nuclear reactor. Fuel bundle vibration mechanism is investigated through experiments and numerical simulations. The three-dimensional turbulent flow that passes through the simulated bundles is modeled using the large eddy simulation (LES) and solved with parallel processing. The local cross flows induced by the presence of endplates at the inlet location and bundle interface location are investigated. The fluid forces are obtained as excitations for the fuel bundle vibration analysis. A finite element model of the fuel bundles is developed with the endplates modeled using the 3rd order thick plate theory. The response of the inlet fuel bundle to the fluid excitations is solved in the time and the frequency domain. The added mass and the fluid damping are approximated with the theory on the flow-induced vibration of slender bodies in a parallel flow. Measurements are obtained and used to validate the numerical prediction under various operating flow conditions.

Control of Vortical Flows Past Open Cavities

2013 ◽  
Vol 332 ◽  
pp. 21-26
Author(s):  
Marius Stoia-Djeska ◽  
Carmen Anca Safta ◽  
Adina Cotuna
Keyword(s):  
Aspect Ratio ◽  
Numerical Simulations ◽  
Compressible Flows ◽  
Leading Edge ◽  
Control Device ◽  
Spanwise Direction ◽  
Large Aspect Ratio ◽  
Pressure Oscillations ◽  
Sustained Oscillations ◽  
Open Cavities

Numerical simulations are used to verify the possibility to mitigate the undesired flow self-sustained oscillations of the compressible flows past open cavities. The simple control device proposed in this work consists in a large aspect ratio wing with an non-symmetric thin airfoil mounted in the spanwise direction of the cavity and located immediately upstream with respect the leading edge of the cavity . The results show that this control device is efficient and diminishes the pressure oscillations.

scholarly journals In vitro Biomodels in Stenotic Arteries to Perform Blood Analogues Flow Visualizations and Measurements: A Review

2020 ◽  
Vol 14 (1) ◽  
pp. 87-102 ◽  
Author(s):  
Violeta Carvalho ◽  
Inês Maia ◽  
Andrews Souza ◽  
João Ribeiro ◽  
Pedro Costa ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Flow Behavior ◽  
Measurement Techniques ◽  
Alternative Methods ◽  
Flow Measurements ◽  
Physiological Variables ◽  
Macro Scale ◽  
Stenotic Arteries

Cardiovascular diseases are one of the leading causes of death globally and the most common pathological process is atherosclerosis. Over the years, these cardiovascular complications have been extensively studied by applying in vivo, in vitro and numerical methods (in silico). In vivo studies represent more accurately the physiological conditions and provide the most realistic data. Nevertheless, these approaches are expensive, and it is complex to control several physiological variables. Hence, the continuous effort to find reliable alternative methods has been growing. In the last decades, numerical simulations have been widely used to assess the blood flow behavior in stenotic arteries and, consequently, providing insights into the cardiovascular disease condition, its progression and therapeutic optimization. However, it is necessary to ensure its accuracy and reliability by comparing the numerical simulations with clinical and experimental data. For this reason, with the progress of the in vitro flow measurement techniques and rapid prototyping, experimental investigation of hemodynamics has gained widespread attention. The present work reviews state-of-the-art in vitro macro-scale arterial stenotic biomodels for flow measurements, summarizing the different fabrication methods, blood analogues and highlighting advantages and limitations of the most used techniques.

scholarly journals Hemodynamic numerical simulations of the disturbance due to intracoronary flow measurements by a Doppler guide wire

2016 ◽  
Vol 15 (1) ◽  
Author(s):  
Kamil J. Chodzyński ◽  
Simone Gremmo ◽  
Omer F. Eker ◽  
Jacques Lalmand ◽  
Adel Aminian ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Guide Wire ◽  
Flow Measurements

scholarly journals Electroosmotic flow measurements in a freely suspended liquid film: Experimhents and numerical simulations

2017 ◽  
Vol 38 (20) ◽  
pp. 2554-2560 ◽  
Author(s):  
Abdulkadir Hussein Sheik ◽  
Himiyage Chaminda Hemaka Bandulasena ◽  
Victor Starov ◽  
Anna Trybala
Keyword(s):  
Liquid Film ◽  
Numerical Simulations ◽  
Electroosmotic Flow ◽  
Flow Measurements ◽  
Freely Suspended
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