Numerical and Experimental Analysis of Monostable Mini- and Micro-Oscillators

2007 ◽  
Author(s):  
Rachid Khelfaoui ◽  
Ste´phane Colin ◽  
Robert Caen ◽  
Ste´phane Orieux ◽  
Lucien Baldas
Keyword(s):  
Experimental Data ◽  
Experimental Analysis ◽  
Feedback Loop ◽  
Cfd Simulation ◽  
Sound Propagation ◽  
Simple Analytical Model ◽  
Main Effect ◽  
Compact Plane ◽  
Good Agreement ◽  
Secondary Oscillation

An asymmetric micro-oscillator design based on a monostable fluidic amplifier is proposed. Experimental data with various feedback loop configurations point out that the main effect responsible for the oscillation is a capacitive and not a propagative effect. Actually, sound propagation in the feedback loop only generates a secondary oscillation which is not strong enough to provoke the jet switching. Data from a hybrid simulation using a commercial CFD code and a simple analytical model are in good agreement with the experimental data. A more compact plane design with reduced feedback loop volumes is also studied through a fully CFD simulation that confirms the previous conclusions.

A Simple Analytical Model to Simulate Oblique Ballistic Impact onto Fabric

2011 ◽  
Vol 110-116 ◽  
pp. 3453-3458
Author(s):  
Mohamad Ali Akbari ◽  
Golam Hosein Liaghat ◽  
Hadi Sabouri
Keyword(s):  
Experimental Data ◽  
Analytical Model ◽  
Ballistic Impact ◽  
Experimental Results ◽  
Simple Analytical Model ◽  
Good Agreement

A simple analytical model for oblique ballistic impact of projectiles into fabrics are presented. This model is extension of Chocron-Benloulo penetration model. Results are compared with experimental data. There is good agreement between analytical and experimental results.

Numerical Simulation of Cavitation Phenomena in a Centrifugal Pump

2009 ◽  
Author(s):  
Freddy Jeanty ◽  
Jesu´s De Andrade ◽  
Miguel Asuaje ◽  
Frank Kenyery ◽  
Auristela Va´squez ◽  
...  
Keyword(s):  
Experimental Data ◽  
Centrifugal Pump ◽  
Cfd Simulation ◽  
Common Phenomenon ◽  
Performance Parameters ◽  
Centrifugal Pumps ◽  
Cavitation Model ◽  
Cfd Simulations ◽  
Global Performance ◽  
Good Agreement

Cavitation is a common phenomenon that appears during the operation of the hydraulic turbomachines reducing performance and life of Centrifugal pumps. The main goal of this work is primarily a CFD-simulation of the whole Centrifugal Pump-Turbine including the suction cone, impeller, diffuser blades and volute, in order to characterize and evaluate its performance under cavitation conditions. The CFD simulations results were compared with experimental data under cavitation and non-cavitation conditions. A good agreement has been obtained under non-cavitation conditions for global performance parameters. After the implementation of the Rayleigh Plesset cavitation model, the required Net Positive Suction Head (NPSHr) has been predicted from CFD simulations. Finally, a full cavitation test can be reproduced for a Hydraulic Turbomachine to avoid this dangerous phenomenon.

Experimental and Numerical Investigation of Stationary Ribbed Ducts

2004 ◽  
Author(s):  
A. Magi ◽  
F. Montomoli ◽  
P. Adami ◽  
C. Carcasci
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Cfd Simulation ◽  
Low Cost ◽  
Turbulence Models ◽  
Data Set ◽  
Contour Maps ◽  
Accuracy Level ◽  
Coolant System ◽  
Good Agreement

Goal of this work is to define the main issues and guidelines for an accurate heat transfer CFD simulation of internal ribbed ducts. To this aim, two different ribbed ducts (AR = 1,3) have been experimentally investigated to obtain a data set useful to validate numerical analyses. Experimental HTC contour maps have been obtained using unsteady TLC technique. CFD activity deals with numerical simulation using both a commercial (Star-CD™) and an “in house” solver (HybFlow). Four different variants of the well-known two-equation turbulence models have been considered. Low cost heat transfer predictions of internal ducts are highly demanded by industry despite the uncommon complexity of modern internal coolant system. Accordingly, the main aim of the work is to provide some indications for the numerical modelling and to evaluate the accuracy level of predicted heat transfer when commercial or research packages are employed along with different grid resolution levels. Overall results are in good agreement with experimental data even if some local discrepancies are present.

Influence of Jordanian zeolite on the performance of a solar still: experiments and CFD simulation studies

2016 ◽  
Vol 16 (6) ◽  
pp. 1700-1709 ◽  
Author(s):  
Yazan Taamneh
Keyword(s):  
Experimental Data ◽  
Phase Change ◽  
Cfd Simulation ◽  
Volume Fraction ◽  
Solar Still ◽  
Cfd Simulations ◽  
Two Phase ◽  
Vof Model ◽  
Computational Fluid Dynamics Cfd ◽  
Good Agreement

Computational fluid dynamics (CFD) simulations were performed for experiments carried out with two identical pyramid-shaped solar stills. One was filled with Jordanian zeolite-seawater and the second was filled with seawater only. This work is focused on CFD analysis validation with experimental data conducted using a model of phase change interaction (evaporation-condensation model) inside the solar still. A volume-of-fluid (VOF) model was used to simulate the inter phase change through evaporation-condensation between zeolite-water and water vapor inside the two solar stills. The effect of the volume fraction of the zeolite particles (0 ≤ ϕ ≤ 0.05) on the heat and distillate yield inside the solar still was investigated. Based on the CFD simulation results, the hourly quantity of freshwater showed a good agreement with the corresponding experimental data. The present study has established the utility of using the VOF two phase flow model to provide a reasonable solution to the complicated inter phase mass transfer in a solar still.

CFD Study of Tidal Current Turbine Shroud for Initial Design Evaluation

2014 ◽  
Vol 679 ◽  
pp. 35-38 ◽  
Author(s):  
Azim Arshad ◽  
Shahrani Anuar ◽  
Ahmmad Shukrie ◽  
Rosdi Hussin
Keyword(s):  
Experimental Data ◽  
Tidal Current ◽  
Cfd Simulation ◽  
Ansys Fluent ◽  
Commercial Code ◽  
Simulation And Experiment ◽  
Tidal Current Turbine ◽  
Coefficient Of Velocity ◽  
Current Turbine ◽  
Good Agreement

CFD simulation of a tidal current turbine shroud was performed using Ansys FLUENT commercial code and comparison was made with experimental data. The simulation result obtained was in good agreement with the experimental data. The coefficient of velocity, Cv was in the range of approximately 1.2 to 1.4 for both simulation and experiment. The present study gave useful information on the viability of CFD simulation for the initial evaluation of shroud design performance.

scholarly journals CFD Simulation of an Industrial Spiral Refrigeration System

Energies ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 3358
Author(s):  
A. Khenien ◽  
A. Benattayallah ◽  
G. Tabor
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Cfd Simulation ◽  
Regulatory Requirements ◽  
Cfd Simulations ◽  
Conduction Model ◽  
Cfd Models ◽  
Heating And Cooling ◽  
Mri Scans ◽  
Good Agreement

In the food industry, heating and cooling are key processes where CFD can play an important role in improving quality, productivity and reducing energy costs. Cooling products after baking is crucial for storage and transportation; the product has to be cooled efficiently to a specified temperature (often to fulfill regulatory requirements) whilst preserving its quality. This study involves the analysis of spiral cooling refrigerators used in cooling food products, in this case, Cornish Pasties. Three separate sets of CFD models were developed and validated against experimental data taken in the laboratory and measurements taken in use in industry. In the first set of models a full CFD model was developed of a refrigeration spiral including the pasties, and used to study the heat transfer from the products to the air. Further simulations were carried out on individual pasties to explore the pasty cooling and heat transfer to the air in more detail, with the pasty geometry being determined from MRI scans. In the final set of simulations, Image Based Meshing (IBM) was used to determine the interior structure of the pasty and develop a full heat conduction model of the interior, which was compared with separate laboratory experiments using jets of cold air to cool the pasty. In all cases, good agreement was obtained between the CFD results and experimental data, whilst the CFD simulations provide valuable information about the air flows and cooling in the industrial system.

CFD Simulation of Hydraulics of Sieve Trays with Gas Mal-Distribution

2010 ◽  
Vol 5 (1) ◽  
Author(s):  
Mahmood Reza Rahimi ◽  
Hajir Karimi
Keyword(s):  
Experimental Data ◽  
Path Length ◽  
Gas Flow ◽  
Cfd Simulation ◽  
Three Dimensional ◽  
Flow Path ◽  
Superficial Velocity ◽  
Gas Velocity ◽  
Flow Path Length ◽  
Good Agreement

A transient three-dimensional, two-fluid computational fluid dynamics (CFD) model is developed in the Eulerian framework to predict the hydraulics of sieve trays, especially with gas maldistribution. For this purpose, an algorithm is developed to explain the hole-gas velocity and pressure drop terms along the liquid flow path length. An important modification to the previous CFD works is the use of variable, position dependent, gas superficial velocity for calculation of interphase drag term along the tray. The flow path length of tray was divided into a number of sections; gas-superficial velocity, hydraulic parameters and drag coefficient were obtained for each section. This modification has an important effect on the simulation results and causes faster convergence and better predictions of tray hydraulics. The results are in good agreement with experimental data. Model results obtained in this study have revealed that the effect of hydraulic gradient is significant for high liquid path length and may create non-uniform gas flow. This paper describes how the inlet flow maldistributions can be included in CFD simulation of sieve trays. The results of simulations with non-uniform gas velocity distributions are presented, and compared against experimental data from literature. The results are in good agreement with experimental data.

Energy Levels and Electromagnetic Transition of 90-94mo Nuclei Using Ibm-1

2020 ◽  
pp. 149-152
Keyword(s):  
Experimental Data ◽  
Transition Probability ◽  
Energy Levels ◽  
Dynamical Symmetry ◽  
Interacting Boson Model ◽  
Excitation Energies ◽  
Electromagnetic Transition ◽  
Boson Model ◽  
Energy States ◽  
Good Agreement

The energy states for the J , b , ɤ bands and electromagnetic transitions B (E2) values for even – even molybdenum 90 – 94 Mo nuclei are calculated in the present work of "the interacting boson model (IBM-1)" . The parameters of the equation of IBM-1 Hamiltonian are determined which yield the best excellent suit the experimental energy states . The positive parity of energy states are obtained by using IBS1. for program for even 90 – 94 Mo isotopes with bosons number 5 , 4 and 5 respectively. The" reduced transition probability B(E2)" of these neuclei are calculated and compared with the experimental data . The ratio of the excitation energies of the 41+ to 21+ states ( R4/2) are also calculated . The calculated and experimental (R4/2) values showed that the 90 – 94 Mo nuclei have the vibrational dynamical symmetry U(5). Good agreement was found from comparison between the calculated energy states and electric quadruple probabilities B(E2) transition of the 90–94Mo isotopes with the experimental data .

Predicting the Effect of Tire Tread Pattern Design on Thick Film Wet Traction

1977 ◽  
Vol 5 (1) ◽  
pp. 6-28 ◽  
Author(s):  
A. L. Browne
Keyword(s):  
Experimental Data ◽  
Network Design ◽  
Thick Film ◽  
Digital Computer ◽  
Analytical Tool ◽  
Design Practice ◽  
Pattern Design ◽  
Performance Results ◽  
Good Agreement

Abstract An analytical tool is presented for the prediction of the effects of changes in tread pattern design on thick film wet traction performance. Results are reported for studies in which the analysis, implemented on a digital computer, was used to determine the effect of different tread geometry features, among these being the number, width, and lateral spacing of longitudinal grooves and the angle of zigzags in longitudinal grooves, on thick film wet traction. These results are shown to be in good agreement with experimental data appearing in the literature and are used to formulate guidelines for tread groove network design practice.

A New Condition of Formation and Stablity of All Crystalline Systems in a Good Agreement with Experimental Data

2015 ◽  
Vol 11 (3) ◽  
pp. 3224-3228
Author(s):  
Tarek El-Ashram
Keyword(s):  
Experimental Data ◽  
Brillouin Zone ◽  
Electron Concentration ◽  
Free Electron ◽  
Lattice Point ◽  
Valence Electron ◽  
Fermi Gas ◽  
Valence Electron Concentration ◽  
Fermi Sphere ◽  
Good Agreement

In this paper we derived a new condition of formation and stability of all crystalline systems and we checked its validity andit is found to be in a good agreement with experimental data. This condition is derived directly from the quantum conditionson the free electron Fermi gas inside the crystal. The new condition relates both the volume of Fermi sphere VF andvolume of Brillouin zone VB by the valence electron concentration VEC as ;𝑽𝑭𝑽𝑩= 𝒏𝑽𝑬𝑪𝟐for all crystalline systems (wheren is the number of atoms per lattice point).

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