scholarly journals Numerical Investigation of Aeroelastic Flutter in Two-Dimensional Cascade of Compressor Blades

2020 ◽  
Vol 328 ◽  
pp. 02020
Author(s):  
Jiří Fürst ◽  
Martin Lasota ◽  
Josef Musil ◽  
Jan Pech
Keyword(s):  
Numerical Study ◽  
Turbulence Models ◽  
Moving Mesh ◽  
Two Dimensional ◽  
Compressor Blades ◽  
Source Codes ◽  
Numerical Predictions ◽  
Aeroelastic Flutter ◽  
Numerical Performance ◽  
Dimensional Section

Following contribution presents numerical study of aeroelastic flutter in two-dimensional section of flat wing cascade in wind tunnel. The investigation is conducted as a parametric study of varying pitch angle of one (middle) blade in the cascade with each computational case performed on fixed computational grid. This approach can be viewed as an approximation of fluid-structure interaction realized on moving mesh. Numerical predictions were carried by means of CFD open-source codes OpenFOAM® and Nektar++. The particular aim was focused on assessment of numerical performance and accuracy of the numerical solvers as well as several turbulence models.

scholarly journals Unsteady RANS Modeling of Flow around Two-Dimensional Rectangular Cylinders with Different Side Ratios at Reynolds Number 6.85 × 105

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Shubiao Wang ◽  
Wenming Cheng ◽  
Run Du ◽  
Yupu Wang
Keyword(s):  
Reynolds Number ◽  
Numerical Study ◽  
Turbulence Models ◽  
Aerodynamic Characteristics ◽  
Navier Stokes ◽  
Bluff Bodies ◽  
Two Dimensional ◽  
Practical Engineering ◽  
Unsteady Rans ◽  
Rectangular Cylinders

In practical engineering, the Reynolds number (Re) of box girder structure is usually very high (Re ≥ 105), while most investigations of the flow around bluff bodies are concentrated on relatively lower Reynolds numbers (i.e., Re = 103–104). This paper presented a numerical study of the unsteady flow around two-dimensional rectangular cylinders under a Reynolds number of 6.85 × 105 with different side ratios (R = b/h, width to height) ranging from 0.1 to 4.0. Three unsteady Reynolds-averaged Navier-Stokes (RANS) two-equation k-ε turbulence models (standard, RNG, and realizable) were adopted in the study. The realizable k-ε model was chosen because it was found to perform the best among three models in the main aerodynamic integral parameters. According to the distinctions of aerodynamic characteristics with different side ratios, three regimes were divided and discussed in detail. The distribution of surface pressure over cylinders, the wake parameters, and vorticity contours of the rectangular cylinders with different side ratios were discussed.

scholarly journals CFD analysis of convergent-divergent nozzle flow and base pressure control using micro-JETS

2018 ◽  
Vol 7 (3.29) ◽  
pp. 232 ◽  
Author(s):  
Ambareen Khan ◽  
Abdul Aabid ◽  
S A. Khan
Keyword(s):  
Numerical Study ◽  
Dynamic Control ◽  
Turbulence Models ◽  
Pressure Control ◽  
Wall Pressure ◽  
Base Pressure ◽  
Nozzle Geometry ◽  
Orifice Diameter ◽  
Two Dimensional ◽  
Planar Area

This paper presents numerical study was undertaken to identify the use of the micro-jets to regulate the pressure in the region from two-dimensional convergent-divergent (CD) Nozzle. At the exit of the divergent nozzle in the base region 1 mm of two micro-jets orifice diameter has been arranged at ninety degrees at pcd 13 mm to control base pressure. The inertia level at the inlet to suddenly expanded duct was 1.87. The micro-jets are suddenly expanded into a two-dimensional planar area ratio of 3.24. The L/D of the duct was 1, 2, 4, 5, 6, 8 and 10. The total wall pressure distribution from inlet to the outlet too was recorded. The results indicate that the micro-jets can oblige as the effective regulators of the pressure in the base area. The duct wall pressure field is not negatively affected by the dynamic control. Nozzles were operated with the NPR in the range from 3 to 11. The results show that we can fix the flow parameter which will result in the maximum gain in the base pressure, velocity and temperature. The convergent-divergent nozzle geometry has been modeled and simulated employing turbulence models: K-ε standard wall function turbulence model from the code was validated with the commercial computational fluid dynamics.   

Numerical Investigation of Turbulence Models for Free Jet Flow

2012 ◽  
Vol 229-231 ◽  
pp. 2082-2085
Author(s):  
Boualem Laribi ◽  
Djelloul Belkacemi ◽  
Hadj Abdellah
Keyword(s):  
Velocity Profile ◽  
Numerical Study ◽  
Practical Interest ◽  
Turbulence Models ◽  
Turbulent Jets ◽  
Experimental Results ◽  
Technical Literature ◽  
Free Jet ◽  
Experimental Profile ◽  
Numerical Predictions

The turbulent jets with swirl are of particularly significant and practical interest in various fields of industry. The present numerical study concerns the comparison between three models of turbulence for the forecast of a turbulent free axi-symmetric jet with turbulence and his development. The software used was CFD code Fluent with his three turbulence models namely k-, k- and RSM. This different turbulence models are tested to better simulate and view the effectiveness of models in the description of the jet behaviour. The parameters of flow examined are the velocity profile of jet at Reynolds number of 22000. Comparisons between numerical predictions and experimental measurements taken from the technical literature for the case of natural jet development show that the numerical techniques of Computational Fluid Dynamics are an important tool for studying the jet’s behaviour. The results indicate that the RSM models is higher than the k- and k- models when looking at changes in velocity profile behaviour towards experimental profile, the k- model can be used for predicting re-circulating flows if we are interested in global settings only. The prediction obtained by k- model is far from experimental results. It is misadvised to use k- model for the jets analysis. The better numerical results were obtained by CFD code CFX, where results are in good agreement with the experimental results.

scholarly journals Numerical Study of the Turbulent Flow from a Steam Dumping Pressurizer Relief Tank

Energies ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 4059
Author(s):  
Sen Zhang ◽  
Xiao-Wei Guo ◽  
Chao Li ◽  
Yi Liu ◽  
Ran Zhao ◽  
...  
Keyword(s):  
Turbulent Flow ◽  
Open Source ◽  
Complex Geometry ◽  
Numerical Study ◽  
Flow Characteristics ◽  
Turbulence Models ◽  
Navier Stokes ◽  
Source Codes ◽  
Model Based ◽  
Eddy Simulation

Due to the complex geometry and turbulent flow characteristics, it is hard to simulate the process of steam dumping of the pressurizer relief tank (PRT). In this study, we develop a compressible fluid solver PRTFOAM to numerically study the turbulent flow dynamics from a PRT. The PRTFOAM is implemented based on the OpenFOAM and designed to be capable of integrating various turbulence models. Two representative Reynolds-averaged Navier–Stokes (RANS) models and a Smagorinsky–Lilly SGS model based on Large Eddy Simulation (LES) are coupled and tested with PRTFOAM. The case of a flow past a circular cylinder (Re = 3900) is tested and analyzed comprehensively as a benchmark case. Then, the turbulent steam dumping process in the full geometry of a PRT is analyzed and compared with ANSYS CFX and literature reports. In addition, we tested the WALE model based on the PRT steam dumping process. The results show that SST k-ω model and Smagorinsky–Lilly SGS model-based LES approach are more appropriate than the LRR model for PRT simulations. Moreover, it shows that the simulation results of Smagorinsky–Lilly SGS model and WALE model are basically consistent under the condition of PRT steam dumping process. Under this condition, the drawbacks of Smagorinsky–Lilly SGS model are not obvious. Furthermore, the comparison with CFX showed that our open source solver could be used to obtain better results in complex engineering cases. The design and testing results would provide guidance for further analysis of thermal-hydraulics in reactors based on open source codes.

Numerical Study on Two-dimensional Magnetic Photonic Crystals Made of Magnetized Ferrites

PIERS Online ◽  
2007 ◽  
Vol 3 (3) ◽  
pp. 305-307 ◽  
Author(s):  
Jie Xu ◽  
Ping Chen ◽  
Yue Shi ◽  
Xin-Yi Ji ◽  
Ai-Min Jiang ◽  
...  
Keyword(s):  
Photonic Crystals ◽  
Numerical Study ◽  
Two Dimensional ◽  
Magnetic Photonic Crystals

Co-planar two-dimensional Metal-Insulator-Semiconductor Capacitor: Numerical study of the device electrostatics.

2017 ◽  
Author(s):  
Varun Bheemireddy
Keyword(s):  
Space Charge ◽  
High Performance ◽  
Numerical Study ◽  
2D Materials ◽  
Space Charge Density ◽  
Two Dimensional ◽  
Short Channel ◽  
Metal Insulator ◽  
Metal Insulator Semiconductor ◽  
New Family

The two-dimensional(2D) materials are highly promising candidates to realise elegant and e cient transistor. In the present letter, we conjecture a novel co-planar metal-insulator-semiconductor(MIS) device(capacitor) completely based on lateral 2D materials architecture and perform numerical study of the capacitor with a particular emphasis on its di erences with the conventional 3D MIS electrostatics. The space-charge density features a long charge-tail extending into the bulk of the semiconductor as opposed to the rapid decay in 3D capacitor. Equivalently, total space-charge and semiconductor capacitance densities are atleast an order of magnitude more in 2D semiconductor. In contrast to the bulk capacitor, expansion of maximum depletion width in 2D semiconductor is observed with increasing doping concentration due to lower electrostatic screening. The heuristic approach of performance analysis(2D vs 3D) for digital-logic transistor suggest higher ON-OFF current ratio in the long-channel limit even without third dimension and considerable room to maximise the performance of short-channel transistor. The present results could potentially trigger the exploration of new family of co-planar at transistors that could play a signi significant role in the future low-power and/or high performance electronics.<br>

scholarly journals Numerical Analysis of Air Vortex Interaction with Porous Screen

Fluids ◽  
2021 ◽  
Vol 6 (2) ◽  
pp. 70
Author(s):  
Xudong An ◽  
Lin Jiang ◽  
Fatemeh Hassanipour
Keyword(s):  
Physical Properties ◽  
Vortex Ring ◽  
Numerical Study ◽  
Flow Behavior ◽  
Industrial Applications ◽  
Moving Mesh ◽  
Vortex Flows ◽  
Vortex Interaction ◽  
Piston Cylinder ◽  
Porous Screen

In many industrial applications, a permeable mesh (porous screen) is used to control the unsteady (most commonly vortex) flows. Vortex flows are known to display intriguing behavior while propagating through porous screens. This numerical study aims to investigate the effects of physical properties such as porosity, Reynolds number, inlet flow dimension, and distance to the screen on the flow behavior. The simulation model includes a piston-cylinder vortex ring generator and a permeable mesh constructed by evenly arranged rods. Two methods of user-defined function and moving mesh have been applied to model the vortex ring generation. The results show the formation, evolution, and characteristics of the vortical rings under various conditions. The results for vorticity contours and the kinetic energy dissipation indicate that the physical properties alter the flow behavior in various ways while propagating through the porous screens. The numerical model, cross-validated with the experimental results, provides a better understanding of the fluid–solid interactions of vortex flows and porous screens.

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