Computed Effects of Rotor-Induced Swirl on Brush Seal Performance—Part 1: Leakage Analysis

1996 ◽  
Vol 118 (4) ◽  
pp. 912-919 ◽  
Author(s):  
M. C. Sharatchandra ◽  
D. L. Rhode
Keyword(s):  
Stokes Equations ◽  
Numerical Study ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Brush Seal ◽  
Leakage Resistance ◽  
Flow Features ◽  
Tube Banks ◽  
Volume Method ◽  
Relationship Of

This paper presents a numerical study of the effects of rotor induced swirl velocity on the performance of brush seals. Such effects have been studied experimentally by Ferguson (1988), but this paper is apparently the first to obtain an enhanced understanding from the detailed flowfield distributions. The analysis involves the solution of the full Navier-Stokes equations in a two-dimensional, idealized configuration using a strongly conservative finite volume method developed by the authors in conjunction with the QUICK differencing scheme. The present computations have demonstrated excellent agreement with measurements for the similar flow across tube banks. An enhanced understanding of decreasing leakage with increasing shaft speed was obtained in terms of the various flow features. Specifically, the cause and effect relationship of certain interactions between the axial and tangential flows was identified. Computer-drawn pathlines show how increased leakage resistance results from large rotor-induced lateral motion of leakage fluid particles. In addition, a first-order streamwise periodic boundary condition treatment which facilitates numerical convergence has been proposed for essentially any flow which is streamwise periodic in two orthogonal directions.

scholarly journals Dynamics of Single Droplet Splashing on Liquid Film by Coupling FVM with VOF

Processes ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 841
Author(s):  
Yuzhen Jin ◽  
Huang Zhou ◽  
Linhang Zhu ◽  
Zeqing Li
Keyword(s):  
Liquid Film ◽  
Weber Number ◽  
Stokes Equations ◽  
Numerical Study ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Single Droplet ◽  
Navier Stokes Equations ◽  
Volume Method ◽  
The Relationship

A three-dimensional numerical study of a single droplet splashing vertically on a liquid film is presented. The numerical method is based on the finite volume method (FVM) of Navier–Stokes equations coupled with the volume of fluid (VOF) method, and the adaptive local mesh refinement technology is adopted. It enables the liquid–gas interface to be tracked more accurately, and to be less computationally expensive. The relationship between the diameter of the free rim, the height of the crown with different numbers of collision Weber, and the thickness of the liquid film is explored. The results indicate that the crown height increases as the Weber number increases, and the diameter of the crown rim is inversely proportional to the collision Weber number. It can also be concluded that the dimensionless height of the crown decreases with the increase in the thickness of the dimensionless liquid film, which has little effect on the diameter of the crown rim during its growth.

Numerical Study of Wave Slamming on an Oscillating Flap

2014 ◽  
Author(s):  
Yanji Wei ◽  
Alan Henry ◽  
Olivier Kimmoun ◽  
Frederic Dias
Keyword(s):  
Stokes Equations ◽  
Numerical Study ◽  
Flow Characteristics ◽  
Ocean Waves ◽  
Navier Stokes ◽  
Time Step ◽  
Navier Stokes Equations ◽  
Numerical Studies ◽  
Wave Slamming ◽  
Volume Method

Bottom hinged Oscillating Wave Surge Converters (OWSCs) are efficient devices for extracting power from ocean waves. There is limited knowledge about wave slamming on such devices. This paper deals with numerical studies of wave slamming on an oscillating flap to investigate the mechanism of slamming events. In our model, the Navier–Stokes equations are discretized using the Finite Volume method with the Volume of Fluid (VOF) approach for interface capturing. Waves are generated by a flap-type wave maker in the numerical wave tank, and the dynamic mesh method is applied to model the motion of the oscillating flap. Basic mesh and time step refinement studies are performed. The flow characteristics in a slamming event are analysed based on numerical results. Various simulations with different flap densities, water depths and wave amplitudes are performed for a better understanding of the slamming.

Numerical Study of Wing Aerodynamics in Ground Proximity

2008 ◽  
Author(s):  
Alex E. Ockfen ◽  
Konstantin I. Matveev
Keyword(s):  
Iterative Process ◽  
Stokes Equations ◽  
Numerical Study ◽  
Ground Effect ◽  
Aerodynamic Characteristics ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Design And Optimization ◽  
Volume Method ◽  
Experimental Design And Optimization

Experimental design and optimization of innovative ground-effect transportation means is an iterative process which requires a large amount of time and resources. To avoid the large experimental expense, numerical modeling can be used to investigate Wing-in-Ground (WIG) vehicle flight. In this paper, modeling technique is applied for a two dimensional NACA 4412 airfoil in viscous flow in and out of ground effect. The numerical method consists of a steady state, incompressible, finite volume method utilizing the Spalart-Allmaras turbulence model. Grid generation and solution of the Navier-Stokes equations are completed using FLUENT 6.3. The modeling procedures are first validated against published experimental data for unbounded flow around an airfoil. Wing section aerodynamic characteristics are then studied for varying ground heights and two separate boundary conditions: fixed ground and moving ground. Ground effect calculations are compared to several previous studies, and our results are found to correlate with published aerodynamic trends in ground effect, although all studies appear to predict different magnitudes of aerodynamic forces.

A Numerical Study of Vortex Shedding From a Square Cylinder With Ground Effect

1997 ◽  
Vol 119 (3) ◽  
pp. 512-518 ◽  
Author(s):  
Robert R. Hwang ◽  
Chia-Chi Yao
Keyword(s):  
Vortex Shedding ◽  
Stokes Equations ◽  
Numerical Study ◽  
Subsequent Development ◽  
Ground Effect ◽  
Navier Stokes ◽  
Square Cylinder ◽  
Navier Stokes Equations ◽  
Layer Flow ◽  
Volume Method

A numerical study has been conducted to investigate the behavior of the vortical wake created by a square cylinder placed in a laminar boundary-layer flow. The calculations are performed by solving the unsteady 2D Navier-Stokes equations with a finite-volume method. The Reynolds-number regime investigated is from 500 to 1500. Another parameter that is varied is the distance of the cylinder from the wall. The initial and subsequent development of the vortex shedding phenomenon are investigated. The presence of the wall is found to have strong effects on the properties of these vortices, as well as lift, drag, and Strouhal number.

scholarly journals Three-Dimensional Numerical Study of the Effect of Protective Barrier on the Dispersion of the Contaminant in a Building

Mathematics ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 1125
Author(s):  
Chemseddine Maatki
Keyword(s):  
Rayleigh Number ◽  
Stokes Equations ◽  
Numerical Study ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Vorticity Vector ◽  
Volume Method ◽  
The Impact ◽  
Buoyancy Ratio

The finite volume method and potential-vorticity vector formalism in their three-dimensional form were used to numerically study the impact of an adiabatic and impermeable vertical barrier on the dispersion of a local aero-contaminant due to the double-diffusive Rayleigh–Benard convection inside a cubic container. Different governing parameters such as the Rayleigh number, buoyancy ratio and barrier height were analyzed for Le = 1.2 and Pr = 0.7, representing an air-contaminant mixture. The potential-vector-vorticity formalism in the three-dimensional form allowed the elimination of the pressure terms appearing in the Navier–Stokes equations. It was found that the heat and mass transfer as well as the effectiveness of the barrier in reducing contaminant dispersion are strongly influenced by the buoyancy ratio, the barrier size and the Rayleigh number. In addition, the barrier effectiveness is more than 70% for a height of half the building height.

scholarly journals A Comparative Numerical Study on the Performances and Vortical Patterns of Two Bioinspired Oscillatory Mechanisms: Undulating and Pure Heaving

2015 ◽  
Vol 2015 ◽  
pp. 1-25 ◽  
Author(s):  
Mohsen Ebrahimi ◽  
Madjid Abbaspour
Keyword(s):  
Stokes Equations ◽  
Numerical Study ◽  
Leading Edge ◽  
Navier Stokes ◽  
Arbitrary Lagrangian Eulerian ◽  
Navier Stokes Equations ◽  
And Performance ◽  
Volume Method ◽  
Thrust Production ◽  
High Thrust

The hydrodynamics and energetics of bioinspired oscillating mechanisms have received significant attentions by engineers and biologists to develop the underwater and air vehicles. Undulating and pure heaving (or plunging) motions are two significant mechanisms which are utilized in nature to provide propulsive, maneuvering, and stabilization forces. This study aims to elucidate and compare the propulsive vortical signature and performance of these two important natural mechanisms through a systematic numerical study. Navier-Stokes equations are solved, by a pressure-based finite volume method solver, in an arbitrary Lagrangian-Eulerian (ALE) framework domain containing a2D NACA0012foil moving with prescribed kinematics. Some of the important findings are (1) the thrust production of the heaving foil begins at lower St and has a greater growing slope with respect to the St; (2) the undulating mechanism has some limitations to produce high thrust forces; (3) the undulating foil shows a lower power consumption and higher efficiency; (4) changing the Reynolds number (Re) in a constant St affects the performance of the oscillations; and (5) there is a distinguishable appearance of leading edge vortices in the wake of the heaving foil without observable ones in the wake of the undulating foil, especially at higher St.

scholarly journals A Numerical Study of Wind Flow Over a Coal Storage Shelter

10.14311/1692 ◽  
2012 ◽  
Vol 52 (6) ◽  
Author(s):  
Tomáš Bodnár ◽  
Ludek Beneš ◽  
Luboš Pirkl ◽  
Eva Gulíková
Keyword(s):  
Flow Model ◽  
Stokes Equations ◽  
Numerical Study ◽  
Navier Stokes ◽  
Wind Flow ◽  
Two Dimensional ◽  
Navier Stokes Equations ◽  
Structured Grid ◽  
Impermeable Wall ◽  
Volume Method

This paper presents some of the main numerical results obtained while simulating the wind flow over a shelter covering a coal storage. The aim of this numerical study was to evaluate the change in flow patterns caused by adding an impermeable wall to the originally open shelter. The numerical simulations of selected two-dimensional cases were performed using an open-source CFD code. The flow model is based on Reynolds-Averaged Navier-Stokes Equations solved using a finite-volume method on a structured grid. The turbulence is parametrized using the standard k − ε model. Two shelter wall configuration variants are evaluated, and are compared with the original open shelter setup.

Effect of the Separating Distance of Twin Buildings on the Generated Flow Structure

2010 ◽  
Vol 297-301 ◽  
pp. 924-929
Author(s):  
Inès Bhouri Baouab ◽  
Nejla Mahjoub Said ◽  
Hatem Mhiri ◽  
Georges Le Palec ◽  
Philippe Bournot
Keyword(s):  
Stokes Equations ◽  
Three Dimensional ◽  
Reynolds Stress Model ◽  
Navier Stokes ◽  
Wind Flow ◽  
Turbulent Model ◽  
Navier Stokes Equations ◽  
Twin Buildings ◽  
Volume Method ◽  
Numerical Examination

The present work consists in a numerical examination of the dispersion of pollutants discharged from a bent chimney and crossing twin similar cubic obstacles placed in the lee side of the source. The resulting flow is assumed to be steady, three-dimensional and turbulent. Its modelling is based upon the resolution of the Navier Stokes equations by means of the finite volume method together with the RSM (Reynolds Stress Model) turbulent model. This examination aims essentially at detailing the wind flow perturbations, the recirculation and turbulence generated by the presence of the twin cubic obstacles placed tandem at different spacing distances (gaps): W = 4 h, W = 2 h and W = 1 h where W is the distance separating both buildings.

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