A Numerical Simulation of a Brush Seal Section and Some Experimental Results

1995 ◽  
Vol 117 (1) ◽  
pp. 190-202 ◽  
Author(s):  
M. J. Braun ◽  
V. V. Kudriavtsev
Keyword(s):  
Stokes Equations ◽  
Numerical Models ◽  
Navier Stokes ◽  
Local Pressure ◽  
Local Flow ◽  
Navier Stokes Equations ◽  
Pressure Fields ◽  
Brush Seal ◽  
Flow Phenomena ◽  
Insight Into

The brush seal technology represents quite a promising advance in the effort of construction of more efficient, and possibly smaller size engines. Conclusions of recent workshops determined that while the brush seal works well, there is a need to improve its performance characteristics. The considerable amount of experimental work performed to date has indicated the importance of the local flow phenomena in the global sealing process performance of the brush (Braun et al., 1990a, 1991b, 1992; Hendricks et al., 1991a). The distributed flow and pressure fields are thus of vital importance for the prediction of the possible sudden failure of the brush seal under unexpected local “pressure hikes.” It is in this context that the authors developed a numerical, two-dimensional time accurate dependent formulation of the Navier–Stokes equations with constant properties, and included the effects of inertia, viscous, and pressure terms. The algorithm is applied to a set of noncompliant multirow, multicolumn pin configurations that are similar to the ones found in an idealized brush seal configuration. While the numerical parametric investigation aims at establishing the occurrence of major flow patterns and associated pressure maps, the experimental portion of the paper is aimed at gaining further insight into the relevant flow structures, and thus guiding the development of the mathematical and numerical models.

scholarly journals A Numerical Simulation of a Brush Seal Section and Some Experimental Results

1993 ◽  
Author(s):  
M. J. Braun ◽  
V. V. Kudriavtsev
Keyword(s):  
Stokes Equations ◽  
Navier Stokes ◽  
Local Pressure ◽  
Local Flow ◽  
Navier Stokes Equations ◽  
Pressure Fields ◽  
Sudden Failure ◽  
Brush Seal ◽  
Flow Phenomena ◽  
Insight Into

The brush seal technology represents quite a promising advance in the effort of construction of more efficient, and possibly smaller size engines. Conclusions of recent workshops determined that while the brush seals works well, there is a need to improve its performance characteristics. The considerable amount of experimental work performed to date has indicated the importance of the local flow phenomena in the global sealing process performance of the brush (Braun et al., 1990a, 1991b, 1992, Hendricks et al., 1991a). The distributed flow and pressure fields are thus of vital importance for the prediction of the possible sudden failure of the brush seal under unexpected local “pressure hikes”. It is in this context that the authors developed a numerical, two dimensional time dependent formulation of the Navier-Stokes equations with constant properties, and included the effects of inertia, viscous and pressure terms. The algorithm is applied to a set of non-compliant multirow, multicolumn pin configurations that are similar to the ones found in an idealized brush seal configuration. While the numerical parametric investigation aims to establish the occurrence of major flow patterns and associated pressure maps, the experimental portion of the paper is aimed at gaining further insight into the relevant flow structures, and thus guide the development of the mathematical and numerical model.

Numerical Investigation of Flow Around Bluff Bodies

1998 ◽  
Vol 14 (3) ◽  
pp. 153-159 ◽  
Author(s):  
Chou-Jiu Tsai ◽  
Ger-Jyh Chen
Keyword(s):  
Vortex Shedding ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Bluff Bodies ◽  
Near Wake ◽  
Navier Stokes Equations ◽  
Physical Description ◽  
Geometrical Shapes ◽  
Flow Phenomena ◽  
Volume Method

ABSTRACTIn this study, fluid flow around bluff bodies are studied to examine the vortex shedding phenomenon in conjuction with the geometrical shapes of these vortex shedders. These flow phenomena are numerically simulated. A finite volume method is employed to solve the incompressible two-dimensional Navier-Stokes equations. Thus, quantitative descriptions of the vortex shedding phenomenon in the near wake were made, which lead to a detailed description of the vortex shedding mechanism. Streamline contours, figures of lift coefficent, and figures of drag coefficent in various time, are presented, respectively, for a physical description.

Evolution of Generic Vanelets Applied to a High Pressure Compressor

2013 ◽  
Author(s):  
Andreas Loos ◽  
Tobias Mayenberger ◽  
Florian Danner ◽  
Hans-Peter Kau
Keyword(s):  
High Pressure ◽  
Stokes Equations ◽  
Main Flow ◽  
Navier Stokes ◽  
Stable Operation ◽  
Navier Stokes Equations ◽  
Surge Margin ◽  
Flow Phenomena ◽  
Negative Effect ◽  
Generic Design

The flow field of high pressure compressors is strongly influenced by secondary flow phenomena which lead to performance degradations. A significant fraction of the associated losses arises from tip as well as hub clearance vortices and their interaction with the main flow. In order to decrease the negative effect of clearance vortices, the application of vanelets, winglet-like structures attached to the tips of a cantilevered stator, is studied within the present paper. Different vanelets of generic design are applied to the stator and evaluated with respect to their aerodynamic effect by comparison against a datum configuration. The model comprises the investigated stator enclosed between two rotating blade rows. Detailed insight into the underlying phenomena is provided by numerical investigations with the compressible Reynolds-averaged Navier-Stokes equations. The structures led to an increased efficiency at the aerodynamic design point due to the suppression of the clearance mass flow in combination with a reduced vortex cross section. Under strongly throttled conditions a so called vanelet corner stall developed, which induced blockage near hub. Thus the main flow was displaced towards casing enhancing stable operation of the downstream rotor. Surge margin was consequently increased.

Numerical Modeling of Flow Over a Dam Spillway

2006 ◽  
Author(s):  
Iraj Saeedpanah ◽  
M. Shayanfar ◽  
E. Jabbari ◽  
Mohammad Haji Mohammadi
Keyword(s):  
Free Surface ◽  
Stokes Equations ◽  
Iterative Solution ◽  
Free Surface Flows ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Continuity Equations ◽  
Water Jets ◽  
Pressure Fields ◽  
Good Agreement

Free surface flows are frequently encountered in hydraulic engineering problems including water jets, weirs and around gates. An iterative solution to the incompressible two-dimensional vertical steady Navier-Stokes equations, comprising momentum and continuity equations, is used to solve for the priori unknown free surface, the velocity and the pressure fields. The entire water body is covered by a unstructured finite element grid which is locally refined. The dynamic boundary condition is imposed for the free surface where the pressure vanishes. This procedure is done continuously until the normal velocities components vanish. To overcome numerical errors and oscillations encountering in convection terms, the SUPG (streamline upwinding Petrov-Galerkin) method is applied. The solution method is tested for different discharges onto a standard spillway geometries. The results shows good agreement with available experimental data.

scholarly journals Two-Dimensional Modelling of a Quayside Floating System

2020 ◽  
Vol 8 (11) ◽  
pp. 903
Author(s):  
Sixtine Neuvéglise ◽  
Gaële Perret ◽  
Hassan Smaoui ◽  
François Marin ◽  
Philippe Sergent
Keyword(s):  
Stokes Equations ◽  
Numerical Models ◽  
Navier Stokes ◽  
Intermediate Water ◽  
Navier Stokes Equations ◽  
Quadratic Drag ◽  
Floating System ◽  
Physical Tests ◽  
Comparison Of The Results ◽  
The Impact

This paper studies the behaviour of a quayside floater oscillating in front of a vertical dike. In order to study the floater motion and the impact of the dike on the floater, a linear analytical model based on 2D potential flow theory in intermediate water depth conditions and a numerical model resolving 2D Navier–Stokes equations are developed. Physical tests performed for different floater dimensions in a wave tank are used as references for the analytical and numerical models. The comparison of the results obtained analytically, numerically and experimentally leads to the validity domain of the potential model. A correction of this model is proposed, based on the optimization of the radiated coefficients, and a quadratic drag term is added according to Morison equation. The impact of the different parameters of the system on floater behaviour is considered. Results show that the draft has the most important impact on floater motion.

The Research on Numerical Simulation of the Centrifugal Pump and Configuration Perfected

2013 ◽  
Vol 694-697 ◽  
pp. 56-60
Author(s):  
Yue Jun Ma ◽  
Ji Tao Zhao ◽  
Yu Min Yang
Keyword(s):  
Numerical Simulation ◽  
Centrifugal Pump ◽  
Unstructured Grid ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Internal Flow ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Flow Phenomena ◽  
Simplec Algorithm

In the paper, on the basis of three-dimensional Reynolds-averaged Navier-Stokes equations and the RNG κ-ε turbulence model, adopting Three-dimensional unstructured grid and pressure connection the implicit correction SIMPLEC algorithm, and using MRF model which is supported by Fluent, this paper carries out numerical simulation of the internal flow of the centrifugal pump in different operation points. According to the results of numerical simulation, this paper analyzes the bad flow phenomena of the centrifugal pump, and puts forward suggests about configuration perfected of the centrifugal pump. In addition, this paper is also predicted the experimental value of the centrifugal pump performance, which is corresponding well with the measured value.

Aerodynamic Origin of Rotor-Rotor Interaction Noise From Unducted Propulsors

2013 ◽  
Author(s):  
Florian Danner ◽  
Christofer Kendall-Torry ◽  
Hans-Peter Kau
Keyword(s):  
Stokes Equations ◽  
Navier Stokes ◽  
Propagation Characteristics ◽  
Propulsion Systems ◽  
Navier Stokes Equations ◽  
Pressure Distributions ◽  
Blade Row ◽  
Open Rotor ◽  
Blade Row Interaction ◽  
Insight Into

The sound arising from blade row interaction in open rotor propulsion systems is known to significantly contribute to overall noise emissions. The present paper therefore addresses the origination of rotor-rotor interaction noise from a pair of unducted counter-rotating fans. The focus is on the aerodynamic mechanisms that involve sound generation, in order to provide the physical understanding required to find noise-reducing means. Detailed insight into the underlying phenomena is provided on the basis of numerical simulations applying the unsteady Reynolds-averaged Navier-Stokes equations. The interaction mechanisms are identified by extracting the time-dependent disturbances of the flow field in the respective rotor relative frame of reference. Conclusions on the sources of interaction noise and potential noise-reducing means are drawn by evaluating polar directivities, blade surface pressure distributions and propagation characteristics.

Numerical Simulation of Flow Field Inside Reactor Upper Plenum for PWR With Code_Saturne

2017 ◽  
Author(s):  
Jiawei Liu ◽  
Puzhen Gao ◽  
Tingting Xu ◽  
Jiesheng Min ◽  
Guofei Chen
Keyword(s):  
Stokes Equations ◽  
Fluid Dynamic ◽  
Structure Design ◽  
Navier Stokes ◽  
Guide Tube ◽  
Flow Induced Vibration ◽  
Local Pressure ◽  
Pressurized Water ◽  
Local Flow ◽  
Control Rod

Flow characteristic in upper plenum has a strong influence on reactor functional margin and rod cluster control assembly (RCCA) guide tube wear. Upper plenum flow governs loops flow rate measurement via hot leg temperature which has also an influence on the reactor protection system. For RCCA guide tube wear, it appears in operation with RCCA flow-induced vibration, leading to its replacement. It is important to know the flow condition in the upper plenum, and in particular the outlet. Existing Generation III reactors have their own specialties on the design. Comparison between current technologies is a good way for better understanding on the key structure design for the upper plenum. In this paper, simplified models based on upper plenum structure of Korean advanced pressurized water reactor (PWR) and Westinghouse design AP1000 are constructed and meshed with a volume around 6 million cells to obtain a 3-dimensional global and local flow distributions inside the upper plenum and to characterize the vital flow features for reactor safety. The Navier-Stokes equations are solved with standard k-ε turbulence model by using EDF in-house open source computational fluid dynamic (CFD) software: Code_Saturne. Through calculations, pressure and velocity distributions are obtained, axial and lateral variations have been analyzed. Compared with APR1400, it can be observed that for the design of AP1000, the rotational flow entrained in the edge of upper plenum and high velocity area due to the hot leg suction effect contribute to the relatively lower local pressure, and may have an impact on the drop velocity of control rod.

Investigation and Optimisation of Boat Deployment Systems at High Seas

2006 ◽  
Author(s):  
Gu¨nther F. Clauss ◽  
Andre´ Kauffeldt
Keyword(s):  
Stokes Equations ◽  
Operation Mode ◽  
Coast Guard ◽  
Navier Stokes ◽  
Local Flow ◽  
Navier Stokes Equations ◽  
The Time Domain ◽  
Mother Ship ◽  
Relative Motions ◽  
High Seas

There is a multitude of seagoing missions such as rescue missions, coast guard and pilot duties, whose success depend on ship-deployed boats. Launching these boats from a mother ship or recovering them by special deployment systems in a broad range of environmental conditions are key operations for a successive mission. In recent years, new boat deployment systems, promising better operational availability at high sea states, have evolved beyond the traditional side-davit system with dual falls. These new systems deploy their boats via stern ramps integrated into the transom of the mother ship, for example seen at numerous rescue cruisers around the world. This paper presents two different boat deployment systems. After a short discussion of the disadvantages of side-davit systems, a new type of a stern boat deployment device, the so called Janssen Docking System [1], is introduced. This system is equipped with an articulated ramp hinged to the stern. Whereas launching operations are less critical, the recovery of boats is quite hazardous. For this operation mode structural forces on critical areas as well as the relative motions between the ramp and the small boat are systematically investigated in model tests. Based on the results of these sea keeping tests the feasibility of the system has been analysed and improvements are recommended. As a second system a floodable dock integrated into a mother ship is presented. For launching and recovering small boats at high seas the swell inside the dock and the resulting relative motions between boat and dock ship are investigated. This leads to critical flow conditions inside the harbour in terms of sloshing waves with heights up to 3 meters. The analysis of local flow phenomena inside the dock dependent on the motion of the ship in a given sea state are the basis for the development of an optimized dock shape. Therefore an existing nonlinear numerical method for unsteady viscous computation based on Volume of Fluid (VOF) methods and Reynolds Averaged Navier Stokes Equations (RANSE) is used to simulate these phenomena. The time domain calculation allows to change local dock shapes systematically for further improvements. To validate the numerical solution the calculated results are compared to sea keeping tests at model scale. The paper concludes with a perspective for the further development of the dock shape.

scholarly journals COMPARISON OF DIFFERENT METHODS FOR GENERATION AND ABSORPTION OF WATER WAVES

2019 ◽  
Vol 18 (1) ◽  
pp. 71 ◽  
Author(s):  
J. M. P. Conde
Keyword(s):  
Water Waves ◽  
Stokes Equations ◽  
Numerical Models ◽  
Experimental Studies ◽  
Wave Generation ◽  
Navier Stokes ◽  
Small Scale ◽  
Navier Stokes Equations ◽  
Wave Absorption ◽  
Water Level Rise

The knowledge of water wave characteristics (generation, propagation, transformation and breaking) is fundamental for hydrodynamic studies and the design of ocean, coastal and port structures. In addition to the small-scale experimental studies, the use of numerical models is also a very important tool in hydrodynamic studies. To have reliable numerical results a proper validation is required. The main objective of this paper is to compare different methods of wave generation and wave absorption in a numerical flume, and to find what is the most suited to simulate non-breaking regular wave propagation in a two-dimensional flume in deep water condition. The numerical simulations were made using the OpenFOAM® software package. Two solvers, waves2Foam and IHFoam/OlaFlow, the utility GroovyBC and a mesh stretching technique are compared. These numerical codes solve the transient Navier-Stokes equations and use a VoF (Volume of Fluid) method to identify the free surface. A solution dependence study with the methods of wave generation and wave absorption is presented. The results are also compared with the theoretical wave and experimental data. The results show that the different methods of generation produce waves similar to the theoretical and the experimental ones, only slightly differences were visible. The three method of wave dissipation considered produce very different results: IHFoam/OlaFlow is not able to dissipate the wave tested; the mesh stretching technique is able to dissipate the waves but produces a water level rise; the waves2Foam solver is able to dissipate properly the wave tested.

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