Experimental Investigation and Mathematical Modelling of Clearance Brush Seals

1997 ◽  
Author(s):  
Mike T. Turner ◽  
John W. Chew ◽  
Chris A. Long
Keyword(s):  
Radial Pressure ◽  
Cfd Analysis ◽  
Axial Pressure ◽  
Pressure Distributions ◽  
Experimental Programme ◽  
Linear Resistance ◽  
Brush Seal ◽  
Flow Through ◽  
Definition Of ◽  
Resistance Coefficients

In this paper an experimental programme and a CFD based mathematical model using a brush seal at two bristle to rotor clearances (0,27 mm. and 0,75 mm.), are presented. The experimental programme examined the radial pressure distributions along the backing ring, the axial pressure distribution along the rotor, and the mass flow through the seal, through a range of pressure ratios while exhausting to atmosphere. The results from this experimental programme have been used to further calibrate a CFD based model. This model treats the bristle pack as an axisymmetric, anisotropic porous region, and is calibrated by the definition of non-linear resistance coefficients in three orthogonal directions. The CFD analysis calculates the aerodynamic forces on the bristles, which are subsequently used in a separate program to estimate the bristle movements, stresses and bristle and rotor loads. The analysis shows that a brush seal with a build clearance produces a very different flow field within the bristle pack to one with an interference, and the need to understand the bulk movements of the bristles. These are shown to be affected by the level of friction between the bristles and the backing ring, which has an important effect on the bristles wear and seal leakage characteristics.

Experimental Investigation and Mathematical Modeling of Clearance Brush Seals

1998 ◽  
Vol 120 (3) ◽  
pp. 573-579 ◽  
Author(s):  
M. T. Turner ◽  
J. W. Chew ◽  
C. A. Long
Keyword(s):  
Radial Pressure ◽  
Experimental Program ◽  
Cfd Analysis ◽  
Axial Pressure ◽  
Pressure Distributions ◽  
Brush Seal ◽  
Flow Through ◽  
Definition Of ◽  
Resistance Coefficients ◽  
Nonlinear Resistance

In this paper, an experimental program and a CFD based mathematical model using a brush seal at two bristle to rotor clearances (0.27 mm and 0.75 mm) are presented. The experimental program examined the radial pressure distributions along the backing ring, the axial pressure distribution along the rotor, and the mass flow through the seal through a range of pressure ratios while exhausting to atmosphere. The results from this experimental program have been used to further calibrate a CFD-based model. This model treats the bristle pack as an axisymmetric, anisotropic porous region, and is calibrated by the definition of nonlinear resistance coefficients in three orthogonal directions. The CFD analysis calculates the aerodynamic forces on the bristles, which are subsequently used in a separate program to estimate the bristle movements, stresses, and bristle and rotor loads. The analysis shows that a brush seal with a build clearance produces a very different flow field within the bristle pack to one with an interference, and the need to understand the bulk movements of the bristles. These are shown to be affected by the level of friction between the bristles and the backing ring, which has an important effect on the bristles wear and seal leakage characteristics.

Pressure Distributions Below Brush Seals at Varying Operating Conditions

2018 ◽  
Author(s):  
Fabian Schur ◽  
Jens Friedrichs ◽  
Johan Flegler ◽  
Christos Georgakis ◽  
Thomas Polklas
Keyword(s):  
Radial Pressure ◽  
Operating Conditions ◽  
Optical Measurements ◽  
Design Parameters ◽  
Test Rig ◽  
Axial Pressure ◽  
Backing Plate ◽  
Pressure Distributions ◽  
Flow Through ◽  
Brush Seals

The influences of different manufacturing methods and design parameters of brush seals and their complex interactions with the flow through the bristle pack complicate the modeling of the flow through brush seals. While radial pressure distributions along the backing plate and the leakage behaviour of various brush seal designs are published, experimental data on axial pressure distributions on the surface of the shaft is insufficient. In order to gain a better understanding of the phenomena associated with the flow through brush seals, the axial pressure distributions in the sealing gap below six different brush seals are measured on a cold air test rig at rotational speeds up to 3000rpm and pressure differences across the seals up to 500kPa with an axial resolution of 0.2mm. By investigating a welded and five different clamped brush seals, the influence of two different designs on the flow through the bristles is shown. For the clamped brush seals the design of the front and backing plate is varied. Moreover, the effects of bristle diameter and three different axial inclinations of the bristle pack on the axial pressure distribution are presented. Therefore, the effects of the major design aspects on axial pressure distributions at the interface between brush seals and rotor are examined and the results are supported by optical measurements taken on the rotating and a stationary test rig.

scholarly journals Two stage ejector as a pre-stage of the water ring vacuum pump

2019 ◽  
Vol 20 (7) ◽  
pp. 703
Author(s):  
Róbert Olšiak ◽  
Marek Mlkvik ◽  
František Ridzoň ◽  
Pavol Slovák
Keyword(s):  
Experimental Studies ◽  
Vacuum Pump ◽  
3D Printer ◽  
Cfd Analysis ◽  
Suction Pressure ◽  
Governing Equations ◽  
Flow Through ◽  
Definition Of ◽  
Water Ring ◽  
Liquid Ring

A supersonic gas ejector in conjunction with a liquid ring vacuum pump is used for creating and maintaining a vacuum in a chamber for technological purposes. In this paper, the authors submit an overview of the problematics of suction pressure reduction with a supersonic gas ejector used as a pre-stage of a liquid ring vacuum pump. This system has also the function of a cavitation protection due to the higher pressure present at the suction throat of the vacuum pump. A part of this paper is devoted to the governing equations used at the definition of the flow through an ejector. The CFD analysis of the problem was implemented with the package Fluent in 2 dimensions using the axisymmetric approach. The parts of the physical model were printed on a STRATASYS 3D printer, or were cast from technical resin. The experimental studies are then carried out in our own laboratory for validation purposes.

The Computation of Transonic Flow Through Two-Dimensional Gas Turbine Cascades

1971 ◽  
Author(s):  
P. W. McDonald
Keyword(s):  
Flow Field ◽  
Gas Turbine ◽  
Transonic Flow ◽  
Equations Of Motion ◽  
Two Dimensional ◽  
Airfoil Surface ◽  
Pressure Distributions ◽  
Flow Through ◽  
Turbine Cascades ◽  
Definition Of

Steady transonic flow through two-dimensional gas turbine cascades is efficiently predicted using a time-dependent formulation of the equations of motion. An integral representation of the equations has been used in which subsonic and supersonic regions of the flow field receive identical treatment. Mild shock structures are permitted to develop naturally without prior knowledge of their exact strength or position. Although the solutions yield a complete definition of the flow field, the primary aim is to produce airfoil surface pressure distributions for the design of aerodynamically efficient turbine blade contours. In order to demonstrate the accuracy of this method, computed airfoil pressure distributions have been compared to experimental results.

Flow Resistance Coefficients of Porous Brush Seal As a Function of Pressure Load

2017 ◽  
Author(s):  
Yahya Doğu ◽  
Mustafa C. Sertçakan ◽  
Koray Gezer ◽  
Mustafa Kocagül
Keyword(s):  
Pressure Distribution ◽  
Flow Resistance ◽  
Radial Pressure ◽  
Blow Down ◽  
Static Test ◽  
Backing Plate ◽  
Pressure Load ◽  
Brush Seal ◽  
Brush Seals ◽  
Resistance Coefficients

Developments in brush seal analyses tools have been covering advanced flow and structural analyses since brush seals are applied at elevated pressure loads, temperatures, surface speeds, and transients. Brush seals have dynamic flow and structural behaviors that need to be investigated in detail in order to estimate final leakage output and service life. Bristles move, bend and form a grift matrix depending on pressure load. The level of pressure load determines the tightness of the bristle pack, and thus, the leakage. In the CFD analyses of this work, the bristle pack is treated as a porous medium. Based on brush seal test data, the flow resistance coefficients (FRC) for the porous bristle pack are calibrated as a function of pressure load. A circular seal is tested in a static test rig under various pressure loads at room temperature. The FRC calibration is based on test leakage and literature based axial pressure distribution on the rotor surface and radial pressure distribution over the backing plate. The anisotropic FRC are treated as spatial dependent in axi-symmetrical coordinates. The fence height region and the upper region of bristle pack have different FRC since the upper region is supported by backing plate while bristles are free to move and bend at the fence height region. The FRC are found to be almost linearly dependent on the pressure load for investigated conditions. The blow-down is also calculated by incorporating test leakage and calibrated FRC.

scholarly journals Simulation-based Study of Graphene-water Nanofluid flow through Microchannel Heatsink

2021 ◽  
Vol 1206 (1) ◽  
pp. 012008
Author(s):  
Ritwik Bhattacharya ◽  
Pranab Samanta
Keyword(s):  
Rectangular Cross Section ◽  
Constant Heat Flux ◽  
Cfd Analysis ◽  
Nanofluid Flow ◽  
Constant Heat ◽  
Ansys Fluent ◽  
Pressure Distributions ◽  
Simulation Based ◽  
Flow Through ◽  
Temperature And Pressure

Abstract This study presents a CFD analysis of the laminar flow of graphene-water nanofluid through a Silicon microchannel heatsink using commercial software ANSYS FLUENT. The microchannel has a rectangular cross-section of given dimensions, and the base of the heatsink is subjected to a constant heat flux. Simulations of the coolant flow are performed at different fluid inlet velocities for nanoparticle concentrations of 0%, 3% and 6% in the base fluid-Water. Results for temperature and pressure distributions in the microchannel heatsink are presented. The cooling performance of the MCHS improves significantly by increasing the flow velocity and enhancing the nanoparticle concentration in the coolant.

Flow Resistance Coefficients of Porous Brush Seal as a Function of Pressure Load

2018 ◽  
Vol 140 (8) ◽  
Author(s):  
Yahya Doğu ◽  
Mustafa C. Sertçakan ◽  
Koray Gezer ◽  
Mustafa Kocagül
Keyword(s):  
Pressure Distribution ◽  
Flow Resistance ◽  
Radial Pressure ◽  
Blow Down ◽  
Static Test ◽  
Backing Plate ◽  
Pressure Load ◽  
Brush Seal ◽  
Brush Seals ◽  
Resistance Coefficients

Developments in brush seal analyses tools have been covering advanced flow and structural analyses since brush seals are applied at elevated pressure loads, temperatures, surface speeds, and transients. Brush seals have dynamic flow and structural behaviors that need to be investigated in detail in order to estimate final leakage output and service life. Bristles move, bend, and form a grift matrix depending on pressure load. The level of pressure load determines the tightness of the bristle pack, and thus, the leakage. In the computational fluid dynamics (CFD) analyses of this work, the bristle pack is treated as a porous medium. Based on brush seal test data, the flow resistance coefficients (FRC) for the porous bristle pack are calibrated as a function of pressure load. A circular seal is tested in a static test rig under various pressure loads at room temperature. The FRC calibration is based on test leakage and literature-based axial pressure distribution on the rotor surface and radial pressure distribution over the backing plate. The anisotropic FRC are treated as spatial dependent in axisymmetrical coordinates. The fence height region and the upper region of bristle pack have different FRC since the upper region is supported by backing plate, while bristles are free to move and bend at the fence height region. The FRC are found to be almost linearly dependent on the pressure load for investigated conditions. The blow-down is also calculated by incorporating test leakage and calibrated FRC.

scholarly journals Flow Visualization in a Simulated Brush Seal

1990 ◽  
Author(s):  
M. J. Braun ◽  
R. C. Hendricks ◽  
V. Canacci
Keyword(s):  
Flow Visualization ◽  
Flow Fields ◽  
Inlet Pressure ◽  
Complex Flow ◽  
Axial Pressure ◽  
Interface Motion ◽  
Pressure Profiles ◽  
Brush Seal ◽  
Brush Seals

A method to visualize and characterize the complex flow fields in simulated brush seals is presented. The brush seal configuration was tested in a water and then in an oil tunnel. The visualization procedure revealed typical regions that are rivering, jetting, vortical or lateral flows and exist upstream, downstream or within the seal. Such flows are engendered by variations in fiber void that are spatial and temporal and affect changes in seal leakage and stability. While the effects of interface motion for linear or cylindrical configurations have not been considered herein, it is believed that the observed flow fields characterize flow phenomenology in both circular and linear brush seals. The axial pressure profiles upstream, across and downstream of the brush in the oil tunnel have been measured under a variety of inlet pressure conditions and the ensuing pressure maps are presented and discussed.

Instability Modes of Two-Phase Flows in a Mixing-Layer Microdevice

2001 ◽  
Author(s):  
Tak For Yu ◽  
Sylvanus Yuk Kwan Lee ◽  
Yitshak Zohar ◽  
Man Wong
Keyword(s):  
Gas Flow ◽  
Mixing Layer ◽  
Fluid Flows ◽  
Two Phase Flows ◽  
Two Phase ◽  
Pressure Distributions ◽  
Instability Modes ◽  
In Series ◽  
Mass Flow Rates ◽  
Flow Through

Abstract Extensive development of biomedical and chemical analytic microdevices involves microscale fluid flows. Merging of fluid streams is expected to be a key feature in such devices. An integrated microsystem consisting of merging microchannels and distributed pressure microsensors has been designed and characterized to study this phenomenon on a microscale. The two narrow, uniform and identical channels merged smoothly into a wide, straight and uniform channel downstream of a splitter plate. All of the devices were fabricated using standard micromachining techniques. Mass flow rates and pressure distributions were measured for single-phase gas flow in order to characterize the device. The experimental results indicated that the flow developed when both inlets were connected together to the gas source could be modeled as gas flow through a straight and uniform microchannel. The flow through a single branch while the other was blocked, however, could be modeled as gas flow through a pair of microchannels in series. Flow visualizations of two-phase flows have been conducted when driving liquid and gas through the inlet channels. Several instability modes of the gas/liquid interface have been observed as a function of the pressure difference between the two streams at the merging location.

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