Brush Seal Temperature Distribution Analysis

2005 ◽  
Vol 128 (3) ◽  
pp. 599-609 ◽  
Author(s):  
Yahya Dogu ◽  
Mahmut F. Aksit
Keyword(s):  
Heat Flux ◽  
Temperature Distribution ◽  
Heat Generation ◽  
Operating Conditions ◽  
Frictional Heat ◽  
Distribution Analysis ◽  
Cfd Analysis ◽  
Oxidation Rates ◽  
Frictional Heat Generation ◽  
Brush Seal

Brush seals are designed to survive transient rotor rubs. Inherent brush seal flexibility reduces frictional heat generation. However, high surface speeds combined with thin rotor sections may result in local hot spots. Considering large surface area and accelerated oxidation rates, frictional heat at bristle tips is another major concern especially in challenging high-temperature applications. This study investigates temperature distribution in a brush seal as a function of frictional heat generation at bristle tips. The two-dimensional axisymmetric computational fluid dynamics (CFD) analysis includes the permeable bristle pack as a porous medium allowing fluid flow throughout the bristle matrix. In addition to effective flow resistance coefficients, isotropic effective thermal conductivity as a function of temperature is defined for the bristle pack. Employing a fin approach for a single bristle, a theoretical analysis has been developed after outlining the brush seal heat transfer mechanism. Theoretical and CFD analysis results are compared. To ensure coverage for various seal designs and operating conditions, several frictional heat input cases corresponding to different seal stiffness values have been studied. Frictional heat generation is outlined to introduce a practical heat flux input into the analysis model. Effect of seal stiffness on nominal bristle tip temperature has been evaluated. Analyses show a steep temperature rise close to bristle tips that diminishes further away. Heat flux conducted through the bristles dissipates into the flow by a strong convection at the fence-height region.

Brush Seal Temperature Distribution Analysis

2005 ◽  
Author(s):  
Yahya Dogu ◽  
Mahmut F. Aksit
Keyword(s):  
Heat Flux ◽  
Temperature Distribution ◽  
Heat Generation ◽  
Operating Conditions ◽  
Frictional Heat ◽  
Distribution Analysis ◽  
Cfd Analysis ◽  
Oxidation Rates ◽  
Frictional Heat Generation ◽  
Brush Seal

Brush seals are designed to survive transient rotor rubs. Inherent brush seal flexibility reduces frictional heat generation. However, high surface speeds combined with thin rotor sections may result in local hot spots. Considering large surface area and accelerated oxidation rates, frictional heat at bristles tips is another major concern especially in challenging high temperature applications. This study investigates temperature distribution in a brush seal as a function of frictional heat generation at bristle tips. The two-dimensional axisymmetric CFD analysis includes the permeable bristle pack as a porous medium allowing fluid flow throughout the bristle matrix. In addition to effective flow resistance coefficients, isotropic effective thermal conductivity as a function of temperature is defined for the bristle pack. Employing a fin approach for a single bristle, a theoretical analysis has been developed after outlining the brush seal heat transfer mechanism. Theoretical and CFD analysis results are compared. To ensure coverage for various seal designs and operating conditions, several frictional heat input cases corresponding to different seal stiffness have been studied. Frictional heat generation is outlined to introduce a practical heat flux input into the analysis model. Effect of seal stiffness on nominal bristle tip temperature has been evaluated. Analyses show a steep temperature rise close to bristle tips that diminishes further away. Heat flux conducted through the bristles dissipates into the flow by a strong convection at fence height region.

Investigation of Conjugate Heat Transfer in Brush Seals Using Porous Media Approach Under Local Thermal Non-Equilibrium Conditions

2015 ◽  
Author(s):  
Bo Qiu ◽  
Jun Li ◽  
Zhenping Feng
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Heat Generation ◽  
Frictional Force ◽  
Conjugate Heat Transfer ◽  
Frictional Heat ◽  
Equilibrium Conditions ◽  
Frictional Heat Generation ◽  
Brush Seal ◽  
Brush Seals

As a type of contacting seal technology, brush seals provide superior sealing performance and flexible behavior. Brush seals have found increasing application in more challenging high-temperature locations in recent years. Thus, the frictional heat generation between the seal bristles and mating surfaces is becoming another major concern for stable operation of brush seals. This study presents detailed investigations on the conjugate heat transfer behavior of brush seals using Computational Fluid Dynamics (CFD) and Finite Element Method (FEM) approaches. A dual-energy equation was proposed to describe the conjugate heat transfer in the porous bristle pack region under local thermal non-equilibrium conditions. The heat transfer CFD model was established with consideration of anisotropic thermal conductivity and a radius-dependent porosity of the bristle pack. The frictional heat generation was calculated from the product of the bristle-rotor frictional force and sliding velocity. The bristle-rotor frictional force was obtained from the brush seal FEM model with consideration of internal friction and aerodynamic load on the bristles. The temperature distribution of the brush seal was predicted at various operational conditions using the iterative CFD and FEM brush seal model. The effects of pressure ratios and rotational speeds on the temperature distribution and bristle maximum temperature of the brush seal were investigated based on the developed numerical approach. The effect of frictional heat generation on brush seal leakage was also analyzed.

An Investigation of Heat Generation Characteristics of Brush Seals

2007 ◽  
Author(s):  
Mehmet Demiroglu ◽  
John A. Tichy
Keyword(s):  
Contact Force ◽  
Heat Generation ◽  
Operating Conditions ◽  
Frictional Heat ◽  
Design Parameters ◽  
Frictional Heat Generation ◽  
Operation Conditions ◽  
Seal Design ◽  
Wide Range ◽  
Brush Seals

Brush seals are considered as a category of compliant seals, which tolerate a great high level of interference between the seal and the rotor or shaft. Their superior leakage characteristics have opened many application fields in the turbo-machinery world, ranging from industrial steam turbines to jet engines. However, brush seal designers have to find a trade-off between the lower parasitic leakage but higher heat generation properties of brush seals for given operation conditions. As brush seals can maintain contact with the rotor for a wide range of operating conditions, the contact force/pressure generated at the seal-rotor interface becomes an important design parameter for sustained seal performance and longevity of its service life. Furthermore, due to this contact force at the interface, frictional heat generation is inevitable and must be evaluated for various design and operating conditions. In this paper, frictional heat generation at the sealrotor interface is studied. To capture temperature rise at the interface, a thermal image of the seal and rotor is taken with an infrared camera under various operating conditions. The temperature map of the rotor is compared to results from thermal finite element analysis of the rotor to back calculate the heat flux to the rotor. A closed form equation for frictional heat generation is suggested as a function of seal design parameters, material properties, friction coefficient and empirical factors from testing.

Brush Seal Frictional Heat Generation: Test Rig Design and Validation Under Steam Environment

2016 ◽  
Author(s):  
M. Raben ◽  
J. Friedrichs ◽  
J. Flegler
Keyword(s):  
Steam Turbine ◽  
Heat Generation ◽  
Gas Turbines ◽  
Frictional Heat ◽  
Narrow Gap ◽  
Test Rig ◽  
Frictional Heat Generation ◽  
Brush Seal ◽  
Rotor Surface ◽  
Brush Seals

Sealing technology is a key feature to improve efficiency of steam turbines for both new power stations and modernization projects. One of the most powerful sealing alternatives for reducing parasitic leakages in the blade path of a turbine as well as in shaft sealing areas is the use of brush seals, which are also widely used in gas turbines and turbo compressors. The advantage of brush seals over other sealing concepts is based on the narrow gap that is formed between the brush seal bristle tips and the mating rotor surface together with its radial adaptivity. While the narrow gap between the bristle tips and the rotor leads to a strongly decreased flow through the seal compared with conventional turbomachinery seals, it is important to be aware of the tight gap that can be bridged by relative motion between the rotor and the brush seal, leading to a contact of the bristles and the rotor surface. Besides abrasive wear occurrence, the friction between the bristles and the rotor leads to heat generation which can be detrimental to turbine operation due to thermal effects, leading to rotor bending connected to increasing shaft vibrations. In order to investigate the frictional heat generation of brush seals, different investigation concepts have been introduced through the past years. To broaden the knowledge about frictional heat generation and to make it applicable for steam turbine applications, a new testing setup was designed for the steam test rig of the Institute of Jet Propulsion and Turbomachinery - TU Braunschweig, Germany, enabling temperature measurements in the rotor body under stationary and transient operation in steam by using rotor-integrated thermocouples. Within this paper, the development of the instrumented new rotor design and all relevant parts of the new testing setup is shown along with the testing ability by means of the validation of the test rig concept and the achieved measurement accuracy. First results prove that the new system can be used to investigate frictional heat generation of brush seals under conditions relevant for steam turbine shaft seals.

Effect of frictional heat generation on the temperature distribution in roller linear motion rail surface

2017 ◽  
Vol 31 (3) ◽  
pp. 1477-1487 ◽  
Author(s):  
De-Jun Cheng ◽  
Je-Hong Park ◽  
Jeong-Se Suh ◽  
Su-Jin Kim ◽  
Chun-Hong Park
Keyword(s):  
Temperature Distribution ◽  
Heat Generation ◽  
Frictional Heat ◽  
Linear Motion ◽  
Frictional Heat Generation

Numerical Investigations on the Heat Transfer Behavior of Brush Seals Using Combined Computational Fluid Dynamics and Finite Element Method

2013 ◽  
Vol 135 (12) ◽  
Author(s):  
Bo Qiu ◽  
Jun Li
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Finite Element Method ◽  
Computational Fluid Dynamics ◽  
Finite Element ◽  
Heat Generation ◽  
Frictional Heat ◽  
Frictional Heat Generation ◽  
Brush Seal ◽  
Brush Seals

Brush seals have been applied in more and more challenging high-temperature locations. The high speed bristle-rotor friction causes a considerable heat generation which accelerates the bristles wear. The frictional heat generation at bristle-rotor interface becomes another major concern in brush seal applications. This study presented detailed investigations on the heat transfer characteristics and contact mechanics of brush seals using a combined computational fluid dynamics (CFD) and finite element method (FEM) brush seal model. The CFD model of brush seal for mass and heat transfer employed Reynolds-averaged Navier–Stokes (RANS) solutions coupled with non-Darcian porous medium approach. The nonlinear contact model of brush seal was established using FEM with considerations of internal frictions (bristle to rotor, bristle to backing plate, and bristle to bristle) and aerodynamic loads on bristles. The numerical method involved iterations between CFD and FEM models to better evaluate the heat transfer behaviors of the brush seal with consideration of bristle deflections. The frictional heat generation was calculated from the product of bristle-rotor frictional force and sliding velocity. The bristle deflections and temperature distributions of the brush seal were predicted at various operational conditions using the iterative CFD and FEM brush seal model. The effects of pressure differential and rotational speed on the contact behavior, temperature distribution and bristle maximum temperature of brush seals were numerically investigated using the developed approach. The detailed pressure contours and streamline distributions of the brush seal were also illustrated.

Brush Seal Frictional Heat Generation—Test Rig Design and Validation Under Steam Environment

2016 ◽  
Vol 139 (3) ◽  
Author(s):  
Markus Raben ◽  
Jens Friedrichs ◽  
Johan Flegler
Keyword(s):  
Steam Turbine ◽  
Heat Generation ◽  
Gas Turbines ◽  
Frictional Heat ◽  
Narrow Gap ◽  
Test Rig ◽  
Frictional Heat Generation ◽  
Brush Seal ◽  
Rotor Surface ◽  
Brush Seals

Sealing technology is a key feature to improve efficiency of steam turbines for both new power stations and modernization projects. One of the most powerful sealing alternatives for reducing parasitic leakages in the blade path of a turbine as well as in shaft sealing areas is the use of brush seals, which are also widely used in gas turbines and turbo compressors. The advantage of brush seals over other sealing concepts is based on the narrow gap that is formed between the brush seal bristle tips and the mating rotor surface together with its radial adaptivity. While the narrow gap between the bristle tips and the rotor leads to a strongly decreased flow through the seal compared with conventional turbomachinery seals, it is important to be aware of the tight gap that can be bridged by relative motion between the rotor and the brush seal, leading to a contact of the bristles and the rotor surface. Besides abrasive wear occurrence, the friction between the bristles and the rotor leads to heat generation which can be detrimental to turbine operation due to thermal effects, leading to rotor bending connected to increasing shaft vibrations. In order to investigate the frictional heat generation of brush seals, different investigation concepts have been introduced through the past years. To broaden the knowledge about frictional heat generation and to make it applicable for steam turbine applications, a new testing setup was designed for the steam test rig of the Institute of Jet Propulsion and Turbomachinery—TU Braunschweig, Germany, enabling temperature measurements in the rotor body under stationary and transient operation in steam by using rotor-integrated thermocouples. Within this paper, the development of the instrumented new rotor design and all relevant parts of the new testing setup is shown along with the testing ability by means of the validation of the test rig concept and the achieved measurement accuracy. First results prove that the new system can be used to investigate frictional heat generation of brush seals under conditions relevant for steam turbine shaft seals.

Finite element method estimation of temperature distribution of automotive tire using one-way-coupled method

2021 ◽  
pp. 095440702110087
Author(s):  
Zumrat Usmanova ◽  
Emin Sunbuloglu
Keyword(s):  
Thermal Analysis ◽  
Temperature Distribution ◽  
Heat Generation ◽  
Complex Geometry ◽  
Rolling Resistance ◽  
Operating Conditions ◽  
Deformation Analysis ◽  
Coupled Method ◽  
Experimental Values ◽  
Hysteretic Loss

Numerical simulation of automotive tires is still a challenging problem due to their complex geometry and structures, as well as the non-uniform loading and operating conditions. Hysteretic loss and rolling resistance are the most crucial features of tire design for engineers. A decoupled numerical model was proposed to predict hysteretic loss and temperature distribution in a tire, however temperature dependent material properties being utilized only during the heat generation analysis stage. Cyclic change of strain energy values was extracted from 3-D deformation analysis, which was further used in a thermal analysis as input to predict temperature distribution and thermal heat generation due to hysteretic loss. This method was compared with the decoupled model where temperature dependence was ignored in both deformation and thermal analysis stages. Deformation analysis results were compared with experimental data available. The proposed method of numerical modeling was quite accurate and results were found to be close to the actual tire behavior. It was shown that one-way-coupled method provides rolling resistance and peak temperature values that are in agreement with experimental values as well.

scholarly journals Brush seal with thermo-regulating bimetal elements

2018 ◽  
Vol 8 (1) ◽  
pp. 307-313 ◽  
Author(s):  
Michał Stanclik
Keyword(s):  
Heat Flux ◽  
Contact Area ◽  
Heat Load ◽  
Experimental Results ◽  
Frictional Heat ◽  
Brush Seal ◽  
Thermoregulatory Function ◽  
Shaft Surface

Abstract This paper presents a new brush seal construction idea. It was shown that it is possible to use bimetallic elements for the construction of the brush seal, which have a thermoregulatory function by relieving a contact area between bristles and a shaft surface reducing frictional heat flux. This should improve the durability of the seal by diminishing the heat load and significantly decreases the temperature of the seal during the startup/ shutdown. This article shows a simplified construction of the concept brush seal as well as numerical and experimental results.

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