scholarly journals Effects of Front Plate Geometry on Brush Seal in Highly Swirling Environments of Gas Turbine

Energies ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7768
Author(s):  
Yuxin Liu ◽  
Benzhuang Yue ◽  
Xiaozhi Kong ◽  
Hua Chen ◽  
Huawei Lu
Keyword(s):  
Gas Turbine ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Swirl Flow ◽  
Seal Failure ◽  
Plane Front ◽  
Brush Seal ◽  
Front Plate ◽  
The Impact ◽  
Plate Geometry

Advanced brush seal technology has a significant impact on the performance and efficiency of gas turbine engines. However, in highly inlet swirling environments, the bristles of a brush seal tend to circumferentially slip, which may lead to aerodynamic instability and seal failure. In this paper, seven different front plate geometries were proposed to reduce the impact of high inlet swirl on the bristle pack, and a three-dimensional porous medium model was carried out to simulate the brush seal flow characteristics. Comparisons of a plane front plate with a relief cavity, plane front plate with axial drilled holes, anti-“L”-type plate and their relative improved configurations on the pressure and flow fields as well as the leakage behavior were conducted. The results show that the holed front plate can effectively regulate and control the upstream flow pattern of the bristle pack, inducing the swirl flow to move radially inward, which results in decreased circumferential velocity component. The anti-“L” plate with both axial holes and one radial hole was observed to have the best effect on reducing the swirl of those investigated. The swirl velocity upstream the bristle pack can decline 50% compared to the baseline model with plane front plate, and the circumferential aerodynamic forces on the bristles, which scale with the swirl dynamic head, are reduced by a factor of 4. This could increase the bristle stability dramatically. Moreover, the front plate geometry does not influence the leakage performance significantly, and the application of the axial hole on the front plate will increase the leakage slightly by around 3.5%.

The Impact of Gas Modeling in the Numerical Analysis of a Multistage Gas Turbine

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Filippo Rubechini ◽  
Michele Marconcini ◽  
Andrea Arnone ◽  
Massimiliano Maritano ◽  
Stefano Cecchi
Keyword(s):  
Gas Turbine ◽  
Flow Direction ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Ratio Distribution ◽  
Real Gas ◽  
Turbine Performance ◽  
Wall Boundary Conditions ◽  
Heavy Duty Gas Turbine ◽  
The Impact

In this work a numerical investigation of a four stage heavy-duty gas turbine is presented. Fully three-dimensional, multistage, Navier-Stokes analyses are carried out to predict the overall turbine performance. Coolant injections, cavity purge flows, and leakage flows are included in the turbine modeling by means of suitable wall boundary conditions. The main objective is the evaluation of the impact of gas modeling on the prediction of the stage and turbine performance parameters. To this end, four different gas models were used: three models are based on the perfect gas assumption with different values of constant cp, and the fourth is a real gas model which accounts for thermodynamic gas properties variations with temperature and mean fuel∕air ratio distribution in the through-flow direction. For the real gas computations, a numerical model is used which is based on the use of gas property tables, and exploits a local fitting of gas data to compute thermodynamic properties. Experimental measurements are available for comparison purposes in terms of static pressure values at the inlet∕outlet of each row and total temperature at the turbine exit.

Breaking the Swirl With Brush Seals: Numerical Modeling and Experimental Evidence

2008 ◽  
Author(s):  
Peter Helm ◽  
Alexander Pugachev ◽  
Matthias Neef
Keyword(s):  
Experimental Evidence ◽  
Swirl Flow ◽  
Operating Conditions ◽  
Brush Seal ◽  
Stable Operating ◽  
Beneficial Impact ◽  
Rotor Surface ◽  
Brush Seals ◽  
Experimental Values ◽  
The Impact

Striving for smaller losses in turbomachinery has led to many advancements in the design of seals. Modern sealing concepts such as brush seals hold a great potential to increase the efficiency of both flight engines and stationary turbines. At the same time, in order to maintain stable operating conditions of the rotor, swirl-induced forces must be kept at a minimum in the sealing channels. Therefore, the influence of the permeable and flexible bristle pack of brush seals on the flow around the rotor surface must be known. In this paper the swirl flow in the cavities of two different seal geometries is studied experimentally and numerically. A conventional three-tooth labyrinth serves as a reference. A second seal arrangement with a bristle pack upstream of two teeth is compared with the reference labyrinth. The swirl is evaluated experimentally from total and static pressure measurements in various axial and circumferential positions. Additionally, the axial swirl distribution is calculated using computational fluid dynamics (CFD). Here, the numerical model of the brush seal is based on the porous medium approach and is calibrated using the experimental values of the leakage and the bristle clearance by adjusting the thickness of the bristle pack. The calibrated CFD model is then used to study the impact of the brush seal on the swirl component of the sealing flow. The observed significant decrease of the swirl by the brush seal shows good agreement with the experimental data. The impact of changes in bristle pack clearance on the swirl is also investigated and compared with experimental evidence. The aim is to show that the brush seals have a natural tendency to interrupt seal swirl. They can therefore be used for swirl control in order to create a beneficial impact on the dynamic stability of turbomachines.

Numerical Investigation of Positive Displacement Rotary Lobe Pump With Twisted Rotors

2014 ◽  
Author(s):  
Xiaojun Jiang ◽  
Yi Li ◽  
Zhaohui He ◽  
Cui Baoling ◽  
Wenlong Dong
Keyword(s):  
Flow Structure ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Dynamic Flow ◽  
Flow Fluctuation ◽  
Flow Field Characteristics ◽  
Lobe Pump ◽  
The Impact

The three-dimensional flow field characteristics are obtained by performing numerical simulation of flow in a lobe pump with twisted rotors. The relationship between the dynamic flow structure and the flow fluctuation is explored. Actually, the viscous incompressible Navier-Stokes equations are solved within an unsteady flow model. The dynamic mesh technique is applied to obtain the dynamic flow structure. By comparing the simulated results of straight rotor with those of twisted rotor, the effect of rotor shape on the flow fluctuation was revealed. Finally, the impact of the lobes number of rotors on flow pulsations is discussed. The results show that there is an intrinsic relationship between the flow fluctuation and the vortex in the lobe pump. The use of twisted rotors can effectively improve the internal flow characteristics of lobe pump and reduce flow fluctuation. With the increase of the number of lobes, the lobe pump output is more stable and capacity has been improved.

Effects of Geometry on Brush Seal Pressure and Flow Fields—Part I: Front Plate Configurations

2005 ◽  
Vol 128 (2) ◽  
pp. 367-378 ◽  
Author(s):  
Yahya Dogu ◽  
Mahmut F. Aksit
Keyword(s):  
Flow Field ◽  
Radial Flow ◽  
Flow Fields ◽  
Protective Role ◽  
Blow Down ◽  
Geometric Configurations ◽  
Brush Seal ◽  
Front Plate ◽  
Field Formation ◽  
Plate Geometry

Pressure and flow fields lay at the basis of such common phenomena affecting brush seal performance as bristle flutter, blow-down, hang-up, hysteresis, pressure stiffening, wear, and leakage. Over the past two decades of brush seal evolution, manufacturers and researchers have applied many geometric configurations to the front and backing plates of a standard brush seal in order to control the flow field and consequent seal performance. The number of studies evaluating the effect of geometric configurations on the brush seal flow field remains limited in spite of the high number of filed patent disclosures. This study presents a numerical analysis of brush seal pressure and flow fields with regard to common conceptual front plate configurations. A CFD model has been employed to calculate pressure and flow fields in the seal domain. The model incorporates a bulk porous medium approach for the bristle pack. The effectiveness of various conceptual geometries has been outlined in terms of flow field formation. Results disclose unique effects of geometry on pressure and flow fields such that a longer front plate drives outward radial flow while playing a protective role against upstream cavity disturbances. Findings also indicate that variations in front plate geometry do not directly affect leakage performance. A long front plate or damper shim considerably changes the flow field while at the same time having limited effect on the pressure field. Moreover, a strong suction towards the clearance enhances inward radial flow in clearance operation.

Experimental and Numerical Investigations on Leakage Flow Characteristics of Two Kinds of Brush Seals

2018 ◽  
Author(s):  
Yuanqiao Zhang ◽  
Jun Li ◽  
Xin Yan ◽  
Zhigang Li
Keyword(s):  
Three Dimensional ◽  
Flow Characteristics ◽  
Navier Stokes ◽  
Blow Down ◽  
Brush Seal ◽  
Leakage Coefficient ◽  
Computational Fluid Dynamics Cfd ◽  
Brush Seals ◽  
Deflector Plate ◽  
Hysteresis Characteristics

The leakage characteristics of interference and clearance brush seals were experimentally measured and numerically simulated in this paper. The leakage coefficients of the brush seals without a deflector plate at different pressure differentials were firstly measured. The effect of deflector plate and clearance on seal performance and the detailed flow field of the brush seal were numerically investigated using three-dimensional Reynolds-Averaged Navier-Stokes (RANS) solutions coupled with a Non-Darcian Porous Medium model. In addition, this study experimentally investigated the hysteresis characteristic of interference and clearance brush seals without deflector plates, and presented detailed investigations on the blow down effect of clearance brush seal using Computational Fluid Dynamics (CFD) as mentioned above and Finite Element Method (FEM) approaches. The obtained results show that the leakage coefficient and blow-down effect of the brush seal with a deflector plate is lower than that of the brush seal without a deflector plate at the same pressure difference and the clearance between the bristle pack and shaft will increase the leakage coefficient significantly. The different hysteresis characteristics of interference and clearance brush seals are illustrated and discussed.

Confinement Effects on Flow Dynamics in Swirling Flames

2005 ◽  
Author(s):  
S. Archer ◽  
A. K. Gupta
Keyword(s):  
Gas Turbine ◽  
Recirculation Zone ◽  
Direct Injection ◽  
Model Development ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Flow Dynamics ◽  
Swirl Number ◽  
Outer Flow ◽  
Lean Direct Injection

Three-dimensional (3-D) flowfield data has been obtained using Particle Image Velocimetry (PIV) for varying swirl distributions in the burner. The 3-D data also allows one determine the local swirl number of the resulting flow. Flow characteristics of the resulting flowfield, both without and with combustion, have been examined for the effect of co- and counter-swirl under lean direct injection conditions using unconfined and confined combustor geometry. Experimental results of the effect of swirl and combustion are presented to simulate the flow dynamics of Lean Direct Injection (LDI) configuration gas turbine combustion. The selected configuration is typical because it does not make use a premixing zone and relies totally on the swirl and the injector to accomplish rapid mixing. Specifically, the effect of radial distribution of combustion air and swirl in a burner are examined under non-burning and burning conditions using propane as the fuel. The present study explores single swirler interaction with the use of an experimental double concentric swirl burner that simulates one swirler of a practical gas turbine combustor. Results showed that both swirl and combustion has significant effect on the characteristics of the internal and external recirculation zones. The calculated local swirl number differs significantly form that estimated using geometrical relationship derived from the vane angle only. The effect of combustion for the confined and unconfined geometries was also been found to be different. In the confined geometry combustion decreases the size of the recirculation zone. This is in contrast to that found for the unconfined conditions. Combustion enhances the recirculation zone in the unconfined geometry. Combustion provides greater velocity magnitudes than their counter non-combustion conditions. The counter-swirl combination resulted in smaller and more well defined internal recirculation regions. The results provide the role of swirl and combustion on the mean and turbulence characteristics of flows over a range of swirl and shear conditions between the inner and outer flow of the burner. This data provides important insights on the flow dynamics in addition to providing data for model validation and model development.

Effect of Pitch Chord Ratio and Side Wall Expansion Angle on Flow Through Vane Swirlers

2006 ◽  
Author(s):  
R. Thundil Karuppa Raj ◽  
V. Ganesan
Keyword(s):  
Computational Study ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Side Wall ◽  
Reynolds Stress Model ◽  
Swirl Flow ◽  
Expansion Angle ◽  
Turbulence Effects ◽  
Flow Field Characteristics ◽  
Flow Through

This paper is concerned with the computational study of steady flow through the vane swirlers. Swirl flow field characteristics for various pitch chord ratio (s/c) at swirler mean radius are studied for a 45° vane swirler under both sudden and gradual expansions with side-wall expansion angles of 90° and 45° respectively. In the computational study the geometry and meshing is done using pre-processor GAMBIT. Three-dimensional flow within the geometry and through the swirler has been simulated by solving the appropriate governing equations viz. conservation of mass and momentum using FLUENT code. Turbulence effects are taken care of by the Reynolds stress model and shear stress transport k-ω model for high swirls and standard k-ε model for low and medium swirls. The effect of pitch to chord ratio (s/c) on flow characteristics have been studied. The predicted results are validated with the experimental data available in the literature for s/c ratio of 1. The numerical results of axial velocity profiles downstream of the swirler at various axial planes are found to be in close agreement with the experimental results. It is found that the s/c ratio of 1 provides good turning efficiency.

scholarly journals Supercritical flow at an abrupt drop: flow patterns and aeration

1998 ◽  
Vol 25 (5) ◽  
pp. 956-966 ◽  
Author(s):  
H Chanson ◽  
L Toombes
Keyword(s):  
Shock Waves ◽  
Open Channel ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Flow Patterns ◽  
Three Dimensional Flow ◽  
Supercritical Flow ◽  
Drop Flow ◽  
Supercritical Flows ◽  
The Impact

Stepped waterways and cascades are common features of storm waterways, at dam outlets, and in water treatment plants. At an abrupt drop, open channel flows are characterized by the presence of shock waves and a substantial flow aeration. There is, however, little information on the basic flow characteristics. The study presents new experimental data obtained in a 0.5-m-wide stepped flume with an unventilated nappe. The investigations describe the three-dimensional flow patterns, including shock waves, standing waves, and spray, downstream of the nappe impact. The characteristics of the flow patterns are similar to those observed with abrupt expansion supercritical flows. Downstream of the drop brink, substantial aeration takes place along the nappe interfaces and the flow downstream of the impact is deaerated.Key words: abrupt drop, supercritical flow, shock waves, flow patterns, cascade.

scholarly journals The Use of Enhanced Nozzle Maps for Gas-Turbine Performance Modelling

2021 ◽  
Author(s):  
Aws A. Al-Akam ◽  
Theoklis Nikolaidis ◽  
David G. MacManus ◽  
Alvise Pellegrini
Keyword(s):  
Three Dimensional ◽  
Flow Characteristics ◽  
Engine Performance ◽  
Exhaust System ◽  
Limited Range ◽  
Performance Modelling ◽  
Essential Components ◽  
Wide Range ◽  
Aero Engine ◽  
The Impact

Abstract The use of a simulation tool to predict the aero-engine performance before committing to a final engine design has become one of the most cost-saving approaches in this field. However, most of these tools are based on low fidelity thermodynamic models, which are incapable of fully capturing the impact of three-dimensional flow characteristics. An aero-engine exhaust-system is one of the essential components that affect the engine performance. Currently, engine performance models tend to utilize simplified nozzle performance maps. These maps typically provide information over a very limited range of nozzle geometries, which may not apply to the wide range of architectures and designs of aeroengines. The current paper presents a methodology for the development of nozzle performance maps, which takes into account the aerodynamic and the geometric parameters of the nozzle design. The methodology is based on the reduced-order models. These models are integrated into a zero-dimensional engine performance code to improve the accuracy of its thrust calculation. The impact of the new thrust model on the overall engine performance and the operating point is analysed and discussed. The results showed that the implementation of the modified maps, which take into account the flow characteristics and the geometry of the nozzle, affects the thrust calculation. In a typical case of a turbofan operating at cruise conditions, the net thrust estimation with the modified nozzle maps showed a difference of 0.2%, compared with the simple nozzle maps. The new thrust calculation method has the advantage in capturing the multidimensional impact of the flow of the nozzle as compared with the conventional one. Furthermore, the implementation of the new method reduces the uncertainties introduced by a simplified nozzle model and, consequently, it can support the decision-making process in the design of the engine.

Flow Dynamics of Unconfined Swirling Flames Under Fuel-Lean Conditions

2006 ◽  
Author(s):  
S. S. Archer ◽  
A. K. Gupta ◽  
K. Kitagawa
Keyword(s):  
Direct Injection ◽  
Air Flow ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Swirl Flow ◽  
Flow Dynamics ◽  
Swirl Number ◽  
Burner Exit ◽  
Swirl Vane

This study provides the role of co- and counter swirl distribution in a experimental double concentric swirl burner that simulates the that simulates one swirl cup of a practical gas turbine combustor. Results of the effect of radial distribution of swirl in a burner under unconfined non-burning and combustion conditions are presented on the flow dynamics of a fuel-lean direct injection (LDI) configuration using propane as the fuel. Three-dimensional (3-D) flowfield data has been obtained immediately downstream of the burner exit to determine the detailed flow dynamics associated with the flow. The fuel was injected radially into the surrounding swirl flow. Flow characteristics, both without and with combustion, have been obtained for the co- and counter-swirl distributions to the combustion air flow under unconfined conditions. Flat vane swirlers have been used to induce swirl to the air flow. Both combustion and swirl distribution significantly influences the resulting flowfield. The resulting swirl number of the flow was calculated using the 3-D velocity data. Results show that swirl distribution in the burner and combustion provides significant effect on the characteristics of the internal and external recirculation zones. The heat release from combustion enhances the inner recirculation zone by increasing its width and length. Combustion causes significant increase to the velocity and vorticity magnitudes in the flow, and promotes flowfield symmetry. Combustion also affects the swirl number of the flow. The swirl number calculated from the geometrical relationships, derived from the swirl vane angle and swirler dimensions, is much different than that determined from the 3-D velocity field data. The entrained mass flow rate is larger for the co-swirl distribution case and this entrainment is further enhanced with combustion. The results provide the role of radial swirl distribution on the mean and turbulence characteristics of flows for the two different shear flow conditions between the inner and outer annulus of the burner.

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