Parametric Studies on Gas Turbine Labyrinth Seal for the Secondary Air Flow Optimization at Cold and Hot Flow Conditions

2019 ◽  
Author(s):  
Karthick Raja K ◽  
Giridhara Babu Y ◽  
Jayakumar J S ◽  
Kishor Kumar
Keyword(s):  
Gas Turbine ◽  
Air Flow ◽  
Labyrinth Seal ◽  
Flow Conditions ◽  
Flow Optimization ◽  
Parametric Studies ◽  
Secondary Air

Coupled Simulation of the Secondary Air Flow, Heat Transfer, and Structural Deflection of a Gas Turbine Engine

2012 ◽  
Author(s):  
Guilherme Tondello ◽  
Wolodymir Boruszewski ◽  
Fernando Mengele ◽  
Marcelo Assato ◽  
Silvio Shimizu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Structural Model ◽  
Air Flow ◽  
Labyrinth Seal ◽  
Simulation Software ◽  
Thermal Loads ◽  
Labyrinth Seals ◽  
Secondary Air

In secondary air flow in gas turbines, labyrinth seals are used to control the flow to and from each cavity and to the rotor blades for cooling purposes. Those components and the final flow rate are very sensitive to gap clearance and displacement due to structural and thermal loads during operation, therefore designing those seals and knowing the resultant flow rates in each part of the circuit during the design phase is not an easy task, and tuning those gap values may bring significant increase in turbine efficiency. This paper describes the application of coupled commercial codes for secondary air flow and structural simulation for better evaluating temperature profiles and labyrinth seal behavior during operation. Flowmaster V7 was used for building a one dimensional model of the complete secondary air flow path including swirl effects and heat transfer phenomena, and ANSYS was used for building a structural model, taking into account both rotational and thermal loads. The labyrinth seals clearances, and thermal interactions between solid and fluid were coupled bi-directionally between the two simulation software. This simulation focused in the system, including the effects of each region, passage, seal and cavity in the calculations. The turbine model simulated was a VSE’s gas turbine under development, having a nominal rotation of 22600 rpm. This paper presents the numerical characteristics of each model, the details about the 1D fluid and 3D structural coupling, and the results obtained.

Experiments on Aft-Disk Cavity Ingestion in a Model 1.5-Stage Axial-Flow Turbine

2011 ◽  
Author(s):  
J. Balasubramanian ◽  
N. Junnarkar ◽  
D. W. Zhou ◽  
R. P. Roy ◽  
Y. W. Kim ◽  
...  
Keyword(s):  
Velocity Field ◽  
Fluid Velocity ◽  
Air Flow ◽  
Axial Flow ◽  
Initial Step ◽  
Labyrinth Seal ◽  
Radial Clearance ◽  
Main Stream ◽  
Flow Rates ◽  
Secondary Air

Experiments were carried out in a model 1.5-stage (vane-blade-vane) axial-flow air turbine to investigate the ingestion of main-stream air into the aft disk cavity. This cavity features rotor and stator rim seals with radial clearance and axial overlap, and an inner labyrinth seal. Results are reported for two main air flow rates, two rotor speeds, and three purge (secondary) air flow rates. The initial step at each experimental condition was the measurement of time-average static pressure distribution in the turbine stage to ensure that a nominally steady run condition had been achieved. Subsequently, tracer gas concentration and particle image velocimetry (PIV) techniques were employed to measure, respectively, the main gas ingestion into the disk cavity (rim and inner parts) and the fluid velocity field in the rim cavity. Finally, the egress trajectory of the purge air into the main-stream air was mapped in the axial-radial plane by PIV at multiple circumferential positions within one aft vane pitch. The purge air egress trajectory and velocity field are important because the interaction of this air with the main gas stream has aerodynamic, stage performance, and downstream vane/endwall heat transfer implications.

Investigation of the Prediction Correlations for the Flow Through Rotating Orifices in the Gas Turbine Secondary Air Flow System

2013 ◽  
Author(s):  
Deoras Prabhudharwadkar ◽  
Zain Dweik ◽  
A. Subramani ◽  
Murali Krishnan R.
Keyword(s):  
Gas Turbine ◽  
Discharge Coefficient ◽  
Flow System ◽  
Air Flow ◽  
Tangential Velocity ◽  
Cross Flow ◽  
Secondary System ◽  
Accurate Analysis ◽  
Secondary Air ◽  
Reliable Design

The secondary air flow system of a gas turbine cools and seals those parts of the turbine which would otherwise be exposed to the high temperatures, resulting in their life reduction or even failures. At the same time, excessive secondary air flow hinders the performance of the engine. Accurate analysis of the secondary system is therefore necessary to safeguard the reliable design of the engine and accurate life predictions. The secondary system is analyzed through the flow network analysis which comprises of chambers or cavities connected through flow passages or restrictions. There are significant number of locations where the air passes through stationary or rotating holes, e.g., the pre-swirl nozzles and the turbine blade receiver holes respectively. The accuracy of the flow prediction depends on the accuracy of the orifice discharge coefficient. This paper provides a detailed assessment of the available discharge coefficient correlations. The discharge coefficient has been found to be dependent on the geometric parameters (viz., length, inlet radius, chamfer), and the amount of cross-flow at the orifice entrance. The cross-flow may result from the relative tangential velocity between the orifice and the air or the inclination of the inlet flow with respect to the orifice axis. In this study, it was found that the discharge coefficient correlations provide similar predictions for flows without any cross-flow. However, significant deviations are seen in the predictions for the cases involving cross-flow. To identify the most accurate correlation for secondary flow application, a thorough assessment was performed using the static and the rotating test data available in the literature. In addition to the comparison using available experimental data, a CFD study was performed to independently assess the correlations. This exercise led to the identification of the most suitable correlation for our application.

Experimental Investigation on Leakage Losses and Heat Transfer in a Non Conventional Labyrinth Seal

2011 ◽  
Author(s):  
Luca Bozzi ◽  
Enrico D’Angelo ◽  
Bruno Facchini ◽  
Mirko Micio ◽  
Riccardo Da Soghe
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Gas Turbine ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Labyrinth Seal ◽  
Leakage Flow ◽  
Transfer Coefficients ◽  
Secondary Air

Different labyrinth seal configurations are used in modern heavy-duty gas turbine such as see-through stepped or honeycomb seals. The characterization of leakage flow through the seals is one of the main tasks for secondary air system designers as well as the evaluation of increase in temperature due to heat transfer and windage effects. In high temperature turbomachinery applications, knowledge of the heat transfer characteristics of flow leaking through the seals is needed in order to accurately predict seal dimensions and performance as affected by thermal expansion. This paper deals with the influence of clearance on the leakage flow and heat transfer coefficient of a contactless labyrinth seal. A scaled-up planar model of the seal mounted in the inner shrouded vane of the Ansaldo AE94.3A gas turbine has been experimentally investigated. Five clearances were tested using a stationary test rig. The experiments covered a range of Reynolds numbers between 5000 and 40000 and pressure ratios between 1 and 3.3. Local heat transfer coefficients were calculated using a transient technique. It is shown that the clearance/pitch ratio has a significant effect upon both leakage loss and heat transfer coefficient. Hodkinson’s and Vermes’ models are used to fit experimental mass flow rate and pressure drop data. This approach shows a good agreement with experimental data.

Effect of Air-Curtains on Labyrinth Seal Performance

2016 ◽  
Author(s):  
Aakash C. Rai ◽  
Deoras Prabhudharwadkar ◽  
Sunil Murthy ◽  
Andrew Giametta ◽  
David Johns
Keyword(s):  
Gas Turbines ◽  
Cross Flow ◽  
Labyrinth Seal ◽  
Labyrinth Seals ◽  
Air Curtain ◽  
Baseline Design ◽  
Leakage Flows ◽  
Seal Design ◽  
Parametric Studies ◽  
Secondary Air

Labyrinth seals are used in many key sealing locations in gas turbines to control various leakage flows, e.g., to control the secondary air-flow from the compressor (bypassing the combustor), the turbine inter-stage leakages and blade tip leakages. This study was performed to assess the improvement in the performance of a labyrinth seal by using an air-curtain (cross-flow jet(s)) from the stator. Detailed parametric studies were performed to study the effect of the air-curtain jet pressure, location, and the number of jets on the seal performance with respect to the leakage flow. The analysis was done using 2-dimensional axisymmetric CFD simulations. It was found that in the case of a labyrinth seal with a flat stator (without a honeycomb attached to the stator) the air-curtain design can reduce the seal leakage by about 30% over the baseline seal design without air-curtains. This reduction happened because the air-curtain jet deflected the main seal jet away from the seal clearance. A similar conclusion was also obtained in case of a labyrinth seal with a honeycombed stator. Furthermore, our parametric studies with different air-curtain designs parameters implemented over a honeycombed labyrinth seal showed that the air-curtain jet pressure, location, and the number of jets were crucial factors governing the seal leakage. Amongst the air-curtain designs studied, it was found that implementing three air-curtains in the 1st pocket gave the maximum leakage reduction (by about 50%) over the baseline design.

Lung-Diaphragm Behavior of the Respiratory System During Input From Excitation

2002 ◽  
Author(s):  
P. Ruby Mawasha ◽  
Paul Lam ◽  
Lalitha Kasturi
Keyword(s):  
Mathematical Model ◽  
Respiratory System ◽  
Periodic Motion ◽  
Constitutive Relations ◽  
Air Flow ◽  
Flow Conditions ◽  
Mouth Pressure ◽  
Parametric Studies ◽  
The Mathematical Model ◽  
Operating Regimes

A numerical behavior of a lung-diaphragm model of a respiratory system during input from mouth pressure and diaphragm excitation is being investigated. A lung-diaphragm is subject to constant inlet air-flow conditions into the respiratory system. The mouth pressure (Macia et. al., 1997) and diaphragm excitation (Ricci et. al., 2002) are described by a constitutive relations containing nonlinearities from rib cage muscles forces and inlet air-flow conditions. Within certain operating regimes, the model exhibits self-excited pulsatile periodic motion and the qualitative features of the response can be understood in terms of the underlying model. Further, the mathematical model is a more general approach and can be used to conduct parametric studies and determine the instability mechanisms involved in the modeling of lung-diaphragm behavior of the respiratory system during input from excitation.

Labyrinth Seal Analysis

1972 ◽  
Vol 94 (1) ◽  
pp. 5-11
Author(s):  
H. A. Koenig ◽  
W. W. Bowley
Keyword(s):  
Gas Turbine ◽  
Theoretical Consideration ◽  
Computer Code ◽  
Labyrinth Seal ◽  
Design Parameters ◽  
Flow Conditions ◽  
Labyrinth Seals ◽  
Seal Design ◽  
Theoretical Considerations ◽  
Actual Test

A computer code is developed herein which is shown to be a useful tool in the design of labyrinth seals for gas turbine and other engineering applications. The algorithm is based upon theoretical considerations and is general enough to provide seal design parameters for a variety of input and flow conditions. Two examples are solved. The first, a theoretical consideration, demonstrates the ability of the program to effectively treat various geometrical and dynamic conditions. The second, an actual test, demonstrates the accuracy with which the analysis will predict the actual seal leakage behavior.

The Behavior of Gas Turbine Combustion Chambers While Burning Different Fuels

1960 ◽  
Author(s):  
C. Kind
Keyword(s):  
Gas Turbine ◽  
Air Flow ◽  
Flow Conditions ◽  
Combustion Chambers ◽  
Primary Condition ◽  
Full Benefit ◽  
Gas Turbine Combustion

In order to gain full benefit from the versatility of the gas turbine it is desirable for combustion chambers to be designed which can burn widely different fuels without modification. Large single combustion chambers with vortex mixing appear to be very suitable. A primary condition for this is that the input of fuel should be appropriately adapted to the air-flow conditions on which the design is based.

Pressure Driven Temperature Field in a Combustion Chamber

2004 ◽  
Author(s):  
Fernando Z. Sierra ◽  
Janusz Kubiak ◽  
Gustavo Urquiza
Keyword(s):  
Temperature Field ◽  
Combustion Chamber ◽  
Gas Turbine ◽  
Numerical Computation ◽  
High Temperatures ◽  
Characteristic Temperature ◽  
Air Flow ◽  
Combined Cycle ◽  
Auxiliary Equipment ◽  
Secondary Air

In this work numerical computation has been applied to investigate the temperature field in a gas turbine combustion chamber. The simulation considered pressure imbalance conditions of air flow between primary and secondary inlets. The combustion chamber under study is part of a 70 MW gas turbine from an operating combined cycle power plant. The combustion was simulated with proper fuel-air flow rate assuming stoichiometric conditions. Characteristic temperature and pressure fields were obtained under constant boundary conditions of air inlet. However, with pressure distribution imbalances of the order of 3 kPa between primary and secondary air inlets, excessive heating in regions other than the combustion chamber core were obtained. Over heating in these regions helped to explain what was observed to produce permanent damage to auxiliary equipment surrounding the combustion chamber core, like the cross flame pipes. It is observed that high temperatures which normally develop in the central region of the combustion chamber may reach other surrounding upstream regions by modifying slightly the air pressure. Scanning microscope examination of the damaged material confirmed that it was exposed to high temperatures such as predicted through the numerical computation.

Parametric Studies on Gas Turbine Labyrinth Seal for the Secondary Air Flow Optimization at Static and Rotating Conditions

2019 ◽  
Author(s):  
Karthick Raja Kaliraj ◽  
Giridhara Babu Yepuri ◽  
Jayakumar Janardanan Sarasamma ◽  
Kishor Kumar ◽  
Felix Jesuraj
Keyword(s):  
Experimental Data ◽  
Numerical Data ◽  
Labyrinth Seal ◽  
Leakage Flow ◽  
Stationary Condition ◽  
Cfd Analysis ◽  
Labyrinth Seals ◽  
Sst Turbulence Model ◽  
Parametric Studies ◽  
Secondary Air

Abstract Various studies have been carried out related to the labyrinth seals and reported in the open literature using the different seal arrangements at the stator-rotor seal cavity region. In the present study, numerical analysis has been carried out for the static and rotational effects of labyrinth seals at various flow and geometrical, parametric conditions for the optimized leak flow using straight and steeped seal configurations. And, an experimental data has been generated for the straight through seals, and the numerical data of the same case is validated with the experimental data. The k-omega SST turbulence model is considered with 5% turbulence intensity for the CFD analysis. At a particular seal clearance, as the number of teeth increases the leakage flow is found to be decreased. The leak flow is found to be lower with the stepped labyrinth seals in comparison to the straight through seals. The leak flow amount is found to be lower at a rotational condition in comparison to the stationary condition. From the overall results, it is observed that the stepped seal with a lower clearance at a compressor bleed air temperature and rotational conditions have shown better performance with the lower leak air mass flow.

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