An Investigation Into Numerical Analysis Alternatives for Predicting Re-Ingestion in Turbine Disc Rim Cavities

2012 ◽  
Author(s):  
Antonio Guijarro Valencia ◽  
Jeffrey A. Dixon ◽  
Riccardo Da Soghe ◽  
Bruno Facchini ◽  
Peter E. J. Smith ◽  
...  
Keyword(s):  
Gas Turbines ◽  
Turbulence Models ◽  
Research Programme ◽  
Paper Analysis ◽  
Main Stream ◽  
Cfd Modelling ◽  
Cooling Flow ◽  
Air Supply ◽  
Modelling Techniques ◽  
Cooling Air

Reliable means of predicting ingestion in cavities adjacent to the main gas path are increasingly being sought by engineers involved in the design of gas turbines. In this paper, analysis is to be presented that results from an extended research programme, MAGPI, sponsored by the EU and several leading gas turbine manufactures and universities. Extensive use is made of CFD modelling techniques to understand the aerodynamic behaviour of a turbine stator well cavity, focusing on the interaction of cooling air supply with the main annulus gas. The objective of the study has been to benchmark a number of CFD codes and numerical techniques covering RANS and URANS calculations with different turbulence models in order to assess the suitability of the standard settings used in the industry for calculating the mechanics of the flow travelling between cavities in a turbine through the main gas path. The modelling methods employed have been compared making use of experimental data gathered from a dedicated two-stage turbine rig, running at engine representative conditions. Extensive measurements are available for a range of flow conditions and alternative cooling arrangements. The limitations of the numerical methods in calculating the interaction of the cooling flow egress and the main stream gas, and subsequent ingestion into downstream cavities in the engine (i.e. re-ingestion), have been exposed. This has been done without losing sight of the validation of the CFD for its use for predicting heat transfer, which was the main objective of the partners of the MAGPI Work-Package 1 consortium.

Heat Transfer in Turbine Hub Cavities Adjacent to the Main Gas Path

2010 ◽  
Author(s):  
Jeffrey A. Dixon ◽  
Antonio Guijarro ◽  
Andreas Bauknecht ◽  
Daniel Coren ◽  
Nick Atkins
Keyword(s):  
Heat Transfer ◽  
Gas Turbines ◽  
Research Programme ◽  
Fe Modelling ◽  
Turbine Stator ◽  
Turbine Efficiency ◽  
Fuel Burn ◽  
Air Supply ◽  
Modelling Techniques ◽  
Cooling Air

Reliable means of predicting heat transfer in cavities adjacent to the main gas path are increasingly being sought by engineers involved in the design of gas turbines. In this paper an interim summary of the results of a four-year research programme sponsored by the EU and several leading gas turbine manufactures and universities will be presented. Extensive use is made of CFD and FE modelling techniques to understand the thermo-mechanical behaviour of a turbine stator well cavity, including the interaction of cooling air supply with the main annulus gas (see Figure 1). The objective of the study has been to provide a means of optimising the design of such cavities for maintaining a safe environment for critical parts, such as disc rims and blade fixings, whilst maximising the turbine efficiency, and minimising the fuel burn and emissions penalties associated with the secondary airflow system. The modelling methods employed have been validated against data gathered from a dedicated two-stage turbine rig, running at engine representative conditions. Extensive measurements are available for a range of flow conditions and alternative cooling arrangements. The analysis method has been used to inform a design change which is also to be tested. Comparisons are provided between the predictions and measurements of the turbine stator well component temperature.

Characterisation of Static Strip Seal Flow

2007 ◽  
Author(s):  
Arash Farahani ◽  
Peter Childs
Keyword(s):  
Gas Flow ◽  
Pressure Ratio ◽  
Flow Characteristics ◽  
Main Stream ◽  
Cfd Modelling ◽  
Height Range ◽  
And Performance ◽  
Nozzle Guide ◽  
The Cost ◽  
Cooling Air

Strip seals are used in gas turbine engines between two static elements or between components which do not move relative to each other, such as Nozzle Guide Vanes (NGVs). The key role of a strip seal between NGV segments is sealing between the flow through the main stream annulus and the internal air system, a further purpose is to limit the inter-segmental movements. In general the shape of the strip seal is a rectangular strip that fits into two slots in adjacent components. The minimum clearance required for static strip seals must be found by accounting for thermal expansion, misalignment, and application, to allow correct fitment of the strip seals. Any increase in leakage raises the cost due to an increase in the cooling air use, which is linked to specific fuel consumption, and it can also alter gas flow paths and performance. The narrow path within the seal assembly, especially the height has the most significant affect on leakage. The height range of the narrow path studied in this paper is 0.01–0.06 mm. The behaviour of the flow passing through the narrow path has been studied using CFD modelling and measurements in a bespoke rig. The CFD and experimental results show that normalized leakage flow increases with pressure ratio before reaching a maximum. The main aim of this paper is to provide new experimental data to verify the CFD modelling for static strip seals. The typical flow characteristics validated by CFD modelling and experiments can be used to predict the flow behaviour for future static strip seal designs.

Heat Transfer in Turbine Hub Cavities Adjacent to the Main Gas Path Including FE-CFD Coupled Thermal Analysis

2011 ◽  
Author(s):  
Antonio Guijarro Valencia ◽  
Jeffrey A. Dixon ◽  
Attilio Guardini ◽  
Daniel D. Coren ◽  
Daniel Eastwood
Keyword(s):  
Heat Transfer ◽  
Gas Turbines ◽  
Flow Distribution ◽  
Research Programme ◽  
Coupled Analysis ◽  
Analysis Method ◽  
Fe Modelling ◽  
Turbine Stator ◽  
Fuel Burn ◽  
Air Supply

Reliable means of predicting heat transfer in cavities adjacent to the main gas path are increasingly being sought by engineers involved in the design of gas turbines. In this paper an up-dated analysis of the interim results from an extended research programme, MAGPI, sponsored by the EU and several leading gas turbine manufactures and universities, will be presented. Extensive use is made of CFD and FE modelling techniques to understand the thermo-mechanical behaviour and convective heat transfer of a turbine stator well cavity, including the interaction of cooling air supply with the main annulus gas. It is also important to establish the hot running seal clearances for a full understanding of the cooling flow distribution and heat transfer in the cavity. The objective of the study has been to provide a means of optimising the design of such cavities (see Figure 1) for maintaining a safe environment for critical parts, such as disc rims and blade fixings, whilst maximising the turbine efficiency by means of reducing the fuel burn and emissions penalties associated with the secondary airflow system. The modelling methods employed have been validated against data gathered from a dedicated two-stage turbine rig, running at engine representative conditions. Extensive measurements are available for a range of flow conditions and alternative cooling arrangements. The analysis method has been used to inform a design change which will be tested in a second test phase. Data from this test will also be used to further benchmark the analysis method. Comparisons are provided between the predictions and measurements from the original configuration, turbine stator well component temperature survey, including the use of a coupled analysis technique between FE and CFD solutions.

Turbine Stator Well CFD Studies: Effects of Cavity Cooling Air Flow

2008 ◽  
Author(s):  
Antonio Andreini ◽  
Riccardo Da Soghe ◽  
Bruno Facchini ◽  
Stefano Zecchi
Keyword(s):  
Heat Transfer ◽  
Gas Turbines ◽  
Numerical Models ◽  
Engine Performance ◽  
Research Programme ◽  
Experimental Tests ◽  
Air Cooling ◽  
Manufacturing Companies ◽  
Secondary Air ◽  
Cooling Air

The improvement of the aerodynamic efficiency of gas turbine components is becoming more and more difficult to achieve. Nevertheless there are still some devices that could be improved to enhance engine performance. Further investigations on the internal air cooling systems, for instance, may lead to a reduction of cavities cooling air with a direct beneficial effect on engine performance. At the same time, further investigations on heat transfer mechanisms within turbine cavities may help to optimize cooling air flows saving engine life duration. This paper presents some CFD preliminary studies conducted on an two-stage axial turbine rig developed in a research programme on internal air systems funded by EU, named the Main Annulus Gas Path Interactions (MAGPI). Each turbine stage consists of 39 vanes and 78 rotating blades and the modelled domain includes both the main gas path of the two turbine stages and the second stator well. Pre experimental tests CFD computations were planned in order to point out the reliability of numerical models in the description of the flow patterns in the main annulus and in the cavities. Several computational meshes were considered with steady and unsteady approaches in order to assess the sensitivity to computational approach regarding the evaluation of the interactions between main annulus and disk cavities flows. Results were obtained for several cavities cooling air mass-flow rates and data were further analyzed to investigate the influence of the sealing flow inside the main annulus. MAGPI project is a 4 years Specific-Targeted-Research-Project (2007–2011) and its consortium includes six universities and nine gas turbines manufacturing companies. The project is focused on the analysis of interactions between primary and secondary air systems achieving a novel approach as these systems have, up to now, only been considered separately. In particular one of the tasks of the project will focus on heat transfer phenomena and delivering experimental data which will be used to validate the advanced design tools used by industries (CFD codes and correlative formulations).

scholarly journals Effects of Various Modeling Schemes on Mist Film Cooling Simulation

2005 ◽  
Author(s):  
Xianchang Li ◽  
Ting Wang
Keyword(s):  
Turbulence Intensity ◽  
Film Cooling ◽  
Turbulence Models ◽  
Cooling Effectiveness ◽  
Air Supply ◽  
Cooling Enhancement ◽  
Simulation Results ◽  
Density Ratios ◽  
Slot Film Cooling ◽  
Cooling Air

Numerical simulation is performed in this study to explore film-cooling enhancement by injecting mist into the cooling air with a focus on investigating the effect of various modeling schemes on the simulation results. The effect of turbulence models, dispersed-phase modeling, inclusion of different forces (Saffman, thermophoresis, and Brownian), trajectory tracking, and mist injection scheme is studied. The effect of flow inlet boundary conditions (with/without air supply plenum), inlet turbulence intensity, and the near-wall grid density on simulation results is also included. Using a 2-D slot film cooling simulation with a fixed blowing angle and blowing ratio shows a 2% mist injected into the cooling air can increase the cooling effectiveness about 45%. The RNG k-ε model, RSM and the standard k-ε turbulence model with the enhanced wall treatment produce consistent and reasonable results while the turbulence dispersion has a significant effect on mist film cooling through the stochastic trajectory calculation. The thermophoretic force slightly increases the cooling effectiveness, but the effect of Brownian force and Saffman lift is imperceptible. The cooling performance is affected negatively by the plenum in this study, which alters the velocity profile and turbulence intensity at the jet exit plane. The results of this paper can serve as the qualification reference for future more complicated studies including 3-D cooling holes, different blowing ratios, various density ratios, and rotational effect.

Turbine Stator Well CFD Studies: Effects of Coolant Supply Geometry on Cavity Sealing Performance

2009 ◽  
Author(s):  
Antonio Andreini ◽  
Riccardo Da Soghe ◽  
Bruno Facchini
Keyword(s):  
Research Programme ◽  
Air Cooling ◽  
Sector Model ◽  
Engine Efficiency ◽  
Air Supply ◽  
Sealing Performance ◽  
Aero Engines ◽  
Set Up ◽  
Cooling Air

The increase of aero engines performance through the improvement of aerodynamic efficiency of main annulus flow is becoming more and more difficult to achieve. However there are still some devices that could be improved to enhance global engine efficiency. Particularly, investigations on the internal air cooling systems, may lead to a reduction of cooling air with a direct benefit to the overall performance. At the same time, further investigations on heat transfer mechanisms within turbine cavities may help to optimize cooling air flows saving engine life duration. This paper presents a CFD study aimed at the characterization of the effects of different geometries for cooling air supply within turbine cavities on wall thermal effectiveness and sealing mass flow rate. Several sealing air supply geometries were considered in order to point out the role of cooling air injection position, swirl number and jet penetration on the cavities sealing performance. The study was set up on a two-stage axial turbine rig developed in a research programme on internal air systems funded by EU (Main Annulus Gas Path Interactions - MAGPI). Steady state calculations were performed using two different computational domains: the first consists in a sector model of the whole turbine including the second stator well, while the second is a cut-down model of the stator well. Thanks to the simplified geometry of the test rig with respect to actual engines, the study has pointed out clear design suggestions regarding the effects of geometry modification of cooling air supply system.

ICAS-GT: A European Collaborative Research Programme on Internal Cooling Air Systems for Gas Turbines

2002 ◽  
Author(s):  
Peter D. Smout ◽  
John W. Chew ◽  
Peter R. N. Childs
Keyword(s):  
Heat Transfer ◽  
Gas Turbines ◽  
Research Programme ◽  
Cavity Flow ◽  
Internal Cooling ◽  
Manufacturing Companies ◽  
Flow And Heat Transfer ◽  
Rotating Cavity ◽  
Internal Fluid Flow ◽  
Cooling Air

The Internal Cooling Air Systems for Gas Turbines (ICAS-GT) research programme, sponsored by the European Commission, ran from January 1998 to December 2000, and was undertaken by a consortium of ten gas turbine manufacturing companies and four universities. Research was concentrated in five discrete but related areas of the air system including turbine rim seals, rotating cavity flow and heat transfer, and turbine pre-swirl system effectiveness. In each case, experiments were conducted to extend the database of pressure, temperature, flow and heat transfer measurements to engine representative non-dimensional conditions. The data was used to develop correlations, and to validate CFD and FE calculation methods, for internal fluid flow and heat transfer. This paper summarises the outcome of the project by presenting a sample of experimental results from each technical work package. Examples of the associated CFD calculations are included to illustrate the progress made in developing validated tools for predicting rotating cavity flow and heat transfer over an engine representative range of flow conditions.

Investigation of Internal Cooling Air Flow of Gas Turbines With Attention to Heat Transfer

2003 ◽  
Author(s):  
D. Brillert ◽  
F.-K. Benra ◽  
H. J. Dohmen ◽  
O. Schneider
Keyword(s):  
Heat Transfer ◽  
Gas Turbines ◽  
Turbine Blades ◽  
Internal Cooling ◽  
Flow Physics ◽  
Cooling Flow ◽  
Air System ◽  
Secondary Air ◽  
Cooling Air ◽  
Material Temperature

The cooling air in the secondary air system of gas turbines is routed through the inside of the rotor shaft. The air enters the rotor through an internal extraction in the compressor section and flows through different components to the turbine blades. Constant improvements of the secondary air system is a basic element to increase efficiency and power of heavy duty gas turbines. It is becoming more and more important to have a precise calculation of the heat transfer and air temperature in the internal cooling air system. This influences the cooling behavior, the material temperature and consequently the cooling efficiency. The material temperature influences the stresses and the creep behavior which is important for the life time prediction and the reliability of the components of the engine. Furthermore, the material temperature influences the clearances and again the cooling flow, e.g. the amount of mass flow rate, hot gas ingestion etc. This paper deals with an investigation of the influence of heat transfer on the internal cooling air system and on the material temperature. It shows a comparison between numerical calculations with and without heat transfer. Firstly, the Navier-Stokes CFD calculation shows the cooling flow physics of different parts of the secondary air system passages with solid heat transfer. In the second approach, the study is expanded to consider the cooling flow physics under conditions without heat transfer. On the basis of these investigations, the paper shows a comparison between the flow with and without heat transfer. The results of the simulation with heat transfer show a negligible influence on the cooling flow temperature and a stronger influence on the material temperature. The results of the calculations are compared with measured data. The influence on the material temperature is verified with measured material temperatures from a Siemens Model V84.3A gas turbine prototype.

Internal Air Systems Experimental Rig Best Practice

2006 ◽  
Author(s):  
Peter Childs ◽  
Klaus Dullenkopf ◽  
Dieter Bohn
Keyword(s):  
Gas Turbines ◽  
High Speed ◽  
Best Practice ◽  
Research Programme ◽  
Internal Cooling ◽  
Manufacturing Companies ◽  
Compressor Rotor ◽  
Wide Range ◽  
Cooling Air ◽  
Experimental Rig

This paper reports best practice principles for experimental rig design and operation arising from a European Commision funded programme of research on internal air systems. The Internal Cooling Air Systems for Gas Turbines 2 (ICAS-GT2) research programme, ran from April 2001 to June 2005, and was undertaken by a consortium of ten gas turbine manufacturing companies and four universities. The programme of research involved both design and operation of a series of high pressure, high speed rotating rigs in order to deliver data at or near engine representative conditions. The rigs concerned cover the pre-swirl system, turbine rim seals, turbine stator wells, compressor rotor-rotor disc cavities, bolt windage and real engine parts experiments. Operation of these rigs has presented a wide range of challenges, particularly with respect to optical access in rotor-rotor and rotor-stator disc cavities and measurement of disc heat transfer. This paper explores the best practice principles developed for internal air system experimental rig design, operation and associated instrumentation.

scholarly journals Effects of Various Modeling Schemes on Mist Film Cooling Simulation

2007 ◽  
Vol 129 (4) ◽  
pp. 472-482 ◽  
Author(s):  
Xianchang Li ◽  
Ting Wang
Keyword(s):  
Turbulence Intensity ◽  
Film Cooling ◽  
Turbulence Models ◽  
Reynolds Stress Model ◽  
Cooling Effectiveness ◽  
Air Supply ◽  
Cooling Enhancement ◽  
Simulation Results ◽  
Density Ratios ◽  
Cooling Air

Numerical simulation is performed in this study to explore film-cooling enhancement by injecting mist into the cooling air with a focus on investigating the effect of various modeling schemes on simulation results. The effect of turbulence models, dispersed-phase modeling, inclusion of different forces (Saffman, thermophoresis, and Brownian), trajectory tracking, and mist injection scheme is studied. The effect of flow inlet boundary conditions (with/without air supply plenum), inlet turbulence intensity, and the near-wall grid density on simulation results is also included. Simulation of a two-dimensional (2D) slot film cooling with a fixed blowing angle and blowing ratio shows a 2% mist (by mass) injected into the cooling air can increase the cooling effectiveness about 45%. The renormalization group (RNG) k-ε model, Reynolds stress model, and the standard k-ε turbulence model with an enhanced wall treatment produce consistent and reasonable results while the turbulence dispersion has a significant effect on mist film cooling through the stochastic trajectory calculation. The thermophoretic force slightly increases the cooling effectiveness, but the effect of Brownian force and Saffman lift is imperceptible. The cooling performance deteriorates when the plenum is included in the calculation due to the altered velocity profile and turbulence intensity at the jet exit plane. The results of this paper can provide guidance for corresponding experiments and serve as the qualification reference for future more complicated studies with 3D cooling holes, different blowing ratios, various density ratios, and rotational effect.

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