Secondary Air Systems in Aeroengines Employing Vortex Reducers

2001 ◽  
Author(s):  
Dimitrie Negulescu ◽  
Michael Pfitzner
Keyword(s):  
Flow Path ◽  
Supporting Evidence ◽  
Excessive Pressure ◽  
Pressure Losses ◽  
Low Pressure Turbine ◽  
Hot Gas ◽  
Air System ◽  
High Integrity ◽  
Secondary Air ◽  
Aero Engines

A secondary air system in modern aero engines is required to cool the compressor and turbine discs and make sure that no hot gas ingestion occurs into the cavities between the turbine discs, which could cause an inadvertent reduction of disc life. A high integrity solution for guiding the air from the compressor to the turbine is through an inner bleed from the compressor platform and through the space between the disc bores and the shaft connecting the fan with the low pressure turbine. Since strongly swirling air is taken from the compressor platforms to a much lower radius, a means of deswirling the air has to be used to avoid excessive pressure losses along the flow path. The paper describes a system utilizing tubeless vortex reducers to accomplish this deswirl, which are compared to a more conventional air system utilizing tubes. The working principles of both types of vortex reducer and guidelines for the design of a secondary air system using vortex reducers are explained with supporting evidence from rig tests and CFD calculations. Opportunities for the aerodynamic optimisation of the tubeless vortex reducer are elaborated and the experience gained using the system during the development of the BR700 engine is described.

Probabilistic Analysis of the Secondary Air System of a Low-Pressure Turbine

2014 ◽  
Author(s):  
Stefan Brack ◽  
Yannick Muller
Keyword(s):  
Correlation Coefficient ◽  
Probabilistic Analysis ◽  
Flow Model ◽  
Turbine Rotor ◽  
Effect Analysis ◽  
Low Pressure Turbine ◽  
Hot Gas ◽  
Air System ◽  
Secondary Air ◽  
The Impact

The present investigation aims at performing a probabilistic analysis of the secondary air system of a three-stage low-pressure turbine rotor in a jet engine. Geometrical engine to engine variations due to the tolerance of the different parts as well as the variation of engine performance parameters are taken into account to analyse the impact on the aerodynamic behaviour of the secondary air system. Three main functions of the secondary air system have been investigated at one engine condition — take-off. At first the variation of the turbine rotor cooling flow consumption was studied. Secondly the axial bearing loads were considered and finally the system was analysed with regard to its robustness towards disc space hot gas ingestion. To determine the uncertainty in the accomplishment of these tasks and to identify the major variation drivers, a Latin Hypercube sampling method coupled with the correlation coefficient analysis was applied to the 1D flow model. The incapability of the correlation coefficient analysis to deal with functional relationships of not monotonic behaviour or strong interaction effects was compensated by additionally applying in such cases an Elementary Effect analysis to determine the influential variables. As the 1D flow model cannot consider thermal and centrifugal growth effects, a simple mathematical model was deduced from the physical dependencies enhancing the 1D flow model to approximately capture the impact of these effects on the labyrinth seals. Results showed that the cooling mass flow and axial bearing load are both normally distributed while their uncertainties are mainly induced by the uncertainties of the state variable of the primary air system. The investigated chamber temperature ratio to analyse the hot gas ingestion showed a not normally distributed histogram and a strong influence of interaction terms. Therefore the results of the correlation coefficient analysis were complemented with the results of an Elementary Effect analysis.

Probabilistic Analysis of the Secondary Air System of a Low-Pressure Turbine

2014 ◽  
Vol 137 (2) ◽  
Author(s):  
Stefan Brack ◽  
Yannick Muller
Keyword(s):  
Correlation Coefficient ◽  
Probabilistic Analysis ◽  
Flow Model ◽  
Turbine Rotor ◽  
Effect Analysis ◽  
Low Pressure Turbine ◽  
Hot Gas ◽  
Air System ◽  
Secondary Air ◽  
The Impact

The present investigation aims at performing a probabilistic analysis of the secondary air system (SAS) of a three-stage low-pressure turbine rotor in a jet engine. Geometrical engine to engine variations due to the tolerance of the different parts as well as the variation of engine performance parameters are taken into account to analyze the impact on the aerodynamic behavior of the SAS. Three main functions of the SAS have been investigated at one engine condition—takeoff. At first the variation of the turbine rotor cooling flow consumption was studied. Second, the axial bearing loads were considered and finally the system was analyzed with regard to its robustness toward disk space hot gas ingestion. To determine the uncertainty in the accomplishment of these tasks and to identify the major variation drivers, a Latin hypercube sampling (LHS) method coupled with the correlation coefficient analysis was applied to the 1D flow model. The incapability of the correlation coefficient analysis to deal with functional relationships of not monotonic behavior or strong interaction effects was compensated by additionally applying in such cases an elementary effect analysis to determine the influential variables. As the 1D flow model cannot consider thermal and centrifugal growth effects, a simple mathematical model was deduced from the physical dependencies enhancing the 1D flow model to approximately capture the impact of these effects on the labyrinth seals. Results showed that the cooling mass flow and axial bearing load are both normally distributed while their uncertainties are mainly induced by the uncertainties of the state variable of the primary air system. The investigated chamber temperature ratio to analyze the hot gas ingestion showed a not normally distributed histogram and a strong influence of interaction terms. Therefore, the results of the correlation coefficient analysis were complemented with the results of an elementary effect analysis.

Robust Design Optimization of a Low Pressure Turbine Rotor Discs Secondary Air System

2017 ◽  
Author(s):  
Giulia Antinori ◽  
Ilya Arsenyev ◽  
Andreas Fischersworring-Bunk
Keyword(s):  
Parameter Space ◽  
Cooling System ◽  
Optimization Methods ◽  
Low Pressure ◽  
Life Cycles ◽  
Robust Design Optimization ◽  
Design Parameters ◽  
Low Pressure Turbine ◽  
Air System ◽  
Secondary Air

Low pressure turbine (LPT) rotor discs undergo high thermal and mechanical loads during normal aircraft missions. Therefore, to meet the minimum requirement for life, temperatures and stresses in the disk need to be maintained within certain limits. This is achieved by carefully designing the disk shape and the cooling system. The complexity of this multi-physics problem together with a large number of design parameters require the use of numerical optimization methods for the Secondary Air System (SAS) design. Moreover, possible variations in the boundary conditions due to ambient parameters (e.g. temperatures, pressures) and manufacturing tolerances of the SAS components should be taken into account within the system design and optimization phase. In this paper an application of robust optimization methods for the design of a LPT secondary air system is proposed. The objective is to increase the engine efficiency by minimizing the amount of cooling flow, which is needed to guarantee a minimum required number of life cycles and to keep maximal temperatures within the limits. In order to predict the disks life accurately, transient thermal-structural analysis is used, which is computationally demanding. For this reason, optimization should be performed with a very limited amount of system evaluations. The dimension of the parameter space is reduced through the application of global sensitivity analysis methods by selecting the parameters that most affect the results. Optimization methods are sped up by the use of surrogate models, created over the reduced parameter space, which approximate the objective function and the constraints.

Separation of Particles in the Secondary Air System of Gas Turbines

2011 ◽  
Author(s):  
Natalia Garci´a Vi´llora ◽  
Klaus Dullenkopf ◽  
Hans-Jo¨rg Bauer
Keyword(s):  
Film Cooling ◽  
Gas Turbines ◽  
Separation Efficiency ◽  
Cooling System ◽  
Turbine Blades ◽  
Spherical Particles ◽  
Experimental Investigations ◽  
Air System ◽  
Secondary Air ◽  
Aero Engines

Particles contaminating the secondary air system of land based gas turbines or aero-engines can cause serious problems in various engine components, particularly in the cooling system. The capability of the pre-swirl system in separating particles will be described in this paper. So far, only a few publications can be found on experimental investigations on this subject. The work presented in this paper attempts to give a contribution to fill this gap and thus represents a further step towards a better understanding of the behaviour of solid contaminants in the secondary air system. Due to the strong swirl in the pre-swirl cavity, the aero-dynamical forces can be used to separate particles, thus preventing depositions inside the turbine blades or even block-age of the film cooling holes. Numerous experiments in a pre-swirl system have been performed using spherical particles and non-spherical particles. As reference cases, three types of spheres, with two size ranges and different materials, were used to understand how size and density influence the separation efficiency. For further experiments, irregularly-shaped particles, more similar to the ones found in real aero-engines, were used too. The separation efficiency was investigated at different pre-swirl nozzle pressure ratios, rotational speeds and radial mass flows. The results are presented in relation to the particle Reynolds numbers, drag coefficients, Stokes numbers and swirl ratios in the pre-swirl cavity.

Secondary Air System Model for Integrated Thermomechanical Analysis of a Jet Engine

2008 ◽  
Author(s):  
Yannick Muller
Keyword(s):  
Coupling Effect ◽  
Thermomechanical Analysis ◽  
Mechanical Analysis ◽  
Analysis Tool ◽  
Thermomechanical Model ◽  
Jet Engine ◽  
Pressure Losses ◽  
Finite Element Software ◽  
Air System ◽  
Secondary Air

As temperatures in jet engine combustion chamber and turbine increase, the relevance of heat transfer between structure and secondary airflow is increasing. Secondary air properties greatly influence material temperatures, which control the thermal expansion of engine parts. Redefining tip clearances and seal gaps, this modifies considerably pressure losses and mass flow rates in the air system, impacting flow and material temperatures. The coupling effect, estimated strong, must be accurately addressed to obtain an optimized secondary air system design. The aerodynamic calculations yielding mass flows and pressures, and thermal analysis providing temperatures and the material expansion are performed separately. In reality, there are interactions currently not considered which would require a lot of time-consuming iterations. The present investigation aims at taking this mutual interaction into consideration in a robust and modular analysis tool, combining secondary air system, thermal and mechanical analysis. For air system calculations, a network representation with nodes, chambers, connected by pressure loss devices is used. This network is coupled with a thermomechanical model of the engine secondary air system in the free finite element software CalculiX® [1]. This paper presents the first module implemented in CalculiX®, dedicated to solve typical Secondary Air System problems and gives an insight on the implementation of the coupling process currently under development.

Development, Numerical Investigation and Experimental Validation of a New Recuperator Design for Aero Engines Applications

2017 ◽  
Author(s):  
Zinon Vlahostergios ◽  
Dimitrios Misirlis ◽  
Michael Flouros ◽  
Christina Salpingidou ◽  
Stefan Donnerhack ◽  
...  
Keyword(s):  
Fuel Consumption ◽  
Waste Heat ◽  
External Pressure ◽  
Pollutant Emissions ◽  
Pressure Losses ◽  
Low Pressure Turbine ◽  
Heat Exchanger Design ◽  
Aero Engine ◽  
Pollutants Emission ◽  
Aero Engines

Targeting the development of more efficient aero engine designs, various concepts have been considered through the previous years, among which is the Intercooled Recuperative Aero engine (IRA) concept. In the IRA concept a system of heat exchangers is mounted in the hot-gas exhaust nozzle, downstream of the low-pressure turbine focusing on the exploitation of the waste heat exhaust gasses for preheating the compressor discharge air just before the latter enters the combustion chamber, resulting in fuel consumption and pollutants emission reduction. In the present work a new heat exchanger design for use as a recuperator is proposed for possible implementation in the IRA engine, based on an annular configuration design which is more easily integrated in an aero engine. The new recuperator external pressure losses are computationally and experimentally investigated for laboratory conditions, providing very good agreement. Additionally, the pressure losses just before the recuperator were further minimized by introducing riblet films inside the exhaust conical nozzle. The optimized recuperator characteristics were included in a thermodynamic analysis of the IRA engine and it was shown that considerable improvement in fuel consumption and pollutant emissions reduction could be achieved.

Experimental Study on Pressure Losses in Circular Orifices With Inlet Cross Flow

2017 ◽  
Author(s):  
Daniel Feseker ◽  
Mats Kinell ◽  
Matthias Neef
Keyword(s):  
Experimental Study ◽  
Film Cooling ◽  
Gas Turbines ◽  
Discharge Coefficient ◽  
Pressure Ratio ◽  
Cross Flow ◽  
Pressure Losses ◽  
Wide Range ◽  
Air System ◽  
Secondary Air

The cooling air in the secondary air system of gas turbines is controlled and metered by numerous restrictors, mainly in the shape of orifices. The ability to understand and predict the associated pressure losses are important in order to improve the air flow in the secondary air system. This experimental study investigates the behavior of the discharge coefficient for circular orifices with inlet cross flow which is a common flow case in gas turbines. Examples of this are at the inlet of a film cooling hole or the feeding of air to a blade through an orifice in a rotor disc. Measurements were conducted for a total number of 38 orifices, covering a wide range of length-to-diameter ratios, including short and long orifices with varying inlet geometries. Up to five different chamfer-to-diameter and radius-to-diameter ratios were tested per orifice length. Furthermore, the static pressure ratio across the orifice was varied between 1.05 and 1.6 for all examined orifices. The results of this comprehensive investigation demonstrate the beneficial influence of rounded inlet geometries and the ability to decrease pressure losses, which is especially true for higher cross flow ratios where the reduction of the pressure loss in comparison to sharp edged holes can be as high as 54%. With some exceptions, the chamfered orifices show a similar behavior as the rounded ones but with generally lower discharge coefficients. Nevertheless, a chamfered inlet yields lower pressure losses than a sharp edged inlet. The obtained experimental data was used to develop two correlations for the discharge coefficient as a function of geometrical as well as flow properties.

Analysis of Heavy Duty Gas Turbine Stator-Rotor Cavity Through 3D CFD-1D Fluid Network — Field Measurements Combined Approach

2016 ◽  
Author(s):  
Francesco Bavassano ◽  
Marco Mantero ◽  
Thibault Gasnier ◽  
Emanuele Ronconi
Keyword(s):  
Gas Turbine ◽  
Thrust Bearing ◽  
Computational Domain ◽  
Heavy Duty ◽  
Axial Thrust ◽  
Hot Gas ◽  
Fluid Network ◽  
Air System ◽  
Secondary Air ◽  
Heavy Duty Gas Turbine

An effective design and development of the Secondary Air System of a heavy-duty gas turbine is crucial for many purposes, such as cooling and sealing air supply, pre-swirling features, leakages control, casings and rotor thermal state assessment and rotor axial thrust management. All of these features directly impact on the performances and integrity of the whole machine and accordingly require advanced design approaches. The first stage stator-rotor turbine cavity of Ansaldo E-Class heavy-duty gas turbine AE94.2 underwent design modifications to adjust its internal pressure and consequently lower the global rotor axial load acting on the thrust bearing. This goal had to be reached while maintaining safety against hot gas ingestion from the turbine section main flow into the cavity, thus preserving the GT integrity. A multi-purpose analysis was then carried out on the cavity Secondary Air System. This involved steady 3D CFD calculations with a computational domain comprising the first turbine stage and the corresponding stator-rotor wheelspace. A combined use of CFD and SASAC, the in-house Ansaldo 1D fluid network code, finally led to an upgraded design of the cavity. Two field measurement campaigns were subsequently carried out on an AE94.2 GT to validate both the baseline configuration and the upgraded one, by means of 6 pressure and temperature sensors in the cavity and 12 load cells/thermocouples on the thrust bearing. The CFD model and results are presented, the fluid network tuning is discussed and the experimental setup and main outcomes of the two field campaigns are reported. Constant references to the definitive literature are made, with an effort to correlate at best research and industrial practice. These integrated activities allowed to perform a reliable verification against hot gas ingestion into the stator-rotor cavity and to successfully develop an effective solution, which reduced the GT rotor residual axial thrust by up to 25% less.

Innovative Design Features of the SGT5-8000H Turbine and Secondary Air System

2009 ◽  
Author(s):  
Ronald Rudolph ◽  
Robert Sunshine ◽  
Michael Woodhall ◽  
Michael Haendler
Keyword(s):  
Gas Turbine ◽  
High Efficiency ◽  
Innovative Design ◽  
Advanced Technologies ◽  
Air System ◽  
Secondary Air ◽  
Aero Engines ◽  
Stage 1 ◽  
Turbine Design ◽  
Validation Testing

Siemens Energy began the design of its H-class SGT5-8000H gas turbine in October of 2000. Validation testing of the SGT5-8000H prototype gas turbine began in December of 2007 at E.ON Energie’s Irsching, Germany power plant. The innovative turbine and secondary air system was designed by an international team of engineers, drawing on experience from Siemens and Westinghouse as well as experience from aero engines and academia. At the onset of the design, customers were consulted to identify features and functions they considered important. The result is a design that incorporates proven technologies from the current fleet of Siemens engines as well as numerous advanced technologies to create a simple, robust turbine design with H-class efficiency. The paper describes key features of the secondary air system including extractions, pre-swirlers, sealing systems and multi-use cooling. The SGT5-8000H turbine design has many unique features that promote high efficiency, excellent operability and improved maintainability. The paper describes features such as thermal barrier coatings, hydraulic clearance optimization, fast startup capability and stage 1 component removability via the combustor shell. The design is also being applied to the 60 Hz version of this product.

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