Virtual Gas Turbines Part Ii: an Automated Whole-engine Secondary Air System Model Generation

2021 ◽  
Author(s):  
Davendu Kulkarni ◽  
Luca di Mare
Keyword(s):  
Gas Turbine ◽  
Network Model ◽  
Gas Turbines ◽  
Model Generation ◽  
Time Cost ◽  
Flow Network ◽  
Turbine Engine ◽  
Geometry Model ◽  
Air System ◽  
Secondary Air

Abstract The design and analysis of the secondary air system (SAS) of gas turbine engine is a complex and time-consuming process because of the complicated topology and iterative nature of SAS design. The conventional SAS design-analysis model generation process is quite tedious and inefficient. It is still largely dependent on human expertise and thus incurs high time-cost. This paper presents an automated, whole-engine SAS flow network model generation methodology. This method accesses a pre-built feature-based whole-engine geometry model and transforms the geometry features into the features suitable for SAS flow network analysis. The proposed method extracts both the geometric and non-geometric information from the engine geometry model such as, rotational frames, materials and boundary conditions etc. Apart from ensuring geometric consistency, this methodology also establishes a bi-directional information exchange protocol between the engine geometry model and the SAS flow network model, which enables to make engine geometry modifications based on SAS analysis results. The application of this feature mapping methodology is demonstrated by generating the secondary air system (SAS) flow network model of a modern three-shaft gas turbine engine. This flow network model is generated within a few minutes, without any human intervention, which significantly reduces the SAS design-analysis time-cost. The proposed methodology seamlessly links the geometry and the air system modellers of Virtual Gas Turbines simulation framework and thus allows performing a large number of whole-engine SAS simulations, design optimisations and fast re-design activities.

Virtual Gas Turbines Part II: an Automated Whole-Engine Secondary Air System Model Generation

2021 ◽  
Author(s):  
Davendu Y. Kulkarni ◽  
Luca di Mare
Keyword(s):  
Gas Turbine ◽  
Network Model ◽  
Design Analysis ◽  
Model Generation ◽  
Time Cost ◽  
Flow Network ◽  
Turbine Engine ◽  
Geometry Model ◽  
Air System ◽  
Secondary Air

Abstract The design and analysis of the secondary air system (SAS) of gas turbine engine is a complex and time-consuming process because of its complicated geometry topology. The conventional SAS design-analysis model generation process is quite tedious, time consuming. It is still heavily dependent on human expertise and thus incurs high time-cost. This paper presents an automated, whole-engine SAS flow network model generation methodology. During the SAS preprocessing step, the method accesses a pre-built whole-engine geometry model created using a novel, in-house, feature-based geometry modelling environment. It then transforms the engine geometry features into the features suitable for SAS flow network analysis. The proposed method not only extracts the geometric information from the computational geometry but also retrieves additional non-geometric attributes such as, rotational frames, boundary types, materials and boundary conditions etc. Apart from ensuring geometric consistency, this methodology also establishes a bi-directional information exchange protocol between engine geometry model and SAS flow network model, which enables making engine geometry modifications based on SAS analysis results. The application of this feature mapping methodology is demonstrated by generating the secondary air system (SAS) flow network model of a modern three-shaft gas turbine engine. This capability is particularly useful for the integration of geometry modeler with the simulation framework. The present SAS model is generated within a few minutes, without any human intervention, which significantly reduces the SAS design-analysis time-cost. The proposed method allows performing a large number of whole-engine SAS simulations, design optimisations and fast re-design activities.

Impact of the Secondary Air System Design Parameters on the Calculation of Turbine Discs Windage

2014 ◽  
Author(s):  
Jose Maria Rey Villazón ◽  
Toni Wildow ◽  
Robert Benton ◽  
Moritz Göhler ◽  
Arnold Kühhorn
Keyword(s):  
Flow Field ◽  
Network Model ◽  
Gas Turbines ◽  
Integral Model ◽  
Design Parameters ◽  
Flow Network ◽  
Aero Engine ◽  
Air System ◽  
Secondary Air ◽  
The Impact

The rotating components in gas turbines are very highly stressed as a result of the centrifugal and thermal loads. One of the main functions of the secondary air system (SAS) is to ensure that the rotating components are surrounded by air that optimizes disc lifing and integrity. The SAS is also responsible for the blade cooling flow supply, preventing hot gas ingestion from the main annulus into the rotor-stator cavities, and for balancing the net axial load in the thrust bearings. Thus, the SAS design requires a multidisciplinary compromise to provide the above functions, while minimizing the penalty of the secondary flows on engine performance. The phenomenon known as rotor-stator drag or windage is defined as the power of the rotor moment acting on its environment. The power loss due to windage has a direct impact on the performance of the turbine and the overall efficiency of the engine. This paper describes a novel preliminary design approach to calculate the windage of the rotor-stator cavities in the front of a typical aero engine HP turbine. The new method is applied to investigate the impact of the SAS design parameters on the windage losses and on the properties of the cooling flows leading to the main annulus. Initially, a theoretical approach is followed to calculate the power losses of each part of the HPT front air feed system. Then, a 1D-network integral model of the cavities and flow passages of the HPT front is built and enhanced with detailed flow field correlations. The new 1D-flow network model offers higher fidelity regarding local effects. A result comparison between the theoretical calculation and the prediction of the enhanced flow network model puts forward the relevance of the local flow field effects in the design concept of the SAS. Using the enhanced 1D-flow network models, the SAS design parameters are varied to assess their influence on the windage and pumping power calculation. As a conclusion, the paper shows how the SAS design can have a significant influence on the HPT overall power and the air that is fed back into the turbine blade rows. Controlling these features is essential to bid a competitive technology in the aero engine industry.

Analysis of Gas Turbine Rotating Cavities by an One-Dimensional Model

2009 ◽  
Author(s):  
Riccardo Da Soghe ◽  
Bruno Facchini ◽  
Luca Innocenti ◽  
Mirko Micio
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Design Tool ◽  
Operating Conditions ◽  
Outer Flow ◽  
One Dimensional ◽  
Wide Range ◽  
Air System ◽  
Secondary Air ◽  
Radial Outflow

Reliable design of secondary air system is one of the main tasks for the safety, unfailing and performance of gas turbine engines. To meet the increasing demands of gas turbines design, improved tools in prediction of the secondary air system behavior over a wide range of operating conditions are needed. A real gas turbine secondary air system includes several components, therefore its analysis is not carried out through a complete CFD approach. Usually, that predictions are performed using codes, based on simplified approach which allows to evaluate the flow characteristics in each branch of the air system requiring very poor computational resources and few calculation time. Generally the available simplified commercial packages allow to correctly solve only some of the components of a real air system and often the elements with a more complex flow structure cannot be studied; among such elements, the analysis of rotating cavities is very hard. This paper deals with a design-tool developed at the University of Florence for the simulation of rotating cavities. This simplified in-house code solves the governing equations for steady one-dimensional axysimmetric flow using experimental correlations both to incorporate flow phenomena caused by multidimensional effects, like heat transfer and flow field losses, and to evaluate the circumferential component of velocity. Although this calculation approach does not enable a correct modeling of the turbulent flow within a wheel space cavity, the authors tried to create an accurate model taking into account the effects of inner and outer flow extraction, rotor and stator drag, leakages, injection momentum and, finally, the shroud/rim seal effects on cavity ingestion. The simplified calculation tool was designed to simulate the flow in a rotating cavity with radial outflow both with a Batchelor and/or Stewartson flow structures. A primary 1D-code testing campaign is available in the literature [1]. In the present paper the authors develop, using CFD tools, reliable correlations for both stator and rotor friction coefficients and provide a full 1D-code validation comparing, due to lack of experimental data, the in house design-code predictions with those evaluated by CFD.

Heavy Duty Gas Turbine Simulation: Global Performances Estimation and Secondary Air System Modifications

2006 ◽  
Author(s):  
Carlo Carcasci ◽  
Bruno Facchini ◽  
Stefano Gori ◽  
Luca Bozzi ◽  
Stefano Traverso
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Cooling System ◽  
Energy System ◽  
Operating Conditions ◽  
Coupled Analysis ◽  
Ambient Conditions ◽  
Air System ◽  
Secondary Air ◽  
And Performance

This paper reviews a modular-structured program ESMS (Energy System Modular Simulation) for the simulation of air-cooled gas turbines cycles, including the calculation of the secondary air system. The program has been tested for the Ansaldo Energia gas turbine V94.3A, which is one of the more advanced models in the family Vx4.3A with a rated power of 270 MW. V94.3A cooling system has been modeled with SASAC (Secondary Air System Ansaldo Code), the Ansaldo code used to predict the structure of the flow through the internal air system. The objective of the work was to investigate the tuning of the analytical program on the basis of the data from design and performance codes in use at Ansaldo Energy Gas Turbine Department. The results, both at base load over different ambient conditions and in critical off-design operating points (full-speed-no-load and minimum-load), have been compared with APC (Ansaldo Performance Code) and confirmed by field data. The coupled analysis of cycle and cooling network shows interesting evaluations for components life estimation and reliability during off-design operating conditions.

Finite Element Transient Modelling for Aero-Thermo-Mechanical Analysis of Whole Gas Turbine Engine

2019 ◽  
Author(s):  
Sabrina Giuntini ◽  
Antonio Andreini ◽  
Bruno Facchini
Keyword(s):  
Gas Turbines ◽  
Structural Integrity ◽  
Numerical Procedure ◽  
Mechanical Analysis ◽  
Operating Conditions ◽  
Test Case ◽  
Large Power ◽  
Turbine Engine ◽  
Air System ◽  
Secondary Air

Abstract It is here proposed a numerical procedure aimed to perform transient aero-thermo-mechanical calculations of large power generation gas turbines. Due to the frequent startups and shutdowns that nowadays these engines encounter, procedures for multi-physics simulations have to take into account the complex coupled interactions related to inertial and thermal loads, and seal running clearances. In order to develop suitable secondary air system configurations, guarantee structural integrity and maintain actual clearances and temperature peaks in pre-established ranges, the overall complexity of the structure has to be reproduced with a whole engine modelling approach, simulating the entire machine in the real operating conditions. In the proposed methodology the aerodynamic solution providing mass flows and pressures, and the thermo-mechanical analysis returning temperatures and material expansion, are performed separately. The procedure faces the aero-thermo-mechanical problem with an iterative process with the aim of taking into account the complex aero-thermo-mechanical interactions actually characterizing a real engine, in a robust and modular tool, combining secondary air system, thermal and mechanical analysis. The heat conduction in the solid and the fluid-solid heat transfer are computed by a customized version of the open source FEM solver CalculiX®. The secondary air system is modelled by a customized version of the embedded CalculiX® one-dimensional fluid network solver. In order to assess the physical coherence of the presented methodology the procedure has been applied to a test case representative of a portion of a real engine geometry, tested in a thermal transient cycle for the assessment of the interaction between secondary air system properties and geometry deformations.

Particulate Monitor for Gas Turbine Cooling Air

2008 ◽  
Author(s):  
Richard H. Bunce ◽  
Francisco Dovali-Solis ◽  
Robert W. Baxter
Keyword(s):  
Gas Turbine ◽  
Monitoring System ◽  
Cooling System ◽  
Gas Turbine Engine ◽  
Minimum Size ◽  
Turbine Engine ◽  
Air System ◽  
Air Cooler ◽  
Secondary Air ◽  
Cooling Air

It is important to monitor the quality of the air used in the cooling system of a gas turbine engine. There can be many reasons that particulates smaller than the minimum size removed by typical engine air filters can enter the secondary air system piping in a gas turbine engine system. Siemens has developed a system that provide real time monitoring of particulate concentrations by adapting a commercial electrodynamic devise for use within the confines of the gas turbine secondary air system with provision for a grab sample option to collect samples for laboratory analysis. This on-line monitoring system is functional at typical engine cooling system piping operating pressure and temperature. The system is calibrated for detection of iron oxide particles in the 1 to 100 micrometer range at concentration of from 1 to 50 parts per million mass wet (ppmmw) The electro dynamic device is nominally operable at 800°C. The particulate monitoring system requires special mounting and antenna. This system may be adjusted for other materials, sizes and concentrations. The system and its developmental application are described. The system has been tested and test results are reviewed. The test application was the cooling air piping of a Siemens gas turbine engine. Multiple locations were monitored. The cooling system in this engine incorporates an air cooler and the particulate monitoring system was tested upstream and downstream of the air cooler for temperature contrast. The monitor itself is limited to the piping system and not the engine gas-path.

ALGOR Gas Turbine Performance Modular Tool: Map Based Modules Development

2016 ◽  
Author(s):  
Roberto Canepa ◽  
Stefano Piola ◽  
Marco Pirotta ◽  
Andrea Silingardi ◽  
Federico Bonzani ◽  
...  
Keyword(s):  
Mass Balance ◽  
Gas Turbine ◽  
Reference Points ◽  
Performance Estimation ◽  
Modular Structure ◽  
Nonlinear Phenomena ◽  
Turbine Engine ◽  
Air System ◽  
Secondary Air ◽  
Flow Functions

Commercially available or in-house developed performance tools, mostly based on heat and mass balance, are nowadays widespread among Universities, consulting companies and utilities. Generally these software are based on main gas turbine measurable information and, yet accurate on global performance estimation, are limited in the level of insight on component performance they can provide and also in the range of analysis, generally limited to engine possible operating points. On the other hand, the tools adopted by OEMs generally differ for components (compressor, turbine and combustor) and secondary air system details. In ASEN experience ALGOR heat and mass balance software is used as a platform for system integrations between each disciplines by means of a modular structure in which a large number of modules, chosen from the available library, are freely connected allowing to potentially analyze any gas turbine engine configuration. This paper describes the structure and the implementation of latest ALGOR updates, developed by ASEN and University of Florence, aimed at creating new map based modules for compressor and secondary air system. With this approach, component performance coming from field data can be continuously adopted to refine the reliability of calculation. Furthermore, nonlinear phenomena occurring in stationary and rotating cooling passages can be evaluated only with devoted calculation tools, which output can be conveniently translated in flow functions maps. Thanks to ALGOR modular structure, with these newly available (map-interpolating) modules, additional levels of analysis are allowed, ranging from “cycle deck” map-matching level, to mixed modelling in which map based modules are linked with 1D mean line analysis modules. Moreover their use can be also foreseen in ASEN conceptual design approach in which just map reference points are adjusted to reflect expected technological leaps required by engine upgrade.

Numerical and Experimental Investigation of Secondary Flows and Influence of Air System Design on Heavy-Duty Gas Turbine Performance

2012 ◽  
Author(s):  
Luca Bozzi ◽  
Enrico D’angelo
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Engine Performance ◽  
Combined Cycle ◽  
Secondary Flows ◽  
Operating Conditions ◽  
Heavy Duty ◽  
Turbine Performance ◽  
Air System ◽  
Secondary Air

High turn-down operating of heavy-duty gas turbines in modern Combined Cycle Plants requires a highly efficient secondary air system to ensure the proper supply of cooling and sealing air. Thus, accurate performance prediction of secondary flows in the complete range of operating conditions is crucial. The paper gives an overview of the secondary air system of Ansaldo F-class AEx4.3A gas turbines. Focus of the work is a procedure to calculate the cooling flows, which allows investigating both the interaction between cooled rows and additional secondary flows (sealing and leakage air) and the influence on gas turbine performance. The procedure is based on a fluid-network solver modelling the engine secondary air system. Parametric curves implemented into the network model give the consumption of cooling air of blades and vanes. Performances of blade cooling systems based on different cooling technology are presented. Variations of secondary air flows in function of load and/or ambient conditions are discussed and justified. The effect of secondary air reduction is investigated in details showing the relationship between the position, along the gas path, of the upgrade and the increasing of engine performance. In particular, a section of the paper describes the application of a consistent and straightforward technique, based on an exergy analysis, to estimate the effect of major modifications to the air system on overall engine performance. A set of models for the different factors of cooling loss is presented and sample calculations are used to illustrate the splitting and magnitude of losses. Field data, referred to AE64.3A gas turbine, are used to calibrate the correlation method and to enhance the structure of the lumped-parameters network models.

An Efficient Procedure for the Analysis of Heavy Duty Gas Turbine Secondary Flows in Different Operating Conditions

2010 ◽  
Author(s):  
Matteo Cerutti ◽  
Luca Bozzi ◽  
Federico Bonzani ◽  
Carlo Carcasci
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Cooling System ◽  
Secondary Flows ◽  
Operating Conditions ◽  
Heavy Duty ◽  
Efficient Procedure ◽  
Air System ◽  
Secondary Air ◽  
Flow Functions

Combined cycle and partial load operating of modern heavy-duty gas turbines require highly efficient secondary air systems to supply both cooling and sealing air. Accurate performance predictions are then a fundamental demand over a wide range of operability. The paper describes the development of an efficient procedure for the investigation of gas turbine secondary flows, based on an in-house made fluid network solver, written in Matlab® environment. Fast network generation and debugging are achieved thanks to Simulink® graphical interface and modular structure, allowing predictions of the whole secondary air system. A crucial aspect of such an analysis is the calculation of blade and vane cooling flows, taking into account the interaction between inner and outer extraction lines. The problem is closed thanks to ad-hoc calculated transfer functions: cooling system performances and flow functions are solved in a pre-processing phase and results correlated to influencing parameters using Response Surface Methodology (RSM) and Design of Experiments (DOE) techniques. The procedure has been proved on the secondary air system of the AE94.3A2 Ansaldo Energia gas turbine. Flow functions for the cooling system of the first stage blade, calculated by RSM and DOE techniques, are presented. Flow functions based calculation of film cooling, tip cooling and trailing edge cooling air flows is described in details.

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