ALGOR Gas Turbine Performance Modular Tool: One Dimensional Turbine Module Validation

2016 ◽  
Author(s):  
Stefano Piola ◽  
Roberto Canepa ◽  
Andrea Silingardi ◽  
Stefano Cecchi ◽  
Carlo Carcasci ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Pressure Ratio ◽  
Operating Conditions ◽  
Computational Time ◽  
Flow Angle ◽  
One Dimensional ◽  
Design Performance ◽  
Turbine Performance ◽  
Air System ◽  
Secondary Air

One dimensional codes play a key role in gas turbine performance simulation: once they are calibrated they can give reliable results within very short computational time if compared to two or three dimensional analysis. Thanks to their ability to quickly evaluate flow, pressure and temperature along the energy conversion from fluid to shaft or reverse, one dimensional tools fit the requirements of modular-structured program for the simulation of complete gas turbine. In ASEN experience, ALGOR heat and mass balance software is used as a platform for system integration 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. ALGOR code provides advanced cycle calculation capabilities for example in case that cooling and secondary air system layout modification have to be considered in design process. In these situations, a turbine map-based approach is hardly applicable, while a one dimensional aerodynamic row by row simulation can provide a suitable method for off-design turbine behavior prediction. In ASEN practice, ALGOR turbine module is calibrated at design point on one dimensional data provided by turbine designers and is then adopted for the engine configuration optimization or off-design performance evaluation. This paper presents the validation of the off-design performance prediction given by the ALGOR embedded 1D turbine model comparing calculated results with experimental ones. The warm air full scale test rig investigated within the GE-NASA “Energy Efficient Engine” program for the aerodynamic evaluation of a two stages high pressure turbine has been chosen as validation case. It includes both experimental performance maps varying turbine operating conditions such as speed and pressure ratio extending to the sub-idle and starting region and an analysis of cooling flow variation effect on turbine performance. Literature available loss and exit flow angle correlations are implemented and compared to experimental data. The results given by each of them are analyzed to appreciate their accuracy in evaluating efficiency and flow variations. In addition the paper shows the ability of the 1D turbine module to consider secondary air system modification impact on performance comparing calculated results to experimental ones. Literature correlations tuning on proprietary experimental results could further improve the tool performance for the off-design evaluation of ASEN turbine geometries.

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.

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.

Analysis of Gas Turbine Rotating Cavities by a One-Dimensional Model: Definition of New Disk Friction Coefficient Correlations Set

2010 ◽  
Vol 133 (2) ◽  
Author(s):  
Riccardo Da Soghe ◽  
Bruno Facchini ◽  
Luca Innocenti ◽  
Mirko Micio
Keyword(s):  
Gas Turbine ◽  
Axisymmetric Flow ◽  
Operating Conditions ◽  
Dimensional Model ◽  
Outer Flow ◽  
One Dimensional ◽  
Wide Range ◽  
Air System ◽  
Secondary Air ◽  
Radial Outflow

Reliable design of a secondary air system is one of the main tasks for the safety and unfailing performance of gas turbine engines. To meet the increasing demands of gas turbine designs, improved tools in the prediction of 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 computational fluid dynamics (CFD) approach. Usually, those 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 axisymmetric flow using experimental correlations, both to incorporate the flow phenomena caused by multidimensional effects such as 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 the Batchelor and/or Stewartson flow structures. A primary 1D-code testing campaign is available in the literature (2008, “Analysis of Gas Turbine Rotating Cavities by a One-Dimensional Model,” ISROMAC Paper No. 12-2008-20161). In the present paper, the authors developed, using CFD tools, reliable correlations for both stator and rotor friction coefficients and provided a full 1D-code validation, due to the lack of experimental data, comparing 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.

Nonlinear Multiple Points Gas Turbine Off-Design Performance Adaptation Using a Genetic Algorithm

2011 ◽  
Vol 133 (7) ◽  
Author(s):  
Y. G. Li ◽  
M. F. Abdul Ghafir ◽  
L. Wang ◽  
R. Singh ◽  
K. Huang ◽  
...  
Keyword(s):  
Genetic Algorithm ◽  
Gas Turbine ◽  
Scaling Factor ◽  
Performance Model ◽  
Operating Conditions ◽  
Performance Models ◽  
Design Performance ◽  
Turbine Performance ◽  
Thermodynamic Performance ◽  
Performance Adaptation

Accurate gas turbine performance models are crucial in many gas turbine performance analysis and gas path diagnostic applications. With current thermodynamic performance modeling techniques, the accuracy of gas turbine performance models at off-design conditions is determined by engine component characteristic maps obtained in rig tests and these maps may not be available to gas turbine users or may not be accurate for individual engines. In this paper, a nonlinear multiple point performance adaptation approach using a genetic algorithm is introduced with the aim to improve the performance prediction accuracy of gas turbine engines at different off-design conditions by calibrating the engine performance models against available test data. Such calibration is carried out with introduced nonlinear map scaling factor functions by “modifying” initially implemented component characteristic maps in the gas turbine thermodynamic performance models. A genetic algorithm is used to search for an optimal set of nonlinear scaling factor functions for the maps via an objective function that measures the difference between the simulated and actual gas path measurements. The developed off-design performance adaptation approach has been applied to a model single spool turbo-shaft aero gas turbine engine and has demonstrated a significant improvement in the performance model accuracy at off-design operating conditions.

About Simplifications in Gas Turbine Performance Calculations

2007 ◽  
Author(s):  
Joachim Kurzke
Keyword(s):  
Gas Turbine ◽  
Real World ◽  
Thermal Efficiency ◽  
Flow Characteristics ◽  
Operating Conditions ◽  
Flow Distortion ◽  
One Dimensional ◽  
Practical Applications ◽  
Turbine Performance ◽  
In Series

Any gas turbine performance simulation tool employs simplifications, some more, some less. It depends on the intent of the simulation which simplifications are appropriate. For beginners, many are necessary for teaching how the gas turbine works from principle. For practical applications — because of the accuracy requirements — many simplifications introduced in textbooks are not appropriate. This paper comments on the simplifications that are typically made. Simplified gas property models are quite acceptable for ideal cycle analysis. For the examination of real cycles, however, especially the model of the burner should be better than those described in most textbooks. This is because these models yield the best cycle efficiency at stoichiometric fuel-air-ratio while a realistic burner model leads to the conclusion that the best thermal efficiency happens to be at significantly lower fuel-air-ratios respectively temperatures. For off-design simulations many simplifications have the aim to avoid iterative solutions or restricting the algorithms to one-dimensional iterations. If more than one iteration variable shows up — which is the case with multi-spool engine simulations — then the problem is solved with fitting several one-dimensional iterations into each other. This methodology is described in most textbooks, but it is nearly never used in industry because the logic is more complex than necessary and difficult to adapt to special needs. The seeming simplification is actually a complication when applied to real world problems. Universities should teach as a standard the multidimensional Newton Raphson iteration technique which allows writing gas turbine cycle codes with nearly no restriction to the methods of formulating the laws of physics. The consequence of simplified mathematics is often an off-design simulation which does not employ compressor and turbine maps. Such a methodology yields accurate values for thermal efficiency respectively specific fuel consumption only within a narrow range of operating conditions; the accuracy of the results is not sufficient for real world applications. Of course also in programs for industrial use the reality is modeled with many compromises. Some simplifications which have not so obvious consequences are discussed. For example, there is an influence of the speed-flow characteristics in the booster map on its operating line if an often used type of fan performance representation is employed. Another example is that an oversimplified description of what happens in the compressor interduct can lead to wrong conclusions when the effects of inlet flow distortion on the stability of compressors in series are sought.

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.

Compressor Performance With Water Injection

2001 ◽  
Author(s):  
J. H. Horlock
Keyword(s):  
Specific Heat ◽  
Gas Turbine ◽  
Dimensional Analysis ◽  
Water Injection ◽  
Operating Conditions ◽  
Water Droplets ◽  
One Dimensional ◽  
Design Performance ◽  
Effective Specific Heat ◽  
Compressor Performance

There has been renewed interest recently in the injection of water at inlet to gas turbine plants. As is to be expected there is a drop in temperature at the inlet face to the compressor and this obviously has an effect on compressor performance. But a second effect occurs within the early stages of the compressor itself, associated with an increase in the effective specific heat due to continuing evaporation of the water droplets. Consequently there are movements away from design operating conditions on the stage characteristics. A one-dimensional analysis of compressor off-design performance is developed to illustrate these effects, which appear to be appreciable, even for very small quantities of water injection.

Non-Linear Multiple Points Gas Turbine Off-Design Performance Adaptation Using a Genetic Algorithm

2010 ◽  
Author(s):  
Y. G. Li ◽  
M. F. Abdul Ghafir ◽  
L. Wang ◽  
R. Singh ◽  
K. Huang ◽  
...  
Keyword(s):  
Genetic Algorithm ◽  
Gas Turbine ◽  
Scaling Factor ◽  
Operating Conditions ◽  
Performance Models ◽  
Design Performance ◽  
Turbine Performance ◽  
Thermodynamic Performance ◽  
Non Linear ◽  
Performance Adaptation

Accurate gas turbine performance models are crucial in many gas turbine performance analysis and gas path diagnostic applications. With current thermodynamic performance modelling techniques, the accuracy of gas turbine performance models at off-design conditions is determined by engine component characteristic maps obtained in rig tests and these maps may not be available to gas turbine users or may not be accurate for individual engines. In this paper, a non-linear multiple point performance adaptation approach using a Genetic Algorithm is introduced with the aim to improve the performance prediction accuracy of gas turbine engines at different off-design conditions by calibrating the engine performance models against available test data. Such calibration is carried out with introduced non-linear map scaling factor functions by ‘modifying’ initially implemented component characteristic maps in the gas turbine thermodynamic performance models. A Genetic Algorithm is used to search for an optimal set of non-linear scaling factor functions for the maps via an objective function that measures the difference between the simulated and actual gas path measurements. The developed off-design performance adaptation approach has been applied to a model single spool turboshaft aero gas turbine engine and demonstrated a significant improvement in the performance model accuracy at off-design operating conditions.

Development of Numerical Tools for Stator-Rotor Cavities Calculation in Heavy-Duty Gas Turbines

2008 ◽  
Author(s):  
C. Bianchini ◽  
R. Da Soghe ◽  
B. Facchini ◽  
L. Innocenti ◽  
M. Micio ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Inlet Temperature ◽  
Heavy Duty ◽  
One Dimensional ◽  
Air System ◽  
Numerical Tools ◽  
Secondary Air ◽  
The One

In high performance heavy-duty engines, turbine inlet temperature is considerably higher than the melting point of the metals used for turbine components e.g. nozzle guide vanes, turbine rotor blades, platforms and discs, etc. Cooling of those components is therefore essential and is achieved by diverting a few percent of the compressed air from extraction points in the compressor and passing it to the turbine through stationary ducts and over rotating shafts and discs. All those elements form the so-called secondary air system of the gas turbine, whose correct design is hence fundamental for safety, reliability and performance of the engine. Secondary air system analysis is generally performed using one dimensional calculation procedures, based correlations both for pressure losses and heat transfer coefficient evaluations. Such calculation approach, usually used in industry, takes advantages in terms of reduced computational resources. Besides, for those elements of air systems where multidimensional flow effects are not negligible and the flow field structure is highly complex, the one-dimensional–correlative modeling needs to be supported by CFD investigations. Among these elements, rotating cavities need a careful modeling in order to correctly estimate discs temperature and the minimum amount of purge air to prevent hot gas ingestion. Ansaldo Energia is facing the investigation of secondary air system of Vx4.3A gas turbine models also by using numerical tools developed by Dipartimento di Energetica “Sergio Stecco” of University of Florence. They include both a one-dimensional cavity solver and a 3D unstructured finite volume code of compressible Navier-Stokes Equation based on open source C++ Open-Foam libraries for continuum mechanics. The first numerical tool has been widely employed in simplified analysis of stator-rotor cavities and is undergoing to be integrated into a in-house lumped-parameters fluid network solver simulating the entire secondary air system. This paper is aimed at discussing some interesting results from numerical tests performed with the above discussed programs on stator-rotor cavities of a V94.3A2 gas turbine. Such numerical analysis was addressed both for better understanding the flow phenomena in the wheel space regions and for testing and verifying the experimental correlations and the calculation procedure implemented in the one-dimensional program. A detailed comparative analysis between the two different codes will be shown, both in adiabatic and heat transfer conditions.

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