Thermo-Fluid Modelling for Gas Turbines—Part I: Theoretical Foundation and Uncertainty Analysis

2009 ◽  
Author(s):  
Konstantinos G. Kyprianidis ◽  
Vishal Sethi ◽  
Stephen O. T. Ogaji ◽  
Pericles Pilidis ◽  
Riti Singh ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Simulation Software ◽  
System Level ◽  
Fluid Models ◽  
Performance Simulation ◽  
Turbine Performance ◽  
Aircraft System ◽  
The Impact ◽  
Made In

In this two-part publication, various aspects of thermo-fluid modelling for gas turbines are described and their impact on performance calculations and emissions predictions at aircraft system level is assessed. Accurate and reliable fluid modelling is essential for any gas turbine performance simulation software as it provides a robust foundation for building advanced multi-disciplinary modelling capabilities. Caloric properties for generic and semi-generic gas turbine performance simulation codes can be calculated at various levels of fidelity; selection of the fidelity level is dependent upon the objectives of the simulation and execution time constraints. However, rigorous fluid modelling may not necessarily improve performance simulation accuracy unless all modelling assumptions and sources of uncertainty are aligned to the same level. Certain modelling aspects such as the introduction of chemical kinetics, and dissociation effects, may reduce computational speed and this is of significant importance for radical space exploration and novel propulsion cycle assessment. This paper describes and compares fluid models, based on different levels of fidelity, which have been developed for an industry standard gas turbine performance simulation code and an environmental assessment tool for novel propulsion cycles. The latter comprises the following modules: engine performance, aircraft performance, emissions prediction, and environmental impact. The work presented aims to fill the current literature gap by: (i) investigating the common assumptions made in thermo-fluid modelling for gas turbines and their effect on caloric properties and (ii) assessing the impact of uncertainties on performance calculations and emissions predictions at aircraft system level. In Part I of this two-part publication, a comprehensive analysis of thermo-fluid modelling for gas turbines is presented and the fluid models developed are discussed in detail. Common technical models, used for calculating caloric properties, are compared while typical assumptions made in fluid modelling, and the uncertainties induced, are examined. Several analyses, which demonstrate the effects of composition, temperature and pressure on caloric properties of working mediums for gas turbines, are presented. The working mediums examined include dry air and combustion products for various fuels and H/C ratios. The errors induced by ignoring dissociation effects are also discussed.

Thermo-Fluid Modelling for Gas Turbines—Part II: Impact on Performance Calculations and Emissions Predictions at Aircraft System Level

2009 ◽  
Author(s):  
Konstantinos G. Kyprianidis ◽  
Vishal Sethi ◽  
Stephen O. T. Ogaji ◽  
Pericles Pilidis ◽  
Riti Singh ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Fluid Model ◽  
Simulation Software ◽  
System Level ◽  
Computational Time ◽  
Performance Simulation ◽  
Turbine Performance ◽  
Aircraft System ◽  
Different Levels

In this two-part publication, various aspects of thermo-fluid modelling for gas turbines are described and their impact on performance calculations and emissions predictions at aircraft system level is assessed. Accurate and reliable fluid modelling is essential for any gas turbine performance simulation software as it provides a robust foundation for building advanced multi-disciplinary modelling capabilities. Caloric properties for generic and semi-generic gas turbine performance simulation codes can be calculated at various levels of fidelity; selection of the fidelity level is dependent upon the objectives of the simulation and execution time constraints. However, rigorous fluid modelling may not necessarily improve performance simulation accuracy unless all modelling assumptions and sources of uncertainty are aligned to the same level. Certain modelling aspects such as the introduction of chemical kinetics, and dissociation effects, may reduce computational speed and this is of significant importance for radical space exploration and novel propulsion cycle assessment. This paper describes and compares fluid models, based on different levels of fidelity, which have been developed for an industry standard gas turbine performance simulation code and an environmental assessment tool for novel propulsion cycles. The latter comprises the following modules: engine performance, aircraft performance, emissions prediction, and environmental impact. The work presented aims to fill the current literature gap by: (i) investigating the common assumptions made in thermo-fluid modelling for gas turbines and their effect on caloric properties and (ii) assessing the impact of uncertainties on performance calculations and emissions predictions at aircraft system level. In Part II of this two-part publication, the uncertainty induced in performance calculations by common technical models, used for calculating caloric properties, is discussed at engine level. The errors induced by ignoring dissociation are examined at 3 different levels: i) component level, ii) engine level, and iii) aircraft system level. Essentially, an attempt is made to shed light on the trade-off between improving the accuracy of a fluid model and the accuracy of a multi-disciplinary simulation at aircraft system level, against computational time penalties. The results obtained demonstrate that accurate modelling of the working fluid is not always essential; the accuracy/uncertainty for an overall engine model will always be better than the mean accuracy/uncertainty of the individual component estimates as long as systematic errors are carefully examined and reduced to acceptable levels to ensure error propagation does not cause significant discrepancies. Computational time penalties induced by improving the accuracy of the fluid model as well as the validity of the ideal gas assumption for future turbofan engines and novel propulsion cycles are discussed.

Uncertainty in gas turbine thermo-fluid modelling and its impact on performance calculations and emissions predictions at aircraft system level

2011 ◽  
Vol 226 (2) ◽  
pp. 163-181 ◽  
Author(s):  
K G Kyprianidis ◽  
V Sethi ◽  
S O T Ogaji ◽  
P Pilidis ◽  
R Singh ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Fluid Model ◽  
Simulation Software ◽  
System Level ◽  
Computational Time ◽  
Performance Simulation ◽  
Turbine Performance ◽  
Aircraft System ◽  
Working Media

In this article, various aspects of thermo-fluid modelling for gas turbines are described and the impact on performance calculations and emissions predictions at aircraft system level is assessed. Accurate and reliable fluid modelling is essential for any gas turbine performance simulation software as it provides a robust foundation for building advanced multi-disciplinary modelling capabilities. Caloric properties for generic and semi-generic gas turbine performance simulation codes can be calculated at various levels of fidelity; selection of the fidelity level is dependent upon the objectives of the simulation and execution time constraints. However, rigorous fluid modelling may not necessarily improve performance simulation accuracy unless all modelling assumptions and sources of uncertainty are aligned to the same level. A comprehensive analysis of thermo-fluid modelling for gas turbines is presented, and the fluid models developed are discussed in detail. Common technical models, used for calculating caloric properties, are compared while typical assumptions made in fluid modelling, and the uncertainties induced, are examined. Several analyses, which demonstrate the effects of composition, temperature, and pressure on caloric properties of working media for gas turbines, are presented. The working media examined include dry air and combustion products for various fuels and H/C ratios. The uncertainty induced in calculations by (a) using common technical models for evaluating fluid caloric properties and (b) ignoring dissociation effects is examined at three different levels: (i) component level, (ii) engine level, and (iii) aircraft system level. An attempt is made to shed light on the trade-off between improving the accuracy of a fluid model and the accuracy of a multi-disciplinary simulation at aircraft system level, against computational time penalties. The validity of the ideal gas assumption for future turbofan engines and novel propulsion cycles is discussed. The results obtained demonstrate that accurate modelling of the working fluid is essential, especially for assessing novel and/or aggressive cycles at aircraft system level. Where radical design space exploration is concerned, improving the accuracy of the fluid model will need to be carefully balanced with the computational time penalties involved.

Advanced Modeling of Fluid Thermodynamic Properties for Gas Turbine Performance Simulation

2008 ◽  
Author(s):  
Vishal Sethi ◽  
Fulvio Diara ◽  
Sina Atabak ◽  
Anthony Jackson ◽  
Arjun Bala ◽  
...  
Keyword(s):  
Thermodynamic Properties ◽  
Gas Turbine ◽  
Fluid Model ◽  
Simulation Software ◽  
Working Fluid ◽  
Performance Simulation ◽  
Turbine Performance ◽  
Fluid Properties ◽  
Convergence Problems ◽  
The Impact

This paper describes the structure of an advanced fluid thermodynamic model which has been developed for a novel advanced gas turbine simulation environment called PROOSIS. PROOSIS (PRopulsion Object Oriented SImulation Software) is part of the VIVACE-ECP (Value Improvement through a Virtual Aeronautical Collaborative Enterprise - European Cycle Programme) project. The main objective of the paper is to determine a way to achieve an accurate, robust and reliable fluid model. The results obtained demonstrate that accurate modeling of the working fluid is essential to avoid convergence problems of the thermodynamic functions thereby increasing the accuracy of calculated fluid properties. Additionally, the impact of accurately modeling fuel thermodynamic properties, at the point of the injection, is discussed.

Dynamic Performance Simulation of an Aeroderivative Gas Turbine Using the Matlab Simulink Environment

2013 ◽  
Author(s):  
Elias Tsoutsanis ◽  
Nader Meskin ◽  
Mohieddine Benammar ◽  
Khashayar Khorasani
Keyword(s):  
Power Generation ◽  
Real Time ◽  
Gas Turbine ◽  
Dynamic Behavior ◽  
Gas Turbines ◽  
Simulation Software ◽  
Performance Simulation ◽  
Matlab Simulink ◽  
Engine Model ◽  
Turbine Performance

In fossil fuel applications, such as air transportation and power generation systems, gas turbine is the prime mover which governs the aircraft’s propulsive and the plant’s thermal efficiency, respectively. Therefore, an accurate engine performance simulation has a significant impact on the operation and maintenance of gas turbines as far as reliability and availability considerations are concerned. Current trends in achieving stable engine operation, reliable fault diagnosis and prognosis requirements do motivate the development and implementation of real-time dynamic simulators for gas turbines that are sufficiently complex, highly nonlinear, have high fidelity and include fast response modules. This paper presents a gas turbine performance model for predicting the transient dynamic behavior of an aeroderivative engine that is suitable for both mechanical drive and power generation applications. The engine model has been developed in the Matlab/Simulink environment and combines both the inter-component volume and the constant mass flow methods. Dynamic equations of the mass momentum and the energy balance are incorporated into the steady state thermodynamic equations. This allows one to represent the engine model by a set of first order differential and algebraic equations. The developed Simulink model in an object oriented environment, can be easily adapted to any kind of gas turbine configuration. The model consists of a number of subsystems for representing the gas turbine’s components and the thermodynamic relationships among them. The components are represented by a set of suitable performance maps that are available from the open literature. The engine model has been validated with an established gas turbine performance simulation software. Time responses of the main variables that describe the gas turbine dynamic behavior are also included. The proposed gas turbine model with its dynamic simulation characteristics is a useful tool for development of real-time model-based diagnostics and prognostics technologies.

scholarly journals Industrial Gas Turbine Performance: Compressor Fouling and On-Line Washing

2014 ◽  
Vol 136 (10) ◽  
Author(s):  
Uyioghosa Igie ◽  
Pericles Pilidis ◽  
Dimitrios Fouflias ◽  
Kenneth Ramsden ◽  
Panagiotis Laskaridis
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Engine Performance ◽  
Operating Conditions ◽  
Compressor Cascade ◽  
Compressor Blades ◽  
Turbine Performance ◽  
Industrial Gas Turbines ◽  
On Line ◽  
The Impact

Industrial gas turbines are susceptible to compressor fouling, which is the deposition and accretion of airborne particles or contaminants on the compressor blades. This paper demonstrates the blade aerodynamic effects of fouling through experimental compressor cascade tests and the accompanied engine performance degradation using turbomatch, an in-house gas turbine performance software. Similarly, on-line compressor washing is implemented taking into account typical operating conditions comparable with industry high pressure washing. The fouling study shows the changes in the individual stage maps of the compressor in this condition, the impact of degradation during part-load, influence of control variables, and the identification of key parameters to ascertain fouling levels. Applying demineralized water for 10 min, with a liquid-to-air ratio of 0.2%, the aerodynamic performance of the blade is shown to improve, however most of the cleaning effect occurred in the first 5 min. The most effectively washed part of the blade was the pressure side, in which most of the particles deposited during the accelerated fouling. The simulation of fouled and washed engine conditions indicates 30% recovery of the lost power due to washing.

The Impact of Atmospheric Conditions on Gas Turbine Performance

1990 ◽  
Vol 112 (4) ◽  
pp. 590-596 ◽  
Author(s):  
A. A. El Hadik
Keyword(s):  
Relative Humidity ◽  
Ambient Temperature ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Arabian Gulf ◽  
Inlet Temperature ◽  
Atmospheric Conditions ◽  
Design Factor ◽  
Turbine Performance ◽  
The Impact

In a hot summer climate, as in Kuwait and other Arabian Gulf countries, the performance of a gas turbine deteriorates drastically during the high-temperature hours (up to 60°C in Kuwait). Power demand is the highest at these times. This necessitates an increase in installed gas turbine capacities to balance this deterioration. Gas turbines users are becoming aware of this problem as they depend more on gas turbines to satisfy their power needs and process heat for desalination due to the recent technical and economical development of gas turbines. This paper is devoted to studying the impact of atmospheric conditions, such as ambient temperature, pressure, and relative humidity on gas turbine performance. The reason for considering air pressures different from standard atmospheric pressure at the compressor inlet is the variation of this pressure with altitude. The results of this study can be generalized to include the cases of flights at high altitudes. A fully interactive computer program based on the derived governing equations is developed. The effects of typical variations of atmospheric conditions on power output and efficiency are considered. These include ambient temperature (range from −20 to 60°C), altitude (range from zero to 2000 m above sea level), and relative humidity (range from zero to 100 percent). The thermal efficiency and specific net work of a gas turbine were calculated at different values of maximum turbine inlet temperature (TIT) and variable environmental conditions. The value of TIT is a design factor that depends on the material specifications and the fuel/air ratio. Typical operating values of TIT in modern gas turbines were chosen for this study: 1000, 1200, 1400, and 1600 K. Both partial and full loads were considered in the analysis. Finally the calculated results were compared with actual gas turbine data supplied by manufacturers.

Uncertainty Reduction in Gas Turbine Performance Diagnostics by Accounting for Humidity Effects

2001 ◽  
Author(s):  
K. Mathioudakis ◽  
A. Tsalavoutas
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Ambient Conditions ◽  
Ambient Temperatures ◽  
Turbine Performance ◽  
Industrial Gas Turbines ◽  
Industrial Gas Turbine ◽  
The Impact ◽  
Performance Diagnostics ◽  
Health Parameters

The paper presents an analysis of the effect of ambient humidity on the performance of industrial gas turbines and examines the impact of humidity on methods used for engine condition assessment and fault diagnostics. First, the way of incorporating the effect of humidity into a computer model of gas turbine performance is described. The model is then used to derive parameters indicative of the “health” of a gas turbine and thus diagnose the presence of deterioration or faults. The impact of humidity magnitude on the values of these health parameters is studied and the uncertainty introduced, if humidity is not taken into account, is assessed. It is shown that the magnitude of the effect of humidity depends on ambient conditions and is more severe for higher ambient temperatures. Data from an industrial gas turbine are presented to demonstrate these effects and to show that if humidity is appropriately taken into account, the uncertainty in the estimation of health parameters is reduced

An Investigation of Component Deterioration in Gas Turbines Using Transient Performance Simulation

1988 ◽  
Author(s):  
Maurice F. White
Keyword(s):  
Gas Turbine ◽  
Mass Flow ◽  
Gas Turbines ◽  
Combustion Efficiency ◽  
Transient Performance ◽  
Performance Simulation ◽  
Turbine Plant ◽  
Physical Volume ◽  
Gas Turbine Plant ◽  
Made In

This paper discusses a program which has been developed for the prediction of steady state and transient performance of a gas turbine driven generator. The gas turbine plant was modelled using the component model principle and is based on the method for continuity of mass flow. The model requires the use of compressor and turbine characteristics together with curves for combustion efficiency. A number of simplifications are made in connecion with transient calculations. The influence of the machines physical volume on continuity of mass flow and effects of heat transfer between the gas and structural components are neglected. The model was used to investigate how component deterioration affects the important condition parameters during load transients and during rapid acceleration or deceleration. Fault conditions were simulated by manipulating the various efficiencies and loss factors for the different components in the machine. Many of the condition parameters that were investigated showed changes during acceleration which were considerably different from comparable changes in a fault free gas turbine.

A Method to Evaluate the Impact of Power Demand on HPT Blade Creep Life

2011 ◽  
Author(s):  
W. Mohamed ◽  
S. Eshati ◽  
P. Pilidis ◽  
S. Ogaji ◽  
P. Laskaridis ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Thermal Analyses ◽  
Peak Load ◽  
Quantitative Relationship ◽  
Simulation Software ◽  
Power Demand ◽  
Creep Life ◽  
Turbine Engine ◽  
The Impact

Peak load operation requires gas turbines to operate at high firing temperature with consequence reduction in the useful lives of components. This paper studies the quantitative relationship between gas turbine power setting and the hot gas-path components’ life consumption. A 165MW gas turbine engine is modelled and investigated in this study. A comparative lifing model, which performs stress and thermal analyses, estimates the minimum creep life of components using the parametric Larson Miller method. This lifing model was integrated with in-house performance simulation software to simulate the engine performances at design point and off-design conditions. The results showed that the combined effect of the operating environment and the power demand could have significant impact on blade creep life. Predicting this impact will aid gas turbine users in the decision making processes associated with gas turbine operation.

scholarly journals EVALUATION OF DEGRADATION EFFECT ON INTERCOOLED GAS TURBINE PERFORMANCE OPERATED IN FLEXIBLE MODE

2019 ◽  
Vol 2 (1) ◽  
pp. 52-70
Author(s):  
Siddig Dabbashi ◽  
Tarak Assaleh ◽  
Asia Gabassa
Keyword(s):  
Power Plant ◽  
Gas Turbine ◽  
Thermal Efficiency ◽  
Gas Turbines ◽  
Renewable Energy Sources ◽  
Simulation Software ◽  
Flexible Mode ◽  
Turbine Performance ◽  
Study Results ◽  
Flexible Operation

This paper investigates the effect of type and level of degradation in industrial gas turbine components on its performance under flexible operation due to working as a back-up to renewable energy sources (RES). This investigation was carried out for a 2-shaft 100MW aero-derivative gas turbine with intercooler. Due to the influence of unpredictable nature of power produced by RES, power plants are now operating in a flexible manner, which will require the operator to either stop operation during high feed-in from renewables or reducing the power output from the power plant to a certain percentage. This in turn has an impact on the gas turbine performance and thermal efficiency, which is also affected by the type and level of degradation of their components compared to the non-degraded gas turbines. In-House performance simulation software (TURBOMATCH), which was developed in Cranfield University, was used to carry out gas turbine performance modelling according to daily flexible operation scenarios for all seasons. These daily operating scenarios, which describe the power settings and ambient conditions for a period of 24 hours, were developed from data obtained from the UK national grid and the meteorology office data base. Different levels of degradation in mass flow and efficiency for low-pressure compressor and high-pressure turbine were applied in this study. Results illustrate an obvious impact of degradation type and level on fuel flow, turbine entry temperature, blade cooling temperature, shaft rotational speed and thermal efficiency for different seasons. This study has resulted in a tool which may be useful to power plant operators in understanding the various operating scenarios according to the criteria they wish to choose.

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