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

Author(s):  
Maurice F. White

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.

Author(s):  
R. Yadav ◽  
P. Sreedhar Yadav

The major challenges before the design engineers of a gas turbine plant and its variants are the enhancement of power output, substantial reduction in NOx emission and improvement in plant thermal efficiency. There are various possibilities to achieve these objectives and humid air gas turbine cycle power plant is one of them. The present study deals with the thermodynamic study of humid air gas turbine cycle power plants based on first law. Using the modeling and governing equations, the parametric study has been carried out. The results obtained will be helpful in designing the humid air gas turbines, which are used as peaking units. The comparison of performance of humid air gas turbine cycle shows that it is superior to basic gas turbine cycle but inferior and more complex to steam injected cycle.


Author(s):  
Konstantinos G. Kyprianidis ◽  
Vishal Sethi ◽  
Stephen O. T. Ogaji ◽  
Pericles Pilidis ◽  
Riti Singh ◽  
...  

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.


Author(s):  
G. E. Marin ◽  
B. M. Osipov ◽  
A. R. Akhmetshin

THE PURPOSE. The study is aimed at studying the effect of fuel gases of various component composition on the environmental performance of the GE 6FA gas turbine unit. Consider using hydrogen as primary sweat to minimize emissions and improve performance of the GE 6FA gas turbine. METHODS. To achieve this goal, the ASGRET (Automated system for gas-dynamic calculations of power turbomachines) software package was used. RESULTS. The article discusses promising directions for the utilization of CO2 using highly efficient technologies with further use or disposal. A mathematical model of a GE 6FA gas turbine unit, diagrams of changes in the main characteristics and the composition of emissions when operating on various types of fuel, including hydrogen, are presented. CONCLUSION. The studies carried out show that a change in the component composition of the gas affects the energy characteristics of the engine. The method for determining the quantitative composition of COx, NOx, SOx in the exhaust gases of a gas turbine plant is presented. The transition to the reserve fuel kerosene leads to an increase in the amount of emissions, which must be taken into account when designing systems for capturing harmful emissions with a dual-fuel fuel gas supply system. The use of hydrogen as a fuel for gas turbines allows to reduce not only the cost of fuel preparation, but also to minimize emissions and improve the performance of the gas turbine plant.


2000 ◽  
Vol 123 (2) ◽  
pp. 265-270 ◽  
Author(s):  
E. A. Khodak ◽  
G. A. Romakhova

At present high temperature, internally cooled gas turbines form the basis for the development of highly efficient plants for utility and industrial markets. Minimizing irreversibility of processes in all components of a gas turbine plant leads to greater plant efficiency. Turbine cooling, like all real processes, is an irreversible process and results in lost opportunity for producing work. Traditional tools based on the first and second laws of thermodynamics enable performance parameters of a plant to be evaluated, but they give no way of separating the losses due to cooling from the overall losses. This limitation arises from the fact that the two processes, expansion and cooling, go on simultaneously in the turbine. Part of the cooling losses are conventionally attributed to the turbine losses. This study was intended for the direct determination of lost work due to cooling. To this end, a cooled gas turbine plant has been treated as a work-producing thermodynamic system consisting of two systems that exchange heat with one another. The concepts of availability and exergy have been used in the analysis of such a system. The proposed approach is applicable to gas turbines with various types of cooling: open-air, closed-steam, and open-steam cooling. The open-air cooling technology has found the most wide application in current gas turbines. Using this type of cooling as an example, the potential of the developed method is shown. Losses and destructions of exergy in the conversion of the fuel exergy into work are illustrated by the exergy flow diagram.


Author(s):  
Jayoung Ki ◽  
Changduk Kong ◽  
Seonghee Kho ◽  
Changho Lee

Because an aircraft gas turbine operates under various flight conditions that change with altitude, flight velocity, and ambient temperature, the performance estimation that considers the flight conditions must be known before developing or operating the gas turbine. More so, for the unmanned aerial vehicle (UAV) where the engine is activated by an onboard engine controller in emergencies, the precise performance model including the estimated steady-state and transient performance data should be provided to the engine control system and the engine health monitoring system. In this study, a graphic user interface (GUI) type steady-state and transient performance simulation model of the PW206C turboshaft engine that was adopted for use in the Smart UAV was developed using SIMULINK for the performance analysis. For the simulation model, first the component maps including the compressor, gas generator turbine, and power turbine were inversely generated from the manufacturer’s limited performance deck data by the hybrid method. For the work and mass flow matching between components of the steady-state simulation, the state-flow library of SIMULINK was applied. The proposed steady-state performance model can simulate off-design point performance at various flight conditions and part loads, and in order to evaluate the steady-state performance model their simulation results were compared with the manufacturer’s performance deck data. According to comparison results, it was confirmed that the steady-state model agreed well with the deck data within 3% in all flight envelopes. In the transient performance simulation model, the continuity of mass flow (CMF) method was used, and the rotational speed change was calculated by integrating the excess torque due to the transient fuel flow change using the Runge–Kutta method. In this transient performance simulation, the turbine overshoot was predicted.


1997 ◽  
Vol 119 (3) ◽  
pp. 565-567
Author(s):  
Q. Song ◽  
M. J. Grimble

The algorithm for a multivariable controller using neural network is based on a discrete-time fixed controller and the neural network provides a compensation signal to suppress the nonlinearity. The multivariable neural controller is easy to train and applied to an aircraft gas turbine plant.


Author(s):  
Jayoung Ki ◽  
Changduk Kong ◽  
Seonghee Kho ◽  
Changho Lee

Because aircraft gas turbine operates under various flight conditions that changes with altitude, flight velocity and ambient temperature, performance estimation that considers the flight conditions must be known before developing or operating the gas turbine. More so, for the UAV (Unmanned Aerial Vehicle) where the engine is activated by an onboard engine controller in emergency, the precise performance model including the estimated steady-state and transient performance data should be provided to the engine control system and the engine health monitoring system. In this study, a GUI (Graphic User Interface) type steady-state and transient performance simulation model of the PW206C turbo shaft engine that was adopted for use on the Smart UAV was developed using SIMULINK for performance analysis. For the simulation model, firstly the component maps including compressor, gas generator turbine and power turbine were inversely generated from manufacturer’s limited performance deck data by Hybrid Method. For the work and mass flow matching between components of the steady-state simulation, the state-flow library of SIMULINK was applied. The proposed steady-state performance model can simulate off-design point performance at various flight conditions and part loads, and in order to evaluate the steady-state performance model their simulation results were compared with manufacturer’s performance deck data. According to comparison results, it was confirm that the steady-state model well agreed with the deck data within 3% in all flight envelop. In the transient performance simulation model, the CMF (Continuity of Mass Flow) method was used and the rotational speed change was calculated by integrating the excess torque due to the transient fuel flow change using Runge-Kutta method. In this transient performance simulation, the turbine overshoot was predicted.


Author(s):  
R. W. Ball

The gas turbines owned and operated by utilities throughout the world burn expensive fuels and are under-utilised. Much research work has been done into burning cheaper, alternative fuels. The range of alternative fuels that are available is extensive and the gas turbine can be adapted to burn most of them. The adaptation process will cost the utility money, the pay back period for which depends on the utilisation of the modified plant. Modification of gas turbine plant to burn acceptable fuels can delay purchase of new plant. No major problems are envisaged in the modification of gas turbine plant operated in New Zealand.


Author(s):  
F. R. Spurrier

A gas-turbine engine employed as the main propulsion plant in a ship must satisfy design requirements which differ considerably from those for other turbine applications. The design objectives in a gas-turbine plant for application to naval vessels of medium displacement are discussed in this paper. Such vessels, notably escort types, have duty profile characteristics which demand relatively short periods of operation at maximum power, and long periods at small percentages of maximum power. Normal cruising power may be only 15 per cent of the maximum available but economy of operation must be assured at this condition. In this respect, such engines introduce problems which do not arise in commercial vessels or aircraft-machines, where most of the operating life is spent at high percentages of the maximum available power.


Author(s):  
D. H. Benn

Methods of mathematical analysis are reviewed for defining and numerically computing the reliability of warship propulsion systems. Experimental analysis is made of a twin-screw all-gas-turbine plant design for a small warship and the results are compared with computed figures previously published for a geared-steam-turbine plant. It is apparent that relatively simple arrangement of components in subsystems is an inherent advantage of the gas turbine plant from the reliability standpoint and that this type of plant has a potential for high reliability. The analysis was made possible by the availability of component MTBF figures taken from past experience. It is hoped that this will encourage users of marine propulsion equipment to compile and present additional reliability statistics and possibly complete reliability analyses of propulsion plants currently in service.


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