Gas Turbine Performance and Health Status Estimation Using Adaptive Gas Path Analysis

Author(s):  
Y. G. Li

In gas turbine operations, engine performance and health status are very important information for engine operators. Such engine performance is normally represented by engine airflow rate, compressor pressure ratios, compressor isentropic efficiencies, turbine entry temperature, turbine isentropic efficiencies, etc., while the engine health status is represented by compressor and turbine efficiency indices and flow capacity indices. However, these crucial performance and health information cannot be directly measured and therefore are not easily available. In this research, a novel Adaptive Gas Path Analysis (Adaptive GPA) approach has been developed to estimate actual engine performance and gas path component health status by using gas path measurements, such as gas path pressures, temperatures, shaft rotational speeds, fuel flow rate, etc. Two steps are included in the Adaptive GPA approach, the first step is the estimation of degraded engine performance status by a novel application of a performance adaptation method, and the second step is the estimation of engine health status at component level by using a new diagnostic method introduced in this paper, based on the information obtained in the first step. The developed Adaptive GPA approach has been tested in four test cases where the performance and degradation of a model gas turbine engine similar to Rolls-Royce aero engine Avon-300 have been analyzed. The case studies have shown that the developed novel linear and nonlinear Adaptive GPA approaches can accurately and quickly estimate the degraded engine performance and predict the degradation of major engine gas path components with the existence of measurement noise. The test cases have also shown that the calculation time required by the approach is short enough for its potential online applications.

Author(s):  
Y. G. Li

In gas turbine operation, engine performance and health status is very important information for engine operators. Such engine performance is normally represented by engine air flow rate, compressor pressure ratios, compressor isentropic efficiencies, turbine entry temperature, turbine isentropic efficiencies, etc. while the engine health status is represented by compressor and turbine efficiency indices and flow capacity indices, etc. However, these crucial performance and health information can not be directly measured and therefore are not easily available. In this research, a novel Adaptive Gas Path Analysis (Adaptive GPA) approach has been developed to estimate actual engine performance and gas path component health status by using gas path measurements, such as gas path pressures, temperatures, shaft rotational speeds, fuel flow rate, etc. Two steps are included in the Adaptive GPA approach, the first step is the estimation of degraded engine performance status by a novel application of a performance adaptation method and the second step is the estimation of engine health status at component level by using a new diagnostic method introduced in this paper based on the information obtained in the first step. The developed Adaptive GPA approach has been tested in four test cases where the performance and degradation of a model gas turbine engine similar to Rolls-Royce aero engine AVON-300 have been analyzed. The case studies have shown that the developed novel linear and non-linear Adaptive GPA approach can accurately and quickly estimate the degraded engine performance and predict the degradation of major engine gas path components with the existence of measurement noise. The test cases have also shown that the calculation time required by the approach is short enough for its potential online applications.


Author(s):  
Ericcson Ramadhan ◽  
Yi-Guang Li ◽  
Deplian Maherdianta

Abstract The gas turbine inspection activities provided by the manufacturers and user maintenance scheme may be different from each other. To accommodate the difference, performing engine diagnostic as a condition-based monitoring technique is necessary to support Asset Performance Management (APM) adopted by the gas turbine users to improve the scheme. This paper provides an application of a novel Adaptive Gas Path Analysis (Adaptive GPA) to diagnose performance and health condition of a GE industrial gas turbine MS5001PA operated by PT Pupuk Kaltim (PKT). In the application, an engine thermodynamic model is constructed, adapted, and validated on the actual engine performance based on its gas path measurements. To estimate the health condition from the degraded engine data, two steps are applied in the Adaptive GPA diagnostic process. The first step is the estimation of degraded engine performance status and the second step is the prediction of engine health status at the gas turbine component level. Adaptive GPA results show that satisfactory predictions of the engine degradation have been achieved. In other words, the compressor has been predicted 5.56% degradation in flow capacity and 4.26% degradation in efficiency respectively, which is an indication of compressor fouling. Combining the diagnostic results, manufacturer’s recommendations, and user maintenance strategy, it is relatively safe and allowable to increase the maintenance inspection interval from 12,000 to 16,000 hours. Therefore, the adaptive GPA is proven to be beneficial to support condition-based maintenance decisions.


Author(s):  
Vahid Noei Aghaei ◽  
Hiwa Khaledi ◽  
Mohsen Reza Soltani

Performance testing of gas turbine packages is becoming increasingly common to assure that the turbine output power and efficiency meet the expected values during the turbine life cycle. In the conventional Performance Test Analysis (PTA), field measurements and calculations are carried out on the basis of standard codes to find the whole engine performance parameters (i.e. power and efficiency) at test conditions and to compare them with the expected values. Recently, regarding the development of Gas Path Analysis (GPA) and diagnostic techniques to investigate the gas turbine health state, performance test capabilities can be improved by using these analyses to perform further examination on the measured test data and to determine the deviation of gas turbine component health parameters from the “new and clean” health state during the engine operation. Determining the mentioned deviations, potentials of engine improvement in the component level can be obtained and subsequently the action-oriented recommendations are reported as guidelines in the overhaul. Also in the case of performance test after the overhaul, the main result of the GPA application in PTA is the verification of the overhaul effectiveness. Using the GPA in the cases studied in this paper indicates that heath state of engine components can be investigated from the performance test data and as the main result, it is show that applying the GPA, it is possible to distinguish the effect of non-recoverable degradation and that of the poor overhaul on the engine performance and finally to assess technically the effectiveness of overhaul.


Author(s):  
Y. G. Li

Accurate estimation of performance status of a gas turbine engine at certain ambient and operating condition based on measured gas path parameters is very important for both engine designers and users alike. It could be a very challenging task for engine performance engineers to estimate the value of component design parameters in order to match measured gas path parameters when the number of design point component parameters and the number of measurable performance parameters become large. Such status estimation can be used to distinguish the performance difference among fleet engines and build accurate engine models at an artificial design point for individual engines, which is also crucially important for gas path diagnostic analysis. In this paper, a gas turbine design point performance adaptation approach based on the integration of gas turbine thermodynamic performance modelling and a Genetic Algorithm has been developed in order to estimate the design point component parameters and match the available gas path measurements of real engines. In the approach, the initially unknown component parameters may be compressor pressure ratios and efficiencies, turbine entry temperature, turbine efficiencies, air mass flow rate, cooling flows, by-pass ratio, etc. The engine measurable performance parameters may be thrust and specific fuel consumption for aero engines, shaft power and thermal efficiency for industrial engines, gas path pressures and temperatures, etc. The developed adaptation approach has been applied to a design point performance status estimation of an industrial gas turbine engine GE LM2500+ operating in Manx Electricity Authority (MEA), UK. The application shows that the adaptation approach is very effective and robust in producing a model engine that matches the actual engine performance with acceptable computation speed. Theoretically the developed techniques can be applied to different gas turbine engines.


Author(s):  
P. A. Phillips ◽  
Peter Spear

After briefly summarizing worldwide automotive gas turbine activity, the paper analyses the power plant requirements of a wide range of vehicle applications in order to formulate the design criteria for acceptable vehicle gas turbines. Ample data are available on the thermodynamic merits of various gas turbine cycles; however, the low cost of its piston engine competitor tends to eliminate all but the simplest cycles from vehicle gas turbine considerations. In order to improve the part load fuel economy, some complexity is inevitable, but this is limited to the addition of a glass ceramic regenerator in the 150 b.h.p. engine which is described in some detail. The alternative further complications necessary to achieve satisfactory vehicle response at various power/weight ratios are examined. Further improvement in engine performance will come by increasing the maximum cycle temperature. This can be achieved at lower cost by the extension of the use of ceramics. The paper is intended to stimulate the design application of the gas turbine engine.


Author(s):  
Peter D. Smout ◽  
Steven C. Cook

The determination of gas turbine engine performance relies heavily on intrusive rakes of pilot tubes and thermocouples for gas path pressure and temperature measurement. For over forty years, Kiel-shrouds mounted on the rake body leading edge have been used as the industry standard to de-sensitise the instrument to variations in flow incidence and velocity. This results in a complex rake design which is expensive to manufacture, susceptible to mechanical damage, and difficult to repair. This paper describes an exercise aimed at radically reducing rake manufacture and repair costs. A novel ’common cavity rake’ (CCR) design is presented where the pressure and/or temperature sensors are housed in a single slot let into the rake leading edge. Aerodynamic calibration data is included to show that the performance of the CCR design under uniform flow conditions and in an imposed total pressure gradient is equivalent to that of a conventional Kiel-shrouded rake.


Author(s):  
V. Pachidis ◽  
P. Pilidis ◽  
I. Li

The performance analysis of modern gas turbine engine systems has led industry to the development of sophisticated gas turbine performance simulation tools and the utilization of skilled operators who must possess the ability to balance environmental, performance and economic requirements. Academic institutions, in their training of potential gas turbine performance engineers have to be able to meet these new challenges, at least at a postgraduate level. This paper describes in detail the “Gas Turbine Performance Simulation” module of the “Thermal Power” MSc course at Cranfield University in the UK, and particularly its practical content. This covers a laboratory test of a small Auxiliary Power Unit (APU) gas turbine engine, the simulation of the ‘clean’ engine performance using a sophisticated gas turbine performance simulation tool, as well as the simulation of the degraded performance of the engine. Through this exercise students are expected to gain a basic understanding of compressor and turbine operation, gain experience in gas turbine engine testing and test data collection and assessment, develop a clear, analytical approach to gas turbine performance simulation issues, improve their technical communication skills and finally gain experience in writing a proper technical report.


Author(s):  
SS Talebi ◽  
AM Tousi ◽  
A Madadi ◽  
M Kiaee

Recently, the utilization of micro gas turbines in smart grids are rising that makes the part-load operation principal situation of the engine service. This leads to faster life consumption that increases the importance of the diagnostics process. Gas path analysis is an effective method for gas turbine diagnostics. Complex dynamics of gas turbine induces challenging conditions to perform applicable gas path analysis. This study aims to facilitate MGT gas path diagnostics through reducing the number of monitoring parameters and preparation a pattern for engine level and component level health assessment in both full and part load operation of a recuperated micro gas turbine. To attain this goal a model is proposed to simulate MGT off-design performance which is validated against experimental data in healthy and degraded operation modes. Fouling in compressor, turbine and recuperator and erosion in compressor and turbine as the most common degradations in the gas turbine are considered. The fault simulation is performed by changing the health parameters of gas path components. According to the result investigation, a matrix comprises deviation contours of four parameters, Power, fuel flow, compressor discharge pressure, and exhaust gas temperature is presented and analyzed. The analysis shows that monitoring these parameters makes it possible to perform engine level and component level diagnostics through evaluating a binary code (generated by mentioned parameter variations) against the fault effects pattern in different load fractions and fault severities. The simulation also showed that the most power drop occurred under the compressor fouling by about 8.7% while the most reduction in thermal efficiency is observed under recuperator fouling by about 7.84%. Furthermore, the investigation showed the maximum decrease in the surge margin induced by the compressor fouling during the lower part-load operation by about 45.7% while in the higher loads created by the turbine fouling by about 14%.


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