Improving Gas Turbine Performance Through Reassembling Degraded Components: An Experimental and Computational Study

Author(s):  
Shuocheng Xia ◽  
Zhongran Chi ◽  
Shusheng Zang ◽  
Hui Wang

Abstract Performance degradation of gas turbine is a common phenomenon during operation. Maintenance of the degraded gas turbines and improving their performance at a low cost are important in engineering. In this paper, the maintenance method based on reassembling degraded components of existing gas turbines was studied. This research was based on a type of 2MW gas turbine engine. Blue ray scanning was carried out to rebuild the 3D flow-path geometries of the compressor and turbine of a degraded engine. Then CFD simulations were carried out to compare the characteristic maps of new and degraded components. Secondly, performance tests of six engines were carried out. A correction method was developed to get the specific component characteristics using test data, which can also analyze and quantify the degradations. Also, a gas turbine performance prediction program was used to find the promising component-exchange plan within 5 given gas turbines to improve total thermal efficiency. Finally, additional test was carried out to verify the performance of the reassembled gas turbine. Through the developed method including 3D scanning, CFD simulation, and correction of component characteristics with engine test data, the component performance degradation of a specific gas turbine can be obtained in quantity. The gas turbine performance predictions based on the acquired characteristic maps showed good agreement with test data. With the help of the method developed in this work, a new gas turbine engine was obtained through exchanging the components of degraded engines, which is at a very low cost and in a short time. The improvement in total thermal efficiency was about 0.3 percentage, which was verified by engine tests.

Author(s):  
J. D. MacLeod ◽  
W. Grabe

The Machinery and Engine Technology (MET) Program of the National Research Council of Canada (NRCC) has established a program for the evaluation of sensors to measure gas turbine engine performance accurately. The precise measurement of fuel flow is an essential part of steady-state gas turbine performance assessment. Prompted by an international engine testing and information exchange program, and a mandate to improve all aspects of gas turbine performance evaluation, the MET Laboratory has critically examined two types of fuel flowmeters, Coriolis and turbine. The two flowmeter types are different in that the Coriolis flowmeter measures mass flow directly, while the turbine flowmeter measures volumetric flow, which must be converted to mass flow for conventional performance analysis. The direct measurement of mass flow, using a Coriolis flowmeter, has many advantages in field testing of gas turbines, because it reduces the risk of errors resulting from the conversion process. Turbine flowmeters, on the other hand, have been regarded as an industry standard because they are compact, rugged, reliable, and relatively inexpensive. This paper describes the project objectives, the experimental installation, and the results of the comparison of the Coriolis and turbine type flowmeters in steady-state performance testing. Discussed are variations between the two types of flowmeters due to fuel characteristics, fuel handling equipment, acoustic and vibration interference and installation effects. Also included in this paper are estimations of measurement uncertainties for both types of flowmeters. Results indicate that the agreement between Coriolis and turbine type flowmeters is good over the entire steady-state operating range of a typical gas turbine engine. In some cases the repeatability of the Coriolis flowmeter is better than the manufacturers specification. Even a significant variation in fuel density (10%), and viscosity (300%), did not appear to compromise the ability of the Coriolis flowmeter to match the performance of the turbine flowmeter.


1995 ◽  
Vol 117 (1) ◽  
pp. 132-137 ◽  
Author(s):  
J. D. MacLeod ◽  
W. Grabe

The Machinery and Engine Technology (MET) Program of the National Research Council of Canada (NRCC) has established a program for the evaluation of sensors to measure gas turbine engine performance accurately. The precise measurement of fuel flow is an essential part of steady-state gas turbine performance assessment. Prompted by an international engine testing and information exchange program, and a mandate to improve all aspects of gas turbine performance evaluation, the MET Laboratory has critically examined two types of fuel flowmeters, Coriolis and turbine. The two flowmeter types are different in that the Coriolis flowmeter measures mass flow directly, while the turbine flowmeter measures volumetric flow, which must be converted to mass flow for conventional performance analysis. The direct measurement of mass flow, using a Coriolis flowmeter, has many advantages in field testing of gas turbines, because it reduces the risk of errors resulting from the conversion process. Turbine flowmeters, on the other hand, have been regarded as an industry standard because they are compact, rugged, reliable, and relatively inexpensive. This paper describes the project objectives, the experimental installation, and the results of the comparison of the Coriolis and turbine-type flowmeters in steady-state performance testing. Discussed are variations between the two types of flowmeters due to fuel characteristics, fuel handling equipment, acoustic and vibration interference, and installation effects. Also included in this paper are estimations of measurement uncertainties for both types of flowmeter. Results indicate that the agreement between Coriolis and turbine-type flowmeters is good over the entire steady-state operating range of a typical gas turbine engine. In some cases the repeatability of the Coriolis flowmeter is better than the manufacturer’s specification. Even a significant variation in fuel density (10 percent), and viscosity (300 percent) did not appear to compromise the ability of the Coriolis flowmeter to match the performance of the turbine flowmeter.


1976 ◽  
Author(s):  
I. J. Ushiyama ◽  
N. Matsumoto

In designing the gas turbine engine, it is important to know the rough relationship between the specific output, thermal efficiency, and pressure ratios before setting about calculating the practical cycle. In general, the specific output and the thermal efficiency have their maximum values at certain pressure ratios. The pressure ratios for these maximum values, however, differ in the case of the specific output from the thermal efficiency even in the same type of gas turbine. This paper presents the equations for the optimum pressure ratios of the specific output and thermal efficiency which are obtained for seven types of single-shaft gas turbines. Furthermore, a change in the forms of the curves is made clear by the numerical calculations for the specific output and thermal efficiency near the range of optimum pressure ratios. From the results of this paper, the optimum pressure ratios for every type of single-shaft gas turbine can be easily determined from the thermodynamical point of view.


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):  
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):  
J. D. MacLeod ◽  
B. Drbanski

The Engine Laboratory of the National Research Council of Canada (NRCC), with the assistance of Standard Aero Ltd., has established a program for the evaluation of component deterioration on gas turbine engine performance. As part of this project, a study of the effects of turbine rebuild tolerances on overall engine performance was undertaken. This study investigated the range of performance changes that might be expected for simply disassembling and reassembling the turbine module of a gas turbine engine, and how these changes would influence the results of the component fault implantation program. To evaluate the effects of rebuilding the turbine on the performance of a single spool engine, such as Allison T56 turboprop engine, a series of three rebuilds were carried out. This study was performed in a similar way to a previous NRCC study on the effects of compressor rebuilding. While the compressor rebuild study had found performance changes in the order of 1% on various engine parameters, the effects of rebuilding the turbine have proven to be even more significant. Based on the results of the turbine rebuild study, new methods to improve the assurance of the best possible tolerances during the rebuild process are currently being addressed. This paper describes the project objectives, the experimental installation, and the results of the performance evaluations. Discussed are performance variations due to turbine rebuilds on engine performance characteristics. As the performance changes were significant, a rigorous measurement uncertainty analysis is included.


1973 ◽  
Vol 95 (3) ◽  
pp. 191-198 ◽  
Author(s):  
D. J. White ◽  
P. B. Roberts ◽  
W. A. Compton

In recent years automotive engine emissions have become subject to stringent Federal legislation. The most severe of these regulations pertains to the 1976 Emission Standards as defined by the Advanced Automotive Power Systems (AAPS) Division of the Environmental Protection Agency (EPA). A unique combustor concept has been developed by Solar which has demonstrated the feasibility of meeting these emission requirements. The integrated emissions of a typical regenerative gas turbine engine employing this combustor type were each below one half of the levels specified by the Federal 1976 Standards, when tested over a simulated federal driving cycle. The success of the feasibility tests for this combustor concept has lead to more fundamental studies and the planned development of a prototype combustor for demonstration on the EPA-AAPS baseline gas turbine engine. The prototype combustor for the baseline engine is described together with its variable area port mechanisms, which has been demonstrated as necessary for emission control.


Author(s):  
J. H. Horlock ◽  
W. A. Woods

Earlier analytical and graphical treatments of gas turbine performance, assuming the working fluid to be a perfect gas, are developed to allow for ‘non-perfect’ gas effects and pressure losses. The pressure ratios for maximum power and maximum thermal efficiency are determined analytically; the graphical presentations of performance based on the earlier approach are also modified. It is shown that the optimum conditions previously determined from the ‘air standard’ analyses may be changed quite substantially by the inclusion of the ‘real’ effects.


Author(s):  
Ugo Campora ◽  
Mauro Carretta ◽  
Carlo Cravero

A simulation of performance degradation for an aeronautical gas turbine engine (Honeywell T55 L712) is presented. The effects of turbine (low and high pressure stages) erosion on the engine performance have been investigated in some detail. The behavior of the engine has been simulated using a dynamic model implemented in Matlab-Simulink. Using a throughflow code the LPT and HPT have been simulated and their performance maps have been obtained with a high level of accuracy. In order to understand the effects of turbine erosion nine degradation levels have been introduced and the LPT and HPT performance have been computed using the abovementioned throughflow code. The degradation levels have been based on stator erosion effects (increase of throat section and blade thickness reduction) only according to the experimental evidence from the engine tests from Piaggio Aero Industries. The introduction of the modified turbine characteristics into the Matlab-Simulink model has allowed the degradation effects on the overall engine performance to be tested and discussed. Finally, using experimental data from the industrial maintenance database, the link of each level of degradation with the number of the engine operational time (hours) has been obtained.


Author(s):  
J. Zelina ◽  
D. T. Shouse ◽  
J. S. Stutrud ◽  
G. J. Sturgess ◽  
W. M. Roquemore

An aero gas turbine engine has been proposed that uses a near-constant-temperature (NCT) cycle and an Inter-Turbine Burner (ITB) to provide large amounts of power extraction from the low-pressure turbine. This level of energy is achieved with a modest temperature rise across the ITB. The additional energy can be used to power a large geared fan for an ultra-high bypass ratio transport aircraft, or to drive an alternator for large amounts of electrical power extraction. Conventional gas turbines engines cannot drive ultra-large diameter fans without causing excessively high turbine temperatures, and cannot meet high power extraction demands without a loss of engine thrust. Reducing the size of the combustion system is key to make use of a NCT gas turbine cycle. Ultra-compact combustor (UCC) concepts are being explored experimentally. These systems use high swirl in a circumferential cavity about the engine centerline to enhance reaction rates via high cavity g-loading on the order of 3000 g’s. Any increase in reaction rate can be exploited to reduce combustor volume. The UCC design integrates compressor and turbine features which will enable a shorter and potentially less complex gas turbine engine. This paper will present experimental data of the Ultra-Compact Combustor (UCC) performance in vitiated flow. Vitiation levels were varied from 12–20% oxygen levels to simulate exhaust from the high pressure turbine (HPT). Experimental results from the ITB at atmospheric pressure indicate that the combustion system operates at 97–99% combustion efficiency over a wide range of operating conditions burning JP-8 +100 fuel. Flame lengths were extremely short, at about 50% of those seen in conventional systems. A wide range of operation is possible with lean blowout fuel-air ratio limits at 25–50% below the value of current systems. These results are significant because the ITB only requires a small (300°F) temperature rise for optimal power extraction, leading to operation of the ITB at near-lean-blowout limits of conventional combustor designs. This data lays the foundation for the design space required for future engine designs.


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