bluuebunny/crossref_metadata_2025 huggingface dataset:
Design and Evaluation of an LCV Combustor for the Volvo VT4400 Industrial Gas Turbine
Authors: Eriksson Pontus , Walsh Steve , Gabrielsson Rolf , Waldheim Lars , Hermann Fredrik
Published: February 2009

A combustor has been developed to burn a low calorific gas mixture reflecting a composition typically available from a bio-mass gasification plant. This reference composition contained (by volume) 11,7% H2, 15,4% CO, 5,9% CH4, 13,3% CO2, 46,7% N2 and 7% H2O. The combustor was subsequently tested with gas compositions having varying amounts of NH3, H2O and CO/H2 content. It was also tested with three compositions rich in CO, but lacking H2; these are typically available from blast furnace, or other metallurgical processes. The combustor is designed to be stoichiometric/lean and is suitable for up to 2,1 MW thermal input. The flame tube walls are predominantly effusion-cooled. A natural gas pilot is provided for ignition and operation up to 20% load. UHC emissions were only seen when operating on the reference LCV composition below 40% load. CO emissions were less than 20 ppmv between 40% and 100% load regardless of gas composition tested. Combined thermal and prompt NOX, when operating without ammonia addition, was found to be less than 9 ppmv at full load for the reference gas. When ammonia was introduced to the gas composition the molar ammonia conversion to NOX was approximately 60% for 2500 ppmv NH3 fuel concentration. This was seen to increase to 90% as the ammonia concentration was reduced to 500 ppmv. The combustor showed acceptable temperatures while operating on the reference composition. The compositions having higher net calorific value produced excessive flame tube temperatures. The combustor had excellent combustion stability regardless of gas composition and operating condition.
Sector Tests of a Low NOx, Lean-Direct-Injection, Multipoint Integrated Module Combustor Concept
Authors: Tacina Robert , Wey Changlie , Laing Peter , Mansour Adel
Published: February 2009

Results of a low-NOx combustor test with a 15° sector are presented. A multipoint, lean-direct injection concept is used. The configuration tested has 36 fuel injectors and fuel-air mixers in place of a dual annular arrangement of two conventional fuel injectors. An integrated-module approach is used for the construction where chemically etched laminates that are diffusion bonded, combine the fuel injectors, air swirlers and fuel manifold into a single element. Test conditions include inlet temperatures up to 866K, and inlet pressures up to 4825 kPa. The fuel used was Jet A. A correlation is developed relating the NOx emissions to the inlet temperature, inlet pressure, and fuel-air ratio. Using a hypothetical 55:1 pressure-ratio engine, cycle NOx emissions are estimated to be less than 40% of the 1996 ICAO standard.
The Optimisation of Reaction Rate Parameters for Chemical Kinetic Modelling Using Genetic Algorithms
Authors: Elliott L. , Ingham D. B. , Kyne A. G. , Mera N. S. , Pourkashanian M. , Wilson C. W.
Published: February 2009

It is well recognised that many important combustion phenomena are kinetically controlled. Whether it be the burning velocity of a premixed flame, the formation of pollutants in an exhaust stack or the conversion of NO to NO2 in a gas turbine combustor, it is important that a detailed chemical kinetic approach be undertaken in order to fully understand the chemical processes taking place. This study uses a genetic algorithm to determine new reaction rate parameters (A’s, β’s and Ea’s in the Arrhenius expressions) for the combustion of both a hydrogen/air and methane/air mixture in a perfectly stirred reactor. In both cases, output species profiles obtained from an original set of rate constants are reproduced by a new different set obtained using a genetic algorithm inversion process. The new set of rate constants lie between predefined boundaries (±25% of the original values) which in future work can be extended to represent the uncertainty associated with experimental findings. In addition, this powerful technique may be used in developing reaction mechanisms whose newly optimised rate constants reproduce all the experimental data available, enabling a greater confidence in their predictive capabilities. The results of this study therefore demonstrate that the genetic algorithm inversion process promises the ability to assess combustion behaviour for fuels where the reaction rate coefficients are not known with any confidence and, subsequently, accurately predict emission characteristics, stable species concentrations and flame characterisation. Such predictive capabilities will be of paramount importance within the gas turbine industry.
The Premixed Conditional Moment Closure Method Applied to Idealized Lean Premixed Gas Turbine Combustors
Authors: Martin Scott M. , Kramlich John C. , Kosa´ly George , Riley James J.
Published: February 2009

This paper presents the premixed Conditional Moment Closure (CMC) method as a new tool for modeling turbulent premixed combustion with detailed chemistry. By using conditional averages the CMC method can more accurately model the affects of the turbulent fluctuations of the temperature on the reaction rates. This provides an improved means of solving a major problem with traditional turbulent reacting flow models, namely how to close the reaction rate source term. Combined with a commercial CFD code this model provides insight into the emission formation pathways with reasonable runtimes. Results using the full GRI2.11 methane kinetic mechanism are compared to experimental data for a backward facing step burning premixed methane. This model holds promise as a design tool for lean premixed gas turbine combustors.
Validation of a Flamelet Approach to Modelling 3-D Turbulent Combustion Within an Airspray Combustor
Authors: Kyne A. G. , Pourkashanian M. , Wilson C. W. , Williams A.
Published: February 2009

Over the past two decades Computational Fluid Dynamics (CFD) has become increasingly popular with the gas turbine industry as a design tool. By applying CFD techniques during the early stages of designing a product, engineers can establish the key parameters and dimensions of a system before any experimental trial and error tests are made, thus reducing the product cycle time and costs. This study compares CFD predictions with a comprehensive set of experimental measurements made at QinetiQ on the combustion of aviation fuel within a modem airspray combustor. The performances of two separate models describing the chemical interactions are compared. First, an equilibrium model was employed and linked to the 3D commercial solver, FLUENT 5.5, through a mixture fraction/PDF lookup table approach. Similarly a flamelet model was implemented using a recently developed detailed chemical reaction mechanism describing aviation fuel combustion which has previously received rigorous testing with regard to its predictive performance over a wide range of combustion conditions (Patterson et al., 2001). Both cases predicted heat transfer through a new non-adiabatic PDF lookup table generator developed within the department. This allowed the implementation of a discrete phase model that treats the fuel entering the combustor as a fine liquid spray before evaporating and arriving in the gaseous phase. Two turbulence models (k-ε and Reynolds Stress models) were also used and the results of each compared.
Numerical Simulation of Flame Propagation in a Staged Combustor
Authors: Tsuru Tomoko , Imamura Akira , Kinoshita Yasuhiro , Nonaka Yoshiharu , Itoh Yuichi , Taniguchi Nobuyuki
Published: February 2009

Highly unsteady flow fields are generated in recent low-emissions gas turbine combustors. Numerical simulation of such flows using conventional numerical code using a time-averaged turbulence model is difficult and time-accurate LES (Large Eddy Simulation) is expected to predict them. Calculation of turbulent combusting and non-combusting flow field in a staged combustor were conducted using LES. To validate the LES calculation, a prediction of time-averaged velocity field is compared with those by an experiment and a conventional numerical method based on RANS model. Turbulence intensity affects flame speed so much that velocity fluctuations were measured to obtain turbulence intensity in the non-combustion test. Strongly turbulent regions between the pilot and main stages, which are important for the flame propagation, were simulated. The combustion was calculated using a laminar flamelet model and the flame propagating phenomenon was simulated properly, which is impractical by the conventional simulations using time-averaged turbulence models. The feasibility of the LES calculation is discussed.
Development of a Fuel and Air Mixer for an 11MW Gas Turbine Catalytic Combustion System
Authors: Corr Robert , Caron Tim , Barnes John , Meyer Stefan , Battaglioli John , Howell Tom , Dodge Paul
Published: February 2009

This paper describes a fuel and air mixer being developed for an 11 MW gas turbine catalytic combustion system. The fuel is natural gas. The mixer is based loosely on the radial-swirler design used in the XONON™-2.0 combustor, but has an axial swirler and inlet. Features have been incorporated in the design to make it resistant to flameholding. A combination of atmospheric testing and advanced CFD analysis have resulted in a design that is close to meeting its design targets of +/− 5% fuel to air uniformity, +/− 10°C thermal uniformity and 0.5% pressure loss. Modal and thermal stress finite element analyses have been incorporated in the development from its beginning phases to assure that the final design will meet life targets. This mixer is one of two alternative designs being considered for the production version of the catalytic combustion system.
Liquid Fuel Placement and Mixing of a Generic Aeroengine Premix Module at Different Operating Conditions
Authors: Becker Julian , Hassa Christoph
Published: February 2009

Fuel placement and air-fuel mixing in a generic aeroengine premix module employing plain jet liquid fuel injection into a counter-swirling double-annular crossflow were investigated at different values of air inlet pressure (6 bar, 700 K and 12 bar, 700 K) and liquid-to-air momentum flux ratio, both parameters being a function of engine power. Kerosene Jet A-1 was used as liquid fuel. Measurement techniques included LDA for investigation of the airflow and Mie-scattering laser light sheets and PDA for investigation of the two-phase flow. Measurements were taken at various axial distances from the fuel nozzle equivalent to mean residence times of up to 0.47 ms. It was found that the initial fuel placement reacts very sensitively to a variation of liquid-to-air momentum flux ratio. Susceptibility of the spray to dispersion due to centrifugal forces and to turbulent mixing is primarily a function of the fuel droplet diameters, which in turn depend on operating pressure. The data are interpreted by evaluation of the corresponding Stokes numbers.
CFD Modelling of Biogas Cofiring in a Gas Turbine
Authors: Lycklama a` Nijeholt J. A. , Komen E. M. J. , Hermanns R. T. E. , de Goey L. P. H. , van Beek M. C. , Verhage A. J. L.
Published: February 2009

Cofiring of biogas in existing gas turbines is a feasible option to reduce the consumption of natural gas. However, admixing of biogas will have an effect on the combustion process. As a consequence, the burning velocity and, therefore, the flame stability may be affected when a significant amount of biogas is mixed with the natural gas. The effect of admixing natural gas with biogas on the stability of the combustion process in lean premixed gas turbines is insufficiently known. In the present paper, a Computational Fluid Dynamics (CFD) methodology will be presented for the assessment of the safe limit of biogas cofiring in a gasturbine. An advanced Flamelet/Flamefront combustion model [1, 2, 3] and the Coherent Flame Model [4] are utilized. In both models, the detailed GRI 3.0 reaction mechanism [5] has been used to describe the combustion chemistry. The degree of mixing of fuel and air in the lean premix-burners of the gasturbine has been determined with a separate CFD model of the burners.
V64.3A Gas Turbine Natural Gas Burner Development
Authors: Hermsmeyer Heinrich , Prade Bernd , Gruschka Uwe , Schmitz Udo , Hoffmann Stefan , Krebs Werner
Published: February 2009

From the very first beginning of the V64.3A development the HR3 burner was selected as standard design for this frame. The HR3 burner was originally developed for the Vx4.2 and Vx4.3 fleet featuring silo combustors in order to mitigate the risk of flashback and to improve the NOx-emissions (Prade, Streb, 1996). Due to its favourable performance characteristics in the Vx4.3 family the advanced HR3 burner was adapted to the Vx4.3A series with annular combustor (hybrid burner ring – HBR). This paper reports about the burner development for V64.3A gas turbines to reach NOx emissions below 25 ppmvd and CO emissions below 10 ppmvd. It is described how performance and NOx emissions have been optimised by implementation of fuel system and burner modifications. The development approach, emission results and commercial operation experiences as well are described. The modifications of the combustion system were successfully and reliably demonstrated on commercially running units. NOx emissions considerably below 25ppmvd were achieved at and above design baseload. An outlook to further steps of V64.3A burner development in the near future will be given in this paper.
The Development of an Ultra Low Emissions Liquid Fuel Combustor for the OPRA OP16 Gas Turbine
Authors: Klein Sikke , Austrem Ivar , Mowill Jan
Published: February 2009

During the last few years OPRA has been working intensively on the development of an ultra low emissions combustor for the OP16 gas turbine. The main focus has been on the combustion of liquid fuels (diesel fuel #2), but a natural gas and a dual fuel system has also been developed. The most important aspect of the development has been the patented Controlled Fuel Air Ratio (COFAR) system incorporating the venturi premixer, the air valve and the fuel injection nozzle. The original diesel fuel injection nozzle of the OP16 was a hybrid design, comprising a pressure swirl central injector surrounded by a classic air-blast atomizer. While the emissions with this fuel nozzle were quite good (30 ppm up to 85% load), subsequent natural gas tests demonstrating single digit emissions, while running at a higher average flame temperature indicated that there was scope for improvement of the fuel preparation system. It was clear that atomization, evaporation and mixing of the diesel fuel could be further improved. For better understanding of the combustion of diesel fuel, an atomization and mixing model was developed, to study the quality of the fuel/air mixture leaving the pre-mixer. Based on the results of this study, a fuel nozzle system, using multipoint injection with small pressure swirl nozzles was selected. Three different sets of atomizers have been evaluated and a nozzle arrangement comprising five identical pressure swirl nozzles showed the best results. The emissions on diesel fuel with the new injector proved very satisfactory. The NOx concentration was kept below 25 ppm from 50% load up to 90% load and below 30 ppm at full load. CO and UHC were well below 10 ppm. These low emissions were achieved by running at a low flame temperature (below 1820K). Furthermore, no combustion dynamics or flame instability was observed.
Dynamic Modeling Results of a 1MW Molten Carbonate Fuel Cell/Gas Turbine Power System
Authors: Liese Eric , Gemmen Randall S.
Published: February 2009

A dynamic system model is presented for a 1 MW Molten Carbonate Fuel Cell/Gas Turbine (FC/GT) hybrid power generation system. Results are shown for both a fuel step reduction at the anode inlet, and a voltage step reduction to the fuel cell. Results showed significant thermal consequences at the cathode inlet for both perturbations. To mitigate these thermal consequences, methods of airflow management were examined and indicated that reducing the total gas turbine air flow worked better than an air bleed arrangement. As one option for air flow management, a control for the turbine speed was studied. These results are also presented showing that the thermal conditions are managed far better with such a control method.
Thermodynamic Performance Analysis of New Gas Turbine Combined Cycles With No Emissions of Carbon Dioxide
Authors: Gabbrielli R. , Singh R.
Published: February 2009

In the context of the reduction of the carbon dioxide (CO2) emissions as prescribed by the Kyoto protocol, this paper describes a thermodynamic performance analysis of new gas turbine combined cycles with no emissions of CO2 and nitrogen oxides. Three new similar cycles belonging to the same typology are proposed. These cycles use water/steam as working fluid, which is compressed in liquid and vapour phase, and the internal combustion process, which takes place between syngas and pure oxygen. The top Brayton cycle and the bottom Rankine cycle are integrated together. The syngas is produced by steam-natural gas reforming with internal chemical heat recovery. The CO2 produced in the combustion is captured simply by water condensation from the exhaust gas and liquefied to be stored. A simulation analysis has been performed to evaluate the net efficiency and the net specific work of the cycles. Varying the most important operative variables and using the least square regression and 2k factorial design techniques, a very large sensitivity analysis has permitted to highlight the performance behaviour of the cycles. Including the energy penalty due to the liquefaction of CO2 and to the oxygen production and adopting standard operative conditions, the LHV-based net efficiency and the net specific work may exceed 50% and 1000 kJ/kg, respectively.
Conceptual Design for an Industrial Prototype Graz Cycle Power Plant
Authors: Jericha H. , Go¨ttlich E.
Published: February 2009

The gas turbine system GRAZ CYCLE has been thoroughly studied in terms of thermodynamics and turbomachinery layout. What is to be presented here is a prototype design for an industrial size plant, suited for NG-fuel and coal and heavy fuel oil gasification products, capable to retain the CO2 from combustion and at the same time able to achieve maximum thermal efficiency. The authors hope for an international cooperation to make such a plant available within a few years.
Exergy Analysis of Part Flow Evaporative Gas Turbine Cycles: Part 2 — Results and Discussion
Authors: Jonsson Maria , Yan Jinyue
Published: February 2009

This paper is the second part of a two-part paper. The first part contains an introduction to the evaporative gas turbine (EvGT) cycle and the methods used in the study. The second part contains the results, discussion, and conclusions. In this study, exergy analysis of EvGT cycles with part flow humidification based on the industrial GTX100 and the aeroderivative Trent has been performed. In part flow EvGT cycles, only a fraction of the compressed air is passed through the humidification system. The paper presents and analyzes the exergetic efficiencies of the components of both gas turbine cycles. The highest cycle exergetic efficiencies were found for the full flow case for the GTX100 cycles and for the 20% part flow case for the Trent cycles. The largest exergy destruction occurs in the combustor, and the exergetic efficiency of this component has a large influence on the overall cycle performance. The exergy destruction of the heat recovery system is low.
Experimental and Theoretical Results of a Humidification Tower in an Evaporative Gas Turbine Cycle Pilot Plant
Authors: Lindquist Torbjo¨rn , Thern Marcus , Torisson Tord
Published: February 2009

The Evaporative Gas Turbine Pilot Plant has been in operation at Lund Institute of Technology in Sweden since 1997. In this cycle low-grade heat in the flue gases is utilized for water evaporation into the compressed air in the humidification tower. This result in, amongst others, power augmentation, efficiency increase and lower emissions. This article presents the experimental and theoretical results of the humidification tower, in which simultaneous heat and mass transfer occurs. A theoretical model has been established for the simultaneous heat and mass transfer occurring in the humidification tower and it has been validated with experiments. The humidification tower in the pilot plant can be operated at several operating conditions. An after-cooler makes it possible to chill the compressor discharge air before entering the humidification tower. The saturation temperature of the incoming compressed air can thereby be varied from 62 to 105 °C at the operating pressure of 8 bar(a). It has been shown that the air and water can be calculated throughout the column in a satisfactory way. The height of the column can be estimated with an error of 10% compared with measurements. The results from the model are most sensitive of the properties of the diffusion coefficient, viscosity and thermal conductivity due to the complexity of the polar gas mixture of water and air.
Novel EFHAT System With Enhancement of Humidification by Recovery of GT Exhaust Latent Heat
Authors: Jin Hongguang , Zhao Hongbin , Liu Zelong , Deng Shimin , Cai Ruixian
Published: February 2009

In this paper, we have proposed a new type of gas turbine cycle based on innovative combination of a newly designed HAT cycle with an externally fired boiler (EFHAT). In this manner, “dirty” fuels such as coal, biomass and etc. can be more efficiently used than before, and the water can be recovered. It is different from the conventional HAT cycle. In particular, the temperature of clean humid air discharging to atmosphere is not limited by the dew point, and the latent heat of steam can be utilized to generate hot water entering the humidifier. Therefore, the humidification ability is significantly enhanced, which is beneficial to improvement on system efficiency. As a result, with a gas turbine of 1073 K TIT, the net efficiency of the new system may reach as high as 43.0%. Furthermore, we have identified that air saturation can make a good temperature match in system, which results in effective utilization of both quality and quantity of energy at low and/or middle temperature range. With the principle of cascade utilization of energy and the methodology of system integration, we have opened up a new orientation for the clean coal power generation system.
Improved Gas Turbine Efficiency Through Alternative Regenerator Configuration
Authors: Dellenback Paul A.
Published: February 2009

An alternative configuration for a regenerative gas turbine engine cycle is presented that yields higher cycle efficiencies than either simple or conventional regenerative cycles operating under the same conditions. The essence of the scheme is to preheat compressor discharge air with high temperature combustion gases before the latter are fully expanded across the turbine. The efficiency is improved because air enters the combustor at a higher temperature, and hence heat addition in the combustor occurs at a higher average temperature. The heat exchanger operating conditions are more demanding than for a conventional regeneration configuration, but well within the capability of modern heat exchangers. Models of cycle performance exhibit several percentage points of improvement relative to either simple cycles or conventional regeneration schemes. The peak efficiencies of the alternative regeneration configuration occur at optimum pressure ratios that are significantly lower than those required for the simple cycle. For example, at a turbine inlet temperature of 1300°C (2370°F), the alternative regeneration scheme results in cycle efficiencies of 50% for overall pressure ratios of 22, whereas simple cycles operating at the same temperature would yield efficiencies of only 43.8% at optimum pressure ratios of 50, which are not feasible with current compressor designs. Model calculations for a wide range of parameters are presented, as are comparisons with simple and conventional regeneration cycles.
Part Load Behavior Optimization of Hybrid Coal and Gas Fired Combined Cycles Including Deactivation of Components
Authors: Ku¨hnel Janpeter , Abhari Reza S.
Published: February 2009

This paper presents a methodology to optimize the part load behavior of complex power plant cycles. As free optimization parameters the traditional continuous control parameter and the activation/deactivation of defined plant components are considered resulting in a mixed integer non-linear programming problems (MINLP). The procedure starts with a continuous process on either side of the non-linearity in part load, while refining the steps as it approaches the discontinuity. It is shown that good convergence around the non-linearity can be found with the present scheme. For part load operation a number of continuous and binary free optimization parameters are available creating a challenging optimization problem. The developed procedure is applied to a conventional steam cycle power plant, which is parallel repowered with a modern gas turbine. The resulting power plant layout is a hybrid coal and gas fired combined cycle. As objective function the maximized overall thermal efficiency and the minimized fuel costs are two examples chosen. Investigating the minimized fuel costs as the objective function the optimized operation strategy is found to be an unique function of the fuel price ratio between coal and gas for the chosen layout. Finally we show, that the operation strategy can be notably improved by considering the deactivation of cycle components for minimizing the fuel costs and for maximizing the cycle efficiency. For example the cycle efficiency can be improved up to 2% by deactivating the high pressure feed water preheating. The fuel costs are reduced by 20% for a particular load point by deactivating the gas turbine.
Noise Reduction From Engine Tests at Airports
Authors: Adkins Richard
Published: February 2009

A major cause of noise at airports are the run-up tests conducted after engine maintenance. The acoustic enclosures currently used to alleviate the problem are expensive and not very effective and can only be used during favorable wind conditions. Delays and complaints are commonplace. The reason why engines on stationary aircraft are at least twice as noisy as engines in flight is investigated and the findings used to propose more efficient and cost effective methods of noise reduction. This approach has also revealed a possible cause of premature and unexpected failure of combustors and turbines.
HTGR Closed Cycle GT Plant Analysis: Options and Procedures for Startup With Hot Gas Injection
Authors: Kumar K. N. Pradeep , Tourlidakis A. , Pilidis P.
Published: February 2009

The Starting up and Shutting down of a closed cycle gas turbine power plant needs special attention due to the inter-dependable nature of the components. Achieving self-sustainability in a fast and efficient way within the mechanical constraints is the challenge in the start-up of a closed cycle. The Nuclear reactor as the heat source will add more complexity to the system. The paper looks into the various options available for the start up and shutdown of a closed cycle Helium turbine using a gas cooled reactor as the heat source. A comparative analysis of these options is carried out by simulating various operating scenarios using a Transient Simulation Computer Programme especially prepared for an HTGR Project called PBMR (Pebble Bed Modular Reactor), which is being carried out in South Africa. The simulation was focused on the power conversion side of the plant, which includes all the Turbocompressors, Turbogenerator, Heat exchangers, Valves etc. Based on the analysis and its findings, an outline of a start up and shutdown procedure for a 3-shaft Closed Cycle Turbine Power Plant using hot gas injection is proposed in the paper.
Economic Feasibility of Fast Nuclear-Power Merchant Ships
Authors: Paramonov Dmitry V.
Published: February 2009

Expected doubling of marine trade within the next two decades, threats of global warming amplified by the increased consumption of fossil fuels, globalization of world economy resulting in growing need for rapid ocean transport of time sensitive freight, and recent rise in the fossil fuel prices prompted the Society of Naval Architects and Marine Engineers (SNAME) to initiate a study to examine power plant options for the next generation of high-speed merchant ships. Emerging nuclear power technologies, which might be applicable to such ships, including long core life light water reactors, heavy liquid metal cooled reactors, and gas cooled reactors are discussed. Results of a study comparing economic benefits of nuclear and conventional gas turbine merchant ship propulsion systems are reported. Finally, cost and performance characteristics that would make nuclear power a viable alternative for high-speed merchant ships are identified.
A New Tailpipe Design for GE Frame Type Gas Turbines to Substantially Lower Pressure Losses
Authors: Golomb Richard , Sahai Vivek , Cheng Dah Yu
Published: February 2009

Many GE frame gas turbines have a unique 90-degree tailpipe exhaust system that contains struts, diffusers, and turning vanes. As confirmed in a recent report by GE and other authors [1], it is known in the industry that this tailpipe design has large pressure losses. In this recent report a pressure loss as high as 60 inches of water (0.15 kgs/sqcm) was cited. Due to the flow separations they create, the report indicates that the struts can cause very high-pressure losses in the turbine. The report also states that these pressure losses can vary with different turbine load conditions. Cheng Fluid Systems and Cheng Power Systems have conducted a study aimed at substantially reducing these pressure losses. Flow control technology introduced to the refinery industry, i.e., the Cheng Rotation Vane (CRV) and the Large Angle Diffuser (LAD) can be used to mitigate the flow separation and turbulence that occurs in turns, bends, and large sudden expansions. Specifically the CRV addresses the flow separations in pipe turns, and the LAD addresses the flow problems that occur with large sudden expansion areas. The paper will introduce the past experience of the CRV and LAD, and will then use computer simulations to show the flow characteristics around a new design. First, the study meticulously goes through the entire GE exhaust system, starting with the redesign of the airfoil shape surrounding the struts. This new design has a larger angle of attack and minimizes the flow separations over a much wider operating range. Second, the pros and cons of the concentric turning vanes are studied and it is shown that they are more flow restrictive, rather than flow enhancing. Third, it is shown that the highly turbulent rectangular box type exhaust ducting design, substantially contributes to high noise levels and pressure losses. In this paper a completed design will be shown that incorporates a new airfoil shape for the struts, and by using CRV flow technology in combination with the LAD flow technology, the pressure recovery can be enhanced. If the pressure losses could be reduced by 40 inches of water (0.10 kgs/sqcm), the turbine efficiency could be increased by 5%, and the power output could be increased by 6%.
Universal Electric Machine for the Start-Up and Power Generation of Large Frame Size Gas Turbines
Authors: Cheng Dah Yu , Nelson Albert L. C.
Published: February 2009

The Universal Electric Machine (UEM) separates the speed of the magnetic field on the rotor from the mechanical speed of the rotor. This fundamental ability has numerous consequences that are very appealing in the power industry. The UEM is capable of generating AC power at a frequency that is independent of the mechanical drive speed on the rotor. Thus the UEM generator is a single product that can efficiently convert power into either 50 Hz or 60 Hz regardless of prime mover speed. The UEM maintains a steady-state frequency through a load transient, however severe, from full load to no load or vice versa. As a motor, the UEM uses this same ability to control speed independently of line frequency. The UEM simulates the torque-rpm characteristics of a large mechanical prime mover as the torque increases with mechanical speed. The UEM is capable of automatic synchronization of the electrical output/input to the power source, in frequency, phase angle and voltage. Finally by using modern power electronics, the configuration of the machine is brushless. These properties are ideally suited for both startup and power generation of large gas turbines. The UEM is under development and testing. A patent has been granted in the United States and international patent applications are being submitted.
Integration of Gas Turbine Education in an Undergraduate Thermodynamics Course
Authors: Albert Blace C. , Arnas A. O¨zer
Published: February 2009

The mission of the United States Military Academy (USMA) is “To educate, train, and inspire the Corps of Cadets so that each graduate is a commissioned leader of character committed to the values of Duty, Honor, Country; professional growth throughout a career as an officer in the United States Army; and a lifetime of selfless service to the nation.” [1] In order to accomplish this mission, USMA puts their cadets through a 47-month program that includes a variety of military training, and college courses totaling about 150 credit-hours. Upon completion of the program, cadets receive a Bachelor of Science degree and become Second Lieutenants in the United States Army. A very unique aspect of the academic program at USMA is that each cadet is required to take a minimum of five engineering classes regardless of their major or field of study. This means that about 500 cadets will have taken the one-semester course in thermodynamics. The thermodynamics course taught at USMA is different from others throughout the country because within every class there is a mixture of cadets majoring in engineering and those that are in other majors, i.e. languages, history [2]. Topics on gas turbine machinery have been integrated into this unique thermodynamics course. Because the cadets will encounter gas turbines throughout their service in the Army, we feel that it is important for all of the students, not just engineering majors, to learn about gas turbines, their operation, and their applications. This is accomplished by four methods. The first is in a classroom environment. Cadets learn how actual gas turbines work, how to model them, and learn how to solve problems. Thermodynamics instructors have access to several actual gas turbines used in military applications to aid in cadet learning. The second method occurs in the laboratory where cadets take measurements and analyze an operational auxiliary power unit (APU) from an Army helicopter. The third method occurs in the form of a design project. The engineering majors redesign the cogeneration plant that exists here at West Point. Many of them use a topping cycle in this design. The final method is a capstone design project. During the 2001–02 academic year, three cadets are improving the thermodynamic laboratories. Among their tasks are designing a new test stand for the APU, increasing the benefit of the gas turbine laboratory through more student interaction, and designing a web-based gas turbine pre-laboratory instruction to compliment the actual laboratory exercise.
A Rotating Machinery Course at Virginia Tech Developed With Industry Support
Authors: Kasarda Mary E. F.
Published: February 2009

This paper describes an undergraduate course on rotating machinery that has been developed at Virginia Tech with the close collaboration of an industry partner, the Bently Nevada Corporation. The course is offered as a technical elective in the Department of Mechanical Engineering for undergraduate students at the senior level. The motivation for the development of the course was to give students the experience of applying some of their basic courses to real engineering scenarios while educating students in additional specialized issues associated with the operation, design, and maintenance of rotating machinery. The development of this course is novel in that multiple academic, industrial, and institutional resources are utilized to create real engineering experiences appropriate for the undergraduate classroom. Creating this type of learning experience at the senior level helps students translate their basic engineering skills into practical engineering skills in order to successfully address real engineering scenarios that are not always straightforward problems based on straightforward information. This paper describes some of the course details and how a diversity of resources is incorporated into an undergraduate course. It is hoped that the information presented here will facilitate more industry and academic collaborations for the benefits of future engineers and the discipline itself.
Robust Gas Turbine Design
Authors: Becker Bernard
Published: February 2009

Industrial gas turbines utilize numerous design features that cannot be implemented in jet aircraft turbines for weight reasons, but because of their straight-forward and robust nature trim costs and reduce both maintenance effort and operating risks. Regardless of manufacturer, the following design features, for example, have become the established industry standard: • single-shaft rotor; • 2 bearings at atmospheric pressure; • Journal bearing instead of ball bearings; • steel blading in the compressor. For the key components compressor, turbine, rotor, and combustion chamber of its 3A family (Fig. 1), Siemens has developed and tested additional features that reduce wear further and improve operational reliability. Operating experience gathered to date has shown that these features enable achievements of very high reliability and availability. Some of the measures described also contribute to enhanced output and efficiency.
Laser Weld Repair of Service Exposed IN738 and GTD111 Buckets
Authors: Frederick Greg , Gandy David , Stover J. T.
Published: February 2009

Repairs of gas turbine buckets (blades) are currently limited to the upper tip region of the airfoil where operating stresses are commonly low. This limitation is predicated upon the use of low strength welding filler materials and the use of high energy welding processes such as gas tungsten arc welding (GTAW). When bucket damage is located within parts of the airfoil subjected to higher stress levels, buckets are often scrapped or replaced, costing utilities/independent power producers millions of dollars. Advanced repair techniques which allow repairs at higher stress regions of the bucket airfoil will significantly reduce the need and costs of scrapping buckets. “Structural” repairs to higher stress areas of the airfoil will require the use of welding fillers with similar composition and strength to that of the bucket base alloy and improvements in repair processing.
Electric Power Generation Equipment Specification and Supply in the Rapidly Changing Global Regulatory Scene
Authors: Willey Lawrence D. , Chalfin Joel
Published: February 2009

The proliferation of new codes & standards for power generation equipment procurement, and their increased frequency of revision, contributes to an atmosphere of increasingly rapid change in global trade considerations. This dynamic environment has amplified intensely with each year, to an extent that the life cycle of a given standard is in many instances appreciably less than the delivery cycles of heavy machinery. Other issues are created by the slower pace of harmonization of codes & standards in the European Union (EU), US and elsewhere. These codes & standards cover requirements that include emissions, acoustics, and safety that exert pronounced effects on the design, manufacture, and integration of power plant components. Conformity assessment partnering and the importance of other expert interpretation services are a key component to successfully meeting evolving compliance requirements. Delivering Customer Fulfillment for the Order to Remittance (OTR) phase of a project must be circled back to the Inquiry to Order (ITO) front end of the business cycle for new proposals. Another interesting arena is the relationship of advanced prime mover design balanced with the need for standardization to meet these regulatory challenges in the face of high production volume. The typical power generation project cycle, measured in terms of years, coupled with the present high demand worldwide results in orders for equipment that in many cases can’t foresee regulatory requirements 2 to 3 years into the future. Examples include projects in the EU where the Pressure Equipment Directive (PED) and Atmospheres Explosive (ATEX) Directive have mandatory compliance dates of May 2002 and June 2003 respectively. Electric power generation Original Equipment Manufacturers (OEMs) and their suppliers must plan for and price into contracts compliance with these laws years before the equipment is built and shipped. This is further complicated by the interpretation of specific requirements and the definition of the OEM conformity assessment strategy. To rectify this situation, it is recommended that steps be initiated to accelerate the worldwide harmonization of technical standards. In addition, consideration for the delivery cycles and commissioning of new power plants must be included in the regulatory process and in setting the dates for mandatory compliance with regional law.
Long Term Verification Results and Reliability Improvement of M501G Gas Turbine
Authors: Maekawa A. , Akita E. , Akagi K. , Uemura K. , Fukuizumi Y. , Kallianpur V.
Published: February 2009

Large combined cycle power plants utilizing advanced gas turbine technology are in demand worldwide due to attractive $/kw installation and operating cost advantages. A combined cycle plant has been operating since 1997 to determine the long-term reliability and hot parts durability of 1,500 degree C class M501G gas turbine technology that utilizes steam cooling of the combustor hardware. The verification is being conducted at MHI’s in-house combined cycle verification power plant known as T-Point. The verification is conducted while dispatching power to a local utility to augment the summer peak demand period. The gas turbine has accumulated over 12,000 actual operating hours and 650 start/stop cycles since it is primarily applied under Daily Start and Stop (DSS) duty. To date the availability has been 98.6 per cent, where Availability is defined as the actual power supply hours over the demanded power supply hours. The DSS duty imposes severe thermal-mechanical conditions that also facilitate in the accelerated assessment of the long-term reliability and parts durability. During the initial period of verification nearly 1,800 items were checked with special instrumentation, and about 1,000 items continue to be monitored in order to better quantify the physics. This has been supplemented by annual detailed overhaul inspections of the hardware to compare the accuracy of the predictions versus actual condition. Such inspections also included the rotor after approx. 10,000 operating hours to verify the integrity of all the parts in the rotor train. The knowledge and experience from the long-term verification has enabled several improvements because of valuable quantified data. (e.g enhancements, steam cooling effectiveness, etc.) Such verification data is critical for being able to introduce steam-cooled technology in new land based advanced gas technologies such as “G” and “H” class. Those are also important steps in commercial introductions of the M501G and M701G steam cooled combustor technologies. This paper describes results from the verification of the new technology with respect to operation, and design enhancements focused at reliability and hot parts life durability improvement.
Humid Air NOx Reduction Effect on Liquid Fuel Combustion
Authors: Chen Alexander G. , Maloney Daniel J. , Day William H.
Published: February 2009

An experimental investigation was carried out at DOE NETL on the humid air combustion process using liquid fuel to determine the effects of humidity on pollutant emissions and flame stability. Tests were conducted at pressures of up to 100 psia (690 kPa), and a typical inlet air temperature of 860 °F (733 K). The emissions and RMS pressures were documented for a relatively wide range of flame temperature from 2440–3090 °F (1610 − 1970 K) with and without added humidity. The results show more than 90 percent reduction of NOx through 10 percent humidity addition to the compressed air compared with the dry case at the same flame temperature. The substantial reduction of NOx is due to a shift in the chemical mechanisms and cannot be explained by flame temperature reduction due to added moisture since the comparison was made for the same flame temperature.
Leading-Edge Film-Cooling Physics: Part I — Adiabatic Effectiveness
Authors: York William D. , Leylek James H.
Published: February 2009

A systematic, computational methodology was employed to study film cooling on a turbine airfoil leading edge. In this paper, numerical predictions are compared with surface effectiveness measurements from a code-validation quality experiment in the open literature, and a detailed discussion of the physical mechanisms involved in leading edge film cooling is presented. The leading edge model was elliptic in shape to accurately simulate a rotor airfoil, and other geometric parameters were in the range of current design practice for aviation gas turbines. Three laterally-staggered rows of cylindrical film-cooling holes were investigated. One row of holes was centered on the stagnation line, and the other rows were located 3.5 hole-diameters downstream, mirrored about the stagnation line. All holes had an injection angle of 20° with the surface, and a 90° compound angle (radial injection). The average blowing ratio was varied from 1.0 to 2.5, and the coolant-to-mainstream density ratio was 1.8 in all simulations. Converged and grid independent solutions were obtained using a high-quality, multi-topology grid with 3.6 million cells and a fully-implicit, pressure correction-based Navier-Stokes solver. Turbulence closure was obtained with a realizable k-ε model, which has been demonstrated to be especially effective in controlling spurious production of turbulent kinetic energy in regions of rapid, irrotational strain. The predictions of laterally averaged effectiveness agreed well with the experimental data, especially at low-range blowing ratios. Highly nonuniform coolant coverage was seen to exist downstream of the second row of holes, caused mainly by interaction between the two rows of jets and by a strong vortex that reduced the spread of coolant from the downstream row. The results of the present study demonstrate that computational methods can accurately model the highly-complex film-cooling flowfield in the stagnation region.