bluuebunny/crossref_metadata_2025 huggingface dataset:
Production of Simulated Gasified Biomass for Pilot Plant Applications
Authors: Duwig Christophe , Fredriksson Jan , Fransson Torsten
Published: July 2014

The design of modern Low Heating Value (LHV) fuel combustion devices, such as gas turbine combustors, relies heavily on numerical simulations. In addition, numerical predictions are always validated by experimental tests. In this work, an experimental facility was built. The fuel input power of the combustor was 300 kW. Such facility requires a gas flow of typically 0.06 kg/s, so a syngas production at a reasonable cost was required to undertake tests under real working conditions.

Within this work, an inexpensive and flexible syngas generator has been designed, produced and tested. The main idea was to use cheap available gas fuels and to crack it in order to obtain the syngas. Such conversion is heavily used in oil refineries and called “Steam Reforming”. Propane is used as a fuel and is cracked on a commercial steam reforming catalyst. To ensure the wanted ratio of C/H and C/O in the final product, CO2, H2O and air were added to the fuel gas. Catalytic cracking is needed as propane cracking kinetics are low at wanted operation temperatures, namely 900 to 1100 K. Care is taken to avoid carbon formation in the gasification device which may cause decomposition of the stainless steel reactor vessel.

The gasification device was used to feed a 300kW combustor at 2.8 bar pressure. The device was successfully integrated into a test rig and used for a burner study. The obtained composition was quite close to a typical gasified biomass composition. A wide range of different compositions has also been explored. Hydrocarbon concentration range was investigated from 3 vol% up to 16 vol% (Methane equivalent). The CO2 concentration varied between 13 vol% and 20 vol%. The syngas temperature was kept at an interval between 900 and 1100 K. The device provided 0.06 kg/s of a 3 to 5 MJ/kg heating value fuel. The operating costs of the gasification device were found about one tenth of the bottled gas price.
Pressurized Pilot-Scale Test Facility for Catalytic Combustion of Simulated Gasified Biomass: First Test Results
Authors: Jacoby J. , Strasser T. , Fransson T. , Thevenin P. , Järås S.
Published: July 2014

Gasified biomass has become an attractive fuel source for the production of electricity for various processes due to its potential to reduce the net CO2 emission. The overall aim is to combine biomass as a fuel source with high temperature catalytic combustion in order to lower emissions of nitrogen oxides, carbon monoxide and hydrocarbons.

This paper presents the design of a pressurized test facility for testing various catalytic materials under varying operating conditions and arrangements in the combustor. Instrumentation of the rig is described. Catalyst development and preparations are being described as well as the first results from the pilot-scale test facility. Different catalyst configurations and compositions have been tested.

It was shown that a Pd / LaAl11O18 catalyst is able to ignite the synthetic gasified biomass and that high conversion rates of H2 can be achieved with this type of catalyst. By applying a layer of barium stabilized alumina, thermal protection of the catalyst is achieved, hence limiting the maximum catalyst temperature.
Turbine Engine Performance Improvements: A Proactive Approach
Authors: Gastineau Zane D.
Published: July 2014

Turbine engine concepts for the future are placing ever-increasing demands on the design engineer. These future systems are seeking to increase performance while at the same time reduce costs. However, traditional engine design methods use large margins in the design process of a specific component in order to guarantee proper operation throughout the flight envelope over the life of the engine. These margins in fact reduce engine performance and increase the costs. In this paper, active control will be presented as one potential means of achieving the requirements for future turbine engines. In addition, specific active control applications will be discussed.
Internal Reforming Solid Oxide Fuel Cell Gas Turbine Combined Cycles (IRSOFC-GT): Part B — Exergy and Thermoeconomic Analyses
Authors: Massardo Aristide F. , Magistri Loredana
Published: July 2014

The aim of this work is to investigate the performance of Internal Reforming Solid Oxide Fuel Cell (IRSOFC) and Gas Turbine (GT) combined cycles.

A mathematical model of the IRSOFC steady-state operation was presented in Part A of this work (Massardo and Lubelli, 1998), coupled to the thermodynamic analysis of a number of proposed IRSOFC-GT combined cycles, taking into account the influence of several technological constraints.

In the second part of this work, both an exergy and a thermoeconomic analysis of the proposed cycles have been carried out using the TEMP code developed by the Author (Agazzani and Massardo, 1997). A suitable equation for IRSOFC cost evaluation based on cell geometry and performance has been proposed and employed to evaluate the electricity generation cost of the proposed combined systems.

The results are presented and the influence of several parameters is discussed: external reformer operating conditions, fuel to air ratio, cell current density, compressor pressure ratio, etc. Diagrams proposed by the Author (Massardo and Scialo’, 2000) for cost vs. efficiency, cost vs. specific work, and cost vs. system pressure are also presented and discussed.
Comparative Analysis of Hybrid Cycles Based on Molten Carbonate and Solid Oxide Fuel Cells
Authors: Campanari Stefano , Macchi Ennio
Published: July 2014

High temperature fuel cells are experiencing an increasing amount of attention thanks to the successful operation of prototype plants, including a multi-MW Molten Carbonate Fuel Cell (MCFC) demonstration plant and a hybrid Solid Oxide Fuel Cell (SOFC) gas turbine power plant. Both MCFCs and SOFCs are currently considered attractive for the integration with gas turbines in more complex “hybrid” plants, with projected performances that largely exceed combined cycles efficiencies even at a small-scale size and with an extremely low environmental impact.

This paper compares the performances of MCFC and SOFC hybrid cycles. The comparison shows some advantages for the SOFC hybrid cycle in terms of plant simplicity and moderately higher efficiency.
Modelling the Air-Cooled Gas Turbine: Part 1 — General Thermodynamics
Authors: Young J. B. , Wilcock R. C.
Published: July 2014

This paper is Part I of a study concerned with developing a formal framework for modelling air-cooled gas turbine cycles and deals with basic thermodynamic issues. Such cycles involve gas mixtures with varying composition which must be modelled realistically. A possible approach is to define just two components, air and gas, the latter being the products of stoichiometric combustion of the fuel with air. If these components can be represented as ideal gases, the entropy increase due to compositional mixing, although a true exergy loss, can be ignored for the purpose of performance prediction. This provides considerable simplification.

Consideration of three idealised simple cycles shows that the introduction of cooling with an associated thermal mixing loss does not necessarily result in a loss of cycle efficiency. This is no longer true when real gas properties and turbomachinery losses are included. The analysis clarifies the role of the cooling losses and shows the importance of assessing performance in the context of the complete cycle. There is a strong case for representing the cooling losses in terms of irreversible entropy production as this provides a formalised framework, clarifies the modelling difficulties and aids physical interpretation. Results are presented which show the effects on performance of varying cooling flowrates and cooling losses. A comparison between simple and reheat cycles highlights the rôle of the thermal mixing loss. Detailed modelling of the heat transfer and cooling losses is discussed in Part II of this paper.
Gas Turbine Performance of Mature, F- and Advanced Technologies 2000
Authors: von Rappard Axel W. , Della Villa Salvatore
Published: July 2014

The contribution of the gas turbine in simple and combined cycle systems to power production in the United States has been steadily rising over the past 25 years. In 1998 their contribution to power production was approximately 15% and it increased over the past 5 years by 1.5 to 2%, annually. In parallel, the United States Department of Energy (DOE) has financially supported Advanced Technology development with good formulated goals for overall performance of plants including reliability, availability and maintainability (RAM). In this paper the authors evaluate RAM performance data from power plants over the past five years. This evaluation can be used as baseline or benchmark for further improvements. It takes into account the mode of operation being base load, cycling or peaking application and analyses the power plant on a year-by-year evaluation. All RAM-data came from the same source and are collected and analyzed according to standardized procedures.

Availability will be reviewed for machines of different sizes and technologies. Maintainability will be analyzed as function of the size of units, energy production, and the mode of operation.

Gas turbine simple and combined cycle power plants have been operated in peaking, cycling, base and continuous load operation. The flexibility is shown in different “Service Hours per Successful Start” and a correlation with the RAM parameters. To analyze and explain these differences will be the main result of this evaluation. The contribution shall help to evaluate the best solution for individual sites because efficiency and availability cannot always be increased in parallel.
Advanced Gas Turbine Technology: ABB/BBC Historical Firsts
Authors: Eckardt Dietrich , Rufli Peter
Published: July 2014

During more than 100 years engineers of the Swiss development center of A.-G. BBC Brown, Boveri & Cie., from 1988 onwards ABB Asea Brown Boveri Ltd, in 1999 ABB ALSTOM POWER Ltd and now ALSTOM Power Ltd in Baden, Switzerland have significantly contributed to the achievement of todays advanced gas turbine concept. Numerous “Firsts” are highlighted in this paper — ranging from the first realization of the industrial, heavy-duty gas turbine in the 1930s to todays high-technology Gas Turbine (GT) products, combining excellent performance, extraordinary low environmental impact with commercial attractiveness for global power generation. Interesting connections could be unveiled for the early parallel development of industrial and areo gas turbines.
Testing the Latest Model V84.3A Gas Turbine in the Siemens Test Facility in Berlin
Authors: Frank Stefan L. F. , Lechner Christof , Mertens Bernward , Warnack Dieter
Published: July 2014

Since the end of 1998, the new V84.3A has been under investigation in the Siemens Gas Turbine Development and Manufacturing Center in Berlin. Especially for the testing of gas turbine prototypes, Siemens runs a test bed which allows full load tests with speed variations. Hence the engine can be tested at the extremes of real gas turbine operation conditions.

Within the range of the investigations there have been combustion optimization and performance tests at full and part load. A focus was the testing of various kinds of water injection. Additionally blade vibration measurements in the turbine and the compressor, surface temperature measurements using thermal paint and pyrometry, and aerodynamics measurements using five-hole probes have been performed.
The W501G Testing and Validation in the Siemens Westinghouse Advanced Turbine Systems Program
Authors: Gaul Gregory R. , Diakunchak Ihor S. , Dodd Alfred M.
Published: July 2014

The Siemens Westinghouse Advanced Turbine System (ATS) has the ultimate goal of achieving greater than 60% LHV-based net plant thermal efficiency, less than 10 parts per million NOx emissions, a 10% reduction in cost of electricity, and reliability-availability-maintainability (RAM) equivalent to modern advanced power generation systems. The ATS program, which is supported by the U.S. Department of Energy, introduces advanced technologies in three evolutionary steps to minimize risks and to increase the net benefits of the program. The W501G, the first step in the ATS engine introduction, incorporates many ATS technologies such as closed-loop steam cooling, advanced compressor design, and high temperature materials. The lead unit has completed full-load testing at the City of Lakeland McIntosh #5 site in Lakeland, FL and has produced power and revenue for Lakeland Electric since May 2000. Results from the testing are presented and future developments are discussed. Building on the current W501G, advancements will include steam-cooled turbine vanes and leakage enhancements. Continuing this low risk step-wise introduction of new technology, the W501ATS engine adds further advanced designs that achieve the program objectives. Siemens Westinghouse is also infusing ATS technologies into its mature frames in both new units and service upgrades to maximize the benefit of the program.
Fundamental Design Issues of Brush Seals for Industrial Applications
Authors: Dinc Saim , Demiroglu Mehmet , Turnquist Norman , Mortzheim Jason , Goetze Gayle , Maupin John , Hopkins James , Wolfe Christopher , Florin Mark
Published: July 2014

Advanced seals have been applied to numerous turbine machines over the last decade to improve the performance and output. Industrial experiences have shown that significant benefits can be attained if the seals are designed and applied properly. On the other hand, penalties can be expected if brush seals are not designed correctly.

In recent years, attempts have been made to apply brush seals to more challenging locations with high speed (>400 m/s), high temperature (>650 °C), and discontinuous contact surfaces, such as blade tips in a turbine. Various failure modes of a brush seal can be activated under these conditions. It becomes crucial to understand the physical behavior of a brush seal under the operating conditions, and to be capable of quantifying seal life and performance as functions of both operating parameters and seal design parameters. Design criteria are required for different failure modes such as stress, fatigue, creep, wear, oxidation etc. This paper illustrates some of the most important brush seal design criteria and the trade-off of different design approaches.
Three Component Velocity Field Measurements in the Stagnation Region of a Film Cooled Turbine Vane
Authors: Polanka Marc D. , Cutbirth J. Michael , Bogard David G.
Published: July 2014

The showerhead region of a film cooled turbine vane in a gas turbine engine involves a complex interaction between mainstream flow and coolant jets. This flow field was studied using three-component laser Doppler velocimeter measurements in a simulated turbine vane test facility. Measurements were focused around the stagnation row of holes. Low and high mainstream turbulence conditions were used. The spanwise orientation of the coolant jets, typical for showerhead coolant holes, had a dominating effect. Very high levels of turbulence were generated by the mainstream interaction with the coolant jets. Furthermore, this turbulence was highly anisotropic, with the spanwise component of the turbulent fluctuations being twice as large as the other components. Finally, there was an interaction of the high mainstream turbulence with the coolant injection resulting in increased turbulence levels for the spanwise velocity component, but had little effect on the other velocity components.
Compressor Discharge Brush Seal for Gas Turbine Model 7EA
Authors: Ingistov Steve
Published: July 2014

Single shaft-heavy-duty- industrial gas turbines are extremely sensitive to compressed air bypassing at compressor discharge plane. This plane represents the highest pressure location in entire Gas Turbine Unit (GTU). Standard method to minimize compressed air leakage is labyrinth seal that is integral part of the cylindrical element here called “inner barrel”. The “inner barrel” is also the part of compressor discharge diffuser. This Paper describes the efforts related to conversion of standard labyrinth seal into the hybrid seal that is combination of labyrinth and brush seals.
Development of Assessment Method for Oxidation Resistance of MCrAlY Coating on Gas Turbine Bucket: Part 1
Authors: Okada Mitsutoshi , Etori Yoshiyuki , Hisamatsu Toru
Published: July 2014

Analysis is performed to investigate the degradation of CoCrAlY coating on a stage 1 bucket used in a 1100°C-class gas turbine running on LNG fuel for about 38000 hours. It is confirmed that the diffusion or movement of aluminum in the coating is important to understand the degradation of the oxidation resistance of the coating. In order to clarify the degradation behavior, high temperature oxidation tests are carried out in electric furnaces by means of CoCrAlY coating specimens. The density of aluminum below Al-oxide of the surface is decreased and such area forms a layer. This layer grows as the oxidation proceeds, and its behavior is observed. Moreover, the influence of temperature, partial pressures of steam and stress on the oxidation and the microstructural degradation are examined. They depend only on temperature and time not on partial pressure of steam or stress.
Estimation of Thermophysical Properties and Microstructure of Aged Thermal Barrier Coatings
Authors: Fujii Tomoharu , Takahashi Takeshi
Published: July 2014

A thermal barrier coating (TBC) is used for protecting hot gas path parts, and is useful for allowing the turbine inlet gas temperature to be increased. In order to quantitatively evaluate the performance of TBCs, the thermal conductivity of TBCs on the combustor of a gas turbine were measured. The results indicate that the thermal conductivity of age-deteriorated TBCs were higher than that of the as-sprayed TBC. This finding suggested that the thermal barrier performance of the TBC had deteriorated. When the thermal barrier performance of a TBC deteriorates, the temperature of the metal substrate rises, shortening the service life of hot gas path components. Accordingly, using experimental TBCs, laboratory-scale studies were performed to identify the causes of the deterioration of thermal barrier performance in TBCs. Six types of TBCs, prepared from six grades of plasma spray powder of yttria stabilized zirconia (YSZ), were tested. Average powder size, powder configuration, and percentage of yttria were the parameters of plasma spray powder taken to measure the thermophysical properties and carry out microstructural analyses on the as-sprayed TBCs and heat-treated TBCs.

The results of the thermophysical property measurements indicate that the thermal barrier performance of heat-treated TBCs were two to three times greater than that of the as-sprayed TBCs. The results of the microstructural analyses revealed that the deterioration in performance was caused by changes occurring in the crystalline structure and the reduction of the non-contact area as in TBCs. The changes in thermal conductivity of TBCs were expressed as coefficients of porosity, crystalline structure, and heating time and temperature.
The Effects of Entrapped Grit on the Thermomechanical Fatigue Properties of a Pt-Al Superalloy Coating
Authors: Purvis Andrew L. , Warnes Bruce M.
Published: July 2014

Superalloy specimens were treated in different manners prior to applying a platinum aluminide coating by chemical vapor deposition (CVD). Experiments were conducted to measure the effects of the various prealuminizing treatments on the thermomechanical fatigue (TMF) life of the coated specimens. The largest effect on the fatigue crack resistance was specimen immersion in a molten caustic solution prior to coating application. The primary reason for the increase in coating life because of this variable was determined to be the removal of grit particles embedded in the surface during routine processing prior to the application of the Pt-Al coating. This was verified by extensive microstructural examination and electron microscopy. Included are discussions on the relative effects of expected service life for gas turbine components subjected to these variables during routine manufacturing processing.
Designing Hot Working Processes of Nickel Base Superalloys Using FEM Simulation
Authors: Kopp R. , Tschirnich M. , Wolske M. , Klöwer J.
Published: July 2014

Knowledge of correct flow stress curves of Ni-based alloys at high temperatures is of essential importance for reliable plasto-mechanical simulations in materials processing and for an effective planning and designing of industrial hot forming schedules like hot rolling or forging. The experiments are performed on a computer controlled servo-hydraulic testing machine at IBF (Institute of Metal Forming). To avoid an inhomogeneous deformation due to the influence of friction and initial microstructure, a suitable specimen geometry and lubricant is used and a thermal treatment before testing has to provide a microstructure, similar to the structure of the material in the real process.

The compression tests are performed within a furnace, which keeps sample, tools and surrounding atmosphere at the defined forming temperature. The uniaxial compressions were carried out in the range of strain rates between 0.001 and 50 s−1 and temperatures between 950 and 1280°C. Furthermore two-stage step tests are carried out to derive the work hardening and softening behaviour as well as the recrystallisation kinetics of the selected Ni-based alloys.

At the end of this work a material model is adapted by the previously determined material data. This model is integrated into the Finite Element program LARSTRAN/SHAPE to calculate a forging process of the material Alloy 617.
Cavity and Protrusion Effects in a Single-Stage Compressor
Authors: Demargne A. A. J. , Longley J. P.
Published: July 2014

The effect of opening a stator-shroud cavity to the mainstream (no net leakage), upstream of a moderately loaded stator is investigated in a single-stage research compressor.

The investigations consist of a series of measurements and calculations, which reveal various inconsistencies in flow turning, secondary flow and blockage. CFD analysis is used as a diagnostic tool to show that the unexpected trends measured in the single-stage compressor can be attributed to the protrusion of the arrangement used to seal the cavity into the mainstream, disrupting the hub endwall flow into the stator passage.

The CFD results on the single-stage compressor without protrusion confirm the trends observed in the linear cascade experiment relative to the effects of the upstream shroud cavity on the hub endwall flow and stator performance, in the presence of the stator blade pressure field. These results clearly illustrate the strong sensitivity of the performance of the stator row to small protrusions and cavities in the endwalls. Such effects are no longer negligible when compared to the level of resolution and sophistication achieved with current solvers.
A Parametric Analysis of Reduced Order Models of Potential Flows in Turbomachinery Using Proper Orthogonal Decomposition
Authors: Epureanu Bogdan I. , Dowell Earl H. , Hall Kenneth C.
Published: July 2014

An unsteady inviscid flow through a cascade of oscillating airfoils is investigated. An inviscid nonlinear subsonic and transonic model is used to compute the steady flow solution. Then a small amplitude motion of the airfoils about their steady flow configuration is considered. The unsteady flow is linearized about the nonlinear steady response based on the observation that in many practical cases the unsteadiness in the flow has a substantially smaller magnitude than the steady component. Several reduced order modal models are constructed in the frequency domain using the proper orthogonal decomposition technique. The dependency of the required number of aerodynamic modes in a reduced order model on the far-field upstream Mach number is investigated. It is shown that the transonic reduced order models require a larger number of modes than the subsonic models for a similar geometry, range of reduced frequencies and interblade phase angles. The increased number of modes may be due to the increased Mach number per se, or the presence of the strong spatial gradients in the region of the shock. These two possible causes are investigated. Also, the geometry of the cascade is shown to influence strongly the shape of the aerodynamic modes, but only weakly the required dimension of the reduced order models.
The Application of Ultra High Lift Blading in the BR715 LP Turbine
Authors: Haselbach Frank , Schiffer Heinz-Peter , Horsman Mannfred , Dressen Stefan , Harvey Neil , Read Simon
Published: July 2014

The original LP turbine of the BR715 engine featured “High Lift” blading, which achieved a 20% reduction in aerofoil numbers compared to blading with conventional levels of lift - reported in Cobley et al. (1997). This paper describes the design and test of a re-bladed LP turbine with new “Ultra High Lift” aerofoils, achieving a further reduction of approximately 11% in aerofoil count and significant reductions in turbine weight. The design is based on the successful cascade experiments of Howell et al. (2000) and Brunner et al. (2000). Unsteady wake - boundary layer interaction on these low Reynolds number aerofoils is of particular importance in their successful application. Test results show the LP turbine performance to be in line with expectation. Measured aerofoil pressure distributions are presented and compared with the design intent. Changes in the turbine characteristics relative to the original design are interpreted by making reference to the detailed differences in the two aerofoil design styles.
Numerical Simulation of 3D Flow Field Structure in Turbine Cascade With Bowed Blades
Authors: Wang Songtao , Wang Zhongqi , Feng Guotai
Published: July 2014

The differences of flow field in bowed blade cascade and that in straight blade cascade are systematically studied in this paper. To bow a blade means to change its geometric boundary condition. This change not only affect the pressure distribution along the blade profile exit Mach number but also has great effect on the original position and development of the passage vertex. All of the changes mentioned above have great influence on the loss.

Numerical simulation result showed that blade bowing can decrease the cross-pressure gradient near the end wall. This trend will be more obvious with the increase of the bow angle. The pressure gradient decrease is beneficial to weaken the passage vortex strength and reduces the secondary loss near the endwalls. In addition, Pressure gradient from endwalls to midspan can be established near suction surface in positively bowed blade. With the increase of bow angle, this C-type pressure distribution is remarkable. It is also found that this C-type pressure distribution will influence the position of corner vortex near the suction surface and will also influence the position and size of the passage vortex. Blade bowing also has great influence on the position of the saddle point near the leading edge and the separated line of the horseshoe vortex. It is found that the position of the saddle point and the separated line of both legs of the horseshoe vortex move forward in a positively bowed blade.

The passage vortex structure in bowed cascade is also presented. It can be concluded that a bowed blade can make the passage vortex stable and helps change its structure from loose to compact. Blade bowing is also beneficial to limit the influence domain of the unstable passage vortex core by the stable limit cycle.
Improving the Efficiency of the Trent 500 HP Turbine Using Non-Axisymmetric End Walls: Part 1 — Turbine Design
Authors: Brennan G. , Harvey N. W. , Rose M. G. , Fomison N. , Taylor M. D.
Published: July 2014

This paper describes the redesign of the HP turbine of the Rolls-Royce Trent 500 engine, making use of non-axisymmetric end walls. The original, datum turbine used conventional axisymmetric end walls, while the vane and (shrouded) rotor aerofoil profiles were nominally the same for the two designs. Previous research on the large scale, low speed linear cascade at Durham University, see Hartland et al [1], had already demonstrated significant potential for reducing turbine secondary losses using non-axisymmetric end walls - by about one third. This paper shows how a methodology was derived from the results of this research and applied to the design of the single stage Trent 500 HP turbine (model rig). In particular the application of a new linear design system for the parametric definition of these end wall shapes, described in Harvey et al [2], is discussed in detail.
Application of Pulse Detonation Combustion to Turbofan Engines
Authors: Mawid M. A. , Park T. W. , Sekar B. , Arana C.
Published: July 2014

The potential performance gain of utilizing pulse detonation combustion in the bypass duct of a turbofan engine for possible elimination of the traditional afterburner was investigated in this study. A pulse detonation turbofan engine concept without an afterburner was studied and its performance was assessed. The thrust, SFC and specific thrust of a conventional turbofan with an afterburner and the new pulse detonation turbofan engine concept were calculated and compared. The pulse detonation device performance in the bypass duct was obtained by using multidimensional CFD analysis. The results showed that significant performance gains can be obtained by using the pulse detonation turbofan engine concept as compared to the conventional afterburning turbofan engine. In particular, it was demonstrated that for a pulse detonation bypass duct operating at a frequency of 100 Hz and higher, the thrust and specific thrust of a pulse-detonation turbofan engine can nearly be twice as much as those of the conventional afterburning turbofan engine. SFC was also shown to be reduced. The effects of fuel-air mixture equivalence ratio and partial filling on performance were also predicted. However, the interaction between pulse detonation combustion in the bypass duct and the engine fan, for potential fan stall, and engine nozzle have not been investigated in this study.
One-Disk Nutating-Engine Performance for Unmanned Aerial Vehicles
Authors: Korakianitis T. , Meyer L. , Boruta M. , McCormick H. E.
Published: July 2014

The nutating engine is a new type of internal combustion engine. The engine has unique advantages over conventional piston engines and gas turbines in small power ranges suitable for unmanned aerial vehicles (UAV), and other applications. This publication is the original presentation of the performance potential of the simplest version of the engine, a one-disk engine operating at constant compression ratio, for light airframe propulsion. In its basic configuration the core of the engine is a nutating non-rotating disk, with the center of its hub mounted in the middle of a Z-shaped shaft. The two ends of the shaft rotate, while the disk “nutates”, performs a wobbling motion without rotating around its axis. The motion of the disk circumference prescribes a portion of a sphere. A portion of the area of the disk is used for intake and compression, a portion is used to seal against a center casing, and the remaining portion is used for expansion and exhaust. The compressed air is admitted to an external accumulator, and then into an external combustion chamber before it is admitted to the power side of the disk. The external combustion chamber enables the engine to use diesel fuel in small engine sizes, giving it unique capabilities for UAV propulsion. The performance of the one-disk engine configuration for flight Mach numbers from 0 to 1 and altitudes from 0 to 20 km is presented and discussed. The performance with equal compression and expansion volume is compared with the higher-efficiency version with expansion volume higher than compression volume. A companion paper examines multi-disk alternative engine configurations and load control schemes.
Methods for Desensitizing Tip Clearance Effects in Turbines
Authors: Tallman J. , Lakshminarayana B.
Published: July 2014

This study is an attempt to reduce the effect of the leakage vortex in axial flow turbines. A 3D Navier-Stokes CFD solver with k-ε turbulence modeling was used compute the flow through an axial flow turbine with modified blade tip designs. A baseline flat tip case and three modified tip cases were simulated and the leakage flow and vortex for each was analyzed in detail. The three modified blade tip designs each involved adding a chamfer to the tip of the blade, in an attempt to diffuse the leakage flow through the gap and obstruct the leakage flow with the outer casing’s shear layer. Chamfering of the blade tip near the leading edge of the gap and across the entire gap region both failed to reduce the size and strength of the leakage vortex. By chamfering the blade tip near the trailing edge of the gap, the leakage flow inside the gap was turned toward the direction of the blade’s camber. This turning resulted in a decrease in the size and the strength of the leakage vortex and its subsequent losses, while at the same time, did not reduce the blade loading by an appreciable amount.

This paper is available in color on the World Wide Web at http://navier.aero.psu.edu/∼jat/research.html
Operational Behavior of a Complex Transonic Test Turbine Facility
Authors: Neumayer F. , Kulhanek G. , Pirker H.-P. , Jericha H. , Seyr A. , Sanz W.
Published: July 2014

This paper describes the operation of a continuously operating cold flow test stand for axial turbine stages. The interesting feature of this test stand is the fact that the power generated by the test turbine is used for driving a compressor, which supplies additional air to drive the turbine. The brake compressor was a donation from industry and was a very welcome alternative to a water brake. The advantages of using this compressor lie in the low installation costs and the power savings. The performance of the test turbine stage influences the capabilities of the test stand. A suction blower driven by a helicopter engine can be used to decrease the exhaust pressure allowing to increase the turbine expansion ratio.

The performance of the whole test facility and the complex interaction of the components will be described. In general, design engineers are interested in the performance of their test stages at different operating conditions (i.e. corrected speed, pressure ratio). It will be shown by which control mechanisms different operation points can be obtained and which range of the values can be achieved.
Enhanced Heat Transfer for Microturbine Recuperators
Authors: Thompson Brian E. , Floryan J. M. , Nolan Richard E. , Osgood Sarah J.
Published: July 2014

Calculated and measured results are presented to quantify the effects of surface waves in laminar flow through high-aspect ratio channels typical of many in microturbine recuperators. Flow structures were calculated with spectral methods that solve incompressible Navier-Stokes equations and use Fourier expansions to represent the corrugated-wall boundary condition. Stability analysis with a generalized Floquet formulation that accounts for spatial modulation of the flow was used with the spectral flow field to predict the shape of streamlines that lead to streamwise vortices. Results indicate that vortices are produced in a very narrow range of streamline wavelengths and amplitudes. Streamlines were also calculated using a RANS method for the purpose of finding a surface that would produce the necessary streamline patterns. Hot-wire measurements show the frequency and amplitude of streamwise vortex structures increases in the flow over a sinusoidal wall with the predicted surface waves.
Particles Trajectories Through an Axial Fan and Performance Degradation due to Sand Ingestion
Authors: Ghenaiet A. , Elder R. L. , Tan S. C.
Published: July 2014

The erosion of an axial fan was investigated, both theoretically and experimentally. A computer program was developed to predict particle trajectories and erosion through turbomachines. It also accounts for different boundary conditions and stage interfaces. The governing equations of the particle motion were solved using Runge-Kutta Fehlberg technique in a given flowfield. The tracking of particles and their locations are based on the finite element interpolation method. The methodology was applied to an axial fan with inlet guide vanes (IGV). The flowfield was solved using the TASCflow code. The number of particles seeded upstream of the IGV was determined from experimentally measured profile concentration, with respect to a random distribution of particle sizes. The erosion of the blades and changes to the chord and tip clearances were also measured. The concentration profiles and velocities of the particle were measured with a laser transit anemometer and used as input to the trajectory code. The fan performance was measured before and after sand ingestion to assess the degradation in performance due to the eroded geometry
The Effect of Variable Chord Length on Transonic Axial Rotor Performance
Authors: Roberts William B. , Armin Albert , Kassaseya George , Suder Kenneth L. , Thorp Scott A. , Strazisar Anthony J.
Published: July 2014

Aircraft fan and compressor blade leading edges suffer from atmospheric particulate erosion that reduces aerodynamic performance. Recontouring the blade leading edge region can restore blade performance. This process typically results in blades of varying chord length. The question therefore arises as to whether performance of refurbished fans and compressors could be further improved if blades of varying chord length are installed into the disk in a certain order. To investigate this issue the aerodynamic performance of a transonic compressor rotor operating with blades of varying chord length was measured in back-to-back compressor test rig entries. One half of the rotor blades were the full nominal chord length while the remaining half of the blades were cut back at the leading edge to 95% of chord length and recontoured. The rotor aerodynamic performance was measured at 100%, 80% and 60% of design speed for three blade installation configurations: nominal-chord blades in half of the disk and short-chord blades in half of the disk; four alternating quadrants of nominal-chord and short-chord blades; nominal-chord and short-chord blades alternating around the disk. No significant difference in performance was found between configurations, indicating that blade chord variation is not important to aerodynamic performance above the stall chord limit if leading edges have the same shape. The stall chord limit for most civil aviation turbofan engines is between 94-96% of nominal (new) blade chord.
Enhancing Reliability and Reducing O&M Expenditures in Advanced Combined Cycle Gas Turbine Power Plants
Authors: Kallianpur V. , Akita E. , Tsukuda Y.
Published: July 2014

Explosive growth in power plants in the US and elsewhere is occurring through combined cycle advanced gas turbine technology. Significant fuel expenditure savings are possible through such technology. Much of the recent advances have been possible through the transfer of aero engine design tools, elevated temperature materials, coatings, and sealing technologies. A balanced approach that melds the aero engine technologies and longstanding field experience from large industrial frame gas turbines is key to ensuring Reliability, Availability, Maintainability and Durability (RAM-D) design objectives are met. Future costs associated with power generation and distribution with these advanced gas turbine combined cycle power plants will undoubtedly be driven by major decisions of OEMs pertaining to design and validation approach, material selection, reparability, design criteria, and design features for quicker maintainability.

In this paper, MHI’s approach for enhancing RAM-D performance and reducing O&M expenditures of advanced combined cycle gas turbines are described.
Combined Cycle and Cogeneration Prospects in Former Centrally Planned Economies
Authors: Domachowski Zygfryd , Dzida Marek
Published: July 2014

An important restructuring of Polish electric power system is required. It should result in electric power capacity development, thermodynamic and economic efficiency increase, environment pollution reduction. These are two low investment ways of performing those goals: combined cycle and cogeneration. The problem is similar in most of former centrally planned economies (Central and Eastern Europe).
Comparative Evaluation of Power Plants With Regard to Technical, Ecological and Economical Aspects
Authors: Lezuo Alex , Taud Robert
Published: July 2014

The development of efficiency of gas turbine based combined cycle plants has been very fast during the last 10 years and has reached now a value of close to 60 %. This value is well above that of coal power plants or other technologies. Even though development has been going on in these fields as well.

For a fairly comprehensive reorientation and status evaluation with the time frame of 2005 in focus, a comparative study with equal boundary conditions has been performed considering coal steam plants with various steam parameters, fluidized bed combustion, coal gasification and natural gas fired combined cycle plants. Besides investment also technical differences and ecological data are given.

The final evaluation of power generation technologies is based however mainly on its electricity generation costs or life cycle cost. Considering today’s fuel prices and price development projections over the plant life times, an economical analysis has been performed and will be presented, serving also as framework for project and investment decisions.
Improving the Efficiency of the Trent 500 HP Turbine Using Non-Axisymmetric End Walls: Part II — Experimental Validation
Authors: Rose M. G. , Harvey N. W. , Seaman P. , Newman D. A. , McManus D.
Published: July 2014

Part I of this paper described how the HP turbine model rig of the Rolls-Royce Trent 500 was redesigned by applying non-axisymmetric end walls to both the vane and blade passages, whilst leaving the turbine operating point and overall flow conditions unaltered. This paper describes the results obtained from testing of the model rig and compares them with those obtained for the datum design (with conventional axisymmetric end walls). Measured improvements in the turbine efficiency are shown to be in line with those expected from the previous linear cascade research at Durham University, see Harvey et al. [1] and Hartland et al. [2]. These improvements are observed at both design and off-design conditions. Hot wire traverses taken at the exit of the rotor show, unexpectedly, that the end wall profiling has caused changes across the whole of the turbine flow field. This result is discussed making reference to a preliminary 3-D CFD analysis. It is concluded that the design methodology described in part I of this paper has been validated, and that non-axisymmetric end wall profiling is now a major new tool for the reduction of secondary loss in turbines (and potentially all axial flow turbomachinery). Further work, though, is needed to fully understand the stage (and multistage) effects of end wall profiling.
Ceramic Stationary Gas Turbine Program: Combustor Liner Development Summary
Authors: Miriyala Narendernath , Fahme Anthony , van Roode Mark
Published: July 2014

Under the Ceramic Stationary Gas Turbine Program sponsored by the U. S. Department of Energy, Solar Turbines Incorporated has successfully designed and developed ceramic combustor liners. Their potential for low emissions has been demonstrated in five field-engine tests for a total duration of over 30,000 hours, with over 13,000 hours on EBC protected liners in one engine test. The ceramic combustor development under the CSGT Program (1992–2000), including design, material selection, testing and evaluation are discussed.
Ceramic Stationary Gas Turbine Development Program: Eighth Annual Summary
Authors: Price Jeffrey , Jimenez Oscar , Miriyala Narendernath , Kimmel Josh B. , Leroux Don R. , Fahme Tony
Published: July 2014

The Ceramic Stationary Gas Turbine (CSGT) program has been performed under the sponsorship of the United States Department of Energy, Office of Industrial Technologies and Office of Power Technologies. The objective of the program was to improve the performance of stationary gas turbines in cogeneration by retrofitting uncooled ceramic components into the hot section of the engine. The replacement of previously cooled metallic hot section components with the uncooled ceramics enables improved thermal efficiency, increased output power, and reduced gas turbine emissions. This review summarizes the latest progress on Phase III of the program, which involves 1) preparation for the final in-house CSGT engine test of ceramic blades, nozzles and CFCC liners, and 2) field testing of the CFCC combustor liners at two cogeneration end user sites. The field testing of CFCC combustor liners is now being performed under the Advanced Materials Program, sponsored by DOE, Office of Power Technologies.

The Solar Centaur 50S engine, which operates at a turbine rotor inlet temperature (TRIT) of 1010°C, was selected for the developmental program. The program goals include an increase in the TRIT to 1121°C, accompanied by increases in thermal efficiency and output power. This is to be accomplished by the incorporation of ceramic first stage blades and nozzles, and a “hot wall” ceramic combustor liner. The performance improvements are attributable to the increase in TRIT and the reduction in cooling air requirements for the ceramic parts. The “hot wall” ceramic liners also enable a reduction in gas turbine emissions of NOx and CO. This 1121°C TRIT engine test of the ceramic hot section is planned for the first quarter of 2001.

The component design and material selection have been previously definitized for the ceramic blades, nozzles and combustor liners. Each of these ceramic component designs was successfully evaluated in short-term engine tests in the Centaur 50S engine test cell facility at Solar. Environmental barrier coatings for the ceramic components are also being optimized. To date, seven field installations of the CSGT Centaur 50S engine totaling over 30,000 hours of operation have been initiated under the program at two industrial cogeneration sites. This paper briefly discusses the recent developmental efforts for the upcoming 1121°C TRIT engine test, but focuses on the various field demonstrations of CFCC combustor liners.