bluuebunny/crossref_metadata_2025_split huggingface dataset:
A High Efficiency Recuperated Cycle, Optimized for Reliable, Low Cost, Industrial Gas Turbine Engines
Authors: Ragland Thomas L. 
Published: February 2015

With the increasing need for more efficient industrial gas turbine engines, the recuperated engine cycle is being considered as a means of meeting these needs.
This paper discusses a recuperated cycle design that is optimized to take full advantage of the recuperator but at the same time accommodate the real world market constraints of reliability, durability and cost.
Current simple cycle industrial engines are evolving to very high pressure ratios and high firing temperatures in order to reach cycle efficiencies in the 37% to 39% range. Some simple cycle industrial gas turbines with lower cycle pressure ratios and firing temperatures have been modified so a recuperated option can be added. Although the addition of a recuperator to these engines does improve cycle efficiency, levels of only the 33% to 35% range are reached. This is mainly due to the fact that the resulting cycles are not optimized for a recuperator.
An engine cycle that is optimized around a recuperator could obtain cycle efficiencies in the 43% to 45% range. Fortunately, this cycle optimizes at low pressure ratios and modest firing temperatures which results in lower cost components which tend to offset the additional cost of the recuperator.
Trial Operation Results of the Fully-Fired Combined Cycle Generating Plants in Chita
Authors: Mita T. , Ando N. , Kawauchi A. , Morikawa K. 
Published: February 2015

A fully-fired combined cycle power plant (FFCCPP) combines a steam thermal power plant with a gas turbine. Hot exhaust gases fed from the gas turbine are used as combustion air for the boiler, thus increasing total plant output and efficiency.
An unusually hot spell in Japan in the summer of 1990 brought about such a rapid surge in power demand for air conditioning so that all electric power companies registered record highs in consumption.
This promoted Chubu Electric Power Co. to decide to add a 154-MW gas turbine to each of its six existing steam thermal power plants (four 700-MW and two 375-MW units), thus repowering their system into an FFCCPP.
Construction work began in 1992. In September, 1994, two 700-MW steam thermal power plants (Chita Thermal Power Plant’s No. 6 unit and Chita Second Thermal Power Plant’s No. 1 unit) were modified into FFCCPPs, which then began operating in a trouble-free manner.
This paper reports the characteristics and test-run results of the above two plants, which have been operating in good condition as the largest-capacity FFCCPPs in the world.
Development and Engine Testing of a Dry Low Emissions Combustor for Allison 501-K Industrial Gas Turbine Engines
Authors: McLeroy Jacob T. , Smith Duane A. , Razdan Mohan K. 
Published: February 2015

The Allison Engine Company has been developing a low emission, can-annular combustion system for the 501K industrial gas turbine engine to satisfy increasingly stringent environmental requirements. This paper describes the progress achieved, over that previously reported by Razdan et al. (1994), through subsequent design evolution, bench testing, and engine evaluation. Allison’s goal is to develop a retrofittable, can-annular combustion system that limits emission levels to less than 25 ppm nitrogen oxide (NOx), 50 ppm carbon monoxide (CO), and 20 ppm unburned hydrocarbon (UHC), while operating at full load conditions. The interim emissions goals for the combustion system are 37 ppm NOx, 80 ppm CO, and 20 ppm UHC (all dry 15% O2 corrected).
The combustion system under development employs a dual mode combustion approach to meet engine operability requirements and high power emission targets without the use of combustor diluent injection or postcombustor exhaust treatment. A lean premixed combustion mode is used to minimize combustion zone temperature and limit NOx production during high power engine operation. The lean premix mode is augmented with a diffusion flame pilot mode for engine starting and low power operation.
Initial engine testing showed a dry low NOx combustion system, designed to meet a 37 ppm NOx limit, produced less than 34 ppm NOx and less than 10 ppm CO and UHC in test stand verification test. Continued burner rig testing with modified primary combustion zone stoichiometry has demonstrated NOx less than 25 ppm, CO less than 50 ppm, and UHC less than 20 ppm with simulated engine conditions representing 20 to 100% power. Development activity continues on the combustion system as engine field evaluation trials proceed.
Dynamic Simulation of the FT8-2™ Gas Turbine
Authors: Metzger Alan 
Published: February 2015

With the approach of the 1990 Clean Air Act compliance limits, the race is on to produce a functional, low-emission gas turbine. While most prototype Dry Low NOx (DLN) gas turbines are based on existing designs, the leap in technology required to meet NOx abatement levels is significant. To meet these goals, significant testing is required before low-emission turbines are ready for commercial production.
This paper describes the test procedure that was used to verify control system and modulating valve technology for Turbo Power & Marine’s FT8-2™ Dry Low NOx prototype turbine. In particular, dynamic turbine simulation before the actual engine test will be discussed. The method and benefits of this test procedure will be presented.
Rapid Design, Integration and Test of Improved Digital Fuel Control for the LM2500 Gas Turbine Engine
Authors: Howell Max , Hartshorn Bill 
Published: February 2015

This paper describes how Martin Marietta performed rapid design, integration, and test of a Digital Fuel Control (DFC) system for control of shipboard GE LM2500 Gas Turbine Engines. This phase was performed in Orlando, Florida and included real time hardware in the loop (HWTL) testing of the DFC with a simulated engine and test cell. With this approach, all of the DFC hardware and software could be validated before performing control of a real engine. Therefore risk was minimized and the schedule did not depend on availability of an LM2500 engine. The engine and test cell were simulated using the Integrated Systems, Inc. (ISI) AC100 Real Time Controller, which is easily transportable from site to site. The next phase will involve testing the DFC and AC100 with a real LM2500 engine and test cell.
The AC100 incorporates parallel digital signal processing and various input/output (I/O) options such as analog to digital (A/D) converters, digital to analog (D/A) converters, logical inputs and outputs, resolver to digital converters, pulse width modulation output, etc. Programs and I/O connections are made using extensive software on a workstation which produces code which is downloaded to the AC100 via Ethernet The programs are developed using a user-friendly, menu-driven graphical language called System Build. An autocode generator converts the system model to C or Ada, which is compiled and downloaded to the AC100 for real time execution.
Influence of Powder Manufacturing Process on TBC Lifetime
Authors: Froning Marc J. , Sahoo Purush 
Published: February 2015

Thermal barrier coatings (TBC) have been used extensively in aircraft engines to protect the gas turbines’ hot section from mechanical and enviromental degradation as well as to improve thermodynamic efficiency. Because TBC’s enhance operating temperature and service life, they are expected to play and increasingly important role in protecting both flight and land based industrial turbine engines. This investigation examines the functionality of air plasma sprayed two-layer TBC systems with a MCrAlY bond coat and a yttria partially stabilized zirconia (YSZ) top coat.
Qualitative X-ray diffraction (XRD) analyses were conducted on several commercially produced YSZ powders and the coatings produced from the powders. Thermal cycle lifetime studies were carried out at 2040°F. Phase structures of the coatings were evaluated before and after testing. An attempt was then made to correlate those results to thermal cycle life. It was found that the powder manufacturing process appears to have an influence on coating characteristics and on thermal shock lifetime.
Application of an Industrial Gas Turbine for Cogeneration and Process Services
Authors: Ehlers Gary A. 
Published: February 2015

The gas turbine is not limited to single service applications such as power generation or mechanical drive service. An application has been developed recently to use an industrial gas turbine to drive an electric generator for power while at the same time contributing to the heat balance of a refinery unit. Specifically, a G. E. Frame 5 gas turbine installed with a hydrogen reformer furnace can significantly reduce the overall heat input required by capturing the waste heat in the exhaust gas to preheat the feed to the furnace and to generate high pressure steam for the owner’s refinery steam system.
The gas turbine selected for the projects described in this paper is the G.E. Frame 5, model “R” (5271 RA). The model “R” was originally described as a “single shaft mechanical drive” turbine but easily adapted to generator drive. The design is some 30 years old as it was developed in the 1960’s. The term “single shaft mechanical drive” is somewhat strange to us in the process industries as we’re more accustomed to mechanical drive gas turbines designed with two shafts for speed control purposes. Many of the design / construction features of this model make it ideally suited for this application.
The higher cost of fuels, and electrical power contribute significantly to making the economics attractive. First of all the heat of the turbine exhaust gas will reduce the fuel required for firing to heat the feed to the furnace. The steam generated in the heat recovery section then contributes to generating power in the steam side in the steam turbine. The results are fuel savings and electric power purchase savings.
The steam turbine portion of the cycle is designed to vary with the owner’s steam system and balance. For that reason the steam turbine includes a high pressure inlet, medium pressure steam chest for extraction, a low pressure steam chest designed for induction or extraction and a surface condenser to condense the steam passed through.
Fuel flexibility is a major consideration of the unit design. Natural gas or methane rich gas is a base fuel that the gas turbine will fire most of the time. Alternate fuels however, such as propane or butane are commonly available in a refinery and could be fired in the gas turbine as currently configured.
Use of Knowledge-Based Engineering in Compressor Rotor Design
Authors: Marra John 
Published: February 2015

Competitive pressures are forcing manufacturers of turbine engines to reduce product development times, minimize design iterations, and react rapidly to changing markets and customers. Concurrent Engineering replaces the traditional sequential design process with parallel efforts in multiple disciplines, increasing product quality while reducing leadtime. Knowledge-Based Engineering captures product and process knowledge contained in the “corporate memory” to enhance and accelerate the design process. Linking the two together provides a wide variety of synergistic effects not separately available.
In this paper a general description of the process used to create a Knowledge Based Engineering (KBE) System capable of Concurrent Engineering (CE) will be presented, along with selected results. The summary discusses use of the system created to pursue real world design problems.
An Evaluation of Indentation and Finishing Properties of Bearing Grade Silicon Nitrides
Authors: Dill James F. , Gardos Michael N. , Hardisty Robert G. 
Published: February 2015

This paper describes the results of studies of the machining performance and the indentation hardness and fracture toughness of different silicon nitride materials as part of an effort to better define the optimum machining conditions for bearing components. This work builds on prior efforts by two of the authors, Gardos and Hardisty (1993) who formulated a simple relationship between diamond grinding performance of silicon nitride bearing balls and a wear equation first detailed by Evans and Wilshaw (1976).
The goal of this present work was to determine the general applicability of such a relationship, i.e. could simple indentation studies be used to define finishing conditions for different silicon nitride materials. The availability of such a simple test would reduce the time required for developing an acceptable process when a supplier changes his formulation, or when a new material becomes available. Quicker development of optimum finishing conditions would eventually result in a lower-cost product for users.
The initial study by Gardos and Hardisty (1993) was based on limited data taken at a fixed set of conditions. This study expanded the range of conditions evaluated and the number of ceramic materials studied in an effort to define the universality of the relationship between grinding wear, hardness and toughness.
This study has shown that no simple relationship like that first envisioned by the authors exists. The results showed that the grinding wear of the individual silicon nitride materials increased at different rates as a function of load. Because of the differences found in the load dependence of grinding rates, no simple relationship between hardness, fracture toughness and grinding rate could be found which fit the data over the range of conditions studied. This work is part of an ARPA funded effort to provide a tribological performance database on ceramic bearing materials, including their grinding and finishing properties, and their interaction with standard bearing steels.
Modeling and Simulation Methods for MDOF Structures and Rotating Machinery With Impact Dampers
Authors: McElhaney John M. , Palazzolo A. , Kascak A. 
Published: February 2015

Previously published work on applied impact damping typically relates to SDOF models or simple MDOF models such as the classical cantilever beam. Structural models often require an extremely large number of DOF with mode shapes that are generally very complex. Dynamics simulation of these typically becomes both complicated and time consuming as well. The non-linear behavior of impact dampers further complicates such simulation in that standard linear solutions are not possible.
The primary objective in this research extends previous work by applying impact dampers to MDOF structures that are modeled with general 3-D ‘beam’ finite elements. Modal based models of the MDOF systems and efficient impact damper tracking algorithms were also developed which significantly reduced CPU time for simulation.
Significant among the objectives was obtaining an impact damper design for the MDOF casing structure of the Space Shuttle Main Engine (SSME), High Pressure Oxygen Turbo-Pump (HPOTP), subject to pump rotor shaft unbalance. Impact damper performance is based on suppression of vibration at casing critical frequencies for rotor speed ranges, at rotor full speed, and very high unbalance to simulate a defect such as loosing an impeller blade fragment or a cracked bearing[6]. Simulations show significant reductions in vibration at the casing critical frequencies and very high unbalance levels while little or no improvement was observed off resonance.
Additionally, the previous work with an experimental rotor bearing system (RBS) and impact damper was modeled using the developed modal based methods. Simulation of the resulting model response shows remarkable agreement with the experimental.
Finally, both the RBS and the HPOTP were modeled and simulated as unstable systems with attached impact dampers. The simulations predict that the impact damper is an excellent stabilizing mechanism for a range of instability driver values.
Simulation of the models in this research with the developed modal based algorithms were accomplished with excellent efficiency, and accurate results.
Measured Force/Current Relations in Solid Magnetic Thrust Bearings
Authors: Allaire P. E. , Fittro R. L. , Maslen E. H. , Wakefield W. C. 
Published: February 2015

When magnetic bearings are employed in a pump, compressor, turbine or other rotating machine, measurement of the current in the bearing coils provides knowledge of the forces imposed on the bearings. This can be a significant indicator of machine problems. Additionally, magnetic bearings can be utilized as a load cell for measuring impeller forces in test rigs. The forces supported by magnetic bearings are directly related to the currents, air gaps and other parameters in the bearings. This paper discusses the current/force relation for magnetic thrust bearings.
Force vs. current measurements were made on a particular magnetic bearing in a test rig as the bearing coil currents were cycled at various time rates of change. The quasi-static force vs. current relations were measured for a variety of air gaps and currents. The thrust bearing exhibits a hysteresis effect which creates a significant difference between the measured force when the current is increasing as compared to that when the current is decreasing. For design current loops, 0.95 A to 2.55 A, at the time rate of change of 0.1 A/sec, the difference between increasing and decreasing current curves due to hysteresis ranged from 4% to 8%. If the bearing is operated in small trajectories about a fixed (non-zero) operation point on the F/I (force/current) curve, the scatter in the measurement error could be expected to be on the order of 4 percent.
A quasi-static non-linear current/force equation was developed to model the data and curve Fit parameters established for the measured data. The effect of coercive force and iron reluctance, obtained from conventional magnetic materials tests, were included to improve the model but theoretically calculated values from simple magnetic circuit theory do not produce accurate results. Magnetic fringing, leakage and other effects must be included.
A sinusoidal perturbation current was also imposed on the thrust bearing. Force/current magnitude and phase angle values vs. frequency were obtained for the bearing. The magnitude was relatively constant up to 2 Hz but then decreased with frequency. The phase lag was determined to increase with frequency with value of 16 degrees at 40 Hz. This effect is due to eddy currents which are induced in the solid thrust bearing components.
Dry Ultra-Low NOx ‘Green Thumb’ Combustor for Allison’s 501-K Series Industrial Engines
Authors: Puri Rahul , Stansel David M. , Smith Duane A. , Razdan Mohan K. 
Published: February 2015

This paper describes the progress made in developing an external ultra-low oxides of nitrogen (NOx) ‘Green Thumb’ combustor for the Allison Engine Company’s 501-K series engines. A lean premixed approach is being pursued to meet the emissions goals of 9 ppm NOx, 50 ppm carbon monoxide (CO), and 10 ppm unburned hydrocarbon (UHC). Several lean premixed (LPM) module configurations were identified computationally for the best NOx-CO trade-off by varying the location of fuel injection and the swirl angle of the module. These configurations were fabricated and screened under atmospheric conditions by direct visualization through a quartz liner; measurement of the stoichiometry at lean blow out (LBO); measurement of the fuel/air mixing efficiency at the module exit; and emissions measurements at the combustor exit, as well as velocity measurements. The influence of liner residence time on emissions was also examined.
An LPM module featuring a radial inflow swirler demonstrated efficient fuel-air mixing and subsequent low NOx and CO production in extensive atmospheric bench and simulated engine testing. Measurements show the fuel concentration distribution at the module exit impacts the trade-off between NOx and CO emissions. The effect of varying the swirl angle of the module also has a similar effect with the gains in NOx emissions reduction being traded for increased CO emissions. A uniform fuel-air mixture (± 2.5% azimuthal variation) at the exit of the module yields low NOx (5–10 ppm) at inlet conditions of 1 MPa (∼10 atmospheres) and temperatures as high as 616 K (650°F). The combustion efficiency at the above conditions was also good (> 99.9%) with CO and UHC emissions below 76 ppm and 39 ppm, respectively. This LPM module was resistant to flashback, and stability was good as LBO was observed below ϕ = 0.50. Tests with multiple modules in a single liner indicate a strong intermodule interaction and show lower NOx and CO emissions. The close proximity of adjacent modules and lower confinement in the liner most likely reduces the size of the recirculation zone associated with each module, thereby reducing the NOx formed therein. The CO emissions are probably lowered due to the reduced cool liner surface area per module resulting when several modules feed into the same liner.
Conversion of Liquid to Gaseous Fuels for Lean Premixed Combustion
Authors: Stoffel B. , Reh L. 
Published: February 2015

The lean premixed combustion of gaseous fuels is an attractive technology to attain very low NOx emission levels in gas turbine engines. If liquid fuels are converted to gaseous fuels by vaporization, they also can be used in premix gas burners and similar low NOx emissions are achievable. Experiments were carried out in a test rig in which the three main process steps of liquid fuel combustion (vaporization of fuel, mixing of air and fuel vapor and combustion reaction) can be performed successively in three separate devices and examined independently.
A wide range of liquid fuels (methanol, ethanol, heptane, gasoline, rape oil methyl ester and two diesel oil qualities) was vaporized in an externally heated tube in the presence of superheated steam. These fuel vapors were led to a Pyrocore® radiant burner operating in fully premixed mode at atmosperic pressure. For all fuels without bound nitrogen, NOx levels below 15 mg/m3 at 3% O2 in the dry exhaust gas (2.5 ppm at 15% O2) were measured at lean combustion conditions.
However, the nitrogen particularly bound in higher boiling fuels like diesel oil was converted completely to NOx under these conditions. The fuel bound nitrogen (FBN) proved to be the major source of NOx when burning vaporized diesel oil.
Problems in Military Propulsion Engines of the South African Air Force
Authors: Benson J. , Miglietti W. , Glass S. J. , Getliffe K. 
Published: February 2015

The Nimonic 105 first stage turbine blade of the Rolls Royce Viper 22/1 engine has a design life of 2400 hrs. Over the years, these blades have prematurely failed (1 200–1 800 hrs), necessitating a service limit of 1 000 hrs. Initial investigations thought the cause of failure to be linked with higher than desired lead content but the final cause of failure was attributed to an incorrect heat treatment, forming continuous grain boundary carbides, resulting in embrittlement of the blade. A rejuvenation heat treatment was then developed.
The IN-713 and IN-X-40 first stage vanes of the Allison T56 engine suffer thermal fatigue cracking. The IN-713 vanes suffer narrow, fine but long cracks, whereas the X-40 vanes suffer severe cracking (cracks as wide as 3 mm) and excessive oxidation due to overheating. The X-40 alloy is protected by a Cr2O3 scale compared with Al3O3 on the IN-713 alloy. Above 1 000 °C the Cr2O3 breaks down and excessive oxidation results. A braze repair was developed for the X-40 vanes.