bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Swirl and Wall Geometry on the Emissions of Advanced Gas Turbine Combustors
Authors: Micklow Gerald J. , Shivaraman Karthikeyan 
Published: February 2015

A numerical study was performed to investigate the chemically reactive flow with liquid spray injection in a staged combustor concept for reducing pollutant emissions. The staged combustor consists of an airblast atomizer, a rich bum section, a converging connecting pipe, a quick mix zone, a diverging connecting pipe, and a lean combustion zone. For computational efficiency, the combustor was split into two subsystems, i.e. the fuel nozzle/rich burn section and the quick quench/lean bum section.
The current study investigates the effect of wall geometry and swirl direction, i.e. co- or counter-rotating swirl, on fuel distribution, temperature distribution, and emissions for the fuel nozzle/rich bum section at a cruise condition. At an equivalence ratio of 1.9, the nozzle-combustor (dome) interface geometry was varied from a flat wall (normal to the combustor wall) to a sloped wall of 45 degrees. It is seen that the sloped wall with co-rotating swirl direction had a substantial effect on combustor performance and reducing pollutant emissions.
Dynamic Control of Rotating Stall in Axial Flow Compressors Using Aeromechanical Feedback
Authors: Gysling D. L. , Greitzer E. M. 
Published: February 2015

Dynamic control of rotating stall in an axial flow compressor has been implemented using aeromechanical feedback. The control strategy developed used an array of wall jets, upstream of a single-stage compressor, which were regulated by locally reacting reed valves. These reed valves responded to flowfield pressure perturbations associated with the small amplitude perturbations that precede rotating stall. The valve design was such that the combined system, compressor plus reed valve controller, was stable under operating conditions that had been unstable without feedback. A 10% decrease in the stalling flow coefficient was achieved using the control strategy, and the stable flow range was extended with no noticeable change in the steady state performance of the compression system.
The experimental demonstration is the first use of aeromechanical feedback to extend the stable operating range of an axial flow compressor. It is also the first use of local feedback and dynamic compensation techniques to suppress rotating stall.
The design of the experiment was based on a two-dimensional stall inception model which incorporated the effect of the aeromechanical feedback. The physical mechanism for rotating stall in axial flow compressors was examined with focus on the role of dynamic feedback in stabilizing compression system instability. The effectiveness of the aeromechanical control strategy was predicted, and experimentally demonstrated, to depend on a set of non-dimensional control parameters that determine the interaction of the control strategy and the rotating stall dynamics.
The Application and Experience of HVOF Coatings in the Repair and Overhaul of Industrial Gas Turbines
Authors: Smith C. W. , Naisbitt G. 
Published: February 2015

High Velocity Oxy-Fuel thermal spray systems (HVOF), also known as High Velocity Combustion systems (HVC) are high energy thermal spray combustion processes, producing very hard, high density coatings. These coatings are used in areas where high wear resistance is of particular importance, with metal carbide coatings being typical in gas turbine applications.
Gas turbines use hard face coatings in such areas where vibration is the initial source of the problem. The areas tend to be in the hot end of the gas turbines although certain areas of the cold end are also affected. To date the hard face coating that has been predominately applied in gas turbines particularly in the hot end, is the Praxair (Union Carbide) “D” gun coating. As a result to date, the “D” gun system has had a virtual monopoly with regards to the overhaul/repair of gas turbine components where hard face coating was required.
However new HVOF systems have come on to the market Examples are: CDS, Plasma Technik; Diamond Jet, Metco; Top Gun, UPT U.K. (Miller); Jet Kote, Deloro Stellite; Gun. Metallisation and JP 5000, Hobart Tafa. As a result gas turbine overhaul bases are now in a position to offer a more competitve coating service, producing comparable, and in some cases superior, coatings to those produced by the “D” gun process.
This paper covers, from the Rolls Wood Group point of view, the developments of the HVOF systems, where they appear to be today and how these systems, now allow overhaul bases to offer services not previously available and the ability to develop new coating applications.
Advanced GT’s Call for Advanced CC’s (OR: the 4 S’s)
Authors: Jury Walter , Luthi Hans K. 
Published: February 2015

Four key parameters, the 4 S’s, determine the technoeconomical performance of the steam bottoming cycle to a given gasturbine: [S1], the temperature of the heat Source, [S2], the temperature of the heat Sink, [S3] cycle Structure and [S4] component Specifications. The first two are given by the gasturbine exhaust gas temperature (TEX) and ambient water/air temperatures respectively; the last two are designer’s choice but depend on economics: how much can you afford to pay for an extra kW? (parity factor or differential capital outlay).
The paper analyses the effect of current trends in the first two S’s on the latter two: «S1», the higher TIT (turbine inlet temperature) of advanced GT’s generally leads to higher TEX, especially when coupled with Sequential Combustion; and [S2]«S2», the trend from fresh water cooling to cooling towers — and again from wet to dry types — due to environmental considerations and/or water shortages leads to higher condenser pressures. These trends change the economics of «S3», the structure (one-, two- or three-pressure, reheat, supercritical etc.); finally, macro-economical trends (fuel cost, cost of capital, more Independent Power Producers or IPP’s) determine «S4», equipment specifications (delta-T’s, delta-P’s, number of stages or exhaust flows etc.).
In this written paper the authors report on their technoeconomical analysis; at the conference they will present hands-on solutions, optimized for ABB’s Type GT24 (60Hz, 165 MW) and GT26 (50 Hz, 240 MW) gasturbines. (Note that throughout the paper definite figures are only given for ABB gasturbines and steam turbines, as the authors cannot vouch for information published by other manufacturers or third parties).
Development of an Acoustically Enhanced Cyclone Collector for PFBC
Authors: Gallca Marlene A. 
Published: February 2015

Acoustically enhanced cyclone collectors offer the potential of achieving environmental particulate control standards under pressurized fluidized bed combustion (PFBC) conditions without the need for post turbine particulate control. The objective of this research program is to extend acoustic agglomeration technology from the laboratory scale up to the sub-pilot scale. The effects of high intensity sound on the agglomeration of fly ash particles are being investigated in a simulated PFBC effluent stream. The test facility consists of a variable residence time acoustic agglomeration chamber with a vitiating air preheat combustor, an ash injection system utilizing an auger feeder, a natural gas fired pulse combustor sound source, and a two-stage high temperature, high pressure cyclone. Fly ash for these tests has been obtained from the TVA (Tennessee Valley Authority) Shawnee Station circulating fluidized bed combustor (CFBC), as well as the Nucla CFBC, and Tidd PFBC. Acoustic agglomeration tests are underway.
The acoustically enhanced cyclone collector is being evaluated with two distinct goals in mind: 1) determine the effects of the major operating parameters on acoustic agglomeration efficiency, and 2) optimize the agglomeration system performance for maximum particulate removal efficiency. The data obtained during these tests will provide direct information on the effects of sound intensity and frequency, particle residence time, ash loading, and pressure on the enhancement of cyclone collection efficiency with acoustic agglomeration. These data, in conjunction with results from an acoustic agglomeration computer model will be used to evaluate the economic and engineering feasibility of an acoustically enhanced cyclone collector for a full scale pressurized fluidized bed combustor.
The Model V84.3 Shop Tests: Tip Clearance Measurements and Evaluation
Authors: Janssen M. , Seume J. , Zimmermann H. 
Published: February 2015

The design of high-performance gas turbines requires the reliable prediction of blade tip clearances. Excess clearances allow a portion of the hot gas to flow over the blade tips without performing useful work. The tip leakage flow disturbs the flow field which results in additional losses. Moreover, insufficient blade tip clearance may cause interference which can reduce turbine life. In conventional turbomachines, the blade tip clearances vary markedly with the operating condition of the turbine, essentially as a result of variations in gas temperatures and rotor speed.
Siemens tests prototype gas turbines in its own test facility. An extensive experimental program is devised to verify design calculations regarding strength, aerodynamics and thermodynamics. Among other measurements, the minimum operating tip clearance is measured by abrasion pins. Electro-mechanical sensors measure transient tip clearance during a selected duty cycle consisting of turning-gear operation, cold start, idle operation, as well as part-load, full-load, and most importantly, hot-start. In the present paper, the compressor and turbine tip clearances measured during such a load cycle are compared with calculated predictions. The experimental instrumentation for the prototype gas turbine, as well as design calculations, are presented.
The results show that the new Model V84.3 gas turbine does not exhibit critically small clearances during cold start nor during hot-start due to the careful matching of magnitude and the time constants of the thermal expansion of the blades, discs, blade-ring carriers and casing.
A Theory for the Hydrodynamic Performance of Centrifugal Pump Impellers in Stall
Authors: Dussourd Jules L. , Hermann Paul , Westhoff Paul E. 
Published: February 2015

A computerized analysis is presented which may have the potential of calculating the performance of turbomachines operating in the stalled regime. The method however is still in its infancy in that here only radial impellers pumping incompressible fluids and working with the simplest of diffusers are considered.
The physical model consists of a rotating cascade which admits forward flows as well as backflows existing concurrently, both described as time steady jets and wakes flowing on two stream surfaces which must be in equilibrium. The losses for non-reattaching flows are mainly the result of momentum exchanges, making it possible to develop a model somewhat, but not entirely free of empirical quantities.
The sum of the physical constraints that must be satisfied form a system of nine simultaneous equations with nine variables. Their solutions are computerized for PC work. The output yields the internal pressures and velocity diagrams, including quantification of the forward and backward flows, suction line vortexing, cavitation and overall performance.
To the extent that it could be explored to date, corroboration against test pumps measurements shows promising agreement using as criteria the absorbed power and in a more preliminary way, the intensity of the suction pipe phenomena and the head-flow curves when appropriate. The corroborations however have been carried out only for a few pumps.
Influence of Tip Clearance on the Inter Blade and Exit Flow Field of a Turbine Rotor Cascade
Authors: Govardhan M. , Venkatrayulu N. , Vishnubhotla V. S. 
Published: February 2015

A detailed study of flow through the blade passage and downstream of a linear turbine cascade was carried out for four cases of tip clearance including zero clearance. Apart from inlet traverse, a total of eight stations were chosen for inter-blade flow traversing between 5% and 95% of axial chord from leading edge. Downstream flow surveys were made at distances of 106% of axial chord from the blade leading edge. Pitchwise and spanwise traverses were conducted for each tip clearance at these stations using a small five hole probe. Provision was also made for the measurement of static pressure distribution on the suction and pressure surfaces and also on the blade tip surface when clearance is present.
At about 40% of axial chord from the leading edge, the presence of clearance vortex is identified inside the passage. The growth of the clearance vortex in size, its movement towards the suction surface and its increase in strength with the gap size were observed beyond 55% of axial chord till the trailing edge region. The rate of growth of the losses in the endwall region increased with clearance. Horse shoe vortex was not observed for the highest clearance. The overall losses increase rapidly with clearance in the rear half of the blade.
Development Requirements for an Advanced Gas Turbine System
Authors: Bannister R. L. , Cheruvu N. S. , Little D. A. , McQuiggan G. 
Published: February 2015

In cooperation with U.S. Department of Energy’s Morgantown Energy Technology Center, a Westinghouse led team is working on the second part of an 8-year, Advanced Turbine Systems Program to develop the technology required to provide a significant increase in natural gas-fired combined cycle power generation plant efficiency.
This paper reports on the Westinghouse program to develop an innovative natural gas-fired advanced turbine cycle which, in combination with increased thing temperature, use of advanced materials, increased component efficiencies and reduced cooling air usage, has the potential of achieving a lower heating value plant efficiency in excess of 60%.
Ceramic Hybrid Bearings in Air-Cycle Machines
Authors: Burgmeier Lyman , Poursaba Matt 
Published: February 2015

Extensive research in the field of ceramic rolling contact bearings has been conducted over the past several years. The results of this research indicate that silicon nitride may offer significant improvements in rolling fatigue life and a possible increase in operating temperature. AlliedSignal Aerospace Systems & Equipment (ASE) and the Air Force Item Management Engineering Branch at Tinker Air Force Base are conducting a development program under contract to ARPA to introduce ceramic hybrid bearings into existing F-15, F-111, and C-130 aircraft fleets in a near-term program involving retrofitting mature air-cycle machines with such bearings. The air-cycle machine (ACM) is a complex bearing application, operating at very high speeds (up to 100,000 rpm) and at high temperatures. In more severe military ACM applications, mean times between failures (MTBF’s) of 2000 and 3000 hours are common. The fleet would see an immediate benefit from improved bearing life.
This paper describes the analytical approach to evaluating and comparing ceramic to steel bearings, describes the laboratory test program to verify performance, and discusses the life-cycle cost improvement and the flight test program.
Hot Gas Cleaning for Combined Cycle Based on Pressurized Coal Combustion
Authors: Gudenau H. W. , Hoberg H. , Mayerhofer A. 
Published: February 2015

The aim of a project supported by the Minister of Science and Technology is the development of a process for gas cleaning at temperatures above 1573K. The simultaneous removal of particles and alkalis should be possible with this process. This hot gas cleaning ought to be integrated into an advanced combined cycle based on a pressurized slag tap furnace. The research concerning the development of a venturi scrubber with molten slag have been done at the Institute of Ferrous Metallurgy of the Technical University of Aachen.
Studies concerning the chemical and physical properties of slags are necessary to realize such a system for hot gas cleaning. This research must be followed by research concerning the influence of physical properties of slags such as viscosity or surface tension on the atomization of liquids. Furthermore, studies are necessary concerning the precipitation efficiency of a venturi scrubber with a liquid which has the same physical properties as slag.
This paper presents thermochemical calculations with regard to the absorption of gaseous alkalis by molten slag. Furthermore, it contains the investigations concerning the influence of alkali oxides on the viscosity of moltén slag.
Advantages of Air Conditioning and Supercharging an LM6000 Gas Turbine Inlet
Authors: Kolp Donald A. , Guidotti Harold A. , Flye William M. 
Published: February 2015

Of all the external factors affecting a gas turbine, inlet pressure and temperature have the greatest impact on performance. The effect of inlet temperature variations is especially pronounced in the new generation of high-efficiency gas turbines typified by the 40 MW GE LM6000. A reduction of 50 F (28 C) in inlet temperature can result in a 30% increase in power and a 4.5% improvement in heat rate. An elevation increase to 5000 feet (1524 meters) above sea level decreases turbine output 17%; conversely supercharging can increase output more than 20%.
This paper addresses various means of heating, cooling and supercharging LM6000 inlet air. An economic model is developed and sample cases are cited to illustrate the optimization of gas turbine inlet systems, taking into account site conditions, incremental equipment cost and subsequent performance enhancement.
A Modern Approach to Conceptual/Preliminary Design of Gas Turbine Based Propulsion Systems
Authors: Shahroudi Kamran Eftekhari 
Published: February 2015

This paper describes the development and implementation of the Natural Design Cycle to Conceptual/Preliminary Design of gas-turbine-based aircraft engines. The Natural Design Cycle is a high speed design optimization cycle within which the human designer is actively employed.
The CAGEDR (Computer Aided General Engine Design) was developed at Delft TU to closely mimic the Natural Design Cycle. The main objective of this exercise was to obtain a modern and efficient tool to assist engineers in the conceptual/preliminary phase of gas turbine based aircraft engine mechanical and thermodynamic design, by automating many of the laborious tasks involved while leaving all intuitive and decision making tasks to the human designer.
The topics discussed herein will be of interest to other propulsion software and/or CAD developers, Among them,
• The Natural Design Cycle and its advantages
• generation High Speed (or Real Time) Engine Models in the form of ANSI C Source Code
• Integration with Aircraft Design/Analysis
• Real Time Movement Through Design Space for “Human in the Loop” optimization (the Dyn-Carp and the Dyn-Hist modules)
• The role of Graphic User Interface for defining engine models
Externally Fired Combustion Cycle (EFCC) a DOE Clean Coal V Project: Effective Means of Rejuvenation for Older Coal-Fired Stations
Authors: LaHaye P. G. , Bary M. R. 
Published: February 2015

A long term program was initiated in 1987 to develop an electric utility indirect coal-fired gas turbine combined cycle. This initial program was supported primarily by U.S. electric utility organizations and had as a purpose the experimental assessment of a ceramic heat exchanger concept applied as a high pressure gas turbine air heater developed by Hague International.
The purpose of the initial phase of the development program was to determine if the ceramic materials, then available for use in the air heater, would withstand the high temperature 2200 F (1204 °C) corrosive environment produced by the combustion of coal. Also, in this initial phase, the program was intended to evaluate means of preventing the fouling of the air heater by fly ash. This experimental work was successful. A second phase of the program to build a 7-MW thermal input prototype was initiated in 1990 under the auspices of a cooperative agreement with the U.S. Department of Energy Morgantown Energy Technology Center (DOE-METC). This work was funded by a consortium of electric utilities, utility organizations, industrial organizations, state agencies, international entities, and the U.S. Department of Energy-METC. New members joined the existing Phase I Consortium to participate in funding the second phase. This second prototype phase is nearing completion and test results are to be available beginning mid-1994.
A third, or demonstration phase, of the indirect-fired gas turbine program was selected under the U.S. Clean Coal Technology Program Round V. in May, 1993. This demonstration phase is currently in the planning and preliminary engineering stage. The objective of this proposed demonstration phase is to repower an existing coal-fired power plant in the Pennsylvania Electric Company system at Warren, Pennsylvania (Figure 1). This paper describes the demonstration plant, and the anticipated role of the EFCC cycle in the power generation industry, as well as the performance and economic merits of the Warren repowering concept.
Analysis of Ganciclovir-Resistant Human Herpesvirus 6B Clinical Isolates Using Quenching Probe PCR Methodology
Authors: Hiramatsu Hiroyuki , Suzuki Ryota , Yamada Shigeki , Ihira Masaru , Isegawa Yuji , Kawamura Yoshiki , Matsuoka Erina , Miura Hiroki , Yoshikawa Tetsushi 
Published: February 2015

ABSTRACT
Quenching probe PCR (QP-PCR) analysis was used to determine the frequency of ganciclovir (GCV) resistance among clinical isolates of human herpesvirus 6B (HHV-6B) obtained from patients with primary viral infection and viral reactivation. Forty-two HHV-6B clinical isolates were repeatedly recovered from 15 hematopoietic stem cell transplant (HSCT) recipients, and 20 isolates were recovered from 20 exanthem subitum (ES) patients. Of the 15 HSCT recipients, 9 received GCV during the observation period; however, none of the ES patients were treated with GCV. Two established laboratory strains, Z29 and HST, were used as standards in this study. Regions 1 and 2 of the U69 gene of all of the clinical isolates demonstrated the same melting temperature as regions 1 and 2 of the Z29 strain. For region 3, the melting temperatures of all clinical isolates fell between the melting temperature of the plasmid containing the A462D single nucleotide polymorphism (SNP) and the melting temperature of the Z29 strain, and the melting temperatures profiles of all clinical isolates were similar to the melting temperature profile of the Japanese HST strain. As expected, none of the 20 clinical isolates recovered from the ES patients and the 14 isolates recovered from the HSCT recipients who did not receive GCV treatment carried the six known SNPs associated with GCV resistance. Interestingly, these six SNPs were not detected in the 28 clinical isolates recovered from the 9 HSCT recipients who received GCV. Additional sequence analysis of the U69 gene from the 15 representative isolates from the 15 HSCT recipients identified other SNPs. These SNPs were identical to those identified in the HST strain. Therefore, the rate of emergence of GCV-resistant HHV-6B strains appears to be relatively low, even in HSCT recipients treated with GCV.
Colistin Resistance Mechanisms in Klebsiella pneumoniae Strains from Taiwan
Authors: Cheng Yi-Hsiang , Lin Tzu-Lung , Pan Yi-Jiun , Wang Yu-Ping , Lin Yi-Tsung , Wang Jin-Town 
Published: February 2015

ABSTRACT

Colistin is one of the antibiotics of last resort for the treatment of carbapenem-resistant
Klebsiella pneumoniae
infection. This study showed that capsular type K64 (50%) and ST11 (53.9%) are the prevalent capsular and sequence types in the colistin-resistant strains in Taiwan. The interruption of transcripts (38.5%) and amino acid mutation (15.4%) in
mgrB
are the major mechanisms contributing to colistin resistance. In addition, novel single amino acid changes in MgrB (Stop48Tyr) and PhoQ (Leu26Pro) were observed to contribute to colistin resistance.