bluuebunny/crossref_metadata_2025 huggingface dataset:
Log-canonical pairs and Gorenstein stable surfaces with
Authors: Franciosi Marco , Pardini Rita , Rollenske Sönke
Published: April 2015

We classify log-canonical pairs $(X,{\rm\Delta})$ of dimension two such that $K_{X}+{\rm\Delta}$ is an ample Cartier divisor with $(K_{X}+{\rm\Delta})^{2}=1$, giving some applications to stable surfaces with $K^{2}=1$. A rough classification is also given in the case where ${\rm\Delta}=0$.
Feedwater Heating Allocation Optimization for Large Capacity Steam Turbine Unit Based on Particle Swarm Optimization
Authors: Fu Wenfeng , Yang Xueming , Wang Lanjing , Yang Yongping
Published: April 2015

The allocation of feedwater heating in regenerative heaters is one of the important points related to the thermo-economy analysis of thermal power plants. Optimizing the allocation of feedwater heating can obtain obvious economic benefits without additional equipment investment or material consumption. Based on a modified particle swarm optimization (PSO), this paper proposes a numerical model for feedwater heating allocation problem in selecting the optimum feedwater heating allocation of large capacity steam turbine unit. A real case of a 600 MW steam turbine unit shows that the optimized results are significantly better than the original design value. The proposed method is convenient for analyzing and solving the problem of optimum feedwater heating allocation, and the results presented in this work should have important implications in the design and tapping energy-saving potential of large capacity steam turbine unit.
Design and Implementation of a Binary Redundant Manipulator With Cascaded Modules1
Authors: Tzorakoleftherakis Emmanouil , Mavrommati Anastasia , Tzes Anthony
Published: April 2015

The subject of this paper is the design and implementation of a prototype snakelike redundant manipulator. The manipulator consists of cascaded modules eventually forming a macroscopically serial robot and is powered by shape memory alloy (SMA) wires. The SMAs (NiTi) act as binary actuators with two stable states and as a result, the repeatability of the manipulator's movement is ensured, alleviating the need for complex feedback sensing. Each module is composed of a customized spring and three SMA wires which form a tripod with three degrees of freedom (DOFs). Embedded microcontrollers networked with the I2C protocol activate the actuators of each module individually. In addition, we discuss certain design aspects and propose a solution that deals with the limited absolute stroke achieved by SMA wires. The forward and inverse kinematics of the binary manipulator are also presented and the tradeoff between maneuverability and computational complexity is specifically addressed. Finally, the functionality and maneuverability of this design are verified in simulation and experimentally.
The Undercut Criterion of Pinion Shaper Cutters: And an Improvement by Modifying the Basic Rack Profile
Authors: Svahn Mattias
Published: April 2015

The fillet of the gear tooth is highly stressed in operation; so for heavily loaded gears, the fillet geometry must be controlled. The manufacturer's task is to, within acceptable tolerances, produce the gear to the designer's specifications regardless of the manufacturing method. Most often gear cutting tools are used that work under generating conditions. The tool will form the gear tooth; so to produce the specified gear geometry and, especially, the fillet geometry, this tool must be conjugated to the same basic rack as the gear to cut. However, this gives a risk that the tooth tip of the tool will be undercut, and if this occurs the tool will not cut the intended gear fillet. In this report, novel analytical equations are derived, which predict the limit when the tool tip will be undercut. It is shown that if the gear tooth should be conjugated to the standard basic rack with a circular fillet, which is the normal case, very large tool-tooth numbers are needed for pinion shaper cutters and gear skiving cutters to avoid this type of undercut. However, the minimum tooth number to achieve a smooth continuous tool-tooth profile is reduced by modifications to the fillet of the basic rack profile.
An LNG Carrier Adjustable Speed Gas Turbine Electric Propulsion System
Authors: Hauschildt M. R. , Gripp L. P. , Peters W.
Published: April 2015

This paper describes the design of a 43,000 shp (32,065 KW), 110 propeller rpm, Liquid Natural Gas (LNG) Carrier, gas turbine AC electric, adjustable speed propulsion system, burning LNG and/or diesel fuels. Excess boil-off energy is dissipated through a load bank resistor system. Boil-off compressor, ship service electric loads and auxiliary steam services are supplied by waste heat boilers. A relative economic and operating characteristic comparison of steam vs gas turbine electric LNG propulsion plants is presented for various assumed fuel costs. The ship application is a single shaft, 125,000 cubic meter LNG Carrier of about 96,000 tons (97,541 tones) displacement.
The Venting Characteristics of a Fibrous Thermal Barrier System During a Rapid Depressurization Accident (Rotor Failure) in an HTGR-GT
Authors: Lightner S. , Betts W. S.
Published: April 2015

The thermal barrier inside the primary circuit of the direct-cycle, high-temperature gas-cooled reactor-gas turbine (HTGR-GT) may experience rapid depressurization transients. Turbine rotor failure induces the most severe pressure transient. To determine how rotor failure affects the design adequacy of the thermal barrier, the authors experimentally examined the venting characteristics of the fibrous insulation. This paper theoretically develops a simulation technique and correlates the analytical results with test data.
A Model for Dynamic Loss Response in Axial-Flow Compressors
Authors: Sexton M. R. , O’Brien W. F.
Published: April 2015

An experimentally-determined dynamic loss response function was developed and incorporated in a model to predict the rotating stall behavior of an experimental compressor. The loss response model was developed employing Fourier transforms. The basis of the compressor model is a mathematical representation of the flow fields upstream and downstream of the compressor rotor. The compressor rotor is represented in the model by a semi-actuator disc. The results of the investigation show that the physical mechanisms which control the onset and propagation velocity of rotating stall in a single-stage compressor can be modeled with the use of the loss response function in a semi-actuator disc model of the compressor. The function represents the dynamic loss characteristics of the compressor rotor row, and provides important advantages over previous techniques.
Maintenance of Aero-Derived Industrial Gas Turbines
Authors: Porter B.
Published: April 2015

The aero derived industrial gas generator has for many years been the source of power for pumping and electrical generation both onshore and offshore in many parts of the world. These lightweight units are operating in every conceivable climate and geographical location and as such have proved themselves particularly suitable for use in the harsh environment of the North Sea. The advantages of this type of unit for offshore operation are: compact size, high power to weight ratio lightweight modular construction, rapid black start capability, fast load change response, low onsite routine inspection/maintenance downtime, fast turn round heavy maintenance and speedy unit change out.
Tube Stresses in the Radiation Part of Solar Receivers and of Conventionally Fired Heaters
Authors: Bammert K. , Seifert P.
Published: April 2015

The tubes for the receiver of a solar power plant are designed taking into account thermal and mechanical loads. The receiver transfers 60 MW of heat to the working medium of a closed cycle gas turbine, the medium being air. It is shown how the stress pattern in the tubes are influenced by the distribution of the locally absorbed heat flux, assuming linearly elastic deformation of the tube material. Criteria for the influence of the partially plastic behavior of the tubes are discussed for different distributions of the intensity of the absorbed heat flux.
NASA Gas Turbine Stator Vane Ring
Authors: Gersch H. M.
Published: April 2015

AiResearch Casting Company has produced four monolithic stator vane rings from reaction-bonded silicon nitride. This paper describes the various steps involved: wax injection of stator vane patterns, precise fixturing of patterns, mold fabrication, slip preparation, casting, prenitriding, nitriding, and ceramic machining. Each process step is discussed and illustrated, and tables of property measurements are included.
MS9001E: A New 100 MW Gas Turbine
Authors: Rucigay J. C. , Orsino A. J.
Published: April 2015

A new 100 MW gas turbine has been designed for electric power generation for either simple cycle or combined cycle applications. This paper describes the basis for design, new design features, performance, and test program.
The Westinghouse 501D Combustion Turbine Engine
Authors: Scalzo A. J. , Holden P. C. , Howard G. S.
Published: April 2015

The Westinghouse 501D combustion turbine engine is the latest in a long line of Westinghouse designed and manufactured large single shaft heavy duty gas turbines designed especially for 60 Hz utility or industrial service. This 100 MW engine is described along with the design techniques utilized and the evolutionary changes made from previous engines. Also described are the component, shop, and field test conducted to bring the engine to fruition.
Use of Cascade and Small Turbine Tests to Determine Erosion of Utility Turbines
Authors: Wenglarz R. A. , Menguturk M.
Published: April 2015

Experiments using cascades and small turbines have been conducted or are being considered to simulate large utility turbine operation with future coal-fired power plants. The purpose of these experiments is to evaluate utility turbine tolerances to particulates and to determine gas cleanup requirements for successful turbine performance. Since these tests do not fully reproduce the flow and erosion conditions in large utility turbines, this paper explores the interpretation of data from simulation experiments to assess erosion in large utility turbines. Effects of physical scale, rotation speed, and pressure differences between test cascades and small test turbines and large utility turbines are considered.
Improved Particle Trajectory Calculations Through Turbomachinery Affected by Coal Ash Particles
Authors: Beecher B. , Tabakoff W. , Hamed A.
Published: April 2015

Trajectories of small coal ash particles encountered in coal-fired gas turbines are calculated with an improved computer analysis currently under development. The analysis uses an improved numerical grid and mathematical spline-fitting techniques to account for three-dimensional gradients in the flow field and blade geometry. The greater accuracy thus achieved in flow field definition improves the trajectory calculations over previous two-dimensional models by allowing the small particles to react to radial variations in the flow properties. A greater accuracy thus achieved in the geometry definition permits particle rebounding in a direction perpendicular to the blade and flow path surfaces rather than in a two-dimensional plane. The improved method also accounts for radial variations in airfoil chord, stagger, and blade thickness when computing particle impact at a blade location.
Gemini T-20G-8 XM1 Tank APU
Authors: Rodgers C. , Zeno J. , Drury E. A. , Karchon A.
Published: April 2015

Auxiliary power is often provided on combat vehicles in the U.S. Army for battery charging, operation of auxiliary vehicle equipment when the main engine is not running, or to provide assistance in starting the main engine in extreme cold weather conditions. The use of a gas turbine for these applications is particularly attractive, due to its small size and lightweight. In November 1978, the U.S. Army Tank-Automotive Research and Development Command, Warren, MI awarded a contract to the Turbomach Division of Solar Turbines International, San Diego, CA, for the development of a 10 kW 28 vdc gas turbine powered auxiliary power unit (APU) for installation in the XM1 main battle tank. This paper describes the general features of the Solar Turbomach T-20G-8 Auxiliary Power Unit, a single-shaft gas turbine driven generator set which has been developed under this contract. This APU is one of the family of Gemini powered APUs and is a derivative of the U.S. Army 10 kW gas turbine engine-driven, 60 and 400 Hz generator sets developed by Solar. The electrical components were newly developed for this particular application. Currently, the APU is in qualification testing both in the laboratory and in the XM1 main battle tank.
On the Performance Prediction of a Centrifugal Compressor Scaled Up
Authors: Mashimo T. , Ariga I. , Sakai T. , Watanabe I.
Published: April 2015

A centrifugal compressor performance prediction method, in which each loss generated within the compressor stage was estimated by recognizing the individual relationship with Mach number, was investigated over a wide range of sizes and types. Calculation formulae for the losses were established by analyzing test results. It was confirmed that the formulae could be applied to predict the performance levels of compressors with impeller diameters from 78 mm to 640 mm by refering to unpublished test data obtained experimentally by other researchers. From the results, it could be deduced that: (1) The wall friction losses and the secondary flow losses within the compressor decreased with increase of impeller size. (2) The leakage flow losses were found to increase when scaling up the compressor, even when tip clearance/blade height were held constant. The present paper presents a progress report of work still underway.
Factory Testing Gas Turbines and Driven Equipment for Prudhoe Bay, Alaska (EOA)
Authors: Broadbent L. L.
Published: April 2015

The high costs which could result from delays in startup, unscheduled shutdowns, and field repairs in the Eastern Operating Area (EOA) at Prudhoe Bay have provided the impetus for an extensive factory testing program for gas turbines and their driven equipment. The testing program devised for proving out the rotating equipment in the manufacturer’s facilities, thus eliminating the transfer of problems to the field, is presented in this paper. The trains of equipment tested, the types of tests conducted, the data obtained, the evaluation techniques, and the results achieved are also presented.
Integrated Aircraft Avionics and Powerplant Control and Management Systems
Authors: McNamara J. , Seabridge A. G.
Published: April 2015

The paper describes a joint British Aerospace/Rolls Royce study on the role of the Powerplant Control System in a high technology combat aircraft. The need to reduce pilot workload and the trend towards the use of Integrated Avionic Systems and Serial Digital Data Transmission on modern aircraft projects has forced a change in the traditional approach to powerplant control system design. The principles of Fault Tolerance with the ability of the Powerplant Control System to survive combinations of faults is described. An ideal system is presented which will provide benefits for the airframe constructor. The utilization of cheap, accurate and reliable microprocessor devices with compatible L.S.I. MIL-STD-1553 Chip Sets offers an attractive solution to aircraft avionic data transmission systems including Powerplant Control and Management for future aircraft.
Utilization of Coal-Derived Fuel in Advanced Power Generation Systems: An Evaluation
Authors: Lessard R. D. , Robson F. L. , Blecher W. A. , Carlson A. W.
Published: April 2015

This paper highlights a recently completed study program to evaluate the performance and cost of advanced power generation systems which utilize coal-derived, medium-Btu fuel gas. Three advanced power generation systems are covered: combined-cycle gas turbine, molten carbonate fuel cell, and open-cycle MHD/steam. Two coal gasification processes for supplying the medium-Btu fuel gas are considered; they are the oxygen-blown Texaco process and British Gas Corporation/Lurgi process or simply BGC process. Descriptions of the advanced power generation systems and of the medium-Btu fuel gas supplied by the gasification processes are provided. The performance of each of the advanced power generation systems is evaluated when utilizing coal-derived, medium-Btu fuel gas supplied 1) via pipeline from each of the two coal gasifiers, and 2) through integration with each of the two coal gasifiers. Estimates of electric power costs are given.
Erosion Resistance and Efficiency of Energy Exchangers
Authors: Thayer W. J. , Taussig R. T.
Published: April 2015

Applications of energy exchangers, a type of gasdynamic wave machine, were evaluated in power plants fired by pressurized, fluidized bed combustors (PFBCs). Comparative analyses of overall power plant efficiency indicate that the use of energy exchangers as hot gas expanders may provide a 0.5 to 1.5 efficiency point increase relative to gas turbines. In addition, the unique operating characteristics of these machines are expected to reduce rotating component wear by a factor of 50 to 300 relative to conventional gas turbines operating in the particulate laden PFBC effluent stream.
Application of Heavy Fuel Test Results to Gas Turbine Operation
Authors: Rose R. S. , Caruvana A. , Cohn A. , Von Doering H.
Published: April 2015

The results of ash deposition tests with simulated residual oil are presented. Both air-cooled and water-cooled nozzles were tested over a range of firing temperature, fuel contaminant levels, and metal surface temperatures. Extensive ash cleaning tests were also completed under full, steady-state operating conditions. Various online ash removal techniques were tested including small nutshells, large nutshells, coke particles, and water droplets. The results of these tests were applied to a General Electric gas turbine to predict actual field operation at turbine inlet temperatures up to 2300°F (1260°C). Use of on-line ash removal and optimum water washing intervals are shown to significantly improve the economics of gas turbine operation on heavy fuels. The improvements in heavy fuel operation were larger with a water-cooled stage 1 nozzle than with an air-cooled nozzle. This work was jointly sponsored by the Electric Power Research Institute and General Electric under the Advanced Cooling, Full-Scale Engine Demonstration Program.
Theoretical and Experimental Investigations About Vaneless Return Channels of Multi-Stage Radial Flow Turbomachines
Authors: Fister W. , Zahn G. , Tasche J.
Published: April 2015

Based on the Navier-Stokes-Equations, a numerical method which is a variation of the “partially-parabolic” approach used by Moore et al., was applied to calculate the three-dimensional, turbulent, viscous flow in vaneless return channels of multistage radial flow turbomachines. To avoid the high demand for computer time and storage capacity generally needed for the numerical treatment of the Navier-Stokes-Equations, the method is restricted to the calculation of flows with a predominant flow direction without separation. The procedure carries out an iteration between a marching integration of the conservation equations through the three-dimensional flow field along the mean flow direction and the solution of an elliptic pressure correction equation. So it is guaranteed that downstream influences can be considered upstream.
Local Heat Transfer to Staggered Arrays of Impinging Circular Air Jets
Authors: Behbahani A. I. , Goldstein R. J.
Published: April 2015

Measurements are made of the local heat transfer from a flat plate to impinging arrays of staggered circular air jets. Fluid from the spent jets is constrained to flow out in one direction. Two different jet-to-jet spacings, 4 and 8 jet diameters, are employed. The parameters that are varied include jet-orifice-plate to impingement-surface spacing and jet Reynolds number. Local heat transfer coefficients vary periodically both in the flow direction and across the span with high values occurring at stagnation regions. Stagnation regions of individual jets as determined by local heat transfer coefficients move further in the downstream direction as the amount of crossflow due to upstream jet air increases. Local heat transfer coefficients are averaged numerically to obtain spanwise and streamwise-spanwise averaged heat transfer coefficients.
A General Performance Model for the Open-Loop Water-Cooled Gas Turbine
Authors: El-Masri M. A. , Kobayashi Y. , Louis J. F.
Published: April 2015

A thermodynamic efficiency analysis of a simple open cycle, open-loop, water-cooled gas turbine is presented. Losses due to water pumping work, mixing of water and steam with turbine gas, and heat transfer from the gas are included. To achieve generality and provide system design guidelines, the results are presented in terms of dimensionless variables. It is shown that system performance is strongly influenced by water tip exit quality. Sample calculations reveal the optimum turbine inlet temperature for different pressure ratios using typical values of the dimensionless parameters. The results are presented for two different approaches: either the tip quality is treated as a given quantity or it is calculated using a model for the channel critical heat flux. The sensitivity of the cycle efficiency to each parameter is reported. The influence of water collection on cycle efficiency is assessed.
Advanced Turboprop Engines for Long Endurance Naval Patrol Aircraft
Authors: Hirschkron R. , Davis R. H.
Published: April 2015

Long endurance naval patrol aircraft of the future will require more efficient advanced turboprop powerplants. Engines used in this kind of application will have performance requirements emphasizing prolonged endurance and very low specific fuel consumption for cruise and part-power loiter operation. Regenerative, regenerative/intercooled and advanced conventional cycle screening studies were carried out to select the cycle pressure ratio and turbine temperature for each type, considering the effects on installed performance and weight. Design and cycle choices were studied in each engine category including recuperator types, effectiveness, pressure drop, bypass bleed and variable area turbine nozzle. The engine characteristics of each type were then compared using a representative mission. The advanced conventional engine showed the largest potential, the regenerative second and the regenerative/intercooled the least promise for lower installed fuel consumption and improved mission performance.
Experimental Evaluation of Squeeze Film Supported Flexible Rotors
Authors: Rabinowitz M. D. , Hahn E. J.
Published: April 2015

This paper describes the experimental investigations which were conducted to verify existing theoretical vibration amplitude predictions for centrally preloaded, squeeze film supported flexible rotors. The influence of measurement errors and operating condition uncertainties are quantified. The agreement between theory and experiment was excellent, and it is shown that any discrepancy can be explained in terms of errors in determining the mean lubricant viscosity and the orbit magnitudes. Hence, for the range of parameters investigated, the theoretical model and predictions therefrom are validated.
The Response of a Geared Compressor Set to Torsional Excitation Accounting for Damping and Flexibility in the Bearings and Damping and Backlash in the Gear
Authors: Simmons P. E.
Published: April 2015

A mathematical model representing the torsional characteristics of a machine train including a gear has been developed incorporating a number of features which are usually neglected, namely, damping and flexibility in the bearings and damping, backlash and pitch error in the gear teeth. This model has been used in conjunction with a computer simulation language to predict the performance of a geared compressor in which there is a torsional resonant frequency close to twice the motor speed.
Ceramic Thermal Barrier Coatings for Gas Turbine Engines
Authors: Bratton R. J. , Lau S. K. , Andersson C. A. , Lee S. Y.
Published: April 2015

Ceramic thermal barrier coatings are currently under active development in the U.S. for both aircraft and industrial/Utility gas turbine operation. These coating systems generally consist of an oxidation-corrosion resistant metal bond coat of the MCrAlY type and either a single thick layer ceramic overcoat or a graded ceramic/MCrAlY overcoat. This paper summarizes studies conducted on the high-temperature corrosion resistance of ZrO2 · Y2O3, ZrO2 · MgO and Ca2SiO4 plasma sprayed coatings that are candidates for use as thermal barrier coatings in gas turbine engines. Coatings were evaluated in both atmospheric burner rig and pressurized passage tests using GT No. 2 fuel and that doped with corrosive impurities such as sodium, sulfur and vanadium. The test results showed that the coatings perform very well in the clean fuel pressurized passage tests as well as burner rig tests. With impure fuels, it was found that chemical reactions between the ceramic coatings and combustion gases/condensates played the critical role in coating degradation. This work was conducted for NASA and EPRI under contract NAS3-21377. Advanced coating development studies have also been conducted for NASA and DOE under contract DEN3-110.
Investigation of the Transonic Calibration Characteristics of Turbine Static Pressure Probes
Authors: Langford R. W. , Keeley K. R. , Wood N. B.
Published: April 2015

Measurement of static pressure in transonic turbines is made difficult because of the need to use probes with substantial support stems in the measurement plane, enabling them to traverse in the confined axial spaces between blade rows. Problems arise because of shock interactions with the probes and the close proximity of shock-reflecting surfaces. Tests show that the calibration can depend on the proportion of probe support immersed in the transonic flow. The wind tunnel gives only partial representation of the turbine transonic flow field, but by using turbine measured and computed static pressures the most representative calibration is selected.
Unsteady Gapwise Periodicity of Oscillating Cascaded Airfoils
Authors: Carta F. O.
Published: April 2015

Tests were conducted on a linear cascade of airfoils oscillating in pitch to measure the unsteady pressure response on selected blades along the leading edge plane of the cascade and over the chord of the center blade. The pressure data were reduced to Fourier coefficient form for direct comparison, and were also processed to yield integrated loads and, particularly, the aerodynamic damping coefficient. In addition, results from two unsteady theories for cascaded blades with nonzero thickness and camber were compared with the experimental measurements. The three primary results that emerged from this investigation were: (a) from the leading edge plane blade data, the cascade was judged to be periodic in unsteady flow over the range of parameters tested, (b) as before, the interblade phase angle was found to be the single most important parameter affecting the stability of the oscillating cascade blades, and (c) the real blade theory and the experiment were in excellent agreement for the several cases chosen for comparison.
Plain-Jet Airblast Atomization of Alternative Liquid Petroleum Fuels Under High Ambient Air Pressure Conditions
Authors: Jasuja A. K.
Published: April 2015

An investigation has been conducted of the effects that air and fuel properties have upon the spray mean dropsize characteristics of a plain-jet airblast atomizer of the type employed in the gas turbine engine. The fuels tested included kerosine, gas oil and a high-viscosity blend of gas oil in residual fuel oil. The tests covered a wide range of ambient air pressures. Well established laser light-scattering technique was employed for dropsize measurements. The experimental data collected in the present investigation are presented in this paper and comparisons are made against similar data relating to the pre-filming type of airblast atomizer, collected in an earlier study (2).
Experimental Study of External Fuel Vaporization
Authors: Szetela E. J. , TeVelde J. A.
Published: April 2015

Experiments were run to investigate the feasibility of a flash vaporization system for aircraft gas turbine engines. The experiments consisted of a determination of boiling points, dew points, critical temperature, critical pressure, heat transfer coefficients, deposit formation rates, and deposit removal in a flowing system. Three fuels were included in the experiments including Jet-A, ERBS, and a premium No. 2 diesel fuel. Engine conditions representing the E3 at SLTO, cruise and idle were simulated in the vaporization system and it was found that single phase flow was maintained in the heat exchanger and downstream of the throttle. Deposits encountered in the heat exchanger represented a thermal resistance as high as 1.3 × 103 M2 K/watt and a deposit formation rate over 1000 gC/cm2 hr. It was found that the deposit can be removed by cleaning with air at a temperature of 720 K for 10 minutes.
Turbine Blade Tip Clearance Measurements in a Large Industrial Two-Shaft Gas Turbine
Authors: Van Den Andel J.
Published: April 2015

In horizontally split gas turbines, distortions of the cylinders may be expected, especially during start-up conditions. This article describes how the distortions of an inner cylinder were first measured outside the turbine by placing it on a horizontal boring mill while heating the inner diameter. Modifications were made to reduce the distortion and the difference is shown. The cylinder was then tested in the actual turbine (CW352) where the diameter was compared with the presumably perfect circle described by the passing blades. Three monitors were used to determine the gap between the blades and the seal plates which are a part of the inner cylinder. Described is how a high accuracy is obtained using complex touch probe actuators and an electronic control unit which computes the blade-to-seal-plate gap and displays it for read out. A computer interface allows the information to be stored in the master computer for recall.
AGT-102 Advanced Automotive Gas Turbine Powertrain
Authors: Wagner C. E. , Chapman W. I.
Published: April 2015

This paper describes the initial design of the AGT-102 advanced automotive gas turbine powertrain by Chrysler Corporation and Williams International Corporation. It reflects an emphasis on simplicity, light weight, driveability, producibility, packageability, and competitive overall cost appropriate to future front wheel drive vehicles. The basic engine is a 78-hp, single-shaft, gas turbine engine with a 2300 °F (1260 °C) turbine inlet temperature and a rotor speed of 99,500 rpm. The engine has a centrifugal compressor, ceramic radial turbine, dual ceramic regenerator, and a lean premixed, prevaporized, fixed geometry combustor. The vehicle is driven through a two-range, synchronous shift, metal compression belt continuously variable transmission. A response assist flywheel is incorporated into the reduction gear train to achieve acceptable levels of engine response.
Evaluation of Coated Combustion Turbine Components From Saudi Arabia
Authors: Barksdale D. C. , Scheirer S. T. , Spengler C. J. , Aeschbacher H. J. , Ziady G. N.
Published: April 2015

Combustion turbines have been in service in Saudi Arabia for many years. Over this period, it has become apparent that the unique conditions of high sulfur gas fuel (sometimes with liquid carryover) and wind blown sand and salt particles result in a serious turbine hot corrosion problem. Metallurgical study of service blades and vanes, together with site analyses, served as background for a detailed laboratory coating evaluation. As a result, two corrosion resistant coatings fan electron beam physical vapor deposited CoCrAlY overlay and a pack diffusion Rh-Pt aluminide) were selected for application to turbine blades and vanes installed in Westinghouse W501D units for service in Saudi Arabia. State-of-the-art inlet air filtration was also installed to further reduce the possibility of hot corrosion. Comparisons were made between the two coatings after as much as 20,000 hr of service, and results were correlated with laboratory pressurized rig tests conducted under simulated conditions. In general, the performance of the CoCrAlY overlay coating was superior to that of the Rh-Pt aluminide diffusion coating.
The Effect of Fuel Composition on Hot Section Performance of a Gas Turbine Engine
Authors: Rutter Stephen
Published: April 2015

The combustor system of an AVCO Lycoming T53-L-13B turboshaft engine was tested to identify fuel properties detrimental to engine performance or hot section durability, and to measure their effect. Test fuels were characteristic of current and near-term alternate fuels for military aircraft. Relations were developed for altitude ignition, particulate emissions, combustion efficiency, and combustor liner life. Fuel hydrogen content was found to be an important consideration for particulates and combustor liner life, while fuel viscosity, density and mass transfer number were important to idle efficiency and altitude ignition.
The Application of Air Dynamometers for Testing Turbo-Shaft Gas Turbine Engines
Authors: Foor William B. , Jansen Willem
Published: April 2015

Testing of turbo-shaft engines requires power absorption devices that must be capable of stable operation at both variable powers and speeds (idle, take-off, cruise). A dynamometer transfers the engine shaft power to the incoming fluid and transforms it into thermal energy. An air-dynamometer has many advantages and is preferred over water brakes or electric generators, but must be made to operate stably over a wide range of speeds and powers.
Design of Highly Loaded Blade Profiles Using an Iterative Inverse-Direct Computational Procedure
Authors: Miton Hubert , Sankale Hervé , Chauvin Jacques
Published: April 2015

This paper describes the principle of a transonic blade design process based on a numerical approach combining an inverse and a direct methods of flow calculation, and its application to a transonic turbine stage.

The initial data required are the Mach vector distribution (in magnitude and direction) on a starting streamline (usually the succion side), and the distribution of one component of the velocity vector (magnitude or direction) in the channel inlet and outlet plane.

The example used is related to three cascade sections of a single heavily loaded turbine.

In its present state, the very fast inverse method (less than 1 sec. C.P.U. on an IBM 3033) cannot, by itself, provide a satisfactory design, as it does not include automatically the flow periodicity conditions. This justifies the combined and iterative use of a direct method to obtain the coherence of the process.

With this better approach, satisfactory cascade geometry can be provided.
Axial Compressor Performance Restoration by Blade Profile Control
Authors: Roberts William B.
Published: April 2015

One major source of increased compressor losses is imperfection in blade shape. These imperfections exist for new blades, and as an engine wears in service, the blade shapes become further distorted due to erosion. These imperfections cause an aerodynamic performance penalty in the form of decreased engine capability and increased fuel consumption.

A simple numerical blade element panel method, combined with a integral boundary layer technique, has been used to make an aerodynamic analysis of the effect of imperfections in blade shape for compressor blading. This analysis indicated what blade shapes would give increased profile losses, and what kind of reshaping allows restoration of nominal performance.

The results of this study were tested by a series of engine cell tests with JT8D engines. These tests indicate that new or used blades that have been sorted, properly re-shaped, and matched allow a superior recovery of performance compared with traditional blade refurbishment practices.
Corrosion and Corrosion Control in Gas Turbines: Part II — The Turbine Section
Authors: Mom A. J. A. , Kolkman H. J.
Published: April 2015

The phenomenology of the corrosion processes in the turbine section, including the conditions which govern corrosion behaviour, like temperature, pressure, fuel quality and presence of sulphur are discussed.

Various methods to combat the corrosion attack are described: limits to be imposed on fuel and intake air impurities, the use of fuel additives, and the application of corrosion resistant materials and coatings. The background to and the merits of these methods are discussed.

Furthermore service experience with current and advanced coating systems in marine, industrial and aircraft gas turbines is reported.

Corrosion processes in the compressor section are discussed in part I.
Aeronautical Propulsion: Present Status and Future Directions
Authors: Hartmann Melvin J.
Published: April 2015

The advancement of aeropropulsion systems continues to provide technology to various portions of the gas turbine field. It is recognized that this area is undergoing considerable change, which will result in substantially improved gas turbine components and systems. These changes are occurring in a number of technical areas including advanced analytical and physical measurement methods, the application of large scientific computers, the dynamic modeling of components and systems, the application of integrated control systems that optimize and improve performance and system condition monitoring, and the development of new and unique materials and structures. As these areas evolve, the ways in which technology will advance, and factors affecting the design and development of new systems, will probably be considerably different than those of today. It is also anticipated that the necessary skilled work force will be different. Certainly there will be changes, but the nature, extent, and rate of those changes can only be surmised at this time.
Intestinal invagination secondary to intestinal adenocarcinoma in coeliac disease
Authors: Sahin Cem , Ozseker Burak , Sagiroglu Tamer , Cullu Nesat
Published: April 2015

Invagination is defined as a medical condition in which a part of the gastrointestinal tract has entered into another section. Intestinal invagination is a rare clinical entity among adults and there is an underlying structural lesion in most of the cases. Coeliac disease is considered as a risk factor for intestinal invagination, because of the associated inflammatory processes and motility disorders as well as the increased risk for secondary malignancies. We report a case of intestinal invagination secondary to intestinal adenocarcinoma in a woman with coeliac disease, whose adherence to a gluten-free diet was poor.
Timing is everything in the treatment of multiple sclerosis
Authors: McCarthy Claire Louise , Giovannoni Gavin , Coles Alasdair John
Published: April 2015

We present two similar cases of relapsing–remitting multiple sclerosis, both of whom received treatment with the monoclonal antibody alemtuzumab, but had significantly different long-term outcomes. Patient A is 12 years into his illness and was treated early in his disease course, he has no disability and continues to perform at a high level as a professional golfer. Patient B was initially started on interferon-β1a therapy and went on to have two disabling relapses on this treatment which resulted in a degree of fixed disability prior to the start of alemtuzumab. 10 years into his disease course he has moderate disability and daily symptoms of spasticity in his legs which impair his quality of life. These two contrasting cases highlight the difficult decision of when to start potent immune modulating therapies for multiple sclerosis in young adults who appear well early in their disease but have the potential to rapidly accrue irreversible disability from future relapses.
Evidence for a persistent, major excess in all cause admissions to hospital in children with type-1 diabetes: results from a large Welsh national matched community cohort study
Authors: Sayers Adrian , Thayer Daniel , Harvey John N , Luzio Stephen , Atkinson Mark D , French Robert , Warner Justin T , Dayan Colin M , Wong Susan F , Gregory John W
Published: April 2015

Objectives

To estimate the excess in admissions associated with type1 diabetes in childhood.

Design

Matched-cohort study using anonymously linked hospital admission data.

Setting

Brecon Group Register of new cases of childhood diabetes in Wales linked to hospital admissions data within the Secure Anonymised Information Linkage Databank.

Population

1577 Welsh children (aged between 0 and 15 years) from the Brecon Group Register with newly-diagnosed type-1 diabetes between 1999–2009 and 7800 population controls matched on age, sex, county, and deprivation, randomly selected from the local population.

Main outcome measures

Difference in all-cause hospital admission rates, 30-days post-diagnosis until 31 May 2012, between participants and controls.

Results

Children with type-1 diabetes were followed up for a total of 12 102 person years and were at 480% (incidence rate ratios, IRR 5.789, (95% CI 5.34 to 6.723), p<0.0001) increased risk of hospital admission in comparison to matched controls. The highest absolute excess of admission was in the age group of 0–5 years, with a 15.4% (IRR 0.846, (95% CI 0.744 to 0.965), p=0.0061) reduction in hospital admissions for every 5-year increase in age at diagnosis. A trend of increasing admission rates in lower socioeconomic status groups was also observed, but there was no evidence of a differential rate of admissions between men and women when adjusted for background risk. Those receiving outpatient care at large centres had a 16.1% (IRR 0.839, (95% CI 0.709 to 0.990), p=0.0189) reduction in hospital admissions compared with those treated at small centres.

Conclusions

There is a large excess of hospital admissions in paediatric patients with type-1 diabetes. Rates are highest in the youngest children with low socioeconomic status. Factors influencing higher admission rates in smaller centres (eg, “out of hours resources”) need to be explored with the aim of targeting modifiable influences on admission rates.
Anaemia prevalence and associated factors among lactating mothers in Ethiopia: evidence from the 2005 and 2011 demographic and health surveys
Authors: Lakew Yihunie , Biadgilign Sibhatu , Haile Demewoz
Published: April 2015

Objective

To identify factors associated with anaemia in lactating mothers in Ethiopia.

Design

A cross-sectional secondary analysis of data pooled from two rounds of the 2005 and 2011 Ethiopian Demographic and Health Survey (EDHS) was used. A multivariate logistic regression model was applied to determine the factors associated with anaemia.

Population

A total of 7332 lactating mothers (2285 from EDHS 2005 and 5047 from EDHS 2011) were included from 11 administrative states of Ethiopia.

Main outcome measures

Lactating mothers considered anaemic if haemoglobin level <12 g/dL.

Results

The overall prevalence of anaemia among lactating mothers was 22.1% (95% CI 21.13% to 23.03%). The highest prevalence was 48.7% (95% CI 40.80% to 56.62%) found in the Somali region, followed by 43.8% (95% CI 31.83% to 56.87%) in the Afar region. The multivariate statistical model showed that having a husband who had attended primary education (adjusted OR (AOR) 0.79; 95% CI 0.68 to 0.91), working during the 12 months preceding the survey (AOR 0.71; 95% CI 0.63 to 0.80), having a normal maternal body mass index (18.5–24.99 kg/m2) (AOR 0.78; 95% CI 0.68 to 0.89), being in the middle wealth quintile (AOR 0.83; 95% CI 0.71 to 0.98) or rich wealth quintile (AOR 0.83; 95% CI 0.70 to 0.98), having ever used family planning (AOR 0.68; 95% CI 0.57 to 0.80), having attended antenatal care (ANC) for the indexed pregnancy four times or more (AOR 0.73; 95% CI 0.59 to 0.91), having experienced time variation between the two surveys (AOR 0.73; 95% CI 0.64 to 0.85), and breastfeeding for 2 years (AOR 0.76; 95% CI 0.66 to 0.87) were factors associated with lower odds of having anaemia in lactating mothers.

Conclusions

Anaemia is highly prevalent among lactating mothers, particularly in the pastoralist communities of Somali and Afar. Promoting partner education, improving maternal nutritional status, and creating behavioural change to use family planning and ANC services at health facilities are recommended interventions to reduce the prevalence of anaemia among lactating mothers in Ethiopia.
UK research spend in 2008 and 2012: comparing stroke, cancer, coronary heart disease and dementia
Authors: Luengo-Fernandez Ramon , Leal Jose , Gray Alastair
Published: April 2015

Objective

To assess UK governmental and charity research funding in 2012 for cancer, coronary heart disease (CHD), dementia and stroke, and to make comparisons with 2008 levels.

Design

Analysis of research expenditure.

Setting

United Kingdom.

Main outcome measures

We identified UK governmental agencies and charities providing health research funding to determine the 2012 levels of funding for cancer, CHD, dementia and stroke. Levels of research funding were compared to burden of disease measures, including prevalence, disability adjusted life years and economic burden.

Results

The combined research funding into cancer, CHD, dementia and stroke by governmental and charity organisations in 2012 was £856 million, of which £544 million (64%) was devoted to cancer, £166 million (19%) to CHD, £90 million (11%) to dementia and £56 million (7%) to stroke. For every £10 of health and social care costs attributable to each disease, cancer received £1.08 in research funding, CHD £0.65, stroke £0.19 and dementia £0.08. A considerable shift in the distribution of government research funding was observed between 2008 and 2012. In 2008, 66% of governmental research funding into the four conditions under study was devoted to cancer, 21% to CHD, 9% to dementia and 4% to stroke. In 2012, the proportions devoted to dementia and stroke had increased to 21% and 12%, respectively, with cancer accounting for 45% of total research spend.

Conclusions

Although there has been much progress by government to increase levels of research funding for dementia and stroke, these areas remain underfunded when compared with the burden of disease.