bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effect of Operating Conditions on the Aerodynamic Performance of an Integrated OGV and S-Shaped Duct
Authors: Britchford K. M. , Carrotte J. F. , Kim J. H. , Hield P. M.
Published: July 2014

This paper is concerned with the design and performance of an annular S-shaped duct that would be used to connect an LP fan to the core within a gas turbine engine. The desire to minimise engine length means the duct is of relatively short length so that, without novel design, flow separation is likely to occur. Hence the upstream OGV row has been leant tangentially so that it assists in turning the flow within the first bend of the S-shaped duct. In such an ‘integrated’ design, a component of the lift force generated by the OGV row turns the flow radially inward. In this way, the aerodynamic loading on the critical inner wall boundary layer, within the downstream S-shaped duct, is reduced. In addition, by incorporating the blade row within the duct, rather than upstream of it, a further length reduction can also be achieved. The paper outlines the OGV design methodology and presents experimental results that define the aerodynamic performance of the integrated system. The overall system loss is determined mainly by the OGV row, and the subsequent mixing out of the blade wakes prior to the inlet of the core duct. In addition, for the range of conditions tested, the stagnation pressure profile at core duct exit reflects that portion of the OGV exit profile that is captured by the core duct.
A Parallel Flow Solver for Unsteady Multiple Blade Row Turbomachinery Simulations
Authors: Chen J. P. , Briley W. R.
Published: July 2014

A parallel flow solver has been developed to provide a turbomachinery flow simulation tool that extends the capabilities of a previous single–processor production code (TURBO) for unsteady turbomachinery flow analysis. The code solves the unsteady Reynolds-averaged Navier-Stokes equations with a k–ε turbulence model. The parallel code now includes most features of the serial production code, but is implemented in a portable, scalable form for distributed–memory parallel computers using MPI message passing. The parallel implementation employs domain decomposition and supports general multiblock grids with arbitrary grid–block connectivity. The solution algorithm is an iterative implicit time–accurate scheme with characteristics–based finite–volume spatial discretization. The Newton subiterations are solved using a concurrent block–Jacobi symmetric Gauss–Seidel (BJ–SGS) relaxation scheme. Unsteady blade–row interaction is treated either by simulating full or periodic sectors of blade–rows, or by solving within a single passage for each row using phase–lag and wake–blade interaction approximations at boundaries. A scalable dynamic sliding–interface algorithm is developed here, with an efficient parallel data communication between blade rows in relative motion. Parallel computations are given here for flat plate, single blade row (Rotor 67) and single stage (Stage 37) test cases, and these results are validated by comparison with corresponding results from the previously validated serial production code. Good speedup performance is demonstrated for the single–stage case with a relatively small grid of 600,000 points.
Numerical Investigation of Transonic Compressor Rotor Flow Using an Implicit 3D Flow Solver With One-Equation Spalart-Allmaras Turbulence Model
Authors: Ning Fangfei , Xu L.
Published: July 2014

A CFD code for three-dimensional viscous flows, in particular for those in turbomachinery, has been developed based on Favre-averaged compressible Navier-Stokes equations and one-equation Spalart-Allmaras turbulence closure. The model equation of Spalart-Allmaras turbulence closure is converted into conservative form and discretized in the same manner as that for mean flow equations. A two-dimensional transonic diffuser flow and a two-dimensional transonic nozzle flow which feature pressure-gradient induced separation and shock wave/boundary layer interaction respectively are used to validate the code and application of the Spalart-Allmaras model (hereafter the S-A model) in internal flows. It is shown that the S-A model can give fairly good results compared to the experimental data. Some modifications of model equation are introduced for improving the grid insensitivity of the turbulence model. To validate the applicability of the code to the complex flows in transonic turbomachines, flows through two transonic compressor rotors, NASA Rotors 67 and 37 are calculated, and numerical results are compared with the well documented experimental data. The calculated results agree reasonably well with the experiments, and as expected, the S-A model, which is primarily developed for external flows, can also be effectively applied to internal flows. Discrepancies between the experimental data and calculations and the possible causes are also discussed.
Design and Off-Design Predictions of a Combined SOFC and Gas Turbine System
Authors: Palsson Jens , Selimovic Azra
Published: July 2014

In the present study design and off-design performance of a combined SOFC/GT system is investigated. For the evaluation a process simulation tool, Aspen Plus®, was used, completed with a user model representing a SOFC component of planar design. The fuel cell model is a detailed mathematical and physical description thereby avoiding performance curves. A recuperated SOFC/GT system, in size of around 500 kW, with natural gas as fuel, was analysed. Design calculations and sensitivity studies resulted in high electric efficiencies at low pressure ratios. Recent work has focused on off-design calculations investigating different ambient conditions and part load behaviour of this system. Thanks to the small size of the gas turbine, the operational mode is assumed flexible, allowing variation of both rotor speed and of turbine inlet temperature (TIT). In the calculations a simplified compressor map and a choked expander were considered. A high part load efficiency of the system was found exceeding the design point efficiency by as much as three percentage points.
Compressor Characteristics in Gas Turbine Performance Modelling
Authors: Jones Geoff , Pilidis Pericles , Curnock Barry
Published: July 2014

The choice of how to represent the performance of the fans and compressors of a gas turbine engine in a whole-engine performance model can be critical to the number of iterations required by the solver or indeed whether the system can be solved.

This paper therefore investigates a number of compressor modelling methods and compares their relative merits. Particular attention is given to investigating the ability of the various representations to model the performance far from design point. It is noted that, for low rotational speeds and flows, matching on pressure ratio will produce problems, and that efficiency is a discontinuous function at these conditions. Thus, such traditional representations of compressors are not suitable for investigations of starting or windmilling performance.

Matching on pressure ratio, Beta, the Crainic exit flow function and the true exit flow function is investigated. The independent parameters of isentropic efficiency, pressure loss, a modified pressure loss parameter, specific torque, and ideal and actual enthalpy rises are compared.

The requirements of the characteristic choice are investigated, with regard to choosing matching variables and ensuring that relationships are smooth and continuous throughout the operating range of the engine.
Convective Blade Cooling Modelling for the Analysis of Innovative Gas Turbine Cycles
Authors: Jordal Kristin , Torbidoni Leonardo , Massardo Aristide F.
Published: July 2014

With the objective to perform reliable gas-turbine cycle calculations, a new, simultaneous use of two different thermodynamic blade cooling evaluation codes is presented. The proposed approach can be used to evaluate: (i) the blade coolant mass flow rate; (ii) the blade internal geometry data, necessary for the evaluation of (iii) the pressure drop of the coolant that flows through the blade; (iv) the main flow (hot gas side) Stanton number (employed to get concordance between input data for the two models), and (v) the temperature of the coolant as it leaves the blade at the outlet section Tco. The results for the cooled blade can easily be employed on a system level.

The base of the study is available data for air-cooled conventional gas turbine blades. Thereafter, for a given blade geometry, it is possible to investigate the influence of changing fluid properties for both coolant and hot gas, which is useful for studies of innovative gas turbine cycles.
Testing the World’s Largest Gas Turbines
Authors: DuBose Ronald A. , Callahan Thomas P. , Bugg Carl R.
Published: July 2014

Emprise Corporation designed and managed construction for a new state-of-the-art facility (Test Stand 8) and for a radical upgrade and renovation of a circa 1972 test facility (Test Stand 3). General Electric will use Test Stand 8 for prototype 9H (50 Hz) gas turbine testing, and will use Test Stand 3 for 7F (60 Hz) gas turbine testing. This paper summarizes the unique challenges and innovative solutions that were required for these projects.
Options to Maximize Power Output for Merchant Plants in Combined Cycle Applications
Authors: Tawney Rattan , Pearson Cheryl , Brown Mona
Published: July 2014

Deregulation and growth in the power industry are causing dramatic changes in power production and distribution. The demand for peak power and potentially high revenues due to premium electricity rates has attracted independent developers to the concept of Merchant Power Plants (MPPs).

Over 100,000 MW of greenfield capacity is currently being developed through approximately 200 merchant plants in North America. These MPPs will have no captive customers or long-term power purchase agreements, but will rely on selling electricity into a volatile electricity spot market. Because of this, MPPs need the capability to export as much power as possible on demand. MPPs must also have the capability to produce significant assets in order to compete in the marketplace, based on both technical and commercial operation factors such as value engineering, life-cycle cost management, and information technology. It is no surprise then, that almost all merchant project developers have specified combined cycle (CC) technology. The CC power plant offers the highest thermal efficiency of all electric generating systems commercially available today. It also exhibits low capital costs, low emissions, fuel and operating flexibility, low operation and maintenance costs, short installation schedule, and high reliability/availability.

However, since gas turbines (GTs) are the basis for CC power plants, these plants experience power output reductions in the range of 10 to 15 percent during summer months, the period most associated with peak power demand. In order to regain this loss of output as well as to provide additional power to meet peak demands, the most common options are GT inlet fogging, GT steam injection, and heat recovery steam generator (HRSG) supplemental firing. This paper focuses on plant design, cycle performance, and the economics of plant configuration associated with these options. Guidelines are presented in this paper to assist the owner in selecting power enhancement options for the MPP that will maximize their Return on Equity (ROE).
Experimental Investigation of an Inert Gas Generator for Fire Suppressing
Authors: Kim SooYong , Slitenko A.
Published: July 2014

Present study deals with experimental and theoretical performance analysis of an inert gas generator(IGG) which can be used as an effective mean to suppress the fire. The system consists of a gas turbine engine and afterburning system with injection of water, exit nozzle to produce the inert gas. It is generally known that the degree of oxygen content in the product of combustion depends on both inlet and outlet temperature of a combustor. Less the oxygen content in the combustion product higher will be the effectiveness of fire suppression. Injection of water brings additional advantages of suffocating and cooling effects which are both indespensable factors for fire suppressing. The special test rig was manufactured and experimental investigation of IGG system has been carried out. The automatic control system ensured stable operation of gas turbine engine and afterburner, water injection, fuel control and others. During the investigation the main parameters of gas turbine engine and auxiliarly systems were measured: gas temperature and pressure at gas turbine and afterburner exit, fuel flow rate, water mass flow rate, inlet air temperature, water temperature in the cooling chamber, mass flow rate, temperature and velocity of exhaust gas-steam mixture in the exit nozzle, oxygen content in the exit jet. The experimental investigation shows that developed IGG system can work very well for indoor fires but need some modifications in application to outdoor fire suppressing.
Qualification of a Frequency Scanning Eddy Current Equipment for Nondestructive Characterization of New and Serviced High-Temperature Coatings
Authors: Antonelli Giampiero , Crisafulli Paola , Tirone Giacomo
Published: July 2014

As modern gas turbines are continuously being upgraded, mainly through the increase of their firing temperature and cooling optimization, the prime protection of the high technology and high-cost hot gas path parts is increasingly being transferred to the coatings. In order to avoid the risk of structural damage of these components, with its potential for greater economic losses — mostly traceable to unexpected prime time outages — refurbishment cycle should be dictated by the amount of the life actually expended by the coating.

To address the issues of quality and condition assessment of new and serviced high-temperature coatings applied on buckets and vanes, an innovative non-destructive system was developed based on a frequency scanning eddy current technique. It combines outstanding high frequency hardware with model based analysis of raw data.

In the paper, quantitative data on equipment qualification are presented, relating to its capability in measuring both the thickness and β-aluminide depletion of MCrAlY coatings applied on Ni-base superalloys. The results of an inspection campaign on serviced blades, performed during major overhauls of ENEL gas turbines, will also be reported, together with recent system upgrades, aiming at extending its applicability to newer coatings such as thermal barriers and over-aluminized MCrAlY’s.
Pressure Surface Separations in Low Pressure Turbines: Part 1 of 2 — Midspan Behaviour
Authors: Brear Michael J. , Hodson Howard P. , Harvey Neil W.
Published: July 2014

This paper describes an investigation into the behaviour of the pressure surface separation at midspan in a linear cascade. It is found that the pressure surface separation can be a significant contributor to the profile loss of a thin, solid, low pressure turbine blade that is typical of current engine designs.

Numerical predictions are first used to study the inviscid behaviour of the blade. These show a strong incidence dependence around the leading edge of the profile. Experiments then show clearly that all characteristics of the pressure surface separation are controlled primarily by the incidence. It is also shown that the effects of wake passing, freestream turbulence and Reynolds number are of secondary importance.

A simple two-part model of the pressure surface flow is then proposed. This model suggests that the pressure surface separation is highly dissipative through the action of its strong turbulent shear. As the incidence is reduced, the increasing blockage of the pressure surface separation then raises the velocity in the separated shear layer to levels at which the separation can create significant loss.
A Turbine Airfoil Aerodynamic Design Process
Authors: Xu C. , Amano R. S.
Published: July 2014

A turbine airfoil aerodynamic design process, similar to the current industry practice, is used to design turbine airfoil sections. The airfoil generator code employs Bezier polynomial curves to produce smooth airfoil shapes.

For the calculations of the airfoil pressure distributions a discrete vortex method is used after the airfoil is designed and the novel Navier-Stokes (N-S) solver is developed for further examination of the airfoil performance. The vortex method can provide a fast way to calculate the airfoil pressure distributions. The N-S code is used to obtain the blade-to-blade quasi-three-dimensional, turbulent, and viscous flow characteristics. The time-dependent N-S equations are discretized and integrated in a coupled manner based on a finite-volume formulation as well as a flux-difference splitting. The flux-difference splitting method enables us to compute with a rapid convergence.

After the flow solver is validated with experimental data, this new code is further used to obtain an optimal airfoil design by analyzing the cascade flows. The present N-S code can handle computations of both subsonic and supersonic flows and can be connected to an external optimizer code with the airfoil generator.
Integrated Vehicle Comparison of Turbo-Ramjet Engine and Pulsed Detonation Engine (PDE)
Authors: Kaemming Tom
Published: July 2014

The Pulsed Detonation Engine, PDE, is a unique propulsion system that uses the pressure rise associated with detonations to efficiently provide thrust. A study was conducted under the direction of the NASA Langley Research Center to identify the flight applications that provide the greatest potential benefits when incorporating a PDE propulsion system. The study was conducted in three phases. The first two phases progressively screened a large matrix of possible applications down to three applications for a more in-depth, advanced design analysis. The three applications best suited to the PDE were: 1) a supersonic tactical aircraft, 2) a supersonic strike missile and 3) a hypersonic single-stage-to-orbit, SSTO, vehicle. The supersonic tactical aircraft is the focus of this paper.

The supersonic, tactical aircraft is envisioned as a Mach 3.5 high altitude reconnaissance aircraft with possible strike capability. The high speed was selected based on the perceived high speed fuel efficiency benefits of the PDE. Relative to a turbo-ramjet powered vehicle, the study identified an 11% to 21% takeoff gross weight, TOGW, benefit to the PDE on the baseline 700 n.mi. radius mission depending on the assumptions used for PDE performance and mission requirements. The TOGW benefits predicted were a result of the PDE lower cruise specific fuel consumption, SFC, and lower vehicle supersonic drag. The lower vehicle drag resulted from better aft vehicle shaping, which was a result of better distribution of the PDE cross-sectional area.

The reduction in TOGW and fuel usage produced an estimated 4% reduction in life cycle cost for the PDE vehicle. The study also showed that the simplicity of the PDE enables concurrent engineering development of the vehicle and engine.
Development of a Temporally Modulated Fuel Injector With Controlled Spray Dynamics
Authors: Chang Hyeonsoo , Sipperley Chad , Nelson David , Edwards Chris
Published: July 2014

It is now well established that combustion instability in liquid-fueled gas turbines can be controlled through the use of active fuel modulation. What is less clear is the mechanism by which this is achieved. This results from the fact that in most fuel modulation strategies not only is the instantaneous mass flow rate of fuel affected but so to are the parameters which define the post-atomization spray that takes part in the combustion. Specifically, experience with piezoelectric modulated sprays has shown that drop size, velocity, cone angle, and patternation are all affected by the modulation process. This inability to decouple changes in the fueling rate from changes in the spray distribution makes understanding of the mechanism of instability control problematic.

This paper presents the results of an effort to develop an injector which can provide temporal modulation of the fuel flow rate but without concomitant changes in spray dynamics. This is achieved using an atomization strategy which is insensitive to both fuel flow rate and combustor acoustics (an over-pressured spill-return nozzle) coupled with an actuator with flat frequency response (a low-mass voice coil). The design and development of the actuator (and its control system) are described, and a combination of Phase-Doppler Interferometry and imaging are used to establish its performance. Results show that the system is capable of producing sprays which have little variation in cone angle or spray distribution function despite variations in mass flow rate (number density) of greater than 50% over a range of frequencies of interest for control of combustion instability (10 Hz to 1 kHz).
Passive Fault Tolerance for a Magnetic Bearing Under PID Control
Authors: Choi Benjamin , Provenza Andrew
Published: July 2014

NASA Glenn Research Center (GRC) has developed a Fault-Tolerant Magnetic Bearing Suspension rig to enhance the safety of the bearing system for multiple component failures. A simple proportional-integral-derivative (PID) controller with no fault detection mechanisms was tested in a passive way where the initial bias current and control gains for all the eight heteropolar poles were not changed for the remaining active poles in the fault situations. The action of the integral term in the controller generated autonomous corrective actions for the pole failures to return the rotor to the set point (middle position) after the failure transient. The system stability and control of the rotor position were maintained over the entire speed range, where the rotor passes through the rigid body critical speeds and other rotor disturbances, provided that there was sufficient position stiffness and damping at low speeds. As far as the summation of force vectors of two attracting forces and rotor weight is zero, the passive fault tolerance was successfully demonstrated by using as few as two active poles out of the eight independent poles from each radial bearing (that is simply, 12 out of 16 poles dead). The rotor was spun without losing stability or desired position up to the rig’s maximum allowable speed of 20,000 rpm.
Ceramic Stationary Gas Turbine Program: Monolithic Ceramic Component Development Summary
Authors: van Roode Mark , Price Jeffrey R. , Richerson David W. , Parthasarathy Vijay , Graves George A.
Published: July 2014

In the Ceramic Stationary Gas Turbine (CSGT) development program, sponsored by the U.S. Department of Energy (DOE) Offices of Industrial Technologies and Power Technologies (OIT/OPT), monolithic silicon nitride and silicon carbide ceramics were evaluated for application as structural materials for hot section components in an industrial gas turbine, the Solar Centaur 50S. First generation blades of GN10, NT164, and SN253 silicon nitrides, second generation blades of AS800 and SN281 silicon nitrides, and first generation SN-88 silicon nitride nozzles were evaluated in rigs and test engines. Hexoloy SA silicon carbide combustor liner tiles were tested in a subscale rig. The selection and evaluation of monolithic materials over the duration of the CSGT program (1992 to 2000) will be reviewed.
Accelerated Testing Methodologogy in Constant Stress-Rate Testing for Advanced Structural Ceramics: A Preloading Technique
Authors: Choi Sung R. , Gyekenyesi John P. , Huebert Dean , Bartlett Allen , Choi Han-Ho
Published: July 2014

Preloading technique was used as a means of an accelerated testing methodology in constant stress-rate (“dynamic fatigue”) testing for two different brittle materials. The theory developed previously for fatigue strength as a function of preload was further verified through extensive constant stress-rate testing for glass-ceramic and CRT glass in room-temperature distilled water. The preloading technique was also used in this study to identify the prevailing failure mechanisms at elevated temperatures, particularly at lower test rates in which a series of mechanisms would be associated simultaneously with material failure, resulting in significant strength increase or decrease. Two different advanced ceramics including SiC whisker-reinforced composite silicon nitride and 96 wt% alumina were used at elevated temperatures. It was found that the preloading technique can be used as an additional tool to pinpoint the dominant failure mechanism that is associated with such a phenomenon of considerable strength increase or decrease.
Technical Risks and Mitigation Measures in Combustion Turbine Project Development
Authors: Grace Dale , Scheibel John
Published: July 2014

Project developers, insurers, financiers and maintenance organizations have an interest in quantifying technical risks and evaluating risk mitigation alternatives for combustion turbine (CT) power plants. By identifying exposure to risk early in the project development process, optimal procurement decisions and mitigation measures can be adopted for improved financial returns. This paper describes a methodology used to quantify all non-fuel O&M costs, including scheduled and unplanned maintenance, and business interruption costs due to unplanned outages. The paper offers examples that demonstrate the impact of technical risk on project profitability. An overview of activities required for addressing technical risk as part of the equipment selection and procurement process is provided, and areas of technical improvements for reducing life cycle costs are described.
A Comparison of Some Heat Transfer Surfaces for Small Gas Turbine Recuperators
Authors: Utriainen Esa , Sundén Bengt
Published: July 2014

For small gas turbines a recuperator is mandatory to achieve high thermal efficiencies, 30 percent and higher. As the recuperator represents 25–30 percent of the overall machine cost, efforts are now being focused on establishing new low cost recuperator concepts for gas turbine engines. In this paper a comparison of four different heat transfer surfaces is performed for a recuperator for a representative 50 kW micro turbine. Two standard methods of comparison, the so-called volume goodness factor and the flow area goodness factor, were used to choose several promising heat transfer surfaces for design calculations of a recuperator heat transfer matrix. Thus a direct comparison of recuperator matrix dimensions, volume and weight is possible for the selected surfaces. The hydraulic diameter is equal for all surfaces thus only their thermohydraulic performances are compared. In this paper details of the heat transfer surface geometries as well as the resulting recuperator matrix dimensions, volumes and weights are presented.
The Model Steam Turbine: A Method of Evaluating a Heat Recovery Steam Generator in a Combined Cycle Plant
Authors: Schmidt Dietmar , Sullivan Terrence
Published: July 2014

Turnkey and thermal island supply scopes present turbine manufacturers with a perfect way to sell their rotating products. The popularity of these plant configurations, along with the recent availability of more holistic test codes, has led to the need for an accurate and reasonable method of determining the thermal performance of the externally-purchased HRSG component.

To assess a multiple pressure HRSG, it is advantageous and convenient to have one single criterion for the evaluation of performance, especially when this criterion provides for the compensation of the different outlet energy streams. The so-called Model Steam Turbine method of HRSG evaluation was developed for these reasons. The result of the calculation, a lone performance criterion, is the shaft power of the fictitious Model Steam Turbine.

In this paper we will detail the components of the Model Steam Turbine calculation and explore the merits of this method. Some thoughts on performance corrections are also presented.
The Development of Ceramic-Based Thermocouples for Application in Gas Turbines
Authors: Farrell D. M. , Parmar J. , Robbins B. J.
Published: July 2014

A research and development project has recently been carried out to develop ceramic thermocouple probes (CTPs) capable of measuring temperatures up to 2000°C and rugged enough to withstand extended service in high-temperature gas turbine environments. Existing metallic thermocouple technology cannot withstand such conditions for sustainable periods of time. Following initial laboratory studies, CTP trials were carried out in power generation boilers (Farrell and Higginbottom, 1995). Prototype CTPs were subsequently developed for evaluation in gas turbine (GT) combustors (at atmospheric and elevated pressures) and in a Spey engine (Patent, 1996). The CTPs performed well under the harsh conditions imposed, demonstrating their mechanical integrity and consistency/sustainability of signal output. Initial studies have also been carried out with a view to applying ‘thin-layer’ ceramic thermocouples directly onto thermal barrier coatings to give surface temperatures on stator or other hot gas surfaces, and are briefly mentioned. Rowan Technologies and TÜV Energy Services are currently looking for companies interested in exploiting this new ceramic thermocouple technology.
Demonstration of Active Control of Combustion Instabilities on a Full-Scale Gas Turbine Combustor
Authors: Johnson C. E. , Neumeier Y. , Neumaier M. , Zinn B. T. , Darling D. D. , Sattinger S. S.
Published: July 2014

This paper presents the results of an investigation of active control of combustion instabilities in a natural gas, high-pressure, full-scale gas turbine combustor that was retrofitted with an Active Control System (ACS). The combustor test rig simulates the geometry, inlet airflow distribution, and pressurization of a can-type combustor that exhibits dynamic flame instabilities at some off-design operating conditions. Two essential features of the investigated ACS are 1) a real-time mode observer that identified the frequencies, amplitudes and phases of the dominant modes in the pressure signal and 2) a fast response servo valve that can modulate a large portion of the gaseous fuel. Two active control configurations were studied. In the first configuration, the actuator was mounted on one of two premixed fuel stages, and in the second configuration it was mounted on the inlet to the stabilizing diffusion stage. In both configurations, the ACS damped combustion instabilities, attenuating the dominant mode by up to 15dB and reducing the overall broadband noise by 30-40%. NOx emissions were also reduced by approximately 10% when control was applied. Finally, this study demonstrated the importance of having a fast multiple-mode observer when dealing with complex combustion processes with inherently large time delays.
A High-Efficiency SOFC Hybrid Power System Using the Mercury 50 ATS Gas Turbine
Authors: Lundberg Wayne L. , Veyo Stephen E. , Moeckel Mark D.
Published: July 2014

The conceptual design of a 20 MWe-class hybrid power generating system that integrates a Siemens Westinghouse pressurized solid oxide fuel cell generator with a Mercury 50 gas turbine is discussed. The Mercury 50 was designed and developed by Caterpillar/Solar Turbines during the U.S. Department of Energy (DOE) Advanced Turbine Systems (ATS) program, and the hybrid system design concept was evaluated during a recently completed project that was part of the DOE High Efficiency Fossil Power Plant (HEFPP) program. While achieving a high power system efficiency by the hybrid cycle approach was important, the focus of the design study was to select the SOFC generator capacity such that the low specific cost of the ATS gas turbine and the high efficiency of the more expensive PSOFC generator would combine optimally to produce an attractively-low cost of electricity (COE) for the overall power system. The system cycle and physical characteristics are described; power, efficiency, and emissions estimates are presented; and estimates of system cost and COE are provided. In addition, two bottoming cycle options (steam turbine and ammonia turbine) are described, and performance and cost projections for each are reviewed.
Contact Stresses in Dovetail Attachments: Alleviation via Precision Crowning
Authors: Sinclair G. B. , Cormier N. G.
Published: July 2014

Previous studies of contact stresses in dovetail attachments provide verified finite element stresses as well as some simple physical models of such stresses. Generally there is good agreement between the finite element analysis and the simple physical models. Together the two identify a pinching mechanism as leading to large fluctuations in hoop stresses at the edges of contact. These fluctuating hoop stresses can be expected to be a major contributor to the fatigue of dovetail attachments.

The present study investigates a method of alleviating the fluctuating hoop stresses. This method entails crowning of the contacting flat on a blade. Such crowning is in two orthogonal directions on the blade flat. Two-dimensional finite element analyses are made in both directions. These analyses indicate that significant reductions in fluctuating hoop stresses can be achieved by the method, provided the crowning is controlled sufficiently precisely.
Semi-Closed Gas Turbine Cycles: An Ecological Solution
Authors: Laganelli A. L. , Rodgers C. , Lear W. E. , Meitner P. L.
Published: July 2014

The impact on global warming of transportation and the infrastructure that supports it has been investigated over several decades. Anthropogenic heat and the generation of greenhouse gases from burning of fossil fuels and are major contributors to the warming process. An approach to mitigate these effects is discussed that considers semi-closed cycle gas turbine engines as a practical approach to slowing the release of greenhouse gases. Semi-closed cycle gas turbine engines have an inherent capability to reduce all regulated emissions while maintaining high efficiency, which in turn reduces CO2 emissions.

With emerging technology development that includes higher component efficiencies, high temperature material development, improved control devices, and advanced combustor designs, aided by computational fluid dynamics, semi-closed cycle engines appear to have the potential to mitigate global warming with little economic or infrastructural impact. A specific semi-closed engine type is described, the high pressure recuperated turbine engine (HPRTE), along with the inherent mechanisms for control of NOx, CO, unburned hydrocarbons, and particulates. Results from a breadboard demonstration of the HPRTE are discussed, as well as emerging technologies which benefit this type of engine.
Study on the High Efficiency Closed Cycle Gas Turbine System
Authors: Koda Eiichi , Takahashi Toru , Uematsu Kazuo , Sugishita Hideaki , Yamashita Katsuya , Koga Akinori
Published: July 2014

In WE-NET project Phase I Program, the power generation system with more than 60%(HHV) thermal efficiency had been designed. However, because this system must be fueled by pure hydrogen, commercialization of this system in early stage is thought to be difficult. Therefore, the new project, in which the natural gas fueled system is targeted, has been started since FY1999. In this project, the power generation efficiency is aimed to be 60%(HHV) or higher, with turbine inlet maximum temperature of 1973K. In this report, the feature of the target system is explained at first. Then, the sensitivities of many parameters are examined in detail.
Development of the Advanced Closed-Cycle Gas Turbine System
Authors: Koyama Miki , Mimaki Toshio
Published: July 2014

This aims to put the fruits of the R&D; “The Hydrogen Combustion Turbine” in WE-NET Phase I Program(1993-1998) to practical use at an early stage. The topping regenerating cycle was selected as the optimum cycle, with energy efficiency expected to be more than 60%(HHV) under the conditions of the turbine inlet temperature of 1973K(1700°C) and the pressure of 4.8MPa,in it.

• As the turbine inlet temperature and pressure increase, issues to be resolved include the amount of NOx emissions and the durability of super alloys for turbine blades under such thermal conditions. In this respect, the development of the highly efficient methane-oxygen combustion technology, the turbine blade cooling technology, and the ultrahigh-temperature materials including thermal barrier coatings is being carried out.

• In 1999, the results made it clear that there are little error among the three analytic programs used to verify the system efficiency, it was verified that the burning rate was going to arrive at over 98% from the methane-oxygen combustion test (under the atmospheric pressure). And the type of vane “Film cooling plus recycle type with internal cooling system” was selected as the most suitable vane.
LSR™ Slurry Coating Technologies
Authors: Liburdi J. , Moravek V. , Lowden P.
Published: July 2014

A novel slurry process has been developed for producing plain, silicon and platinum modified aluminides. The LSR™ coatings exhibit microstructures, chemistries and oxidation behaviour that are similar to the conventionally specified coatings and can be easily qualified to replace the older pack or spray technologies. The simple, compact LSR™ process makes it possible to incorporate the coating operation in new part manufacturing or repair cells and to reduce the overall cycle time or delivery.
Effect of the Axial Spacing Between Rotor and Stator With Regard to the Indexing in an Axial Compressor
Authors: Layachi M. Y. , Bölcs A.
Published: July 2014

An experimental investigation was carried out to examine the influence of the axial spacing between rotor and stator. The test facility of the Swiss Federal Institute of Technology is made up of an inlet guide vane (IGV), a rotor and a stator.

Temperature and aerodynamic measurements determined the characteristics of the compressor stage. Data were acquired over a range of flow coefficients for four different axial spacings. A refined measurement mesh was used for Pitot probe measurements in different sections of the compressor.

As the compressor has a rather low aspect ratio of 1.21, the flow was governed by strong secondary flows. The interaction between the different secondary flows, especially the Influence of the IGV wake on the secondary flows in the stator, were detected by the detailed Pitot probe measurements. Shifting the stator axially changes the circumferential position of the IGV wake entering the stator. From this statement, the link between an axial variation of the distance between rotor and stator and the clocking between IGV and stator will be shown. Further Pitot measurement with different indexings between IGV and stator were performed. The Pitot measurements for the different axial spacings as for the different indexings brought to light strong interactions in the wall regions especially between the IGV wake and the clearances at the rotor tip and at the stator hub. The structure of the flow thus changes with the indexing and with the axial spacing.
ASC-1, PAT2, and P2RX5 are cell surface markers for white, beige, and brown adipocytes
Authors: Ussar Siegfried , Lee Kevin Y. , Dankel Simon N. , Boucher Jeremie , Haering Max-Felix , Kleinridders Andre , Thomou Thomas , Xue Ruidan , Macotela Yazmin , Cypess Aaron M. , Tseng Yu-Hua , Mellgren Gunnar , Kahn C. Ronald
Published: July 2014

The cell surface markers ASC-1, PAT2, and P2RX5 can be used to mark and identify brown, beige, and white adipocytes in both rodents and humans.
New antigens for a multicomponent blood-stage malaria vaccine
Authors: Osier Faith H. , Mackinnon Margaret J. , Crosnier Cécile , Fegan Gregory , Kamuyu Gathoni , Wanaguru Madushi , Ogada Edna , McDade Brian , Rayner Julian C. , Wright Gavin J. , Marsh Kevin
Published: July 2014

Uncharacterized proteins from the merozoite stage of
Plasmodium falciparum
provide new antigens for malaria blood-stage vaccine development.
Hematogenous dissemination of glioblastoma multiforme
Authors: Müller Carolin , Holtschmidt Johannes , Auer Martina , Heitzer Ellen , Lamszus Katrin , Schulte Alexander , Matschke Jakob , Langer-Freitag Sabine , Gasch Christin , Stoupiec Malgorzata , Mauermann Oliver , Peine Sven , Glatzel Markus , Speicher Michael R. , Geigl Jochen B. , Westphal Manfred , Pantel Klaus , Riethdorf Sabine
Published: July 2014

Hematogenous spread of glioblastoma multiforme (GBM) might be responsible for reported extracranial metastases and transmission of GBM by organ transplantation.
Highly Recombinant VGII Cryptococcus gattii Population Develops Clonal Outbreak Clusters through both Sexual Macroevolution and Asexual Microevolution
Authors: Billmyre R. Blake , Croll Daniel , Li Wenjun , Mieczkowski Piotr , Carter Dee A. , Cuomo Christina A. , Kronstad James W. , Heitman Joseph
Published: July 2014

An outbreak of the fungal pathogen
Cryptococcus gattii
began in the Pacific Northwest (PNW) in the late 1990s. This outbreak consists of three clonal subpopulations: VGIIa/major, VGIIb/minor, and VGIIc/novel. Both VGIIa and VGIIc are unique to the PNW and exhibit increased virulence. In this study, we sequenced the genomes of isolates from these three groups, as well as global isolates, and analyzed a total of 53 isolates. We found that VGIIa/b/c populations show evidence of clonal expansion in the PNW. Whole-genome sequencing provided evidence that VGIIb originated in Australia, while VGIIa may have originated in South America, and these were likely independently introduced. Additionally, the VGIIa outbreak lineage may have arisen from a less virulent clade that contained a mutation in the
MSH2
ortholog, but this appears to have reverted in the VGIIa outbreak strains, suggesting that a transient mutator phenotype may have contributed to adaptation and evolution of virulence in the PNW outbreak. PNW outbreak isolates share genomic islands, both between the clonal lineages and with global isolates, indicative of sexual recombination. This suggests that VGII
C. gattii
has undergone sexual reproduction, either bisexual or unisexual, in multiple locales contributing to the production of novel, virulent subtypes. We also found that the genomes of two basal VGII isolates from HIV
+
patients contain an introgression tract spanning three genes. Introgression substantially contributed to intra-VGII polymorphism and likely occurred through sexual reproduction with VGI. More broadly, these findings illustrate how both microevolution and sexual reproduction play central roles in the development of infectious outbreaks from avirulent or less virulent progenitors.

IMPORTANCE
Cryptococcus gattii
is the causative agent responsible for ongoing infections in the Pacific Northwest of the United States and western Canada. The incidence of these infections increased dramatically in the 1990s and remains elevated. These infections are attributable to three clonal lineages of
C. gattii
, VGIIa, VGIIb, and VGIIc, with only VGIIa identified once previously in the Pacific Northwest prior to the start of the outbreak, albeit in a less virulent form. This study addresses the origin and emergence of this outbreak, using whole-genome sequencing and comparison of both outbreak and global isolates. We show that VGIIa arose mitotically from a less virulent clonal group, possibly via the action of a mutator phenotype, while VGIIb was likely introduced from Australia, and VGIIc appears to have emerged in the United States or in an undersampled locale via sexual reproduction. This work shows that multiple processes can contribute to the emergence of an outbreak.
Alternatives for restoration of a hemisected mandibular molar
Authors: Naveen Y G , Patel Jayanti R , Parikh Pooja , Shah Khyati
Published: July 2014

Hemisection is a common conservative treatment option for periodontally or endodontically compromised teeth. It is most likely to be performed on mandibular molars with class II or III furcation involvement. Their restoration is more critical than implant surgery to ensure the ability to masticate along with the ability to maintain good oral hygiene. There are various alternatives to restore such types of teeth: the remaining root restored as an individual tooth, restoring individual roots with either a molar or premolar morphology using the adjacent tooth as an abutment in a full coverage fixed partial denture, restoring individual roots with either molar or premolar morphology using an inlay type of restoration on the adjacent abutment tooth. This article reports two cases, one treated with molar morphology and an inlay type of restoration and the other with a premolar morphology and a full coverage fixed partial denture.
Bickerstaff's encephalitis
Authors: Horton Emma , Krishnamoorthy Sanjay , Reynolds Lucy
Published: July 2014

Bickerstaff's brainstem encephalitis is a rare syndrome defined by the triad of ophthalmoplegia, ataxia and decreased consciousness. It is considered to be a variant of Miller Fisher syndrome and Guillain-Barré syndrome but is differentiated from the two by the presence of central nervous system involvement, commonly in the form of impaired consciousness. We present an unusual case of Bickerstaff's encephalitis, where the patient presented with pseudobulbar affect.
The nature and importance of quality of therapeutic relationships in the delivery of palliative care to people with intellectual disabilities
Authors: Ryan Karen , Guerin Suzanne , McEvoy John
Published: July 2014

Background

The importance of the therapeutic relationship in the delivery of palliative care is well recognised. Little has been published on the nature or quality of relationships formed between staff and patients with intellectual disabilities despite case reports suggesting that difficulties exist in providing palliative care to this group.

Aims

This study was part of a project that aimed to describe the delivery of palliative care to people with intellectual disabilities in a region of Ireland and to conduct a corporate assessment of palliative care need. We detail findings that explore the nature and importance of the quality of relationship in the delivery of care.

Methods

91 staff from palliative care and intellectual disability services participated in 16 focus groups.

Findings

Staff valued their relationships with service users, and felt that the quality of their relationship affected its therapeutic potential. Participants described factors fundamental to the development of quality relationships. Palliative care and intellectual disability staff commented on the importance of trust, of continuity of relationship and of knowing the individual. However, palliative care staff admitted to difficulties in these areas when providing care to people with intellectual disabilities. It appeared that quality of care was affected in situations where staff failed to form authentic relationships.

Conclusions

This study adds to our knowledge of the processes of delivery of care to people with intellectual disabilities. The description of difficulties experienced by palliative care staff gives us an opportunity to develop strategies to improve the quality of services provided.