bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transfusion‐associated circulatory overload (TACO) and potential risk factors among the inpatient US elderly as recorded in Medicare administrative databases during 2011
Authors: Menis M. , Anderson S. A. , Forshee R. A. , McKean S. , Johnson C. , Holness L. , Warnock R. , Gondalia R. , Worrall C. M. , Kelman J. A. , Ball R. , Izurieta H. S. 
Published: July 2013

Background and ObjectivesTransfusion‐associated circulatory overload (TACO) is a serious transfusion complication resulting in respiratory distress. The study's objective was to assess TACO occurrence and potential risk factors among elderly Medicare beneficiaries (ages 65 and older) in the inpatient setting during 2011.Materials and MethodsThis retrospective claims‐based study utilized Medicare administrative databases in coordination with Centers for Medicare & Medicaid Services. Transfusions were identified by recorded procedure and revenue centre codes, while TACO was ascertained via ICD‐9‐CM diagnosis code. We evaluated TACO diagnosis code rates overall and by age, gender, race, number of units and blood components transfused. Multivariate logistic regression analyses were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs).ResultsAmong 2 147 038 inpatient transfusion stays for elderly in 2011, 1340 had TACO diagnosis code, overall rate of 62·4 per 100 000 stays. TACO rates increased significantly with age and units transfused (P < 0·0001). After adjustment for confounding, significantly higher odds of TACO were found for women vs. men (OR = 1·40, 95% CI 1·26–1·60), White people vs. non‐White people (OR = 1·38, 95% CI 1·20–1·62) and persons with congestive heart failure (OR = 1·61, 95% CI 1·44–1·88), chronic pulmonary disease (OR = 1·19, 95% CI 1·08–1·32) and different anaemias.ConclusionOur study identified largest number of potential TACO cases to date and showed a substantial increase in TACO occurrence with age and number of units transfused. The study suggested increased TACO risk in elderly with congestive heart failure, chronic pulmonary disease and anaemias. Overall, study shows importance of large administrative databases as an additional epidemiological tool.
Electro-Thermal Measurement of Heat Transfer Coefficients
Authors: Uffrecht Wieland , Günther André , Caspary Volker 
Published: July 2013

Heat transfer coefficients are very important for the design of the various flow paths found in turbomachinery. Therefore, the measurement of heat transfer coefficients plays an important role in the field of turbomachinery research. An accurate measurement of heat transfer is not a simple task considering gaseous flow in combination with good thermal conductivity of the boundaries along the flow path. The majority of the measurement methods applied has at least one of the following problems. The measurement setup as for instance a heat flux sensor is a thermal barrier in the object of interest or the sensor introduces for measurement reasons a lot of heat into the object of interest. In both cases the main error results from the modification of the system, which is critical for the investigation of any kind of flow influenced by buoyancy. Furthermore, insufficient fluid reference temperature and/or heat flux with changing sign corrupts any attempt to calculate reasonably heat transfer coefficients.
The measurement of heat transfer coefficients becomes even more complicated if the flow path of interest rotates at some thousand rpm as for instance in gas turbines or any other fast rotating machine with fluid flow. This contribution presents an experimental investigation of a setup for the direct measurement of heat transfer coefficients in gaseous flow with metallic boundaries. The calibration of a test sample probe is presented for the standard case forced convection on a flat plate. The sensor setup provides low influence of the measurement on the object investigated. It overcomes the problem of a reference temperature and delivers always positive heat transfer coefficients. Furthermore, the measurement setup fulfils the requirements of telemetric application in the rotating system of a machine. The test of the sensor for its strength against centrifugal acceleration is part of the continuation of the work.
Performance and Emission Experimental Evaluation and Comparison of a Regenerative Gas Turbine Using Ethanol as Fuel
Authors: dos Santos Eraldo Cruz , do Nascimento Marco Antônio Rosa 
Published: July 2013

Brazil is the most advanced country in terms of technology, production and use of ethanol as fuel. Alcohol can be obtained from various forms of biomass, being sugarcane a current economic reality. The environmental benefits associated with the use of alcohol are enormous, as approximately 2.3 tons of CO2 are no longer emitted to the atmosphere for each ton of ethanol, without taking into account emissions of other gases such as SO2. Sugarcane is the second largest source of renewable energy in Brazil, with 12.6% of participation in the current energy matrix, considering the ethanol fuel and cogeneration of electricity from sugarcane bagasse.
The aim of this work is an experimental analysis of thermal performance/emissions of a 30 kW regenerative cycle gas turbine engine using ethanol as fuel. The tests were carried out in the laboratories of the Federal University of Itajubá – UNIFEI, Brazil, on steady state condition under different load levels, considering the properties of ethanol in compliance with Brazilian legislations.
The results shown that there were no significant changes in the thermal performance of the gas turbine engine and the emissions ware a slight increase in CO and a reduction in concentrations of NOx.
Absolute and Convective Instability in Gas Turbine Fuel Injectors
Authors: Juniper Matthew P. 
Published: July 2013

Hydrodynamic instabilities in gas turbine fuel injectors help to mix the fuel and air but can sometimes lock into acoustic oscillations and contribute to thermoacoustic instability. This paper describes a linear stability analysis that predicts the frequencies and strengths of hydrodynamic instabilities and identifies the regions of the flow that cause them. It distinguishes between convective instabilities, which grow in time but are convected away by the flow, and absolute instabilities, which grow in time without being convected away. Convectively unstable flows amplify external perturbations, while absolutely unstable flows also oscillate at intrinsic frequencies. As an input, this analysis requires velocity and density fields, either from a steady but unstable solution to the Navier–Stokes equations, or from time-averaged numerical simulations. In the former case, the analysis is a predictive tool. In the latter case, it is a diagnostic tool. This technique is applied to three flows: a swirling wake at Re = 400, a single stream swirling fuel injector at Re ∼ 106, and a lean premixed gas turbine injector with five swirling streams at Re ∼ 106.
Its application to the swirling wake demonstrates that this technique can correctly predict the frequency, growth rate and dominant wavemaker region of the flow. It also shows that the zone of absolute instability found from the spatio-temporal analysis is a good approximation to the wavemaker region, which is found by overlapping the direct and adjoint global modes. This approximation is used in the other two flows because it is difficult to calculate their adjoint global modes.
Its application to the single stream fuel injector demonstrates that it can identify the regions of the flow that are responsible for generating the hydrodynamic oscillations seen in LES and experimental data. The frequencies predicted by this technique are within a few percent of the measured frequencies. The technique also explains why these oscillations become weaker when a central jet is injected along the centreline. This is because the absolutely unstable region that causes the oscillations becomes convectively unstable.
Its application to the lean premixed gas turbine injector reveals that several regions of the flow are hydrodynamically unstable, each with a different frequency and a different strength. For example, it reveals that the central region of confined swirling flow is strongly absolutely unstable and sets up a precessing vortex core, which is likely to aid mixing throughout the injector. It also reveals that the region between the second and third streams is slightly absolutely unstable at a frequency that is likely to coincide with acoustic modes within the combustion chamber. This technique, coupled with knowledge of the acoustic modes in a combustion chamber, is likely to be a useful design tool for the passive control of mixing and combustion instability.
Development of a Lean Staged Combustor for Small Aero-Engines
Authors: Matsuyama Ryusuke , Kobayashi Masayoshi , Ogata Hideki , Horikawa Atsushi , Kinoshita Yasuhiro 
Published: July 2013

As the amount of air traffic is rapidly increasing, the local air quality around airports and the global climate change are two major concerns. Under the circumstances, the regulation for NOx emission becomes more stringent year after year. Lean burn technology is one of the key technologies for the next generation civil aircraft engines. Kawasaki Heavy Industries (KHI) has been developing a Lean Pre-mixed Pre-vaporized (LPP) combustor for around 10,000 lb thrust class engine under the project of Environmentally Compatible Aircraft Engines for Small Aircraft (ECO)[1] led by New Energy and Industrial Technology Development Organization (NEDO) and Ministry of Economy, Trade and Industry (METI).
In this paper the results of the LPP combustor development about reducing NOx emissions is presented. The LPP burner main premixed duct is designed to have better mixing fuel and air. KHI have achieved 30%CAEP4 NOx without deterioration of the other combustor performance. In general altitude relight would be one of the weak points for LPP combustion system. Successful lights were confirmed up to 30kft altitude condition in the multi sector rig, which is as good as that of the conventional combustors. Several LPP burners have been developed through CFD results. The burners have been spray-tested and combustion-tested in a single burner test rig in order to improve the burner potential. The burners selected in the single sector tests have been evaluated in a multi sector combustor rig with several combustor configurations. This paper describes the multi sector test results together with the brief introduction on burner development activities through burner tests.
Reduction of NOx Emissions in Alstom GT11NM Engines: Development, Validation and Engine Operation Experience of the EV-Alpha Burner
Authors: Magni Fulvio , Hudgins Duane , Geng Weiqun , Grimm Frank 
Published: July 2013

The first Alstom GT11N engine was introduced to the market at the end of the eighties. In order to keep our base fleet engines (aged fleet) attractive for dispatch and therefore for operation, one of the key issues of the service business is the development of upgrade packages. For the GT11N fleet an emission reduction package was worked out in recent years with the target of single digit NOx at base load (<10 ppm NOx @15%O2). The purpose of this paper is to present the performed development work, starting from the R&D work with the CFD optimization of the mixing quality, going to the atmospheric combustion tests and finally to the engine validation tests on site.
The first section of the paper focuses on the performed R&D work, mainly on the improvement of the gas/air mixing quality of the EV burner. For the down selection of the most promising configurations the calculated unmixedness at different places of the burner and the hottest flame zones were analyzed and evaluated. The second part of the paper focuses on the results of the atmospheric burner combustion tests. The last part of the paper is focusing on the verification phase and on the achieved results during the engine validation tests on site. The EV-alpha burners were implemented during an A-inspection. Before the implementation a reference measurement with the standard EV burners was carried out. This section gives an overview of the performed engine tests and achieved emissions at base load and part load, about flame stability behaviour and transient operation results.
With the implementation of the EV-alpha burner the target “single digit NOx” could be achieved and the combustion stability kept at comparable levels.
Absorption of Normal-Incidence Acoustic Waves by Double Perforated Liners of Industrial Gas Turbine Combustors
Authors: Jayatunga Charith , Qin Qin , Sanderson Victoria , Rubini Phil , You Danning , Krebs Werner 
Published: July 2013

Perforated liners consist of sheet metal perforated with multiple holes with diameters of magnitude in the order of millimeters and regular spacing, backed by an air cavity in front of a rigid wall. This type of liner is very effective at absorbing sound and is used in many applications. At the resonance frequency, the liner shifts the phase of the incident wave by 180° thus providing damping through wave cancellation.
The perforations in the liner convert acoustic energy into flow energy through vortex shedding at the rims of the liner apertures.
Applied to gas turbine combustors they can attenuate thermoacoustic instabilities and as such significantly improve the reliability of the gas turbine with an additional benefit to the emissions. The Siemens SGT-100 to 400 engines exploit this technology in their DLE combustion system in a configuration of two concentric liners separated by an air cavity with the rear liner acting as the rigid wall in the conventional setting.
In this paper the evaluation of double perforated liners in the absorption of normal-incident plane acoustic waves in an impedance tube and in a gas turbine combustor environment is investigated.
A one-dimensional impedance model that embodies the electro-acoustic analogy was used to predict the absorption characteristics of the double perforated liner. The model was validated by comparing the predictions with experimental data obtained from the impedance tube, with excellent agreement. With the confidence in the equations of the model in predicting the acoustic behavior, the model was then applied to predict the damping performance under realistic gas turbine combustor operating conditions. The prediction also shows two distinct peaks in the absorption characteristics of a double-liner.
Geometric parameters such as hole diameters & thicknesses of the two liners, gap between the liners and the overall pressure drop across the liners have been considered for the predictions. A parametric study of these parameters carried out using the ISIGHT software with design investigation tools identified the order of importance of the parameters considered for sound absorption.
The work reported in this paper has successfully validated an impedance model in the prediction of double perforated liners in the absorption of normal-incident plane acoustic waves. Based on the parametric study carried out design guidelines are given for designing a double perforated liner for maximum absorption of normal incident acoustic waves.
Ignition Delay Time and Laminar Flame Speed Calculations for Natural Gas/Hydrogen Blends at Elevated Pressures
Authors: Brower Marissa , Petersen Eric , Metcalfe Wayne , Curran Henry J. , Füri Marc , Bourque Gilles , Aluri Naresh , Güthe Felix 
Published: July 2013

Applications of natural gas and hydrogen co-firing have received increased attention in the gas turbine market, which aims at higher flexibility due to concerns over the availability of fuels. While much work has been done in the development of a fuels database and corresponding chemical kinetics mechanism for natural gas mixtures, there are nonetheless few if any data for mixtures with high levels of hydrogen at conditions of interest to gas turbines. The focus of the present paper is on gas turbine engines with primary and secondary reaction zones as represented in the Alstom and Rolls Royce product portfolio.
The present effort includes a parametric study, a gas turbine model study, and turbulent flame speed predictions. Using a highly optimized chemical kinetics mechanism, ignition delay times and laminar burning velocities were calculated for fuels from pure methane to pure hydrogen and with natural gas/hydrogen mixtures. A wide range of engine-relevant conditions were studied: pressures from 1 to 30 atm, flame temperatures from 1600 to 2200 K, primary combustor inlet temperature from 300 to 900 K, and secondary combustor inlet temperatures from 900 to 1400 K. Hydrogen addition was found to increase the reactivity of hydrocarbon fuels at all conditions by increasing the laminar flame speed and decreasing the ignition delay time. Predictions of turbulent flame speeds from the laminar flame speeds show that hydrogen addition affects the reactivity more when turbulence is considered. This combined effort of industrial and university partners brings together the know-how of applied, as well as experimental and theoretical disciplines.
Simulation of Spray Autoignition Introducing “Spraylets”
Authors: Klinkov Konstantin , Eigenbrod Christian , Giese Frank , Rickmers Peter , Reimert Manfredo 
Published: July 2013

Spray ignition is a complex combination of physical and chemical processes. Therefore there is no way to simulate all processes without significant simplifications. Dynamic and thermal effects of droplets in a two phase flow are respected through averaged properties of mass, momentum and energy. When modeling mixing of fuel vapor with the surrounding gas, the differences between diffusion rates of components as well as the finite penetration of the diffusion fluxes are not taken into account. Last seen in the fact that fuel vapor is uniformly mixed with the gas filling within the calculation cell, whose dimensions are several orders of magnitude larger than the droplet. As a consequence, the chemical reactions in the two-phase medium are represented by volume processes in the computational cell. Meanwhile, it is well known that the surrounding of an individual droplet or a group of droplets is characterized through significant inhomogeneity. Under such circumstances, self-ignition of fuel vapor cannot be considered as a process in a well stirred reactor of a size of the computational cell.
In this work a new approach for spray ignition simulation is presented. The simulation is split into two tasks. A CFD package is used to calculate spray injection and subsequent two-phase flow in the given conditions. From this two-phase flow the droplet track data and the gas phase parameters are extracted to serve as variable boundary conditions for the second task, the one dimensional single droplet ignition simulations, named “Spraylet”, which are fully transient and based on comprehensive chemistry. The obtained ignition delay times can be transformed into spatial distributions of ignition probability. While the CFD part is handling spray formation, turbulence, temperature, pressure and global vaporization, the spraylet calculations take care of droplet related physics and chemistry.
The spraylet model is based on the transient differential energy and mass conservation equations in the liquid and gas phases with variable physical properties. Also the concept of multi-component diffusion is applied. The effects of the presence of neighboring droplets in the flow, usually referred to as “spray” effects, is approximated by taking modifications of the conditions at the outer boundary of the computational domain into account. Thus the model considers the finite rates of diffusion and chemical reactions, as well as spray effects, and allows for spray ignition simulations to predict the most probable instants of ignition of the individually calculated droplet trajectories.
The validation of the spraylet-based simulation is performed by comparison with experimental data obtained in the hot-wind-tunnel. N-heptane as liquid fuel was injected into cross flow of air with a pressure of 5 bar and a temperature of 800 K.
Effects of the Mean Flow Field on the Thermo-Acoustic Stability of Aero-Engine Combustion Chambers
Authors: Gikadi Jannis , Sattelmayer Thomas , Peschiulli Antonio 
Published: July 2013

This paper presents a finite element methodology to predict the thermoacoustic eigenmodes of combustion chambers using the linearized Navier-Stokes equations (LNSE) in frequency space. The effect of the mean flow on the acoustics is accounted for. Besides scattering and refraction of acoustic waves in shear layers, this set of equation describes two main damping mechanisms. One is related to the generation of entropy waves, so called hot-spots, in flame regions. The other is related to the transformation of acoustic energy into vorticity waves at sharp leading or trailing edges. Both fluctuation types, i.e. entropy and vorticity, are convected by the mean flow, leading to significant damping when the fluid discharges into an open outlet. In combustion chamber environments these waves are accelerated in the downstream high pressure distributor and are partially transformed back into acoustic waves constituting to the feedback loop of thermo-acoustic instabilities. Accurate prediction of the eigenmodes and eigenfrequencies of instability require therefore to take these interaction effects into account.
First, the accuracy of the LNSE approach, to capture the damping generated by the first mechanism of entropy generation and convection, is investigated for a generic premixed flame configuration. Solutions of the LNSE are compared to the analytic solutions as well as eigenvalues determined by an Helmholtz ansatz. Later methodology assumes a quiescent medium and neglects all interactions of acoustics with the mean flow. It is shown that large errors are introduced with increasing Mach-number.
To illustrate errors assuming a quiescent medium for realistic combustion chambers, the LNSE are used to assess the eigenmodes of a two-dimensional aero-engine combustor including strong shear regions, in the next step. The non-isothermal mean flow field is obtained performing an incompressible RANS simulation. It features an expanding jet with inner and outer recirculation zones. The acoustic computations using LNSE reveal a set of unstable and neutral hydrodynamic modes in addition to acoustic modes. Both damping mechanisms are present and contribute to the overall system stability. Again the obtained solution is compared to the solution of an Helmholtz code and differences are discussed.