bluuebunny/crossref_metadata_2025 huggingface dataset:
Perception of Pediatric Pain: a comparison of postoperative pain assessments between child, parent, nurse, and independent observer
Authors: Khin Hla Thel , Hegarty Mary , Russell Phil , Drake‐Brockman Thomas F , Ramgolam Anoop , von Ungern‐Sternberg Britta S.
Published: July 2014

Introduction

Pain is a subjective experience. In children with limited understanding and communication skills, reliable assessment of pain is challenging. Self‐reporting of pain is the gold standard of pain measurement. For children who are unable to self‐report their pain, assessments made by their parents are often used as a proxy measure. The validity of this approach has not been conclusively determined.

Aim

To investigate differences in the assessment of pediatric pain between children, parents, nurses, and independent observers in the acute postoperative setting.

Method

Three hundred and seven children (207 verbal, 100 nonverbal) undergoing elective day‐case surgery were asked to participate in this quality of care audit. Pain scores given by verbal children, their parents, nurses, and independent observers were collected. A numerical rating scale or the Wong‐Baker Faces Pain Scale was used. All participants were blinded from other scorers.

Results

For verbal children, scores reported by patients and their parents did not differ significantly. Median [inter‐quartile range (IQR)] scores by children, parents, nurses, and independent observers were, respectively, 2.0 (0–4.0), 2.0 (1.0–4.0), 0.0 (0–2.0), and 1.0 (0–2.0). In nonverbal children, median (IQR) scores by parents, nurses, and independent observers were 1.0 (0–3.0), 0 (0–1.0), and 0 (0–2.0), respectively. The agreement between the different scorers was statistically significant.

Conclusion

Children's pain self‐reports should be used wherever possible to guide management, but in their absence, parental pain scores can be reliably used as a surrogate measure. Nurses and independent observers produce lower pain scores than parents or children, which may result in inadequate treatment of pain.
Virus‐induced gene silencing reveals control of reactive oxygen species accumulation and salt tolerance in tomato byγ‐aminobutyric acid metabolic pathway
Authors: BAO HEXIGEDULENG , CHEN XIANYANG , LV SULIAN , JIANG PING , FENG JUANJUAN , FAN PENGXIANG , NIE LINGLING , LI YINXIN
Published: July 2014

γ‐Aminobutyric acid (GABA) accumulates in many plant species in response to environmental stress. However, the physiological function ofGABAor its metabolic pathway (GABAshunt) in plants remains largely unclear. Here, the genes, includingglutamate decarboxylases(SlGADs),GABA transaminases(SlGABA‐Ts) andsuccinic semialdehyde dehydrogenase(SlSSADH), controlling three steps of the metabolic pathway ofGABA, were studied through virus‐induced gene silencing approach in tomato. Silencing ofSlGADs(GABAbiosynthetic genes) andSlGABA‐Ts(GABAcatabolic genes) led to increased accumulation of reactive oxygen species (ROS) as well as salt sensitivity under 200 mmNaCltreatment. Targeted quantitative analysis of metabolites revealed thatGABAdecreased and increased in theSlGADs‐ andSlGABA‐Ts‐silenced plants, respectively, whereas succinate (the final product ofGABAmetabolism) decreased in both silenced plants. Contrarily,SlSSADH‐silenced plants, also defective inGABAdegradation process, showed dwarf phenotype, curled leaves and enhanced accumulation ofROSin normal conditions, suggesting the involvement of a bypath for succinic semialdehyde catabolism toγ‐hydroxybutyrate as reported previously inArabidopsis, were less sensitive to salt stress. These results suggest thatGABAshunt is involved in salt tolerance of tomato, probably by affecting the homeostasis of metabolites such as succinate andγ‐hydroxybutyrate and subsequentROSaccumulation under salt stress.
Identification and functional characterization of the Arabidopsis Snf1‐related protein kinase SnRK2.4 phosphatidic acid‐binding domain
Authors: JULKOWSKA MAGDALENA M. , MCLOUGHLIN FIONN , GALVAN‐AMPUDIA CARLOS S. , RANKENBERG JOHANNA M. , KAWA DOROTA , KLIMECKA MARIA , HARING MICHEL A. , MUNNIK TEUN , KOOIJMAN EDGAR E. , TESTERINK CHRISTA
Published: July 2014

Phosphatidic acid (PA) is an important signalling lipid involved in various stress‐induced signalling cascades. Two SnRK2 protein kinases (SnRK2.4 and SnRK2.10), previously identified as PA‐binding proteins, are shown here to prefer binding to PA over other anionic phospholipids and to associate with cellular membranes in response to salt stress in Arabidopsis roots. A 42 amino acid sequence was identified as the primary PA‐binding domain (PABD) of SnRK2.4. Unlike the full‐length SnRK2.4, neither the PABD‐YFP fusion protein nor the SnRK2.10 re‐localized into punctate structures upon salt stress treatment, showing that additional domains of the SnRK2.4 protein are required for its re‐localization during salt stress. Within the PABD, five basic amino acids, conserved in class 1 SnRK2s, were found to be necessary for PA binding. Remarkably, plants overexpressing the PABD, but not a non‐PA‐binding mutant version, showed a severe reduction in root growth. Together, this study biochemically characterizes the PA–SnRK2.4 interaction and shows that functionality of the SnRK2.4 PABD affects root development.
Effects of flower dimorphism and light environment on arbuscular mycorrhizal colonisation in a cleistogamous herb
Authors: Parra‐Tabla V. , Munguía‐Rosas M. , Campos‐Navarrete M. J. , Ramos‐Zapata J. A.
Published: July 2014

Although it is known that floral dimorphism contributes to the maintenance of mixed breeding systems, the consequences of producing progeny of a contrasting genetic background and seeds with differential resource allocation has been practically ignored regarding establishment of belowground organisms–plant interactions. This article evaluates the combined effect of floral dimorphism with cross type and light environment on interactions between Ruellia nudiflora and arbuscular mycorrhizal fungi (AMF). R. nudiflora produces cleistogamous (CL) flowers that exhibit obligate self‐pollination and chasmogamous (CH) flowers with facultative self‐ (CHs) or cross‐ (CHc) pollination. We evaluated the establishment of the plant–AMF interaction in progeny derived from each floral type, under two light conditions (shaded versus open). We established different scenarios depending on the existence of inbreeding depression (ID) and whether the differential resource allocation (DRA) to CH and CL flowers affected the R. nudiflora–AMF interaction. We predicted that under shaded light conditions there might be an intensification of ID, having a negative effect on AMF colonisation. The percentages of hyphae and vesicles in the harvested roots was significantly higher in the shaded plants (F ≥ 4.11, P < 0.05), while progeny of CHc and CHs presented a higher percentage of hyphae and vesicle colonisation compared to CL progeny (F = 15.26, P < 0.01). The results show that DRA to CH flowers and light availability both determines the establishment of R. nudiflora–AMF interaction. The results also suggest that even under stressful light conditions, endogamy does not affect this interaction, which may explain the success of R. nudiflora as an invasive species.
Context reinstatement and memory for intrinsic versus extrinsic context: The role of item generation at encoding or retrieval
Authors: Nieznański Marek
Published: July 2014

According to many theoretical accounts, reinstating study context at the time of test creates optimal circumstances for item retrieval. The role of context reinstatement was tested in reference to context memory in several experiments. On the encoding phase, participants were presented with words printed in two different font colors (intrinsic context) or two different sides of the computer screen (extrinsic context). At test, the context was reinstated or changed and participants were asked to recognize words and recollect their study context. Moreover, a read‐generate manipulation was introduced at encoding and retrieval, which was intended to influence the relative salience of item and context information. The results showed that context reinstatement had no effect on memory for extrinsic context but affected memory for intrinsic context when the item was generated at encoding and read at test. These results supported the hypothesis that context information is reconstructed at retrieval only when context was poorly encoded at study.
Persimals
Authors: Luper Steven
Published: July 2014

What sort of thing, fundamentally, are you and I? For convenience, I use the termpersimalto refer to the kind of thing we are, whatever that kind turns out to be. Accordingly, the question is, what are persimals? One possible answer is that persimalhood consists in being a human animal, but many theorists, includingDerekParfit andJeffMcMahan, not to mention John Locke, reject this idea in favor of a radically different view, according to which persimalhood consists in having certain sorts of mental or psychological features. In this essay, I try to show that the animalist approach is defensible as against the mentalist approach. I also suggest that animalists have a plausible story to tell about cases such as brain transplantation and dicephaly that might appear to support the mentalist approach.
Animalism and the Persistence of Human Organisms
Authors: Dupré John
Published: July 2014

Humans are a kind of animal, and it is a natural and sensible idea that the way to understand what it is for a human person to persist over time is to reflect on what it is for an animal to persist. This paper accepts this strategy. However, especially in the light of a range of recent biological findings, the persistence of animals turns out to be much more problematic than is generally supposed. The main philosophical premise of the paper is that living systems generally are best treated as processes rather than things. These processes prove to be so complexly intertwined and interdependent, that there is no unique, objective way of distinguishing the individuals from which they are composed. For this reason the animalist perspective, it is argued, problematizes as much as it resolves the problem of personal identity. Traditional concerns with responsibility and reactive attitudes provide an intelligible and defensible motivation for distinguishing the individuals we standardly assume as the explanandum in these discussions. But, from a biological point of view, the underlying individualism is a contingent perspective, as much justified by these concerns as providing an objective grounding for them.
Models, Mechanisms, and Animal Minds
Authors: Allen Colin
Published: July 2014

In this paper, I describe grounds for dissatisfaction with certain aspects of the sciences of animal cognition and argue that a turn toward mathematical modeling of animal cognition is warranted. I consider some objections to this call and argue that the implications of such a turn are not as drastic for ordinary, commonsense understanding of animal minds as they might seem.
Roughness Corrections for the k–ω Shear Stress Transport Model: Status and Proposals
Authors: Aupoix B.
Published: July 2014

Various corrections were previously proposed to account for wall roughness with the k–ω and shear stress transport (SST) models. A simplified analysis, based upon the wall region analysis, is proposed to characterize the behavior of these roughness corrections. As this analysis points out some deficiencies for each correction, two new corrections are proposed for the SST model, to reproduce different behaviors, mainly in the transition regime. The correction development is based upon a previously developed strategy. A large set of boundary layer experiments is used to compare the different roughness corrections, confirm the failures of previous proposals, and validate the present ones. Moreover, it assesses the proposed simplified analysis. It also evidences the difficulty to determine the equivalent sand grain roughness for a given surface. The Colebrook based correction is recommended while the Nikuradse based one can add information about the envelope of possible behaviors in the transition regime.
A Theoretical Analysis of the Mixed Elastohydrodynamic Lubrication in Elliptical Contacts With an Arbitrary Entrainment Angle
Authors: Pu Wei , Wang Jiaxu , Zhang Ying , Zhu Dong
Published: July 2014

Numerical simulations of the elastohydrodynamic lubrication (EHL) have been conducted by many researchers, in which the entrainment velocity is usually parallel to one of the axes of Hertzian contact ellipse. However, in some engineering applications, such as the counterformal contacts in spiral bevel and hypoid gears, entraining velocity vector may have an oblique angle that could possibly influence the lubrication characteristics significantly. Also, a vast majority of gears operate in mixed EHL mode in which the rough surface asperity contacts and lubricant films coexist. These gears are key elements widely used for transmitting significant power in various types of vehicles and engineering machinery. Therefore, model development for the mixed EHL in elliptical contacts with an arbitrary entrainment angle is of great importance. In the present paper, a recently developed mixed EHL model is modified to consider the effect of arbitrary entraining velocity angle, and the model is validated by comparing its results with available experimental data and previous numerical analyses found in literature. Based on this, numerical simulations are conducted to systematically study the influence of entrainment angle on lubricant film thickness in wide ranges of speed, load, and contact ellipticity. The obtained results cover the entire lubrication spectrum from thick-film and thin-film lubrication all the way down to mixed and boundary lubrication. In addition, minimum film thickness prediction formula is also developed through curve-fitting of the numerical results.
The Modeling and Analysis of a Package-Scale Circulating Fluidized Combustor
Authors: Kremer Matthew J. , Yavuzkurt Savas
Published: July 2014

The preliminary analysis of a package-scale circulating fluidized bed (CFB) combustor through modeling and experimentation was performed to help determine particle trajectories and carbon burnout efficiency. The CFB consisted of a primary fast fluidizing bed and two bubbling beds. The fluidized bed models found in literature and a freeboard model utilizing a commercial code, FLUENT, were used in simulations. Primary gas velocity of the fast fluidizing bed was varied between 4.9 and 12.2 m/s and gas temperatures were varied between 800 and 1200 K. For comparison with computations of hydrodynamics, a scaled down version of the combustor was run using granulated plastic particles at 300 K.

The results of computations showed that the freeboard has a very complex flow with many recirculation zones that usually become larger and move away from the walls with increasing primary velocity. There was less particle movement in the experiments than in the simulations due to the differences in particle diameters, the type of particles, the gas temperature, and the scaling geometry.
A Unique Correction Technique for Evaporative Gas Turbine (EvGT) Parameters
Authors: Mesbahi Ehsan , Assadi Mohsen , Torisson Tord , Lindquist Torbjörn
Published: July 2014

Modelling and data-normalization of a gas turbine process, called Evaporative Gas Turbine (EvGT) is studied here. The most important factor to achieve a high level of accuracy during the data normalization, is the consideration of changes in thermodynamic properties of the working medium at different environmental conditions. Performance of the EvGT, which is working with a mixture of air and steam, is strongly affected by the changes in the environmental conditions. When the properties of the working fluid such as the water content are continuously changing, the normalization process using conventional techniques becomes very difficult if not impossible. In this study, measured data from the worlds’ first Evaporative Gas Turbine at Lund University in Sweden have been used for generation of an empirical model by a single Artificial Neural Network system. Performance maps generated by ANN have been successfully used for data normalization and performance prediction of the Evaporative Gas Turbine. ANN predicted values are compared with experimental results, not used during the training, where very good correlation was observed.
Model Based Control Concepts for Jet Engines
Authors: Lietzau Klaus , Kreiner Andreas
Published: July 2014

Many jet engine variables cannot be measured in-flight or can only be measured with a complex, and hence unreliable, instrumentation system. This includes variables that are of imminent importance for the safe operation of the engine or for engine life, such as the temperature of the high pressure turbine blades or the surge margins of the turbo compressors, for instance. Current control systems therefore transform limits on these variables into limits on other variables measured by the engine’s sensors. This leads to increased safety margins and thus to non-optimal engine performance. An onboard engine model incorporated into the engine control system could provide information about all engine variables. This could enable further control and monitoring system optimisations leading to improved engine performance, reduced fuel consumption, increased safety and engine life.

This paper explains the principle of model based engine control and gives an overview about possible applications for conventional and also thrust vectored jet engines. Modeling methods for real-time simulation as well as methods for online model adaptation are presented. The potential of model based jet engine control is analyzed and fortified by some prototype realizations.
Multivariable Modelling of Gas Turbine Dynamics
Authors: Evans Ceri , Chiras Neophytos , Guillaume Patrick , Rees David
Published: July 2014

The linear multivariable modelling of an aircraft gas turbine is presented. A frequency-domain identification method is employed to estimate a family of models from engine data at a range of operating points. It is found that the fuel feed to shaft speed dynamics can be represented by second-order models. This matches the results obtained for the reduced-order linearised thermodynamic models derived from the engine physics. A direct comparison can thus be made between the estimated and thermodynamic models, which shows significant discrepancies between them for the engine tested. This work illustrates how modern system identification techniques can be used to verify engine models. The multivariable framework employed means that additional inputs and outputs can be easily incorporated into the model.
Hybrid Magnetic/Foil Bearing System for an Oil-Free Thrust Bearing Test Rig
Authors: Russell Thomas E. , Heshmat Crystal , Locke Dennis
Published: July 2014

A novel, high-speed, high temperature, oil-free, foil thrust bearing test rig has been developed with a critical element being a double-acting, active magnetic thrust bearing. The magnetic thrust bearing is used to react against loads applied to the foil thrust bearing under test. The magnetic bearing has the capability of reacting against thrust loads of up to 2224 N (500 pounds) at speeds to 80,000 rpm, while the rotor is supported by foil journal bearings.

Two issues that are especially challenging for this test rig are magnetic material selection and the electronic control system. The magnetic material selection is critical due to the high centrifugal stresses that occur at 80,000 rpm. The electronic control system must handle the non-linear variation in stiffness and damping that is seen by the magnetic thrust bearing as the foil thrust bearing is loaded, as well as maintain rotor system stability as the foil bearing is purposefully overloaded to the point of failure to discover maximum load and performance capabilities.

This paper describes the design of the active magnetic thrust bearing, the material selection process, and the development of a digital signal processor based control system.

Typical experimental data obtained during operation of the test rig will also be presented.
Rolling Element Bearing Defect Detection and Diagnostics Using Displacement Transducers
Authors: Yu John J. , Bently Donald E. , Goldman Paul , Dayton Kenwood P. , Van Slyke Brandon G.
Published: July 2014

This paper introduces the methodology of rolling element bearing defect detection using high-gain displacement transducers. The nature of defect influence on the outer race deflection in the vicinity of the transducer tip in time base has been established. Inner race, outer race, and rolling element (ball/roller) defects, which often occur sequentially, can be clearly identified according to spike signals on the time-varying outer race deflection curve along with known bearing frequencies. The developed techniques are fully corroborated by experimental data. Spike-to-deflection amplitude ratio, which is almost independent of changes in speed and load for a given defect, is used to judge the defect severity. Spectral characteristics due to these defects have also been found. It is shown that this direct measurement by using displacement transducers without casing influence, which would be inevitable by using accelerometers mounted on the casing, is a reliable approach to detect bearing defects as well as their severity and locations.
Improved Vibration Monitoring on Aeroderivative Gas Generators With Internal Transducers
Authors: Swan Peyton , Betts Robert G.
Published: July 2014

This paper discusses a research project undertaken by Bently Nevada Corporation and TransCanada PipeLines to develop an improved machinery condition monitoring system for the Rolls-Royce Avon gas turbine engine. The project centers on the installation of internal vibration and temperature transducers in and around the engine internal wheel case housing for the center bearing. The paper outlines the current industry-accepted vibration monitoring system, why there is a need to improve the system, the design of the internal transducer mounting arrangements, and test results of the new system.
Finite Element Modeling of the Eddy-Current Inspection of Land-Based Gas Turbine Blades
Authors: Fukutomi Hiroyuki , Ogata Takashi
Published: July 2014

There has been a growing need in recent technology of gas turbines in combined cycle to assess the remaining life of high temperature components. It is also required that the nondestructive assessment be more accurate in maintaining combined cycle plants. This paper describes the use of a simulator solving forward and inverse problems under eddy current testing, in parametric studies of inspection parameters for 1100°C-class gas turbine blades in terms of test probe capabilities, frequencies and signal interpretation. The simulator is based on a differential formulation constructed with a magnetic vector potential and a 3-dimensional edge-based finite-element modeling method. Its features are forming coils and defects independent of a whole finite element model, very fast eddy current response predictions, and identifications of electromagnetic properties. Using the simulator, optimal sensor types and test frequencies are determined in terms of assessment of degradation, selectability between surface-breaking and subsurface cracks, reconstruction of crack profiles, and detection of multiple cracks.
Improved Gas Turbine Performance Prediction Using a Map Based Fleet Analysis
Authors: Werner Klaus
Published: July 2014

The more accurate a performance prediction is the higher the benefit will be for both, the customer and the manufacturer of gas turbines. The customer will achieve an advantage as the whole plant will work close to its design parameters and thus close to the planned economical optimum, while the manufacturer can guarantee the performance of the gas turbine with minimised margins.

This paper describes how the combination of certain software tools and detailed fleet analysis leads to performance predictions with high confidence levels considering at the same time that the handling of thousands of data has to be based on a sufficient quality procedure. As the methods focus on heavy duty gas turbines producing electrical power in commercial applications, only quasi steady state operation at constant speed is investigated.

Based on the definitions for compressor and turbine maps the paper explains, how test data are evaluated, statistically investigated and finally used as an input for a routine that assimilates the maps to the best knowledge of what has been concluded out of the test experiences so that the circle is closed. Showing examples out of a fleet analysis for a Siemens gas turbine the principles of the single steps are illustrated. The structure of the used maps is described as well as the basic application of the mathematical methods.

The focus, however, is not on the special mathematical solution itself, but on the principle of the general procedure, i.e. that for the specific task of predicting those performance data that have direct impact on plant economics, a simplified method can be derived that not necessarily has to take into account the physical correlation of parameters that are used to describe a gas turbine cycle on a higher detailed level. Thus the paper should not be understood as a further attempt to optimise mathematical functions for maps in order to simulate gas turbine operation, but as a report on how sufficient results may be obtained concerning to practical and fast performance prediction, even though only a few values are measured and investigated theoretically.
Study of Liquid Atomization in an Internally Mixed Liquid Atomizer
Authors: Kushari A. , Neumeier Y. , Lubarsky E. , Zinn B. T.
Published: July 2014

This paper presents the results of experimental and theoretical studies of an internally mixed liquid injector. In this type of injector atomization is attained by injecting a small amount of air into a liquid stream within the injector. The results presented in this paper suggest that the investigated injector could be used to control the flow rate and spray characteristics, e.g., droplet size and spray penetration, and hence, a “controlled” version of the investigated injector may find applications in modern gas turbine engines. This paper also describes the development and predictions of a heuristic model that depicts the two-phase flow inside an internally mixed atomizer. The developed model assumes that the formation of liquid drops, due to the interaction between the air and liquid flows, occurs inside the injector. Basic conservation equations, along with appropriate boundary conditions, are used to model the two-phase air-liquid flow inside the injector. A statistically distributed Weber number criterion is used to estimate the sizes of the droplets being produced in the process. The liquid flow rates and the droplet sizes predicted by the model are compared with the experimental data and they are found to be in fair agreement with each other, suggesting that the model properly describes the physics of the two-phase flow within the injector.
Flashback in a Swirl Burner With Cylindrical Premixing Zone
Authors: Fritz Jassin , Kröner Martin , Sattelmayer Thomas
Published: July 2014

Flame flashback from the combustion chamber into the mixing zone is one of the inherent problems of lean premixed combustion and essentially determines the reliability of low NOx burners. Generally, flashback can be initiated by one of the following four phenomena: flashback due to the conditions in the boundary layer, flashback due to turbulent flame propagation in the core flow, flashback induced by combustion instabilities and flashback caused by combustion induced vortex breakdown.

In this study, flashback in a swirling tubular flow was investigated. In order to draw maximum benefit from the tests with respect to the application in gas turbines, the radial distribution of the axial and circumferential momentum in the tube was selected such that the typical character of a flow in mixing zones of premix burners without centerbody was obtained. A single burner test rig has been designed to provoke flashback with the preheating temperature, the equivalence ratio and the mean flow rate being the influencing parameters. The flame position within the mixing section is detected by a special optical flame sensor array, which allows the control of the experiment and furthermore the triggering of the measurement techniques. The burning velocity of the fuel has been varied by using natural gas or hydrogen.

The characteristics of the flashback, the unsteady swirling flow during the flame propagation, the flame dynamics and the reaction zones have been investigated by applying High Speed Video recordings, the Laser Doppler Anemometry and the Laser Induced Fluorescence. The presented results show that a combustion induced vortex breakdown is the dominating mechansim of the observed flashback. This mechanism is very sensitive to the momentum distribution in the vortex core. By adding axial momentum around the mixing tube axis, the circumferential velocity gradient is reduced and flashback can be prevented.
Performance of a Trapped Vortex Spray Combustor
Authors: Mancilla Paulo C. , Chakka Pitchaiah , Acharya Sumanta
Published: July 2014

The performance of a liquid-fueled trapped vortex (TV) combustor is analyzed both experimentally and computationally. The TV cavity, formed between a forebody and an afterbody, is placed coaxially inside a combustor shell. Fuel and primary air are injected from the inside face of the afterbody. The flame holding capability of this trapped vortex configuration is evaluated for different primary equivalence ratios. Very low overall lean-blow-out (LBO) equivalence ratios are obtained for the TV combustor over a wide range of annular and primary airflow rates. It is found that by injecting the primary air with a tangential velocity component the circumferential mixing is improved without disrupting the vortex trapped in the cavity. The performance of the TV combustor is also evaluated through emissions measurements at the exit of the combustor and temperature distribution inside the cavity. Numerical simulations are performed for the TV configuration with a k-ε turbulence model coupled with a PDF combustion chemistry model for simulating liquid spray combustion. The predicted results are in reasonable agreement with the measurements and provide an assessment of the flow distribution in the cavity region.
High Turndown Ratio Low NOx Gas Turbine Combustion
Authors: Andrews G. E. , Mkpadi M. C.
Published: July 2014

The aim of this work was to show that a two-stage system of pilot and main burner could be used to extend the range of minimum to maximum power (turndown) under low NOx conditions. All the combustion air was admitted to the first stage where the natural gas fuel was split between the pilot and the main swirler. The main swirler was a counter-rotating radial swirler, with only the upstream passage fuelled, using a single point fuel injector on the centre of each radial vane passage inlet. Two pilot fuel injector locations were investigated: central radial outward injection and injection into the dump expansion recirculation zone. It was shown at 600K inlet temperature and atmospheric pressure, that with the central pilot fuelled at a constant 0.18 equivalence ratio the main fuel could be increased to 0.7 equivalence ratio with the NOx increasing from 4 to 6 ppm at 15% oxygen. The use of the outer dump expansion recirculation zone for the pilot resulted in excellent turndown, but higher NOx emissions than for the central pilot fuel injection. This gave a very compact low NOx combustor with a high turndown and no acoustic problems.
Performance Prediction and Combustion Modeling of Low-CO2 Emission Gas Turbines
Authors: Bozza Fabio , Cameretti Maria Cristina , Tuccillo Raffaele
Published: July 2014

The authors present a comprehensive analysis of innovative solutions for reducing the CO2 emission from gas turbine based power plants. Two different gas turbine types are considered, first in their baseline arrangement and then with modified configurations with regenerative, water-intercooled cycles.

The carbon dioxide reduction is obtained through a partial oxidation of the natural gas upstream of the combustion chamber.

The analyses are carried out with an increasing level of complexity, starting from a purely thermodynamic approach and then proceeding with a component matching based method.

Finally, the comparison of the CFD simulation of the combustion processes of the conventionally fuelled combustor and of the one supplied with the decarbonized fuel is presented.
Daesan Combined Cycle Power Plant: Successful Operating Experience on Low Sulphur Waxy Residual Fuel Oil
Authors: Lee Koen-Woo , Kim Hwan-Doo , Wi Sung-Il , Stalder Jean-Pierre
Published: July 2014

This paper presents and discusses the successful operating experience and the issues related to burning low sulphur waxy residual (LSWR) fuel oil at the 507 MW IPP Daesan Combined Cycle Power Plant. The power plant was built and is operated by Hyundai Heavy Industries (HHI). It comprises four Siemens-Westinghouse 501D5 engines, each with a heat recovery boiler including supplementary firing and one steam turbine. This plant, commissioned in 1997, is designed to burn LSWR fuel oil. LSWR fuel oil was selected because of the lower fuel cost as compared to LNG and other liquid fuels available in Korea. By adding a combustion improver to the LSWR fuel oil it is possible for HHI to comply with the tight Korean environmental regulations, despite the tendency for heavy smoke and particulate emissions when burning this type of fuel oil. The successful operating experience, availability, reliability and performance achieved in Daesan, as well as the commercial viability (which by far offsets the additional capital expenditure and the additional related O&M costs) demonstrate that LSWR fuel oil firing in heavy duty gas turbines is rewarding. This is especially important in view of the growing disposal problems of residuals at refineries around the world.
Multi Fuel Concept of the Siemens 3A – Gas Turbine Series
Authors: Deuker Eberhard , Waldinger Roger , Rauh Horst Uwe , Schade Frank
Published: July 2014

To provide maximum fuel flexibility, Siemens has developed a liquid-fuel supply system for its 3A-Series gas turbines, which in addition to customary distillate can also accommodate special fuels such as naphtha and condensates, and which also enables fuel changeover during gas turbine operation. The high vapor pressure and correspondingly low flash point of naphtha and condensates necessitate a complex fuel system safety concept as well as special flushing procedures when the gas turbine is started up and shut down. The addition of water to the fuel has been shown to be an efficient method of reducing NOx emissions. This addition of water, coupled with the highly variable fuel density, places increased demands on the gas turbine control system. Moreover, it is possible to switch from natural-gas operation to fuel-oil operation and back again when the turbine is operated in the output range near base load.
Development of Dry Low-NOx Combustor for 300 kW Class Gas Turbine Applied to Co-Generation Systems
Authors: Ohkubo Yoichiro , Azegami Osamu , Sato Hiroshi , Idota Yoshinori , Higuchi Shinichiro
Published: July 2014

A 300 kWe class gas turbine which has a two-shaft and simple-cycle has been developed to apply to co-generation systems. The gas turbine engine is operated in the range of about 30% partial load to 100% load. The gas turbine combustor requires a wide range of stable operations and low NOx characteristics. A double staged lean premixed combustor, which has a primary combustion duct made of Si3N4 ceramics, was developed to meet NOx regulations of less than 80 ppm (corrected at 0% oxygen). The gas turbine with the combustor has demonstrated superior low-emission performance of around 40 ppm (corrected at 0% oxygen) of NOx, and more than 99.5% of combustion efficiency between 30% and 100% of engine load. Endurance testing has demonstrated stable high combustion performance over 3,000 hours in spite of a wide compressor inlet air temperature (CIT) range of 5 to 35 degree C.. While increasing the gas generator turbine speed, the flow rate of primary fuel was controlled to hold a constant equivalence ratio of around 0.5 in the CIT range of more than 15 C. The output power was also decreased while increasing the CIT, in order to keep a constant temperature at the turbine inlet. The NOx decreases in the CIT range of more than 15 C. On the other hand, the NOx increases in the CIT range of less than 15 C when the output power was kept a constant maximum power. As a result, NOx emission has a peak value of about 40 ppm at 15 C.
Performance Assessment of a Prototype Trapped Vortex Combustor Concept for Gas Turbine Application
Authors: Burrus D. L. , Johnson A. W. , Roquemore W. M. , Shouse D. T.
Published: July 2014

GE Aircraft Engines and the Air Force Research Laboratory have been jointly developing a novel combustor technology concept for potential application in gas turbine engines. This novel combustor concept is known as the Trapped Vortex Combustor (TVC). The GE and AFRL team began work on the design of a prototypical TVC test rig in 1996. This effort represents the extension of earlier AFRL research with the TVC [1,2]. This work led to the fabrication of a 30.5 cm wide rectangular sector test rig capable of operation at inlet pressures up to 20.5 atmospheres, inlet temperatures up to 900 K, and to stoichiometric discharge conditions. Testing of the rectangular sector rig was initiated in mid year 1998. The performance evaluation performed on the test rig covered all aspects of gas turbine combustor performance and operability including ground start ignition, lean blowout, altitude re-light, emissions, combustion efficiency, exit gas temperature profile, and structural metal temperatures. Test rig operating conditions provided simulations of current commercial and military aircraft gas turbine engine cycles as well as some advanced engine cycles, with JP-8 type fuel. Data was also obtained at selected operating conditions for the LM2500 marine Navy duty cycle using DL-1 type fuel. The prototype rig has been operated for a total of approximately 300 run hours. 60 hours of run time at pressures exceeding 13.6 atmospheres and temperatures exceeding 675 K. 12 hours of run time at pressures exceeding 15.3 atmospheres, temperatures exceeding 780 K. Over 700 data points were obtained. The assessment of the demonstrated performance revealed the prototype TVC test rig had exceeded all initial expectations. Demonstrated ignition, blow out, and altitude re-light were up to 50% improved over current technology conventional swirl stabilized combustors. NOx emissions were in the range from 40% to 60% of the 1996 ICAO standard. Combustion efficiency at or above 99% was maintained over a 40% wider operating range than a conventional combustor. The performance and operability achieved with this prototype test rig has clearly demonstrated the validity and potential performance payoffs of the TVC concept. This paper will summarize the TVC rectangular sector test rig configurations evaluated as part of this test program, and the performance and operability achieved.
Combustion Test Results of an Uncooled Combustor With Ceramic Matrix Composite Liner
Authors: Suzuki Yasufumi , Satoh Toyoichi , Kawano Manabu , Akikawa Naofumi , Matsuda Yoshihiro
Published: July 2014

A reverse-flow annular combustor with its casing diameter of 400 mm was developed using an uncooled liner made of three-dimensional-woven ceramic-matrix composite. The combustor was tested using the TRDI high-pressure combustor test facility at the combustor maximum inlet and exit temperature of 723K and 1623K respectively. Although both the material and combustion characteristics were evaluated in the test, this report focused on the combustion performance. As the results of the test, the high combustion efficiency and high heat release ratio of 99.9% and 1032 W/m3/Pa were obtained at the design point. The latter figure is approximately twice as high as that of existing reverse–flow annular combustors. Pattern factor was sufficiently low and was less than 0.1. Surface temperatures of the liner wall were confirmed to be higher than the limit of the combustor made of existing heat-resistant metallic materials.
Optimization Assessment of Hybrid MCFC-Gas Turbine Cycles
Authors: Basurto Maria-Teresa , Pilidis Pericles , Hales Richard
Published: July 2014

The intention of this paper is to offer a general description of the Molten Carbonate Fuel Cell (MCFC), its performance parameters, and the work done on the integration of MCFCs and gas turbines into an hybrid cycle to achieve high efficiencies. The paper describes results obtained for several hybrid configurations, some of them using pressurised MCFCs, others using atmospheric pressure MCFCs. Each configuration is analysed for different values of the cycle parameters, as part of the optimization process done to find an optimum solution. Finally, some conclusions are presented.

An important part of the work corresponds to the development of the code MC-GreenCell that simulates the performance of MCFC. This code, developed by the authors, estimates power, voltage, electrical current densities, heat losses, temperatures, gases flow rates and compositions, resulting from the steam reformer and from the MCFC stack. The code was utilized together with a commercial code on the assessment of the design point performance of the hybrid system. In the future the code will be used to evaluate the off-design performance of the cycle. The code has been validated using MCFC field data available from current projects.

The study focuses on hybrid cycles of 1÷25 megawatt size that may be used in commercial or industrial cogeneration, distributed power generation for hospitals, public buildings, etc.
Modelling of Alkali Contaminant Flows in Evaporative Gas Turbines
Authors: Bartlett Michael A. , Westermark Mats O.
Published: July 2014

A new advanced gas turbine cycle, called the Evaporative Gas Turbine (EvGT), also known as a Humid Air Turbine (HAT), has recently been demonstrated in Sweden, with a pilot plant built and operational. As the EvGT cycle involves complex interactions between air and water streams, air quality aspects need to be carefully examined. This article examines different strategies to prevent contamination and turbine corrosion and presents a theoretical model simulating the flow of alkali salts in the EvGT cycle for different ambient salt concentrations, cycle configurations and equipment performance.

Similar to the existing pilot plant, the EvGT cycle studied in this article requires no external water source to meet its water demands. Instead, water is condensed from the flue gas and recycled to the humidification tower. Recirculating the condensate implies that the best strategy to ensure a high air quality and hinder impurity build up and transfer within the cycle is to filter the incoming air. Furthermore, air intake filters could simplify or eliminate the need for condensate treatment. The humidification tower is an important area for the transfer of contaminants to and from the water and air streams. Minimising droplet entrainment and bleeding off a fraction of the humidifying water are key strategies to protect the turbine, while the capture of airborne particles in the humidifying water film improves the air quality.

The model constructed predicts that a small blow down from the water circuit (typically 0.1-3.5% of the feed water flow) is sufficient to ensure that the alkali concentration does not exceed those in an equivalent dry gas turbine. This blow down can then be treated and partly recycled to the water circuit or discarded.
Feasibility Study of a Gas Turbine at Micro Scale
Authors: Isomura Kousuke , Murayama Motohide , Kawakubo Tomoki
Published: July 2014

Feasibility of a small centrifugal gas turbine with its impeller diameter around a centimeter has been studied. From cycle analysis, minimum requirements for each component were set. Then, feasibility to achieve these minimum requirements were studied, component by component. The results show that the micro-scale gas turbine is feasible at impeller diameter 1cm. The largest issue will be the isolation of the heat between the compressor and the combustor to prevent the large reduction of the compressor efficiency.
System Description and Test Planning for a Combined Heat and Power (CHP) Plant Composed by a Micro Gas Turbine and an Absorption Chiller / Heater
Authors: Banetta Stefano , Paganucci Fabrizio , Giglioli Romano
Published: July 2014

The paper deals with the set-up and preliminary test-planning of an innovative mini cogeneration plant, in which exhaust gases coming from a 45 kWe rated turbogenerator directly feed an absorption chiller / heater with a 170 kWth chilling and a 160 kWth heating capability. Electric power is partly used on site to satisfy the plant auxiliary systems power demands and partly vectorised to the main building of the Engineering Faculty (15 km from the plant site) through the main electric grid. Thermal power is exploited locally for any season air conditioning of laboratory rooms.

The paper describes the plant layout and the technical solutions adopted for installation and diagnostic purposes.

This plant has been conceived even as a test-bed for Remote Monitoring (RM) and Plant Condition Monitoring (PCM) techniques development and testing. To this purpose dedicated diagnostics have been set up and mathematical models of all the main components are being developed to perform the identification of their operational parameters (e.g. efficiencies) on the basis of the acquired parameters. These are aimed at obtaining both a correct management of the plant and an early diagnosis of malfunctions to achieve the ability of following an on-condition maintenance philosophy to reduce maintenance costs and outage periods.
Graphical Spreadsheets as Convenient Tools for Turbomachinery Education
Authors: Miller Timothy F.
Published: July 2014

An unfortunate aspect of engineering education in general, and turbomachinery education in specific, has been the difficulty of incorporating the design aspect of instruction with the time-consuming components that make up theoretical instruction. The primary reason for this difficulty is the extremely limited time (typically three months) allocated to teach turbomachinery as a senior-level quarter or semester technical elective. It is desirable to develop an educational design tool that can be simultaneously exercised by a student to perform various design tasks and function as a means of theoretical instruction. Such a tool can permit the students both greater depth and breadth of exposure and may be subsequently used by the students in their future capacity as professional engineers. In this paper, this tool is illustrated by several applications of a commercial “graphical spreadsheet” software package (MathCAD, though others such as Mathmatica and Macsyma are appropriate as well). Some graphical spreadsheet design tools are presented, and these tools are applied to the analysis and design of a radial pump, centrifugal compressor, and radial-inflow turbine.