bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heat Recovery Steam Generator Health Assessment Basing on Reconciled Measurement
Authors: Sorce Alessandro , Martini Alessio , Traverso Alberto , Torelli Giorgio 
Published: September 2014

Long-term monitoring and diagnostic of power plants is a permanent issue for the energy companies. In particular with the increase of flexible operation (e.g. daily start-up and shutdown cycles, part load operations) the definition of proper diagnostic indicators becomes mandatory. Different monitoring strategies were developed, implemented and tested for the main components of a combined cycle power plant (e.g. Gas Turbine, Heat Recovery Steam Generator, Steam Turbine, Pumps) to prevent fault/failure or to plan/evaluate the maintenance activities.
This work focuses on the first principles health assessment of the Heat Recovery Steam Generator (HRSG). The impact of ambient conditions on the gas turbine outlet temperature and mass flow rate and thus on the HRSG behavior is presented referring to the control strategies of the Gas Turbine (GT). To validate the measurements a preprocessing phase basing on Data Reconciliation was performed, aimed at improving the accuracy of the estimation of exhaust mass flow rate entering the HRSG. Gas Turbine and HRSG nergy balances are exploited to reduce the uncertainties of the results, eliminate the outlier data sets and obtain consistent data. Moreover an evaluation of the sensitivity of the indicator will be made basing on field measurements before and after a maintenance intervention.
Predictive Capability of CFD Models for Transonic Compressor Design
Authors: Ellbrant Lars , Eriksson Lars-Erik , Mårtensson Hans 
Published: September 2014

The primary focus of this work is to validate a CFD model intended to be used for transonic compressor design purposes. This design model includes a coarse grid using wall functions and mixing planes at interfaces connecting the compressor components. The computations are compared with experimental data from the transonic highly loaded 1.5 stage compressor test case Hulda. Additional comparisons are done with higher complexity CFD models accounting for the rotor-stator interaction. The performance of Hulda has been measured with both a small and a large tip clearance. These two configurations are used to investigate the necessity of resolving the tip clearance gap in the design model. The comparison is presented in terms of the overall performance at two rotational speeds as well as radial distribution of total pressure and total temperature at stations downstream of the rotor. The predictive capability at these speeds is assessed in terms of mass flow, pressure ratio and efficiency. Furthermore, the response of the predicted radial flow distributions with respect to the throttle setting along the two rotational speeds is qualitatively compared with the measurements.
The validation of the small tip clearance test shows that the design model, with or without tip gap modeling, is in good agreement with the measurements at both speeds. As for the large tip clearance test a design model resolving the tip clearance was able to predict trends but the penalty related to the increased tip gap was overestimated compared to the measured.
Tri-Generation Systems Optimization: Comparison of Heuristic and Mixed Integer Linear Programming Approaches
Authors: Bischi Aldo , Campanari Stefano , Castiglioni Alberto , Manzolini Giampaolo , Martelli Emanuele , Silva Paolo , Macchi Ennio 
Published: September 2014

This work compares two optimization approaches for combined cooling, heating and power (CCHP or Tri-generation) energy systems scheduling. Both approaches are developed through dedicated software codes and are based on simulation models capable of evaluating of the best operating strategy (both economically and energy-wise) to run a given trigeneration plant while dealing with time-variable loads and tariffs. The simultaneous use of different prime movers operating in parallel is taken into consideration as well as their part load performance, the influence of ambient temperature and the usage of a heat storage system. Cooling may be generated through absorption chillers or electrically driven compression cycles. One of the models is heuristic and adopts an optimization strategy based on a multi-step approach: it simulates several cases according to a pre-defined number of paths, exploring the most reasonable operational modes and comparing them systematically. The other relies on a mathematical approach, based on a Mixed Integer Linear Programming (MILP) optimization model which has been developed in order to deal with more complex systems without the need of predefining a too large variety of operation paths.
Results of the two models are compared against a test case based on real plant specifications, discussing their performance by the point of view of simulation capabilities, quality and accuracy of the optimization results (in terms of differences in energy and economic performance) and computational resources.
Application of Complex Demodulation for Pseudo-Key-Phasor Recovery From Fast-Response Pressure Measurements
Authors: Ilott Jordan W. , Allan W. D. E. , Asghar Asad 
Published: September 2014

When digitizing the output of fast-response pressure transducers installed on rotating machinery, it is often desirable to use a phase-synchronized method. The mechanical design of many turbomachines, particularly those not originally designed for a research application, can make it difficult to install the physical key-phasor needed to acquire phase-synchronized measurements.
A method of phase-synchronization using a pseudo-key-phasor is presented in this paper. The technique applies complex demodulation to recover a pseudo-key-phasor signal from the blade-passing signal recorded in sampled data. The recovered pseudo-key-phasor is then used to digitally resample the data at a constant phase angle, removing the effect of small rotor speed variations. Example applications of this technique to vibration measurements can be found in the literature; however, examples of application to rotor pressure measurement were not.
The technique has been applied to fast-response pressure measurements taken on the shroud of a high speed centrifugal compressor. It was found that this technique was able to remove the effect of rotor speed variations from data sampled with equal time intervals, making them suitable for phase averaging.
Advanced 0-D Performance Modelling of Counter Rotating Propellers for Multi-Disciplinary Preliminary Design Assessments of Open Rotors
Authors: Bellocq Pablo , Sethi Vishal , Capodanno Stefano , Patin Alexis , Rodriguez Lucas Fernando 
Published: September 2014

Due to their high propulsive efficiency, Counter Rotating Open Rotors (CRORs) have the potential to significantly reduce fuel consumption and emissions relative to conventional high bypass ratio turbofans. However, this novel engine architecture presents many design and operational challenges both at engine and aircraft level.
The assessment of the impact of the main low pressure preliminary design and control parameters of CRORs on mission fuel burn, certification noise and emissions is necessary at preliminary design stages in order to identify optimum design regions. These assessments may also aid the development process when compromises need to be performed as a consequence of design, operational or regulatory constraints.
The required preliminary design simulation tools should ideally be 0-D or 1-D (for computational purposes) and should capture the impact of the independent variation of the main low pressure system design and control variables such as: the number of blades, diameter and rotational speed of each propeller, the spacing between the propellers and the torque ratio of the gearbox or the counter rotating turbine amongst others. From a performance point of view, counter rotating propellers have historically been modelled as single propellers. Such a performance model does not provide the required flexibility for a detailed design and control study.
This paper presents a novel 0-D performance model for Counter Rotating Propellers (CRPs) based on the classical low speed performance model for individual propellers and the interactions between them. This model also incorporates a compressibility correction which is applied to both propellers. The proposed model is verified with publicly available wind tunnel test data from NASA.
The novel 0-D counter rotating propeller performance model is used to produce a performance model of a geared Open Rotor engine with a 10% clipped propeller. This engine model is first used to study the impact of the control of the propellers on the cruise fuel consumption. Subsequently, the engine performance model is integrated in a multi-disciplinary simulation platform to study the impact of the control of the propellers on the certification noise.
The results of this case study show that 1–2% SFC savings at cruise are possible and an optimal control schedule is identified. It is also concluded that significant certification noise reductions are possible through an adequate control of the rotational speeds of the propellers.
A Remotely Operated Aeroelastically Unstable LPT Cascade for Turbomachinery Aeromechanics Education and Training: Remote Flutter Lab
Authors: Monaco Lucio , Vogt Damian M. , Bergmans John , Fransson Torsten H. 
Published: September 2014

The use of advanced pedagogical methodologies in connection with advanced use of modern information technology (ICT) for delivery enables new ways of communicating, of exchanging knowledge, and of learning that are gaining increasing relevance in our society. Remote laboratory exercises offer the possibility to enhance learning for students in different technical areas, especially to the ones not having physical access to laboratory facilities and thus spreading knowledge in a world-wide perspective. A new “Remote Flutter Laboratory” has been developed to introduce aeromechanics engineering students and professionals to aeroelastic phenomena in turbomachinery. The laboratory is world-wide unique in the sense that it allows global access for learners anywhere and anytime to a facility dedicated to what is both a complex and relevant area for gas turbine design and operation. The core of the system consists of an aeroelastically unstable turbine blade row that exhibits self-excited and self-sustained flutter at specific operating conditions. Steady and unsteady blade loading and motion data are simultaneously acquired on five neighboring suspended blades and the whole system allows for a distant-based operation and monitoring of the rig as well as for automatic data-retrieval.
This paper focuses on the development of the “Remote Flutter Laboratory” exercise as a hands-on learning platform for online and distant-based education and training in turbomachinery aeromechanics enabling familiarization with the concept of critical reduced frequency and of flutter phenomena. This laboratory set-up can easily be used “as is” directly by any turbomachinery teacher in the world, free of charge and independent upon time and location with the intended learning outcomes as specified in the lab, but it can also very easily be adapted to other intended learning outcomes that a teacher might want to highlight in a specific course. As such it is also a base for a turbomachinery repository of advanced remote laboratories of global uniqueness and access. The present work documents also the pioneer implementation of the LabSocket System for the remote operation of a wind tunnel test facility from any Internet-enabled computer, tablet or smartphone with no end-user software or plug-in installation.
Axial Bladeless Turbine Suitable for High Supersonic Flows
Authors: Vinha N. , Paniagua G. , Sousa J. , Saracoğlu B. 
Published: September 2014

The development of future propulsion systems, targeting superior efficiencies with ultra compact designs, may rely on the extraction of power from high supersonic flows. In conventional supersonic turbines operating under such extreme flow conditions, the presence of airfoils induces important flow perturbations that originate severe aerodynamic losses while restricting the operating range due to starting issues. These limitations represent design opportunities for bladeless turbines.
The present paper documents for the first time in the open literature an axial bladeless turbine concept, able to extract mechanical power from high supersonic flows through an annular channel. The tangential drag force exerted by the viscous supersonic flow on the rotating inner and outer endwalls produce power, with enhanced simplicity, coolability, manufacturability, and maintainability. Reynolds Averaged Navier-Stokes simulations allowed the detailed evaluation of the aerodynamic performance of the bladeless configuration. The present unconventional axial turbine concept becomes an exceptional design choice when one seeks to extract certain amount of power from supersonic flows with minimum pressure losses.
Experimental and Numerical Performance Characterization of a Transonic Compressor Rotor Operating Behind an Inlet-Guide Vane With Variable Flap Angles
Authors: Hobson Garth V. , Gannon Anthony , Holmes Wendell , McCormick Michael , Capece Vincent 
Published: September 2014

The performance of a modern, forward-swept, transonic compressor rotor has been characterized operating behind an inlet-guide (IGV) vane section that has variable flaps. Testing was performed at both transonic and subsonic rotor tip speeds in an attempt to determine the off-design performance of the rotor at various flap angle settings of the IGV’s. Measurements at moderate flap angles (+20° and −10°) have been determined up to 90% speed (27,000 rpm) of the drive turbine maximum capability. Extremely high flap angles, in excess of +55°, were tested down into the low speed range. For this study the negative flap angles produced counterswirl and the positive flap angles produced swirl in the same direction as the rotation of the rotor.
A rigorous definition of the mass-averaged efficiency is presented. Performance predictions were carried out using ANSYS-CFX on a single passage model consisting of both the IGV and the rotor. Reasonable comparisons with a medium mesh resolution were obatined when compared to experiment.
Numerical Analysis of the Use of Vegetable Oil-Tars Mixtures From Syngas Scrubbing in a Microturbine Combustor
Authors: Laranci Paolo , Bidini Gianni , D’Alessandro Bruno , Fantozzi Francesco 
Published: September 2014

TARs are a mixture of heavy and light hydrocarbons produced from pyrolysis and gasification of biomass and waste, as condensable volatiles in the syngas. Given their relatively low dew point, they are usually removed from syngas to avoid condensation and fouling of engines and equipment. Vegetable oil scrubbing compared to water scrubbing yields oil tar mixtures which is a renewable fuel and may be useful successfully to power a gas turbine. The feasibility of burning TAR, blended vegetable oil, in a combustor of a turbine is investigated. Computational simulations with a CFD software were performed to analyze evaporation and combustion processes of vegetable oil-tars mixture compared with pure vegetable oil and diesel, in terms of residence time, temperature distributions, inlet turbine conditions.
The results show difficulties in evaporation of both vegetable oil and vegetable oil-tar mixture compared to diesel, with consequences in the combustion in terms of temperature distributions and higher NOx emissions. Preheating of vegetable oil and vegetable oil-tar mixture improves their evaporation approaching the results to those of the diesel case.
Rotordynamic Validation of an Ultra High Speed Multistage Centrifugal Compressor Stacked Rotor
Authors: Vannini Giuseppe 
Published: September 2014

The author’s company is currently developing some centrifugal compressor prototypes where the traditional rotor design based on shrunk on wheels and spacers is not suitable due to the specific service requirements (e.g. high peripheral speed or high temperature). For instance the development of a new centrifugal compressor technology aimed to reduce the number of compressor units needed to fulfill a given service is ongoing. In order to accomplish this challenging target a very high rotational speed is required together with special “high pressure ratio” centrifugal stages. The rotor mechanical configuration which has been selected here is a stacked configuration where each centrifugal wheel is integral with the relevant shaft portion. The several shaft portions are mated together through high precision toothed connections (Hirth couplings) and the assembly is secured through a pre-stretched tie-rod.
This rotor stacked configuration is not typical for the most of the industrial centrifugal compressors (a solid shaft with shrink fitted impellers is the common solution, as anticipated) but it is allowed by API standards [1], and it is referenced in Turbomachinery technical literature [2].
The rotordynamics of this special prototype is very challenging since it deals with a seven piece stacked rotor running supercritical. An extensive validation program was required in addition to careful design. This is the specific subject of the present paper which will cover the main following items: validation of the “rotor alone” rotordynamic modelization through comparison with the relevant ping test results, selection of special high speed journal bearings, and overview of the low and high speed balancing process. All these steps together finally allowed the author’s company to fully demonstrate the soundness of this stacked rotor technology for application in High Pressure Ratio Compression service.
Stimulation of Innate Immunity byIn VivoCyclic di-GMP Synthesis Using Adenovirus
Authors: Koestler Benjamin J. , Seregin Sergey S. , Rastall David P. W. , Aldhamen Yasser A. , Godbehere Sarah , Amalfitano Andrea , Waters Christopher M. 
Published: September 2014

ABSTRACTThe bacterial second messenger cyclic di-GMP (c-di-GMP) stimulates inflammation by initiating innate immune cell recruitment and triggering the release of proinflammatory cytokines and chemokines. These properties make c-di-GMP a promising candidate for use as a vaccine adjuvant, and numerous studies have demonstrated that administration of purified c-di-GMP with different antigens increases protection against infection in animal models. Here, we have developed a novel approach to produce c-di-GMP inside host cells as an adjuvant to exploit a host-pathogen interaction and initiate an innate immune response. We have demonstrated that c-di-GMP can be synthesizedin vivoby transducing a diguanylate cyclase (DGC) gene into mammalian cells using an adenovirus serotype 5 (Ad5) vector. Expression of DGC led to the production of c-di-GMPin vitroandin vivo, and this was able to alter proinflammatory gene expression in murine tissues and increase the secretion of numerous cytokines and chemokines when administered to animals. Furthermore, coexpression of DGC modestly increased T-cell responses to aClostridium difficileantigen expressed from an adenovirus vaccine, although no significant differences in antibody titers were observed. This adenovirus c-di-GMP delivery system offers a novel method to administer c-di-GMP as an adjuvant to stimulate innate immunity during vaccination.
Safety and Immunogenicity of Tetanus-Diphtheria-Acellular Pertussis Vaccine Administered to Children 10 or 11 Years of Age
Authors: Marshall Gary S. , Pool Vitali , Greenberg David P. , Johnson David R. , Sheng Xiaohua , Decker Michael D. 
Published: September 2014

ABSTRACTBoosting immunity to tetanus, diphtheria, and pertussis through the use of Tdap vaccines is routinely recommended at 11 to 12 years of age; some states, however, require Tdap for entry into middle school, which may begin at 10 years of age. This study was conducted to determine whether Tdap5 (Adacel), which is licensed for use in children beginning at 11 years of age, is as safe and immunogenic in 10-year-olds as it is in 11-year-olds. Children who had received 5 previous doses of any diphtheria-tetanus-acellular pertussis (DTaP) vaccine were enrolled in a phase IV clinical trial; 646 10-year-olds and 645 11-year-olds completed the study, which involved a single intramuscular dose of Tdap5 along with pre- and postvaccination serologies. Postvaccination geometric mean concentrations (GMCs) of antibody to pertussis antigens (pertussis toxoid, filamentous hemagglutinin, pertactin, and fimbria types 2 and 3) of 10-year-olds were noninferior to those of 11-year-olds, as were booster response rates for all pertussis antibodies, except for those to fimbrial antigens (94% and 97%, respectively). Seroprotection rates among 10-year-olds for tetanus and diphtheria were noninferior to those in 11-year-olds. Rates of injection site reactions, solicited systemic reactions, and unsolicited adverse events, adverse reactions, and serious adverse events were similar in the two groups. These data support the conclusion that Tdap5 is safe and immunogenic in 10-year-olds. (This study has been registered at ClinicalTrials.gov under registration no. NCT01311557.)
Multilocus Sequence Typing (MLST) and Whole-Genome MLST of Campylobacter jejuni Isolates from Human Infections in Three Districts during a Seasonal Peak in Finland
Authors: Kovanen Sara M. , Kivistö Rauni I. , Rossi Mirko , Schott Thomas , Kärkkäinen Ulla-Maija , Tuuminen Tamara , Uksila Jaakko , Rautelin Hilpi , Hänninen Marja-Liisa 
Published: September 2014

ABSTRACT

A total of 95 human
Campylobacter jejuni
isolates acquired from domestic infections and collected from three districts in Finland during the seasonal peak (June to September) in 2012 were analyzed by PCR-based multilocus sequence typing (MLST) and by whole-genome sequencing (WGS). Four predominant sequence types (STs) were detected among the isolates: ST-45 (21%) and ST-230 (14%, ST-45 clonal complex [CC]), ST-267 (21%, ST-283 CC), and ST-677 (19%, ST-677 CC). In districts 1 and 3, most of the infections occurred from early July to the middle of August, with a peak at weeks 29 to 31, but in district 2, the infections were dispersed more evenly throughout 3 months (June to August). WGS data were used for further whole-genome MLST (wgMLST) analyses of the isolates representing the four common STs. Shared loci of the isolates within each ST were analyzed as distance matrices of allelic profiles by the neighbor-net algorithm. The highest allelic variations (>400 different alleles) were detected between different clusters of ST-45 isolates (1,121 shared loci), while ST-230 (1,264 shared loci), ST-677 (1,169 shared loci), and ST-267 isolates (1,217 shared loci) were less diverse with the clusters differing by <40 alleles. Closely related isolates showing no allelic variation (subclusters) were detected among all four major STs. In some cases, they originated from different districts, suggesting that isolates can be epidemiologically connected and may have the same infection source despite being originally identified as sporadic infections.