bluuebunny/crossref_metadata_2025_split huggingface dataset:
LES for the Evaluation of Acoustic Damping of Effusion Plates
Authors: Andreini A. , Bianchini C. , Facchini B. , Peschiulli A. , Vitale I. 
Published: July 2013

Effusion cooled liners, commonly used in gas turbine combustion chambers to reduce wall temperature, may also help reducing the propagation of pressure fluctuations due to thermoacoustic instabilities.
Large Eddy Simulations were conducted to accurately model the flow field and the acoustic response of effusion plates subject to a mean bias flow under external sinusoidal forcing. Even though existing lower order computational models showed good predicting capabilities, it is interesting to verify directly the influence of those parameters such as the staggered arrangement, the hole inclination, the presence of a grazing flow and the level of bias flow, which are not fully included in those models.
A first bi-periodic single hole configuration with normal acoustic forcing was selected to investigate the acousting behavior with varying inclination angle, bias and grazing flow. 90° and 30° perforations were simulated for bias flow Mach number in the range 0.05–0.1 and grazing flow between 0 and 0.08. Those conditions were chosen to expand the knowledge of acoustic properties towards actual liners working conditions. A second more computationally expensive set-up, including 4 inclined holes at 30°, focused on the damping of parallel to the plate waves.
Details of the computational methods implemented in the general purpose open-source unstructured CFD code OpenFOAM® exploited to conduct this analysis are reported together with an analysis of the results obtained from the acoustic computations both regarding the flow field generated and the absorption and energy dissipation coefficient.
LES-Based Study of the Influence of Thermal Boundary Condition and Combustor Confinement on Premix Flame Transfer Functions
Authors: Tay-Wo-Chong Luis , Polifke Wolfgang 
Published: July 2013

The influence of thermal boundary condition at the combustor wall and combustor confinement on the dynamic flame response of a perfectly premixed axial swirl burner is investigated. Large Eddy Simulations are carried out using the Dynamically Thickened Flame combustion model. Then, system identification methods are used to determine the flame transfer function (FTF) from the computed time series data.
Two configurations are compared against a reference case with 90 mm × 90 mm combustor cross section and nonadiabatic walls: 1) combustor cross section similar to the reference case with adiabatic combustor walls, and 2) different confinement (160 mm × 160 mm) with nonadiabatic walls. It is found that combustor confinement and thermal boundary conditions have a noticeable influence on the flame response due to differences in flame shape and flow field. In particular the FTF computed with adiabatic wall boundary condition, which produces a flame with significant heat release in both shear layers, differs significantly from the FTF with nonadiabatic walls, where the flame stabilizes only in the inner shear layer. The observed differences in flow field and flame shape are discussed in relation to the unit impulse response of the flame. The impact of the differences in FTF on stability limits is analyzed with a low-order thermoacoustic model.
Extension of Fuel Flexibility in the Siemens Dry Low Emissions SGT-300-1S to Cover a Wobbe Index Range of 15 to 49 MJ/m3
Authors: Liu Kexin , Alexander Varkey , Sanderson Victoria , Bulat Ghenadie 
Published: July 2013

The extension of gas fuel flexibility in the Siemens SGT-300 single shaft (SGT-300-1S) is reported in this paper. A successful development programme has increased the capability of the Siemens Industrial Turbomachinery, Lincoln (SITL) dry low emissions (DLE) burner configuration to a fuel range covering a Wobbe Index (WI) from 15 to 49 MJ/m3.
The standard SGT-300-1S SITL DLE combustion hardware allowed for gas and liquid fuels within a specified range typically associated with natural gas and diesel, respectively. Field operation of the standard production SGT-300-1S has confirmed the reliable operation with an extension to the fuels range to include processed land fill gas (PLG) from 32 to 49 MJ/m3.
The further extension of the fuel range for the SGT-300-1S SITL DLE combustion system was achieved through high pressure testing of a single combustion system at engine operating conditions. The rig facility allowed for the actual fuel type to be tested using a mixing plant. The variations in fuel heating value were achieved by blending natural gas with diluent CO2 and/or N2. Various diagnostics were used to assess the performance of the combustion system including measurement of combustion dynamics, temperature, fuel supply pressure and emissions of NOx, CO and unburned hydrocarbon (UHC).
The results of the testing showed that the standard production burner can operate for a fuel with WI as low as 23 MJ/m3 which corresponds to 35% CO2 (in volume) in the fuel. This range can be extended to 15 MJ/m3 (54.5% CO2 in the fuel) with only minor modification, to control losses through the burner and to maintain similar fuel injection characteristics.
The SITL DLE combustion system is able to cover a WI range of 15 to 49 MJ/m3 in two configurations. The results of testing showed a lowering in WI, from diluting with CO2 and/or N2, a benefit in NOx reduction is observed. This decrease in WI may lead to an increased requirement in fuel supply pressure.
EZEE®: A High Power Density Modulating FLOX® Combustor
Authors: Schütz H. , Lammel O. , Schmitz G. , Rödiger T. , Aigner M. 
Published: July 2013

Presented in this paper is a novel gas turbine combustor: EZEE® based upon the FLOX® combustion technology. The specific feature of this combustor is the ability to modulate the power density PA for natural gas (NG) combustion on a high thermal power level between PA = 13.3 MW/m2/bar in the main load and PA = 7.9 MW/m2/bar in the part load operation. The operational range for the global air to fuel excess ratio λ is between λ = 1.6 and λ = 2.7 corresponding to adiabatic flame temperatures between Tad ≈ 2000 K and 1500 K, respectively. The air preheating temperature is 673 K and the pressure level is 8 bar. The inspected operational range satisfies the demands of modern gas turbine combustors.
The idea of EZEE® is to manipulate the flame position by radial staging of two independent fuel supplies in order to prevent flame extinction with increasing λ. The combustor is developed with the aid of computational tools and accordingly manufactured and experimentally investigated at the DLR test facilities. It is demonstrated that the combustion is complete and stable and that the pollutant emission is low. Presented are first results of our investigations that show the usefulness and the potential of the concept. However, it is also shown that additional fine-tuning is still necessary to further reduce the pollutant emissions.
Combustion Characteristics and NOX Emission of Hydrogen-Rich Fuel Gases at Gas Turbine Relevant Conditions
Authors: Lin Y.-C. , Daniele S. , Jansohn P. , Boulouchos K. 
Published: July 2013

In this paper, characteristics of turbulent combustion and NOx emission for high hydrogen-content fuel gases (H2 > 70 vol. %; “hydrogen-rich”) are addressed. An experimental investigation is performed in a perfectly-premixed axial-dump combustor under gas turbine relevant conditions. Fundamental features of turbulent combustion for these mixtures are evaluated based on OH-PLIF diagnostics. On the other hand, NOx emissions are measured with an exhaust gas sampling probe positioned downstream the combustor outlet.
Compared to syngas mixtures (H2 + CO), the operational limits for hydrogen-rich fuel gases are found to occur at even leaner conditions concerning flashback phenomena. With respect to effects of operating pressure, a strongly reduced operational envelope is observed at elevated pressure. Only with decreasing the preheat temperature a viable approach to further extend the operational range is seen. Evaluation of the averaged turbulent flame shape shows that the profile of the flame front is generally approaching that of an ideal cone. Thus a simplified approach for estimating the turbulent flame speed via the location of the flame tip alone can be applied.
The level of NOx emission for the hydrogen-rich fuel mixtures is generally above that of syngas mixtures, which exhibit already higher NOx emission values than natural gas. Distinct chemical kinetic features are found specifically at elevated pressure. While the pressure effects are weak for syngas, a non-monotonic behavior is observed for the hydrogen-rich fuels. Reaction path analysis is performed to complement and provide more insight to the findings from the measurements. From chemical kinetic calculations a distinct shift in NOx formation pathways (thermal NOx vs. NOx through N2O/NNH reaction channels) can be observed for the different fuel mixtures at different pressure levels.
Studying the Stabilization Dynamics of Swirling Partially Premixed Flames by Proper Orthogonal Decomposition
Authors: Duwig Christophe , Ducruix Sébastien , Veynante Denis 
Published: July 2013

Environmental regulations are continuously pushing lower emissions with an impact on the combustion process in gas turbines (GT). As a consequence, GT combustors operate in very lean regimes (i.e. at relatively low temperature) to reduce NOx formation. Unfortunately, stabilization becomes a challenge for these lean premixed flames. The extremely unsteady dynamics of swirl stabilized flames present crucial issues and this investigation aims at understanding the interaction of swirl stabilization with large coherent fluctuations inherent to vortex breakdown.
The investigation utilizes a simplified cylindrical model combustor consisting of a premixing tube discharging in a larger combustion chamber. Fuel and swirling air are injected separately in the mixing tube so that a partially premixed swirling jet encounters vortex breakdown and allows the partially premixed flame to stabilize. The aforementioned extreme sensitivity of lean partially premixed flames challenges any investigation either for measuring, simulating or post-processing the case of interest.
In this paper, the problem is addressed using large eddy simulation (LES) and planar laser induced fluorescence. The LES data are used to follow the fuel air/mixing as well as the fuel combustion evidencing large-scale dynamics. These dynamics are further investigated using Proper Orthogonal Decomposition to identify the role of the premixing stage and of the Precessing Vortex Core in the flame behaviour.
Modelling Flame-Generated Noise in a Partially Premixed, Bluff Body Stabilized Model Combustor
Authors: Tufano Saverio , Stopford Phil , Roman Casado J. C. , Kok J. B. W. 
Published: July 2013

Numerical simulation using Computational Fluid Dynamics (CFD) has become increasingly important as a tool to predict the potential occurrence of combustion instabilities in gas turbine combustors operating in lean premixed mode. Within the EU-funded Marie Curie project, LIMOUSINE (Limit cycles of thermo-acoustic oscillations in gas turbine combustors), a model test burner has been built in order to have reproducible experimental results for model validation. The burner consists of a Rijke tube of rectangular section having a flame-stabilizing wedge at about 1/4 of its length. Fuel and air supplies were carefully designed to give closed end acoustic inlet boundary conditions while the atmospheric outlet representing an acoustically open end. A transient CFD simulation of the turbulent, partially premixed, bluff body stabilized combusting flow has been carried out for the LIMOUSINE burner using ANSYS CFX commercial software. A 2-D section has been modelled by means of the scale resolving turbulence model, Scale-Adaptive Simulation (SAS), and a two-step Eddy Dissipation combustion model.
Experiments were performed on the LIMOUSINE model burner to measure the dynamic variation of pressure and temperature. Results were obtained for several cases with power input ranging from 40 to 60 kW and air factors between 1.2 and 1.8.
The CFD results are found to be in good agreement with experiments: the flame is predicted to stabilise on the bluff body in the fluid recirculation zone; resonance frequencies are found to change depending on power and air excess ratio and have a good agreement with experimental results and analytical values; pressure oscillations are consistent with pipe acoustic modes.
Investigation of a Flame Anchored in Crossflow Stream of Vitiated Air at Elevated Pressures
Authors: Galeazzo Flavio Cesar Cunha , Prathap Chockalingam , Kern Matthias , Habisreuther Peter , Zarzalis Nikolaos , Beck Christian , Krebs Werner , Wegner Bernhard 
Published: July 2013

The objective was to study the effect of equivalence ratio of secondary stage combustible mixture injected into the cross flow stream of vitiated air in a two staged combustion system on the characteristics of the secondary stage combustion zone. The primary cylindrical combustor equipped with low swirl air blast nozzle operating with kerosene generates vitiated air. A methane injector was flush mounted to the inner surface of the secondary combustor. It was used to inject the premixed methane-air mixtures perpendicular into the crossflow of vitiated air. An optical, double shell, secondary combustor with three optical windows on its outer shell was used to image the secondary stage flames. The inner shell was a quadratic fused quartz tube which acts as a thermal barrier and the outer thick quartz windows mounted in the quadratic stainless steel chamber withholds the pressure. Chemiluminescence imaging technique equipped with ICCD camera was used to image the OH* emissions of the secondary stage flame.
The vitiated air was generated at 2 bar and 1700 K. The velocity of the vitiated air in the secondary combustor was 57 m/s. A premixed methane air mixture was injected into the cross flow stream of vitiated air. The momentum flux ratio between the jet and the vitiated air was maintained at 1.4. The equivalence ratio of the premixed methane-air mixture was varied from 0.5 to 1.0. As the equivalence ratio of the secondary stage combustible mixture moves towards stoichiometric condition, the secondary stage combustion zone becomes compact and also the distance between the burner and the combustion zone decreases.
The turbulent flame stabilized in the secondary combustor exhibited large scale structures and other unsteady phenomena that require time-resolved computational methods. Large eddy simulations (LES) are well suited to the calculation of such complex flows. The flame was embedded in a strong turbulent flow where auto-ignition and quenching are important, which poses a significant challenge for the reaction modeling. The presumed JPDF turbulent reaction model, which has been proven to be a reliable model for these challenging conditions, was successfully coupled with the LES simulation. The qualitative agreement between the results of simulations and measurements was quite satisfactory.
Characteristics of Deposits in Gas Turbine Combustion Chambers Using Synthetic and Conventional Jet Fuels
Authors: Pucher Greg , Allan William , Poitras Pierre 
Published: July 2013

The synthetic fuel industry is poised to experience large scale growth and profoundly affect current aviation fuel infrastructure. New candidate technologies, such as Camelina oil-derived synthetic fuel have been demonstrated to not only provide satisfactory quasi drop-in characteristics for conventional fuels, but in life cycle analysis studies have also been shown to potentially offer positive improvements relative to conventional feedstocks with respect to economic, environmental, and land use considerations.
As part of a multi-year study at the Royal Military College of Canada to evaluate combustion related parameters of fuel additives and alternative fuels for gas turbine applications, a Camelina-derived synthetic fuel blend was assessed to determine potential combustion related benefits as compared to conventional and other synthetic blends. The Combustion Chamber Sector Rig (CCSR) which houses a Rolls Royce T-56-A-15 combustion section, was utilized for the evaluation of emissions and deposits. Following combustion testing, several combustion system components, including the combustion chamber, fuel nozzle and igniter plug were analyzed for relative levels of deposit build-up. As with other Fischer Tropsch derived synthetic fuels, there were positive benefits found with Camelina blends in terms of emissions performance and deposit production tendencies.
Nuclear Pore Scaffold Structure Analyzed by Super-Resolution Microscopy and Particle Averaging
Authors: Szymborska Anna , de Marco Alex , Daigle Nathalie , Cordes Volker C. , Briggs John A. G. , Ellenberg Jan 
Published: July 2013

Poring Over the Nuclear PoreThe nuclear pore is a macromolecular complex that traverses the paired membranes of the nuclear envelope through which a variety of nuclear protein and RNA cargoes must traffic.Szymborskaet al.(p.655, published online 11 July) combined super-resolution microscopy with single-particle averaging to localize the proteins that make up the structural scaffold of the nuclear pore complex with a precision well below one nanometer. These molecular positional constraints clarified contradictory models for the structure of the nuclear pore and demonstrate that the structural organization of protein complexes can be studied by light microscopy in situ in whole cells.
Genome Sequence of “
Candidatus
Methanomassiliicoccus intestinalis” Issoire-Mx1, a Third
Thermoplasmatales
-Related Methanogenic Archaeon from Human Feces
Authors: Borrel Guillaume , Harris Hugh M. B. , Parisot Nicolas , Gaci Nadia , Tottey William , Mihajlovski Agnès , Deane Jennifer , Gribaldo Simonetta , Bardot Olivier , Peyretaillade Eric , Peyret Pierre , O'Toole Paul W. , Brugère Jean-François 
Published: July 2013

ABSTRACT

“
Candidatus
Methanomassiliicoccus intestinalis” Issoire-Mx1 is a methanogenic archaeon found in the human gut and is a representative of the novel order of methanogens related to
Thermoplasmatales
. Its complete genome sequence is presented here.
Genome Sequences of Four Yersinia enterocolitica Bioserotype 4/O:3 Isolates from Mammals
Authors: Garzetti Debora , Heesemann Jürgen , Rakin Alexander 
Published: July 2013

ABSTRACT

We report here the complete genome sequences of four European
Yersinia enterocolitica
mammalian isolates of bioserotype 4/O:3. The genomes have an average size of 4.50 Mb, a G+C content of 47%, and between 4,231 and 4,330 coding sequences (CDSs). No relevant differences were detected by genome comparison between mammalian and human isolates.
Draft Genome Sequence of a Highly Flagellated, Fast-Swimming Archaeon, Methanocaldococcus villosus Strain KIN24-T80 (DSM 22612)
Authors: Thennarasu Sugumar , Polireddy Dineshreddy , Antony Aju , Yada Madhava Rao , Algarawi Sami , Sivakumar Neelamegam 
Published: July 2013

ABSTRACT

We report the draft genome sequence of a hyperthermophilic
Methanocaldococcus villosus
strain, KIN24-T80. The gene associated with its heavy flagellum formation was annotated in the 1.2-Mb draft genome sequence, and this strain may be a good model system to study the extensive functional role of flagella and their fast motor activity.
Draft Genome Sequence of Strain CBD-635, a Methicillin-Resistant Staphylococcus aureus USA100 Isolate
Authors: Carroll Ronan K. , Burda Whittney N. , Roberts Jill C. , Peak Kealy K. , Cannons Andrew C. , Shaw Lindsey N. 
Published: July 2013

ABSTRACT

We present the draft genome sequence of methicillin-resistant
Staphylococcus aureus
strain CBD-635, from the USA100 lineage. This is a sepsis isolate obtained from Tampa General Hospital. This strain is
spa
type t003 and multilocus sequence typing (MLST) type ST5, and it has been used by our group in the study of novel antimicrobial chemotherapeutics.
Perioperative medication management: expanding the role of the preadmission clinic pharmacist in a single centre, randomised controlled trial of collaborative prescribing
Authors: Hale A R , Coombes I D , Stokes J , McDougall D , Whitfield K , Maycock E , Nissen L 
Published: July 2013

ObjectivesCurrent evidence to support non-medical prescribing is predominantly qualitative, with little evaluation of accuracy, safety and appropriateness. Our aim was to evaluate a new model of service for the Australia healthcare system, of inpatient medication prescribing by a pharmacist in an elective surgery preadmission clinic (PAC) against usual care, using an endorsed performance framework.DesignSingle centre, randomised controlled, two-arm trial.SettingElective surgery PAC in a Brisbane-based tertiary hospital.Participants400 adults scheduled for elective surgery were randomised to intervention or control.InterventionA pharmacist generated the inpatient medication chart to reflect the patient's regular medication, made a plan for medication perioperatively and prescribed venous thromboembolism (VTE) prophylaxis. In the control arm, the medication chart was generated by the Resident Medical Officers.Outcome measuresPrimary outcome was frequency of omissions and prescribing errors when compared against the medication history. The clinical significance of omissions was also analysed. Secondary outcome was appropriateness of VTE prophylaxis prescribing.ResultsThere were significantly less unintended omissions of medications: 11 of 887 (1.2%) intervention orders compared with 383 of 1217 (31.5%) control (p<0.001). There were significantly less prescribing errors involving selection of drug, dose or frequency: 2 in 857 (0.2%) intervention orders compared with 51 in 807 (6.3%) control (p<0.001). Orders with at least one component of the prescription missing, incorrect or unclear occurred in 208 of 904 (23%) intervention orders and 445 of 1034 (43%) controls (p<0.001). VTE prophylaxis on admission to the ward was appropriate in 93% of intervention patients and 90% controls (p=0.29).ConclusionsMedication charts in the intervention arm contained fewer clinically significant omissions, and prescribing errors, when compared with controls. There was no difference in appropriateness of VTE prophylaxis on admission between the two groups.Trial RegistrationRegistered with ANZCTR—ACTR Number ACTRN12609000426280