bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spray Characteristics of an Airblast-Simplex Nozzle for Liquid-Fueled Gas Turbine Combustors
Authors: Ibrahim Mounir , Sanders Terry , Yarwood Debra , Moawed Mohammed , Steinthorsson Erlendur , Benjamin Michael 
Published: December 2014

Experimental and computational (CFD) investigations were conducted on an Airblast Simplex (ABS) nozzle. A Phase Doppler Particle Analyzer (PDPA) was used to study the main characteristics of the nozzle. Water was used as the test liquid with pressure drops of 68.9, 172.3 & 689 kPa, while the air pressure drops were 2.49 & 34.5 kPa. PDPA data were obtained at three different axial distances from the nozzle exit (x = 2.5 (or 7), 17 & 40 mm). In the numerical simulations, the three-dimensional flow field for both air and liquid was computed. The combination of detailed experimental measurements and CFD provided excellent insight into the physics of the atomizer. The three-dimensional CFD simulation showed distinct jets originating the air swirler and secondary flows that cause multiple peaks in number density, volume flux and velocity distributions. The jets suggest why asymmetric distributions are common in sprays. The jetting effect from the swirler vanes emphasizes the importance of swirler and airflow design on the performance of a spray nozzle. The discrete jetting effect is not visually observable, nor is it easily measured using PDPA.
The ABS nozzle examined has several distinct advantages over a pressure swirl atomizer, including, (1) the distinct sheet from the hollow cone spray is dispersed within 17 mm in all cases studied herein, and (2) the spray volume does not change significantly with increasing air or liquid pressure drop. Therefore, careful design of ABS nozzle results in a spray with nearly constant spray volume and SMD over a wide range of Air/Liquid Ratios.
Detection of Precursor Waves Announcing Stall in Two 3-Stage Axial Compressors
Authors: Grauer F. , Volgmann W. , Stoff H. , Breuer T. 
Published: December 2014

Rotating stall and surge limit the operating range of a compressor towards low throughflow and high pressure in the performance map. Usually a safety margin must be observed to prevent the compressor from entering unintentionally aerodynamic instabilities. As the range of highest performance and efficiency lies in the vicinity of the stability limit, efforts concentrate on recognizing imminent onset of unstable operation prior to its occurrence.
The present investigation centers on means of detecting information about onsetting instability from signals of pressure fluctuations in two transonic medium-pressure axial compressors of 3 stages. Fourier-transform-methods as well as artificial neural networks are applied for the data reduction of the time-dependent pressure signals. The methods of investigation presented here detected stall precursors announcing the onset of instability. Some of them seem appropriate to be used in connection with active stall control.
Ceramic Stationary Gas Turbine Development Program — Design and Test of a First Stage Ceramic Nozzle
Authors: Faulder Leslie , McClain John , Edwards Bryan , Parthasarathy Vijay 
Published: December 2014

The goal of the Ceramic Stationary Gas Turbine(CSGT) Development Program, under the sponsorship of the United States Department of Energy (DOE), Office of Industrial Technologies (OIT), is to improve the performance (fuel efficiency, output power, exhaust emissions) of stationary gas turbines in cogeneration through the selective replacement of hot section components with ceramic parts. Phase II of this program includes detailed engine and component design, procurement and testing. This paper will review the design and test of the first stage ceramic nozzle for the Centaur 50S engine. For this test an uncooled monolithic ceramic nozzle made from SN-88 silicon nitride(NGK Insulators Ltd.) was used.
A major challenge in the successful introduction of ceramic parts into a gas turbine is the design of the interface between the ceramic parts and metallic components. The design and attachment of the ceramic nozzle was greatly influenced by these considerations. Metallic components in the stationary structure of the turbine have been added or redesigned to retrofit the ceramic nozzle into the all metallic Centaur 50S engine.
This paper will also discuss special handling and assembly techniques used to install the ceramic nozzle into the engine. Trial assemblies were used in the engine build process, this proved most beneficial in identifying problems and reducing the risk of damage to the ceramic nozzles. Assembly techniques were designed to reduce assembly loads and to eliminate blind assemblies.
Before installing any ceramic nozzles into the engine they were first required to successfully pass both mechanical and thermal proof tests. Details of these proof tests and the final full load engine test will be described in this paper. The engine test was run at a turbine rotor inlet temperature(TRIT) of 1010°C. Total number of engine starts was six, and the total run time was approximately 10 hours.
Further Development of the Siemens LPP Hybrid Burner
Authors: Hoffmann Stefan , Judith Hans , Holm Carl-Gunnar 
Published: December 2014

Lean premixed (LP) combustion is a proven concept for NOx-reduction in gas turbine systems. Lean premixed liquid fuel systems, also known as LPP (lean premixed prevaporized) systems, however, are more complex, as the fuel has to be atomized, evaporated and premixed prior to combustion and there is a higher risk of autoignition and coking.
The Siemens LPP Hybrid burner, which was introduced into the Halmstadvaerket gas turbine of Sydkraft AB in Sweden in 1993, has since proven its reliability. As the primary design criteria have been maximum reliability and security against flashback, it still has a considerable potential for NOx-Emissions reduction.
The objectives of this paper are to summarize the activities connected with the further development of the LPP Hybrid burner based on the Halmstadvaerket operation experience. These include the introduction of the LPP burner into a new machine generation with ring combustors as well as investigations into the two phase flow phenomena inside the burner.
When the Model VX4.3A gas turbine family was introduced, the LPP Hybrid burner had to be scaled down to fit the different machine sizes. The paper reports on the development steps and first operation experiences with the LPP Hybrid burner system in HBR-combustor machines.
In a concluding chapter, the paper outlines the next steps in the LPP development program. These include further experimental and numerical studies which are partly conducted in a co-operation between Sydkraft AB and Siemens AG.
Ceramic Gas Turbine Technology Development
Authors: Easley Michael L. , Schenk Bjoern , Cai Hongda 
Published: December 2014

AlliedSignal Engines is addressing critical concerns slowing commercialization of structural ceramics in gas turbines. The AlliedSignal 331-200[CT] APU test bed features ceramic first-stage nozzles and blades. Fabrication of ceramic components provides manufacturing process demonstration scale-up to minimum levels for commercial viability. Endurance tests and field testing in commercial aircraft will demonstrate component reliability.
Manufacturing scale-up activities showed significant progress in 1997. Subcontractors AlliedSignal Ceramic Components (CC, Torrance, CA) and Kyocera Industrial Ceramics Corporation (KICC, Vancouver, WA), transitioned process refinements to demonstration. CC initiated trial production of 100 nozzles/month. These suppliers are also developing fixed processes to fabricate ceramic integrally-bladed turbine rotors (“blisks”).
Ceramic design technology advanced with carbon particle impact testing supporting impact model verification, and 300 hours successful engine testing of longer-life inserted blade attachment compliant layers. Ceramic turbine nozzles were readied for planned field demonstrations with 473 hours of engine testing.
This work was funded as part of the Turbine Engine Technologies Program by the DoE Office of Transportation Technologies under Contract No. DE-AC02-96EE50454.
Adaptation of the Stuttgart University Altitude Test Facility for BR700 Core Demonstrator Engine Tests
Authors: Schmidt Klaus-J. , Merten Ralph , Menrath Martin , Braig Wolfgang 
Published: December 2014

Within the initiative of the German Aerospace Research Programme - Engine 3E Project - the altitude test facility at the University of Stuttgart has been successfully adapted and commissioned as a new facility for BR700 core demonstrator engine tests.
A core demonstrator consists of high pressure components of the engine. The low pressure system, which is not part of the core engine, must be simulated by the test facility itself. This paper describes the technical concept of the computer control system and the procedure in which the core demonstrator, altitude test facility and sub-systems were integrated and tested. The concept consists of:
1. A Master Control System to run the measurement process and to control and monitor the overall test activity.
2. A modified FADEC of a BR700-710 engine with modified control laws to control the core demonstrator.
3. A Facility Controller to control the air conditioning process of the facility-air station and to provide the required core inlet pressure and temperature profiles for the running of the core demonstrator.
4. Various sub-systems for supplying the core engine with lubricating oil, fuel, etc.
The test programme was focussed on evaluating the interaction between the various control systems. It was found that the test facility fulfills the requirements of providing the transient pressure and temperature profiles for rapid accelerations and decelerations during core engine test.
Evolution of the Solar Turbines Titan 130 Industrial Gas Turbine
Authors: Rocha G. , Etheridge C. J. 
Published: December 2014

Solar Turbines Incorporated has extended the size-range of its’ turbomachinery products with development of the Titan™ 130 industrial gas turbine. The 13 megawatt-class, simple-cycle machine is designed to produce 13.3 MW (17,800 hp) output power with a thermal efficiency of 34.5% at ISO inlet conditions with no losses. The larger gas turbine is intended to meet increasing market demands in gas compression and mechanical pump-drive industrial applications.
The overall engine design is based on aerodynamic-scale of the 7 MW-class Taurus™ 70 gas turbine with similar operating cycle parameters. The engine configuration consists of hardware that has been scaled from the Taurus 70 and components that are common with the Mars® gas turbine. As with the Taurus 70 and Mars products, the Titan 130 gas turbine features a low emissions combustion system based on Solar’s proven dry, lean-premix, pollution-prevention technology. The enhance system is capable of reducing pollutant emissions over an extended operating range from part-load to full-load conditions.
This paper discusses the evolutionary design of the Titan 130 from the Taurus 70 and Mars gas turbines products. Descriptions of the basic configuration, component scaling techniques and modular design construction are presented.
Leakage Effects in the Rotor Tip-Clearance Region of a Multistage Axial Compressor: Part 1 — Innovative Experiments
Authors: Ivey P. C. , Swoboda M. 
Published: December 2014

This paper describes work conducted as part of an experimental and numerical study of leakage effects by numerous Research and Industrial partners. For clarity it is presented in two parts. Part 1 presents measurements of tip-clearance flow for a 3rd stage rotor embedded in a four stage low-speed research compressor. The measurements are innovative and comprise measurements in the rotor relative frame of reference and 3D Laser time-of-flight Anemometry. Both techniques are relevant for improved understanding of multistage compressor flow dynamics and consequently, validated multistage CFD simulations.
In part 2 of this paper (see Politis et al 1997b) it is shown that downstream of the rotor passage the location and size of a tip-clearance vortex, identified from both independent measurement techniques in Part 1, is in good agreement with 3D solutions of the Navier-Stokes equations modelling this compressor. These 3D numerical solutions reveal the tip-clearance flow structure using a multiblock grid technique.
Effect of Asparagine Substitutions in the YXN Loop of a Class C β-Lactamase of Acinetobacter baumannii on Substrate and Inhibitor Kinetics
Authors: Skalweit Marion J. , Li Mei , Taracila Magda A. 
Published: December 2014

ABSTRACT

Class C cephalosporinases are a growing threat, and inhibitors of these enzymes are currently unavailable. Studies exploring the YXN loop asparagine in the
Escherichia coli
AmpC, P99, and CMY-2 enzymes have suggested that interactions between C6′ or C7′ substituents on penicillins or cephalosporins and this Asn are important in determining substrate specificity and enzymatic stability. We sought to characterize the YXN loop asparagine in the clinically important ADC-7 class C β-lactamase of
Acinetobacter baumannii
. Mutagenesis at the N148 position in ADC-7 yields functional mutants (N152G, -S, -T, -Q, -A, and -C) that retain cephalosporinase activity. Using standard assays, we show that N148G, -S, and -T variants possess good catalytic activity toward cefoxitin and ceftaroline but that cefepime is a poor substrate. Because N152 variants of CMY-2, another class C β-lactamase, are more readily inhibited by tazobactam due to higher rates of inactivation, we also tested if the N148 substitutions in ADC-7 would affect inactivation by sulfone inhibitors, sulbactam and tazobactam, class A β-lactamase, and
A. baumannii
penicillin-binding protein (PBP) inhibitors with
in vitro
activity against ADC-7. The 50% inhibitory concentrations (IC
50
s) for tazobactam and sulbactam were improved, with 7-fold and 2-fold reductions, respectively, for the N148S variant. A homology model of the N148S ADC-7 enzyme in a Michaelis-Menten complex with tazobactam showed a loss of interaction between N148 and the sulfone moiety of the inhibitor. We postulate that this may result in more-rapid secondary ring opening of the inhibitor, as the unbound sulfone is an excellent leaving group, leading to more-rapid formation of the stable linearized inhibitor.
Molecular Diagnosis of Fluoroquinolone Resistance in Mycobacterium tuberculosis
Authors: Bernard Christine , Veziris Nicolas , Brossier Florence , Sougakoff Wladimir , Jarlier Vincent , Robert Jérôme , Aubry Alexandra 
Published: December 2014

ABSTRACT

As a consequence of the use of fluoroquinolones (FQ), resistance to FQ has emerged, leading to cases of nearly untreatable and extensively drug-resistant tuberculosis. Mutations in DNA gyrase represent the main mechanism of FQ resistance. A full understanding of the pattern of mutations found in FQ-resistant (FQ
r
) clinical isolates, and of their proportions, is crucial for improving molecular methods for the detection of FQ resistance in
Mycobacterium tuberculosis
. In this study, we reviewed the detection of FQ resistance in isolates addressed to the French National Reference Center for Mycobacteria from 2007 to 2012, with the aim of evaluating the performance of PCR sequencing in a real-life context.
gyrA
and
gyrB
sequencing, performed prospectively on
M. tuberculosis
clinical isolates, was compared for FQ susceptibility to 2 mg/liter ofloxacin by the reference proportion method. A total of 605 isolates, of which 50% were multidrug resistant, were analyzed. The increase in FQ
r
strains among multidrug-resistant (MDR) strains during the time of the study was alarming (8% to 30%). The majority (78%) of the isolates with
gyrA
mutations were FQ
r
, whereas only 36% of those with
gyrB
mutations were FQ
r
. Only 12% of the FQ
r
isolates had a single mutation in
gyrB
. Combined
gyrA
and
gyrB
sequencing led to >93% sensitivity for detecting resistance. The analysis of the four false-positive and the five false-negative results of
gyrA
and
gyrB
sequencing illustrated the actual limitations of the reference proportion method. Our data emphasize the need for combined
gyrA
and
gyrB
sequencing in the investigation of FQ susceptibility in
M. tuberculosis
and challenge the validity of the current phenotype-based approach as the diagnostic gold standard for determining FQ resistance.
Protection against Klebsiella pneumoniae Using Lithium Chloride in an Intragastric Infection Model
Authors: Tsao Nina , Kuo Chih-Feng , Chiu Ching-Chen , Lin Wei-Chen , Huang Wan-Hui , Chen Li-Yang 
Published: December 2014

ABSTRACT

Intragastric
Klebsiella pneumoniae
infections of mice can cause liver abscesses, necrosis of liver tissues, and bacteremia. Lithium chloride, a widely prescribed drug for bipolar mood disorder, has been reported to possess anti-inflammatory properties. Using an intragastric infection model, the effects of LiCl on
K. pneumoniae
infections were examined. Providing mice with drinking water containing LiCl immediately after infection protected them from
K. pneumoniae
-induced death and liver injuries, such as necrosis of liver tissues, as well as increasing blood levels of aspartate aminotransferase and alanine aminotransferase, in a dose-dependent manner. LiCl administered as late as 24 h postinfection still provided protection. Monitoring of the LiCl concentrations in the sera of
K. pneumoniae
-infected mice showed that approximately 0.33 mM LiCl was the most effective dose for protecting mice against infections, which is lower than the clinically toxic dose of LiCl. Surveys of bacterial counts and cytokine expression levels in LiCl-treated mice revealed that both were effectively inhibited in blood and liver tissues. Using
in vitro
assays, we found that LiCl (5 μM to 1 mM) did not directly interfere with the growth of
K. pneumoniae
but made
K. pneumoniae
cells lose the mucoid phenotype and become more susceptible to macrophage killing. Furthermore, low doses of LiCl also partially enhanced the bactericidal activity of macrophages. Taken together, these data suggest that LiCl is an alternative therapeutic agent for
K. pneumoniae
-induced liver infections.
A Novel Inhibitor of Gyrase B Is a Potent Drug Candidate for Treatment of Tuberculosis and Nontuberculosis Mycobacterial Infections
Authors: Locher Christopher P. , Jones Steven M. , Hanzelka Brian L. , Perola Emanuele , Shoen Carolyn M. , Cynamon Michael H. , Ngwane Andile H. , Wiid Ian J. , van Helden Paul D. , Betoudji Fabrice , Nuermberger Eric L. , Thomson John A. 
Published: December 2014

ABSTRACT

New drugs to treat drug-resistant tuberculosis are urgently needed. Extensively drug-resistant and probably the totally drug-resistant tuberculosis strains are resistant to fluoroquinolones like moxifloxacin, which target gyrase A, and most people infected with these strains die within a year. In this study, we found that a novel aminobenzimidazole, VXc-486, which targets gyrase B, potently inhibits multiple drug-sensitive isolates and drug-resistant isolates of
Mycobacterium tuberculosis
in vitro
(MICs of 0.03 to 0.30 μg/ml and 0.08 to 5.48 μg/ml, respectively) and reduces mycobacterial burdens in lungs of infected mice
in vivo
. VXc-486 is active against drug-resistant isolates, has bactericidal activity, and kills intracellular and dormant
M. tuberculosis
bacteria in a low-oxygen environment. Furthermore, we found that VXc-486 inhibits the growth of multiple strains of
Mycobacterium abscessus
,
Mycobacterium avium
complex, and
Mycobacterium kansasii
(MICs of 0.1 to 2.0 μg/ml), as well as that of several strains of
Nocardia
spp. (MICs of 0.1 to 1.0 μg/ml). We made a direct comparison of the parent compound VXc-486 and a phosphate prodrug of VXc-486 and showed that the prodrug of VXc-486 had more potent killing of
M. tuberculosis
than did VXc-486
in vivo
. In combination with other antimycobacterial drugs, the prodrug of VXc-486 sterilized
M. tuberculosis
infection when combined with rifapentine-pyrazinamide and bedaquiline-pyrazinamide in a relapse infection study in mice. Furthermore, the prodrug of VXc-486 appeared to perform at least as well as the gyrase A inhibitor moxifloxacin. These findings warrant further development of the prodrug of VXc-486 for the treatment of tuberculosis and nontuberculosis mycobacterial infections.
Molecular Analysis of Codon 548 in the
rpoB
Gene Involved in Mycobacterium tuberculosis Resistance to Rifampin
Authors: Horng Yu-Tze , Jeng Wen-Yih , Chen Yih-Yuan , Liu Che-Hung , Dou Horng-Yunn , Lee Jen-Jyh , Chang Kai-Chih , Chien Chih-Ching , Soo Po-Chi 
Published: December 2014

ABSTRACT

Most
Mycobacterium tuberculosis
rifampin-resistant strains have been associated with mutations in an 81-bp rifampin resistance-determining region (RRDR) in the gene
rpoB
. However, if this region alone were targeted, rifampin-resistant strains with mutations outside the RRDR would not be detected. In this study, among 51 rifampin-resistant clinical isolates analyzed by sequencing 1,681-bp-long DNA fragments containing the RRDR, 47 isolates contained mutations within the RRDR, three isolates contained mutations both within and outside the RRDR, and only one isolate had a single missense mutation (Arg548His) located outside the RRDR. A drug susceptibility test of recombinant
Mycobacterium smegmatis
and
M. tuberculosis
isolates carrying mutated
rpoB
(Arg548His) showed an increased MIC for rifampin compared to that of the control strains. Modeling of the Arg548His mutant RpoB-DNA complex revealed that the His548 side chain formed a more stable hydrogen bond structure than did Arg548, reducing the flexibility of the rifampin-resistant cluster II region of RpoB, suggesting that the RpoB Arg548His mutant does not effectively interact with rifampin and results in bacterial resistance to the drug. This is the first report on the relationship between the mutation in codon 548 of RpoB and rifampin resistance in tuberculosis. The novel mutational profile of the
rpoB
gene described here will contribute to the comprehensive understanding of rifampin resistance patterns and to the development of a useful tool for simple and rapid drug susceptibility tests.
Involvement of Holliday Junction Resolvase in Fluoroquinolone-Mediated Killing of Mycobacterium smegmatis
Authors: Long Quanxin , Du Qinglin , Fu Tiwei , Drlica Karl , Zhao Xilin , Xie Jianping 
Published: December 2014

ABSTRACT

The absence of the Holliday-junction Ruv resolvase of
Mycobacterium smegmatis
increased the bacteriostatic and bactericidal activities of the fluoroquinolone moxifloxacin, an important antituberculosis agent. The treatment of
ruvAB
-deficient cells with thiourea and 2,2′-bipyridyl lowered moxifloxacin lethality to wild-type levels, indicating that the absence of
ruvAB
stimulates a lethal pathway involving reactive oxygen species. A hexapeptide that traps the Holliday junction substrate of RuvAB potentiated moxifloxacin-mediated lethality, supporting the development of small-molecule enhancers for moxifloxacin activity against mycobacteria.