bluuebunny/crossref_metadata_2025_split huggingface dataset:
Distribution and Diversity of Salmonella Strains in Shipments of Hatchling Poultry, United States, 2013
Authors: Habing G. G. , Kessler S. E. , Mollenkopf D. F. , Wittum T. E. , Anderson T. C. , Barton Behravesh C. , Joseph L. A. , Erdman M. M. 
Published: September 2014

SummaryMultistate outbreaks of salmonellosis associated with live poultry contact have been occurring with increasing frequency. In 2013, multistate outbreaks of salmonellosis were traced back to exposure to live poultry, some of which were purchased at a national chain of farm stores (Farm store chain Y). This study was conducted at 36 stores of Farm store chain Y and was concurrent with the timing of exposure for the human outbreaks of salmonellosis in 2013. We used environmental swabs of arriving shipment boxes of hatchling poultry and shipment tracking information to examine the distribution, diversity and anti‐microbial resistance of non‐typhoidal Salmonella (NTS) across farm stores and hatcheries. Isolates recovered from shipment boxes underwent serotyping, anti‐microbial resistance (AMR) testing and pulsed‐field gel electrophoresis (PFGE). Postal service tracking codes from the shipment boxes were used to determine the hatchery of origin. The PFGE patterns were compared with the PFGE patterns of NTS causing outbreaks of salmonellosis in 2013. A total of 219 hatchling boxes from 36 stores in 13 states were swabbed between 15 March 2013 and 18 April 2013. NTS were recovered from 59 (27%) of 219 hatchling boxes. Recovery was not significantly associated with species of hatchlings, number of birds in the shipment box, or the presence of dead, injured or sick birds. Four of the 23 PFGE patterns and 23 of 50 isolates were indistinguishable from strains causing human outbreaks in 2013. For serotypes associated with human illnesses, PFGE patterns most frequently recovered from shipment boxes were also more frequent causes of human illness. Boxes positive for the same PFGE pattern most frequently originated from the same mail‐order hatchery. Only one of 59 isolates was resistant to anti‐microbials used to treat Salmonella infections in people. This study provides critical information to address recurrent human outbreaks of salmonellosis associated with mail‐order hatchling poultry.
The Use of Electrostatic Charge Measurements as an Early Warning of Distress in Heavy-Duty Gas Turbines
Authors: Lapini G. L. , Zippo M. , Tirone G. 
Published: September 2014

The idea of measuring the electrostatic charge associated with the debris contained in the exhaust gases of a gas turbine (sometimes named EDMS, Engine Debris Monitoring System, or EEMS, Electrostatic Engine Monitoring System) has been demonstrated by several authors as an interesting diagnostic tool for the early warning of possible internal distresses (rubs, coating wear, hot spots in combustors, improper combustion, etc.) especially for jet engines or aeroderivative gas turbines.
While potentially applicable to machines of larger size, the possibility of transferring this monitoring technology to heavy-duty gas turbines, which have exhaust ducts much bigger in size and different operating conditions, should be demonstrated.
The authors present a synthesis of their experience and of the most significant data collected during a demonstration program performed on behalf of ENEL, the main Italian electric utility. The purpose of this program was to test this concept in real operating conditions on large turbines, and hence to evaluate the influence of the operating conditions on the system response and to assess its sensitivity to possible distresses.
A good amount of testing has been performed, during this program, both on a full scale combustion rig, and on two machines rated at about 120 MW, during their normal and purposely perturbed operating conditions in a power plant.
The authors, on the basis of the encouraging results obtained to date, comment on the work still required to bring this technology to full maturity.
The Matching of a Vaned Diffuser With a Radial Compressor Impeller and its Effect on the Stage Performance
Authors: Casey Michael , Rusch Daniel 
Published: September 2014

The matching of a vaned diffuser with a centrifugal impeller is examined with a one-dimensional (1D) analysis combined with extensive experimental data. A matching equation is derived to define the required throat area of the diffuser relative to the throat area of the impeller at different design speeds and validated by comparison with a wide range of compressor designs. The matching equation is then used to give design guidelines for the throat area of vaned diffusers operating with impellers at different tip-speed Mach numbers.
An analysis of test data for a range of high pressure ratio turbocharger compressor stages is presented in which different matching between the diffuser and the impeller has been experimentally examined. The test data includes different impellers with different diffuser throat areas over a wide range of speeds. It is shown that the changes in performance with speed and diffuser throat area can be explained on the basis of the tip-speed Mach number which causes both the diffuser and impeller to choke at the same mass flow. Based on this understanding, a radial compressor map prediction method is extended to include this parameter, so that more accurate maps for matched and mismatched vaned diffusers can be predicted.
Determination of Allowable FOD Defects Sizes on the Surface of Gas-Turbine Engine Stator Parts Based on Stress-Concentration Factors
Authors: Pakhomenkov Alexandr , Slobodskoy Denis 
Published: September 2014

Requirements for reliability and safety of modern aircraft engines are constantly growing [1–2]. Among these requirements is periodic inspection of the engine condition and condition of its individual parts during operation, for the purpose of evaluation of the risk to operation. This is to ascertain possible damage to various engine parts in the course of operation and progressive wear. Damage can occur for a variety of reasons: ingestion of foreign matter in the engine gas path, operation in extreme and off-design conditions, wear, etc. To trace the engine parts condition and detect various damage on the engine parts, periodic inspection is provided. In case of any damage or deviations on parts, the question of their performance and possibility to break during operation are addressed. There are two ways of answering this question:
1 – experimental demonstration of the required strength of parts with damage;
2 – computational demonstration of the required strength of parts with damage.
The first way requires a good deal of time and money for carrying out the experiments. It is efficient only with enough operational experience in typical parts with various surface damage. While developing a new engine (having no prototypes) it is more reasonable to use computational methods.
To determine the allowable damage of gas-turbine engine parts, a special procedure has been developed. Its main principles consist of the following:
- classification of the typical parts damage by foreign object ingestion;
- determination of the stress concentration factors (Kt) due to damage for various defect sizes;
- determination of strength factors of safety and life for various zones of parts without damage;
- determination of Kt values with which minimum allowable values of strength safety factor and life are attained;
- determination of allowable sizes of various types of damage for all zones of each part based on previously defined Kt dependencies on typical damage sizes.
This methodology is proposed for determination of allowable damage on the surface of gas-turbine engines stator parts caused by foreign object ingestion in order to ensure the required reliability and safety; its experimental verification is foreseen for the future.
Acoustic Minimization of Rotor-Stator Interaction Noise of Axial Fans by Trailing-Edge Blowing
Authors: Kohlhaas Michael , Carolus Thomas H. 
Published: September 2014

The work deals with tonal noise of axial turbo fan stages by rotor-stator interaction. The objective of this study is the reduction of this noise by injection of a secondary mass flow at the rotor blades’ trailing edge (trailing edge blowing, TEB).
A literature survey suggested that at least the tonal rotor/stator interaction sound can be reduced considerably by perfect blade wake filling which usually is achieved by blowing air through slots in the blade trailing edge region. Our own studies proved that this traditional trailing edge blowing strategy is problematic. Hence, in this paper a novel strategy of trailing edge blowing is described. The key idea is the combination of experimental trailing edge blowing with an evolutionary optimization algorithm. Aiming directly at a minimum of far field sound pressure level we identified spanwise trailing edge flowing distributions that reduced the fundamental tone at blade passing frequency (BPF) by 1.4 dB, and at its first harmonic by 21.4 dB (the latter corresponding to a complete elimination). The required blowing mass flow rate is 2% of the mass flow rate through the stage and hence relatively moderate.
3D hot wire measurement revealed that the acoustically relevant upwash velocity fluctuations as seen by the stator are not only caused by the wakes from the rotor blades but also by vortex structures at the rotor’s hub and tip. Traditional trailing edge blowing primarily aims at eliminating the rotor blade wakes. By applying the novel optimization strategy even some (but not all) of those secondary flow structures could be put out of action which eventually led to the reduction of the spectral components observed.
A New Emergency Stop and Control Valve Design: Part 2 — Validation of Numerical Model and Transient Flow Physics
Authors: Musch Christian , Deister Frank , Zimmer Gerta , Balkowski Ingo , Brüggemann Peter , Haslinger Wolfgang 
Published: September 2014

In order to enhance steam mass flow through a turbine it becomes necessary to reduce the flow resistance of the turbine inlet valves. Consequently, a replacement of the high pressure turbine inlet valves is required. The valve combination described in this paper consists of a control valve and an emergency stop valve, opposite to the control valve. Both valves share a common valve seat. The control valve is a single-seat valve with integral pilot disc. A pre-stoke is introduced to allow for moderate opening forces. The emergency stop valve closes in countercurrent with the steam mass flow.
The flow through the valve is analyzed by steady state and transient computational flow simulations. In addition to the steam mass flow, the forces acting upon the valve are determined. Transient behavior will be investigated by means of analyzing pressure fluctuations. Therefore frequencies caused by the steam flow are determined in the range up to 2000Hz.
It will be shown that neither steady state nor transient simulations with a simple eddy viscosity turbulence model are capable to correctly predict the complex flow inside the valve. More sophisticated turbulence modeling like Large-Eddy simulation is thus inevitable. Furthermore, the physical phenomena causing the transient behavior are discussed. All findings are verified by comparison of the CFD with the measurements.
The Semi-Closed Recuperated Cycle With Intercooled Compressors
Authors: Wettstein Hans E. 
Published: September 2014

The Gas Turbine Combined Cycle (GTCC) is the best currently available choice, if gaps in the renewable electric power supply need being filled at short notice with power from fossil fuels. The GTCC manufacturers are in a fierce competition responding to these needs, especially for the best part load efficiency, the fastest load ramp capability and for the lowest low load power parking at an acceptable NOx and CO emission level.
But there is an option outperforming the GTCC technology for the above mentioned requirements, which is theoretically known since years but it has not yet been practically developed. It is the Semi-Closed Recuperated Cycle (SCRC). The author has described this recently in an article [1] with the title “The air breathing semi-closed recuperated cycle and its super chargeable predecessors”.
The SCRC does not require any component technology, which is not yet proven in operating commercial GTCC or GT plants. But of course the cycle integration is a different one, requiring a specific design of the components. An inherent side feature of the SCRC is the exhaust gas composition, which corresponds to a near-stoichiometric combustion gas. This allows comparing the SCRC with a (CO2-) capture ready GTCC having exhaust gas recirculation.
The above mentioned article [1] describes the thermodynamic performance analysis of a SCRC with an adiabatic compressor. But the cycle becomes even more attractive with an intercooling stage in each of the two compressors. Here this is quantified with another detailed thermodynamic analysis. Additionally also an ideal case with isothermal compression is analyzed. The latter is of course unrealistic for a practical realization. But it indicates the potential of using more than one intercooling stage per compressor. The aim of this paper is to quantitatively compare the three variants with adiabatic, intercooled and isothermal compressors. In all three cases the same turbine and recuperator temperature limitations are used while some other cycle data assumptions are adapted to the compressor technology in order to achieve an optimal performance level for each variant. The thermodynamic results have been cross-checked with a breakdown of the exergy losses in the three variants. The final results for base load operation indicate that the intercooled variant could become the best choice.
Numerical Investigation of VSVs Mal-Schedule Effects in a Three-Stage Axial Compressor
Authors: Li Yan-Ling , Sayma Abdulnaser 
Published: September 2014

Variable Stator Vanes (VSVs) are commonly used in multi-stage axial compressors for stage matching at part load operations and during start up. Improper VSVs settings or malfunction of the controlling actuator system can lead to compressor instabilities including rotating stall and surge. It is important to be able to predict the aerodynamic behaviour of compressors in such events to either produce tolerant designs or incorporate diagnosis and recovery systems.
This paper presents a numerical study of a compressor operating near the stall boundary for a mal-scheduled VSVs case. A high-speed three-stage axial compressor with Inlet Guide Vanes (IGV) is used in the investigation because of its relative simplicity and availability of geometry and aerodynamic data. A 3D RANS viscous unsteady time-accurate flow solver was used to perform the full annulus simulation with a downstream variable nozzle to control outflow boundary conditions. The unstructured mesh contained about 25 million grid points and the simulation was performed on a high performance computing cluster for many engine rotations. Rotating stall with one single cell covering several passages in all three rotors was predicted which propagated at approximately half of the shaft speed. Full analysis of the flow features is presented in the paper.
Broadband Combustion Noise Prediction With the Fast Random Particle Method
Authors: Grimm Felix , Ewert Roland , Dierke Jürgen , Noll Berthold , Aigner Manfred 
Published: September 2014

A new highly efficient, hybrid CFD/CAA approach for broadband combustion noise modeling is introduced. The inherent sound source generation mechanism is based on turbulent flow field statistics, which are determined from reacting RANS calculations. The generated sources form the right-hand side of the linearized Euler equations for the calculation of sound fields. The stochastic time-domain source reconstruction algorithm is briefly described with emphasis on two different ways of spatial discretization, RPM (Random Particle Method) and the newly developed FRPM (Fast RPM). The application of mainly the latter technique to combustion noise (CN) prediction and several methodical progressions are presented in the paper.
(F)RPM-CN is verified in terms of its ability to accurately reproduce prescribed turbulence-induced one- and two-point statistics for a generic test and the DLR-A jet flame validation case. Former works on RPM-CN have been revised and as a consequence methodical improvements are introduced along with the progression to FRPM-CN: A canonical CAA setup for the applications DLR-A, -B and H3 flame is used. Furthermore, a second order Langevin decorrelation model is introduced for FRPM-CN, to avoid spurious high frequency noise. A new calibration parameter set for reacting jet noise prediction with (F)RPM-CN is proposed. The analysis shows the universality of the data set for 2D jet flame applications and furthermore the method’s accountance for Reynolds scalability. In this context, a Mach number scaling law is used to conserve Strouhal similarity of the jet flame spectra. Finally, the numerical results are compared to suitable similarity spectra.
Understanding Complexities in Underplatform Damper Mechanics
Authors: Gola Muzio M. , Gastaldi Chiara 
Published: September 2014

All numerical models of friction damped bladed arrays require knowledge or information of contact-friction parameters, which are established either through direct frictional measurements, done with the help of single contact test arrangements, or by fine tuning the parameters in the numerical model and comparing the experimental response of damped blade against its computed response. Some critical assumptions are necessary to the purpose, such as the position and extension of the real contact areas and the values of local friction coefficients.
In the light of recent results from direct measurements on under-platform dampers [1–3] it became evident that a dedicated routine for the damper mechanics is a much more effective tool to capture those finer details which are essential to an appropriate description of damper behaviour. This was made possible by the successful effort of the present authors to accurately measure the forces transmitted between the platforms through the damper and to relate them with the relative platform movement [2].
Simulations, and the matching experiments which are here not described, are performed under so called out-of-phase (O-O-P) and in-phase (I-P) condition simulating the two basically important motion types. Damper forces and damper kinematics are discussed for two highly representative cases in the low frequency range. Diagrams are then used to show the sensitivity to contact parameters, input motion and initial conditions on damper behaviour, casting heavy doubts on the validity of oversimplified practices.
Setting Up and Managing a PEMS Mathematical Formula to Fully Respond to the Expectations of the Regulator
Authors: Bainier Francis , Havard Florian 
Published: September 2014

Due to environmental regulations, Oxides of nitrogen (NOx) and carbon monoxide (CO) are important issues for gas turbine plants. Regulators are becoming more and more involved and they often require overall and real-time emission information. These measurements can easily be done with gas analyzers. This technology is called CEMS: Continuous Emissions Monitoring System. With CEMS, regulators easily understand proofs such as calibration and certificate. However, this technology is expensive to buy and to maintain. An alternative method is to use a calculation based on the turbine operation. This technology is called PEMS: Predictive Emissions Monitoring System. Although PEMS is less expensive than CEMS, setting up and managing a PEMS mathematical formula to fully respond to the expectations of the regulator is more complicated than using CEMS.
This paper describes an approach to set up an equation for PEMS which can be accepted by regulators.
Before starting PEMS research, expectations must be established. What are the expectations of the regulator? What are the users’ expectations? Yes, do not forget the goals of the unit operators. It is not sufficient to provide answers for regulator at the lowest cost. A responsible user is also concerned about the environmental aspect and this fact will help your in the future. GRTgaz, the main gas transmission company in France managing 44 turbines spread over 25 stations across France, has decided to answer these questions before starting research. The answers to these questions make up the first part of this 4-part paper.
The second part of the paper is a review of publications and literature. Since no applicable PEMS exist for all types of combustion turbines, analyzing empirical and theoretical formulas leads to the important parameters and the link between them.
The third part is dedicated to turbines. A lean premixed combustion system and its regulation are described. Also in this part, the available measured parameters are listed in regards to their combustion influence and their accuracy.
The fourth part deals with the establishment of equations and their tests in regards to the goals.
The last part presents the implementation of the equations on the units.
If tools and knowledge are available, the conclusion point out that achieving a PEMS requires a good evaluation and understanding of the expectations of the regulator, not only in the present day but also what they will and could be.
Techno–Economic Evaluation of Recuperated Gas Turbine Cogeneration Cycles Utilizing Animal Manure and Energy Crops for Biogas Fuel
Authors: Kontokostas Georgios , Goulos Ioannis , Stamatis Anastassios 
Published: September 2014

This work presents the development of an integrated approach, targeting the techno-economic assessment of recuperated cogeneration gas turbine cycles, utilizing anaerobic digestion products of animal manure and energy crops for biogas fuel. The overall approach consists of a series of fundamental modeling theories applicable to; anaerobic digestion and biogas fuel yield, thermodynamic analysis of cogeneration gas turbine cycles, exergetic analysis of anaerobic digestion, and economic modeling of implementation and operation. The developed methodology is applied to the techno-economic analysis of a representative anaerobic digestion plant yielding biogas fuel which is supplied to a recuperated cogeneration gas turbine powerplant. The influence of employed thermodynamic cycle parameters along with the incorporated technology level, on the cycle performance parameters and economic sustainability of integrated digestion–cogeneration powerplant designs, is thoroughly investigated.
The obtained results suggest that, the dominant thermodynamic cycle variables that affect the electrical performance of integrated digestion-cogeneration systems, are the gas/air temperatures at the combustor outlet and recuperator air side exit, respectively. It is shown that the profitability of the investment is highly depended on the electrical power output and the feed–in tariff for electrical energy. Optimization of the employed co-generation cycle for maximum electrical power output, is shown to be a crucial element in terms of securing investment sustainability. A general review of the results indicates that, anaerobic treatment of animal manure and energy crops may constitute a sustainable investment, primarily for cases that substantial volumes of substrates are available in order to secure biogas yield and stable operation of the AD–gas turbine power plant.