bluuebunny/crossref_metadata_2025_split huggingface dataset:
Trailing Edge 3D Free Shear Layers
Authors: Schröder N. , Hofmann G. , Hourmouziadis J. 
Published: August 2014

This paper reports on an investigation of coherent structures and the characteristic flow field of trailing edge shed vorticity, which can be found downstream of blade rows as well as behind lobed exhaust mixers. The corresponding, fundamental flow case of a free, skewed mixing layer was studied both experimentally in a low-speed test facility and numerically using Standard k,ε-Model and Large Eddy Simulation (LES).
The investigation gave a new insight into the flow structure. Along the complete development length there is a coexistence of the streamwise vortices generated by cross-shear with the spanwise vorticity of Von-Karman vortex street or two-dimensional Kelvin-Helmholtz instability. This was confirmed by extensive flow-field measurements using five-hole probes and X-wire anemometry as well as by CFD. The measurement of the mixing layer spreading resulted in a growth rate of the skewed mixing layer very similar to that of the two-dimensional flow. The development of energy thickness downstream of the trailing edge, representing the mixing losses, was found to be practically independent of skewing angle. The spacing and the fluctuation of the streamwise vortex cores were not accessible to probe measurement, but were determined by visualization and large eddy simulation. The separation of vorticity-components gave stable distributions in streamwise and spanwise direction until vortex breakdown, which appears to be independent of the initial state of the boundary layer. A criterion for streamwise vortex breakdown was identified by correcting the development length with the equivalent shear layer parameter. The content of turbulent kinetic energy as a measure for turbulence production and mixing efficiency is discussed.
The Influence of Low Solidity Vaned Diffusers on the Static Pressure Non-Uniformity Caused by a Centrifugal Compressor Discharge Volute
Authors: Sorokes James M. , Koch Jay M. 
Published: August 2014

The paper is a sequel to an earlier work by Sorokes et al. 1998, “Investigation of the Circumferential Static Pressure Non-Uniformity Caused by a Centrifugal Compressor Discharge Volute.” The earlier work described experimental and computational fluid dynamics analyses of the non-uniform static pressure distortion caused by the discharge volute in a high pressure, centrifugal compressor with vaneless diffusers. This paper describes additional testing and analytical work done using low solidity vaned diffusers (LSD’s) in place of select vaneless diffusers to determine the alternate diffuser’s effectiveness in eliminating or reducing the magnitude of the non-uniform pressure field. As in the earlier studies, the experiments described in this paper were done using a heavily instrumented gas re-injection compressor operating at over 6000 psia discharge pressure. Instrumentation was installed to measure static, total, and dynamic pressure as well as impeller strain and mechanical vibrations. A brief description of the compressor and instrumentation are provided.
Concurrent with the experimental work, CFD runs were completed to study the effect of the alternate vaned diffusers. The CFD pressure profile trends agreed well with the experimental results and provided analytical corroboration for the conclusions drawn from the test data.
Conclusions are drawn regarding: a) the effectiveness of the LSD’s on the pressure non-uniformity; b) the associated effects on the measured dynamic strains in the impellers; and c) the usefulness of computational fluid dynamics (CFD) in assessing the aerodynamic forces associated with the non-uniformity.
Flow Interaction From the Exit Cavity of an Axial Turbine Blade Row Labyrinth Seal
Authors: Pfau A. , Treiber M. , Sell M. , Gyarmathy G. 
Published: August 2014

The structure of labyrinth cavity flow has been experimentally investigated in a three fin axial turbine labyrinth seal (four cavities). The geometry corresponds to a generic steam turbine rotor shroud. The relative wall motion has not been modeled. The measurements were made with specially developed low-blockage pneumatic probes and extensive wall pressure mapping.
Instead of the classical picture of a circumferentially uniform leakage sheet exiting from the last labyrinth clearance, entering the channel, and uniformly spreading over the downstream channel wall, the results reveal uneven flow and the existence of high circumferential velocity within the entire exit cavity. The circumferential momentum is brought into the cavity by swirling fluid from the main channel. This fluid penetrates the cavity and breaks up the leakage sheet into individual jets spaced according to the blade passages. This gives rise to strong local cross flows that may also considerably disturb the performance of a downstream blade row.
Investigation of the Spanwise Transport of the Rotor – Stator Slot Flow in a Test Turbine
Authors: Lindqvist Lars O. , Wickholm Joakim E. , Fransson Torsten H. , Torisson Tord 
Published: August 2014

Modern gas turbines are working in a high temperature environment. The needs for cooling the first stage discs and airfoils are inevitable. In order to avoid overcooling it is necessary to have as much information of the temperature redistribution along the flow path as possible. This paper presents results from both a numerical and an experimental investigation of the temperature redistribution.
The numerical part of this investigation is based on 3D Navier-Stokes calculations, where a single stage test turbine is modeled. Combined with an experimental testing of the calculated geometry the influences of the slot flow, which enters the main gas from a slot at the hub section between the stator and the rotor, are evaluated.
The test turbine is working with air at low temperature, typically in the order of atmospheric conditions. In order to simulate the temperature distribution caused by the slot flow trace gas technique is used.
The influence of three parameters, the slot mass flow, the velocity ratio and the pressure ratio, was studied.
The main result of changing the slot mass flow is a change in the absolute value of the temperature minimum. In addition a slight dependence of the penetration depth was observed.
The spanwise transport of the slot flow within the rotor is highly dependent on the velocity ratio. However, some distance downstream of the trailing edge, the core of the slot flow merges together for different velocity ratios.
Varying the turbine stage pressure ratio, from 1.14 to 1.34, did not affect the spanwise transport. Since the pressure ratio is a representative of the main gas mass flow, a decreased pressure ratio results in a higher degree of cooling, as less main gas is present.
Three-Dimensional Turbulent Flow of the Tip Leakage Vortex in an Axial Compressor Rotor Passage
Authors: Ma Hongwei , Jiang Haokang 
Published: August 2014

Three-dimensional turbulent flow of the tip leakage vortex in a single-stage axial compressor rotor passage is studied using a 3-Component Laser Doppler Velocimetry. The measurement results indicate that the tip leakage vortex originates at about 10% axial chord, 8% pitch away from the suction surface, and becomes strongest at about 30% chord.
With the flow downstream, the vortex core moves toward the pressure surface and to a lower radial location, leading to substantial flow mixing, blockage and turbulence in the tip region. The radial component of turbulence intensities is found to be the highest while the axial-radial component of Reynolds stresses is the largest.
Breakdown of the leakage vortex occurs inside the rear rotor passage, which makes the flow more turbulent in a wider region downstream. This viewpoint is confirmed by the measurements of unsteady static pressure on the casing wall.
Breakdown of a leakage vortex is observed clearly in a compressor cascade with a small clearance. Unsteady interactions of the broken vorticities and the suction surface’s boundary layer are shown obviously inside the downstream passage.
Rotating Instabilities in an Axial Compressor Originating From the Fluctuating Blade Tip Vortex
Authors: Mailach R. , Lehmann I. , Vogeler K. 
Published: August 2014

Rotating instabilities (RI) have been observed in axial flow fans, centrifugal compressors as well as in low-speed and high-speed axial compressors. They are responsible for the excitation of high amplitude rotor blade vibrations and noise generation. This flow phenomenon moves relative to the rotor blades and causes periodic vortex separations at the blade tips and an axial reversed flow through the tip clearance of the rotor blades.
The paper describes experimental investigations of RI in the Dresden Low-Speed Research Compressor (LSRC). The objective is to show that the fluctuation of the blade tip vortex is responsible for the origination of this flow phenomenon.
RI have been found at operating points near the stability limit of the compressor with relatively large tip clearance of the rotor blades. The application of time-resolving sensors in both fixed and rotating frame of reference enables a detailed description of the circumferential structure and the spatial development of this unsteady flow phenomenon, which is limited to the blade tip region.
Laser-Doppler-Anemometry (LDA) within the rotor blade passages and within the tip clearance as well as unsteady pressure measurements on the rotor blades show the structure of the blade tip vortex.
It will be shown that the periodical interaction of the blade tip vortex of one blade with the flow at the adjacent blade is responsible for the generation of a rotating structure with high mode orders, termed as rotating instability (RI).
A Test Rig for Frictionally Damped Bladed Segments
Authors: Berruti T. , Goglio L. , Filippi S. , Gola M. M. , Salvano S. 
Published: August 2014

The paper describes the development of an instrumented test rig suitable to carry out vibration testing of the bladed segments of a turbine (belonging to a stator low pressure stage) in which the friction occurring at the contact of neighboring segments is used in service to damp the vibrations.
The system is able to assign the desired preload to the segment and to measure the forces exerted in the contact and the relative displacements due to slipping.
The main results that can be obtained concern the type of motion that takes place (stick/slip) and the effect of the interlocking on it, the friction coefficients, the contact tangential stiffness, and, more generally, the frequency response.
An Update of the Virtual Energy Laboratory
Authors: Perez-Blanco H. , Albright Paul 
Published: August 2014

The Virtual Energy Lab (VEL) is a PC based didactic tool for use in conjunction with courses on technical thermodynamics and thermal system design. The tool can also be used for conceptual design of large-scale systems incorporating cogeneration schemes of varied types. The user can learn how to combine conventional thermal systems in creative ways to enhance exergetic efficiency.
In the present work, we describe upgrades to this tool, and we present several examples to show the possibilities of energy cascading. The features of ease of learning, user ability to specify important parameters and ready targeting of conceptual designs were preserved in the updated version.
What is the Electric Output of a Cogeneration Project Worth?
Authors: de Kok Alexandra C. , Hill Jane P. 
Published: August 2014

The economics of cogeneration depend on whose perspective is being considered. A retail electric customer is concerned with the degree to which electric purchases at regulated tariffs can be reduced. A public utility’s perspective includes where the unit would fit in the generation “stack,” how much the unit would operate, and the opportunity costs of operating the cogeneration unit as opposed to other available units. An independent power producer (IPP) has many of the same objectives as an electric utility. However, an IPP has no franchised service territory guaranteeing markets for electricity it produces, although an IPP escapes many issues associated with regulation.
Because of these different perspectives, a cogeneration project which is economic for one entity might not be for another. In addition, even if cogeneration is thought to be economic for all three, the optimal equipment selection and operating scenario can vary substantially among potential investors.
This paper discusses the factors which influence economic viability of cogeneration from the perspectives of different potential investors.
Dynamic Behaviour of a Vertical Natural Circulation Two Pressure Stage HRSG Behind a Heavy Duty Gas Turbine
Authors: Stamatelopoulos Georg N. , Ponweiser Karl , Walter Heimo , Linzer Wladimir , Neßler Hubert , Strohmaier Robert 
Published: August 2014

Modern combined cycle gas turbines are highly flexible in their operation, concerning start up, load change and shut down. Heat Recovery Steam Generators (HRSG) arranged downstream of the Gas Turbine (GT) are forced to operate in such a way, that the gas turbine operation is not restricted by them. Therefore, they should be designed for a high cycling capability with typical values in the range of 200 to 250 cold starts, 1000 warm and 2500 hot starts for their typical 25 year life span. Cold starts are defined as a standstill period of over 120 hours, warm starts to a weekend shutdown and hot starts to an overnight shut down.
AE Energietechnik GmbH (AE), a Babcock Borsig Power company has specialized in designing, erecting and commissioning vertical natural circulation multiple pressure stage HRSGs. The vertical design combines simplicity and low investment costs with performance reliability and high availability. In order to forecast the dynamic behaviour of such a HRSG, AE has supported the development of a dynamic simulation code at the Institute of Thermal Engineering (ITW) located at the Vienna University of Technology. This finite volume code enables the prediction of velocities, pressures and temperatures for several dynamic processes of the HRSG.
In the present paper computational results of starts and load changes will be presented for a vertical natural circulation HRSG. Furthermore, several design optimization changes which where made in order to increase operational reliability and availability will be demonstrated. Finally, practical applications of already constructed HRSG will be discussed and conclusions will be drawn.
United States Navy (USN) Integrated Power System (IPS) Testing Experience With a LM2500 Generator Set Utilizing a MicroNet Controller
Authors: Kingsley Joseph , Stauffer Matthew 
Published: August 2014

The US Navy has been researching integrated electric propulsion systems for many years. The economic advantages of the integrated electric architecture, where power for propulsion as well as ship service are derived from a common set of generators, are well recognized and such systems are used throughout many sectors of the commercial marine industry today. In addition to the economic advantages, there are military benefits to the ship when an Integrated Power System (IPS) architecture is adopted. Those include increased reliability and survivability, reduced signatures and increased upgradeability.
A full scale Land Based Engineering Site (LBES) was constructed at the Advanced Propulsion and Power Generation Test Site (APPGTS) of the Naval Surface Warfare Center, Carderock Division – Ship Systems Engineering Station (NSWCCD-SSES) in Philadelphia, Pa, to demonstrate the system architecture and feasibility of chosen technologies for a warship application. This paper will describe the IPS, test site construction, and test operational experience with a GE LM2500 engine, utilizing a Woodward Governor Company (WGC) MicroNet controller, as the prime mover for the main generator set.
MCTP system model based on linear programming optimization of apertures obtained from sequencing patient image data maps
Authors: Ureba A. , Salguero F. J. , Barbeiro A. R. , Jimenez‐Ortega E. , Baeza J. A. , Miras H. , Linares R. , Perucha M. , Leal A. 
Published: August 2014

Purpose:The authors present a hybrid direct multileaf collimator (MLC) aperture optimization model exclusively based on sequencing of patient imaging data to be implemented on a Monte Carlo treatment planning system (MC‐TPS) to allow the explicit radiation transport simulation of advanced radiotherapy treatments with optimal results in efficient times for clinical practice.Methods:The planning system (called CARMEN) is a full MC‐TPS, controlled through aMATLAB interface, which is based on the sequencing of a novel map, called “biophysical” map, which is generated from enhanced image data of patients to achieve a set of segments actually deliverable. In order to reduce the required computation time, the conventional fluence map has been replaced by the biophysical map which is sequenced to provide direct apertures that will later be weighted by means of an optimization algorithm based on linear programming. A ray‐casting algorithm throughout the patient CT assembles information about the found structures, the mass thickness crossed, as well as PET values. Data are recorded to generate a biophysical map for each gantry angle. These maps are the input files for a home‐made sequencer developed to take into account the interactions of photons and electrons with the MLC. For each linac (Axesse of Elekta and Primus of Siemens) and energy beam studied (6, 9, 12, 15 MeV and 6 MV), phase space files were simulated with the EGSnrc/BEAMnrc code. The dose calculation in patient was carried out with the BEAMDOSE code. This code is a modified version of EGSnrc/DOSXYZnrc able to calculate the beamlet dose in order to combine them with different weights during the optimization process.Results:Three complex radiotherapy treatments were selected to check the reliability of CARMEN in situations where the MC calculation can offer an added value: A head‐and‐neck case (Case I) with three targets delineated on PET/CT images and a demanding dose‐escalation; a partial breast irradiation case (Case II) solved with photon and electron modulated beams (IMRT + MERT); and a prostatic bed case (Case III) with a pronounced concave‐shaped PTV by using volumetric modulated arc therapy. In the three cases, the required target prescription doses and constraints on organs at risk were fulfilled in a short enough time to allow routine clinical implementation. The quality assurance protocol followed to check CARMEN system showed a high agreement with the experimental measurements.Conclusions:A Monte Carlo treatment planning model exclusively based on maps performed from patient imaging data has been presented. The sequencing of these maps allows obtaining deliverable apertures which are weighted for modulation under a linear programming formulation. The model is able to solve complex radiotherapy treatments with high accuracy in an efficient computation time.
Draft Genome Sequence of Pasteurella multocida subsp.
multocida
B:2 Strain VTCCBAA264 Isolated from
Bubalus bubalis
in North India
Authors: Vaid R. K. , Shanmugasundaram K. , Boora Ashok , Bera B. C. , Shukla B. N. , Anand Taruna , Singha Harisankar , Riyesh Thachamvally , Virmani N. , Barua S. , Ahir V. B. , Koringa P. G. , Sajnani M. R. , Bhat Vaibhav D. , Rana N. , Singh K. P. , Malik P. , Singh R. K. , Joshi C. G. 
Published: August 2014

ABSTRACT

The
Pasteurella multocida
subsp.
multocida
B:2 serotype causes hemorrhagic septicemia in bubalines with high morbidity and mortality in the Indian subcontinent. We report the draft genome sequence of
Pasteurella multocida
strain VTCCBAA264 isolated from the small-intestine of a buffalo calf that died of high fever.
Cell-Cycle Reprogramming for PI3K Inhibition Overrides a Relapse-Specific C481SBTKMutation Revealed by Longitudinal Functional Genomics in Mantle Cell Lymphoma
Authors: Chiron David , Di Liberto Maurizio , Martin Peter , Huang Xiangao , Sharman Jeff , Blecua Pedro , Mathew Susan , Vijay Priyanka , Eng Ken , Ali Siraj , Johnson Amy , Chang Betty , Ely Scott , Elemento Olivier , Mason Christopher E. , Leonard John P. , Chen-Kiang Selina 
Published: August 2014

AbstractDespite the unprecedented clinical activity of the Bruton tyrosine kinase (BTK) inhibitor ibrutinib in mantle cell lymphoma (MCL), acquired resistance is common. By longitudinal integrative whole-exome and whole-transcriptome sequencing and targeted sequencing, we identified the first relapse-specific C481S mutation at the ibrutinib binding site of BTK in MCL cells at progression following a durable response. This mutation enhanced BTK and AKT activation and tissue-specific proliferation of resistant MCL cells driven by CDK4 activation. It was absent, however, in patients with primary resistance or progression following transient response to ibrutinib, suggesting alternative mechanisms of resistance. Through synergistic induction of PIK3IP1 and inhibition of PI3K–AKT activation, prolonged early G1 arrest induced by PD 0332991 (palbociclib) inhibition of CDK4 sensitized resistant lymphoma cells to ibrutinib killing when BTK was unmutated, and to PI3K inhibitors independent of C481S mutation. These data identify a genomic basis for acquired ibrutinib resistance in MCL and suggest a strategy to override both primary and acquired ibrutinib resistance.Significance: We have discovered the first relapse-specific BTK mutation in patients with MCL with acquired resistance, but not primary resistance, to ibrutinib, and demonstrated a rationale for targeting the proliferative resistant MCL cells by inhibiting CDK4 and the cell cycle in combination with ibrutinib in the presence of BTKWT or a PI3K inhibitor independent of BTK mutation. As drug resistance remains a major challenge and CDK4 and PI3K are dysregulated at a high frequency in human cancers, targeting CDK4 in genome-based combination therapy represents a novel approach to lymphoma and cancer therapy. Cancer Discov; 4(9); 1022–35. ©2014 AACR.This article is highlighted in the In This Issue feature, p. 973