bluuebunny/crossref_metadata_2025 huggingface dataset:
Environmental Justice and Community‐Based Research in Texas Borderland Colonias
Authors: Cantu Adelita , Graham Margaret A. , Millard Ann V. , Flores Isidore , Mugleston Meaghan K. , Reyes Iris Y. , Carbajal Ester S.
Published: March 2015

Objective

An innovative academic‐community partnership studied daily decisions in communities of mostly Spanish‐speaking, low‐income residents of colonias in Hidalgo County, TX, about risk of exposure to fish contaminated by PCBs at an Environmental Protection Agency (EPA) Superfund site.

Design and Sample

The team used focus group interviews with colonia residents and content analysis to assess knowledge of risk related to the Superfund site, the Donna Reservoir and Canal System.

Results

(1) many lacked knowledge of the Superfund site contamination; (2) a few participants fished at the lake, knew people who did so, and consumed the catch, but most participants feared going there; (3) some participants remember receiving messages saying not to fish at the site, although they recalled nothing about contamination, but most participants knew of no such messages; (4) many use cell phones to get local information through personal networks and several Spanish‐language news sources, but they have no consistent, culturally tailored local information source.

Conclusions

The findings indicate the need for further efforts to design culturally tailored means of communication and messages to inform local communities widely about the dangers related to the Superfund site and thus decrease health disparities resulting from consuming fish from the site.
Arginase activity in peripheral blood of patients with intestinal schistosomiasis, Wonji, Central Ethiopia
Authors: Getaneh A. , Tamrat A. , Tadesse K.
Published: March 2015

Morbidity and mortality caused by schistosomiasis usually results from immunopathology. But the underlying mechanisms are not yet clearly understood. Th2‐type immune response is thought to be dominant during chronic schistosomiasis, and upregulation of arginase‐I is one component of this milieu. A cohort study was conducted to assess arginase activity in peripheral blood of humans with intestinal schistosomiasis in Wonji‐Shoa Sugar Estate, Central Ethiopia. Laboratory‐confirmed 30 Schistosoma mansoni‐infected patients and 18 apparently healthy controls were recruited. Faecal egg count was carried out by Kato‐Katz technique. Plasma and peripheral blood mononuclear cells (PBMCs) were isolated from whole blood. Activity of arginase in plasma and PBMC lysates was measured, and results were compared with that of controls. Twenty‐one of 30 patients had light infection, whereas moderate and heavy intensity infections were observed in eight and only one patient(s), respectively. A significant increase in both PBMC (patients: 59·96 + 82·99, controls: 25·44 + 24·6 mU/mg protein, P < 0·0001) and plasma (patients: 1·61 + 2·19, controls: 0·31 + 0·73 mU/mL plasma, P < 0·0001) arginase activity was observed during human S. mansoni infection. Arginase activity increases in peripheral blood of patients with intestinal schistosomiasis.
An Advanced Systematic Literature Review on Spatiotemporal Analyses of Twitter Data
Authors: Steiger Enrico , de Albuquerque João Porto , Zipf Alexander
Published: March 2015

The objective of this article is to conduct a systematic literature review that provides an overview of the current state of research concerning methods and application for spatiotemporal analyses of the social network Twitter. Reviewed papers and their application domains have shown that the study of geographical processes by using spatiotemporal information from location‐based social networks represent a promising and still underexplored field for GIScience researchers.
The Role of Contextual Info‐Marks in Navigating a Virtual Rural Environment
Authors: Rousell Adam , Jarvis Claire , Brunsdon Chris
Published: March 2015

Navigation is a task performed in both large and small scale environments. Landmarks within an environment are of great benefit to these navigational tasks, but in large rural environments such landmarks may be sparse. It has been shown that landmarks need not be purely visual and that a change in context for a feature can make it become a landmark against its surroundings (such as being provided with significant meaning). Such meaning could be added through personal experience or by informing the observer via some form of communication. To investigate the effects of providing such contextual information on navigational performance, experiments were conducted in a large rural virtual environment where the delivery method of the information was varied between onscreen and PDA display. Users were instructed to perform a route tracing navigation task. In some instances users were presented with textual information about specific locations within the environment which appeared when they were in the vicinity of the location. Both quantitative and qualitative data were collected and analyzed, with results indicating that although the actual performance in the task was not significantly improved, users felt that their performance was better and the task easier when they were presented with the contextual information.
Extemporaneous benznidazole oral suspension prepared from commercially available tablets for treatment of Chagas disease in paediatric patients
Authors: García Mónica C. , Manzo Ruben H. , Jimenez‐Kairuz Alvaro F.
Published: March 2015

Objective

To develop an extemporaneous 1% benznidazole (BNZ) suspension, with masked taste and adequate stability starting from available commercial tablets. The quality of compounding was evaluated through content uniformity measurement and physical and microbiological stability evaluation, under different storage conditions during 90 days.

Methods

Six batches of 1% BNZ suspension were prepared using safe excipients currently available in a galenic area of Hospital Pharmacy and then stored at 5 and 25 °C for 90 days. The BNZ content was determined by UV spectrophotometry. Physical stability was defined as the absence of colour, odour and/or flavour changes and the re‐suspension of solid phase by a reasonable amount of simple 15‐s shaking. The compliance with microbiological attributes of non‐sterile pharmaceutical products was also evaluated.

Results

An oral liquid suspension, containing 1% of BNZ, was developed from commercially available BNZ tablets. The formulations stored for 90 days were easily re‐dispersed after a simple 15‐s shaking, ensuring the pouring of a liquid volume containing the desired dose of BNZ. All samples were within the acceptable range of BNZ concentration with minimal standard deviations. There were no detectable changes in colour, odour, viscosity, pH and microbial growth, complying with official quality requirements. The quality attributes were not affected by storage, room or refrigeration conditions or by the frequent opening or closing of the multidose containers.

Conclusion

Paediatric oral liquid suspension containing 1.0% of BNZ was easily prepared starting from commercial tablets, being an interesting alternative for optimising the paediatric treatment of Chagas disease.
Is zidovudine first‐line therapy virologically comparable to tenofovir in resource‐limited settings?
Authors: Labhardt Niklaus D. , Bader Joëlle , Lejone Thabo Ismael , Ringera Isaac , Puga Daniel , Glass Tracy R. , Klimkait Thomas
Published: March 2015

Objective

To compare virologic success between adult patients on tenofovir (TDF) and zidovudine (AZT)‐containing first‐line antiretroviral (ART) regimens in 10 rural clinics in Lesotho, Southern Africa.

Methods

Multicentre cross‐sectional study, patients ≥16 years, on first‐line ART ≥6 months, receiving AZT/lamivudine (3TC) or TDF/3TC combined with efavirenz (EFV) or nevirapine (NVP). Patient characteristics and clinical/therapeutic history were collected on the day of blood draw for viral load (VL). Analysis was stratified for non‐nucleoside reverse transcriptase inhibitor (EFV or NVP). A logistic regression model weighted for patients' baseline characteristics was used to assess the likelihood of virologic success (<80 copies/ml) in patients with TDF‐ as compared to AZT‐backbones.

Results

In total 1539 patients were included in the analysis. Most were clinically and immunologically stable (clinical failure: 2.7% (AZT) and 2.8% (TDF); immunological failure: 4.6% (AZT) and 4.8% (TDF)). In EFV‐based regimens (n = 1162), TDF was significantly associated with higher rates of virologic suppression than AZT (93.8% vs. 88.1%; weighted odds ratio: 2.15 (95% CI: 1.29–3.58; P = 0.003)). In NVP‐based regimens, a similar trend was observed, but not significant (89.4% vs. 86.7%; 1.99 (0.83–4.75, P = 0.121)).

Conclusion

These findings support the WHO recommendation to use TDF/3TC/EFV as first‐line regimen. They do, however, not support the recommendation that patients who are clinically stable on AZT should continue on this first‐line regimen.
Lrp1/LDL Receptor Play Critical Roles in Mannose 6‐Phosphate‐Independent Lysosomal Enzyme Targeting
Authors: Markmann Sandra , Thelen Melanie , Cornils Kerstin , Schweizer Michaela , Brocke‐Ahmadinejad Nahal , Willnow Thomas , Heeren Joerg , Gieselmann Volkmar , Braulke Thomas , Kollmann Katrin
Published: March 2015

Most lysosomal enzymes require mannose 6‐phosphate (M6P) residues for efficient receptor‐mediated lysosomal targeting. Although the lack of M6P residues results in missorting and hypersecretion, selected lysosomal enzymes reach normal levels in lysosomes of various cell types, suggesting the existence of M6P‐independent transport routes. Here, we quantify the lysosomal proteome in M6P‐deficient mouse fibroblasts (PTki) using Stable Isotope Labeling by Amino acids in Cell culture (SILAC)‐based comparative mass spectrometry, and find unchanged amounts of 20% of lysosomal enzymes, including cathepsins D and B (Ctsd and Ctsb). Examination of fibroblasts from a new mouse line lacking both M6P and sortilin, a candidate for M6P‐independent transport of lysosomal enzymes, revealed that sortilin does not act as cargo receptor for Ctsb and Ctsd. Using fibroblast lines deficient for endocytic lipoprotein receptors, we could demonstrate that both LDL receptor and Lrp1 mediate the internalization of non‐phosphorylated Ctsb and Ctsd. Furthermore, the presence of Lrp1 inhibitor increased the secretion of Ctsd from PTki cells. These findings establish Lrp1 and LDL receptors in M6P‐independent secretion‐recapture targeting mechanism for lysosomal enzymes.
Survivors of Organizational Change: A Resource Perspective
Authors: Lee Yu-Chin , Mao Pei-Chuan
Published: March 2015

The failure rate of organizational change and studies regarding personal turmoil resulting from organizational change indicate that even employees survive layoff, merger, or any forms of changes, they still develop symptoms of distress, cynicism, and work withdrawal. In this paper, we propose a conceptual model based on the conservation of resources theory to examine the effect of organizational change on survivors’ organizational identification and well-being. Moreover, we suggest that organizational change may not be as harmful for employees who possess positive attitude toward the process. We offer research propositions and discuss implications for future organizational change research.
Inhibitory effects of relaxin on cardiac fibroblast‐to‐myofibroblast transition: an electrophysiological study
Authors: Squecco Roberta , Sassoli Chiara , Garella Rachele , Chellini Flaminia , Idrizaj Eglantina , Nistri Silvia , Formigli Lucia , Bani Daniele , Francini Fabio
Published: March 2015

New Findings

What is the central question of this study?

Fibroblast‐to‐myofibroblast transition is a key mechanism in the reparative response to tissue damage, but myofibroblast persistence in the wound leads to fibrosis and organ failure. The role of relaxin as an antifibrotic agent capable of counteracting the acquisition of biophysical features of differentiated myofibroblasts deserves further investigation.

What is the main finding and its importance?

Electrophysiological analysis showed that relaxin, administered during profibrotic treatment, hyperpolarizes the membrane potential and attenuates delayed rectifier and inwardly rectifying K+ currents, which usually increase in the transition to myofibroblasts. These findings provide further clues to the therapeutic potential of relaxin in fibrosis.

The hormone relaxin (RLX) is produced by the heart and may be involved in endogenous mechanisms of cardiac protection against ischaemic injury and fibrosis. Recent findings in cultured cardiac stromal cells suggest that RLX can inhibit fibroblast‐to‐myofibroblast transition, thereby counteracting fibrosis. In order to explore its efficiency as an antifibrotic agent further, we designed the present study to investigate whether RLX may influence the electrophysiological events associated with differentiation of cardiac stromal cells to myofibroblasts. Primary cardiac proto‐myofibroblasts and NIH/3T3 fibroblasts were induced to myofibroblasts by transforming growth factor‐β1, and the electrophysiological features of both cell populations were investigated by whole‐cell patch clamp. We demonstrated that proto‐myofibroblasts and myofibroblasts express different membrane passive properties and K+ currents. Here, we have shown, for the first time, that RLX (100 ng ml−1) significantly reduced both voltage‐ and Ca2+‐dependent delayed‐rectifier and inward‐rectifying K+ currents that are typically increased in myofibroblasts compared with proto‐myofibroblasts, suggesting that this hormone can antagonize the biophysical effects of transforming growth factor‐β1 in inducing myofibroblast differentiation. These newly recognized effects of RLX on the electrical properties of cardiac stromal cell membrane correlate well with its well‐known ability to suppress myofibroblast differentiation, further supporting the possibility that RLX may be used for the treatment of cardiac fibrosis.
Experiments With a Low Specific Speed Partial Emission Centrifugal Compressor
Authors: Rodgers Colin
Published: March 2015

This paper describes experiments that were conducted several years ago on a single-stage open face centrifugal partial emission compressor with a non-dimensional specific speed of D.15 (19.3 dimensional). The purpose of the experiments was to experimentally evaluate the partial emission compressor as a possible candidate for a high speed low flow natural gas fuel pump, the alternative to which was a larger heavier reciprocating compressor.

A review and re-analysis of the test data were conducted. The used updated compressor data reduction performance procedures and flow models to redefine the experimental compressor as a reference case in the low specific speed range of single-stage centrifugal compressors.

Normalized performance characteristics are presented for the experimental compressor in terms of efficiencies, diffuser recovery, and head coefficients versus diffuser relative flow parameter, or choke margin. Peak efficiency obtained at a De Laval number of 1.16, and nondimensional specific speed of 0.15, was 34.5%.

Stage performance is found to be dominated by diffuser geometry and choke margin, plus windage losses.
Turbo-S.T.I.G.: The Turbocharged Steam Injected Gas Turbine Cycle
Authors: Foster-Pegg R. W.
Published: March 2015

In this Steam Injected Gas turbine cycle, maximum steam is raised with exhaust heat at the highest practical pressure for expansion in a back pressure steam turbine before injection into the gas turbine combustor. Additional steam is raised at lower pressure and injected into the combustor, to effect more complete recovery of heat. The back pressure steam turbine drives a topping air compressor which raises the gas cycle pressure ratio. This allows the standard gas turbine blading to accommodate the additional steam flow because of the higher pressure and density of the gas.
Use of the Brayton Cycle in Solar Electric Power Generation
Authors: Weiner Dan , Meron Giora
Published: March 2015

The utilization of gas turbines in a central receiver is an attractive alternative due to the ability of these prime movers to endure temperatures of about 2000°F while achieving high performance. In this paper the problems of modifying a 250 kW Allison Turboshaft Engine and its conversion into solar gas turbines are presented. The various solutions referring to the various system components, such as combustion chamber, hot pipeline, electric generator and control system are detailed.
MS7001F Prototype Test Results
Authors: Brandt D. E.
Published: March 2015

The MS7001F heavy–duty gas turbine has been designed utilizing advanced analytical methods and a substantial array of component tests. The integrity of the system required that the prototype unit, with its accessories, be rigorously tested under load. The factory load test was completed on May 18, 1988 after 387 hours and 134 start/stop cycles.

The MS7001F prototype gas turbine was instrumented with more than 3000 pieces of instrumentation in order to record all critical temperatures, pressures, flows, strains, displacements, and other pertinent data. The load device was a modified MS7001E compressor, which also supplied the means by which the MS7001F prototype compressor’s pressure ratio was increased to provide for surge margin determination. Inlet throttling of the MS7001F compressor allowed for full firing temperature operation, at reduced load.

The results of this factory prototype load test are reported in the paper as are observations made during post test teardown.
Heat Flux Measurements
Authors: Liebert Curt H. , Weikle Donald H.
Published: March 2015

This paper discusses a new automated, computer controlled heat flux measurement facility. Continuous transient and steady-state surface heat flux values varying from about 0.3 to 6 MW/m2 over a temperature range of 100 to 1200 K can be obtained in the facility. An application of this facility is the development of heat flux gauges for continuous fast transient surface heat flux measurement on turbine blades operating in space shuttle main engine turbopumps. The facility is also useful for durability testing at fast temperature transients.
Advanced Turbine Technology Applications Project (ATTAP): Overview, Status, and Outlook
Authors: Haley Philip J.
Published: March 2015

The ATTAP aims at proving the performance and life of structural ceramic components in the hot gas path of an automotive gas turbine engine. This Department of Energy (DOE)-sponsored, NASA-managed program is being addressed by a General Motors (GM) team drawing expertise from the Advanced Engineering Staff (AES) and from Allison. The program includes design, process development and fabrication, rig and engine testing, and iterative development of selected key ceramic components for the AGT-5 engine. A reference powertrain design (RPD) based on this engine predicts acceleration, driveability, and fuel economy characteristics exceeding those of both current engines and the DOE goals.

A low-apsect-ratio ceramic turbine rotor design has been successfully engine-demonstrated at 2200°F and 100% speed, including survival of impact and other hostile flow path conditions. Turbine flow path components have been designed for the 2500°F cycle, using improved monolithic ceramics targeted for Year 2 fabrication. Major development/fabrication efforts have been subcontracted at Carborundum, GTE Labs, Corning Glass, Garrett Ceramic Components, and Manville. Feasibility studies were initiated with Ceramics Process Systems and Drexel University.
Second Law Analysis of Gas Power Cycles
Authors: Agrawal D. D. , Chandrakar I. S.
Published: March 2015

Second Law analysis of Gas Power Cycles, used in practice, is presented. The objective of this analysis was to compute the available energy degradations and entropy creations caused by the departures from the ideal standard such as finite temperature difference in heat exchange processes and fluid friction in different pieces of equipment. Various combinations of Brayton cycle with varying irreversibilities were analysed. It was demonstrated that the decrease of shaft work output from ideal maximum, available energy degraded and the increase in the unavailable energy of the Universe are all equal. This analysis will facilitate the selection of combination of equipment which gives more favourable work output.
Dual Pressure Ratio Compressor
Authors: Paine Charles J.
Published: March 2015

The dual pressure ratio centrifugal compressor was conceived and developed as part of an advanced auxiliary power unit (APU) program (Ref. 1). The objective was to provide relatively low pressure bleed flow and high pressure turbine flow from a single stage centrifugal compressor.

Concept feasibility was first demonstrated by modifying and rig testing an existing centrifugal compressor. Subsequently, a second compressor (reference compressor), meeting the overall APU power section and bleed cycle pressure ratio requirements was designed and rig tested. This configuration was then scaled and tested in an APU.

Test results showed that the compressor efficiency and pressure ratio were approximately as predicted for the flow split off to the turbine (referred to as the turbine flow side). The bleed flow side vaneless diffuser experienced a strong flow separation. Mechanical problems were also encountered with the flow splitter shroud.

Although further development was indicated to correct the mechanical and aerodynamic problems encountered, the experiment provided a benchmark for the dual pressure ratio compressor concept.
Elevated Temperature Studies of Continuous and Discontinuous Fiber Reinforced Ceramic Matrix Composites
Authors: Majidi Azar P. , Chou Tsu-Wei
Published: March 2015

This paper reviews the analytical and experimental investigations at the Center for Composite Materials of the University of Delaware on ceramic matrix composites with continuous and discontinuous reinforcements. The focus is on the strength, fracture and creep behaviors of these composites. The experimental studies have been conducted on hot-pressed SiC whisker reinforced alumina and Nicalon SiC fiber reinforced calcium aluminosilicate (CAS) composites.
Fracture Energy for Short Brittle Fiber/Brittle Matrix Composites With Three-Dimensional Fiber Orientation
Authors: Wetherhold Robert C.
Published: March 2015

Adding brittle fibers to a brittle matrix can create a composite which is substantially tougher than the monolithic matrix by providing mechanisms for energy dissipation during crack propagation. A model based on probabilistic principles has been developed to calculate the increased energy absorption during fracture for a brittle matrix reinforced with very short, poorly bonded fibers. This model, previously developed for planar fiber orientations, is extended to consider the three-dimensional fiber orientations which may occur during composite fabrication. The fiber pull-out energy is assumed to dominate other fracture energy terms, and simple parametric studies are given to demonstrate the effect of fiber orientation, fiber length, fiber diameter, and fiber-matrix interfacial shear stress. In particular, the fiber orientation effects may be grouped into an effective “orientation parameter”. The model predictions compare satisfactorily with the limited data available, and offer a conceptual framework for considering the effect of changing the physical variables on the fracture energy of the composite.
Development of an Integrated BEM for Hot Fluid-Structure Interaction
Authors: Dargush G. F. , Banerjee P. K.
Published: March 2015

A boundary element approach is developed for problems of hot fluid-structure interaction. The structure is idealized as a thermoelastic solid, and a time-domain, boundary-only integral formulation is described. Meanwhile, several approaches are discussed for the hot fluid. Integral equations are developed for both compressible and incompressible thermoviscous flow. Due to the presence of nonlinear convective terms in the governing differential equations, domain discretization is generally required. However, with the introduction of reference velocities, volume modeling often can be confined to regions near obstacles and walls.

All formulations are implemented for two-dimensional problems in GP-BEST, a general purpose boundary element computer program. An overview of this numerical implementation is provided, along with several illustrative examples. The present fluid formulations are appropriate in the low to medium Reynolds number ranges, however, some enhancements required for higher speed simulations are noted.
Application of Host Technology to the SSME HPFTP Blade
Authors: McKnight R. L. , Cook T. S. , Bechtel G. S. , Huang H. T.
Published: March 2015

The Hot Section Technology (HOST) program has focussed on providing methods to solve difficult structural analysis problems. Few structures require as much effort to analyze as the modern aircraft gas turbine engine; heat transfer, constitutive relations, linear and nonlinear analysis, multiple advanced materials are some of the key topics requiring attention in the structural analysis of engine components. Usually based on limited information and experience, these advanced methods must evolve from expert systems to widely verified user friendly techniques available to the design community. This paper will discuss the development of turbine blade analysis tools as they moved from research contracts under the NASA HOST program to a PC based system for preliminary design and their use in evaluating the SSME HPFTP blade, a similar but subtly different problem. Included in the discussion will be the heat transfer and structural analysis of the blade, development of a data base for constitutive modelling of the blade materials, including coatings, and the usage of advanced nonlinear finite element methods.
Viscous Flow in a Controlled Diffusion Compressor Cascade With Increasing Incidence
Authors: Elazar Y. , Shreeve R. P.
Published: March 2015

A detailed two-component LDV mapping of the flow through a controlled diffusion compressor cascade at low Mach number (∼0.25) and Reynolds number of about 7×105, at three inlet air angles from design to near stall, is reported. It was found that the suction side boundary layer reattached turbulent after a laminar separation bubble, and remained attached to the trailing edge even at the highest incidence, at which losses were 3 to 4 times the minimum value for the geometry. Boundary layer thickness increased to fill 20% of the blade passage at the highest incidence. Results for pressure-side boundary layer and near wake are also summarized. Information sufficient to allow preliminary assessment of viscous codes is tabulated.
Numerical Optimization of Axial Compressor Designs
Authors: Hearsey Richard M.
Published: March 2015

An application of numerical optimization to axial compressor design is illustrated in this paper. A design-point efficiency model is coupled to an optimization routine to create a method of deriving designs that are optimized for efficiency. Numerous constraints, many non-linear, are applied to control parameters to which the efficiency model is insensitive, such as rotor hub choking. The High Pressure Compressor of the Energy Efficient Engine that was designed for NASA by the General Electric Company is used as a vehicle to demonstrate the potential merits of the procedure; design-point efficiency increases of several points are projected for optimized designs.
Compressor Redesign for the CW251B12 Gas Turbine
Authors: Marson Ezio
Published: March 2015

The different aspects of the CW251B12 compressor redesign intended for possible upgrading of currently installed B10 engines and for the B12 model are described in this paper. The design philosophy is based upon experience with previous compressor upratings. Aerodynamic and mechanical considerations as well as description of the new features introduced into the redesigned compressor are included in the paper. Generalized compressor design rules are also presented.
Three-Dimensional Relief in Turbomachinery Blading
Authors: Wadia A. R. , Beacher B. F.
Published: March 2015

The leading edge region of turbomachinery blading in the vicinity of the endwalls is typically characterized by an abrupt increase in the inlet flow angle and a reduction in total pressure associated with endwall boundary layer flow. Conventional two-dimensional cascade analysis of the airfoil sections at the endwalls indicates large leading edge loadings, apparently detrimental to the performance. However, experimental data exist that suggest that cascade leading edge loading conditions are not nearly as severe as those indicated by a two-dimensional cascade analysis. This discrepancy between two-dimensional cascade analyses and experimental measurements has generally been attributed to inviscid three-dimensional effects. This article reports on two- and three-dimensional calculations of the flow within two axial flow compressor Stators operating near their design points. The computational results of the three-dimensional analysis reveal a significant three-dimensional relief near the casing endwall absent in the two-dimensional calculations. The calculated inviscid three-dimensional relief at the endwall is substantiated by airfoil surface static pressure measurements on low speed research compressor blading designed to model the flow in the high speed compressor. A strong spanwise flow towards the endwall along the leading edge on the suction surface of the airfoil is responsible for the relief in the leading edge loading at the endwall. This radial migration of flow results in a more uniform spanwise loading compared to that predicted by two-dimensional calculations.
A Review of Failure Models for Ceramic Matrix Composite Laminates Under Monotonic Loads
Authors: Tripp David E. , Hemann John H. , Gyekenyesi John P.
Published: March 2015

Ceramic matrix composites offer significant potential for improving the performance of turbine engines. In order to achieve their potential, however, improvements in design methodology are needed. In the past most components using structural ceramic matrix composites were designed by “trial and error” since the emphasis on feasibility demonstration minimized the development of mathematical models. To understand the key parameters controlling response and the mechanics of failure, the development of structural failure models is required. A review of short term failure models with potential for ceramic matrix composite laminates under monotonic loads is presented. Phenomenological, semi-empirical, shear-lag, fracture mechanics, damage mechanics, and statistical models for the fast fracture analysis of continuous fiber unidirectional ceramic matrix composites under monotonic loads are surveyed.
Verification of an Impeller Design by Laser Measurements and 3D-Viscous Flow Calculations
Authors: Krain H. , Hoffman W.
Published: March 2015

Laser measurements and 3D-viscous calculations were performed to verify the design of a 30deg. backswept impeller with advanced blade geometry and high design rotor pressure ratio (πt12=4.7:1). Both, measured and calculated results are in good agreement. They are pointing to a low velocity area inside the rotor that vanishes toward the exit resulting in comparatively smooth discharge velocity profiles. The rotor geometry used for the verification is released. The application of the 3D-viscous calculation code now embedded in an impeller design procedure and its support by a number of pre- and postprocessing programs is described.
LDV Measurements and Investigation of Flow Field Through Radial Turbine Guide Vanes
Authors: Eroglu Hasan , Tabakoff Widen
Published: March 2015

The results of LDV measurements and investigation of the detailed flow field in a radial inflow turbine nozzle are presented. The flow velocities were measured at upstream, inside and downstream of the nozzle blades for two different mass flow rates, using a three-component LDV system. Results are presented as contour plots of mean velocities, flow angles and turbulence intensities. The flow field inside the nozzle blade passages were found to be strongly influenced by the upstream scroll geometry. Significant end wall cross flows and flow mixing were observed. The flow turbulence increased in the downstream flow direction. The LDV mean flow results on the blade-to-blade plane at midspan location were also compared with an inviscid, “panel method” solution.
Gas Turbine Applications of Abrasive Flow Machining
Authors: Perry Winfield B. , Stackhouse John
Published: March 2015

Abrasive Flow Machining (AFM) is a non-traditional finishing method used for precision deburring, edge contouring, surface improvement and the removal of abusive machining and thermal recast layers. A firm-bodied abrasive laden compound is flowed at pressures of 75–500 psi (5–35 bar) across selective features of a fixtured workpiece. Gas turbine components benefited by this method include: axial and centrifugal rotors, stators, turbine blades, compressor and turbine disks, shafts, seals and other rotating parts. AFM process principles are explained and specific applications are reviewed.
Injection Molding Development of Ceramic Turbine Components
Authors: Ohnsorg R. W. , Eyck M. O. Ten , Friedman W. D. , Engler P. , Havrilla G. J. , Armstrong E. E.
Published: March 2015

Ceramic fabrication development of large static components has been an integral part of the U.S. Government sponsored gas turbine development programs. Carborundum has produced sintered alpha silicon carbide transition ducts which have been successfully tested in Garrett’s AGT 101 engine having a turbine inlet temperature of 2500°F. Injection molding as opposed to isopressing/green machining was chosen for the development project because of its near net shape capability and high volume potential.

Mold design is important to minimize internal flaws and provide uniform green density. Injection molding control variables also influence external surface quality as determined by knit lines and blisters. Statistically designed three level experiments were instrumental in isolating the control variables which influence part quality and to determine their optimum values. Flow modeling was used to verify field trials and optimize specific molding variables to minimize pressure, shear rate and shear stress gradients within the part as well as suggest gating options.

Destructive and nondestructive evaluation was then used to evaluate the quality of ducts at various processing steps. Dual energy tomography and X-ray fluorescence are being developed as techniques for measuring the density and composition of molded parts.
Small Cogeneration in Industry: Requirements and Solutions With an Efficient Gas Turbine
Authors: Benvenuti Erio , Stecco Sergio S.
Published: March 2015

This paper examines some of the major problems connected with cogeneration in some typical industrial sectors. A prior study of the impact of monitorized energy consumption on the choice of cogeneration solution showed that:

- In the 0.5–3.0 MW range: Gas turbines with heat recovery represent an appealing solution in terms of overall plant costs.

- In the 0.5–0.8 MW range: Industry characteristics must be better clarified before dealing with competition from internal combustion (IC) reciprocating engines.

This study served to establish the design guidelines for the NuovoPignone PGT2 gas turbine, rated at 2 MW, with a 25% efficiency at the generator terminals. The design exhaust temperature of 550°C is well suited to cogeneration applications in the types of industry investigated (textile-, cement-, and paper-making). However, in other cases such as nonindustrial cogeneration, where very low electricity costs are desirable, the available regenerative cycle option has a potential electrical efficiency of over 28% at lower exhaust temperatures and heat levels.
The Effect of Density Ratio on the Heat Transfer Coefficient From a Film Cooled Flat Plate
Authors: Ammari H. D. , Hay N. , Lampard D.
Published: March 2015

The effect of density ratio of cooling films on the heat transfer coefficient on a flat plate is investigated using a heat-mass transfer analogy. The experimental technique employed uses a swollen polymer surface and laser holographic interferometry. A density ratio of 1.0 was achieved using air as the injectant. Density ratios of 1.38 and 1.52, representative of turbine operating conditions, were obtained by using foreign gases.

The coolant fluids were injected at various blowing rates through a single normal hole or through a row of holes spaced at three-diameter intervals, and inclined at 35° or 90° to the mainstream direction. The experiments were conducted under isothermal conditions in a subsonic, zero mainstream pressure gradient turbulent boundary layer. The results indicated large differences in behaviour between the two injection angles. For normal injection, the heat transfer coefficient at a fixed blowing parameter was insensitive to the variation of density ratio, whereas for 35° injection strong dependence was observed. Scaling parameters for the heat transfer data have been proposed so that use can be made of data obtained at density ratios not representative of gas turbine practice. In addition, a correlation for normal injection data has been formulated.
Application of a Low Reynolds Number k-ϵ Turbulence Model to High-Speed Rotating Cavity Flows
Authors: Morse A. P.
Published: March 2015

A low turbulence Reynolds number k-ϵ model has been used in conjunction with an elliptic flow calculation procedure to obtain finite-difference solutions for radial outflow in the cavity formed between two plane corotating discs and an outer peripheral shroud. Air enters the cavity axially through a central hole in one of the discs and is assumed to leave via a uniform sink layer adjacent to the shroud.

The main emphasis of the paper is the extension of the solution procedure to cover high rotational speeds, with rotational Reynolds numbers up to 107. As a necessary prerequisite to this exercise, the turbulence model is validated by its good predictive accuracy of existing experimental data up to a maximum rotational Reynolds number of 1.1 × 106.
Experimental and Theoretical Study of the Swirling Flow in Centrifugal Compressor Volutes
Authors: Van Den Braembussche R. A. , Hände B. M.
Published: March 2015

Measurements of the three-dimensional flow in a simplified model of a centrifugal compressor volute at design and off-design operation are presented.
Impingement/Effusion Cooling: The Influence of the Number of Impingement Holes and Pressure Loss on the Heat Transfer Coefficient
Authors: Al Dabagh A. M. , Andrews G. E. , Abdul Husain R. A. A. , Husain C. I. , Nazari A. , Wu J.
Published: March 2015

Measurements of the overall heat transfer coefficient within an impingement/effusion cooled wall are presented. The FLUENT CFD computer code has been applied to the internal aerodynamics to demonstrate the importance of the internal recirculation in the impingement gap. This generates a convective heat transfer to the impingement jet and measurements of this heat transfer plate coefficient are presented that show it to be approximately a half of the impingement/effusion heat transfer coefficient. The influence of the relative pressure loss or X/D between the impingement and effusion was investigated, for an effusion X/D of 4.67 and a Z of 8 mm, and shown to be only significant at high G where a reduction in h of 20% occurred. Increasing the number of holes, N, in the impingement/effusion array at a constant Z of 8 mm reduced h by 20%, mainly due to the higher Z/D for the smaller holes at high N. Reduced numbers of impingement holes relative to the effusion holes, in a ratio of 1 to 4, were shown to have a small influence on h with a maximum reduction in h of 20% at high G and a negligible effect at low G.
Comparative Controller Design for a Marine Gas Turbine Propulsion System
Authors: Smith David L. , Stammetti Vincent A.
Published: March 2015

Controller design for marine gas turbine systems should consider three measures of performance: transient control, steady state accuracy, and distrubance rejection. This paper presents and compares two common types of controller designs in terms of these measures. The goal of the controllers was shaft speed control. To meet this goal, a classical Proportional-plus-integral controller was designed and compared to a modern Linear Quadratic Regulator design. The controllers’ performances were evaluated with respect to the three measures mentioned above, with disturbances being input as oscillations in shaft torque due to seaway cycling.
Aerodynamics of Cooling Jets Introduced in the Secondary Flow of a Low Speed Turbine Cascade
Authors: Bario F. , Leboeuf F. , Onvani A. , Seddini A.
Published: March 2015

The aerodynamic behaviour of cold discrete jets in a cold secondary flow is investigated. Configurations including single jets and rows of jets are studied.

These jets are introduced through the side wall of a low speed nozzle turbine cascade. The experimental set up and the jet behaviour are fully described.

The effects of location with respect to the blades, mass flow ratio, yaw and incidence angles on the aerodynamics of single jets are investigated. The influence of neighbouring jets is detailed in the case of multiple jet configurations. The interaction with the secondary flow is presented. The local pressure and velocity fields, trajectories and visualizations are discussed. The measuring apparatus includes a five hole probe and an hot wire for intermittency measurements.
United States Navy Gas Turbine Propulsion Machinery Systems Testing
Authors: Nufrio Robert P. , McNamara James
Published: March 2015

Significant U.S. Navy controlled land based testing has been successfully conducted on gas turbines and gas turbine main propulsion systems since the early 1950’s. Through the success of these tested systems, largely as a result of successful land based testing, the demand for gas turbine powered main propulsion systems has been steadily increasing. Consequently, gas turbine technology, its applications, and required test capabilities are constantly being developed to meet future U.S. Navy requirements.
Experimental Investigation Into the Effects of Rotating and Static Bolts on Both Windage Heating and Local Heat Transfer Coefficients in a Rotor/Stator Cavity
Authors: Millward J. A. , Robinson P. H.
Published: March 2015

Experiments have been carried out over fully representative ranges of Rotational Reynolds Number ρωr2μ and Throughflow Reynolds Number m.μr into the effects of single row and multi rows of bolts on both windage and local disc surface heat transfer coefficients. Experiments were carried out on the following combinations; single row rotating, single row static, double row rotating and combined rotating and static. Different sizes of bolts were tested as was variation in pitching and the effects of various bolt shields.

The Adiabatic Wall Temperature (AWT) was measured locally at various positions on the rotor surface both between adjacent bolts and at different pitch circle diameters. Using measured AWT and local rotor surface temperatures the local Nusselt numbers were obtained. In addition an effective Nusselt number for heat transfer into the disc through an actual bolt was obtained by the use of specially instrumented bolts.

In the course of the testing, surprising results were obtained for one particular disc profile. A considerable reduction in windage due to the shape of the disc surface near the rim was measured.

The paper describes the experimental technique used and presents a selection of the windage and heat transfer results.
Measurements of Unsteady Flow Over and Heat Transfer From a Flat Plate
Authors: Liu X. , Rodi W.
Published: March 2015

A detailed experimental investigation is described of unsteady flow over and heat transfer from a flat plate. The oncoming 2-D periodic unsteady flow was generated by a squirrel cage device mounted upstream of the plate. Velocity measurements were carried out in the free stream over the plate and in the boundary layer by hot-wire anemometers, and the distributions of pressure and heat transfer coefficient along the plate surface were measured, the latter with a glue-on hot film. All results are presented in ensemble averaged form so that the unsteady flow processes can be studied phase by phase.
Simulation of Cooling Film Density Ratios in a Mass Transfer Technique
Authors: Ammari H. D. , Hay N. , Lampard D.
Published: March 2015

A systematic investigation of the influence of molecular Schmidt number on cooling film mass transfer coefficient has been conducted using a swollen polymer technique and laser holographic interferometry. A variation in Schmidt number by about 28% was accomplished by injection of a foreign gas and gas mixtures through a single normal hole at a blowing rate of one. The experiments were performed at a constant temperature in a subsonic, zero mainstream pressure gradient turbulent boundary layer on a flat plate.

The experimental results indicate that Schmidt number has a negligible effect on cooling film mass transfer coefficient within the range examined. Consequently, measurement of cooling film mass transfer coefficients at non-unity density ratios using a mass transfer method with foreign gas injection is experimentally validated.
Sequential Linearization as an Approach to Real Time Marine Gas Turbine Simulation
Authors: Smith David L. , Stammetti Vincent A.
Published: March 2015

A real time marine gas turbine simulation would offer an essential basis for advanced marine propulsion control designs. Such designs may be realized as model reference controllers and/or health monitoring controllers. This paper presents an approach to real time turbine simulation using a method of sequential state space linearizations. The linearizations are shown to be simple enough to be computed in real time. Comparisons between simulations and experiments are presented and discussed. The approach is shown to have very good accuracy for both transient and steady state predictions.
Adaptive Simulation of Gas Turbine Performance
Authors: Stamatis A. , Mathioudakis K. , Papailiou K. D.
Published: March 2015

A method is presented allowing the simulation of Gas Turbine performance with the possibility of adapting to engine particularities. Measurements along the gas path are used, in order to adapt a given performance model by appropriate modification of the component maps. The proposed method can provide accurate simulation for engines of the same type, differing due to manufacturing or assembly tolerances. It doesn’t require accurate component maps, as they are derived during the adaptation process. It can also be used for health monitoring purposes, introducing thus a novel approach for component condition assessment. The effectiveness of the proposed method is demonstrated by application to an industrial Gas Turbine.
Ultra High Bypass (UHB) Engine Critical Component Technology
Authors: Cloft Thomas G. , Muldoon Patricia L.
Published: March 2015

The commercial air transport industry is on the threshold of the Ultra High Bypass (UHB) engine era, which will usher in another leap forward in fuel efficient, low noise gas turbine engines. Anticipation of propulsion system requirements has led to implementation of advanced technology development supporting both the Counter Rotation Propfan (CRP) and the Advanced Ducted Prop (ADP) concepts. The paper will review the advanced cycles for these concepts, definition of critical component technology and the technology readiness programs underway at Pratt & Whitney (P&W).