bluuebunny/crossref_metadata_2025 huggingface dataset:
Immunomodulating properties of protein hydrolysates for application in cow's milk allergy
Authors: Kiewiet M. B. G. , Gros M. , van Neerven R. J. J. , Faas M. M. , de Vos P.
Published: February 2015

Cow's milk proteins cause allergic symptoms in 2–3% of all infants. In these individuals, the tolerogenic state of the intestinal immune system is broken, which can lead to sensitization against antigens and eventually to allergic responses. Although a true treatment for food allergy is not available, symptoms can be avoided by providing the infants with hydrolyzed proteins. Hydrolyzed proteins are proteins that are enzymatically degraded. They lack typical allergenic IgE‐binding epitopes but are also thought to play a pertinent role in other mechanisms inducing hypoallergenic effects. This review discusses the mechanisms and evidence for immunomodulating properties of cow's milk hydrolysates. Hydrolysates are found to strengthen the epithelial barrier, modulate T‐cell differentiation, and decrease inflammation. Some studies suggest a role for hydrolysates in manipulating pathogen recognition receptors signaling as underlying mechanism. Peptides from hydrolysates have been shown to bind to TLR2 and TLR4 and influence cytokine production in epithelial cells and macrophages. Current insight suggests that hydrolysates may actively participate in modulating the immune responses in subjects with cow's milk allergy and those at risk to develop cow's milk allergy. However, more research is required to design effective and reproducible means to develop targeting strategies to modulate the immune response.
Lichenoid Drug Eruption After Human Papillomavirus Vaccination
Authors: Laschinger Mary E. , Schleichert Rachel A. , Green Brian
Published: February 2015

Lichenoid drug reactions have been linked to a long and growing list of medications, most of which are used mainly in adults, making these reactions exceedingly rare in children. To the best of our knowledge, this case report is the first of a lichenoid drug eruption in a child after human papillomavirus vaccination.
Pigmented Purpuric Dermatosis: Clinicopathologic Characterization in a Pediatric Series
Authors: Coulombe Jérôme , Jean Sara‐Elizabeth , Hatami Afshin , Powell Julie , Marcoux Danielle , Kokta Victor , McCuaig Catherine
Published: February 2015

Pigmentary purpuras (PPs) are a group of chronic disorders of unknown origin seldom described in children. With this study we sought to better characterize PP eruptions, including clinical evolution and management. A retrospective chart review from 2003 to 2013 querying characteristics of children with a biopsy‐proven diagnosis of PP in the Centre Hospitalier Universitaire Ste‐Justine dermatology clinic (Montreal, Quebec, Canada) was performed. Follow‐up was obtained through telephone interviews. Descriptive statistical analysis was used. Of the 17 subjects, 8 were male and the mean age of onset was 9 years. PP was asymptomatic in 11 patients, pruritic in 3, and of cosmetic concern in 3. Schamberg's disease was the most frequent subtype in 12 cases. Resolution of PP was found in 13 cases with a median duration of less than 1 year (range 6 months–9 years). Five patients experienced spontaneous clearing without treatment, and improvement was observed in 75% of cases treated with topical corticosteroids and 100% with narrowband ultraviolet B (nbUVB). No associated disease, significant drug exposure, or contact allergens were found. Those findings support that PPs in children are idiopathic, chronic eruptions that can benefit from watchful waiting, although topical corticosteroids or nbUVB are may be useful if the patient or family desires faster resolution. This study was limited by its small size, its retrospective nature, and selection and recall bias.
Nevus Anemicus: A Distinctive Cutaneous Finding in Neurofibromatosis Type 1
Authors: Hernández‐Martín Angela , García‐Martínez Francisco Javier , Duat Anna , López‐Martín Inmaculada , Noguera‐Morel Lucero , Torrelo Antonio
Published: February 2015

Nevus anemicus (NA) is a cutaneous anomaly characterized by pale, well‐defined patches with limited vascularization after rubbing. They are largely known to be associated with neurofibromatosis 1 (NF1) and have received little attention in the literature until recently. We sought to characterize the prevalence and clinical features of patients with NA and NF1. We conducted an observational prospective study of 99 children with NF1 at the Hospital Niño Jesús, Madrid, Spain, from January 1, 2012, through July 31, 2013, and reviewed three other series of patients with NF1 and NA recently reported. The prevalence of NA in children with NF1 ranged from 8.8% to 51%, being much more prevalent at younger ages. Prospective studies yielded a higher prevalence than retrospective studies. NA was located most commonly on the trunk, particularly on the anterior chest wall, and was often multiple. Patients with segmental NF1 or isolated café au lait spots rarely had NA, and NA was absent in other genodermatoses. The collection of data was not homogeneous in all studies. NA has a high prevalence in individuals with NF1 patients but seems to be absent in connection with other genodermatoses, therefore its presence can assist in the diagnosis of suspected cases of NF1. The subtle clinical appearance of NA makes its detection difficult, and physicians involved in the care of children with NF1 must be aware of its possible presence and significance.
Growth Hormone Induces Recurrence of Infantile Hemangiomas After Apparent Involution: Evidence of Growth Hormone Receptors in Infantile Hemangioma
Authors: Munabi Naikhoba C. O. , Tan Qian Kun , Garzon Maria C. , Behr Gerald G. , Shawber Carrie J. , Wu June K.
Published: February 2015

Infantile hemangiomas (IHs) are the most common benign tumor of infancy, characterized by a natural history of early proliferation in the first months of life to eventual involution during childhood, often with residual fibrofatty tissue. Once involution has been achieved, IHs do not typically recur. We present two cases of exogenous growth hormone therapy resulting in the recurrence of IHs in late childhood, supported by radiological, immunohistochemical, in vitro, and in vivo evidence.
The impact of rituximab in ABO‐incompatible pediatric living donor liver transplantation: The experience of a single center
Authors: Okada Noriki , Sanada Yukihiro , Hirata Yuta , Yamada Naoya , Wakiya Taiichi , Ihara Yoshiyuki , Urahashi Taizen , Miki Atsushi , Kaneda Yuji , Sasanuma Hideki , Fujiwara Takehito , Sakuma Yasunaru , Shimizu Atsushi , Hyodo Masanobu , Yasuda Yoshikazu , Mizuta Koichi
Published: February 2015

Previous studies have demonstrated the safety of ABO‐incompatible pediatric LDLT using preoperative plasmapheresis and rituximab; however, no reports have described the timing and dosage of rituximab administration for pediatric LDLT. This study aimed to describe a safe and effective dosage and timing of rituximab for patients undergoing pediatric ABO‐incompatible LDLT based on the experience of our single center. A total of 192 LDLTs in 187 patients were examined. These cases included 29 ABO‐incompatible LDLTs in 28 patients. Rituximab was used beginning in January 2004 in recipients older than two yr of age (first period: 375 mg/m2 in two cases; second period: 50 mg/m2 in two cases; and 200 mg/m2 in eight cases). Two patients who received 375 mg/m2 rituximab died of Pneumocystis carinii pneumonia and hemophagocytic syndrome. One patient who received 50 mg/m2 rituximab required retransplantation as a consequence of antibody‐mediated complications. All eight patients administered 200 mg/m2 survived, and the mean CD20+ lymphocyte count was 0.1% at the time of LDLT. In the preoperative management of patients undergoing pediatric ABO‐incompatible LDLT, the administration of 200 mg/m2 rituximab three wk prior to LDLT was safe and effective.
Research Constituents and Authorship Patterns in the Production and Operations Management Journal
Authors: Saladin Brooke A. , Shang Guangzhi , Fry Timothy D. , Donohue Joan M.
Published: February 2015

The Production and Operations Management Society is the largest professional society dedicated to creating and disseminating knowledge in product and process design, operations, and supply chains for the management of manufacturing and services. Its research journal, Production and Operations Management ( POM), covers all topics in the discipline and all research paradigms to serve the entire community. Since its inception in 1992, POM has become recognized as a top tier outlet for operations management research. We identify research institutions in the operations management community that have played major roles in developing the journal based on the research of their faculty members and doctoral graduates. Our findings show that the constituency of the journal reflects the constituency of the society.
Effects of Knowledge on Attitude Formation and Change Toward Genetically Modified Foods
Authors: Zhu Xiaoqin , Xie Xiaofei
Published: February 2015

In three waves, this study investigates the impact of risk and benefit knowledge on attitude formation toward genetically modified (GM) foods as well as the moderating effect of knowledge level on attitude change caused by receiving information. The data in Wave 1 (N = 561) demonstrate that both benefit and risk knowledge either directly contribute to attitude formation or indirectly affect attitudes through the mediating roles of benefit and risk perceptions. Overall, benefit and risk knowledge affect consumer attitudes positively and negatively, respectively. In Wave 2, 486 participants from Wave 1 were provided with information about GM foods, and their attitudes were assessed. Three weeks later, 433 of these participants again reported their attitudes. The results indicate that compared with the benefit and mixed information, risk information has a greater and longer lasting impact on attitude change, which results in lower acceptance of GM foods. Furthermore, risk information more strongly influences participants with a higher knowledge level. The moderating effect of knowledge on attitude change may result from these participants’ better understanding of and greater trust in the information. These findings highlight the important role of knowledge in attitude formation and attitude change toward GM foods as well as the necessity of considering the determinants of attitude formation in attitude change studies.
Phenothiazine‐Derived Antipsychotic Drugs Inhibit Dynamin and Clathrin‐Mediated Endocytosis
Authors: Daniel James A. , Chau Ngoc , Abdel‐Hamid Mohammed K. , Hu Lingbo , von Kleist Lisa , Whiting Ainslie , Krishnan Sai , Maamary Peter , Joseph Shannon R. , Simpson Fiona , Haucke Volker , McCluskey Adam , Robinson Phillip J.
Published: February 2015

Chlorpromazine is a phenothiazine‐derived antipsychotic drug (APD) that inhibits clathrin‐mediated endocytosis (CME) in cells by an unknown mechanism. We examined whether its action and that of other APDs might be mediated by the GTPase activity of dynamin. Eight of eight phenothiazine‐derived APDs inhibited dynamin I (dynI) in the 2–12 µm range, the most potent being trifluoperazine (IC50 2.6 ± 0.7 µm). They also inhibited dynamin II (dynII) at similar concentrations. Typical and atypical APDs not based on the phenothiazine scaffold were 8‐ to 10‐fold less potent (haloperidol and clozapine) or were inactive (droperidol, olanzapine and risperidone). Kinetic analysis showed that phenothiazine‐derived APDs were lipid competitive, while haloperidol was uncompetitive with lipid. Accordingly, phenothiazine‐derived APDs inhibited dynI GTPase activity stimulated by lipids but not by various SH3 domains. All dynamin‐active APDs also inhibited transferrin (Tfn) CME in cells at related potencies. Structure–activity relationships (SAR) revealed dynamin inhibition to be conferred by a substituent group containing a terminal tertiary amino group at the N2 position. Chlorpromazine was previously proposed to target AP‐2 recruitment in the formation of clathrin‐coated vesicles (CCV). However, neither chlorpromazine nor thioridazine affected AP‐2 interaction with amphiphysin or clathrin. Super‐resolution microscopy revealed that chlorpromazine blocks neither clathrin recruitment by AP‐2, nor AP‐2 recruitment, showing that CME inhibition occurs downstream of CCV formation. Overall, potent dynamin inhibition is a shared characteristic of phenothiazine‐derived APDs, but not other typical or atypical APDs, and the data indicate that dynamin is their likely in‐cell target in endocytosis.
p120‐Catenin modulating nuclear factor‐κB activation is partially RhoA/ROCKdependent in scratch injury
Authors: Qin Shenghui , Qin Lingzhi , Zhang Chao , Liu Liwei , Sun Wenjia , Li Naping , Wu Renliang , Wang Xi
Published: February 2015

p120‐catenin (p120) is known as a cadherin‐associated protein that participates in tumor metastasis and invasion, as well as an anti‐inflammatory mediator. Recently, its anti‐inflammatory role is drawing increasing attention, but the regulatory mechanisms are still unknown. Here, we report that p120 modulated inflammatory responses partially depends on RhoA/ROCK pathway in scratch‐induced injury in human bronchial epithelial cells (BECs). For the first time, we found that p120 was significantly reduced in BECs after scratching, which could induce interleukin‐8 (IL‐8) production through nuclear factor‐κB (NF‐κB) activation accompanied with IκBα phosphorylation. Over‐expression of p120 3A could inhibit NF‐κB activation and IL‐8 mRNA expression and protein synthesis after scratching, while p120 knockdown by small interfering RNA could promote NF‐κB activation and IL‐8 mRNA expression and protein synthesis after scratching. Furthermore, we found that RhoA was the binding partner of p120 in BECs. Although total RhoA and p120‐binded RhoA remained unchanged, the RhoA activity was increased after scratching. Chemical blockade of RhoA/ROCK signaling (Y27632) inhibited scratch‐induced nuclear translocation of NF‐κB p65. Over‐expression of p120 3A attenuated scratch‐induced RhoA activation, whereas silence of p120 significantly elevated scratch‐induced RhoA activation in BCEs. Conclusively, these results indicate an anti‐inflammatory effect of p120 in bronchial epithelial cells through its modulation of NF‐κB signaling depending on RhoA/ROCK pathway.
Effects of saliva on early post–tooth extraction tissue repair in rats
Authors: Mohn Claudia E. , Steimetz Tammy , Surkin Pablo N. , Fernandez‐Solari Javier , Elverdin Juan C. , Guglielmotti María B.
Published: February 2015

The aim of the present study was to perform a biochemical, histological, and histomorphometrical evaluation of the mechanisms involved in tissue repair in rats subjected to submandibulectomy‐induced hyposialia, 24, 48, and 72 hours of post–tooth extraction. We studied the correlation between the lack of submandibular saliva and the modulation of inflammatory mediators involved in tissue repair, such as prostaglandin E2, nitric oxide (NO), and tumor necrosis factor alpha (TNF‐α). Rats with hyposialia showed a delay in socket healing, slow replacement of the clot with granulation tissue, and fewer cells and collagen fibers, concomitant with a longer inflammatory process, as compared to controls. The lack of saliva induced by submandibulectomy modified the levels of prostaglandin E2, NO, and TNF‐α, and tissue response in the early stages of wound healing compared to controls, and could thus determine alterations in later osteogenic response. Our results allow concluding that hyposialia modulates the parameters of inflammation studied here, and that it is essential for optimal healing. Therefore, these findings provide evidence for the importance of submandibular saliva to final bone socket healing.
An Investigation on the Implications of Design Process Phases on Artifact Novelty
Authors: Ozge Ozaltin Nur , Besterfield-Sacre Mary , Okudan Kremer Gül E. , Shuman Larry J.
Published: February 2015

Innovation, including engineering innovation, is essential for economic growth. Currently, while most design practices in engineering education focus on aspects of “good” technical design, elements of innovation may be neglected. This research investigates design process activities that yield innovative artifacts. Specifically, we examine the types of design activities, their timing, and the associations among each other. Specifically, two research questions are explored. First, what design activities do teams engage in that relate to the innovativeness of the resultant design artifact? Second, how do these design activities impact the succeeding activities across the design process (from problem definition to working prototype (WP))? To explore these questions, 16 senior capstone bioengineering design teams are followed as they advance from initial conceptualization to WP over an average 23 week period. Several significant measures suggest that innovative teams differ from their noninnovative counterparts in terms of what activities they engage in, how much they engage in the particular activities, and in what phase they conduct the activities. Specifically, certain activities utilized in the early phase (e.g., marketing) are essential for innovation. Moreover, in terms of iterations through activities, spending significant time and effort while developing a design, as well as having smooth, rich iterations throughout the process contribute to the innovativeness of the artifact.
Leading Edge Film Cooling of a Turbine Blade Model Through Single and Double Row Injection: Effects of Coolant Density
Authors: Salcudean M. , Gartshore I. , Zhang K. , Barnea Y.
Published: February 2015

Experiments have been conducted on a large model of a turbine blade. Attention has been focussed on the leading edge region, which has a semi-circular shape and four rows of film cooling holes positioned symmetrically about the stagnation line. The cooling holes were oriented in a spanwise direction with an inclination of 30° to the surface, and had streamwise locations of ±15° and ±44° from the stagnation line. Film cooling effectiveness was measured using a heat/mass analogy. Single row cooling from the holes at 15° and 44° showed similar patterns: spanwise averaged effectiveness which rises from zero at zero coolant mass flow to a maximum value η* at some value of mass flow ratio M*, then drops to low values of η at higher M. The trends can be quantitatively explained from simple momentum considerations for either air or CO2 as the coolant gas. Close to the holes, air provides higher η values for small M. At higher M, particularly farther downstream, the CO2 may be superior. The use of an appropriately defined momentum ratio G collapses the data from both holes using either CO2 or air as coolant onto a single curve. For η*, the value of G for all data is about 0.1. Double row cooling with air as coolant shows that the relative stagger of the two rows is an important parameter. Holes in line with each other in successive rows can provide improvements in spanwise averaged film cooling effectiveness of as much as 100% over the common staggered arrangement. This improvement is due to the interaction between coolant from rows one and two, which tends to provide complete coverage of the downstream surface when the rows are placed correctly with respect to each other.
Turbulence Intensity and Length Scale Measurements in Multistage Compressors
Authors: Camp T. R. , Shin H.-W.
Published: February 2015

This paper describes the measurement and processing of turbulence data from multistage low-speed compressors. Measurements were made at the same relative positions in three four-stage compressors, each having different levels of the design stage loading coefficient.

A new method of data processing to calculate turbulence intensities and integral length scales is outlined. Using this method, integral length scales have been measured in turbomachinery flows for the first time. It is shown how the turbulence intensity and integral length scale vary with position in the blade passage, with changing flow coefficient and with the value of the design stage loading coefficient.

The results have been used to specify representative inlet conditions for experimental rigs and to improve the application of CFD turbulence models to turbomachinery modeling.
AGATA: A European Ceramic Gas Turbine for Hybrid Vehicles
Authors: Lundberg Robert
Published: February 2015

The European EUREKA project EU 209 or AGATA - Advanced Gas Turbine for Automobiles is a program dedicated to the development of three critical ceramic components; i. catalytic combustor, ii. radial turbine wheel, iii. static heat exchanger, designed for a 60 kW turbogenerator for a hybrid electric vehicle. The objective is to develop and test the three components as a full scale feasibility study with an industrial perspective. The AGATA partners represent car manufacturers as well as companies and research institutes in the turbine, catalyst and ceramic material fields in France and Sweden.
Status of the Automotive Ceramic Gas Turbine Development Program: Year 3 Progress
Authors: Itoh Takane , Kimura Hidetomo
Published: February 2015

Under the ongoing seven-year program, designated “Research and Development of Automotive Ceramic Gas Turbine Engine (CGT Program)”, started in June 1990. Japan Automobile Research Institute. Inc. (JARI) is continuing to address the issues of developing and demonstrating the advantageous potentials of ceramic gas turbines for automotive use. This program has been conducted by the Petroleum Energy Center (PEC) with the financial support of MITI.

The basic engine is a 100 kW, single-shaft regenerative engine having a turbine inlet temperature of 1350°C and a rotor speed of 110,000 rpm. In the third year of this program, the experimental evaluation of the individual engine components and various assembly tests in a static thermal test rig were continued. Exhaust emissions were also measured in a performance test rig for an initially designed pre-mixed, pre-vaporized lean (PPL) combustor. A maximum speed of 130,700 rpm was obtained during hot spin tests of delivered ceramic turbine rotors, which was almost the same level as during cold spin tests. A dynamic thermal test including a centrifugal compressor, a ceramic radial turbine rotor and all the ceramic stationary hot parts was initiated.
Flow and Heat Transfer Behavior in Transitional Boundary Layers With Streamwise Acceleration
Authors: Keller F. Jeffrey , Wang Ting
Published: February 2015

The effects of streamwise acceleration on a two-dimensional heated boundary layer undergoing natural laminar-turbulent transition were investigated with detailed measurements of momentum and thermal transport phenomena. Tests were conducted over a heated flat wall with zero pressure-gradient and three levels of streamwise acceleration: K≡νU¯∞2dU¯∞dx= 0.07, 0.16, and 0.25 × 10−6. Free-stream turbulence intensities were maintained at approximately 0.5% for the baseline case and 0.4% for the accelerating cases. A miniature three-wire probe was used to measure mean velocity and temperature profiles, Reynolds stresses, and Reynolds heat fluxes. Transition onset and end were inferred from Stanton numbers and skin-friction coefficients.

The results indicate that mild acceleration delays transition onset and increases transition length both in terms of distance, x1 and Reynolds number based on x. Transition onset and length are relatively insensitive to acceleration in terms of momentum thickness Reynolds number. This is supported by the boundary layer thickness and integral parameters which indicate that a favorable pressure gradient suppresses boundary layer growth and development in the transition region. Heat transfer rates and temperature profiles in the late-transition and early-turbulent regions lag behind the development of wall shear stress and velocity profiles. This lag increases as K increases, indicating that the evolution of the heat transport is slower than that of the momentum transport. Comparison of the evolution of RMS temperature fluctuations to the evolution of Reynolds normal stresses indicates a similar lag in the RMS temperature fluctuations.
Studies on Wake-Affected Heat Transfer Around the Circular Leading Edge of Blunt Body
Authors: Funazaki K.
Published: February 2015

Detailed measurements are performed about time-averaged beat transfer distributions around the leading edge of a blunt body which is affected by incoming periodic wakes from the upstream moving bars. The blunt body is a test model of a front portion of a turbine blade in gas turbines and consists of a semicircular cylindrical leading edge and a flat plate afterbody. A wide range of the steady and unsteady flow conditions are adopted as for the Reynolds number based on the diameter of the leading edge and the bar-passing Strouhal number. The measured heat transfer distributions indicate that the wakes passing over the leading edge cause significant increase in beat transfer before the separation and the higher Strouhal number results in higher heat transfer. From this experiment, a correlation for the heat transfer enhancement around the leading edge due to the periodic wakes is deduced as a function of the Stanton number and it is reviewed by comparison with the other experimental works.
On Fast-Response Probes: Part 2 — Aerodynamic Probe Design Studies
Authors: Humm Hans J. , Gossweiler Christoph R. , Gyarmathy George
Published: February 2015

The influence of the probe size and geometry on the quality of fast-response measurements in turbomachines has been experimentally investigated.

For investigations in the static domain (time independent flows) probes were calibrated in two continuously operating wind tunnels in the range 0.2< Ma < 1.2. For dynamic calibrations in time variant flows model experiments in water (0.025 < k < 0.4, reduced frequency) were performed.

Aerodynamic characteristics were determined for a great number of probe geometries such as circular cylinders and wedge-type probes with varied apex angles, locations of the sensing holes and leading edge shapes. The experiments comprised investigations in tolerance ranges for prismatic total pressure probes, yaw angle sensitivity, yaw angle and Mach number effects on calibration and influence of dynamic yaw angle fluctuation on probe characteristics. As a result of the experiments errors due to static and dynamic aerodynamic effects could be quantified.

The majority of the errors arising during measurements in turbomachines can be directly related to the probe size. An important number of these errors are systematic and can be analytically modelled and hence their influence corrected.

In fluctuating flows the most severe measurement errors, which often may exceed the quantity of interest, are due to dynamic stall effects. This phenomenon, which is of transient nature and cannot be corrected, is typical for sharp wedge probes but is not present with circular cylinders or the effects being much smaller with very blunt wedges.
A Pump Instability Theory Using an Acoustic Feedback Mechanism
Authors: Corley James E.
Published: February 2015

A subsynchronous vibration problem with a large water injection pump was solved in 1974 by modifying the discharge piping transition to a long taper configuration. This paper describes a quantitative theory based upon the dynamic modeling of the pump rotor and piping system. The mode] successfully duplicates the experimental results of the pump instability and reproduces the subsynchronous vibration described in the original paper.

The analysis results in a log decrement of the system that is dependent upon the time delay of the acoustic pulsation. It shows that the system can be driven unstable for acoustic path lengths that are much less than the quarter wave length. The analysis also shows the log decrement is minimized when the time delay is equivalent to exactly that of an eighth wave length of the resonant frequency of the pump.
A Design Study of Radial Inflow Turbines With Splitter Blades in Three-Dimensional Flow
Authors: Tjokroamlnata W. D. , Tan C. S. , Hawthorne W. R.
Published: February 2015

An inverse design technique to design turbomachinery blading with splitter blades in three-dimensional flow is developed. It is based on the use of Clebsch transformation which allows the velocity field to be written as a potential part and a rotational part. It is shown that the rotational part can be expressed in terms of the mean swirl schedule (the circumferential average of the product of radius and tangential velocity) and the blade geometry that includes the main blade as well as the splitter blade. This results in an inverse design approach in which both the main and the splitter blade geometry are determined from a specification of the swirl schedule. Previous design study of a heavily-loaded radial inflow turbine, without splitter blades, for a rather wide variety of specified mean swirl schedules result in a blade shape with unacceptable non-radial blade filament; the resulting reduced static pressure distribution yields an “inviscid reverse flow region”1 covering almost the first half of the blade pressure surface. When the inverse design technique is applied to the design study of the turbine wheel with splitter blades, the results indicate that the use of splitter blades is an effective means for making the blade filament at an axial location more radial as well as a potential means for eliminating any “inviscid reverse flow” region that may exist on the pressure side of the blades.
A Scanning Radiation Thermometry Technique for Determining Temperature Distribution in Gas Turbines
Authors: De Lucia Maurizio , Masotti Giovanni
Published: February 2015

A scanning radiation thermometry technique for determining temperature distributions in gas turbines is presented. The system, an enhancement of an earlier work, can be used by operators even without special training, since the temperature distribution is measured and corrected in terms of the error due to the reflected radiation only on the basis of the turbine’s known geometry and the physical properties of the materials. In the proposed model, the surface-exitent radiances are directly acquired via 360-deg scans. Experimental testing was performed on a static turbine-blading model. Since the angle factors emerged as a notable influence on the accuracy of the model, two angle factor calculation methods, selected for suitability from a literature survey, are exhaustively investigated and their selection criteria, defined.
Experimental Investigation and Performance Analysis of Six Low Flow Coefficient Centrifugal Compressor Stages
Authors: Paroubek J. , Cyrus V. , Kyncl J.
Published: February 2015

Some results of a research and development programme for centrifugal compressors are presented. Six stage configurations with low flow coefficient were tested. The stages had channel width parameter bo/D2=0.01 and 0.03. For each value of the width parameter three different impellers with inlet hub to outlet diameter ratio do/D2=0.3, 0.4 and 0.5 were designed. Test rig, instrumentation and data analysis are described. Special attention was devoted to probe calibrations and to evaluation of the leakage, bearing and disc friction losses. Aerodynamic performance of all tested stages is presented. Slip factors of impellers obtained experimentally and theoretically are compared. Losses in both vaneless diffuser and return channel with de-swirl vanes are discussed. Rotating stall was also investigated. Criteria for stall limit were tested.
Suppression of Secondary Flows in a Mixed-Flow Pump Impeller by Application of 3D Inverse Design Method: Part 1 — Design and Numerical Validation
Authors: Zangeneh M. , Goto A. , Takemura T.
Published: February 2015

This paper describes the design of the blade geometry of a medium specific speed mixed flow pump impeller by using a 3D inverse design method in which the blade circulation (or rVθ) is specified. The design objective being the reduction of impeller exit flow non-uniformity by reducing the secondary flows on the blade suction surface. The paper describes in detail the aerodynamic critria used for the suppression of secondary flows with reference to the loading distribution and blade stacking condition used in the design. The flow through the designed impeller is computed by Dawes viscous code, which indicates that the secondary flows are well suppressed on the suction surface. Comparison between the predicted exit flow field of the inverse designed impeller and a corresponding conventional impeller indicates that the suppression of secondary flows has resulted in substantial improvement in the exit flow field. Experimental comparison of the flow fields inside and at exit from the conventional and the inverse designed impeller is made in part 2 of the paper.
Effect of Steam Injected Gas Turbines on the Unit Sizing of a Cogeneration Plant
Authors: Ito Koichi , Yokoyama Ryohei , Matsumoto Yoshikazu
Published: February 2015

The effect of installing steam injected gas turbines in a cogeneration plant is analyzed in the aspects of unit sizing and operational planning. An optimization method is used to determine the capacities of gas turbines and other auxiliary machinery in consideration of their operational strategies for variations of electricity and thermal energy demands. Through a numerical study on a plant for district hearing and cooling, it is clarified how the installation of steam injected gas turbines in place of simple cycle ones can improve the economic and energy saving properties. The influence of capital cost of steam injected gas turbines on the unit sizing and the above properties is also clarified.
Film Cooling of the Gas Turbine Endwall by Discrete-Hole Injection
Authors: Jabbari M. Y. , Marston K. C. , Eckert E. R. G. , Goldstein R. J.
Published: February 2015

Film cooling performance for injection through discrete holes in the endwall of a turbine blade is investigated. The effectiveness is measured at sixty locations in the region covered by injection. Three nominal blowing rates, two density ratios, and two approaching flow Reynolds numbers are examined. Analysis of the data reveals that even sixty locations are insufficient for the determination of the field of film cooling effectiveness with its strong local variations. Visualization of the traces of the coolant jets on the endwall surface, using ammonium-diazo-paper, provides useful qualitative information for the interpretation of the measurements, revealing the paths and interaction of the jets which change with blowing rate and density ratio.
Numerical Analysis of 3-D Unsteady Hot Streak Migration and Shock Interaction in a Turbine Stage
Authors: Saxer André P. , Felicl Hélène M.
Published: February 2015

A 3-D unsteady flow computation has been performed for a transonic first turbine stage under the influence of streaks of hot gas exiting the combustion chamber. Realistic flow conditions are obtained by using a non-equal stator-to-rotor pitch, a single-streak/multi-stator channels configuration and periodic boundary conditions. The resulting unsteady shock waves system and the hot streaks migration as well as the shock wave/streak interaction are presented and discussed. In addition, the time-average of the periodic unsteady solution is analyzed and compared with a steady-state computation. The steady-state solution matches the time-averaged one in terms of the pressure field and the maximum stagnation temperature on the rotor blade surface. However, the rotor blade temperature patterns are different with a stronger radial secondary flow present in the time-averaged solution due to the retention of the circumferential streak variations at the stator/rotor interface.
An Improved Squeeze Film Damper for Rotor Vibration Control: Theoretical Results
Authors: Zhao J. Y. , Linnett I. W. , Hahn E. J.
Published: February 2015

This paper proposes an improved squeeze film damper which will prevent the bistable operation associated with conventional squeeze film dampers at large unbalances and/or at small bearing parameters. It consists of a conventional squeeze film damper with a flexibly supported outer ring. This secondary flexible support is considered to be massless, and to have a constant stiffness and damping. The effectiveness of this damper in preventing bistable operation is investigated over a wide range of operating conditions for a rigid rotor supported on a centrally preloaded squeeze film damper. It is shown that depending on relevant parameters such as the stiffness ratio between the secondary support and the retaining spring, the damping coefficient of the support, and the mass ratio between the damper outer ring and the rotor, this proposed damper is very effective in preventing bistable operation even for high unbalance conditions.
Identification and Monitoring of Turbo Rotors in Active Magnetic Bearings
Authors: Siegwart Roland Y. , Herzog Raoul J. P. , Larsonneur René
Published: February 2015

In turbomachinery application Active Magnetic Bearings (AMB) have become an interesting alternative to conventional bearings. They not only offer an excellent solution to suspend the rotor, but also allow for sophisticated real-time data acquisition and monitoring with no additional hardware within the machine.

The present paper describes a digital controller environment for active magnetic bearing systems. The controller computer consists of a digital signal processor board with a fast parallel link to a PC. Special software has been developed to directly interfaces the control program to the software package MATLAB1 which is used on the host computer for data processing, identification and controller layout. These facilities are used to achieve time and frequency domain measurements for fast on-site tuning and data monitoring. Different examples are presented to demonstrate these powerful tools. Possible procedure for future system identification are discussed.
Recent Gas Turbine Applications in Large Commercial Vessels
Authors: Luck David L.
Published: February 2015

Demand for greater carrying capacity and higher speed in waterborne passenger and vehicle transportation has led to increased use of aeroderivative gas turbines as propulsion prime movers in large vessels. Operating economies require high operating availability which demands demonstrated reliability and support. New designs and recent experience in large gas turbine application to fast vessels is discussed. Considerations in propulsion system tradeoff’s are explored for various operational requirements.
Radial Mixing in an Axial Turbine
Authors: Dring Robert P.
Published: February 2015

The objective of this work was to examine radial mixing in an axial turbine from a number of different perspectives. These include: (1) its impact on the spanwise distributions of the force on the airfoils and the change in the fluid momentum as it passed between them, (2) the mixing coefficient distribution based on measured secondary flow velocities, and (3) comparisons of measured and calculated profile redistribution for an axisymmetric inlet profile and for profiles generated by introducing hot and cold streaks upstream of the turbine. It was seen that a simple diffusive transport model could give a good prediction of most of the measured results.
The Flow in a Second Stage Nozzle of a Low Speed Axial Turbine and its Effect on Tip Clearance Loss Development
Authors: Morphis G. , Bindon J. P.
Published: February 2015

The flow field in a one and a half stage low speed axial turbine with varying levels of rotor tip clearance was measured in order to compare the behaviour of the second nozzle with the first and to identify the manner in which second nozzle responds to the complex tip clearance dependent flow presented to it and completes the formation of tip clearance loss.

The tangentially averaged flow relative to the rotor blade in the tip clearance region was found to differ radically from that found in cascade and is not underturned with a high axial velocity. There is evidence rather of overturning caused by secondary flow. The axial velocity follows an almost normal endwall boundary layer pattern with almost no leakage jet effect. The cascade tip clearance model is therefore not accurate.

The reduction in second stage nozzle loss was shown to occur near the hub and tip which confirms that it is probably a reduction in secondary flow loss. The nozzle exit loss contours showed that leakage suppressed the formation of the classical secondary flow pattern and that a new tip clearance related loss phenomena exists on the suction surface.

The second stage nozzle reduced hub endwall boundary layer below that of both the first nozzle and that behind the rotor. It also rectified secondary and tip clearance flows to such a degree that a second stage rotor would experience no greater flow distortion than the first stage rotor.

Radial flow angles behind the second stage nozzle were much smaller than found in a previous study with low aspect ratio un-twisted blades.
Dynamic Surge Behavior of a Centrifugal Pumping System
Authors: Bons Jeffrey P.
Published: February 2015

A facility has been constructed to investigate the dynamic surge behavior of centrifugal pumping systems. The facility includes discrete air volumes which can be varied to alter the pumping system’s compliance, and hence susceptibility, to surge. With this facility, the first detailed measurements of surge behavior for a low specific speed, shrouded, centrifugal pump have been obtained and compared with theoretical predictions. The pump tested is a geometrically and dynamically scaled model of a small industrial pump with known surge tendencies. A thorough characterization of the surge phenomenon has been performed, including surge cycle frequency, amplitude, point(s) of inception, and variations with operating point. The results underline the dominant role of: (1) the shape of the pump performance characteristic and (2) the system stability (B) parameter in determining the pump behavior. A simple 1-D model of the pumping system is shown to capture all observed trends in the experimental data. The model accounts for variations in pump wheel speed with mass flow, and employs a first order time lag in pressure rise to model the pump response.
Method for Predicting Choke Flow in Vaned Radial Diffusers Based on Thermodynamic and Gas Dynamic Criteria
Authors: Seidel U. , Rautenberg M.
Published: February 2015

Conventional vaned diffusers have the disadvantage of extremely high total pressure losses in the region of choke, resulting from channel constrictions in the diffuser cascade. This effect is closely related to increasing impeller tip Mach numbers Mu,2 or increasing diffuser inlet flow Mach numbers. This aspect demands very special attention in diffuser design. On the basis of experimental and theoretical studies a hypothetical description of flow conditions within the diffusor was undertaken. The key feature of the working hypothesis is a one-dimensional loss model which is formulated in terms of thermodynamic and gas dynamic relationships. In conjunction with an appropriate application of the laws of conservation, this formulation leads to a method of solution for determining the aerodynamic conditions at the choke condition. Moreover, the method of analysis presented here is also applicable to a wide range of problems in fluid dynamics. In view of the fact that the position of the compressor choke flow rate is physically defined at the cascade inlet and the minimum cascade crossection, this work concentrates thematically on the formulation of the state variables at these locations. The method of analysis was illustrated by way of examples, and the theoretical approach was verified on the basis of experimentally determined flow conditions at choke flow rate.
Development of Periodic Unsteady Turbulent Wakes in a Curved Channel at Zero Streamwise Pressure Gradient
Authors: Schobeiri M. T. , John J.
Published: February 2015

The development of turbomachinery wake flows is influenced by streamline curvature and streamwise pressure gradient. This paper is a part of a comprehensive experimental and analytical study on the development of the steady and periodic unsteady turbulent wakes in curved channels at different longitudinal (streamwise) pressure gradients. The development of periodic unsteady wakes in a curved channel at zero longitudinal pressure gradient is reported in this paper. Instantaneous velocity components of the periodic wakes, measured using a X-hot-film probe, are analyzed by employing phase-averaging techniques. The temporal distribution of phase-averaged velocity and Reynolds stress components obtained in stationary frame of reference are transformed to a relative spatial coordinate system. The profiles of the velocity and Reynolds stress distribution in relative spatial coordinate system and similarity coordinates are consistent with the measurements of the wake development behind stationary cylinder in the same curved channel.
Operation of Gas Turbine Engines in Volcanic Ash Clouds
Authors: Dunn Michael G. , Baran Adam J. , Miatech Jerry
Published: February 2015

Results are reported for a technology program designed to determine the behavior of gas turbine engines when operating in particle-laden clouds. There are several ways that such clouds may be created, i.e., explosive volcanic eruption, sand storm, military conflict, etc. The response of several different engines, among them the Pratt & Whitney JT3D turbofan, the Pratt & Whitney J57 turbojet, a Pratt & Whitney engine of the JT9 vintage, and an engine of the General Electric CF6 vintage has been determined.

The particular damage mode that will be dominant when an engine experiences a dust cloud depends upon the particular engine (the turbine inlet temperature at which the engine is operating when it encounters the dust cloud), the concentration of foreign material in the cloud, and the constituents of the foreign material (the respective melting temperature of the various constituents). Further, the rate at which engine damage will occur depends upon all of the factors given above and the damage is cumulative with continued exposure.

An important part of the Calspan effort has been to identify environmental warning signs and to determine which of the engine parameters available for monitoring by the flight crew can provide an early indication of impending difficulty. On the basis of current knowledge, if one knows the location of a particle-laden cloud, then that region should be avoided. However, if the cloud location is unknown, which is generally the case, then it is important to know how to recognize when an encounter has occurred and to understand how to safely operate, which is another part of the Calspan effort.