bluuebunny/crossref_metadata_2025 huggingface dataset:
Factors predicting health‐related quality of life in pediatric liver transplant recipients in the functional outcomes group
Authors: Alonso Estella M. , Martz Karen , Wang Deli , Yi Michael S. , Neighbors Katie , Varni James W. , Bucuvalas John C. ,   The Studies of Pediatric Liver Transplantation (SPLIT) Functional Outcomes Group (FOG)
Published: August 2013

Data from 997 pediatric LT recipients were used to model demographic and medical variables as predictors of lower levels of HRQOL. Data were collected through SPLIT FOG project. Patients were between 2 and 18 yr of age and survived LT by at least 12 months. Parents and children (age ≥ 8 yr) completed PedsQL™ 4.0 Generic Core and CF Scales at one time point. Demographic and medical variables were obtained from SPLIT. HRQOL scores were categorized as “poor” based on lower 25% of scores for each measure. Logistic regression models were generated. Single‐parent households (OR 1.94, CI 1.13–3.33, p = 0.017), anti‐seizure medications (OR 3.99, CI 1.26–12.70, p = 0.019), and number of days hospitalized (OR 1.03, CI 1.01–1.06, p = 0.0067) were associated with lower self‐reported HRQOL. Parent data identified increasing age at transplant, age 5–12 yr at survey, hospitalization >21 days at LT, re‐operations, diabetes, and growth failure at LT as additional predictors of generic HRQOL. Male gender, single‐parent households, higher bilirubin levels at LT, and use of anti‐seizure medication predicted lower cognitive function scores. HRQOL following pediatric LT is related to medical and demographic variables.
Adolescent transplant recipients as peer mentors: A program to improve self‐management and health‐related quality of life
Authors: Jerson Bradley , D'Urso Christine , Arnon Ronen , Miloh Tamir , Iyer Kishore , Kerkar Nanda , Annunziato Rachel A.
Published: August 2013

The purpose of this study was to examine the safety, feasibility, acceptability, and preliminary efficacy of a cross‐age peer mentoring program created to improve adherence and psychosocial outcomes for pediatric liver transplant recipients. Twenty‐two participants were assigned to a “mentor now” or “mentor later” waitlist control group. Tacrolimus SD, a validated measure of adherence, was assessed for six months pre‐ and post‐intervention for both groups. Self‐report measures of self‐management and HRQOL were completed at recruitment and three months after training. Participant report indicated the acceptability of the intervention. Clinically significant improvement in adherence was detected. No significant changes on the psychosocial outcome measures at follow‐up were observed. This study demonstrated that an outpatient‐based mentoring program is a safe, feasible, and acceptable option to incorporate within a pediatric liver transplant program with potential for promising application in other transplantation populations as well. These results also suggest that the program may have been associated with meaningful improvement in adherence, although further evaluation is warranted.
Non‐invasive biological quantification of acute gastrointestinal graft‐versus‐host disease in children by plasma citrulline
Authors: Merlin E. , Minet‐Quinard R. , Pereira B. , Rochette E. , Auvrignon A. , Oudot C. , Sapin V. , Deméocq F. , Kanold J.
Published: August 2013

Clinical grading of GI involvement during acute GVHD remains a challenging issue, especially in children. Plasma citrulline, a non‐protein amino acid selectively produced and released by enterocytes, is a suitable surrogate endpoint for small intestinal epithelial cell mass, irrespective of the underlying cause of cell loss. Children referred for allogeneic bone marrow transplantation who were free from chronic malabsorption or constitutional disease involving the GI tract were consecutively included in this prospective study. Plasma citrulline and albumin concentration was measured every week between day 7 and day 28 of BMT until resolution of the aGVHD or occurrence of chronic GVHD. In total, 31 children were included between 2008 and 2011. After a CR, citrulline levels fell to a minimum level on day 7 and then increased to reach the initial value on day 28. After day 28, plasma citrulline but not albumin was strongly linked to the occurrence of GI GVHD, the threshold being set at 10 μmol/L. The correlation with clinical grade of GI‐aGVHD now needs to be assessed in larger populations. In pediatric patients, citrulline is valuable as a suitable non‐invasive marker of GI involvement in acute GVHD.
Widespread overspill from a saline density‐current channel and its interaction with topography on the south‐west Black Sea shelf
Authors: Hiscott Richard N. , Aksu Ali E. , Flood Roger D. , Kostylev Vladimir , Yaşar Doğan
Published: August 2013

Seaward of the Bosphorus Strait, the south‐west Black Sea shelf is dominated by the world's largest channel network maintained by a quasi‐continuous saline (ca 35 → 31 psu) underflow. Calculations indicate that >85% of the initial discharge of ca 104 m3s−1 spills overbank before the shelf edge. This paper documents interaction of the overspill with sea bed topography using multibeam bathymetry, echo‐sounder images of the water column, conductivity–temperature–depth profiles and sediment cores. Overbank spill is widespread, particularly through crevasse channels and on the middle shelf where confinement by channel banks is negligible. Towards the outer shelf, the wind‐driven Rim Current advects mud along the shelf, contributing to levée successions and deposition on stoss sides of elongate transverse ridges. Echo‐sounder profiles reveal metre‐scale eddies over megaflutes, and breaking lee waves and internal hydraulic jumps over ridges. Megaflutes reach 600 m long and 7 m deep, yet form where the underflow, outside the flute, is no thicker than ca 2 to 5 m. Two types of elongate seaward‐facing ridges are recognized. Type 1 ridges, 2 to 5 m high, consist of bivalve‐rich muddy sand in low‐angle (3·5° to 6°) cross‐sets created by the underflow. Type 2 ridges, ca 5 m high, have crests up to 2 km long and a buried wedge‐shaped foundation (the ‘ridge‐core’) comprised of facies similar to Type 1 ridges. These ridge‐cores are blanketed on the landward side by stratified muds, and are capped by obliquely oriented ribs supporting a diverse benthic community. This facies distribution is interpreted to result from stoss‐side and lee‐side velocity and turbulence fluctuations induced by internal hydraulic jumps and breaking lee waves in overspilling portions of the underflow. Experimental results published by W.H. Snyder and co‐workers effectively explain ridge evolution and flow across the ridges, and therefore can be applied with confidence to less easily studied deep‐marine settings swept by turbidity currents.
Some Remarks onPutnam's Contributions to Semantics
Authors: Burge Tyler
Published: August 2013

After a critical discussion of Putnam's early work on the analytic–synthetic distinction, this article discusses seven contributions that Putnam has made to the philosophy of language. These contributions are (1) to understanding the role of definitions in science and in ordinary discourse; (2) to recognizing the role of stereotypes in explaining meaning; (3) to acknowledging the minimal role of explicative understanding in having linguistic competence with natural kind words; (4) to distinguishing sharply between identifying natural kinds and determining their more fundamental natures; (5) to exploring a division of linguistic labour – a role for social interaction in determining reference, especially of natural kind terms; (6) to establishing a broadly unified causal account of the reference of ordinary natural kind terms and scientific physical magnitude terms; and (7) to reviving a conception of scientific language that allows for trans‐theoretical reference and one sort of trans‐theoretical meaning.
Screening recipients of increased‐risk donor organs: a survey of transplant infectious diseases physician practices
Authors: Theodoropoulos N. , Ladner D.P. , Ison M.G.
Published: August 2013

Background

In 1994, the Public Health Service published guidelines to minimize the risk of human immunodeficiency virus (HIV) transmission and to monitor recipients following the transplantation of organs from increased‐risk donors. A 2007 survey revealed the post‐transplant surveillance of recipients of organs from increased‐risk donors (ROIRD) is variable.

Methods

An electronic survey was sent to transplant infectious diseases physicians at US solid organ transplant centers.

Results

A total of 126 surveys were sent to infectious diseases physicians, and we received 51 (40%) responses. We found that 22% of respondents obtain only verbal, 69% verbal and written, and 8% do not obtain any special consent from ROIRD, despite an Organ Procurement and Transplantation Network policy requiring such consent. Post‐solid organ transplantation serologies for HIV, hepatitis B virus (HBV), and hepatitis C virus (HCV) are performed by 6–8% of respondents in all recipients, by 69% of respondents in ROIRD only, and 25% of respondents do not perform them at all. Post‐transplant nucleic acid testing is carried out by 55–64% of respondents in ROIRD, by 0–2% in all recipients, and not performed by 35–43% of respondents.

Conclusion

Screening RIORD for HIV, HBV, and HCV has increased since 2007, but remains less than optimal and is incomplete when screening for disease transmission at many centers.
Heart transplantation in a patient with heteroresistant vancomycin‐intermediate Staphylococcus aureus ventricular assist device mediastinitis and bacteremia
Authors: Swartz T.H. , Huprikar S. , LaBombardi V. , Pinney S. , Anyanwu A. , Lee M. , Patel G.
Published: August 2013

Vancomycin‐intermediate Staphylococcus aureus (VISA) infections are an emerging problem and antibiotic options are limited. We report the first case, to our knowledge, of heteroresistant VISA mediastinitis and bacteremia in a patient with a ventricular assist device who underwent orthotopic heart transplantation with clinical cure.
Evaluation of accelerated collagen cross‐linking for the treatment of melting keratitis in eight dogs
Authors: Famose Frank
Published: August 2013

Objective

Melting keratitis is serious condition presenting a high risk of permanent blindness and is caused by infectious or noninfectious factors. In humans, the clinical efficacy of collagen cross‐linking (CXL) has been described in the treatment of refractory infectious keratitis by arresting keratomalacia. The aim of this study was to evaluate the efficacy of acceleratedCXLfor the treatment of melting keratitis in dogs.

Animal studied and Procedure

Eight dogs were treated for unilateral melting keratitis by accelerated CXL. Corneas were irradiated by UVA (370 nm) at 30 mW/cm² irradiance for 3 min after soaking by 0.1% riboflavin in 20% dextran for 30 min. Follow‐up was conducted 3, 7, 14, and 30 days after treatment.

Results

Pain improvement was observed for all cases within 3 days after treatment. Epithelial healing was observed within 15 days for all cases.

Disappearance of cellular infiltration was observed for all cases at day 7. The corneal vascularization disappeared for 4 of 8 dogs and was reduced for 4 of 8 dogs within 1 month. At 1 month, all cases presented a variable degree of corneal scarring, but all eyes had visual function. No recurrent infection was observed.

Conclusions

The main observation of this study is that all the cases have presented with the same clinical result regardless of the presence and the sensitivity of the infectious agents and regardless of the duration of the condition prior toCXLtreatment. AcceleratedCXLappears to be a valuable option for the treatment of melting keratitis.
Treatment of immune‐mediated keratitis in horses with episcleral silicone matrix cyclosporine delivery devices
Authors: Gilger Brian C. , Stoppini Riccardo , Wilkie David A. , Clode Alison B. , Pinto Nelson H. , Hempstead Julie , Gerding Joseph , Salmon Jacklyn H.
Published: August 2013

Purpose

To describe the use of episcleral silicone matrix cyclosporine (ESMC) drug delivery devices in horses with immune‐mediated keratitis (IMMK) with evaluation of tolerability and efficacy in long‐term control of inflammation.

Methods

Retrospective study. ESMC implants (1.2 cm length, 30% wt/wt cyclosporine (CsA) in silicone; with approximately 2 μg/day steady‐state release for at least 400 days) were used.

Results

Nineteen horses (20 eyes) received two or more ESMC implants for superficial stromal (n = 9), midstromal (n = 3), or endothelial (n = 5) IMMK. Three additional horses received two or more ESMC implants for pigmentary keratouveitis (PK). Nine eyes of eight horses with superficial and five eyes of five horses with endothelial IMMK were well controlled after placement of ESMC implants (mean follow‐up 176.8 and 207.2 days, respectively). Horses with midstromal IMMK and PK were not controlled with ESMC implants alone, but instead required frequent use of other medications or surgery to control the disease. The mean duration of disease prior to ESMC implantation of horses with midstromal IMMK was 495 ± 203.9 days, compared with 121.6 ± 92.7 days with superficial IMMK. ESMC implants were well tolerated by all horses without documented loss of the device.

Conclusions

Results from this preliminary retrospective study suggest that the ESMC implants were well tolerated and associated with treatment success with superficial and endothelial IMMK, especially if placed early in the disease process. Further study is needed to determine the duration of efficacy, number of implants required, and better therapies for chronic midstromal IMMK and pigmentary keratouveitis.
IMAGING DIAGNOSIS—TEMPOROMANDIBULAR JOINT DYSPLASIA IN A BASSET HOUND
Authors: Lerer Assaf , Chalmers Heather J. , Moens Noel MM , Mackenzie Shawn D. , Kry Kristin
Published: August 2013

A 5‐month‐old intact male Basset Hound presented for evaluation of pain and crepitation during manipulation of the temporomandibular joint, worse on the right side. A computed tomography (CT) scan of the head was performed. The CT images demonstrated the osseous features of temporomandibular joint dysplasia and facilitated a 3D reconstruction, which allowed better visualization of the dysplastic features. The patient responded to conservative management with a tape muzzle with no recurrence reported by the owner 6 months after presentation.
An Improved Nickel Based MIMS Thermocouple for High Temperature Gas Turbine Applications
Authors: Scervini Michele , Rae Catherine
Published: August 2013

A new nickel based thermocouple for high temperature applications in gas turbines has been devised at the Department of Material Science and Metallurgy of the University of Cambridge. This paper describes the new features of the thermocouple, the drift tests on the first prototype, and compares the behavior of the new sensor with conventional mineral insulated metal sheathed Type K thermocouples: the new thermocouple has a significant improvement in terms of drift and temperature capabilities. Metallurgical analysis has been undertaken on selected sections of the thermocouples exposed at high temperatures, which rationalizes the reduced drift of the new sensor. A second prototype will be tested in subsequent research, from which further improvements in drift and temperature capabilities are expected.
Experimental and Computational Determination of Laminar Burning Velocity of Liquefied Petroleum Gas-Air Mixtures at Elevated Temperatures
Authors: Akram Mohammad , Kumar Sudarshan , Saxena Priyank
Published: August 2013

The laminar burning velocity of liquefied petroleum gas (LPG) air mixtures at high temperatures is extracted from the planar flames stabilized in the preheated mesoscale diverging channel. The experiments were carried out for a range of equivalence ratios and mixture temperatures. Computational predictions of the burning velocity and detailed flame structure were performed using the PREMIX code with USC mech 2.0. The present data are in very good agreement with both the recent experimental and computational results available. A peak burning velocity was observed for slightly rich mixtures, even at higher mixture temperatures. The minimum value of th temperature exponent is observed for slightly rich mixtures.
Large-Eddy Simulation of Turbulent Spray Combustion in a Subscale Aircraft Jet Engine Combustor—Predictions of NO and Soot Concentrations
Authors: Moriai Hideki , Kurose Ryoichi , Watanabe Hiroaki , Yano Yutaka , Akamatsu Fumiteru , Komori Satoru
Published: August 2013

Large-eddy simulation (LES) is applied to turbulent spray combustion fields in a subscale (1/2) aircraft jet engine combustor with an air-blast type swirl fuel nozzle and validity is examined by comparing with measurements. In the LES, Jet-A is used as liquid fuel, and individual droplet motion is tracked in a Lagrangian manner with a parcel model. As a turbulent combustion model, the extended flamelet/progress-variable approach, in which heat transfer between droplets and ambient gas including radiation and heat loss from walls can be taken into account, is employed. A detailed chemistry mechanism of Jet-A with 1537 reactions and 274 chemical species is used. The radiative heat transfer is computed by the discrete ordinate (DO) method. The equivalence ratio ranges from 0.91 to 1.29. The comparisons of the predicted droplet velocity and size, gaseous temperature, NO, and soot emissions with the measurements show that the present LES is capable of capturing the general features of the turbulent spray combustion fields in the subscale (1/2) aircraft jet engine combustor.
The Effects of a Parametric Variation of the Rim Seal Geometry on the Interaction Between Hub Leakage and Mainstream Flows in HP Turbines
Authors: Popović I. , Hodson H. P.
Published: August 2013

The objective of this work was to assess and understand the effects of parametric variation performed on a typical overlapping rim seal geometry. The datum geometry has been focus of a detailed experimental investigation employing a large-scale linear cascade subjected to a range of the mass flow rates and swirl velocities of the leakage air. The parametric variations described in this paper were examined using validated CFD. As a part of the parametric studies, both the axial and the radial seal clearance between the rotor fin (angel wing) and stator platform were varied as well as the length of the overlap between stator and rotor platforms. In addition, the effects of forward and backward facing annulus steps were also investigated.

It has been found that a backward facing annulus step was detrimental for all conditions considered, while a forward facing step offered improvements for smaller step heights and/or lower leakage fractions. Tightening of the seal clearances closer to the annulus line improved the sealing effectiveness, but often at the expense of increased losses. On the other hand, increasing the overlap length led to improvements in the sealing effectiveness with very small effects on the overall losses. Moving the rim seal away from the blade leading edges reduced the pressure asymmetry at the rim seal and increased the flow uniformity of the leakage air. However, this led to an increased cross-passage flow (more negative skew) and higher losses at all but lowest leakage fractions.

The results presented in this paper highlight the fact that there may not be an optimum rim seal solution that would offer an improvement for the full range of leakage fractions and that for different rim sealing flows there may be a different optimum geometry. In addition, rotor disc movements in radial and axial directions at various off-design conditions should be considered as a part of the design process. Based on the presented results it may be of a benefit to the turbine designer to consider rotor disc designs which would be more biased towards the upstream and outward disc movements that would result in tightening of the seal clearances and avoidance of a backward facing annulus step.
Experimental Investigation on the Leading Edge Film Cooling of Cylindrical and Laid-Back Holes With Different Hole Pitches
Authors: Liu Cun-liang , Zhu Hui-ren , Zhang Zong-wei
Published: August 2013

Experimental investigation has been performed to study the film cooling performance of cylindrical and laid-back film holes on the turbine blade leading edge. Four test models are measured for four blowing ratios to investigate the influence of film hole shape and hole pitch on the film cooling performance. Film cooling effectiveness and heat transfer coefficient are obtained using transient heat transfer measurement technique with double thermochromic liquid crystals. As the blowing ratio increases, the trajectory of jets deviates to the spanwise direction and lifts off gradually. However, more area can benefit from the film protection under large blowing ratio, while the heat transfer coefficient is also higher. The basic distribution features of heat transfer coefficient are similar for all the four models. Heat transfer coefficient in the region where the jet core flows through is relatively lower, while heat transfer coefficient in the jet edge region is relatively higher. For the models with small hole pitch, the laid-back holes only give better film coverage performance than the cylindrical holes under large blowing ratio. For the models with large hole pitch, the advantage of laid-back holes in film cooling effectiveness is more obvious in the upstream region relative to the cylindrical holes. For the cylindrical hole model and the laid-back hole model with the same hole pitch, the laterally averaged heat transfer coefficients are nearly the same with each other under the same blowing ratios. Compared with the models with large hole pitch, the laterally averaged film cooling effectiveness and the laterally averaged heat transfer coefficient are larger for the models with small hole pitch because of larger proportion of film covering area and strong heat transfer region.
Genetic Algorithm Optimization of an HPT Vane Pressure Side Film Cooling Array
Authors: Johnson J. J. , King P. I. , Clark J. P. , Ooten M. K.
Published: August 2013

The following work is an in-depth investigation of the heat transfer characteristics and cooling effectiveness of a full-scale fully-cooled modern high-pressure turbine (HPT) vane as a result of genetic algorithm (GA) optimization, relative to the baseline cooling configuration. Individual designs were evaluated using 3-D Reynolds-Averaged Navier-Stokes (RANS) computational fluid dynamics (CFD) that modeled film cooling injection using a transpiration boundary condition. 1,800 total different film cooling arrays were assessed for fitness within the optimization where film cooling parameters such as axial and radial hole location, hole size, injection angle, compound angle, and custom-designed row patterns were varied in the design space. The GA was able to find a unique pressure side (PS) cooling array after only 13 generations. The fitness functions prescribed for the problem successfully lowered the PS average surface temperature, lowered the maximum temperature, and increased the average overall effectiveness. Results clearly show how the optimized design redistributed flow from over-cooled areas on the vane PS to under-cooled areas near the shroud. Methods used in substantially improving pressure side film cooling performance here are promising in terms of eliminating durability problem areas for individual HPT components in their proper operating environments as well as increasing the potential to use less air from the compressor for cooling purposes in a gas turbine engine.
Exploring Conjugate CFD Heat Transfer Characteristics for a Film-Cooled Flat Plate and 3-D Turbine Inlet Vane
Authors: Johnson J. J. , King P. I. , Clark J. P. , Koch P. J.
Published: August 2013

As part of a thorough benchmarking of the baseline cooling design in planned optimization work, Reynolds-Averaged Navier Stokes (RANS) conjugate heat transfer (CHT) computational fluid dynamics (CFD) assessments have been accomplished at RTV design flow conditions to simulate both a cooled flat plate pressure side (PS) model infrared thermography experiment as well as a full-scale, fully-cooled, full-wheel blowdown experiment on the same high pressure turbine (HPT) vane. Numerous past works on turbomachinery film cooling have been conducted using flat plate models because of their simplicity, repeatability, and low cost of experimentation relative to full scale rotating blowdown rigs. Some of these works generated film cooling correlations still in use today in industry for HPT components. The CFD assessments in this work provide insight into the fundamental differences between a flat plate model and a realistic 3-D vane in terms of film cooling performance for the same PS cooling array. The comparisons of results wring out expected differences between the geometries due to aspects such as highly curved surfaces and endwall effects. However, with nearly-matched coolant-to-mainstream temperature and pressure ratios, the cooling performance between the two models is surprisingly similar, especially in the midspan region. The similarities and differences observed herein represent the rigor and accuracy afforded by simulating both the solid and fluid domains as well as the high-density unstructured meshes that take into account all individual cooling passages and internal plenums, on top of the typically-assessed external fluid flow field.
Impact of the Combustor-Turbine Interface Slot Orientation on the Durability of a Nozzle Guide Vane Endwall
Authors: Thrift A. A. , Thole K. A. , Hada S.
Published: August 2013

The combustor-turbine interface is an essential component in a gas turbine engine as it allows for thermal expansion between the first stage turbine vanes and combustor section. Although not considered as part of the external cooling scheme, leakage flow from the combustor-turbine interface can be utilized as coolant. This paper reports on the effects of orientation of a two-dimensional leakage slot, simulating the combustor-turbine interface, on the net heat flux reduction to a nozzle guide vane endwall. In addition to adiabatic effectiveness and heat transfer measurements, time-resolved, digital particle image velocimetry (TRDPIV) measurements were performed in the vane stagnation plane. Four interface slot orientations of 90°, 65°, 45°, and 30° located at 17% axial chord upstream of a first vane in a linear cascade were studied. Results indicate that reducing the slot angle to 45° can provide as much as a 137% reduction to the average heat load experienced by the endwall. Velocity measurements indicate the formation of a large leading edge vortex for coolant injected at 90° and 65° while coolant injected at 45° and 30° flows along the endwall and washes up the vane surface at the endwall junction.
Effusion-Cooling Performance at Gas Turbine Combustor Representative Flow Conditions
Authors: Kakade Vinod U. , Thorpe Steven J. , Gerendás Miklós
Published: August 2013

The thermal management of aero gas turbine engine combustion systems commonly employs effusion-cooling in combination with various cold-side convective cooling schemes. The combustor liner incorporates many small holes which are usually set in staggered arrays and at a shallow angle to the cooled surface; relatively cold compressor delivery air is then allowed to flow through these holes to provide the full-coverage film-cooling effect. The efficient design of such systems requires robust correlations of film-cooling effectiveness and heat transfer coefficient at a range of aero-thermal conditions, and the use of appropriately validated computational models. However, the flow conditions within a combustor are characterised by particularly high turbulence levels and relatively large length scales. The experimental evidence for performance of effusion-cooling under such flow conditions is currently sparse. The work reported here is aimed at quantifying typical effusion-cooling performance at a range of combustor relevant free-stream conditions (high turbulence), and also to assess the importance of modeling the coolant to free-stream density ratio. Details of a new laboratory wind-tunnel facility for the investigation of film-cooling at high turbulence levels are reported. For a typical combustor effusion geometry that uses cylindrical holes, spatially resolved measurements of adiabatic effectiveness, heat transfer coefficient and net heat flux reduction are presented for a range of blowing ratios (0.48 to 2), free-stream turbulence conditions (4 and 22%) and density ratios (0.97 and 1.47). The measurements reveal that elevated free-stream turbulence impacts on both the adiabatic effectiveness and heat transfer coefficient, although this is dependent upon the blowing ratio being employed and particularly the extent to which the coolant jets detach from the surface. At low blowing ratios the presence of high turbulence levels causes increased lateral spreading of the coolant adjacent to the injection points, but more rapid degradation in the downstream direction. At high blowing ratios, high turbulence levels cause a modest increase in effectiveness due to turbulent transport of the detached coolant fluid. Additionally, the augmentation of heat transfer coefficient caused by the coolant injection is seen to be increased at high free-stream turbulence levels.
Effects of Varying Streamwise and Spanwise Spacing in Pin-Fin Arrays
Authors: Ostanek Jason K. , Thole Karen A.
Published: August 2013

Pin-fin channels are commonly used for cooling the trailing edges in turbine blades and vanes. While many studies have investigated heat transfer performance of pin-fin channels, few studies have investigated pin-fin flowfields. The present study compares the time-dependent near wake flow and the time-mean surface heat transfer for varying pin-fin configurations at a Reynolds number of 2.0e4. Pin-fin aspect ratio showed little influence on pin-surface heat transfer coefficients when increasing H/D from 1.0 to 2.0. Changes in streamwise and spanwise spacing, however, were found to significantly impact the behavior of the near wake flow and local heat transfer coefficients. Decreasing spanwise spacing from S/D = 3.0 to 1.5 in a single pin-fin row was found to suppress downstream vortex shedding and create biased, asymmetric wakes. Local heat transfer coefficients on the trailing side of the pin-fin reflected that vortex shedding, observed for spanwise spacings S/D ≥ 2.0, was beneficial for heat transfer on the pin-surface. Similarly, decreasing streamwise spacing from X/D = 3.03 to 2.16 was found to suppress vortex shedding in the first row of a seven row array. For those cases that support vortex shedding, X/D ≥ 2.60, pin-fin heat transfer increased on the trailing side but array heat transfer in downstream rows decreased.
Impact of the 3D Flow Effects on the Silo Combustor Thermal State
Authors: Vassiliev Vladimir , Magni Fulvio , Chernyshev Sergey , Kostege Valery
Published: August 2013

Many Alstom heavy-duty gas turbines with a silo combustor are in service and moreover undergoing upgrades for performance augmentation, lifetime extension, and emission reduction. Several structural parts of the combustor are exposed to high gas temperatures, and therefore their lifetime depends mainly on the metal temperatures, which must be kept within the acceptable limits. This paper describes methodology based on the state of the art methods of 3D CFD and finite element (FE) computations, which are combined into the computational process for the reliable silo combustor thermal analyses.

In the first part of the paper the computational model of the silo combustor is discussed. The model comprises CFD models simulating the hot gas path and the cooling air supply system, as well as the FE model of the structural parts. The CFD models predict the gas temperatures and heat transfer coefficients that are used by the FE model for calculating the metal temperatures.

In the second part of the paper the computational results are presented and several 3D flow phenomena are analysed in details. One effect is the interaction of dilution jets in swirled cross flow. At different operation conditions, pairing of those jets occurs, which generates the periodic metal temperature distribution, as recorded in the field. This analysis also revealed factors, which influence on the temperature distribution. The combustor simulation delivers an insight into non-homogeneous temperature profiles in front of the turbine behind the transition channel of the silo-combustor. Finally, by adding leakages into the flow model, the interesting example of the non-homogeneous leakage of cold air, which can lead to local increase of material temperature, was simulated. All these simulations led to reliable silo-combustor upgrades.
Simulations of Multi-Phase Particle Deposition on a Non-Axisymmetric Contoured Endwall With Film-Cooling
Authors: Lawson Seth A. , Lynch Stephen P. , Thole Karen A.
Published: August 2013

Designing turbine components for maximum aerodynamic performance with adequate cooling is a critical challenge for gas turbine engineers, particularly at the endwall of a turbine due to complex secondary flows. To complicate matters, impurities from the fuel and intake air can deposit on film-cooled components downstream of the combustor. Deposition induced roughness can reduce cooling effectiveness and aerodynamic performance dramatically. One method commonly used for reducing the effects of secondary flows on aerodynamic performance is endwall contouring. The current study evaluates deposition effects on endwall contouring given the change to the secondary flow pattern.

For the current study, deposition was dynamically simulated in a turbine cascade to determine its effects on film-cooling with and without endwall contouring. Computationally predicted impactions were in qualitative agreement with experimental deposition simulations showing that contouring reduced deposition around strategically placed film-cooling holes. Deposition reduced cooling effectiveness by 50% on a flat endwall and 40% on an identically cooled contoured endwall. Although 40% is still a dramatic reduction in effectiveness, the method of using the endwall contouring to alter deposition effects shows promise.
Uniform Crystal Temperature Sensor Accuracy Under Transient Conditions
Authors: DeVoe Jason , Odom Stephen , Ginzbursky Lev
Published: August 2013

This paper investigates the accuracy of Uniform Crystal Temperature Sensors (UCTS) under transient conditions and describes a methodology for addressing sources of systematic error based on the findings. The study applies to the important task of thermal mapping of critical turbine parts during the engine development phase, for which UCTS is particularly well suited [1, 2, 3, 4]. A previous study focused on UCTS in steady state regimes and provided recommendations for optimizing the technique [5]. However, a substantial reduction in engine development costs may be achieved by being able to combine, for instance cyclic endurance tests with thermal mapping assuming that neither task will jeopardize the other.

The basic trends and magnitude of measurement errors were assessed as a function of factors such as UCTS installation configuration, thermo-physical properties of the installation materials and cycle characteristics. The authors used Finite Element Analysis to simulate transient heat transfer through a thin wall with an embedded UCTS. Stress calculations performed for the case of densely packed multi-UCTS installation on turbine blades showed no detrimental influence of standard micro-cavities on blade structural characteristics. These results were confirmed by a number of successful endurance tests, proving its compatibility with the task of thermography. Attention was focused on the cyclic test influence on the accuracy of thermal mapping. Single and multiple cycle test configurations have been considered.

After completion of a computational matrix, the characteristic results of interest are presented in the form of plots and diagrams to support the technical discussion. Recommendations drawn from this research will help analytical designers, test and instrumentation engineers to plan and execute dual task transient tests with a high accuracy of thermal mapping result interpretation.
First Results of a New Test Rig for the Research on the Internal Air System of an Industrial Gas Turbine
Authors: Günther André , Uffrecht Wieland , Odenbach Stefan , Caspary Volker
Published: August 2013

Improvement of the internal air system has great impact on the efficiency and power of gas turbines. This paper describes a new two-stage test rig for research on the cooling air supply of industrial gas turbines. The design is modeled on a simplified geometry of the internal cavities of the high pressure turbine with receiver holes simulating the restriction imposed by internal blade cooling flow circuits. The test rig consists of a rotor-stator cavity and a full rotating cavity. The Stage One supply and the Stage Two supply are separated inside the rotorstator cavity. The intended aim of the research is the branched cooling air supply. The rim seal flow, which effect on cavity flows is known to be non-trivial, is outside the scope of this area of interest.

This paper concentrates on the flow path supplying the Stage Two. Variations of the axial gap size and the radial location of the connecting holes respectively the outlets of the rotor-stator cavity are described here. The air enters axially without pre-swirl at the outer radius of the stator and leaves the rotor-stator cavity through three rotating, axially directed connecting holes at a radius depending on the investigated case, which causes axial throughflow in Case 1 and radial inflow in Case 2.

The experimental results show that the net cavity mass flow, presented in terms of a reduced mass flow parameter, increases with increasing pressure ratio, rotational Reynolds number and gap size. The increase due to a larger gap size depends on the rotation and is less prominent at higher rotational Reynolds numbers. An axial throughflow at the outer radius results in higher values of the reduced mass flow parameter, as compared to the case with radial inflow. The difference between the two cases increases with increasing rotational Reynolds number. Measured static pressure fluctuations inside the rotor-stator cavity due to the rotating nozzles can be raised up to ± 4% of the mean in the case with the small gap and the outlet at outer radius. The Pitot probe measurements show a low swirl ratio, radial outflow near the rotor and radial inflow close to the stator, which is consistent with Batchelor-type flow.
Experimental and Numerical Studies on Leading Edge Film Cooling Performance: Effects of Hole Exit Shape and Freestream Turbulence
Authors: Funazaki Ken-ichi , Kawabata Hirokazu , Takahashi Daichi , Okita Yoji
Published: August 2013

This study deals with the experimental and numerical studies of the effect of hole exit shape and free-stream turbulence on turbine blade leading edge film cooling. The study examines several test cases with two blowing ratios (BR = 1.0 and 2.0) and three mainstream turbulence intensities (1.0, 3.3 and 12.0%) using two types of leading edge models with cylindrical holes and diffuser holes [1]. The leading edge model consists of a semi-circular part of 80mm diameter and a flat after-body. In this study total pressure loss coefficient is measured by total pressure probe. Film effectiveness and heat transfer coefficient on the model surface are measured by the transient method using thermochromatic liquid crystal with video camera. In addition, detailed investigation of the film cooling is carried out using CFD simulations. RANS approach using Shear Stress Transport turbulence model and Detached Eddy Simulation (DES) approach are employed to solve the flow field. In the case of diffuser hole, the effect of mainstream turbulence intensity appears significant, and its spanwise averaged film effectiveness is decreased.
Development of a Macroscopic CFD Model for Effusion Cooling Applications
Authors: Voigt Stefan , Noll Berthold , Aigner Manfred
Published: August 2013

A CFD model was developed for simulations of effusion cooled structures like combustor liners or turbine blades. The main problem in such simulations is the mesh size, since the inclusion of the effusion cooling holes in the mesh rapidly increases the mesh size, which leads to very high computational costs. The present model circumvents this problem by replacing the effusion cooling holes with a set of mass sinks on the cold side of the cooled surface and mass sources on the hot side of the cooled surface. Furthermore, in case of a conjugate heat transfer simulation, heat sinks can be added inside the structure to account for heat loss due to convective cooling. In these cases the heat which is removed through the heat sinks is added to the mass sources as an increase in temperature. Each cooling hole is represented by one mass sink, one mass source and one heat sink in cases which include conjugate heat transfer. The main advantage of the model is a low requirement regarding the spatial resolution of the computational mesh. Node distances in the area around the cooled surface can be chosen to be as large as the effusion hole diameter. For a first validation the model has been applied to a test case comprising an effusion cooled flat plate with 7 rows of staggered cooling holes including conjugate heat transfer. Simulations of the test case show good agreement with experimental results. In this first test case the mass flow through all cooling holes was assumed to be equal. However, in realistic geometries, which include complex flows like recirculating or swirling flows, the mass flow through each cooling hole might be different, depending on the pressure distribution along the cooled surface. Therefore the model will be extended to be able to calculate the mass flow through each cooling hole separately depending on the pressure drop through the hole.
Hole Staggering Effect on the Cooling Performance of Narrow Impingement Channels
Authors: Terzis Alexandros , Wagner Guillaume , Ott Peter
Published: August 2013

This study examines experimentally the cooling performance of integrally cast impingement cooling channels which provide increased heat transfer area compared to traditional impingement configurations. For the evaluation of the heat transfer coefficient, the transient liquid crystal method was used. Full surface heat transfer coefficient distributions on the target plate and the side walls of the channel have been measured by recording the temperature history of liquid crystals using a frame grabber. Several impingement cooling geometries have been tested composing a test matrix of nine different geometrical configurations. The experimental data are analyzed by means of various post-processing procedures and aim to clarify and quantify the effect of hole staggering on the overall cooling performance, a variable which has been little addressed in the open literature. The experiments were carried out in a low speed wind tunnel over a wide range of Reynolds numbers between 15,000 and 100,000. The results indicated similarities with convectional multi-jet impingement cooling systems as well as a noticeable effect of the cooling hole pattern. Finally, an error propagation analysis of the experimental uncertainties was performed providing information for the significance of scatter on repeated experiments.
Pre-Swirl Cooling Air Delivery System Performance Study
Authors: Didenko Roman A. , Karelin Dmitry V. , Ievlev Dmitry G. , Shmotin Yuri N. , Nagoga Georgy P.
Published: August 2013

This paper reports the results from numerical simulations of the turbine blade cooling air delivery system performance using commercial CFD code Ansys CFX v11. Computations have been performed with variation of pre-swirl nozzle location radius, rotor-rotor rotating cavity width and the way of air transmission through the cover-plate. There are two ways of air transmission depending on the cover-plate design: through the CAO (circular array of orifices) or CAS (continuous annular slot). Computations are performed within the parameter range similar to gas-turbine engine operating conditions: 0.375<λT<0.98; 0.548<β0<2.5; 1.69·107<Reφ<2.33·107; 2.79·105<Cw<5.73·105.

It has been shown that the selection of optimum radius of pre-swirl nozzle location is determined by different factors and depends on design and boundary conditions. The rotor-rotor rotating cavity width does not affect delivery system performances and is selected by a designer based on the constructional necessity, strength, weight and dynamic behavior of the turbine rotor. Rotating orifices reduce the swirl ratio βb before the blade cooling rim slot reduce adiabatic effectiveness Θ and increase loss coefficient ζ.
3D Velocity and Scalar Field Measurements of an Airfoil Trailing Edge With Slot Film Cooling: The Effect of an Internal Structure in the Slot
Authors: Ling Julia , Yapa Sayuri D. , Benson Michael J. , Elkins Christopher J. , Eaton John K.
Published: August 2013

Measurements of the 3D velocity and concentration fields were obtained using magnetic resonance imaging for a pressure side cutback film cooling experiment. The cutback geometry consisted of rectangular slots separated by straight lands; inside each of the slots was an airfoil-shaped blockage. The results from this trailing edge configuration, the “island airfoil,” are compared to the results obtained with the “generic airfoil,” a geometry with narrower slots, wider, tapered lands, and no blockages. The objective was to determine how the narrower lands and internal blockages affected the average film cooling effectiveness and the spanwise uniformity. Velocimetry data revealed that strong horseshoe vortices formed around the blockages in the slots, which resulted in greater coolant non-uniformity on the airfoil breakout surface and in the wake. The thinner lands of the island airfoil allowed the coolant to cover a larger fraction of the trailing edge span, giving a much higher spanwise-averaged surface effectiveness, especially near the slot exit where the generic airfoil lands are widest.
Numerical and Experimental Investigation of Secondary Flows and Influence of Air System Design on Heavy-Duty Gas Turbine Performance
Authors: Bozzi Luca , D’angelo Enrico
Published: August 2013

High turn-down operating of heavy-duty gas turbines in modern Combined Cycle Plants requires a highly efficient secondary air system to ensure the proper supply of cooling and sealing air. Thus, accurate performance prediction of secondary flows in the complete range of operating conditions is crucial.

The paper gives an overview of the secondary air system of Ansaldo F-class AEx4.3A gas turbines. Focus of the work is a procedure to calculate the cooling flows, which allows investigating both the interaction between cooled rows and additional secondary flows (sealing and leakage air) and the influence on gas turbine performance. The procedure is based on a fluid-network solver modelling the engine secondary air system. Parametric curves implemented into the network model give the consumption of cooling air of blades and vanes. Performances of blade cooling systems based on different cooling technology are presented. Variations of secondary air flows in function of load and/or ambient conditions are discussed and justified.

The effect of secondary air reduction is investigated in details showing the relationship between the position, along the gas path, of the upgrade and the increasing of engine performance. In particular, a section of the paper describes the application of a consistent and straightforward technique, based on an exergy analysis, to estimate the effect of major modifications to the air system on overall engine performance. A set of models for the different factors of cooling loss is presented and sample calculations are used to illustrate the splitting and magnitude of losses. Field data, referred to AE64.3A gas turbine, are used to calibrate the correlation method and to enhance the structure of the lumped-parameters network models.