bluuebunny/crossref_metadata_2025_split huggingface dataset:
Representative Bureaucracy: A Lever to Enhance Social Equity, Coproduction, and Democracy
Authors: Riccucci Norma M. , Van Ryzin Gregg G. 
Published: September 2016

AbstractScholars and practitioners have long questioned whether the race, ethnicity, and gender of public bureaucrats matter to the efficacy and legitimacy of public services. Representative bureaucracy theory and research provide a growing body of empirical evidence that it does. This article examines some of the rich scholarly work that has been generated on representative bureaucracy and its implications for practice. A significant aspect of recent research focuses on the notion of symbolic representation, whereby the mere existence of a passively represented bureaucracy can itself improve outcomes by influencing the attitudes and behaviors of clients, regardless of bureaucratic actions or results. This article is intended to help both students and public managers understand the importance of representativeness in public organizations for a broad spectrum of practices and goals, from the coproduction of services to democratic rule.
Different ways of knowing a child and their relations to mother‐reported autonomy support
Authors: Mageau Geneviève A. , Sherman Amanda , Grusec Joan E. , Koestner Richard , Bureau Julien S. 
Published: September 2016

AbstractWe considered how different forms of child knowledge (i.e., mothers’ reports of taking their child's perspective, their accurate knowledge in the form of precise predictions of their child's ratings regarding distress/comforting and compliance/discipline situations, and their perceived knowledge) are differentially associated with mother‐reported autonomy support (i.e., providing meaningful rationales, providing choice, and acknowledging feelings; Koestner, Ryan, Bernieri, & Holt, ). Mothers and their children (141 dyads, M = 11 years old at Time 1) participated in a two‐wave longitudinal study with assessments made two years apart. The only form of knowledge that predicted changes in autonomy support was perspective‐taking. Autonomy support, in turn, indirectly predicted changes in distress/comforting accuracy through child‐reported self‐disclosure and directly predicted changes in perceived knowledge. These findings underline the importance of differentiating among forms of child knowledge in the study of socialization processes.
Whose Reality Counts? Critical Junctures in Livelihood Trajectories Under Deforestation
Authors: Biddulph Robin , Amberntsson Pelle 
Published: September 2016

AbstractLivelihoods approaches focus on the poor and their knowledge and agency, but risk underplaying broader contextual forces which constrain and shape that agency. Livelihood trajectories approaches attend more fully to these structural, contextual dynamics. A three‐year study using quantitative and qualitative methods investigated livelihood trajectories over two decades in a village affected by deforestation in Northeast Cambodia, and sought to identify critical junctures structuring those trajectories. A timber rush, a land rush, a turn to agriculture and ongoing competition to shape post‐forest reterritorialisation were identified as the critical junctures. These transformed the physical environment, and initiated waves of migration which in turn transformed the social and economic structure and everyday life of the village. This valuably disrupts narrative simplifications associated with community forestry. The junctures furthermore suggest an analytical framework for understanding deforestation‐livelihoods dynamics in other contexts, thus demonstrating how livelihood trajectories research might contribute to middle‐level theory building.
Experimental Evaluation of Compressor Blade Fouling
Authors: Kurz Rainer , Musgrove Grant , Brun Klaus 
Published: September 2016

Fouling of compressor blades is an important mechanism leading to performance deterioration in gas turbines over time. Experimental and simulation data are available for the impact of specified amounts of fouling on performance, as well as the amount of foulants entering the engine for defined air filtration systems and ambient conditions.
This study provides experimental data on the amount of foulants in the air that actually stick to a blade surface for different conditions of the blade surface. Quantitative results both indicate the amount of dust as well as the distribution of dust on the airfoil, for a dry airfoil, as well as airfoils that were wet from ingested water, as well as different types of oil. The retention patterns are correlated with the boundary layer shear stress. The tests show the higher dust retention from wet surfaces compared to dry surfaces. They also provide information about the behavior of the particles after they impact on the blade surface, showing that for a certain amount of wet film thickness, the shear forces actually wash the dust downstream, and off the airfoil. Further, the effect of particle agglomeration of particles to form larger clusters was observed, which would explain the disproportional impact of very small particles on boundary layer losses.
The Design and Testing of a Low Reaction Turbine Blade Profile for HP and IP Steam Flow Path
Authors: Deng Guoliang , Sun Qi , Wu Qilin , Fan Xiaoping , Yin Mingyan , Tian Chaoyang , Ping Yan 
Published: September 2016

The design of a low reaction turbine blade profiles was carried out to improve the steam flow efficiency. The blade profiles geometry design for both the stationary and moving blades and reprofiling of them are done using Vista ATBlade, according to the aerodynamic analysis results from the cascade analysis code MISES.
The original stator profile is aft-loaded, and the new one present in this paper is highly-aft-loaded (HAL) to depress the development of secondary flow further, while maintaining even lower profile loss and wider incidence angle tolerance. The newly designed moving blade is more robust compared with the original one, thus it has larger aspect ratio under the same blade section average stress level, and with better incidence tolerant capability as well.
The planar cascade air tests were first carried out to verify the stator profile loss improvement, with a decrease of energy loss coefficient of almost 0.8% obtained under the Reynolds number of about 1e6. Then the annular cascade air tests with fully 360 degrees stator blades installed were conducted to validate the reduction of endwall loss and the profile loss as well, and to measure the mass flow capability (real mass flow/ideal mass flow).
Finally, two three-stage tests for the original blades and the new one were developed to verify the improvement under real multi-stages flow conditions. All the stages for both tests are designed with the hub reaction of about 15%, without interstage swirl, in the design condition. The flow probes at upstream of first stage stator and downstream of last stage moving blade, the hydraulic dynamometer and the flowmeter are used to test the overall efficiency. Three traverse planes are located at the upstream, middle and downstream of the second stage to measure the flow properties using five hole pneumatic probes. The test results showed a increase of overall efficiency of about 1.5%.
The CFD simulations showed very good agreement of mass flow capability with the tests, for both the stator annular and multi-stage tests.
The application of the newly designed blade profiles in SanHe subcritical reheat 300MW steam turbine (16.7MPa/537°C/537°C) retrofit gives the final proof of the efficiency improvement. The measured efficiency showed remarkable performance, with an increase of efficiency of 1.5%–2.2% for both the HP and IP cylinder.
Steady-State Power Operation of a Supercritical Carbon Dioxide Brayton Cycle With Thermal-Hydraulic Control
Authors: Clementoni Eric M. , Cox Timothy L. , King Martha A. 
Published: September 2016

The Bechtel Marine Propulsion Corporation (BMPC) Integrated System Test (IST) is a two shaft recuperated closed Brayton cycle using supercritical carbon dioxide (sCO2) as the working fluid. The IST is a simple recuperated Brayton cycle with a variable speed turbine driven compressor and a constant speed turbine driven generator designed to output 100 kWe. The main focus of the IST is to demonstrate operational, control, and performance characteristics of an sCO2 Brayton power cycle over a wide range of conditions.
IST operation has reached the point where the system can be run with the turbine-compressor thermal-hydraulically balanced so that the net power of the cycle is equal to the turbine-generator output. In this operating mode, power level is changed by using the compressor recirculation valve to adjust the fraction of compressor flow that goes to the turbines as well as the compressor pressure ratio. Steady-state operational data and trends are presented at various system power levels from near zero net cycle power to maximum operating power using a simplified thermal-hydraulic based control method. Confirmation of stable steady-state operation of the system with automatic thermal-hydraulic control is also discussed.
Alleviation of Rotating Pressure Oscillations in the Last LP Turbine Stage During Low-Load Conditions
Authors: Haller B. R. , Rice T. S. , Sigg R. 
Published: September 2016

In Steam Turbines, under low flow conditions, the flow structure on the long last stage blades is complex. The rotor blades create outward radial flow. Recirculations are setup near the tip in the gap between the fixed and moving blades, and near the hub downstream of the moving blade. The blade carries negative loading and encounters gross flow separations. In this environment, fluctuations in pressure are detected rotating at about half of the rotor speed. Some similarities exist with rotating stall, as found in compressors. In the validation of a new blade design, checks are therefore included to ensure that the rotating excitation does not pass over a natural frequency of the blading. In turn, this can reduce the available design space.
A less restrictive approach is to consider alleviation techniques. A promising candidate is a scheme where steam jets are directed into the flow, onto the LSB, from the outer boundary. Jets have been introduced and tested on a 1/3rd scale multistage steam turbine. The test turbine is both aerodynamically and mechanically representative of a full size machine. The blowing scheme was shown to reduce and then practically eliminate the rotating pressure pattern. 3D CFD computations reveal the major influence of the jets. The solution is elegant because it does not lead to loss of efficiency or design space.
Gas Compression Optimization for Changing Pipeline Landscape
Authors: Zhang Donghui , Kurz Rainer , Lubomirsky Matt , Garcia David , Singh Avneet , Troya Alex 
Published: September 2016

The natural gas midstream gathering and pipeline landscape has become much more dynamic in recent years. Some of the attributes contributing to these continuous changes in operations are due to increased supply from shale gas explorations in North America and increasing natural gas demand in Asia. These changes require new pipelines and compressor stations to be built or existing pipelines and compressor stations to be modified to match new required operating conditions.
Economic factors such as initial capital investment and life cycle costs are very important considerations in the decision process to evaluate the benefits of building new stations or modifying existing stations. This paper presents a discussion of some of the more fundamental factors to be considered in evaluating the economics of station optimization projects, and also introduces a variety of options to manage the lifecycle of the centrifugal gas compressors units and stations.
Transient Lift-Off Test Results for an Experimental Hybrid Bearing in Air, Simulating a Liquid Hydrogen Turbopump Start Transient
Authors: Childs Dara W. , Klooster David , Borchard Henry , Pavelek Dustin , Phillips Stephen 
Published: September 2016

Start-transient testing of a hybrid (combined hydrostatic and hydrodynamic action) bearing supplied with air was completed, providing an indication of its performance while operating in a compressible fluid medium. The test start transients were modeled after Rocket Engine Transient Simulation Software (ROCETS) predictions for start-transient behavior of running speed ω(t) and bearing supply pressure Ps(t). The top test speed was 15 krpm. The ramp rate, supply pressure Ps values at 15 krpm, constant bearing unit load magnitude w0, and load orientation (load-on-recess LOR or load-on-land LOL) were varied. Five different load-case combinations were carried out (separately) for LOR and LOL load configurations with ramp rates varying from 2206 rpm/s to 8824 rpm/s. The target pressures at 15 krpm varied from 5.32 bars to 18.25 bars.
The tested bearing dimensions were: L = D = 38.1 mm, and Cr =.0635 mm. Lift-off occurs due to the increase in Ps (ω dependent) and was defined as the point of departure towards the center of the bearing with increasing ω while the rotor remained 0.00254 mm (0.1 mils) above the bearing surface. This method is limited by the inability to accurately measure an established operating bearing clearance.
Evaluation of the lift-off Ps versus applied unit load w0 supports the following conclusions: (1) Lift-off Ps is approximately a linear function of w0, (2) Changing the ramp rate while keeping constant the specified Ps at 15 krpm has no significant impact, (3) Lowering the limit Ps at 15 krpm may reduce the lift-off Ps value, and (4) The LOR start-transient cases required a higher lift-off speed and lift-off Ps values than the corresponding LOL start-transient cases.
Flow Field Characterization at the Outlet of a Lean Burn Single Sector Combustor by Laser-Optical Methods
Authors: Schroll M. , Doll U. , Stockhausen G. , Meier U. , Willert C. , Hassa C. , Bagchi I. 
Published: September 2016

High OPR engine cycles for reduced NOx emissions will generate new aggravated requirements and boundary conditions by implementing low emission combustion technologies into advanced engine architectures. Lean burn combustion systems will have a significant impact on the temperature and velocity traverse at the combustor exit. Lean burn fuel injectors dominate the combustor exit conditions. This is due to the fact that they pass a majority of the total combustor flow, and to the lack of mixing jets like in a conventional combustor. With the transition to high pressure engines it is essential to fully understand and determine the high energetic interface between combustor and turbine to avoid excessive cooling, which has a detrimental impact on turbine and overall engine efficiency.
Velocity distributions and their fluctuations at the combustor exit for lean burn are of special interest as they can influence the efficiency and capacity of the turbine. Within the EU project LEMCOTEC, a lean burn single sector combustor was designed and built at DLR, providing optical access to its rectangular exit section. The sector was operated with a fuel staged lean burn injector from Rolls-Royce Deutschland. Measurements were performed under various operating conditions, covering idle and cruise operation. Two techniques were used to perform velocity measurements at the combustor exit in the demanding environment of highly luminous flames under elevated pressures: Particle Image Velocimetry (PIV) and Filtered Rayleigh Scattering (FRS). The latter was used for the first time in an aero-engine combustor environment. In addition to a conventional signal detection arrangement, FRS was also applied with an endoscope for signal collection, to assess its practicality for a potential future application in a full annular combustor with restricted optical access. Both measurement techniques are complementary in several respects, which justified their respective application and comparative assessment. PIV is able to record instantaneous velocity distributions and is therefore capable to deliver higher velocity moments, in addition to temporal averages. Applied in two orthogonal traversable light sheet arrangements, it could be used to map all three velocity components across the entire combustor cross section, and obtain data on velocity variances, cross-correlations and turbulence intensities. FRS is limited to measurements of average velocities, as long sampling times are required due to the weak physical process of Rayleigh scattering. However, FRS has two advantages: It requires no particle seeding, because it is based on the measurement of a molecular Doppler shift, and it can provide temperature information simultaneously. This contribution complements a second paper (GT2016-56370) focusing on the measurement of temperature distributions at the same combustor exit section by laser-based optical methods.
sHAWT Design: Airfoil Aerodynamics Under the Influence of Roughness
Authors: Holst D. , Pechlivanoglou G. , Kohlrausch C. T. , Nayeri C. N. , Paschereit C. O. 
Published: September 2016

Small horizontal axis wind turbines (sHAWTs) are mostly designed by smaller companies with no or just small possibilities of aerodynamic testing and hence, airfoil selection is often based on published performance data and minimal or no experimental testing from the blade designer’s side. This paper focuses on the aerodynamic consequences resulting from an unqualified airfoil selection and accumulating surface soiling. The high performance low Reynolds profile FX 63-137 is compared to an Eppler-338 wing section as well as to a high performance utility scale wind turbine airfoil, AH 93-W-174 -1ex. We extensively investigated these three different airfoils within the low Reynolds regime between 50,000 and 200,000. This regime is especially important for the starting behavior of a wind turbine, i.e. a quick speed up, and is crucial for small wind turbines because they have more frequent start/stop events. A Reynolds number of 200 k is additionally the operational regime of some sHAWT under the 5–10 kW level.
The present study discusses not only the low Reynolds performance of the smooth profiles but investigates the influence of surface soiling. This ranges from 2D disturbances, such as a 0.2mm thin tripwire or several zigzag tapes, up to the simulation of massive sand build up by covering the entire leading edge region with a 40 grit sand paper. The experiments reveal that even small surface soiling has an impact and massive roughness leads in some cases to the loss of 50% in lift coefficient. The experimental data is used to simulate a sHAWT in different stages of debris. While the peak power was reduced by two thirds compared to the clean configuration the annual energy production has halved under certain conditions.
Numerical Aerodynamic Damping Evaluation of High-Pressure Steam Turbine Blades for Aeromechanical Characterization
Authors: Peruzzi Lorenzo , Bellucci Juri , Pinelli Lorenzo , Arnone Andrea , Arcangeli Lorenzo , Cosi Lorenzo , Mazzucco Marco 
Published: September 2016

A validated non-linear uncoupled method for flutter stability analysis was employed to estimate the aerodynamic damping of an HP (High-Pressure) steam turbine blade row.
Usually such blade rows are not affected to flutter instability problems, yet an estimation of the aerodynamic damping can be useful for an accurate aeromechanical characterization of these kind of blade rows. The geometry under investigation is a typical steam turbine blade row at design point. Computational aeroelastic analyses are performed on the more relevant modeshape, sampling the nodal diameters, in order to well describe the typical aeroelastic stability curve. The presence of the tip shroud implies a strong mechanical coupling between adjacent blades resulting in complex modeshapes with high frequency, significantly different from those usually analyzed in the flutter analysis.
The results in term of aerodynamic damping curves are rather different from the usually sinusoidal shape. This is due to the large variation of the frequency over the analyzed nodal diameters, especially at low nodal diameters range. This results are useful to give a better insight in the aeroelastic response of this type of blades.
Heat Transfer Investigation in a Smooth Rotating Channel With Thermography Liquid Crystal
Authors: You Ruquan , Li Haiwang , Tao Zhi , Wei Kuan 
Published: September 2016

An experiment investigation was conducted in a smooth cooling channel under rotating conditions on a new rotating facility. The heat transfer phenomenon of rotating channel with constant heat flux boundary conditions was measured using PIV and TLCs (Thermography Liquid Crystal). The square cross-section channel is manufactured from Plexiglas. Four 1 mm thick transparent ITO (Indium Tin Oxide) heater glasses taped on four Plexiglas walls independently to provide the same constant heat flux boundary conditions. The size of the heated channel is 600 mm*80 mm*80 mm.
TLCs was used for measuring the two-dimensional detail distribution of the temperature on the leading surface and trailing surface of the channel. The pixel-level calibration method was used for reducing the error of the TLCs. In the experiments, the Reynolds number, based on the channel hydraulic diameter (D) of 80 mm and the bulk mean velocity, is 20000, and the rotation number are 0, 0.068, 0.135, 0.205, 0.273, respectively. The obtained result shows that rotation has an important different effects on the heat transfer of leading and trailing side. On the trailing side, the heat transfer increases with the rotation number monotonically along the stream wise (X direction), and rotation enhances the local Nu/Nus up to 20%. On the leading side, rotation weakens the Nu/Nus around 25% with the rotation number of 0.273. However, on the leading side, with the increase of rotation number, the Nu/Nus is not decreasing monotonically along the stream wise, there is a slight enhancement (turning point) along the stream wise with different rotation numbers. The position of turning point on the leading side is different with various rotation numbers. With higher rotation number, the turning point moves closer to the inlet of the channel. This phenomenon is an important reference to investigate the flow field in our future work with PIV. More details of two-dimensional distribution Nu on the leading and trailing side will be shown in this work.
S-CO2 Turbine Design for Decay Heat Removal System of Sodium Cooled Fast Reactor
Authors: Cho Seong Kuk , Lee Jekyoung , Lee Jeong Ik , Cha Jae Eun 
Published: September 2016

A Sodium-cooled Fast Reactor (SFR) has receiving attention as one of the promising next generation nuclear reactors because it can recycle the spent nuclear fuel produced from the current commercial nuclear reactors and accomplish higher thermal efficiency than the current commercial nuclear reactors. However, after shutdown of the nuclear reactor core, the accumulated fission products of the SFR also decay and release heat via radiation within the reactor. To remove this residual heat, a decay heat removal system (DHRS) with supercritical CO2 (S-CO2) as the working fluid is suggested with a turbocharger system which achieves passive operational capability. However, for designing this system an improved S-CO2 turbine design methodology should be suggested because the existing methodology for designing the S-CO2 Brayton cycle has focused only on the compressor design near the critical point.
To develop a S-CO2 turbine design methodology, the non-dimensional number based design and the 1D mean line design method were modified and suggested. The design methodology was implemented into the developed code and the code results were compared with existing turbine experimental data. The data were collected under air and S-CO2 environment. The developed code in this research showed a reasonable agreement with the experimental data. Finally using the design code, the turbocharger design for the suggested DHRS and prediction of the off design performance were carried out. As further works, more effort will be put it to expand the S-CO2 turbine test data for validating the design code and methodology.