bluuebunny/crossref_metadata_2025_split huggingface dataset:
Combined Back-Side Cooled Combustor Liner and Variable Geometry Injector Technology
Authors: Arellano L. , Smith K. , Fahme A. 
Published: July 2014

The need to evolve next-generation ultra-lean premixed systems with advanced air management and improved liner cooling strategies have led Solar to develop a pre-production combustion system for its C50 class engine. The system uses an Augmented Backside Cooled/Thermal Barrier Coated (ABC/TBC) combustor and Variable Geometry injectors. The technology reduces both NOx and CO emissions, while improving part-load cycle efficiency.
The ABC/TBC combustor technology eliminates quenching of the reaction at the walls typically found in combustors using film-cooling techniques. Eliminating this quenching effect is not only conducive to reducing CO emissions, but it also enables the operation of the combustor primary zone at low temperatures to produce minimum thermal NOx. Coupled with a set of variable geometry injectors, the system manages air more effectively to extend the combustor operating range under which emissions and stability limits are maintained. The injectors enable the control of air entering the combustor as a function of engine load and ambient temperature. Such ability reduces the need to bleed high-pressure compressor air at part-load, thus enhancing the engine cycle efficiency.
The pre-production combustion system is currently undergoing field evaluation to assess long-term durability, characterize system performance, and develop optimum control algorithms. The development methodology and experience for this system is discussed in this paper.
CO2 Capture Using a Hydrogen Decomposed From Natural Gas Turbine
Authors: Moritsuka Hideto 
Published: July 2014

The present writer proposes a new concept of power generation system for CO2 recovery named Hydrogen Decomposed from Natural Gas Turbine (HYDET) in this paper. This concept is natural gas reforming and hydrogen separation. The natural gas is reformed with steam simultaneously the hydrogen is separated from the reformed gas through the hydrogen separation membrane. After the residual gas is combusted by the after burner with pure oxygen, CO2 steam mixture is exhausted.
An inorganic hydrogen separation membrane will be assumed to use such as ceramic multi-layer porous membranes. The performance of the proposed system will be over 50% HHV at the sending-end. Though the CO2 recovery ratio will depend upon Hydrogen and CO2 separation ratio of the membrane, theoretically it will be over 90%. And using CO2 liquefaction equipment of LNG cold heat exchanger, liquefied CO2 will be recovered with extra high efficiency. In order to apply this system, the development of the membrane reformer is the key technology.
Augmentation of Gas Turbine Power Output by Steam Injection
Authors: Fischer August C. , Frutschi Hans Ulrich , Haselbacher Hermann 
Published: July 2014

Steam injection into the combustion chambers of gas turbines (GT) increases their power output. Additionally, the thermal efficiency can be raised, if steam is generated by exhaust heat.
The types of steam injected gas turbines (STIG) are distinguished according to the kind of limit to the amount of steam that can be injected. A gas turbine is called partial STIG, if it cannot utilize the total amount of steam that could be generated by the gas turbine exhaust heat. The limit is given by the flow capacity of the turbine. If, on the other hand, the gas turbine is sized such that the entire amount of steam producible can be utilized, it is called full STIG.
Three different partial STIG cooling models were selected to analyze the power output, the efficiency and the impact on two important components. Since the differences in the results for the three cycles are marginal, the following conclusion can be briefly summarized: Compressor surge turned out to be the strongest limit for overloading the gas turbine. At the point of maximum overload — where safe operation is still guaranteed — the steam mass flow amounts to one tenth of the nominal compressor air mass flow. At this operating point, the power output can be raised by more than 30% with a simultaneous increase in efficiency.
Based on the gas turbine configurations used for the partial STIGs, the preliminary designs of two full STIG cycles have been developed. However, for full STIG operation by injection of the total amount of steam producible, either the compressor or the turbines of the original gas turbine have to be modified. In this case, the steam flow exceeding that required for cooling has to be injected into the compressed air in front of the combustor. Depending on whether the compressor is scaled down or the turbines are scaled up, the power output of full STIGs is 30 to 135% higher than that of the original gas turbine. The gross thermal efficiency is about 50.5.%.
A Unique Approach for Thermo-Economic Optimization of an Intercooled, Reheat and Recuperated Gas Turbine for Cogeneration Applications
Authors: Bhargava R. , Peretto A. 
Published: July 2014

In the present paper, a comprehensive methodology for the thermo-economic performance optimization of an intercooled reheat (ICRH) gas turbine with recuperation for cogenerative applications has been presented covering a wide range of power-to-heat ratio values achievable. To show relative changes in the thermo-economic performance for the recuperated ICRH gas turbine cycle, results for ICRH, recuperated Brayton and simple Brayton cycles are also included in the paper. For the three load cases investigated, the recuperated ICRH gas turbine cycle provides the highest values of electric efficiency and Energy Saving Index for the cogenerative systems requiring low thermal loads (high power-to-heat ratio) compared to the other cycles.
Also, this study showed, in general, that the recuperated ICRH cycle permits wider power-to-heat ratio range compared to the other cycles and for different load cases examined, a beneficial thermodynamic characteristic for the cogeneration applications. Furthermore, this study clearly shows that implementation of the recuperated ICRH cycle in a cogeneration system will permit to design a gas turbine which has the high specific work capacity and high electric efficiency at low value of the overall cycle pressure ratio compared to the other cycles studied.
Economic performance of the investigated gas turbine cycles have been found dependent on the power-to-heat ratio value and the selected cost structure (fuel cost, electric sale price, steam sale price etc.), the results for a selected cost structure in the study are discussed in this paper.
Estimation of Distributed Unbalance of Rotors
Authors: Yang Tachung , Lin Chunyi 
Published: July 2014

Mass unbalance commonly causes vibration of rotor-bearing systems. Lumped mass modeling of unbalance was adapted in most previous research. The lumped unbalance assumption is adequate for thin disks or impellers, but not for thick disks or shafts. Lee et al. (1993) proposed that the unbalance of shafts should be continuously distributed. Balancing methods based on discrete unbalance models may not be very appropriate for rotors with distributed unbalance. A better alternative is to identify the distributed unbalance of shafts before balancing.
In this study, the eccentricity distribution of the shaft is assumed in piecewise polynomials. A finite element model for the distributed unbalance is provided. Singular value decomposition is used to identify the eccentricity curves of the rotor. Numerical validation of this method is presented and examples are given to show the effectiveness of the identification method.
Stress Redistribution for Increased Creep Life in the GE MS6001 B Second Stage Blade
Authors: DiCristoforo Paul E. , Elledge Mark 
Published: July 2014

When a hot end blade for a gas turbine is designed, several failure criteria must be considered to insure reliability. The criteria include (but are not limited to) creep rupture, low cycle fatigue, high cycle fatigue and creep deflection. This paper will focus on the second stage turbine blade for the GE MS6001 industrial gas turbine. BP Amoco has experienced failure of this blade due to excessive creep deflection.
Creep deflection rate is a function of stress level and metal temperature. A typical approach to reducing creep deflection is to reduce the bulk temperature in the blade. In this paper a design is reviewed that has had the stress redistributed, so that the high temperature regions of the airfoil are at a lower stress level, thereby reducing the creep rate to an acceptable level.
Prediction of Bird Impact Pressures and Damage Using MSC/DYTRAN
Authors: Moffat T. J. , Cleghorn W. L. 
Published: July 2014

Finite element modeling of bird impacts has been developed and calibrated using the 3-D impact analysis code MSC/DYTRAN. These modeling efforts have shown that the Arbitrary Lagrange Euler (ALE) formulation within MSC/DYTRAN is capable of capturing the physics of the bird impact problem, producing impact pressures and damage similar to that of a real bird.
This work is divided into two areas. First, a review of the literature was carried out to identify the physical processes, pressures and damage associated with real bird impacts. Second, finite element modeling of two simple bird impacts cases were carried out using MSC/DYTRAN. A comparison of the finite element predictions with the experimental data showed excellent agreement, and demonstrated the robustness of the ALE formulation.
3D LES Modeling of Combustion Dynamics in Lean Premixed Combustors
Authors: Cannon Steven M. , Adumitroaie Virgil , Smith Clifford E. 
Published: July 2014

A lean premixed fuel injector/combustor typical of industrial gas turbine combustors has been analyzed using 3D Large Eddy Simulation (LES) methods. The objective of the study was to evaluate the 3D LES modeling approach for predicting combustion dynamics and compare it with simpler unsteady Reynolds Averaged Navier Stokes (RANS) methods using 2D and 3D analyses. Large amplitude pressure oscillations were observed experimentally at the modeled operating conditions, and previous 2D axisymmetric unsteady RANS analysis has shown reasonable, but not perfect, engineering agreement with pressure measurements. Although the pressure amplitude was accurately predicted, the frequency was substantially in error. This study sought to see if 3D modeling would improve the agreement.
2D axisymmetric and full 3D calculations were performed with a state-of-the-art, unstructured-grid, parallel (domain decomposition) CFD code. For the unsteady RANS calculations, the RNG k-ε turbulence model was employed, while for the LES calculation the Smagorinsky subgrid turbulence model was employed. Surprisingly, the 2D unsteady RANS, 3D unsteady RANS, and 3D LES calculations gave nearly identical pressure oscillation predictions, and all calculations had the oscillation frequency around 280 Hertz. This work has shown that smaller turbulent structures captured with 3D LES have very little effect on capturing combustion instability driven primarily by a fuel time-lag.
Development of a Variable Fuel Placement Airblast Atomiser
Authors: Morgan Leigh C. , Wheatley Alan J. , Brundish Kevin D. 
Published: July 2014

This paper presents the progress made on the development of a dual spray, direct injection airblast fuel nozzle capable of variable fuel placement. It is anticipated that by varying the fuel placement within the confines of a combustion chamber it will be possible to control localised flame ‘Fuel Air Ratio’ and thus extend both stability and emissions performance in respect of engine power range. The extension of combustion stability is particularly desirable to high pressure, temperature and turndown ratio aero engines where the ratio between maximum and flight idle fuel flows is extreme.
Atomiser aerodynamics have been developed that produce two different airflow re-circulating regions within the combustor. A concentric fuel filmer feeds each of these regions. By staging the fuel into each flame re-circulation zone the variation of local ‘Fuel Air Ratio’ can be more accurately controlled.
A combination of bench testing and CFD has been used to analyse and manipulate airflow distribution between swirlers to form the two distinct flame regions. The work is ultimately concerned with the rationalisation of airflow distribution and fuel placement to best fit the operational envelope of the engine.
The variable placement fuel injector features three or more air swirlers (inner swirler, middle swirler and dome swirler) and two ‘airblast’ fuel filmers (pilot and main).
The paper describes the progress made with a number of fuel injector configurations.
Turbulent Spots in Strong Adverse Pressure Gradients: Part 2 — Spot Propagation and Spreading Rates
Authors: D’Ovidio A. , Harkins J. A. , Gostelow J. P. 
Published: July 2014

The study of turbulent spots in strong adverse pressure gradients is of current interest in turbomachinery research. The aim of this investigation is to use information gathered from boundary layer transition and laminar separation, in wind tunnel tests on flat plates, to predict the equivalent phenomena occurring on turbomachinery blade surfaces.
In Part 1 turbulent spot behavior was documented for two Reynolds numbers, corresponding to a laminar separation bubble (LSB) and an incipient separation condition (IS). In Part 2 further results are reported characterizing typical spot propagation and spreading rates and serving to validate or modify existing correlations for predicting transition length.
Pressure and Suction Surfaces Redesign for High Lift Low Pressure Turbines
Authors: González P. , Ulizar I. , Vázquez R. , Hodson H. P. 
Published: July 2014

Nowadays there is a big effort toward improving the low pressure turbine efficiency even to the extent of penalising other relevant design parameters. LP turbine efficiency influences SFC more than other modules in the engine. Most of the research has been oriented to reduce profile losses, modifying the suction surface, the pressure surface or the three-dimensional regions of the flow. To date, the pressure surface has received very little attention.
The dependence of the profile losses on the behaviour of both pressure and suction surfaces has been investigated for the case of a high lift design that is representative of a modern civil engine LP turbine. The experimental work described in this paper consists on two different sets of experiments: the first one concluded an improved pressure surface definition and the second set was oriented to achieve further improvement in losses modifying the profile suction surface. Three profiles were designed and tested over a range of conditions. The first profile is a thin-solid design. This profile has a large pressure side separation bubble extending from near the leading edge to mid-chord. The second profile is a hollow design with the same suction surface as the first one but avoiding pressure surface separation. The third one is also a hollow design with the same pressure surface as the second profile but more aft loaded suction surface. The study is part of a wider on-going research programme covering the effects of the different design parameters on losses.
The paper describes the experiments conducted in a low-speed linear cascade facility. It gathers together steady and unsteady loss measurements by wake traverse and surface pressure distributions for all the profiles. It is shown that thick profiles generate only around 90% of the losses of a thin-solid profile with the same suction surface. The results support the idea of an optimum axial position for the peak Mach number. Caution is recommended as profile aft loading would not be a completely secure method for reducing losses.
Development of a Crack Growth Prediction System for First Stage Nozzle of Gas Turbine
Authors: Fujii Tomoharu , Takahashi Takeshi 
Published: July 2014

A system was developed for predicting the length of cracks generated in the first-stage nozzles of 1100 °C class gas turbines. The system consists of three programs, namely, crack input, crack display, and crack predicting programs, and a database containing data on 210,000 cracks generated in first-stage nozzles gathered from existing maintenance records maintained at three major power plants in Japan. The crack database also contains numerous crack data collected during inspections, operating hours and number of starts of gas turbine up to the time of inspection. The distinctive features of the system are 1) the crack data can be input as an image over the drawing of first-stage nozzles with a mouse, 2) by accumulating crack data, the sections in which most cracks occur in the first-stage nozzles can be clarified, 3) the correlation of crack length to operating time and number of starts can be analyzed simply, and 4) the length of cracks growing in any direction of any section of first-stage nozzles can be predicted.
Crack data collected from three power plants were analyzed. It was found that the cracks that were comparatively long and grew in proportion to an increase in operating time and number of starts were only 11 crack patterns as compared to the entire first-stage nozzles. The length of these 11 crack patterns was predicted for new first-stage nozzles and compared with the measured values obtained from inspection. As a result, it was verified that the crack length could be predicted.
Performance Measurement of the Second Stage of a Transonic Turbine
Authors: Seyr A. , Kulhanek G. , Neumayer F. , Rossi E. , Sanz W. 
Published: July 2014

In November 1999 the turbine test facility at the Institute for Thermal Turbomachinery and Machine Dynamics was completed. This test stand is a cold flow transonic test turbine facility, which is a unique combination of a 2.3 MW axial test turbine and a directly-coupled compressor that generates about the half of the compressed air needed to drive the turbine. To cover the losses, additional air is provided by an electrically-driven compressor station. A 600 kW suction blower driven by a helicopter gas turbine is used to decrease the exhaust pressure, thus increasing the expansion ratio up to 4.5 (see Erhard and Gehrer “Design and Construction of a Transonic Test-Turbine Facility”, ASME Paper 2000-GT-480).
Since then, flow measurements with two different transonic turbine stages have been carried out.
This paper will focus on the description of the measurement system, data analysis and the newest test results that have been obtained on a turbine stage developed by Nuovo Pignone. This stage has been configured to be representative of advanced designs for medium/small land based gas turbines and is characterized by high pressure ratios and strongly transonic effects. The characteristic feature of this stage is the convergent- divergent flow channel. Basic data of this turbine stage to obtain flow similarity are: 2.2 MW shaft power at 11500 rpm, pressure ratio 4.5, mass flow 22 kg/s. The paper will contain appropriately plotted results of dimensionless stage characteristic curves over a broad range of operation points.
Microturbine Cycle Options
Authors: Rodgers C. 
Published: July 2014

The deregulation of electric power and growing emphasis placed on distributed power generation, is establishing the need for a compact thermal energy system capable of providing the total energy needs for a small business. Natural gas fueled microturbines with ultra low emissions can fulfill this need.
The results of a study comparing the thermodynamic performances of various cycle options for microturbines in the 50 Kwe range are presented. It was determined that with current state of art component peak performance levels, and metallic materials, a thermal efficiency of 30% was attainable for the recuperated open cycle single shaft microturbine.
The challenge to success of the microturbine may not be curtailed by gas turbine component or cycle technology, insomuch as the achievement of low emissions and low cost component manufacturing techniques.
If in the future heat engines are to be regulated on net global warming potential, semi-closed cycle gas microturbines with high exhaust flow recirculation may politically penetrate the marketplace.
Physical Inactivity and Associated Factors Among Women From a Municipality in Southern Brazil
Authors: Marcellino Cristiano , Henn Ruth Liane , Anselmo Olinto Maria Teresa , Bressan Ana Weigert , Vieira Paniz Vera Maria , Pattussi Marcos Pascoal 
Published: July 2014

Background:Physical inactivity is one of the most important modifiable risk factors that is raising the global burden of chronic diseases.Methods:This is a cross-sectional, population-based study of 790 women aged 20 years or older living in the urban area of a municipality in Southern Brazil. The level of physical activity was measured using the International Physical Activity Questionnaire, short form. Inactivity was defined as fewer than 150 min/wk−1 spent in moderate or vigorous physical activities. Prevalence ratios were calculated by robust Poisson regression.Results:The prevalence of physical inactivity was 48.7% (95% CI, 43.3%–54.1%). After adjusting for confounders, we found a linear trend for increasing prevalence of physical inactivity with increasing body mass index (P = .008). Women who were married or in a domestic partnership were 29% less physically active than single women (P = .044). A borderline association was detected between the presence of minor psychiatric disorders (MPD) and physical inactivity (P = .058).Conclusions:There was a high prevalence of inactivity. Obese women, those married or in domestic partnerships and those with MPD were more likely to lead an inactive lifestyle. These results suggest that strategies are required for breaking down barriers to physical activity in this demographic group.
The Association of Adolescent Fatness and Fitness With Risk Factors for Adult Metabolic Syndrome: A 22-Year Follow-up Study
Authors: Jekal Yoonsuk , Kim YoonMyung , Yun Ji Eun , Kim Eun Sung , Naruse Masayo , Park Ji Hye , Lee Dong Hoon , Hong Seung-youn , Jee Sun Ha , Jeon Justin Y. 
Published: July 2014

Background:Few studies have been conducted to explore the associations of fatness and fitness during adolescence with risk factors of metabolic syndrome (MetS) during adulthood, particularly in Asians.Methods:Adolescent anthropometric and fitness data were collected during the participants’ high school years (N = 15,896) and their corresponding health examination data from adulthood were taken from the National Health Insurance Corporation (NHIC) in Korea. A total of 1,006 participants (6.3%) were analyzed in the study.Results:The odds ratios (ORs) for being overweight (BMI ≥ 25 kg/m2) during adulthood was 11.87 (95% CI: 4.19–33.59) in men and 8.44 (95% CI: 1.78–40.02) in women, respectively, in the fattest group vs. the leanest group during adolescence. Participants with low fitness levels during adolescence were more likely to be overweight and have abnormal MetS risk factors in adulthood vs. those with high fitness levels. Joint exposure analyses of fatness and fitness showed that male participants who were more fat and unfit during adolescence had 4.11 (95% CI: 1.19–14.14) and 3.04 (95% CI: 1.17–11.12) times higher risk of having abnormal glucose and MetS risks during adulthood, respectively.Conclusions:Fatness and fitness levels during adolescence appear to be significantly associated with the MetS risk factors and prevalence in adulthood in Koreans.