bluuebunny/crossref_metadata_2025_split huggingface dataset:
Technologies for Reducing Greenhouse Gas Emissions From Fossil Fuels
Authors: Audus Harry , Freund Paul 
Published: December 2014

In recent years, the possibility of climate change has begun to be considered seriously. Options available today can help reduce emissions at relatively little overall cost but may be able to achieve only moderate reductions. If it becomes necessary to reduce emissions further, it is likely there will be opportunities for new technologies as well as making greater use of existing ones. Bearing in mind the time required to develop and deploy new energy supply technologies on a large-scale, it is only sensible to adopt a precautionary stance. This requires better understanding of the potential of technologies not yet in widespread use and stimulation of the development and deployment of promising ones. The EEA Greenhouse Gas R&D Programme is working to improve understanding of technologies for reducing greenhouse gas emissions from fossil fuels. This is an example of effective co-operative action between different countries and industries. Membership is worldwide; through this work, members are able to learn about new technologies and share experiences. This paper reviews the work of the IEA Greenhouse Gas R&D Programme.
The established options for reducing emissions include improving energy efficiency, substitution of lower-carbon fuels for high-carbon fuels, and introduction of alternative energy sources. If deep reductions in emissions are required, discussion tends to focus on alternatives to fossil fuels even though the latter provide a very large proportion of the energy used today. To avoid disruptive changes, the world will need to be able to continue using fossil fuels but in a climate-friendly way.
Capture and storage of carbon dioxide could deliver deep reductions in emissions from fossil fuels but the technology is still in its infancy — this is the subject of on-going work by the IEA Greenhouse Gas R&D Programme. Enhancement of natural sinks, such as forests, could also help by sequestering atmospheric carbon dioxide. Use of biomass for power generation has also been examined to see how it compares as a large-scale mitigation option compared with capture and storage. Methane is another important greenhouse gas, produced by many human activities. Technology can help reduce emissions of methane; examples of some of these technologies will be described. The mechanism of Activities Implemented Jointly is potentially important for application of all of these options and the Greenhouse Gas Programme is working to improving understanding about viable options and methods of delivering successful projects.
Detailed Measurements Within a Selection of Pipe Diffusers for Centrifugal Compressors
Authors: Bennett I. , Tourlidakis A. , Elder R. L. 
Published: December 2014

It is well established that the flow between the impeller tip and the diffuser throat is very influential on the performance and flow range of a centrifugal compressor stage. Detailed measurements of a parametric selection of pipe diffusers have been carried out within this region using a combination of conventional pneumatic and high speed pressure transducers.
Four pipe diffuser designs were examined. The first and datum consisted of 31 pipes, representing a design with minimal meridional step (or sidewall expansion) between impeller tip and diffuser throat. The step size was increased to 1.3 for the second design resulting in a 22 pipe diffuser. A further increase of sidewall expansion ratio to 1.7 with 13 pipes was completed following favourable results from the 22 pipe tests. The final diffuser was of hybrid design consisting of an oval rather than circular throat cross-section. This departure allowed for a 13 pipe diffuser without sidewall expansion.
Flow range and performance comparisons are made in addition to detailed measurements which clearly show that strong planar pulsations dominate the distorted diffuser throat flow. Larger pressure pulsations are quantified for the designs with low numbers of pipes.
3D Laser Anemometry in a Rotating Cooling Channel
Authors: Servouze Y. 
Published: December 2014

The flow in rotating cooling passages of jet engine turbine rotors is considered. Contrary to thermal data which have been obtained by a lot of people, velocity field data are very few. Nevertheless, in order to validate Navier-Stokes calculations, these two types of data are necessary. In such a flow with complexe secondary structures, 3D laser anemometer is the most suitable tool but its implementation on this application was a challenge.
Measurements were made first in static mode at Reynolds numbers of 5,000 and 25,000. The same model sections were then explored during rotation at a Reynolds number of 5,000 and a Rossby number of 0.33. Some results were obtained a Reynolds number of 25,000 and a Rossby numbers of 0.033 and 0.066.
The distortion of the axial velocity profile resulting from the Coriolis acceleration appears clearly when comparing the results obtained in the sections of the centrifugal arm. In the transverse plane, the two other velocity components show the secondary flow structures with two contrarotating vortices. The results obtained in the centripetal arm show that the flow depends on the 180 deg straight-corner turn located upstream.
These measurements confirm the assumptions made on the organisation of this type of flow, and the simulation results obtained at ONERA with the MATHILDA code and also by other teams who have published papers on the subject.
The first results obtained during this experimental work demonstrate the validity of the 3D laser anemometry in such a case. They show also some insufficiencies due to an application deemed difficult.
35 Years of Operation With Rolls-Royce Marine Proteus Gas Turbines in Swedish Navy Fast Surface Attack Ships
Authors: Löfdahl Jan-Olof 
Published: December 2014

This paper covers 35 years of operation with the ROLLS-ROYCE Marine PROTEUS Gas Turbine in the Swedish Navy SPICA class Torpedo Boats and the NORRKÖPING class Missile Boats.
54 installed PROTEUS Gas Turbines in 18 boats have accumulated nearly 300 000 running hours. The service is intended to continue until year 2010.
The paper describes:
• Experience from operation.
• Technical problems and their solutions.
• Major modifications.
• Life extension program.
• Problem areas.
• The future of the PROTEUS within Swedish Navy.
The Swedish Navy operation of PROTEUS engines in fast surface attack ships is demanding and the environment is harsh. This causes great strain to the entire machinery.
With the Gas Turbine Propulsion new Ship maneuvering technique had to be developed and adopted.
Initial installation and engine problems had to be cured.
Throughout the years several technical problems have turned up and been solved.
The largest number or serious engine damages has been Power degradation and broken Compressor or burnt Turbine Blades and Vanes. Mainly as a result of a fouled Compressor, incorrect Bleed Valve setting or corrosion.
Next largest engine problem has been vibration. In the early days engine related but nowadays generated by the installation or other equipment in the ship.
All efforts laid down by involved personnel has greatly contributed to improve the reliability of the engine and its installation.
New problems will certainly show up by age and changed operational procedures, thus calling for a continued improvement work.
Spare parts accessibility will be the limiting factor for future PROTEUS operation. Therefore cooperation with ROLLS-ROYCE and the remaining operators in Spare Parts production and for exchange of Spare Parts is essential.
Simulations and Measurements on Impulse Blades for Heat Transfer Prediction in Supersonic Turbine Applications
Authors: Håll U. , Larsson J. , Bario F. , Kulisa P. , Slimani J. , Begin V. , Eriksson L.-E. , Wåhlén U. 
Published: December 2014

This paper presents an overview of a research project aimed at improving the currently available methods to predict the flow and heat transfer in uncooled supersonic impulse turbines. These turbines are typically used in rocket engines based on the gas-generator cycle.
A fast boundary-layer method, suitable in the design phase, is presented. This method includes effects related to curvature, transition and separation bubbles.
For more detailed analysis, Navier-Stokes methods are used. Experiences from using a wide range of two-equation models to predict turbine blade heat transfer are summarized.
The experimental work uses a scaled-up, heated, linear blade cascade. The aim is to gain fundamental insight into the phenomena involved in turbine blade heat transfer and to obtain data for validation and development of new numerical methods. Detailed measurements, of both averaged and fluctuating properties of the velocity field, are made in the boundary layers down to a Y+ below 10. The results presented here are focused on the leading edge.
Recuperators in Gas Turbine Systems
Authors: Utriainen Esa , Sundén Bengt 
Published: December 2014

The application of recuperators in advanced thermodynamic cycles is growing due to stronger demands of low emissions of pollutants and the necessity of improving the cycle efficiency of power plants to reduce the fuel consumption.
This paper covers applications and types of heat exchangers used in gas turbine units. The trends of research and development are brought up and the future need for research and development is discussed. Material aspects are covered to some extent.
Attempts to achieve compact heat exchangers for these applications are also discussed. With the increasing pressure ratio in the gas turbine cycle, large pressure differences between the hot and cold sides exist. This has to be accounted for.
The applicability of CFD (Computational Fluid Dynamics) is discussed and a CFD–approach is presented for a specific recuperator. This recuperator has narrow wavy ducts with complex cross-sections and the hydraulic diameter is so small that laminar flow prevails. The thermal-hydraulic performance is of major concern.
Design and Experimental Verification of an Optimised Compressor Blade
Authors: Bogers P. F. , Van den Braembussche R. A. , Breugelmans F. A. E. 
Published: December 2014

This paper deals with the design of an optimised compressor blade and the experimental verification of its performance at design and off-design operation.
Starting from an existing controlled-diffusion blade, a new two-dimensional blade section has been designed by means of an inverse method, maintaining the same flow turning. Optimisation is made to achieve lower losses over an incidence range of 10 degrees while care has been taken to keep the blade thickness within prescribed tolerances.
The blade has been manufactured and tested in the C1 low speed cascade tunnel of the von Karman Institute. Experiments confirm substantial performance improvements at the blade mid section over the whole range of incidences. Measurements near the side walls show that the secondary flow losses are unchanged.
Verifications with a Navier-Stokes solver show a remarkable agreement with measurements and flow visualisations and explain the reasons for the important performance improvement at high incidence.
Air System Correlations: Part 1 — Labyrinth Seals
Authors: Zimmermann H. , Wolff K. H. 
Published: December 2014

Three important subjects of the physics of air systems have been chosen,
Part 1: Labyrinth Seals
Part 2: Rotating Holes and Two Phase Flow
as in these fields many new papers, partly controversial, are available. A new method of correlating the throughflow for labyrinth seals is generated, it covers the most important parameters and is based on several sources out of the literature. Recommendations for the necessary further research are added. It is concluded that much more effort is required in order to achieve progress against the literature partly consisting of more than 40-year-old books and not comprehensive enough for computerized engineering.
Field Experience of the Sequential Combustion System for the GT24/GT26 Gas Turbine Family
Authors: Joos Franz , Brunner Philipp , Stalder Marcel , Tschirren Stefan 
Published: December 2014

The first units of the Sequential Combustion System gas turbine family are in commercial operation. The first gas turbine GT24 (60Hz, 165MW-class) started the commercial operation, while the first GT26 (50Hz, 265MW-class) demonstrates its performance at the GT test facility. More engines are presently in the commissioning phase or will be in the near future. These turbines are designed to offer increased output at high GT efficiency. To acheive this, the sequential combustion system, a reheat process with two combustors, has been developed. Whereas the first combustor is based on the proven EV-combustor technology, extensive research and development efforts have been carried out in developing the lean premixed self-igniting second combustor (SEV).
This paper is a follow-up of the ASME paper 96-GT-315, which described the basic research work concerning the lean premixing SEV-burners with self-ignition. The present paper reports the experience gained during commissioning of the first engines.
The performance of the two combustors, as well as the measured emissions, are discussed and compared with the expected values and rig test results.
Finally, the potential of the sequential combustion system to reach low NOx levels is demonstrated by unveiling the results of the extensive testing program during the commissioning phase.
Validation of Numerical Methods at a Confined Turbulent Natural Gas Diffusion Flame Considering Detailed Radiative Transfer
Authors: Ganz Benedikt , Schmittel Peter , Koch Rainer , Wittig Sigmar 
Published: December 2014

Radiation heat transfer in flames depends strongly on local quantities such as pressure, temperature and concentration of participating species. In the present study, 3D numerical calculations of radiative heat transfer together with the reacting flow field are compared to detailed measurements of the velocity, temperature and spectral radiation field of a model combustor.
The geometry of the combustion chamber (dch = 0.5m), the flame configuration (type-II swirling, diffusion flame) and the highly turbulent flow conditions resemble the characteristics of industrial combustors.
The concentrations of CO2, H2O, CO, CH4, NO, NOx, O2 and H2 as well as local mean temperatures and their fluctuations were recorded at 300 locations at 14 axial planes. The radiation intensity incident on the wall was measured spectrally and time resolved at 11 axial planes within the spectral range of 1.4 to 5.4 μm.
For numerically solving the reacting flow field, spectral methods for calculating the radiative heat transfer were coupled to fluid mechanical methods for calculating the reacting flow.
The agreement between numerical prediction and measurements for the reacting flow field as well as for the radiative heat transfer is reasonably good. The numerical computations show that radiative transfer is of major importance. The temperature in the hot reaction zone was found to be lowered by approximately 400 K by radiative losses.
The Effect of the Fuel Injector Internal Geometry Upon the Primary Zone Aerodynamics
Authors: Hicks R. A. , Whiteman M. , Wilson C. W. 
Published: December 2014

One of the major aims of research in gas turbine combustor systems is the minimisation of non-desirable emissions. The primary method of reducing pollutants such as soot and NOx has been to run the combustion primary zone lean. Unfortunately, this causes problems when the combustor is run under idle and relight conditions as the primary zone air fuel ratio (AFR) can exceed the flammability limit.
Altering this AFR directly affects the primary zone aerodynamics through changes in the spray profile. One method of determining the influence of changes in AFR upon the primary zone is to use Computational Fluid Dynamic (CFD) models. However, to model the flow through an air-blast fuel injector and accurately predict the resulting primary zone aerodynamics requires hundreds of thousands, if not millions, of cells. Therefore, with current computer capabilities simplifications need to be made.
One simplification is to model the primary zone as a 2-D case. This reduces the number of cells to a computationally solvable level. However, by reducing the problem to 2-D the ability to accurately model air-blast fuel injectors is lost as they are intrinsically 3-D devices. Therefore, it is necessary to define boundary conditions for the fuel injector.
Currently, due to difficulties in obtaining experimental measurements inside a air-blast fuel injector, these boundary conditions are often derived using semi-empirical methods. This paper presents and compares two such models; the model proposed by Crocker et al. in 1996 and one developed at DERA specifically for modelling air-blast fuel injectors.
The work also highlights the importance of the often neglected radial component upon the primary zone aerodynamics.
Numerical Simulation of the Flow Through the Return Channel of Multi-Stage Centrifugal Compressors
Authors: Lenke L. J. , Simon H. 
Published: December 2014

The numerical simulation of the flow within a return channel is reported in this paper. The investigated return channel is typically to join the exit from one stage of a centrifugal machine to the inlet of the next stage. These channel covers the range of extremely low flow coefficients.
Different 3-D calculations with two different turbulence models (low-Reynolds-number k-ϵ and explicit algebraic Reynolds stress model) at the design point and part load range show the strongly three-dimensional flow structure with secondary flows on hub and shroud of the deswirl vanes. There are also significant separations downstream of the 180°-bend at suction and pressure side of the vanes.
The presented numerical results are compared with experimental data in different planes and at the vane contour. The results indicate small differences between the turbulence models in the prediction of losses, flow angles and separation behavior at design point. At off-design conditions the turbulence models begin to deviate notably in their prediction of separation.
Nonlinear Heat-Release/Acoustic Model for Thermoacoustic Instability in Lean Premixed Combustors
Authors: Peracchio A. A. , Proscia W. M. 
Published: December 2014

Lean premixed combustors, such as those used in industrial gas turbines to achieve low emissions, are often susceptible to thermoacoustic combustion instabilities, which manifest themselves as pressure and heat release oscillations in the combustor. These oscillations can result in increased noise and decreased durability due to vibration and flame motion. A physically based nonlinear parametric model has been developed that captures this instability. It describes the coupling of combustor acoustics with the rate of heat release. The model represents this coupling by accounting for the effect of acoustic pressure fluctuations on the varying fuel/air ratio being delivered to the flame, causing a fluctuating heat release due to both fuel air ratio variations and flame front oscillations. If the phasing of the fluctuating heat release and pressure are proper, an instability results that grows into a limit cycle. The nonlinear nature of the model predicts the onset of the instability and additionally captures the resulting limit cycle.
Tests of a lean premixed nozzle run at engine scale and engine operating conditions in the UTRC Single Nozzle Rig, conducted under DARPA contract, exhibited instabilities. Parameters from the model were adjusted so that analytical results were consistent with relevant experimental data from this test. The parametric model captures the limit cycle behavior over a range of mean fuel air ratios, showing the instability amplitude (pressure and heat release) to increase and limit cycle frequency to decrease as mean fuel air ratio is reduced.
Effects of Compressibility and Turbulence Level on Bypass Transition
Authors: Schook R. , de Lange H. C. , van Steenhoven A. A. 
Published: December 2014

The influences of compressibility and turbulence level on boundary layer transition are studied using a Ludwieg tube set-up. Heat transfer measurements are performed on the flow over a flat plate. The Mach number is varied between 0.16 and 0.56 while the unit-Reynolds number is kept constant. Several turbulence generating grids are used giving turbulence levels between 1.2% and 4.4%. Increasing the Mach number results in a decreasing turbulence level. Besides, the transition start Reynolds number increases.
The results indicate that besides the turbulence level another parameter is desired for the existing transition models. The dimensionless spot parameter is influenced by both the turbulence level and the Mach number. A tentative conclusion is that the start of transition depends on the inertial range minimum frequency in the energy spectrum while the shape of the transition curve, i.e. the intermittency, depends on the corresponding length scale.
The Potential of Sequential Combustion for High Bypass Jet Engines
Authors: Vogeler Konrad 
Published: December 2014

ABB has designed a new family of industrial gasturbines for power generation using a Sequential Combustion Cycle (SCC) on a large single shaft engine. This concept allows considerable increase in power density and efficiency by only increasing pressure without raising the maximum hot gas temperature of the cycle. Instead a second combustion after an HP-turbine is used to reheat the gas before the final expansion in an LP-turbine.
This concept is applied to the analysis of a high bypass ratio jet engine. In an engine with a single combustor, thrust is a function of bypass ratio and the combination of maximum pressure and temperature in the cycle. The proposed SCC allows increased thrust without pushing technology on materials and cooling. A modern twin spool engine is taken as reference. When total inlet massflow is kept constant, increasing bypass ratio decreases core mass flow. This limits the fuel flow for the HP-spool and hence total energy input to the engine. Introduction of the SCC gives another parameter of freedom to the cycle design. However the twin spool concept is now a disadvantage. The low fuel flow for the HP-spool due to high bypass ratio means there is not enough energy available to build up the necessary pressure for an economical expansion in the LP-turbine after the second combustion. Specific fuel consumption will be unacceptable.
It is proposed to apply the SCC concept in a single spool engine with a geared fan. Both turbines can now support the compression. The fan is operated as a constant speed propeller with variable blade pitch. This engine concept allows for a given inlet massflow a substantially higher bypass ratio and hence decreases specific fuel consumption while specific thrust can be kept on a level which will be considerably higher than it would be in todays engines with comparable bypass ratio.