bluuebunny/crossref_metadata_2025_split huggingface dataset:
Full Load and Part-Load Performance Prediction for Integrated SOFC and Microturbine Systems
Authors: Campanari Stefano 
Published: December 2014

During the last years, two new subjects among the others have risen interest in the field of small scale electric power generation: advanced microturbines and Solid Oxide Fuel Cells.
This paper investigates the thermodynamic potential of the integration of the Solid Oxide Fuel Cell technology with microturbine systems, in order to obtain ultra-high efficiency small capacity plants, generating electric power in the range of 250 kW with 65% LHV net electrical efficiency and with the possibility of cogenerating heat. A detailed description of the calculation model is presented, capable of full and part-load performances analysis of the microturbine and of the integrated SOFC+microturbine system.
The NEREUS Installation — The Non-Nuclear Part (GT)
Authors: Crommelin G. A. K. 
Published: December 2014

This paper should be read in conjunction with the paper The NEREUS installation — the nuclear part (HTR). This part will discuss the non-nuclear part of the nuclear gas turbine installation called the NEREUS installation.
It will discuss the non-nuclear part of a modular energy production installation consisting of an inherently safe, helium cooled, graphite moderated nuclear reactor, which acts as heat source to an energy conversion unit consisting of a closed-cycle recuperative gas turbine driving a generator (abbreviated as HTR-GT) (see also ref. 11 and 12). The paper is based upon an ongoing study, supported by specialists and scientists, among others of the Delft University of Technology, of most aspects concerning this type of power producing unit. This paper will discuss its (non-nuclear) components, efficiency, market potential and costing in comparison with existing and comparable installations. So it will report on a pre-feasibility study, based upon existing reports, publications, estimations by specialists and from active projects.
A Supercharged Turbojet for High Altitude Atmospheric Science Investigations
Authors: Cyrus John D. , Bents David J. , Overholt David M. 
Published: December 2014

A study was conducted for NASA Dryden Flight Research Center to investigate the viability of developing an externally powered zero stage booster fan to boost the altitude performance of a high altitude turbojet from 80 kft. to over 90 kft., in order to realize a very high altitude subsonic remotely piloted aircraft (RPA) capable of atmospheric science missions.
A modified non-airbreathing torpedo engine powers the booster fan. The powered fan is grafted onto an airbreathing turbojet (the General Electric YJ97 jet engine) and is used to supercharge the engine (boost inlet pressure and airflow) at altitudes above its original design limits. The inlet boost keeps the engine operating and delivering thrust, at subsonic speeds, to mission altitudes over 95,000 ft.
If this modified engine were grafted back into the air vehicle it was originally designed for (the Viet Nam era AQM-91A Compass Arrow) the modifications would enable the vehicle to increase its maximum altitude from 80,000 ft to over 88,000 ft for periods up to 45 min. With some additional wing area, the aircraft, which is in the 5000 lbm TOGW class, could carry a 500 lbm payload to altitudes over 92,000 kft with an operational radius over 1500 NMi.
This study examined a number of candidate component arrangements to realize this fan-boosted propulsion system. Performance was estimated for the subsystem components, the resulting propulsion systems, and the associated RPA. In addition, the study estimated the time and cost to demonstrate/validate this concept in a full-scale propulsion system wind tunnel test program.
This paper describes the concept, summarizes the concept selection efforts and performance analysis conducted during the study, and explains the rationale behind this unusual approach. A description of the proposed development and test program, and the cost estimate, lies beyond the scope of this paper.
Prediction of Thermoacoustic Instabilities With Focus on the Dynamic Flame Behavior for the 3A-Series Gas Turbine of Siemens KWU
Authors: Krüger Uwe , Hüren Jens , Hoffmann Stefan , Krebs Werner , Bohn Dieter 
Published: December 2014

Self-induced combustion driven oscillations are a crucial challenge in the design of advanced gas turbine combustors. Lean premixed combustion, typically used in modern gas turbines, has a pronounced tendency to produce these instabilities.
Thus, the prediction of these thermoacoustic instabilities in the design phase of an engine becomes more and more important. A method based on linear acoustic four-pole elements to predict the instabilities of the ring combustor of the Siemens 3A-series gas turbines will be presented in this paper. The complex network includes the entire system starting from both compressor outlet and fuel supply system and ending at the turbine inlet.
Most of the transfer elements can be described by analytical data. Nevertheless, the most important elements, “flame” and “combustion chamber”, have to be investigated more in detail due to their complex 3D acoustics.
For the turbulent, premixed and swirled flame, a numerical simulation of the transient behavior after a sudden jump in mass flow at the inlet (step-function approach) is used to obtain the flame frequency response for axial direction as well as circumferential direction. This method has been verified for numerous different flame types (Krüger et al. (1998), Bohn et al. (1997), Bohn et al. (1996)). The four-pole element of the annular combustor is derived by an eigenfrequency analysis of the chamber, including a numerical predicted temperature and flow distribution.
The results show the principle possibilities of the instability analysis described. The frequencies predicted correspond well with experience from engine test fields. The importance of several elements for self-induced combustion driven oscillations is pointed out clearly.
Modelling Combustion Instabilities Using Computational Fluid Dynamics
Authors: Brookes Steve J. , Cant R. Stewart , Dowling Ann P. 
Published: December 2014

The drive for lower emissions has forced combustor designers to consider lean premixed combustion systems. Unfortunately, premixed combustion systems are particularly susceptible to instabilities, raising large periodic fluctuations in heat release and pressure, that may cause structural damage. A reliable computational tool for predicting the onset of these oscillations would be extremely useful during the design process.
The work contained in this paper utilises computational fluid dynamics to model a simple premixed combustor, consisting of a bluff-body stabilised flame burning within a cylindrical duct. State of the art models are used to represent the combustion heat release and the turbulent transport within the combustor. Both forced oscillations and a nearly self-excited condition are modelled and compared with experiment.
Experimental Study of Showerhead Cooling on a Cylinder Comparing Several Configurations Using Cylindrical and Shaped Holes
Authors: Reiss H. , Bölcs A. 
Published: December 2014

Film cooling and heat transfer measurements on a cylinder model have been conducted using the transient thermochromic liquid crystal technique. Three showerhead cooling configurations adapted to leading edge film cooling of gas turbine blades were directly compared: ‘classical’ cylindrical holes versus two types of shaped hole exits. The experiments were carried out in a free jet test facility at two different flow conditions, Mach numbers M = 0.14 and M = 0.26, yielding Reynolds numbers based on the cylinder diameter of 8.6e4 and 1.55e5, respectively. All experiments were done at a main stream turbulence level of Tu = 7% with an integral lengthscale of Lx = 9.1mm (M = 0.14), or Lx = 10.5mm (M = 0.26) respectively. Foreign gas injection (CO2) was used yielding an engine-near density ratio of 1.6, with blowing ratios ranging from 0.6 to 1.5.
Detailed experimental results are shown, including surface distribution of film cooling effectiveness and local heat transfer coefficients. Additionally, heat transfer and heat load augmentation due to injection with respect to the uncooled cylinder are reported.
For a given cooling gas consumption the laid-back shaped hole exits lead to a clear enhancement of the cooling performance compared to cylindrical exits, whereas laterally expanded holes give only slight performance enhancement.
An Investigation on the Onset of Wake-Induced Transition and Turbulent Spot Production Rate Using Thermochromic Liquid Crystals
Authors: Kittichaikarn C. , Ireland P. T. , Zhong S. , Hodson H. P. 
Published: December 2014

Wakes shed by upstream blade rows are known to cause boundary layer transition in both the compressor and turbine stages of axial flow gas turbines. This transition process is believed to take place via discrete zones of turbulence known as turbulent spots which occur in an otherwise laminar boundary layer. However, the process of transition over the blade surface cannot, at present, be reliably predicted. This is due to a lack of information on where and when these turbulent spots form and how they grow and merge as they convect downstream to form the turbulent boundary layer.
This paper presents detailed experimental information on the process of boundary layer transition induced by a bar generated wake travelling over a zero pressure gradient laminar boundary layer on a flat plate. The Reynolds number was 3×105. The peak turbulence intensity within the wakes varied from 3 to 6 % by using different bar of different diameters. An encapsulated cholesteric liquid crystals coating has been employed on a heated flat plate to reveal detailed information over the full surface. The information includes the thermal characteristics, the spot onset and formation rate. Data were obtained at high resolution on a grid of 30,000 points. The results were compared to intermittency plots and time-distance diagrams obtained by using surface-mounted thin film gauges and found to be similar. The data were also consistent with well established correlations and other published data from the literature for existing wake-induced transition models.
Development of Hip Diffusion Bonding Processes for ODS Alloy Turbine Vanes
Authors: Matsuda Yoshihiro , Takikita Toshihiro , Noumi Shin-ichiro , Akikawa Naofumi , Yoshida Toyoaki , Taki Masanobu 
Published: December 2014

Turbine inlet temperature of gas turbine engines have been increased in order to improve engine efficiency but is closing in on the upper limit of capacity for current casting materials and thermal barrier coating systems. To cope with such situations, it is necessary to develop new material applications which have superior heat resistant properties than current casting superalloys, ODS alloys are one of the candidate materials.
In this study, optimum HIP (Hot Isostatic Pressing) diffusion bonding parameters and a manufacturing process for turbine vanes of Ni base ODS (Oxide Dispersion Strengthened) alloy, MA754, were developed for the purpose of introducing advanced internal cooling structures. By using these parameters and process, HIP diffusion bonded MA754 turbine vanes were manufactured experimentally. As another application of the bonding process, MA754 turbine vanes HIP diffusion bonded with pure Cu internal cooling structure which has high thermal conductivity were also manufactured.
An Infrared Technique for Evaluating Turbine Airfoil Cooling Designs
Authors: Sweeney Patrick C. , Rhodes Jeffrey F. 
Published: December 2014

An experimental approach is used to evaluate turbine airfoil cooling designs for advanced gas turbine engine applications by incorporating double-wall film-cooled design features into large scale flat plate specimens. An infrared (IR) imaging system is used to make detailed, two-dimensional steady state measurements of flat plate surface temperature with spatial resolution on the order of 0.4 mm. The technique employs a cooled zinc selenide window transparent to infrared radiation and calibrates the IR temperature readings to reference thermocouples embedded in each specimen, yielding a surface temperature measurement accuracy of ±4 °C. With minimal thermocouple installation required, the flat plate/IR approach is cost effective, essentially non-intrusive, and produces abundant results quickly. Design concepts can proceed from art to part to data in a manner consistent with aggressive development schedules.
The infrared technique is demonstrated here by considering the effect of film hole injection angle for a staggered array of film cooling holes integrated with a highly effective internal cooling pattern. Heated freestream air and room temperature cooling air are used to produce a nominal temperature ratio of 2 over a range of blowing ratios from 0.7 to 1.5. Results were obtained at hole angles of 90° and 30° for two different hole spacings and are presented in terms of overall cooling effectiveness.
Modelling of a Microslip Friction Damper Subjected to Translation and Rotation
Authors: Csaba Gabor 
Published: December 2014

This paper presents a friction interface model where one of the mating surfaces is curved. The model is based on a discretization of the Winkler elastic foundation model and is general in the sense that it allows for relative motion in all six degrees of freedom. The variables for the contact model are based on damper geometry and material data, except coefficient of friction and tangential stiffness coefficient, which have to be measured. Simulated and experimental hysteresis curves are presented.
A model of a curved wedge damper has been developed using the contact model. An algorithm for solving forces and displacement when the damper is allowed to move in all six degrees of freedom has been presented. The governing algebraic equations are solved using a nonlinear least-square method routine in a commercial software package.
Forced response of a beam-damper-beam test set-up has been simulated and compared with experiments. The results highlighted some effects which have not been modelled e.g. the actual contact area between damper and blade is influenced by surface roughness for low normal loads. It is assumed that this effect resulted in problems in getting agreement between experiments and analysis. The influence of surface roughness is assumed to be negligible when vibrations of real turbomachinery are considered. This is due to the fact that both normal and excitation force on the clamper are about ten times higher than what was used in the experiments and simulations in this paper.
Variation of contact radius of the damper shows that a larger radius e.g. a flatter contact gives better damping and increases the resonance frequency. The disadvantage is that the alignment of the damper becomes more unreliable.
Comparison of Different Acceleration Techniques and Methods for Periodic Boundary Treatment in Unsteady Turbine Stage Flow Simulations
Authors: von Hoyningen-Huene Martin , Jung Alexander R. 
Published: December 2014

This paper studies different acceleration techniques for unsteady flow calculations. The results are compared with a non-accelerated, fully-explicit solution in terms of time-averaged pressure distributions, the unsteady pressure and entropy in the frequency domain and the skin friction factor. The numerical method solves the unsteady three-dimensional Navier-Stokes equations via an explicit time-stepping procedure. The flow in the first stage of a modern industrial gas turbine is chosen as a test case. After a description of the numerical method used for the simulation, the test case is introduced. The comparison of the different numerical algorithms for explicit schemes is intended to ease the decision about which acceleration technique to use for calculations as far as accuracy and computational time are concerned. The convergence acceleration methods under consideration are, respectively, explicit time-stepping with implicit residual averaging, explicit time-consistent multigrid and implicit dual time stepping. The investigation and comparison of the different acceleration techniques are applicable to all explicit unsteady flow solvers.
As another point of interest, the influence of the stage blade count ratio on the flow field is investigated. For this purpose, a simulation with a stage pitch ratio of unity is compared with a calculation using the real ratio of 78:80, which requires a more sophisticated method for periodic boundary condition treatment. This paper should help to decide whether it is vital from the turbine designer’s point of view to model the real pitch ratio in unsteady flow simulations in turbine stages.
Co-Gasification of Coal/Biomass Blends in a Pressurized Fluidized-Bed Gasifier: The Advantageous Synergies in the Process
Authors: Chen Guanxing , Yu Qizhuang , Brage Claes , Rosén Christer , Sjöström Krister 
Published: December 2014

An experimental study on co-gasification of coal and biomass blends in an oxygen-containing atmosphere has been carried out in a pressurized fluidized-bed gasifier. Several different biomass materials including wood and energy crops were used in the study, whereas two coals ranked of bituminite from Poland and UK were used in the investigation. The gasifier used was a Laboratory Development Unit (LDU) with an inner diameter of 144 mm. The operation temperature was 900 °C, and the pressure was 0.4 MPa. The research was part of the European Commission’s APAS and JOULE III clean coal technology programs.
The study was focused on possible synergistic effects in the thermochemical treatment of the fuel blends. The char formed was examined. The tar produced in the process was analyzed. The environmentally concerned nitrogen compounds emitted from the process were detected. An unexpected result was that the blends of the fuels and their char formed in situ exhibited higher gasification reaction rate under the studied conditions. The yield of char diminished and consequently the gas production increased. Furthermore, both the formation of tar and nitrogen compounds seemed also affected synergistically in co-gasification process of the fuel blends. The yields of tar and ammonia were lower than expected.
Conditioning and Detailed Analysis of Biomass Derived Fuel Gas Ongoing and Planned Work by Battelle
Authors: Anson Don , Paisley Mark A. , Ratcliff M. A. 
Published: December 2014

Gas turbine based power and cogeneration schemes are likely to become more favored as turbine efficiencies improve, but the economics of local power generation may depend on the use of low cost fuels other than natural gas. Opportunities may arise in the application of gas turbines in the pulp and paper industry and the wider use of biomass derived fuels in general.
These fuels, as produced, typically contain inorganic impurities originating from ash forming substances and other minor constituents of the feedstock. Also, depending on the biomass treatment process, they contain varying amounts of complex organic derivatives, commonly referred to as tars, and some simpler condensable vapors.
The Department of Energy is sponsoring work aimed at providing realistic data on low level constituents and impurities in gas derived by indirect gasification of wood, some of which may have disproportionately severe effects on turbine operation, durability, and emissions performance. It is planned to sample gas from both laboratory scale (up to 20 tons/day) and pilot scale (200 tons/day) installations and to assess the effectiveness of wet scrubbing procedures and catalytic reforming of condensables in cleaning up the gases. This paper discusses the rationale for this work, experimental approach, and analytic procedures that will be used. The work will include the operation of a small (220-kWe) gas turbine to provide direct information on the impact of using the final biomass derived gas delivered by the system.
The laboratory scale work is currently under way, with a planned completion date in mid 2000. The second phase is dependent on arrangements for integration of the R&D effort with the operation of the pilot plant.
Development of a Composite Inlet Housing for GTX100
Authors: Andersson Roger S. , Eriksson Ingemar A. G. , Granström Olov C. 
Published: December 2014

The development of the new industrial gas turbine GTX100 offered possibilities to introduce new applications for materials and design.
The characteristics of the inlet housing are not just important from a power output viewpoint but also from a flow field distortion and compressor blade excitation point of view. This paper describes the evolutionary process and considerations in the development of the GTX100 composite inlet housing. The goal, which has been accomplished, was to find a new design that would result in lower manufacturing costs and improved performance.
Rotor Dynamic Response at Blade Loss
Authors: Karlsson B. Agne , Bergström C. Pontus , Domeij J. Thomas F. 
Published: December 2014

This paper shows the influence of the method of modelling the support structure, i.e. the casings, support struts and skid, on the rotor dynamics and forced response in a gas turbine structure. Numerical examples, based on the conceptual design of GTX100 in the simple cycle configuration, are given for the blade loss case.
The standard method of analysing the rotor dynamics of a stationary gas- or steam-turbine rotor train, with hydrodynamic bearings, is based on beam theory. The bearings are modelled as a system of linear springs and dampers and are in some cases modelled as if there is no cross-coupling between the bearings. The support structure is normally based on a simple FE-analysis. This method is normally sufficient for the analysis of rotor dynamics characteristics at normal running if the stiffness of the bearings are much lower than the stiffness of the support structure.
In analysing the case of blade loss, the dynamic characteristics of the casing and the support structure have a much stronger influence on the rotor dynamics and the forced response in the structure. At the high unbalance forces present at a blade loss, the stiffness of the bearings will be of the same magnitude as that of the structure.
Results are given and discussed for the analysis of the rotor dynamic response based on coupled 3D-FE models, and on beam theory with the dynamic characteristics of the support structure described by various FE models.