bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical Investigation of Tandem-Impeller Designs for a Gas Turbine Compressor
Authors: Roberts Douglas A. , Kacker Suresh C. 
Published: July 2014

The tandem-bladed impeller centrifugal compressor, which may offer potential aerodynamic benefits over conventional designs, is rarely employed in production gas-turbine applications. Conventional impeller designs are often favored because of concerns for both significant performance losses and increased manufacturing costs associated with tandem configurations. In addition, much of the available literature concerning the characteristics of tandem-impellers is inconclusive, and at times contradictory. Because of the scarcity of tandem-impellers, rules for their design are nearly non-existent. Also, the effects of inducer/exducer clocking upon tandem-impeller performance and exit flow characteristics are not fully understood. In the present study, a numerical investigation was performed to investigate the aerodynamic characteristics of a tandem-impeller design for the rear-stage of a gas-turbine compressor (target impeller PRt-t≈3.0). A parametric study of tandem-impeller inducer/exducer clocking was performed in order to explore its effect upon performance and exit flow quality. Because the tandem impeller was designed to be retrofittable for an existing conventional impeller, it was also compared to predictions for the baseline conventional design.
Results of the study indicated that the tandem-impeller was less efficient than the conventional design for all clocking configurations studied. Tandem-impeller blade clocking was found to have a significant effect upon predicted pressure-ratio, temperature-ratio, efficiency, and slip-factor; the maximum values for these parameters were predicted for the in-line tandem configuration. The minimum predicted tandem-impeller isentropic efficiency occurred at a clocking fraction of 50%, falling 3.8 points below that of the in-line case. Although the tandem-impeller performance was predicted to diminish as blade clocking was increased, significant improvements in the uniformity of impeller exit velocity profiles were observed. Profiles of both total pressure and swirl at impeller exit indicated that the tandem-impeller design may offer both improved diffuser recovery and stalling margin over the conventional design.
Experimental and Numerical Investigation of the Flow in a 5-Stage Transonic Compressor Rig
Authors: Lecheler Stefan , Schnell Rainer , Stubert Bertram 
Published: July 2014

The flow in a 5-stage transonic compressor rig was experimentally and numerically investigated. The rig is geometrically scaled from the front part of an existing heavy duty gas turbine compressor with CDA-blading.
At several operating points pressures and temperatures were measured in order to get the performance map of the compressor, radial distributions at vane leading edges and static pressures at vanes and casing.
In order to identify shock locations and to get information about the rotor-stator interactions and the flow angles, 3D L2F-measurements were done in the first and second rotor at two speeds. A newly developed double periodic measuring L2F-system was employed in order to analyze the results with respect to up- and downstream effects of both rotors.
The experimental data were used for the validation and calibration of two steady 3D multistage Navier-Stokes codes with mixing plane models between the blade rows.
With STAGE3D, calculations were mainly done for the first 2 transonic stages in order to compare shock locations, velocities, inlet and outlet flow angles with measurements. Furthermore the code was calibrated, which means, that grid sizes and numerical parameters were adjusted to give the best fit to the experiments while having acceptable calculation times. A set of parameters was found, which will be used for the design of new transonic multistage compressors. However not all flow quantities fit well to the measurements. Mass flow and pressures could not be fulfilled at the same time.
The other code used was TRACE-S. A procedure for a fast calculation of the whole performance map for all 9 blade rows together was developed and tested. The shape of the calculated speed lines fit well to the measured ones, but the mass flow is predicted too high at off-design conditions. The reason is a too low calculated loss production which is confirmed by the higher calculated radial total pressure distributions.
Thermodynamic, Economic and Environmental Benefits of the Integration Between Oil Refineries and IGCCs
Authors: Consonni Stefano , Pelliccia Giampaolo 
Published: July 2014

IGCC technology enables environmentally-friendly generation of electricity from high sulphur content refinery residuals and, at the same time, higher production of light and middle distillates over a wide range of crude quality. The latter represents a particularly valuable feature because environmental regulations are driving toward larger market shares of lighter and cleaner distillates and, at the same time, crude quality is declining.
This paper illustrates how the integration between a refinery process and an IGCC can reduce primary energy consumption and emissions, as well as improve the economic prospects of the refinery. The analysis moves from the specific case of the ISAB-Energy plant recently completed in Priolo (Italy) and then assesses the thermodynamic, economic and environmental benefits achievable by the upgrade of the whole Italian refinery system under three sets of assumptions: IGCC with the same features and cost of the ISAB plant; advanced IGCC (LHV efficiency 46%) with a specific cost of 1400 $/kW; advanced IGCC with a specific cost of 1200 $/kW.
If all Italian refineries were integrated with advanced IGCCs (with natural gas fired Combined Cycles covering the deficit of electricity production), national primary energy consumption would decrease by more than five millions tons of oil equivalent per year, CO2 emissions would decrease by almost 15 million t/y and there would be substantial reductions of SOx, NOx and particulate emissions. If the overall cost of this restructuring were totally charged to the reduction of CO2 emissions, each ton of avoided CO2 emissions would costs between 4,5 to 29,3 $.
Production of Simulated Gasified Biomass for Pilot Plant Applications
Authors: Duwig Christophe , Fredriksson Jan , Fransson Torsten 
Published: July 2014

The design of modern Low Heating Value (LHV) fuel combustion devices, such as gas turbine combustors, relies heavily on numerical simulations. In addition, numerical predictions are always validated by experimental tests. In this work, an experimental facility was built. The fuel input power of the combustor was 300 kW. Such facility requires a gas flow of typically 0.06 kg/s, so a syngas production at a reasonable cost was required to undertake tests under real working conditions.
Within this work, an inexpensive and flexible syngas generator has been designed, produced and tested. The main idea was to use cheap available gas fuels and to crack it in order to obtain the syngas. Such conversion is heavily used in oil refineries and called “Steam Reforming”. Propane is used as a fuel and is cracked on a commercial steam reforming catalyst. To ensure the wanted ratio of C/H and C/O in the final product, CO2, H2O and air were added to the fuel gas. Catalytic cracking is needed as propane cracking kinetics are low at wanted operation temperatures, namely 900 to 1100 K. Care is taken to avoid carbon formation in the gasification device which may cause decomposition of the stainless steel reactor vessel.
The gasification device was used to feed a 300kW combustor at 2.8 bar pressure. The device was successfully integrated into a test rig and used for a burner study. The obtained composition was quite close to a typical gasified biomass composition. A wide range of different compositions has also been explored. Hydrocarbon concentration range was investigated from 3 vol% up to 16 vol% (Methane equivalent). The CO2 concentration varied between 13 vol% and 20 vol%. The syngas temperature was kept at an interval between 900 and 1100 K. The device provided 0.06 kg/s of a 3 to 5 MJ/kg heating value fuel. The operating costs of the gasification device were found about one tenth of the bottled gas price.
Pressurized Pilot-Scale Test Facility for Catalytic Combustion of Simulated Gasified Biomass: First Test Results
Authors: Jacoby J. , Strasser T. , Fransson T. , Thevenin P. , Järås S. 
Published: July 2014

Gasified biomass has become an attractive fuel source for the production of electricity for various processes due to its potential to reduce the net CO2 emission. The overall aim is to combine biomass as a fuel source with high temperature catalytic combustion in order to lower emissions of nitrogen oxides, carbon monoxide and hydrocarbons.
This paper presents the design of a pressurized test facility for testing various catalytic materials under varying operating conditions and arrangements in the combustor. Instrumentation of the rig is described. Catalyst development and preparations are being described as well as the first results from the pilot-scale test facility. Different catalyst configurations and compositions have been tested.
It was shown that a Pd / LaAl11O18 catalyst is able to ignite the synthetic gasified biomass and that high conversion rates of H2 can be achieved with this type of catalyst. By applying a layer of barium stabilized alumina, thermal protection of the catalyst is achieved, hence limiting the maximum catalyst temperature.
Internal Reforming Solid Oxide Fuel Cell Gas Turbine Combined Cycles (IRSOFC-GT): Part B — Exergy and Thermoeconomic Analyses
Authors: Massardo Aristide F. , Magistri Loredana 
Published: July 2014

The aim of this work is to investigate the performance of Internal Reforming Solid Oxide Fuel Cell (IRSOFC) and Gas Turbine (GT) combined cycles.
A mathematical model of the IRSOFC steady-state operation was presented in Part A of this work (Massardo and Lubelli, 1998), coupled to the thermodynamic analysis of a number of proposed IRSOFC-GT combined cycles, taking into account the influence of several technological constraints.
In the second part of this work, both an exergy and a thermoeconomic analysis of the proposed cycles have been carried out using the TEMP code developed by the Author (Agazzani and Massardo, 1997). A suitable equation for IRSOFC cost evaluation based on cell geometry and performance has been proposed and employed to evaluate the electricity generation cost of the proposed combined systems.
The results are presented and the influence of several parameters is discussed: external reformer operating conditions, fuel to air ratio, cell current density, compressor pressure ratio, etc. Diagrams proposed by the Author (Massardo and Scialo’, 2000) for cost vs. efficiency, cost vs. specific work, and cost vs. system pressure are also presented and discussed.
Comparative Analysis of Hybrid Cycles Based on Molten Carbonate and Solid Oxide Fuel Cells
Authors: Campanari Stefano , Macchi Ennio 
Published: July 2014

High temperature fuel cells are experiencing an increasing amount of attention thanks to the successful operation of prototype plants, including a multi-MW Molten Carbonate Fuel Cell (MCFC) demonstration plant and a hybrid Solid Oxide Fuel Cell (SOFC) gas turbine power plant. Both MCFCs and SOFCs are currently considered attractive for the integration with gas turbines in more complex “hybrid” plants, with projected performances that largely exceed combined cycles efficiencies even at a small-scale size and with an extremely low environmental impact.
This paper compares the performances of MCFC and SOFC hybrid cycles. The comparison shows some advantages for the SOFC hybrid cycle in terms of plant simplicity and moderately higher efficiency.
Modelling the Air-Cooled Gas Turbine: Part 1 — General Thermodynamics
Authors: Young J. B. , Wilcock R. C. 
Published: July 2014

This paper is Part I of a study concerned with developing a formal framework for modelling air-cooled gas turbine cycles and deals with basic thermodynamic issues. Such cycles involve gas mixtures with varying composition which must be modelled realistically. A possible approach is to define just two components, air and gas, the latter being the products of stoichiometric combustion of the fuel with air. If these components can be represented as ideal gases, the entropy increase due to compositional mixing, although a true exergy loss, can be ignored for the purpose of performance prediction. This provides considerable simplification.
Consideration of three idealised simple cycles shows that the introduction of cooling with an associated thermal mixing loss does not necessarily result in a loss of cycle efficiency. This is no longer true when real gas properties and turbomachinery losses are included. The analysis clarifies the role of the cooling losses and shows the importance of assessing performance in the context of the complete cycle. There is a strong case for representing the cooling losses in terms of irreversible entropy production as this provides a formalised framework, clarifies the modelling difficulties and aids physical interpretation. Results are presented which show the effects on performance of varying cooling flowrates and cooling losses. A comparison between simple and reheat cycles highlights the rôle of the thermal mixing loss. Detailed modelling of the heat transfer and cooling losses is discussed in Part II of this paper.
Gas Turbine Performance of Mature, F- and Advanced Technologies 2000
Authors: von Rappard Axel W. , Della Villa Salvatore 
Published: July 2014

The contribution of the gas turbine in simple and combined cycle systems to power production in the United States has been steadily rising over the past 25 years. In 1998 their contribution to power production was approximately 15% and it increased over the past 5 years by 1.5 to 2%, annually. In parallel, the United States Department of Energy (DOE) has financially supported Advanced Technology development with good formulated goals for overall performance of plants including reliability, availability and maintainability (RAM). In this paper the authors evaluate RAM performance data from power plants over the past five years. This evaluation can be used as baseline or benchmark for further improvements. It takes into account the mode of operation being base load, cycling or peaking application and analyses the power plant on a year-by-year evaluation. All RAM-data came from the same source and are collected and analyzed according to standardized procedures.
Availability will be reviewed for machines of different sizes and technologies. Maintainability will be analyzed as function of the size of units, energy production, and the mode of operation.
Gas turbine simple and combined cycle power plants have been operated in peaking, cycling, base and continuous load operation. The flexibility is shown in different “Service Hours per Successful Start” and a correlation with the RAM parameters. To analyze and explain these differences will be the main result of this evaluation. The contribution shall help to evaluate the best solution for individual sites because efficiency and availability cannot always be increased in parallel.
Testing the Latest Model V84.3A Gas Turbine in the Siemens Test Facility in Berlin
Authors: Frank Stefan L. F. , Lechner Christof , Mertens Bernward , Warnack Dieter 
Published: July 2014

Since the end of 1998, the new V84.3A has been under investigation in the Siemens Gas Turbine Development and Manufacturing Center in Berlin. Especially for the testing of gas turbine prototypes, Siemens runs a test bed which allows full load tests with speed variations. Hence the engine can be tested at the extremes of real gas turbine operation conditions.
Within the range of the investigations there have been combustion optimization and performance tests at full and part load. A focus was the testing of various kinds of water injection. Additionally blade vibration measurements in the turbine and the compressor, surface temperature measurements using thermal paint and pyrometry, and aerodynamics measurements using five-hole probes have been performed.
Fundamental Design Issues of Brush Seals for Industrial Applications
Authors: Dinc Saim , Demiroglu Mehmet , Turnquist Norman , Mortzheim Jason , Goetze Gayle , Maupin John , Hopkins James , Wolfe Christopher , Florin Mark 
Published: July 2014

Advanced seals have been applied to numerous turbine machines over the last decade to improve the performance and output. Industrial experiences have shown that significant benefits can be attained if the seals are designed and applied properly. On the other hand, penalties can be expected if brush seals are not designed correctly.
In recent years, attempts have been made to apply brush seals to more challenging locations with high speed (>400 m/s), high temperature (>650 °C), and discontinuous contact surfaces, such as blade tips in a turbine. Various failure modes of a brush seal can be activated under these conditions. It becomes crucial to understand the physical behavior of a brush seal under the operating conditions, and to be capable of quantifying seal life and performance as functions of both operating parameters and seal design parameters. Design criteria are required for different failure modes such as stress, fatigue, creep, wear, oxidation etc. This paper illustrates some of the most important brush seal design criteria and the trade-off of different design approaches.
Estimation of Thermophysical Properties and Microstructure of Aged Thermal Barrier Coatings
Authors: Fujii Tomoharu , Takahashi Takeshi 
Published: July 2014

A thermal barrier coating (TBC) is used for protecting hot gas path parts, and is useful for allowing the turbine inlet gas temperature to be increased. In order to quantitatively evaluate the performance of TBCs, the thermal conductivity of TBCs on the combustor of a gas turbine were measured. The results indicate that the thermal conductivity of age-deteriorated TBCs were higher than that of the as-sprayed TBC. This finding suggested that the thermal barrier performance of the TBC had deteriorated. When the thermal barrier performance of a TBC deteriorates, the temperature of the metal substrate rises, shortening the service life of hot gas path components. Accordingly, using experimental TBCs, laboratory-scale studies were performed to identify the causes of the deterioration of thermal barrier performance in TBCs. Six types of TBCs, prepared from six grades of plasma spray powder of yttria stabilized zirconia (YSZ), were tested. Average powder size, powder configuration, and percentage of yttria were the parameters of plasma spray powder taken to measure the thermophysical properties and carry out microstructural analyses on the as-sprayed TBCs and heat-treated TBCs.
The results of the thermophysical property measurements indicate that the thermal barrier performance of heat-treated TBCs were two to three times greater than that of the as-sprayed TBCs. The results of the microstructural analyses revealed that the deterioration in performance was caused by changes occurring in the crystalline structure and the reduction of the non-contact area as in TBCs. The changes in thermal conductivity of TBCs were expressed as coefficients of porosity, crystalline structure, and heating time and temperature.
Designing Hot Working Processes of Nickel Base Superalloys Using FEM Simulation
Authors: Kopp R. , Tschirnich M. , Wolske M. , Klöwer J. 
Published: July 2014

Knowledge of correct flow stress curves of Ni-based alloys at high temperatures is of essential importance for reliable plasto-mechanical simulations in materials processing and for an effective planning and designing of industrial hot forming schedules like hot rolling or forging. The experiments are performed on a computer controlled servo-hydraulic testing machine at IBF (Institute of Metal Forming). To avoid an inhomogeneous deformation due to the influence of friction and initial microstructure, a suitable specimen geometry and lubricant is used and a thermal treatment before testing has to provide a microstructure, similar to the structure of the material in the real process.
The compression tests are performed within a furnace, which keeps sample, tools and surrounding atmosphere at the defined forming temperature. The uniaxial compressions were carried out in the range of strain rates between 0.001 and 50 s−1 and temperatures between 950 and 1280°C. Furthermore two-stage step tests are carried out to derive the work hardening and softening behaviour as well as the recrystallisation kinetics of the selected Ni-based alloys.
At the end of this work a material model is adapted by the previously determined material data. This model is integrated into the Finite Element program LARSTRAN/SHAPE to calculate a forging process of the material Alloy 617.
Cavity and Protrusion Effects in a Single-Stage Compressor
Authors: Demargne A. A. J. , Longley J. P. 
Published: July 2014

The effect of opening a stator-shroud cavity to the mainstream (no net leakage), upstream of a moderately loaded stator is investigated in a single-stage research compressor.
The investigations consist of a series of measurements and calculations, which reveal various inconsistencies in flow turning, secondary flow and blockage. CFD analysis is used as a diagnostic tool to show that the unexpected trends measured in the single-stage compressor can be attributed to the protrusion of the arrangement used to seal the cavity into the mainstream, disrupting the hub endwall flow into the stator passage.
The CFD results on the single-stage compressor without protrusion confirm the trends observed in the linear cascade experiment relative to the effects of the upstream shroud cavity on the hub endwall flow and stator performance, in the presence of the stator blade pressure field. These results clearly illustrate the strong sensitivity of the performance of the stator row to small protrusions and cavities in the endwalls. Such effects are no longer negligible when compared to the level of resolution and sophistication achieved with current solvers.
Numerical Simulation of 3D Flow Field Structure in Turbine Cascade With Bowed Blades
Authors: Wang Songtao , Wang Zhongqi , Feng Guotai 
Published: July 2014

The differences of flow field in bowed blade cascade and that in straight blade cascade are systematically studied in this paper. To bow a blade means to change its geometric boundary condition. This change not only affect the pressure distribution along the blade profile exit Mach number but also has great effect on the original position and development of the passage vertex. All of the changes mentioned above have great influence on the loss.
Numerical simulation result showed that blade bowing can decrease the cross-pressure gradient near the end wall. This trend will be more obvious with the increase of the bow angle. The pressure gradient decrease is beneficial to weaken the passage vortex strength and reduces the secondary loss near the endwalls. In addition, Pressure gradient from endwalls to midspan can be established near suction surface in positively bowed blade. With the increase of bow angle, this C-type pressure distribution is remarkable. It is also found that this C-type pressure distribution will influence the position of corner vortex near the suction surface and will also influence the position and size of the passage vortex. Blade bowing also has great influence on the position of the saddle point near the leading edge and the separated line of the horseshoe vortex. It is found that the position of the saddle point and the separated line of both legs of the horseshoe vortex move forward in a positively bowed blade.
The passage vortex structure in bowed cascade is also presented. It can be concluded that a bowed blade can make the passage vortex stable and helps change its structure from loose to compact. Blade bowing is also beneficial to limit the influence domain of the unstable passage vortex core by the stable limit cycle.