bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparison of a State of the Art and a High Stage Loading Rotor
Authors: Selic Thorsten , Lengani Davide , Schönleitner Florian , Marn Andreas , Broszat Dominik 
Published: September 2014

This paper presents measurement results of a 1½ stage LPT test rig at Graz University of Technology incorporating two different rotor geometries: one with a regular blade loading and a second rotor with a highly loaded blade geometry. The test rig was designed in cooperation with MTU Aero Engines and represents the last 1.5 stages of a commercial aero engine. Considerable efforts were put on the adjustment of all relevant model parameters (Mach number, blade count ratio, airfoil aspect ratio, blade loading, etc.) to reproduce the full scale LPT situation. The rig diameter is approximately half of that of a commercial aero engine LPT. The number of blades and vanes for the two investigated stages as well as the pressure ratio and power output are identical, resulting in a decrease in rotational speed of the HSL rotor. Measurement data from a fast response pressure probe (FRAPP) is used to compare the flow fields of the two different stages.
The effect of the different stage designs can be seen when comparing the exit flow fields. The highly loaded stage shows a more pronounced tip leakage vortex compared to the datum stage. The highly loaded stage shows wider wakes with a lower total pressure deficit. The fluctuations of total pressure within the flow field are directly related to the upstream wake. If the measurement position is located within a stator wake, the fluctuations are significantly smaller than out of the wake.
Thermodynamic Analysis of Innovative Micro Gas Turbine Cycles
Authors: Nikpey Homam , Mansouri Majoumerd Mohammad , Assadi Mohsen , Breuhaus Peter 
Published: September 2014

The growing global energy demand has been faced with increasing concerns about climate change over recent decades. In order to cover the additional demand and to mitigate CO2 emissions, one option is to utilize renewable energies such as solar and wind power. These energy sources are, however, intermittent by nature. Therefore, it is inevitable that a quick balancing and back-up power should be available to maintain grid stability at a certain level.
Gas turbine (GT) technology could certainly be one alternative for back-up/balancing power and could be utilized to complement renewable energy in the energy market. However, the GT industry needs to consider innovative cycle configurations to attain higher system performance and lower emissions and to cope with renewable powers. In this regard, the humid air turbine (HAT) cycle and the exhaust gas recirculation (EGR) cycle are amongst the promising GT cycles.
In the current study a micro gas turbine (MGT), a Turbec T100, has been selected as the base case for further investigation. A thermodynamic model for the base case has been developed in IPSEpro software and validated using experimental data obtained from an existing test facility in Stavanger, Norway.
Based on this validated model, system performance calculations for other alternative cycles, i.e. EGR and HAT cycles, have been carried out. Results confirm that the performance improvement potential is significant for the HAT cycle with only minor modifications to the baseline MGT cycle. The EGR cycle, with a maximum attainable recirculation ratio of 50%, shows a slightly lower level of performance compared to the base case. However, its potential for future CO2 capture is greater compared to the base case and the HAT cycle. The overall cycle efficiencies for the base case, the HAT, and the EGR cycles at full load operation, i.e. 100kW power, are 31.1%, 32.8%, and 30.4%, respectively.
The Impact of Representative Aerodynamic Flow Fields on Liquid Fuel Atomisation in Modern Gas Turbine Fuel Injectors
Authors: Barker A. G. , Carrotte J. F. 
Published: September 2014

In modern gas turbine engines swirl is typically imparted to the airflow as it enters the region of heat release to stabilize the flame. This swirling airstream is often highly turbulent and contains non-uniformities such as swirl vane wakes. However, it is within this environment that fuel atomization takes place. This paper is concerned with the potential effect of these airstream characteristics on the atomization process. Such a flow field is difficult to capture within simplified geometries and so measurements have been made within, and downstream of, injector representative geometries. This is experimentally challenging and required the application of a variety of techniques. The geometry considered is thought typical of an air-blast style injector, as may be used within current or future applications, whereby liquid fuel is introduced onto a pre-filming surface over which an airstream passes.
Data is presented which characterizes the atomizing airstream presented to the pre-filming region. This includes significant flow field non-uniformities and turbulence characteristics that are mainly associated with the swirling flow along with the vanes used to impart this swirl. The subsequent development of these aerodynamic features over the pre-filming surface is also captured with, for example, swirl vane wakes being evident through the injector passage and into the downstream flow field. It is argued these characteristics will be common to many injector designs. Measurements with and without fuel indicate the effect of the liquid film, on the non-dimensional aerodynamic flow field upstream of the pre-filming region, is minimal. However, the amount of airflow passing through the pre-filming passage is affected. In addition to characterization of the airstream, its impact on the liquid fuel film and its development along the pre-filming surface is visualized. Furthermore, PDA measurements downstream of the fuel injector (i.e. the injector ‘far-field) are presented and the observed spray characteristics spatially correlated with the upstream aerodynamic atomizing flow field. Hence for the first time a series of experimental techniques have been used to capture and correlate both near and far field atomization characteristics within an engine representative aerodynamic flow field.
The Oxy-Fuel, Supercritical CO2 Allam Cycle: New Cycle Developments to Produce Even Lower-Cost Electricity From Fossil Fuels Without Atmospheric Emissions
Authors: Allam R. J. , Fetvedt J. E. , Forrest B. A. , Freed D. A. 
Published: September 2014

The Allam Cycle is a new, high-pressure, oxy-fuel, supercritical CO2 cycle that generates low-cost electricity from fossil fuels while producing near-zero air emissions; all CO2 generated by the system is produced as a high-pressure, pipeline-ready by-product for use in enhanced oil recovery, industrial processes, or sequestration.
The base cycle was developed by 8 Rivers Capital and is being commercialized by NET Power, LLC in partnership with Toshiba Corporation, Exelon Corporation, and CB&I. The four parties are currently developing a natural gas-fired power plant to demonstrate this system. Target net efficiencies for the natural gas and coal versions of this cycle, based on current process modeling, are 59% and 52% (LHV) respectively, both with full carbon capture and no other air emissions. Detailed designs indicate that NET Power plants, with full carbon capture, will produce lower-cost electricity than state-of-the-art fossil fuel plants without CCS.
8 Rivers Capital continues to develop on top of the Allam Cycle platform. Building upon the original single turbine design, 8 Rivers has developed a two-turbine design that combines the benefits of the original, high-pressure Allam Cycle with a low-pressure reheat cycle. This new design can enable Allam Cycle-based plants to greatly increase power output with only a moderate increases in capital cost, substantially lowering the overall plant $/kW cost. Such a configuration would enable Allam Cycle plants to produce even lower-cost electricity than the single turbine Allam Cycle design currently being commercialized by NET Power, CB&I, Toshiba and Exelon. This paper outlines the design considerations utilized for the base Allam Cycle development and then details this new cycle design and its potential benefits.
A Robust Mixing Plane Method and its Application in 3D Inverse Design of Transonic Turbine Stages
Authors: Ray Saurya Ranjan , Zangeneh Mehrdad 
Published: September 2014

A robust mixing plane method satisfying interface flux conservation, non-reflectivity and retaining interface flow variation; valid at all Mach numbers and applicable for any machine configuration is formulated and implemented in a vertex based finite volume solver for flow analysis and inverse design of turbomachinery stage configurations. The formulation is based on superposing perturbed flow variables in the form of 3D characteristics obtained along the flow direction on the exchanged mixed out average quantities at the stage interface. A condition is derived in the mixed-out averaging procedure to distinguish between the subsonic and supersonic flow conditions at the interface. Using preconditioning technique, the new functionality is demonstrated to be applicable for a wide range of interface conditions and over different machine configurations with small spatial gap across the blade rows. The method is shown to satisfy flux conservation across the interface without generating spurious oscillations in the flow field at the domain boundaries and validated against available commercial solvers.
Subsequently, a blade re-design approach in a multi-row configuration is conceptualised and demonstrated by the application of the 3D inverse design method on a single stage Low Pressure Turbine. Meridional load variation, stage reaction and blade stacking angle are considered as the design variables to explore the design space. Conducting design runs at a fixed mass flow boundary condition and similar overall loading condition; the optimised configuration is shown to satisfy redistributed meridional load, providing performance improvement while maintaining a similar level of flow rate and work extraction as the baseline configuration.
Successfully Validated Combustion System Upgrade for the SGT5/6-8000H Gas Turbines: Technical Features and Test Results
Authors: Janus Bertram , Bigalk Joachim , Helmers Lennard , Witzel Benjamin , Ghermay Yohannes , Huth Michael , Johnson Cliff , Landry Kyle , Sunshine Robert 
Published: September 2014

An upgrade of the lean premixed combustion system installed in the SGT5-8000H in Irsching/Germany was developed for the 50 Hz and 60 Hz versions of the SGTX-8000H gas turbines. It features lower CO and NOx emissions by improving combustion aerodynamics and reduction of the air consumption of the combustion system.
Furthermore an improved secondary air managing system increases the amount of air, which can be supplied in a controllable way to the turbine in part load operation and, thus, increases the combustor temperature. This is done in stepwise increasing the air mass flow to the turbine by feeding compressor exit air to different distinct turbine stages. All in all this system extends the turn down capability beyond the level achievable by the new combustion system alone.
The new combustion system and the secondary air managing system were installed in full scale and tested in the SGT6-8000H test facility of the Siemens Gas turbine plant in Berlin.
The results have subsequently successfully been validated in the first commercial application on a customer site.
This paper presents the technical features of the systems, the development program and the test results.
A Grey-Box Identification Approach for Thermoacoustic Network Models
Authors: Jaensch S. , Emmert T. , Silva C. F. , Polifke W. 
Published: September 2014

This work discusses from a system theoretic point of view the low order modeling and identification of the acoustic scattering behavior of a ducted flame.
In this context, one distinguishes between black-box and grey-box models. The former rely on time series data only and do not require any physical modeling of the system that is to be identified. The latter exploit prior knowledge of the system physics to some extent and in this sense are physically motivated.
For the case of a flame stabilized in a duct, a grey-box model is formulated that comprises an acoustic part as well as sub-models for the flame dynamics and the jump conditions for acoustic variables across the region of heat release. Each of the subsystems can be modeled with or without physical a priori knowledge, in combination they yield a model for the scattering behavior of the flame.
We demonstrate these concepts by analyzing a CFD model of a laminar conical premixed flame. The grey-box approach allows to optimize directly the scattering behavior of the identified model. Furthermore, we show that the method allows to estimate heat release rate fluctuations as well as the flame transfer function from acoustic measurements only.
Stabilizing a 46 MW Multi-Stage Utility Steam Turbine Using Integral Squeeze Film Bearing Support Dampers
Authors: Ertas Bugra , Cerny Vaclav , Kim Jongsoo , Polreich Vaclav 
Published: September 2014

A 46 MW 5,500 rpm multistage single casing utility steam turbine experienced strong subsynchronous rotordynamic vibration of the first rotor mode; preventing full load operation of the unit. The root cause of the vibration stemmed from steam whirl forces generated at secondary sealing locations in combination with flexible rotor-bearing system. Several attempts were made to eliminate the subsynchronous vibration by modifying bearing geometry and clearances, which came short of enabling full load operation.
The following paper presents experimental tests and analytical results focused on stabilizing a 46 MW 6,230kg utility steam turbine experiencing subsynchronous rotordynamic instability. The paper advances an integral squeeze film damper (ISFD) solution, which was implemented to resolve the subsynchronous vibration and allow full load and full speed operation of the machine. The present work addresses the bearing-damper analysis, rotordynamic analysis, and experimental validation through waterfall plots, and synchronous vibration data of the steam turbine rotor. Analytical and experimental results show that using ISFD improved the stability margin by a factor of 12 eliminating the subsynchronous instability and significantly reducing critical speed amplification factors. Additionally, by using ISFD the analysis showed significant reduction in interstage clearance closures during critical speed transitions in comparison to the hard mounted tilting pad bearing configuration.
Transfer of the DDG-51 Ship Service Gas Turbine Generator (SSGTG) Marine Electrical Power System Assembly and Installation to the Republic of Korea Navy KDX-III Destroyer Program
Authors: Shaw Jesse , Kim Sungon 
Published: September 2014

In 2004, Rolls-Royce Naval Marine, Inc. (RRNMI, Walpole, MA, USA, now Rolls-Royce Marine North America, RRMNA) reached an agreement with Samsung Techwin Co. Ltd. (Seoul and Changwon, Korea) for the transfer of the assembly and installation of a marine electrical power system. This agreement culminated in the installation and use of Rolls-Royce Ship Service Gas Turbine Generators (SSGTGs) in the Republic of Korea Navy (RoKN) KDX-III Destroyers. In order to deliver success for this program, both companies had to overcome numerous technical and non-technical challenges.
Among these challenges were:
- Development of a kitting structure supplemented with tailored assembly drawings and instructions that could duplicate an established production process
- Agreement on the amount of Korean labor and materials to be utilized, referred to as “in-country” content
- Development of appropriate and necessary training for the assembly and testing of AG9140RF SSGTGs
- Determination of a correlation factor which equalizes the variables between RRMNA’s engine test cell and Samsung Techwin’s engine test cell
- Application of DAPA Quality Assurance (QA) requirements upon a system designed in accordance with US Navy QA requirements
- Ensuring compliance with Export Control guidelines, Export License requirements, and Manufacturing License Agreements
- Obtaining US Government approval for sale and transfer of technology and hardware to the Republic of Korea (RoK)
A Soot Chemistry Model That Captures Fuel Effects
Authors: Puduppakkam Karthik V. , Modak Abhijit U. , Naik Chitralkumar V. , Camacho Joaquin , Wang Hai , Meeks Ellen 
Published: September 2014

A detailed chemistry model is necessary to simulate the effects of variations in fuel composition on soot emissions. In this work, we have developed a detailed chemistry model for the soot formation and oxidation chemistry, with a focus on the surface kinetics of the soot-particle. The model has been compared to a unique set of soot particle-size data measured in flames for several single-component fuels. Fuel components used in the experiments represent the chemical classes found in jet, gasoline, and diesel fuels, including n-heptane (representative of n-alkanes) and toluene (aromatic). Measurements were taken in burner-stabilized stagnation-flame (BSSF) experiments, which can be simulated well using the 1-dimensional BSSF flame model in CHEMKIN-PRO. Soot volume fraction and particle size distributions are modeled using the sectional method option for Particle Tracking, within CHEMKIN-PRO software. The well-characterized flow of the BSSF experiments allows the modeling to focus on the kinetics. Validated detailed reaction mechanisms for fuel combustion and PAH production, combined with the new soot surface-kinetics mechanism, were used in the simulations. Simulation results were compared to measurements for both particle size distributions and total soot volume fraction. Observed effects of fuel, temperature, pressure, equivalence ratio and residence time on the soot size distribution shape and soot quantity were reproduced by the model.
The chemistry in the soot surface model includes particle nucleation, growth through the HACA (hydrogen-abstraction/carbon-addition) and PAH-condensation (polycyclic aromatic hydrocarbons) pathways, as well as soot-oxidation pathways. In addition to soot chemistry, the physics of particle coagulation and aggregation were included in the model. The results demonstrate the ability of well-validated chemistry to predict both dramatic and subtle effects related to soot mass and soot particle size.
Experimental Investigation of the Diffuser Vane Clearance Effect in a Centrifugal Compressor Stage With Adjustable Diffuser Geometry: Part II — Detailed Flow Analysis
Authors: Ubben Stefan , Niehuis Reinhard 
Published: September 2014

The combination of variable speed control and adjustable diffuser vanes offers an attractive design option for centrifugal compressors applied in industrial applications where a wide operating range at high efficiency level and a favorable surge line is required. However, the knowledge about the impact on compressor performance of a diffuser vane clearance between vane and diffuser wall which is mandatory since the diffuser geometry adjustment has to take place during operation, is still not satisfying.
The results of characteristic line and probe measurements presented in Part I [18] of this two-part paper showed that an one-sided diffuser clearance not necessarily need to lead to a negative impact on compressor operating behavior but is able to contribute to an increase in flow range, stall margin, pressure ratio and efficiency, as long as the diffuser passage is broad enough with respect to the clearance height.
In order to reveal the relevant flow phenomena, in Part II the results of detailed measurements of the pressure distribution at diffuser exit and Particle Image Velocimetry (PIV) measurements inside the diffuser channel performed at three clearance configurations and three diffuser angles at a fixed radial gap are discussed. It was found, that for defined diffuser configurations the clearance flow amplifies the diffuser throat vortex capable to reduce the loading of the highly loaded vane pressure side and to support a more homogenous diffuser flow. It turned out that the coaction of the geometry parameter diffuser vane angle and diffuser clearance height is of particular importance.
The experimental results are published as an open CFD testcase “Radiver 2” [17], extending the experimental data base of the testcase “Radiver” published in 2003 by Ziegler [24].
High Pressure Subsonic Nucleation in 1D Nozzles — An Experimental Study
Authors: Guo Tao , Burnett Mark , Turnquist Norman , Moraga Francisco 
Published: September 2014

The presence of moisture in steam turbines is known to cause blade erosion and reduce turbine performance. As a result, nucleating wet steam flow has been the topic of both academic and engineering research for many decades. However, almost all of the previous experimental studies on steam nucleation have been carried out under low pressure supersonic flow conditions, either in converging-diverging (Laval) nozzles or in supersonic airfoil cascades. Some recent experimental studies conducted droplet size/wetness measurements within actual turbines, but these tests in general only give qualitative assessment on the nucleation phenomena. They are not intended to study the mechanisms of the nucleating steam flow.
In this paper, an experimental study of nucleating wet steam flow under high-pressure subsonic flow conditions is presented. In particular, the world’s first high-pressure subsonic nucleation test rig was designed and built at the GE Global Research Center. This advanced test rig takes high pressure (up to 1000 psia) clean steam with controlled inlet superheat and expands it through 1D subsonic nozzles. The Wilson line location and the length of the nucleation zone are controlled through different combinations of inlet steam pressure and superheat, and overall pressure ratios.
An advanced optical measurement system was developed and used to measure the Wilson line, the ensuing condensation zone, and the droplet size and number density generated from nucleation. The flow path in the nozzle is visible through specially designed sapphire windows. The optical system is essentially comprised of two laser-photodiode pairs (405 nm and 689 nm wavelength), which can be traversed along the length of the nozzle.
The experiment data have indicated that significant differences exist between high pressure subsonic nucleation and low pressure supersonic nucleation. Further, an in-house 1D analytical tool as well as a 3D multiphase CFD have been used to model the test runs, and reasonable agreements have been obtained. This study has direct application in the design of Nuclear and Concentrated Solar high pressure steam turbines.