bluuebunny/crossref_metadata_2025_split huggingface dataset:
Single-Digit Emissions in a Full Scale Catalytic Combustor
Authors: Schlatter James C. , Dalla Betta Ralph A. , Nickolas Sarento G. , Cutrone Martin B. , Beebe Kenneth W. , Tsuchiya Toshiaki 
Published: December 2014

Catalytic combustion offers the possibility of attaining the firing temperatures of current and next generation gas turbines [up to ∼1450°C (2640°F)] with nitrogen oxides (NOx) production as low as 1 part per million by volume (ppmv). Such catalytic combustion technology has been under development at Catalytica for several years, and the first full scale test of the technology took place at the General Electric Company under TEPCO sponsorship in 1992. The results of the most recent and most successful full scale test in this program are reported in this paper.
The catalytic combustor system was designed for the GE Model MS9001E gas turbine fired with natural gas fuel. The 508-mm (20-in) diameter catalytic reactor was operated at conditions representative of the startup and load cycle of that machine. It was verified that the observed NOx levels were produced not in the catalyst, but in the diffusinn flame of the preburner used to start the system and maintain the necessary catalyst inlet temperature. Even so, NOx levels below 5 ppmv (at 15% O2) were achieved at the simulated base load operating point. Carbon monoxide (CO) and unburned hydrocarbons (UHC) emissions were likewise below 10 ppmv at that condition. Single digit emissions levels also were recorded at conditions representative of the combustor operating at 78% load, the first such demonstration of the turndown capability of this system. Throughout the test, dynamic pressure measurements showed the catalytic combustor to be quieter than even the diffusion flame combustors currently in commercial service.
An Introduction to Harmonic Wavelet Analysis of Machine Vibrations
Authors: Bonel-Cerdan Jose I. , Nikolajsen Jorgen L. 
Published: December 2014

The Fast Wavelet Transform (FWT) is a powerful new tool which can be used for vibration analysis and condition monitoring of advanced rotating machinery. The main advantage of wavelet analysis for condition monitoring is that so-called wavelet maps can be produced showing three dimensional plots of amplitude versus frequency and time. This is in contrast to Fast Fourier Transform (FFT) analysis, in which the time domain of the signal is lost. The wavelet maps provide striking visual indications of tiny changes in machine behaviour which cannot be detected in a normal frequency spectrum. This improves the chances of averting catastrophic failures and expands the time window available to take corrective action. Additional advantages of wavelet analysis over FFT analysis include: (1) no requirements for periodicity of the signal, (2) extremely fast computation, (3) the location of patterns in the time domain and (4) an effective detection of high frequency details.
Wavelet analyses of all types are available but user-friendly information is hard to come by and this has a detrimental effect on progress towards practical commercial applications. Thus, the main purpose of this paper is to provide a simple and clear introduction to wavelet analysis and its use in machine condition monitoring. The paper has been written for an audience having some familiarity with spectrum analysis but no prior knowledge of wavelets.
Effective Automatic Expert Systems for Dynamic Predictive Maintenance Applications
Authors: Flanagan Michael A. , Andersson Carsten , Surland Peter 
Published: December 2014

As the need for specialist decision-making has increased with the volume of data produced by modern monitoring systems, and the current trend towards downsizing and external sourcing (for example, specialist consultant companies) has continued, the demand for computer-based expert systems for automatic machine condition (vibration and process) analysis and diagnosis has intensified.
Various levels of success have been achieved, but most expert systems available today do not reflect the actual reasoning process of a human expert; are inherently obsolete for the continuous learning capability required for dynamic applications; and/or require considerable skills in computer simulation or statistical methods to update the system.
In this paper, new techniques and tools are presented that address the basic elements in the reasoning process of a human expert, and offer solutions to the practical implementation of effective and reliable automatic machine diagnosis. Essential tools for optimum automatic spectrum analysis are first introduced, and then a method presented that allows system results to be automatically qualified and improved upon to reflect actual machine conditions. The paper then introduces neural-network technology as a means of implementing a workable, user-defined knowledge base that can be used to augment the expert system with the user’s own knowledge and experience, and the idiosyncrasies of individual machines.
Development and Fabrication of Silicon Nitride Components for Ceramic Gas Turbine
Authors: Makino Keisuke , Mizuno Ken-Ichi , Shimamori Toru 
Published: December 2014

NGK Spark Plug Co., Ltd. has been developing various silicon nitride materials, and the technology for fabricating components for ceramic gas turbines (CGT) using theses materials. We are supplying silicon nitride material components for the project to develop 300 kW class CGT for co-generation in Japan. EC-152 was developed for components that require high strength at high temperature, such as turbine blades and turbine nozzles.
In order to adapt the increasing of the turbine inlet temperature (TIT) up to 1,350 °C in accordance with the project goals, we developed two silicon nitride materials with further unproved properties: ST-1 and ST-2. ST-1 has a higher strength than EC-152 and is suitable for first stage turbine blades and power turbine blades. ST-2 has higher oxidation resistance than EC-152 and is suitable for power turbine nozzles.
In this paper, we report on the properties of these materials, and present the results of evaluations of these materials when they are actually used for CGT components such as first stage turbine blades and power turbine nozzles.
Numerical Analysis of Transonic Compressor Rotor Flow Near Stall Points
Authors: Masaki Daisaku , Kaji Shojiro 
Published: December 2014

A three-dimensional Navier-Stokes solver based upon a high resolution shock-capturing scheme has been developed in order to analyze complex flow phenomena inside transonic fan/compressor rotors, especially tip clearance flow. The aim of this research is to find out a key element concerned with aerodynamic instability of transonic fan/compressor rotors such as rotating stall and surge by using this newly developed numerical tool. The numerical analysis of this research is twofold. First it investigates the flowfield of a transonic compressor rotor along the design speed operating line. It obtains definite flow structures around the tip region and clear description of the transition of the flow pattern inside the clearance gap between operating points, which shows that shock-tip leakage vortex interaction plays an important role on both loss generation and the failure of steady flow, or surge. A model will be proposed on the onset of tip stall in transonic compressor rotors according to the calculated results.
Secondly, the above model will be examined through a series of numerical experiments by altering tip clearance height white keeping the design speed. From qualitative point of view, the model works fairly well and seems geometry-independent for typical transonic fan/compressor rotors. A clue to the optimum clearance is also obtained.
Simple Analytical Techniques to Determine the Disperant Capacity and Metal Deactivator Additive Concentration of JP-8+100 and Other Jet Fuels
Authors: Kauffman Robert E. 
Published: December 2014

The US Air Force is developing an additive package to improve the thermal stability of JP-8 fuels by 100°F. Consequently, JP-8 fuels containing the developed additive package are referred to as JP-8+100 fuels. Field tests of the JP-8+100 fuels have shown that the additive package greatly reduces maintenance cost and labor in comparison to JP-8 fuels by minimizing fuel system malfunctions caused by fuel deposition, e.g., fuel control changeouts, combustor damage, etc. The developed additive package contains three components: antioxidant, dispersant/detergent, and metal deactivator.
This paper presents simple analytical techniques that can be performed on-site or in the laboratory to determine the dispersant capacity and metal deactivator additive concentrations of JP-8+100 fuels. Since several dispersant/detergent candidates are being evaluated for use in the JP-8+100 additive package, the analytical techniques were developed to measure the dispersant capacity of the additive package instead of the concentration of one particular dispersant/detergent. The dispersant capacity test measures the ability of a fuel sample to suspend a metal oxide powder/water/isopropanol mixture. The dispersant capacity test can be used to identify jet fuels which contain the JP-8+100 additive package and to rate the dispersant capacity of a JP-8+100 fuel.
In contrast to the dispersant capacity test, the metal deactivator additive (MDA) tests were designed to determine the concentration of N,N′-disalicylidene-1,2-propanediamine which is the primary MDA used in jet fuels. The MDA tests use fuel soluble compounds or aqueous extraction to chemically react MDA to form colored species. The color of the MDA compound is measured visually for qualitative determinations or spectrometrically for quantitative determinations. Combination of the different MDA tests allows MDA to be detected down to 0.1 ppm regardless of fuel color, age, or type.
The Influence of Downstream Passage on the Flow Within an Annular S-Shaped Duct
Authors: Sonoda Toyotaka , Arima Toshiyuki , Oana Mineyasu 
Published: December 2014

Experimental and numerical investigations were carried out to gain a better understanding or the flow characteristics within an annular S-shaped duct, including the influence of the shape of the downstream passage located at the exit of the duct on the flow. A duct with six struts and the same geometry as that used to connect the compressor spools on our new experimental small two-spool turbofan engine was investigated. Two types of downstream passage were used. One type had a straight annular passage and the other a curved annular passage with a similar meridional flow path geometry to that of the centrifugal compressor.
Results showed that the total pressure loss near the hub is large due to instability of the flow, as compared with that near the casing. Also, a vortex related to the horseshoe vortex was observed near the casing, in the case of the curved annular passage, the total pressure loss near the hub was greatly increased compared with the case of the straight annular passage, and the spatial position of the above vortex depends on the passage core pressure gradient. Furthermore, results of calculation using an in-house-developed three-dimensional Navier-Stokes code with a low Reynolds number k-ε turbulence model were in good qualitative agreement with experimental results. According to the simulation results, a region of very high pressure loss is observed near the hub at the duct exit with the increase of inlet boundary layer thickness. Such regions of high pressure loss may act on the downstream compressor as a large inlet distortion, and strongly affect downstream compressor performance.
Energy Input of a Centrifugal Stage Into the Attached Piping System During Mild Surge
Authors: Ribi Beat , Gyarmathy George 
Published: December 2014

Subjected to an oscillating flow rate a compressor may feed additional (excitational) energy into the attached piping system. The relation between this additional energy input and the instantaneous behavior of a centrifugal compressor stage is dealt in a first part. Modeling the stage behavior by taking into account either inertia of the enclosed fluid mass or a first-order transient element or transient stall in any component leads to a different energy input.
The energy input at a flow rate oscillation of given frequency and amplitude was calculated as a function of the slope of the characteristic and the reduced frequency applying a previously published model to describe the instantaneous behavior of the stage. In this model transient stall in the diffuser is taken into account. At reduced frequencies above unity the energy input of the diffuser was reduced by a considerable amount due to the specified instantaneous behavior of the diffuser. This indicates a potential to reduce the additional energy input of the diffuser either by increasing the time constant of the stall process or by increasing the mild surge frequency. For the investigated diffuser size the required reduced frequencies imply mild surge frequencies in a range being too high for industrial application (> 200 Hz). Still, this method turned out to give useful insight into the link between the instantaneous behavior of the compressor and its energy input.
In a second part for the same centrifugal compressor the energy contribution of several stage segments during mild surge oscillations was determined from detailed instantaneous measurements. As a result the contribution of each stage segment to the conservation of the mild surge pulsation emerges. Although at the investigated mild surge frequencies the stage segments no longer behave strictly quasi-steadily their contribution to the additional energy input is found to be mainly determined by the slope of their quasi-steady characteristic.
Progress on the Hybrid Vehicle Turbine Engine Technology Support (HVTE-TS) Program
Authors: Sinnet George T. , French J. Mark , Groseclose Lance E. 
Published: December 2014

The purpose of the HVTE-TS program is to develop gas turbine engine technology in support of U.S. Department of Energy/automotive industry programs exploring the use of gas turbine generator sets in hybrid-electric automotive propulsion systems.
The primary objective is the development of four key technologies to be applied to advanced turbogenerators for hybrid vehicles:
• structural ceramic materials and processes
• low emissions combustion systems
• regenerators and seal systems
• insulation systems and processes.
The HVTE-TS program builds upon the significant technology base already established by the previous DoE/NASA Advanced Turbine Technology Applications Project (ATTAP).
HVTE-TS activities during 1996 included: ceramic component design, materials and component characterization, ceramic component process development and fabrication, ceramic component rig testing, and test-bed engine installation and setup. Progress has also been made in the durability testing of various regenerator materials and components, as well as in the application of unique insulation systems. This paper highlights recent progress and current status of each of the four key technologies described above.
Numerical Simulation of the Flow Through the Rotor of a Radial Inflow Turbine
Authors: Amedick V. , Simon H. 
Published: December 2014

An existing Navier-Stokes solver to simulate the turbulent transonic flow using block-structured grids has been used to optimize the guide vanes of radial inflow turbines. The code has been extended to calculate the flow in the rotating parts of turbomachines and is now used to simulate the turbulent flow through the rotor of a radial inflow turbine.
The results of three calculations are presented (inviscid and viscous flow without tip clearance, viscous flow with tip clearance). The flowfield is investigated at design conditions where a large incidence angle exists at the entrance of the rotor. Unsteady effects are neglected.
The comparison of the results of the inviscid and viscous simulations shows the strong influence of the viscous forces. Strong secondary flow patterns are found in the vicinity of the blades and the walls. Special attention has been paid to the analysis of the flow through the gap between the casing and the blades. The determination of the mass flow rate through the gap shows that mass is transported from the suction towards the pressure side of the blade at the beginning of the blade (6.1% of the blade length). Thereafter, the mass flow through the gap changes its direction.
Automatic Mesh Generation by a Mixed Advancing-Front Delaunay Approach
Authors: Corral Roque , Barroso Juan Manuel , Burgos Manuel Antonio 
Published: December 2014

A simple, three-dimensional, unstructured grid generation system is discussed and relevant results for turbomachinery and exhaust systems applications are presented. The method makes special emphasis in algorithm selection based in a small development effort to grid quality ratio. Engineering decisions based on state of the art grid technology knowledge have been adopted to balance fast development progress and turnover time.
The system is based in the sequential execution of Advancing Front and a Delaunay algorithms to produced solution adapted meshes. In a first step a coarse background grid is created by the Advancing-Front method. During this phase boundaries are strictly preserved due to the nature of the approach. At this stage a Delaunay algorithm is employed and the boundary faces are blocked so that they cannot be destroyed in further triangulations. Since both techniques collaborate in the solution of the problem it is possible to write simplified versions of the algorithms that retain nearly all the benefits and eliminate most of the troubles while keeping still reasonable performances.
Origins of Loss Within a Multistage Turbine Environment Under Conditions of Partial Admission
Authors: Wakeley Guy R. , Potts Ian 
Published: December 2014

A partially admitted first stage is routinely used in a wide variety of turbo-machines to match the turbine swallowing capacity to the cycle pressure ratio over a range of outputs. Such a configuration is often favoured for applications in which optimised part-load efficiency is a design requirement. Partial admission is achieved by dividing the stator row into discrete arcs, each of which can be separately supplied with fluid. This arrangement creates circumferential discontinuities and considerable unsteadiness in the flow field within the intra-stage gap, and this unsteadiness can propagate through several downstream rows of fully admitted blading.
In the current work an unsteady, multi-stage, multi-passage, Navier-Stokes solver has been validated against experimental results from a multistage axial flow air turbine. Interstage traverses of static and total pressure are shown to agree well with the CFD predictions, and the measured and predicted partial admission loss is compared with published correlations. It is further shown that the operating point of downstream stages is influenced by the degree of partial admission in the first stage. Additionally, increased alternating blade bending stresses are predicted. These phenomena are not included in any published turbine design methods, and are discussed within the context of large output steam turbine optimisation.
A Magnetic Bearing Suspension System for High Temperature Gas Turbine Applications: Part III — Magnetic Actuator Development
Authors: Kelleher William P. , Kondoleon Anthony S. 
Published: December 2014

Magnetic bearings, unlike traditional mechanical bearings, consist of a series of components when mated together, form a stabilized system. A series of four papers will summaries the results carried out at Draper in the development of a high temperature magnetic bearing suspension system for a gas turbine application. Part I [1] will document our approach for rotordynamics modeling of the turbine shaft and the development of models for use in our simulation programs. Part II [2] documents the simulation efforts and the control system which resulted from this effort. Parts III and IV [3] document the design and fabrication of the magnetic bearing actuators and the auxiliary touchdown bearings.
This paper, part III, deals with the design of the high temperature magnetic bearing actuators. Two radial and one axial magnetic bearing actuator were designed to meet the requirements for the turbine application. No bias coils are included in these design. The biasing flux is provided by current from the control power amplifiers. All the coils are made from ceramic coated copper wire and are terminated to high temperature connectors designed into the actuators. The new high strength Hiperco 50 HS material was chosen for the rotor lamination material for the radial bearings. A customized heat treatment process for this material in a high vacuum environment was developed to insure the maximum strength was obtained with the maximum magnetic properties. High temperature ceramic coated copper wire and bonding and potting material used for the coil assembly were tested up to 650 degrees C without failures.
Effects of Very High Free-Stream Turbulence on the Jet-Mainstream Interaction in a Film Cooling Flow
Authors: Kohli Atul , Bogard David G. 
Published: December 2014

Dispersion of coolant jets in a film cooling flow field is the result of a highly complex interaction between the film cooling jets and the mainstream. Understanding this complex interaction, particularly near the injection location, is critical for improving the predictive capabilities of existing film cooling models, especially when very high free-stream turbulence levels exist. This study uses a high frequency response temperature sensor to investigate the mean and fluctuating thermal field of a film cooling flow for two vastly different free-stream turbulence levels (0.5% and 20%). The high frequency response temperature sensor provides new information about the film cooling flow in terms of actual rms levels (Θ′), probability density functions (pdf’s), and frequency spectra of the thermal field. Results are presented for both free-stream conditions using round holes inclined at 35°, at a momentum flux ratio of I = 0.156 and density ratio of DR = 1.05.
The mean thermal field results show severe degradation of the film cooling jet occurs with very high free-stream turbulence levels. Temperature rms results indicate levels as high as Θ′ = 0.25 exist at the jet-mainstream interface. More information is provided by the temperature pdf’s which are able to identify differences in the jet-mainstream interaction for the two free-stream conditions. With small free-stream turbulence, strong intermittent flow structures generated at the jet-mainstream interface disperse the jet by moving hot mainstream fluid into the coolant core, and ejecting coolant fluid into the mainstream. When the free-stream has large scales and very high turbulence levels, the jet-mainstream interface is obliterated by large scale turbulent structures originating from the free-stream which completely penetrate the coolant jet causing very rapid dispersion of the film cooling jet.
Experimental Investigation of an Atmospheric Rectangular Rich Quench Lean Combustor Sector for Aeroengines
Authors: Griebel Peter , Fischer Michael , Hassa Christoph , Magens Eggert , Nannen Henning , Winandy Adolf , Chrysostomou Antigoni , Meier Ulrich , Stricker Winfried 
Published: December 2014

In this research work the potential of rich quench lean combustion for low emission aeroengines is investigated in a rectangular atmospheric sector, representing a segment of an annular combustor. For a constant design point (cruise) the mixing process and the NOx formation are studied in detail by concentration, temperature and velocity measurements using intrusive and non-intrusive measuring techniques.
Measurements at the exit of the homogeneous primary zone show relatively high levels of non-thermal NO. The NOx formation in the quench zone is very low due to the quick mixing of the secondary air achieved by an adequate penetration of the secondary air jets and a high turbulence level. The NOx and CO emissions at the combustor exit are low and the pattern factor of the temperature distribution is sufficient.