bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fast CE™ — A Radical Approach to Concurrent Engineering
Authors: Barbeau Dennis E. 
Published: December 2014

This paper describes the status and potential for a fast time-to-market concurrent engineering process. The principles have been developed by the author over a 25 year learning process and used effectively on a variety of programs. Fast CE™ is fundamentally predicated on integration of the manufacturing and engineering processes at the conceptual design phase. Commencement at this early date is critical — 80 to 90% of the inherent production unit cost is locked in place during this process. Subsequent to development of an integrated design strategy, both producibility and functional product development evolve in parallel using a “model-centric” approach to maintain the integrity of all elements of the program. Fast CE™ not only eliminates the use of drawings, it requires that they not be used in any capacity except as a convenience reference. This provides tight control over a common data base that directly links all of the activities necessary to design and produce a product. The result is a significant reduction in cost and schedule, with gains in all of the processes required to bring a product to market. Drawing elimination in itself can amount to a savings of as much as one third of the total design cost. The activities previously supported by drawings — quality assurance, for example — are managed through simpler, more functionally oriented processes.
The author describes the elements of Fast CE™ and the radical changes required in certain areas. Historical background traces development of the processes, providing perspective on the strategies and the issues faced and overcome, and leading to the issues currently faced in attainment of its full potential. The cost and schedule gains identified require cultural as well as operational changes. The more radical of these changes present a management challenge to any organization intent on gaining the full spectrum of benefits.
Application of Stress Relaxation Testing in Metallurgical Life Assessment Evaluations of GTD111 Alloy Turbine Buckets
Authors: Daleo Joseph A. , Ellison Keith A. , Woodford David A. 
Published: December 2014

Stress relaxation and constant displacement rate tensile tests were performed on poly-crystalline GTD111 alloy material removed from General Electric MS6001B first stage combustion turbine buckets. Samples were examined in the standard heat treated condition, thermally exposed at 900°C for 5000 hours and from service run buckets. Creep rates of the material were measured and evaluated directly in terms of temperature capability at 850°C and 900°C. Stress relaxation tests done at 0.8% total strain indicated that the creep rate properties in the service exposed airfoil were an order of magnitude higher than the material properties in the standard heat treated condition measured in the root form. In terms of temperature capability, the creep rate properties of the service run airfoil material had decreased by the equivalent of almost 40°C.
The stress relaxation test method was demonstrated to be a very useful tool in quantifying the degradation of creep properties in service run components. Creep data that would require years to gather using conventional creep tests was generated in a few days. This now makes realistic life assessment and repair / replace decisions possible during turbine overhauls.
The test method’s unique ability to measure changes in creep rate over a large stress range, enabled the technique to distinguish between changes in creep strength due to (normal) microstructural evolution from the combined effects of microstructural evolution and strain related creep damage.
A method for estimating standard constant load creep rupture life from the stress relaxation creep rate data is also presented along with time-temperature parameter correlations. The data sets examined in this study indicate that creep rupture lives can be estimated within a factor of three from the stress relaxation data.
The information and analysis techniques described in this paper are directly applicable to metallurgical life assessment evaluations and the re-qualification of repaired General Electric buckets in Frame 3, 5, 6, 7 and 9 engine models.
The Creep Damage Behavior of the Plasma-Sprayed Thermal Barrier Coating System NiCr22Co12Mo9-NiCoCrAlY-ZrO2/7%Y2O3
Authors: Schmidt Uli T. , Vöhringer Otmar , Löhe Detlef 
Published: December 2014

During creep loading metallic substrates impose deformation on deposited ceramic thermal barrier coatings (TBC). Strain accomodation of the TBC is not attained by plastic deformation, but by means of crack initiation, crack opening, crack propagation or sliding of adjacent crack faces. In technical applications a distinction is made between tolerated or desired cracks perpendicular to the surface, and detrimental cracks parallel to the substrate-coating interface. Thus, TBC can respond to creep deformation by segmentation or spallation, the latter being referred to as failure.
The parameters influencing the probability of either segmentation or spallation are temperature, creep rate, magnitude of creep deformation, layer thickness and microstructure of the TBC. It can be stated that spallation failure probability increases with increasing creep rate, creep deformation and layer thickness. The presence of pores between single spraying layers also strongly augments the likelyhood of spallation. No significant influence of temperature on spallation failure probability can be found in the range from 850°C to 1050°C.
Light microscopy and scanning electron microscopy investigations show that the microstructure of the ceramic TBC changes during creep, and that the density of cracks detected on micrographs with low magnification (x50), increases with increasing creep deformation. On the other hand, the density of microcracks visible with high magnification (x500) is constant, or even decreases with increasing creep deformation. These findings are explained by sintering processes enabled by stress relaxation due to formation of macroscopic cracks perpendicular to the surface as a response to creep deformation.
A relationship between microstructural changes and the emission of acoustic signals recorded during creep is presented.
Development and Test of a Catalytic Combustor for an Automotive Gas Turbine
Authors: Lipinski John J. , Brine Philip R. , Buch Rajesh D. , Lester George R. 
Published: December 2014

A catalytic combustor was designed and tested for a small recuperated gas turbine engine for use in a hybrid electric vehicle (HEV). Combustor rig and engine tests were performed with DF-2 diesel fuel, kerosene, and automotive gasoline. Rig test steady-state emissions were measured over the full engine operating range. Nitrogen oxides (NOx) emissions were insensitive to operating condition, and were almost strictly a function of fuel nitrogen content. For low-nitrogen kerosene, NOx emissions less than 1 ppm(vol) (at 15 percent O2) were demonstrated. Startup emissions were measured for conditions modeling engine spoolup from ignition to full speed.
Laboratory engine tests on DF-2 over a range of speeds and loads demonstrated tailpipe emissions less than 10 ppm(vol) NOx and less than 1 ppm(vol) unburned hydrocarbons (HC). NOx, HC, and carbon monoxide (CO) emissions were less than the California State Ultra-Low Emissions Vehicle (ULEV) standards for steady-state operation, corrected for assumed vehicle load and fuel consumption rate.
Testing, Analysis, and CFD Modeling of a Profiled Leading Edge Groove Tilting Pad Journal Bearing
Authors: Edney Stephen L. , Heitland Gregory B. , DeCamillo Scan M. 
Published: December 2014

Testing and analysis of a profiled leading edge groove tilting pad journal bearing developed for light load operation is described. This bearing was designed for a generic, small, high speed steam turbine operating at projected loads of less than 25 psi (172.4 kPa) and journal surface speeds to 400 ft/s (122 m/s). On the second turbine application, a rotor instability was experienced with the oil flowrate reduced to optimize bearing steady state performance. This instability was eliminated by machining a taper on the exit side of the feed groove on each pad. At the reduced flowrate, the profiled groove bearing greatly improved the operating characteristics of the rotor system by reducing vibration amplitudes and stabilizing operation at speed.
This paper is divided into two sections. The first section compares the rotordynamics analysis with test data that shows improved unbalance response and operating stability with the profiled groove bearing. The second section provides original insight of the effect of the profiled geometry on the bearing flow field using computational fluid dynamics models.
Does User-Oriented Gas Turbine Research Pay Off?
Authors: Rooth Rudy A. 
Published: December 2014

In 1994, the Dutch utilities started a five-year program aimed at 1) reduction of the forced unavailability of their gas turbine fleet and 2) keeping the operational and maintenance cost down. The project approaches its completion so now is the time to evaluate what it has delivered. Subjects of the project were the development of on-line and off-line diagnostic techniques, blade life management systems, optimization strategies for maintenance, air filtration and compressor washing, evaluation of NOx control techniques and evaluation and development of test methods for repair and reconditioning techniques. This paper gives an overview of the project achievements and a look at the evolution of the unavailability in the course of the years until 1995.
New (on-line) techniques developed are e.g. a flame stability monitoring system, correlating operational parameters to burner characteristics, a pyrometer with high spatial resolution and a tip shroud deflection monitor. Off-line inspection techniques include the development of a combined in-situ crack detection and sizing instrument as well as a method for measuring alumina depletion from coatings. REMLIF6, a life estimating algorithm for GE Frame 6 turbine blade and nozzles has been completed. Recommendations for optimized filter exchange and compressor washing schedules have been formulated. Development of the forced unavailability shows less problems related to turbine blading, possibly related to better knowledge on blade temperatures, and liners. An increase in burner related problems is noticeable, associated with the introduction of Low-NOx combustion. Overall the forced unavailability figures are going down and a number of problems in recent years has been solved quicker because of tools and knowledge developed in the project. The evolution of maintenance cost is under study.
Effects of Compound Angle Injection on Flat-Plate Film Cooling Through a Row of Conical Holes
Authors: Chen Ping-Hei , Ai Di , Lee Szu-Hsien 
Published: December 2014

This paper presents the measured heat transfer and film cooling results over a flat plate as the secondary flow is ejected into the mainstream through a row of conical holes. A transient liquid crystal thermography was employed to derive the film cooling performance and heat transfer distribution over the test flat plate. Each conical injection hole, with a pitch-to-diameter ratio of 3 on the exit plane, had an expanded angle of 8 degrees. The effects of changing the spanwise injection angles and blowing ratios on both film cooling and heat transfer distributions were investigated. Test pieces in this study used different spanwise injection angles of β = 0°, 45°, and 90° but maintained the same inclination angle of γ = 35°. For each test piece, four different blowing ratios of 0.5, 1.0, 1.25 and 1.5 were tested at Re = 44,000, Tu = 2.3%, δ1/d = 0.22, p/d = 3, and R = 1.06. A baseline check was also conducted for the flat-plate film cooling through the use of straight circular holes. In addition, a comparison was made between the film cooling results using conical holes with those using straight circular holes.
Measured results showed that the laterally averaged heat transfer coefficient increases with the blowing ratio for both straight circular and conical hole configurations. For the simple injection, a conical configuration was found to have better film cooling protection only at higher blowing ratio (M = 1.25 and 1.5). Compound angle injection does not have specific advantage for the film cooling protection in the case of conical configuration.
Separated-Flow Transition: Part 1 — Experimental Methodology and Mode Classification
Authors: Hatman Anca , Wang Ting 
Published: December 2014

This first part of the paper presents techniques implemented for the experimental investigation of the transition mechanism in 2-D pressure driven separated boundary layer flows over a flat plate at inlet free-stream turbulence intensities ranging from 0.3 to 0.6% and imposed adverse pressure gradients ranging from K = − 0.68 × 10−6 to − 6.25 × 10−6. The structure and behavior of the separation bubble were investigated for various flow conditions. The separated-flow transition modes were identified and classified. The distribution end strength of the adverse pressure gradient were obtained by varying the test section outer wall divergence angle.
Specific methods identifying the main parameters that characterize separated-flow transition are introduced and issues regarding measurements of reverse flow are discussed. The methods implemented in determining the separation point, maximum displacement location, the unsteady reattachment region, the start and end of transition, etc. are described.
High-Temperature Properties of SiC-Si3N4 Particle Composites
Authors: Woetting Gerhard , Caspers Bernhard , Gugel Ernst , Westerheide Ralf 
Published: December 2014

Due to promising results in literature, SiC-Si3N4 particle composites in the range 0–100% SiC were evaluated. Focusing on high-temperature properties, mainly Y2O3 was used as sintering additive. Consolidation occurred primarily by hot-pressing, sintering tests were performed for comparison. Besides short-term properties like strength, toughness etc., long-term properties like creep and oxidation behavior were determined.
Results as a function of SiC-content and microstructure were discussed with respect to materials’ performance at high temperatures and possibilities of their production on a technical scale.
Effects of Inlet Flow Field Conditions on the Performance of Centrifugal Compressor Diffusers: Part 2 — Straight-Channel Diffuser
Authors: Deniz Sabri , Greitzer Edward M. , Cumpsty Nicholas A. 
Published: December 2014

This is Part 2 of an examination of influence of inlet flow conditions on the performance and operating range of centrifugal compressor vaned diffusers. The paper describes tests of straight-channel type diffuser, sometimes called a wedge-vane diffuser, and compares the results with those from the discrete-passage diffusers described in Part 1. Effects of diffuser inlet Mach number, flow angle, blockage, and axial flow non-uniformity on diffuser pressure recovery and operating range are addressed.
The straight-channel diffuser investigated has 30 vanes and was designed for the same aerodynamic duty as the discrete-passage diffuser described in Part 1. The ranges of the overall pressure recovery coefficients were 0.65–0.78 for the straight-channel diffuser and 0.60–0.70 for the discrete-passage diffuser; the pressure recovery of the straight-channel diffuser was roughly 10% higher than that of the discrete-passage diffuser. Both types of the diffusers showed similar behavior regarding the dependence on diffuser inlet flow angle and the insensitivity of the performance to inlet flow field axial distortion and Mach number. The operating range of the straight-channel diffuser, as for the discrete-passage diffusers was limited by the onset of rotating stall at a fixed momentum-averaged flow angle into the diffuser, which was for the straight-channel diffuser, αcrit = 70° ±0.5°.
The background, nomenclature and description of the facility and method are all given in Part 1.
Inlet and Exit Flow Characteristics of Mixed Flow Turbines
Authors: Arcoumanis C. , Martinez-Botas R. F. , Nouri J. M. , Su C. C. 
Published: December 2014

The steady performance of mainly two high pressure ratio mixed flow turbines for an automotive turbocharger (expansion ratio of 2.9) has been investigated and the results indicated superior performance of the rotor with a constant inlet blade angle relative to that with a nominally constant incidence angle. These results have been confirmed by the measurement of the three components of velocity, the Reynolds normal stresses and the flow angle at the inlet and exit of the mixed-flow turbine rotors by laser Doppler velocimetry (LDV) under steady state conditions. The turbine testing conditions corresponded to the 50% and 70% design speeds, equivalent to 29,400 and 41,300 rpm respectively.
The velocity results have indicated that the flow upstream of the rotor varies significantly along the blade inlet plane, and this is more evident at the 50% design speed. The flow in the volute behaves as a free vortex except in regions close to the hub, while the exit flow revealed that the constant incidence design rotor has a significantly higher exit swirl angle than the constant blade design, in agreement with the higher exit kinetic energy loss in the former case.
Current Status of Ceramic Gas Turbine (CGT302)
Authors: Kobayashi Hirotake , Tatsumi Tetsuo , Nakashima Takashi , Takehara Isashi , Ichikawa Yoshihiro 
Published: December 2014

In Japan, from the point of view of energy saving and environmental protection, a 300kW Ceramic Gas Turbine (CGT) Research and Development program started in 1988 and is still continuing as a part of “the New Sunshine Project” promoted by the Ministry of International Trade and Industry (MITT).
The final target of the program is to achieve 42% thermal efficiency at 1350°C of turbine inlet temperature (TIT) and to keep NOx emissions below present national regulations. Under contract to the New Energy and Industrial Technology Development Organization (NEDO), Kawasaki Heavy Industries, Ltd. (KHI) has been developing the CGT302 with Kyocera Corporation and Sumitomo Precision Products Co., Ltd.
By the end of the fiscal year 1996, the CGT302 achieved 37.0% thermal efficiency at 1280°C of TIT. In 1997, TIT reached 1350°C and a durability operation for 20 hours at 1350°C was conducted successfully. Also fairly low NOx was proved at 1300°C of TIT. In January 1998, the CGT302 has achieved 37.4% thermal efficiency at 1250°C TIT.
In this paper, we will describe our approaches to the target performance of the CGT302 and current status.
Through Flow Calculation in Axial Flow Turbines Using a Quasi-Orthogonal Solver
Authors: Noera F. , Satta A. 
Published: December 2014

Application of CFD investigating and analysing axial flow turbomachines has reached, in the last years, a high level of accuracy and thus can be applied quite routinely in the prediction of different kinds of flow. The numerical investigation of axial flow turbine performance is of great interest because of the importance of correct product design and of the behaviour in off-design conditions.
In this paper a new formulation of the radial equilibrium equation is presented. This formulation is particularly suitable for turbomachinery numerical investigation, and is applied in a quasi-orthogonal through flow solver. All the terms involved in the proposed formulation have been taken into account in order to solve the more general problem.
Mesh generation and blade geometrical representation are simplified in order to reduce the pre-processing work. In order to evaluate cascade losses and deviation angle, Ainley- and Mathieson semi-empirical correlations and their correction proposed by Dunham and Came and Kacker and Okapuu have been utilised. The four stages Hannover experimental turbine and the Cambridge one have been analysed in different operating conditions; numerical results have been compared with the experimental ones to evaluate the level of accuracy of the proposed procedure.
A Non-Local Theory for the Assessment of Multiaxial High Cycle Fatigue Failure
Authors: Sjödin Björn 
Published: December 2014

Looking at HCF, the most critical component on the turbine is the blade.
At the present moment there is a need for a HCF criterion suitable for evaluation of stresses calculated with the Finite Element Method. Today there are some, such criterions e.g. Sines. However the criterion does not include important aspects such as the influence of; ‘geometrical size’, ‘stressed volume’ or ‘stress gradient’.
A better understanding of the HCF phenomena would give an increase in the design precision and an opportunity to increase the load on the blades.
A proposal is made for a new theory for HCF assessment. The input required by the theory is roughly the Haigh-diagram for a smooth test specimen.
The theory is a merger between the Sines criterion and the statistical approach made by Weibull. 3 basic assumptions are made; equivalent stresses are calculated according to Sines, ‘the weakest link assumption’ and finally that the fatigue limit for a smooth specimen has a statistical distribution.
Comparing the proposal to classical HCF assessment with Haigh-diagram, the following factors are incorporated:
1, stress concentration factor
2, fatigue notch factor (or notch sensitivity factor)
3, geometric volume dependence
4, different Haigh-diagrams for push-pull, bending and torsion
If the factors are incorporated partially or fully remains to be shown. It is also possible to give a geometrical quantification of the so called ‘stressed volume’.
Qualitative and quantitative tests have been made. Looking at them, the theory looks promising. However, it has to be tested further to get acquainted with any shortcomings of the theory.
Microstructure and Property Assessment of Conventionally Cast and Directionally Solidified Buckets Refurbished After Long-Term Service
Authors: Swaminathan V. P. , Cheruvu N. S. , Klein J. M. , Robinson W. M. 
Published: December 2014

Conventionally cast GTD-111EA first stage buckets from GE Frame 5001P-NT engine after 42,000 hours of service, directionally solidified GTD-111DS Frame 5002C buckets after 49,000 hours of service, and conventionally cast IN-738 Frame 5002B buckets after 81,000 hours of service were evaluated before and after refurbishment. These buckets were coated with GT-29, GT-29 plus and RT-22 coatings respectively. Coating condition, microstructural degradation, tensile properties, and creep properties were evaluated in the service aged condition. Microstructure was assessed after the hot isostatic pressing (HIP) and solution heat treatment and again after the full refurbishment and recoating of the buckets. It was found that the GT-29 coating was breached 100% by oxidation in the 5001P engine after service. The GT-29 plus coating on the 5002C engine was breached very slightly and the majority of the coating was still in good condition. The RT-22 coating on the IN-738 bucket was stripped before it was received for evaluation at SwRI. Gamma prime growth, coalescence and agglomeration were found in all of the buckets. Continuous carbide network near the airfoil leading edge was found in the GTD-111EA bucket.
Significant improvement in the microstructural condition was observed after the refurbishment for the GTD-111 buckets. However, the gamma prime morphology was not normal for the IN-738 bucket. Both tensile and creep properties of the GTD-111 buckets showed significant improvement after refurbishment. However, for the IN-738 bucket little improvement on the mechanical properties was observed. The reasons for this and the correlation between the microstructure and properties are discussed in this paper.