bluuebunny/crossref_metadata_2025_split huggingface dataset:
CM 186 LC® Alloy Single Crystal Turbine Vanes
Authors: Burkholder Phil S. , Thomas Malcolm C. , Helmink Randy , Frasier Donald J. , Harris Ken , Wahl Jacqueline B. 
Published: December 2014

There is a need to introduce advanced turbine technology at reduced cost. SX superalloy vanes demonstrate excellent engine performance and durability benefits compared to their polycrystalline counterparts. However, their manufacturing cost can be prohibitive due to low casting and solution heat treatment yields due to rejectable grain defects. High purity (carbon and boron free), ultra high creep and fatigue strength SX alloys are limited to low angle boundaries (LABs) normally not exceeding 6° in critical airfoil locations. Carbon (C) and boron (B) containing SX superalloys (Ross, et al., 1996) can accommodate low angle boundaries in the 9°–12° range with an overall sacrifice in creep and fatigue properties. Aero engine vane segments with complex configurations, can result in not only LAB defects exceeding 9°–12° but also high angle grain boundary (HAB) defects ≥ 15° occurring during the SX solidification process. This is further excaberated by recrystallised grains occurring during solution heat treatment from residual casting stresses and associated strain.
CM 186 LC® is a hafnium (Hf) containing nickel-base superalloy developed for directionally solidified (DS) columnar grain turbine airfoils. SX casting experience — development and production — has shown the alloy can be readily cast into aero turbine multi-airfoil segments. Mechanical property and turbine engine testing show the alloy can accommodate grain boundaries at least up to 30° resulting in high SX casting yields. The SX vane components are either used as-cast or approximately 50% partial solutioned which avoid any recrystallisation (Rx) problems. Component costs can be < 50% of that of a conventional high purity SX alloy.
Mechanical property, oxidation and coating performance characterisation studies on SX CM 186 LC (including DS test pieces) and turbine engine test and application experience show a 72°F (40°C) metal temperature capability improvement (thin wall) over DS MAR M 002 alloy.
NESTEM: A Computational Tool to Perform Probabilistic Structural Analysis of Components Subjected to Uncertain Mechanical and Thermal Loading
Authors: Patel Bhogilal M. , Strack William C. , Nagpal Vinod , Pai Shantaram S. , Murthy P. L. N. 
Published: December 2014

This paper presents an overview of a newly developed code, NESTEM that analyzes structural components subjected to varying thermal and mechanical loads. This program is an enhanced version of NESSUS and has all the capabilities of NESSUS. In addition, it allows one to perform heat transfer analysis. The basic heat transfer variables can be included as random variables along with the mechanical random variables to quantify risk using probabilistic methods and to perform sensitivity analysis.
The analysis capabilities of NESTEM have been demonstrated by analyzing a cylindrical combustor liner. This analysis includes evaluating stresses and their variations at critical points on the liner using material properties, pressure loading and basic heat transfer variables as the random variables. The heat transfer variables are convection temperatures, film coefficients, radiation temperatures, emissivity, absorptivity and conductivity. Cumulative distribution functions and sensitivity factors, for stress responses, for mechanical and thermal random variables are calculated. These results can be used to quickly identify the most critical design variables, in order to optimize the design, to make it cost effective.
Antisurge Control for Variable Geometry Compressors
Authors: Batson B. W. 
Published: December 2014

Compressors used for industrial applications are sometimes fitted with some form of variable geometry. Centrifugal compressors may have adjustable inlet guide vanes on one or multiple stages, or diffuser guide vanes at the discharge of the compressor. Axial compressors often have variable inlet guide vanes or adjustable stators. Such variable geometry compressors are becoming more common in the petroleum and chemical industries.
For many variable geometry compressors (but not all), the boundary between the stable operating region and surge is a surface, not just a curve.
In this paper, we discuss which forms of variable geometry result in a surge limit curve and which forms spread out into a surface. We describe some methods for determining the location of the operating point relative to the surge limit. An example is included showing actual surge points as found in the field. Surge testing to determine the complete surge limit surface is discussed.
A Study of Combustion Characteristics of Gasified Coal Fuel
Authors: Hasegawa Takeharu , Sato Mikio , Nakata Toshihiko 
Published: December 2014

The development of integrated, coal-gasification combined cycle (IGCC) systems provides cost-effective and environmentally sound options for meeting future coal-utilizing power generation needs in the world. The Japanese government and the Electric Power Industries in Japan promoted research and development of an IGCC system. We have being working on developing a low-NOx combustion technology used in gas turbine combustors for IGCC.
Each gaseous fuel produced from some raw materials contained CO and H2 as the main combustible components, and a small amount of CH4. Compositions and calorific values of gasified coal fuels varied widely depending on raw materials and gasifier types. Gaseous fuel, produced in various gasifiers, has a calorific value of 4–13MJ/m 3, which is about one-tenth to one-third that of natural gas. The flame temperatures of fuels increase as the fuel calorific value rises. When the fuel calorific value rises 8MJ/m 3 or higher, the flame temperature is higher than that of natural gas, and so NOx production from nitrogen fixation is expected to increase significantly. Also, some gasified coal fuels contain fuel nitrogen, such as ammonia, if the hot/dry type gas cleaning system is employed. These factors affect the combustion characteristics of the gasified coal fuel.
In this paper, we clarified the influence of gasified coal fuel properties on NOx and CO emissions through experiments using a small diffusion burner and through numerical analysis based on reaction kinetics. The main results were as follows:
(1) NH3 conversion to NOx increases with increasing CH4 concentration in gaseous fuel.
(2) If gaseous fuel contains CH4, there will be some specific equivalence ratio in the primary combustion zone for the minimum NH3 conversion to NOx in the two-staged combustion.
(3) Its specific equivalence ratio in the primary combustion zone increases with decreasing CH4 concentration in gaseous fuel.
(4) If the fuel contains a small percent of CH4, there is no influence of the CO/H2 molar ratio in the fuel on the conversion rate of NH3 to NOx, while there is an influence in the case where fuel contains no CH4. The conversion rate increases with rises in the CO/H2 molar ratio.
(5) As the pressure increases, the conversion rate of NH3 to NOx slightly decreases and the CO emission declines significantly.
Comparison of Theoretical and Experimental Data for an Oscillating Transonic Compressor Cascade
Authors: Carstens Volker , Schmitt Stefan 
Published: December 2014

Numerical and experimental results are compared for a compressor cascade performing harmonic oscillations in transonic flow. The flow field was calculated by a Q3D Navier Stokes code, the basic features of which are the use of an upwind flux difference scheme for the convective terms, the implementation of an effective one-equation turbulence model and the use of deforming multi-block grids. The experimental investigations were performed in an annular cascade windtunnel where unsteady blade pressures were measured for two different operating conditions of the cascade.
The present data were all obtained for tuned torsional modes where the blades performed pitching oscillations with the same frequency and amplitude, but with a constant interblade phase angle. In the first test case the steady flow around the blades was purely subsonic. For the second test case the compressor cascade was run under transonic flow conditions where a normal shock in the front part of the blades’ suction side is followed by a blade passage shock.
It becomes apparent that under subsonic flow conditions the predicted aerodynamic damping coefficients are in resonable agreement with the experimental data, although the numerical pressure amplitudes are much higher than the measured ones. In transonic flow significant discrepancies between computed and experimentally determined pressure amplitudes are observed, whereas the accuracy of the pressure phase prediction is comparable to the subsonic test case. Another important result of these investigations is that oscillations of the blade passage shock lead to strong variations of the local aerodynamic damping of the blades, but do not significantly change the global damping coefficient of the tested compressor cascade.
Flow Field Measurements in an Annular Gas Turbine Exhaust Diffuser With Struts
Authors: Desideri Umberto , Ubertini Stefano 
Published: December 2014

This paper presents the velocity and turbulence characteristics of the flow in an annular diffuser, which is a model of a gas turbine exhaust diffuser with six struts. The diffuser where the measurements were made is a scaled down model of a 10 MW gas turbine, built by GE/Nuovo Pignone.
In a previous paper (Desideri and Manfrida, 1995) 2-D turbulence and velocity measurements were presented with axial inlet velocity conditions.
In this paper a more detailed 3-D analysis of the design and off design behavior of the diffuser is presented. Turbulence characteristics were determined by means of two hot split-film probes, which allowed measuring axial, radial and tangential components of the mean velocity and their fluctuating components. The measuring point is moved inside the diffuser by means of two step-motors, which allow the rotation of the hub and the radial displacement of the probe.
Off-design behavior of the annular diffuser was determined by changing the inlet velocity angle of 10° from axial direction. The effect of swirl on the performance of the diffuser will be presented.
Turbulence microscales were also calculated in regions of interest inside the diffuser, with particular attention to the strut wake.
The 701F Gas Turbine Design Process: Upgrade and Innovations
Authors: Facchini B. , Carcasci C. , Ferrara G. , Innocenti L. , Coutandin D. , Monzi G. , Protto S. 
Published: December 2014

In this paper, a Fiat Avio 701F gas turbine re-design process is presented. This already tested gas turbine has been modified, for a particular re-powering application: a reduction in the net power production is required, whereas efficiency and exhaust temperature have been improved by mean of increased hot gas temperature at the first nozzle inlet section. Consequently this re-powering solution clearly requires consistent re-design efforts to satisfy specific plant operating conditions.
The gas turbine power output has been tuned to the required value by reducing the air inlet mass flowrate; the combustion chamber setting has been modified with particular attention to the control of pollutant emission level. The increase of inlet stator turbine temperature necessitated a complete review of the three cooled turbine stages. The aim of greater overall efficiency with inlet and exit turbine temperature increase also involved the introduction of a new blade material. For design tool flexibility the blade cooling design procedure has been improved making better optimization of the cooling system possible.
In this paper a detailed description of the several gas turbine modifications with particular attention to the blade cooling design procedure and to the corresponding simulation results is reported. The modifications developed could also be introduced on the new version of the 701F, at full power capability, in order to get better efficiency and power.
Coating Stripping Method for Refurbishing of Gas Turbine Blades and Vanes
Authors: Corcoruto Sergio , Guerreschi Umberto , Gandini Ettore 
Published: December 2014

Hot gas path components (blades, vanes, heat shields...) in modern gas turbines are protected against hot corrosion and oxidation by MCrAlY overlay coatings deposited throughout Vacuum Plasma Spray (VPS) process. These coatings are designed to be consumed during the operation of the engine. To extend the life of the parts the exhausted coatings must be removed without damage to the base material, so already used parts could be reapplied with new coatings and returned to service.
A stripping method has been developed in alternative to the acid stripping. The originality of the method is in using a spraying process to deposit onto the MCrAlY coating a layer of aluminium, followed by a diffusion heat treatment in vacuum. The resulting brittle aluminide layer is easily removed by mechanical means, like grit blasting.
The aluminium spraying process has been developed for turbine blades and vanes with a plasma gun positioned on a six axis robot, while uncoated areas are stopped off from aluminising. The penetration of aluminium is controlled by proper heat treatment parameters to guarantee uniformity and repeatability. The capability of recoating stripped parts as new ones has been verified.
Optimization of a Vaned Diffuser Geometry for Radial Compressors: Part I — Investigation of the Influence of Geometry Parameters on Performance of a Diffuser
Authors: Kmecl Tomaz , Dalbert Peter 
Published: December 2014

In the present investigation the influence of different diffuser geometry parameters on the stage efficiency and operating range of radial compressor stages has been studied. In addition to a parallel-walled vaneless diffuser, 20 vaned diffusers were experimentally tested with three different impellers having the same meridional contour. All diffusers were designed for industrial compressor stages with subsonic diffuser flow and had parallel sidewalls, diffuser vanes with simple circular are profiles of constant thickness and rounded leading edges.
In the first part of this investigation the length of the vaneless space, the number of diffuser vanes, the vane length, the inlet vane angle of a diffuser, and the solidity have been altered systematically.
The results show that the throat area of a diffuser, and consequently the number of diffuser vanes, are the most important parameters affecting the operating range of a diffuser. The vaneless space extent and the diffuser vane inlet angle have a significant effect on diffuser efficiency, while their effect on operating range is much smaller. Changing these two parameters induces primarily a shift of diffuser characteristics. The diffuser vane length is a very important parameter at overload, where high losses in a diffuser channel occur when using a long diffuser vane.
Stall Inception in a 5-Stage HP-Compressor With Increased Load due to Inlet Distortion
Authors: Jahnen Werner , Peters Thomas , Fottner Leonhard 
Published: December 2014

Unsteady measurements of the flow and performance of a high speed 5-stage HP compressor have been carried out at different speeds under undistorted conditions and with swirl and total pressure inlet distortions. Distributions of incidence and diffusion factor have been derived from the test data which, together with hot-wire measurements of stall inception, provide new insights into the onset of stall with inlet distortion.
A stall cell initiates as a disturbance in the distorted flow sector, which may decay as it passes through the undistorted sector. Stall inception occurs only when the damping of the disturbance in the undistorted sector is insufficient to prevail its growth. As this damping depends on the size of the disturbance, the Parallel Compressor model, based on the linear stability properties of the undistorted compressor alone, is unable to predict the stall inception with inlet distortion.
Catalytic Combustor Development Within the AGATA Program
Authors: Gabrielsson Rolf , Payen Gerard , Avran Patrick 
Published: December 2014

The European AGATA programme (Advanced Gas Turbine for Automobiles), is a programme dedicated to the development of three critical ceramic components — a catalytic combustor, a radial turbine wheel and a static heat exchanger — for a 60 kW turbogenerator in a hybrid electric vehicle. These three components, which are of critical importance to the achievement of low emissions and high efficiency, have been designed, developed, manufactured and tested as part of a full-scale feasibility study. The AGATA partners represent car manufacturers as well as companies and research institutes in the turbine, catalyst and ceramic material fields in both France and Sweden. The AGATA project commenced in early 1993 and has occupied a 5-year period until April 1998. This paper summarises the results from the development of the catalytic combustor.
The catalytic combustor operates at temperatures in the catalytic section from inlet 935°C to the exhaust 1350°C. Therefore all structural components in the hot section are made of ceramic materials.
The testing and validation have been run through a component test campaign from which it was concluded that:
• The catalytic section substrates showed good behaviour during the high temperature tests.
• Palladium was chosen as the active catalytic material after extensive testing at pilot scale. Ageing at high temperature (1270°C) has a strong effect on catalyst deactivation.
• Emissions levels of the preheater are in agreement with the state of the an for small aero-engines according to the ICAO legislation.
The complete full scale combustor testing was run in the following steps:
• Initial gas analysis tests at inlet temperature 200° lower than the nominal value
• CARS and gas analysis
• Comparison diesel and ethanol fuels
• Final testing at maximum design temperatures and pressure
The catalytic combustor was run on diesel fuel during the complete test period. A test campaign comparing exhaust emissions when running on ethanol fuel was performed at Volvo Aero Turbines. These results showed that the catalyst reaction rate and CO/HC/NOx emissions were similar. This means that the chosen catalytic combustor can be used as a dual fuel combustor diesel/ethanol.
The final test campaign at ONERA, France, was run up to temperatures slightly above the specified maximum design temperatures. Inlet temperature 962°C (design 935°C) and exhaust temperature 1362°C (design 1350°C). These tests showed that NOx emission levels below 4 ppm @15% O2 were obtained when low CO and HC emissions levels were measured at full load conditions. This promising performance level was reached with technologies that still have to be thoroughly evaluated in terms of durability and low cost potential for industrial applications.
An Interactive Methodology for Axial Compressor Design Teaching
Authors: Ramsden K. W. 
Published: December 2014

The implementation of new technology in the gas turbine industry is accelerating at a rate which demands increasing specialisation by its engineering design staff. Simultaneously, this industry has been adopting concurrent engineering practices to reduce product lead-time. Accordingly, the industry now requires its engineers to acquire early competence in a wide range of technological disciplines. In addition, the individual must have a thorough understanding of the impact of component design decisions on both other components and on the engine as a whole.
Against this background, gas turbine educational providers must respond to these increasing demands with teaching programmes that facilitate a faster and deeper understanding of this very complex product. The ambition of the teacher, however, to adequately prepare the student will continue to be limited by time constraints within lecture courses. Hitherto, this has normally resulted in class worked examples which are necessarily narrow in scope and confined to a limited range of design cases.
This paper describes a teaching methodology which is structured to facilitate in-depth understanding of the key interactions between aerodynamics, thermodynamics and mechanical integrity arising in axial compressor design optimisation. This is achieved interactively through a combination of lectures, a hand worked multistage preliminary compressor design, a series of personal computer based design optimisation workshops and a final collective design assessment.
Structure and Propagation of Rotating Stall in a Single- and a Multi-Stage Axial Compressor
Authors: Saxer-Felici H. M. , Saxer A. P. , Ginter F. , Inderbitzin A. , Gyarmathy G. 
Published: December 2014

The structure and propagation of rotating stall cells in a single- and a two-stage subsonic axial compressor is addressed in this paper using computational and experimental analysis. Unsteady solutions of the 2-D inviscid compressible (Euler) equations of motion are presented for one operating point in the fully-developed rotating stall regime for both a single- and a two-stage compressor. The inviscid assumption is verified by comparing the single-stage 2-D in viscid/compressible solution with an equivalent 2-D viscous (Navier-Stokes) result for incompressible flow. The structure of the rotating stall cell is analyzed and compared for the single- and two-stage cases. The numerical solutions are validated against experimental data consisting of flow visualization and unsteady row-by-row static pressure measurements obtained in a four-stage water model of a subsonic compressor.
The CFD solutions supply a link between the observed experimental features and provide additional information on the structure of the stall flow. Based on this study. supporting assumptions regarding the driving mechanisms for the propagation of fully-developed rotating stall cells and their structure are postulated. In methodical respect the results suggest that the inviscid model is able to reproduce the essentials of the flow physics associated with the propagation of fully-developed, full-span rotating stall in a subsonic axial compressor.
Do Formulation Differences between the Reference Listed Drug and Generic Piperacillin-Tazobactam Impact Reconstitution?
Authors: Zheng HaiAn , Truong James , Carroll Fred , Pai Manjunath P. 
Published: December 2014

ABSTRACT

Pharmaceutical differences between the reference listed drug (RLD) and generic formulations of piperacillin-tazobactam may impact the reconstitution process for intravenous administration. This study evaluated the RLD against three generic formulations and measured their reconstitution times using a standardized process. The mean (standard deviation [SD]) reconstitution time for one generic formulation was 5.57 (1.49) min, which was 35% to 42% longer (
P
< 0.002) than that for the RLD and two other formulations. Observable microscopic differences in powder particle morphology may explain these findings.