bluuebunny/crossref_metadata_2025 huggingface dataset:
Rainbow Field Test of Coatings for Hot Corrosion Protection of Gas Turbine Hot Section Components
Authors: Van Roode Mark , Kubarych Kenneth G. , McCarron Russell L.
Published: March 2015

The work described in this paper was conducted under Electric Power Research Institute (EPRI) Contract RP 2465, “Rainbow Test of Advanced Coatings for Gas Turbine Blades and Vanes”.

A field test of a rainbow rotor and nozzle was carried out to establish the hot corrosion protection of various aluminide and MCrAlX (X = Y, Hf) overlay coatings on first stage blades and nozzles of a Centaur gas turbine operating in Valera, Venezuela. The blade coatings included both simple and precious metal aluminides, Electron Beam-Physical Vapor Deposition (EB-PVD) coatings and Low Pressure Plasma Spray (LPPS) coatings on Inconel-738LC, Inconel-792 and MAR-M421 substrates. The turbine nozzle vanes were coated by similar methods on FSX-414 and MAR-M509 substrates. Field testing was performed under industrial conditions where the continuous duty engine, used for power generation, ran on a liquid fuel contaminated with sodium and sulfur. The engine test was terminated after nearly 8,000 hours of operation. Visual examination and micro-structural analysis indicated that EB-PVD and LPPS overlay coatings were more effective than simple and modified aluminides for hot section hot corrosion protection. The protection of overlay coatings on nozzle airfoils was found to increase with their chromium content.
Investigation of the Heat Transfer in High Temperature Gas Turbine Vanes
Authors: Sato Tomohiko , Takeishi Kenichiro
Published: March 2015

The demand for higher efficiency, higher temperature industrial gas turbines used for the combined cycle plants has increased. The key technology of such high-temperature gas turbines with a turbine inlet temperature of 1300°C is the development of reliable air-cooled turbine vanes and blades. The life prediction of such air-cooled turbine vanes is strongly dependent on an accurate prediction of the metal temperature. The problem of temperature prediction is essentially one of obtaining the convective heat transfer boundary conditions on the external and internal surfaces of the vane. In this paper, typical heat transfer data which are indispensable for the analysis, are presented. Improvement of the temperature prediction accuracy within 25°C, the final goal, is sought by feeding the discrepancy between the cascade test and the analysis back into the fundamental heat transfer tests.
The Development of a Diesel Burning Combustion Chamber With a Multiple Jet Primary Zone
Authors: Cottington R. V. , Hakluytt J. P. D. , Tilston J. R.
Published: March 2015

A new primary zone for a gas turbine combustor has been developed which achieves efficient combustion in fuel lean conditions for minimizing carbon formation. This uses a large number of jets in the head of the chamber to generate independent shear layers in a co-operative array. Good combustion performance, wide fuel/air ratio operational range and tolerance to fuel quality have been demonstrated on research rigs. The combustor itself has been developed to an engine standard for a naval gas turbine required to operate with low smoke emission on distillate diesel fuel. The rig programme used to optimise the design is described together with results from engine evaluation. Practical advantages of this type of chamber apply equally to aero applications on kerosene.
Experimental Evaluation of Fuel Injection Configurations for a Lean-Premixed Low NOx Gas Turbine Combustor
Authors: Smith Kenneth O. , Kurzynske F. R. , Angello Leonard C.
Published: March 2015

The design and testing of three natural gas fuel injector configurations for a low emissions gas turbine combustor are described. The injectors provided varying degrees of fuel/air premixing and permitted an assessment of the degree of premixing necessary to achieve NOx emissions below the program goal of 10 ppm. The work described represents a preliminary step in an effort to develop production-level gas turbine combustor hardware with ultra-low NOx capabilities.
Unsteady Pressure Distributions on the Impeller Blades of a Centrifugal Pump-Impeller Operating Off-Design
Authors: Kikuyama K. , Minemura K. , Hasegawa Y. , Asakura E. , Murakami M.
Published: March 2015

Pressure distributions on the impeller blades of a centrifugal pump were examined experimentally. The periodic pressure change caused in the suction and delivery pipes by the interaction between the rotating impeller blades and the dividing ridge of the volute casing was small. However, a noticeable cyclic change in the pressure on the blade surface was measured and related to the nonuniform pressure distribution in the volute casing at off-design flow rates. In a lower than normal range of flow rates this pressure fluctuation was largely increased near the leading edge of the blade due to the turbulent fluctuations and the flow separation from the blade surfaces. These periodic pressure changes have a large effect upon cavitation inception along the impeller periphery.
Development of the AGT101 Regenerator Seals
Authors: Fucinari C. A. , Vallance J. K. , Rahnke C. J.
Published: March 2015

The design and development of the regenerator seals used in the AGT101 gas turbine engine are described in this paper. The all ceramic AGT101 gas turbine engine was designed for 100 hp at 5:1 pressure ratio with 2500F (1371C) turbine inlet temperature.

Six distinct phases of seal design were investigated experimentally and analytically to develop the final design. Static and dynamic test rig results obtained during the seal development program are presented. In addition, analytical techniques are described. The program objectives of reduced seal leakage, without additional diaphragm cooling, to 3.6% of total engine airflow and higher seal operating temperature resulting from the 2000F (1093C) inlet exhaust gas temperature were met.
Prediction of Gas Turbine Combustor-Liner Temperature
Authors: Najjar Yousef S. H. , Droubi Riad M.
Published: March 2015

Broadening of fuel specifications decreases the hydrogen content and increases the aromatics and final boiling point. The cumulative effect will be an increase in soot formation hence flame radiation which affects flame tube durability.

In this work an analytical study is made where empirical formulae are developed for luminosity, radiation and convection at idle and full load conditions. These equations predict combustor liner temperature with high degree of agreement with previous experimental work.
A Multi-Grid Algorithm for 2-D Transonic Potential Cascade Flow
Authors: Ji Wei , Jiang Hongde , Cai Ruixian
Published: March 2015

A fast effective Multi-grid algorithm for calculating 2-D transonic cascade flow governed by full-potential equation is presented in this paper. Numerical results obtained show the powerful effect of the method in both accelerating convergence and improving accuracy. In addition, according to the conservation of potential equations, a reasonable treatment for cascade leading edge calculation in H-type grid is also presented.
Wall Shear Stress Measurement in Blade End-Wall Corner Region
Authors: Bhargava R. , Raj R. , Boldman D. R.
Published: March 2015

Experimental results on the local wall shear stress vector and surface pressure measurements upstream and in the blade end-wall corner region are presented in this paper. The measurements were obtained at a free stream velocity of 27.3 m/s with the Reynolds number based on Preston tube outer diameter and friction velocity varying from 30 to 100. A specially constructed Preston tube, the tip of which can be concentrically rotated about its axis of rotation at the measurement location, was employed for the measurement of wall shear stress vector. The magnitude of the wall shear stress in the vicinity of the corner was observed to increase significantly (≈170 % max.) compared to its far upstream value. This increase was consistently found to be higher on the blade surface compared to its value on the plate surface of the blade end-wall corner. On both the surfaces in the blade end-wall corner, the variation of the wall shear stress direction was found to be more predominant in the vicinity of the blade leading edge location. The trend of the measured wall shear stress direction showed good agreement with the limiting streamline directions obtained from the flow visualization studies. The surface pressure variation, at any axial station in the corner region, on the flat plate part of the blade end-wall corner was found to be relatively larger than on the blade surface. Some plausible explanation for the observed variation in the local wall shear stress and surface pressure in the blade end-wall corner are described here.
Analysis of Windage Losses and Velocity Distribution for a Shrouded Rotating Disk
Authors: Gärtner W.
Published: March 2015

An analysis of experimental results was carried out, establishing a direct correlation between measured velocity profiles and windage losses for a rotating disk inside a shrouded stator as typically found in turbomachinery.

The analysis gives information on the regions of the rotating and static parts, which have a dominant effect upon disk windage.
Stability of Conical and Curved Annular Diffusers for Mixed-Flow Compressors
Authors: Abir A. , Whitfield A.
Published: March 2015

For mixed-flow compressors the downstream vaneless diffuser can be either a straight or curved annular passage. Investigations have been carried out on model diffusers six times larger than those employed in a turbocharger study, Whitfield et al (1978). This made it possible to carry out detailed internal flow measurements using a five hole yaw probe and a hot wire anemometer. The development of the flow profiles throughout the diffuser were studied with particular reference to the onset of unstable conditions. Flush mounted wall pressure transducers were also used to detect the onset of unstable flows and to measure the extent and development of the unsteady conditions.

Two curved and one straight annular diffusers have been tested in order to study their relative merits. In addition, the results obtained with a straight radial diffuser are included for comparison. It has generally been observed that the straight annular diffuser was the least stable, with the radial diffuser exhibiting the best stability characteristics. Of the two curved annular diffusers tested flow stability was improved by reducing the passage width. In both cases, however, the curved diffuser proved to be clearly superior to the simpler straight design.
Characteristics of a Centrifugal Compressor With a Radial Shelf Diffuser
Authors: Hanus G. J.
Published: March 2015

An experimental investigation was conducted to determine the range and efficiency characteristics of a “shelf” vaneless, radial diffuser in a centrifugal compressor. The shelf describes a region immediately downstream of the impeller exit in which a step increase in the radial diffuser width is introduced, followed by a specified meridional convergence back to a reference diffuser width. Various shelf geometries were tested and compared with a reference diffuser to establish choke point change, surge point variation and efficiency changes over a range of impeller speeds. The shelf diffuser concept extended the choke point over the reference configuration by 9% at the lowest impeller speed, between 5% and 8% at the intermediate speeds (depending upon the particular shelf geometry tested) and less than 3% at the highest speed. Surge points at all impeller exit Mach number conditions remained nearly unchanged. Peak efficiency changes for the various shelf geometries were not dramatic, varying ± 2-1/2 points from the reference case, depending on impeller speed. Detailed measurements of pressure within the shelf segment of the diffuser demonstrated nearly equivalent loss characteristics as documented for the reference configuration. Profiles of total pressure and flow angle just downstream of the shelf segment exhibited extremely flat characteristics for both the reference as well as the shelf configurations.
Combined Cycle Repowering Two Concepts at Virginia Power
Authors: Rives J. D. , Letarte J. R. , Catina J. L.
Published: March 2015

A study was undertaken to determine the engineering and economic feasibility of repowering several conventional pulverized coal and oil fired units with combustion turbines.

Both feedwater repowering and hot windbox repowering were examined. Performance was evaluated using PEPSE.

The results of the most promising units are presented in detail.

The duration of the study was six months and the project cost approximately $75,000.
Digital Controls for Gas Turbine Engines
Authors: Robinson K.
Published: March 2015

This paper begins by first describing the simplistic requirements of a gas turbine engine; how these requirements are best satisfied, frequently with the aid of electronic control systems; what the trade-off between integrity and reliability means; and finally, but forming a major section, this paper describes in qualitative detail a few of the current programmes for Full Authority Digital Engine Controls (FADEC).
Application of the Transient Test Technique to Measure Local Heat Transfer Coefficients Associated With Augmented Airfoil Cooling Passages
Authors: Saabas H. J. , Arora S. C. , Messeh W. Abdel
Published: March 2015

The failure of a turbine airfoil is a local phenomena. However, to date, the design of these airfoils has been based on steady state heat transfer tests that are capable of yielding only locally averaged data. To overcome this limitation, a transient technique using active surface coatings has been developed and is capable of yielding local data. This technique has been used to determine the Nusselt number distributions within augmented passages typical of gas turbine airfoils. However, certain assumptions have been made in these analyses without verification. This paper will address this aspect of the problem, as well as an improved data reduction procedure, and an alternative error analysis.

The data reduction procedure has been improved by incorporating a higher order approximation to the convective boundary condition, and by introducing a means of calculating the fluid bulk temperature-time-space profile. An image analysis system which yields an unbiased means of determining the time required for the surface to reach a specified temperature is introduced. Furthermore, it was observed that for augmented surfaces, the one dimensional conduction assumption made in the heat transfer solution is not valid for all times. Finally, treating the experimentally obtained quantities as values that are randomly distributed about some true value is not correct for all experimentally measured quantities.
Navier-Stokes Predictions of Transition, Loss and Heat Transfer in a Turbine Cascade
Authors: Birch N. T.
Published: March 2015

The loss and heat transfer of a turbine cascade are strongly influenced by the location and extent of the transitional boundary layer. In this paper, two approaches are adopted to predict the onset and extent of transition within a 2-D explicit Navier-Stokes solution procedure. In the first, transition is predicted by coupling transition data correlations with an algebraic turbulence model. In the second, a low Reynolds Number one-equation turbulence model is used. Comparison is made with the turbine cascade data of Nicholson et al. (1982). This indicates that the first model gives good predictions of suction surface behaviour but poor predictions on the pressure surface. The model is also difficult to apply in a N-S method. The second model gives good predictions of pressure surface behaviour but consistently predicts transition near the leading edge on the suction surface. The latter is attributed to a Mach Number over-speed and leading edge effects.
A Method for Calculating Turbulent Boundary Layers and Losses in the Flow Channels of Turbomachines
Authors: Schumann Lawrence F.
Published: March 2015

An interactive inviscid core flow-boundary layer method is presented for the calculation of turbomachine channel flows. For this method, a one-dimensional inviscid core flow is assumed. The end-wall and blade surface boundary layers are calculated using an integral entrainment method. The boundary layers are assumed to be collateral and thus are two-dimensional. The boundary layer equations are written in a stream-line coordinate system. The streamwise velocity profiles are approximated by power law profiles. Compressibility is accounted for in the streamwise direction but not in the normal direction.

Equations are derived for the special cases of conical and two-dimensional rectangular diffusers. For these cases, the assumptions of a one-dimensional core flow and collateral boundary layers are valid. Results using the method are compared with experiment and good quantitative agreement is obtained.
AGT101: Ceramic Gas Turbine Development
Authors: Boyd G. L. , Easley M. L. , Kreiner D. M.
Published: March 2015

A major technical effort has resulted in recent testing of the all-ceramic hot section in the DOE/NASA sponsored AGT101 Advanced Gas Turbine. This testing was preceded by critical component developments including ceramic structures design evolution to satisfactorily pass the peak stress start transients with 25-percent margin. Ceramic structures test evaluation at 2500F (1371C), ceramic combustor operation on various fuels and ceramic static seal leakage reduction have been necessary for the ceramic engine test. The most challenging ceramic component, the turbine rotor, has undergone successful fabrication development, but further process and material development are necessary to meet the high temperature durability goals.

The 100-hour engine test of the ceramic structures to 2100F (1149C), and the later 85-hour engine test of the all-ceramic hot section to 2200F (1204C) have been important program accomplishments. Full speed operation to 100,000 rpm and a ceramic rotor tip speed of 2300 ft/sec (701 m/s) has been demonstrated. The ability of these experimental gas turbines to operate in a regime where the unique properties of structural ceramics can be exploited offers the opportunity to further advance ceramic technology.
A Trade-Off Study of Rotor Tip Clearance Flow in a Turbine/Exhaust Diffuser System
Authors: Farokhi Saeed
Published: March 2015

In a modern gas turbine power plant, the axial exhaust diffuser accounts for up to 10% of the generator power. An unshrouded rotor, due to its highly energetic tip clearance flow, improves the pressure recovery characteristic of the exhaust diffuser, while the power production within the blading suffers a loss as a result of the tip leakage flow. In this paper, these conflicting trends are thermodynamically investigated and nondimensional expressions are derived which facilitate the task of a gas turbine system designer. Conservatively, 1% thermal efficiency gain results from elimination of the last rotor tip clearance flow. The corresponding increase in thermal efficiency of a modern gas turbine power plant due to enhanced diffuser pressure recovery is less than one percent.
Pressure Distributions in the Tip Clearance Region of an Unshrouded Axial Turbine as Affecting the Problem of Tip Burnout
Authors: Bindon Jeffery P.
Published: March 2015

The pressure distribution in the tip clearance region of a 2D turbine cascade was examined with reference to unknown factors which cause high heat transfer rates and burnout along the edge of the pressure surface of unshrouded cooled axial turbines.

Using a special micro-tapping technique, the pressure along a very narrow strip of the blade edge was found to be 2.8 times lower than the cascade outlet pressure. This low pressure, coupled with a thin boundary layer due to the intense acceleration at gap entry, are believed to cause blade burnout. The flow phenomena causing the low pressure are of very small scale and do not appear to have been previously reported.

The ultra low pressure is primarily caused by the sharp flow curvature demanded of the leakage flow at gap entry. The curvature is made more severe by the apparent attachement of the flow around the corner instead of immediately separating to increase the radius demanded of the flow. The low pressures are intensified by a depression in the suction corner and by the formation of a separation bubble in the clearance gap. The bubble creates a venturi action. The suction corner depression is due to the mainstream flow moving round the leakage and secondary vortices.
Design Criteria and Efficiency Prediction for Radial Inflow Turbines
Authors: Perdichizzi Antonio , Lozza Giovanni
Published: March 2015

A theoretical investigation was performed to predict the maximum achievable efficiency of radial inflow turbines for different design conditions. The analytical tool used in the investigation is a computer code able to perform the contemporary optimization of the main design variables, in order to obtain maximum efficiency. Since the results are strictly dependent on the loss correlations, reliability of the efficiency predictions was tested at first by comparison with several test-cases available in literature: good agreement with experimental data was found, pointing to the validity of the results presented here.

A large number of cases were analyzed: the efficiency and the main design parameters, obtained after the optimization process, are presented for optimum specific speed. Turbine efficiency was found to be dependent both on compressibility effects, related to the volume expansion ratio, and on actual turbine size, accounting for geometric non-similarity effects. Influence of non-optimum specific speed is also discussed.

By means of similarity rules, the results enable turbine design to be performed in a simple way, for a variety of working fluids and design conditions.
Calculation of a Three-Dimensional Turbomachinery Rotor Flow With a Navier-Stokes Code
Authors: Warfield Matthew J. , Lakshminarayana B.
Published: March 2015

This paper deals with a numerical solution of the full Navier-Stokes equations governing the flowfield in a turbomachinery rotor. The incompressible equations are solved using a pseudocompressibility time marching code. A two-equation turbulence model (k-ε) coupled with a vectorial eddy viscosity model based on an Algebraic Reynolds Stress Model is used to account for the anisotropic effects of rotation and three dimensionality. The predictions are compared with laser doppler velocimeter and hot wire data acquired in a compressor rotor passage at two different flow coefficients. The predicted blade to blade profiles of velocity at various radial locations as well as the streamwise velocity profiles in the blade boundary layer show good agreement with experimental data. The radial velocities are qualitatively predicted but good comparison with data was not achieved. Boundary layer growth is predicted reasonably well.
Water Wash System for Marine Gas Turbine Inlet Filters
Authors: Reinauer Glenn A.
Published: March 2015

A water wash system has been developed to allow greater operating flexibility of marine gas turbine intake filters in dust/sand conditions. The water wash system provides protection against sand and dust ingestion previously obtainable only with heavy, expensive inertial separators. Routine filter maintenance is greatly simplified with the use of this system and leads to an average pressure drop reduction through the intake system. This reduction results in significant fuel savings. Furthermore, the introduction of a Propylene Glycol/sea water mixture through the water wash system has shown to be an effective alternative to conventional bleed air de-icing under ice/snow conditions.
Theoretical and Experimental Analysis of a Compressor Cascade at Supercritical Flow Conditions
Authors: Weber A. , Faden M. , Starken H. , Jawtusch V.
Published: March 2015

A comparison theory - experiment in terms of profile Mach number distribution, loss behavior and exit flow angle has been made for a compressor rotor cascade at M1 = 0.85. Measurements in the cascade wind tunnel and calculations were performed over the whole incidence range.

(A) A 2-D finite element method applied to the full potential equation is used as analysis code.

(B) Viscous effects are considered by using McNally’s integral boundary layer method with additional procedures for laminar and turbulent separation and shock boundary layer interaction.

(A) and (B) are coupled iteratively by adding the displacement thickness to the metal blade contour.

(C) The averaged exit flow properties and the total pressure loss coefficient are evaluated by application of the conservation laws.
Design and Application of a Natural Gas Pipeline Optimization Program
Authors: Gilmour Jill
Published: March 2015

A software package which optimizes natural gas pipeline operation for minimum fuel consumption is in use on a commercial transmission pipeline. This Optimization Program has resulted in pipeline fuel savings in daily pipeline operation. In addition, the effect of a new compressor/turbine unit on the pipeline system as a whole can be accurately and easily quantified through use of the Optimization Program before the unit is even installed. The results from one turbine replacement study showed the total system fuel consumption and operating hours predicted for each unit were not directly related to a high turbine efficiency.

This paper describes the simulation techniques used for the gas turbine and compressor modeling. The methodology behind the system-wide optimization is also provided, along with a detailed discussion of the program application to gas turbine and compressor replacement studies.
Characterization of the Multiaxial States of Stress in an Uncooled Gas Turbine Blade
Authors: Fischersworring A. , Koschel W.
Published: March 2015

The assessment of fatigue-creep life of hot engine components either using conventional safe life design approach or damage tolerant design concepts require the computation and evaluation of the stress-strain-temperature-time cycles corresponding to the operational sequences. For typical jet engine operations the temperature and elastic stress-strain states for an uncooled turbine blade were calculated using finite elements. A primary concern was the aspect of multiaxiality and associated non-proportionality. The results are discussed in regard to multiaxial equivalent damage concepts.
Research and Development on the HPT of the AGTJ-100B
Authors: Arai Masashi , Imai Tetsu , Teshima Kiyomi , Koga Akinori
Published: March 2015

The final target of development of the advanced gas turbine sponsored by MITI of Japan is a thermal efficiency of over 55% at an HPT inlet temperature of 1400°C as a combined plant. In order to attain this target, a feasibility study of the design and various R & D tasks have been conducted.

This paper will first present the basic plan and then some important R & D items.
Development of a High Pressure Dry Coal Feed System for a Two-Stage Slagging Gas Turbine Combustor
Authors: LeCren R. T. , White D. J.
Published: March 2015

Solar Turbines Incorporated, under the sponsorship of DOE-Morgantown Energy Technology Center has developed an advanced gas turbine coal-fired two-stage slagging combustor (TSSC). Rig test results using various coal-water mixtures have been reported previously (ASME 85-GT-206 and 85-JPGC/GT-17).

As part of the program it was required that the performance of the TSSC when operated with dry micronized coal be compared to that when burning coal water mixtures. As a prerequisite to this performance testing, a reliable high-pressure dry coal feed system had to be developed. A dense-phase feed and transport system was selected as the best compromise that satisfied the various needs. The system design development included the design and testing of a splitter system that divided the primary feed into four secondary flows. A number of problems were encountered and corrected during the testing. These problems, their solutions and the final system configurations are described. A comparison of the emissions using CWM and dry micronized coal is also presented. In general, NOx is higher and CO and UHC are lower on dry coal than on CWM because of the reduction of the reaction zone temperature by the water.
Feasibility Test of a Low Emissions Topping Combustor for Fluidized Bed Applications
Authors: Pillsbury Paul W. , Garland Richard V.
Published: March 2015

Combined cycles utilizing fluidized bed combustors, whether they be atmospheric or pressurized, are temperature limited. In order to capture sulfur effectively, bed operating temperature and, therefore, the gas turbine inlet temperature is limited to about 1600°F (1144 K) (Makanski and Schweiger, 1982) in atmospheric beds, and about 1700°F (1200 K) in pressurized beds as reported in DOE/METC/SP-185 (1980). In some applications, material limitations also come into play. While these systems show encouraging economics, they can be enhanced substantially by increasing the turbine inlet temperature. An atmospheric fluidized bed (AFB) example is discussed in this paper.

The addition of a topping combustor, thereby increasing the turbine inlet temperature in fluidized bed combined cycles, provides the means for increasing power output which enhances plant economics. Although emissions control and maintaining acceptable wall temperatures are achieved through the application of the multi-annular swirl burner, the design of such a combustor requires careful consideration of cooling and combustion because of the inherently higher cooling air and combustion air temperatures.
A Generalized Numerical Method for Solving Direct, Inverse and Hybrid Problems of Blade Cascade Flow by Using Streamline-Co-Ordinate Equation
Authors: Nai-Xing Chen , Feng-Xian Zhang
Published: March 2015

This paper describes a generalized numerical method for solving direct, inverse and hybrid aerodynamic problems of the blade cascade flow on the stream surface of revolution. The computational method is based on the numerical solution of the streamline-co-ordinate equation by a linear relaxation scheme. Two conventional blade cascades and a tandem blade have been calculated by the present method.
Analytical R&M Methods Applied to Forecasting Engine Logistics Requirements
Authors: Saunders D. E.
Published: March 2015

Spare parts shortages for engine programs in the late 1970’s, together with significant tightening of military spare parts budgets, prompted the development of a sophisticated forecasting system at General Electric Company, Aircraft Engine Business Group, Lynn, Massachusetts. GE’s system revolves around a generic simulation program containing the reliability, durability, maintainability and availability characteristics of an engine and its component parts in the data set. Subroutines of the program include the logic associated with particular types of maintenance policy such as on-condition maintenance, opportunistic maintenance, or scheduled part replacement.
Optimizing the Design Conditions of a 100 MWe CAES Plant With Salt Dome Air Storage
Authors: Karalis A. J. , Sosnowicz E. J. , Haselbacher H. , Istvan J.
Published: March 2015

A CAES plant consists of three (3) major systems; the turbomachinery train, the underground air storage chamber and the balance of plant. The turbomachinery train and the underground air storage chamber interrelationship needs to be optimized with respect to performance and cost while the balance of plant supports this relationship and is dependent upon the site conditions. The qualitative relationship between the air storage chamber and the operation of the turbomachinery train have been reported in the literature. This paper takes a salt dome geology and examines the factors affecting optimization of a 100 MWe CAES plant design.
Localization of Natural Modes of Vibration in Bladed Disks
Authors: Bendiksen O. O. , Valero N. A.
Published: March 2015

A study is presented of the mode localization phenomenon in imperfect blade-disk and blade-shroud-disk assemblies. This surprising phenomenon, first discovered in solid state physics, occurs in a number of periodic structures when the periodicity is broken by disorder or imperfections. Localization is signalled by the amplitude of a global blade-disk mode becoming confined to one or more local regions consisting of just a few blades, and could have serious implications for blade fatigue life. The results of this investigation indicate that unshrouded blades mounted on stiff disks are especially susceptible, and even small blade imperfections within manufacturing tolerances are likely to trigger mode localization. Increasing the interblade coupling by adding shrouds or reducing the disk stiffness greatly reduces the localization susceptibility, although certain modes may still become localized if the shrouds are free to slip.
Experimental Study on the Atomization of Plain Orifice Injector Under Uniform and Non-Uniform Cross Flowing Air Stream
Authors: Zhang Yan , Zhu Jun Yong , Wang Li Xin , Chin Ju Shan
Published: March 2015

The effects of three parameters: air velocity, nozzle pressure drop and injector orifice diameter, on the spray characteristics of a plain orifice injector under uniform and non-uniform cross flowing air stream have been studied experimentally. For uniform cross flowing air stream, the results show that the effects of these parameters are interrelated. The exponents of these terms in a correlation are not constants. Based on a very large amount of experimental data, the following correlation has been derived for Sauter Mean Diameter.

SMD = 8.28 • 10 4 V ¯ a A • Δ P ¯ f B • d ¯ C

where:

A = −1.59 −0.0044ΔP̄f −0.01 d̄

B = −0.13 −0.025 d̄ +0.34 Ma

C = 0.36 −0.55 Ma −0.0032ΔP̄f

(Va ≤ 140 M/s ; ΔPf ≤ 11 Kg·f/cm2 ; d ≤ 2.5 mm)

For small orifice diameters, the drop size distribution parameter, N (Rosin-Rammler distribution ), decreases until a minimum then increases with air velocity. For large orifice diameters, it decreases with air velocity. N always decreases with the increases of nozzle pressure drop or orifice diameter.

For non-uniform cross flowing air stream, atomizations under four velocity profiles with same averaged velocity and with a velocity recess of same shape but at different radial positions have been tested. The atomization data were compared with that of uniform cross flowing air stream. Two types of comparison were made based on: a) the undisturbed velocity, b) the averaged velocity, equals to the velocity of uniform cross flowing air stream. For former situation the atomization for non-uniform cross flowing air stream tested is always poorer. The influence from the velocity recess will be maximum at certain nozzle pressure drop.

The experimental evidence obtained has shown that cross flow atomization is a combination of pressure atomization (at low air flow velocity) and airblast atomization (at high air flow velocity).
New Materials for Fabricated Gas Turbine Hot Section Components
Authors: Rothman M. F. , Patriarca C. R.
Published: March 2015

Materials have been developed in recent years which are particularly well-suited for use in fabricated gas turbine hot section components. Among these are HAYNES® alloy No. 230 and HASTELLOY® alloy S. These alloys combine very good performance characteristics with capability for fabrication into such complex components as combustion chambers, afterburner flameholders, seal rings, and thermocouple/probe assemblies. The properties and fabrication characteristics of these two materials are reviewed and compared with other well-known gas turbine alloys.
Advanced Ultrasonic NDE Methods for Characterizing Porosity in SiC
Authors: Kunerth D. C. , Telschow K. L.
Published: March 2015

Ultrasonic techniques are being developed to detect and characterize porosity in advanced ceramic materials. The techniques use the acoustic backscatter resulting from the porosity or other anomalies and the ultrasonic signal timing and energy characteristics corresponding to propagation velocity and signal amplitude. Although all of the techniques are acoustic in nature, different signal processing algorithms provide different information about the porosity distribution. Four techniques are presented as well as experimental results from a sample of silicon carbide having a known porosity distribution. Information obtained from radiography and microscopic optical examination are compared with the ultrasonic results.
Failure Prediction of Hot-Pressed Si3N4 Ceramics by NDE
Authors: Singh J. P. , Roberts R. A. , Vaitekunas J. J. , Ellingson W. A.
Published: March 2015

Results are presented on the detection of critical flaws in hot-pressed Si3N4 with Fe inclusions by nondestructive evaluation (NDE) and fractographic observation. The NDE methods employed included (1) low-energy contact radiography with digital image enhancement and (2) through-transmission and backscatter ultrasonic imaging. A comparison of NDE and fractography results indicates that the backscatter ultrasonic method may be more suitable than low-kV contact radiography for the detection of near-surface flaws.
A New Time-Averaging Procedure for Compressible, Unsteady Turbulent Flows
Authors: Kreitmeier F.
Published: March 2015

The computations done at present for turbulent flow fields use either time-averaged (Reynolds) or time-and-mass-averaged (Favre) quantities, together with time-averaged fluctuating terms (FTs). Large numbers of these FTs, which are derived from the time-averaged balance equations, occur whenever all relevant time-averaged balance equations are being used and all quantities, including the transport quantities, must be considered as turbulent. The FTs require a great deal of experimental and theoretical work — for example, for closing time-averaged balance equations using familiar heuristic methods. For general simplification, then, a new averaging procedure is presented here which employs no arbitrary breakdown of the turbulent quantities, thus completely avoiding the FTs. This method is based on hypothetical reversible and irreversible equilibration processes on three control surfaces perpendicular to the major axes and in the control volume of a fluid element. The time-averaged balance equations take on the same manageable form as the instantaneous balance equations. In addition, the effort required for closing the time-averaged balance equations is reduced to a minimum.
Hybrid Catalytic Combustion for Stationary Gas Turbine: Concept and Small Scale Test Results
Authors: Furuya Tomiaki , Hayata Terunobu , Yamanaka Susumu , Koezuka Junji , Yoshine Toshiyuki , Ohkoshi Akio
Published: March 2015

Catalytic combustion for gas turbine applications has been investigated. Its significant advantages in reducing combustor emissions, particularly nitrogen oxides (NOx), have been shown. One of the main problems in regard to developing a catalytic combustor is the durability of catalysts, because the catalysts deteriorate during high temperature operation, which is normal for current gas turbines and near future gas turbines. The hybrid catalytic combustion concept has advantages concerned with catalyst durability. This paper shows its concept and small scale test results. This hybrid catalytic combustion concept comprises the following steps; premix fuel and air for a catalyst-packed zone; operate catalysts at rather low temperatures, to prolong catalyst life; add fresh fuel into the stream at the catalyst-packed zone outlet, where gas phase combustion occurs completely without a catalyst; add dilution air into the stream at the gas phase combustion zone outlet with a by-pass valve. Experimental data and analyses indicated that this hybrid catalytic combustion has a potential of being applicable to current gas turbines (turbine inlet temperature is about 1100°C) and near future gas turbines (turbine inlet temperature is about 1300°C).
Development and evaluation of a method of calibrating medical displays based on fixed adaptation
Authors: Sund Patrik , Månsson Lars Gunnar , Båth Magnus
Published: March 2015

Purpose:

The purpose of this work was to develop and evaluate a new method for calibration of medical displays that includes the effect of fixed adaptation and by using equipment and luminance levels typical for a modern radiology department.

Methods:

Low contrast sinusoidal test patterns were derived at nine luminance levels from 2 to 600 cd/m2 and used in a two alternative forced choice observer study, where the adaptation level was fixed at the logarithmic average of 35 cd/m2. The contrast sensitivity at each luminance level was derived by establishing a linear relationship between the ten pattern contrast levels used at every luminance level and a detectability index (d′) calculated from the fraction of correct responses. A Gaussian function was fitted to the data and normalized to the adaptation level. The corresponding equation was used in a display calibration method that included the grayscale standard display function (GSDF) but compensated for fixed adaptation. In the evaluation study, the contrast of circular objects with a fixed pixel contrast was displayed using both calibration methods and was rated on a five‐grade scale. Results were calculated using a visual grading characteristics method. Error estimations in both observer studies were derived using a bootstrap method.

Results:

The contrast sensitivities for the darkest and brightest patterns compared to the contrast sensitivity at the adaptation luminance were 37% and 56%, respectively. The obtained Gaussian fit corresponded well with similar studies. The evaluation study showed a higher degree of equally distributed contrast throughout the luminance range with the calibration method compensated for fixed adaptation than for the GSDF. The two lowest scores for the GSDF were obtained for the darkest and brightest patterns. These scores were significantly lower than the lowest score obtained for the compensated GSDF. For the GSDF, the scores for all luminance levels were statistically separated from the average value; three were lower and two were higher. For the compensated GSDF, three of the scores could not be separated from the average value.

Conclusions:

An observer study using clinically relevant displays and luminance settings has demonstrated that the calibration of displays according to the GSDF causes the perceived contrast to be unevenly distributed when using displays with a high luminance range. As the luminance range increases, the perceived contrast in the dark and bright regions will be significantly lower than the perceived contrast in the middle of the luminance range. A new calibration method that includes the effect of fixed adaptation was developed and evaluated in an observer study and was found to distribute the contrast of the display more evenly throughout the grayscale than the GSDF.
Predicting adenocarcinoma recurrence using computational texture models of nodule components in lung CT
Authors: Depeursinge Adrien , Yanagawa Masahiro , Leung Ann N. , Rubin Daniel L.
Published: March 2015

Purpose:

To investigate the importance of presurgical computed tomography (CT) intensity and texture information from ground‐glass opacities (GGO) and solid nodule components for the prediction of adenocarcinoma recurrence.

Methods:

For this study, 101 patients with surgically resected stage I adenocarcinoma were selected. During the follow‐up period, 17 patients had disease recurrence with six associated cancer‐related deaths. GGO and solid tumor components were delineated on presurgical CT scans by a radiologist. Computational texture models of GGO and solid regions were built using linear combinations of steerable Riesz wavelets learned with linear support vector machines (SVMs). Unlike other traditional texture attributes, the proposed texture models are designed to encode local image scales and directions that are specific to GGO and solid tissue. The responses of the locally steered models were used as texture attributes and compared to the responses of unaligned Riesz wavelets. The texture attributes were combined with CT intensities to predict tumor recurrence and patient hazard according to disease‐free survival (DFS) time. Two families of predictive models were compared: LASSO and SVMs, and their survival counterparts: Cox‐LASSO and survival SVMs.

Results:

The best‐performing predictive model of patient hazard was associated with a concordance index (C‐index) of 0.81 ± 0.02 and was based on the combination of the steered models and CT intensities with survival SVMs. The same feature group and the LASSO model yielded the highest area under the receiver operating characteristic curve (AUC) of 0.8 ± 0.01 for predicting tumor recurrence, although no statistically significant difference was found when compared to using intensity features solely. For all models, the performance was found to be significantly higher when image attributes were based on the solid components solely versus using the entire tumors (p < 3.08 × 10−5).

Conclusions:

This study constitutes a novel perspective on how to interpret imaging information from CT examinations by suggesting that most of the information related to adenocarcinoma aggressiveness is related to the intensity and morphological properties of solid components of the tumor. The prediction of adenocarcinoma relapse was found to have low specificity but very high sensitivity. Our results could be useful in clinical practice to identify patients for which no recurrence is expected with a very high confidence using a presurgical CT scan only. It also provided an accurate estimation of the risk of recurrence after a given duration t from surgical resection (i.e., C‐index = 0.81 ± 0.02).
The Effect of Exertion on Joint Kinematics and Kinetics During Running Using a Waveform Analysis Approach
Authors: Benson Lauren C. , O’Connor Kristian M.
Published: April 2015

About half of all runners sustain a running-related injury every year. Exertion may contribute to risk of injury by altering joint mechanics. The purpose of this study was to examine the effects of exertion on runners’ joint mechanics using principal component analysis (PCA). Three-dimensional motion analysis of the lower extremity was performed on 16 healthy female runners before and after their typical training run. PCA was used to determine exertion-related changes in joint mechanics at the ankle, knee, and hip. Statistical significance for repeated-measures MANOVA of the retained principal components at each joint and plane of motion was at P < .05. Exercise effects were identified at the ankle (greater rate of eversion [PC2: P = .027], and decreased plantar flexion moment [overall: P = .044] and external rotation moment [PC3: P = .003]), knee (increased adduction [overall: P = .044] and internal rotation [PC3: P = .034], and decreased abduction moment [overall: P = .045]), and hip (increased internal rotation [PC1: P = .013] and range of mid- to late-stance rotation [PC2: P = .009], and decreased internal rotation moment [PC1: P = .001]). The observed changes in running mechanics reflect a gait profile that is often linked to running injury. The effects of more strenuous activity may result in mechanics that present an even greater risk for injury.