bluuebunny/crossref_metadata_2025_split huggingface dataset:
A New Analytical Model for Interpreting the Wear Mechanisms of Abradable Seal Systems and Verification by Testing
Authors: Soehngen J. 
Published: March 2015

In order to minimize the specific fuel consumption of gas turbines it is necessary to increase the gas temperatures and pressure ratios. Therefore, new high-temperature resistant abradable seal systems must be developed, especially for the hot section. Since the required operating temperatures are above 1050°C, the use of metallic materials as abradables is out of the question. A problem commonly encountered in the selection of new (ceramic) materials for seal systems is that of insufficient knowledge of the tribological process occurring when turbine blades rub against an abradable seal.
The purpose of the investigation was to find a simplified analytical model to describe the tribological process occurring in the rubbing of the blades against the seal, in order to help in the preselection of materials for abradable seals. The model was verified by testing high-temperature resistant abradable seals under simulated engine conditions, followed by metallurgical examination. The results of the examination of two abradable seals on run engine components confirmed the analytical prediction and laboratory tests.
The differences in material loss from the blade and the abradable seal can be correlated to the heat flux distribution in the sliding parts. Using different materials on the blade tip and stationary seal (e.g. ceramic blade tip and ceramic or metallic abradable seal), the heat flux can be directed in such a way that the wear takes place largely on the static part of the engine. By calculating their relative abradability, material combinations with optimum performance for each seal application can be found.
The Properties and Characteristics of Electroless Nickel Coatings Applied to Gas Turbine Engine Components
Authors: Bleeks Thomas W. , Brindisi Frank 
Published: March 2015

The improvement of reliability and reduction of overhaul time is of paramount importance to engineers involved with coatings used on gas turbine engine components. Aluminum/phosphate/chromate coatings are currently used in industrial and aircraft gas turbine engines for coating compressor components. Traditional electrolytic nickel with diffused cadmium coatings are also used but to a lesser extent. Field experience, however, has shown limitations with both coating systems, particularly in the areas of erosion, wear, and simplicity in component processability.
Currently, several new electroless nickel coatings are gaining significant acceptance in the industry, both for overhaul and repair, as well as for new part manufacture. This paper presents erosion, corrosion, fatigue and stress data on these coatings. Some field experience is also presented from airline operators and overhaul facilities who are incorporating these coatings on aircraft gas turbine engine components. Information is also given on the capability of electroless nickel coatings to reduce manufacturing cost and simplify the processing of complex parts.
Feasibility Study on Honeycomb Ceramics for Catalytic Combustor
Authors: Kawakami Takashi , Furuya Tomiaki , Sasaki Yukio , Yoshine Toshiyuki , Furuse Yutaka , Hoshino Mitsunobu 
Published: March 2015

This paper contains results of a structural feasibility study on honeycomb ceramic materials used for catalytic combustors in power gas turbines. Extruded cordierite honeycomb substrates are widely used as catalyst carriers in automotive exhaust systems, because of their excellent thermal shock resistance. For gas turbines, however, the ceramic catalyst carriers should retain the reliability at high temperature.
In a hybrid catalytic combustor, which handles both catalysis and gas phases combustion, cordierite honeycomb structures (melt at 1445°C) can be adopted as the catalyst carrier, because the auxiliary gas phase combustion makes catalyst temperature lower than the conventional catalytic combustor.
During this study, cordierite honeycomb (200 square cells/in2) tensile tests were carried out at high temperatures up to 1000°C. Using the finite element method, stresses in a cell wall were analyzed. The honeycomb cell wall mechanical strength was derived by comparing the experimental and analytical results. Also, combustor honeycomb cell stresses were calculated under typical oprerating conditions. Consequently, it was shown that it is sufficiently feasible to use the cordierite honeycomb structure as a catalyst carrier for hybrid catalytic combustors.
Application of Recess Vaned Casing Treatment to Axial Flow Fans
Authors: Azimian A. R. , Elder R. L. , McKenzie A. B. 
Published: March 2015

The effect of applying a vaned recessed casing treatment to a single stage axial flow fan has been investigated. The influence of the axial position of the recess relative to the rotor leading edge and other geometrical modifications of the vane passage have been examined. Significant improvements in stall margin were observed without (in some builds) loss in peak efficiency.
Slow and fast frequency response yawmeter probes have been used in the study to examine both the steady flow conditions and the unsteady flow caused by rotating stall.
An Approximate 3-D Aerodynamic Design Method for Centrifugal Impeller Blades
Authors: Xiaolu Zhao , Lisen Qin 
Published: March 2015

An aerodynamic design method, which based on the Mean Stream Surface Method (MSSM), has been developed in designing the centrifugal compressor impeller blades. As a component of a CAD system for centrifugal compressor, it is convenient to use the presented method for generating impeller blade geometry, taking care of manufacturing as well as aerodynamic aspects.
The design procedure starts with an S2m indirect solution. Afterwards from the specified S2m surface, by the use of Taylor series expansion, the blade geometry is generated by straight-line elements to meet the requirement of manufacture. Simultaneously, the fluid dynamic quantities across the blade passage, can be determined directly. In terms of these results, the designer can revise the distribution of angular momentum along the shroud and hub, which are associated with blade loading to get satisfactory velocities along the blade surfaces in order to avoid or delay flow separation.
Incremental Fuel Cost Prediction for a Gas Turbine Combined Cycle Utility
Authors: Little D. , Nikkels H. , Smithson P. 
Published: March 2015

For a medium sized (300 MW) utility producing electricity from a 130 MW combined cycle, and supplemental 15 MW to 77 MW capacity simple cycle gas turbines, the incremental fuel costs accompanying changes in generating capacity vary considerably with unit, health, load level, and ambient. To enable incremental power to be sold to neighbouring utilities on an incremental fuel cost basis, accurate models of all gas turbines and the combined cycle were developed which would allow a realistic calculation of fuel consumption under all operating conditions. The fuel cost prediction program is in two parts; in the first part, gas turbine health is diagnosed from measured parameters; in the second part, fuel consumption is calculated from compressor and turbine health, ambient conditions and power levels.
The paper describes the program philosophy, development, and initial operating experience.
Expanding Expertise With State-of-the-Art Monitoring
Authors: Gramatikas George F. , Davis Daniel L. 
Published: March 2015

This paper describes a program that groups gas turbines from one or more sites for the purpose of efficient monitoring and performance evaluation. Cost-improved gas turbine and power plant operation is achieved by a new, unified-yet-flexible service approach which combines state-of-the-art microprocessor-based monitoring with routine and emergency evaluation by a core of highly skilled personnel many miles from the operating site.
This unique approach delivers expertise which supplements the gas turbine owner’s in-house resources. It is based on a modular concept of condition health monitoring and performance evaluation, including scheduled as well as on-line services. Portable condition health monitoring equipment provides the capability for scheduled plant performance evaluation by service engineers without investment in additional equipment. On-line monitoring includes a PC-based software system and a computer link to the service engineer’s headquarters. Both scheduled and on-line monitoring services include trend evaluation, projected maintenance requirements, maintenance planning assistance and suggestions for performance enhancement.
Effect of Rib-Angle Orientation on Local Mass Transfer Distribution in a Three-Pass Rib-Roughened Channel
Authors: Han J. C. , Zhang P. 
Published: March 2015

In this experimental investigation of the heat transfer characteristics of turbulent air flow in a three-pass square channel, the test section consisted of three straight square channels jointed by two 180° turns, modeling the internal cooling passages of gas turbine airfoils. Naphthalene-coated ribs were attached to the top and the bottom walls of the naphthalene-coated, three-pass channel. The rib height-to-hydraulic diameter ratio was 0.063; the rib pitch-to-height ratio was 10; the rib angles were 90° and 60°. For α = 60°, both the crossed ribs (on two opposite walls of the cooling channel) and the parallel ribs (on two opposite walls of the cooling channel) were investigated. The combined effects of the two sharp 180° turns and the rib orientations on the distributions of the local mass transfer coefficient in the entire three-pass channel were determined.
The rib angle, the rib orientation, and the sharp 180° turn significantly affect the local mass transfer distributions. The combined effects of these parameters can increase or decrease the mass transfer coefficients after the sharp 180° turns. The angled ribs, in general, provide higher mass transfer coefficients than the transverse ribs; the parallel ribs give higher mass transfer than the crossed ribs.
Three-Dimensional Rotational Flow in Transonic Turbomachines: Part II — Full 3D Flow in CAS Rotor Obtained by Using a Number of S1 and S2 Stream Filaments
Authors: Chung-Hua Wu , Xiaolu Zhao , Lisen Qin 
Published: March 2015

The general theory for three–dimensional flow in subsonic and supersonic turbomachines has recently been extended to transonic turbomachines. In Part II of the paper, quasi– and full three–dimensional solutions of the transonic flow in the CAS rotor are presented. The solutions are obtained by iterative calculation between a number of S1 stream filaments and, respectively, a central S2 stream filament and a number of S2m stream filaments. Relatively simple methods developed recently for solving the transonic flow along S1 and S2 stream filaments are used in the calculation.
The three–dimensional flow fields in the CAS rotor obtained by the present method are presented in detail with special emphasis on the converging process for the configuration of the S1 and S2 stream filaments. The three–dimensional flow fields obtained in the quasi– and full 3D solutions are quite similar, but the former gives a lower peak Mach number and a smaller circumferential variation in Mach number than the latter. A comparison between the theoretical solution and the Laser–2–Focus measurement shows that the character of the transonic flow including the 3D shock structure is in good agreement, but the measured velocity is slightly higher than the calculated one over most of the flow field.
Status of Topping Combustor Development for Second Generation Fluidized Bed Combined Cycles
Authors: Garland Richard V. , Pillsbury Paul W. 
Published: March 2015

Addition of a fluidized bed combustor to a high efficiency combined cycle plant enables direct firing of inexpensive run-of-the-mine coal in an environmentally acceptable manner. To attain high thermal efficiencies, coal pyrolysis is included. The low heating value fuel gas from the pyrolizer is burned in a topping combustion system that boosts gas turbine inlet temperature to state of the art while the pyrolizer-produced char is burned in the bed.
The candidate topping combustor, the multi-annular swirl burner, based on a design by J. M. Beér is presented and discussed. Design requirements differ from conventional gas turbine combustors. The use of hot, vitiated air for cooling and combustion, and the use of low heating value fuel containing ammonia are two factors that make the design requirements unique.
The multi-annular swirl burner contains rich-burn, quick-quench, and lean-burn zones formed aerodynamically rather than the physically separate volumes found in other rich-lean combustors.
Although fuel is injected through a centrally located nozzle, the combustion air enters axially through a series of swirlers. Wall temperatures are controlled by relatively thick layers of air entering through the various swirler sections, which allows the combustor to be of all-metal construction rather than the ceramic often used in rich-lean concepts.
This 12-inch diameter design utilizes some of the features of the previous 5-inch and 10-inch versions of the multi-annular swirl burner; and, test results from the previous projects were utilized in the formulation of the test for the present program. In the upcoming tests, vitiated air will be provided to simulate a pressurized fluidized bed effluent. Hot syngas seeded with ammonia will be used to simulate the low BTU gas produced in the pyrolizer.
The Influence of Blade Lean on Turbine Losses
Authors: Harrison S. 
Published: March 2015

Three linear cascades of highly loaded, low aspect ratio turbine blades have been tested in order to investigate the mechanisms by which blade lean (dihedral) influences loss generation. The blades in all three cascades have the same section but they are stacked perpendicular to the endwall in the first cascade, on a straight line inclined at 20° from perpendicular in the second and on a circular arc inclined at 30° from perpendicular at each end in the third cascade.
Lean has a marked effect upon blade loading, on the distribution of loss generation and on the state of boundary layers on the blade suction surfaces and the endwalls, but its effect upon overall loss coefficient was found to be minimal. It was found, however, that compound lean reduced the downstream mixing losses, and reasons for this are proposed. Compound lean also has the beneficial effect of substantially reducing spanwise variations of mean exit flow angle. In a turbine this would be likely to reduce losses in the downstream bladerow as well as making matching easier and improving off-design performance.
Recent Test Results in the Direct Coal-Fired 80 MW Combustion Turbine Program
Authors: Bannister R. L. , Pillsbury P. W. , Diehl R. C. , Loftus P. J. 
Published: March 2015

Under sponsorship of the Morgantown Energy Technology Center of the Department of Energy, the Westinghouse Electric Corporation and Avco Research Laboratory/Textron (ARL) are developing a direct coal-fired 80-MW combustion turbine. This is to be an element in a 207-MW direct coal-fired combustion turbine combined cycle, comprising another combustion turbine, a heat-recovery steam generator, and a steam turbine. Following conceptual and economic studies, the first experimental task has been to develop a direct coal-fired slagging combustor in small scale. A year’s testing with this unit has now been accomplished. It is thus possible to discuss experimental results in the areas of slag management, general combustor operability, coal fuel feed, heat loss, pressure loss, combustion efficiency, and emissions.
Westinghouse and ARL selected the slagging combustor for use in this program because of its unique ability to accept inexpensive standard utility-type coal without sending excessive pollutants and particulates to the expander-turbine. It accomplishes this by burning the coal at a temperature high enough to melt the ash, and then removing the molten slag with an impact separator. This combustor is also of the rich-lean type, which allows it to emit very low levels of NOx. Sulfur oxides are controlled through injection of a sorbent which combines with gaseous forms of sulfur in the rich zone, and then takes them out with the slag.
The plan in this program is to develop the slagging combustor in small scale at 12 million Btu/h (12.66 million kJ/h) heat input, 6 atmospheres pressure, and then move to design and verification testing of a full-scale 70 million Btu/h (73.85 million kJ/h), 14-atmosphere unit. It is with the smaller burner that this paper is concerned. During this period, coals have been fed into the 6-atm combustor exclusively in the dry-pulverized form with air as the carrier gas. To date, high- and low-sulfur eastern bituminous, and low-sulfur western subbituminous coals have been evaluated, with, and without sorbents, which have included various calcium and iron containing minerals. Coal samples have been of the 200 mesh size, and have not been beneficiated.
Combustor operation has been efficient and repeatable and slag flow has been symmetrical and manageable. Slag removal has been greater than 90 percent and carbon burnout has been greater than 99 percent. Nitrogen oxide emissions meet the goals of EPA’s NSPS for coal-fired plants. Current tests are focused on the goal of 90 percent sulfur removal. Although some results are available, various sorbents and injection techniques continue under test.
Development of a New 25MW High Efficiency Heavy-Duty Gas Turbine H-25
Authors: Urushidani Haruo , Sasada Tetsuo , Wada Masamichi , Kawaike Kazuhiko 
Published: March 2015

A new 25MW class gas turbine H-25 has been developed to meet both 50 Hz and 60 Hz power generation needs with high reliability and efficient performance utilizing advanced high temperature gas turbine technologies. Because of its superior performance, over 32% in simple cycle efficiency, the H-25 gas turbine enables significant reduction of fuel consumption compared with previous 25MH class turbines. The H-25 also achieves higher thermal efficiency in a combined cycle power plant and a cogeneration plant with a waste heat recovery boiler. The first unit entered commercial operation at the end of November 1988 after full load factory test instrumented with more than 800 pieces of instrumentation.
This paper describes the design features and the latest technological refinements in each component of the H-25 gas turbine. Also presented are the component test programs and the results of full load factory test and field test on the first unit.
Parametric Experiments on Coaxial Airblast Jet Atomization
Authors: Farago Zoltan , Chigier Norman 
Published: March 2015

Experiments using high speed, high magnification, and high contrast photography on airblast coaxial atomizers were carried out to study the wave characteristics of liquid surfaces, ligament breakup, and droplet formation. Liquid flow rate was changed from 4 to 50 kg/h, corresponding to a velocity range of 1.5 to 18 m/s, and a Reynolds number range of 1400 to 18000. Air flow rate was varied from 8 to 70 kg/h, corresponding to a velocity range of 22 to 180 m/s, and a Reynolds number range of 13000 to 105000. Tube wall thicknesses of 145 and 320 microns were used.
Under different flow conditions, different jet instabilities (capillary, helical and Kelvin-Helmholtz) and different dominant mechanisms of ligament formation were observed. One of the most surprising experimental results is that, under certain flow conditions, the coaxial round liquid jet, surrounded by an axisymmetric annular air stream, forms a flat curling liquid sheet. This liquid sheet breaks into droplet clouds with a frequency of a few thousand Hertz and emits strong oscillations and fluctuating, highly non-axisymmetric vibrations.
An Analysis of Pressure Swirl and Pure Airblast Atomization
Authors: Mao Chien-Pei , Chuech S. G. , Przekwas A. J. 
Published: March 2015

The present investigation examines the fundamental aspects of airblast atomization in both the breakup and drop dispersion regimes. Experiments were conducted using a high-magnification 4×5 camera and a Phase/Doppler particle analyzer to evaluate the spray characteristics and atomizer performance. The primary parameters of interest are: liquid film breakup length, spray angle, drop size and trajectory. Observation of wave formation and propagation along the sheet surface was made to provide guidance in formulating mathematical models. Effects of air flow and nozzle design on atomization were examined for a wide range of flow conditions.
Computational analysis was also utilized to predict the sheet breakup and subsequent drop behavior. This model considered a swirling sheet interacting with the surrounding air streams. The governing equations were formulated in a curvilinear coordinate system conforming to the film boundaries. Primary breakup is based upon linear stability analysis. The present model is capable of predicting the variations in thickness, trajectory, velocity, and angle of a liquid film as a function of nozzle geometry, operating conditions, fluid properties, and ambient conditions. Secondary breakup and drop history calculations were also included in the model to provide local drop size spectra.
Agreement between the experimental and predicted breakup length and angle was excellent. The predictions of drop size, trajectory and other parameters were qualitatively correct. The present investigation demonstrated a realistic approach for simulating the breakup process and described the physical structure of a pure airblast atomizer spray.
Integrity Assessments of Components in the Creep Range
Authors: Penny R. K. , Weber M. A. 
Published: March 2015

Robust methods for the predictions of deformations and lifetimes of components operating in the creep range are presented. The ingredients used for this are well-tried numerical techniques, combined with the concepts of continuum damage and so-called reference stresses. The methods described are derived in order to obtain the maximum benefit during the early stages of design where broad assessments of the influences of material choice, loadings and geometry need to be made quickly and with economical use of computers. It is also intended that the same methods will be of value during operation if estimates of damage or if exercises in life extension are required.
Results of the suggested method are amenable to tabular or graphical representation and to illustrate the use of these in parametric studies, three brief case studies are included. These involve a notched rod, a perforated plate, and a pipe for which life time estimates based upon failure criteria involving different degrees of conservatism are calculated. In addition, an illustration is given of the use of the charts presented in deciding inspection intervals and lifetime extensions. Finally, a brief excursion into the possibility for using the suggested methods for the mapping of designs within given regional constraints is given.
Flexibility and Adaptability of Closed Brayton Cycles Associated With Low Power Level Space Nuclear Heat Sources
Authors: Tilliette Z. P. , Carre F. O. , Proust E. 
Published: March 2015

A feature of the French preliminary studies of space nuclear power systems of about 20 kwe is the selection of the closed Brayton cycle as the conversion subsystem.
As examples of future applications of turbogenerators in space, near or longer term U.S. and Soviet projects are mentioned, including technical advances expected in this field.
Several nuclear reactors concepts can be proposed now or in the future. The need for a satisfactory adaptation between the heat source and the converter prompts to further investigate the Brayton cycle capability for that purpose. For instance, a long lifetime thermal spectrum reactor would require a relatively low inlet temperature for moderator thermal conditioning. Cycle configurations featuring one or two separate radiators and possible intercooling are presented. Such arrangements imply a main low temperature radiator made, for instance, of multiple, pivoting tubes.
It is shown that the Brayton cycle can offer flexibility and adaptability for a wide range of space missions.