bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of Advanced Combustors for Dry NOx Suppression With Nitrogen Bearing Fuels in Utility and Industrial Gas Turbines
Authors: Cutrone M. B. , Hilt M. B. , Goyal A. , Ekstedt E. E. , Notardonato J.
Published: October 2009

The work described in this paper is part of the DOE/LeRC Advanced Conversion-Technology Project (ACT). The program is a multiple contract effort with funding provided by the Department of Energy, and technical program management provided by NASA LeRC. Combustion tests are in progress to evaluate the potential of seven advanced combustor concepts for achieving low NOx emissions for utility gas turbine engines without the use of water injection. Emphasis was on the development of the required combustor aerothermodynamic features for burning high nitrogen fuels. Testing was conducted over a wide range of operating conditions for a 12:1 pressure ratio heavy-duty gas turbine. Combustors were evaluated with distillate fuel, SRC-II coal-derived fuel, residual fuel, and blends. Test results indicate that low levels of NOx and fuel-bound nitrogen conversion can be achieved with rich-lean combustors for fuels with high fuel-bound nitrogen. In addition, ultra-low levels of NOx can be achieved with lean-lean combustors for fuels with low fuel-bound nitrogen.
The Influence of Unsteady Rotor Response on a Distorted Flow Field
Authors: Henderson R. E. , Shen I. C.
Published: October 2009

The influence of the unsteady rotor response on the shape of stagnation pressure and axial velocity distortions passing through an axial flow rotor are investigated. Experimental data obtained with an isolated rotor in an incompressible, distorted inflow demonstrate that the magnitude of the distortion downstream of the rotor is a strong function of the ratio of the blade spacing s to the distortion wavelength ln. An existing actuator disk analysis based on a quasi-steady model of the rotor response and used extensively to predict the downstream distortion, has been extended to include the unsteady response of the rotor. By examining a series of sinusoidal distortions of varying wavelength, a semi-actuator disk analysis, which includes the unsteady rotor response, is shown to predict the same trend with s/ln as exhibited by the experimental data.
Three-Dimensional Flow Field in the Tip Region of a Compressor Rotor Passage—Part I: Mean Velocity Profiles and Annulus Wall Boundary Layer
Authors: Lakshminarayana B. , Pouagare M. , Davino R.
Published: October 2009

The flow field in the annulus wall and tip region of a compressor rotor was measured using a triaxial, hot-wire probe rotating with the rotor. The flow was surveyed across the entire passage at five axial locations (leading edge, 1/4 chord, 1/2 chord, 3/4 chord, and trailing edge locations) and at six radial locations inside the passage. The data derived include all three components of mean velocity. Blade-to-blade variations of the velocity components, pitch and yaw angles, as well as the passage-averaged mean properties of the annulus wall boundary layer, are derived from this data. The measurements indicate that the leakage flow starts beyond a quarter-chord and tends to roll up farther away from the suction surface than that observed in cascades. Substantial velocity deficiencies and radial inward velocities are observed in this region. The annulus wall boundary layer is well behaved up to half a chord, beyond which interactions with the leakage flow produce complex profiles.
Flame Blowoff Studies Using Large-Scale Flameholders
Authors: Rao K. V. L. , Lefebvre A. H.
Published: October 2009

Experimental and theoretical studies are made of the factors governing the blowoff velocities of stabilized flames supplied with flowing gaseous combustible mixtures. The test program includes wide variations in effective pressure, obtained using the water injection technique, and also covers wide ranges of velocity, flameholder size, and flameholder blockage. An equation is derived for predicting blowoff velocities which shows good agreement with the experimental data.
Two-Phase Transpiration Cooling
Authors: El-Masri M. A.
Published: October 2009

Two-phase transpiration is shown to possess considerable potential for gas turbine cooling. In this concept, water fed into a porous component boils within the wall. The resulting steam issues from the hot surface forming the transpiration film. A model for the performance of such a system is developed. Assuming constant properties and a linear reduction of Stanton number with transpiration rate, closed-form solutions are obtained. The governing dimensionless parameters are identified, the system behavior predicted, and the modes of operation delineated. Those are defined as two-phase, partially-flooded, and completely-flooded modes. At low values of a certain “modified Peclet number,” the two-phase mode is unstable and the system tends to flood. Large values of this parameter indicate stable, well-regulated behavior. Discussions on gas turbine applications are presented. A typical numerical example is given in the Appendix.
Performance Analysis of the Test Results on a Two-Stage Transonic Fan
Authors: Chen Baoshi , Zhang Tianyi
Published: October 2009

Test results obtained from a two-stage fan are analysed and the reasons that caused the design performance target not to be attained are presented in this paper. Addition of a partspan shroud on rotor 1 caused higher losses and changed radial distribution of parameters. Modification on the flowpath and chord length of stator 1 resulted in excessively high inlet Mach number and flow separation in the hub region. The high load and high incidence at the hub of rotor 2 caused higher losses and reduced stall margin of the fan.
A Mixed-Flow Cascade Passage Design Procedure Based on a Power Series Expansion
Authors: Novak R. A. , Haymann-Haber G.
Published: October 2009

Flow passage design and analysis procedures employing a TAYLOR series expansion across the flow field were first suggested as far back as 1908. With very few exceptions the early work addressed only the problem of symmetrical convergent-divergent passages. A generalization and an extension of the approach permits it to be used for the design of arbitrary cascade passages in subsonic, supersonic, or mixed-flow regimes. The method will give fast, realistic solutions in situations where shock-free flow is meaningful, and where the cascade gap-chord ratio is not excessive. It assumes inviscid, irrotational flow and employs a fourth-order TAYLOR series expansion across the cascade passage. Numerous examples are given, with comparisons with experimental data and other analytic solutions.
Ceramic Tube Heat Exchanger Technology Development for Indirect-Fired Gas Turbine Cycle
Authors: Ward M. E. , Metcalfe A. G. , Dapkunas S. J.
Published: October 2009

Technology for pressurized, high-temperature, ceramic-tube heat exchangers is being established by materials evaluation, design, and fabrication studies followed by rig tests. Candidate ceramic materials have been surveyed for strength, environmental reactions with coal ash, and other design properties. Design and fabrication studies of joining methods were responsible for selection of the chosen heat exchanger configuration. A full-length, twenty eight-tube, 4.56 m (15 ft), ceramic-tube heat exchanger with an 11.43-cm (4.5 in.)-dia ceramic header has been successfully tested with a 1232°C (2250°F) outlet temperature at 689 kPa (100 psi). Hot side gas temperature during this test was 1370°C (2500°F). This module has been operated for approximately 125 hrs including operation with a pulverized coal combustor.
Manufacturing Methods for Erosion-Resistant Ceramic Nozzles for Small Gas Turbines
Authors: Arnold J. P. , McGovern W. , Russell A. D. , Napier J. C.
Published: October 2009

Ceramic vanes significantly improve erosion resistance of small gas turbines. Methods of economically manufacturing ceramic vanes and associated metal shrouds were developed. Nozzle performance was verified for corrosion, thermal shock, and erosion. Detailed cost studies have shown a ceramic vane nozzle can be built for 150 percent of the cost of a metal vane nozzle. Production tooling has been ordered and engine qualification is planned.
In-Plane Inertial Coupling in Tuned and Severely Mistuned Bladed Disks
Authors: Crawley E. F.
Published: October 2009

A model has been developed and verified for blade-disk-shaft coupling in rotors due to the in-plane rigid body modes of the disk. An analytic model has been derived which couples the in-plane rigid body modes of the disk on an elastic shaft with the blade bending modes. Bench resonance tests were carried out on the MIT Compressor Rotor, typical of research rotors with flexible blades and a thick rigid disk. When the rotor was carefully tuned, the structural coupling of the blades by the disks was confined to zero and one nodal diameter modes, whose modal frequencies were greater than the blade cantilever frequency. In the case of the tuned rotor, and in two cases where severe mistuning was intentionally introduced, agreement between the predicted and observed natural frequencies is excellent.
The Effect of Temperature Ratios on the Film Cooling Process
Authors: Loftus P. J. , Jones T. V.
Published: October 2009

Film cooling experiments have been conducted at conditions which realistically simulate the gas turbine environment. Heat transfer has been measured using a short duration wind tunnel. Mainstream injection and wall temperatures have been varied independently in order to conduct a systematic investigation of the injection process. A model of the film cooling process based on the principle of superposition is used to interpret the experimental results. The effect of gas to wall temperature ratio on heat transfer to an uncooled plate has also been investigated.
Chemical Neutralization to Control Denting in Nuclear Steam Generators
Authors: Beineke T. A. , Hall J. F. , Marugg K. E. , Scott D. B. , Orsulak R. M. , Grondahl E. E. , Silva E. J. , Fink G. C.
Published: October 2009

Laboratory testing at Combustion Engineering has indicated promise in controlling simulated steam generator tube denting through chemical neutralization. Testing was limited to on-line treatment, and two neutralizers have been evaluated: (i) calcium hydroxide, and (ii) boric acid. On-line treatment with calcium hydroxide successfully halted active denting whenever the bulk calcium concentration (in ppm) equaled or exceeded the bulk chloride concentration (in ppm). Calcium hydroxide also was effective as an alternative to ammonia as a pH controlling agent in two tests conducted without ingress of chloride. On-line treatment with boric acid consisted of a four-day soak at simulated low (approximately 30 percent) power with 50 ppm B followed by one month full-power operation with 10 ppm B. This treatment also halted denting. Nondestructive and destructive examination of test boilers gave no indication of adverse side effects associated with either neutralizer.
Modeling Considerations for the Analysis of LMFBR Steam Generator Tube Clamps
Authors: Lay D. M. , Piper R. M.
Published: October 2009

In the design of the Babcock & Wilcox Helical Coil Liquid Metal Fast Breeder Reactor (LMFBR) Steam Generator, the tube bundle is connected to the feedwater and steam plenums via “inlet/outlet tubes”. Of prime importance in the design of these tubes is the tube-to-tube and tube-to-shell clamps which are provided to prevent detrimental vibration. This paper presents a method of modeling the tube-to-tube clamps to accurately predict tube-to-clamp interaction in the finite element analysis. It is also the objective of this paper to demonstrate the validity of specific modeling assumptions in determining stresses in the clamp assembly. As this paper deals only with the analytical approach taken, no detailed results are presented.
Twenty-Five Years of Operating Experience With the Coal-Fired, Closed-Cycle Gas Turbine Cogeneration Plant at Coburg
Authors: Bammert K.
Published: October 2009

The only commercially running closed-cycle gas turbine in the world delivering electricity as well as heat to a public utility and a heating network, is the heat and power station in Coburg, West Germany. The plant is fired exclusively with pulverized coal and uses air as the working medium. It has a maximum continuous electric power output of 6.6 MW into the grid and up to 16 MW of direct heating capacity into the town’s heating network. The plant has accumulated 150,000 operating hours to date (approximately 7000 hrs per year); it is scheduled to remain in service during the following years due to its excellent performance. Since relatively little has been published about the plant in the technical literature, a report about its design and operating experience is presented here.
Simulation of Centrifugal Compressor Transient Performance for Process Plant Applications
Authors: Macdougal I. , Elder R. L.
Published: October 2009

The development of a theoretical model capable of simulating centrifugal compressor transient performance (including compressor surge) is detailed. Simulation results from a Fortran computer program are compared with measured compressor transient data. Good simulation of compressor transients between stable operating points, and compressor presurge flow oscillations has been obtained. General application criteria are presented for the geometric distribution of model elements within a compressor system. Model applications and future work are outlined.
Augmented Vectored Thrust Engines and the Problem of Avoiding Hot Gas Recirculation
Authors: Lewis W. J. , Hurd R.
Published: October 2009

It can be argued that the vectored thrust engine is one of the best propulsion systems for V/STOL combat aircraft. The next step is to consider the problems to be overcome in integrating such a powerplant into the airframe. A critical installation issue, and one which is not unique to vectored thrust systems, is that of hot exhaust gas recirculation. In this paper some of Rolls-Royce’s hot gas recirculation experience is described, covering, in particular, the creation of a specialized recirculation test facility and some sample test results. The application of the results to a vectored thrust installation is discussed, together with some of the implications for the aircraft designer. Finally, some comments are made regarding the requirements of other V/STOL propulsion systems to avoid excessive hot gas recirculation.
Fractography of Reaction-Sintered Si3N4
Authors: Mendiratta M. G. , Land P. L. , Ruh R. , Rice R. W. , Larsen D. C.
Published: October 2009

Fractography studies were accomplished on two reaction-sintered Si3N4 materials (Norton NC-350 Si3N4 and KBI (Kawecki-Berylco) Si3N4) which had been tested in four-point bending at room temperature, 1200, 1350, and 1500°C in air. At room temperature NC-350 exhibited uniform planar features representing a transgranular fracture mode, uniformly distributed small pores having a size range of 1–2 μm or less, and a few isolated large pores of ∼10 μm. In contrast, the KBI Si3N4 at room temperature exhibited nonuniform, diffuse, and ill-defined fracture features, small pores having a size range of 2–5 μm, and many large pores of ∼50 μm in size. At high temperatures, the fracture appearance of NC-350 Si3N4 was ill defined and diffuse, indicating a change in fracture mode. The fracture originating flaws in NC-350 were primarily the large pores or pore agglomerates. At all temperatures, in the KBI material, it was not possible to observe the mirror and, therefore, the site of fracture initiation. For NC-350, KIC values were 1.2–1.6 MN/m3/2 at room temperature and 2.1–2.4 MN/m3/2 at high temperatures.
An Experimental Study of Endwall and Airfoil Surface Heat Transfer in a Large Scale Turbine Blade Cascade
Authors: Graziani R. A. , Blair M. F. , Taylor J. R. , Mayle R. E.
Published: October 2009

Local rates of heat transfer on the endwall, suction, and pressure surfaces of a large scale turbine blade cascade were measured for two inlet boundary layer thicknesses and for a Reynolds number typical of gas turbine engine operation. The accuracy and spatial resolution of the measurements were sufficient to reveal local variations of heat transfer associated with distinct flow regimes and with regions of strong three-dimensional flow. Pertinent results of surface flow visualization and pressure measurements are included. The dominant role of the passage vortex, which develops from the singular separation of the inlet boundary layer, in determining heat transfer at the endwall and at certain regions of the airfoil surface is illustrated. Heat transfer on the passage surfaces is discussed and measurements at airfoil midspan are compared with current finite difference prediction methods.
Do Photovoltaics have a Future?
Authors: Williams B. F.
Published: October 2009

While there are several commercial businesses selling photovoltaic power supplies, the applications are all in places where conventional electric power is unavailable. The present interest in solar cell electricity for widespread terrestrial use has led to an intense activity exploring the opportunities for significant cost reduction. In this paper obstacles to cost reduction will be identified and the programs addressing techniques for overcoming those obstacles will be presented.
An Approximate Analysis of Foundation Stresses in Horizontal Pressure Vessels
Authors: Singh Krishna P. , Luk V. K.
Published: October 2009

Saddle supports of horizontally mounted pressure vessels, when subject to seismic and mechanical loads, interact with the foundation in a highly non-linear manner. The maximum foundation concrete pressure, and hold-down bolt stresses are important design considerations which often govern the vessel support geometry. A method is given herein to determine the foundation stresses due to arbitrary imposed loadings. The solution procedure lends itself easily to automated computation—a highly desirable feature—since most nuclear equipment has to be analyzed for a large number of loading conditions.
The Behavior of a Closed-Cycle Gas Turbine with Time Dependent Operating Conditions
Authors: Bammert K. , Poesentrup H.
Published: October 2009

The closed-cycle gas turbine can be applied in thermal power stations using fossil, nuclear or solar energy. Here the behavior of the closed-cycle gas turbine plant under time dependent operating conditions is particularly important. A theoretical model was developed which unlike previously applied methods also considers the transient processes in the heat exchanging units, the heat transfer between the working medium and the internally insulated hot-gas pipes, and the condition of the blading. For examination of the model, measurements were taken on a closed-cycle air turbine. The results of the calculation made for comparison with the test results show the reliability of the calculation model. There is conformity of the measured speeds of the turbo group and of the pressures, temperatures and mass flows of the cycle with the theoretical values until a new steady-state condition is reached.
Characterization and Combustion of SRC II Fuel Oil
Authors: Downs W. , Vecci S. J. , Barsin J. A. , Rovesti W. C.
Published: October 2009

This paper deals with an experimental evaluation of the combustion properties of solvent refined coal II fuel oil. The purpose was to identify problems, if any, associated with handling, storing, pumping, and burning SRC fuel oil. Detailed fuels characterizations were performed and compared to petroleum distillate products. Laboratory fuel analyses and combustion tests were performed with SRC fuel oil, No. 2 fuel oil, and No. 5 fuel oil. Four B&W atomizers were tested and two B&W oil burners were utilized. The laboratory fuel analyses indicated that in most respects this SRC fuel oil sample behaved similarly to No. 2 fuel oil. The combustion tests confirmed that expectation. The one identified problem was relatively high concentrations of fuel-bound nitrogen and, consequently NOx emissions were relatively high. It was concluded that SRC fuel oil may require the application of NOx combustion control techniques.
Full-Coverage Film Cooling—Part I: Comparison of Heat Transfer Data for Three Injection Angles
Authors: Crawford M. E. , Kays W. M. , Moffat R. J.
Published: October 2009

Wind tunnel experiments were carried out at Stanford between 1971 and 1977 to study the heat transfer characteristics of full-coverage film cooled surfaces with three geometries: normal-, 30 deg slant-, and 30 deg × 45 deg compound-angled injection. A flat full-coverage section and downstream recovery section comprised the heat transfer system. The experimental objectives were to determine, for each geometry, the effects on surface heat flux of injection blowing ratio (M), injection temperature ratio (θ), and upstream initial conditions. Spanwise-averaged Stanton numbers were measured for blowing ratios from 0 to 1.3, and for two values of injection temperature at each blowing ratio. The heat transfer coefficient was defined on the basis of a mainstream-to-wall temperature difference. Initial momentum and enthalpy thickness Reynolds numbers were varied from 500 to about 3000. This paper compares the experimental results for the three injection geometries. In addition, the effects of hole spacing and number of rows of holes were examined.
Synchronous Unbalance Response of an Overhung Rotor with Disk Skew
Authors: Salamone D. J. , Gunter E. J.
Published: October 2009

This paper deals with the influence of disk skew on the synchronous unbalance response of flexible rotors in damped bearings. A simple overhung rotor is treated to illustrate the effects of various combinations of unbalance and disk skew on the amplitude and phase angle response at the disk and bearings. The paper shows that it is impossible to balance the rotor at all speeds by single plane balancing even if three correction planes are employed. The presence of disk skew may be best detected by monitoring the far bearing for a rapid phase angle decrease after passing through the first critical speed.
Thermal Performance of Spray-Canal Cooling Systems
Authors: Chaturvedi S. K. , Porter R. W.
Published: October 2009

Spray canals are alternatives to cooling ponds and towers for steam-electric power plants. The literature of thermal modeling is reviewed. A rational analysis supported by field experiments at two large central power stations has led to correlation of local spray cooling performance in terms of two dimensionless groups, one of which is dependent mainly on the type of spray module, and the other is a heating-humidification interference-allowance parameter which depends on wind speed and direction and the type and placement of modules. The analysis is incorporated into a systems performance model for arbitrary canal layout. Examples presented are the circular, race-track and straight double-back canals. Implications for design are discussed.
Continuously Variable Ratio Transmissions for Single-Shaft Gas Turbines
Authors: Fo¨rster H. J.
Published: October 2009

The single-shaft gas turbine was combined with various CVR transmission. Of the three variants studied in detail—purely hydrostatic transmission, hydrostatic transmission with internal power splitting, and hydrodynamic transmission with variable pitch converter—the latter gives the best transmission efficiency. However, comparison with the two-shaft gas turbine shows quite clearly that in practically all cases a large part of the gain in efficiency achieved by increasing the process temperature to 1623 K is absorbed by the losses from the CVR transmissions. Because of the great significance attached today to fuel consumption, the combination of single-shaft gas turbine with CVR transmission—on the basis of these investigations—cannot be recommended. This statement would even apply if it was to be proved that the simple design of the single-shaft gas turbine alone permitted the use of ceramic material and thus the higher process temperatures. This is because the conditions along the traction resistance line for level ground have a much greater effect on everyday fuel consumption than the efficiency ratings at full load. The latter only has an effect during acceleration or when steep gradients are being negotiated.
The Influence of Recent Heat Transfer Data on Gas Mixtures (He-Ar, H2-CO2) on Closed Cycle Gas Turbines
Authors: Pierce B. L.
Published: October 2009

Previous studies have been made on the composition of an optimal working fluid for closed cycle gas turbines. Those studies were based on the assumption that the objective could be achieved by mixing helium with a gas of higher molecular weight. The results of those calculations, based on heat transfer data of pure gases and air, indicated the possibility of significant cost advantages of gas mixtures relative to pure helium. Recent heat transfer measurements of low Prandtl number gas mixtures indicate that existing scaling laws for normal Prandtl number (∼0.7) gases do not adequately represent the heat transfer characteristic of these gas mixtures. In this paper the influence of these gas mixture heat transfer data on closed cycle gas turbine coolers, recuperators and heat source exchangers is presented. The characteristic dimensions (flow area, surface area, and length) of these heat exchangers utilizing pure gases and gas mixtures are compared.
Interferometric Measurements in a Turbine Cascade Using Image-Plane Holography
Authors: Bryanston-Cross P. J. , Lang T. , Oldfield M. L. G. , Norton R. J. G.
Published: October 2009

A holographic technique used to produce image plane interferograms with white light reconstruction is described. This was used to study the transonic flow in a passage of a turbine stator cascade at a typical Reynolds number, Mach number, and free stream to blade surface temperature ratio. Both absolute holographic interferograms (fringes of constant flow density) and differential holographic interferograms (changes of density in 100 μsecs) are presented showing fine details in the boundary layer flow, trailing edge shocks, and wake structure. By counting the fringes on the interferograms, the free stream and surface Mach numbers and boundary layer temperature gradients can be determined.
Aerodynamic and Geometric Design Criteria for the Performance of Low Powered Vehicular Gas Turbines
Authors: Balje O. E.
Published: October 2009

A study of the design criteria for the performance of small single and two-spool vehicular gas turbines using metallic rotors shows that the acceleration capability, i.e., component inertia and the net power output, determine to a large degree the obtainable cycle efficiency. Fluid viscosity effects and manufacturing limitations cause the cycle efficiency to decrease with decreasing net powers. When fast acceleration capability is desired, aero-dynamically compromised component designs may have to be selected which causes an efficiency penalty. It is found that the blade height of the compressor turbine in two-spool designs is a significant parameter for this penalty. One interesting result of the calculations is that single spool designs using metallic radial inflow turbine rotors can be quite competitive with two-spool designs using ceramic rotors in regard to efficiency. They suffer, however, from a comparatively high rotor inertia, i.e., reduced acceleration capability. Areas of uncertainties remain for the loss relations so that the calculated performance values must be viewed as trend data. The prime performance parameter used in this study is the flow path efficiency. The thermal cycle efficiency is presented only for constant values of heat exchanger effectiveness and mechanical efficiency.
Experiments on the Vibration Characteristics of a Rotor With Flexible, Damped Support
Authors: Yan Li-Tang , Li Qi-Han
Published: October 2009

Experiments were performed on a model rotor test rig with a disk located at the mide-span and a squeeze film damper and/or flexible support at one end and a rigid support at the other end. The damping effects of the flexible support and stress variation of the support itself have been tested. Emphasis was placed on the steadystate characteristics and the damping effects of the flexible supports and dampers with different radial clearances under various level of rotor unbalance. The dampers are without end seals and oil grooves. Comparative tests of the damping effects of the flexible, damped support were done during passing through the first and second critical speeds. Simulating tests of the vibration of the bearing housing excited by nonrotor exciting sources have been carried out and the damping effects of the oil film dampers on this type of vibrations were examined.
The Civic: A Concept in Vortex Induced Combustion for the Solar Gemini 10 kW Gas Turbine
Authors: Shekleton J. R.
Published: October 2009

The Radial Engine Division of Solar Turbines International, an Operating Group of International Harvester, under contract to the U.S. Army Mobility Equipment Research & Development Command, developed and qualified a 10 kW gas turbine generator set. The very small size of the gas turbine created problems and, in the combustor, novel solutions were necessary. Differing types of fuel injectors, combustion chambers, and flame stabilizing methods were investigated. The arrangement chosen had a rotating cup fuel injector, in a can combustor, with conventional swirl flame stabilization but was devoid of the usual jet stirred recirculation. The use of centrifugal force to control combustion conferred substantial benefit (Rayleigh Instability Criteria). Three types of combustion processes were identified: stratified and unstratified charge (diffusion flames) and pre-mix. Emphasis is placed on five nondimensional groups (Richardson, Bagnold, Damko¨hler, Mach, and Reynolds numbers) for the better control of these combustion processes.
Turbomachinery Design Considerations for the Nuclear HTGR-GT Power Plant
Authors: McDonald Colin F. , Smith Murdo J.
Published: October 2009

For several years, design studies have been underway in the U.S. on a nuclear closed-cycle gas turbine plant (HTGR-GT). This paper presents design aspects of the helium turbo-machine portion of these studies. Gas dynamic and mechanical design considerations are presented for helium turbomachines in the 400 MWe (non-intercooled) and 600 MWe (intercooled) power range. Design of the turbomachine is a key element in the overall power plant program effort, which is currently directed towards the selection of a reference HTGR-GT commercial plant configuration for the U.S. utility market. A conservative design approach has been emphasized to provide for maximum safety and durability. The studies presented for the integrated plant concept outline the necessary close working relationship between the reactor primary system and turbomachine designers. State-of-the-art technology from large industrial gas turbines developed in the U.S., considered directly applicable to the design of a helium turbomachine, particularly in the areas of design methodology, performance, materials, and fabrication methods, is emphasized.
A Mathematical Model for the Stirling Engine Cycle
Authors: Beans E. W.
Published: October 2009

A mathematical model for the Stirling engine cycle is presented. This model differs from the Schmidt Cycle in that an adiabatic dead space is assumed and that the enthalpy exchange between various volumes is accounted for. The model, in general, predicts performance which is lower than the Schmidt Cycle. The model results in a thermal efficiency which is a function of all design parameters rather than temperature only. A comparison between the p-ν diagram from the mathematical model and a measured diagram is in good agreement.
Application of the Semi-Loof Thin Shell Element to the Analysis of Aircraft Engine Structures
Authors: Elkelish M. S. , Elsawaf A. , Barsoum M.
Published: October 2009

Most gas turbine engine structures consist of thin shells with multiple junctions. The curved isoparametric shell element gives unsatisfactory results when used for very thin shells. The Semi-Loof shell element was developed especially to deal with thin shell structures with sharp corners and multiple junctions. The Semi-Loof shell program was used at P&WC for the analysis of large engine structures. Application to the analysis of an engine static structural model, for which experimental data are also available, has confirmed the efficiency of the Semi-Loof shell element in comparison with the conventional isoparametric element.
Long Arc Shrouding—A Reliability Improvement for Untuned Steam Turbine Blading
Authors: Ortolano R. J. , La Rosa J. A. , Welch W. P.
Published: October 2009

An approach to the design and modification of untuned variable speed steam turbine exhaust blading has been found to be highly successful in eliminating fatigue failures due to the first tangential in-phase mode resonance. The approach consists of butt-welding the shrouds on the short arc blade groups to form a substantially longer arc length. The result is a significant reduction in vibratory stress at resonant speeds. Because of the ease with which the approach can be implemented in the field, backfitting is highly attractive to turbine operators. Availability benefits to the marine, utility, petrochemical, refining, industrial and commercial fields are anticipated.
A Mathematical Model for Heat Transfer in Combustion Chambers of Steam Generators
Authors: Gulicˇ M. G. , Gvozdenac D. D.
Published: October 2009

This paper describes a mathematical model for determining the total heat transfer in combustion chambers of steam generators. The model is based on the energy balance of radiation in a spherical combustion chamber which is divided into a combustion zone and gaseous zone. The model was tested on a Hewlett-Packard Type 9815 A computer with 2008 program memories. Calculations were made for a number of steam generator combustion chambers of different furnace loads for which all important factors were established. The model allows a didactic analysis of factors influencing the process of combustion and heat transfer.
Performance of a Multiphase Boiling MHD Generator
Authors: Urbach H. B. , Purnell J. G. , Knauss D. T.
Published: October 2009

Adiabatic liquid metal-water MHD generators produce power during water boiling because both temperature and pressure drop throughout the phase change. Therefore, boiling MHD generators with boiling water, as distinguished from purely expansive steam-liquid metal MHD generators, may be useful energy-conversion devices. A generator, with a working fluid consisting of a liquid-metal eutectic of tin and bismuth, water, and steam, was analyzed in accordance with anticipated isentropic efficiencies. Real-gas-law data from steam tables were employed to integrate one-dimensional multiphase thermodynamic equations by using Simpson’s rule. Consistency checks on the boiling section showed errors of about 1 percent. The contribution of the boiling section of the generator was computed to be about 20 percent greater per unit length and 360 percent greater per unit volume than the purely expansive section of the MHD generator for the studied inlet conditions.
Fan/Foundation Interaction—A Simplified Calculation Procedure
Authors: Chen H. M. , Malanoski S. B.
Published: October 2009

This paper presents a simplified analysis procedure to provide initial assessment and guidance on fan rotor dynamics including the foundation interaction. For purposes of early-design decision-making (or trouble-shooting), the interaction of a rotor-bearing dynamic system and a foundation-soil/piling dynamic system is viewed approximately for the vertical, horizontal, and rocking modes of vibration. The equations of motion are written in matrix form and include the pertinent parameters. A numerical example is presented to guide in the interpretation of the analysis; this example considers the unbalance response of the entire system as measured at the bearings.
Sexual Conflict Resolved by Invasion of a Novel Sex Determiner in Lake Malawi Cichlid Fishes
Authors: Roberts Reade B. , Ser Jennifer R. , Kocher Thomas D.
Published: October 2009

Sexual Blotch

Sexual conflicts may provide selection pressures that facilitate invasion of new genetic sex determiners.

Roberts
et al.

(p.
998
, published online 1 October) describe data obtained from several species of sexually dimorphic cichlid fishes found in Lake Malawi that support this model. An orangeblotch color pattern has evolved among the females of rock-dwelling species because it provides effective camouflage against the algae-coated rocks. Blotched males (OB) are rare, possibly because the trait interferes with the normal male color pattern of blue stripes that are important cues for mate selection. The pigmentation pattern that creates this conflict between natural selection in females and sexual selection in males is caused by mutation in the
cis
-regulatory region of the
Pax7
gene and is tightly linked to a dominant female sex determiner. When bred in the lab, the OB males inherit the intact maternal OB haplotype and their OB-carrying chromosome determines female sex in the offspring; the males seem to be sex-reversed by another mechanism.
A Population of Compact Elliptical Galaxies Detected with the Virtual Observatory
Authors: Chilingarian Igor , Cayatte Véronique , Revaz Yves , Dodonov Serguei , Durand Daniel , Durret Florence , Micol Alberto , Slezak Eric
Published: October 2009

Elliptical Galaxy Evolution

Our closest elliptical galaxy, M32, represents a rare class of elliptical galaxies that are too compact for their luminosities. Only a handful of elliptical galaxies with luminosities and sizes comparable to M32 have been found, making it difficult to understand how they evolved.

Chilingarian
et al.

(p.
1379
, published online 1 October) present a sample of 21 compact elliptical galaxies gathered through automated data mining of the Hubble Space Telescope Legacy Archive and other databases by means of virtual observatory tools. The results suggest that tidal stripping of more massive progenitor galaxies produces compact elliptical galaxies.
Cigarette brand preference as a function of price among smoking youths in Canada: are they smoking premium, discount or native brands?
Authors: Leatherdale S T , Ahmed R , Barisic A , Murnaghan D , Manske S
Published: October 2009

Introduction:

Given that little is known about the price-related cigarette brand preferences of youths, the current study seeks to characterise cigarette brand preferences and examine factors associated with smoking discount or native cigarette brands among Canadian youths who are current smokers.

Methods:

This study used nationally representative data collected from 71 003 grade 5–12 students as part of the 2006–7 Canadian Youth Smoking Survey (YSS). Using data from current smokers, logistic regression models were used to examine factors associated with smoking discount or native cigarette brands relative to premium cigarette brands.

Results:

In 2006, premium cigarettes were the most prevalent brand of cigarette youths report usually smoking (49.4%); a substantial number of youths do report usually smoking either discount (12.9%) or native (9.3%) cigarette brands. Occasional smokers were more likely to report usually smoking premium cigarettes whereas daily smokers were more likely to report smoking either discount or native cigarettes. In particular, discount and native brands appear to be appealing among smoking youths with less spending money or those who are heavier smokers compared to youths smoking premium brands.

Conclusion:

Discount and native cigarette brands are commonly used by a substantial number of smoking youths in Canada. Additional research is required to better understand the reasons behind different cigarette brand preferences and how youths are able to access premium, discount and illicit native cigarettes. Moreover, ongoing surveillance of the cigarette brand preferences of youths is required for guiding future tobacco control policy and programming activities.
Support for smoke-free policy among restaurant owners and managers in Ulaanbaatar, Mongolia
Authors: Chang S-H , Delgermaa V , Mungun-Ulzii K , Erdenekhuu N , Odkhuu E , Huang S-L
Published: October 2009

Objectives:

Exposure to second-hand smoke (SHS) is widespread in restaurants in Ulaanbaatar, the capital city of Mongolia. While a smoke-free policy is the most effective way of protecting restaurant workers and customers from SHS, this has not been well accepted in Mongolia. Furthermore, little is known about restaurants’ attitude toward the smoke-free policy.

Methods:

A cross-sectional survey directed to restaurant owners or managers was conducted in 475 representative restaurants in Ulaanbaatar. Face-to-face interviews using a questionnaire and on-site observation were performed.

Results:

Only 29.3% of the restaurants claimed to prohibit smoking; none of the remaining had any protection toward SHS, and half of the restaurants estimated that more than 20% of customers would smoke inside. None of them had visible “no smoking” signs and the majority never received complaints about SHS. Despite the generally high level of knowledge of the health effects of SHS, of the 336 restaurants that were not smoke free, only 25.9% expressed that they planned to take action in the near future. By contrast, 87.8% of restaurants would support the government if it asked all restaurants to ban smoking. Multivariate analysis identified that restaurants having menus in foreign languages, selling cigarettes and predicting business decline were less likely to support the government smoke-free policy.

Conclusions:

This survey demonstrates that restaurants owners and managers were reluctant to take action on their own, but would support government policy. The government can assume a stronger role first by revising the law on tobacco control following the Framework Convention on Tobacco Control guideline.
EXTENDED SCALING SCHEME FOR CRITICALLY DIVERGENT QUANTITIES AND CRITICAL EXPONENTS OF AN ISING SPIN GLASS
Authors: HUKUSHIMA K. , CAMPBELL I. A. , TAKAYAMA H.
Published: October 2009

A long-standing issue in a three-dimensional Ising spin glass (3DISG) is to settle the critical exponents. Numerical simulations and a conventional finite-size-scaling analysis have given controversial estimates, in particular, for the value of thermal exponent ν. Here a recently proposed extended scaling scheme is reviewed and illustrated for the canonical two-dimensional Ising ferromagnet. By applying the extended scaling to our extensive Monte Carlo data for 3DISG, consistent estimates of critical parameters are obtained in contrast to previous analyses.
NONEQUILIBRIUM RELAXATION STUDIES FOR FRUSTRATED SPIN SYSTEMS WITH KOSTERLITZ–THOULESS TRANSITIONS
Authors: OZEKI YUKIYASU , YOTSUYANAGI SATOSHI
Published: October 2009

The q-state clock gauge glass model in two dimensions with q = 6, 8, 10, 12, 14, 16 is studied by the use of the nonequilibrium relaxation analysis of the Kosterlitz–Thouless (KT) transition. The successive transitions of FM-KT-PM phases are investigated along the Nishimori line. For the upper critical temperature, it is found that the transition temperature is almost the same as in the continuous case for all q values. The lower transition temperature is found to be proportional to 1/q2. While the present model is not self-dual, we have a remarkable behavior with respect to the duality relation derived for the self-dual Villain-type model.
MIXING DIFFERENT RANDOM DEPOSITIONS IN NONEQUILIBRIUM SURFACE GROWTH MODELS
Authors: NOVOTNY M. A. , KOLAKOWSKA A.
Published: October 2009

An exact solution is presented for mixing two or more different types of Random Deposition (RD) nonequilibrium surface growth processes. The depositions may be made in a sequential mode, or in a random mode by first randomly choosing the lattice site for deposition. The results hold in all dimensions d. Simulations are presented in d = 1 for comparison. Furthermore, a mean-field type of approach to mixing RD with other surface growth processes is tested against the exact solution.
COMPLEX BEHAVIOR IN SIMPLE MODELS OF BIOLOGICAL COEVOLUTION
Authors: RIKVOLD PER ARNE
Published: October 2009

We explore the complex dynamical behavior of simple predator-prey models of biological coevolution that account for interspecific and intraspecific competition for resources, as well as adaptive foraging behavior. In long kinetic Monte Carlo simulations of these models we find quite robust 1/f-like noise in species diversity and population sizes, as well as power-law distributions for the lifetimes of individual species and the durations of quiet periods of relative evolutionary stasis. In one model, based on the Holling Type II functional response, adaptive foraging produces a metastable low-diversity phase and a stable high-diversity phase.
PHASE TRANSITIONS IN SPIN GLASSES
Authors: YOUNG A. P.
Published: October 2009

Some recent progress in Monte Carlo simulations of spin glasses will be presented. The problem of slow dynamics at low temperatures is partially alleviated by use of the parallel tempering (replica exchange) method. A useful technique to check for equilibration (applicable only for a Gaussian distribution) will be discussed. It will be argued that a finite size scaling analysis of the scaled correlation length of the system is a good approach with which to investigate phase transitions in spin glasses. This method will be used to study two questions:

(i) whether there is a phase transition in zero field in the Heisenberg spin glass in three dimensions, and

(ii) whether there is phase transition in a magnetic field in an Ising spin glass, also in three dimensions.
QUANTUM PHASE TRANSITION OF A TRIANGULAR LATTICE SPIN TUBE AND EDGE SPIN EFFECTS
Authors: OKUNISHI KOUICHI , YOSHIKAWA SHIN-ICHIRO , SAKAI TÔRU , MIYASHITA SEIJI
Published: October 2009

We study the low-energy excitation of the quantum spin tube with the triangular lattice structure, using density matrix renormalization group. Taking account of the edge spin effect, we particularly investigate the spin gap behavior and the low-field magnetization curve near the quantum phase transition point in contrast with the usual free boundary condition. We then find that the bulk behavior of the spin tube can be extracted easier for the single spin termination.
SMOOTHED PROFILE METHOD TO SIMULATE COLLOIDAL PARTICLES IN COMPLEX FLUIDS
Authors: YAMAMOTO RYOICHI , NAKAYAMA YASUYA , KIM KANG
Published: October 2009

A new direct numerical simulation scheme, called "Smoothed Profile (SP) method," is presented. The SP method, as a direct numerical simulation of particulate flow, provides a way to couple continuum fluid dynamics with rigid-body dynamics through smoothed profile of colloidal particle. Our formulation includes extensions to colloids in multicomponent solvents such as charged colloids in electrolyte solutions. This method enables us to compute the time evolutions of colloidal particles, ions, and host fluids simultaneously by solving Newton, advection-diffusion, and Navier–Stokes equations so that the electro-hydrodynamic couplings can be fully taken into account. The electrophoretic mobilities of charged spherical particles are calculated in several situations. The comparisons with approximation theories show quantitative agreements for dilute dispersions without any empirical parameters.
ELEMENTARY EXCITATIONS AND SPIN DYNAMICS IN NANOWIRE QUANTUM MAGNETS
Authors: SAKAI TÔRU , TONEGAWA TAKASHI , OKAMOTO KIYOMI
Published: October 2009

We investigate the elementary excitations and magnetization dynamics of the recently synthesized single-chain magnets, which consist of Mn and Ni ions, and some related systems, using the numerical exact diagonalization of finite-size clusters and the density matrix renormalization group method. It is found that, as the easy-axis anisotropy D increases, a crossover of the lowest-lying elementary excitation should exist between the spin wave and Ising-like excitations. For the realistic trimer single-chain magnet, we estimate several crossover temperatures. In addition we predict that a magnetization plateau at 2/3 of the saturation magnetization would appear in the (s, S) = (1, 2) spin-alternating chain. The phase diagram of the plateau is also presented.