bluuebunny/crossref_metadata_2025 huggingface dataset:
Construction of Three-Workpiece Lapping Process
Authors: Sakai Y. , Tanaka Y. , Ido M.
Published: November 2010

A new method, designated three-workpiece lapping, is proposed to produce flat surfaces of all the three workpieces prepared through some stages of reciprocation lapping, which is performed by a simple machine, by choosing appropriate combinations of upper, lower and waiting workpieces. Simulated and experimental results show that the parabolic shapes of the surfaces are maintained during lapping and two inherent properties exist in the change of profile parallel to the reciprocation, that is, (1) upper workpiece and lower one become concave and convex respectively as lapping proceeds and (2) they tend to fit each other, while only the second property is observed in the change of profile perpendicular to the reciprocation. Linear vector differential equations are introduced to represent the above properties and the stages required to get flat surfaces are deduced by constructing trajectories which express the changes of the shapes on the spaces where the differential equations are given.
Hydrazine Monopropellant Reciprocating Engine Development
Authors: Akkerman J. W.
Published: November 2010

A hydrazine-fueled piston-type engine for providing 11.2 kW (15 hp) has been developed to satisfy the need for an efficient power supply in the range from 3.7 to 74.6 kW (5 to 100 hp) where existing nonair-breathing power supplies such as fuel cells or turbines are inappropriate. The engine was developed for an aircraft to fly to 21.3 km (70 000 ft) and above and cruise for extended periods. The NASA Hugh L. Dryden Flight Research Center developed a remotely piloted aircraft and the associated flight control techniques for this application. The engine is geared down internally (2/1) to accommodate a 1.8-m (6 ft) diameter propeller. An alternator is included to provide electrical power. The pusher-type engine is mounted onto the aft closure of the fuel tank, which also provides mounting for all other propulsion equipment. About 20 hr of run time have demonstrated good efficiency and adequate life. One flight test to 6.1 km (20 000 ft) has been made using the engine with a small fixed-pitch four-bladed propeller. The test was successful in demonstrating operational characteristics and future potential.
Effect of Surface Contamination on the Diffusion Bonding of Copper
Authors: Bradford J. M. , Nagpal V.
Published: November 2010

An investigation was made of the effect of cleaning the contacting surfaces of copper samples upon the strength of the diffusion bond formed. The cleaning of surfaces by filing and the diffusion bonding were carried out in high vacuum. Results showed that the bond formed between samples cleaned by filing was greater than the bond formed by samples that were not cleaned prior to bonding. An analysis is made of the data to show that the activation energy of the bonding process is much less than the activation energy of bulk self diffusion of copper.
Application of the CO2 Laser to Thermal Properties Measurements in Biomaterials
Authors: Hansen W. P. , Greenwald R. J. , Bowman H. F.
Published: November 2010

The CO2 laser provides radiation that is strongly absorbed and only weakly back-scattered by high water-content materials, such as biological tissue. Several methods can be employed to obtain radial distributions of laser irradiance that are described by simple mathematical functions. It is therefore possible to use the CO2 laser to noninvasively establish an accurately known surface heat source. An effective thermal conductivity of the material can be determined from the temperature response due to laser heating. Thermal conductivity is reported for agar gel using CO2 laser heating and thermocouple temperature sensing.
Surface Finishes Produced by Tungsten Carbide Taper Pin Reamers
Authors: Turley D. M.
Published: November 2010

The surface finishes produced by taper reaming of holes in a composite structure of aluminum alloy and ultra-high strength steel are examined for both dry and lubricated cutting conditions. In dry reaming cutting occurred under built-up-edge (BUE) conditions whereas when a mineral cutting oil was used no significant BUE was formed. Reaming under the latter conditions resulted in a more undulating steel surface finish but a much smoother surface finish for the aluminum alloy.
Predictions of the Effect of Yield Strength on Fatigue Crack Growth
Retardation in HP-9Ni-4Co-30C Steel
Authors: Petrak G. J. , Gallagher J. P.
Published: November 2010

Baseline mechanical property data, constant amplitude fatigue crack growth rate data, and single-peak overload test data are presented for HP-9Ni-4Co-30C steel heat treated to three strength levels. These data are then used to evaluate a new model proposed for defining the instantaneous crack growth rate following an overload. The constant amplitude crack growth rates are affected by the strength level of the material with the higher strength exhibiting the faster cracking rates. The magnitude of retardation following an overload cycle is also shown to be influenced by the strength of the material. The lower strength steel displayed significantly more retardation for the same load levels. A general yield zone model is used to predict retarded growth rates. These predictions are shown to correlate quite well with the test data. The model successfully accounts for the different amounts of retardation associated with the different strength levels of the material.
Test Methods for Fuel Oil Ash Corrosion of Heat Resisting Alloys
Authors: Tanaka R. , Miyagawa O.
Published: November 2010

A cooperative study has been performed by twenty members of the Committee on Heat Resisting Metals and Alloys of Japan Society for the Promotion of Science to find a useful rapid test method for evaluation of resistance of heat resisting alloys to fuel oil ash corrosion. It was concluded that furnace tests yielded relative corrosion rates very similar to those attained in a combustion test rig designed to approach actual engine conditions. This test method has been authorized by the Committee as a standard rapid test method for screening of austenitic heat resisting alloys.
Some New Approaches in the Analysis of High-Temperature Deformation
Authors: Woodford D. A.
Published: November 2010

Creep tests on two heats of a CrMoV steel at 811K (1000°F) are analyzed using a new graphical procedure to solve the equation σ = C(t) H(ε). This enables prediction of both constant load and constant stress creep behavior at different stresses within the range examined which included tests lasting in excess of 10,000 hr. An analytical solution of the equation is also described and used to generate isochronous stress-strain curves. Attempts to predict the response in relaxation and constant strain rate tests where the load is continuously changing are described. Reasonable agreement was obtained in the former type of test using a total strain rule, which assumes a unique relationship between stress, strain and time, when the stress range covered was within the range used in the creep analysis. For constant strain rate testing, where a much broader stress range was involved, it was necessary to use incremental analysis to achieve good agreement between predicted and experimental curves up to about 2 percent strain.
The Modeling of Flow Concentration in Two-Phase Materials
Authors: Cook T. S. , Rau C. A. , Smith E.
Published: November 2010

Many high strength alloys that are developed for arduous operating conditions have essentially a two-phase microstructure that is produced by a precipitation-hardening procedure. However, alloys that are heat-treated to have maximum hardness, often have poor monotonic and poor fatigue fracture characteristics when these are assessed in relation to their high yield strengths, and this imposes limits to their use for service applications. Experimental investigations covering a wide range of precipitation-hardened alloys have shown that the inferior fracture properties are due to plastic deformation being concentrated within narrow zones. Against this background, Pratt & Whitney Aircraft is undertaking a comprehensive theoretical investigation based on the representation of flow concentration by appropriate theoretical models. The general objective is to provide a quantitative understanding of flow concentration, both with respect to its causes and consequences, in terms of both material and externally imposed parameters such as, for example, the state of loading. The aim of the present paper is not to survey the complete problem of flow concentration in the light of the research undertaken to date, but to provide a limited number of examples that illustrate how specific aspects of the problem have been considered using appropriate models to describe the operative physical processes. With the Conference’s objectives in mind, the paper’s general intention is therefore to provide further evidence that micromechanical modeling can be successfully used to relate mechanical behavior with metallurgical parameters, and thereby add further support for the view that such work forms an integral part of any balanced materials research and development program.
Susceptibility to Underclad Cracking in Relation to Chemical Composition
Authors: Kume R. , Okabayashi H. , Amano M.
Published: November 2010

Heat-affected zone cracking under the weld-overlay-cladding has been investigated for the combination of 22 kinds of ferritic base metals and electrodes including strip electrodes of austenitic and ferritic stainless steels, Inconel and mild steel, and covered electrodes of austenitic and ferritic stainless steels and Inconel. The results indicate that (1) intercrystalline cracks form on stress relieving under the overlap area of the cladding beads, (2) the susceptibility to cracking depends markedly on the chemical composition of the base metal, and the following equation predicts cracking tendency, ΔG = [Cr] + 3.3 [Mo] + 8.1 [V] − 2, and (3) cracking is avoided or decreased by using cladding material which is similar in thermal expansion coefficient to base metal.
High Temperature Thermal-Elastic Analysis of Dissimilar Metal Transition Joints
Authors: Dalcher A. W. , Yang T. M. , Chu C. L.
Published: November 2010

Thermal-elastic analyses of dissimilar metal transition weld joints of a 24″ sodium piping system were performed. This piping system is for Liquid Metal Fast Breeder Reactor application, operating at elevated temperature (965°F). These analyses form a basis for the selection of the material combination and weld preparation of the transition joints. Two material combinations were selected for weld joint thermal-elastic analysis: 2 1/4 Cr - 1 Mo ferritic steel to 316 stainless steel, and 2 1/4 Cr - 1 Mo steel to Incoloy 800, with Inconel 82 as the welding metal in both cases. Weld preparations with various geometries were assumed for each material combination. The transition joints were evaluated for thermal loadings due to the changes in sodium temperatures during anticipated operating conditions of the breeder reactor. Thermal analyses were performed to define the temperature time history in the metals; the temperature gradient across the wall thickness; and especially, the temperature distribution near the material interfaces. The magnitude of the temperature gradients and the temperature distribution as affected by the heat transfer characteristics of each material were of particular interest. Stresses created due to the differences of thermal expansion of the materials, radial and axial temperature gradients, and applied internal pressure were evaluated using finite element analysis methods. In this investigation, the materials were treated as elastic and isotropic. The contributions from the applied pressure and thermal loading were separated from the total stresses and the most important contributor was identified. The elastic analyses served for a preliminary evaluation of the transition joint selection. Based on the information obtained in stress versus material combination and the stress variation as a function of the geometry of the weld preparation, a weld design (material combination and geometry) was selected.
A J-Integral Approach to Crack Resistance for Aluminum, Steel, and Titanium Alloys
Authors: Wilhem D. P. , Ratwani M. M. , Zielsdorff G. F.
Published: November 2010

Crack growth resistance data have been obtained for a variety of materials as a function of thickness and crack orientation. Resistance to crack extension is determined in terms of the square root of JR which includes crack tip plasticity. To obtain these data elastic and elastic-plastic analyses were performed on the crack line wedge loaded (CLWL) specimen. The data thus obtained can be used as a failure criterion in both plane stress and mixed mode fracture of uniaxially loaded, reinforced structure containing initial or fatigue induced flaws.
The Influence of Material Variability on the Predicted Environmental Behavior of Composite Materials
Authors: Adams Donald F. , Miller A. Keith
Published: November 2010

The stresses and strains induced in a composite material when subjected to mechanical loads are shown to be strongly influenced by prior exposure to both temperature changes (e.g., cooldown from the curing temperature) and moisture absorption (e.g., even normal exposure to ambient conditions after cure). These environmental effects are in turn influenced by normal variabilities in the basic properties of the composite constituents. Using a recently developed finite element numerical model of composite material inelastic hygrothermal response, variations in stresses and strains are predicted as a function of variations in constituent material properties. A typical graphite/epoxy composite is selected for detailed study. This system is of particular interest because of the anisotropic nature of graphite fibers, and the strong temperature and moisture dependence of the epoxy matrix. Specific fiber property variations considered include transverse modulus, major Poisson’s ratio, and in-plane Poisson’s ratio. Results are compared with those obtained for an isotropic fiber composite.
Thermal Analysis of Capacitor Discharge Welding and its Correlation With Observed Stress Wave Emission (SWE)
Authors: Paek U. C. , Vahaviolos S. J. , Kleinedler G. E.
Published: November 2010

A theoretical approach to thermal analysis of capacitor discharge welding is presented. The weld current is divided into three segments (premelting, melting, and postmelting) and each is analyzed with a one dimensional heat conduction model. From this analysis, normalized parameter values are plotted to provide an estimate of the thermal time constant of welding and the extent of melting. The predicted weld zone depth of penetration was experimentally verified with metallographic data. Similarly, using signal frequency discrimination techniques, it was found that Stress Wave Emission (SWE) techniques could be adapted to measure the parameters of the above three pulse segments (tm, te, tc) accurately and in real time. Theoretical and experimental metallographic and SWE results are in good agreement.
Design of the First Large United Kingdom Power Producing Refuse Disposal Plant
Authors: Pepe P. D. , Turner G. M.
Published: November 2010

The Refuse Disposal plant being erected at Edmonton for the Greater London Council is the first of its kind to be built in the United Kingdom. It is designed to handle automatically 1333 tons (2240 lb per ton) of crude refuse every 24 hr, untouched by hand. The refuse is used as a fuel to produce steam for the generation of about 30 mw of electric power, the exact amount depending on the throughput and calorific value of the fuel. A brief description of the plant is followed by the reasons and economic considerations associated with the overall concept. Later a more detailed explanation is given of those aspects of the design which were influenced by problems peculiar to refuse handling and incineration. The roller type incineration grates and combustion chambers, which are suitable for handling metallic objects as large as bedsteads, are described and their combustion principles explained. The boilers, of which the grates and combustion chambers are an integral part, presented some problems in designing for satisfactory availability of the gas side of heating surfaces and for an economically justifiable life of certain critical parts; these problems are described and reference is made to the somewhat limited large-scale experience available at the time of establishing the design. Other parts of the plant are also described where novel in design or application.
Loss and Flow Path Studies on Centrifugal Compressors—Part I
Authors: Balje´ O. E.
Published: November 2010

Relations are derived for the boundary layer momentum thickness growth in channels with adverse pressure gradients and for the maximum allowable momentum thickness to avoid flow separation. These data are obtained by integrating the Truckenbrodt equation stepwise and by extending the Gruschwitz-Schmidbauer separation criterion. Fair agreement between calculated data and test information is demonstrated.
Investigation of Air Bearings for Small High-Performance Aircraft Gas Turbines
Authors: Curwen P. W. , Young W. E. , Furgurson R. G.
Published: November 2010

High temperatures and rotative speeds of future U. S. Army aircraft propulsion systems will impose increasingly severe operating requirements on oil-lubricated engine bearings and associated seals. Accordingly, air-lubricated bearings are being investigated as a possible approach to alleviating the lubrication problems. This paper presents the results of design and performance studies, as well as bearing component tests, relative to applying air bearings to a two-shaft, 3.5-lb/sec turboshaft engine. The test results verify that air bearings can carry the maximum loads imposed by flight and landing conditions, and can survive the sliding contacts associated with 15,000 engine start/stop cycles. Incentives for pursuing the air-bearing approach are identified, as are also the development and problem areas.
On the Unsteady Supersonic Cascade With a Subsonic Leading Edge—An Exact First Order Theory—Part 1
Authors: Kurosaka M.
Published: November 2010

This paper presents, in two parts, the theoretical predictions of the aerodynamic forces acting on slowly oscillating airfoils in a supersonic cascade with a subsonic leading edge. The analysis is based on the assumption of an inviscid, two-dimensional and linearized flow. In the first part of the paper, the flow field ahead of the cascade is considered. An initial value problem is posed and, from the periodicity requirement in the cascade, the problem is reformulated in terms of integral equations. Solution of the integral equations, accurate to the first order of a frequency parameter, are obtained in closed form. In the limit of the steady flow, the unsteady flow analysis yields a mathematical verification of the unique incidence effect. Based on this proof, a simple rule is presented for the airfoil suction surface contour satisfying steady flow requirement ahead of the cascade. The complete aeroelastic problem, including the solution for the flow field between the blades and the trailing interference zone, is treated in Part 2.
Equilibrium Composition of Simulated Coal Combustion Products: Relationship to Fireside Corrosion and Ash Fouling
Authors: Wilson J. S. , Redifer M. W.
Published: November 2010

A computer solution of chemical equilibrium composition is presented for high-temperature combustion reactions related to fireside corrosion and ash fouling. A simple calculation system, which models the injection of a sodium-potassium mixture through a flame, is solved for equilibrium compositions at temperatures from 1500 deg to 3000 deg F at varying oxygen levels from 0.1 percent to 17 percent in the gas stream and 1 atmosphere pressure. At equilibrium, principally alkali sulfates and hydroxides are produced in the model of a combustion product atmosphere resembling that in a coal-fired boiler. A total of 42 reactions involving 40 chemical species were treated in the reactant mixture and compositions for the entire system are included.
Performance of Perforated Heat Exchanger Surfaces
Authors: Mondt J. R. , Siegla D. C.
Published: November 2010

Heat transfer and flow friction behavior have been measured for plain and perforated plate-fin and 10-deg herringbone surfaces. For the range of geometries and Reynolds numbers studied, the perforations produced no significant improvement in heat transfer for the same pressure drop. Heat transfer behavior was determined with the “single blow” transient technique. The “initial rise” evaluation procedure was used for low Ntu test packs. Entrance length effects on both heat transfer and friction behavior were correlated for L/4rh as low as 45.
Vibrating Beam Dampers for Reducing Vibrations in Gas Turbine Blades
Authors: Jones D. I. G. , Nashif A. D. , Stargardter H.
Published: November 2010

This paper reports the results of a preliminary investigation of the feasibility of reducing vibratory response levels in jet engine turbine blades by means of tuned damping devices incorporating high temperature vitreous enamels for energy dissipation. It is shown that an externally coated cantilever beam damper can be very effective in reducing vibration amplitudes, provided that it is properly tuned. Further efforts are needed to develop and verify an engineering design which will satisfy all operational requirements. The first step in that direction, which should be the next phase of the investigation, is to verify that the enamels and dampers considered in this paper will withstand the centrifugal loads imposed by rotation of the blades.
Deviation Angle Estimation for Axial-Flow Compressors Using Inviscid Flow Solutions
Authors: Miller M. J. , Serovy G. K.
Published: November 2010

Development of a more satisfactory method of estimating deviation angles was attempted using analytical procedures. Solutions for inviscid, irrotational flow in the blade-to-blade plane were obtained with a finite-difference calculation method. Deviation angles for three cascades with rounded trailing edges were estimated using the inviscid flow solutions and four existing trailing edge hypotheses. The estimated deviation angles were compared with experimental values for a range of incidence angle and inlet flow angle. None of the hypotheses were satisfactory at all incidence angles for all the cascades considered. An alternative hypothesis is presented which is suitable for one of the cascade profiles over a range of incidence and blade setting angle.
Study of Casing Treatment Effects in Axial Flow Compressors
Authors: Boyce M. P. , Schiller R. N. , Desai A. R.
Published: November 2010

The phenomenon of surge in an axial flow compressor has long eluded the analytical fluid dynamist. In the recent years, a growing degree of improvement and sophistication in the design of axial flow compressors to achieve higher pressure ratios has resulted in increasingly narrow domains of stable operation. A search for improving stability margins revealed the importance of the blade tip region and casing treatments. The authors have approached the problem by both experimental and analytical methods. The results are mutually confirming. Important new inroads have been made in understanding the flow in the blade tip region, operation of casing treatments and the mechanism of the onset of surge. Some significant conclusions in the selection and design of casing treatments and their effects on the stability margin are presented and explained on the basis of experimental and theoretical results.
Limit Design of Condenser Hotwell Floors
Authors: Soler A. I.
Published: November 2010

Rigid plastic plate theory is used to determine the limit load for a pipe-supported flat plate loaded by uniform pressure. The solution is applied to design of condenser hotwell floors under hydrotest loading. A comparison is made with a formula for design of similar configurations suggested in Section VIII, Division 1 of the ASME Pressure Vessel Code, and in texts on elastic plate theory.
Western Coals—Laboratory Characterization and Field Evaluations of Cleaning Requirements
Authors: Moore G. F. , Ehrler R. F.
Published: November 2010

Many discussions have pointed out the differences in the characteristics of eastern and western coals. Low rank western coals have higher moistures, lower calorific values, and the ash constituents are more basic. Slagging and fouling indexes based on the ash chemistry of eastern bituminous coals are not applicable for low rank western coals. These differences led to dissimilarities in the behavior of eastern and western coals, so we have directed our efforts toward a study of the behavior of low rank western coals and how they differ from eastern coals. Three nonroutine laboratory tests: (1) burning profiles, (2) coal ash sintering strengths, and (3) viscosity temperature relationship of coal ash were used to distinquish the difference in the behavior of these coals. Three generating stations were selected to compare slagging and fouling predictions with soot blower performance. The coals burned at these stations were: (1) a North Dakota lignite, (2) a Montana subbituminous coal, and (3) an Illinois bituminous coal. Excellent results were noted as the observed soot blower performance and the performance predicted by our evaluation of the slagging and fouling characteristics of the coals were in agreement.
Experimental Investigation of a New Concept of Fuel Prevaporization
Authors: Kappler G. , Kirschey G. , Fehler A.
Published: November 2010

The established emission standards for aircraft engines require the development of low emission combustors which incorporate new concepts of fuel prevaporization and pre-mixing systems. At MTU-Muenchen a fuel injection system was designed which greatly suppresses droplet combustion and avoids burning at stoichiometric air fuel ratios. Thereby the large quantities of NO produced at adiabatic peak temperatures are omitted and soot formation as a result of low velocity droplet combustion is avoided. Tests with a combustor incorporating the fuel injection system yielded high combustion efficiencies, improved combustor outlet temperature distributions and low pollutant emissions. Comparing the measured emission indices for CO, NO, and unburned HC with values required for civil aircraft engines showed a promising development potential of achieving the standards.
Film Cooling of Gas Turbine Blades: A Study of the Effect of Large Temperature Differences on Film Cooling Effectiveness
Authors: Paradis M. A.
Published: November 2010

Experiments have been performed on the film cooling of gas turbine blades in order to study the influence of large temperature differences on the effectiveness of film cooling. A two-dimensional flat plate model was tested in a stream of 1000 K combustion gases flowing at between 110 and 170 m/s. The model was cooled on both sides by jets of air coming from flush angled slots. The range of velocity ratios Uc/Ug covered was from 0.3 to 1.7 and the range of blowing rates was between 0.5 and 5. Film cooling effectiveness was measured and boundary layer traverses were performed. It has been found that once radiation and conduction effects are taken into account, the simple equations proposed by previous workers for the constant property case could be used with little error.
Some Adverse Effects of Stress Corrosion in Steam Turbines
Authors: Sperry R. E. , Toney S. , Shade D. J.
Published: November 2010

The performance and reliability of a steam turbine can be seriously impaired by the admission of steam of unacceptable quality. Of particular concern are contaminants such as caustic, chlorides, and sulfides which can promote the occurrence of corrosion attack and stress corrosion cracking. Critical flaw size growth from cracks initiated by the stress corrosion mechanism can result in brittle-type failure. The importance of stress corrosion as one of the failure mechanisms responsible for turbine outages indicates the need for some understanding of the essential aspects of this phenomenon. The metallurgical aspects of stress corrosion cracking, field experiences with turbine components in aggressive steam environments and results of a study of turbine-material behavior in caustic and sulfide environments are discussed. Field experiences discussed are limited to fossil-fueled industrial and small utility turbines. To further emphasize the serious consequences of stress corrosion failures, typical turbine outage times based on our experience are discussed.
Investigation of Squeeze Film Damper Forces Produced by Circular Centered Orbits
Authors: Feder E. , Bansal P. N. , Blanco A.
Published: November 2010

This paper presents the results of an experimental and analytical investigation of the dynamic forces generated by a squeeze film bearing damper constrained to move in circular centered orbits. These orbits were mechanically produced in a specially designed, end sealed, test rig. Aircraft engine damper geometry and operating conditions were simulated. The effect of journal speed, oil viscosity, inlet pressure, and eccentricity ratio on the damper performance was studied. The pressure distributions about the journal were measured for each test condition by high-response diaphragm-type pressure transducers. These pressure profiles were numerically integrated to determine the force components of the squeeze film. Experimental results were compared to an analysis which is summarized in this paper and included the effects of inlet and cavitation pressures. The “long bearing theory” was found to be reasonably accurate in predicting the shape and magnitude of the pressure distribution. Considerable emphasis was directed to the study of the circumferential pressure distributions between 180 deg and 360 deg since aircraft engine dampers generally operate in this region. For the cavitated film (i.e., pressure distributions less than 360 deg), accurate prediction of the damper forces was found to be critically dependent on the effect of inlet and cavitation pressures.
An Efficient, Flexible Arrangement to Generate High Quality Process or Domestic Heat in Recuperative Gas Cycle Power Plants: Application to Helium Direct Cycle Nuclear Power Plants
Authors: Tilliette Z. P. , Pierre B. , Jude P. F.
Published: November 2010

The advantages of gas turbine power plants in general and closed cycle systems under gas pressure in particular for waste heat recovery are well known. A satisfactory efficiency for electric power generation and good conditions to obtain a significant amount of hot water above 100°C lead to a high fuel utilization. However, as in most of projects, it is not much possible to produce high temperature steam or water without significantly decreasing the electricity production. A new method for an additional generation of high quality process or domestic heat is proposed. The basic feature of this method lies in arranging one or two steam generators or preheaters in parallel with the low pressure side of the recuperator. The high total efficiency and the noteworthy flexibility of this system are emphasized. This arrangement is suitable for any kind of heat source, but the applications presented in this paper are related to helium direct cycle nuclear power plants the main features of which are a single 600 MW(e) turbomachine, a turbine inlet temperature of 775°C, no or one intermediate cooling and a primary circuit fully integrated in a pre-stressed concrete reactor vessel.
Fluidic Thermistors or Fluidic Temperature Sensing With Capillaries
Authors: Drzewiecki T. M. , Phillippi R. M.
Published: November 2010

Described in this report is an analytical and experimental investigation of fluidic capillary temperature sensors and subsequent matching to a fluidic laminar gain block. Experimental sensor/gain-block sensitivities of 1.5 kPa/°C were obtained, which compared favorably with the analytical model. Assuming a dynamic range of 104, resolutions of 0.001°C are estimated.
Prediction of Yield in Ductile Materials Operating at Creep Temperatures
Authors: Kurajian G. M. , Na T. Y.
Published: November 2010

Utilizing a thermodynamic approach, this paper provides the designer with formulations and data so that he can obtain or verify, and then employ, the yield strength (or yield point) value he may desire in the design of a particular ductile machine element operating in the creep temperature range. A previous paper by the authors [1] dealt with the prediction of failure of such elements in the range between room temperature and the lower creep temperature. Thus, the present paper in conjunction with [1], and the references in both, is to provide a thermodynamic explanation for failure of such elements operating in elevated temperature environments ranging from room through creep temperatures. Specific applications are taken for three selected categories of steel with good agreement between the theory and experimental data. However, with necessary data, the procedures in this paper, as it was in [1], is expected to be applicable to other ductile metals as well.
Measurements of Quasi-Steady and Unsteady Flow Effects in a Supersonic Compressor Stage
Authors: Gallus H. E. , Bohn D. , Broichhausen K.-D.
Published: November 2010

In the present paper results of measurements are discussed that give a survey of the flow through rotor and stator of a supersonic compressor stage. In order to analyze the flow, piezoelectric and semiconductor transducers are used for measuring the unsteady pressure distributions along the casing on the one hand and schlieren photography procedure and stroboscopic technique for flow visualization on the other. The pressure transducers are mounted at the casing and shifted along the test region by different series of measurements. The effects of the unsteady flow to the stator produced by the rotor, on the behavior of the flow in the stator channels were analyzed. The oscillation of the pressure at the entrance region of the stator is reduced in axial direction by the cascades, so that the amplitudes diminish at the exit region of the stator. Nevertheless the frequency, induced by the rotor, can be well recognized in the unsteady pressure distribution downstream of the stator. These measurements were completed by the visualization of the flow through the stator. The optical system is working by a modified coincidence method. The starting procedure of the stage up to design speed was observed using shadow and schlieren method at continuous and stroboscopic illumination. The development of the shock waves, the shock-boundary-layer-interaction, and the influence of the rotor-wakes to the stator-flow are discussed.
A Procedure for Axial Blade Optimization
Authors: de Neeve P. F. W. , Dukkipati R. V.
Published: November 2010

This paper proposes a method to modify the geometry of an axial blade to obtain a better stress distribution without compromising the aerodynamic design. The method is applied to an axial blade and is most relevant to those blades with a high degree of twist, such as for instance fan blades. The behavior of such blades is described by a finite element shell model. The initial aerodynamic definition of the axial blade is taken as the basic geometry. Variations of geometry are now considered, which maintain the essential aerodynamic characteristics, and the stresses are calculated. The stresses are expressed as a linear function of the geometric variations. A simple search technique is utilized to find the optimum combination of geometric variations. An example of a representative model shows that a quick convergence towards the final geometry is achieved.
The Effects of Diesel Fuel Properties on Performance, Smoke, and Emissions
Authors: Gross G. P. , Murphy K. E.
Published: November 2010

Diesel fuels were blended from selected components to provide aromatics contents from 10 to 57 percent and viscosities from 2.21 to 6.95 cSt (mm2/s) at 100°F (38°C) in a 14 fuel set which included a commercial diesel fuel as a reference fuel. Tests of the fuels were conducted under full load at several speeds and in the Federal 13-mode and smoke-cycle procedures, using a 2-stroke naturally aspirated engine and a 4-stroke turbocharged engine. Fuel properties such as viscosity, aromaticity, cetane number, gravity, distillation points, and heat of combustion, some of which were partially correlated, were examined individually and in combinations as predictors of the engine performance data. The two test engines responded similarly to fuel variables, but with some differences in sensitivity. Power output (bhp) and fuel economy (bhp-h/lb) were correlated with the heats of combustion on volume and weight bases, respectively. Smoke increased with the amount of fuel boiling above 640°F (338°C) and was not apparently affected by fuel aromatic content. Emissions of nitrogen oxides and of nitrogen oxides plus hydrocarbons increased with increasing fuel aromatics by itself or with increasing fuel specific gravity and decreasing fuel 50 percent-distillation temperature. Hydrocarbon emissions decreased with increasing viscosity or cetane number. Carbon monoxide emissions increased with increasing 90 percent-distillation temperature and with decreases in cetane number.
Innovative Design of Ceramic Utility Gas Turbines
Authors: Elkins R. T. , Heath B. B. , Yonushonis T.
Published: November 2010

This paper describes innovative methods of utilizing ceramics in conjunction with a Brown Boveri Type 11 utility gas turbine (70-MW power range) to improve overall cycle efficiency. The compressor of the Type 11 gas turbine is destaged and additional compression is provided by a compressor on a separate shaft driven by a ceramic turbine. The turbine inlet temperature of the ceramic turbine is 2600°F and results in an improvement in cycle efficiency of the Type 11 alone. This concept favors the use of ceramics in that the volume and surface area of the ceramic turbine blades can be kept relatively small (maximum blade heights are approximately 5 in.) which should result in better ceramic reliability. Special consideration is given to utilizing coal-derived gaseous fuel in the system. A candidate turbine design that favors the superior compressive strength of ceramics is presented. The ceramic blades are attached to the inside of a rotating cylinder which is attached to the high-pressure compressor shaft. The cylinder is wrapped with high-strength fibers to contain the growth due to thermal and centrifugal loading. Also, presented is a more conventional turbine design in which the ceramic blades are attached to a rotating disk. The use of ceramics in the combustor is discussed. Ceramic materials for the turbine and combustor are reviewed.
Utilizing Geothermal Resources Below 150 C (300 F)
Authors: Kunze J. F.
Published: November 2010

Except for the steam-dominated geothermal field at Geysers, Calif., the use of geothermal energy in the US has been minimal. We have been so preoccupied with searching for the high temperature resources (above 350 F), for generating electricity, that we have largely ignored the greatest potential for geothermal energy, that at temperatures below 150 C (300 F). These waters are much more abundant than the higher temperature ones, and, therefore, represent 10 or more times as much useable energy than the total of the energy in all the high temperature waters. The problems have, in part, been technological—how to economically convert these lower temperature geothermal waters to useful energy—and in part institutional. This paper describes the last five year’s program, largely centered at the Idaho National Engineering Laboratory, to make it more practical and economical to harness the lower temperature geothermal resources.
A Unique Approach to the Offshore Gas Disposal Problem: Castellon SALS Production Facilities
Authors: O’Neill D. A. , Hoornenborg B. C.
Published: November 2010

This paper outlines the problems, and their solutions, associated with the production, storage and gas disposal facilities of Shell Espana’s successful Single Anchor Leg Storage (SALS) development of the Castellon Field, situated in some 380-ft waterdepth, offshore Eastern Spain. An underwater completed well produces some 10,000 bbl/day, with Gas/Oil ratio of 125 sdf/bbl, via a single-anchor leg mooring system to a weather-vaning tanker, where separation, gas disposal and storage facilities are provided and whence the oil is exported via a shuttle tanker. The separation and storage systems are briefly described but the main interest centers on gas-associated problems since disposal of gas by conventional methods of flaring, venting or dilution was unacceptable if production was to continue uninterruptedly during transfer of oil to the export shuttle tanker. The alternative of closed incinerators adjacent to the funnel was considered and consultation with Holec Gas Generators/Smit Ovens Nijmegen B.V., manufacturers of inert-gas generators, led to modification and extension of Holec’s basic concepts, resulting in their design of closed, water-cooled units acceptable to the vessel’s classification society for mounting on the aft superstructure. The facilities described represent the likely minimum requirements for the production of a small offshore field. The short period between project initiation and first production — some 11 mo — imposed the necessity for using straightforward and reliable equipment and the success achieved underlines the suitability of a tanker-based system, of which the incinerators are seen as an almost integral feature, for the economic development of small or marginal fields for which more conventional methods are not viable.
The Surface Heat Balance in Simulations of Permafrost Behavior
Authors: Miller T. W.
Published: November 2010

This paper presents a surface heat balance simulator that models the complex heat-exchange mechanisms (e.g., radiation, convection) that govern the amount of heat flowing through the ground surface. It can be used integrally with a 2-D Permafrost Heat Transfer Program [6] to implicitly calculate ground surface temperatures based on climatic conditions, surface characteristics, and soil thermal properties. Thus it provides a rational means of predicting disturbed permafrost temperatures and of designing thermal protection systems to minimize thermal disturbances. The power of the surface simulator method is demonstrated by investigating thermal disturbances and various permafrost protection schemes for both arctic and subarctic conditions, and these demonstrations show some unique differences in permafrost thermal behavior in these two regimes.
The Economics of Energy Recovery From Industrial Waste Incineration
Authors: Lombard W. K.
Published: November 2010

The equipment technology to incinerate and in turn recover energy from industrial wastes is reasonably well documented via the manufacturers of the equipment involved. The difficult question for the industrial plant manager is whether the capital investment and operating costs are economically justified. This paper will review the styles of incineration and heat recovery systems which are typically applied to industrial wastes – solids, liquids, and gases – and then assess the quantity and type of waste materials which are needed to make the cost of installing that equipment economically justified.
Measurements of the Terminal Velocity of Bubbles Rising in a Chain
Authors: Marks C. H.
Published: November 2010

Measurements were made of the effect of frequency of formation on the velocity of air bubbles rising in a chain through distilled water, lap water, and sugar water. In all cases, increasing the frequency increased the rise velocity for a given bubble size. Measurements made in distilled water showed that the increase of velocity with frequency dropped off with bubble size until it was negligible for the smaller bubbles. It was shown that the variation of bubble velocity with frequency and size can be fairly well correlated with the velocity of rise of solitary bubbles by means of a model based on turbulent wake theory. Tap-water measurements showed the same effect of impurities in the water on the bubble rise velocity as had been observed for solitary bubbles; however, the bubble radius at which the effect became apparent decreased with frequency. Measurements made in sugar water showed that the effect of fluid properties on the rise velocity decreased as frequency increased. At the highest frequencies, no difference could be seen between the distilled water and the sugar water rise velocity curves.
Experimental and Analytic Data Correlation Study of Water Column Separation
Authors: Safwat Hemmat H. , Van Den Polder Jaap
Published: November 2010

Hydraulic transients in a short horizontal pipeline resulting from the closure of a valve at the upstream end of the pipe were examined. Test conditions resulted in water column separation at the valve. Measurements of transient pressure and velocity changes for a number of tests are presented. Calculated results based on the method of characteristics are compared with the measurements. Special attention was devoted to the evaluation of the dynamic behavior of the valve.
Oscillatory Flow Phenomena in Diffusers at Low Reynolds Numbers
Authors: Stenning A. H. , Schachenmann A. A.
Published: November 2010

In studies of a diffuser operating with inlet flow oscillations, it has been found that large amplification of the inlet velocity oscillations occurs within the diffuser when the throat Reynolds number lies in the range 103 to 104. This phenomenon is caused by travelling waves in the wall boundary layer which are initiated in the laminar portion of the boundary layer and propagate into the turbulent boundary layer, causing large variations in the displacement thickness.
Leakage and Frictional Characteristics of Turbulent Helical Flow in Fine Clearance
Authors: Bilgen E. , Boulos R. , Akgungor A. C.
Published: November 2010

The leakage and frictional characteristics of helical flow in concentric cylinders with fine clearance have been studied for the ratio of clearance to radius from 0.0006 to 0.0127 and the ratio of length to clearance from 20 to 750. The Reynolds number based on the axial velocity was from zero to 104 and the Reynolds number based on the radius and tangential velocity was from 103 to 3 × 105. These geometrical and kinematical conditions are usually encountered in the seal design of turbomachines. The leakage and the frictional torque have been measured with a 20 in. dia test rig for various pressure gradients and different rotational speeds of the inner cylinder. The case of zero pressure gradient has also been included. The experimental data and those published in the literature have been analyzed and correlated in the form of empirical equations.
Cryptosteady-Flow Energy Separation
Authors: Foa J. V.
Published: November 2010

The mechanism of cryptosteady-flow energy separation is described and analyzed in its most general form, with full consideration of the effects of bearing friction or other rotor torque, and of such asymmetries as unequal discharge pressures, peripheral velocities, flow losses, prerotation velocities, and discharge angles. Equations are also developed for the proportioning of rotor nozzles in accordance with performance specifications.