bluuebunny/crossref_metadata_2025 huggingface dataset:
Steam-Cooled Gas Turbine Casings, Struts, and Disks in a Reheat Gas Turbine Combined Cycle: Part II—Gas Generator Turbine and Power Turbine
Authors: Rice I. G.
Published: October 2009

High-cycle pressure-ratio (38–42) gas turbines being developed for future aircraft and, in turn, industrial applications impose more critical disk and casing cooling and thermal-expansion problems. Additional attention, therefore, is being focused on cooling and the proper selection of materials. Associated blade-tip clearance control of the high-pressure compressor and high-temperature turbine is critical for high performance. This paper relates to the use of extracted steam from a steam turbine as a coolant in a combined cycle to enhance material selection and to control expansion in such a manner that the cooling process increases combined-cycle efficiency, gas turbine output and steam turbine output.
Gas Turbine Compressor Interstage Cooling Using Methanol
Authors: Fortin J. A. C. , Bardon M. F.
Published: October 2009

An earlier study demonstrated the theoretical potential of the concept of injecting methanol into a gas turbine compressor inlet as a means of increasing cycle thermal efficiency. To attain the full potential of such a system, continuous shifting vapour/liquid equilibrium is required which would pose formidable difficulties in practice due to the presence of liquid in the compressor blading. This study evaluates a more practicable configuration in which the alcohol is injected between stages of a multistage machine so that, due to the higher air temperatures, evaporation is complete before the mixture enters subsequent stages. Through a computer analysis, it is shown that this arrangement would retain most of the potential of the concept while greatly reducing the design and operating problems.
Thermodynamic Models for Pipeline Gas Turbine Diagnostics
Authors: Saravanamuttoo H. I. H. , MacIsaac B. D.
Published: October 2009

Thermodynamic models suitable for use as diagnostic tools for pipeline gas turbines have been developed. A basic requirement was the prediction of the performance of gas turbines subject to in-service deterioration, including effects such as compressor fouling, foreign object damage, and turbine damage. This was met by creating thermodynamic models capable of operation over the complete running range expected, with a provision for introducing arbitrarily controlled degradations. Models for a variety of types of gas turbines currently in pipeline use have been tested, demonstrating good agreement with user experience. The models are extremely flexible in use and may be used either for investigation of specific problems or to increase user understanding of operating problems.
Aerodynamic Tests on Centrifugal Process Compressors—the Influence of the Vaneless Diffusor Shape
Authors: Ludtke K.
Published: October 2009

Shop performance tests were conducted on a four-stage industrial centrifugal compressor. The first stage consisted of a radial plenum inlet, an open inducer type impeller with high hub/tip ratio and radial exit blades, a short vaneless diffuser, and a scroll including a conical diffuser. These stages with high flow coefficients and high tip speed Mach numbers are sometimes used as a first stage with multistage process compressors to increase the volumetric capacity of the given casing and reduce the number of stages. We have four versions of the vaneless diffuser with a radius ratio of 1.46: wide parallel walled, narrow parallel walled, constant area tapered, and reduced area tapered. The influence of these modifications was tested within a tip speed Mach number range of 0.94 to 1.07. Improvement of turn-down was obtained by narrowing and tapering. But the two extremely narrow diffusers reduced the rated point efficiencies beyond acceptable limits. The wide parallel walled diffuser has the highest efficiency and the most unfavorable surge, whereas the constant area diffuser achieved 10 percent better surge without practically any detrimental effects on efficiency.
Aerodynamic Tests on Centrifugal Process Compressors—Influence of Diffusor Diameter Ratio, Axial Stage Pitch, and Impeller Cutback
Authors: Lindner P.
Published: October 2009

Almost all process compressors manufactured today are built in accordance with the fixed geometry modular system. It is not always possible to accurately predict the operational behavior of a compressor, particularly in such cases where a deviation from the standard solution is advisable or even necessary. This paper describes and analyses by means of experimental measurements the influence of three different stage modifications (axial stage pitch, shortening of the vaneless annular diffusor, blading cut-back). The results given here are directly related to engineering practice as they enable the design engineer to apply realistic efficiences even for modified stages in the early planning stage.
A New Look at Performance Analysis of Centrifugal Compressors Operating With Mixed Hydrocarbon Gases
Authors: Nathoo N. S. , Gottenberg W. G.
Published: October 2009

A program was undertaken to examine the thermodynamic performance of multistage centrifugal compressors operating with hydrocarbon gas mixtures. Experimental aspects included methods for accurate measurement of such variables as the pressure and temperature of the process gas stream before and after each compressor stage and the acquisition of gas samples and their analysis. Emphasis was placed on development of an analytical technique using an equation-of-state representation for the gas mixture to evaulate its thermodynamic properties. This permitted integration of the exact thermodynamic equations developed by Schultz in 1962 for describing the compression path of the gas stream. The effect of the variation of the so called polytropic volume exponent, n, on the performance parameters was examined. The special case of the polytropic path, i.e., n considered a constant, was shown to be acceptable in most practical applications. The technique was validated by examples of field tests and by comparison with test cases reported in the literature.
Component Synthesis of Multicase, Rotating Machinery Trains by the Generalized Receptance Approach
Authors: Palazzolo A. B. , Wang Bo Ping , Pilkey W. D.
Published: October 2009

A method is presented for computing the eigenvalues of multicase, coupled, rotating machinery trains. The method is based on a synthesis technique which utilizes generalized receptance formulas, previously derived by the authors. These formulas improve the accuracy of the computed receptance when only an incomplete set of modes is available. A nonsynchronous, gyroscopic, two-rotor example is examined to illustrate the synthesis procedure.
Aerodynamic Design of Fixed and Variable Geometry Nozzleless Turbine Casings
Authors: Chappie P. M. , Flynn P. F. , Mulloy J. M.
Published: October 2009

A design method has been developed to produce nozzleless turbine casings which provide a centrifugal turbine wheel with a uniform inlet state. The analysis includes the effect of wall friction and has been found to accurately predict the mass flow versus pressure ratio characteristics of nozzleless casings. The uniform inlet state provided by this design approach provides turbine wheel/casing configurations with near optimum efficiency and a very low aerodynamic blade vibration excitation level. The model has been extended to produce variable area casings to simulate a simplified variable casing geometry. Testing has verified the accuracy of the approach both in the design point and variable geometry cases. Also depicted are new insights into turbine wheel design constraints discovered when using a variable geometry turbine casing.
Study of Metals Erosion in High Temperature Coal Gas Streams
Authors: Tabakoff W. , Hamed A. , Ramachandran J.
Published: October 2009

In order to provide the basis for alloy selection in future turbines using pulverized coal, an investigation is undertaken to obtain a basic understanding of the mechanisms of erosion at high temperatures. The test equipment has been designed to simulate the aerodynamic and thermodynamic conditions in the turbine. This facility has the capability of providing between ambient and a 1093°C (2000°F) environment temperature for erosion testing of various materials. The effects of high temperature on the erosion rate was determined and the test results from 304 stainless steel alloy are presented.
Blade-Row Interaction in an Axial-Flow Subsonic Compressor Stage
Authors: Gallus H. E. , Lambertz J. , Wallmann Th.
Published: October 2009

This paper contains the results of the measurements of fluctuating pressures on the mid-span profile surfaces of both rotor and stator blades for several points of operation. By the aid of rotating probes behind the rotor, the shapes of the rotor wakes were measured, too. All the measurements have been performed twice, at first with guide vanes in front of the rotor, and afterwards without the latter. The results of the measurements are evaluated with respect to the parameters involved, like Strouhal-number, reduced frequency, and circumferential Mach number. The flow analysis is done for various wake-fields behind the rotor correspondent to different operation points. Emphasis is given to the establishment of correlations for the blade-row interaction and to the comparison of the measured pressure distributions with computed results according to well-known theoretical approaches.
Acoustics and Performance of High-Speed, Unequally Spaced Fan Rotors
Authors: Fujii S.
Published: October 2009

This paper describes an experimental measurement of the effects of uneven blade spacing on the acoustic and aero-thermodynamic characteristics of high-speed, high-pressure-ratio fan rotors at two selected spacing configurations. A test rig, consisting of inlet guide vanes and transonic rotor blades, was employed to explore the redistribution of harmonic sound energy into a series of multiple tones of lower sound pressure level. The measured data indicated that a ten percent modulated rotor exhibited a six to eight decibel decrease in the sound pressure level as compared with the original first blade passage frequency harmonic. Disadvantages in aerodynamic performance resulting from spacing modulation were not so unfavorable for the ten percent modulated blades. However, with five percent modulated blades, serious deterioration in aerodynamic performance was observed particularly near the blade tip section, which produced an unfavourable acoustic signature. A calculation method, assuming a pulse event for each blade sound pressure, provided agreeable results with the measured data.
Nonlinear Dynamic Model of a Fluidized-Bed Steam Generation System
Authors: Ray A. , Berkowitz D. A. , Sumaria V. H.
Published: October 2009

A dynamic model of an atmospheric pressure fluidized-bed steam generation system is presented which allows digital simulation and analytical controller design. The nonlinear, time-invariant, deterministic, continuous-time model is derived in state-space form from conservation relations, empirical correlations and system design data. The model has been verified for steady-state and transient performance with measured data from experimental test runs. Transient responses of several process variables, following independent step disturbances in coal feed rate and air flow, are illustrated.
On Flame Stabilization by Bluff-Bodies
Authors: Kundu K. M. , Banerjee D. , Bhaduri D.
Published: October 2009

Flame stabilization by bluff-bodies has been investigated to highlight the role of recirculation zone on the phenomenon. It has been observed that close correlations exist between heat exchange from recirculation zone and flame stability as controlled by recirculation strength.
Axial-Flow Compressor Turning Angle and Loss by Inviscid-Viscous Interaction Blade-to-Blade Computation
Authors: Hansen E. C. , Serovy G. K. , Sockol P. M.
Published: October 2009

A method for computation of the flow field around an arbitrary airfoil cascade on an axially symmetric blade-to-blade surface was developed which takes into account the development and separation of the blade surface boundary layers and mixing in the wake. The method predicts the overall fluid turning and total pressure loss in the context of an inviscid-viscous interaction scheme. The inviscid flow solution is obtained from a compressible flow matrix method. The viscous flow is obtained from a differential boundary layer method which calculates laminar, transitional and turbulent boundary layers. Provisions for the calculation of laminar and turbulent separation regions were added to the viscous scheme. The combined inviscid-viscous interaction scheme described yields results which are quantitatively consistent with experimental data. This suggests that the physical basis for the interactive system is correct and justifies continued exploration and use of the method.
Experimental and Analytical Investigation of the Effects of Reynolds Number and Blade Surface Roughness on Multistage Axial Flow Compressors
Authors: Scha¨ffler A.
Published: October 2009

The general effect of Reynolds Number on axial flow compressors operating over a sufficiently wide range is described and illustrated by experimental data for four multistage axial compressors. The wide operating range of military aircraft engines leads in the back stages of high pressure ratio compression systems to three distinctly different regimes of operation, characterized by the boundary layer conditions of the cascade flow: • laminar separation, • turbulent attached flow with hydraulically smooth blade surface, • turbulent attached flow with hydraulically rough blade surface. Two “critical” Reynolds Numbers are defined, the “lower critical Reynolds Number” below which laminar separation occurs with a definite steepening of the efficiency/Reynolds Number relation and an “upper critical Reynolds Number” above which the blade surface behaves hydraulically rough, resulting in an efficiency independant of Reynolds Number. The permissible blade surface roughness for hydraulically smooth boundary layer conditions in modern high pressure ratio compression systems is derived from experimental data achieved with blades produced by grinding, electrochemical machining and forging. A correlation between the effect of technical roughness and sand type roughness is given. The potential loss of efficiency in the back end of compression systems due to excessive blade roughness is derived from experimental results. The repeatedly experienced different sensitivity of front and back stages towards laminar separation in the low Reynolds Number regime is explained by boundary layer calculations as a Mach Number effect on blade pressure distribution, i.e. transonic versus subsonic flow.
Computation of Supercritical Compressor and Turbine Cascades with a Design Method for Transonic Flows
Authors: Schmidt E.
Published: October 2009

The development of supercritical cascades follows experience with supercritical single profiles. In cascade arrangement strong inter-blade influences exist in the transonic region, so that a desired pressure distribution, starting from the contour shape, is not easy to realize. For these cases, a design method has been developed in which the boundary conditions can be prescribed in a simple and clear manner. Thickness and deflection are not restricted, since the full potential equation is treated. Variation of the axial velocity density ratio is provided for. The solution by relaxation leads to short computing times. Experimental comparisons for turbine and compressor cascades show the applicability of the method.
Study of Mean- and Turbulent-Velocity Fields in a Large-Scale Turbine-Vane Passage
Authors: Bailey D. A.
Published: October 2009

Laser-Doppler velocimetry was used to investigate the secondary flow in the endwall region of a large-scale turbine inlet-guide-vane passage. The mean and turbulent velocities were measured for three different test conditions. The different test conditions consisted of variations in the blade aspect ratio and the inlet boundary-layer thickness or all three cases, a passage vortex was identified and its development documented. The turbulent stresses within the vortex were found to be quite low in comparison with the turbulence in the inlet boundary layer.
Utilization of the Cold by LNG Vaporization With Closed-Cycle Gas Turbine
Authors: Krey G.
Published: October 2009

In the course of the world-wide efforts to save energy, the utilization of cold in connection with the regasification of liquefied natural gas gains more and more importance. The aim is the partial recovery of the energy consumed in liquefaction. There are particular advantages when using the closed-cycle gas turbine, in which the exergy of the liquefied natural gas is transformed to electrical energy with a very high efficiency. The paper deals with the optimization, design, and operational behavior of such a plant.
The Influence of the Blading Surface Roughness on the Aerodynamic Behavior and Characteristic of an Axial Compressor
Authors: Bammert K. , Woelk G. U.
Published: October 2009

The conversion of energy in an axial compressor is influenced in great measure by the surface quality of the blading. To achieve low flow losses, the roughness values of the blade surface must be below certain limits. However, the blade surface, which is hydraulically smooth on commissioning of the machine, is in many cases attacked by dirt, corrosion and erosion during operation. For investigation of the influence of the surface quality on the efficiency, flow rate, pressure ratio, and the shifting of the characteristic curves, systematic measurements were taken on a three-stage axial compressor with smooth and uniformly rough blading. The roughness was produced by applying loose emery grain of different grades.
Development Progress on the Atmospheric Fluidized Bed Coal Combustor for Cogeneration Gas Turbine System for Industrial Cogeneration Plants
Authors: Holcomb R. S.
Published: October 2009

The Atmospheric Fluidized Bed Coal Combustor Program will develop the technology for a fluidized bed coal combustion system to provide a source of high temperature air for process heating and power generation with gas turbines in industrial plants. The gas turbine has the advantages of a higher ratio of electric power output to exhaust heat load and a higher exhaust temperature than do steam turbines in cogeneration applications. The program is directed toward systems in the size range of 5 to 50 MW(e) and is sponsored by the Department of Energy. A study of industrial energy use has been completed that indicates a large potential market for gas turbine cogeneration systems. Conceptual design studies have been done for typical industrial’ installations, and some of these results are presented. The conceptual design of a 300 kW(e) test unit has been completed. A number of furnace design firms have been invited to submit their own designs for a 1500 kW(t) (5 × 106 Btu/hr) combustor, from which a final selection will be made. The design of the balance of the test system will proceed in parallel with the combustor design. An engineering design study has been completed by AiResearch Division of Garrett Corporation in which the modifications required to adapt an existing AiResearch 831-200 gas turbine to this cycle for both open and closed cycle operation were determined. Development and testing have been conducted in the areas of fluidization, heat transfer, tube corrosion and coal feeding. Results from heat transfer, tube corrosion, and coal feeding tests are presented.
Friction Damping of Resonant Stresses in Gas Turbine Engine Airfoils
Authors: Griffin J. H.
Published: October 2009

The resonant response of a turbine airfoil attenuated through use of a Coulomb damper is analyzed. Parameters that control the damper’s effectiveness are identified and characteristics of an optimized system are described. The results of the analysis are confirmed by laboratory tests.
The Time-Variant Aerodynamic Response of a Stator Row Including the Effects of Airfoil Camber
Authors: Fleeter S. , Bennett W. A. , Jay R. L.
Published: October 2009

An experimental investigation was conducted to quantitatively determine the validity and applicability of state-of-the-art transverse gust cascade analyses. This was accomplished by obtaining fundamental time-variant forced response data at realistic values of key parameters in a large-scale, low-speed, single-stage research compressor. The forcing function, the velocity defect created by the rotor blade wakes, was measured with a crossed hot-wire probe. The resulting time-variant aerodynamic response was measured by means of flush mounted high response pressure transducers on both flat plate and cambered airfoil stator vane rows over a wide range of incidence angles. These dynamic data were then analyzed to determine the chordwise variation of the unsteady pressure difference in terms of a dimensionless dynamic pressure coefficient and an aerodynamic phase lag referenced to a transverse gust at the leading edge of the vanes. These dimensionless pressure difference data were all correlated with predictions obtained from a state-of-the-art compressible transverse gust, flat plate cascade analysis. Correlation of the classical flat plate unsteady data with the predictions permitted the range of validity of the analysis to be assessed in terms of incidence angle. Correlation of the cambered vane unsteady data with those for the flat plate and with the predictions allowed the effects of airfoil camber as well as the applicability of the flat plate prediction to realistic cambered airfoils to be quantitatively determined.
Aerodynamic and Aeroelastic Characteristics of Oscillating Loaded Cascades at Low Mach Number—Part I: Pressure Distribution, Forces, and Moments
Authors: Atassi H. , Akai T. J.
Published: October 2009

A complete theory is developed in Part I of these two papers for the analysis of oscillating airfoils in cascade in uniform incompressible flows. The theory fully accounts for the geometry of the airfoils and cascade parameters. It is shown that the strong mean velocity gradient near the leading edges of the airfoils significantly affects the unsteady pressure, forces and moments acting upon the airfoils. In Part II the aeroelastic characteristics of a loaded cascade are investigated for one and two degrees of freedom oscillations.
Modal Analysis of Gas Turbine Buckets Using a Digital Test System
Authors: Nied H. A.
Published: October 2009

A modal analysis was conducted on gas turbine buckets using a digital Fourier analyzer. This digital test/computer system measures a set of frequency response functions for broadband impulse excitation at successive locations on the bucket airfoil. From the set of frequency response functions, the analyzer computes the modal parameters used to determine the natural frequencies, critical damping ratio and mode shapes of the turbine buckets. An animated display of the mode shapes for a discrete experimental model graphically revealed compound modes due to coupling. The test has shown that the digital modal analysis using the impulse excitation technique is a rapid and precise experimental method to determine the modal parameters of turbine buckets with a high degree of repeatability.
Removal of Gaseous Alkali Metal Compounds from Hot Flue Gas by Particulate Sorbents
Authors: Lee S. H. D. , Johnson I.
Published: October 2009

Six commercially available materials have been tested as granular sorbents to be used in granular-bed filters for the removal of gaseous alkali metal compounds from the hot (1073 to 1153 K) flue gas of pressurized fluidized-bed combustors (PFBC) for proposed combined-cycle power generation. Tests were performed using a simulated dry flue gas of PFBC in a laboratory-scale, fixed-bed combustor. Diatomaceous earth and activated bauxite were found to be the two most promising sorbents. The experimental results of screening tests are presented, along with the effects of temperature and superficial velocity and space velocity of the flue gas on the sorption performance for the two sorbents. Possible sorption mechanisms, applications of the sorbents and preliminary cost evaluations are discussed.
Weak Extinction Limits of Turbulent Heterogeneous Fuel/Air Mixtures
Authors: Ballal D. R. , Lefebvre A. H.
Published: October 2009

Experimental and theoretical studies are made of the factors governing the weak extinction limits of stabilized flames supplied with flowing mixtures of liquid fuel drops and air. The test program includes wide variations in inlet air pressure, velocity and turbulence level, and also covers wide ranges of fuel volatility and mean drop size. The influence of flameholder size and blockage is also examined. An equation is derived for predicting weak extinction limits which shows good agreement with the corresponding experimental values.
A Partial Oxidation Staging Concept for Gas Turbines Using Broadened Specification Fuels
Authors: Clayton R. M.
Published: October 2009

A concept is described for using a very fuel-rich partial oxidation process as the first stage of a two-stage combustion system for onboard processing of broadened specification fuels to improve their combustion characteristics. Results of an initial step in the experimental verification of the concept are presented, where the basic benefits of H2 enrichment are shown to provide extended lean-combustion limits and permit simultaneous achievement of ultralow levels of NOx, CO, and HC emissions. The H2 required to obtain these results is within the range available from a partial oxidation precombustion stage. Operation of a catalytic partial oxidation reactor using a conventional aviation turbine fuel (JP5) and an unconventional fuel (blend of JP5/xylene) is shown to produce a “fuel gas” stream with near-theoretical equilibrium H2 content. However, a number of design considerations indicate that the precombustion stage should be incorporated as a thermal reaction.
The Effects of LBG Composition and Combustor Characteristics on Fuel NOx Formation
Authors: Folsom B. A. , Courtney C. W. , Heap M. P.
Published: October 2009

The low Btu gas (LBG) combined gas and steam turbine power cycle is a potentially attractive alternative to the direct coal fired steam cycle because of the potential for low sulfur emissions and high overall cycle efficiency. However, LBG may contain ammonia (NH3) which could be converted to nitrogen oxides (NOx) under typical combustion conditions. This paper examines the effects of LBG composition and combustor design on NOx emissions. Low Btu gases of varying compositions were synthesized from bottled gases and fired in three atmospheric pressure flame reactors: diffusion flame reactor, flat flame reactor and catalytic reactor. Nitrogen oxide emissions were found to be most sensitive to the concentrations of NH3 and hydrocarbon fuel gas in the synthetic LBG. Lowest NOx emissions were produced by the diffusion flame reactor operating at near stoichiometric conditions and the catalytic reactor operating fuel rich.
Design and Testing of a Cavity-Type, Steam-Generating, Central Receiver for a Solar Thermal Power Plant
Authors: Zoschak R. J. , Wu S. F. , Gorman D. N.
Published: October 2009

This paper focuses on the design and operating aspects of a 10-MWe cavity-type, natural-circulation, steam-generating receiver for a central-receiver thermal power plant. The development of the receiver concept and the basic design features are described. The solar energy input analysis, thermal/hydraulic performance, and structural design of the receiver are discussed along with its control concept and transient operation. The design, construction, and testing of a 5-MWt scaled-down version of the 10-MWe receiver are summarized with emphasis on test objectives, scaling criteria, and design similarities to the full-scale receiver.
Double-Row Discrete-Hole Cooling: an Experimental and Numerical Study
Authors: Bergeles G. , Gosman A. D. , Launder B. E.
Published: October 2009

Double-row discrete-hole cooling arrangements offer several advantages over single-row systems yet the detailed cooling mechanism is less completely understood than for the single-row. This is partly because there have been fewer studies of this geometry and partly because the flow structure is more complex. The present paper presents detailed flow-field and concentration measurements around the injection holes for double-row injection on a flat plate at 30 deg to the mainstream. The experiments span values of the blowing injection mass velocities from 0.25 to 1.0 times the free stream mass velocity and for two boundary layer thicknesses just upstream of the injection. In contrast to single-row injection the cooling effectiveness rise monotonically with M over the range studied. Computer simulation of these flows and similar experiments of [7] has been made using a three-dimensional finite-difference code that embodies a semi-elliptic treatment of the flow field in the neighborhood of the injection holes in conjunction with a two-equation turbulence model with non-isotropic effective transport coefficients. It emerged from the calculations, that, for injection velocities up to 50 percent of the free stream value, levels of film-cooling effectiveness are extremely well predicted beyond about 10 diameters behind the leading row of holes. Around the holes themselves, however, there are certain discrepancies which become more serious as the injection level is raised.
The Effect of Material Properties on the Thermal Efficiency of the Minto Solar Wheel
Authors: Lin S. , Bhardwaj R.
Published: October 2009

The characteristic of the thermal performance of the Minto solar wheel is that its thermal efficiency is strongly dependent on the material properties of the working fluid. For a specified working fluid, the thermal efficiency of the ideal cycle of the Minto solar wheel is dependent only on the mean diameter of the wheel. To study the effect of the material properties of the working fluid on the ideal thermal efficiency, 14 working fluids are selected, and their thermal efficiencies as functions of the mean diameter of the wheel are calculated and compared with each other. Among these fluids, R-12, R-115, R-500, R-22 and R-13B1 achieve better thermal performance than the others.
Production of Photovoltaic Devices
Authors: McGinnis R.
Published: October 2009

This paper will provide a broad overview of present and future activities important for the production of Photovoltaic modules. First, the current methods for production will be reviewed, then a study of the techniques for further development will lead to an attempt to describe the factory of the future for Photovoltaic device production. The paper will look at the issues and technologies for the conversion from high purity quartz to silicon substrates and will then analyze processes from substrates to finished solar cells, and finish by reviewing the concepts for the manufacturing of the Photovoltaic modules.
Designing Reliability into High-Effectiveness Industrial Gas Turbine Regenerators
Authors: Valentino S. J.
Published: October 2009

The increased demand for fuel conservation has provided the impetus for higher efficiency in the design of gas turbines and their operation. To conserve more fuel, regenerators must operate at higher temperatures and pressures, and must experience frequent on-off cycles. The design concept, methodology, and full-scale testing leading to the final design of the regenerator will be presented. Particular emphasis will be given to the importance of meaningful testing of both the regenerator and materials used. The necessity of having materials data, in the as-processed condition versus catalog data, for reliable design, is also presented.
Account of Film Turbulence for Predicting Film Cooling Effectiveness in Gas Turbine Combustors
Authors: Sturgess G. J.
Published: October 2009

The paper deals with a small but important part of the overall gas turbine engine combustion system and continues earlier published work on turbulence effects in film cooling to cover the case of film turbulence. Film cooling of the gas turbine combustor liner imposes certain geometric limitations on the coolant injection device. The impact of practical film injection geometry on the cooling is one of increased rates of film decay when compared to the performance from idealized injection geometries at similar injection conditions. It is important to combustor durability and life estimation to be able to predict accurately the performance obtainable from a given practical slot. The coolant film is modeled as three distinct regions, and the effects of injection slot geometry on the development of each region are described in terms of film turbulence intensity and initial circumferential non-uniformity of the injected coolant. The concept of the well-designed slot is introduced and film effectiveness is shown to be dependent on it. Only slots which can be described as well-designed are of interest in practical equipment design. A prediction procedure is provided for well-designed slots which describes growth of the film downstream of the first of the three film regions. Comparisons of predictions with measured data are made for several very different well-designed slots over a relatively wide range of injection conditions, and good agreement is shown.
Ongoing Development of a Low Emission Industrial Gas Turbine Combustion Chamber
Authors: Sood V. M. , Shekleton J. R.
Published: October 2009

Experiments were performed in laboratory-and full-scale combustors to test the feasibility of meeting proposed EPA emission standards. It was found that by uniformly mixing gaseous fuel and primary zone air prior to combustion and burning fuel leanly (equivalence ratio <1.0), it was possible to meet the proposed emission standards in an industrial gas turbine. The characteristic narrow range of flame stability obtained with lean premix combustion necessitated the use of fuel staging or variable geometry to handle the operational range of the engine. Fuel staging was selected for its relative simplicity. Consequently, EPA proposed emission standards were met only over a narrow range covering the engine operation at and near the design point. Experiments on small scale models of various sizes operated with gaseous and liquid fuels showed that, contrary to expectation, NOx production from a lean premix combustion system is independent of the system pressure in the pressure range investigated (1 atm to 16 atm). The desirability of high combustor inlet temperature and pressure for premixing was indicated. Despite the complexities of premixing fuel and air, such a combustion system, in addition to meeting the proposed emission standards, offers advantages such as easing of combustor wall cooling problems, improved combustor exit temperature distribution, and freedom from exhaust and primary zone smoke.
An IHX Design for Pool Type LMFBR System Application
Authors: DeFur D. D.
Published: October 2009

This paper presents the design of a 500 MWt Intermediate Heat Exchanger (IHX) for application in a multi-zone pool-type Liquid Metal Fast Breeder Reactor System. The primary feature around which this design was developed is the ability to function under all steady-state and transient conditions without the need for a distinct mechanical feature to accommodate differential thermal expansion between the tube bundle and shell. This is accomplished by using thermal baffles and judiciously adjusting the ratio of shell length in contact with the hot and cold pools of the multi-zone reactor. Thus, the component shell is maintained at a higher temperature than the tube bundle and the tubes are basically tension members. Under certain transient conditions the tubes heat up and become compression members but are not loaded to the point of buckling. A secondary, but not less significant, feature is the low primary side pressure drop and good flow distribution offered by this design. (Multi-zone reactor systems have no hard piping between the IHX outlet and primary pump inlet; therefore, the relatively small differential head of sodium between the two pools is the only driving element which causes flow through the primary side of the IHX. For this reason, a low primary side pressure drop is essential). To accomplish this, the primary sodium flows through the tube side of the component where the flow channel is simple and unimpeded by tube supports or other restrictions. Secondary flow distribution, through the shell side of the unit, can be adjusted as required since a higher pressure drop can be tolerated.
A High Reliability Straight Tube LMFBR Steam Generator Design
Authors: Spring A. H. , DeFur D. D.
Published: October 2009

Straight-tube counterflow steam generators for LMFBR applications have been proposed, tested, fabricated and operated with varying degrees of success. A new embodiment of the straight-tube concept is described which incorporates a number of unique features which contribute to high reliability and availability. These features include a replaceable bellows for accommodation of differential thermal expansion between shell and tubes and a redundant, crevice-free tube-to-tubesheet joint design. The design can also easily incorporate single-wall or double-wall tubes. Single and double-wall tube versions are described whose thermal and geometric size are based on anticipated manufacturing limitations. The results of scoping tests of the tube-to-tubesheet welds are described which provide positive indications of the soundness of the weld design.
The Flow and Film Cooling Effectiveness Following Injection through a Row of Holes
Authors: Foster N. W. , Lampard D.
Published: October 2009

Using a mass transfer technique, detailed studies have been made of the effectiveness and flow downstream of a row of holes in the flat floor of a wind tunnel. The effects of variation of injection angle, upstream boundary layer, and hole spacing are described, and an assessment of the relative aerodynamic penalties is made. A small injection angle is shown to give the best cooling effectiveness at low blowing ratio while large injection angles are best at high blowing rates. Increasing the upstream boundary layer thickness reduces the effectiveness due to enhanced lateral mixing and film dilution. Small hole spacings give improved lateral coverage and alleviate jet lift-off effects.
Matching of Turbocomponents Described by the Example of Impeller and Diffuser in a Centrifugal Compressor: Part I—Aerothermodynamic Coupling of Impeller and Diffuser. Part II—Optimized Stage Efficiency of a Centrifugal Compressor
Authors: Bammert K. , Rautenberg M. , Wittekindt W.
Published: October 2009

An important task in the design of turbo machinery is the determination of the aerothermodynamic parameters necessary to assure optimum matching of the individual compressor components. With centrifugal compressors, the problem is to design impeller and diffuser such that a maximum overall efficiency is achieved for the desired design point. For this purpose, a mathematical model is developed coupling the individual component efficiencies. In the first part of this paper, the aerothermodynamic bases are derived and the coupling equation is illustrated. In the second part, a solution is displayed for the complex problem of matching the impeller and the vaneless diffuser of a centrifugal compressor. The solution is obtained by means of a stochastic-mathematical optimization procedure based on the biological evolution strategy.
The Film Cooling Effectiveness of Double Rows of Holes
Authors: Afejuku W. O. , Hay N. , Lampard D.
Published: October 2009

The film cooling effectiveness provided by two rows of holes separated by a range of distances has been studied experimentally using a mass transfer technique. The blowing rates at the two rows were varied independently. The results are presented in forms suitable for design purposes. Spanwise and area averaged effectivenesses are given for a range of blowing rates. Thus optimum blowing rates for a given row spacing and total coolant flow can be established. Comparisons with a simple superposition theory show that this can be used with safety for design purposes if the holes in the two rows are staggered, but restrictions apply if they are in-line.
A Fiber-Optic Laser-Doppler Probe for Vibration Analysis of Rotating Machines
Authors: Cookson R. A. , Bandyopadhyay P.
Published: October 2009

The problem of obtaining vibratory information from remote, rotating, components within a machine has been overcome by means of a laser-Doppler fiber-optic probe. Laser light is transmitted down the fiber-optic and scattered light is returned for analysis in the same way. The Twyman-Green mode of operation of the laser-Doppler system has been shown to have serious shortcomings for this type of work and a new mode has been produced, and used successfully, in conjunction with Bragg cells for frequency shifting. The use of a single set of Bragg cells to compensate for the average velocity of a rotating system, limits the allowable speed of rotation to about 1000 rpm. However, other techniques for frequency shifting are available. An experimental investigation is reported in which a rotating system, consisting of a disk carrying flat cantilever blades, was rotated at about 1000 rpm while one of the blades was excited at 163 Hz. The measured frequency of the vibrating blade was 162.8 Hz and similar accuracy was obtained for the amplitude measurements.
Conceptual Examination of Gas Phase Particulate Formation in Gas Turbine Combustors
Authors: Kesten A. S. , Sangiovanni J. J. , Goldberg P.
Published: October 2009

Recent laboratory studies of droplet combustion indicate the potential for substantial gas phase particulate formation even with single component hydrocarbon fuels. Formation of large particles has been observed in the neighborhood of burning droplet arrays, particularly when the droplets are closely spaced. To provide insight into the potential for particulate formation during the combustion of fuel droplet sprays in gas turbine combustors, a mathematical framework is developed for examining the formation of soot nuclei in droplet combustion. A simplified model of the chemistry of fuel pyrolysis and nuclei formation is used and a series of calculations is made to explore the sensitivity of soot nuclei formation to conditions typical of gas turbine combustion systems.
Effects of Nonuniform Passages on Compact Heat Exchanger Performance
Authors: Shah R. K. , London A. L.
Published: October 2009

Neighboring passages in a compact heat exchanger such as a rotary regenerator are never geometrically identical due to manufacturing tolerances. This passage-to-passage nonuniformity can result in a significant penalty on heat transfer performance with only a small compensating effect of reduced pressure drop. Continuous cylindrical passage geometries, operating with laminar flow, are particularly sensitive to these effects. In this paper, a procedure is outlined to establish the effective friction factors and Nusselt numbers for one fluid side of an exchanger having n different cylindrical passage geometries. Two special cases of longitudinal wall temperature variation are considered corresponding to conditions of Cmin/Cmax of zero and unity. The analysis is presented for both fully developed and developing laminar flow.
Techniques for the Thermal/Hydraulic Analysis of LMFBR Check Valves
Authors: Cho S. M. , Kane R. S.
Published: October 2009

A thermal/hydraulic analysis of the check valves in liquid sodium service for LMFBR plants is required to provide temperature data for thermal stress analysis of the valves for specified transient conditions. Because of the complex three-dimensional flow pattern within the valve, the heat transfer analysis techniques for less complicated shapes could not be used. This paper discusses the thermal analysis techniques used to assure that the valve stress analysis is conservative. These techniques include a method for evaluating the recirculating flow patterns and for selecting appropriately conservative heat transfer correlations in various regions of the valve.
Further Development of an Advanced Low-NOx Combustion System and its Potential Application to Coal-Fired Utility Boilers
Authors: Sommer T. M. , Johnson S. A. , Lindstrom G. D.
Published: October 2009

The Babcock & Wilcox Company (B&W), under contract with the Electric Power Research Institute (EPRI), has designed and tested an advanced staged combustion system on a four million Btu/hr (4.2-million kJ/hr) scale. Results of these tests showed the potential to limit the emission of nitrogen oxides from coal-fired boilers to 100–150 ppm and identified a new kinetic mechanism for NO destruction. Subsequently, the correlations and initial design parameters derived from the small-scale tests were applied to a conceptual commercial system to ensure that this concept was indeed commercially feasible. These design considerations and the favored preliminary arrangement of a low-NOx combustion system will be discussed herein. Before commercializing this concept, however, further research is necessary. Testing on a nominal 50-million Btu/hr (53-million kJ/hr) prototype system is now in progress. Initial results indicate that NOx emission correlations and design parameters will need only slight revisions before the concept is ready for a field demonstration.
Corrosion and Deposits from Combustion of Solid Waste—Part VII: Coincineration of Refuse and Sewage Sludge
Authors: Krause H. H. , Cover P. W. , Berry W. E. , Olexsey R. A.
Published: October 2009

Corrosion probe exposures were conducted in the Harrisburg, Pennsylvania, incinerator to determine the effects of burning low-chloride sewage sludge with municipal refuse. Probes having controlled temperature gradients were used to measure corrosion rates for exposure times up to 816 hours. The effects of exposure time, metal temperature, and gas temperature were studied. The results demonstrated that the addition of the sludge reduced the initial corrosion rates of carbon and low-alloy steels to about half that from refuse alone. Little effect was observed on the rates for Types 310 and 347 stainless steels. An aluminized coating on steel resisted corrosion effectively and offers promise as a cost-effective substitute for expensive alloys. In the range 500–900° F the corrosion rates of carbon steel and T22 increased with temperature while those for the stainless steels decreased. Reducing the flue gas temperature from 1500° F to 1100° F reduced corrosion rates significantly and made them less dependent on metal temperature. The addition of low-chloride sludge to refuse is recommended as a corrosion prevention measure and a waste disposal technique.
The Influence of Liquid Film Thickness on Airblast Atomization
Authors: Rizk N. K. , Lefebvre A. H.
Published: October 2009

The influence of initial liquid film thickness on mean drop size and drop-size distribution was examined using two specially designed airblast atomizers. Both were constructed to produce a flat liquid sheet across the centerline of a two-dimensional air duct with the liquid sheet exposed on both sides to high velocity air. In one case a thin film of uniform thickness was produced by injecting the liquid through a porous plate located just upstream of the atomizing edge. The film thickness, t, was then measured by a needle contact device. In the second design the fuel entered the air stream through a thin slot whose height could be adjusted accurately to vary and control the initial film thickness. Drop sizes were measured by the well-established light-scattering technique. From analysis of the processes involved, and from correlation of the experimental data, it was found that high values of liquid viscosity and liquid flow rate result in thicker films. It was also observed that thinner liquid films produce better atomization, according to the relationship, SMD ∝ t0.38.