bluuebunny/crossref_metadata_2025 huggingface dataset:
The Use of a Powered Model for Subsonic Nacelle Optimization
Authors: Motycka D. L. , DiSabato V. J. , Andersen L. Q.
Published: April 2015

The continual demands for improved technology aircraft propulsion systems require refined wind tunnel model testing techniques to more closely simulate full-scale performance. Toward this end a test program was conducted using a subsonic powered nacelle model to statistically investigate the effect of key geometrical variables on nacelle pressure drag. A comparison of test results with analytical prediction techniques is presented, along with the effects of various design parameters on drag. The advantage of powered nacelle models for obtaining subsonic nacelle pressure drag information is also included.
Actuator Disc Flow Calculated by Relaxation: An Approach to the Analysis Problem of Turbomachinery
Authors: Schröder H. J. , Schuster P.
Published: April 2015

When dealing with axisymmetric rotating flow through turbomachines of a given geometry, the existence of discontinuities, due to incidence at the leading edges of the blades, has to be accepted as a logical consequence of axisymmetry. By introducing special conditions resulting from dynamical equilibrium considerations, a relaxation method has been enabled to cope with these discontinuities.
Some Studies of Front Fans With and Without Snubbers
Authors: Fujii Shoichi
Published: April 2015

Full-scale front fans were designed and tested with satisfactory results. The flow field in passing through the fans was estimated with a powerful method called streamline-curvature technique, and the first test-program was carried out in equipping the rotor blade row without snubbers (part-span shroud) and the second conducted with them. The detailed analyses of the test results showed that the snubbers had some effect on the operation of a fan stage at all locations within the stage and not only in locations locally near to the snubbers.
Review of new Forming Methods Pertinent to the Gas Turbine Industry
Authors: Kularni K. M. , Glenn G. M.
Published: April 2015

In the last few years a number of new metal forming techniques have been developed. Some of these which have a potential for becoming important production processes for gas turbine components are reviewed. For each method, the basic principle is first explained, then its present status is reviewed, and some areas in which additional development work is required are pointed out. Finally, the gas turbine components for which the method may be used are indicated. Processes considered include isothermal forging, contoured cross rolling, squeeze casting, radial forging, form rolling, and forging of powder metallurgy preforms.
Local Heat Transfer Coefficient Distribution With Air Impingement Into a Cavity
Authors: Burggraf F.
Published: April 2015

Impingement heat transfer coefficients are presented for a row of holes impinging into an oval cavity with the spent air leaving through holes on one or both sides of the cavity. The distribution around the cavity surface is obtained and is correlated with a survey of the recent literature. In addition, local heat flux gages were used with an impingement jet air supply which could be changed in location along the axis of the test section. This permitted the determination of local heat transfer coefficient distribution over the surface both around the cavity and also in the region between the impinging jets. This two-dimensional distribution is shown to be influenced by the bleed geometry and the shape of the impinging jet holes.
Advanced Nonpolluting Gas Turbine for Utility Applications in Urban Environments
Authors: Biancardi F. R. , Peters G. T.
Published: April 2015

The fossil-fueled, open-cycle gas turbine power plant which incorporates advanced design features derived from aircraft gas turbine engines offers the potential of providing nonpolluting base-load electric power in many regions of the United States at generation costs below that of competing steam electric systems. The results of analytical studies to estimate the performance, size, and cost characteristics of advanced simple-cycle and regenerative-cycle gas turbines which are anticipated to be commercially available in the next two decades are described. The advantages of utilizing waste-heat recovery systems in combination with these high-temperature gas turbines to provide heat (for space heating, air conditioning system operation, process heating, etc.) in addition to electric power for urban communities, while conserving fuel resources and reducing or eliminating air and water pollution, are discussed.
Heavy Duty Marine Gas Turbines: A Case Study
Authors: Jones R. A. , Hefner W. J.
Published: April 2015

The Broken Hills Proprietary Company, Ltd. of Australia is building two gas turbine powered roll-on, roll-off ships. The main propulsion plants of these unique vessels are General Electric Model Series–5002 heavy duty marine gas turbines. This paper describes some of the features of these ships and their gas turbines as well as reviewing the controls and supporting systems.
Development and Trialing of HMCS BRAS D’OR: An Open Ocean Hydrofoil
Authors: Fischer K. E. , Callow M. J.
Published: April 2015

The hydrofoil, a ship that overcomes hull resistance by operating with the hull above the water surface, is one type of vessel that is able to cruise at speeds of up to 50 knots in significant sea states. This paper presents a review of the Canadian program directly related to the constructing and trialing of HMCS BRAS D’OR, an open ocean hydrofoil. It summarizes the history of the designing, constructing, and trialing of the vessel. The hull layout, foil configuration, and machinery arrangement are discussed in some detail. Practical operating experience and some results obtained during the trials conducted throughout the program are also described.
Exhaust Emission Characteristics of Aircraft Gas Turbine Engines
Authors: Nelson A. W.
Published: April 2015

Accurate measurement of the exhaust emissions of aircraft gas turbine engines presents a challenge not only because of the high velocities and temperatures of the exhaust stream, but also because of the variation of the exhaust constitutents over the relatively large-cross-section of the jet stream itself. Other factors which affect exhaust emission level include ambient temperature and humidity. This paper presents the results of independent efforts by Pratt & Whitney Aircraft to identify emission variation characteristics together with results of an exhaust emission documentation program funded by the Environmental Protection Agency. Methods and techniques employed in the above programs are also discussed. The results of these programs indicate that additional effort is required to properly evaluate and understand the emission characteristics of aircraft gas turbine engines.
Operational Experience of the S.S.S. (Synchro-Self-Shifting) Clutch Particularly in Naval Propulsion Machinery
Authors: Clements H. A.
Published: April 2015

The S.S.S. (Synchro-Self-Shifting) overrunning clutch with its pawl actuated helical sliding motion is well known, particularly in the gas turbine field. This paper reviews briefly the clutch operating principle, then outlines some of the service experience since 1958 in naval main propulsion drives in COSOS, COSAG, CODOG, CODAG and COGOG plant. Extra features are then described such as a lock-out control as is usually necessary for turbine applications to permit turbine testing, e.g., when in harbor; also a lock-in control as is essential when the clutch has to transmit power in both directions of rotation. Various clutch mounting respective advantages. The paper concludes with information regarding reliability during many years of service experience.
A New Generation Heavy Duty Gas Turbine for Pipeline Applications
Authors: Hefner W. J.
Published: April 2015

This paper describes a new generation of heavy duty gas turbines manufactured by the General Electric Company. The new unit, known as Model Series 5000 two shaft, has recently been introduced for pipeline service. A detailed description of the design features of the gas turbine is given along with some general comments concerning a typical pipeline installation.
Turbofan Trends for Short Haul
Authors: Dawson L. G. , Sills T. D.
Published: April 2015

After a general indication of the noise problem the relation between conventional and STOL systems are broadly reviewed and their requirements as regards the powerplant are discussed. Some of the associated technical challenges are then considered. These include variable pitch fans, reduction gears, thrust reversal and the environment, (noise and pollution). It is shown that the development of a quiet, clean propulsion engine is perhaps the most important and pressing single task for the powerplant constructor to attack.
The Development of a Carbohydrate-Based Gelling Agent for Turbine Fuel
Authors: Teng James , Lucas J. M. , Scallet B. L.
Published: April 2015

A carbohydrate derivative was designed as a gelling agent for turbine fuel. The gelling agent is effective in reducing fire hazards of the fuel. The chemical and physical properties of the gelling agent are presented. Rheological data of the gelled fuel pertinent to aircraft operation are outlined and discussed.
Experimental Study on High Loading Combustor for Lift Jet Engine
Authors: Yamanaka Kuniyasu
Published: April 2015

This paper deals with the parameters to specify a performance of a spray-type combustor which is a high loading combustor for a lift jet engine. The mixing parameter to control a combustion efficiency was obtained analytically by means of simplifying a primary zone, and its effectiveness was confirmed experimentally. The combustor geometry used for the test was 90-deg sector model of an annular type, the 42 combinations of different seven swirlers and six deflectors were tested systematically. The maximum combustion loading of 2.0 × 107 Btu/hr/cu ft combustion volume per atmosphere was obtained.
The Production of Vorticity and its Effects on the Flow in Centrifugal Compressor Impellers
Authors: Goulas Apostolos
Published: April 2015

Based on a hub-to-shroud stream surface solution of the flow in a centrifugal compressor impeller, the equations governing the production of vorticity in a centrifugal compressor impeller are solved. The results are similar to experimental ones for shrouded and unshrouded impellers. Furthermore, assuming that the circumferential gradient of vorticity is zero, a picture of the three-dimensional velocity field is obtained. The picture obtained is similar to experimental ones, although the vortex associated with the suction side is smaller.
Application of Aircraft Derivative and Heavy Duty Gas Turbines in the Process Industries
Authors: Doherty M. C. , Wright D. R.
Published: April 2015

Typical applications of aircraft derivative and heavy duty gas turbines in petroleum production and refining, natural gas processing, ethylene, ammonia, LNG processing plants and offshore platforms are reviewed. Guidelines are included to illustrate how gas turbines can be applied to minimize fuel consumption and cooling water requirements and optimize space utilization.
The Base Pressure Problem in Transonic Turbine Cascades
Authors: Sieverding C. H. , Stanislas M. , Snoek J.
Published: April 2015

Base pressure data were systematically collected at VKI during recent years on a great variety of cascades operated over a wide range of outlet March numbers. An attempt is made to correlate these data by relating the base pressure to important cascade and flow parameters. Details about the trailing edge flow are obtained by using an enlarged model simulating the overhang section of convergent turbine cascades. The experimental cascade and model test results are compared with theoretical calculations using base pressure calculation methods.
The Development of the Olympus “C” Gas Generator
Authors: Green C. H. , Bean C. J.
Published: April 2015

Firmly based on the well established Olympus “A” and “B” gas generators, the successful design and development of a 30 percent more powerful version, the Olympus “O,” specifically for industrial and marine operation, represents a significant milestone in the use of compact gas turbines in these fields. Producing 33 EGMW, the re-design of the gas generator turbines and combustion system to introduce more advanced technology permitted the raising of the maximum cycle temperature by 140 K. The engineering program from project concept through basic development and launch to successful commercial service operation is described with particular emphasis on problem identification, analysis, and solution.
Performance Estimation of Partial Admission Turbines
Authors: Korematsu Koji , Hirayama Naomichi
Published: April 2015

The new relationships of partial admission losses which account for influence of all major geometric parameters of concern to the turbine designer are presented, based on fluid dynamic analysis of the losses. The performance maps are presented showing the trends in efficiencies that are attainable in turbine designed over a wide range of loading, axial velocity/blade speed ratio, Reynolds number, and aspect ratio. Finally, the question of partial admission versus low aspect ratio is discussed.
Low-Turbulence High-Speed Wind Tunnel for the Determination of Cascade Shock Losses
Authors: Slovisky J. A. , Roberts W. B. , Sandercock D. M.
Published: April 2015

A low turbulence high-speed wind tunnel, using anti-turbulence screening and a 100:1 contraction ratio, has been found suitable for high-speed smoke flow visualization. The location and strength of normal, oblique, and curved shock waves generated by transonic or supersonic wind tunnel flow over airfoils or through axial compressor cascades is determined by combined shadowgraph and smokelines visualization techniques without the interference effects caused by intrusive probes. The Reynolds number based on chord varied between 50,000 and 106. Preliminary results are compared with the relevant theory and data gathered using a total pressure probe.
Laboratory Evaluation of a Closed Brayton Engine With a Gas Management System
Authors: Duvall G. D.
Published: April 2015

A previously tested 30-kw shaft output engine has been fitted with a closed-loop gas management system for power control. The closed-cycle engine operates at essentially constant speed and turbine inlet temperature, and power capability is a function of pressure level. The gas management system compresses and stores excess argon working fluid during load removal and injects on demand in response to load application. The system consists of a low, medium and high pressure storage accumulator, piston-type motor-driven compressor, valving and electronic control unit for sequencing the accumulators. Peak storage pressures at minimum power (10kw) are 765, 1076, and 1517 kPa (111, 156, and 220 psia). The engine and control system were run for a total of 57 hr over numerous transients of varying duration and range. Operation was characterized by quick response, smooth switching, and effective control. During load removal, the compressor required up to 3 min. to reduce full inventory to minimum power while turbine bypass valves allowed immediate engine response without excessive overspeed. Manually adjustable inject orifices allowed system response to closely follow load applications of 15 sec to 3 min. Compression heating in the accumulators during charging tended to elevate the switch points slightly, altering the storage capacities after repeated transients.
Thermal Influences in Gas Turbine Transients: Effects of Changes in Compressor Characteristics
Authors: Maccallum N. R. L.
Published: April 2015

During transients of axial-flow gas turbines, the characteristics of the compressor are altered. The changes in these characteristics (excluding surge line changes) have been related to transient heat transfer parameters, and these relations have been incorporated in a program for predicting the transient response of a single-shaft aero gas turbine. The effect of the change in compressor characteristics has been examined in accelerations using two alternative acceleration fuel schedules. When the fuel is scheduled on compressor delivery pressure alone. there is no increase in predicted acceleration times. When the fuel is scheduled on shaft speed alone, the predicted acceleration times are increased by about 5 to 6 percent.
Status of Marine Gas Turbine Inlet Development Program
Authors: Frazier C. T. , Ruskin R. E. , Mihalek E. W.
Published: April 2015

Over ocean, salt aerosols ingested in the combustion air of a marine gas turbine cause engine compressor fouling and are a primary factor in engine hot section corrosion. To minimize salt ingestion effects on engine performance and life, a high performance salt filtration system is required. The U.S. Navy is currently conducting the Gas Turbine Inlet Development Program. The program consists of work elements including salt filter tests, at-sea salt-in-air measurements, ship aerodynamic studies, inlet duct design, etc. To complete the assigned work tasks, Navy facilities had to develop state-of-the-art instrumentation and test procedures. Based on these work tasks, the U.S. Navy will publish a Gas Turbine Inlet System Design Handbook. The handbook will provide design guidance for the ship builder and inlet duct designer for optimizing shipboard salt filtration perfmance.
Effects of the Combustion Products of Coal-Derived Fuels on Gas Turbine Hot-Stage Hardware
Authors: Sims C. T. , Doering H. vonE. , Smith D. P.
Published: April 2015

This paper reports a DOE-sponsored program to evaluate the effect of the combustion products of coal-derived fuels on current and potential materials used in gas turbine hot-section components and on the plugging of cooling holes in air-cooled airfoils. Atmospheric-pressure small burner rigs and a combustor operating at elevated pressures and design air flows, equipped with a segment of a first-stage nozzle (turbine simulator), were used in these evaluations.
An Introduction to a Unified Approach to Flexible Rotor Balancing
Authors: Parkinson A. G. , Darlow M. S. , Smalley A. J. , Badgley R. H.
Published: April 2015

Several successful methods for balancing flexible rotating shells have been developed in recent years. The methods can apparently be subdivided into a group which is based on modal characteristics and another set which employs influence coefficients. The relative merits of these two approaches have been the subject of much discussion and argument — most of it inconclusive and rather fruitless. The authors consider that in practice many of the differences are more apparent than real and that they seem to occur because the various techniques are normally presented in relatively simple and ideal, theoretical terms. This paper represents the start of a joint project which hopes to resolve the apparent differences and, eventually, develop a unified approach to such balancing. A discussion of the theoretical basis for this unified approach is presented along with a description of a test program conducted to explore the possibilities of such an approach.
Atomization of Water Jets and Sheets in Axial and Swirling Airflows
Authors: Ingebo R. D.
Published: April 2015

Axial and swirling airflows were used to break up water jets and sheets into sprays of droplets to determine the overall effects of orifice diameter, weight flow of air, and the use of an air swirler on fineness of atomization as characterized by mean drop size. A scanning radiometer was used to determine the mean drop diameter of each spray. Swirling airflows were produced with an axial combustor, 70-deg brake angle, air swirler. Water jets were injected axially upstream, axially downstream and cross stream into the airflow. In addition, pressure atomizing fuel nozzles which produced a sheet and ligament type of breakup were investigated. Increasing the weight flow rate of air or the use of an air swiler markedly reduced the spray mean drop size. Test conditions included a water flow rate of 68.0 liter per hour and airflow rates (per unit area) of 3.7 to 25.7 g per square cm per sec, at 293 K and inlet-air static pressures of 1.01 × 105 to 1.98 × 105 N/m2.
Wind Tunnel Model Study of the Hot Exhaust Plume From the Compressor Research Facility at Wright-Patterson Air Force Base, OH
Authors: Ludwig G. R.
Published: April 2015

This paper presents the results of a wind tunnel model study to determine temperatures at various locations generated by the hot exhaust air from the Compressor Research Facility [CRF] which is being built at Wright-Patterson Air Force Base, Ohio. The study was designed to provide data at the inlet to the CRF and at other nearby locations where pedestrians, building ventilation systems, and vegetation might be affected. The test program, which was conducted in the Calspan Atmospheric Simulation Facility, included flow visualization studies and quantitative concentration measurements of a tracer gas from which full-scale temperature could be calculated. The concentration measurements were performed for a number of wind speeds at each of twelve different wind directions. Two exhaust flows and two exhaust stack configurations were studied.
Power Station Experience With Retrofitted Programmable Fuel Management and Sequencing Controllers for Aero-Derivative Gas Turbine
Authors: Peacock B. , Semmens R.
Published: April 2015

To assess the improvements in starting reliability obtainable from the use of programmable controllers for sequence control, governing and fuel management of gas turbine powered generating sets, the CEGB installed controllers on two 17 1/2-MW Olympus powered units. This report looks at the performance achieved and the problems encountered from their use on power station plant.
An Experimental Investigation of the Heat Transfer to a Turbine Vane at Simulated Engine Conditions
Authors: York R. E. , Hylton L. D. , Fox R. G. , Simonich J. C.
Published: April 2015

Full application of 2D boundary layer calculations for heat transfer predictions during turbine vane design still awaits verification against relevant data. Although there are a few data sets in the literature, there is a definite need for basic vane heat transfer data under conditions that fully simulate the aerodynamic and thermal conditions of a modern turbine. Accordingly, an experiment was performed to obtain the local heat transfer distribution on a typical engine vane in an aerothermodynamic cascade facility. Heat transfer data were obtained for a range of Mach and Reynolds numbers. The cascade was closely coupled behind the facility burner so that the test included the effects of high free-stream turbulence. Turbulence data were obtained by LDV and are included.
Shock Boundary Layer Interaction on High Turning Transonic Turbine Cascades
Authors: Graham C. G. , Kost F. H.
Published: April 2015

In recent years, the increase in turbine entry temperature, coupled with the capability of higher blade speeds, has led to greater interest in the high work capacity single-stage transonic high pressure turbine. However, the transonic turbine has a performance penalty compared with an equivalent subsonic unit due mainly to shock induced losses. A cascade investigation into the influence of supersonic shocks on turbine blade performance is reported. Two different rotor profiles designed for the same duty were tested in the rectilinear cascade wind tunnel at DFVLR-AVA Goettingen. The results indicate the sensitivity of the cascade performance to shock boundary layer interaction. The importance of Schlieren optics flow visualization (including high-speed film to show the unsteady behavior of the flow) in evaluating the results is discussed.
System Status of the Water-Cooled Gas Turbine for the High Temperature Turbine Technology Program
Authors: Caruvana A. , Day W. H. , Cincotta G. A. , Rose R. S.
Published: April 2015

This paper presents an update on the status of the technology of the water-cooled gas turbine developed by the General Electric Company under contracts with EPRI, ERDA, and DOE. Particular emphasis is devoted to the design and development of water-cooled composite turbine nozzles and buckets, and a sectoral combustor designed for low-Btu coal-derived gas operation. The operating characteristics of a low-temperature coal gas chemical cleanup system which is to be added to the coal gasification facility are also discussed. Status of the materials and process developments in support of the designs are also presented, as are updates to the Phase I HTTT Program combined-cycle studies, which evaluate the commercial viability of integrated coal gasification and combined-cycle operation.
Future Tactical Fighter Requirements: A Propulsion Technology Update
Authors: Lind G. W. , Ervolina T. S.
Published: April 2015

This paper examines the potential roles that are emerging from current studies of future U.S. Air Force tactical fighters and analyzes their impact on the propulsion system requirements. It provides an updated review of the leading propulsion technology concepts that are the candidates in meeting such critical design challenges as supersonic cruise, stealth, STOL, as well as high maneuvering capability with a cost-efficient weapon system.
On the Optimal Tube Spacing for Shell-and-Tube Gas Turbine Recuperators
Authors: Lee W. Hilary
Published: April 2015

The effect of high pressure inside and outside of tubes and of pressure ratios on tube spacings associated with minimum volume and minimum weight of shell-and-tube gas turbine recuperators, is examined. For this purpose, a method was developed for analyzing volume and weight of shell-and-tube heat exchanger surfaces. The influence of TEMA recommended minimum spacing-to-diameter ratio on the result is discussed. Implications of the above findings on gas turbine recuperator design is sketched.
Performance Correlations for Flat and Conical Diffusers
Authors: Thompson R. G.
Published: April 2015

Minimum length diffusers investigated and reported in the Creare Diffuser Data Book are examined in the light of the maximum diffusion rate theory due to Stratford and Tubbs, and the constant discharge blockage concept proposed by D. P. Kenny. Simple correlations for recovery versus length, effectiveness versus blockage, and loss versus blockage at area ratio = 4.0 are given for flat diffusers of aspect ratio = 1 and for conical diffusers.
An Application of 3-D Viscous Flow Analysis to the Design of a Low-Aspect-Ratio Turbine
Authors: Liu H. C. , Booth T. C. , Tall W. A.
Published: April 2015

Previously reported cascade test results verified and provided a calibration of the 3-D viscous flow analysis. This paper describes the subsequent AFAPL-sponsored technology program in which the 3-D viscous flow computer program was used to optimize the low-aspect-ratio stator of a high-work turbine stage. The optimization procedure, in conjunction with the radial distribution of energy extraction, led to innovative-but-realistic blading for advanced gas generator turbines. A turbine stage was tested with this stator, in conjunction with an appropriate rotor design. The total-to-total design-point efficiency — 92 percent at 1-percent tip clearance — was achieved at 31.83 Btu/lbm specific work. In addition to stage tests, separate stator tests were conducted including a measurement of total pressure loss and stator reaction torque, which provided baseline data to assess interaction effects during stage testing with stator reaction measurements “in vivo.”
Laser Balancing Demonstration on a High-Speed Flexible Rotor
Authors: DeMuth R. S. , Fleming D. P. , Rio R. A.
Published: April 2015

This paper describes a flexible rotor system used for two-plane laser balancing and an experimental demonstration of the laser material removal method for balancing. A laboratory test rotor was modified to accept balancing corrections using a laser metal removal method while the rotor is at operating speed. The laser setup hardware required to balance the rotor using two correction planes is described. The test rig optical configuration and a neodymium glass laser were assembled and calibrated for material removal rates. Rotor amplitudes before and after balancing, trial and correction weights, rotor speed during operation of laser, and balancing time were documented. The rotor was balanced through the first bending critical speed using the laser material removal procedure to apply trial weights and correction weights without stopping the rotor.
An Off-Design Correlation of Part Span Damper Losses Through Transonic Axial Fan Rotors
Authors: Roberts W. B. , Crouse J. E. , Sandercock D. M.
Published: April 2015

The experimental performance of 10 transonic fan rotors was used to correlate losses caused by midchord part-span dampers (PSD) during off-design operation between 50 and 100 percent of design speed. The design tip speed for the rotors used varied from 419 to 425 meters per second and the design pressure ratios from 1.6 to 2.0. The loss attributable to the damper and the region influenced along the blade height was correlated with relevant aerodynamic and geometric parameters. The losses at the design point were estimated by a previously reported correlation [1]. Using this as a base, the off-design losses were correlated with variation in blade suction surface incidence. A check with independent data showed that the prediction of damper losses and region of influence was fair to good for most of the off-design data examined.
Soot and the Combined Cycle Boiler
Authors: Roberts P. B. , Marron H. D.
Published: April 2015

Liquid-fueled gas turbines can produce serious steam generator fouling in combined cycle applications and other waste heat recovery systems as a result of combustion system generated soot particles. In addition, standard soot blowing practices are not always compatible with the advanced, compact matrix designs sometimes required for minimum package size applications. This paper describes an experimental program conducted on both test rigs and engine hardware designed to evaluate the effects on gas side soot fouling rates of various operational parameters such as soot loading, temperature and velocity. Particular attention is given to the effectiveness of the self-cleaning concept where elevated steam generator metal temperatures are utilized to remove soot deposits.
NOx Removal Process by Injection of NH3 and H2O2 in Gas Turbine Exhaust Gas
Authors: Hishinuma Y. , Nakajima F. , Akimoto H. , Uchiyama Y. , Azuhata S. , Oshima R. , Kato M.
Published: April 2015

For the removal of NOx in a gas turbine exhaust gas, the reduction of NOx with NH3 and H2O2 was studied. It was found that the addition of H2O2 very effectively lowers the reduction temperature of NO with NH3 and that more than 90 percent NOx reduction could be attained at 550 C in the absence of O2. However, the NOx reduction rate decreased with increases in the concentration of O2, and NOx reduction was about 40 to 60 percent under gas turbine exhaust gas condition (15 percent O2). In order to attain a high rate of reduction of NOx, a combined reduction process, which consisted of homogeneous gas phase and the catalytic heterogeneous reactions, was also developed. The efficiency of the new process was proved in a pilot plant using half a size model of a 25-MW gas turbine combustor.
Design Considerations for the Closed-Loop Water-Cooled Turbine
Authors: El-Masri M. A. , Louis J. F.
Published: April 2015

One method of liquid-cooling gas turbines is by circulating coolant through a system of radial subsurface passages within the rotating blades. The effect of the large centrifugal force upon the varying-density coolant could cause flow instability or maldistribution problems. Those are discussed and analysis suggests possible stable channel configurations. To efficiently design such a system, it would be necessary to estimate the critical heat flux (CHF) for the coolant channels. Experiments were run to determine CHF during subcooled boiling in rotating tubes with radial inflow, this being the most stable arrangement. The data displays interesting effects peculiar to rotating tubes. Those are explained in terms of the development of secondary flows. A physical model is presented and this provides a rational basis for correlating the CHF data.
The Optimization of Heat Exchanger Solidity for Coal-Fired Fluidized Bed Combustors
Authors: Miller G. , Zakkay V. , Rosen S.
Published: April 2015

The efficient extraction of a high-temperature working fluid from a coal-fired fluidized bed combustor depends, to a great extent, on the design of the immersed heat exchanger. Of special importance is the solidity of the cooling tubes immersed in the bed. The interaction between increasing solidity and the consequent degradation of proper fluidization and circulation is being studied at the New York University fluidized bed combustion facility. It is found that under certain conditions, the solidity of heat exchanger in the bed can be significantly increased and thus one can extract increased mass flows of clean working fluid. In addition, a variation in local solidity may be another mechanism for improving performance.
The “Second Generation” LM2500: An Example of High Level of Reliability/Availability With Low Life-Cycle Costs
Authors: Spector R. B.
Published: April 2015

The first LM2500 “second generation” gas generator was placed in gas transmission service in December 1970. Derived from the TF39 and CF6 engines, advanced aircraft power plants in service since 1965 for the Air Force C5A transport and the new wide-bodied commercial airlines, the LM2500 has accumulated over 315,000 operational hours in gas transmission service. During this period, the LM2500 has demonstrated the capability to exceed 45,000 hr without major overhaul. Demonstrated reliability and availability have exceeded 99 percent. This paper describes the evolution of the LM2500 from its aircraft progenitors in order to illustrate the effect of the initial design concepts embodied upon reliability, availability, maintainability and life cycle-costs. Included is a discussion of the overall influence of initial acquisition, fuel, maintenance, and repair costs and their effects on system availability and overall life-cycle cost.
Low Cost Thin-Film CdS-Based Solar Cells Progress and Promise
Authors: Barnett A. M. , Meakin J. D.
Published: April 2015

The direct conversion of sunlight to electricity using thin film solar cells offers the potential of a low cost renewable source of energy. A major factor contributing to the low projected costs is the very small quantities of materials required as the active layers of the cells can be as little as 2 microns (0.0002 cm) thick. The efficiency of these low cost thin film solar cells may have to exceed 10 percent to achieve economic central power generation. Until 1976, no thin film solar cells with above 7 percent efficiency in sunlight had been reported, but since then the Institute of Energy Conversion has successively reported 7.8, 8.55, and 9.15 percent. This paper will describe the loss minimization methodology utilized to achieve these increases in performance. Analysis shows that efficiencies as high as 14 to 16 percent for CdS-based solar cells are achievable. The research and development necessary to achieve these high efficiencies will be described. The feasibility of an extremely low cost manufacturing process capable of producing solar cells costing $250/kw will be discussed. Recent progress in development of low-cost thin-film devices shows great promise that direct conversion of sunlight to electricity can make a measurable contribution to the electrical energy supply both nationally and internationally.
Treatment of Molybdenite Ore Using a 2 kw Solar Furnace
Authors: Skaggs S. R. , Coutures J. P.
Published: April 2015

Hydrometallurgical methods of extracting molybdenite (MoS2) from the raw ore consume 145 × 106 Btu ton of fossil fuel equivalent energy per ton of concentrate produced. Processing the ore using a solar heat source could save 56 percent of this energy. Thermodynamic considerations indicate that MoS2 is the easiest of the economically valuable ores to extract. If the technique can be developed with this ore, it may be possible to extend it to other ores. Oxidation of the sulfide to molybdic oxide (MoO3) is an exothermic process, and it should proceed autogenically if the concentration of MoS2 is high enough. Experiments to measure the specific heat of the raw ore were conducted to determine the crossover point for this autogenic reaction. Using a calorimeter, we found three distinct reaction temperature ranges corresponding to water and organic vapors, oxidation of pyrite (FeS2), and oxidation of molybdenite. The production rate of SO2 was measured for 0.5-g samples of three different concentrations of molybdenite: (a) 95 percent MoS2 concentrate, (b) 10 percent concentrate in the raw ore, and (c) the unadulterated raw ore. A crude mass balance was obtained between the reaction products and the unreacted ore in the hearth. The curves of reacted product wersus time look very similar to the curves of SO2 gas produced versus time. Both sets of curves show the reaction is more than 90 percent complete in one minute. This work is sponsored by the US Department of Energy and the French Center Nationale de Recherche Scientifique. It is a cooperative effort of the Los Alamos Scientific Laboratory in the US and the Laboratoire des Ultra-Refractaires and the Laboratoire d’Energetique Solaire in Odeillo, France.
Textile Drying Using Solar Process Steam
Authors: Beesing M. E.
Published: April 2015

This paper describes a solar energy collector system for providing process heat to a textile drying process in a WestPoint Pepperell mill in Fairfax, Alabama. The solar collector system uses 24 single axis tracking parabolic trough concentrating collectors to heat water in a high temperature water loop. The high temperature water fuels a steam generator to provide process steam. The process that was solarized is a textile drying process using cylindrical can dryers. The dryers are utilized in the slashing operation, a textile process where yarn is treated with sizing in preparation for weaving.
Matching Solar Systems to Industrial Needs
Authors: Brown K. C. , Stadjuhar S. A.
Published: April 2015

This paper presents the results of an applications analysis of solar industrial process heat for six cities in the United States. Over 70 percent of the industrial plants in each city are identified and process heat requirements typical of the industries are recorded. Using actual meteorological and economic data for these sites and actual solar system component characteristics, a long-term average performance estimate is generated for each of six generic solar systems using each of approximately 20 actual collectors. The simulation program used in obtaining long-term annual performance has been specifically developed by SERI and is a significant tool in such analyses because of its short computational time and flexibility. A cost analysis is made for each case in order to provide criteria by which promising specific applications can be identified.
Solar Rankine Engines: Examples and Projected Costs
Authors: Barber R. E.
Published: April 2015

Solar heat can be converted into shaft power by use of the Organic Rankine Cycle Engine (ORCE). The efficiency of the ORCE to convert the solar heat to shaft power varies from 7 or 8 percent for an ORCE heated by low temperature flat plate collectors at 200 F, to near 15 percent when heated by intermediate temperature collectors (300 F), and up to 25 percent with high temperature concentrating collectors (600 F). Barber-Nichols designed, built, and tested its first solar heated ORCE in 1973, which produced three tons of air conditioning. Since that time, the three-ton unit has reached its fourth iteration on the development path to production; a 77-ton water chiller was installed at LASL; two ORCE drives for 100-ton water chillers were delivered to Honeywell; seven 25-ton water Chillers were delivered to DOE demonstration sites; and a 25-hp ORCE for irrigation pumping was installed in Willard, N.M. Photographs, design details, and the measured performance of these units are presented herein as examples. The cost of solar power systems using an ORCE is also presented which shows that for the current $150 to $200/m2 cost of cencentrating collectors, the system cost would be in excess of $2500/kw peak. The ORCE is approximately 25 percent of this cost or $600/kw. Consequently, while reductions in the cost and improvements in the performance of the ORCE can and should be made in the development process, the cost competitiveness of a solar power system is largely dependent on developing low cost concentrating collectors which can be sold for 1/2 to 1/3 of today’s price.
Experimental Cultivation of Giant Kelp in Oceanic Environments
Authors: North W. J.
Published: April 2015

Producing biomass in the ocean was conceived in the late 1960s by Hall and Wilcox as an alternative energy source whose attractions included abundances of available space on the sea surface, plant nutrients in the ocean depths, and environmental energy in the waves and currents. Efforts by these two scientists and by many others has led to the Marine Biomass Project. The Project is a cooperative research program managed by General Electric Co. with participation by the U.S. Department of Agriculture (kelp processing studies). Institute of Gas Technology (methane production studies), Global Marine Development, Inc. (marine engineering), and California Institute of Technology (kelp production studies), as well as supporting microbiological and other studies within General Electric. The primary objective is to develop an integrated system for producing, harvesting, and processing marine biomass, followed by conversion to methane. Giant Kelp, Macrocystis, is under current study as the producer of biomass, but other seaweed species may eventually be used. This paper describes primarily the kelp production studies. Objectives of the kelp production studies include: (a) determine elements needed in Macrocystis nutrition, (b) develop an optimal strategy for fertilizing plants in an oceanic setting, (c) determine harvest yields from a group of adult test plants continually fertilized. The most promising common source of plant nutrients in the sea lies in waters at depths of 100 m or greater. These could be pumped up by environmental energy to fertilize kelp held near the surface on artificial structures. Our laboratory work indicates that available micronutrients present in water from 300 m deep are usually depleted in surface waters, but the reverse may sometimes be true for some trace metals such as Fe and Mn. Therefore, appropriate mixtures of surface and deep water may be the optimal fertilizing medium. Research is currently emphasizing a large field study that will measure harvest yields from a group of 100 adult transplants continually fertilized by water pumped from depths of 450 m. Information on yields is critically needed to assess economic feasibility of the concept.
Hawaiian Sugarcane Energy Plantations
Authors: Mashima K. I. , Gibson W. O.
Published: April 2015

Hawaiian sugarcane plantations are presently in the business of producing food sugar and are nearly energy self-sufficient through use of residual fiber for fuel. They could be converted to “energy plantations” by converting sugar to ethanol by fermentation. Energy and economic analyses of this alternative energy source are presented.
Initial Investigations of a Shallow-Layer Algal Production System
Authors: Raymond L. P.
Published: April 2015

A system for the intensive cultivation of the marine diatom Phaeodactylum tricornutum is described and evaluated. Unique features of the system include: (a) the incorporation of solar heat collection device which transmits only photosynthetically active radiation (PAR) to the growing culture; (b) the formulation of a new seawater enrichment medium that promotes physiological responses not previously observed in culture; and (c) the use of a foam fractionation device which separates microalgae, from the culture media, adds CO2-enriched air, and/or simultaneously recirculates the growing culture in shallow layers through an interconnecting series of hemicylindrical channels. The outdoor system demonstrated that very high ash-free dry weight yields of Phaeodactylum tricornutum are produced, a result of high photosynthetic efficiency. Actual yield over an eight-day period was equivalent to 39.57 ash-free dry tons/acre-year. Observed photosynthetic efficiency, based on photosynthetically active radiation incident upon the external surface of the system, is 13.1 percent, nearly three times the limit previously considered economically practical. The data indicate that greater yields may be expected using this system at locations receiveing higher insolation. A conservative projection is that 80 ash-free dry tons/acre-year will be realized in land regions receiveing 3 × 1010 Btu/acre-year total solar radiation. It is concluded that this system clearly warrants further investigation to determine its capacity to produce large and economical quantities of algal biomass for use as potential petroleum-fuel substitutes. The development of a comprehensive and systematic bio-engineering program is recommended to upgrade and evaluate the system to its full potential.
Group 3 innate lymphoid cells mediate intestinal selection of commensal bacteria–specific CD4
+
T cells
Authors: Hepworth Matthew R. , Fung Thomas C. , Masur Samuel H. , Kelsen Judith R. , McConnell Fiona M. , Dubrot Juan , Withers David R. , Hugues Stephanie , Farrar Michael A. , Reith Walter , Eberl Gérard , Baldassano Robert N. , Laufer Terri M. , Elson Charles O. , Sonnenberg Gregory F.
Published: April 2015

Innate lymphoid cells keep gut T cells in check

Trillions of bacteria inhabit our guts. So do many types of immune cells, including T cells, which might be expected to attack these bacteria. How, then, do our bodies manage to keep the peace? Working in mice, Hepworth
et al.
report one such mechanism. A population of immune cells, called innate lymphoid cells, directly killed CD4
+
T cells that react to commensal gut microbes. Some of the specifics of this process parallel how the immune system keeps developing self-reactive T cells in check in the thymus. Furthermore, this peacekeeping process may be disrupted in children with inflammatory bowel disease.

Science
, this issue p.
1031
Chronicling modern human's arrival in Europe
Authors: Conard Nicholas J. , Bolus Michael
Published: April 2015

Dental remains elucidate the demise of the Neandertals

[Also see Report by

Benazzi
et al.

]
Genome Sequences of Beak and Feather Disease Virus in Urban Rainbow Lorikeets (Trichoglossus haematodus)
Authors: Collings David A. , Collings Berwyn G. , Julian Laurel , Kurenbach Brigitta , Varsani Arvind
Published: April 2015

Beak and feather disease viral genomes were recovered from two deceased juvenile urban rainbow lorikeets (Trichoglossus haematodus) that lacked tail feathers. These genomes share ~95% pairwise identity with two beak and feather disease virus (BFDV) genomes identified in wild and captive AustralianT. haematodusbirds and ~92% identity to those in wild New CaledonianT. haematodus deplanchiibirds.
Genome Sequence of
Phlebopus portentosus
Strain PP33, a Cultivated Bolete
Authors: Cao Yang , Zhang Ying , Yu Zefen , Wang Pengfei , Tang Xiaozhao , He Xiaoxia , Mi Fei , Liu Chunli , Yang Dan , Xu Jianping
Published: April 2015

Phlebopus portentosus
can form fruiting bodies, both independently as a saprophyte and in association with plants as an ectomycorrhizal symbiont. It thus offers an excellent model from which to examine the genetic basis of lifestyle adaptations and transitions for mushrooms. This paper reports the genome sequence of a homokaryotic strain of
P. portentosus
, PP33.
Complete Genome Sequence of Mycoplasma yeatsii Strain GM274B (ATCC 43094)
Authors: Calcutt Michael J. , Kent Bethany N. , Foecking Mark F.
Published: April 2015

Mycoplasma yeatsii
is a goat mycoplasma species that, although an obligate parasite, accommodates this lifestyle as an inapparent commensalist. High-frequency transformation has also been reported for this species. The complete 895,051-bp genome sequence of strain GM274B has been determined, enabling an analysis of the features of this potential cloning host.