bluuebunny/crossref_metadata_2025 huggingface dataset:
Introduction
Authors: Emmons Howard W.
Published: April 2015

Stall, to a hydraulic or turbomachinery engineer, may denote a variety of difficulties encountered in the fluid mechanic performance of engineering equipment. At one extreme the term may mean no more than an expression of ignorance of just what is wrong, while at the other extreme it means the reverse flow encountered on the upper surface of an airplane wing when the lift abruptly drops with increasing angle of attack.
Technical Considerations in the Development of a Maritime Gas-Cooled Reactor System
Authors: Resnick Bernard T.
Published: May 2015

The Maritime gas-cooled-reactor concept is a closed-cycle nuclear propulsion system in the 20,000-shp range. The power cycle consists of a beryllium-oxide, helium-cooled reactor, directly coupled to a closed-cycle axial-flow, split turbine. The high-pressure turbine drives the directly connected helium compressors. The low-pressure turbine drives the propeller shaft through a suitable speed reducer. Problems relating to the design development of principal plant components and systems, and the current status of turbomachinery and reactor technology are discussed.
Materials Keep Pace With Industrial Gas-Turbine Needs
Authors: Gayley Harry B.
Published: May 2015

Reliability and improvements in industrial gas turbines are closely related to the materials study programs which are conducted in support of the turbine design. The studies at the author’s company are described with presentation of blade and disk material data. Field experience as related to materials evaluations are described, with particular emphasis on returning parts to service. Materials now available when fully evaluated, through the program described, will permit metal temperatures 100 degrees F higher than currently used.
The New 40-MW Gas Turbine of the Västervik Central Station
Authors: Schnittger Jan R.
Published: May 2015

In the autumn of 1955 the Swedish State Power Board decided to build a gas-turbine central at Vätervik on the Swedish East Coast, which would be utilized as a dry-year and peak-load plant and to be run for phase compensation to diminish transmission losses. Heavy fuel oil burning, low first cost, minimum personnel requirement, quick start even from “dead station,” possibility to arrange remote operation and an acceptable noise level were all of importance. It was found, that the size of the State power system as well as the over-all economy called for a large gas turbine. The De Laval Ljungstrom Company submitted plans for a 40-mw, three-shaft arrangement with a simple, intercooled cycle and a free-running power turbine, which was accepted for completion in the fall of 1959. 1770 hours of operation have been accumulated in the station as of May 1, 1961, and the present paper gives a general description thereof and a discussion on the initial operational experience.
Development of a Control System for a Dual-Shaft Gas Turbine for Rapid Load Acceptance and Rejection
Authors: McGuire Leo P.
Published: May 2015

The application required large electrical load changes with very limited variations in frequency and voltage. With a dual-shaft gas turbine, nominal rating 8000 kilowatts, instantaneous loads up to 90 per cent rated were successfully accepted and rejected with frequency maintained within a one and one half per cent band. Voltage variation did not exceed four per cent. Frequency and voltage recovery were well within two seconds. The foregoing was accomplished by incorporating a control system which permitted operation of the turbine at other than normal operating conditions when auxiliary control valves were preset in anticipation of the load variation. The auxiliary control valves were air-inlet throttling valves, an inter-turbine bleed valve, and an additional fuel valve. The basic machine consisted of a 15-stage axial compressor, a two-stage, high-pressure turbine, and a two-stage power turbine. The unique requirements necessitated off-design operation and considerable extrapolation from known test data. However, it was possible to program the control-system components so that a conventional pneumatic control system was capable of maintaining speed within the prescribed band even though the applied load varied from that anticipated by as much as 12.5 per cent.
Design Features for a 22-Mw Decentralized Gas-Turbine Plant
Authors: Morrash James
Published: May 2015

Today many utilities are confronted with the problem of increasing their generating capacity to shave system peaks. By the nature of being a complete power cycle, the gas turbine appears as an attractive prime mover in this type application. This paper describes a 22-mw decentralized gas-turbine generating station designed specifically for peaking service. The philosophy of the design of the equipment and its arrangement in the plant is included along with a description of its control and operation.
Gas Turbines in Hydrofoil Seacraft
Authors: Palmer Irwin
Published: May 2015

This paper describes the use of gas-turbine propulsion systems in hydrofail seacraft. Background information on the early hydrofoil developments is presented, as well as discussions of the factors affecting choice of power plants, economics of operation, and the practical considerations involved with respect to marine environments, installation requirements, and engine characteristics. Descriptions of turbine-powered hydrofoil craft are also included.
Production of Integrally-Cast Airfoil Components for Small Gas-Turbine Engines
Authors: Boyle J. H.
Published: May 2015

This paper presents a review of the progress made by the investment casting foundries in producing integrally-cast airfoil components for small gas-turbine engines. The casting process, from pattern production to the final inspection operations, is discussed in detail. Suggested dimensional tolerances, based on the present state of the art, are included. Finally, the properties and casting characteristics of various alloys commonly used for internal components are presented.
Jet Engines in Airline Service
Authors: Overend Walter J.
Published: May 2015

In the aircraft industry, the evolution from the DC-3 to the DC-7 was a rather slow-paced progression. How then did we suddenly produce such aircraft as the DC-8 and the Convair 880?
The Volvo-Turbo Experimental Gas Turbine
Authors: Kronogard S. O.
Published: May 2015

This paper gives a brief description of the Volvo experimental turbine, its working cycle, its basic components and their relative arrangement as well as some of the basic thinking behind the selection of the same. The paper also gives a short description of the new concept of a dual-geared power turbine, the combined reduction gear and high-speed hydrodynamic retarder, as well as some other new features incorporated.
Current Technology of Radial-Inflow Turbines for Compressible Fluids
Authors: Wood Homer J.
Published: May 2015

Efficiencies up to 94 per cent may be achieved with radial, mixed, or axial-flow turbines using either compressible or incompressible fluids. Such high performances are possible only if specific speeds are within certain limits and criteria with respect to Reynolds number and Mach number are favorable. All three types are applicable with no efficiency disadvantage at low and medium specific speeds. For specific speeds above certain limits, radial-inflow turbines tend to be less efficient. In the medium-specific-speed range, a form of radial-inflow turbine having straight radial blade elements has special interest for compressible-fluid applications. Efficiencies in the 90–94 per cent regime have been demonstrated. Stress characteristics are such that for high temperatures and proper specific-speed ranges, higher heads per stage may be used efficiently in one stage than is possible with a single-stage axial turbine.
Vehicular Gas Turbine Periodic-Flow Heat Exchanger Solid and Fluid Temperature Distributions
Authors: Mondt James R.
Published: May 2015

Design, fabrication and operation experience with periodic-flow heat exchangers used in General Motors regenerative vehicular gas turbines has indicated that analysis techniques available in published reports are too restrictive for accurate performance and thermal-distortion calculations. The design usefulness of previously published anaylses is somewhat limited because fluid and metal-temperature distributions are not part of the calculated results. These distributions are required for primary seal matching and core and structural thermal-stress calculations. A nodal analysis has been accomplished at the General Motors Research Laboratories and a type of finite-difference solution obtained for the periodic-flow heat exchanger. This solution can be used to study the effects of longitudinal thermal conduction, variable heat-transfer coefficients, finite rotation, and provides temperature distributions as functions of time and space for transient as well as “steady state.” This has been checked both with available solutions for more simplified cases and some experimental measured results for periodic-flow heat exchangers designed and built as part of the General Motors vehicular regenerative gas-turbine program. A brief outline of the calculation procedures, program capabilities, and some calculated results are presented. This includes temperature distributions for periodic-flow heat exchanger parameters encountered in the vehicular regenerator application.
The Use of Compressor-Inlet Prewhirl for the Control of Small Gas Turbines
Authors: Anderson J. R. , Shouman A. R.
Published: May 2015

The objective of this paper is to describe a control system recently developed to provide nearly instantaneous power response with a two-shaft gas turbine. The principal elements in this system are movable guide vanes in the compressor inlet. The effects of air prewhirl on centrifugal compressor and gas-turbine-engine performance are discussed and test results are presented.
Maritime Administration Gas-Turbine Program
Authors: Peterson R. R.
Published: May 2015

A review of the function of the Maritime Administration in fostering the development of a merchant marine is given. Three major items of gas-turbine development are covered. Their requirements, methods proposed by contractors to meet these requirements, present status and future development potential are discussed as part of the overall goal of making the American merchant marine a strong competitor in the field of world trade.
Industrial Closed-Cycle Gas Turbines for Conventional and Nuclear Fuel
Authors: Keller C. , Schmidt D.
Published: April 2015

Development reports on closed-cycle gas turbines (CCGT) as proposed by Ackeret and Keller (AK system) and promoted mainly by Escher Wyss Ltd., Zurich, Switzerland, and Gutenhoffnungshütte (GHH), Germany, have been presented since 1945 at ASME meetings about every five years (1). This, the sixth paper, reports on the operating experience with some newer fossil-fuel fired plants made by different manufacturers and gives the study results of European designers for nuclear gas turbines which can be built already with today’s technology for the 600 to 1000-Mw range. The special physical properties of air and helium and their influence on plant design are discussed. The combination of a CCGT and a high-temperature reactor offers many possibilities for simplifications of nuclear plants and lowering capital costs.
Pneumatic Starting Systems
Authors: Von Flue Robert J.
Published: April 2015

Pneumatic starting systems for gas turbine engines are discussed. A general description of various energy sources, system components and arrangements is included. Systems are reviewed from the standpoint of energy utilization, versatility and reliability. It is concluded that the auxiliary gas turbine compressor/air turbine starter combination is the optimum arrangement, and, without a doubt, it will continue to be the primary starting means in gas turbine engine applications.
The Materials Challenge of High-Temperature Turbine Vanes and Blades
Authors: Martens W. R. , Raabe W. A.
Published: April 2015

Turbine vanes and blades are life-limited by one of three primary failure modes: creep, corrosion, and thermal fatigue. All of these modes are dependent upon the turbine inlet temperature; either the absolute temperature, or its rate of change. The development of better materials and the use of air cooling techniques have done much to reduce creep and thermal fatigue, but additional materials and coating development are required to solve the corrosion problem.
Residual Oil Combustion in Gas Turbines: State of the Art
Authors: Taylor William G.
Published: April 2015

This is a brief review of the problems encountered in the combustion of residual fuel in commercial gas turbines. The technical problems have been solved except for turbine deposit build-up running base load for long periods. Use of this fuel is economically marginal owing to increased operating complications and maintenance costs.
Control Design and Experience on CODAG-Powered 210-ft Reliance-Class Cutters
Authors: Hamilton Reed D.
Published: April 2015

The first successful CODAG-powered vessel to be built in the United States presented some interesting and unique control requirements and problems. The requirements were that the vessel speed must be the same for a particular handle position regardless of the propulsion machinery being used; and when operating as CODAG, the gas turbine and the diesel engine were to share the load under all operating conditions proportionate to their load-carrying ability. The design approach to solving this problem, including necessary data and curves, is outlined and explained in detail. While a thorough engineering job was done, there are always problems encountered in commissioning and tuning such a control system. The problems, solutions to these problems, and suggested improvements for a future control system are part of the discussion.
Experimental Results of a Transpiration-Cooled Turbine Operated in an Engine for 150 Hours at 2500 F Turbine Inlet Temperature
Authors: Lombardo S. , Moskowitz S. L. , Schnure S. A.
Published: April 2015

A key element in the development of gas turbine powerplants for advanced subsonic and supersonic aircraft is the ability to operate at turbine inlet temperatures significantly above the 1600–1800 F limit of today. This limit is imposed by the fact that current materials available for use in turbines exhibit inadequate strength and oxidation characteristics above 1600–1800 F. Certain metals such as molybdenum, chromium, tungsten and other high-melting-point alloys show good strength properties at temperatures far above which conventional super alloys are useful in turbines. However, these materials lack either the ductility or oxidation resistance necessary for turbine components. A means of realizing the gains possible by operating turbines at high turbine inlet temperatures is through cooling of the highly stressed turbine components. The necessity of reliable and efficient turbine operation for periods of long life in an environment of gas temperatures above the actual melting temperatures of the materials requires that effective means of cooling the blades be developed. The authors discuss the design of transpiration air cooled turbines as a means of operating engines at gas temperatures of 2500 F and higher, utilizing available turbine materials which are limited to metal temperatures between 1600 and 1800 F. The technique utilized in fabricating transpiration air cooled turbine blades is discussed. The results of operating a full-scale J65 engine, modified to incorporate a single-stage turbine fitted with transpiration air cooled blades, for 150 hr at 2500 F turbine inlet temperature are presented.
AiResearch Energy Systems Applications of the 831 Series Gas Turbines
Authors: Hoffman Russell V.
Published: April 2015

This paper discusses the commercial and industrial applications of the AiResearch Model 831 Turbopower Module. The 500-hp turbine is described with particular emphasis upon the functional and control characteristics that have gained for it an enviable place in the energy-conversion field. Accessory equipment such as exhaust heat exchangers, absorption chillers, and turbopowered compressors are described in sufficient detail to enable the reader to understand their operation. Three typical commercial and industrial applications are described with particular emphasis on illustrating the economic feasibility of these on-site turbopowered energy systems. The results of the successful application of turbo-powered energy systems are tabulated.
Mechanical Drive Combined-Cycle Gas and Steam Turbines for Northern Gas Products
Authors: Wobker B. F. , Knight C. E.
Published: April 2015

Gas turbines were selected for base-load operation because the waste heat could be utilized in this natural gas liquid extraction plant. It is the object of this paper to present the operation experience of a gas turbine driving a propane compressor used for base-load operation in a combined cycle. The turbines drive centrifugal refrigeration compressors for the extraction of propane, heavier liquid components, and helium from natural gas. As this is one of the largest plants of its type, the operating experience and performance are outlined. The selection, method of operation, reliability, and maintenance costs of this combined-cycle plant are discussed. It is not practical to generalize on selection of combining prime movers and major machinery for an extraction plant or a mechanical drive combined cycle. Each case must be individually evaluated and is dependent upon its location, application, and economic factors. The conclusion describes the reliability and availability of the combined cycle as borne out by approximately four years of operation.
V/STOL Aircraft Gas Turbine Requirements
Authors: Robbins O. G.
Published: April 2015

The gas turbine requirements for V/STOL aircraft are strongly influenced by the type of airplane and the mission to be performed. For pusposes of this paper, the gas turbine requirements are established in several propulsion-system concepts which encompass the majority of engine requirements necessary to the V/STOL airplanes. General requirements are explored which are common to gas turbines regardless of mission or airplane type. Specific requirements for the air-superiority fighter airplane, the subsonic fighter attack airplane, and the transport-cargo type of airplane are discussed. These three types of airplanes are propelled by propulsion systems incorporating lift turbojet engines, turbofan engines, fans with remote gas generators, and turboprop engines.
The Marine Gas Turbine Regenerator Material and Fabrication Considerations
Authors: Weber H. A. , Thorsrud E. C.
Published: April 2015

Gas turbine heat exchangers of the stationary and rotary types are used to increase power-plant thermal efficiency. Economic justification for the use of regenerative equipment depends on the criteria of initial cost and component life. Materials selection and fabricating techniques must be in accord with cost and life objectives. In this regard, the U. S. Navy Ship Systems Command has sponsored a program to investigate the particular problems associated with marine gas turbine heat exchangers. This paper presents the results of the investigation to date.
High Speed Cascade Testing and its Application to Axial Flow Supersonic Compressors
Authors: Breugelmans F. A. E.
Published: April 2015

This paper describes the high speed cascade program underway at the von Karman Institute Turbomachinery Laboratory in Belgium. The primary purpose of the program is to contribute to the understanding of turbomachinery flow problems at transonic and supersonic speeds. Supersonic axial flow rotor blade sections and subsonic stator blade sections are investigated in a high speed cascade facility. The paper describes the cascade facility, instrumentation, and blade sections investigated. The aerodynamic flow through high subsonic and supersonic cascade blades is discussed, and some data obtained in the cascade tunnel are compared with those obtained in a rotating machine. Several major problems of high speed cascade testing are discussed, although a final solution is not always presented.
The Role of High Temperature Gas Turbines in Power Generation
Authors: Barnes J. F.
Published: April 2015

The purpose of this paper is to examine some possibilities for achieving high gas temperatures in the turbines of both open-cycle and closed-cycle plant and to show how some of the experience gained from research, development, and design of internally cooled blading for aero-engines can be applied to industrial power generation. For the short-term future, preferred schemes would seem to embrace the use of internal air cooling for open-cycle plant and refractory metals without cooling for closed-cycle nuclear plant.
Some Operating Experiences With Gas Turbines Approaching the Maximum Limits of the Proposed ASTM No. 3 Fuel Specification
Authors: Hussey C. E. , Johnson K. W.
Published: April 2015

The current proposed ASTM GT fuel oil specifications for gas turbines imposes certain limits on contaminants. This paper presents some operating experiences with two gas turbines using a fuel oil that approaches these maximum limits for vanadium and sodium for the proposed Nos. 1, 2, and 3 GT fuels. One year’s satisfactory operation was achieved although evidence of minor corrosion was present, but insufficient to cause replacement of components.
16:1 Pressure Ratio Gas Turbine Recuperator
Authors: Topouzian Armen
Published: May 2015

This paper will discuss the specific development of the plate-fin type of recuperator utilized on the Ford Motor Company’s 16:1 pressure ratio, gas turbine engine.
Experience With the Olympus Powered Brown Boveri Gas Turbine Machinery of the Finish Navy 700 Ton Gunboat
Authors: Illingworth A. , Stys Z. Stanley
Published: May 2015

Commencing with a review of the relationship between the manufacturers of the gas turbine machinery, the paper goes on to describe the arrangement of the main propulsion machinery of the Finnish gunboat ‘Turunmaa’. The paper discusses the control arrangement and operation of the boat, and finally discusses the operating experience with the machinery.
Engine Vane Control
Authors: Babic George M. , Urban Louis A.
Published: May 2015

This paper presents some of the basic considerations underlying the choice of compressor inlet Mach number as a parameter to control the geometry of high performance variable stator compressors. One particular mechanization of the concept utilizing a pressure ratio sensor is described.
The Gas Turbine as a Source of Continuous Precise Power
Authors: Mackay Robin
Published: May 2015

Third generation computers require precise uninterrupted power. Without it, they can make errors or shut down. Where computers are used in real-time or time sharing applications, power quality is particularly important. Gas turbine-driven generators are now being used to provide continuous precise power. There is no connection to utility lines. One more generator set than is necessary to meet the load is always on line. Thus even in the event of a failure, the malfunctioning generator set can be isolated. The remaining set(s) can handle the full computer load without interruption. A series of tests were conducted to determine whether or not the turbine generator sets could maintain frequency during paralleling, simulated failures, shock loads, faults, and internal shorts. The results of the above tests along with sound level, maintenance and general installation information are included in this paper. Also covered are details of three specific installations currently on-line.
Fatigue Behavior of Titanium Castings
Authors: Bass C. D. , Harmsworth C. L.
Published: May 2015

The Air Force Materials Laboratory has conducted an internal test program to obtain design information on titanium alloy castings to facilitate a wider usage of this material where its application will benefit Air Force Systems. Emphasis was on obtaining room and elevated temperature fatigue data on the Ti-6Al-4V alloy in the annealed and heat-treated conditions. Limited fracture toughness, stress rupture and creep data were also obtained. The results showed generally favorable properties compared to forgings, plate and extrusions of the same alloy; however, existing production and inspection techniques do not always insure a flaw-free product.
The Potential of Titanium Castings in Gas Turbine Engines
Authors: Corey A. , O’Connor J. , Sprague R. , Donachie M.
Published: May 2015

The areas of potential usage of titanium in cast parts for gas turbine engines are delineated. Static structures are considered for cooler compressor and fan sections. The application of titanium in rotating hot section parts is evaluated. The need for alloy development to produce alloy compositions with unique properties as castings is emphasized.
Allison Model 501-K14 Gas Turbine 1000-Hr Saltwater Ingestion Test
Authors: Humphrey W. R. , Maas L. M.
Published: May 2015

The Allison Model 501-K14 industrial gas turbine engine, a modified version of the T56 aircraft engine, has been used extensively as a prime mover for industrial applications. The areas of application to date have been in the gas transmission field driving centrifugal gas compressors and driving electrical generators. This paper describes a 1000-hr cyclic test of the Model 501-K14 engine with salt water ingestion as the first step in qualifying the engine for marine application. Performance data, photographs of the installation and engine components, and inspection results are included in this report.
Some Consideration in the Design and Application of Heat Recovery Steam Generators
Authors: Hunt E. C.
Published: May 2015

The characteristics of heat recovery steam generation are compared to fully fired steam generators. Methods for stating performance are discussed. A compact forced circulation design is presented in some detail with comments on possible arrangements, construction methods, materials, and the use of supplementary firing. The importance of parallel control design to the ultimate success of the steam generator performance and operation is presented.
Diffusion Bonding Ti-6Al-4V for Jet Engine Applications
Authors: Peck J. V.
Published: May 2015

Diffusion bonding offers a means of fabricating hollow jet engine components such as disks and blades to provide weight reductions and internal cooling. Considerable emphasis has been placed on developing diffusion bonding technology for producing hollow titanium compressor blades. This paper summarizes the results of investigations aimed at establishing diffusion bonding parameters; i.e., time, temperature, and pressure for Ti-6Al-4V and determining the influence of surface preparation, postbond heat treatment and deformation control on bond quality and mechanical properties. Current results show that diffusion bonding of Ti-6Al-4V can produce joints having strength and ductility identical to parent metal.
Integration of Control and Fuel System Components Today and Tomorrow
Authors: Moulton L. J.
Published: May 2015

New gas turbine engines, because of their requirements for improved performance at lower weights, are placing additional requirements on the control and fuel system. At the same time control and fuel system must weigh less. Integration of certain control and fuel system components is one approach which has allowed some of these seemingly conflicting requirements to be met. While future control systems may be able to achieve some additional weight savings by additional integration, further use of new techniques particularly those in electronic and pneumatic computational components seem areas to be explored if step reductions in control weight and volume are to be attained.
Wall Temperature and Prandtl Number Effects on Turbulent Boundary Layer Thicknesses and Shape Factors for Subsonic Compressible Gas Flow Over a Flat Plate
Authors: Kelnhofer W. J.
Published: May 2015

Based on n-power velocity and temperature profiles a method of computing various turbulent boundary layer thicknesses and shape factors affected by wall temperature and Prandtl number for fully developed subsonic gas flow over a flat plate is presented. Density variation in the boundary layer is given main consideration. Numerical computations include both heating and cooling of gas. Boundary layer thicknesses and shape factors are shown to be significantly affected by wall temperature and to a lesser degree by Prandtl number. An experiment is described which involved air flow up to 30 m/sec over a flat plate maintained at constant wall temperatures up to 250 C. Comparisons between theory and experiment are good.
Optimization of the Turbine Compressor Set in the Closed Cycle (AK Process) System
Authors: Kinney C. A.
Published: May 2015

The closed cycle (AK process) originated in Europe in 1935 with the first application for patents on the system. Development since that time has been through the efforts of Escher Wyss of Switzerland and its licensees. Since the early 1950’s the U. S. Army has been a leading proponent of this concept for use within a compact, mobile nuclear power plant. Of major importance to this cycle is the selection of an optimized turbine compressor set in order to achieve the most useful work per pound of gas circulated. This will result in the achievement of highest system efficiency and the smallest component size possible. This paper will show a practical method for the selection of optimum pressure ratio for the turbine compressor set and compare predicted results with test results obtained at the Advanced Power Conversion Experimental Facility at Fort Belvoir, VA.
The Mechanical Design of a 10-Kw Feher Cycle Turbo-Alternator
Authors: Brass E. A.
Published: May 2015

The Feher cycle heat engine is a new approach to efficient and effective energy conversion. The mechanical design of the XFCTAP 01-01 10-kw Turbo-Alternator test unit is described with specific attention to the small turbomachinery component fabrication, the design of the hydrostatically stabilized self-acting fluid film radial bearings, overall rotor dynamics, thermal analysis of the turbine section, turbine tip clearance control, and the general construction of the machine. A preliminary layout of the unit is included.
The Dependence of Power Cycles’ Performance on Their Location Relative to the Andrews Curve
Authors: Casci C. , Angelino G.
Published: May 2015

The adoption of the closed cycle and of working fluids other than steam or air gives the possibility of utilizing for power cycles regions of the temperature-entropy diagram which are inaccessible when the working media are water or combustion products and which enjoy some useful peculiarities. A number of fluids are presented which are suitable for industrial applications and which allow the organization of power cycles covering the liquid, gaseous, and hypercritical regions of the state diagram of a typical substance. Efficiency, specific work, heat transfer surfaces, dimensions of turbomachines, distribution of losses among the various components relating to different fluids and cycles are analyzed and reported. The results strongly support the conclusion that the nature of the working fluid is a powerful tool to adapt the characteristics of power cycles to the widely differing requirements encountered in technical applications.
Vibration and Noise Characteristics of an Aircraft-Type Gas Turbine Used in a Marine Propulsion System
Authors: Harper R. E.
Published: May 2015

Sound and vibration data measured on a combination diesel gas turbine propulsion system in a 2000-ton antisubmarine warfare ship are presented. The data can be considered representative of the noise levels, both structureborne and airborne, that can be expected in an installation of this or a similar type. Examples of the attenuation of structureborne noise through selected structural joints illustrate the vibration isolation attainable through the use of lightweight aircraft-type structures.
Fan Compressor Noise Reduction
Authors: Benzakein M. J. , Kazin S. B.
Published: May 2015

A study of various fan/compressor noise reduction methods is presented. The analytical treatment of the basic mechanisms of fan/compressor noise generation is described. The results are presented in parametric form and indicate the effects of fan/compressor design, number of blades, vane/blade ratio, aerodynamic parameters, and blade row spacing on pure tone noise reduction. These results are based on nonsteady aerodynamic treatment of wake and potential interaction effects and theoretical extensions of spinning mode theories.
Speed Governing by Pulse Synchronized Duty Cycle Modulation Technique
Authors: Rabinowitz C. M. , Gentile A.
Published: April 2015

Digital techniques are being applied to the design of high performance electronic speed governors to obtain speed regulation of 0.1 percent or better. Achieving this accuracy is difficult, if not impossible, for a conventional analog governor, particularly when severe power supply and temperature variations are encountered. Accuracies of this order are practical goals for digital or hybrid electronic governors which use a stable frequency as a speed reference. This paper introduces and describes the operation of a hybrid electronic governor using duty cycle (pulse width) modulated signals to control speed, and which provides significant improvements over similar type governors described in earlier papers.
Systems Engineering Approach to Gas Turbine Marine Propulsion
Authors: Lauriat T. B.
Published: April 2015

This paper includes a description of the Systems Engineering approach to two representative marine propulsion systems utilizing gas turbine power. One approach deals with the Vosper VT-1 Hovercraft Propulsion engine manufacture and installation, the second deals with the much more detailed and sophisticated efforts required in producing and installing a complete marine propulsion system for a Navy Riverine assault craft. Preliminary scheduling to meet delivery dates, methods of part list procedures, testing philosophy, and methods of shipment are discussed, as well as customer liaison. The efforts of the Systems Engineering team are discussed in both cases pointing up the need for extremely close liaison in early vessel design stages to facilitate proper engine installation in the craft. Problems as they relate to earlier planning are included. The summary includes some actual vehicle test results.
Establishing the Longitudinal Temperature Distribution for Fully Developed Turbulent Flow in a Gas Turbine Exhaust Duct
Authors: Torpey P. J. , Welch R. M.
Published: April 2015

The ability to predict the longitudinal temperature distribution along a gas turbine exhaust duct facilitates the selection of the proper duct material and the appropriate paint or other external coating. It also allows accurate determination of thermal expansion over the entire length. A first-order differential equation is derived from a one-dimensional heat flow model for the exhaust system. A digital computer program employing this model is also presented. The computer solution, in addition to eliminating tedious manual computation, extends the analysis capability by accounting for changes in temperature and flow-dependent variables along the duct length. Measured gas and duct wall temperatures for a 1.5-kw gas turbine exhaust system are compared with values predicted by the analysis. Good agreement is noted throughout that portion of the system in which fully developed flow exists.
Justifications for an All-Radial 1600-HP Gas Turbine Engine
Authors: Mowill R. J.
Published: April 2015

The philosophy and justifications behind a large all-radial single-shaft gas turbine engine development are discussed. In addition, some of the factors affecting the marketing of a simple and low cost engine are dealt with.
Thermal Design of a Radiant Gas Heater for Brayton Cycle Power System
Authors: Evans D. M. , Pucci P. F.
Published: April 2015

The thermal design of a ground test gas heater for the NASA Brayton cycle power system is reviewed. The heater consists of a U-tube heat exchanger flowing a helium-xenon gas mixture, irradiated by a low-density pattern of tungsten filament quartz lamp heater modules, arranged to produce an exponential flux distribution along the tube axis. Choice of the correlating equation for gas-mixture forced-convection heat transfer, methods for selecting the most critical design cases with respect to flow friction and heat transfer, and the method of calculating radiant flux distribution for a particular heater module arrangement are discussed.
The Design and Operating Experience of a Mobile Gas Turbine With 16,000-HP Capability
Authors: Ritcey D. R.
Published: April 2015

This paper describes a mobile gas turbine driven compressor plant of 16,000-hp capability. The plant consists of two tractor trailer assemblies, one containing the gas turbine and the other the centrifugal compressor. A discussion of the design limits required by the mobility concept is included with the methods used to achieve these limits. A discussion of field operating experience after some 12,000 hr of operation is included with charts and graphs showing performance parameters of speed, power, and temperature.
A Practical Trace Element Monitoring System for Intermediate Gas Turbine Fuels
Authors: Obidinski E. S. , Johnson K. W.
Published: April 2015

Intermediate fuels (GT-3) are less expensive than distillates and do not cause difficulties in a gas turbine provided the contaminant level of the GT-3 oil is consistently kept below accurately set limits. The key to trouble-free operation is a reliable, relatively inexpensive and fairly fast on-site monitoring system. Experience with such a system was previously reported. The present paper discusses the on-site monitoring systems in some detail. The method provides results for metallic trace element analyses in the order of 10 ppm, within ±0.2 ppm, using the oil ash as the subject of investigation with a flame emission spectrophotometer, a colorimeter and an atomic absorption spectrophotometer. Elimination of interference effects is described and procedures for the appropriate solutions are shown. Investment costs and man-hour requirements are described.
Manufacturing Approaches to Resin Matrix Composite Airfoils for Gas Turbine Engines
Authors: Whitaker R. A. , Reinhart W. H. , Castle C. H.
Published: April 2015

Fan and compressor blades for gas turbine engines were identified early as potential applications for resin matrix composites. However, for these composites to reach production status, they have to be more effective than existing metal blades in both performance and cost. Graphite fiber and prepreg prices were surveyed for development and initial production price trends because composite material prices represent a significant portion of total part cost. Resin matrix composite airfoil construction is briefly described to aid in a later description of the related fabrication sequence. Manufacturing methods as currently anticipated for high volume production are discussed with regard to the fabrication sequence and effective material utilization. Quality requirements and appropriate inspection methods, both dimensional and nondestructive, are briefly reviewed. Several examples of current prototype work are described as they relate to proving out certain production processing concepts. It is important to work out volume production manufacturing methods concurrent to the composite blade design and engine testing efforts because both technologies have to be available if composite blades are to be accepted for use in an advanced technology engine.
The Combustion of Heavy Distillate Fuels in Heavy Duty Gas Turbines
Authors: Schiefer R. B.
Published: April 2015

Heavy distillate fuel oils are being offered for use in gas turbines at a significant reduction in fuel cost. This paper will summarize the characteristics of some of these fuels, their effect on gas turbine combustion performance, and the problems associated with their use.
Gas Turbine Testing on Naval Distillate Fuel
Authors: Siemietkowski J. S.
Published: April 2015

A Pratt & Whitney FT4A Marine Gas Turbine Engine rated at 22,600 hp, 3600 rpm was run at the Naval Ship Engineering Center, Philadelphia Division for 1000 hr. Fuel used was naval distillate having a vanadium level of 0.5 ppm. Basically there was no problem with engine operation on naval distillate when compared to diesel fuel. The smoke level was barely visible at high powers. Coalescent fuel filters are a problem due to their relatively short (100–130 hr) life. The corrosion rate was accelerated when compared to navy diesel fuel. The fuel parameter suspect is vanadium, however other parameters may be at fault. Additional efforts are required into definitely determining the cause of accelerated corrosion and also into optimizing nozzle guide vane and turbine blade base materials and coatings.
Enhanced light trapping and plasmonic properties of aluminum nanorods fabricated by glancing angle deposition
Authors: Abdulrahman Rosure Borhanalden , Cansizoglu Hilal , Cansizoglu Mehmet F. , Herzog Joseph B. , Karabacak Tansel
Published: May 2015

Vertically aligned arrays of aluminum (Al) nanorods were fabricated by glancing angle deposition (GLAD) method. Nanorods with maximum lengths of 200 and 350 nm were grown on 100 nm flat Al thin film. Total and diffuse reflectance profiles were measured using an ultraviolet–visible–near infrared (UV-Vis-NIR) spectrophotometer utilizing an integrating sphere to study detailed optical properties of Al nanorods in comparison to conventional planar Al thin film samples. Finite-difference-time-domain (FDTD) optical modeling method was utilized to simulate the optical response of Al nanorod array and thin film structures. FDTD simulations were carried out for periodic and random arrays of Al nanorods as well as for an isolated single nanorod in order to investigate effects of geometrical structure on plasmonic and light trapping effects. UV-Vis-NIR spectrum results reveal that total reflectance is inversely proportional with nanorod length, and decreases down to as low as ∼25%–30% in the visible spectrum at wavelengths smaller than ∼750 nm, while it stays at ∼85%–90% for flat Al thin films at those wavelengths. FDTD simulation results indicate significant light absorption by GLAD Al nanorods mainly originating from enhanced light trapping and surface plasmon resonance among the nanorods.
Ultrasound tomography for simultaneous reconstruction of acoustic density, attenuation, and compressibility profiles
Authors: Mojabi Pedram , LoVetri Joe
Published: April 2015

A fast and efficient forward scattering solver is developed for use in ultrasound tomography. The solver is formulated so as to enable the calculation of scattering from large and relatively high-contrast objects with inhomogeneous physical properties that vary simultaneously in acoustic attenuation, compressibility, and density. It is based on the method of moments in conjunction with a novel implementation of the conjugate gradient algorithm which requires the use of the adjoints of the scattering operators. The solver takes advantage of the symmetric block Toeplitz matrix with symmetric Toeplitz blocks property of the Green's function matrix to increase efficiency and only stores the first row of this matrix to reduce memory requirements. This row is then used for the matrix-vector multiplication using the fast Fourier transform technique, thus, resulting in the computational complexity of O(n log n). The marching-on-source technique is also used to provide a good initial guess which allows the conjugate gradient technique to converge faster than initializing with an arbitrary guess. This feature is important in tomographic inversion algorithms which require that the object to be imaged be interrogated via several incident fields. Forward scattering and inversion examples, based on the Conjugate Gradient Least Squares regularized Born Iterative Method, are shown, in two-dimensions, for objects varying in all three physical properties.
Estimation of aircraft angular coordinates using a directional-microphone array—An experimental study
Authors: Genescà Meritxell , Svensson U. Peter , Taraldsen Gunnar
Published: April 2015

Ground reflections cause problems when estimating the direction of arrival of aircraft noise. In traditional methods, based on the time differences between the microphones of a compact array, they may cause a significant loss of accuracy in the vertical direction. This study evaluates the use of first-order directional microphones, instead of omnidirectional, with the aim of reducing the amplitude of the reflected sound. Such a modification allows the problem to be treated as in free field conditions. Although further tests are needed for a complete evaluation of the method, the experimental results presented here show that under the particular conditions tested the vertical angle error is reduced ∼10° for both jet and propeller aircraft by selecting an appropriate directivity pattern. It is also shown that the final level of error depends on the vertical angle of arrival of the sound, and that the estimates of the horizontal angle of arrival are not influenced by the directivity pattern of the microphones nor by the reflective properties of the ground.
Isogeometric analysis of free vibration of simple shaped elastic samples
Authors: Kolman Radek , Sorokin Sergey , Bastl Bohumír , Kopačka Ján , Plešek Jiří
Published: April 2015

The paper is devoted to numerical solution of free vibration problems for elastic bodies of canonical shapes by means of a spline based finite element method (FEM), called Isogeometric Analysis (IGA). It has an advantage that the geometry is described exactly and the approximation of unknown quantities is smooth due to higher-order continuous shape functions. IGA exhibits very convenient convergence rates and small frequency errors for higher frequency spectrum. In this paper, the IGA strategy is used in computation of eigen-frequencies of a block and cylinder as benchmark tests. Results are compared with the standard FEM, the Rayleigh-Ritz method, and available experimental data. The main attention is paid to the comparison of convergence rate, accuracy, and time-consumption of IGA against FEM and also to show a spline order and parameterization effects. In addition, the potential of IGA in Resonant Ultrasound Spectroscopy measurements of elastic properties of general anisotropy solids is discussed.
Effects of exposure to intermittent and continuous 6–7 kHz sonar sweeps on harbor porpoise (Phocoena phocoena) hearing
Authors: Kastelein Ronald A. , Gransier Robin , Schop Jessica , Hoek Lean
Published: April 2015

Safety criteria for mid-frequency naval sonar sounds are needed to protect harbor porpoise hearing. A porpoise was exposed to sequences of one-second 6–7 kHz sonar down-sweeps, with 10–200 sweeps in a sequence, at an average received sound pressure level (SPLav.re.) of 166 dB re 1 μPa, with duty cycles of 10% (intermittent sounds) and 100% (continuous). Behavioral hearing thresholds at 9.2 kHz were determined before and after exposure to the fatiguing noise, to quantify temporary hearing threshold shifts (TTS1–4 min) and recovery. Significant TTS1–4 min occurred after 10–25 sweeps when the duty cycle was 10% (cumulative sound exposure level, SELcum: ∼178 dB re 1 μPa2s). For the same SELcum, the TTS1–4 min was greater for exposures with 100% duty cycle. The difference in TTS between the two duty cycle exposures increased as the number of sweeps in the exposure sequences increased. Therefore, to predict TTS and permanent threshold shift, not only SELcum needs to be known, but also the duty cycle or equivalent sound pressure level (Leq). It appears that the injury criterion for non-pulses proposed by Southall, Bowles, Ellison, Finneran, Gentry, Greene, Kastak, Ketten, Miller, Nachtigall, Richardson, Thomas, and Tyack [(2007). Aquat. Mamm. 33, 411–521] for cetaceans echolocating at high frequency (SEL 215 dB re 1 μPa2s) is too high for the harbor porpoise.