bluuebunny/crossref_metadata_2025 huggingface dataset:
Cycle Flexibility: It’s Impact on V/STOL Tactical Aircraft Propulsion Systems
Authors: Hoelzer C. A. , Cea R. A.
Published: April 2015

The design of a V/STOL aircraft, incorporating only one lift-cruise engine places great emphasis on the flexibility of its propulsion system to provide sufficient thrust for take-off and efficient fuel consumption for cruise. In order to attain a reasonable range with a lightweight vehicle this inconsistency of thrust and SFC mis-match must be resolved. A brief survey of engine technology predictions for the next decade indicates that future aircraft systems would be offered a wider choice of cycle characteristics, higher technology levels, and added cycle flexibility. A comparative parametric study was conducted to determine the effect of these advancements on a postulated 1983 V/STOL aircraft. In particular the effect of increasing thrust through the use of thrust lapse-rating and variable turbine geometry were compared to more conventional augmentors such as duct burning and water injection. Additionally, the effects of varying cycle characteristics to realize SFC improvements were investigated.
Propulsion System and Airframe Integration for Jet-Lift V/STOL Airplanes
Authors: Weber H. A. , Karemaa Aadu
Published: April 2015

The design of a vertical or short takeoff and landing airplane powered by jet or turbofan lift engines is primarily an exercise in propulsion package and airframe matching. This task is complicated by the unique requirements and constraints imposed by the takeoff and landing profiles of hybrid jet-lift airplanes. Performance of such aircraft is sensitive to the overall propulsion system capabilities, specifically to thrust vector management, lift-engine bypass ratios, airframe-engine interactions and power plant packaging. In turn, the complete propulsion system design is related to the airplane wing loading and aerodynamic high-lift system. This paper examines the propulsion system/airframe matching considerations that influence the V/STOL vehicle propulsion system design, as seen from the preliminary design engineer’s point of view.
A Steady-State Radial Inlet Pressure Distortion Index for Axial-Flow Compressors
Authors: Brunda D. F. , Boytos J. F.
Published: April 2015

A radial inlet pressure distortion index is derived using a mathematical compressor model, the two-dimensional continuity equation and the expression for radial velocity upstream of a low hub-tip ratio, multi-stage compressor. These expressions are combined with two conditions required for inlet flow similarity at compressor stall; namely, constant rotor angle of attack and constant ratio of mixing time to air residence time in the blade passage. The theory was tested on a twin-spool turbojet engine at sea level static conditions.
Noise and Other Environmental Considerations in the Design and Planning of Gas Compressor Stations in the U.K.
Authors: Cleveland A.
Published: April 2015

This paper briefly outlines some of the considerations taken into account in the design and planning of gas compressor stations for the UK Natural Gas Transmission System. Environmental considerations, and in particular the aspects of noise, play a large part in the design of these stations. The requirements for silencing to meet very low ambient noise levels and the development of gas turbine compressor unit enclosures is dealt with in some detail. The need for acoustically efficient and aesthetically pleasing structures is emphasized. The paper compares some representative alternative designs for individual enclosures with the design of an equivalent building and concludes that for small numbers of units, the individual enclosure is the economic solution. Other aspects of noise, including venting of gas are discussed and future design trends indicated. In the consideration of future designs, ease of maintenance and security are fundamental considerations, together with the need to ensure that noise emitted will not pollute the environment.
Experience With Industrial Gas Turbines Used in a 3 by 15,000-hp Gas Compressor Station
Authors: Arvidsson F. L. , Ekman S. N. , Ljung Lars R.
Published: April 2015

The first three units of the improved industrial 15,000-hp gas generator GT35 were taken into commercial operation during 1970 in a gas compressor station for the Nederlandse Gasunie in Wieringermeer, the Netherlands. This paper gives a description of the equipment and deals with the experience from workshop tests, commissioning and commercial operation.
Fuels for Marine Gas Turbines Requirements and Availability in the 1970’s
Authors: Morrow A. S.
Published: April 2015

This paper briefly reviews the development of specifications for fuels which can be burned in marinized aircraft and industrial-type gas turbines for ship propulsion and auxiliary power. It then considers the types of fuels — gas to residual — which will be available on a worldwide basis during the ‘70s, logistics involved, and potential problems that can develop in handling and firing them.
Combustion of Heavy Distillate Fuel for the LM2500 Gas Turbine
Authors: Ekstedt E. E. , Macaulay R. W.
Published: April 2015

The LM2500 is a Marine and Industrial gas turbine derived from the TF39 engine built for the USAF C5A transport. As such it operates as a core engine without the high bypass fan supercharging effect. The combustor for the LM2500 is an annular combustor developed for use with marine and industrial fuels including natural gas and heavy distillates. This paper relates the development of this combustor including some of the design criteria, the fuel properties and some of the combustor performance results such as exit gas temperature patterns, ignition, pressure loss, and efficiency. The engine combustor operates with a clear smokeless stack utilizing heavy distillate fuels and is free of carbon formation. Fuel properties and atomization properties are related to exhaust smoke. Investigations have included a wide range of fuels and several fuel injector designs. The engine has operated in GTS Adm. Wm. M. Callaghan for a total of more than 10,000 hrs with no combustor problems, smoke, carbon, life or otherwise.
Crashworthiness of Safe Fuels
Authors: Rockow R. A. , Shaw L. M.
Published: April 2015

Safety fuels such as emulsified and gelled fuels have been studied over the past several years as one means for reducing the post-crash fire hazard associated with aircraft accidents. However, through the work described herein, only recently has a quantitative evaluation been made to characterize the safety performance of these fuels. The safety performance evaluation program described in this paper includes an initial series of screening tests designed to obtain the characteristics of safe fuels in the aircraft crash environment. The authenticity of the screening tests relative to the full-scale crash environment was evaluated through a second series of experiments designed to simulate a full-scale aircraft crash environment. A crashworthiness evaluation criterion was established in terms of an “ignition susceptibility parameter” to quantitize the relative safety performance of different fuels. The conclusions of this research clearly show that significant savings in lives and equipment can be realized if safe fuels which perform within the non-hazardous envelope of the ignition susceptibility parameter are operationally incorporated in present-day aircraft.
Computation of Shocked Flows in Compressor Cascades
Authors: Gopalakrishnan S. , Bozzola R.
Published: April 2015

A numerical technique is presented for the calculation of shocked flows in compressor cascades. The problem is posed in the time-dependent form and the asymptotic solution at large times provides the solution of the steady physical problem. The solutions exhibit the formation and movement of shocks as the static pressure ratio across the cascade is varied. The resulting inlet and outlet angles and total pressure loss are also shown.
Two-Dimensional Flow Losses of a Turbine Cascade With Boundary Layer Injection
Authors: Tabakoff W. , Earley R.
Published: April 2015

A method for determining the performance of a two-dimensional turbine cascade with boundary layer injection is developed using existing incompressible boundary layer approximate solutions with a new formulation for the injection. The overall cascade loss includes friction and wake mixing losses. The results of the analysis are compared with experimentally obtained data as a check of the validity of the new analytical method.
A Comparison of the Predicted and Measured Performance of High Pressure Ratio Centrifugal Compressor Diffusers
Authors: Kenny D. P.
Published: April 2015

A novel analysis of the hub and shroud wall boundary layer growth through the diffusing system of a centrifugal compressor is proposed to model the physical processes. It is shown that the diffuser throat blockage and total pressure loss characteristics can be accurately predicted for a 6:1 PR stage. The static pressure effectiveness and stalling limit are successfully predicted qualitatively, but are underestimated and overestimated by 14 and 12 percent respectively. It is argued that diffuser performance is largely controlled by the combined effect of the boundary layer conditions on the hub and shroud walls at impeller exit and the diffusion required to the diffuser throat. For this reason, it is contended that, for best performance at high pressure ratio (≃ 12:1), impeller exit Mach number must be minimized by employing zero to negative prewhirl at impeller entry which in turn maximizes impeller entry shroud relative Mach number. Performance maps are presented for a single-stage centrifugal compressor based on this premise with specific speed = 90. At 15, 12 and 101 PR, 72, 75 and 76.8 percent efficiency, respectively, were attached at 2.6 lb/sec.
Instrumentation for Flow Measurements in Turbomachine Rotors
Authors: O’Brien W. F. , Moses H. L.
Published: April 2015

Flow measurements taken on the rotors of turbomachines are of great value for improved understanding and advancement of design techniques. On-rotor experiments have been limited in the past because of instrumentation problems, especially with the data transmission system. Recent advances in miniature electronic systems and transducer technology have produced a renewed interest in this area. These considerations are discussed, and research on a telemetry-type data transmission system is described with experimental verification using a strain gage on an axial-flow fan blade.
Dense Si3N4 and SiC: Some Critical Properties for Gas Turbine Application
Authors: Lange F. F.
Published: April 2015

Both Si3N4 and SiC in their dense forms are leading candidate ceramics for gas turbine components because of their unique physical properties that minimize the thermal stresses which develop during gas turbine operation and their ability to resist oxidation at high temperatures. The purpose of this paper is to present current property data for both materials that are required to calculate thermal stresses, i.e., strength, Young’s modulus, Poisson’s ratio, thermal expansion, thermal conductivity, and specific heat.
Variable Pitch Ducted Fans for STOL Transport Aircraft
Authors: Denning R. M.
Published: April 2015

The Variable Pitch fan has a number of features which make it attractive as the basis for ultra-high bypass ratio ducted fans designed primarily for STOL aircraft. The variability imposes certain design constraints, particularly on fan pressure ratio, and leads to differences in engine geometry relative to equivalent fixed pitch engines. The merits of such engines are discussed under the headings of Performance, Noise, Engine Control, Thrust Modulation, Provision of Air Bleed for High Lift, Reverse Thrust and Development Flexibility.
Gas Turbine Power Generation and Motor-Driven Compressors are Featured in Unique Compressor Station Design
Authors: Wrenn K. F.
Published: April 2015

This paper describes the economic and technical justification for applying motor-driven compressors powered by on-site generated electricity. This application is unique in the gas pipeline industry and can be employed only under special conditions. The governing conditions are discussed and the alternatives that were considered are presented. The electrical expertise required for the project was contributed by the major equipment supplier, and the scope of this effort is presented. The equipment has been in operation for more than 14 consecutive months, so that reliable operating costs and experience can also be considered.
The ST6 Vehicular Experience
Authors: Hardy G.
Published: April 2015

ST6 gas turbine engines in the 600-shp class have been used in many different vehicles ranging from high-speed turbo trains to Indianapolis roadsters. This experience has lead to the development of operating characteristics and design features of the engine which have improved its performance and reliability. In addition much has been learned about how to rate turbine engines and how to predict maintenance and overhaul periods in vehicular operation. This experience will be useful for future applications of turbine engines to vehicles and for design input to new turbine engines being considered for automotive use. The ST6 has proven itself well suited for prime or auxiliary power use in many types of vehicles.
Military Vertical Takeoff and Landing (VTOL) Propulsion Systems Design
Authors: Kohn A. O.
Published: April 2015

This paper deals with the parameters that must be considered in the selection and design of propulsion systems for military VTOL aircraft. Some of these parameters, for instance lightweight, are applicable to engines for all types of aircraft. For the VTOL aircraft, special emphasis must be placed on many of these parameters since aircraft takeoff gross weight determines engine size. Other significant considerations in the selection of the propulsion system include: (a) the ratio of subsonic cruise thrust to maximum thrust; and, (b) exhaust downwash characteristics. Consideration (a) is important because, in the case where no auxiliary lift engines or devices are used, subsonic cruise thrust is about 25 to 30 percent maximum, and at this low power setting, specific fuel consumption is increasing rapidly. Exhaust downwash characteristics are significant because of the variety of landing and takeoff sites likely to be encountered (i.e., shipboard or unprepared fields).
British Experience Using the Aero Derived Gas Turbine for Main Propulsion in Air Cushion Vehicles and Fast Patrol Craft
Authors: Woodward M. L.
Published: April 2015

The paper outlines the experiences which have resulted from the application of two gas turbine engines (Proteus and Gnome) to provide main propulsion in marine craft. The emphasis is on the use of these engines in the Air Cushion Vehicle (Hovercraft). Summarizing the lessons learned with the Marine Proteus powering fast displacement craft, and the development of the engine for this role, the author then relates this work to the advent of Hovercraft. The fore-running small hovercraft had been largely dependent on the Marine Gnome engine, and much of the experience with both units can be cross-related. Marine Proteus entered the hovercraft world in the larger vehicles. This experience is discussed in some detail, and is further correlated to the continuing build-up of usage of the same engine in Fast Patrol Boats and Hydrofoil Craft.
Aerodynamic Damping in Turbomachinery
Authors: Cavaillé Y.
Published: April 2015

An experimental study of aerodynamic damping has been carried out on an axial compressor in which stagger angle, pressure ratio, and relative velocity was varied. The study utilized explosive charges buried in the tip of the blade to provide excitation and found the damping by measuring the log decrement of the vibrations. The blade vibratory mode was pure bending.
Proposed Gas Turbine Procurement Standard Maintenance Considerations
Authors: Foster-Pegg R. W.
Published: April 2015

It is in the interests of both the prospective owner and the manufacturer of a gas turbine that equipment be purchased suited to the owner’s maintenance facilities and the features be incorporated to facilitate preventive and corrective maintenance in the intended service. A purchase decision should include consideration of probable cost of maintenance and the procurement document should elicit this information. These considerations together with information which must be provided by a prospective owner and a manufacturer to reach an understanding are discussed in this paper.
Modularization and Installation of the Gas Turbine Propulsion System in Euroliner
Authors: McAllister P. J.
Published: April 2015

This paper discusses the modularization and installation of the FT4 gas turbine engines and the automatic propulsion control system aboard the high-speed container vessel, Euroliner, vanguard of four ships to open a new container transportation system in the North Atlantic.
Generalized Outlook on Marine Gas Turbine Hot Section Deterioration
Authors: Rogus B. J. , Weinert E. P.
Published: April 2015

Investigators have compared results of gas turbine hot section material rig tests to field experiences with identical materials. They proposed that such correlation would be useful for turbine design engineers. But gas turbine users, particularly in the marine field, need a guide to correlate the few reported hot section experiences and realistically project when parts should be replaced. It is suggested that most hot section materials in properly protected marine gas turbines have much lower deterioration rates than those predicted. After coatings on turbine nozzles and blades have been operationally removed, increasingly better predictions of replacement time are possible. Sample at-sea experiences and environmental full-scale test results are offered to illustrate some unity among isolated experiences within a generalized framework of gas turbine hot section deterioration. A method for predicting further useful life of hot parts is proposed. A procedure and tool for in-place nondestructive evaluating of hot section deterioration are offered with a guide for scheduling future maintenance sections.
The Treatment of Marine Heavy Fuels for Gas Turbine Combustion
Authors: Cullen P. J. , Urbas T. A.
Published: April 2015

The resurgence of interest in the heavy duty gas turbine for marine use is due in a large part to its ability to burn residual and crude fuels. Generalities involving fuel treatment requirements have been bandied about for years and often the wrong information is used by unknowledgeable individuals when making quotations or bid evaluations. The purpose of this paper is to present firm information on the treatment of marine fuels for heavy duty gas turbines.
Design and Testing of Two Supercritical Compressor Cascades
Authors: Rechter H. , Schimming P. , Starken H.
Published: April 2015

Based upon a blade pressure distribution similar to that one proposed by D. Korn, a supercritical cascade blade section was developed for a transonic compressor stator. The design inlet Mach number of M1 = 0.8 and the flow turning of Θ = 36.8 deg resulted in a diffusion factor around D = 0.5 and the blade suction surface pressure distribution was optimized with the aid of a boundary-layer calculation. In order to obtain the related cascade geometry, an inverse blade calculation was performed by E. Schmidt (University of Stuttgart) solving the potential flow equation with a finite difference relaxation method. In the experimental cascade tests, reasonable performance could be obtained at design point conditions for reduced loading (increeased axial velocity density ratio). However, the performance at lower inlet Mach numbers and different inlet flow angles was not acceptable. This was attributed to the measured blade pressure distribution, which differed from the design in the leading edge region. Based upon these results, a second supercritical cascade blade section was developed for the same inlet flow conditions and identical flow turning. The modified pressure distribution included also an axial stream tube contraction. The design intent was verified by the cascade tests which showed an improved performance at design and off-design. The combination of boundary layer and inverse blade-to-blade computation promises to become an effective design tool for axial flow compressors.
Maintenance Considerations in the Design of the Direct-Cycle Nuclear Gas Turbine Power Plant
Authors: McDonald C. F. , Paget J. A.
Published: April 2015

In the integrated gas turbine high temperature gas cooled reactor (GT-HTGR) plant, all of the helium turbine power conversion machinery operates on the reactor coolant helium and is installed inside the reactor vessel; therefore, it is important that maintenance aspects be considered during the plant conceptual design phase. The primary objective of the GT-HTGR plant maintenance and inspection plan is to provide facilities, equipment, and component designs of reasonable cost that will yield good plant availability. It is, therefore, a matter of policy to design the reactor and the power conversion system installation, as well as the related maintenance facilities, for practical operation for both planned and unplanned maintenance. All primary system equipment is designed for full plant lifetime, with no limited-life parts, and the influence of maintenance considerations on the design of the major components and the plant configuration is discussed. Turbomachinery change-out is regarded as a planned maintenance activity and the sequence of events, together with the necessary equipment items, for removal and re-installation of helium gas turbine is discussed. The maintenance and repair of components such as the heat exchangers, ducting, and valves, which are designed to last throughout the plant lifetime but could fail due to unforeseen circumstances, are also discussed.
Core Design Considerations for a Large Gas Turbine HTGR
Authors: Rao R. , Baxter A.
Published: April 2015

Advanced high-temperature gas-cooled reactor (HTGR) design concepts for energy production using gas turbine applications depend on cores capable of generating helium coolant outlet temperatures up to 900 C (1652 F). This paper describes a preliminary analysis of a large HTGR [4000 MW (t)] core using a prismatic fuel with coolant gas core outlet temperatures of 850 C (1562 F). This study provides core design considerations in the areas of radial fuel zoning, power distribution, fuel performance, fuel temperatures, and fission product release for a large HTGR core operating under high-temperature conditions. Though the work was performed on a 4000-MW(t) core, all design considerations developed are equally applicable to a 3000-MW(t) core. Potentials for upgrading the core performance and suggested improvements for implementation in future design work are cited.
Determination of the Reynolds-Stress Tensor With a Single Slanted Hot-Wire in Periodically Unsteady Turbomachinery Flow
Authors: Kool P.
Published: April 2015

The pitchwise distribution of the components of the Reynolds stress tensor downstream of a rotating blade row can be obtained with a single slanted hot-wire and the technique of periodic sampling and averaging. The requirements imposed on the hot-wire and the sensitivity coefficients to the six stresses are given. Information concerning the electronic set-up and the problems associated with measuring the Reynolds stresses are discussed. It is shown that the sampling technique does not modify the mean square value of the sampled signal if the correlation time of the turbulence is smaller than half the sampling rate, or when the frequency bandwidth of the turbulence is higher than twice the sampling frequency. Typical results, including the 3D-mean flow data obtained downstream of a low-speed axial compressor rotor at different radii are presented. The results show typical modifications of the stresses in the rotor wake region and the regions influenced by secondary flow or tip-leakage flow.
An Engineering Approach to Cumulative Damage Fracture Mechanics in Gas Turbine Disks
Authors: Annis C. G.
Published: April 2015

An empirical description of fatigue crack propagation (FCP) under complex loadings, typical of those experienced by gas turbine disks, is presented. This approach uses a three coefficient sigmoidal curve (SINH) to model the macroscopic effects on FCP of service overloads, dwells, and load sequencing, as well as basic influences of frequency, stress ratio, and temperature. The coefficients are then related to these growth-controlling parameters through simple, linear, empirical functions. Comparisons are made of this approach with more conventional methods, and the results of laboratory verification tests are presented.
Synchronous Unbalance Response of an Overhung Rotor With Disk Skew
Authors: Salamone O. J. , Gunter E. J.
Published: April 2015

This paper deals with the influence of disk skew on the synchronous unbalance of flexible rotors in damped bearings. A simple overhung rotor 1E treated to illustrate the effects of various combinations of unbalance and disk skew on the amplitude and phase angle response at the disk and bearings. The paper shows that it is impossible to balance the rotor at all speeds by single plane balancing even if three correction planes are employed. The presence of disk skew may be best detected by monitoring the far bearing for a rapid phase angle decrease after passing through the first critical speed.
Methane Utilization
Authors: White D. J. , Rito R. J. Fio
Published: April 2015

Methane/air volumetric mixtures (gob-gas) ranging from 10 to 40 percent methane have been experimentally evaluated in the Solar Low Calorific Value Gas Combustor Facility. The majority of data was taken at ambient atmospheric conditions at the inlet to the combustor with some testing to 200 C (400 F) inlet temperature and two atmospheres pressure. Operational fuel-air ranges for 99 percent combustion efficiency were defined as well as the lean extinction limits for the above mentioned range of gob gas mixtures. This latter reduced data has been correlated so as to provide approximate combustor design functions.
Radiative Heat Transfer From Gas Turbine Flames
Authors: Ferguson C. A. , Mellor A. M.
Published: April 2015

Measurements have been made of the normal component of the radiative heat flux to the wall of a model gas turbine combustor with and without a mirrored background. Measurements have also been made of the centerline soot concentration. The data show that the heat flux correlated with the soot concentration but not universally, since JET A fuel yielded a different curve 1han DIESEL fuel. A theoretical analysis of the heat flux from a soot suspension was formulated. A criterion was established for the use of a small particle analysis. Finally, it is shown that there is no correspondence between theory and these experiments. It is speculated that turbulent fluctuations need to be modeled.
Relationships for Nozzle Performance Coefficients
Authors: Beans E. W.
Published: April 2015

The relationships between the performance coefficients for flow, kinetic energy, and thrust are developed for the irreversible adiabatic flow through a choked nozzle. The basis of the development is maximum flowrate per unit area and an exit pressure greater than or equal to the exhaust pressure. The relationships cannot be presented in explicit mathematical form. However, from the application of linearizing techniques, linear relationships have been developed, which are accurate to within 0.1 percent. The relationships allow one to determine two performance coefficients from empirical data for a single coefficient. The relationships also allow one to predict difficult to measure flow properties such as the exit plane pressure for a choked nozzle. The applicability of the development to supersonic and unchoked nozzles is discussed.
Major Considerations in the Design and Engineering of Cogeneration Facilities
Authors: Kropp R. E. , Hansen E. J. , Destefanis R.
Published: April 2015

Most cogeneration facilities considered since the Arab oil embargo have been limited to study activity. These studies are based primarily on regulatory and economic constraints. Important factors to be considered include site, fuel, and capital requirements for various options. This paper examines several studies and their findings and comments on the advantages and disadvantages of various systems including combustion turbines, coal fired steam boilers and turbine generators.
Application of a Power Recovery System to Gas Turbine Exhaust Gases
Authors: Baudat N. P. , James O. R.
Published: April 2015

This paper discusses the application of a power recovery system to recover waste heat from the exhaust gases of gas turbines and convert this energy into shaft horsepower. Also discussed are power cycles, selection of power fluid, equipment selection, and application of the power recovery system to various gas turbines. Several charts and tables are included: process flow diagram, cycle efficiencies, curve for estimating recoverable horsepower.
Acoustic Control of the Exit Plane Thermodynamic State of a Combustor
Authors: Vermeulen P. J. , Odgers J.
Published: April 2015

A combustor of the gas turbine type, employing acoustic control of the dilution-air jet flows, was designed and successfully tested. Temperature measurements showed that acoustic modulation of the dilution-air flows can be used to selectively and progressively control the exit plane temperature distribution. The effectiveness of the process was found to depend on the excitation frequency and power of the loudspeaker drivers. Reductions in the exit plane temperature profile, by as much as 545 C, were observed. The mechanism of interaction between the modulated dilution-air flow and combustor main gas flow appears to depend on the combined effect of pulsed flow with superimposed toroidal vortex. The increase in pressure drop across the combustor, associated with the operation of the acoustic drive, was found to be negligible. The work contributes to the design of combustors such that a desired exit plane temperature distribution may be achieved.
Three-Dimensional Lifting-Surface Theory for an Annular Blade Row
Authors: Homicz G. F. , Lordi J. A.
Published: April 2015

A lifting-surface analysis is presented for the steady, three-dimensional, compressible flow through an annular blade row. A kernel-function procedure is used to solve the linearized integral equation which relates the unknown blade loading to a specified camber line. The unknown loading is expanded in a finite series of prescribed loading functions which allows the required integrations to be performed analytically, leading to a great savings in computer time. Numerical results are reported for a range of solidities and hub-to-tip ratios; comparisons are made with both two-dimensional strip theory and other three-dimensional results.
The Prediction of Steady, Circumferential Pressure and Temperature Distortions in Multistage Axial Flow Compressors
Authors: Mokelke H.
Published: April 2015

A small perturbation theory is presented for the prediction of the decay of steady circumferential pressure, temperature and velocity distortions in multistage axial flow compressors. The mathematical model which is employed replaces the blade rows of the compressor by actuator discs. A closed solution for the linearized equations describing the two-dimensional, inviscid and compressible flow between the discs is derived and appropriate matching conditions at the discs (assuming a quasi-steady blade response) are determined. An efficient calculation procedure is presented which allows the rapid computation of the distortion development through any compressor configuration, i.e., through any combination of rotors, stators, and axial clearances including the core engine compression system. The theory can be applied to the mean section of the compressor or separately from stream surface to stream surface. Due to the assumption of a two-dimensional flow, however, it is restricted to purely circumferential distortions in compressors with sufficiently high hub-to-tip ratios where radial flow redistributions can be expected to be small. The validity of the small perturbation theory is demonstrated by comparing the theoretical results with experimental data. In addition, the theory is used to study the effect of Mach-number and flow rate on the decay of the distortions through two compressor configurations. Suggestions are made on how to utilize the theory for the design of distortion-tolerant compressors.
Catalytic Combustion for Gas Turbine Applications
Authors: Krill W. V. , Kesselring J. P. , Chu E. K.
Published: April 2015

Developments in catalytic combustion have shown increasing potential for application in gas turbine combustors. Significant advantages in reducing combustor emissions, particularly nitrogen oxides (NOx), can be realized. Both thermal and fuel NOx control were demonstrated for a developed graded cell catalyst concept. Other criteria for catalyst scaleup and high pressure operation have been developed. The concepts have been demonstrated in a catalytic model gas turbine combustor and a catalytic staged combustor. The staged combustor shows great potential for control of fuel NOx. New concepts in turbine combustors are required to implement catalytic combustion technology. Gas turbine manufacturers were surveyed to identify design criteria. The established criteria were prioritized and incorporated into several conceptual designs for the combustor. Ongoing development will advance the concepts to prototype demonstration.
Control of Combustion Turbine Particulate Emissions Verified by Improved Measurement Technology
Authors: Ambrose M. J. , Obidinski E. S. , Marlow J. H.
Published: April 2015

Early field tests on 25- and 33-MW combustion turbines indicated that, with modest controls on fuel sulfur content, compliance with strict regulations on particulate emissions, such as the 10 lb (4.5 kg) per hour Rule 67 of the Los Angeles Air Pollution Control District, was feasible. This paper describes the field development program to demonstrate Rule 67 compliance on an 80-MW combustion turbine for which the 10-lb/hr (4.5-kg/hr) limit is approximately 4 psm by weight. Particulate controls were implemented by installing improved-smoke combustors, and using water injection and low sulfur fuel. Meticulous sampling and analytical procedures were developed, using a specially designed and equipped environmental test laboratory trailer, to study the properties of particulate collection filters, and to improve the precision of measurements from each portion of the particulate sampling system: probe, filter, and water impingers. The test results clearly indicate that with proper attention to the details of sample system preconditioning, sample collection and analysis, the large combustion turbine can comply with the stringent 10-lb/hr (4.5-kg/hr) particulate limit of Rule 67.
Characteristic Time Correlations of Pollutant Emissions From an Annular Gas Turbine Combustor
Authors: Mellor A. M. , Washam R. M.
Published: April 2015

The continuing development of a characteristic time model for gaseous pollutant emissions from conventional gas turbine engines is described. The now engine studied here is the Pratt and Whitney JT9D, and it is shown that universal correlations can be obtained by comparison with previous results. Current limitations of the modeling approach are detailed.
Experimental Study of the Iso-Heat-Transfer-Rate Lines on the End-Wall of a Turbine Cascade
Authors: Georgiou D. P. , Godard M. , Richards B. E.
Published: April 2015

Experiments were conducted to study the distribution of the iso-heat-transfer-rate lines on the end-wall of a turbine cascade. A light piston isentropic compression tube facility was used for the experiments together with thin film heat transfer gages and a fast response analog recording system. The conditions fully represented typical Mach and Reynolds numbers, temperature ratio as well as the blade section of a modern cooled turbine. Special attention was paid to the need for good spatial resolution. The study includes the effect of the free-stream turbulence intensity level and the inlet boundary layer thickness. A subsonic compressible flow calculation method was used to predict the potential flow streamlines and a visualization method was used to study the limiting streamlines on the end wall. Furthermore, the distribution of various heat transfer parameters (e.g., qω, St) along these streamlines have undergone detailed study and some uniformity is shown to exist.
Account of Film Turbulence for Predicting Film Cooling Effectiveness in Gas Turbine Combustors
Authors: Sturgess G. J.
Published: April 2015

The paper deals with a small but important part of the overall gas turbine engine combustion system and continues earlier published work on turbulence effects in film cooling to cover the case of film turbulence. Film cooling of the gas turbine combustor liner imposes certain geometric limitations on the coolant injection device. The impact of practical film injection geometry on the cooling is one of increased rates of film decay when compared to the performance from idealized injection geometries at similar injection conditions. It is important to combustor durability and life estimation to be able to predict accurately the performance obtainable from a given practical slot. The coolant film is modeled as three distinct regions, and the effects of injection slot geometry on the development of each region are described in terms of film turbulence intensity and initial circumferential non-uniformity of the injected coolant. The concept of the well-designed slot is introduced and film effectiveness is shown to be dependent on it. Only slots which can be described as well-designed are of interest in practical equipment design. A prediction procedure is provided for well-designed slots which describes growth of the film downstream of the first of the three film regions. Comparisons of predictions with measured data are made for several very different well-designed slots over a relatively wide range of injection conditions, and good agreement is shown.
Mean Velocity and Decay Characteristics of the Near- and Far-Wake of a Compressor Rotor Blade of Moderate Loading
Authors: Ravindranath A. , Lakshminarayana B.
Published: April 2015

This paper reports the experimental study of the three-dimensional characteristics of the mean velocity in the wake of a moderately loaded compressor rotor blade. The measurements were taken with a three-sensor hot-wire probe rotating with the rotor. The wake was surveyed at several radial and axial stations. The loading was found to have substantial effect and this was reflected not only in the axial and tangential components, but also in the radial component. The radial velocities were found to be high very near the trailing-edge and this exhibits the characteristics prevalent in a trailing vortex system. The static pressures across the wake were measured using a direction insensitive spherical head static-stagnation pressure probe. The static pressure was found to be higher inside the wake. These and other measurements are reported and correlated in this paper.
Determination of Heat Transfer Coefficients Around a Blade Surface From Temperature Measurements
Authors: Mukherjee D. K.
Published: April 2015

To design cooled gas turbine blades, heat transfer coefficients around its surface are required. The calculated heat transfer data under operating conditions in the turbine are often inaccurate and require experimental verification. A method is presented here to determine the heat transfer coefficients around the blade surface and in the coolant channels. This requires measurements of the main stream and coolant temperatures together with the outer surface temperature distribution at varying mass flows. In order to conduct these tests in a gas turbine, test blades have to be specially prepared allowing the variation and measurement of coolant mass flow.
The Effect of Environmental Regulations on the General Electric Research and Development Program for Combustion Turbines Using Coal-Derived Fuels
Authors: Dibelius N. R. , Ketterer R. J. , Manning G. B.
Published: April 2015

This paper discusses the Clean Air Act, the Clean Water Act, and Noise Control Act as they affect stationary combustion turbines, including combustion turbines on coal-derived liquid and gaseous fuels. It also includes a discussion of regulations resulting from these acts insofar as they existed as of July, 1978. New regulations are being added periodically. This situation will continue and, therefore, requires that the most recent regulations be consulted for any given case. The views expressed in this paper are those of the authors and do not necessarily represent those of the Department of Energy or General Electric Company.
Water-Cooled Gas Turbine Technology Development: Fuels Flexibility
Authors: Horner M. W. , Day W. H. , Smith D. P. , Cohn A.
Published: April 2015

A continuing technology development program initiated by General Electric (GE) in the early 1960s and joined by the Electric Power Research Institute (EPRI) in 1974 is successfully resolving potential barrier problems in the development of water cooled turbines. Early work by GE Corporate Research and Development demonstrated the feasibility of closed circuit, pressurized water-cooling of stationary nozzles (vanes), and of open circuit, unpressurized water-cooling of rotating buckets (blades). A small-scale turbine was designed, fabricated, and operated at a gas temperature of 2850 F (1565 C) at 16 atm, with surface metal temperatures less than 1000 F (540 C). Early results from the EPRI sponsored Water-Cooled Gas Turbine Development Programs were presented at the 1978 Gas Turbine Conference (Report #ASME 78-GT-72). This paper reports more recent results, obtained between mid-1977 and mid-1978. Significant progress has been made in a number of areas: (a) water-cooled nozzle and bucket design and fabrication, (b) corrosion kinetics model verification and testing, (c) partially filled internal channel bucket heat transfer testing, and (d) stationary to rotating water transfer and collection testing. Results to date are encouraging with regard to the application of water-cooled turbine components to achieve improved reliability and fuels flexibility at increased turbine firing temperatures.
A Flywheel Energy Storage and Conversion System for Solar Photovoltaic Applications
Authors: Millner A. R.
Published: April 2015

A low-drag, low-power magnetic bearing and a permanent magnet brushless d-c motor-generator have been developed for a satellite flywheel. These will be combined with a terrestrial flywheel and control electronics to make up a flywheel energy storage and conversion system for use in a stand-alone solar photovoltaic residence. Technical and economic performance analyses indicate that, contrary to general thought, a flywheel system will be competitive if not superior to more conventional systems utilizing either present-day or advanced batteries. This derives from the ability of the flywheel to perform the functions of d-c to a-c inversion and optimal impedance matching between the PV arrays and the load in addition to providing energy storage. The motor-generator design will also be discussed. This paper describes the structural topology, performance data, design parameters, and test measurements of the magnetic bearing and motor-generator as well as a description of the flywheel and control electronics to be used. A preliminary discussion of the economic aspects is also included.
Field Tests of Photovoltaic Power Systems
Authors: Pope M. D. , Matlin R. W.
Published: April 2015

Field test experience gained at existing photovoltaic test sites is discussed. These sites include a 25-kW peak power system at Mead, Nebraska, a 12-kW peak array at MIT/Lincoln Laboratory, a 1.6-kW peak PV power system at the Chicago Museum of Science and Industry, and several small (∼100 watts peak) arrays located in various urban and rural sites. All of these systems were constructed for the U.S. Department of Energy by MIT/Lincoln Laboratory. Data are given on failures which have occurred in the field and on the frequency of unscheduled outages. Also, information is presented concerning the environmental extremes to which the systems have been exposed. Operating experience gained from these projects is discussed in the contexts of storage, reliability, safety and cost. Finally, some projects which are currently in the design stage are discussed. This includes a 100-kW peak power system which will serve the entire electric load for the Natural Bridges National Monument in Utah, and a 10- to 20-kW peak power system which will power a small AM radio station located at a site yet to be determined in the North Central/North East region of the United States.
Solar Photovoltaic Power for Residential Use
Authors: Hammond B.
Published: April 2015

As fossil fuel prices increase along with concern for the environment, interest in converting sunlight directly into electricity using photovoltaic solar cells continues to mount. And a common question is — when will photovoltaics be economical for residential use? Phoenix, Arizona, was chosen as the site to evaluate the economics of photovoltaic application to an energy conservative home (7109 kwh/yr). The analysis shows that a large summer load exists — which is what the utility company has been telling us for years. With such a load profile, optimum tilt angle of the solar array is 10 deg from the horizontal facing south (of interest in design of the roof structure). Peak power loads can be most economically handled with an auxiliary power source — either by power from the utility grid or from a gasoline generator. The auxiliary source would handle 18 percent of the load in June, 34 percent in July, and 24 percent in August. For the remainder of the year, power would be supplied 99 percent by the solar array. The need to handle peak loads with auxiliary power considerably reduces the solar energy storage problem in 1979. However, auxiliary power and energy storage in 1989 becomes a major part of the cost when grid power is not available. Cost per kwh for PV power in 1989 is projected at 2.8¢ when using utility grid backup and 11¢ when using generator backup.
Cast Semicrystalline Silicon for Solar Cells
Authors: Putney Z. C.
Published: April 2015

While the cost of photovoltaics has been reduced by a factor of 50 in the past six years, a major barrier for meeting future price goals is the cost of the silicon sheet material used to make solar cells. One potential solution is the casting of silicon into ingots, foregoing the costly processes now required to produce single crystal silicon. The resulting “semicrystalline” silicon is polycrystalline in nature, requires less energy to produce and may use cheaper, less refined silicon as a starting material. Solarex cells with excellent electrical characteristics have been produced from cast silicon, with conversion efficiencies as high as 16 percent. This promises to have a profound impact upon the cost and range of applications for photovoltaics.