bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of Air-Cooled Ceramic Nozzles for a Power Generating Gas Turbine
Authors: Tsuchiya Toshiaki , Furuse Yutaka , Yoshino Shin , Chikami Rintaro , Tsukagoshi Keizo , Mori Masahiko
Published: February 2015

The development of air-cooled ceramic nozzle vanes for a power generating gas turbine has been reported. To make up the limited temperature resistance of present ceramic materials, the utilization of a small amount of cooling air has been studied for the first stage nozzle vanes of a 1500°C class gas turbine.

A series of cascade tests were carried out for the designed air-cooled Si3N4 nozzle vanes under 6 ata and 1500°C conditions. It was confirmed that the maximum ceramic temperature can be maintained below 1300°C by a small amount of cooling air. In spite of the increased thermal stresses by local cooling, all Si3N4 nozzle vanes survived in the cascade tests including both steady state and transients of emergency shutdown and the possibility of air cooled ceramic nozzle was demonstrated for a 1500°C class gas turbine application.
Life Cycle Considerations in Propulsion Alternatives for Fast Vessels
Authors: Luck David L.
Published: February 2015

Fast vessels are being built and operated for a large range of passenger carrying applications. Fast cargo carrying vessels are being considered in a variety of sizes as well. A major decision in design and construction of these vessels is the propulsion system; this decision has major impacts on the operation economics as well as the operational capabilities of the vessels. Factors involved in consideration of propulsion alternatives for fast vessels are examined, with emphasis upon the total life cycle operating implications of these factors. A methodology for considering the factors is suggested, and an example is presented with results of the consideration tradeoffs.
Two-Phase Air/Oil Flow in Aero Engine Bearing Chambers: Characterization of Oil Film Flows
Authors: Glahn A. , Wittig S.
Published: February 2015

For the design of secondary air and lubrication oil systems a sufficient knowledge on two-phase flow and heat transfer phenomena under bearing chamber flow conditions is required. The characterization of oil film flows at the bearing chamber walls is one of the major tasks for a better understanding of these processes and, therefore, a necessity for improvements of the efficiency of aero engines. The present paper gives a contribution to this subject.

Utilizing a fibre-optic LDV-setup, measurements of oil film velocity profiles have been performed in our high speed bearing chamber rig simulating real engine conditions. All data have been compared with different theoretical approaches which have been derived from a force balance at a liquid film element, including geometrical conditions and temperature dependent fluid properties, and by approaches for the eddy viscosity available in the literature.
Predicted Performance of a Thrust-Enhanced SR-71 Aircraft With an External Payload
Authors: Conners Timothy R.
Published: February 2015

NASA Dryden Flight Research Center has completed a preliminary performance analysis of the SR-71 aircraft for use as a launch platform for high-speed research vehicles and for carrying captive experimental packages to high altitude and Mach number conditions. Externally mounted research platforms can significantly increase drag, limiting test time and, in extreme cases, prohibiting penetration through the high-drag, transonic flight regime.

To provide supplemental SR-71 acceleration, methods have been developed that could increase the thrust of the J58 turbojet engines. These methods include temperature and speed increases and augmentor nitrous oxide injection. The thrust-enhanced engines would allow the SR-71 aircraft to carry higher drag research platforms than it could without enhancement.

This paper presents predicted SR-71 performance with and without enhanced engines. A modified climb-dive technique is shown to reduce fuel consumption when flying through the transonic flight regime with a large external pay load. Estimates are included of the maximum platform drag profiles with which the aircraft could still complete a high-speed research mission. In this case, enhancement was found to increase the SR-71 payload drag capability by 25 percent. The thrust enhancement techniques and performance prediction methodology are described.
Influence of Vaned Diffuser on Dangerous Blade Vibration due to Blade Flow Interactions in a Centrifugal Compressor
Authors: Jin D. , Jiang Z. , Hasemann H. , Haupt U. , Rautenberg M.
Published: February 2015

Influence of diffuser vane position on dangerous blade vibration due to blade flow interactions at part load operating condition was investigated in a centrifugal compressor. By means of some measurement and analysis techniques a mechanism of interaction between blade vibration and circumferential flow condition in the impeller with vaned diffuser was determined, which is a cause of dangerous blade vibration in resonance. Experiments for the compressor with different radial diffuser positions have been performed to reduce the effect of the blade flow interaction and the dangerous blade vibration A quantitative estimate of the influence of vaneless space length between diffuser and impeller on the blade flow interaction was made. An optimal diffuser position with lower blade vibration and higher compressor characteristics was determined.
The Calibration of a Surface Mounted Aerodynamic Wall Shear Stress Gauge in Laminar Flow With a Free-Stream Pressure Gradient
Authors: Duffy James T. , Davies Mark R. D. , Hamilton Leona
Published: February 2015

A method of calibrating surface mounted thin film gauges to measure aerodynamic wall shear stress in laminar flow is presented. Hot wire measurements from the boundary-layer on a flat plate are used to find the first calibration constant and the shear stress predictions for a cylinder in cross flow are used to find the second. The cylindrical shape incorporates a favourable pressure gradient into the calibration method. Good agreement has been found between aerodynamic experimental results for the two shapes which suggests that a unique calibration exists. All experiments used Dantec 55R47 gauges operated at an overheat of 383 K above a reference temperature of 293 K. A new semi-empirical theory is used for the purpose of calibration. Input of experimental data enables the calculation of the equation parameters so that the new theory may be applied to a gauge mounted on a variety of surface profiles. Finally, calibrated gauges are used to measure the wall shear stress in laminar flow at four chordwise positions on the suction surface of a turbine blade in a two dimensional cascade.
Calculation of Turbulent Flows Through Linear Turbine Cascades With and Without Tip Clearance
Authors: Lee Hun G. , Yoo Jung Y. , Yun Jun W.
Published: February 2015

Three dimensional turbulent incompressible flows through linear cascades of turbine rotor blades with high turning angles have been analyzed numerically by using a generalized k-ε model which is a high Reynolds number form and derived by RNG (renormalized group) method to account for the variation of the rate of strain. A second order upwind scheme is used to suppress numerical diffusion in approximating the convective terms. Boundary-fitted coordinates are adopted to represent the complex blade geometry accurately. For the case without tip clearance, secondary flows and flow losses are shown to be in good agreement with previous experimental results. For the case with tip clearance, the effects of the passage vortex and tip clearance flow on the total pressure loss as well as their interactions are discussed. The flow within the tip clearance has been analyzed to illustrate the existences of the tip clearance vortex and vena contracta.
Allison 501-KB7 Industrial Gas Turbine Engine
Authors: Porter Ronald P.
Published: February 2015

The 5MW class Allison 501-KB7 gas turbine was introduced to the industrial power generation market in 1993 as a low risk upgrade of the 501-KB5 engine. The aero-derivative and industrial background of the 501-KB5 engine is discussed along with the 501-KB7 product definition and product description. The results of the development, and preproduction 501-KB7 engines are presented, including performance testing and the first year of customer operation. The extensive use of 3-D flow solvers to minimize development cost and schedule is discussed. In addition, near-term improvement plans for the 501-KB7 are outlined.
Design and Implementation of a Condition Monitoring System for Process Plants, Off-Shore Platforms, and Pipeline Compressor Stations
Authors: Boyce Meherwan P. , Lakshminarasimha Arkalgud N. , Mullin Timothy S.
Published: February 2015

This paper presents the design and features of a Condition Monitoring System (CMS) suitable for process plants, off-shore platforms, pipeline compressor stations and other facilities. The system uses advanced computer technologies such as client/server computer networks and satellite data transmission to achieve its objectives. Diagnostic windows can display condition monitoring data from any process component and on any PC connected to the network. Systems with these features are currently installed on off-shore platforms, chemical plants, and other industrial complexes. The design and features of the CMS are explained by using an off-shore oil platform that consists of sixteen machine trains. To show the system’s analysis capability, the performance analysis of a natural gas compressor which uses real-gas equations is detailed. Useful CMS design features such as exhaust gas temperature distribution analysis, turbine load distribution charts, trending and “what-if” calculation procedures are also explained.
Emission Monitoring and Testing of Combustion Processes
Authors: Wagner George H.
Published: February 2015

An outline of the federal regulations which require toting and continuous monitoring of combustion process emissions is presented. A discussion of the NOx RACT regulations and the differences between selected state agencies is presented. A brief review of the components of the proposed enhanced monitoring rule is provided.

The technology and types of continuous emission monitors (CEM) currently available for criteria and hazardous air pollutants are described. The new CEM technologies being developed for criteria and hazardous air pollutants are summarized. The factors to be considered in purchasing, installing, certifying and operating a CEM system are outlined.

The approved EPA test methods, procedures for new test method development and the new EPA stationary source and analyses database are reviewed. The use of continues monitors to develop individual combustion curves for optimization of reduced emissions is summarized. The Office of Air Quality Planning and Standard (QAQPS) network of databases is introduced.
Characteristic Time Model Correlation of NOx Emissions From Lean Premixed Combustors
Authors: Newburry Donald M. , Mellor Arthur M.
Published: February 2015

The semi–empirical characteristic time model (CTM) has been used previously to correlate and predict emissions data from conventional diffusion flame, gas turbine combustors. The form of the model equation was derived for NOx emissions from laboratory flameholders and then extended to conventional gas turbine combustors. The model relates emissions to the characteristic times of distinct combustion subprocesses, with empirically determined model constants. In this paper, a new model is developed for lean premixed (LP) NOx emissions from a perforated plate flameholder combustor burning propane fuel. Several modifications to the diffusion flame CTM were required, including a new activation energy and a more complicated dependence on combustor pressure. Appropriate model constants were determined from the data, and the correlation results are reasonable. An attempt was made to validate the new model with LP NOx data for a different but geometrically similar flameholder operating at lower pressures. The predictions are good for the low equivalence ratio data. However, a systematic error in the reported equivalence ratios may be adversely affecting the predictions of the higher equivalence ratio data through the calculated adiabatic flame temperature.
Design of Inlet Conditions for High Pressure NOx Measurements in Lean Premixed Combustors
Authors: McDonald Jon P. , Mellor Arthur M.
Published: February 2015

Semi–empirical characteristic time models (CTMs) for NOx emissions index (EI) and lean blowoff are used in the design of an inlet condition matrix for measurement of NOxEI from a lean premixed combustor. Such models relate either NOxEI or the weak extinction limit to times representing relevant physical and chemical processes in the combustor. Lean premixed (LP) natural gas/air combustion is considered for the following conditions: inlet temperature, 300–800 K; combustor pressure, 1–30 atm; and equivalence ratio, 0.5–0.7.

The NOx model is used to determine combinations of inlet conditions corresponding to greatest NOx sensitivity. A dependence of NOx emissions on pressure is included in the model. Emissions of oxides of nitrogen are found to he most sensitive to variations in inlet temperature and combustor pressure, in the 560–800 K and 20–30 atm ranges, respectively, while sensitivity to variations in equivalence ratio is substantial over the entire range considered. Thus it is found that operating conditions for high thermal efficiency in LP turbine combustors conflict with the goal of lowering NOx emissions, a result consistent with thermal NOx from conventional, diffusion flame combustors.

A lean blowoff model is used to estimate the lowest equivalence ratio at which a flame can he held, as well as to determine whether a flame can be stabilised at the operating conditions suggested by the NOx sensitivity analysis. The results suggest a nominal lower limit on equivalence ratio of 0.4, and that a flame can be held for most of the combinations of inlet conditions suggested by the NOx sensitivity analysis. Autoignition of the fuel/air mixture is also considered in relation to the location and/or design of the premixing system.

The current NOx CTM is applied to LP natural gas fired data from the literature. A model modification, thought to better represent the fluid mechanics relevant to LP NOx formation, is applied, and its implications discussed.
Design and Test of a Catalytic Combustor for a Heavy Duty Industrial Gas Turbine
Authors: Beebe K. W. , Cutrone M. B. , Matthews R. N. , Dalla Betta R. A. , Schlatter J. C. , Furuse Y. , Tsuchiya T.
Published: February 2015

The most effective technologies currently available for controlling NOx emissions from heavy duty industrial gas turbines are either diluent injection in the combustor reaction zone, or dry low NOx (DLN) combustion, coupled with selective catalytic reduction (SCR) De-NOx in the gas turbine exhaust. A competing technology with the potential for achieving comparable emissions levels at substantially lower capital investment and operating cost is catalytic combustion of lean premixed fuel and air within the gas turbine. A preliminary design of a catalytic combustion system using natural gas fuel has been prepared for the GE Model MS9001E gas turbine. A full scale test combustor has been constructed for a full pressure development test based upon this design work and was operated at the GE Power Generation Engineering Laboratory in Schenectady, New York. Discussion of the catalytic combustor design, the catalytic reactor design and laboratory development test results is presented.
Digital Control of the WR21 Intercooled Recuperated Gas Turbine
Authors: Carlson R. J. , Olson R. E.
Published: February 2015

The on-going development of a full authority digital engine control (FADEC) system for the US Navy’s Intercooled Recuperated (ICR) gas turbine requires a high level of system coordination to achieve the primary benefits of reduced specific fuel consumption and improved specific output power relative to a simple cycle engine. This paper describes the system evolution and the hardware and associated control algorithms implemented in the Advanced Development prototype ICR control system design.

The ICR control system is required to coordinate the actions of 58 actuator channels using data taken from 141 sensors. Primary control of the engine output power is provided by regulation of the fuel metering valve. Thermal management of the intercooler, recuperator, and variable area power turbine nozzle results in maximum cycle efficiency within safe operating limits.

The new electronic engine controller (EEC) is based on an open architecture Futurebus+ backplane and is fully redundant in all operationally critical control functions. The EEC also features an integrated operating panel and video display for local operation and maintenance of the control system. The graphical display and function keys provide access to control functions as well as assist maintenance activities with built-in test diagnostics to trouble shoot failed circuitry.
A Realistic Method to Establish the Required Gearbox Rating for a Gas Turbine Application
Authors: Rakhit A. K.
Published: February 2015

A reliable gearbox rating is essential for successful operation of high speed gas turbines. Presently, there is no dependable method to establish such a rating based on actual gas turbine performance under operating conditions. A great majority of manufacturers of this equipment use gas turbine output power at inlet air temperature of −20°F as the basis for this rating, while others assume an arbitrary inlet air temperature profile for turbine operation and use turbine output powers at various temperatures of the profile to derive an average rating for the gearbox. The major drawbacks of these methods are that they do not consider the effects of turbine performance characteristics and also do not include temperature profiles of actual installation sites. Thus, a vast majority of gear transmission equipment used in today’s high speed turbomachinery applications are either under- or over-rated. The procedure, as outlined in this paper, provides a reliable method to rate gearboxes for gas turbine driven equipment.
Experimental and Numerical Investigations of Aerodynamic Aspects of Hot Gas Ingestion in Rotor-Stator Systems With Superimposed Cooling Mass Flow
Authors: Bohn Dieter , Johann Erik , Krüger Uwe
Published: February 2015

Modern “High Temperature Gas Turbines” need very complex cooling configurations. Not only the turbine vanes and blades, but also the turbine discs, are cooled by air flow extracted from the compressor. Therefore, rotor-stator systems with a superimposed cooling mass flow are found in many constructions of gas turbines. The hot gas ingress into the wheelspace between stator and-rotor, taking place under special conditions, is one of the major problems in these systems.

An experimental set-up has been built to get a better knowledge of the aerodynamics of such configurations. The ingress of hot gas into the wheelspace with different sealing configurations has been considered by the measurements of surface pressure and velocities (using the LDA-measurement technique) in the shrouded rotor-stator-system. A variable mainstream flow (Ma-number up to 0.7, Re-number up to 2·106) — with and without nozzle guide vanes — has been realized, to obtain flow situations approximating those in real gas turbines.

Parallel to the experiments, the flow structure has been calculated numerically using a modern multiblock finite-volume-scheme with non-orthogonal body-fitted grids. The influence of the mainstream flow has also been taken into account. Two different versions of the k-ε-turbulence model have been used to describe the turbulent effects of the flow.

Important features of the experimental results are as follows: hot gas ingress can not only occur on the stator but also on the rotor side of the wheelspace depending on the conditions between the cooling gas and the mainstream flow. In real systems with pressure and velocity gradients in the circumferential direction, hot gas ingestion can not be completely prevented. It was only in the 2-D-axisymmetric case, without guide nozzles in the mainstream, that hot gas ingress could be suppressed completely. The numerical data has been compared to the solution obtained by similitude theory as well as to the measurements. It was found that the data correspond reasonably well. The numerical results confirm the conclusions drawn by experiment about the physical mechanism of hot gas ingress into the wheelspace.
Advanced User-Friendly Gas Turbine Performance Calculations on a Personal Computer
Authors: Kurzke Joachim
Published: February 2015

Personal Computers are nowadays very powerful. They allow us to do complete gasturbine performance calculations both for the engine design point and the partload behavior. A typical helicopter engine serves as an example for a cycle study. The simple variation of compressor pressure ratio and turbine inlet temperature, however, does not yield a realistic result. Only after including the effects of variable amounts of cooling air needed for constant metal temperature and turbine efficiency as a function of aerodynamic loading one does get results that are in line with the cycle of real engines.

Off-design performance calculations need no longer use crude simplifications for reasonable calculation times. Real component maps can be used while the matching of the cycle is done by iterative methods. Transient simulations on a 486DX machine are only a matter of a few minutes. Even the effects of inlet distortion (pressure or temperature) can be dealt with by using the parallel compressor model.

The key to userfriendliness is, to hide everything from the user that he does not need to know at the very moment. The things he needs to know, however, must be presented in clear and easily understandable expressions. Results must be shown in graphics whenever it makes sense. This is the only way to recognize quickly problem areas or to convince people, that the selected design is optimal.
A Combined Experimental/Computational Study of Flow in Turbine Blade Cooling Passage: Part II — Numerical Simulations
Authors: McGrath Diane M. , Tse David G. N.
Published: February 2015

A combined experimental/computational study has been performed for flow in rotating serpentine passages which approximate internal cooling passage for turbine blades. Experimental results are presented in the companion, Part I. The numerical simulations were performed using detailed experimental velocity profile measurements, documented in Part I, to set inflow conditions. Incompressible flow predictions with a two-layer k-ε turbulence model, which isolated the Coriolis induced secondary flow, agreed well with the measured velocities. Fluid density variations were included in compressible flow simulations which show the impact of the centrifugal buoyancy force in addition to the Coriolis force. Comparison with previously acquired heat transfer data indicates that the buoyancy force may be important in gas turbine applications.
A Study of Reynolds Stresses and Loss Generation at the Inlet to a Centrifugal Vaneless Diffuser
Authors: Pinarbasi Ali , Johnson Mark W.
Published: February 2015

Detailed flow measurements at the inlet to a centrifugal compressor vaneless diffuser are presented. The mean velocities and six component stress tensor are used to determine the turbulence production terms which lead to total pressure loss. Four regions in the flow are identified as potential sources of loss — the blade wake, the shear layers between passage wake and jet, the thickened hub boundary layer and the interaction region between the secondary flow within the blade wake and the passage vortex. The blade wakes generate most turbulence, with smaller contributions from the hub boundary layer and secondary flows, but no significant contribution is apparent from the passage wake shear layers.
Characteristics Charts for Preliminary Design and Selection of a Gas Turbine Cogeneration Plant
Authors: Sarabchi K. , Polley G. T.
Published: February 2015

The important and well-established performance criteria for assessment of a gas turbine cogeneration plant (GTCP) were examined. It was found that expressions could be derived for these criteria in terms of two key parameters: work efficiency and boiler efficiency. Three characteristics charts were then constructed. These covered gas turbine analysis, boiler analysis and GTCP performance analysis respectively. It is then demonstrated how these charts may be used as an effective tool for both performance prediction and preliminary design analysis.

Thermodynamic design of a GTCP as an integrated system is also investigated and discussed.
Field Experience Versus Theory in Turbine Engine Deterioration
Authors: Pettigrew James L.
Published: February 2015

This paper describes observations and analysis of data recorded on operating helicopter engines using advanced technology data recording systems. The US Army began the test on TS3 engines in 1986 and expanded it to their T55, T63, T700, and T703 helicopter engines in 1990. These engines have a gas generator with a free turbine for power production. A portable instrumentation system is used to do inflight helicopter engine tests and electronically record performance information.

A PC based data analysis system uses artificial intelligence to change the data into diagnostic information for the test engine’s capability to perform the missions. The data output presents this information in an easily understandable format that allows the decision maker to see differences in the condition of individual engines and rank them on their relative capability. The resulting data base clearly shows each engine’s on-condition status. Valid knowledge of each engine’s condition is very valuable as the basis for decisions that direct the limited resources to the least capable engines.

Rejection criteria for installed engine deterioration does not fully agree with observed operational behavior. Observations that are different are: (1) a deteriorated engine’s gas generator slows down when running at rated power yet no minimum speed limit exists and (2) a deteriorated engine operates at a lower SFC than a newly overhauled one yet no minimum limit exists, instead, both conditions are considered indications of better engines.
Emissions Performance of a Ramburner Sector of a Mach 5 Combined-Cycle Engine
Authors: Hautman Donald J.
Published: February 2015

A research program was conducted to acquire and analyze data from a ramburner sector operating at conditions typical for a methane-fueled ramburner in a Mach 5 Turboramjet propulsion system. A combined experimental and analytical approach was used to obtain and interpret a data base suitable for ramburner design. Non-reacting Mie scattering measurements documented the fuel-air mixing as a function of fuel-injection geometry and flow conditions. Computational fluid dynamics calculations were shown to agree reasonably well with measured jet penetrations, but overpredicted the rate of mixing. An equation to calculate the average equivalence ratio as a function of orifice diameter, orifice spacing, effective duct height, flameholder momentum flux ratio, vertical distance, and downstream distance was developed from the analyses of the non-reacting data. Concentrations of carbon dioxide, carbon monoxide, oxygen, unburned hydrocarbons, and nitric oxides were measured in a ramburner sector as a function of inlet temperature, inlet Mach number, air flow rate/area, equivalence ratio, and sampling probe location. Equations were developed that relate the combustion efficiency and the nitric oxides emission index to the reaction time and residence time.
NOx Emission Characteristics of a Catalytic Combustor Under High-Temperature Conditions
Authors: Valk Martin , Vortmeyer Nicolas , Kappler Günter
Published: February 2015

A catalytic combustor concept with short catalyst segments and a thermal reactor is investigated with regard to NOx production of this concept under high-temperature conditions. The maximum combustor exit temperature was more than 1800 K with catalyst temperatures below 1300 K. For combustion of iso-octane, NOx emissions of 4 ppm (dry, 15% O2) at a flame temperature of 1800 K were measured. No significant influence of catalyst length, reference velocity and overall residence time on NOx emissions was observed.

Additionally, the test combustor was fuelled with commercial diesel and kerosene (Jet-A). In this case, NOx emissions were noticeable higher due to fuel-bound nitrogen. The emissions measured were for diesel, 12 ppm, and for kerosene, 7 ppm, (each dry, 15% O2), again at a flame temperature of 1800 K. To evaluate the conversion ratio of fuel-bound nitrogen to NOx iso-octane was doped with various amounts of ammonia and metyhlamine. The conversion rates were 70 to 90%, with a slight tendency to lower values (50%) for nitrogen mass fractions above 0.1%.

Considering the NOx emission level of actual premix burners, the lower emission value of the presented catalytic combustor results from a perfect premixed plug-flow combustion system incorporating a catalyst herein and not from a specific advantage of the principle of catalytic combustion itself. Again similar to a premix-combustor are the NOx emission characteristics in the case of lean combustion of nitrogen bound fuels, which yield very high conversion rates.
Stator Exit Flow Fields in the Multistage Environment of an Axial Compressor
Authors: Jung M. , Eikelmann J.
Published: February 2015

Detailed measurements have been taken at the exit of the four stages of an axial compressor of industrial design for two operating points. Pneumatic probes and fast response pressure transducers have been used. Special attention is paid to the endwall flow near hub and casing and the stage-by-stage development of this region of high loss.

The steady state investigations show the leakage flow to be the dominant feature of the endwall region near the hub. This is also apparent near the casing for the unshrouded and adjustable stator blades. At the hub this flow phenomenon intensifies axially from stage-to-stage and with increased aerodynamic loading.

Variations in geometry of the radial clearance at the casing have been investigated to understand the structure and effects of the leakage flow.

Unsteady state flow measurements confirm the steady state results. Further, the endwall flow and especially the leakage vortex are detected as regions of high periodic fluctuations.
Development of a Swirl and Bluff-Body Stabilized Burner for Low-NOx, Lean-Premixed Combustion
Authors: Lovett Jeffery A. , Mick Warren J.
Published: February 2015

A burner configuration utilizing both swirl and bluff-body stabilization was developed and tested for dry low-NOx combustion of natural gas fuel. A multiple number of these burners can be used to make up a can combustor. The burner consisted of a central hub supporting an axial swirler and spoke-type fuel injectors mounted coaxially within a 100 mm diameter cylindrical tube. The swirl typically provided strong recirculation and mixing, while the flame was anchored physically to the center hub. Tests were conducted at typical heavy-duty gas turbine conditions of 620 K inlet temperature and 10 atmospheres pressure. Parametric studies were conducted with various configurations of the burner to determine the corresponding effects on fuel-air mixing, flame stability, and NOx and CO emissions. The results show that ultra-low NOx emissions can be obtained if the fuel injection is sufficiently well distributed. The compact flame produced by the highly mixed swirling flow results in very low CO emissions as well. The results suggest also that swirl-strength is reduced in an upstream swirler configuration.
Gas Turbine Performance: New Application and Test Correction Curves
Authors: Cloyd Scott T. , Harris Arthur J.
Published: February 2015

The gas turbine industry has adopted the practice of rating engine performance at ISO standard conditions; 15 degrees C, 1.033 ata, 100% methane fuel, and no inlet or exhaust system pressure losses with power output referenced to the generator terminals. (ISO, 1989) While these standards are useful in putting original equipment manufacturers’ (OEM’s) ratings on an equivalent basis it is not likely that an engine would be installed or tested under these types of conditions. To account for variations in engine operating conditions equipment manufacturers’ have utilized performance correction curves to show the influence of changing one operating parameter while holding all others constant.

The purpose of this paper is to review the correction curves that are used for initial project application studies, and the variations to the curves that occur when a unit is put into service as a result of the methods used to control engine operation. Sample corrections curves and a brief explanation of the correction curves are presented to illustrate the variations in the curves. The paper also presents a new method for illustrating the influence of fuel heating value and composition on engine performance for natural gas and oil fuel.

All data presented is for a single shaft, constant speed gas turbine. Two shaft or three shaft gas turbines will not have these correction curves.
Coherent Flame Model for Turbulent Combustion Operating With Both Premixed and Non-Premixed Flames
Authors: Kanniche M. , Zurbach S.
Published: February 2015

Comparisons arc given between four models: standard Eddy-Break-Up model (EBU), inhomogeneous Eddy-Break-Up taking into account inhomogeneous premixed flame, inhomogeneous Coherent Flame Model (CFM) taking into account inhomogeneous premixed flame and a combined Coherent Flame Model model taking into account premixed and diffusion flames. k-ε model is used for turbulence closure. The standard version of Coherent Flame Model is applied to a 2D pure premixed flame of Moreau (1977) and the results are compared to those given by Eddy-Break-Up model and to measurements of temperature and fuel mass fraction. The four models are then applied to a sector of an annular gas turbine combustion chamber similar to the one used in small gas turbine engines. The results of these models are compared and discussed.
Thermodynamic Study of Coupled Steam-Gas Turbine Plant With Steam Extraction and Injection
Authors: Qun Zheng , Shunglong Li , Yaogen Yang
Published: February 2015

A type of coupled steam–gas turbine plant is proposed here. It is composed of a regenerative extraction steam turbine and a steam injected gas turbine. Extracted steam of the regenerative extraction steam cycle is not used to heat water through the regenerative feed–water heater as in conventional plant, but injected into a gas turbine to augment the output of the gas turbine, while the exhaust gas of the gas turbine now displaces the extracted steam to heat the feed water of the steam turbine plant. The proposed repowering turbine plant has two merits: the further utilization of extraction steam and the elimination of the complicated waste heat recovery boiler of a conventional steam injected gas turbine plant, in favor of a gas–to–water heat exchanger.
A Method to Reduce the Rejection Rate for Low Performance at the Acceptance Test of PWC PT6T-6 Overhauled Power Sections
Authors: Colantuoni S. , Mainiero G. , Esposito A.
Published: February 2015

Alfa Romeo Avio is involved in the overhaul process of the Pratt & Whitney of Canada PT6T-6 for the helicopter fleet of Italian Army and civil services.

The overhauled power sections suffered from a high rejection rate (about 40%) for low performance at the acceptance test. Alfa Romeo Avio R&D investigated the causes and developed a method for the reduction of rejection rate.

A first contribution to the decision support method for the selection of the optimal engine configuration can be obtained from engine thermodynamic cycle simulation, which gives indications on the behavior of the average overhauled power section.

In this paper the authors describe also a statistical model based on a cause/effect correlation between power section assembly variables and performance parameters.

A simulation procedure, based on the statistical model, estimates the influence of the configuration assembly data on the power section performance parameters.

A careful application of both statistical and thermodynamic models gives predictions on the optimum matching of turbine nozzle size to reach the target performance at the engine acceptance test.

The method has been tested on the field during last two years and a reduction in the rejection rate at the acceptance test to 18% has been obtained.
Unsteady Numerical Simulations of Radial Temperature Profile Redistribution in a Single-Stage Turbine
Authors: Dorney Daniel J. , Schwab John R.
Published: February 2015

Experimental data taken from gas turbine combustors indicate that the flow exiting the combustor can contain both circumferential and radial temperature gradients. A significant amount of research recently has been devoted to studying turbine flows with inlet temperature gradients, but no total pressure gradients. Less attention has been given to flows containing both temperature and total pressure gradients at the inlet. The significance of the total pressure gradients is that the secondary flows and the temperature redistribution process in the vane blade row can be significantly altered. Experimental data previously obtained in a single-stage turbine with inlet total temperature and total pressure gradients indicated a redistribution of the warmer fluid to the pressure surface of the airfoils, and a severe underturning of the flow at the exit of the stage. In a concurrent numerical simulation, a steady, inviscid, three-dimensional flow analysis was able to capture the redistribution process, but not the exit flow angle distribution. In the current research program, a series of unsteady two- and three-dimensional Navier-Stokes simulations have been performed to study the redistribution of the radial temperature profile in the turbine stage. The three-dimensional analysis predicts both the temperature redistribution and the flow underturning observed in the experiments.
The Effect of Periodic Wake Passing on Film Effectiveness of Discrete Cooling Holes Around the Leading Edge of a Blunt Body
Authors: Funazaki K. , Yokota M. , Yamawaki S.
Published: February 2015

Detailed studies are conducted on film effectiveness of discrete cooling holes around the leading edge of a blunt body that is subjected to periodically incoming wakes as well as free-stream turbulence with various levels of intensity. The cooling holes have a configuration similar to that of typical turbine blades except for the spanwise inclination angle. Secondary air is heated so that the temperature difference between the mainstream and secondary air is about 20K. In this case, air density ratio of the mainstream and secondary air becomes less than unity, therefore the flow condition encountered in an actual aero-engine can not be simulated in terms of the density ratio. A spoke-wheel type wake generator is used in this study. In addition, three types of turbulence grids are used to elevate the free-stream turbulence intensity. We adopt three blowing ratios of the secondary air to the mainstream. For each of the blowing ratios, wall temperature around the surface of the test model are measured by thermocouples situated inside the model. The temperature is visualized using liquid crystals in order to obtain qualitative information of film effectiveness distribution.
Heat Transfer From Air-Cooled Contra-Rotating Discs
Authors: Chen Jian-Xin , Gan Xiaopeng , Owen J. Michael
Published: February 2015

A superposed radial outflow of air is used to cool two discs that are rotating at equal and opposite speeds at rotational Reynolds numbers up to 1.2 × 106. One disc, which is heated up to 100°C, is instrumented with thermocouples and fluxmeters; the other disc, which is unheated, is made from transparent polycarbonate to allow the measurement of velocity using an LDA system. Measured Nusselt numbers and velocities are compared with computations made using an axisymmetric elliptic solver with a low-Reynolds-number k-ε turbulence model. Over the range of flow rates and rotational speeds tested, agreement between the computations and measurements is mainly good. As suggested by the Reynolds analogy, the Nusselt numbers for contra-rotating discs increase strongly with rotational speed and weakly with flow rate; they are lower than the values obtained under equivalent conditions in a rotor-stator system.
Simulating the Multi-Stage Environment for Single-Stage Compressor Experiments
Authors: Place J. M. M. , Howard M. A. , Cumpsty N. A.
Published: February 2015

The performance of a single-stage low-speed compressor has been measured both before and after the introduction of certain features of the multi-stage flow environment. The aim is to make the single-stage rig more appropriate for developing design rules for multi-stage compressors. End-wall blockage was generated by teeth on the hub and casing upstream of the rotor. A grid fitted upstream produced free-stream turbulence at rotor inlet typical of multi-stage machines and raised stage efficiency by 1.8% at the design point. The potential field that would be generated by blade rows downstream of an embedded stage was replicated by introducing a pressure loss screen at stage exit. This reduced the stator hub corner separation and increased the rotor pressure rise at flow rates below design, changing the shape of the pressure-rise characteristic markedly. These results highlight the importance of features of the flow environment that are often omitted from single-stage experiments and offer improved understanding of stage aerodynamics.
Effects of the Inlet Endwall Boundary Layer on 3-D Flows and Loss Evolution in a Linear Turbine Cascade
Authors: Tominaga J. , Outa E. , Yamamoto Atsumasa
Published: February 2015

A three-dimensional Navier-Stokes computation was made for investigating internal flow phenomena of a linear turbine cascade, and the results were compared with the test data obtained inside the cascade passage. The present code was found to fairly well simulate the experimental data, as well as various vortices being generated in the cascade passage. In this paper, detailed mechanisms of the loss generation are discussed mainly from the computational point of view.
Numerical and Experimental Analysis of Secondary Flow in Modern State-of-the-Art Low Pressure Guide Vane Rows
Authors: Lindner Ernst
Published: February 2015

To enhance the performance of the inlet guide vane and the annular duct of a jet engine, a detailed investigation of annular cascades with two different types of turbine guide vane rows is made. The first one is a leaned guide vane with an aspect ratio of two and a half and a transition duct ahead of the vane. To avoid the losses associated to the decelerating transition duct an alternative vane is designed and investigated with the same inlet and exit conditions. In this case the chord of the vane is increased to the effect that the vane begins immediately at the enterance of the diverging annulus and so a continuously accelerated flow is achieved. To maintain a good performance for this configuration a bowed-type vane with an aspect ratio of one is designed.

The aim of the investigation is to obtain detailed informations on the secondary flow behaviour with particular regard to the development of the total pressure losses and the streamwise vorticity of the vortices inside and behind the blade rows. In the first step a three-dimensional, structured, explicit finite-volume flow-solver with a k–ε turbulence model is validated against the measurements, which were made in cross-sections behind the blades. Having proved that the numerical results are very close to the experimental ones, the secondary flow behaviour inside and behind the blade rows is analysed in the second step. By calculating the streamwise vorticity from the numerical results the formation of horse-shoe vortex, passage-vortex and the trailing edge vortex shed is investigated. The differences of the vortical motion and the formation of the total pressure losses between the two configurations of turbine guide vane rows are discussed.
Blade Pitch Influence at the Exit Flow Field of an Axial Flow Fan
Authors: Ballesteros Rafael , Blanco Eduardo , Santolaria Carlos
Published: February 2015

Variable pitch axial flow fans are widely used in industrial applications to satisfy variable operating conditions. In this work, an experimental research on a fan of this kind has been carried out. The performance curves of the fan have been obtained and the flow field has been measured at the best efficiency point of each blade pitch tested and for a lower and higher flow rate, in a fixed plane downstream the rotor with a triple hot-wire probe. The radial and circumferential distributions have been obtained, and maps of the velocity components over a blade channel are shown for each operating condition. The flow structure, including the tip and hub blockage, the blade wakes and the main flow core, is characterized.
Turbulent Flow Computations for Turbine Disk Cavity Flows
Authors: Izenson Michael G. , Kennedy Mark R. , Sirukudi Janaki R.
Published: February 2015

Computational Fluid Dynamics (CFD) plays a key role in the design of rim seals for gas turbines because of the detailed information it can provide about the complex flow in the seal region. However, the fidelity of the computed flow depends strongly on the techniques used to model turbulence. We have performed CFD calculations using several different turbulence models and compared the calculations with data from tests in a water rig at rotational Reynolds numbers of up to 6×105. Calculations were performed using the commercial CFD code, FLUENT™ 4.23 (Fluent, 1990). The turbulence models we used were a full Reynolds Stress Model (RSM) and a k-ε model. The calculated flows were compared to test data using two gross flow measurements: (1) differential pressures measured on the stator face, and (2) directions of the flow measured by dye injection on the stator face. The best agreement with test data was achieved using the RSM. We hypothesize that the RSM is superior to the k-ε turbulence model because of its ability to accurately model the highly anisotropic nature of the turbulence near the rotating turbine disk.
Calculations of Effects of Rotating Inlet Distortion on Flow Instabilities in Compression Systems
Authors: Hu Jun , Fottner Leonhard
Published: February 2015

In the present paper calculations are presented to predict the post stall transient behavior and the onset of flow instabilities in axial compression systems with rotating inlet circumferential total pressure distortion. The effects of system parameters and the compressor characteristic are taken into account, and the effects on the boundaries of rotating stall and surge are investigated. It has been found that both the inlet distortion amplitude and rotating frequency have a strong effect on the stability and post stall transient behavior, and the rotating frequency has the same strong influence on the onset of surge as the influence on the onset of rotating stall. But the resonant response frequency (i.e., the rotating frequency of inlet distortion at which the greatest loss of stability occurs) strongly depends on the frequency at which the stall cell rotates. The study of the effects of system parameters shows that the loading and the flow coefficient of the compressor at the design point have a significant effect on the onset of instability, but they have little effect on the propagation speed of rotating stall and the resonant response frequency. The Greitzer B-parameter affects the onset of rotating stall, but it has little effect on the onset of surge. Some qualitative comparisons with available experimental results are made in this paper and show that the results are reliable.