bluuebunny/crossref_metadata_2025 huggingface dataset:
Ceramic Stationary Gas Turbine Development Program: First Annual Summary
Authors: van Roode Mark , Brentnall William D. , Norton Paul F. , Boyd Gary L.
Published: February 2015

A program is being performed under the sponsorship of the United States Department of Energy, Office of Industrial Technology, to improve the performance of stationary gas turbines in cogeneration through the selective replacement of hot section components with ceramic parts. It is envisioned that the successful demonstration of ceramic gas turbine technology, and the systematic incorporation of ceramics in existing and future gas turbines will enable more efficient engine operation, resulting in significant fuel savings, increased output power, and reduced emissions.

The engine selected for the program, the Centaur 50 (formerly named Centaur ‘H’) will be retrofitted with first stage ceramic blades, first stage ceramic nozzles, and a ceramic combustor liner. The engine hot section is being redesigned to adapt the ceramic parts to the existing metallic support structure.

The work in Phase 1 of the program involved concept and preliminary engine and component design, ceramic materials selection, technical and economic evaluation, and concept assessment. A detailed work plan was developed for Phases II and III of the program. The work in Phase II addresses detailed engine and component design, and ceramic specimen and component procurement and testing. Ceramic blades, nozzles, and combustor liners will be tested in subscale rigs and in a gasifier rig which is a modified Centaur 50 engine. The Phase II effort also involves long term testing of ceramics, development of appropriate nondestructive technologies for part evaluation, and component life prediction. Phase III of the program focuses on a 4,000 hour engine test at a cogeneration site.

This paper summarizes the progress on the program through the end of 1993.
Theoretical and Experimental Investigation of Circumferential Grooved Casing/Hub Treatment
Authors: Du Zhaohui , Liu Zhiwei
Published: February 2015

In this paper the 3-dimensional viscous numerical calculation is applied to explain the mechanism of extending stability of circumferential grooved casing and hub treatments. A new index which can quantitatively evaluate the ability to extend stability of circumferential grooved casing and hub treatments is proposed with flux of gas through the treatment grooves. The influences of the geometric parameters on improving stall margin are discussed. The conclusions are the same as those of experiments.

A circumferential grooved hub treatment is designed and tested beneath the stator blade row in a single stage axial flow compressor. The upstream and downstream 3-dimension flowfields are measured carefully in optimum operation condition and near stall margin condition by a combined three-hole probe and a mirco-five-hole probe which has 1.5mm diameter. It is shown that stall margin can be improved not only for the single stage compressor, but also for the rotor. Through a lot of experimental investigations and theoretical analyses, the mechanism of extending stability of circumferential grooved casing and hub treatments are systematic and comprehensive explained.
Operational Experience and Energy-Saving Improvements on Offshore Gas Turbine Driven Compressor Trains
Authors: Lynghjem Arne , Heltne Terje
Published: February 2015

The efficient operation of offshore gas turbine driven compressor trains is becoming more and more important. With the introduction of the CO2 tax on fuelgas in Norway, the operating costs have dramatically changed. It is now necessary to focus on energy-saving operation and maintenance in order to include the influence of CO2 taxation. In the Statfjord and Gullfaks fields, the LM2500 high efficiency aeroderivative gasturbines have been in operation for several years, and the operational experience is presented and discussed here with regard to efficiency and reliability. An optimised gas turbine maintenance program has been introduced in order to obtain energy-saving and cost reduction. The problems relating to the gas compression trains are discussed with regard to energy conservation and reliability. Off design operating conditions on compressors have caused problems, both with regard to power losses and machinery safeguard control systems. Energy-saving improvements have been implemented on the compressors and the system they are working in. The reliable operation of the compressors can be put at risk by the shaft-sealing system. It is of vital importance to ensure correct operation of seal system in order to obtain safe and economical operation. Improvements to shaft-sealing systems are discussed.
Effects of Leading-Edge Roughness on Fluid Flow and Heat Transfer in the Transitional Boundary Layer Over a Flat Plate
Authors: Pinson Mark , Wang Ting
Published: February 2015

An experimental study was undertaken to gain insight into the physical mechanisms that affect the laminar-turbulent transition process downstream of the leading-edge roughness condition. Three sizes of sandpaper strips were chosen to simulate the randomly distributed roughness located near the leading edge of a turbine blade, and three sizes of cylinders were chosen to simulate the relatively isolated peak nature of the roughness structure. The roughness Reynolds numbers tested covered a wide range, from 2 to 2840. The roughness sizes were selected based on the measured roughness characteristics of used gas turbine blades. The results indicated that at low free-stream velocities (5 m/s), the maximum roughness height was the primary contributor to deviations from the undisturbed case. At higher free-stream velocities (5–7 m/s), three of the rough leading-edge conditions exhibited a dual-slope region between the laminar and turbulent Stanton number versus Reynolds number correlations. Analysis of the boundary layer indicated that the first segment of the dual-slope was laminar, but the wall heat transfer significantly deviates from the laminar correlation. The second segment was transitional. The dual-slope behavior and the waviness of the Stanton number distribution at higher free-stream velocities observed downstream of the rough leading-edge conditions are believed to have been caused by nonlinear amplification introduced by the finite disturbances at the leading edge.
Turbine Rotor Generated Forcing Functions for Flow Induced Vibrations
Authors: Weaver Matthew M. , Fleeter Stanford
Published: February 2015

A series of experiments are performed to investigate the effect of steady loading on the unsteady aerodynamic gust forcing functions generated by turbine rotor blade rows and the validity of the vortical and potential gust splitting techniques. Both the downstream vortical-potential gusts and, for the first time, the upstream generated potential gust are considered. Note that these upstream gusts are in fact the potential field of the rotor and not the nozzle wakes. This is accomplished by measuring the downstream and upstream unsteady forcing functions generated by the first stage rotor of the low speed research turbine over a range of steady loading levels. These forcing functions are then split into vortical and potential gusts utilizing both the V-Method using only velocity data and the P-Method which also incorporates unsteady static pressure data. The results clearly show an increase in potential effects for the downstream gust forcing functions with increased blade loading. The rotor blade gusts upstream of the first rotor are theoretically purely potential gusts since no vorticity can be conducted upstream. These potential disturbances do not appear to be a function of the blade loading. The results of the linear theory splitting show that both splitting methods have discrepancies in their recombined forcing functions. The V-Method either under or over estimates the unsteady static pressure and has trouble duplicating the phase. The P-Method tends to skew the recombined velocity in the lift force direction. The upstream potential gusts posed a particular problem for the splitting, with neither method able to fully reconcile the measured pressure and velocity perturbations.
On the Transport of Spatial Fluctuation Correlations in a Turbine Stator
Authors: Perrin G. , Leboeuf F.
Published: February 2015

When averaging the Navier-Stokes or Euler equations in the circumferential direction of a turbomachine, some so-called “spatial fluctuation terms” appear in the averaged conservation equations. We give the transport equations for these kinematic spatial fluctuation correlations. We evaluate the various terms in these equations, using the results of a three-dimensional Navier-Stokes computation. The test case is a highly loaded subsonic turbine stator.

We discuss the magnitudes of the various terms. It is shown that blade force terms and diffusion terms have dominant effects, as respect to the production by the averaged field and the shear stress terms. The dissipation of the fluctuation kinetic energy occurs mainly in the passage vortex area, and in the blade wake.
Relationship Between Erosion and Characteristics of Deposits in Gas Turbines Burning Heavy High Sulfur Fuel Oil
Authors: Wong-Moreno Adriana , Sánchez-Villalvazo Alicia
Published: February 2015

Heavy, brittle and very hard deposits built on the first row vanes have caused severe erosion of all the first stage blades of a gas turbine during operation with washed and treated heavy residual fuel oil. The high sulphur (3.5–4.0 wt.%) fuel oil consumed by the turbine is also high in vanadium (280–290 ppm) and asphaltene content.

In the present work the results of an investigation on the physical and chemical characteristics of erosive ash deposits as a function of operation conditions and fuel oil characteristics are presented. The structure and chemistry of deposits were studied by chemical analysis, x-ray diffraction, microanalysis and scanning electron microscopy. It was confirmed that deposit friability is enhanced by its MgSO4 content and that its hardness depends on the amount of MgO present. It was also found a clear correlation between the gas inlet temperature and the size of the ash particles deposited, and on the degree of compactness and hardness of the deposit. The role of the unburned particles, unavoidable in the combustion of heavy fuel oils, is discussed in relation to their influence on the effectiveness of the magnesium inhibitor.
The Effect of Adding Roughness and Thickness to a Transonic Axial Compressor Rotor
Authors: Suder Kenneth L. , Chima Rodrick V. , Strazisar Anthony J. , Roberts William B.
Published: February 2015

The performance deterioration of a high speed axial compressor rotor due to surface roughness and airfoil thickness variations is reported. A 0.025 mm (0.001 in.) thick rough coating with a surface finish of 2.54–3.18 RMS μm (100–125 RMS microinches) is applied to the pressure and suction surface of the rotor blades. Coating both surfaces increases the leading edge thickness by 10% at the hub and 20% at the tip. Application of this coating results in a loss in efficiency of 6 points and a 9% reduction in the pressure ratio across the rotor at an operating condition near the design point. To separate the effects of thickness and roughness, a smooth coating of equal thickness is also applied to the blade. The smooth coating surface finish is 0.254–0.508 RMS μm (10–20 RMS microinches), compared to the bare metal blade surface finish of 0.508 RMS μm (20 RMS microinches). The smooth coating results in approximately half of the performance deterioration found from the rough coating. Both coatings are then applied to different portions of the blade surface to determine which portions of the airfoil are most sensitive to thickness/roughness variations.

Aerodynamic performance measurements are presented for a number of coating configurations at 60%, 80%, and 100% of design speed. The results indicate that thickness/roughness over the first 10% of blade chord accounts for virtually all of the observed performance degradation for the smooth coating, compared to about 70% of the observed performance degradation for the rough coating.

The performance deterioration is investigated in more detail at design speed using laser anemometer measurements as well as predictions generated by a quasi-3D Navier-Stokes flow solver which includes a surface roughness model. Measurements and analysis are performed on the baseline blade and the full-coverage smooth and rough coatings. The results indicate that coating the blade causes a thickening of the blade boundary layers. The interaction between the rotor passage shock and the thickened suction surface boundary layer then results in an increase in blockage which reduces the diffusion level in the rear half of the blade passage, thus reducing the aerodynamic performance of the rotor.
Models for the Prediction of Transients in Closed Regenerative Gas-Turbine Cycles With Centrifugal Impellers
Authors: Korakianitis T. , Vlachopoulos N. E. , Zou D.
Published: February 2015

This paper presents transient-flow component models for the prediction of the transient response of gas turbine cycles. The application is to predict the transient response of a small solar-powered regenerative gas-turbine engine with centrifugal impellers. The component sizes are similar to those under consideration for the solar-powered Space Station, but the models can easily be generalized for other applications with axial or mixed-flow turbomachinery. New component models for the prediction of the propagation of arbitrary transients in centrifugal impellers are developed. These are coupled with component models for the heat exchangers, receiver and radiator. The models are based on transient applications of the principles of conservation of mass, energy, and momentum. System transients driven by sinusoidal and double-step inputs in receiver salt temperature are presented and discussed. The new turbomachinery models and their coupling to the heat-exchanger models simulates disturbance-propagation in the components both upstream and downstream from the point of generation. This permitted the study of the physical mechanisms of generation and propagation of higher-frequency contents in the response of the cycle.
Direct Use of Unsteady Aerodynamic Pressures in the Flutter Analysis of Mistuned Blades
Authors: Srinivasan A. V. , Tavares G. G.
Published: February 2015

An aeroelastic stability analysis of a cascade of engine blades coupled only through aerodynamica is developed. The unique feature of the analysis is the direct use of unsteady aerodynamic pressures, rather than lifts and moments, in calculating the susceptibility of a cascade to flutter. The approach developed here is realistic and relevant for analysis of low aspect ratio blades. However, in the calculations presented in this paper, the surface is assumed to be divided into equal elemental areas. The formulation leads to a complex eigenvalue problem, the solution of which determines the susceptibility of the cascade to flutter. The eigenvalues of an assembly of alternately mistuned blades, operating at high reduced frequencies, appear to be very sensitive to the level of mistuned frequencies. The locus of eigenvalues shows a strong tendency to split even for very small percentage differences between the frequencies of the two sets of blades. Further, blades with identical frequencies, but alternately mistuned mode shapes, operating at high reduced frequencies show a tendency towards instability.
Rotor Repairs
Authors: van Gestel Ron , Mattheij Sjef
Published: February 2015

Often, turbine and generator rotors are produced from a single forging or from two forged bearing ends with a stack of discs in between. As with many other components in rotary equipment these precision machined forgings can be damaged or worm during operation. Due to the sensitivity of the material to any kind of heat treatment, including welding, repair of this damage presents a challenge for repair engineers.

This paper will give a general overview of repair. Repair may include welding, heat treatment, plasma spraying, shaft straightening, stress relieving, etc. Some recent repairs will be discussed.
Design Characteristics and Operating Experience of Nuovo Pignone PGT 16 Gas Turbine
Authors: Sabella D. , Sferruzza S.
Published: February 2015

The paper outlines the main features of the PGT 16 gas turbine with its auxiliaries and summarizes the experiences made in the field with the first seven units put in service starting in the first quarter of 1992.

The PGT 16 gas turbine utilizes an aero-derivative gas generator, the LM 1600 manufactured by General Electric, coupled with a heavy-duty power turbine designed and manufactured by Nuovo Pignone. This power turbine is the same utilized for the 14000 HP heavy-duty gas turbine Nuovo Pignone PGT 10. The nominal shaft power is 18600 HP, with 36.4% efficiency.

The design shaft speed of 7900 rpm makes this unit particularly suitable for mechanical drive applications, matching the typical speed range of centrifugal compressors in its power range. At the same time the high efficiency makes this unit attractive for both simple cycle and combined cycle power generation plants.

The package design privileges maintenance requirements to minimize the downtime and to provide the highest possible degree of availability.

The first 5 units in service have been installed along the Transcanada Pipeline and drive pipeline booster ‘compressors, PCL and BCL type: the other two units are in operation in a cogeneration facility in a paper-mill. At October ’93 the seven units have totalled 60,000 fired hours and the fleet leader 13,000 fired hours approximately.
Gas Turbine Acoustic Enclosure Design by the Statistical Energy Analysis Method
Authors: Lu L. K. H. , Mitchell M.
Published: February 2015

Acoustic enclosure design is a complex problem that involves the interaction of multiple components. Yet the present conventional approach uses two-dimensional closed form solution to evaluate transmission loss of acoustic wall. In this paper, Statistical Energy Analysis (SEA) was first studied for simple cases of radiation efficiency, transmission loss, and flanking path calculations. The effectiveness of the SEA method for complex system was then demonstrated through a practical design application to gas turbine enclosure. It was found that SEA was a useful tool for gas turbine acoustic enclosure design.
Modeling of Boundary Layer Transition in Turbulent Flows by Linear Combination Integral Method
Authors: Gostelow J. P. , Hong G. , Walker G. J. , Dey J.
Published: February 2015

Transitional boundary layer parameters in zero and variable pressure gradient flows, typical of turbomachinery applications, are predicted using an integral method of the linear combination type. The code used is that of Dey and Narasimha and the turbulent layer is calculated by a lag-entrainment method. The predictions of test data represent an improvement upon earlier methods; although reasonable agreement is obtained for these low Reynolds number test cases further refinement of predictive correlations to account for free-stream turbulence effects on laminar boundary layers and transition inception is indicated.

The transitional parameters are found to be particularly sensitive to the initial conditions selected for the turbulent layer. Techniques are identified for overcoming this sensitivity and for adequately representing the transition region. Free-stream turbulence effects are quite strong, particularly on the velocity profile of the laminar layer. Modifications to laminar methods are advocated to account for the strong effects on the velocity profile and the early formation of turbulent spots.
A 26 MW Gas Turbine Applied to a Three Casing Storage/Pipeline Compressor String
Authors: Colwell Paul J.
Published: February 2015

Union Gas, like many of the natural gas companies across Canada, has seen significant expansion of it’s compression and pipeline facilities in the past few years. Much of this expansion has been dedicated to the gas storage and transmission needs of the Eastern Canadian and American markets. With the capital costs of these facilities continually on the rise it is critical to ensure that each facility will yield maximum utility to the system for the proposed investment.

Union Gas has a unique position within the Canadian gas industry as not only a major distribution company but also an operator of over 120 BCF of underground gas storage and a transmission pipeline system which is an integral part of the transCanadian gas supply infrastructure. Union’s transmission and storage system provides a vital link between the TransCanada PipeLines transmission system running through Northern Ontario and Central Michigan and several delivery points into the Northeastern United States and Eastern Canada. The diverse nature of Union’s operating facilities dictate a system with two distinctively different modes of compression during the winter operating season. These modes being storage withdrawal, which is typically a high head low flow operation and pipeline transmission which is a low head high flow operation. Each of these modes require specific compressor performance designs which do not typically display the flexibility to be utilized in either mode.

With system demands consistently on the increase it can be very difficult to maintain adequate backup in the event of a compressor plant outage; this is particularly evident’ when considering the different operating requirements at various locations in the system. In an effort to maximize the operational flexibility of a new facility, Union Gas has implemented a new design consisting of a triple case compressor train driven off a single engine gas turbine package. With the external unit piping configured for both series and parallel operation this new design can effectively duplicate all possible modes of operation in Union’s present operating system, for both storage withdrawal and pipeline transmission.

This paper will discuss the extent of operational flexibility this system can offer and the various design concerns associated with this type of compression plant facility.
Design of a State Space Controller for an Intercooled, Regenerated (ICR) Gas Turbine Engine
Authors: Prigge Karl F. , Watts Jerry W. , Dwan Terrence E.
Published: February 2015

A multi-input, multi-output (MIMO) controller for an advanced gas turbine has been developed and tested using a computer simulation. The engine modeled is a two-and-one half spool gas turbine with both an intercooler and a regenerator. In addition, variable stator vanes are present in the free-power turbine. This advanced engine is proposed for future naval propulsion for both mechanical drive ships and electrical drive ships. The designed controller controls free-power turbine speed and turbine inlet temperature using fuel flow and angle of the stator vanes. The controller will also have four modes of operation to deal with over temperature and over speed conditions. An eight state reduced order controller was used with pole placement and LQR to arrive at control gains. Both these methods required considerable insight into the problem. This insight was provided by previous experience with controller design for a less complicated engine, and also by use of a polyhedral search model of the gas turbine engine. The difficulty with a MIMO controller was that both inputs affect both of the control variables. The classical resolution of this problem is to have one input control one variable at a fast time constant and the other input control the other variable at a slow time constant. The “optimal” resolution of this problem is analyzed using the transient curves and basic control theory.
High Speed Milling of Turbine Blades
Authors: Schulz Herbert , Hock Stefan
Published: February 2015

The efficiency of steam- and gasturbines is mainly influenced by the geometry and the surface roughness of the turbine blades. Therefore the profile contour of the blades must be machined as accurate as possible. High speed cutting (hsc) offers a lot of advantages for surface finishing of turbine blades. The paper describes the influence of different cutting parameters as well as the importance of tool geometry for the surface quality achievable by high speed milling. Specific requirements for machine tools for high speed milling will be discussed.
Assessment of Power Generation Concepts on Oil Platforms in Conjunction With CO2 Removal
Authors: Bjerve Yngvil , Bolland Olav
Published: February 2015

The introduction in 1991 of a CO2-tax on offshore combustion of natural gas has lead to an increased interest in both energy conservation and the possibility of separating CO2 from gas turbine exhaust. In this paper, several power generation concepts based on natural gas combustion by existing technology have been assessed in order to find the concept best suited for CO2 removal. An important factor when developing processes for offshore implementation is that space and weight are very expensive offshore. The suggested process consists of a power generation unit, a CO2 absorption unit and a CO2 compression unit. The power generation concepts have been evaluated in order to find the concept which combines the factors low exhaust gas flow, high CO2 concentration, high efficiency and low weight in the best possible manner. The result of the assessment is that a combined cycle with recycling of 40% of the exhaust volume back to the compressor inlet, is best suited for CO2 removal among the options studied.
Experimental Validation of Turbine Blade Dynamics Design Methodology
Authors: Salvano S. , Schips C.
Published: February 2015

This paper deals with the most relevant experimental results regarding turbine blade dynamics acquired from several designs: from both military and commercial aeroengines to industrial gas turbines. On this basis, a common design methodology has been validated for the different applications.

Campbell and Goodman diagrams are the basic tools used to verify resonances and vibratory stress margins. In addition to that, a frequency response type of calculation was developed, nevertheless facing the problem of exciting force and damping assumption. High emphasis is given to evaluating the damping characteristics of the blade: in-house programs have been validated through dedicated tests of shroud optimization and platform damper design.

Experimental tests are in any case necessary when a new blade is designed; however the confidence in the design tools gained by their experimental validation is likely to give better chances to have a good new design, shortening the relative development phase.
Hybrid Bearing Technology for Advanced Turbomachinery: Rolling Contact Fatigue Testing
Authors: Dill James F.
Published: February 2015

The purpose of this paper is to describe the basic structure and results to date of a major ARPA funded effort to provide a tribological performance database on ceramic bearing materials and their interaction with standard bearing steels. Program efforts include studies of material physical properties, machining characteristics and tribological performance. The majority of the testing completed to date focuses on rolling contact fatigue testing of the ceramic materials including efforts to arrive a optimum approaches to evaluating ceramic / steel hybrid combinations in rolling contact fatigue.
Pre-Stall Behavior of Several High-Speed Compressors
Authors: Tryfonidis M. , Etchevers O. , Paduano J. D. , Epstein A. H. , Hendricks G. J.
Published: February 2015

High speed compressor data immediately prior to rotating stall inception are analyzed and compared to stability theory. New techniques for the detection of small amplitude rotating waves in the presence of noise are detailed and experimental and signal processing pitfalls discussed. In all nine compressors examined, rotating stall precedes surge. Prior to rotating stall inception, all the machines support small-amplitude (<1% of fully developed stall) waves travelling about the circumference. Travelling wave strength and structure are shown to be a strong function of corrected speed. At low speeds, a −0.5 times shaft speed wave is present for hundreds of rotor revolutions prior to stall initiation. At 100% speed, a shaft speed rotating wave dominates, growing as stall initiation is approached (fully developed rotating stall occurs at about 1/2 of shaft speed). A new, 2-D, compressible hydrodynamic stability analysis is applied to the geometry of two of the compressors and gives results in agreement with data. The calculations show that, at low corrected speeds, these compressors behave predominantly as incompressible machines. The wave which first goes unstable is the 1/2 shaft frequency mode predicted by the incompressible Moore-Greitzer analysis and previously observed in low speed compressors. Compressibility becomes important at high corrected speeds and adds axial structure to the rotating waves. At 100% corrected speed, it is one of these hitherto unrecognized compressible modes which goes unstable first. The rotating frequency of this mode is constant and predicted to be approximately coincident with shaft speed at design. Thus, it is susceptible to excitation by geometric nonuniformities in the compressor. This new understanding of compressor dynamics is used to introduce the concept of travelling wave energy as a measure of compressor stability. Such a wave energy-based scheme is shown to consistently give an indication of low stability for significant periods (100–200 rotor revolutions) before stall initiation, even at 100% corrected speed.
Thermal Stability and Heat Transfer Characteristics of Methane and Natural Gas Fuels
Authors: Chin Douglas , Hermanson James C. , Spadaccini Louis J.
Published: February 2015

The thermal decomposition and heat transfer characteristics of gaseous, high-purity methane, several methane-hydrocarbon mixtures and a typical natural gas fuel were evaluated using an electrically heated, stainless-steel tube test apparatus. Of several candidate heat transfer correlations, the Dittus-Boelter heat transfer correlation provided the best fit of the methane heat transfer data over the range of Reynolds numbers 10,000 to 215,000. The thermal stability (i.e. deposit formation) characteristics of the methane-hydrocarbon mixtures and the natural gas fuel were established and compared with the deposition characteristics of high-purity methane. Testing was conducted at wall temperatures up to 900 K (fuel temperatures to 835 K) for durations of up to 60 hours. Measurements of deposit mass indicated that there was essentially no deposit buildup for wall temperatures below 650 K. Deposit began to form at wall temperatures between 650 K and 775 K. Above 775 K, there was a rapid monotonic increase in deposition. The data suggest that the use of high-purity methane instead of natural gas at temperatures above 775 K could reduce the deposit thickness under similar operating conditions by as much as a factor of three, or permit operation at higher temperatures.
Numerical Analysis of Nozzle and Afterbody Flow of Hypersonic Transport Systems
Authors: Esch Thomas , Glehrl Marcus
Published: February 2015

Using an implicit Finite-Volume Navier-Stokes code the flow field in a Single Expansion Ramp Nozzle (SERN) for a hypersonic aircraft is studied. Comparisons between experimental data and CFD calculations for certain components of the integrated exhaust system (cold 2D nozzle flow, high temperature reacting 3D combustion chamber flow and 2D nozzle flow with external flow) are presented.

To show the sensitivity of the considered components to off-design operating conditions, comprehensive numerical studies have been carried out.

For the determination of nozzle performance a detailed 20 analysis from transonic to hypersonic flight Mach numbers has been performed. A direct optimization method has been used to investigate the influence of the lower nozzle flap shape on the thrust vector.
Technology Demonstration Nozzle for Mach 7 Turboramjets
Authors: Pirker K. , Knott U.
Published: February 2015

Under the German Hypersonic Technology Program, future-oriented designs and technologies for reusable space vehicles, such as SÄNGER, are being developed. Pioneering the way in a new field of technology, MTU constructed and tested, with success from the very beginning, an actively cooled, asymmetric rectangular nozzle (SERN - single expansion ramp nozzle) of advanced design, characterized by the following innovative features:

- rectangular, flap-controlled variable flow cross section;

- liquid-hydrogen-cooled structures;

- high-temperature-resistant sealing system for variable nozzle flaps; and

- uncooled expansion ramp in carbon/carbon composite with anti-oxidation coating.

Development of the nozzle called for the mastery of new manufacturing techniques; proof of concept was provided in the successful performance of initial tests of 300 seconds duration.
Processing of Continuous Fiber Reinforced SI3N4 Matrix Composites for Gas Turbine Engine Components
Authors: Iwata Misao , Isoda Takeshi , Itoh Takuji
Published: February 2015

The purpose of this study is to significantly improve the fracture toughness of ceramic materials by incorporating continuous fiber reinforcement, and demonstrate the ability to fabricate gas turbine engine components, such as shrouds and liners.

SI3N4, matrix composites were prepared by stacking precursor tapes consisting of carbon fibers coated with a slurry of SI3N4, Al2O3, Y2O3, perhydropolysilazane and xylene.

After sintering the continuous fiber reinforced SI3N4-matrix composites had a 4 to 5 times higher fracture toughness of 28.1 MPam1 /2 and a 250 to 300 times higher work-of-fracture of 2.5 × 104 j/m2, than typical monolithic SI3N4 ceramics.

In the meantime, the preform tape wound at a helical-angle of 45° was used for forming green bodies of the gas turbine engine components by means of the deep drawing method. In order to sinter these preforms, the preceramic polymer infiltration method (P.C.P.I. method) and pseudo hot isostatic press method were applied for fabricating the shroud and liners, respectively.
Combustion Turbine Triple Fuel System for Teesside, England Project
Authors: Hoffman Larry E. , Harrison Chris J. , Shields James J.
Published: February 2015

This paper presents the unique design and operational aspects of the triple fuel system developed and implemented for the Westinghouse/Mitsubishi Heavy Industries 701-DA combustion turbine. Eight of these units have recently been put into service at the Enron cogeneration project in Teesside, England. This facility is currently the world’s largest gas fired combined cycle cogeneration project. The triple fuel system was designed to meet the customer’s unique operational requirements. A variable composition natural gas in combination with gaseous propane, and liquid naphtha presented considerable fuel and control system design challenges.
Evaporation Characteristics of Spray in a Lean Premixed-Prevaporization Combustor for a 100 KW Automotive Ceramic Gas Turbine
Authors: Ohkubo Youichlrou , Idota Yoshinorl , Nomura Yoshihiro
Published: February 2015

Spray characteristics of liquid fuel air-assisted atomizers developed for a lean premixed-prevaporization combustor were evaluated under two kinds of conditions: in still air under non-evaporation conditions at atmospheric pressure and in a prevaporization-premixing tube under evaporation conditions with a running gas turbine. The non-evaporated mass fraction of fuel spray was measured using a phase Doppler particle analyzer in the prevaporization-premixing tube, in which the inlet temperature ranged from 873K to 1173K. The evaporation of the fuel spray in the tube is mainly controlled by its atomization and distribution. The NOx emission characteristics measured with a combustor test rig were evaluated with three-dimensional numerical simulations. A low non-evaporated mass fraction of less than 10% was effective in reducing the exhausted NOx from lean premixed-prevaporization combustion to about 1/6 times smaller than that from lean diffusion (spray) combustion. The flow patterns in the combustor are established by a swirl chamber in fuel-air preparation tube, and affect the flame stabilization of lean combustion.
Pattern Factor Reduction in a Reverse Flow Gas Turbine Combustor Using Angled Dilution Jets
Authors: Crocker D. Scott , Smith Clifford E. , Myers Geoff D.
Published: February 2015

An advanced method for dilution zone mixing in reverse flow gas turbine combustors was experimentally investigated. To enhance circumferential mixing, dilution jets were injected with a high circumferential (swirl) velocity component. The jets on the outer liner were angled in one direction while the jets on the inner liner were angled in the opposite direction.

To demonstrate reduced pattern factor, AlliedSignal Engines’ F109 combustor was tested at sea level takeoff conditions. For the baseline (conventional) configuration, the experimental results showed that large scale circumferential temperature non-uniformities at the turbine inlet were caused primarily by fuel flow variations from nozzle to nozzle. These temperature variations were significantly reduced by angled dilution jets. A pattern factor of 0.102 was achieved compared to the best case pattern factor of 0.163 for the baseline configuration. The only combustor modification was the dilution hole configuration. The radial average temperature profile produced by angled dilution jets was very similar to the profile produced by the baseline configuration.
The Effect of the Pressure Distribution in a Three-Dimensional Flow Field of a Cascade on the Type of Curved Blade
Authors: Wang Zhongqi , Su Jiexian , Zhong Jingjun
Published: February 2015

The effect of the pressure distribution in a three-dimensional flow field of a cascade on the type of curved blade is discussed in this paper through analysing the experimental results and numerical calculative results. Using curved blades, we can obtain “C” type pressure distribution along the blade height in the passage. For the expansion cascade, energy loss in the cascade can be reduced if positive curved blades are used. For guide vanes and compressor cascades, the choice of using positive curved blades or negative curved blades relies on the pressure gradient on the blade midspan suction surface along the direction of flow and whether there exists a separation of the boundary layer there. However, all of these need further studies and discussions.
Effects of Combustor Aerodynamics on the Ignition of Solid Fuel
Authors: Yang Jing-Tang , Wu Cliff Yuh-Yih , Yang Hung-Tsann
Published: February 2015

A traditional and a modified backward-facing steps were designed to investigate the effects of flow characteristics on the ignition of the solid fuel slab in a sudden expansion combustor. Experiments were conducted separately in the cold flow for the turbulent flow field and in a hot oxidizing flow stream for the ignition tests. The velocity flowfield was measured by a laser-Doppler anemometer (LDA) and the ignition process was observed by a high-speed video camera. The inlet flow velocity for the cold flowfield measurements was kept at 15 m/s, but was varied for the ignition tests, whereas the step height of the backstep was 29 mm. The results show that the higher turbulence intensity in the boundary layer near the separated point did not always cause a higher turbulence intensity in the recirculation zone. However, the combustor with a modified backstep generated greater reverse flow rate, turbulence intensity and Reynolds stress in the recirculation zone. As a result, the ignition delay of solid fuel in the modified combustor was significantly reduced as compared with the traditional combustor.
A Methodology to Assess Design Uncertainty in Selecting Affordable Gas Turbine Technology
Authors: Younghans James L. , Johnson James E. , Csonka Steven J.
Published: February 2015

A methodology is discussed which allows quantification of uncertainty in the gas turbine design and analysis process. The methodology can be employed to rank order the cost effectiveness of advanced component technologies or alternatively can be used to determine probable performance (SFC and Thrust) of engines which have component performance uncertainties. Execution of the methodology requires a desk top computer and commercially available software.
Application of Spslife to Preliminary Design Evaluation and Life Assessment of CSGT Components
Authors: Saith Arun , Norton Paul F. , Parthasarathy Vijay M.
Published: February 2015

The Ceramic Stationary Gas Turbine (CSGT) Program has utilized the SPSLIFE computer code to evaluate the preliminary design of ceramic components. The CSGT program is being performed under the sponsorship of the United States Department of Energy, Office of Industrial Technology, to improve the performance of stationary gas turbines in cogeneration through the selective replacement of hot section components with ceramic parts. Preliminary design evaluation and life assessment results are presented here for the following components: (1) Stage 1 Turbine Blade, (2) Stage 1 Turbine Nozzle, and (3) Combustor Inner Liner. From the results of the analysis, recommendations are made for improving the life and reliability of the components. All designs were developed in Phase I (preliminary design) of the CSGT program and will be optimized in Phase II (detail design) of the program.
An Assessment of the Thermodynamic Performance of Mixed Gas-Steam Cycles: Part B — Water-Injected and Hat Cycles
Authors: Chiesa Paolo , Lozza Giovanni , Macchi Ennio , Consonni Stefano
Published: February 2015

Part B of this paper focuses on intercooled recuperated cycles where water is injected to improve both efficiency and power output. This concept is investigated for two basic cycle configurations: a Recuperated Water Injected (RWI) cycle, where water is simply injected downstream the HP compressor, and a Humid Air Turbine (HAT) cycle, where air/water mixing is accomplished in a counter-current heat/mass transfer column called “saturator”.

For both configurations we discuss the selection and the optimization of the main cycle parameters, and track the variations of efficiency and specific work with overall gas turbine pressure ratio and turbine inlet temperature (TIT). TIT can vary to take advantage of lower gas turbine coolant temperatures, but only within the capabilities of current technology. For HAT cycles we also address the modelization of the saturator and the sensitivity to the most crucial characteristics of novel components (temperature differences and pressure drops in heat/mass transfer equipment). The efficiency penalties associated to each process are evaluated by a second-law analysis which also includes the cycles considered in Part A.

For any given TIT in the range considered (1250 to 1500°C), the more reversible air/water mixing mechanism realized in the saturator allows HAT cycles to achieve efficiencies about 2 percentage points higher than those of RWI cycles: at the TIT of 1500°C made possible by intercooling, state-of-the-art aero-engines embodying the above cycle modifications can reach net electrical efficiencies of about 57% and 55%, respectively. This compares to efficiencies slightly below 56% achievable by combined cycles based upon large-scale heavy duty machines with TIT = 1280°C.
Updating the ANSI Standard on Measurement of Exhaust Emissions
Authors: Vaught J. M.
Published: February 2015

The American National Standards Institute (ANSI) required that the source testing Standard on Measurement of Exhaust Emissions from Stationary Gas Turbine Engines, B133.9, be brought up to date with today’s regulatory requirements and best measurement technology. The criteria for the design of the Standard along with its content and format are discussed. The selection of measurement methods for gaseous components, smoke, and particulates emitted by present day emission controlled industrial gas turbine engines is presented.
Medway: A High-Efficiency Combined Cycle Power Plant Design
Authors: Leis Darrell M. , Boss Michael J. , Melsert Matthew P.
Published: February 2015

The Medway Project is a 660 MW combined cycle power plant which employs two of the world’s largest advanced technology MS9001FA combustion turbine generators and an advanced design reheat steam turbine generator in a power plant system designed for high reliability and efficiency. This paper discusses the power plant system optimization and design, including thermodynamic cycle selection, equipment arrangement, and system operation. The design of the MS9031FA combustion turbine generator and the steam turbine generator, including tailoring for the specific application conditions, is discussed.
Gas Turbine and Combined Cycle Technologies for Power and Efficiency Enhancement in Power Plants
Authors: Boyce Meherwan P. , Meher-Homji Cyrus B. , Lakshminarasimha A. N.
Published: February 2015

A wide variety of gas turbine based cycles exist in the market today with several technologies being promoted by individual Original Equipment Manufacturers. This paper is focused on providing users with a conceptual framework within which to view these cycles and choose suitable options for their needs. A basic parametric analysis is provided to show the interdependency of Turbine Inlet Temperature (TIT) and Pressure Ratio on cycle efficiency and specific work.
Retrofittable Dry Low Emissions Combustor for 501-K Industrial Gas Turbine Engines
Authors: Razdan Mohan K. , McLeroy Jacob T. , Weaver William E.
Published: February 2015

This paper describes progress in the development of a 25 ppm NOx combustor that requires no diluent injection or post-combustion treatment The combustor will be retrofittable in all existing Allison Model 501-K series industrial engines. The approach undertaken is based on lean-premix combustion design incorporating an efficient fuel and air pre-mixing, fuel staging, and advanced wall cooling.

Extensive use has been made of Computational Combustor Dynamics (CCD) codes in the design of the low NOx combustor. Experimental work in support of the present effort includes atmospheric bench scale testing and high pressure rig testing. The bench tests have been performed to evaluate several candidate designs, to gain better understanding of general lean pre-mixed combustor behavior, and to verify model predictions. The bench test results have indicated good fuel/air mixing performance of the lean premixing domes. The high pressure simulated engine rig tests of the dry lean pre-mixed low emissions combustors using natural gas have demonstrated NOx levels less than 15 ppm vd (15% O2 corrected), well below the program goals.
Turbulent Gas Jet Flames in Cross-Flow at Low Momentum Flux Ratios
Authors: Gollahalll S. R. , Nanjundappa B.
Published: February 2015

An experimental study of the stability and structure of a propane gas jet flame in cross-flow at a low jet to cross-flow momentum flux ratio (0.024) is presented. The flame structure is characterized by two distinct zones. A two-dimensional flow recirculation zone attached to the burner tube in its wake forms the first zone. An axisymmetric flow follows the first zone downstream. The junction of the two zones is characterized by an intense mixing of jet and cross-flow streams. This paper deals with the structure of the first zone. The temperature and concentration profiles show that the physico-chemical processes and combustion in that zone are diffusion controlled.