bluuebunny/crossref_metadata_2025 huggingface dataset:
3D Laser Anemometry in a Rotating Cooling Channel
Authors: Servouze Y.
Published: December 2014

The flow in rotating cooling passages of jet engine turbine rotors is considered. Contrary to thermal data which have been obtained by a lot of people, velocity field data are very few. Nevertheless, in order to validate Navier-Stokes calculations, these two types of data are necessary. In such a flow with complexe secondary structures, 3D laser anemometer is the most suitable tool but its implementation on this application was a challenge.

Measurements were made first in static mode at Reynolds numbers of 5,000 and 25,000. The same model sections were then explored during rotation at a Reynolds number of 5,000 and a Rossby number of 0.33. Some results were obtained a Reynolds number of 25,000 and a Rossby numbers of 0.033 and 0.066.

The distortion of the axial velocity profile resulting from the Coriolis acceleration appears clearly when comparing the results obtained in the sections of the centrifugal arm. In the transverse plane, the two other velocity components show the secondary flow structures with two contrarotating vortices. The results obtained in the centripetal arm show that the flow depends on the 180 deg straight-corner turn located upstream.

These measurements confirm the assumptions made on the organisation of this type of flow, and the simulation results obtained at ONERA with the MATHILDA code and also by other teams who have published papers on the subject.

The first results obtained during this experimental work demonstrate the validity of the 3D laser anemometry in such a case. They show also some insufficiencies due to an application deemed difficult.
Development of Cooled, Ceramic First Stage Vanes for the FT8 Aeroderivative Gas Turbine
Authors: Day William H. , Kouris Konstantino , Holowczak John E. , Blair Michael F. , Hale Steven E. , Bornemisza Tibor G.
Published: December 2014

A design for an impingement cooled and vented silicon nitride turbine vane for potential application to the Pratt & Whitney/Turbo Power and Marine FT8 aeroderivative stationary turbine is presented. The final design reduced the cooling air requirement for this first stage turbine vane by several percent of total core flow, compared to the current cobalt alloy bill of materials airfoil. Careful attention to achieving uniform internal and external temperature distributions, and design of the trailing edge vests, were necessary to ensure a design having a high Probability of Survival. The NASA CARES code was used to determine probabilistic fast fracture reliability of the silicon nitride airfoil.
35 Years of Operation With Rolls-Royce Marine Proteus Gas Turbines in Swedish Navy Fast Surface Attack Ships
Authors: Löfdahl Jan-Olof
Published: December 2014

This paper covers 35 years of operation with the ROLLS-ROYCE Marine PROTEUS Gas Turbine in the Swedish Navy SPICA class Torpedo Boats and the NORRKÖPING class Missile Boats.

54 installed PROTEUS Gas Turbines in 18 boats have accumulated nearly 300 000 running hours. The service is intended to continue until year 2010.

The paper describes:

• Experience from operation.

• Technical problems and their solutions.

• Major modifications.

• Life extension program.

• Problem areas.

• The future of the PROTEUS within Swedish Navy.

The Swedish Navy operation of PROTEUS engines in fast surface attack ships is demanding and the environment is harsh. This causes great strain to the entire machinery.

With the Gas Turbine Propulsion new Ship maneuvering technique had to be developed and adopted.

Initial installation and engine problems had to be cured.

Throughout the years several technical problems have turned up and been solved.

The largest number or serious engine damages has been Power degradation and broken Compressor or burnt Turbine Blades and Vanes. Mainly as a result of a fouled Compressor, incorrect Bleed Valve setting or corrosion.

Next largest engine problem has been vibration. In the early days engine related but nowadays generated by the installation or other equipment in the ship.

All efforts laid down by involved personnel has greatly contributed to improve the reliability of the engine and its installation.

New problems will certainly show up by age and changed operational procedures, thus calling for a continued improvement work.

Spare parts accessibility will be the limiting factor for future PROTEUS operation. Therefore cooperation with ROLLS-ROYCE and the remaining operators in Spare Parts production and for exchange of Spare Parts is essential.
Simulations and Measurements on Impulse Blades for Heat Transfer Prediction in Supersonic Turbine Applications
Authors: Håll U. , Larsson J. , Bario F. , Kulisa P. , Slimani J. , Begin V. , Eriksson L.-E. , Wåhlén U.
Published: December 2014

This paper presents an overview of a research project aimed at improving the currently available methods to predict the flow and heat transfer in uncooled supersonic impulse turbines. These turbines are typically used in rocket engines based on the gas-generator cycle.

A fast boundary-layer method, suitable in the design phase, is presented. This method includes effects related to curvature, transition and separation bubbles.

For more detailed analysis, Navier-Stokes methods are used. Experiences from using a wide range of two-equation models to predict turbine blade heat transfer are summarized.

The experimental work uses a scaled-up, heated, linear blade cascade. The aim is to gain fundamental insight into the phenomena involved in turbine blade heat transfer and to obtain data for validation and development of new numerical methods. Detailed measurements, of both averaged and fluctuating properties of the velocity field, are made in the boundary layers down to a Y+ below 10. The results presented here are focused on the leading edge.
Recuperators in Gas Turbine Systems
Authors: Utriainen Esa , Sundén Bengt
Published: December 2014

The application of recuperators in advanced thermodynamic cycles is growing due to stronger demands of low emissions of pollutants and the necessity of improving the cycle efficiency of power plants to reduce the fuel consumption.

This paper covers applications and types of heat exchangers used in gas turbine units. The trends of research and development are brought up and the future need for research and development is discussed. Material aspects are covered to some extent.

Attempts to achieve compact heat exchangers for these applications are also discussed. With the increasing pressure ratio in the gas turbine cycle, large pressure differences between the hot and cold sides exist. This has to be accounted for.

The applicability of CFD (Computational Fluid Dynamics) is discussed and a CFD–approach is presented for a specific recuperator. This recuperator has narrow wavy ducts with complex cross-sections and the hydraulic diameter is so small that laminar flow prevails. The thermal-hydraulic performance is of major concern.
Turbine Model Improvement for a Heavy-Duty Gas Turbine Plant Simulation
Authors: Crosa G. , Troilo M. , Torelli A.
Published: December 2014

The interest of the world electricity market in the gas turbine and the gas-steam combined cycles has given a significant stimulus to the development of numerical simulations, useful in the detailed analyses of dynamic behaviour and off-design performance of the gas plant. This paper describes the latest improvements of a physical simulator built to predict the off-design and dynamic behaviour of single shaft, heavy-duty gas turbine plants. The analysis has been applied to the V94.2 and V64.3 models of the Ansaldo Energia production, that feature a compressor equipped with variable inlet guide vanes and an air bleed system cooled turbine. The mathematical model is non linear, based on the lumped parameter approach and described by a set of differential and algebraic equations. In particular, the next version presents a turbine model entirely rebuilt, based on a simplified, one-dimensional row by row calculation method. The equations system and the structure of the new code are here described, and the steady-state results of the dynamic model are compared with the results of an Ansaldo static code with a good correspond in the performance prediction. The model has been developed in the Matlab-Simulink® environment using some FORTRAN subroutines.
Turbulence Spectra and Length Scales Measured in Film Coolant Flows Emerging From Discrete Holes
Authors: Burd Steven W. , Simon Terrence W.
Published: December 2014

To date, very little attention has been devoted to the scales and turbulence energy spectra of coolant exiting from film cooling holes. Length scale documentation and spectral measurements have primarily been concerned with the freestream flow with which the coolant interacts. Documentation of scales and energy decomposition of the coolant flow leads to more complete understanding of this important flow and the mechanisms by which it disperses and mixes with the freestream. CFD modeling of the emerging flow can use these data as verification that flow computations are accurate. To address this need, spectral measurements were taken with single-sensor, hot-wire anemometry at the exit plane of film cooling holes. Energy spectral distributions and length scales calculated from these distributions are presented for film cooling holes of different lengths and for coolant supply plenums of different geometries. Measurements are presented on the hole streamwise centerline at the center of the hole, one-half diameter upstream of center, and one-half diameter downstream of center. The data highlight some fundamental differences in energy content, dominant frequencies, and scales with changes in the hole and plenum geometries. Coolant flowing through long holes exhibits smoothly-distributed spectra as might be anticipated in fully-developed tube flows. Spectra from short-hole flows, however, show dominant frequencies.
Design and Experimental Verification of an Optimised Compressor Blade
Authors: Bogers P. F. , Van den Braembussche R. A. , Breugelmans F. A. E.
Published: December 2014

This paper deals with the design of an optimised compressor blade and the experimental verification of its performance at design and off-design operation.

Starting from an existing controlled-diffusion blade, a new two-dimensional blade section has been designed by means of an inverse method, maintaining the same flow turning. Optimisation is made to achieve lower losses over an incidence range of 10 degrees while care has been taken to keep the blade thickness within prescribed tolerances.

The blade has been manufactured and tested in the C1 low speed cascade tunnel of the von Karman Institute. Experiments confirm substantial performance improvements at the blade mid section over the whole range of incidences. Measurements near the side walls show that the secondary flow losses are unchanged.

Verifications with a Navier-Stokes solver show a remarkable agreement with measurements and flow visualisations and explain the reasons for the important performance improvement at high incidence.
Analysis of Cooperation Between Central Power Utility and Dispersed Cogeneration Systems Through Time-of-Use Pricing
Authors: Yokoyama Ryohei , Ito Koichi
Published: December 2014

Because of an increase in peak electricity demand during summer daytime, a decrease in the annual load factor of power generation facilities has been one of the serious problems for central power utility systems. On the other hand, utility-connected dispersed cogeneration systems have been increasingly installed for energy supply in industrial and commercial sectors. This paper analyzes the cooperative relationship between power utility and cogeneration systems through time-of-use pricing. A game-theory approach in mathematical programming, i.e., bilevel programming, is applied to attain this objective. At the upper level, a power utility system determines the time-of-use rates for demand and energy charges of electricity purchased by a cogeneration system to maximize its load factor, and at the lower level, a cogeneration system determines its design and operation to minimize its annual total cost. Through a basic case study, it has been shown how the time-of-use rates are determined to attain the cooperative relationship between power utility and cogeneration systems.
Air System Correlations: Part 1 — Labyrinth Seals
Authors: Zimmermann H. , Wolff K. H.
Published: December 2014

Three important subjects of the physics of air systems have been chosen,

Part 1: Labyrinth Seals

Part 2: Rotating Holes and Two Phase Flow

as in these fields many new papers, partly controversial, are available. A new method of correlating the throughflow for labyrinth seals is generated, it covers the most important parameters and is based on several sources out of the literature. Recommendations for the necessary further research are added. It is concluded that much more effort is required in order to achieve progress against the literature partly consisting of more than 40-year-old books and not comprehensive enough for computerized engineering.
A Semi-Analytical Approach to Emissions Prediction in Gas Turbine Combustors
Authors: Facchini Bruno , Ferrara Giovanni , Mazzilli Paolo
Published: December 2014

An application of a simplified combustion model to pollutant emissions prediction in gas turbines is presented here. A critical analysis of the Rizk and Mongia semi-analytical model is conducted, and some corrections are accomplished to obtain a better agreement with experimental data. Special attention is devoted to the temperature equation, which is carefully modified, and to the schematization of several kinds of combustors. The simulation of some conventional pollutant reduction techniques, such as inert injection or exhaust gases re-circulation, is conducted with this corrected model. The results show a good agreement with experimental data both in conventional, and in innovative combustors, like Lean-Premixed or Rich-Lean concepts. The model needs a very short computation time and is likely to allow a simultaneous solution of chemical and fluid-dynamic aspect of the combustor.
Field Experience of the Sequential Combustion System for the GT24/GT26 Gas Turbine Family
Authors: Joos Franz , Brunner Philipp , Stalder Marcel , Tschirren Stefan
Published: December 2014

The first units of the Sequential Combustion System gas turbine family are in commercial operation. The first gas turbine GT24 (60Hz, 165MW-class) started the commercial operation, while the first GT26 (50Hz, 265MW-class) demonstrates its performance at the GT test facility. More engines are presently in the commissioning phase or will be in the near future. These turbines are designed to offer increased output at high GT efficiency. To acheive this, the sequential combustion system, a reheat process with two combustors, has been developed. Whereas the first combustor is based on the proven EV-combustor technology, extensive research and development efforts have been carried out in developing the lean premixed self-igniting second combustor (SEV).

This paper is a follow-up of the ASME paper 96-GT-315, which described the basic research work concerning the lean premixing SEV-burners with self-ignition. The present paper reports the experience gained during commissioning of the first engines.

The performance of the two combustors, as well as the measured emissions, are discussed and compared with the expected values and rig test results.

Finally, the potential of the sequential combustion system to reach low NOx levels is demonstrated by unveiling the results of the extensive testing program during the commissioning phase.
Validation of Numerical Methods at a Confined Turbulent Natural Gas Diffusion Flame Considering Detailed Radiative Transfer
Authors: Ganz Benedikt , Schmittel Peter , Koch Rainer , Wittig Sigmar
Published: December 2014

Radiation heat transfer in flames depends strongly on local quantities such as pressure, temperature and concentration of participating species. In the present study, 3D numerical calculations of radiative heat transfer together with the reacting flow field are compared to detailed measurements of the velocity, temperature and spectral radiation field of a model combustor.

The geometry of the combustion chamber (dch = 0.5m), the flame configuration (type-II swirling, diffusion flame) and the highly turbulent flow conditions resemble the characteristics of industrial combustors.

The concentrations of CO2, H2O, CO, CH4, NO, NOx, O2 and H2 as well as local mean temperatures and their fluctuations were recorded at 300 locations at 14 axial planes. The radiation intensity incident on the wall was measured spectrally and time resolved at 11 axial planes within the spectral range of 1.4 to 5.4 μm.

For numerically solving the reacting flow field, spectral methods for calculating the radiative heat transfer were coupled to fluid mechanical methods for calculating the reacting flow.

The agreement between numerical prediction and measurements for the reacting flow field as well as for the radiative heat transfer is reasonably good. The numerical computations show that radiative transfer is of major importance. The temperature in the hot reaction zone was found to be lowered by approximately 400 K by radiative losses.
Advanced Combustion Code: Overall Description, Prediction of a Jet Diffusion Flame and Combustor Flowfields
Authors: Tolpadi Anil K. , Prakash Chander , Hura Harjit , Mongia Hukam C.
Published: December 2014

The Computational Fluid Dynamics (CFD) code that has been used extensively for combustion applications within GE is CONCERT. CONCERT is a fully elliptic body-fitted CFD code based on pressure correction techniques that solves the three-dimensional (3-D) flow in an aircraft engine combustor. The geometry representation is given by single block structured grids. This paper gives an overview and presents some early applications of the Advanced Combustion Code (ACC) which is currently being developed to further advance the use of Computational Combustion Dynamics (CCD) at GE. ACC will have complex geometry representation capability via unstructured multiblock grids, and will comprise of a number of advanced combustion/spray/turbulence models that are being developed in a modularized fashion. The ACC solver is based on a fully implicit pressure correction algorithm with colocated grids. The development of ACC is taking place by comparing, as far as possible, the results against corresponding CONCERT calculations. Results of a systematic evaluation of various combustion models within the framework of a non-swirling jet diffusion flame using ACC will be presented. Full 3-D combustion calculations have been performed in the dome of single and multiple annular combustors: the corresponding flow and temperature fields and emissions predictions will be presented.
The Effect of the Fuel Injector Internal Geometry Upon the Primary Zone Aerodynamics
Authors: Hicks R. A. , Whiteman M. , Wilson C. W.
Published: December 2014

One of the major aims of research in gas turbine combustor systems is the minimisation of non-desirable emissions. The primary method of reducing pollutants such as soot and NOx has been to run the combustion primary zone lean. Unfortunately, this causes problems when the combustor is run under idle and relight conditions as the primary zone air fuel ratio (AFR) can exceed the flammability limit.

Altering this AFR directly affects the primary zone aerodynamics through changes in the spray profile. One method of determining the influence of changes in AFR upon the primary zone is to use Computational Fluid Dynamic (CFD) models. However, to model the flow through an air-blast fuel injector and accurately predict the resulting primary zone aerodynamics requires hundreds of thousands, if not millions, of cells. Therefore, with current computer capabilities simplifications need to be made.

One simplification is to model the primary zone as a 2-D case. This reduces the number of cells to a computationally solvable level. However, by reducing the problem to 2-D the ability to accurately model air-blast fuel injectors is lost as they are intrinsically 3-D devices. Therefore, it is necessary to define boundary conditions for the fuel injector.

Currently, due to difficulties in obtaining experimental measurements inside a air-blast fuel injector, these boundary conditions are often derived using semi-empirical methods. This paper presents and compares two such models; the model proposed by Crocker et al. in 1996 and one developed at DERA specifically for modelling air-blast fuel injectors.

The work also highlights the importance of the often neglected radial component upon the primary zone aerodynamics.
Numerical Simulation of the Flow Through the Return Channel of Multi-Stage Centrifugal Compressors
Authors: Lenke L. J. , Simon H.
Published: December 2014

The numerical simulation of the flow within a return channel is reported in this paper. The investigated return channel is typically to join the exit from one stage of a centrifugal machine to the inlet of the next stage. These channel covers the range of extremely low flow coefficients.

Different 3-D calculations with two different turbulence models (low-Reynolds-number k-ϵ and explicit algebraic Reynolds stress model) at the design point and part load range show the strongly three-dimensional flow structure with secondary flows on hub and shroud of the deswirl vanes. There are also significant separations downstream of the 180°-bend at suction and pressure side of the vanes.

The presented numerical results are compared with experimental data in different planes and at the vane contour. The results indicate small differences between the turbulence models in the prediction of losses, flow angles and separation behavior at design point. At off-design conditions the turbulence models begin to deviate notably in their prediction of separation.
Minimizing Vibratory Strain Measurement Error
Authors: Sensmeier Mark D. , Nichol Kurt L.
Published: December 2014

Correlation between dynamic strain gage measurements and modal analysis results can be adversely affected by gage misplacement and gage misorientation. An optimization algorithm has been developed which allows the modeled strain gage locations and orientations to be varied within specified tolerances. An objective function is defined based on the least squares sum of the differences between experimental and model results. The Kuhn-Tucker conditions are then applied to find the gage locations and orientations which minimize this objective function. The procedure is applied on a one-time basis considering all measured modes of vibration simultaneously. This procedure minimizes instrumentation error which then allows the analyst to modify the model to more accurately represent other factors, including boundary conditions. Flat plate vibratory data was used to demonstrate a significant improvement in correlation between measured data and model predictions.
Numerical Simulation of the Shock-Tip Leakage Vortex Interaction in a HPC Front Stage
Authors: Hoeger M. , Fritsch G. , Bauer D.
Published: December 2014

For a single-stage transonic compressor rig at the TU Darmstadt 3D viscous simulations are compared to L2F-measurements and data from the EGV leading edge instrumentation to demonstrate the predictive capability of the Navier-Stokes code TRACE_S. In a second step the separated regions at the blade tip are investigated in detail to gain insight into the mechanisms of tip leakage vortex-shock interaction at operating points close to stall, peak efficiency and choke. At the casing the simulations reveal a region with axially reversed flow, leading to a rotationally asymmetric displacement of the outermost stream surface and a localized additional pitch-average blockage of app. 2%. Loss mechanisms and streamline patterns deduced from the simulation are also discussed. Although the flow is essentially 3D, a simple model for local blockage from tip leakage is demonstrated to significantly improve 2D-simulations on S1-surfaces.
Nonlinear Heat-Release/Acoustic Model for Thermoacoustic Instability in Lean Premixed Combustors
Authors: Peracchio A. A. , Proscia W. M.
Published: December 2014

Lean premixed combustors, such as those used in industrial gas turbines to achieve low emissions, are often susceptible to thermoacoustic combustion instabilities, which manifest themselves as pressure and heat release oscillations in the combustor. These oscillations can result in increased noise and decreased durability due to vibration and flame motion. A physically based nonlinear parametric model has been developed that captures this instability. It describes the coupling of combustor acoustics with the rate of heat release. The model represents this coupling by accounting for the effect of acoustic pressure fluctuations on the varying fuel/air ratio being delivered to the flame, causing a fluctuating heat release due to both fuel air ratio variations and flame front oscillations. If the phasing of the fluctuating heat release and pressure are proper, an instability results that grows into a limit cycle. The nonlinear nature of the model predicts the onset of the instability and additionally captures the resulting limit cycle.

Tests of a lean premixed nozzle run at engine scale and engine operating conditions in the UTRC Single Nozzle Rig, conducted under DARPA contract, exhibited instabilities. Parameters from the model were adjusted so that analytical results were consistent with relevant experimental data from this test. The parametric model captures the limit cycle behavior over a range of mean fuel air ratios, showing the instability amplitude (pressure and heat release) to increase and limit cycle frequency to decrease as mean fuel air ratio is reduced.
Combined Gas Turbine and Diesel Generator Cooling Air Intake System
Authors: Yee Roger , Oswald Alan
Published: December 2014

A new generation of auxiliary ships to enter the U.S. Navy (USN) fleet is the AOE-6 SUPPLY CLASS. These fast combat support ships conduct operations at sea as part of a Carrier Battle group to provide oil, aviation fuel, and ammunition to the carrier and her escorts. The SUPPLY CLASS is the first ship in the entire USN fleet to use a combined gas turbine and diesel generator cooling air intake system to cool its respective engine modules. The cooling air intake was designed this way to save on costs. As the ships in this class continued with operations and problems of insufficient supply of cooling air for the gas turbines modules started surfacing, the entire intake system required investigation and analysis. Since the gas turbines and diesel generators share a common cooling air trunk, they were competing for air. This paper will outline the tests that were performed to determine the problems, the recommended solutions, and the lessons learned from the investigations.
Flow Characteristics of an Annular Intercooler-Diffuser for Gas Turbines
Authors: Agrawal Ajay K. , Tinneti Alejandro , Gollahalli Surbamanyam R.
Published: December 2014

Benefits of intercooling in power generating gas turbines can be maximized by reducing stagnation pressure loss in the intercooler flow path without adversely affecting the flow pattern in compressors. The intercooler-diffuser isolates the low pressure compressor from the intercooler, recovers the static pressure by decelerating the compressor discharge flow, and uniformly supplies low speed air to the intercooler for effective heat exchange. An experimental investigation was carried out to obtain data in a conceptual design with two sections: an outwardly canted prediffuser and a dump. The test-section was a one-fourth scale model of a typical industrial gas turbine. The diffuser flow is described in terms of the pressure recovery and loss coefficients, velocity vectors, static and stagnation pressure distributions, and the mean velocity and turbulence intensity profiles. The flow resistance by the intercooler was simulated to assess its effects on the upstream diffuser flow. The airflow rate was varied to obtain data at full and part-load operations. The inlet conditions corresponded to naturally developed axisymmetric annulus flow. Results show high stagnation pressure loss and distorted velocity profiles in the dump because of flow recirculation next to the casing. Pressure recovery was confined to the prediffuser and a tail-section downstream of the dump where the flow reattached. Results show that the diffuser flow was practically unaffected by the intercooler and by operation at part-load.
Effects of Compressibility and Turbulence Level on Bypass Transition
Authors: Schook R. , de Lange H. C. , van Steenhoven A. A.
Published: December 2014

The influences of compressibility and turbulence level on boundary layer transition are studied using a Ludwieg tube set-up. Heat transfer measurements are performed on the flow over a flat plate. The Mach number is varied between 0.16 and 0.56 while the unit-Reynolds number is kept constant. Several turbulence generating grids are used giving turbulence levels between 1.2% and 4.4%. Increasing the Mach number results in a decreasing turbulence level. Besides, the transition start Reynolds number increases.

The results indicate that besides the turbulence level another parameter is desired for the existing transition models. The dimensionless spot parameter is influenced by both the turbulence level and the Mach number. A tentative conclusion is that the start of transition depends on the inertial range minimum frequency in the energy spectrum while the shape of the transition curve, i.e. the intermittency, depends on the corresponding length scale.
CFD Assessment of a Wet, Low-NOx Combustion System for a 3MW-Class Industrial Gas Turbine
Authors: Liever Peter A. , Smith Clifford E. , Myers Geoffrey D. , Hernandez Lorenzo , Griffith Tim
Published: December 2014

A wet low-NOx combustion system being developed for the AlliedSignal ASE40 industrial gas turbine is assessed using advanced 3-D CFD analysis. A PDF combustion-turbulence interaction model was modified to allow analysis of simultaneous injection of water with gaseous or liquid fuel. To the authors’ knowledge, such a CFD analysis is unique in the open literature. Analyses of the wet low-NOx combustion system were performed with and without water injection at full power engine conditions. Good qualitative agreement between engine emission data and predictions was seen. NOx reductions of 58% and 77% were measured for water-to-natural gas mass ratios of 0.5 and 1.0, respectively, compared to 75% and 93% for CFD calculations. Corresponding CO levels were measured to increase by factors of 3 and 9, compared to CFD predictions of 4 and 7. Similar trends were predicted for water injection with DF-2 diesel fuel. Predicted overall flow patterns were not significantly changed with water injection. NOx reductions were caused by a reduction in maximum flame temperatures in the primary and intermediate zones when water was injected. CO increases were caused by a reduction of CO oxidation downstream of the dilution zone (in the turn-around duct) due to lower gas temperatures with water injection.
Interim Logistics Support for the 501-K17 Gas Turbine Improvement Program
Authors: Hartey Maurice J. , Kucowski Kenneth , Ochs Linda , Howe Robin
Published: December 2014

The US Navy utilizes Gas Turbine Engines in a variety of propulsion and power generation applications. Despite dramatic shifts in the world defense posture, the basic application requirements for this equipment has not changed. Each ship and her crew operate in potentially hazardous environments, either by threat from man or nature. Because US Navy ships operate around the world, each ship must be self-supported and continue to function in her mission far from repair and maintenance activities. Due to the unique nature of this application, the configuration of the 501-K17 Gas Turbine Generators is constantly under technical review to provide critical technical upgrades. Included in the engineering review process is the requirement to provide integrated logistics support at installation. Interim support packages provide interim logistics products which fulfill the support requirements and maintain configuration control of the Gas Turbine Engines across hull applications without impeding the installation schedule.
The Potential of Sequential Combustion for High Bypass Jet Engines
Authors: Vogeler Konrad
Published: December 2014

ABB has designed a new family of industrial gasturbines for power generation using a Sequential Combustion Cycle (SCC) on a large single shaft engine. This concept allows considerable increase in power density and efficiency by only increasing pressure without raising the maximum hot gas temperature of the cycle. Instead a second combustion after an HP-turbine is used to reheat the gas before the final expansion in an LP-turbine.

This concept is applied to the analysis of a high bypass ratio jet engine. In an engine with a single combustor, thrust is a function of bypass ratio and the combination of maximum pressure and temperature in the cycle. The proposed SCC allows increased thrust without pushing technology on materials and cooling. A modern twin spool engine is taken as reference. When total inlet massflow is kept constant, increasing bypass ratio decreases core mass flow. This limits the fuel flow for the HP-spool and hence total energy input to the engine. Introduction of the SCC gives another parameter of freedom to the cycle design. However the twin spool concept is now a disadvantage. The low fuel flow for the HP-spool due to high bypass ratio means there is not enough energy available to build up the necessary pressure for an economical expansion in the LP-turbine after the second combustion. Specific fuel consumption will be unacceptable.

It is proposed to apply the SCC concept in a single spool engine with a geared fan. Both turbines can now support the compression. The fan is operated as a constant speed propeller with variable blade pitch. This engine concept allows for a given inlet massflow a substantially higher bypass ratio and hence decreases specific fuel consumption while specific thrust can be kept on a level which will be considerably higher than it would be in todays engines with comparable bypass ratio.
A Small Scale Biomass Fueled Gas Turbine Engine
Authors: Craig Joe D. , Purvis Carol R.
Published: December 2014

A new generation of small scale (less than 20 MWe) biomass fueled, power plants are being developed based on a gas turbine (Brayton cycle) prime mover. These power plants are expected to increase the efficiency and lower the cost of generating power from fuels such as wood. The new power plants are also expected to economically utilize annual plant growth materials (such as rice hulls, cotton gin trash, nut shells, and various straws, grasses, and animal manures) that are not normally considered as fuel for power plants. This paper summarizes the new power generation concept with emphasis on the engineering challenges presented by the gas turbine component.
Optimization of Swirl Brakes by Means of a 3D Navier-Stokes Solver
Authors: Nielsen K. Krogh , Van den Braembussche R. A. , Myllerup C. M.
Published: December 2014

This paper deals with the modeling of the flow in the leakage cavity between shroud and stator of a radial pump and the design of optimized swirl brakes at the inlet of the seal. As pressure losses were of no importance in this application, the only criterion for optimization was to minimize the swirl at the seal inlet in order to enhance the rotordynamic stability of it. The design investigation was performed by means of a 3D Navier-Stokes solver. A variety of vane designs were analyzed. It was shown that the three-dimensional vortical structure of the flows plays a dominant role and can be efficiently used to reduce or even invert the swirl at the seal inlet.
Preliminary Economics of Black Liquor Gasifier/Gas Turbine Cogeneration at Pulp and Paper Mills
Authors: Larson Eric D. , Consonni Stefano , Kreutz Thomas G.
Published: December 2014

Black liquor, the lignin-rich byproduct of kraft pulp production, is burned in boiler/steam turbine cogeneration systems at pulp mills today to provide heat and power for onsite use. Black liquor gasification technologies under development would enable this fuel to be used in gas turbines. This paper reports preliminary economics of 100-MWe scale integrated black-liquor gasifier/combined cycles using alternative commercially-proposed gasifier designs. The economics are based on detailed full-load performance modeling and on capital and operating and maintenance costs developed in collaboration with engineers at Bechtel Corporation and Stone and Webster Engineering. Comparisons with conventional boiler/steam turbine systems are included.
Gas Turbine Parameter Corrections
Authors: Volponi Allan J.
Published: December 2014

The various parameters appearing along an engine’s gas path, such as flows, pressures, temperatures, speeds, etc., vary not only with power condition but also with the ambient conditions at the engine’s inlet. Since a change in inlet temperature and/or pressure will contribute to an attendant change in a gas path parameter’s value, it would be difficult to characterize the aero-thermodynamic relationships between gas turbine engine parameters, (even at a constant engine operating point) unless the ambient conditions are somehow accounted for. This is usually accomplished through the use of corrected engine parameters. Although most of these corrections are well known by practitioners in the industry, knowledge of their origin does not appear to be as commonplace. The purpose of this paper is to fill that gap and furnish a summary of the commonly used corrections for the “major” gas path parameters that are used in performance analysis, diagnostics and control design, and to offer a derivation of these corrections. We will suggest both an analytic approach as well as an empirical approach. The latter can be used to establish the correction for parameters not directly addressed in this paper, as well as to fine tune the correction factors when actual engine data is available.
A Mixed Shell Element for Cambered Helicoidal Blades and Dynamic Stresses due to Aerodynamic Excitation
Authors: Rao J. S. , Ramakrishnan C. V. , Gupta K. , Rao K. K.
Published: December 2014

An eight noded mixed shell element for the vibration analysis of rotating cambered helicoidal blades is presented. The strain displacement relations of Gol den’veizer are used and Reissner’s functional is adopted in deriving this element. The effect of initial in-plane stresses is also included. Also, expressions for the pressure difference between the pressure and suction profiles of the rotating blade are derived from two dimensional thin airfoil theories of a stage. The forces thus obtained are applied on the blade to determine the dynamic stresses.
Combustion Aspects of Application of Hydrogen and Natural Gas Fuel Mixtures to MS9001E DLN-1 Gas Turbines at Elsta Plant, Terneuzen, The Netherlands
Authors: Morris John D. , Symonds Richard A. , Ballard F. Leon , Banti Adolfo
Published: December 2014

Elsta B.V. Co., C.V., requested that the General Electric Company and Turbotecnica/Nuovo Pignone propose expanding fuels flexibility for the three MS9001E, DLN-1 (TM) units (being) installed at Terneuzen, The Netherlands. The major challenge was the use of a process gas rich in hydrogen for mixing with normal plant natural gas fuel supply so that molecular hydrogen in the mixture reached 10 percent by volume. Evaluation of the gas turbine combustor operation, based on the criteria of emissions, stability and turndown, required extensive testing, first at the General Electric Corporate Research and Development Center, then at the Schenectady (Building 262) Combustion Laboratory, a full pressure combustor test facility, and finally at Terneuzen with the gas turbines and plant owner’s fuel mixing and forwarding systems. Results of this field testing, built upon the earlier work, are detailed below.
Effects of Tip Clearance and Casing Recess on Heat Transfer and Stage Efficiency in Axial Turbines
Authors: Ameri A. A. , Steinthorsson E. , Rigby David L.
Published: December 2014

Calculations were performed to assess the effect of the tip leakage flow on the rate of heat transfer to blade, blade tip and casing. The effect on exit angle and efficiency was also examined. Passage geometries with and without casing recess were considered. The geometry and the flow conditions of the GE-E3 first stage turbine, which represents a modern gas turbine blade were used for the analysis. Clearance heights of 0%, 1%, 1.5% and 3% of the passage height were considered. For the two largest clearance heights considered, different recess depths were studied. There was an increase in the thermal load on all the heat transfer surfaces considered due to enlargement of the clearance gap. Introduction of recessed casing resulted in a drop in the rate of heat transfer on the pressure side but the picture on the suction side was found to be more complex for the smaller tip clearance height considered. For the larger tip clearance height the effect of casing recess was an orderly reduction in the suction side heat transfer as the casing recess height was increased. There was a marked reduction of heat load and peak values on the blade tip upon introduction of casing recess, however only a small reduction was observed on the casing itself. It was reconfirmed that there is a linear relationship between the efficiency and the tip gap height. It was also observed that the recess casing has a small effect on the efficiency but can have a moderating effect on the flow underturning at smaller tip clearances.
Curvature Effects on Discrete-Hole Film Cooling
Authors: Berhe Mulugeta K. , Patankar Suhas V.
Published: December 2014

A numerical study has been conducted to investigate the effects of surface curvature on cooling effectiveness using three-dimensional film cooling geometries that included the mainflow, injection hole, and supply plenum regions. Three surfaces were considered in this study, namely, convex, concave, and flat surfaces. The fully elliptic, three-dimensional Navier-Stokes equations were solved over a body-fitted grid. The effects of streamline curvature were taken into account by using algebraic relations for the turbulent viscosity and the turbulent Prandtl number in a modified k-ε turbulence model. Computations were performed for blowing ratios of 0.5, 1.0, and 1.5 at a density ratio of 2.0. The computed and experimental cooling effectiveness results were compared. For the most part, the cooling effectiveness was predicted quite well. A comparison of the cooling performances over the three surfaces reveals that the effect of streamline curvature on cooling effectiveness is very significant. For the low blowing ratios considered, the convex surface resulted in a higher cooling effectiveness than both the flat and concave surfaces. The flow structures over the three surfaces also exhibited important differences. On the concave surface, the flow involved a stronger vorticity and greater mixing of the coolant jet with the mainstream gases. On the convex surface, the counter-rotating vortices were suppressed and the coolant jet pressed to the surface by a strong cross-stream pressure gradient.
Inhibition of Interdiffusion From MCrAlY Overlay Coatings by Application of a Ni-Re Interlayer
Authors: Page Richard A. , Leverant Gerald R.
Published: December 2014

The durability of protective coatings on combustion turbine blades and vanes is a critical issue in the power generation industry. Coating life usually dictates the refurbishment intervals for these components, and these intervals have generally been of shorter duration than desired by the operators of the equipment. Both MCrAlY and aluminide type coatings protect against oxidation and hot corrosion by forming a protective Al2O3 surface layer. Degradation of the coatings occurs by depletion of the aluminum content of the coating through interdiffusion with the substrate and through the formation and spallation of an external Al2O3 scale.

The results obtained in this study clearly show that the application of a thin interlayer of Ni-Re beneath the MCrAlY coating can significantly decrease the growth rate of the inner β-NiAl depletion zone. Order of magnitude reductions in the inner depletion zone thickness formed at 1000 hours were obtained with both the Ni-32 wt.% Re and the Ni-47 wt% Re interlayer coatings. Since formation of the inner depletion zone is believed to result from interdiffusion with the substrate, these results suggest that the Ni-Re interlayer provided a significant impediment to the inward diffusion of Al into the substrate.
CO2 Emission Abatement in IGCC Power Plants by Semiclosed Cycles: Part A — With Oxygen-Blown Combustion
Authors: Chiesa Paolo , Lozza Giovanni
Published: December 2014

This paper analyzes the fundamentals of IGCC power plants where carbon dioxide produced by syngas combustion can be removed, liquefied and eventually disposed, to limit the environmental problems due to the “greenhouse effect”. To achieve this goal, a semiclosed-loop gas turbine cycle using an highly-enriched CO2 mixture as working fluid was adopted. As the oxidizer, syngas combustion utilizes oxygen produced by an air separation unit. Combustion gases mainly consist of CO2 and H2O: after expansion, heat recovery and water condensation, a part of the exhausts, highly concentrated in CO2, can be easily extracted, compressed and liquefied for storage or disposal.

A detailed discussion about the configuration and the thermodynamic performance of these plants is the aim of the paper. Proper attention was paid to: (i) the modelization of the gasification section and of its integration with the power cycle, (ii) the optimization of the pressure ratio due the change of the cycle working fluid, (iii) the calculation of the power consumption of the “auxiliary” equipment, including the compression train of the separated CO2 and the air separation unit. The resulting overall efficiency is in the 38–39% range, with status-of-the-art gas turbine technology, but resorting to a substantially higher pressure ratio. The extent of modifications to the gas turbine engine, with respect to commercial units, was therefore discussed. Relevant modifications are needed, but not involving changes in the technology.

A second plant scheme will be considered in the second part of the paper, using air for syngas combustion and a physical absorption process to separate CO2 from nitrogen-rich exhausts. A comparison between the two options will be addressed there.