bluuebunny/crossref_metadata_2025_split huggingface dataset:
Water Injection Into Navy Gas-Turbine Combustors to Reduce NOx Emissions
Authors: Urbach Herman B. , Knauss Donald T. , Wallace Balfour L. , Emory John , Frese John , Bishop Joseph W. 
Published: December 2014

Land-based water injection into the combustor of gas turbines is a state-of-the-art technology, which is a low-risk, low-cost option for reduction of gas-turbine emissions. A controller for a water-injected combustor (WIC) system was designed for automatic control of water injection. Steady-state tests of the WIC system in an LM2500 propulsion-engine facility yielded basic engine-interactive data for the WIC’s unique automatic software logic. The steady-state tests demonstrated anticipated NOx reductions in conformity with proposed (but not implemented) California Air Resources Board (CARB) mandates. The controller automatically compensates for the effects of humidity, temperature and engine load.
This automatic response was expressly designed to deliver acceptable water rates even during the abrupt power excursions encountered in emergencies, including collision-avoidance crashback maneuvers. The transient test data indicated unacceptable flameout in the engine during engine deceleration to idle speed. Detailed analyses of the flameouts show that the controller can reduce water flow within two deciseconds of a change in power demand. However, the residence time of water in the manifolds can be about a second for some operating conditions. Several fixes for this problem are described.
Influence of Turbulence on the Dynamic Behaviour of Premixed Flames
Authors: Krüger Uwe , Hoffmann Stefan , Krebs Werner , Judith Hans , Bohn Dieter , Matouschek Gero 
Published: December 2014

Environmental compatibility requires low emission burners for gas turbine power plants as well as for jet engines. In the past significant progress has been made developing low NOx and CO burners by introducing lean premixed techniques. Unfortunately these burners often have a more pronounced tendency than conventional burner designs to produce combustion driven oscillations. The oscillations may be excited to such an extent that strong pulsation may possibly occur; this is associated with a risk of engine failure and higher NOx emissions.
In order to describe the acoustical behaviour of the complete burner system the determination of the transfer function of the flame itself is crucial. Using a new method which was presented by Bohn, Deutsch and Krüger (1996) and Bohn, Li, Krüger and Matousckek (1997), the dynamic flame behaviour can be predicted by means of a full Navier-Stokes-simulation of the complex combustion process for the steady-state as well as for the transient situation.
This method has been successfully used by the authors to obtain the frequency response of turbulent diffusion flames and laminar premixed flames. For the application in modern gas turbines the influence of turbulence on the dynamic behaviour of premixed flames is of big interest.
Therefore, this paper presents numerical studies of a turbulent premixed flame configuration for which experimental data is available in the literature. Two different combustion models have been used for the steady-state as well as for the transient calculations. With the improved model, which takes into account the chemical kinetics and the interaction between turbulence and kinetics, good agreement has been found for the steady-state results and for the frequency response of the flame.
Thermo-Mechanical Characterizations of Coatings for HP Turbines
Authors: Boudot A. , Crabos F. , Fournier D. , Monceau D. 
Published: December 2014

Three different coatings were studied in this work: vacuum plasma-sprayed NiCoCrAlYTa, electrolytically deposited NiCoCrAlYTa and Ni-Pt aluminide diffusion coatings. These three coatings were deposited on AM3 single crystal alloy. The tensile properties of coated single crystal test specimens were investigated. Ductile to Brittle Transition Temperatures (DBTT) were determined from tensile tests. All the coatings were examined before and after testing.
All the tested coatings induce a ductile/brittle transition. Strain rate has a great influence on the transition temperature. The comparison between plasma-sprayed deposition and electrodeposition illustrates the strong influence of coating microstructure. In every case, NiCoCrAlYTa coatings were more ductile, and then less detrimental, than aluminide coatings.
Three-Dimensional Flow Predictions in Axial-Flow Turbine Cascades
Authors: Niestroj O. , Came P. M. 
Published: December 2014

Numerical investigations of the three-dimensional flowfields in a turbine linear cascade and in an annular, non-rotating turbine cascade have been carried out. Both cascades were the subjects of published experimental studies. In the experimental set-up for the annular cascade the hub wall upstream of the blades could be either stationary or rotating so that a collateral or a skewed inlet boundary layer could be achieved.
The results of the computations have been compared with the experimental data. Total pressure loss coefficients and exit flow angles have been studied and in both cascades the predicted secondary flow effects are in good agreement with the experimental results. Two-dimensional contour plots in the measurement planes and pitchwise-averaged flow angle comparisons illustrate the accuracy of the computations.
Development of Hexaaluminate Catalysts for Combustion of Gasified Biomass in Gas Turbines
Authors: Johansson E. Magnus , Danielsson K. M. Jonny , Ersson Anders G. , Järås Sven G. 
Published: December 2014

There is an increasing interest in catalytic combustors fuelled by low-heating value (LHV) gases, with a LHV of 5–7 MJ/Nm3. This is because catalytic combustion could be advantageous compared to flame combustion with respect to stable combustion of LHV-gases and low conversions of fuel-N (mainly NH3) to NOx. In the present project, funded by the EU Joule Programme, catalytic combustion of gasified wood for gas turbine applications is studied. A synthetic gas mixture of H2, CO, CO2, H2O, CH4, N2 and NH3, that resembles the output from a fluidized bed gasifier using biomass as raw material, is used. The gas mixture is mixed with air at atmospheric pressure and combusted over washcoated cordierite monoliths in a bench-scale laboratory quartz-reactor.
The objectives of the work described here are twofold. To begin with, improvement of the thermal stability of hexaaluminate washcoats by substitutions of rare earth or transition metal compounds is being studied. Secondly, catalytic combustion of gasified biomass over these washcoats has been studied in a bench-scale unit.
In this on-going project, obtained result show that it is possible to improve the surface area of hexaaluminate compounds up to 17 m2/g after careful synthesis and calcination up to 1400 °C for four hours. The selectivity of NH3-conversion to N2 is at present at 60 percent, but varies strongly with temperature. Fuel components such as H2, CO, C2H4 and NH3 ignite at temperatures close to compressor outlet temperatures. This means that a pilot-flame may not be needed for ignition of the fuel. A comparison between a Pd-impregnated lanthanum hexaaluminate and a Mn-substituted lanthanum hexaaluminate showed that the ignition temperature and the NOx-formation varied strongly over the two different catalysts.
Effects of Fuel Nozzle Displacement on Pre-Filming Airblast Atomization
Authors: Han Yeoung Min , Seol Woo Seok , Lee Dae Sung , Yagodkin Victor I. , Jeung In Seuck 
Published: December 2014

In gas turbine combustors, optimum arrangement between a fuel nozzle and a swirler/prefilmer module must be sought to achieve satisfactory ignition and stability characteristics in addition to reduced level of emissions. However, due to thermal expansion of the combustor or misalignment of the fuel nozzle, the location of a fuel nozzle may vary. Displacement of a fuel nozzle may change the amount of fuel injected to the pre-filming device (usually the inner swirler wall) and the location of attachment, which in turn affects the thickness of pre-filming liquid sheet on the wall. As a result, the spray structure formed by pre-filming airblast atomization may be significantly changed.
An experimental investigation is carried out to study the effects of fuel nozzle displacement on the structure of a spray formed by a dual orifice pressure atomizer and a counter-rotating dual swirler. The inner wall of the swirler is designed to be used as a pre-filming device. The behavior of droplets, the flow characteristics of the swirling air flow, and the interaction between droplets and the flow are studied. Optical diagnostic methods including a flow visualization and an Adaptive Phase/Doppler technique are used. Distributions of droplet size, number density, and liquid phase volume flux are presented for various fuel nozzle displacements, in addition to gas phase velocity.
Periodic Transition on an Axial Compressor Stator — Incidence and Clocking Effects: Part I — Experimental Data
Authors: Walker G. J. , Hughes J. D. , Solomon W. J. 
Published: December 2014

Periodic wake-induced transition on the outlet stator of a 1.5 stage axial compressor is examined using hot-film arrays on both the suction and pressure surfaces. The time-mean surface pressure distribution is varied by changing the blade incidence, while the freestream disturbance field is altered by clocking of the stator relative to an inlet guide vane row.
Ensemble average plots of turbulent intermittency and relaxation factor (extent of calmed flow following the passage of a turbulent spot) are presented. These show the strength of periodic wake-induced transition phenomena to be significantly influenced by both incidence and clocking effects. The nature and extent of transition by other modes (natural, bypass and separated flow transition) are altered accordingly. Leading edge and mid-chord separation bubbles are affected in a characteristically different manner by changing freestream periodicity. There are noticeable differences between suction and pressure surface transition behavior, particularly as regards the strength and extent of calming.
In Part II of this paper, the transition onset observations from the compressor stator are used to evaluate the quasi-steady application of conventional transition correlations to predict unsteady transition onset on the blading of an embedded axial compressor stage.
An Empirical Approach to the Preliminary Design of a Closed Cycle Gas Turbine
Authors: op het Veld R. P. , van Buijtenen J. P. 
Published: December 2014

This paper investigates the layout and achievable efficiencies of rotating components of a Helium gas turbine. This is done by making a preliminary design of the compressor and turbine needed for the power conversion in a combined heat and power plant with a 40 MWth nuclear high temperature reactor as a heat source. State of the art efficiency values of air breathing gas turbines are used for the first calculations. The efficiency level is corrected by comparing various dimensionless data of the Helium turbomachine with an air gas turbine of similar dimensions.
A single shaft configuration with a high speed axial turbine will give highest performance and simple construction. If a generator has to be driven at a conventional speed, a free power turbine configuration must be chosen. The choice of the configuration depends among others on the cost and availability of the asynchrone generator and frequency convertor.
Development of Ceramic Components for Ceramic Gas Turbine Engine (CGT302)
Authors: Yoshida Makoto , Tanaka Koichi , Kubo Toshifumi , Terazono Hirofumi , Tsuruzono Sazo 
Published: December 2014

The 300kW Industrial Ceramic Gas Turbine (CGT) Research and Development Project is going on as a part of New Sunshine project under the contract of Japanese Ministry of International Trade and Industry (MITI). The objective of this project is to achieve higher efficiency and lower pollutant emissions for small sized gas turbine engines used in co-generation systems.
Under this project, Kyocera has been developing various ceramic components for the CGT302 engine designed by Kawasaki Heavy Industries (KHI). This engine has set a thermal efficiency of over 42% at a turbine inlet temperature (TIT) of 1350°C as a final target. For such operations, we have developed the new silicon nitride materials, SN281 and SN282, which have excellent stress rupture strength and superior oxidation resistance at elevated temperatures up to 1500°C.
We have also developed improved fabrication technologies for the use of SN281 and SN282 as engine components. In 1997 fiscal year, all ceramic components for the CGT302 were successfully fabricated by using these new materials. Especially, the large sized monolithic power turbine (PT) rotor, which has a 192mm outer diameter, was manufactured by SN282, and exhibited fracture rotating speeds greater than 120% of the design rotating speed in cold spin tests.
This paper discusses the mechanical properties of these new materials and the results of ceramic components evaluated under engine test conditions.
FT8 Phase II Reliability Improvement Program
Authors: Boley Warren M. , Prete Thomas W. 
Published: December 2014

This paper describes the FT8 gas generator (GG8) development history, including required design modifications to the JT8D aircraft engine, initial field experience and the latest reliability improvements incorporated into the GG8. The modifications include improvements to bearing compartment operating temperature, bearing compartment seals, and increases to bearing life. Turbine durability improvements are also discussed.
The incorporation and control of a cold air buffer system to control bearing compartment oil coke formation is provided. Improvements to bearing compartment carbon seals are reviewed and the benefits of this design are discussed. Rotor system thrust bearing life improvements are achieved through the incorporation of modified compressor seals and turbine aerodynamics.
Genetic Algorithm Based Strategies for Radial Flow Impeller Design
Authors: Tuccillo Raffaele , Senatore Adolfo 
Published: December 2014

The authors present a method for radial flow impeller design which pays attention to the set-up of optimal design strategies, the latter based upon the employment of a genetic algorithm which controls a Quasi-3D flow simulation of a radial flow impeller, with integral boundary layer calculation.
The design procedure develops through a number of steps, which are characterized by a progressive reduction in the search interval of each independent variable. In addition, a more accurate definition of the blade geometry and a more reliable flow analysis is obtained through a mesh refinement in the flow model, when the whole optimization process is close to convergence.
The results demonstrate the possibility of achieving an optimal choice of the impeller geometrical parameters by approaching, in a first phase, the design data, and then by proceeding with a number of refinement steps, as outlined above. In this way. the accuracy of the whole procedure is strongly increased, so that the typical effectiveness of the genetic algorithms in the preliminary selection steps is combined with a detailed investigation of the impeller blade features in the final steps of the optimized design. The effectiveness becomes, therefore, comparable with that of classical gradient based methods of optimization. At the same time, the genetic algorithm is capable of handling discontinuities in the objective function, thus overcoming the typical limits of numerical methods.
In order to emphasize the effectiveness of the proposed procedure, the results refer to a wide variety of design data. Both the impeller configurations and the flow distributions found demonstrate that the final solution is in agreement with the design target and constraints.
Aerodynamic Loss Increase due to Individual Film Cooling Injections From Gas Turbine Nozzle Surface
Authors: Kubo Ryo , Otomo Fumio , Fukuyama Yoshitaka , Nakata Yuhji 
Published: December 2014

A CFD investigation was conducted on the total pressure loss variation for a linear nozzle guide vane cascade of a gas turbine, due to the individual film injections from the leading edge shower head, the suction surface, the pressure surface and the trailing edge slot. The results were compared with those of low speed wind tunnel experiments.
A 2-D Navier-Stokes procedure for a 2-D slot injection, which approximated a row of discrete film holes, was performed to clarify the applicable limitation in the pressure loss prediction during an aerodynamic design stage, instead of a costly 3-D procedure for the row of discrete holes.
In mass flow rate ratios of injection to main flow from 0% to 1%, the losses computed by the 2-D procedure agreed well with the experimental losses except for the pressure side injection cases. However, as the mass flow rate ratio was increased to 2.5%, the agreement became insufficient. The same tendency was observed in additional 3-D computations more closely modeling the injection hole shapes.
The summations of both experimental and computed loss increases due to individual row injections were compared with both experimental and computed loss increases due to all-row injection with the mass flow rate ratio ranging from 0% to 7%. Each summation agreed well with each all-row injection result. Agreement between experimental and calculated results was acceptable. Therefore, the loss due to all-row injections in the design stage can be obtained by the correlations of 2-D calculated losses from individual row injections. To improve more precisely the summation prediction for the losses due to the present all-row injections, extensive research on the prediction for the losses due to the pressure side injection should be carried out.
Efficiency Measurements of an Annular Nozzle Guide Vane Cascade With Different Film Cooling Geometries
Authors: Day Charles R. B. , Oldfield Martin L. G. , Lock Gary D. , Dancer Stephen N. 
Published: December 2014

This paper further extends the research reported by Day et al. (1997), which reported aerodynamic efficiency measurements on an annular cascade of engine representative transonic nozzle guide vanes with extensive film cooling.
This work compares the measured aerodynamic efficiencies of blades with 14 rows of cylindrical cooling holes with a new geometry in which 8 of the rows have been replaced by holes having a fan-shaped exit geometry. The effects of adding trailing edge slot ejection are also presented. By selectively blocking rows of holes, the cumulative effect on the mid-span efficiency of adding rows of cooling holes has also been determined.
A dense foreign gas (SF6/Ar mixture) is used to simulate engine representative coolant-to-mainstream density ratios, momentum ratios and blowing rates under ambient temperature conditions. The flowfield measurements have been obtained using a four-hole pyramid probe in a short duration blowdown facility which correctly models engine Reynolds and Mach numbers, as well as the inlet turbulence intensity.
Experimental results are presented as area traverse maps (total pressure, isentropic Mach number and flow angles), from which the incremental changes in efficiency due to film cooling have been calculated. The effects of different assumptions for the coolant total pressure are shown. Experimental data agrees reasonably well with loss predictions using a Hartsel model.
PIV Investigation of the Flow Characteristics in an Internal Coolant Passage With Two Ducts Connected by a Sharp 180° Bend
Authors: Schabacker J. , Bölcs A. , Johnson B. V. 
Published: December 2014

A PIV study of the flow in a stationary model of a smooth two-pass internal coolant passage is presented, which focuses on the flow characteristics in the sharp 180° bend and downstream of the bend where the flow is redeveloping. Because PIV in its traditional conception only allows for the investigation of two-dimensional flow, a stereoscopic digital PIV system was assembled that measures all three velocity components simultaneously. The mean-velocity field and turbulence quantities of the flow are obtained from the PIV measurements.
The model of the coolant passage consists of two square ducts, each having a length of 19 hydraulic diameters, which are connected by a sharp 180° bend with a rectangular outer wall. The measurements were obtained at one flow condition with a flow Reynolds number of 50,000. A strong secondary flow motion occurs in the bend of the smooth passage that consists of two counter rotating vortices, which impinge on the outer wall and influence the flow in the downstream leg. Both of the outer corners contain regions of recirculating flow. A separation bubble, about 1.5 hydraulic diameters long, occurs on the inner wall of the return pass. In the symmetry plane, the flow recovers from the bend effect within 10 hydraulic diameters.
A New Test Facility for Testing of Cooled Gasturbine Components
Authors: Rådeklint Ulf R. , Hjalmarsson Christer S. 
Published: December 2014

A high pressure hot test facility for cooled gas turbine components has been developed for use in turbine cooling research. In this facility, heat transfer tests for a sector of real turbine vanes can be performed under continuous operation. The heat transfer tests are performed at an operating point that is scaled down from the real engine operating point. The compressor can deliver air at the rate of up to 10 kg/s at 20 bars. Air temperatures of up to 1170 K can be achieved by using an oil-fired combustor. Besides conventional instrumentation such as thermocouples and pressure probes, the facility is equipped with an IR-camera to map two-dimensional wall temperature fields. Hot wire anemometry and an LDV system are used to determine mean and fluctuating velocity components.
This paper describes design and performance of the test facility as well as the control and measurement equipment. The test and evaluation procedures used for testing of cooled gas turbine vanes are also presented.
On the Effect of Single Mode Bending/Torsion Coupling on the Flutter Behavior in a Transonic Fan
Authors: Isomura Kousuke 
Published: December 2014

The effect of the coupling of the torsion mode blade vibration to the bending mode flutter in transonic fans has been studied by quasi-3D viscous unsteady calculations. The type of flutter in this research is that of a highly loaded blade with a tip relative Mach number just above unity, for which the mechanism is that the instability of the passage shock wave when it unstarts generates the dominant blade exciting aerodynamic work at its foot on the pressure surface of the blade. The dependence of such flutter on the blade vibration mode, i.e. the amplitude ratio and the phase difference of the bending and torsional components has been studied.
The study showed that the blade exciting aerodynamic work reduced when the torsional component is added in-phase (torsional motion noses up during the upward bending motion) to the bending oscillation. The amplitude of the torsional component was shown to have an optimum amplitude.
It was also shown that this tendency would switch when the shock wave is fully detached, and the blade exciting aerodynamic work would increase by adding the torsional component in-phase to the bending oscillation.