bluuebunny/crossref_metadata_2025 huggingface dataset:
Prediction of Nonuniform Inlet Temperature Effects on Vane and Rotor Heat Transfer
Authors: Boyle R. J. , Giel P. W.
Published: December 2014

The effects of nonuniform combustor exit temperature profiles on vane and rotor heat transfer were determined using a steady-state three-dimensional Navier-Stokes analysis. Both radial and tangential nonuniform temperature profiles were individually considered. Comparisons are made with experimental data for the effects of a radial temperature nonuniformity on rotor heat transfer. There was a decrease in stator heat load, and an increase in rotor heat load for a radial temperature distribution typically seen at the combustor exit. Tangential variations in stator inlet temperature produced significant variations in stator heat load, and resulted in average rotor heat load greater than for the uniform inlet temperature case. Rotor heat load was also calculated for different stator wake locations. Accounting for the stator wake position at the rotor inlet gave a greater average rotor heat load than that obtained by averaging the stator exit flow field in the tangential direction. The increase was most notable on the rotor pressure surface.
Separate and Combined Effects of Surface Roughness and Turbulence Intensity on Vane Heat Transfer
Authors: Bunker Ronald S.
Published: December 2014

A research and development program has been undertaken to ascertain the effects of surface roughness levels on vane external heat transfer, with varied conditions of inlet freestream turbulence intensity and vane Reynolds number. A transonic linear vane cascade was constructed to operate at a nominal overall pressure ratio of 1.86. Airfoil heat transfer distributions are measured using a thin-walled stainless steel airfoil having imbedded thermocouples. The methodology incorporates a thin-foil surface heater to provide a known heat flux condition, with room temperature mainstream air at approximately 5 atm pressure. Heat transfer is characterized for uniform surface average roughness levels of 0.4, 1.85, and 4.5 micrometers, with inlet turbulence intensity levels from 4 to 13%. Airfoil Reynolds number based on axial chord length and exit velocity ranges from 2.2 to 4.8 · 106. Results show consistent individual and combined effects of Reynolds number, turbulence, and surface roughness changes. Higher roughness levels tend to dominate turbulence effects in most regions except the leading edge.
A Three Step NOx Reduction Programme: Achievements With the Single Annular Low-NOx Combustor for the BR 700 Engine Family
Authors: Brehm Norbert , Baker Stephen J. , Jones Steven P.
Published: December 2014

The social responsibility for the environment, in conjunction with the threat of more stringent emissions regulations requirements, initiated a comprehensive NOx-emissions reduction programme in BMW Rolls-Royce. The achievements of the first step for NOx-emissions reduction by optimisation of the single annular combustor stoichiometry and mixing are presented. The combustor development programme is described, and rig and engine test results are compared. The NOx-certification levels achieved with the BR 710 single annular low NOx-combustor are down to 55 % of the actual ICAO limit.
Experimental Investigation of an Atmospheric Rectangular Rich Quench Lean Combustor Sector for Aeroengines
Authors: Griebel Peter , Fischer Michael , Hassa Christoph , Magens Eggert , Nannen Henning , Winandy Adolf , Chrysostomou Antigoni , Meier Ulrich , Stricker Winfried
Published: December 2014

In this research work the potential of rich quench lean combustion for low emission aeroengines is investigated in a rectangular atmospheric sector, representing a segment of an annular combustor. For a constant design point (cruise) the mixing process and the NOx formation are studied in detail by concentration, temperature and velocity measurements using intrusive and non-intrusive measuring techniques.

Measurements at the exit of the homogeneous primary zone show relatively high levels of non-thermal NO. The NOx formation in the quench zone is very low due to the quick mixing of the secondary air achieved by an adequate penetration of the secondary air jets and a high turbulence level. The NOx and CO emissions at the combustor exit are low and the pattern factor of the temperature distribution is sufficient.
Soot Predictions Within an Aero Gas Turbine Combustion Chamber
Authors: Brocklehurst H. T. , Priddin C. H. , Moss J. B.
Published: December 2014

This paper presents two different soot production models and their predictions in a practical combustion chamber. These predictions are compared with detailed internal measurements of soot concentration by probe sampling. Both models solve two additional transport equations for soot mass concentration and number density, and incorporate representations of source terms for particle nucleation, surface growth, coagulation and oxidation. In one approach these rates are inferred from soot property measurements in a confined turbulent jet flame, and in the other from a flamelet-based approach employing computations of a kerosene laminar counter-flow flame which incorporates detailed reaction kinetics. Preliminary results from both models are encouraging. Although both over predict the peak levels of soot measured in a gas turbine combustor at 7 bar, these computations have neglected the effects of radiation, which will be included in subsequent calculations. The approach based on detailed chemistry captures more accurately the very high rate of oxidation towards the combustor exit which is a pronounced feature of the measurements and is missing in earlier reported studies. This is related to differences in the coagulation model. Calibration of model parameters for the empirical model from simple experiments leads to exaggerated coagulation at the higher combustor temperatures, reduced soot number densities and under-estimates effective surface area for oxidation. The suitability of laminar flamelet counter-flow flames as a route to generating the soot production relationships necessary for combustor predictions are carefully reviewed in the light of strain rate and residence time effects on detailed hydrocarbon pyrolysis.
Soot Modeling in Gas Turbine Combustors
Authors: Tolpadi Anil K. , Danis Allen M. , Mongia Hukam C. , Lindstedt R. Peter
Published: December 2014

A method is presented for predicting soot in gas turbine combustors. A soot formation/oxidation model due to Fairweather et al [1992] has been employed. This model has been implemented in the CONCERT code which is a fully elliptic three-dimensional (3-D) body-fitted computational fluid dynamics (CFD) code based on pressure correction techniques. The combustion model used here is based on an assumed probability density function (PDF) parameterized by the mean and variance of the mixture fraction and a β-PDF shape. In the soot modeling, two additional transport equations corresponding to the soot mass fraction and the soot number density are solved. As an initial validation, calculations were performed in a simple propane jet diffusion flame for which experimental soot concentration measurements along the centerline and along the radius at various axial downstream stations were available from the literature. Soot predictions were compared with measured data which showed reasonable agreement. Next, soot predictions were made in a 3-D model of a CF6-80LEC engine single annular combustor over a range of operating pressures and temperatures. Although the fuel in the combustor is Jet-A, the soot computations assumed propane to be the surrogate fuel. To account for this fuel change, the soot production term was increased by a factor of 10X. In addition, the oxidation term was increased by a factor of 4X to account for uncertainties in the assumed collision frequencies. The soot model was also tested against two other combustors, a CF6-80C and a CFM56-5B. Comparison of the predicted scot concentrations with measured smoke numbers showed fairly good correlation within the range of the soot model parameters studied. More work has to be performed to address several modeling issues including sensitivity to oxidation rate coefficients and scalar diffusion.
Effect of Fuel/Air Ratio on Air Blast Simplex Nozzle Performance
Authors: Benjamin Michael A. , McDonell Vincent G. , Samuelsen G. Scott
Published: December 2014

The Air-Blast Simplex (ABS) nozzle may have significant mechanical design advantages when compared to Pure Air-Blast (PAB) designs, and attractive cost benefits. The major barrier to implementing ABS nozzles is spray collapse at high ambient pressures. The present study addresses this issue, and presents the results in a manner that is useful to the gas turbine combustor designer. The results reveal that spray collapse is not significant as long as the fuel-to-air mass ratio is maintained below about 0.3. The results also reveal two distinct curves for air effective area that are attributed to the presence or lack of flow separation in the vane/shroud assembly. In the case of the separated flow, a larger rate of decrease in effective area with increasing fuel air mass or momentum ratio is observed. These results help address ABS spray angle collapse at high pressure, and identify strategies that may adequately mitigate, or even eliminate, spray collapse in a suitably designed combustor.
An Experimental Study on Modeling of Fuel Atomization for Simulating the Idle Regime of a Gas Turbine Combustor by Atmospheric Testing
Authors: Han Yeoung Min , Yoon Min Soo , Seol Woo Seok , Lee Dae Sung , Yagodkin Victor I. , Jeung In Seuck
Published: December 2014

An experimental investigation is carried out on modeling of fuel atomization for the purpose of simulating the idle regime of a gas turbine combustor through atmospheric testing. If the simulation is successfully applied, it will significantly reduce the cost of testing. The simulation must sustain nearly the same fuel spray characteristics and the same aerodynamics at the exit of the frontal device. Air assisting through the main stage of a dual orifice fuel nozzle is employed to match the fuel spray characteristics. Optical diagnostic methods including flow visualization and Adaptive Phase/Doppler Velocimetry are used for the investigation of spray characteristics. Once the fuel spray characteristics are matched by air assisting, the combustor characteristics may then be matched by maintaining the loading parameter constant. The possibility of modeling with air assisting is shown and appropriate conditions for air assisting are found.
Experimental Assessment of Fiber Reinforced Ceramics for Combustor Walls
Authors: Filsinger D. , Münz S. , Schulz A. , Wittig S. , Andrees G.
Published: December 2014

Experimental and theoretical work concerning the application of ceramic components in small high temperature gas turbines has been performed for several years. The significance of some non-oxide ceramic materials for gas turbines in particular is based on their excellent high temperature properties. The application of ceramic materials allows an increase of the turbine inlet temperature resulting in higher efficiencies and a reduction of pollution emissions.

The inherent brittleness of monolithic ceramic materials can be virtually reduced by reinforcement with ceramic fibers leading to a quasi-ductile behavior. Unfortunately, some problems arise due to oxidation of these composite materials in the presence of hot gas flow containing oxygen.

At the Motoren- und Turbinen Union, München GmbH, comprehensive investigations including strength, oxidation, and thermal shock tests of several materials that seemed to be appropriate for combustor liner applications were undertaken. As a result, C/C, SiC/SiC, and two C/SiC-composites coated with SiC, as oxidation protection, were chosen for examination in a gas turbine combustion chamber.

To prove the suitability of these materials under real engine conditions, the fiber reinforced flame tubes were installed in a small gas turbine operating under varying conditions. The loading of the flame tubes was characterized by wall temperature measurements.

The materials showed different oxidation behavior when exposed to the hot gas flow. Inspection of the C/SiC-composites revealed debonding of the coatings. The C/C- and the SiC/SiC-materials withstood the tests with a maximum cumulated test duration of 90 hours without damage.
Ceramic Vane Demonstration in an Industrial Turbine
Authors: Wenglarz Richard A. , Calcuttawala Satish M. , Pope J. Edward
Published: December 2014

A U. S. Department of Energy (DOE) program with the Allison Engine Company will demonstrate ceramic vanes in an industrial turbine. First-stage ceramic vanes and their metallic mounts are to be designed, fabricated, and operated in a relatively short-term engine test (up to 50 hr). The ceramic vanes and mounts will then be retrofitted into an existing turbine for operation at a commercial site for an extended duration test (up to 8000 hr). The ceramic vanes and metallic mounts have been designed. Thermal and stress analyses of the vanes have calculated acceptable fast fracture stress levels and probabilities of survival exceeding 99.99% for turbine continuous power and emergency shutdown (thermal shock) conditions. The maximum calculated steady-state stress is 169 MPa (24.5 ksi) at a material temperature of 1182°C (2160°F). Consequently, currently available ceramics appear to provide acceptable fast fracture strengths for use in industrial turbines. Long-term materials tests will evaluate the life times and retained strength of ceramics at stress and temperature levels in the range calculated from the ceramic vane analyses. The results of these tests will support the decision on which vane material will be used in the long duration turbine demonstration. A successful demonstration could provide a basis for incorporating first-stage ceramic vanes into current generation industrial turbines and also the introduction of ceramic airfoils into downstream rows of future high temperature Advanced Turbine System (ATS) engines.
Development and Investigation of Ceramic Parts for Gas-Turbine Engines
Authors: Nozhnitsky Youry A. , Fedina Youlia A. , Rekin Anatoly D. , Petrov Nickolai I.
Published: December 2014

For years of time there have been conducted the investigations of gas-turbine engine parts made of carbon-carbon and ceramic materials.

This paper presents mainly the results of works done to create engine components of ceramic materials. There are given the investigation results on development of equipment and methods intended for use in determining the characteristics of heat-resistant non-metallic materials under ultra high temperature conditions. The unique tooling is developed to be used for conducting mechanical tests in different conditions (vacuum, protective medium, air) at temperatures up to 2200°C. There are considered three possible fields of application of ceramic materials, that are, turbine (1), combustion chamber and other stator components operating at high temperatures (2), bearings (3). Different ceramic elements are designed and manufactured, their structural strength is investigated in the laboratory faculties and also as part of engine gas generators.
The Design Modifications of the EGT Tornado Industrial Gas Turbine to Incorporate a Dry Low Emissions Combustion System
Authors: Gallimore Stephen , Vickers R. Michael , Boyns Michael B.
Published: December 2014

The Tornado gas turbine was designed at a time when emissions legislation was minimal and was developed through the eighties to accept water or steam injection for NOX reduction. In recent years it has become necessary to develop dry methods of emissions reduction for new engine sales and to enable existing operators to retrofit their engines when legislation demands.

The compact design of the Tornado’s centre section did not lend itself to a simple combustor changeout. The lean pre-mix dry low emissions (DLE) system developed for the Typhoon gas turbine required additional combustor length for CO burnout and could not be fitted into the existing casings of the Tornado engine. The challenge was therefore to redesign the centre section to enable the DLE system to be fitted without compromising the design of the compressor, HP turbine and gas generator rotor.

This paper describes the methodology used and the design of the engine centre section together with the results of design and performance validation undertaken including emissions measurements.
Mass/Heat Transfer in a Ribbed Blade Coolant Passage With Cylindrical Vortex Generators: The Effect of Generator-Rib Spacing
Authors: Hibbs Richard G. , Acharya Sumanta , Chen Yi , Nikitopoulos Dimitris E.
Published: December 2014

The effect of vortex-generators on the heat transfer from the internally ribbed passages of a turbine blade coolant channel is studied experimentally using a mass-transfer technique. Cylindrical vortex-generators placed directly above the ribs have been used in this study. Results are reported on the effect of the spacing between the vortex-generator and the ribs. Detailed distributions of the Sherwood number contours and the centerline Sherwood number distributions are presented. Three generator-rib-spacing/rib-height (s/e) values of 0.55, 1, and 1.5 are considered. It is shown that at small generator-rib spacings (s/e = 0.55), the two act as a single element, and lead to a retardation of the shear layer development past the reattachment point. This is generally associated with lower heat transfer. At a larger generator-rib spacing (s/e = 1.5), the generator-wake and the rib-shear-layer interact with each other to promote mixing and heat transfer.
Film-Cooling From Holes With Expanded Exits: A Comparison of Computational Results With Experiments
Authors: Giebert D. , Gritsch M. , Schulz A. , Wittig S.
Published: December 2014

A 3D Navier-Stokes code, together with the standard k-ϵ model with wall function approach, was used to investigate the flowfield in the vicinity of three different single scaled-up film-cooling holes. The hole geometries include a cylindrical hole, a hole with laterally expanded exit, and a hole with forward-laterally expanded exit.

Comparisons of numerical results with detailed flowfield measurements of mean velocity and turbulent quantities are presented for a blowing ratio and density ratio of unity. Additionally, experimental data for different blowing ratios and a density ratio of about two are taken to perform validation of the code for adiabatic film-cooling effectiveness prediction.

Results show that for both the round and the expanded hole geometries the code is able to capture all dominating flow structures of this jet in crossflow problem. However, discrepancies are found when comparing the flowfield inside the hole and at the hole exit. In particular, jet location at the hole exit differs significantly from measurement for the expanded hole geometries. For the adiabatic film-cooling effectiveness, it is shown that for round and expanded hole exits the intensity of the shear regions and the source of turbulence, respectively, have a strong influence on the predictive capability of the numerical code.
Adiabatic Wall Effectiveness Measurements of Film-Cooling Holes With Expanded Exits
Authors: Gritsch M. , Schulz A. , Wittig S.
Published: December 2014

This paper presents detailed measurements of the film-cooling effectiveness for three single, scaled-up film-cooling hole geometries. The hole geometries investigated include a cylindrical hole and two holes with a diffuser shaped exit portion (i.e. a fanshaped and a laidback fanshaped hole). The flow conditions considered are the crossflow Mach number at the hole entrance side (up to 0.6), the crossflow Mach number at the hole exit side (up to 1.2), and the blowing ratio (up to 2). The coolant-to-mainflow temperature ratio is kept constant at 0.54. The measurements are performed by means of an infrared camera system which provides a two-dimensional distribution of the film-cooling effectiveness in the nearfield of the cooling hole down to x/D = 10.

As compared to the cylindrical hole, both expanded holes show significantly improved thermal protection of the surface downstream of the ejection location, particularly at high blowing ratios. The laidback fanshaped hole provides a better lateral spreading of the ejected coolant than the fanshaped hole which leads to higher laterally averaged film-cooling effectiveness. Coolant passage crossflow Mach number and orientation strongly affect the flowfield of the jet being ejected from the hole and, therefore, have an important impact on film-cooling performance.
Discharge Coefficient Measurements of Film-Cooling Holes With Expanded Exits
Authors: Gritsch M. , Schulz A. , Wittig S.
Published: December 2014

This paper presents the discharge coefficients of three film-cooling hole geometries tested over a wide range of flow conditions. The hole geometries include a cylindrical hole and two holes with a diffuser shaped exit portion (i.e. a fanshaped and a laidback fanshaped hole). The flow conditions considered were the crossflow Mach number at the hole entrance side (up to 0.6), the crossflow Mach number at the hole exit side (up to 1.2), and the pressure ratio across the hole (up to 2).

The results show that the discharge coefficient for all geometries tested strongly depends on the flow conditions (crossflows at hole inlet and exit, and pressure ratio). The discharge coefficient of both expanded holes was found to be higher than of the cylindrical hole, particularly at low pressure ratios and with a hole entrance side crossflow applied. The effect of the additional layback on the discharge coefficient is negligible.
Simulation of the Dynamic Braking Process of Gas Turbine Propulsion System for a Ship
Authors: Shusheng Zang , Hongtao Zheng , Keyong Dong
Published: December 2014

Based on a ship driven by two controllable pitch propellers (CPP), one single CPP driven by one single gas turbine (GT), a mathematical model for a propulsion system is deduced, and its state-space model is established. In this paper, it is verified that the use of Phase-Linearized Discrete Simulation (PLDS) to estimate large perturbations is practicable. Especially for multivariate systems, this method appears to be rather convenient. We also present the results of simulation to the dynamic braking process of gas turbine propulsion system for a ship at the combined speed/power governing mode and the power governing mode of gas turbine.
Research Into the Drive Transition of Combined Diesel or Gas Turbine Plant
Authors: Shusheng Zang , Hongtao Zheng , Shuying Li , Haiou Sun
Published: December 2014

A small test installation of Combined Diesel or Gas turbine (CODOG) was made, its primary aimed at investigating the changes of various operational parameters of the two engines in the change-over process. First, the computer simulation of this process is carred out in the paper. Variations of torque and rotational speed on the transmission shafts under different rates of fuel supply and the effect of hydraulic coupling on the change-over process are investigated. Then, the comparison is made of variation of speed and torque by PI governing with that by PID governing. The result shows that the rate of increase or decrease of diesel engine fuel supply has significant effect on the variation of torque, and the change of parameters in governing system has markable effect on the speed and torque in change-over process, especially on the peake value of diesel engine torque.
A Small Gas Turbine Plant for Cogeneration of Electricity, Thermal and Cooling Thermal Energy With an Absorption Unit
Authors: De Lucia Maurizio , Lanfranchi Carlo , Matucci Antonio
Published: December 2014

A cogeneration plant with a small gas turbine was installed in a pharmaceutical factory and instrumented for acquiring all the values necessary to appraise both its energetic and cost advantages. The plant was designed and built as a demonstrative project under a program for energy use improvement in industry, partially financed by the European Union.

The system comprises as its main components: 1) a gas turbine cogeneration plant for production of power and thermal energy under the form of hot water, superheated water, and steam; 2) a two-stage absorption unit, fueled by the steam produced in the cogeneration plant, for production of cooling thermal energy.

The plant was provided with an automatized control system for the acquisition of plant operating parameters. The large amount of data thus provided made it possible to compare the new plant, under actual operating conditions, with the previously existing cooling power station with compression units, and with a traditional power plant.

This comparative analysis was based on measurements of the plant operating parameters over nine months, and made it possible to compare actual plant performance with that expected and ISO values. The analysis results reveal that gas turbine performance is greatly affected by part-load as well as ambient temperature conditions. Two-stage absorber performance, moreover, turned out to decrease sharply and more than expected in off-design operating conditions.
Comparison of Industrial Gas Turbine Transient Responses Performed by Different Dynamic Models
Authors: Peretto A. , Spina P. R.
Published: December 2014

In this paper, the transient responses of different dynamic models of a generator drive single shaft gas turbine working in parallel with electrical mains, have been analyzed.

The time variations of the main thermodynamic and performance parameters are obtained by varying the fuel valve position, for an assigned IGV angle, and by varying the IGV angle for an assigned fuel valve position.

The influence of the dynamic phenomena due to the working gas mass contained in the gas turbine component volumes, of the metal mass thermal inertia and of the heat transfers, are taken separately into account. The dynamic balance of rotating masses is not instead considered, since the single shaft gas turbine works in parallel with electrical mains.

The developed analysis has shown the negligible influence of the phenomena due to the working gas mass contained in the gas turbine component volumes and a more significative effect of the metal mass inertia and of the heat transfers on the transient response. In particular, this influence is significative only for gas turbine and compressor outlet temperatures.

The influence on the gas turbine transient behaviour of the control system that uses the gas turbine outlet temperature in feedback has been also evaluated.
Gas Turbine Exhaust Emissions Monitoring Using Non-Intrusive Infrared Spectroscopy
Authors: Hilton Moira , Lettington Alan H. , Wilson Chris W.
Published: December 2014

Infrared (IR) spectra of the exhaust emissions from a static gas turbine engine have been studied using Fourier Transform (FT) spectroscopic techniques. Passive detection of the infrared emission from remote (range ∼ 3 m) hot exhaust gases was obtained non-intrusively using a high spectral resolution (0.25 cm−1) FTIR spectrometer. Remote gas temperatures were determined from their emission spectra using the total radiant flux method or by analysis of rotational line structure. The HITRAN database of atmospheric species was used to model the emission from gas mixtures at the relevant temperatures.

The spatial distribution of molecular species across a section transverse to the exhaust plume −10 cm downstream of the jet pipe nozzle was studied using a tomographic reconstruction procedure. Spectra of the infrared emission from the plume were taken along a number of transverse lines of sight from the centreline of the engine outwards. A mathematical matrix inversion technique was applied to reconstruct the molecular concentrations of CO and CO2 in concentric regions about the centreline.

Quantitative measurements of the molecular species concentrations determined non-intrusively were compared with results from conventional extractive sampling techniques.
Detailed Film Cooling Measurements on a Cylindrical Leading Edge Model: Effect of Free-Stream Turbulence and Coolant Density
Authors: Ekkad Srinath V. , Han Je-Chin , Du Hui
Published: December 2014

Detailed heat transfer coefficient and film effectiveness distributions are presented on a cylindrical leading edge model using a transient liquid crystal technique. Tests were done in a low speed wind tunnel on a cylindrical model in a crossflow with two rows of injection holes. Mainstream Reynolds number based on the cylinder diameter was 100,900. The two rows of injection holes were located at ±15° from stagnation. The film holes were spaced 4-hole diameters apart and were angled 30° and 90° to the surface in the spanwise and streamwise directions, respectively. Heat transfer coefficient and film effectiveness distributions are presented on only one side of the front half of the cylinder. The cylinder surface is coated with a thin layer of thermochromic liquid crystals and a transient test is run to obtain the heat transfer coefficients and film effectiveness. Air and CO2 were used as coolant to simulate coolant-to-mainstream density ratio effect. The effect of coolant blowing ratio was studied for blowing ratios of 0.4, 0.8, and 12. Results show that Nusselt numbers downstream of injection increase with an increase in blowing ratio for both coolants. Air provides highest effectiveness at blowing ratio of 0.4 and CO2 provides highest effectiveness at a blowing ratio of 0.8. Higher density coolant (CO2) provides lower Nusselt numbers at all blowing ratios compared to lower density coolant (air). An increase in free-stream turbulence has very small effect on Nusselt numbers for both coolants. However, an increase in free-stream turbulence reduces film effectiveness significantly at low blowing ratios for both coolants.
An Analysis Method for Multistage Transonic Turbines With Coolant Mass Flow Addition
Authors: Mildner Frank , Gallus Heinz E.
Published: December 2014

The subject of this paper is a numerical method for the calculation of the transonic flow field of multistage turbines taking high coolant flow into account. To reduce the processing time, a throughflow method based on the principels of Wu is used for the hub-to-tip calculation. The flow field is obtained by an iterative solution between a three dimensional inviscid hyperbolic time-dependent algorithm with an implicit finite volume method for the blade-to-blade calculations using C-meshes and a single representative meridional S2m-stream surface. Along the S2m-plane with respect to non-orthogonal curvilinear coordinates, the stream function equation governing fluid flow is established. The cooling air inflow inside the blade passage forbids the assumption of a constant mass flow along the main stream direction. To consider the change of the aerodynamic and thermodynamic behaviour, a cooling air model was developed and implemented in the algorithm, which allows the mixing of radially arbitrarily distributed cooling air in the trailing edge section of each blade row. The viscous effects and the influence of cooling air mixing are considered by the use of selected loss correlations for profile-, tip leakage, secondary flow and mixing losses in the S2m-plane in terms of entropy. The method is applied to the four stage high temperature gas turbine Siemens KWU V84.3. The obtained numerical results are in good agreement with the experimental data.
A Test Facility for the Measurement of Torques at the Shaft to Seal Interface in Brush Seals
Authors: Wood P. E. , Jones T. V.
Published: December 2014

An important factor in the performance of brush seals for a wide range of gas turbine applications is the rate of wear at the seal to shaft interface, which is dependant on the contact pressure that exists between the bristles and rubbing surface. This is dependent on a variety of effects. Principally these are; the aerodynamic forces bending the bristles onto the rubbing surface; frictional effects within the bristle pack, and at the backing ring, that arise with the application of pressure differential; geometrical changes due to centrifugal and thermal growths and transient differential movements of the rotor that develop in flight manoeuvres.

In order to investigate the effect of these phenomena on contact pressure, a test facility has been devised in which the torque exerted by a brush seal on a rotating shaft is used as an indirect measurement of contact pressure. This has necessitated the design of a test facility in which all system torques can be fully calibrated. Consequently, a pressure balanced design has been adopted, in which applied seal differential and pressure levels have a minimal effect on axial loads at the rotor bearing assembly. The primary method of torque measurement is the instantaneous deceleration of the rotor. Thus measurements over a wide speed range are acquired with high frequency instrumentation. The means whereby small parasitic torques are evaluated and corrected is given. Results demonstrating the dependence of contact pressure on seal differential and pressure levels are presented.
Effects of Rotation on Blade Surface Heat Transfer: An Experimental Investigation
Authors: Moss Roger W. , Ainsworth Roger W. , Garside Tom
Published: December 2014

Measurements of turbine blade surface heat transfer in a transient rotor facility are compared with predictions and equivalent cascade data. The rotating measurements involved both forwards and reverse rotation (wake free) experiments.

The use of thin-film gauges in the Oxford Rotor Facility provides both time-mean heat transfer levels and the unsteady time history. The time-mean level is not significantly affected by turbulence in the wake; this contrasts with the cascade response to freestream turbulence and simulated wake passing.

Heat transfer predictions show the extent to which such phenomena are successfully modelled by a time-steady code. The accurate prediction of transition is seen to be crucial if useful predictions are to be obtained.
Improved Reliability of Bladed Disks due to Friction Dampers
Authors: Sextro Walter , Popp Karl , Wolter Ivo
Published: December 2014

Friction dampers are installed underneath the blade platforms to improve the reliability. Because of centrifugal forces the dampers are pressed onto the platforms. Due to dry friction and the relative motion between blades and dampers, energy is dissipated, which results in a reduction of blade vibration amplitudes.

The geometry of the contact is in many cases like a Hertzian line contact. A three-dimensional motion of the blades results in a two-dimensional motion of one contact line of the friction dampers in the contact plane. An experiment with one friction damper between two blades is used to verify the two-dimensional contact model including microslip.

By optimizing the friction dampers masses, the best damping effects are obtained.

Finally, different methods are shown to calculate the envelope of a three-dimensional response of a detuned bladed disk assembly (V84.3-4th-stage turbine blade) with friction dampers.
Non-Contact Vibration Measurements of Mistuned Coupled Blades
Authors: Schaber Ulrich
Published: December 2014

Most of the turbomachine manufacturers are using a non-contact measurement system to measure blade vibration by two probes located in the casing radially outside a blade row. All blades of a row can be observed by this system, therefore it may be considered to be an ideal solution for measuring the vibration response of mistuned blades which have quite different vibration levels from blade to blade in resonance conditions.

By a simple calculation model a non-contact blade vibration measurement was simulated. It was found that for mistuned coupled blades the non-contact measurement results show some deviations from the actual vibration amplitudes. Different mistuning conditions have been investigated by a parameter study to estimate the inherent measurement error of the non-contact principle. Measurements at a circumferentially coupled gas turbine blading performed by a non-contact system and by strain gauges did also show deviations in the results obtained by the two measurement methods.
Computation of Compressible Flow and Heat Transfer in a Rotating Duct With Inclined Ribs and a 180-Degree Bend
Authors: Stephens M. A. , Shih T. I-P.
Published: December 2014

Computations were performed to study the three-dimensional flow and heat transfer in a U-shaped duct of square cross section with and without ribs under rotating and staggered inclined ribs of rounded cross sections on the leading and trailing walls. Parameters investigated include: two rotation numbers (0, 0.24), two density ratios (0.13, 0.22), and smooth versus ribbed walls at a Reynolds number of 25,000 and an inlet Mach number of 0.05. For the conditions of the present study, rib-induced secondary flows were found to dominate over those induced by the Coriolis force in terms of flow pattern. This shifted tendency for flow separation induced by centrifugal buoyancy from the leading wall to the outer-side wall for radially outward flow. The secondary flows induced by the 180-degree bend were found to be comparable to that induced by the ribs, creating very complex interactions in flow and surface heat transfer characteristics. The computations are based on the ensemble-averaged conservation equations of mass, momentum (compressible Navier-Stokes), and energy closed by a low Reynolds number k-ω model of turbulence. Solutions were generated by using a cell-centered finite-volume method based on flux-difference splitting and a diagonalized alternating-direction implicit scheme with multigrid.
Allison Advanced Turbine Systems (ATS) Engine Cycle
Authors: Halsey Jack E. , Warns Richard J. , Weisbrod William D.
Published: December 2014

An advanced, simple cycle, gas turbine engine under development will offer revolutionary improvements in simple cycle efficiency, emissions, and the cost of electricity. Overall thermal efficiencies from 38 to 40+% are projected over a 4 to 14 megawatt (MW) power range through the application of industry leading aerodynamics, turbine cooling, and material/manufacturing technologies. This family of engines will be identified as the Allison Model 701-K series. Aggressive compressor pressure ratios and firing temperatures equal to the most advanced, commercially available aero engines, will be used to reach this level of performance. This cycle efficiency is complemented by revolutionary advancements in dry low emission combustion technology that support the demands of future emission regulations.

The initial engine design and development effort is being accomplished under a cooperative agreement between the U.S. Department of Energy (DOE), Allison Engine Company, and multiple industry partners. This paper outlines the path to selecting the ATS engine cycle and general arrangement, the types of technologies required, and their application to the engine. An overview of the engine development program, including component rig and engine tests, and program status are presented. Program plans to evolve the ATS into a family of advanced industrial engines are also outlined.
Blade Fault Recognition Based on Signal Processing and Adaptive Fluid Dynamic Modelling
Authors: Stamatis A. , Aretakis N. , Mathioudakis K.
Published: December 2014

An approach for identification of faults in blades of a gas turbine, based on physical modelling is presented. A measured quantity is used as an input and the deformed blading configuration is produced as an output. This is achieved without using any kind of “signature”, as is customary in diagnostic procedures for this kind of faults. A fluid dynamic model is used in a manner similar to what is known as “inverse design methods”: the solid boundaries which produce a certain flow field are calculated by prescribing this flow field. In the present case a signal, corresponding to the pressure variation on the blade-to-blade plane, is measured. The blade cascade geometry that has produced this signal is then produced by the method. In the paper the method is described and applications to test cases are presented. The test cases include theoretically produced faults as well as experimental cases, where actual measurement data are shown to produce the geometrical deformations which existed in the test engine.
High Temperature Proximity Measurement in Aero and Industrial Turbomachinery
Authors: Sheard A. G. , O’Donnell S. G. , Stringfellow J. F.
Published: December 2014

The measurement of disc and shaft displacement has been performed for many years as part of the development, commissioning and monitoring of all classes of turbomachinery. This measurement has traditionally been performed using sensors that can not operate above the curie point of rare earth magnets.

In this paper a programme of work is described that was undertaken to develop a measurement system that could make a measurement of target proximity in a high temperature environment. The specific objectives were firstly to make possible the measurement of turbine disc axial movement and shaft motion in the engine core, close to the combustion chamber or turbine; and secondly to make possible the measurement of tip clearance over shrouded turbine rotors.
Transient Performance Analysis of a Two Spool Turbofan for Lifing and Handling Purposes
Authors: Kotsiopoulos Petros , Pilidis Pericles , Adamopoulos Dimitrios
Published: December 2014

The handling of a gas turbine and its life usage are closely related. As the handling capability required from an engine increases so does the life consumption. Faster transients and response require higher temperature levels, this reduces component lives. The phenomenon investigated here is thermal fatigue and the main focus is in the hot section of the engine, specifically the turbine blades.

To make a quantitative assessment of the reduction of life due to the requirement of a faster transient response a simulation code of a two spool turbofan engine has been developed. It has a routine that estimates the High Pressure Turbine blade metal temperature. This temperature has been used to estimate the reduction of life loss when fast shaft accelerations are required.

The main conclusion of this work is that, as expected, fast transients consume life faster. The present investigations suggest a quantitative level of thermal life reduction of approximately twenty five to thirty percent when comparing a fast acceleration of two to three seconds with a slower one of eight to ten seconds.
Turbochargers to Small Gas Turbines?
Authors: Rodgers Colin
Published: December 2014

The evolutionary development of the small turbocharger with a single stage centrifugal compressor and single stage radial inflow turbine has in the past four decades resulted in a finely honed turbomachinery accessory fully satisfying both thermodynamic and economic constraints. Its similarity to the small radial type of gas turbine auxiliary power unit has enamored many past efforts to adapt its associated aerothermodynamic features and low manufacturing cost attributes into various gas turbine configurations. This paper examines the viability of these efforts in attempting to achieve lower cost small gas turbines, versus those more specially developed, albeit expensive units, already being marketed by small gas turbine manufacturers.
Development in the Full Assembly Test Rig of the 100kW Automotive Ceramic Gas Turbine
Authors: Nakazawa Norio , Ogita Hiroshi , Takahashi Masayuki , Kawaguchi Yoshihiro
Published: December 2014

“Development of 100kW Automotive Ceramic Gas Turbine (CGT)” is a seven-year program started in fiscal 1990. Subsidized by the Agency of Natural Resources and Energy, the Ministry of International Trade and Industry, this program is being carried forward by the Petroleum Energy Center (PEC) and is aimed at the following goals;

- Maximum Output Power: 100kW

- Maximum Thermal Efficiency: 40% [Turbine Inlet Gas Temperature (TIT): 1350°C]

- Emission Characteristics: Conformity to regulations for gasoline-fueled passenger cars.
Measurements of Aerodynamic Wall Shear Stress With Heated Thin Film Gauges
Authors: Davies M. R. D. , Fitzgerald J. E. , Duffy J. T. , O’Donnell F. K.
Published: December 2014

Previous publications have demonstrated the method of heated thin film gauge aerodynamic wall shear stress calibration in a laminar flow with a favourable free stream pressure gradient. Further evidence, derived from calibrating a gauge in laminar pipe flow and flow over a wedge, supports both the format of the calibrating equation and the value of the calibration constants. The pipe flow calibration is extended into turbulent flow and it is shown that the format of the calibrating equatinn remains unchanged whilst the value of the first constant changes markedly. The calibration constants are applicable to any such gauges mounted on an aluminium substrate in air flow operated at the same overheat temperature. The calibration constants are then applied to allow measurement of the wall shear stress in a low pressure gradient region of the suction surface of a linear cascade turbine blade. Finally, these measurements are compared favourably with those taken from a calibrated Preston tube mounted on the same blade.
Metallurgical Analysis of Temperature Monitored Gas Turbine Blades
Authors: Rooth Rudy A. , Agema Klaas S. , Hiemstra Wiebren
Published: December 2014

A thorough visual inspection and metallurgical analysis of the gamma prime microstructure of GE Frame 6 first row blades has been performed after they were taken out of service. During the last few years of their service life these blades have been temperature monitored using a radiation thermometry system. The monitoring program included the registration of blade temperature profiles as well as temperature transients during start-up and shutdown. The temperature data were correlated to other gas turbine parameters. This radiation thermometry system revealed significant temperature differences between blades (up to 27°C). Accurate spatial information has been obtained using a high-resolution radiation thermometer having a spot size of 1.2 mm and 1.8 MHz electronic bandwidth. There is a clear relation between the observed blade temperatures and the degradation of the material structure. The results clearly show the capabilities of radiation thermometry in indicating blades with potential problems with respect to creep.
Loss Prediction for Rotating Passages in Secondary Air Systems
Authors: Reichert A. W. , Brillert D. , Simon H.
Published: December 2014

Modern heavy duty gas turbines operate with high turbine inlet temperatures, and thus require a complex secondary air system to ensure that the blades and vanes are supplied with the required amount of cooling air. Gas turbines with high thermal efficiency and with low emissions require minimum amounts of cooling and sealing air which means that the design of the secondary air system must be extremely accurate.

A previous paper introduced the secondary air system for the new Siemens Vx4.3A gas turbines and the calculation method used for its design. This paper deals with the detailed calculation of flow field losses in cooling air passages in rotating disks (rotating passages). The paper starts with a brief review of the work on this topic described in the literature and then presents a consistent model for the prediction of the flow field losses in rotating passages of different lengths and with varying upstream swirl. Particularly short passages with developing flow at the passage exit can he calculated using this model. The calculation system is completed by matching the correlations to experimental data.