bluuebunny/crossref_metadata_2025_split huggingface dataset:
Efficiency of Air-Purged Rotor-Stator Seals in Combustion Turbine Engines
Authors: Reichert A. W. , Lieser D. 
Published: December 2014

Although the efficiency of air-purged rotor seals has been the subject of a number of different tests, and the results of these tests are available in the literature. Only a small number of tests actually also modeled the influence of the blading. Consideration of this influence is essential for combustion turbine applications.
Furthermore, the methods chosen for presenting experimental data on the influence of the blading differ from each other, and although the sealing efficiency is correlated to different parameters, the connection to the physical phenomena causing the hot gas ingestion into rotor-stator cavities does not become clear.
The objective of this paper is to improve this situation. The available experimental data are reviewed, and the given correlations for the sealing efficiency are discussed. Universally applicable parameters for the correlation of the sealing efficiency are recommended, and validity limits for this recommendation are discussed.
Computations of Flow and Heat Transfer in a Channel With Rows of Hemispherical Cavities
Authors: Lin Y.-L. , Shih T. I-P. , Chyu M. K. 
Published: December 2014

Computations were performed to investigate the three-dimensional flow and heat transfer in a high aspect ratio channel in which one or two wall are lined with four rows of hemispherical cavities arranged in a staggered fashion with two Reynolds numbers (23,000 and 46,000). The focus is on understanding the flow induced by cavities and how that flow affects surface heat transfer. Computed results were compared with available experimental data.
This computational study is based on the ensemble-averaged conservation equations of mass, momentum (compressible Navier-Stokes), and energy closed by the low Reynolds number shear-stress transport k-ω turbulence model (wall functions were not used). Solutions were generated by a cell-centered finite-volume method that uses third-order accurate flux-difference splitting of Roe with limiters, multigrid acceleration of a diagonalized ADI scheme with local time stepping, and patched/overlapped structured grids.
CFD Liquid Spray Combustion Analysis of a Single Annular Gas Turbine Combustor
Authors: Smiljanovski Vanco , Brehm Norbert 
Published: December 2014

In this paper CFD analysis of the steady two-phase turbulent combusting flow in a single annular low-NOx combustor is presented. For this purpose the commercial code CFD-ACE (1998) was used, where Eulerian equations are solved for the gas phase and the liquid spray fuel droplets are treated in a Lagrangian frame of reference allowing for evaporation of droplets and providing source terms for the gas phase. The standard k-ε model was used for turbulence and an assumed shape probability density function was used for the instantaneous chemistry in the conserved scalar combustion model. Thermal NOx is assumed to be the only source of NOx production and is decoupled from the gas phase reacting flow and calculated in a postprocessing step. The calculation is done on a block structured multi-domain computational grid. Particular attention has be paid to the detailed modeling of the fuel injector having multiple air swirler passages starting from the trailing edge of the air swirler vanes and utilizing up to 400000 computational grid cells for the entire model.
The model represents the single annular low-NOx combustor for the BR700 aircraft engine family, which is based on a Rich Burn - Quick Quench - Lean Burn (RQL) concept. CFD analysis is done for high power reduced take off conditions and is compared with full annular rig test results for the temperature traverse and the integral EINOx. The results imply satisfactory prediction capability for the EINOx and the average radial temperature distribution. The prediction of the details of the temperature traverse is not satisfactory and will remain a challenge for the future.
Real-Time Monitoring of Bearing Condition
Authors: Taylor Barry 
Published: December 2014

Magnetic chip detectors, vibration monitoring devices, and spectrographic oil analysis typically do not detect bearing distress until the bearing is in the latter stages of failure. Now, through the innovation of digital signal processing technology and a breakthrough in inductive sensors, it is possible to provide several months of advance notice on a bearing failure.
Unlike magnetic chip detectors, this technology has the capability to track the shedding of both magnetic and nonmagnetic debris from the bearing. It is a true prognostic sensor that detects the first indications of a bearing spall and continues to track, in real-time, the quantities of wear debris being generated by the bearing. The data collected from the sensor can be changed into information such that with a particle trend graph it can clearly be seen when the bearing should be taken out of service prior to a turbine failure and the possibility of expensive secondary damage.
A New Probabilistic Approach for Accurate Fatigue Data Analysis of Ceramic Materials
Authors: Schenk Bjoern , Brehm Peggy J. , Menon M. N. , Tucker William T. , Peralta Alonso D. 
Published: December 2014

Statistical methods for the design of ceramic components for time-dependent failure modes have been developed which can significantly enhance component reliability, reduce baseline data generation costs, and lead to more accurate estimates of slow crack growth (SCG) parameters. These methods are incorporated into the AlliedSignal Engines CERAMIC and ERICA computer codes. Use of the codes facilitates generation of material strength parameters and SCG parameters simultaneously, by pooling fast fracture data from specimens that are of different sizes, or stressed by different loading conditions, with data derived from static fatigue experiments. The codes also include approaches to calculation of confidence bounds for the Weibull and SCG parameters of censored data and for the predicted reliability of ceramic components.
This paper presents a summary of this new fatigue data analysis technique and an example demonstrating the capabilities of the codes with respect to time-dependent failure modes. This work was sponsored by the U.S. Department of Energy Oak Ridge National Laboratory (DoE/ORNL) under Contract No. DE-AC05-84OR21400.
Non-Axisymmetric Turbine End Wall Design: Part I — Three-Dimensional Linear Design System
Authors: Harvey Neil W. , Rose Martin G. , Taylor Mark D. , Shahpar Shahrokh , Hartland Jonathan , Gregory-Smith David G. 
Published: December 2014

A linear design system, already in use for the forward and inverse design of three-dimensional turbine aerofoils, has been extended for the design of their end walls.
This paper shows how this method has been applied to the design of a non-axisymmetric end wall for a turbine rotor blade in linear cascade. The calculations show that non-axisymmetric end wall profiling is a powerful tool for reducing secondary flows, in particular the secondary kinetic energy and exit angle deviations. Simple end wall profiling is shown to be at least as beneficial aerodynamically as the now standard techniques of differentially skewing aerofoil sections up the span, and (compound) leaning of the aerofoil. A design is presented which combines a number of end wall features aimed at reducing secondary loss and flow deviation. The experimental study of this geometry, aimed at validating the design method, is the subject of the second part of this paper.
The effects of end wall perturbations on the flow field are calculated using a 3-D pressure correction based Reynolds Averaged Navier-Stokes CFD code. These calculations are normally performed overnight on a cluster of work stations. The design system then calculates the relationships between perturbations in the end wall and resulting changes in the flow field. With these available, linear superposition theory is used to enable the designer to investigate quickly the effect on the flow field of many combinations of end wall shapes (a matter of minutes for each shape).
Non-Axisymmetric Turbine End Wall Design: Part II — Experimental Validation
Authors: Hartland J. C. , Gregory-Smith D. G. , Harvey N. W. , Rose M. G. 
Published: December 2014

The Durham Linear Cascade has been redesigned with the non-axisymmetric profiled end wall described in the first part of this paper, with the aim of reducing the effects of secondary flow. The design intent was to reduce the passage vortex strength and to produce a more uniform exit flow angle profile in the radial direction with less over turning at the wall. The new end wall has been tested in the linear cascade and a comprehensive set of measurements taken. These include traverses of the flow field at a number of axial planes and surface static pressure distributions on the end wall. Detailed comparisons have been made with the CFD design predictions, and also for the results with a planar end wall. In this way an improved understanding of the effects of end wall profiling has been obtained.
The experimental results generally agree with the design predictions, showing a reduction in the strength of the secondary flow at the exit and a more uniform flow angle profile. In a turbine stage these effects would be expected to improve the performance of any downstream blade row. There is also a reduction in the overall loss, which was not given by the CFD design predictions. Areas where there are discrepancies between the CFD calculations and measurement are likely to be due to the turbulence model used.
Conclusions for how the three-dimensional linear design system should be used to define end wall geometries for improved turbine performance are presented.
Power Systems Development Facility: High Temperature, High Pressure Filter System Operations in a Combustion Gas
Authors: Scarborough Patrick T. , Hendrix Howard L. , Davidson Matt. D. , Guan Xiaofeng , Dahlin Robert S. , Landham E. Carl 
Published: December 2014

The Power Systems Development Facility (PSDF) is a Department of Energy (DOE) sponsored engineering scale demonstration of two advanced coal-fired power systems. Particulate cleanup is achieved by several High Temperature, High Pressure (HTHP) gas filtration systems. The PSDF was designed at sufficient scale so that advanced power systems and components could be tested in an integrated fashion to provide confidence and data for commercial scale-up. This paper provides an operations summary of a Siemens-Westinghouse Particulate Control Device (PCD) filtering combustion gas from a Kellogg Brown & Root (KBR) transport reactor located at the PSDF.
The transport reactor is an advanced circulating fluidized bed reactor designed to operate as either a combustor or a gasifier. Particulate cleanup is achieved by using one of two PCDs, located downstream of the transport reactor. As of the end of 1998, the transport reactor has operated on coal as a combustor for over 3500 hours. To date, filter elements from 3M, Blasch, Coors, Allied Signal (DuPont), IF&P, McDermott, Pall, Schumacher and Specific Surface have been tested up to 1400°F in the Siemens-Westinghouse PCD.
The PSDF has a unique capability for the collection of samples of suspended dust entering and exiting the PCD with Southern Research Institute’s (SRI) in-situ particulate sampling systems. These systems have operated successfully and have proven to be invaluable assets. Isokinetic samples using a batch sampler, a cascade impactor and a cyclone manifold have provided valuable data to support the operation of the transport reactor and the PCD. Southern Research Institute has also supported the PSDF by conducting filter element material testing.
Intake Engine Interactions of a Modern Large Turbofan Engine
Authors: Freeman Chris , Rowe Arthur L. 
Published: December 2014

An engine experiment has been carried out to investigate Fan Stability and response to ambient wind conditions during static high power running of a modern large turbofan engine. This paper describes the experiment and the conclusions.
Intermittently the inlet would separate and drive the fan into stall from which it did not recover when the inlet cleared up: on high working lines one inlet separation could stall the fan; on lower working lines the inlet separation / fan flow / bypass duct pressure would develop a divergent 10Hz oscillation which could eventually stall the fan. The interaction of the stalled fan with the turbine and mixed nozzle would then raise the fan running line above the stall dropout level thus locking the fan into stall even when the inlet cleared up. A one dimensional dynamic model of the engine was created that would exhibit similar behaviour to the engine when a delay was introduced between the inlet loss and fan face loss. The engine never showed steady operation with the inlet separated.
Model Combustor to Assess the Oxidation Behavior of Ceramic Materials Under Real Engine Conditions
Authors: Filsinger D. , Schulz A. , Wittig S. , Taut C. , Klemm H. , Wötting G. 
Published: December 2014

A further increase of thermal efficiency and a reduction of the exhaust emissions of ground based gas turbines can be achieved by introducing new high temperature resistant materials. Therfore, ceramics are under international development. They offer excellent strengths at room and elevated temperatures. For gas turbine combustor applications, however, these materials have to maintain their advantageous properties under hostile environment. For the assessment and comparison of the oxidation behavior of different nonoxide ceramic materials a test rig was developed at the Institute for Thermal Turbomachinery (ITS), University of Karlsruhe, Germany.
The test rig was integrated into the high temperature/ high pressure laboratory. A ceramic model combustion chamber was designed which allowed the exposure of standard four-point flexure specimens to the hot combustion gas flow. Gas temperatures and pressures could be varied in a wide range. Additionally, the partial steam pressure could be adjusted to real combustor conditions.
The present paper gives a detailed description of the test rig and presents results of 100 hours endurance tests of ceramic materials at 1400°C. The initial strengths and the strengths after oxidation tests are compared. In addition to this, photographs illustrating the changes of the material’s microstructure are presented.
Pneumatic Fuel Feeding of a Directly Wood Particle Fired Gas Turbine Under Special Consideration of Low Conveying Air Ratio
Authors: Joppich Andreas , Haselbacher Hermann 
Published: December 2014

In order to reduce the production of green house gases, the combustion of biomass has been gaining importance in electricity generation. Especially the direct combustion of biomass in gas turbines of a few MW output would offer a very attractive option because of low investment costs and high operational flexibility. Therefore, since 1991 the Institute of Thermal Turbomachines and Powerplants at the Vienna University of Technology has been working on realising a wood particle fired gas turbine with direct combustion. With reference to earlier studies (c.f. Hamrick (1991), Fredriksson and Kallner (1993)), it had been concluded that the design and the operating characteristics of the fuel feed system would strongly influence the combustion and so would be a very important part of the whole facility.
Following an overview of the planned gas turbine test facility including the combustion chamber and the recently installed pneumatic fuel feed system, the paper will deal with three basic requirements of fuel feeding in the case of a directly fired gas turbine: feeding against back pressure, continuous fuel flow rate and a low conveying air ratio, which is the ratio of fuel conveying air to total combustion air of the combustion chamber. While the first two requirements, i.e. feeding against back pressure and continuous feeding, are briefly considered, the minimisation of the conveying air ratio is discussed in detail. For instance, important parameters affecting the conveying air ratio are fuel moisture, combustion air ratio and, in particular, techniques. Following theoretical estimation of the conveying air ratio, results of fuel feeding measurements are presented and conclusions drawn with respect to system integration.
Boundary Conditions for Ceramic Turbine Components: Analytical Prediction and Test Validation
Authors: Bagheri Hamid , Jimenez Oscar 
Published: December 2014

Ceramics allow gas turbine engines to run at higher temperatures to increase power and efficiency. Ceramic component development is therefore required to understand transient thermal behavior and temperature distributions. As a part of contract with US Department of Energy (DOE), a series of finite element analyses were completed and a Solar Turbine (Solar) Centaur 50S engine was tested to characterize this behavior.
To better understand the interaction between the metallic and ceramic components during engine operation, a finite element model was prepared. The boundary conditions for this model were estimated analytically or using existing test data. To verify the boundary conditions in the vicinity of uncooled ceramic components, two engine tests were performed on a metallic engine simulating the ceramic engine configuration.
The Solar Centaur 50S engine normally operates at 1010°C with all metallic components. A Centaur 50S eagine was retrofitted with a ceramic combustor liner and uncooled first stage turbine blades and nozzles. Two tests were conducted at firing temperatures of 1095 and 980°C. Using metallic components saved time, reduced the complexity of working with ceramic components, and eliminated some of the difficulties of attaching instrumentation to ceramic parts. Component temperatures were measured and used in the finite element analyses to help predict blade tip clearances, ceramic component temperatures, stresses and ultimately component lives.
The strategy undertaken and results presented herein provided a reliable and effective approach to ceramic component development and provides critical temperature information in the qualification process for ceramic gas turbines.
Optimization of a Vaned Diffuser Geometry for Radial Compressors: Part II — Optimization of a Diffuser Vane Profile in Low Solidity Diffusers
Authors: Kmecl Tomaz , ter Harkel Rudi , Dalbert Peter 
Published: December 2014

In addition to the diffuser parameter study described in part 1 of this paper the influence of diffuser vane profiles on the efficiency and the operating range of a low solidity diffuser has been studied. Ten different diffuser profiles with identical diffuser configuration (12 vanes, σ = 0.7) were numerically compared. Four of them were tested experimentally.
The basic diffuser for this investigation was a simple circular are profile of constant thickness with rounded leading and trailing edges. The simplest improvement of the basic diffuser was made with an elliptical leading edge. The ellipses of different k values (k = 2, 4, 8) were examined. In addition to circular are diffusers with constant thickness, six fully profiled diffusers with non-constant thickness along the camber line were investigated. Four of them are conformably transformed NACA profiles.
The results show that the diffuser vane profile does not influence the choke of a stage significantly. The choke point is predominantly influenced by the diffuser’s effective throat size, which was kept nearly constant for all investigated diffusers. Near surge the flow field is difficult to predict so that the optimization of a diffuser vane profile does not necessarily result in an improvement of the diffuser performance.
Systematic Reduction of Stress Levels for a Thermally High Loaded Ceramic Nozzle Vane With Trailing Edge Ejection
Authors: Dilzer M. , Schulz A. , Wittig S. 
Published: December 2014

This paper presents a design concept for thermally high loaded ceramic shell components, that is developed at the Institute for Thermal Turbomachinery (ITS, University of Karlsruhe). The aim is to obtain homogenous temperature distribution in the ceramic structure for the whole operating cycle of the engine.
Based on simple flat wall considerations design guidelines are introduced to reduce the dominant thermally induced stresses in ceramic components. The concept includes a systematic adjustment of the local cooling configuration and the local wall thicknesses according to the local thermal boundary conditions.
The concept is applied to increase the reliability of a directly cooled Sintered Silicon Carbide first stage nozzle vane with trailing edge ejection for a 70MW stationary gas turbine. Finite element analyses demonstrate that the application of this methodology leads to a rather uniform temperature distribution in the ceramic structure and therefore to low stress levels for steady state and for tripping conditions.
A transformation of the theoretically derived optimum cooling configuration to a technically feasible cooling setup is performed in the purpose of real engine application. It is found that some differences between optimum and technically feasible cooling configuration (mainly located at the trailing edge region) are of minor importance. The results of failure probability calculations (ITS fracture statistics code CERITS) confirm significantly improved reliability of the ceramic nozzle vane.
Wake Vorticity Decay and Blade Response in an Axial Compressor With Varying Axial Gap
Authors: Wo A. M. , Chung M. H. , Chang S. J. , Lee S. F. 
Published: December 2014

This paper addresses the decay of rotor wake vorticity for a rotor/stator axial compressor, with the axial gap between blade rows being 10, 20 and 30 percent chord, and at both design and high loading levels. Experiments were conducted in a large-scale, low-speed axial compressor. Navier-Stokes calculations were also executed.
Both data and Navier-Stokes results reveal that the decay of rotor wake vorticity increases substantially as the axial gap decreases; the decay for 10 percent gap is about twice that of 30 percent. Increased time-mean blade loading causes the vorticity decay to also increase, with this effect more pronounced for large axial gap than small. At the stator inlet mid-pitch location, the wake maximum vorticity for 10 and 30 percent chord gap cases being nearly the same (differ by 3.8%) at design loading. The corresponding stator unsteady force agrees within 5.2%. Variation of vorticity decay with axial gap is directly linked to the change in potential disturbance by the downstream stator on the rotor wake due to the change in gap spacing. This suggests that the stator potential disturbance causes the upstream rotor wake to decay at an increased rate which, in turns, results in a lowered level of stator response compared to that without this stator/wake interaction effect. Thus, in this context, blade row interaction is considered beneficial.