bluuebunny/crossref_metadata_2025_split huggingface dataset:
3-D Internal Flow and Conjugate Calculations of a Convective Cooled Turbine Blade With Serpentine-Shaped and Ribbed Channels
Authors: Bohn Dieter E. , Becker Volker J. , Kusterer Karsten A. , Otsuki Yokiu , Sugimoto Takao , Tanaka Ryozo 
Published: December 2014

Modern cooling configurations for turbine blades include complex serpentine-shaped cooling channel geometries for internal-forced convective cooling. The channels are ribbed in order to enhance the convective beat transfer. The design of such cooling configurations is within the power of modem CFD-codes with combined heat transfer analysis in solid body regions. One approach is the conjugate fluid flow and heat transfer solver, CHT-Flow, developed at the Institute of Steam and Gas Turbines, Aachen University of Technology. It takes into account of the mutual influences of internal and external fluid flow and heat transfer. The strategy of the procedure is based on a multi-block-technique and a direct coupling module for fluid flow regions and solid body regions.
The configuration under investigation in the present paper is based on a test design of a convective cooled turbine blade with serpentine-shaped cooling passages and cooling gas ejection at the blade tip and the trailing edge. The numerical investigations focus on secondary flow phenomena in the ducts and on the heat transfer analysis at the cooling channel walls. In the first part, the cooling channels are investigated with adiabatic smooth & ribbed walls. The calculations are carried out for the stationary and rotating configuration. Concerning the heat transfer analysis, the results of the ribbed configuration with a fixed thermal boundary condition at the walls in the stationary case are presented.
Furthermore, in order to demonstrate the capability of the conjugate method to work without thermal boundary conditions, the cooling configuration is calculated including the external blade flow and the blade walls with internal and external heat transfer under typical operation conditions of gas turbines. The numerical code is used to determine the blade surface temperatures.
Optimization of Rotor Disk Shape Considering Equalization of Residual Stress Distribution Around Central Hole
Authors: Sekihara M. , Machida T. 
Published: December 2014

A method for optimizing a rotor disk shape so that it equalizes the residual stress distribution around the central hole has been developed. The shape around the central hole is considered a variable, and it is changed in order to determine the optimum for reducing the equivalent stress of the central hole. As a result, the optimized shape that equalizes the residual stress distribution to within 23% variation was found.
Second, experiments with aluminum rotors verified the effectiveness of the optimized shape by measuring residual deformations and stresses. And it was confirmed that the measured residual deformations coincide with the calculated deformations well.
It is therefore possible to equalize the stresses on the surface in the central hole by adopting the optimized shape.
The Development of a New Experimental Facility for the Simulation of Civil Aircraft Engine Air-Intakes at High Reynolds Number
Authors: Murgatroyd Jeremy D. 
Published: December 2014

A unique wind tunnel based method for simulating the engine air intakes of civil aircraft at high Reynolds numbers is described. The method combines a newly developed test rig with the 8ft × 8ft subsonic / supersonic wind tunnel at DERA Bedford. Commissioning tests of the rig took place in November 1997.
Previous studies have shown that Reynolds number can have a significant effect on intake flow characteristics in certain flight regimes. One such regime is high incidence manoeuvre, such as the emergency pull-up, where engine performance may be seriously degraded by distorted airflow from the intake cowl. Common methods for artificially simulating increased Reynolds number, such as boundary layer transition fixing, are not practical for intake model tests due to the widely varying position of the attachment line on the cowl. Hence, for intake tests, there can be significant gains from testing at the highest available Reynolds number, preferably approaching the full-scale value.
The new DERA facility offers accurate and cost effective performance assessment of large-scale intake models at near full-scale Reynolds numbers, across a Mach number range of 0.37 to 0.7. Throat choked mass flows can be achieved at Reynolds numbers up to approximately 11 million based on a model highlight diameter of 0.4 m. Model incidence can be varied between −10° and +30° (with and without sideslip). It is believed that this range of test conditions cannot be matched elsewhere in the world, without the additional risk and expense imposed by full-scale flight testing.
This paper details the conceptual design of the rig and the principles behind its operation. Special mention is made of the innovative use of theoretically based methods to calibrate the rig in the absence of experimental equipment with sufficient flow capacity. These theoretical methods significantly reduced the development time and cost of the rig.
Design and Testing of CFCC Shroud and Combustor Components
Authors: Dean Anthony J. , Corman Gregory S. , Bagepalli Bharat , Luthra Krishan L. , DiMascio Paul S. , Orenstein Robert M. 
Published: December 2014

This paper presents initial results in the development and testing of SiC-based Continuous Fiber Ceramic Composites (CFCC) materials for combustor and stage 1 shroud components of large utility-class gas turbines. Use of CFCC’s for these components has the potential for increasing output power and thermal efficiency and reducing emissions.
First stage turbine shroud components were fabricated using five material systems including three SiC/SiC-Si systems made by silicon melt infiltration (MI), chemical vapor infiltrated (CVI) enhanced SiC-SiC and directed metal oxidation (DIMOX) Al2O3-SiC composite. A combustor liner was made of MI CFCC. Before and after testing the components were inspected by several NDE techniques including IR thermography, resonance testing and visual examination.
A novel, high pressure test rig was used to test four shroud components and a combustor liner simultaneously. Components were exposed to hot gas temperature of 1200°C at 12.5 bar in cyclic and steady-state tests. Cyclic testing simulated engine trip conditions with 200 flame-on, flame-off cycles. Steady state testing involved 100 hours of exposure at high temperature and pressure with hot combustion gases. At the conclusion of the first phase of testing there was visible damage to two pieces of one of the material systems. Destructive testing of the components following rig exposure showed little degradation to the MI composite materials. In summary, high pressure combustion rig testing of these components demonstrated excellent performance with little degradation among the material systems.
Numerical Simulation of Turbulent Premixed Combustion Using a Joint-PDF Approach Based on a Systematically Reduced Multi-Step Reaction Mechanism
Authors: Bohn Dieter E. , Lepers Joachim 
Published: December 2014

Based on the characteristics of turbulent combustion in lean-premix combustion chambers, this paper presents a combustion model which solves transport equations for six chemical species. The source terms are calculated by probability weighted integration of 35 elementary reaction rates. The model presented here does not include any adjustable parameters. Therefore, it is universal in its character for conditions of highly turbulent premixed lean to stoichiometric combustion.
The model is applicable to fuel compositions including methane, carbon monoxide, and hydrogen. The application is shown for a test case burning methane in lean-premixed mode.
Three-Dimensional Performance Prediction of Multistage Axial Flow Compressors With a Repeating Stage Model
Authors: Li Y. G. , Tourlidakis A. , Elder R. L. 
Published: December 2014

In this paper, a method for the performance prediction of multistage axial flow compressors through a steady, three-dimensional, multi-block Navier-Stokes solver is presented.
A repeating stage model has been developed aiming at the simplification of the required global aerodynamic boundary conditions for the simulation of the rear stages of multistage axial compressors where only mass flow rate and exit average static pressure are required. The stage inlet velocity distribution is fixed to be equal to the one calculated at the stage exit and the exit static pressure distribution is fixed to have the same shape to that at inlet but maintain its own average value. A mixing plane approach is used to exchange information between neighbouring blade rows which allows both radial and circumferential variations at both sides of the interface.
A pressure correction method with the standard k–ε turbulence model is used in combination with Stone’s two step procedure for the solution of the algebraic system of the discretised equations. A global iteration is carried out in order to establish the physical consistency between the blade rows.
A combination of two structured grid blocks for the rotor blade row, one for the main passage and a second for the modelling of the tip clearance, is used for a detailed representation of the leakage flows.
Computational results from two methods, the first by using the repeating stage model and the second by setting stage inlet velocity profile, are presented from the analysis of the third stage of the four-stage Cranfield Low Speed Research Compressor (LSRC). Good agreements with the experimental data are obtained in terms of total pressure, static pressure and velocity distributions at the inlet, exit and interface planes proving that the repeating stage model is a very economical and accurate alternative to the very expensive complete multistage simulations.
Nitrogen Oxide Reduction by Staged Combustion of Biomass Gas in Gas Turbines — A Modeling Study of the Effect of Mixing
Authors: Coda Zabetta Edgardo G. , Kilpinen Pia T. , Hupa Mikko M. , Leppälahti Jukka K. , Ståhl C. Krister O. , Cannon Michael F. , Nieminen Jorma J. 
Published: December 2014

Detailed chemical kinetic modeling has been used to study the reduction of nitrogen oxides at gas turbine (GT) combustor conditions. A gas from gasification of wood with air has been used as the fuel. An air-staged combustion technique has been adapted.
In our previous study a simple plug flow model was used to study the effects of pressure and temperature among others process variables. The air-fuel mixing was assumed perfect and instantaneous. Results showed the NOx reduction mainly affected by both pressure and temperature.
The aim of the present work is to establish the effect of air-fuel mixing delay on NOx predictions and to extrapolate indications options for GT. To model the mixing delay, a varying number of air sub-streams are mixed with the fuel gas during different time periods. Alternatively, a combination of a perfectly mixed zone followed by a plug flow zone is illustrated.
Results by any air-fuel mixing model show similar affect of process variables on NOx reduction. When a mixing delay is assumed instead of the instantaneous mixing the NOx reduction is enhanced, and only with delayed mixing NOx are affected by CH4.
Lower temperature and higher pressure in the GT-combustor can enhance the NOx reduction. Also air staging is an effective option: a 3 stages combustor designed for low mixing speed appear competitive compared to more complicate combustors. The fewer hydrocarbons in the gasification gas the high NOx reduction.
A Method for the Diagnosis of Gas Turbine Sensor Faults in Presence of Measurement Noise
Authors: Bettocchi R. , Spina P. R. 
Published: December 2014

This paper presents a method for the detection and isolation of single gas turbine sensor faults, in presence of model inaccuracy and measurement noise.
The method uses a fault matrix with a column-canonical structure (i.e., each matrix column having the same number of zeroes, but in different positions), in order to obtain the unambiguous fault isolation.
The fault matrix was obtained by using a number of ARX (Auto Regressive exogenous) MISO (Multi-Input/Single-Output) models equal to the number of measured gas turbine outputs, each model calculating an estimate of one measurable output as a function of other inputs or outputs measured on the machine.
Moreover, in order to reduce the threshold of fault detection and, therefore, the minimal detectable faults, digital filters were used, applied to the time series of data measured on the machine and computed by the models.
Finally, tests were performed in order to find the minimal sensor faults that can be detected and isolated.
Turbine Inlet Gas Temperature Sensor
Authors: Glasheen W. Michael , DeMilo Charles A. , Sivathanu Yudaya R. 
Published: December 2014

A practical turbine inlet gas temperature sensor (TIGTS) has been designed, fabricated and evaluated both numerically and experimentally. The sensor remotely measures the hot gas spectral radiation intensities at several discrete wavelengths and obtains the Planck-function weighted temperature of the optical path using a look-up-table.
A high temperature optical head collects the radiation intensities emitted by hot gases along a narrow path. The radiation is transmitted using optical fibers to a quadrant detector which measures the intensities at four discrete wavelengths within the spectral bands of water vapor and carbon dioxide. After analog signal processing, under microprocessor control, the signals are digitized. They are input to a look-up-table which was obtained with stochastically generated gas concentrations and temperatures in conjunction with the narrow-band radiation calculation model, RADCAL.
Ceramic Gas Turbine Technology Development
Authors: Schenk Bjoern 
Published: December 2014

AlliedSignal Engines is addressing the critical concerns that are slowing commercialization of structural ceramics in gas turbines. The 331-200[CT] auxiliary power unit (APU) test bed features ceramic first-stage nozzles and blades. Fabrication of ceramic components provides manufacturing process demonstration scale-up to the minimum levels needed for commercial viability. On-site endurance tests are demonstrating component reliability, and additional field testing in APUs onboard commercial aircraft and stationary industrial engines is planned.
Manufacturing scale-up activities showed significant progress during 1998. Subcontractors AlliedSignal Ceramic Components (Torrance, CA) and Kyocera Industrial Ceramics Corporation (Vancouver, WA) transitioned process refinements to full demonstration. Both suppliers achieved demonstration capability of ceramic nozzle production at the rate of 100 pieces/month. These suppliers are also developing fixed processes to fabricate ceramic integrally-bladed turbine rotor disks (“blisks”).
Ceramic design technology advanced, and 776 hours engine operational testing of a ceramic blisk were successfully completed. Ceramic turbine nozzles were readied for planned field demonstrations, with 2.213 hours of engine endurance testing completed. High-temperature ceramic material tests in the cyclic oxidation test rigs were initiated, to establish functional operating temperature limits for current silicon nitride materials in gas turbine environments.
This work was funded as part of the Turbine Engine Technologies Program by the U.S. Dept. of Energy Office of Transportation Technologies under Contract No. DE-AC02-96EE50454.
A Spread Sheet as a Tool in Turbomachinery Design
Authors: Engeda Abraham 
Published: December 2014

Despite great advances in computations, industry still relies on empirical based one dimensional design in turbomachinery.
In colleges and universities that offer turbomachinery education, even the one dimensional design becomes a very complex exercise unless the procedure is programmed. Due to lengthy calculations and iterations, simple solutions are not possible. Design exercises have therefore been limited in the classroom. But recent advances in powerful spreadsheets have opened a simple and fast way of performing turbomachinery design.
This paper describes a typical current compressor design challenge in industry and how a student deals with the design and analysis using a spreadsheet.
Underplatform Dampers for Turbine Blades: Theoretical Modelling, Analysis and Comparison With Experimental Data
Authors: Sanliturk Kenan Y. , Ewins David J. , Stanbridge Anthony B. 
Published: December 2014

This paper describes a theoretical model for analysing the dynamic characteristics of wedge-shaped underplatform dampers for turbine blades, with the objective that this model can be used to minimise the need for conducting expensive experiments for optimising such dampers. The theoretical model presented in the paper has several distinct features to achieve this objective including: (i) it makes use of experimentally-measured contact characteristics (hysteresis loops) for description of the basic contact behaviour of a given material combination with representative surface finish, (ii) the damper motion between the blade platform locations is determined according to the motion of the platforms, (iii) three-dimensional damper motion is included in the model, and (iv) normal load variation across the contact surfaces during vibration is included, thereby accommodating contact opening and closing during vibration.
A dedicated non-linear vibration analysis program has been developed for this study and predictions have been verified against experimental data obtained from two test rigs. Two cantilever beams were used to simulate turbine blades with real underplatform dampers in the first experiment. The second experiment comprised real turbine blades with real underplatform damper. Correlation of the predictions and the experimental results revealed that the analysis can predict (i) the optimum damping condition, (ii) the amount of response reduction and (iii) the natural frequency shift caused by friction dampers, all with acceptable accuracy. It has also been shown that the most commonly-used underplatform dampers in practice are prone to rolling motion, an effect which reduces the damping in certain modes of vibration usually described as the lower nodal diameter bladed-disc modes.
Friction Damper Optimisation: Simulation of Rainbow Tests
Authors: Sanliturk Kenan Y. , Ewins David J. , Elliott Robert , Green Jeff S. 
Published: December 2014

Friction dampers have been used to reduce turbine blade vibration levels for a considerable period of time. However, optimal design of these dampers has been quite difficult due both to a lack of adequate theoretical predictions and to difficulties in conducting reliable experiments. One of the difficulties of damper weight optimisation via the experimental route has been the inevitable effects of mistuning. Also, conducting separate experiments for different damper weights involves excessive cost. Therefore, current practice in the turbomachinery industry has been to conduct so-called ‘rainbow tests’ where friction dampers with different weights are placed between blades with a predefined configuration. However, it has been observed that some rainbow test results have been difficult to interpret and have been inconclusive for determining the optimum damper weight for a given bladed-disc assembly.
A new method of analysis — a combination of Harmonic Balance Method and structural modification approaches — is presented in this paper for the analysis of structures with friction interfaces and the method is applied to search for qualitative answers about the so-called ‘rainbow tests’ in turbomachinery applications. A simple lumped-parameter model of a bladed-disc model was used and different damper weights were modelled using friction elements with different characteristics. Resonance response levels were obtained for bladed discs with various numbers of blades under various engine-order excitations. It was found that rainbow tests, where friction dampers with different weights are used on the same bladed-disc assembly, can be used to find the optimum damper weight if the mode of vibration concerned has weak blade-to-blade coupling (the case where the disc is almost rigid and blades vibrate almost independently from each other). Otherwise, it is very difficult to draw any reliable conclusion from such expensive experiments.
Ceramic Stationary Gas Turbine Development Program: Sixth Annual Summary
Authors: Price Jeffrey R. , Jimenez Oscar , Parthasarathy Vijay , Miriyala Narendernath 
Published: December 2014

The Ceramic Stationary Gas Turbine (CSGT) program is being performed under the sponsorship of the United States Department of Energy, Office of Industrial Technologies. The objective of the program is to improve the performance of stationary gas turbines in cogeneration through the selective replacement of cooled metallic hot section components with uncooled ceramic parts. This review summarizes the progress on Phase III of the program which involves field testing of the ceramic components at a cogeneration end user site and characterization of the ceramic components following the field test exposure.
The Solar Centaur 50S engine, which operates a turbine rotor inlet temperature (TRIT) of 1010°C (1850°F), was selected for the developmental program. The program goals include an increase in the TRIT to 1121°C (2050 °F), accompanied by increases in thermal efficiency and output power. This will be accomplished by the incorporation of uncooled ceramic first stage blades and nozzles, and a “hot wall” ceramic combustor liner. The performance improvements are attributable to the increase in TRIT and the reduction in cooling air requirements for the ceramic parts. The “hot wall” ceramic liners also enable a reduction in gas turbine emissions of NOx and CO.
The component design and material selection have been definitized for the ceramic blades, nozzles and combustor liners. Each of these ceramic component designs were successfully tested in short term engine tests in the Centaur 50S engine test cell facility at Solar. Based on the results of the engine testing of the ceramic components, minor redesigns of the ceramic/metallic attachments were conducted where necessary. Based on their performance in a 100 hour cyclic in-house engine test, the ceramic components are approved for field testing. To date, four field installations of the CSGT Centaur 50S engine totaling over 4000 hours of operation have been initiated under the program at an industrial cogeneration site. This paper discusses the component design and material selection, in house engine testing, field testing, and component characterization.
Natural Gas Fired Combined Cycles With Low CO2 Emissions
Authors: Chiesa Paolo , Consonni Stefano 
Published: December 2014

This paper assesses performances and economic viability of CO2 removal by chemical absorption from the flue gases of natural gas-fired Combined Cycles, more specifically for two configurations: one where CO2 is removed ahead of the stack without modifying the power cycle; the other where part of the flue gases is recirculated to the gas turbine, thereby reducing the flow to be treated by chemical absorption. In both cases sequestered CO2 is made available at conditions suitable to storage into deep oceanic waters.
Performances and cost of electricity are evaluated for systems based on large, heavy-duty turbines representative of state of the art “FA” technology. Carbon sequestration reduces net plant efficiency and power output by about 10% and increases the cost of electricity from 36 to about 50 mills/kWh. Flue gas recirculation warrants slightly higher efficiencies and lower costs.
CO2 removal is eventually compared with other strategies for the reduction of CO2 emissions, like switching existing coal-fired steam plants to natural gas or replacing existing steam plants with conventional CCs. At current fuel prices the latter appears the option of choice, with a cost of about 25 $ per tonn of avoided CO2 emission.