bluuebunny/crossref_metadata_2025_split huggingface dataset:
On-Line Temperature Measurement Inside a Thermal Barrier Sensor Coating During Engine Operation
Authors: Yañez Gonzalez A. , Pilgrim C. C. , Feist J. P. , Sollazzo P. Y. , Beyrau F. , Heyes A. L. 
Published: September 2014

Existing thermal barrier coatings (TBC) can be adapted enhancing their functionalities such that they not only protect critical components from hot gases, but also can sense their own material temperature or other physical properties. The self-sensing capability is introduced by embedding optically active rare earth ions into the thermal barrier ceramic. When illuminated by light the material starts to phosphoresce and the phosphorescence can provide in-situ information on temperature, phase changes, corrosion or erosion of the coating subject to the coating design.
The integration of an on-line temperature detection system enables the full potential of TBCs to be realised due to improved accuracy in temperature measurement and early warning of degradation. This in turn will increase fuel efficiency and will reduce CO2 emissions.
This paper reviews the previous implementation of such a measurement system into a Rolls-Royce jet engine using dysprosium doped yttrium-stabilised-zirconia as a single layer and a dual layer sensor coating material. The temperature measurements were carried out on cooled and uncooled components on a combustion chamber liner and on nozzle guide vanes respectively.
The paper investigates the interpretation of those results looking at coating thickness effects and temperature gradients across the TBC. For the study a specialised cyclic thermal gradient burner test rig was operated and instrumented using equivalent instrumentation to that used for the engine test. This unique rig enables the controlled heating of the coatings at different temperature regimes. A long-wavelength pyrometer was employed detecting the surface temperature of the coating in combination with the phosphorescence detector. A correction was applied to compensate for changes in emissivity using two methods. A thermocouple was used continuously measuring the substrate temperature of the sample. Typical gradients across the coating are less than 1K/μm. As the excitation laser penetrates the coating it generates phosphorescence from several locations throughout the coating and hence provides an integrated signal.
The study successfully proved that the temperature indication from the phosphorescence coating remains between the surface and substrate temperature for all operating conditions. This demonstrates the possibility to measure inside the coating closer to the bond coat. The knowledge of the bond coat temperature is relevant to the growth of the thermally grown oxide which is linked to the delamination of the coating and hence determines its life.
Further, the data is related to a one dimensional phosphorescence model determining the penetration depth of the laser and the emission.
Note: a video of the measurement system can be watched under: [http://www.youtube.com/watch?v=T6uXN1__Z7I].
Off-Line Temperature Profiling Utilising Phosphorescent Thermal History Paints and Coatings
Authors: Feist J. P. , Biswas S. Karmaker , Pilgrim C. , Sollazzo P. Y. , Berthier S. 
Published: September 2014

Temperature profiling of components in gas turbines is of increasing importance as engineers drive to increase firing temperatures and optimise component’s cooling requirements in order to increase efficiency and lower CO2 emissions. However, on-line temperature measurements and, particularly, temperature profiling are difficult, sometimes impossible, to perform due to inaccessibility of the components. A desirable alternative would be to record the exposure temperature in such a way that it can be determined later, off-line.
The commercially available Thermal Paints are toxic in nature and come with a range of technical disadvantages such as subjective readout and limited durability. This paper proposes a novel alternative measurement technique which the authors call Thermal History Paints and Thermal History Coatings. These can be particularly useful in the design process, but further could provide benefits in the maintenance area where hotspots which occurred during operation can be detected during maintenance intervals when the engine is at ambient temperature.
This novel temperature profiling technique uses optical active ions in a ceramic host material. When these ions are excited by light they start to phosphoresce. The host material undergoes irreversible changes when exposed to elevated temperatures and since these changes are on the atomic level they influence the phosphorescent properties such as the life time decay of the phosphorescence. The changes in phosphorescence can be related to temperature through calibration such that in-situ analysis will return the temperature experienced by the coating. A major benefit of this technique is in the automated interpretation of the coatings. An electronic instrument is used to measure the phosphorescence signal eliminating the need for a specialist interpreter and thus increasing readout speed.
This paper reviews results from temperature measurements made with a water based paint for the temperature range 100°C to 800°C in controlled conditions. Repeatability of the tests and errors will be discussed. Further, some measurements are carried out using an electronic hand-held interrogation device which can scan a component surface and provide a spatial resolution of below 3mm. The instrument enables mobile measurements outside of laboratory conditions.
Further a robust Thermal History Coating is introduced demonstrating the capability of the coating to withstand long term exposures. The coating is based on Thermal Barrier Coating architecture with a high temperature bondcoat and deposited using an air plasma spray process to manufacture a reliable long lasting coating. Such a coating could be employed over the life of the component to provide critical temperature information at regular maintenance intervals for example indicating hot spots on engine parts.
Stability Study of a Bladed Disk in Interaction With a Casing via a Labyrinth Seal
Authors: Andreev F. B. , Thouverez F. , Gouskov A. M. , Blanc L. 
Published: September 2014

In this paper a simplified coupled model of a bladed disk and flexible stator developed in a rotating frame is introduced. The interaction between the rotating and stationary parts is adjusted using the gas flow in the straight-through labyrinth seal located on the tip of the blades. This is therefore an “aero elastic contact” problem. An energy-based method is used to express the equations of motion. The computation of eigenvalues provides the Campbell diagram and information on stability. A single-control-volume analysis is performed to predict the destabilizing force exerted by the labyrinth seal.
In terms of strategy a simpler and efficient model with a rigid rotating shaft is compared with models found in the literature before the complete rotor-stator aero elastic contact study is presented. This is followed by a study of the interaction between the bladed disk with a labyrinth seal and the flexible stator.
The model proposed provides a new approach to modelling rotor systems with labyrinth seals. The stator is then modelled as a flexible body and the rotor as a bladed disk. It is shown in the example described that the stability of the system depends on the rigid body movement of the stator and is independent of its nodal diameter modes.
Development of a Pressure-Based Coupled CFD Solver for Turbulent and Compressible Flows in Turbomachinery Applications
Authors: Mangani Luca , Darwish Marwan , Moukalled Fadl 
Published: September 2014

In this paper we present a fully coupled algorithm for the resolution of compressible flows at all speed. The pressure-velocity coupling at the heart of the Navier Stokes equations is accomplished by deriving a pressure equation in similar fashion to what is done in the segregated SIMPLE algorithm except that the influence of the velocity fields is treated implicitly. In a similar way, the assembly of the momentum equations is modified to treat the pressure gradient implicitly. The resulting extended system of equations, now formed of matrix coefficients that couples the momentum and pressure equations, is solved using an algebraic multigrid solver.
The performance of the coupled approach and the improved efficiency of the novel developed code was validated comparing results with experimental and numerical data available from reference literature test cases as well as with segregated solver as exemplified by the SIMPLE algorithm. Moreover the reference geometries considered in the validation process cover the typical aerodynamics applications in gas turbine analysis and design, considering Euler to turbulent flow problems and clearly indicating the substantial improvements in terms of computational cost and robustness.
Influence of Injection Ratio of Dual-Injection Type Air-Blast Fuel Nozzle on Emission Characteristics Applied to Rectangular Single-Sector Combustor Under Atmospheric Condition
Authors: Makida Mitsumasa , Kurosawa Yoji , Yamada Hideshi 
Published: September 2014

In the TechCLEAN project of JAXA, experimental research had been conducted to develop a combustor for a small aircraft engine. The combustor was tuned to show the behavior of the Rich-Lean combustion through tests under atmospheric and practical conditions. Finally, through full annular combustion experiments under practical conditions, the combustor was tuned to reduce NOx emissions to almost 40% of the ICAO CAEP4 standard, also sustaining low CO and THC emissions. In the developing process of above combustors, to simplify the combustor system, air blast type fuel nozzles with single fuel injection and dual swirlers were applied. Successively, in this report, the fuel nozzle is modified to dual fuel injection type with triple swirlers, aiming to control combustion performance under varying load conditions. Fuel is injected from inner and outer injection circuits, and the injection ratio between them is treated as one of the parameters.
The combination of swirl direction of the three swirlers is selected at first through ignition and blowout tests. Secondly, spray patterns of the selected fuel nozzle are observed with different fuel injection ratios. Thirdly, the nozzle is applied to a rectangular single-sector combustor, and tested under atmospheric pressure with inlet temperature of 500K. NOx, CO, CO2, THC and O2 compositions in the exhaust gas are measured, and correlation among measured emissions data and fuel injection ratio is estimated to examine the influence of the injection ratio on combustion characteristics of the Rich-Lean type aero engine combustor.
Dynamic Stress Analysis of a Blade in a Partially Blocked Engine Inlet
Authors: Drewczynski Marcin , Rzadkowski Romuald , Ostrowska Zofia 
Published: September 2014

One of the greatest dangers to properly working aircraft engines, apart from human error, is the ingestion foreign objects into the compressor. These objects may be birds, dust, hail, volcanic ash, ice on wings but also aircraft parts or simply garbage. Modern jet engines can suffer major damage from even small objects being sucked into the engine. We want to show how foreign object debris affects the dynamic stress level of a rotor blade. A comparison between an undisturbed engine inlet and one with an ingested foreign object is carried out. The analysis will focus on the first stage compressor blade of an aircraft engine with a partially blocked radial inlet.
The main subject of this paper concerns transferring a CFD analysis pressure field as a surface load to the structural model of a blade.
First a CFD calculation of a nominal and disturbance regime was conducted. In both cases an unsteady pressure was calculated.
Calculations were carried out on a first stage compressor blade. Ansys 12.1 was used to calculate the entire structure. Unsteady CFD calculations used Fluent for a 1.5 stage axial compressor model. A non-viscous flow was used for the numerical calculations. The unsteady forces were calculated on 10 control cross-sections of a rotor blade. The transient results obtained from the CFD calculations were transferred onto a structural rotor blade model using APDL language script.
Development of a Liquid Fuel System for GE MS5002E Gas Turbine: Rig Test Validation of the Combustor Performance
Authors: Zucca Alessandro , Khayrulin Sergey , Vyazemskaya Natalya , Shershnyov Borys , Myers Geoff 
Published: September 2014

Analysis of the Oil & Gas market segment showed that potential MS5002E customers could benefit from firing the gas turbine with distillate oil as a back-up fuel, mainly to provide power when the fuel gas is not available (e.g. when the plant itself is being commissioned). To address this customer need, the design of a dual fuel system for such mission should target simplicity, reliability and minimize the additional cost with respect to the single gas version. To achieve these targets, the development of the dual fuel system for the MS5002E leveraged the efforts made by GE for the design of a liquid fuel system for Frame 9F-1 series with no need of atomization air. Moreover, the emission capability during liquid fuel operation was enhanced allowing the mixing of water and fuel before injection in the combustion chamber and using of improved injection technology, thus improving the efficiency of water injection with a significant reduction in the required water flow rates; the importance of this achievement is related to both the increasingly stringent regulation on this subject and the often poor availability of water in the Oil & Gas market segment. The system is capable of continuous operation without water injection for applications where emissions are not critical; in these cases a small amount of demineralized water is employed occasionally for fuel line cooling and flushing, thus helping to guarantee constant performances of the injectors, and to maintain liquid fuel start-up capability over time.
This paper presents the expected performance, in terms of ignition capability, emissions, operability and expected hardware durability on LF/water-fuel emulsion operation, based on a single can rig test campaign. The new liquid fuel cartridges were tested from ignition to base load at ISO and extreme simulated ambient conditions, both with and without water injection, showing promising performance in terms of combustor operability and emissions. All the combustor components were instrumented with thermocouples to assess variations in the hardware thermal levels with respect to the single gas conditions, and identify possible issues related to the transient and steady-state liquid fuel operation. Further development and testing will be carried out in the next phases of the development, and the performance will be confirmed by a dedicated engine test at the first commercial opportunity.
Vibration Characteristics of Segmented Stator Assemblies in Axial Compressors
Authors: Meyer Michael , Gentry-Grace Cassandra 
Published: September 2014

A common component in axial compressors used in turbo machinery applications is the segmented stator assembly with fixed airfoils attached to inner and outer bands forming a partial ring. Understanding the potential for vibratory responses of these components during engine operation is vital to avoid harmful vibrations. However, an accurate prediction of segmented stator assembly vibratory characteristics is difficult due to the partial nature of their cyclic symmetry and high part to part manufacturing variation. Numerous analyses related to laboratory tests, engine tests and theoretical studies have been performed to advance the understanding and better quantify the segmented stator assembly dynamic behavior. A summary of the component dynamic behavior is provided through a series of lessons learned from the various analyses completed.
The segmented stator assemblies can be thought of as cyclically symmetric parts with properties of extreme mistuning. These properties are realized when one attempts to evaluate the components using experimental and theoretical approaches traditionally reserved for cyclically symmetric components. Specifically, harmonic indices are often employed to identify modes of interest in a cyclically symmetric system with reference to known engine order excitations. However, with segmented stator assemblies, there is a high density of modal frequency distribution across the engine operating range and mode shapes can suffer from significant contamination of the diametral patterns. These observations complicate linking specific modes to known engine order excitations. This study implements traditional FEA approaches and reduced order models in an attempt to predict the key vibratory modes of concern and to show which component features most significantly affect the vibratory characteristics of segmented stator assemblies. Observations made during bench tests are compared to theoretical analyses and confirm the challenges of assessing the dynamic properties of segmented stator assemblies. This work supports emerging segmented stator design evaluation techniques, an area that is critical to successful integration of these components into turbo machinery applications.
Impact of the Secondary Air System Design Parameters on the Calculation of Turbine Discs Windage
Authors: Rey Villazón Jose Maria , Wildow Toni , Benton Robert , Göhler Moritz , Kühhorn Arnold 
Published: September 2014

The rotating components in gas turbines are very highly stressed as a result of the centrifugal and thermal loads. One of the main functions of the secondary air system (SAS) is to ensure that the rotating components are surrounded by air that optimizes disc lifing and integrity. The SAS is also responsible for the blade cooling flow supply, preventing hot gas ingestion from the main annulus into the rotor-stator cavities, and for balancing the net axial load in the thrust bearings. Thus, the SAS design requires a multidisciplinary compromise to provide the above functions, while minimizing the penalty of the secondary flows on engine performance.
The phenomenon known as rotor-stator drag or windage is defined as the power of the rotor moment acting on its environment. The power loss due to windage has a direct impact on the performance of the turbine and the overall efficiency of the engine. This paper describes a novel preliminary design approach to calculate the windage of the rotor-stator cavities in the front of a typical aero engine HP turbine. The new method is applied to investigate the impact of the SAS design parameters on the windage losses and on the properties of the cooling flows leading to the main annulus.
Initially, a theoretical approach is followed to calculate the power losses of each part of the HPT front air feed system. Then, a 1D-network integral model of the cavities and flow passages of the HPT front is built and enhanced with detailed flow field correlations. The new 1D-flow network model offers higher fidelity regarding local effects. A result comparison between the theoretical calculation and the prediction of the enhanced flow network model puts forward the relevance of the local flow field effects in the design concept of the SAS.
Using the enhanced 1D-flow network models, the SAS design parameters are varied to assess their influence on the windage and pumping power calculation. As a conclusion, the paper shows how the SAS design can have a significant influence on the HPT overall power and the air that is fed back into the turbine blade rows. Controlling these features is essential to bid a competitive technology in the aero engine industry.
Improvement of Flat-Plate Film Cooling Performance by Double Flow Control Devices: Part II — Optimization of Device Shape and Arrangement by Experiment- and CFD-Based Taguchi Method
Authors: Kawabata Hirokazu , Funazaki Ken-ichi , Nakata Ryota , Tagawa Hisato , Horiuchi Yasuhiro 
Published: September 2014

This paper, as a second part of the study on the double flow control device (DFCD) which has been proven in Part I [1] to improve the flat plate film cooling considerably, describes an approach to optimize the device shape and arrangement using Taguchi method. The target cooling holes are conventional cylindrical ones of 3.0d pitch with 35 deg angle to the flat plate surface. The shape of the double flow control device to be optimized is based on the hemi-spheroid used in Part I.
The optimization process in this study is categorized as “static problem”, in which S/N ratios of “larger-the-better” characteristics are calculated for control parameters against their noise factor. The “larger-the-better” characteristics adopted in this study is the area averaged film effectiveness over the downstream region of the cooling hole. L18 orthogonal array is used to accommodate the experiment. Blowing ratios of the cooling air to the main flow used in this study are 0.5, 0.75 and 1.0, which are regarded as noise factor. Seven control parameters such as fillet radius, installation angle of the device are chosen and their effects on the film effectiveness are evaluated by the measurement as well as by RANS simulation. In this research, the optimization which used Taguchi method was at the same time carried out by an experiment and numerical simulation. From a comparison between the optimal parameter combinations attained from the measurement-based and CFD-based approaches, one can have an idea about the dependency of the optimal parameter combination on the characteristic evaluation approach. Additional investigation is also made on the effects of turbulence model upon the optimal parameter combination.
The flow fields in the downstream region of the optimal DFCD are observed using 3D Laser Doppler Velocimeter in order to understand how the device works on the ejected cooling air. In addition, Large-Eddy-Simulation (LES) is also executed in order to grasp unsteady flow structures created by the device and their interaction with the cooling air. It is found from the measurement as well as the LES analysis that the optimal DFCD generates comparatively large-scale longitudinal vortices, causing the drastic increase in film effectiveness.