bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heat Transfer in a Rotating Radial Channel With Swirling Internal Flow
Authors: Glezer B. , Moon H. K. , Kerrebrock J. , Bons J. , Guenette G. 
Published: December 2014

This paper presents experimental results for heat transfer in swirling internal flow, obtained in two ways. A test rig simulated a rotating blade’s leading edge internal passage with heated walls and screw-shaped cooling swirl generated by flow introduced through discrete tangential slots. Spatially resolved variations of the surface heat transfer coefficients were measured in the rotating rig using an IR radiometer.
A blade tested in the actual engine environment had similar geometry of the leading edge cooling passage. The blade surface temperatures were mapped in the engine with thermal paints and compared with a traditional convective cooling configuration. The data from the rotating rig and engine measurements are also compared with non-rotating heat transfer results obtained in the hot cascade using a traversing pyrometer at a realistic wall-to-coolant temperature ratio.
The results are presented for realistic rotational numbers, ranging from 0 to 0.023, and for representative Reynolds number of 20,000 based on the channel diameter. The effect of Coriolis forces is evident with the change of direction of the rotation. A slight negative influence of the crossflow, which increased toward the outer radius of the channel, was recorded in the rig test results.
The results presented will assist in better understanding of the screw-shaped swirl cooling technique, providing the next step toward the application of this highly-effective internal cooling method for the leading edges of turbine blades.
A Performance Evaluation of a Three Splitter Diffuser and Vaneless Diffuser Installed on the Power Turbine Exhaust of a TF40B Gas Turbine
Authors: Harris Howard , Piñeiro Ivan , Norris Tom 
Published: December 2014

A field test was conducted on a three splitter diffuser and a vaneless diffuser (no splitters) to determine, the pressure recovery coefficient, effects on engine performance, exhaust collector temperature distribution, and exhaust gas noise.
This paper presents the cause of the mechanical failure of the three splitter diffuser, basic diffuser design, field test instrumentation, and the test results. The test results found the vaneless diffuser had a higher pressure recovery, created a lower back pressure, and did not raise the exhaust gas temperature (EGT) nor fuel consumption of the engine, as compared to the three splitter diffuser.
Development of a Dual Fuel Catalytic Combustor for a 2.3 MWe Gas Turbine
Authors: Le Gal Jean-Hervé , Martin Gérard , Durand Daniel 
Published: December 2014

Biomass derived fuels are an essential alternative for heat and energy production, in order to minimise environmental impact, since they make no net contribution to the increase of CO2 emissions into the atmosphere. In certain countries, biofuels are also interesting since they are available as waste products from the agricultural or forestry industry. Unfortunately, combustion of biofuels often results in high emissions levels of pollutants such as NOx, CO and unburned hydrocarbons.
In gas turbines, catalytic combustion of biofuels has the potential to reduce emissions of these undesired species. The ULECAT project (Ultra Low Emissions CATalytic combustor) described in this paper is the first step of a program aiming at the development of an ultra-low emission gas turbine in the range of 1 to 5 MWe, able to run with both biomass-derived gases and liquid fuels. The objective of the project is to assess the feasibility of a dual fuel catalytic combustor.
Combustor design issues are investigated at full and part load conditions. For the comparison of combustor configuration, modelling provides a useful help for catalytic section design, in particular for the estimation of catalytic activity and wall temperature which strongly influence catalyst life time.
Catalyst development is one of the main topics of this project. It is mainly focused on high temperature catalyst durability and the reduction of NOx formation. This last point is of primary importance in biofuels combustion and certain catalysts have shown an important potential in reducing ammonia conversion into NOx in some operating conditions. Catalyst performances are evaluated at lab scale and also pilot scale in representative gas turbine combustor conditions with both Diesel fuel and biomass derived fuels.
Behavior of Attractors During Surge in Centrifugal Compression System
Authors: Mutou A. , Mizuki S. , Komatsubara Y. , Tsujita H. 
Published: December 2014

A dynamical system analysis method is presented, that permits the characterization of unsteady phenomena in a centrifugal compression system. The method maps one experimental time series of data into a state space in which behaviors of the compression system should be represented, and reconstructs an attractor that geometrically characterizes a state of the compression system.
The time series of data were obtained by using a high response pressure transducer and an analog to digital converter at surge condition. For the reconstruction of attractors, a noise free differentiation method in time was employed. The differentiation was made by high order finite difference methods. To remove the influence of noise, the data were passed through a filter using a third order spline interpolation. In this study, the dimension of the state space was restricted to three. The measured data itself and their first and second derivatives in time are used to represent an attractor in the state space.
The modeling of the system behavior from the time series of data by second order ordinary differential equations was attempted. It is assumed that the data and their derivatives satisfy the equations at each time. Then, appropriate coefficients are determined by a least square method.
The reconstructed attractor showed complex cyclic trajectories at a first glance. However, by applying a band pass filter to the original signal, it was found that the attractor consisted of three independent wave forms and formed an attractor with torus-like behavior. In contrast, the solution by the modeled equations showed a type of limit cycle.
Vibroacoustic Early Warning System for Gas Turbines
Authors: Moen Lyder , Jahr Knuth 
Published: December 2014

Conventional engine shut-down systems for vibration protection of aero-derivative gas generators and power turbines are usually not appropriate for protecting the machines against component malfunction primary damage.
Consequences often seen are substantial secondary damages to the engine as a result of e.g. ballor roller bearing failure. Effects typically vary from various blade or vane damage, root fretting or blade rubbing, etc.
Conventional engine shut-down systems do not activate until a certain unbalance of energy is released. The nature of the signals related to bearing and bladepass are too small in energy, and lies in too high a frequency range to be monitored by conventional engine protection systems.
This paper highlights the importance of the early detection and trending of vibrations, and taking necessary actions to prevent secondary damage to the engine, and describes the experience from a dedicated vibration and acoustic analysis system designed for early warning of common faults.
Experimentally Determined Rotor Power Losses in Homopolar and Heteropolar Magnetic Bearings
Authors: Kasarda M. E. F. , Allaire P. E. , Norris P. M. , Mastrangelo C. , Maslen E. H. 
Published: December 2014

The identification of parameters that dictate the magnitude of rotor power losses in radial magnetic bearings is very important for many applications. Low loss performance of magnetic bearings in aerospace equipment such as jet engines and flywheel energy storage systems is especially critical. Two basic magnetic bearing designs are employed in industrial practice today: the homopolar design, where the flux paths are of a mixed radial/axial orientation, and the heteropolar design, where the flux paths are primarily radial in nature.
The stator geometry and flux path of a specific bearing can have a significant effect on the rotor losses. This paper describes the detailed measurement of rotor losses for experimentally comparable homopolar and heteropolar designs. The two test bearing configurations are identical except for geometric features that determine the direction of the flux path. Both test bearing designs have the same air gap length, tip clearance ratio, surface area under the poles, and bias flux levels. An experimental test apparatus was used where run down tests were performed on a test rotor with both bearing designs to measure power losses. Numerous test runs where made for each bearing configuration by running multiple levels of flux density. The components of the overall measured power loss, due to hysteresis, eddy currents, and windage, were determined based on theoretical expressions for power loss. It was found that the homopolar bearing had significantly lower power losses than the heteropolar bearing.
Conceptual Design of the Cooling System for 1700°C-Class Hydrogen-Fueled Combustion Gas Turbines
Authors: Kizuka N. , Sagae K. , Anzai S. , Marushima S. , Ikeguchi T. , Kawaike K. 
Published: December 2014

The effects of three types of cooling systems on the calculated operating performances of a hydrogen-fueled thermal power plant with a 1,700°C-class gas turbine were studied with the goal of attaining a thermal efficiency of greater than 60%. The combination of a closed-circuit water cooling system for the nozzle blades and a steam cooling system for the rotor blades was found to be the most efficient, since it eliminated the penalties of a conventional open-circuit cooling system which ejects coolant into the main hot gas stream.
Based on the results, the water cooled first-stage nozzle blade and the steam cooled first-stage rotor blade were designed. The former features array of circular cooling holes close to the surface and uses a copper alloy taking advantage of recent coating technologies such as thermal barrier coatings (TBCs) and metal coatings to decrease the temperature and protect the blade core material. The later has cooling by serpentine cooling passages with V-shaped staggered turbulence promoter ribs which intensify the internal cooling.
Periodic Transition on an Axial Compressor Stator — Incidence and Clocking Effects: Part II — Transition Onset Predictions
Authors: Solomon W. J. , Walker G. J. , Hughes J. D. 
Published: December 2014

Transition onset observations from a 1.5-stage axial compressor outlet stator presented in Part 1 of this paper are compared with the predictions of conventional transition correlations applied in a quasi-steady manner.
The viscous/inviscid interaction code MISES is used to predict the blade surface pressure distributions and boundary layer development. The temporal variation in transition onset is then predicted using ensemble-averaged freestream turbulence data from the compressor measurements. This simple procedure captures most significant features of the complex transition process on the compressor, and is clearly superior to fixed transition models based on long-term average freestream turbulence levels.
Parallel computations for both natural and bypass transition modes indicate that the natural transition mode tends to dominate on the compressor. This is at variance with turbine airfoil experience, where bypass transition is clearly more important.
Comparison of prediction and experiment highlights the significance of leading edge potential flow interactions in promoting periodic wake-induced transition. Viscous/inviscid interactions in the neighborhood of transition can also have an important influence on boundary layer stability and separation phenomena.
Gas Turbine Distributed Control Systems: Power Supply and Communication Data Bus Design Considerations
Authors: Sobanski Kurt , Martin Ken , Shi Fong , Greenway Brad 
Published: December 2014

Over the past several decades, gas turbine control systems have evolved from hydro-mechanical systems to full authority redundant electronic systems. One advanced technology with potential to revolutionize the way engine system designers build new products is high temperature distributed controls. Distributed control systems put electronics close to control functions and reduce the number of interconnects between central processors and sensors or effectors. In distributed systems, power and data buses take the place of multiple discrete analog wire bundles found in centralized control systems. Distributed modules interconnected with power and data buses control effectors such as hydraulic actuators or solenoid valves and read sensors to measure pressures, temperatures and speeds. With distributed controls, many gas turbine applications will require high temperature electronics ruggedized to survive the demanding environment.
For these new systems, manufacturers must determine how to maximize the use of standard interfaces and electronic components and minimize the use of custom parts. Two particular areas would benefit the aerospace industry include distributed system power supplies and communication data buses since these designs play an important role in system cost, weight, size and reliability. Interface standardization will benefit engine manufacturers by lowering system cost and enabling inter-changeability of distributed engine control components from different suppliers. Careful attention to architectural design details for the power supplies and data buses can lead to systems that meet the needs of end users.
Computerized Educational Program in Turbomachinery
Authors: Léotard Philippe , Roy Samuel , Gaulard Frédéric , Fransson Torsten H. 
Published: December 2014

The recent astonishing progress in computerized sciences have given birth to multimedia, an electronic revolution sometimes compared to the Industrial Revolution of the 19th century. The application of multimedia to education is one of the pre-eminent challenges of the future for academic and industrial institutions. It will certainly dramatically increase both teaching and learning capabilities.
Turbomachines traditionally belong to a scientific field of high technology. Education in the field of turbomachinery is however today principally performed in a traditional way, via lectures, calculation exercises and laboratory experiments. The use of multimedia technology opens up possibilities, which did not previously exist, to perform systematic parameter studies and calculations in undergraduate education, so that the students are able to get a taste of the physical variables that govern the phenomena lectured.
A “Multimedia Educational Package” within the sector Turbomachinery has been developed. This tool, available on CD-ROM and partially on Internet, mainly focuses at present on Thermodynamic Cycles, Turbomachines and Measuring Techniques in Thermal Engineering.
Interactivity is the key concept of the program. The knowledge assimilated by the user is assessed via multiple choice questions with guided answers. Various aspects of the developed model are also integrated in a Turbomachinery Graduate Curriculum.
Numerous tests have already been carried out during lectures, with a positive response from the students. Both students and teachers profoundly believe that, if combined with traditional education, this multimedia tool will enhance not only the knowledge of students, but also their interest in this field. As far as the authors are aware this is the most comprehensive multimedia educational package for turbomachines which presently exists. Figure 1 shows the introductory interface of this package and Fig. 2 an example of a simulation of velocity triangles in the “Turbomachines City”.
Influence of Vane-Blade Spacing on Transonic Turbine Stage Aerodynamics: Part II — Time-Resolved Data and Analysis
Authors: Busby Judy A. , Davis Roger L. , Dorney Daniel J. , Dunn Michael G. , Haldeman Charles W. , Abhari Reza S. , Venable Brian L. , Delaney Robert A. 
Published: December 2014

This paper presents results of a combined experimental/computational investigation into the effects of vane-blade spacing on the unsteady aerodynamics of a transonic turbine stage. Time-resolved data were taken in a shock-tunnel facility in which the flow was generated with a short-duration source of heated and pressurized air. This data is compared with the results obtained from four unsteady Navier-Stokes solvers.
The time-resolved flow for three axial spacings is examined. For each vane-blade spacing, the inlet conditions were nearly identical and the vane exit flow was transonic. Surface-mounted high-response pressure transducers at midspan were used to obtain the pressure measurements.
The computed two-dimensional unsteady airfoil surface pressure predictions are compared with the Kulite pressure transducer measurements. The unsteady and axial spacing effects on loading and performance are examined.
In general the numerical solutions compared very favorably with each other and with the experimental data. The overall predicted stage losses and efficiencies did not vary much with vane/blade axial spacing. The computations indicated that any increases in the blade relative total pressure loss were offset by a decrease in vane loss as the axial spacing was decreased. The decrease in predicted vane total pressure loss with decreased axial spacing was primarily due to a reduction in the wake mixing losses. The increase in predicted blade relative total pressure loss with a decrease in axial spacing was found to be mainly due to increased vane wake/blade interaction.
Viscous and Inviscid Linear/Nonlinear Calculations Versus Quasi 3D Experimental Cascade Data for a New Aeroelastic Turbine Standard Configuration
Authors: Fransson T. H. , Jöcker M. , Bölcs A. , Ott P. 
Published: December 2014

This paper presents a new International Standard Configuration to be added to an already existing set of 10 configurations for unsteady flow through vibrating axial-flow turbomachine cascades. This 11th configuration represents a turbine blade geometry with transonic design flow conditions with a normal shock positioned at 75% real chord on the suction side. Out of a set of test cases covering all relevant flow regimes two cases were selected for publication: A subsonic, attached flow case and an off-design transonic case showing a separation bubble at 30% real chord on the suction side are published. The performed tests are shown to be repeatable and suitable for code validations of numerical models predicting flutter in viscous flows.
The validity of the measured data of the two public cases was examined and comparisons with other tests were conducted. Sometimes a large difference in aerodynamic damping was observed on cases with similar flow conditions. This was investigated at three transonic cases with almost identical inlet flow conditions and only small variations in outlet Mach Number. It was found that the differences in the global damping are due to very local changes on the blade surface in the shock region, which obtain a large influence by the integration because of the discrete measuring points. Hence it is recommended not to look at the global damping for code validations but more precisely to the local values. These show a common tendency, which is reproducible with different numerical methods.
This was demonstrated with a potential model, a linear Euler model, a nonlinear Euler model and a Navier-Stokes solver, all applied to predict flutter of each test case with a 2D/Q3D approach. The limitations of inviscid codes to predict flutter in viscous flow regimes is demonstrated, but also their cost advantage in attached flow calculations. The need of viscous code development and validation is pointed out. This should justify and encourage the publication of thoroughly measured test cases with viscous effects.
Effect of the Shear Driven Liquid Wall Film on the Performance of Prefilming Airblast Atomizers
Authors: Rosskamp Heiko , Willmann Michael , Meisl Jürgen , Meier Robert , Maier Georg , Wittig Sigmar 
Published: December 2014

Advanced prefilming airblast atomizers are widely used for low emission combustors since they deliver a fine spray almost independently of the fuel flow rate. The droplet spectrum produced by this type of atomizer results from the aerodynamic forces at the atomizer edge and from the fuel properties prior to the film disintegration. Therefore, the wall film temperature is an important parameter affecting the fuel properties and in turn the atomization quality. Even though this atomizer type became well investigated (Lefebvre 1989, Rizk et al. 1987, Sattelmayer et al. 1989), still no general quantitative relationship between atomizer design and spray quality could be established since the fuel state at the atomizer edge cannot be precisely predicted yet.
In extending earlier experimental and theoretical work on airblast atomizers (Sattelmayer et al. 1989, Himmelsbach et al. 1994, Willmann et al. 1997) and recent advances in the numerical modeling of wall film flows (Rosskamp et al. 1997a), this paper presents a numerical approach to judge the effect of fuel mass flow, air flow and the film length (i. e. length of atomizer lip) on the temperature of the liquid at the atomizer edge. The computer code developed provides detailed information on the wall film flow and the nozzle wall temperature. For the prediction of heat transfer to the film a new model has been developed which is based on measurements of the internal film flow (Elsäßer et al 1997).
This new numerical approach can serve as a design tool to evaluate the effects of design modifications during atomizer development with view to their effect on atomization performance. The paper includes the theory for two-phase flow modeling and a generic parameter study that points out that the liquid loading and the length of the atomizer lip are important parameters in atomizer design. The calculations presented in the paper emphasize the necessity of coupled two-phase flow calculations because the film strongly interacts with the gas phase and the predicted atomizer performance is sensitive to changes in the air flow.
Coupled Acoustic-Structure Analysis of an Annular DLE Combustor
Authors: Cronemyr Peter J. M. , Hulme Chris J. , Troger Christian 
Published: December 2014

With the advent of today’s dry low emission (DLE) combustors for industrial gas turbines (GT), an additional type of load case other than thermal loading on the combustor structure, has put itself heavily into focus, namely pulsation loading. Although recognised for decades in rocket engines and ram-jets, it was not until the incorporation of diluted flames and completely closed combustors, used to reduce NOx emissions, that thermo-acoustically excited pressure pulsations became an issue in the design of industrial GT combustors.
This paper presents the computational methods that are available for the analysis of this phenomenon, and their application in the development of ABB’s latest annular DLE combustor. Among these are calculations of burner excitation frequency, pressure wave propagation within the combustor, acoustic and structural eigen frequencies, and coupled acoustic structural analysis.
Guidelines for the combustor design to prevent instabilities and coupling of air and structure pulsations are suggested.