bluuebunny/crossref_metadata_2025_split huggingface dataset:
Status of the Automotive Ceramic Gas Turbine Development Program: Year Five Progress
Authors: Nisiyama Tsubura , Nakazawa Norio , Sasaki Masafumi , Iwai Masumi , Katagiri Haruo , Handa Noritoshi 
Published: February 2015

Petroleum Energy Center of Japan has been carrying out a 7-year development program to prove the potential of an automotive ceramic gas turbine for five years with the support of the Ministry of International Trade and Industry. The ceramic gas turbine now under development is a regenerative single shaft engine. The output is 100kW, and the turbine inlet temperature (TIT) is 1350°C.
All the ceramic components are now entering the 1350°C TIT test phase after completing 1200°C TIT evaluation tests, including durability tests, in various types of test rigs. The compressor-turbine combined test rig and the full assembly test rig which is the same as an actual engine and incorporates all the components are now going through 1200°C TIT function and performance evaluation tests. In the near future, we are planning to increase the TIT to 1350°C.
In consideration of the current level of high-temperature, long-term strength available from the ceramic materials, we decided to change the rated speed to 100,000 rpm because the initial rated speed of 110,000 rpm, if unchanged, involves considerable risks. Then we reviewed mainly the designs of the compressor and turbine and revised the target values of the individual components to match the specifications that satisfy the target performance of the engine.
Detailed Velocity and Turbulence Measurements of the Profile Boundary Layer in a Large Scale Turbine Cascade
Authors: Ubaldi Marina , Zunino Pietro , Campora Ugo , Ghiglione Andrea 
Published: February 2015

Extensive measurements of velocity and turbulence have been performed by means of a two-component fibre-optic laser Doppler velocimeter, to investigate the profile boundary layer development on a large scale turbine cascade.
Flow field investigation has been integrated with data obtained by surface-mounted hot-film gauges in order to get direct information on the boundary layer nature and on its time varying characteristics.
Measurements were detailed enough to allow constructing mean velocity and Reynolds stress boundary layer profiles giving an in-depth description of the boundary layer development along both suction and pressure surfaces through laminar, transitional and turbulent regimes.
Excited Turbulent Reacting Flows in a Chamber With Gaseous Fuels Injecting Through Porous Walls
Authors: Liou Tong-Miin , Hwang Po-Wen , Lien Wan-Yih 
Published: February 2015

A numerical analysis was performed to study excited turbulent reacting flows in a combustion chamber consisting of gaseous fuels injecting through porous walls. The time-dependent axisymmetric compressible conservation equations were solved directly without using subgrid-scale turbulence models. The combustion process considered was a one-step, irreversible, and infinitely fast chemical reaction. The numerical code used the finite-volume technique, which involved alternating in time the second-order, explicit MacCormack’s and modified Godunov’s schemes. Excitations with various forcing frequencies were applied to the air inflow boundary to investigate their effects on the large-scale unsteady flow structures, vorticity dynamics, mean flame position, mean temperature distribution, and characteristic exhaust velocity.
From the numerical flow visualization of the instantaneous vorticity field and the associated vorticity dynamics analysis, a rationale for the augmentation or diminution of organized vortical structures under external excitations was provided. It is found that an excitation with the fundamental frequency attains a larger high temperature recirculation zone with a higher peak temperature and hence a better flame-holding condition. An application of the active control by forcing the air inlet velocity with the fundamental frequency at various amplitudes to an original non-sustained combustion case indicates that the combustion can be sustained if an appropriate exciting amplitude is selected.
Compressor Off-Design Performance Prediction Using an Endwall Model
Authors: Dunham John 
Published: February 2015

A throughflow method for designing and analysing compressors has to be supplied with loss, deviation, and blockage estimates for every blade row. The earliest methods used empirical correlations for profile loss and deviation, together with an empirical blockage or “work done” factor, and empirical estimates of additional losses near the endwalls. Previous papers by the author have described how to replace the empirical blockage factor and endwall corrections by explicit calculations using a new mathematical model of the endwall phenomena. Those papers illustrated the application of the method near design conditions, using either design profile loss and deviation figures or computations by a viscous-inviscid interaction blade-to-blade method.
In order to estimate off-design performance rapidly over the whole operating range, some way of estimating off-design profile loss and deviation must be chosen. In this paper, the previously-derived design point loss and deviation figures are retained, and an empirical correlation due to Miller, Wasdell, and Wright is used to predict the changes in loss and deviation off-design. It is shown by means of sample three-dimensional Navier-Stokes computations that the endwall model remains applicable off-design.
The method has been tested against two low speed and two high speed compressors, one of each example having controlled-diffusion blading. The low speed compressor characteristic maps are predicted only approximately, but the predicted high speed compressor maps are good. It is widely believed that endwall flow separation can initiate stall or surge. As stall or surge was approached the shape factor of the annulus wall boundary layer at one location rose sharply, but no single stall-predicting value could be found.
The Application of a Computer-Aided Design Technique to the Conceptual Design of Turbochargers: Part A — Centrifugal Compressor Design and Turbine Matching
Authors: Whitfield A. , Abdullah Abu Hasan 
Published: February 2015

In many turbomachinery applications a compressor is directly driven by a turbine; for turbocharger applications a centrifugal compressor is usually adopted which is generally driven by a radial flow turbine, although mixed flow or axial flow turbines are occasionally required. A non-dimensional design procedure is developed to provide the basic dimensions and blade angles of centrifugal compressor impellers, whilst accounting for the turbine conditions as assessed through the matching requirements. The design of the turbine is then considered further in Part B.
The procedure can be applied for any desired compressor pressure ratio and target efficiency to develop an initial non-dimensional skeleton design. No other parameters are required from the initial specification and the design is developed non-dimensionally without recourse to empirical loss models and the associated uncertainties as the target efficiency must be specified. The procedure provides graphical information with respect to the impeller discharge conditions and inlet conditions from which the designer must select the most appropriate design. The screen graphics interface enables the designer to search across the design options; as this search is carried out numerical data are displayed and continuously up-dated to provide immediate information on which an infnrmed assessment can be based.
In addition to the compressor design options which are provided the matching conditions for the drive turbine provides information, such as specific speed, non-dimensional mass flow rate and pressure ratio, relevant to the turbine design. Judgements with respect to the design options for the compressor can then be made with the consequences for the associated turbine design clearly in view.
The non-dimensional design can be translated into an absolute design through the specification of the required mass flow rate and the inlet stagnation pressure and temperature.
The Application of a Computer-Aided Design Technique to the Conceptual Design of Turbochargers: Part B — Radial Turbine Design
Authors: Whitfield A. , Abdullah Abu Hasan 
Published: February 2015

A procedure similar to that presented in Part A is described for the non-dimensional design of radial inflow turbines. The technique is developed non-dimensionally to provide the overall dimensions, including the leading and trailing edge blade angles, of radial flow turbine rotors. Consideration of the adoption of non-radial blades at rotor inlet, leading to mixed flow rotors, and discharge swirl is included.
The procedure is developed from a knowledge of the non-dimensional power requirement which is derived through the turbocharger matching conditions. To satisfy the matching requirement the mechanical efficiency of the turbocharger, the air fuel ratio, the inlet stagnation temperature relative to that at compressor inlet, and the gas constants for the hot exhaust gas must be specified. In addition a target stage efficiency, on a total to static basis, must be specified.
In essence the procedure provides graphically all the possible velocity vectors at rotor inlet and exhaust. The graphical presentation allows the designer to survey all the options available; as this is done relevant data is presented and continuously up-dated to aid in the selection of the preferred design conditions.
The non-dimensional geometry of the rotor is then developed from which the absolute dimensions can be derived through the specification of the gas mass flow rate and the inlet stagnation conditions.
Numerical Calculations of a Turbine Volute Using a 3-D Navier-Stokes Solver
Authors: Martinez-Botas R. F. , Pullen K. R. , Shi F. 
Published: February 2015

The turbine volute is a complex flow device, about which a few papers on both measurements and CFD predictions have appeared. The main reasons for the difficulties being the complicated geometry which hinders measurements to be taken by both intrusive and non-intrusive techniques, and makes the numerical predictions difficult.
In this paper, the complex three-dimensional flow through a turbine volute with non-symmetric circular cross-section is studied by using a 3-D Navier-Stokes solver which has been developed by the authors. In this solver, the fully 3-D Reynolds averaged N-S equations coupled with high Reynolds number k-ε turbulence model together with the wall function under arbitrary curvilinear coordinate system are solved. The Semi-Implicit Method for Pressure-Linked Equations (SIMPLEC algorithm) with the non-staggered grid arrangement is used. In order to eliminate the decoupling between the velocity and pressure under non-staggered grid system, the physical covariant velocity component is selected as dependent variable in momentum equations and a momentum interpolation approach is employed.
The validity of the free-vortex assumption is reviewed. The computation results are compared with a set of experiments performed previously by one of the authors. The flow features in the volute are discussed.
Empirical and Semi-Empirical Correlation of Emissions Data From Modern Turbopropulsion Gas Turbine Engines
Authors: Danis Allen M. , Pritchard Byron A. , Mongia Hukam C. 
Published: February 2015

The engine certification emissions data from a CFM56 single-annular combustor (SAC), the CFM56 dual-annular combustor (DAC), the CF6-80C SAC and the CF6-80C SAC low-emissions configuration (LEC) were used to show the following:
(1) NOxEI can be correlated as a function of P3 and T3.
(2) There is a unique relationship between NOx, CO and unburned hydrocarbons (HC).
(3) NOx, CO and HC for engine operating points can be predicted reasonably well through “single reactor” modeling. However, the resulting NOx/CO/HC relationship is not as well predicted indicating need for further improving the semiempirical methodology.
Transition of a Technology Base for Advanced Aircraft Gas Turbine Control Systems
Authors: McGlone Michael E. 
Published: February 2015

Technology assessments during the 1980’s projected the development of advanced military fighter aircraft which would require propulsion systems which could accommodate multi-mission capability with super maneuverability. These propulsion systems would be required to provide significantly improved thrust to weight, reduced thrust specific fuel consumption, and up and away thrust vectoring capabilities. Digital electronic control systems with significantly expanded capabilities would be required to handle these multi-function control actuation systems, integration with flight control systems, and to provide fail-operational capability.
This paper will discuss the challenges that were presented to propulsion system control designers, the innovation of technology to address these challenges, and the transition of that technology to production readiness. Technology advancements will be discussed in the area of digital electronic control capability and packaging, advanced fuel management systems, high pressure fuel hydraulic actuation systems for multi-function nozzles, integrated flight propulsion controls, and higher order language software development tools. Each of these areas provided unique opportunities where technology development programs and flight prototyping carried concepts to reality.
Structure of Airblast Sprays Under High Ambient Pressure Conditions
Authors: Zheng Q. P. , Jasuja A. K. , Lefebvre A. H. 
Published: February 2015

A single-velocity-component Phase Doppler Particle Analyzer is used to survey and measure local variations in drop-size distributions and drop velocities in the near-nozzle region of a practical, contra-swirling, prefilming airblast atomizer. The technique of Laser Sheet Imaging is used to obtain global patterns of the spray. All measurements are taken with a constant pressure drop across the atomizer of 5 percent, at ambient air pressures of 1, 6 and 12 bar. The liquid employed is aviation kerosine at flow rates up to 75 g/s. The results show that increasing the air pressure from 1 to 12 bar at a constant air/fuel ratio causes the initial spray cone angle to widen from 85° to 105°. Further downstream the spray volume remains largely unaffected by variations in atomizer operating conditions. However, the radial distribution of fuel within the spray volume is such that increases in fuel flow rate cause a larger proportion of fuel to be contained in the outer regions of the spray.
The effect of ambient pressure on the overall Sauter mean diameter is small. This is attributed to the fact that the rapid disintegration of the fuel sheet produced by the contra-swirling air streams ensures that the atomization process is dominated by the ‘prompt’ mechanism. For this mode of liquid breakup, theory predicts that mean drop sizes are independent of air pressure.
Numerical Prediction of the Dynamic Behaviour of Turbulent Diffusion Flames
Authors: Bohn Dieter , Deutsch Gregor , Krüger Uwe 
Published: February 2015

Environmental compatibility requires low emission burners for gas turbine power plants as well as for jet engines. In the past significant progress has been made developing low NOx and CO burners. Unfortunately these burners often have a more pronounced tendency than conventional burner designs to produce combustion driven oscillations The oscillations may be excited to such an extent that pronounced pulsation may possibly occur; this is associated with a risk of engine failure.
The stability of a burner system can be investigated by means of a stability analysis under the assumption of acoustical behaviour. The problem with all these algorithms is the transfer function of the flame. A new method is presented here to predict the dynamic flame behaviour by means of a full Navier-Stokes-simulation of the complex combustion process. The first step is to get a steady-state solution of a flame configuration. After that a transient simulation follows with a sudden change in the mass flow rate at the flame inlet. The time-dependent answer of the flame to this disturbance is then transformed into the frequency space by a Laplace Transformation. This leads, in turn, to the frequency response representing the dynamic behaviour of the flame.
In principle, this method can be adapted for both diffusion as well as premixed flame systems. However, due to the fact that diffusion flames are more controlled by the mixing process than by the chemical kinetic, the method has first been used for the prediction of the dynamic behaviour of turbulent diffusion flames. The combustion has been modelled by a mixed-is-burnt model. The influence of the turbulence has been taken into account by a modified k-ε-model and the turbulence influences the combustion rate by presumed probability density functions (pdf).
The steady-state as well as the transient results have been compared with experimental data for two different diffusion flame configurations. Although the burner configuration is relatively complex, the steady state results collaborate very well with the experiments for velocity, temperature and species distribution. The most important result is that the heat release which drives the oscillations can be modelled sufficiently accurately. The effect of using different pdf-models has been discussed and the best model has been used for the transient calculations of the dynamic flame behaviour.
The results for the frequency response of the flame are very encouraging. The principal behaviour of the flame — higher order time element with a delay time — can be predicted with sufficient precision. In addition, the qualitative results collaborate fairly well with the experiments.
Application of Thermochromic Liquid Crystal to Rotating Surfaces
Authors: Camci C. , Glezer G. , Owen J. M. , Pilbrow R. G. , Syson B. J. 
Published: February 2015

Encapsulated thermochromic liquid crystal (TLC) can be used to measure the surface temperature of stationary or rotating bodies. However, some research workers have reported a “rotational shift”; when the temperature of a rotating body is measured by thermocouples and TLC, there is a difference between the two sets of temperatures, and this difference increases with increasing rotational speed.
Two research groups (Camci and Glezer in the USA, and Owen, Pilbrow and Syson in the UK) have independently examined the effect of speed on TLC applied to the surfaces of rotating disks. The USA group used narrow-band TLC on a disk of 305-mm diameter rotating up to 7500 rev/min, measuring the surface temperature using an infra-red (IR) sensor. The UK group used wide-band TLC on a disk of 580-mm diameter rotating up to 7000 rev/min, measuring the temperature with an IR thermal imager. Both groups used the so-called hue technique to evaluate the temperature of the TLC and concluded that, even for centripetal accelerations in excess of 104g, there is no significant effect of rotational speed on either narrow-band or wide-band TLC. It is suggested that the “rotational shift” observed by some researchers was probably caused by thermal-disturbance errors, which affected the thermocouples, rather than by changes in the TLC.
Design and Test of a New Axial Compressor for the Nuovo Pignone Heavy Duty Gas Turbines
Authors: Benvenuti Erio 
Published: February 2015

This axial compressor design was primarily focused to increase the power rating of the current Nuovo Pignone PGT10 Heavy-Duty gas turbine by 10%. In addition, the new 11-stage design favourably compares with the existing 17-stage compressor in terms of simplicity and cost. By seating the flowpath and blade geometry, the new aerodynamic design can be applied to gas turbines with different power ratings as well. The reduction in the stage number was achieved primarily through the meridional flow-path redesign. The resulting higher blade peripheral speeds achieve larger stage pressure ratios without increasing the aerodynamic loadings. Wide chord blades keep the overall length unchanged thus assuring easy integration with other existing components.
The compressor performance map was extensively checked over the speed range required for two-shaft gas turbines. The prototype unit was installed on a special PGT10 gas turbine setup, that permitted the control of pressure ratio independently from the turbine matching requirements. The flowpath instrumentation included strain-gages, dynamic pressure transducers and stator vane leading edge aerodynamic probes to determine individual stage characteristics. The general blading vibratory behavior was proved fully satisfactory. With minor adjustments to the variable stator settings the front stage aerodynamic matching was optimized and the design performance was achieved.
How to Get Component Maps for Aircraft Gas Turbine Performance Calculations
Authors: Kurzke Joachim 
Published: February 2015

Precise simulations of gas turbine performance cannot be done without component maps. In the early days of a new project one often has to use scaled maps of similar machines. Alternatively one can calculate the component partload characteristics provided that the many details needed for such an exercise are available. In a later stage often rig tests will be done to get detailed information about the behavior of the compressors respectively turbines.
Performance calculation programs usually require the map data in a specific format. To produce this format needs some preprocessing. Measured data cannot be used directly because they show a scatter and they are not evenly distributed over the range of interest. Due to limitations in the test equipment often there is lack of data for very low and very high speed.
With the help of a specialized drawing program available on a PC one can easily eliminate the scatter in the data and also inter- and extrapolate additional lines of constant corrected speed. Many graphs showing both the measured data and the lines passing through the data as a function of physically meaningful parameters allow to check whether the result makes sense or not. The extrapolation of compressor maps toward very low speed, as required for the calculation of starting, idle and windmilling performance calculations, is discussed in some detail.
Instead of true measured data one can use data read from maps published in open literature. The program is also an excellent tool for checking and extending component maps one has derived from sparse information about a gas turbine to be simulated.
Effect of Aspect Ratio on the Buoyancy Driven Reverse Flow Near the Leading Wall of Rotating Cooling Passages
Authors: Tekriwal Prabhat 
Published: February 2015

The present work is concerned with the flow reversal phenomenon that is caused by the centrifugal buoyancy forces in the case of three-dimensional radially outward flow through rectangular ducts rotating in orthogonal mode. Due to the flow reversal, regions of zero to low fluid velocity (stagnation) are created near the leading wall and the heat transfer, consequently, is impaired causing concerns for the design engineers. Three duct cross-sections of the same hydraulic diameter but different aspect ratios (1:1, 2:1 and 3.33:1) have been examined in this numerical study for flows at different rotation numbers and different temperature ratios. The rotation number examined ranged from 0.08 to 0.35. For each rotation number the temperature ratio is increased until the flow reversal phenomenon is observed in the CFD predictions. For all the three ducts, computations have been carried out for Reynolds number equal to 80,000. The onset of the flow reversal near the leading wall and at the exit of the single-pass flow passage is studied with the buoyancy number variation.
As the aspect ratio is increased while keeping the duct hydraulic diameter fixed, the buoyancy number required to cause the onset of flow reversal decreases. Also, for each of the three ducts examined it has been found that the buoyancy number required for the predicted reverse flow to occur increases as the rotation number is increased.