bluuebunny/crossref_metadata_2025 huggingface dataset:
Allergic bronchopulmonary aspergillosis in children
Authors: Zhou Yunlian , Xu Dan , Zhang Yuanyuan , Sheng Yuanjian , Chen Xiaoyou , Chen Zhimin
Published: February 2015

Allergic bronchopulmonary aspergillosis (ABPA) is a disease of the lungs resulting from a hypersensitivity reaction to spores of Aspergillus fumigatus. Here we report the case of a 13‐year‐old girl with ABPA who presented with productive cough, bronchiectasis and decline in lung function, and review the clinical features and treatment for pediatric ABPA.
Relative Identity
Authors: Noonan Harold W.
Published: February 2015

Examples suggest that one and the same A may be different Bs, and hence that there is some sort of incompleteness in the unqualified statement that x and y are the same which needs to be eliminated by answering the question “the same what?” One way to make this more precise is by appeal to Geach's idea that identity is relative. In this paper I evaluate Geach's relative identity thesis.
Large‐scale insertional mutagenesis of Chlamydomonas supports phylogenomic functional prediction of photosynthetic genes and analysis of classical acetate‐requiring mutants
Authors: Dent Rachel M. , Sharifi Marina N. , Malnoë Alizée , Haglund Cat , Calderon Robert H. , Wakao Setsuko , Niyogi Krishna K.
Published: February 2015

Chlamydomonas reinhardtii is a unicellular green alga that is a key model organism in the study of photosynthesis and oxidative stress. Here we describe the large‐scale generation of a population of insertional mutants that have been screened for phenotypes related to photosynthesis and the isolation of 459 flanking sequence tags from 439 mutants. Recent phylogenomic analysis has identified a core set of genes, named GreenCut2, that are conserved in green algae and plants. Many of these genes are likely to be central to the process of photosynthesis, and they are over‐represented by sixfold among the screened insertional mutants, with insertion events isolated in or adjacent to 68 of 597 GreenCut2 genes. This enrichment thus provides experimental support for functional assignments based on previous bioinformatic analysis. To illustrate one of the uses of the population, a candidate gene approach based on genome position of the flanking sequence of the insertional mutant CAL027_01_20 was used to identify the molecular basis of the classical C. reinhardtii mutation ac17. These mutations were shown to affect the gene PDH2, which encodes a subunit of the plastid pyruvate dehydrogenase complex. The mutants and associated flanking sequence data described here are publicly available to the research community, and they represent one of the largest phenotyped collections of algal insertional mutants to date.
Improvement in Bilateral Carpal Valgus Deviation in 9 Foals After Unilateral Distolateral Radial Periosteal Transection and Elevation
Authors: Baker William True , Slone Donnie E. , Ramos Jose A. , Santschi Elizabeth M. , Lord Linda K. , Adams Stephen B. , Lynch Timothy M. , Hughes Faith E.
Published: February 2015

Objectives

To evaluate the effect of periosteal transection and elevation in foals with naturally occurring carpal valgus deviation.

Study Design

Prospective clinical study.

Animals

Foals (n = 9) with bilateral carpal valgus.

Methods

Foals with bilateral carpal valgus had distolateral radial periosteal transection and elevation (PE) including distal ulnar transection on 1 limb. Foals were stall confined until the skin incisions healed, and then allowed free exercise in a small paddock or round pen. Dorsopalmar carpal radiographs were obtained at 14 day intervals to determine the carpal valgus angle (CVA) until it was <5°.

Results

All limbs had a reduction in CVA and there was no significant difference in total carpal valgus angular correction or the rate at which the correction occurred between the surgical and control limb.

Conclusions

Unilateral distolateral radial PE had no effect on carpal angulation in 9 foals with naturally occurring bilateral carpal valgus deviation when performed between 19 and 43 days.
A Rotating Laser-Doppler Anemometry System for Unsteady Relative Flow Measurements in Model Centrifugal Impellers
Authors: Abramian M. , Howard J. H. G.
Published: February 2015

The behaviour of the relative flow in centrifugal turbomachines is extremely complex due to the existence of various fluid dynamic phenomena and their interaction. At design and off-design operating conditions, the relative flow is subject to stationary unsteadiness which includes the flow separation and wakes associated with passage pressure gradients, secondary flows, and boundary layer stability. It is also subject to periodic unsteadiness from the rotating stall and the cyclic flow phenomena induced by the casing.

This paper describes the mechanical and optical design of a rotating laser-Doppler anemometry system which allows direct measurement of the relative flow by means of an optical de-rotator. By isolating the impeller rotational frequency from the sampling frequency, it allows direct time-average measurements of the stationary behaviour of the relative flow along with the ensemble (phase)-average measurements of its periodic behaviour. Its success is demonstrated with measurements conducted in a low specific speed centrifugal impeller fitted with a single volute. Sample results of the time-averaged blade-to-blade variation of total relative velocities along with their associated turbulence intensities are reported. The (periodic) cyclic variations of the impeller exit flow, induced by the volute at low flow rates, are also presented for the suction and pressure sides.
Viscous Analysis of Three-Dimensional Rotor Flow Using a Multigrid Method
Authors: Arnone A.
Published: February 2015

A three-dimensional code for rotating blade-row flow analysis has been developed. The space discretization uses a cell-centered scheme with eigenvalues scaling for the artificial dissipation. The computational efficiency of a four-stage Runge-Kutta scheme is enhanced by using variable coefficients, implicit residual smoothing, and a full-multigrid method.

An application is presented for the NASA rotor 67 transonic fan. Due to the blade stagger and twist, a zonal, non-periodic H-type grid is used to minimize the mesh skewness. The calculation is validated by comparing it with experiments in the range from the maximum flow rate to a near-stall condition. A detailed study of the flow structure near peak efficiency and near stall is presented by means of pressure distribution and particle traces inside boundary layers.
Measurements of the Flow Field Within a Compressor Outlet Guide Vane Passage
Authors: Carrotte J. F. , Young K. F. , Stevens S. J.
Published: February 2015

A series of tests have been carried out to investigate the flow in a Compressor Outlet Guide Vane (OGV) blade row downstream of a single stage rotor. The subsequent flow field that developed within an OGV passage was measured, at intervals of 10% axial chord, using a novel design of miniature 5 hole pressure probe. In addition to indicating overall pressure levels and the growth of regions containing low energy fluid, secondary flow features were identified from calculated axial vorticity contours and flow vectors. Close to each casing the development of classical secondary flow was observed, but towards the centre of the annulus large well defined regions of opposite rotation were measured. These latter flows were due to the streamwise vorticity at inlet to the blade row associated with the skewed inlet profile. Surface static pressures were also measured and used to obtain the blade pressure force at 3 spanwise locations. These values were compared with the local changes in flow momentum calculated from the measured velocity distributions. With the exception of the flow close to the outer casing, which is affected by rotor tip leakage, good agreement was found between these quantities indicating relatively weak radial mixing.
Control of the Unsteady Flow in a Stator Blade Row Interacting With Upstream Moving Wakes
Authors: Valkov T. , Tan C. S.
Published: February 2015

A computational approach, based on a spectral-element Navier-Stokes solver, has been applied to the study of the unsteady flow arising from wake-stator interaction. Direct, as well as turbulence-model calculations, provide insight into the mechanics of the unsteady flow and demonstrate the potential for controlling its effects. The results show that the interaction between the wakes and the stator blades produces a characteristic pattern of vortical disturbances, which have been correlated to the pressure fluctuations. Within the stator passage, the wakes migrate towards the pressure surface where they evolve into counter-rotating vortices. These vortices are the dominant source of disturbances over the pressure surface of the stator blade. Over the suction surface of the stator blade, the disturbances are due to the distortion and detachment of boundary layer fluid. They can be reduced by tailoring the blade loading or by applying non-uniform suction.
Gas Turbine Inlet Air Treatment: A New Technology
Authors: Donle David W. , Kiefer Robert C. , Wright Thomas C. , Bertolami Ugo A. , Hill Denis G.
Published: February 2015

This paper describes the development, application, and performance verification of a new patented technology for cleaning and cooling combustion air to a gas turbine. A two (2) year in-depth research program at Dow Chemical Company in Freeport, Texas resulted in the development of this technology. At the conclusion of the research and development program, full-scale application of the hardware was made on a 100 MW combined cycle gas turbine, and its performance monitored for two (2) years. Application of the new technology resulted in increased power output, higher reliability, NOx emission reduction, reduced maintenance costs, and higher total system efficiency. Since the new technology has produced very large cost savings, Dow is using the new technology on three new combined cycle machines currently being installed, and further is exploring conversion of existing combined cycle gas turbines to this new technology.
Through-Flow Analysis for Axial-Stage Design Including Streamline-Slope Effects
Authors: Korakianitis Theodosios , Zou Dequan
Published: February 2015

This paper presents a new method to design (or analyze) subsonic or supersonic axial compressor and turbine stages and their three-dimensional velocity diagrams from hub to tip by solving the three-dimensional radial-momentum equation. Some previous methods (matrix through-flow based on the streamfunction approach) can not handle locally supersonic flows, and they are computationally intensive when they require the inversion of large matrices. Other previous methods (streamline curvature) require two nested iteration loops to provide a converged solution: an outside iteration loop for the mass-flow balance; and an inside iteration loop to solve the radial momentum equation at each flow station. The present method is of the streamline-curvature category. It still requires the iteration loop for the mass-flow balance, but the radial momentum equation at each flow station is solved using a one-pass numerical predictor-corrector technique, thus reducing the computational effort substantially. The method takes into account the axial slope of the streamlines. Main design characteristics such as the mass-flow rate, total properties at component inlet, hub-to-tip ratio at component inlet, total enthalpy change for each stage, and the expected efficiency of each streamline at each stage are inputs to the method. Other inputs are the radial position and axial velocity component at one surface of revolution through the axial stages. These can be provided for either the hub, or the mean, or the tip location of the blading. In addition the user specifies the azimuthal deflection of the flow from the axial direction at each radius (or as a function of radius) at each blade row inlet and outlet. By construction the method eliminates radial variations of total enthalpy (work) and entropy at each blade row inlet and outlet. In an alternative formulation enthalpy variations across radial positions at each axial station are included in the analysis. The remaining three-dimensional velocity diagrams from hub to tip, and the radial location of the remaining streamlines, are obtained by solving the momentum equation using a predictor-corrector method. Examples for one turbine and one compressor design are included.
Comparative Evaluation of Combined Cycles and Gas Turbine Systems With Water Injection, Steam Injection and Recuperation
Authors: Bolland Olav , Stadaas Jan Fredrik
Published: February 2015

Combined cycles have gained widespread acceptance as the most efficient utilization of the gas turbine for power generation, particularly for large plants. A variety of alternatives to the combined cycle that recover exhaust gas heat for re-use within the gas turbine engine have been proposed and some have been commercially successful in small to medium plants. Most notable has been the steam injected, high-pressure aero-derivatives in sizes up to about 50 MW. Many permutations and combinations of water injection, steam injection, and recuperation, with or without intercooling, have been shown to offer the potential for efficiency improvements in certain ranges of gas turbine cycle design parameters.

A detailed, general model that represents the gas turbine with turbine cooling has been developed. The model is intended for use in cycle analysis applications. Suitable choice of a few technology description parameters enables the model to accurately represent the performance of actual gas turbine engines of different technology classes. The model is applied to compute the performance of combined cycles as well as that of three alternatives. These include the simple cycle, the steam injected cycle and the dual-recuperated intercooled aftercooled steam injected cycle (DRIASI cycle). The comparisons are based on state-of-the-art gas turbine technology and cycle parameters in four classes: large industrial (123–158 MW), medium industrial (38–60 MW), aeroderivatives (21–41 MW) and small industrial (4–6 MW). The combined cycle’s main design parameters for each size range are in the present work selected for computational purposes to conform with practical constraints.

For the small systems, the proposed development of the gas turbine cycle, the DRIASI cycle, are found to provide efficiencies comparable or superior to combined cycles, and superior to steam injected cycles. For the medium systems, combined cycles provide the highest efficiencies but can be challenged by the DRIASI cycle. For the largest systems, the combined cycle was found to be superior to all of the alternative gas turbine based cycles considered in this study.
Stall Testing and Analysis of Two Mixed Flow Turbofans
Authors: Gallops G. W. , Roadinger T. J. , French J. V.
Published: February 2015

The results of an engine stall test and analysis program are described illustrating stall inducing phenomena, surge blowdown and repressurization, rotating stall inception and recovery, component interactions and install component characteristics. The data provide insight into the factors related to the real engine environment that affect the compression system stall inception, development and recovery processes. The results indicate that component system dynamic and aerodynamic interactions can dominate these processes.
Effects of Elevated Free-Stream Turbulence on Flow and Thermal Structures in Transitional Boundary Layers
Authors: Zhou Dadong , Wang Ting
Published: February 2015

The effects of elevated free-stream turbulence on flow and thermal structures in transitional boundary layers were investigated experimentally on a heated flat plate. Detailed boundary layer measurements using a three-wire probe and wall heat transfer were made with free-stream turbulence intensities of 0.5, 3.8, 5.5 and 6.4 percent respectively. The onset of transition, transition length and the turbulent spot formation rate were determined. The statistical results of the streamwise and cross-stream velocity fluctuations, temperature fluctuation, Reynolds stresses and Reynolds heat fluxes were presented. The eddy viscosity, turbulent thermal diffusivity and the turbulent Prandtl number were calculated and related physical mechanisms are discussed.
Induced Draft Fan Innovation for Heat Recovery Steam Generators
Authors: Beasley O. W. , Hutchins E. C. , Predick P. R. , Vavrek J. M.
Published: February 2015

A first of its kind, induced draft (ID) heat recovery steam generators (HRSG) have been in service at a cogeneration facility since 1991.

A preliminary engineering study considered a forced draft (FD) fan to supply combustion air to the HRSG duct burners (when the combustion turbine (CT) is out of service) as a traditional design; however, the study indicated that the FD fan may require the HRSG duct burner to be shut off following a CT trip and reignited after the FD fan was in service. Although the induced draft HRSG design cost more than the FD fan design, the induced draft design has improved the cogeneration facility’s steam generation reliability by enabling the HRSG to remain in service following a CT trip.

This paper briefly summarizes the preliminary engineering study that supported the decision to select the ID fan design. The paper also discusses the control system that operates the fresh-air louvers, duct burners, HRSG and ID fan during a CT trip. Startup and operating experiences are presented which demonstrate the effectiveness of the design. Lessons learned are also summarized for input into future induced draft HRSG designs.
External Heat Transfer Enhancement to Turbine Blading due to Surface Roughness
Authors: Tarada F. , Suzuki M.
Published: February 2015

This paper addresses the influence of surface roughness on the heat transfer to gas turbine blading. A survey of fifty eight industrial and aero-engine blades is reported which indicates the trends in surface roughness with service hours and operating environment. A detailed boundary layer roughness model, incorporating a low Reynolds Number k-ε turbulence model, is then presented. The model is calibrated with respect to the heat transfer measurements of Hosni et al (1989). Predictions are then made of the rough-blade heat transfer measurements of Turner et al (1985), which show that the increased heat load to the blading is reasonably well predicted by the proposed model.
Prediction of Film Cooling by Discrete-Hole Injection
Authors: Zhou Jian-ming , Salcudean Martha , Gartshore Ian S.
Published: February 2015

This paper presents a study on film cooling performance resulting from injection through a single row and alternatively through two staggered rows of holes onto a flat plate. The objective is to use an appropriate computational method for the simulation of the film cooling process in order to improve our understanding of the complex flow and heat transfer phenomena downstream of the coolant injection holes. A multi-grid and segmentation method is used to solve the transport equations of the film cooling process to achieve good local flow resolution and rapid convergence. The turbulence is represented by the k-ϵ model combined with a nonisotropic eddy-viscosity formulation and a near-wall k model. New experimental results are obtained for comparison with the numerical simulations. Cooling through single and double rows of orifices is investigated computationally; for the same overal mass injection, the double row cooling has better spanwise averaged film cooling effectiveness for the range of parameters investigated. The effects of mass flow ratios and injection angles on the double row cooling performance are investigated computationally. Comparison between the predicted and measured spanwise averaged effectiveness shows good agreement for mass flow ratios of 0.2 and 0.4 but also shows that the numerical values are consistently lower than the measured results for mass flow ratios of 0.8. This difference suggests that the k-ϵ turbulence model under-predicts the turbulence production resulting from the shear flow between the main stream and jets when the cross flow momentum is high and the associated streamwise vorticity is strong and therefore that the turbulence stresses and scalar fluxes are not correctly predicted in these cases. Some possible improvements are suggested.
Some Effects of Coolant Density on Film Cooling Effectiveness
Authors: Gartshore Ian S. , Salcudean Marthe , Barnea Y. , Zhang K. , Aghadsi F.
Published: February 2015

Experiments have been conducted on a large wind tunnel model of the leading edge region of a turbine blade. The model had a semi-circular leading edge in which four rows of holes were symmetrically placed about the stagnation line, two at ±15° and two at ±44°. Air and alternatively CO2 were injected from the coolant holes after contamination with a known small percentage of propane. Using a flame ionization detector and the mass transfer analogy, the film cooling effectiveness was measured at various overall mass flow ratios and at various streamwise locations for each coolant type. The division of coolant flow rate from the two rows of holes was found to be more unequal for CO2 than for air, an effect which is predicted from a simple analysis of the coolant/free stream interaction and the hole discharge coefficient. This has practical implications for actual turbine operation since earlier cut-off of the coolant from the front row of holes, due to density differences, could have disastrous effects on the blade. This effect also further complicates any attempt to identify overall trends of coolant density on performance. It is not possible to conclude that air or CO2 coolant has a higher film cooling effectiveness, although, in general, air appears better close to the first row of holes, and CO2 better at some distance downstream of both rows. Based on the measurements, the effects of mass flow ratio, momentum flux ratio, relative hole placement in each row, and spanwise versus streamwise injection are discussed in the paper.
Heat Transfer in Film-Cooled Turbine Blades
Authors: Garg Vijay K. , Gaugler Raymond E.
Published: February 2015

In order to study the effect of film cooling on the flow and heat transfer characteristics of actual turbine blades, a three-dimensional Navier-Stokes code has been developed. An existing code (Chima and Yokota, 1990) has been modified for the purpose. The code is an explicit finite difference code with an algebraic turbulence model. The thin-layer Navier-Stokes equations are solved using a general body-fitted coordinate system. The effects of film cooling have been incorporated into the code in the form of appropriate boundary conditions at the hole locations on the blade surface. Each hole exit is represented by several control volumes, thus providing an ability to study the effect of hole shape on the film-cooling characteristics. Comparison with experimental data is fair. Further validation of the code is required, however, and in this respect, there is an urgent need for detailed experimental data on actual turbine blades.
Application of Computational Fluid Dynamics to Turbine Disc Cavities
Authors: Virr G. P. , Chew J. W. , Coupland J.
Published: February 2015

A CFD code for the prediction of flow and heat transfer in rotating turbine disc cavities is described and its capabilities demonstrated through comparison with available experimental data. Application of the method to configurations typically found in aeroengine gas turbines is illustrated and discussed.

The code employs boundary-fitted coordinates and uses the k-ε turbulence model with alternative near-wall treatments. The wall function approach and a one-equation near-wall model are compared and it is shown that there are particular limitations in the use of wall functions at low rotational Reynolds number. Validation of the code includes comparison with earlier CFD calculations and measurements of heat transfer, disc moment and fluid velocities.

It is concluded that, for this application CFD is a valuable design tool capable of predicting the flow at engine operating conditions thereby offering the potential for reduced engine testing through enhanced understanding of the physical processes.
A Bypass Transition Model for Boundary Layers
Authors: Johnson Mark W.
Published: February 2015

Experimental data for laminar boundary layers developing below a turbulent free stream shows that the fluctuation velocities within the boundary layer increase in amplitude until some critical level is reached which initiates transition. In the near wall region, a simple model, containing a single empirical parameter which depends only on the turbulence level and length scale, is derived to predict the development of the velocity fluctuations in laminar boundary layers with favourable, zero or adverse pressure gradients. A simple bypass transition model which considers the streamline distortion in the near wall region brought about by the velocity fluctuations suggests that transition will commence when the local turbulence level reaches approximately 23%. This value is consistent with experimental findings. This critical local turbulence level is used to derive a bypass transition prediction formula which compares reasonably with start of transition experimental data for a range of pressure gradients (λθ = −0.01 to 0.01) and turbulence levels (Tu = 0.2% to 5%).

Further improvement to the model is proposed through prediction of the boundary layer distortion, which occurs due to Reynolds stresses generated within the boundary layer at high free stream turbulence levels and also through inclusion of the effect of turbulent length scale as well as turbulence level.
Comparison of Conventional and Low Solidity Vaned Diffusers
Authors: Hohlweg William C. , Direnzi Gregory L. , Aungier Ronald H.
Published: February 2015

Test results are presented comparing the aerodynamic performance of single stage centrifugal compressors with thin flat plate, low solidity vaned diffusers to conventional thin vaned diffusers. The test data were acquired from a low Mach number process gas compressor and a high Mach number industrial air compressor. The data are all normalized relative to baseline vaneless diffuser results. Performance parameters of stability, head rise to surge, overload flow margin, and stage efficiency are compared. The low solidity vane inlet incidence angle is shown to be an important design parameter that influences both compressor operating range and efficiency.
Adaptive Unstructured 2D Navier-Stokes Solutions on Mixed Quadrilateral/Triangular Meshes
Authors: Connell Stuart D. , Holmes D. Graham , Braaten Mark E.
Published: February 2015

This paper presents a solution adaptive scheme for solving the Navier-Stokes equations on an unstructured mixed grid of triangles and quadrilaterals. The solution procedure uses an explicit Runge-Kutta finite volume time marching scheme with an adaptive blend of second and fourth order smoothing. The governing equations are solved in a 2D, axisymmetric or quasi-3D form.

In viscous regions quadrilateral elements are used to facilitate the one dimensional refinement required for the efficient resolution of boundary layers and wakes. The effect of turbulence is incorporated through using either a Baldwin-Lomax or k-ε turbulence model.

Solutions are presented for several examples that illustrate the capability of the algorithm to predict viscous phenomena accurately. The examples are a transonic turbine, a nozzle and a combustor diffuser.
A New Approach to the Description of the Off-Design Losses in Radial-Inflow Turbine Rotors
Authors: Schölch M.
Published: February 2015

The off-design behaviour of a radial-inflow turbine with pivotable nozzle vanes was measured. The turbine geometry is presented in figure 1. The losses produced in the rotor were determined over a wide range of operating conditions which were established by varying pressure ratio, speed of rotation of the rotor and the nozzle vane position.

Loss correlations proposed by other authors were used to approximate the measured losses. All correlations were only able to fit the results for a single nozzle position. None of the equations used gave a satisfactory approximation for all the operating points investigated. Therefore a new way of describing the rotor losses is presented and a physical explanation for the new correlation is given.
Experimental Determination of the Flow Field in the Tip Region of a LP-Steam Turbine
Authors: Zimmermann C. , Stetter H.
Published: February 2015

Pneumatic multihole probes were applied to determine the local flow field in the tip region of a LP–steam turbine. For three tip clearances measurements were carried out varying the operating point of the turbine from full to partial load each.

The maxima of the tip clearance flow and the resulting jetflow in the adjacent axial–radial diffusor show a strong dependency on the operating point, the width of the tip gap, and the axial distance to the rotor. In contrast, the radial extension of the jetflow is primarily influenced by the operating point and limited to the upper 10% of the flow channel. The leakage flow rate and the interaction with the main flow are increasing when widening the tip clearance which leads to a significant global efficiency deficit. In order to prevent a smooth flow through the tip gap, the design is changed by casing treatment upstream of the running wheel yielding a positive overlap of the gap. Its effect on the flow is investigated and compared to the other configurations of the turbine.
A Transfer Matrix Approach to Vibration Localization in Mistuned Blade Assemblies
Authors: Óttarsson Gísli , Pierre Christophe
Published: February 2015

A study of mode localization in mistuned bladed disks is performed using transfer matrices. The transfer matrix approach yields the free response of a general, mono-coupled, perfectly cyclic assembly in closed form. A mistuned structure is represented by random transfer matrices, and the expansion of these matrices in terms of the small mistuning parameter leads to the definition of a measure of sensitivity to mistuning. An approximation of the localization factor, the spatially averaged rate of exponential attenuation per blade-disk sector, is obtained through perturbation techniques in the limits of high and low sensitivity. The methodology is applied to a common model of a bladed disk and the results verified by Monte Carlo simulations. The easily calculated sensitivity measure may prove to be a valuable design tool due to its system-independent quantification of mistuning effects such as mode localization.
Experimental Study on Vibration of a Rotating Blade
Authors: Fan Y. C. , Ju M. S. , Tsuei Y. G.
Published: February 2015

The vibration of a rotating blade is investigated in this work. A rotor system is built and natural frequencies of the rotating blade are measured and compared with the numerical results from a finite element analysis. The experimental setup has a strain gage-based telemetry system and a piezoelectric shaker that rotates with the rotor. The finite element model of the beam is derived based on the Timoshenko beam theory. The effects of varying rotating speeds and stagger angles on the blade natural frequencies are studied. The results indicate that the natural frequencies calculated from the finite element model and the experimental values are in good agreement. It is found that the blade natural frequencies increase with the rotating speed in a nonlinear linear way. The effects of the stagger angle on the measured natural frequencies are not clear.
Steam-Injected Gas Turbine Analysis: Part I — Steam Rates
Authors: Rice Ivan G.
Published: February 2015

This paper presents a three-part analysis of steam-injected gas turbines (simple and reheat) as follows: Part I - Steam Rates, Part II - Steam Cycle Efficiency and Part III - Steam-ReGenerated Heat (RGH). The analysis is based on the same approach used for large-utility steam turbines where one pound of throttle steam is passed through the steam turbine, and where enthalpy points are determined along the steam path. Work output, heat input and turbine efficiency are thus determined from this data. When considering a gas turbine, the steam-injection flow is separated from the main gas stream for analysis. Dalton’s and Avogadros’ laws of partial pressure and gas mixtures are applied. Accurate analysis of heat input, partial pressure expansion and heat-rejection steam-enthalpy points are computed with steam-table software.
Behavior of Three-Dimensional Boundary Layers in a Radial Inflow Turbine Scroll
Authors: Hara Kazuo , Furukawa Masato , Inoue Masahiro
Published: February 2015

A detailed experimental investigation was carried out to examine the three-dimensional boundary layer characteristics in a radial inflow turbine scroll. Some basic flow phenomena and growth of secondary flow were also investigated. In the inlet region of the scroll, the incoming boundary layer begins to have the skewed nature, namely the radially inward secondary flow caused by the radial pressure gradient. From the inlet region to the one third of the scroll circumference, the secondary flow grows so strongly that the most of the low momentum fluid in the incoming boundary layer are transported to the nozzle region. The succeeding elimination of the low momentum fluid in the boundary layer suppresses growth of the boundary layer further downstream, where the boundary layer shows a similarity of velocity profile. The distributions of the boundary layer properties in the scroll correspond well to those of the flow properties at the nozzle. The behavior of the boundary layer in the scroll is found to affect the circumferential nonuniformity of the nozzle flow field.
Experimental and Numerical Study of the Time-Dependent Pressure Response of a Shock Wave Oscillating in a Nozzle
Authors: Ott P. , Bölcs A. , Fransson T. H.
Published: February 2015

Investigations of flutter in transonic turbine cascades have shown that the movement of unsteady normal shocks has an important effect on the excitation of blades. In order to predict this phenomenon correctly, detailed studies concerning the response of unsteady blade pressures versus different parameters of an oscillating shock wave should be performed, if possible isolated from other flow effects in cascades. In the present investigation the correlation between an oscillating normal shock wave and the response of wall mounted time-dependent pressure transducers was studied experimentally in a nozzle with fluctuating back pressure. Excitation frequencies between 0 Hz and 180 Hz were investigated.

For the measurements, various measuring techniques were employed. The determination of the unsteady shock position was made by a line scan camera using the Schlieren flow visualization technique. This allowed the simultaneous use of unsteady pressure transducers to evaluate the behavior of the pressure under the moving shock.

A numerical code, based on the fully unsteady Euler equations in conservative form, was developed to simulate the behavior of the shock and the pressures.

The main results of this work were:

• The boundary layer over an unsteady pressure transducer has a quasi-steady behavior with respect to the phase lag. The pressure amplitude depends on the frequency of the back pressure.

• For the geometry investigated the shock amplitude decreased with increasing excitation frequency.

• The pressure transducer sensed the arriving shock before the shock had reached the position of the pressure transducer.

• The computed unsteady phenomena agree well with the results of the measurements.
Engineering Considerations of Gas Turbine/Waterjet Marine Propulsion Systems
Authors: Martin Paul , Blount Donald L.
Published: February 2015

The installation of gas turbines in high-speed marine vessels is relatively new in the merchant marine sector. The main objective of this paper is to present the engineering considerations that were taken into account during the design, testing and classification of the propulsion machinery of DESTRIERO, a high-speed, aluminum hull craft. This Blue Ribbon record-holding vessel will be the basis for, the discussion which will highlight the value of a detailed technical assessment of a vessel’s propulsion system early in the design process.

The DESTRIERO is a 67.7 meter aluminum monohull designed to cross the Atlantic ocean without refueling at a speed in excess of 50 knots in a sea state 4. During trial runs the vessel exceeded 65 knots. In August 1992 during its eastbound transit, the vessel earned the current non-stop Atlantic crossing speed record of 53.09 knots. The propulsion system is provided by three General Electric (GE) LM1600 gas turbines, each developing 20,740 IGHP (ISO base rating). The gas turbines drive three KaMeWa waterjets through a Renk Tacke reduction gearbox. Reverse thrust and steering are accomplished through the two outer jets. Each turbine and its auxiliaries are packaged in MTU modules, which are flexibly mounted to the ship’s structure.
Optimization of a Transonic Turbine Airfoil Using Artificial Intelligence, CFD and Cascade Testing
Authors: Shelton M. L. , Gregory B. A. , Lamson S. H. , Moses H. L. , Doughty R. L. , Kiss T.
Published: February 2015

A transonic turbine airfoil design is optimized using an artificial intelligence engineering design shell coupled with an inviscid, adaptive grid, CFD solver. The objective of the optimization is to minimize the downstream static pressure variation resulting from the trailing edge shock structure. Cascade test results verify the analytical predictions. Techniques are described which were used to couple the optimization shell to the 2-D turbine airfoil shape to allow the search for optimal designs and indicate the quality of those designs. The emphasis of the discussion is upon the application of these techniques rather than the physical details of the resulting blade design.
Real-Time Economic Optimization
Authors: Dierauf Timothy A. , Hanawalt Steven J. , Hinrichs James M.
Published: February 2015

The objective of this paper is to describe the development and commissioning process of a real-time, computerized, performance and economic management system used in optimizing combined cycle power plants. The scope of the paper will include a description of the process of modeling the plant economic and performance characteristics, as well as the motivation behind real-time economic optimization in the power industry today.
Advanced Ceramic Technology Developed for Industrial 300kW CGT (Ceramic Gas Turbine) Research and Development Project in Japan
Authors: Shimada Kazuaki , Ushijima Hiroyasu , Yabe Akira , Ogiyama Hisao , Tsutsui Yasukata
Published: February 2015

The characteristics and the points of innovation for the ceramic technology established in the Japanese national energy conservation project supported by Agency of Industrial Science and Technology (AIST) MITI, entitled “The 300kW Industrial Ceramic Gas Turbine Research and Development Project” have been cleared and reviewed. Especially, from the viewpoint of the role and the characteristics of the ceramic components, the progress of the three types of the ceramic gas turbines, which are: (a) “Regenerative Single–shaft Ceramic Gas Turbine for Cogeneration” (CGT–301); (b) “Regenerative Two–shaft Ceramic Gas Turbine for Cogeneration” (CGT–302) and (c) “Regenerative Two–shaft Ceramic Gas Turbine for Mobile Power Generation” (CGT–303), has been explained in parallel.

All ceramic components have already been manufactured for the turbine inlet temperature of 1200 deg C and tested as the components, which will be assembled and evaluated as the interim evaluation test in 1993. Especially, the characteristics of the ceramic components have been reviewed in several points such as the fabrication process for clearing the contrast among three types of ceramic gas turbine.
Optimization of Gas Turbine Engine Elements by Probability Criteria
Authors: Egorov I. N. , Kretinin G. V.
Published: February 2015

Procedure for the stochastic optimization of design parameters of gas turbine engine components for a prescribed level of production technology is discussed. Such combined criteria of the stochastic optimization as effectiveness-probability of realizing a design of an intricate technical object are proposed.

With reference to the task of optimum designing the rows of a multistage axial flow compressor, there are presented the results, obtained for various probability criteria, in parallel with conducting their comparative analysis, and there are also investigated optimum stable (robust) characteristics of designs obtained for various levels of technology. There are also demonstrated a possibility of a significant increase in probability to realize in actual practice the design, obtained in stochastic setting, as compared to the design, obtained in deterministic setting.
Present Status of Standardization for Fine Ceramics in Japan
Authors: Matsuhiro Keiji , Matsui Minoru
Published: February 2015

The commercialization of ceramic components for structural applications are continuing gradually, but not as quickly as expected. One of the obvious reasons is that a worldwide, common set of standard methods to compare and assure the ceramic component quality does not exist.

In order to solve this problem, Japan has set up cooperative activities industrial standards for the structural ceramics among the government, academia and industry. As of 1992, 16 methods of the standard testing procedure had been settled.

However, further work is needed, as at least another 203 standards are required. The following topics will be reviewed.

1. The relevant organizations, their task functions, and how they are co-working with each other.

2. Schedule of standardization settlement.

3. General steps involved in finishing a standard test method.

4. Present view on utilizing properties measured by standard methods of Japanese industry.

5. Future tasks to be solved.
Criteria for Design With Structural Materials in Combined-Cycle Applications Above 815°F
Authors: Swindeman Robert W. , Marriott Douglas L.
Published: February 2015

A number of materials issues related to the design of piping and support components in high-temperature fluidized bed combustor systems were examined. These issues included the availability of long-time design data on structural materials, the general character of the creep and stress rupture behavior, the performance of weldments, and the assessment of damage accumulation. Emphasis was placed on alloy 800H, but several other alloys were briefly examined for use at temperatures above 816°C (1500°F). It was concluded that the character of the creep curve ranged significantly with chemistry, processing variables, and environment, and that the specification of design allowable stresses and life estimation techniques must be approached with caution for service above 816°C (1500°F).
Discrete-Jet Film Cooling: A Comparison of Computational Results With Experiments
Authors: Leylek J. H. , Zerkle R. D.
Published: February 2015

Large scale computational analyses have been conducted and results compared with experiments to understand coolant jet and crossflow interaction in discrete–jet film cooling. Detailed three–dimensional elliptic Navier–Stokes solutions, with high order turbulence modeling, are presented for film cooling using a new model enabling simultaneous solution of fully coupled flow in plenum, film–hole, and cross–stream regions. Computations are carried out for the following range of film cooling parameters typically found in gas turbine airfoil applications: single row of jets with a film–hole length–to–diameter ratio of 1.75 and 3.5; blowing ratio from 0.5 up to 2; coolant–to–crossflow density ratio of 2; streamwise injection angle of 35 degrees; and pitch–to–diameter ratio of 3. Comparison of computational solutions with experimental data are in good agreement Moreover, the current results complement experiments and support previous interpretations of measured data and flow visualization. The results also explain important aspects of film cooling, such as the development of complex flow within the film–hole in addition to the well known counterrotating vortex structure in the cross–stream.
Influence of High Rotational Speeds on Heat Transfer and Oil Film Thickness in Aero Engine Bearing Chambers
Authors: Wittig S. , Glahn A. , Himmelsbach J.
Published: February 2015

Increasing the thermal loading of bearing chambers in modern aero engines requires advanced techniques for the determination of heat transfer characteristics. In the present study, film thickness and heat transfer measurements have been carried out for the complex two–phase oil/air flow in bearing chambers. In order to ensure real engine conditions, a new test facility has been built up, designed for rotational speeds up to n = 16000 rpm and maximum flow temperatures of Tmax = 473K. Sealing air and lubrication oil flow can be varied nearly in the whole range of aero engine applications. Special interest is directed towards the development of an ultrasonic oil film thickness measuring technique which can be used without any reaction on the flow inside the chamber. The determination of local heat transfer at the bearing chamber housing is based on a well known temperature gradient method using surface temperature measurements and a finite element code to determine temperature distributions within the bearing chamber housing. The influence of high rotational speed on the local heat transfer and the oil film thickness is discussed.
Effects of Embedded Vortices on Injectant From Film Cooling Holes With Large Spanwise Spacing and Compound Angle Orientations in a Turbulent Boundary Layer
Authors: Ligrani Phillip M. , Mitchell Stephen W.
Published: February 2015

Experimental results are presented which describe the effects of embedded, longitudinal vortices on heat transfer and film injectant downstream of a single row of film cooling holes with compound angle orientations. Holes are spaced 7.8 hole diameters apart in the spanwise direction so that information is obtained on the interactions between the vortices and the injectant from a single hole. The compound angle holes are oriented so that their angles with respect to the test surface are 30 degrees in a spanwise/normal plane projection, and 35 degrees in a streamwise/normal plane projection. A blowing ratio of 0.5 is employed and the ratio of vortex core diameter to hole diameter is 1.6–1.67 just downstream of the injection holes (x/d=10.2). At the same location, vortex circulation magnitudes range from 0.15 m2/s to 0.18 m2/s.

The most important conclusion is that local heat transfer and injectant distributions are strongly affected by the longitudinal embedded vortices, including their directions of rotation and their spanwise positions with respect to film injection holes. To obtain information on the latter, clockwise rotating vortices R0-R4 and counter-clockwise rotating vortices L0-L4 are placed at different spanwise locations with respect to the central injection hole located on the spanwise centerline. With vortices R0-R4, the greatest disruption to the film is produced by the vortex whose downwash passes over the central hole (R0). With vortices L0-L4, the greatest disruption is produced by the vortices whose cores pass over the central hole (L1 and L2). To minimize such disruptions, vortex centers must pass at least 1.5 vortex core diameters away from an injection hole on the upwash sides of the vortices and 2.9 vortex core diameters away on the downwash sides of the vortices. Differences resulting from vortex rotation are due to secondary flow vectors, especially beneath vortex cores, which are in different directions with respect to the spanwise velocity components of injectant after it exits the holes. When secondary flow vectors near the wail are in the same direction as the spanwise components of the injectant velocity (vortices R0-R4), the film injectant is more readily swept beneath vortex cores and into vortex upwash regions than for the opposite situation in which near-wall secondary flow vectors are opposite to the spanwise components of the injectant velocity (vortices L0-L4). Consequently, higher Stanton numbers are generally present over larger portions of the test surface with vortices R0-R4 than with vortices L0-L4.