bluuebunny/crossref_metadata_2025 huggingface dataset:
Clinical and histologic description of ocular anatomy in captive black‐tailed prairie dogs (Cynomys ludovicianus)
Authors: Meekins Jessica M. , Eshar David , Rankin Amy J. , Henningson Jamie N.
Published: March 2015

Objective

To describe the clinical and histologic ocular anatomy of the black‐tailed prairie dog (PD).

Animals studied

Seventeen captive black‐tailed PDs (11 males and six females), ranging in age from approximately 4 months to 4.5 years.

Procedures

Complete ocular examinations, including slit‐lamp biomicroscopy, direct and indirect ophthalmoscopy, were performed under isoflurane anesthesia. The globes (n = 2) of one black‐tailed PD were harvested immediately after euthanasia and processed after formalin fixation. Staining with hematoxylin–eosin, cytokeratin AE1/AE3, glial fibrillary acidic protein, chromogranin A, claudin‐5, smooth muscle actin, and vimentin was performed for light microscopic evaluation.

Results

A thick mucinous precorneal tear film was present on the ocular surface. A vestigial nictitating membrane was identified in the medial canthus area. The limbus was heavily pigmented, the iris was a dark homogenous brown, and the pupil was round. Funduscopically, there was no tapetum lucidum, the retinal vascular pattern was holangiotic, and a horizontally elongated optic disk was visualized. The most common ocular abnormalities were acquired eyelid margin defects, present in seven eyes of six black‐tailed PDs (35.3%). On histologic examination, the retina was asymmetric, thicker below the optic disk and thinner above it.

Conclusions

The black‐tailed PD fundus is atapetal with a holangiotic retinal vessel pattern and a horizontally elongated optic disk. Acquired lesions of the peri‐ocular and eyelid region were the most common documented abnormality. Unique anatomic features of the globe and adnexa were confirmed with histologic and immunohistochemical analysis.
Computational analysis of mutated AHAS in response to sulfonylurea herbicides
Authors: Choe M , Choe W , Lee I , Wu M , Liu S
Published: March 2015

Sulfonylurea (SU) herbicides that target acetohydroxyacid synthase (AHAS, also called acetolactate synthase (ALS)) are regarded as one of the most important classes of herbicides, due to their extremely low toxicity towards mammals, ultra‐low dosage application and high selectivity. However, mutations of AHAS to a herbicide‐insensitive form appear to be a worldwide problem for acquired resistance. In this study, three mutated AHAS sequences were used. In the mutated AHASs, the proline (Pro) was replaced by one of threonine (Thr), alanine (Ala) or serine (Ser) in AHAS amino acid (AA) position 197Pro. To understand the herbicide resistance mechanism, we built dimeric AHAS complex models based on 1YBH of protein data bank (PDB) with SU herbicide, chlorimuron ethyl (CIE), using a homology. The three mutated AHASs in complex with CIE were analysed, and the resistance mechanism to SU herbicides was studied by molecular dynamics (MD) simulation performed using GROMACS 4.5.5. MD simulation analysis of wild‐type and the three mutated dimeric AHAS–CIE complex systems revealed the conformational stability and changes in herbicide binding to dimeric AHAS system due to the mutation. Additionally, it showed that conformational change of amino acid residue 200Met (methionine) was associated with the imidazolinone herbicide resistance mechanism. According to our computation, the detailed mechanism of herbicide resistance was variable, depending on the type of mutated amino acid, providing new insights for designing herbicides specific to each mutant AHAS.
Accumulation of ceramide in slow‐twitch muscle contributes to the development of insulin resistance in the obese JCR:LA‐cp rat
Authors: Fillmore Natasha , Keung Wendy , Kelly Sandra E. , Proctor Spencer D. , Lopaschuk Gary D. , Ussher John R.
Published: March 2015

New Findings

What is the central question of this study?

The aim was to determine whether the accumulation of ceramide contributes to skeletal muscle insulin resistance in the JCR obese rat.

What is the main finding and its importance?

Our main new finding is that ceramides accumulate only in slow‐twitch skeletal muscle in the JCR obese rat and that reducing ceramide content in this muscle type by inhibition of serine palmitoyl transferase‐1 halts the progression of insulin resistance in this rat model predisposed to early development of type 2 diabetes. Our findings highlight the importance of assessing insulin signalling/sensitivity and lipid intermediate accumulation in different muscle fibre types.

It has been postulated that insulin resistance results from the accumulation of cytosolic lipid metabolites (i.e. diacylglycerol/ceramide) that impede insulin signalling and impair glucose homeostasis. De novo ceramide synthesis is catalysed by serine palmitoyl transferase‐1. Our aim was to determine whether de novo ceramide synthesis plays a role during development of insulin resistance in the JCR:LA‐cp obese rat. Ten‐week‐old JCR:LA‐cp obese rats were supplemented with either vehicle or the serine palmitoyl transferase‐1 inhibitor l‐cycloserine (360 mg l−1) in their drinking water for a 2 week period, and glycaemia was assessed by meal tolerance testing. Treatment of JCR:LA‐cp obese rats with l‐cycloserine improved their plasma glucose and insulin levels during a meal tolerance test. Examination of muscle lipid metabolites and protein phosphorylation patterns revealed differential signatures in slow‐twitch (soleus) versus fast‐twitch muscle (gastrocnemius), in that ceramide levels were increased in soleus but not gastrocnemius muscles of JCR:LA‐cp obese rats. Likewise, improved glycaemia in l‐cycloserine‐treated JCR:LA‐cp obese rats was associated with enhanced Akt and pyruvate dehydrogenase signalling in soleus but not gastrocnemius muscles, probably as a result of l‐cycloserine reducing elevated ceramides in this muscle type. Potential mechanisms of ceramide‐mediated insulin resistance involve activation of atypical protein kinase Cζ/λ and protein phosphatase 2A; however, neither of these was altered in muscles of JCR:LA‐cp obese rats. Our results suggest a key role for ceramide in the development of insulin resistance in the JCR:LA‐cp obese rat, while supporting serine palmitoyl transferase‐1 inhibition as a novel target for treatment of obesity‐associated insulin resistance.
Transport of Neutral Solute Across Articular Cartilage: The Role of Zonal Diffusivities
Authors: Arbabi V. , Pouran B. , Weinans H. , Zadpoor A. A.
Published: March 2015

Transport of solutes through diffusion is an important metabolic mechanism for the avascular cartilage tissue. Three types of interconnected physical phenomena, namely mechanical, electrical, and chemical, are all involved in the physics of transport in cartilage. In this study, we use a carefully designed experimental-computational setup to separate the effects of mechanical and chemical factors from those of electrical charges. Axial diffusion of a neutral solute (Iodixanol) into cartilage was monitored using calibrated microcomputed tomography (micro-CT) images for up to 48 hr. A biphasic-solute computational model was fitted to the experimental data to determine the diffusion coefficients of cartilage. Cartilage was modeled either using one single diffusion coefficient (single-zone model) or using three diffusion coefficients corresponding to superficial, middle, and deep cartilage zones (multizone model). It was observed that the single-zone model cannot capture the entire concentration-time curve and under-predicts the near-equilibrium concentration values, whereas the multizone model could very well match the experimental data. The diffusion coefficient of the superficial zone was found to be at least one order of magnitude larger than that of the middle zone. Since neutral solutes were used, glycosaminoglycan (GAG) content cannot be the primary reason behind such large differences between the diffusion coefficients of the different cartilage zones. It is therefore concluded that other features of the different cartilage zones such as water content and the organization (orientation) of collagen fibers may be enough to cause large differences in diffusion coefficients through the cartilage thickness.
An Adjustable-Length Intramedullary Nail: Development and Mechanical Evaluation in Cervine Tibiae
Authors: Throop Alexander D. W. , Clark Alexander Martin , Kuxhaus Laurel
Published: March 2015

Intramedullary nails are the gold standard of fracture fixation, yet problems can still arise due to their manufacture in discrete lengths. Patient outcomes are less favorable when implanted with an improper length nail, and the wide range of discrete length options can increase the size hospital inventory. Prototypes of adjustable-length intramedullary nails were developed and tested in axial compression, torsion, and four-point bending. These prototypes are comparable to conventional nails in axial and bending stiffness. The torsional stiffness of the prototypes is less than that of conventional nails, but may be sufficient for clinical use.
Galerkin Approximations for Stability of Delay Differential Equations With Distributed Delays
Authors: Sadath Anwar , Vyasarayani C. P.
Published: March 2015

Delay differential equations (DDEs) are infinite-dimensional systems, therefore analyzing their stability is a difficult task. The delays can be discrete or distributed in nature. DDEs with distributed delays are referred to as delay integro-differential equations (DIDEs) in the literature. In this work, we propose a method to convert the DIDEs into a system of ordinary differential equations (ODEs). The stability of the DIDEs can then be easily studied from the obtained system of ODEs. By using a space-time transformation, we convert the DIDEs into a partial differential equation (PDE) with a time-dependent boundary condition. Then, by using the Galerkin method, we obtain a finite-dimensional approximation to the PDE. The boundary condition is incorporated into the Galerkin approximation using the Tau method. The resulting system of ODEs will have time-periodic coefficients, provided the coefficients of the DIDEs are time periodic. Thus, we use Floquet theory to analyze the stability of the resulting ODE systems. We study several numerical examples of DIDEs with different kernel functions. We show that the results obtained using our method are in close agreement with those existing in the literature. The theory developed in this work can also be used for the integration of DIDEs. The computational complexity of our numerical integration method is O(t), whereas the direct brute-force integration of DIDE has a computational complexity of O(t2).
Incremental Forward Kinematics of Wire-Suspended Parallel Mechanical System (A Many-Worlds Interpretation Approach)
Authors: Hanahara Kazuyuki
Published: March 2015

In this paper, we discuss an incremental forward kinematics of wire-suspended mechanical systems. In order to deal with a mechanical system of this type, we have to take into account the characteristic property of a wire, in that it cannot take any compressive force. We give a general formulation and its solution of the incremental forward kinematics problem taking account of the slack condition of a wire. We also consider the influence of displacement of the mass center position of the suspended platform on the kinematic behavior of the system. An interval arithmetic approach is proposed to deal with the uncertainty in the kinematic parameters. One of the important points is that the number of possible solutions of the formulated incremental kinematics problem is often more than one. We introduce a kind of parallelism, referred to as the “many-worlds interpretation” taken from the quantum mechanics theory, to this problem and offer an approach to deal with plural possible kinematic states simultaneously. The developed approach is based on basic equations in general form and is applicable to various wire-suspended mechanical systems. The feasibility of the proposed incremental kinematics approach is demonstrated by example calculations of three-, six-, and eight-wire systems. On the basis of the example forward kinematics calculation results, we conclude the following. The influence of displacement of mass center position of the platform is not insignificant. The number of possible kinematic states becomes large in the case of the neighborhood of singular configuration. In spite of an incremental kinematics based on linearization, the required computational cost of the proposed parallelism approach is considerable; it is, however, demonstrated that the proposed approach is still fairly practical from the viewpoint of computation. The developed approach cannot deal with drastic change in kinematic configuration in a single incremental step, since it is based on linearization of the kinematic relation; however, the approach can distinguish such discontinuity.
Multitude of Objectives Based Optimum Designs of Cylindrical Roller Bearings With Evolutionary Methods
Authors: Tiwari Rajiv , Chandran Rahul M. P.
Published: March 2015

In the design of cylindrical roller bearings (CRBs), a long life is one of the most essential criteria. However, the life of bearings depends on the multitude of factors that includes the fatigue, lubrication, and thermal characteristics in bearings. In the present work, three primary objectives namely, the dynamic capacity, the elastohydrodynamic lubrication (EHL) minimum film-thickness, and the maximum temperature have been optimized, sequentially. Some of these objectives may be contradicting to each other. The optimum bearing design has been attempted by first deriving a constrained nonlinear formulation and then optimizing it with an evolutionary algorithm. Constraint violations study has been performed to have assessment of the effectiveness of each of the constraints. A convergence study has been carried out to ensure the near global optimum point in the design. In terms of the basic dynamic capacity of the bearing, there is an excellent conformity among the optimized and customary bearings. A sensitivity study of various geometric design variables has been performed to see changes in objective functions and results show that geometric variables have hardly any undesirable influence.
Dynamics of Rocking Semicircular, Parabolic, and Semi-Elliptical Disks: Equilibria, Stability, and Natural Frequencies
Authors: Mazzoleni Michael J. , Krone Michael B. , Mann Brian P.
Published: March 2015

This paper performs a theoretical and experimental investigation of the natural frequency and stability of rocking semicircular, parabolic, and semi-elliptical disks. Horace Lamb's method for deriving the natural frequency of an arbitrary rocking disk is applied to three shapes with semicircular, parabolic, and semi-elliptical cross sections, respectively. For the case of the semicircular disk, the system's equation of motion is derived to verify Lamb's method. Additionally, the rocking semicircular disk is found to always have one stable equilibrium position. For the cases of the parabolic and semi-elliptical disks, this investigation reveals a supercritical pitchfork bifurcation for changes in a single geometric parameter which indicates that the systems can exhibit bistable behavior. Comparisons between experimental validation and theory show good agreement.
The Blowout of Turbulent Jet Flames in Co-Flowing Streams of Fuel-Air Mixtures
Authors: Kibrya M. G. , Karim G. A. , Wierzba I.
Published: March 2015

The blowout limit of a turbulent jet diffusion flame in co-flowing streams of lean fuel air mixtures is examined. The blowout limit of the flame, and thereby the maximum thermal output of a burner can be extended significantly, without any modification to the burner, through the presence of a small amount of fuel homogeneously mixed with the surrounding air. The extent of this extension is related to the observed limit of fuel concentration in the surrounding stream that brings about flame flashback conditions. The flame blowout limits involving different gaseous hydrocarbon fuels have been established at atmospheric pressure and the data were correlated in terms of the surrounding fuel concentrations relative to their corresponding flashback limits.
Evaporation of Fuel Droplets in Turbulent Combustor Flow
Authors: Wittig S. , Klausmann W. , Noll B. , Himmelsbach J.
Published: March 2015

Detailed measurements of a recirculating, droplet charged air flow within a model combustor are compared with predictions based on three different evaporation models. Similar results are obtained with the simplified d2-law, the uniform temperature model and thin skin model for relatively short droplet-heatup phases. Discrepancies, however, are observed under conditions where the droplet heating phase is relatively long, i.e. at low temperature conditions. Extended evaporation models, therefore, are necessary when the ignition performance is to be analysed.
Effect of Stage Loading on Endwall Flows in an Axial Flow Compressor Rotor
Authors: Sitaram N.
Published: March 2015

This paper reports results from investigations conducted to determine the effect of stage loading on endwall flows in a low speed axial flow compressor. These investigations consisted of two sets of measurements. The first set consisted of radial tranverse of flow properties at the rotor inlet and exit, at five flow coefficients. These measurements are used to determined the boundary layer integral parameters. The displacement thicknesses at the rotor hub and tip agree reasonably well with Smith’s (1970) correlation for multistage axial compressors. The second set consisted of measurements of static pressures on the rotor blade at four flow coefficients. From these measurements lift coefficient is determined. Also loss of lift coefficient near the tip is calculated and is attributed mainly to the tip leakage flows.
Innovative Concepts for Auxiliary Power Generation on USN Ships
Authors: Bowen Thomas L. , Ness Jon C.
Published: March 2015

Auxiliary power generation to satisfy demands for electricity and pressurized air onboard naval ships represents a significant impact on the ship’s design and performance. These demands are continually growing as newer ships require improved capabilities and shipboard systems become more complex. This paper briefy examines options to the present use of multiple, simple-cycle, gas-turbine-driven generator sets on U.S. Navy destroyers and cruisers. Improved engines for ship service generator drive applications are considered which are presently available from industry or are adapations of presently available engines. The feasibility of producing an auxiliary gas turbine from components taken from an intercooled-recuperative propulsion gas turbine is examined, as well as an integrated gas turbine plant which allows auxiliary power to be supplied as power takeoff from the propulsion gas turbine. The paper describes some of the design and performance aspects of these alternative approaches as well as some of their advantages and disadvantages.
Dutch Legislation in NOx Emission Standards Applicable to Gas Turbines in Cogeneration Plants
Authors: Bousardt Ir. L. F. L. M.
Published: March 2015

The general growth, in recent years, for the decentralized generation of electricity in the Netherlands is shown in terms of capacity and numbers of gas turbines installed by Dutch industry. This growth trend in cogeneration capacity is projected to the year 2000. NOx emissions standards for gas turbine plants are discussed with particular reference to “acid rain”. The contribution to national NOx emissions of gas turbines is presented for the present and for year 2000. Compliance with these standards by metering (source testing and monitoring) and the results of field testing for NOx emissions are shown.
Numerical Predictions for the Flow Induced by an Enclosed Rotating Disc
Authors: Chew John W. , Vaughan Craig M.
Published: March 2015

Finite difference solutions are presented for turbulent flow in the cavity formed between a rotating and a stationary disc, with and without a net radial outflow of fluid. The mean flow is assumed steady and axisymmetric and a mixing length model of turbulence is used. Grid dependency of the solutions is shown to be acceptably small and results are compared with other workers’ experimental data. Theoretical and measured disc moment coefficients are in good agreement, while theoretical and measured velocities are in reasonable agreement. It is concluded that the mixing-length model is sufficiently accurate for many engineering calculations of boundary layer dominated flows in rotating disc systems.
Optimization Design of the Over-All Dimensions of Centrifugal Compressor Stage
Authors: Qinghuan Wang , Zhiqin Sun
Published: March 2015

A new procedure employed in computer-aided design of centrifugal compressor stage to determine its over-all dimensions is described in this paper. By the use of the COMPLEX METHOD, the arbitrary number of variables to be optimized can be specified to remove the hidden danger of the local optima which stems from adopting a few, for example two or three, variables to be optimized. This procedure is available for any complicated implicit nonlinear objective function and ensures establishment of a true optimum solution. Numerical calculations have been carried out by using the computer program described here to check the ability of the optimization method. The results obtained by the calculations agree fairly well with that obtained by experiments.
The Modernization of a 1965, MS5001, Gas Turbine: New Life for an Old Unit
Authors: Grondahl Clayton M. , Linnell Renard D. , Martin Tommy J.
Published: March 2015

Application of the GE MS5001 gas turbine performance improvement uprate package has been extended to an early model “K” unit at Texaco’s Convent, LA refinery. This extensive modification required replacement of the turbine shell in addition to the installation of new technology components developed for more recent MS5001 models.

This paper presents the customer’s motivation to refurbish a 22 year old gas turbine. Gas turbine component design improvements and interfaces are discussed with performance and reliability gains. Field service engineering experience installing the uprate is also related.
A Transient Flow Facility for the Study of the Thermofluid-Dynamics of a Full Stage Turbine Under Engine Representative Conditions
Authors: Ainsworth R. W. , Schultz D. L. , Davies M. R. D. , Forth C. J. P. , Hilditch M. A. , Oldfield M. L. G. , Sheard A. G.
Published: March 2015

The design and construction of a new experiment, to investigate the steady and unsteady heat transfer and aerodynamic behaviour of a rotating turbine in a transient facility, is described. The need for this experiment is discussed in the context of previous rotating bar wake and shock simulation work carried out in the Oxford transient cascade facility, and research elsewhere on the effects of rotating and three-dimensional flowfields on turbine aerodynamics and heat transfer.

The outline concept and mode of operation of the turbine module are given before novel features of the design are presented in detail. Reference is made to a parallel paper also presented at this conference[18] which gives full details of the developments that have been necessary to allow the measurement of steady and unsteady heat transfer in this facility.

Finally, the future work programme and possible plans for further facility improvements are given.
Investigation of Boundary Layer Transition and Separation in an Axial Turbine Cascade Using Glue-On Hot-Film Gages
Authors: Vijayaraghavan S. B. , Kavanagh P.
Published: March 2015

Experiments were conducted with glue-on hot-film gages in a large-scale axial turbine cascade to identify transition and/or separation on the suction surface of the blade. Standard strain-gage type temperature sensors were adapted and used as the gages and Transition and separation were identified by examining the mean and RMS voltage output. To assist with interpreting the output of the gages, surface oil-flow visualizations were used. Results of this study showed that transition and separation could be easily identified with the hot-film gages. Depending upon the Reynolds number and free stream turbulence level, the suction surface boundary layer was found to undergo bubble-induced transition, natural transition, or a combination of both; i.e, a transition which started naturally but ended abruptly with a bubble.
Notes on the Occurrence and Determination of Carbon Within Gas Turbine Combustors
Authors: Odgers J. , Magnan E. R.
Published: March 2015

Details are presented of two series of experiments to investigate carbon determination in gas turbine combustion chambers. The first series employed a gravimetric technique to examine carbon distribution within the various zones of a combustor with the aim of identifying zones of formation and oxidation.

In the second series a fairly comprehensive investigation of the technique of measuring Smoke Number was made with the objective of obtaining details relevant to its accuracy and applicability. Mixtures of iso-octane and benzene were used as fuel, thereby permitting the effects of hydrogen content to be established. The results are correlated with othersome obtained previously.
Gas Turbine Systems for World Navy Ships
Authors: Brady Eugene F.
Published: March 2015

The application of gas turbines for propulsion of navy ships for all nations continues to increase at an accelerating rate. World navies which use gas turbines include the United States, Great Britain, the Soviet Union and Japan. Therefore, a survey of the principal gas turbine applications in world navies was conducted.

This survey revealed that more than 43 world navies now use gas turbines for ship propulsion. It also indicated that more than 2,700 gas turbines have been (or soon will be) installed in world navy ships. This represents a total worldwide navy application exceeding 38 million installed horsepower.
Two Case Studies of Cogeneration in India
Authors: Shome S. K. , Ganguly P. K.
Published: March 2015

The steam and electric power requirement for an industrial complex can be integrated in a cogeneration system achieving improved efficiency at comparatively lower plant costs.

Various technical and economic parameters of a cogeneration plant in a petrochemical plant and a refinery in India are discussed. Both applications use industrial gas turbine and heat recovery boilers with supplementary firing using gaseous and/or liquid fuel.

For the petrochemical complex, two 25 MW (ISO) industrial gas turbines and two 75 tonnes/hr. heat recovery boilers with provision for supplementary firing were selected to meet the 37 MW power demand and 150 tonnes/hr. (low pressure, saturated) steam demand. The plant is designed for natural gas fuel. The unit tested better than guaranteed.

For the refinery application, two 25 MW (ISO) industrial gas turbines and two heat recovery boilers with supplementary firing were selected to meet a normal steam demand of 90 tonnes/hr. with a peak of 120 tonnes/hr. and a critical power demand of 15.6 MW with a normal demand of 22 MW. The fuel to be used is gas and/or distillate oil. The guaranteed plant efficiency was quoted as 79.25% (on L.H.V. basis). The plant is under construction and expected to go on line in early 1988.
The Oil-Free Shaft Line
Authors: Wagner Bruno
Published: March 2015

This paper recalls the principles and main features of the active magnetic bearings and especially the advantages for turbomachines. Oil-free working and vibration control are part of them.

Field experiences are described for different shaft line configurations. Step by step we are going to get totally rid of oil with the introduction of active magnetic bearings together with dry gas seals and gearless drive. Future machines will take the benefit of all this field experience. The trend of the design optimization is the active magnetic bearings in the process gas itself, for a length reduction of shafts. But at the present stage, the active magnetic bearing is a proven technology today.
1000 Hour Qualification Test of the Textron Lycoming TF40B Marine Gas Turbine Engine for the U.S. Navy LCAC Craft
Authors: Zoccoli Michael J.
Published: March 2015

This paper describes the qualification testing of the TF40B marine gas turbine in accordance with the duty cycle as specified in MIL-E-17341C, but with modifications that reflect the specific engine application to the U.S. Navy LCAC vehicle.

Among the particular requirements of the 1000 hour test are continuous operation in a salt-laden environment of given concentration and humidity, and frequent shutdowns from relatively high power with an ensuing soakback interval.

The narrative discusses the method of test, the duty cycle, and the results which were obtained.

In an epilogue which focuses on posttest activities, a description is given of the corrective actions taken to resolve certain problems that arose during the course of the test. One such problem, namely the occurrence of carbon erosion upon certain hot section components, was eliminated by modification to the combustor, in a very successful posttest test development program.
Brushes as High Performance Gas Turbine Seals
Authors: Ferguson J. G.
Published: March 2015

Brush seals are the first simple and practical alternative, to the finned labyrinth, for gas turbine air system seals. Their use has been made possible by a combination of innovative design features, combined with advanced materials and manufacturing techniques.

Due to the very high rubbing speeds and temperatures, existing in gas turbine air system seal positions, finned labyrinths have been used almost exclusively since the invention of the gas turbine. Development over the years has reduced their leakage flow to the ultimate, but leakage is very much dependent on clearance. A brush seal, replacing the best possible finned labyrinth seal, needing a clearance of 0.7mm, can reduce the flow to approximately 10% of that of the finned seal.

The main advantages of brush seals, therefore, are their dramatic improvement in sealing performance. This is combined, however, with their ability to maintain this performance even during and after transient differential movements. These advantages have been developed and demonstrated after many hours rig and engine running.

Back to back engine tests, with brush seals, replacing finned labyrinths in key air system seals, have demonstrated a significant improvement in thrust for a given stator outlet temperature (SOT).

Flight trials are in progress, on an engine fitted with brush seals, as a further step to their in service use.
New Erosion Resistant Compressor Coatings
Authors: Kolkman H. J.
Published: March 2015

Airfoils of gas turbines and jet engines frequently deteriorate by erosion or corrosion: Protection can be offered by special coatings that are resistant to either erosion or corrosion. However, the conventional corrosion resistant compressor coatings have very poor erosion resistance. Therefore there is a tendency to apply compressor coatings that offer protection against both erosion and corrosion.

The erosion resistance of (improved) conventional aluminium-based compressor coatings and of new TiN, Ti2B and WC coatings was determined at 150° C as a function of the angle of attack. The Ti2B coating had especially promising erosion resistance.
Acquisition of Unsteady Pressure Measurements From a High Speed Multi-Stage Compressor
Authors: Copenhaver William W. , Worland Christopher J.
Published: March 2015

Two methods for acquiring transient pressure measurements from a high speed multi-stage compressor are presented. Data were obtained from upstream, inter-stage and downstream measurement locations on the compressor during unsteady operation. The two methods of data acquisition were real time digital conversion of close coupled pressures and frequency modulated (FM) analog recording of high response measurements. The close coupled measurements provide for a nominal frequency response of 70 Hz while the high response measurements provided 200 Hz nominal response. A description of both acquisition systems is provided with discussion of the limitations involved in both methods. Examples and comparisons of data obtained by both methods are presented.
Real Time Neutron Radiography Applications in Gas Turbine and Internal Combustion Engine Technology
Authors: Lindsay John T. , Kauffman C. W.
Published: March 2015

Real Time Neutron Radiography (RTNR) is rapidly becoming a valuable tool for nondestructive testing and basic research with a wide variety of applications in the field of engine technology. The Phoenix Memorial Laboratory (PML) at the University of Michigan has developed a RTNR facility and has been using this facility to study several phenomena that have direct application to internal combustion and gas turbine engines. These phenomena include; 1) the study of coking and debris deposition in several gas turbine nozzles (including the JT8D), 2) the study of lubrication problems in operating standard internal combustion engines and in operating automatic transmissions (1, 2, 3), 3) the location of lubrication blockage and subsequent imaging of the improvement obtained from design changes, 4) the imaging of sprays inside metallic structures in both a two-dimensional, standard radiographic manner (4, 5) and in a computer reconstructed, three-dimensional, tomographic manner (2, 3), and 5) the imaging of the fuel spray from an injector in a single cylinder diesel engine while the engine is operating. This paper will show via slides and real time video, the above applications of RTNR as well as other applications not directly related to gas turbine engines.
Flow Measurements in Rotating Stall in a Gas Turbine Engine Compressor
Authors: Best R. C. , LaFlamme J. G. C. , Moffatt W. C.
Published: March 2015

For many years, there has been a significant effort, both experimental and theoretical, to better understand the rotating stall phenomenon. For very practical reasons, most of the experimental investigations have focussed on laboratory compressors with very low stage pressure ratios. The aim of the present study was to extend the range of available data to industrial-size compressors operating in a typical real life environment. This paper reports results of detailed flow measurements made on the first four stages of a 10 stage compressor operating as part of a turbojet engine mounted on a test stand. Hot sensor anemometer measurements made at a number of axial and tangential locations showed clear evidence of rotating stall in the front stages during part-speed operation of the engine. Stall cell configuration and rotative speed, and details of flow speed and angle at hub, mid and tip radii are presented in the paper. On the basis of the measurements it is concluded that (1) although rotating stall has its origins in a flow instability, it is a highly reproducible phenomenon, (2) reverse flow can occur within the cells, as has been reported by several other observers and (3) the cells retain an axial (as opposed to helical) configuration on passing from stage to stage through the compressor.
Theoretical Investigation of the Interaction Between a Compressor and the Components During Surge
Authors: Brumm Jürgen , Kalac Hassan , Teipel Ingolf
Published: March 2015

Problems of compressor instability have been of concern not only to aircraft engine designers but also for example to operators of industrial power plants. Two types of flow instabilities are known and in this paper only one of them, the surge phenomenon, will be discussed in detail. For the occurence of these heavy pressure fluctuations the volume of the neighbouring plenum chamber is the important quantity.

Here the basic compression system consisting of a compressor, a duct and a plenum will be analysed in order to show the complete unsteady pressure field. The theoretical model is based on the application of mass, momentum and energy conservation equations of one-dimensional flow. The set of differential equations of hyperbolic type is solved numerically by a ‘predictor-corrector’ scheme. The method itself is an explicit procedure first given by MacCormack /9/. At the interfaces between two components the coupling conditions for pressure and flow velocity are taken from the method of characteristics. The behaviour of the compressor is determined by its performance map, which describes the relationship between pressure and mass flux for all conditions from stable performance to inverse mass flow. For the dynamic change of the pressure development a special compressor characteristic taking into account the unsteady effects is used. This model function is chosen according to a time lagging element often employed in control theory.

To demonstrate the capability of the described method variations of different parameters such as mass flow rate, volume behind the compressor, ect. will be presented. The pressure-time history will be compared with experimental data published in the literature. Also the calculated surge frequencies, will be discussed. Furthermore it will be examined how a working point of the compressor moves from a stable part of the characteristic to another one, stable or unstable. Finally the general time dependent surge performance is considered in comparison to the quasi-steady characteristic.
On Predicting Steam Turbine Blading Erosion and Turbine Efficiency Deterioration
Authors: Krzyzanowski J. A.
Published: March 2015

Two-phase flow of wet steam is nowadays a subject of intensive research for different reasons. Prediction of erosion damage to turbine blading is one of important elements of this research. In the paper, a method of predicting this damage as a function of time is presented briefly. The emphasis is however put on the statistics of the accuracy of damage prediction as compared to field measurements. Also comments on erosion induced turbine efficiency deterioration are presented. The paper relates to the authors experience presented in references [1] and [2].
Comparison of Ceramic vs. Advanced Superalloy Options for a Small Gas Turbine Technology Demonstrator
Authors: Bornemisza T. , Napier J.
Published: March 2015

The next generation of small gas turbines used as compact Auxiliary Power Units (APUs) in aircraft and mobile ground power applications will achieve higher power density than current installations by operating at substantially higher turbine inlet temperatures. Ceramics vs. advanced/cooled superalloy designs are compared as alternate paths to improved performance through increased turbine inlet temperature for the T-100 MPSPU (Multi-purpose Small Power Unit) technology demonstrator engine currently under development.

Past experience at Sundstrand Turbomach in demonstrating ceramic and air cooled components is used to project level of success expected in meeting the demonstrator engine performance goals with either ceramics or advanced/cooled superalloy radial turbine nozzle and turbine wheel. The alternate designs are compared in terms of potential against such criteria as performance, power density and cost.
Review of Design Parameters in Gas Turbines for the Prospective User
Authors: Dundas Robert E.
Published: March 2015

This paper is based on five selected areas of gas turbine design that should be reviewed by prospective purchasers of gas turbines in the specification and procurement phase, in view of adverse industry experience associated with them. The details that should be requested and reviewed, and the criteria that should be met, are discussed. Case histories of adverse industry experience are provided for substantiation of the recommendations.

The design areas discussed are:

1. Compressor-blade resonance diagrams

2. Compressor performance maps

3. Turbine-blade resonance diagrams

4. Temperature profiles in turbine flowpath

5. Response to combustor flameout
Coal Oxidation
Authors: Raj S.
Published: March 2015

Coals contain considerable amounts of oxygen in their structures ranging from 30% in brown coal to about 1.5% in anthracites. The distribution of coal oxygen in various functionalities changes drastically with increasing rank. The hetero-atom functionalities in coal and coal products are of importance in the processing of coal. The process of coal conversion relevant to the steam and gas turbine applications are pyrolysis, oxidation and combustion processes. Initial stages of pyrolysis and oxidation (combustion) are the thermal decomposition of the solid coal matrix to free radicals. Oxygen, sulfur, nitrogen and mineral containing free radicals play an important role during combustion thermodynamically. The differences between the coal functionalities in the solid coal matrix contribute to oxidation reactions of first and second order. The first and second order reactions affect the corrosion and deposition rates of the machine components differently.

In this paper functionality differences of various coals with respect to their oxidation characteristics will be discussed.
Operating Experience With Type H Industrial Gas Turbines on North Sea Platforms
Authors: Cullen J. P.
Published: March 2015

The paper outlines the operating and maintenance experience of the TYPE H industrial gas turbines on 2 of the platforms in the Greater Ekofisk field on the Norwegian continental shelf.

Traditional preventive maintenance procedures based on elapsed fired hours are discussed. Availability and reliability statistics are presented.

Typical component replacement on inspections is tabulated and comments are given.

Finally the author describes an on line, computer supervised, condition monitoring system which is being used and will help replace traditional preventive maintenance with predictive maintenance.
A Secondary Flow Calculation Method Based on the Meridional Vorticity Transport Equation
Authors: Kaldellis J. , Douvikas D. , Papailiou K. D.
Published: March 2015

A secondary flow calculation method is presented in this work, which makes use of the meridional vorticity transport equation. Circumferentially mean flow quantities are calculated using an inverse procedure.

The method makes use of the mean kinetic energy integral equation and calculates simultaneously hub and tip secondary flow development. Emphasis is placed upon the use of a coherent two-zone model and particular care is taken in order to describe adequately the flow inside an unbounded (external), semi-bounded (annulus) and fully-bounded (bladed) space. The velocity field, the losses and the defect forces receive particular attention.

Comparison between theoretical and experimental results is presented.
Structural Design and its Improvements Through the Development of the XF3-30 Engine
Authors: Kikuchi Hidekatsu , Ishii Kiyoshi
Published: March 2015

The XF3-30 engine has been successfully completed its Qualification Test at March 1986 and the production has started as the powerplant for Japan Self Defence Force’s intermedeate trainer T-4. The first flight of the T-4 powered by two XF3-30 engine was made on the 29th July 1985. More than 500 test flights have been made in these two years and engine flight time has accumulated to over 1,500 hours.

This XF3-30 engine has been imposed strict requirements of the structural integrity to meet the MIL-E-5007D specification. This paper describes the structural features of this engine and some structural problems encountered through the development. The improvements for these development problems are covered.
A New Approach to the Calculation of S2 Stream Surfaces With Full Inverse and Hybrid Methods for Turbomachine
Authors: Manchu Ge , Zhengti Yu , Yiping Lou
Published: March 2015

In this paper, a full Inverse problem method — a prescribed wall-velocity method (PWVM) — and a hybrid problem method are suggested in solving S2 stream surface. In these methods two walls or one wall coordinates of the meridional through flow section of turbomachine can be obtained when the velocities along the hub and casing walls or one of them are prescribed. The new form of the governing equations in terms of grid coordinates are obtained. These equations are different with those used for the S1 stream surfaces. The suitable wall-velocities can be selected and prescribed by designer and the coordinates of hub and casing walls will be obtained by solving these new equations on S2 stream surfaces. The boundary conditions and the solution of these equations will be presented too.

The programs have been written and several examples are calculated. The results seems to be satisfactory. A comparison between the solutions of this method and the ordinary method, which is a method given the coordinates of hub and casing walls, is also presented in this paper.
Causes for Turbomachinery Performance Deterioration
Authors: Tabakoff W.
Published: March 2015

Turbines and compressors operating in polluted atmosphere with solid particles are subjected to performance deterioration. This paper presents an investigation carried out on two-stage gas turbine with blunt leading edge blades and on a single-stage axial flow compressor to study the effects of particulates and erosion on performance deterioration.
A Numerical Investigation of Fluid Flow for Disk Pumping Applications
Authors: Roscoe D. V. , Buggeln R. C. , Foster J. A. , McDonald H.
Published: March 2015

This paper describes numerically calculated results obtained for a viscous driven enclosed cavity flow and comparison with the experiments of Daly and Nece (Ref. 4). The sensitive prediction of moment coefficient is chosen for comparison purposes. Some discussion of the impact of k-ε turbulence modeling is also included. A second configuration demonstrating the degree of geometric complexity which can be handled is also presented.
Design Aspects of Recent Developments in Rolls-Royce RB211-524 Powerplants
Authors: Parkes R. J.
Published: March 2015

This paper describes recent design changes in the RB211-524 powerplant. In response to the market requirement for a wide bodied aircraft to make journeys of increased range, the specific fuel consumption of the latest -524 engine has been improved by 14% compared with initial versions.

The paper shows how the potential of the three shaft concept has been coupled with the latest aerodynamic technology to produce over 25% more thrust at essentially the same engine size. This increased thrust has been achieved while meeting the latest noise and gaseous emissions regulations and while achieving continuing improvements in engine reliability.

The paper describes the introduction of electronic engine control to provide improved aircraft operation and maintenance. It also shows how the needs of the latest wide body, long range, twin engined aircraft under development can be met by combining the core of the -524 engine with a larger fan to produce a powerplant with a further 25% increased thrust capability.
Developing the Rolls-Royce Tay
Authors: Wilson N. J.
Published: March 2015

Description & Application

The paper traces the evolution of the Tay engine, launched in response to the requirement for an engine suitable for powering a FAR Part 36 Stage 3 noise compliant aircraft in the 70–100 seat range. The engine, which is derived from the Spey (RB183) MK 555 installed in the Fokker F28 aircraft, incorporates several latest technology features a number of which are already in service in large turbofan engines. Modularity and maintainability are key areas which have been addressed in the design of the engine; these are discussed in regard to operation in service.

Results, Conclusions & General Observations

The eight engine/two year development programme from first engine run to Type Approval by the United Kingdom Civil Aviation Authority is reviewed with detail description of some of the more important and interesting tests. Certification by the US Federal Aviation Administration was subsequently achieved under reciprocal cross-validation procedures. Flight certification of the two lead aircraft applications is now complete.

With completion of type certification of the baseline engine and production deliveries now underway, attention is being turned to growth derivative versions of the engine: an uprated version, due to come on stream late 1988 in an increased weight version of the Fokker 100 has now commenced its certification programme — and further growth capabilities are being explored.