bluuebunny/crossref_metadata_2025 huggingface dataset:
Microbial flora of normal canine conjunctivae
Authors: McDonald P. J. , Watson A. D. J.
Published: September 2008

Over an 8‐month period, samples were obtained from normal conjunctival sacs of 100 dogs, for aerobic and anaerobic culture. No organisms were isolated from 22% of the samples, while a single isolate was obtained from 46% and in 32% two to four species were identified. Gram‐positive organisms predominated, with Staphylococcus spp., Bacillus spp. and Corynebacterium spp. accounting for 76% of the total isolates.

Gram‐negative bacteria comprised 8‐4% of the total. Only one obligate anaerobe, a Clostridium sp., was isolated.
Torsion of a lung lobe in the dog
Authors: CRITGHLEY K. L.
Published: September 2008

A 3‐year‐old Whippet in severe respiratory distress was found to have an extensive pleural effusion associated with a 180o torsion of the cardiac lobe of the right lung. The possible cause of torsion and diagnostic indications of this lesion are discussed.
The frequency of occurrence of anal sacculitis in the dog
Authors: HALNAN C. R. E.
Published: September 2008

A survey of the incidence of anal sacculitis in the dog based on a population of 3,053 dogs treated at two urban practices, one in England and one in Australia, showed that 12‐5% of dogs presented at clinics were affected with anal sacculitis. No predisposition in the dogs or selectivity on the part of the disease was found in relation to breed, sex, age or geographical distribution.
Problems of keeping ornamental waterfowl
Authors: HUMPHREYS P. N.
Published: September 2008

Ornamental waterfowl are now kept by very many people. Aspects of management, behaviour and disease conditions are explained and the diagnosis and treatment of some diseases are discussed.
Canine bacteruria
Authors: KivistÖ A‐K. , Vasenius H. , Sandholm M.
Published: September 2008

Urine from 237 dogs submitted for euthanasia was collected directly by needle aspiration from the urinary bladder. The bacteriological findings were correlated with the sex and age of the dogs. E. coli was the most frequent species found. The overall incidence of bladder infection was 6–2% for males and 26–6% for females. Bladder infection can be categorized on the basis of occurrence in either very young or in older dogs. The infection incidence increased linearly in bitches older than 4 years, ending at a 50% frequency in those more than 10 years old. Pyometra frequency also increased after 4 years of age and this pattern may indicate a common causative factor for urinary tract infection and pyometra. This investigation shows that subclinical urinary tract infection is common in dogs and is related to age in bitches.
Small animal dentistry and the role of ultrasonic instruments in dental care
Authors: Lane J.G.
Published: September 2008

The salient features of the aetiopathogenesis of gingivitis and periodon‐titis are summarized with particular reference to the roles of plaque, saliva and calculus in the degeneration of the supporting tissues of canine and feline teeth. It is emphasized that in many instances irreversible damage will have occurred before an animal is first presented for dental treatment. The working principles of ultrasonic dental instruments are outlined and then followed by a more detailed description of the technique for the use of this equipment in veterinary practice.
Five‐hydroxytryptamine antagonists and feline aortic embolism
Authors: Olmstead Marvin L. , Butler Hugh C.
Published: September 2008

Clinically, feline aortic embolism is manifested by paresis or paralysis of the hind legs. Mere occlusion of the terminal aorta will not cause these signs to develop, i.e. a clot must be present. The clinical condition was duplicated if the aorta was ligated in a manner which formed a cul‐de‐sac into which autologous blood mixed with glass beads was injected.

In three different groups of cats 5‐hydroxytryptamine (5‐HT) antagonists were administered intravenously before the creation of a blood clot in the cul‐de‐sac. The antagonists used were methysergide, cyproheptadine and phenoxybenzamine. The results obtained indicate that cyproheptadine has promise as an effective agent for preventing paresis or paralysis in feline aortic embolism. The active role of 5‐HT in the production of paresis or paralysis in feline aortic embolism is more clearly implicated by the work done in this investigation. This knowledge adds to the basic understanding of the pathophysiology involved in this disease.
An epidemiological survey of the feline urological syndrome
Authors: Walker A. D. , Weaver A. D. , Anderson R. S. , Crighton G. W. , Fennell C. , Gaskell C. J. , Wilkinson G. T.
Published: September 2008

An epidemiological survey of the feline urological (or urolithiasis) syndrome (FUS) was carried out from 1 October 1973 to 30 September 1974. Details of 437 FUS cases were recorded by veterinary surgeons in thirty‐three practices. An independent market research organisation collected corresponding details, where applicable, of 604 pet cats selected randomly from the pet cat population of the practice areas.

Total incidence of reported cases was estimated at about 0.64% of the domestic cat population in one year. The number of cases of FUS was highest in the autumn and winter of 1973 and then decreased to the end of the survey period.

Comparison of clinical and control surveys showed an association of the disease with several factors. These included age, diet and neutering (especially of male animals). By comparison with the controls, FUS cats tended to drink less, to be fed on dry cat food, to be considered lazy, taking little exercise, to have less freedom to leave the house at will and to be provided with indoor urinating facilities. There was also some evidence of an association with the brand of dry cat food and with the number of cats in the household. These factors were not necessarily either causative agents or additive in effect. A follow‐up survey revealed a FUS mortality of 22% (90/403 cats) at 6 months after the survey episode, the majority dying or being put down in the first week. The death‐rate was higher in males. Further episodes were noted in 32% of the cats followed up. The rate of recurrence was the same in those cats (68%) whose diet had been changed after the initial episode.
Glucose tolerance and insulin response in diabetes mellitus of dogs
Authors: KANEKO J. J. , MATTHEEUWS D. , ROTTIERS R. P. , VERMEULEN A.
Published: September 2008

The low dose intravenous glucose tolerance test (IVGTT) and the insulin response to the glucose load were performed in a series of twenty–two diabetic dogs. All diabetic dogs were characterized by glucose intolerance as expressed by an abnormal half time (Tl/2) or fractional turnover rate (k) for glucose clearance. On the basis of the initial insulin level (Io), the insulin peak response (Ip) and the insulinogenic index (I/G), the dogs were classified into three types. Type I dogs were characterized by a low Io, low Ip and low I/G in response to glucose, similar to the juvenile form of diabetes in humans. Type II dogs were characterized by a normal or high Io, but also with a low Ip and a low I/G which are some of the features of the maturity onset form. Type III dogs were characterized by a normal Io and a normal or delayed response to glucose as seen in chemical diabetes. It is suggested that these types represent stages in the natural history of the development of diabetes mellitus in dogs.
The lateral fenestration of canine thoracolumbar disc protrusions: a review of 30 cases
Authors: DENNY H. R.
Published: September 2008

Thirty dogs with disc protrusions in the thoracolumbar region were treated by lateral fenestration of the last three thoracic and first three lumbar discs. The case details and results of treatment are presented.
Oesophageal diverticulum formation in the dog
Authors: PEARSON H. , GIBBS C. , KELLY D. F.
Published: September 2008

This paper briefly reviews previously recorded cases of (epiphrenic) oesophageal diverticula in the dog and describes the clinical and radiological findings in, nine further cases. Four of the nine cases also had a broncho–oesophageal fistula; clinical and histological evidence is presented to suggest that the lesions were congenital in at least five animals.
The EMO system in small animal anaesthesia
Authors: HALL L. W.
Published: September 2008

The EMO System was used to administer ether/air anaesthesia to dogs undergoing clinical surgical procedures. Anaesthesia with spontaneous breathing gave rise to normal oxygen tensions in arterial blood, a slight acidosis and a decrease in arterial carbon dioxide tension. When used with relaxant drugs and intermittent positive pressure ventilation of the lungs it was found that to maintain normal oxygen tensions in the arterial blood it was necessary to hyperventilate to low arterial carbon dioxide tensions. Ether/air anaesthesia with the EMO System was found to meet modern criteria for acceptability in general practice where the veterinary surgeon may be assisted in the operating theatre by a nurse or may be entirely alone.
Distemper and measles vaccines – a comparative trial
Authors: DUDLEY J. M. , NIXON ANN , MUMFORD A. M.
Published: September 2008

A trial was conducted in the Birmingham RSPCA stray dog kennels to compare the efficacy of distemper and measles vaccines. The results show that both vaccines are effective and are of equal value in protecting animals in an infective environment.
Closure after injury of the distal femoral growth plate in the dog
Authors: CULVENOR J. A. , HULSE D. A. , PATTON C. S.
Published: September 2008

Distal femoral growth plate separations were created and repaired using pin–fixation in 24 immature dogs. In 16 dogs, destroyed 10 weeks after surgery, the growth plate had closed. Of eight dogs destroyed from 1 to 4 weeks after surgery, seven had a indication of premature closure while one (destroyed at 1 week) had only injury to the plate.
The larynx of the Basenji dog
Authors: ASHDOWN R. R. , LEA TERESA
Published: September 2008

In two aged Basenji bitches, the lateral laryngeal saccules were absent or reduced and the laryngeal recesses (ventricles of Morgagni) were shallow compared with those of other dogs. No other significant differences were discovered. It is not yet established whether or not these anatomical features are directly related to barklessness in these dogs. The terminology used for these anatomical features is discussed.
Diseases of tortoises: a review of seventy cases
Authors: HOLT P. E. , COOPER J. E. , NEEDHAM J. R.
Published: September 2008

The clinical and pathological findings in seventy tortoises (mostly Testudo graeca) are described. Diagnostic techniques used included microbiological, histopathological and parasitological examination, and both these and the clinical procedures are described and discussed. A variety of conditions was encountered; gastrointestinal helminthiasis and necrotic stomatitis were most common, but other diagnoses included hypovita‐minoses, constipation, abscesses and trauma. On no occasion was a Salmonella sp. isolated.
Canine mammary cancer
Authors: MISDORP W. , HART A. A. M.
Published: September 2008

Microscopic examination showed that mammary cancer in the dog, especially the more infiltrating types, had often been removed (±50%) in an incomplete way. Local recurrence, detected clinically or at post mortem examination, is frequent.

Metastasis is the most frequent cause of death. Dyspnoea is often, but not always, associated with pulmonary metastasis. Lymphogenous and haematogenous metastasis are common.

By‐passing of regional lymph nodes and lungs is extremely uncommon. Pleural metastasis was only found in combination with pulmonary metastasis.

Tumours in the posterior glands had more frequently spread to the lungs and liver than those in the anterior glands. Haematogenous spread to other mammary glands was not detected. Multiple malignant mammary tumours were found to be rare (4%).

Mammary cancer should be treated both surgically and systemically.
Vascular malformation (cavernous angioma) of the spinal cord in a dog
Authors: ZAKI FAROUK A.
Published: September 2008

Cavernous angioma was found in the C5‐C6 spinal cord segments of a 4–month‐old female Siberian Husky. The malformation appeared as vessels packed together and lined by simple endothelial cells surrounded by a thin layer of collagenous connective tissue. These vessels were not separated by neural tissue. Clinically, the dog was presented with progressive tetraparesis over a 1‐month period.
Osteochondritis dissecans of the tibial tarsal bone in dogs
Authors: MASON T. A. , LAVELLE R. B.
Published: September 2008

The clinical histories of nineteen cases of osteochondritis dissecans of the medial ridge of the tibial tarsal bone are described. The clinical signs were lameness and a reduced range of joint flexion. Radiography demonstrated changes over the medial ridge of the tibial tarsal bone. Untreated cases remained lame and the rapid development of degenerative joint changes was noted. Cases treated promptly by arthrotomy, removal of the detached flap of cartilage and curettage made a quick and permanent recovery. Access to the lesion was gained by a postero‐medial approach.
Collie eye anomaly (CEA)
Authors: BARNETT K. C.
Published: September 2008

The Collie Eye Anomaly is described under the headings of the two basic abnormalities—chorioretinal dysplasia and coloboma. The secondary changes of retinal detachment, intraocular haemorrhage and other vascular changes are also described as is the normal collie fundas.
Osteosarcoma associated with healed fractures
Authors: BENNETT D. , CAMPBELL J. R. , BROWN P.
Published: September 2008

Two cases of osteosarcoma development associated with previous long bone fractures are described. In one case the surgical implant used was still in place. Other cases reported in the literature are reviewed.
A veterinary approach to spiders
Authors: COOPER J. E.
Published: September 2008

Spiders are kept as pets, for scientific study and for display. The veterinary profession is increasingly being consulted for advice on their care.

The basic biology and management of spiders are outlined, together with information on physical and chemical restraint. These animals are particularly susceptible to managemental problems but other diseases may also occur. A certain amount of medical and surgical attention is possible.
Financial modelling of the potential cost of ovine Johne's disease and the benefit of vaccinating sheep flocks in southern New South Wales
Authors: Bush RD , Windsor PA , Toribio JA , Webster SR
Published: September 2008

Objective  To develop an enterprise gross margin (GM) model that predicts the on‐farm financial impact of ovine Johne's disease (OJD) for various sheep enterprises in Australia. In addition, to estimate the benefits and costs of control through the use of the Gudair™ vaccination, including a breakeven point.

Design and population  Data for the model was gained from an observational study conducted over a 3‐year period from 2002 to 2004 using sheep from 12 OJD‐infected flocks from southern New South Wales. Flocks ranged between 3500 and 20,000 sheep, with owner estimates of 5% or greater OJD mortality at the start of the study.

Procedure  A GM model was developed to predict the on‐farm financial impact of OJD for various sheep enterprises in Australia, comparing non‐infected, infected (status quo) and infected (vaccination) disease scenarios.

Results  Vaccination breakeven points are achieved within 2 to 3 years for breeding enterprises if OJD mortalities are high, rising towards 7 years for a Merino ewe enterprise if OJD mortalities are low.

Conclusion  The GM model demonstrates the returns to investment of vaccination for Australian sheep producers with OJD‐infected flocks.
Cross‐species amplification of Eucalyptus microsatellite loci
Authors: NEVILL PAUL G. , REED ALASTAIR , BOSSINGER GERD , VAILLANCOURT RENE E. , LARCOMBE MATHEW , ADES PETER K.
Published: September 2008

This study examined the interspecific amplification of nuclear microsatellite loci developed mainly for eucalypts in the subgenus Symphyomyrtus across five species within the second most speciose subgenus, subgenus Eucalyptus. A set of eight to 10 loci, depending on taxon, have been identified that are highly variable and easily scored. The successful transfer of microsatellite loci to these eucalypt species sidesteps the expensive and time‐consuming development of species‐specific microsatellite libraries. This primer set will enable the examination and cross‐species comparison of the genetic resources of commercially and ecologically important members of the subgenus Eucalyptus.
L’UNESCO et les langues : un engagement en faveur de la culture et du développement
Authors: Rosi Mauro
Published: September 2008

Les langues et le multilinguisme sont depuis plus de soixante ans au cœur de la vie de l’UNESCO. Ils le sont encore aujourd’hui et plus que jamais, d’une part parce que l’on assiste à une valorisation sans précédent du patrimoine culturel immatériel sous toutes ses formes, d’autre part, du fait de la crainte de voir la mondialisation accélérer le rythme de disparition d’un grand nombre de langues. Portée par un contexte général exigeant, l’UNESCO s’est engagée en faveur des langues et du multilinguisme en élaborant un outil normatif et en mettant sur pied des programmes opérationnels tant spécialisés que multidisciplinaires.
Vitalité et revitalisation des langues : une place pour chacune d’elles
Authors: Yamamoto Akira Y. , Brenzinger Matthias , Villalón María E.
Published: September 2008

De nombreuses langues sont en train de disparaître à jamais et, avec elles, des trésors du savoir humain. Les langues se perdent lorsqu’on cesse de les utiliser. Dans cet article, nous examinons quelques‐unes des raisons complexes qui peuvent conduire les locuteurs à abandonner la langue de leurs ancêtres en faveur d’une langue dominante. Nous évoquons aussi les moyens de stopper ou d’inverser cette tendance, laquelle s’explique, entre autres facteurs, par des changements dans les identités. De notre point de vue, l’acquisition d’une langue dite « mondiale » ne signifie pas forcément la perte de sa propre langue.
Class and ethnic differences in Canadians' attitudes to native people's rights and immigration
Authors: FILSON GLEN
Published: September 2008

A l'aide de données tirées d'entrevues traitant des attitudes envers l'immigration et des droits des aborigènes dans le cadre de l'étude sur la qualité de la vie (1977), cette note essaye d'expliquer certains aspects de la dialectique de la classe sociale et de l'ethnicité au Canada. On constate ensuite la mesure dans laquelle ces attitudes diffèrent, selon la classe et l'ethnicité, dans la direction de l'éducation. Les résultats, tels que l'opposition considérable de la classe ouvriére à l'immigration et le sérieux antagonisme ethnique à l'intérieur de certain groupes ethniques de même que de certaines classes, sont dévoilés à travers des réalités telles que la division du marché du travail du point de vue ethnique, le rôle des entremetteurs ethniques et la promotion de la conscience ethnique pour étouffer la conscience de classe.

Employing interview data regarding attitudes to immigration and native people's rights from the Quality of Life Survey (1977), I attempt to illuminate aspects of the dialectic of social class and ethnicity in Canada. The proportion of variance in these attitudes explicable by class and ethnicity, controlling for education, are then ascertained. Findings such as the substantial working class opposition to immigration and serious ethnic antagonism within some ethnic groups and classes are understood in the light of such things as the ethnically split labour market, the functions of ethnic antagonism within some ethnic groups and classes are understood in the light of such things as the ethnically split labour market, the functions of ethnic middlemen and the promotion of ethnic consciousness to drown class consciousness.
Head Drop of a Spatial Turbopump Inducer
Authors: Flores Nellyana Gonzalo , Goncalvès Eric , Patella Regiane Fortes , Rolland Julien , Rebattet Claude
Published: September 2008

A computational fluid dynamics model for cavitation simulation was investigated and compared with experimental results in the case of a three-blade industrial inducer. The model is based on a homogeneous approach of the multiphase flow coupled with a barotropic state law for the cool water vapor/liquid mixture. The numerical results showed a good prediction of the head drop for three flow rates. The hydrodynamic mechanism of the head drop was investigated through a global and local study of the flow fields. The evolution of power, efficiency, and the blade loading during the head drop were analyzed and correlated with the visualizations of the vapor/liquid structures. The local flow analysis was made mainly by studying the relative helicity and the axial velocity fields. A first analysis of numerical results showed the high influence of the cavitation on the backflow structure.
The Effect of Impeller Cutback on the Fluid-Dynamic Pulsations and Load at the Blade-Passing Frequency in a Centrifugal Pump
Authors: Barrio Raúl , Blanco Eduardo , Parrondo Jorge , González José , Fernández Joaquín
Published: September 2008

A study is presented on the fluid-dynamic pulsations and the corresponding dynamic forces generated in a centrifugal pump with single suction and vaneless volute due to blade-volute interaction. Four impellers with different outlet diameters, obtained from progressive cutbacks (trimmings) of the greatest one, were successively considered in the test pump, so that the radial gap between the impeller and the volute ranged from 8.8% to 23.2% of the impeller radius. The study was based on the numerical computation of the unsteady flow through the machine for a number of flow rates by means of the FLUENT code, solving the 3D unsteady Reynolds-averaged Navier–Stokes equations. Additionally, an experimental series of tests was conducted for the pump with one of the impellers, in order to obtain pressure fluctuation data along the volute front wall that allowed contrasting the numerical predictions. The data collected from the numerical computations were used to estimate the dynamic radial forces and torque at the blade-passing frequency, as a function of flow rate and blade-tongue radial gap. As expected, for a given impeller diameter, the dynamic load increases for off-design conditions, especially for the low range of flow rates, whereas the progressive reduction of the impeller-tongue gap brings about corresponding increments in dynamic load. In particular, varying the blade-tongue gap within the limits of this study resulted in multiplying the maximum magnitude of the blade-passing frequency radial force by a factor of about 4 for low flow rates (i.e., below the nominal flow rate) and 3 for high flow rates.
Thermodynamic Effect on Cavitation Performances and Cavitation Instabilities in an Inducer
Authors: Kikuta Kengo , Yoshida Yoshiki , Watanabe Mitsuo , Hashimoto Tomoyuki , Nagaura Katsuji , Ohira Katsuhide
Published: September 2008

Based on the length of the tip cavitation as an indication of cavitation, we focused on the effect of thermodynamics on cavitation performances and cavitation instabilities in an inducer. Comparison of the tip cavity length in liquid nitrogen (76K and 80K) as working fluid with that in cold water (296K) allowed us to estimate the strength of the thermodynamic effect on the cavitations. The degree of thermodynamic effect was found to increase with an increase of the cavity length, particularly when the cavity length extended over the throat of the blade passage. In addition, cavitation instabilities occurred both in liquid nitrogen and in cold water when the cavity length increased. Subsynchronous rotating cavitation appeared both in liquid nitrogen and in cold water. In the experiment using liquid nitrogen, the temperature difference between 76K and 80K affected the range in which the subsynchronous rotating cavitation occurred. In contrast, deep cavitation surge appeared only in cold water at lower cavitation numbers. From these experimental results, it was concluded that when the cavity length extends over the throat, the thermodynamic effect also affects the cavitation instabilities as a “thermal damping” through the unsteady cavitation characteristics.
Vortex Breakdown in an Enclosed Cylinder With a Partially Rotating Bottom-Wall
Authors: Yu P. , Lee T. S. , Zeng Y. , Low H. T.
Published: September 2008

A numerical study of the axisymmetric flow in a cylindrical chamber of height H is presented, which is driven by a bottom disk rotating at angular velocity Ω. However, unlike most previous studies, the present rotating disk is of smaller radius than the bottom-wall. The boundary curves for the onset of vortex breakdown are presented using different definitions of the nondimensional parameters, depending on whether the cylinder radius R or the disk radius rd is used as the length scale. The study shows that the boundary curves are best correlated when presented in terms of the Reynolds number Ωrd2∕υ, aspect ratio H∕R, and cylinder-to-disk ratio R∕rd. The cylinder-to-disk ratio R∕rd up to 1.6 is found to have noticeable effect on vortex breakdown; this is attributed to the change of effective aspect ratio. The contours of streamline, angular momentum, and azimuthal vorticity are presented and compared with those of whole bottom-wall rotation.
Optical Diffusometry Techniques and Applications in Biological Agent Detection
Authors: Kumar Aloke , Gorti Venu M. , Shang Hao , Lee Gil U. , Yip Nung Kwan , Wereley Steve T.
Published: September 2008

Optical diffusometry is a technique used for measuring diffusion. This work explores the possibility of directly measuring diffusion coefficients of submicron particles for pathogen detection. The diffusion coefficient of these particles is a function of the drag coefficient of the particle at constant temperatures. Particles introduced into a sample containing an analyte bind with the analyte if functionalized with the appropriate antibodies. This leads to an increase in the hydrodynamic drag of the particles and hence a decrease in their diffusion coefficient. This study uses the above principle to effectively measure the diffusion coefficient of the particles using two different experimental approaches. The measured reduction in the diffusion coefficient can be correlated to the amount of analyte present and thus forms the basis of biological agent detection. Sensitivity to experimental conditions is analyzed. It is observed that alternative techniques such as optical trapping hold promise: the diffusive behavior of particles in optical traps is found to be quantitatively different from that of a free particle. Hence preconditions are identified to make optical trapping appropriate for agent detection.
A Parametric Study of Passive Flow Control for a Short, High Area Ratio 90deg Curved Diffuser
Authors: Chong T. P. , Joseph P. F. , Davies P. O. A. L.
Published: September 2008

This paper represents the results of an experimental program with the aim of controlling the flow in a highly unstable 90deg curved diffuser. The diffuser, which is an integral part of an open jet wind tunnel at the University of Southampton, has the unique configuration of extreme shortness and high area ratio. In this study, several passive flow control devices such as vortex generators, woven wire mesh screens, honeycomb, and guide vanes were employed to control the three-dimensional diffusing flow in a scaled-down model. Although less successful for vortex generators, the other devices were found to improve significantly the uniformity of the flow distribution inside the curved diffuser and hence the exit flow. This study suggests that a cumulative pressure drop coefficient of at least 4.5 at the diffuser exit with at least three guide vanes is required to achieve adequate flow uniformity at the diffuser exit. These flow conditioning treatments were applied to the full-scale diffuser with exit dimensions of 1.3×1.3m2. Flow with comparable uniformity to the scale-model diffuser is obtained. This study provides valuable guidelines on the design of curved/straight diffusers with nonseparated flow and minimal pressure distortion at the exit.
Strategies for Simulating Flow Through Low-Pressure Turbine Cascade
Authors: Gross Andreas , Fasel Hermann F.
Published: September 2008

Laminar separation on the suction side of low-pressure turbine blades at low Reynolds number operating conditions deteriorates overall engine performance and has to be avoided. This requirement affects the blade design and poses a limitation on the maximum permissible blade spacing. Better understanding of the flow physics associated with laminar separation will aid in the development of flow control techniques for delaying or preventing flow separation. Simulations of low-pressure turbine flows are challenging as both unsteady separation and transition are present and interacting. Available simulation strategies have to be evaluated before a well-founded decision for the choice of a particular simulation strategy can be made. With this in mind, this paper provides a comparison of different flow simulation strategies: In particular, “coarse grid” direct numerical simulations, implicit large-eddy simulations, and simulations based on a hybrid turbulence modeling approach are evaluated with particular emphasis on investigating the dynamics of the coherent structures that are generated in the separated flow region and that appear to dominate the entire flow. It is shown that in some instances, the effect of the dominant coherent structures can also be predicted by unsteady Reynolds-averaged Navier–Stokes calculations.
Laminar Non-Newtonian Fluid Flow in Noncircular Ducts and Microchannels
Authors: Muzychka Y. S. , Edge J.
Published: September 2008

Non-Newtonian fluid flow in noncircular ducts and microchannels is examined. A simple model is proposed for power law fluids based on the Rabinowitsch–Mooney formulation. By means of a new characteristic length scale, the square root of the cross-sectional area, it is shown that dimensionless wall shear stress can be made a weak function of duct shape. The proposed model is based on the solution for the rectangular duct and has an accuracy of ±10% or better. The current model eliminates the need for tabulated data or equations for several common shapes found in handbooks, namely, circular tube, elliptic tube, parallel channel, rectangular duct, isosceles triangular duct, circular annulus, and polygonal ducts.
On the Preliminary Design and Noncavitating Performance Prediction of Tapered Axial Inducers
Authors: d’Agostino Luca , Torre Lucio , Pasini Angelo , Cervone Angelo
Published: September 2008

A reduced order model for preliminary design and noncavitating performance prediction of tapered axial inducers is illustrated. In the incompressible, inviscid, irrotational flow approximation, the model expresses the 3D flow field in the blade channels by superposing a 2D cross-sectional vorticity correction to a fully guided axisymmetric flow with radially uniform axial velocity. Suitable redefinition of the diffusion factor for bladings with non-negligible radial flow allows for the control of the blade loading and the estimate of the boundary layer blockage at the specified design flow coefficient, providing a simple criterion for matching the hub profile to the axial variation of the blade pitch angle. Carter’s rule is employed to account for flow deviation at the inducer trailing edge. Mass continuity, angular momentum conservation, and Euler’s equation are used to derive a simple second order boundary value problem, whose numerical solution describes the far-field axisymmetric flow at the inducer discharge. A closed form approximate solution is also provided, which proved to yield equivalently accurate results in the prediction of the inducer performance. Finally, the noncavitating pumping characteristic is obtained by introducing suitably adapted correlations of pressure losses and flow deviation effects. The model has been verified to closely approximate the geometry and noncavitating performance of two space inducers tested in Alta’s Cavitating Pump Rotordynamic Test Facility, as well as the measured pumping characteristics of a number of tapered-hub inducers documented in the literature.
Design Principles and Measured Performance of Multistage Radial Flow Microturbomachinery at Low Reynolds Numbers
Authors: Lee Changgu , Arslan Selin , Fréchette Luc G.
Published: September 2008

This paper introduces and experimentally demonstrates the design concept of multistage microturbomachinery, which is fabricated using silicon microfabrication technology. The design process for multistage microscale turbomachinery based on meanline analysis is presented, along with computational fluid dynamics predictions of the key aerodynamic performance parameters required in this design process. This modeling was compared with a microturbine device with a 4 mm diameter rotor and 100 μm chord blades, based on microelectromechanical system technology, which was spun to 330,000 rpm and produced 0.38 W of mechanical power. Modeling suggests a turbine adiabatic efficiency of 35% and Re=266 at the maximum speed. The pressure distribution across the blade rows was measured and showed close agreement with the calculation results. Using the model, the microturbine is predicted to produce 3.2 W with an adiabatic efficiency of 63% at a rotor speed of 1.1×106 rpm.
Eliminating Static Pressure Distortion by a Large Cut Back Tongue Volute
Authors: Xu C. , Amano R. S.
Published: September 2008

This paper presents a physical solution by eliminating static pressure distortions of impeller exit due to a volute in a centrifugal compressor. The numerical and experimental studies on the circumferential distortion flow characteristics inside the stationary frame of a high-pressure ratio compressor with a large cut back tongue volute. The detailed flow structures and pressure distortions development inside the stationary components are discussed. The numerical results were demonstrated to be in good agreement with the experiments. The volute and diffuser interactions at design and off-design conditions were found to be much smaller for the large cut back volute in comparison with the reported from literature. The study indicated that the large cut back tongue volute design not only benefits the compressor performance but also reduces the impeller exit static pressure non-uniformity caused by discharge volute.
The Impact of Surface Roughness on Axial Compressor Performance Deterioration
Authors: Syverud Elisabet , Bakken Lars E.
Published: September 2008

Axial compressor deterioration due to removable deposits is a major concern in the operation of gas turbines. It is important to fully understand the flow mechanisms in order to successfully monitor and clean the engine. A test program on the GE J85-13 jet engine quantified the increased surface roughness and the distribution of salt deposits in an axial compressor. The test data showed good agreement with published data for stage performance deterioration. This paper compares the GE J85-13 test data on surface roughness to previously published work on surface roughness in compressors. The effect of surface roughness on the stage characteristics is modeled using theory for frictional losses, blockage and deviation. The results are compared to test data. The most significant effect of increased roughness is found to be the variation in the flow coefficient.
Prototype Development of a Novel Radial Flow Gas Turbine: Combustor Development
Authors: Brun Klaus , Gernentz Ryan S.
Published: September 2008

A prototype of a novel gas turbine concept is being developed to demonstrate the technical feasibility of a gas turbine design based on a straight radial flow with no axial flow turning. The prototype gas turbine consists of only two structural elements—a rotor disk and a stator shroud. The rotor consists of a centrifugal compressor and high impulse radial outward-flow turbine connected to an electric generator. The stator shroud contains the combustor and nozzles. The difference between this novel design and conventional radial gas turbine that the compressor and turbine section are installed on the same side of the rotating wheel, while the combustor and nozzle are mounted on the stationary shroud. Thus, the entire assembly consists of two components. Technical advantages are: • Single Rotating Disk; • Compact Two-Piece Construction; • Ease of Repair and Maintenance; • High Power to Weight Ratio. This paper discusses the combustor development and preparation for design testing of the prototype radial gas turbine.
Identification and Clean-Up of Contaminants From Vaporized NGL CGT Fuel
Authors: Newbound T. D. , Beckenbach J. W. , Al-Mutawa H. M.
Published: September 2008

This paper describes an analytical approach used to identify heavy natural gas liquid (NGL) fuel components and fuel conditioning solutions employed to prevent fouling of the vaporized fuel delivery systems. The discussion includes high pressure vaporized fuel sampling, isolation of C7+ and C14+ hydrocarbon fractions from NGL, and performance validation of fuel processing apparatus. Saudi Aramco operates more than 80 aeroderivative gas turbines (CGT’s), from four manufacturers, to drive crude oil pumps and generate electrical power on the East-West Pipeline that traverses the Arabian Peninsula. Since the pipeline was first commissioned in 1980, the CGT’s have been operated primarily on vaporized C2+ NGL. Although the properties of this C2+ NGL (such as density and heating value) are nearly identical to propane, its use as CGT fuel has presented challenges. Fuel system fouling resulted from the presence of heavy hydrocarbons including residual surface-active compounds derived primarily from corrosion inhibitors and intermittent crude oil carryover. This fouling consisted of hard, epoxy-like deposits coating all manifolds and fuel nozzle passages downstream of the vaporizers. The entire fleet suffered from increased operating and maintenance costs and reduced reliability from plugging of last-chance filters to blocked fuel nozzles. This led to temperature spreads in combustors and hot component damage. High temperature rated coalescing filters were applied successfully in three vaporized NGL fuel system configurations. One fuel system configuration that required even more stringent fuel conditioning was modified to reject approximately 15 percent (heavy ends fraction) of the NGL. Performance tests were conducted to measure the extent to which heavy ends were reduced in the modified fuel vaporizers. Analytical methods were developed to identify and measure heavy hydrocarbons at ppm concentrations. The actual fuel compositions determined analytically agreed with compositions predicted from process simulations.
Prediction of Gas Turbine Blade Life: An Interdisciplinary Engineering Approach for Condition-Based Maintenance
Authors: Jin Huitang , Pistor Robert , Lowden Paul , Weber Ben , Grant Ryan
Published: September 2008

Realistic assessment of the remaining serviceable life in turbine hot section components plays an important role in engine condition-based maintenance and overhaul. This paper presents application of an engineering approach that integrates mechanical and performance engineering with metallurgy for turbine blade remaining life on-line assessment. By identifying the life limiting factors in a given application and monitoring the rate of the damage, economical repair, replacement and overhaul intervals can be established. Examples are given to illustrate application of this engineering approach in identifying failure mechanisms and predicting blade remaining serviceable life for TransCanada PipeLines LM1600 fleet.
Analytical Derivatives Technology for Parametric Shape Design and Analysis in Structural Applications
Authors: Akkaram Srikanth , Beley Jean-Daniel , Maffeo Bob , Wiggs Gene
Published: September 2008

The ability to perform and evaluate the effect of shape changes on the stress, modal and thermal response of components is an important ingredient in the ‘design’ of aircraft engine components. The classical design of experiments (DOE) based approach that is motivated from statistics (for physical experiments) is one of the possible approaches for the evaluation of the component response with respect to design parameters [1]. Since the underlying physical model used for the component response is deterministic and understood through a computer simulation model, one needs to re-think the use of the classical DOE techniques for this class of problems. In this paper, we explore an alternate sensitivity analysis based technique where a deterministic parametric response is constructed using exact derivatives of the complex finite-element (FE) based computer models to design parameters. The method is based on a discrete sensitivity analysis formulation using semi-automatic differentiation [2,3] to compute the Taylor series or its Pade equivalent for finite element based responses. Shape design or optimization in the context of finite element modeling is challenging because the evaluation of the response for different shape requires the need for a meshing consistent with the new geometry. This paper examines the differences in the nature and performance (accuracy and efficiency) of the analytical derivatives approach against other existing approaches with validation on several benchmark structural applications. The use of analytical derivatives for parametric analysis is demonstrated to have accuracy benefits on certain classes of shape applications.
Statistical Distribution of the Peak Maximum Amplitude of the Forced Response of a Mistuned Bladed Disk: Some Investigations and Applications of Neural Networks
Authors: Sinha Alok
Published: September 2008

This paper examines the nature of the statistical distribution of the peak maximum amplitude of the forced response of a mistuned bladed disk. Monte Carlo simulations are performed for a range of values of the structural coupling between blades and the standard deviation of mistuning. First, it is determined if the statistical distribution of a peak maximum amplitude can be called three-parameter Weibull in general. Next, using a neural network, a functional relationship between the statistics of the peak maximum amplitude ;e.g., parameters of Weibull distribution, statistical moments, 99 percentile amplitude, and input parameters (structural coupling between blades and standard deviation of mistuning) is developed.
Design and Performance of a High-Temperature Regenerator Having Very High Effectiveness, Low Leakage and Negligible Seal Wear
Authors: Wilson David Gordon , Ballou Jon M.
Published: September 2008

A high-temperature regenerator has been designed under MIT and WTPI patents (figure 1). These call for the ceramic-honeycomb regenerator disk to rotate incrementally, in this case through 90 degrees, for each movement. The seals, which can conform to the profile of the sealing surface, are firmly pressed to the regenerator seal faces during the stationary periods, here about fourteen seconds (figure 2). The seals then lift marginally, just enough to allow free disk movement, during the 0.75 second of the indexing period. Thus no sliding wear can take place. In the demonstrator unit tested the measured effectiveness was over 98%, the pressure drops of the hot and cold flows were under 2%, and the leakage was low within experimental error. The demonstrator was tested at a top temperature of 910° C. (The final temperature after development should be well above 1000°C). The paper describes design methods that are substantially different from those in general use, and discusses design choices for materials and actuation systems. This regenerator was designed to be compatible with a high-temperature 5-kW solid-oxide fuel cell. Our design studies indicate that, when applied (in a considerably larger size) to micro turbines it would enable electrical efficiencies of 50% to be exceeded. Other industrial applications that require too high a temperature for currently available recuperators would also become viable.
Evaluation of Tolerable Misalignment Areas of Bearings of Multi-Support Rotating Machine
Authors: Rybczynski Jozef
Published: September 2008

The paper presents the results of evaluation of admissible misalignments of two neuralgic bearings of a great power turbine set. The areas of admissible misalignments have been evaluated by numerical analysis of the discrete model of the machine with the aid of a package of MESWIR computer codes. For this purpose the criteria of “tolerable misalignment” were formulated with regard to permissible bearing vibrations and with regard to permissible static bearing loads. The areas of tolerable misalignments of the two bearings are presented in the graphs as the envelopes of maximum permissible bearing vibration and permissible bearing load, separately. The envelopes limits misalignments of the bearings to any direction regarded as the superposition of simultaneous vertical and horizontal displacements. Dimensions and the shapes of the areas are different for the two analyzed bearings and also depend on the fact, whether the area was calculated with regard to criterion of bearing vibration or criterion of bearing load. Especially interesting and not expected are shapes of the areas calculated with regard to vibration criterion. In this case after reaching the maximum permissible vibration at some bearing misalignment, further misalignment of the bearing may result in decreasing of vibration level. The method and procedure applied in the investigations allow determining how sensitive is a rotating multi-support machine to random misalignment of bearings. Basing on the method it is possible to correct the location of particular bearings to optimize tolerable bearing misalignment areas. Besides the research makes it possible to formulate a system of diagnostic relations connected with the bearing misalignment defects, which can make the knowledge basis for a diagnostic system.
Prediction of Shrouded Turbomachinery Blade Forced Response by a Complex Mode Analysis
Authors: Chiang Hsiao-Wei D. , Hsu Chih-Neng
Published: September 2008

Turbomachinery shrouded rotor blade design has been widely used in fans, compressors, and turbines. By using either tip or mid-span shroud, the blade structural damping and natural frequencies can be increased to reduce flutter or forced response problems. However, shrouded rotor blade design sometimes results in complex system modes with both bending and torsion present at the same time. Since shrouded rotors are rotationally periodic, the bending and torsion combined system mode can be decomposed into a real component and an imaginary component. Using both the real and imaginary mode shapes, coupled with the blade surface flow-field, a complex mode analysis was developed using a modal solution to determine the forced response of the system. This complex mode analysis was applied to both tip and mid-span shrouded rotor blade applications. Bending-dominated or torsion-dominated simple blade modes in general can be analyzed using an existing single mode approach. However, for the bending and torsion combined system modes, the single mode analysis can be misleading. By using the complex mode analysis, it was demonstrated that the combined bending and torsion system mode plays an important role in determining the blade forced response.