bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tumourigenic canine osteosarcoma cell lines associated with frizzled‐6 up‐regulation and enhanced side population cell frequency
Authors: de Sá Rodrigues L. C. , Holmes K. E. , Thompson V. , Newton M. A. , Stein T. J. 
Published: February 2015

AbstractAn increased serum alkaline phosphatase concentration is known to be associated with a negative prognosis in canine and human osteosarcoma. To expand upon previous studies regarding the biological relevance of increased serum alkaline phosphatase as a negative prognostic factor, xenogeneic heterotopic transplants were performed using six canine primary osteosarcoma cell lines generated from patients with differing serum alkaline phosphatase concentrations (three normal and three increased). Three of the six cell lines were capable of generating tumours and tumour formation was independent of the serum alkaline phosphatase status of the cell line. Microarray analysis identified 379 genes as being differentially expressed between the tumourigenic and non‐tumourigenic cell lines. Frizzled‐6 was upregulated to the greatest extent (7.78‐fold) in tumourigenic cell lines compared with non‐tumourigenic cell lines. Frizzled‐6, a co‐receptor for Wnt ligands has been associated with enhanced tumour‐initiating cells and poor prognosis for other tumours. The increased expression of frizzled‐6 was confirmed by quantitative reverse transcription polymerase chain reaction (QPCR) and Western blot analysis. Additionally, the tumourigenic cell lines also had an increase in the percentage of side population cells compared with non‐tumourigenic cell lines (5.89% versus 1.58%, respectively). There were no differences in tumourigenicity, frizzled‐6 or percentage of side population cells noted between osteosarcoma cell lines generated from patients of differing serum alkaline phosphatase concentration. However, to our knowledge this is the first study to identified frizzled‐6 as a possible marker of osteosarcoma cell populations with enhanced tumourigenicity and side population cells. Future work will focus on defining the role of frizzled‐6 in osteosarcoma tumourigenesis and tumour‐initiating cells.
Handheld tympanometer measurements in conscious dogs for the evaluation of the middle ear and auditory tube
Authors: Strain George M. , Fernandes Asia J. 
Published: February 2015

BackgroundOtitis externa is frequently accompanied by otitis media, yet it can be difficult to evaluate the tympanum, middle ear and auditory tube without the use of advanced radiographic imaging.Hypothesis/ObjectivesThe objective was to develop techniques for tympanometry testing in conscious dogs and to present normative data for clinical use of this equipment to enable assessment of the tympanum, middle ear and auditory tube.AnimalsSixteen hounds (14 female) from a school teaching colony.MethodsDogs were gently restrained in a standing position. After cleaning of the ear canal, a tympanometer probe tip extension was placed in the vertical canal and automated testing performed using a handheld device. Both ears were tested in all dogs.ResultsAcceptable recordings were obtained from both ears of 13 dogs, from one ear in each of two dogs and from neither ear of one dog, resulting in data from 28 of 32 (88%) ears. Otoscopic examination confirmed the absence of inflammation or any other obvious explanation for the noncompliant dogs. No significant differences were seen between ears for any measure. Normative data are reported for peak compliance, peak compliance pressure, gradient and ear canal volume.Conclusions and clinical importanceTympanograms can be recorded in conscious dogs to assist in the evaluation of the middle ear structures.
Turbulent Flow Heat Transfer and Friction in a Rectangular Channel With Varying Number of Ribbed Walls
Authors: Chandra Pankaj R. , Niland Michael E. , Han Je-Chin 
Published: February 2015

An experimental study of wall heat transfer and friction characteristics of a fully-developed turbulent air flow in a rectangular channel with transverse ribs on one, two, and four walls is reported. Tests were performed for Reynolds numbers ranging from 10,000 to 80,000. The pitch-to-rib height ratio, P/e, was kept at 8 and rib height-to-channel hydraulic diameter ratio, e/Dh, was kept at 0.0625. The channel length-to-hydraulic diameter ratio, L/Dh, was 15.
The heat transfer coefficient and friction factor values were enhanced with the increase in the number of ribbed walls. The friction roughness function, R(e+), was almost constant over the entire range of tests performed and was within comparable limits of the previously published data. The heat transfer roughness function, G(e+), decreased with additional ribbed walls and compared well with previous work in this area. Friction data obtained experimentally for the case with four ribbed walls compared well with the values predicted by the assumed theoretical relationship used in the present study and past publications. Results of this investigation could be used in various applications of internal channel turbulent flows involving different number of roughened walls.
Simulation of Film-Cooling Aerodynamics With a 2D Navier-Stokes Solver Using Unstructured Meshes
Authors: Irmisch Stefan 
Published: February 2015

This paper describes the application of an unstructured mesh, solution-adaptive, 2D Navier-Stokes solver to the numerical simulation of the flow through film-cooled turbine cascades. The Navier-Stokes equations are solved using a cell-vertex explicit finite-volume method. Integration in time, to a steady-state solution, is performed by a five-stage Runge-Kutta algorithm. Turbulence effects are accounted for by a k-ε model.
The use of unstructured meshes, based on Delaunay triangulation, allows to mesh the entire flow domain, including internal coolant passages, without any geometrical limitations. In combination with a solution-dependent mesh-adaption technique, the strong interactions between coolant and outer flow, leading to complex flow features, can be simulated in a realistic and efficient way.
Solutions are presented for several test cases with and without film-cooling and are compared with experimental data, illustrating the capabilities of the presented flow solver.
Experimental and Numerical Investigations of the Aerodynamical Effects of Coolant Injection Through the Trailing Edge of a Guide Vane
Authors: Bohn Dieter E. , Becker Volker J. , Behnke Klaus D. , Bonhoff Bernhard F. 
Published: February 2015

Effective turbine blade cooling is necessary to enhance the efficiency of gas turbines. Usually the coolant is mainly ejected through the trailing edge of the vanes. In addition to the desired temperature reduction at the trailing edge there is a 3D-aerodynamical interaction between the hot gas and the coolant. The complex mechanisms of the mixture are a main problem in the numerical prediction of the flow situation in this region.
This paper presents the experimental and numerical results of investigations of annular guide vanes. The experiments were conducted in a scaled turbine test rig. The mixing flow of coolant and hot gas was analyzed by measurement of the distribution of both velocity and turbulence very close to the trailing edge using a 2D-LDA measurement technique at different radial positions.
The experimental results show that the radial and circumferential distribution of the coolant depends on the pressure gradient in both directions. Inside of the mixture region the turbulence was found to be anisotropic resulting in a non-symmetrical distribution of the coolant.
For the numerical calculations a Navier-Stokes-Code was used. The numerical scheme works on the basis of an implicit finite volume method combined with a multi block technique. In order to simulate the aerodynamical effects near the injection slot of the vane it was nessessary to include the coolant flow inside the guide vane.
Performance Improvement Through Indexing of Turbine Airfoils: Part 1 — Experimental Investigation
Authors: Huber F. W. , Johnson P. D. , Sharma O. P. , Staubach J. B. , Gaddis S. W. 
Published: February 2015

This paper describes the results of a study to determine the performance improvements achievable by circumferentially indexing successive rows of turbine stator airfoils. An experimental / analytical investigation has been completed which indicates significant stage efficiency increases can be attained through application of this airfoil clocking concept. A series of tests was conducted at the National Aeronautics and Space Administration’s (NASA) Marshall Space Flight Center (MSFC) to experimentally investigate stator wake clocking effects on the performance of the Space Shuttle Main Engine Alternate Fuel Turbopump Turbine Test Article. Extensive time-accurate Computational Fluid Dynamics (CFD) simulations have been completed for the test configurations. The CFD results provide insight into the performance improvement mechanism.
Part one of this paper describes details of the test facility, rig geometry, instrumentation, and aerodynamic operating parameters. Results of turbine testing at the aerodynamic design point are presented for six circumferential positions of the first stage stator, along with a description of the initial CFD analyses performed for the test article. It should be noted that first vane positions 1 and 6 produced identical first to second vane indexing. Results obtained from off-design testing of the “best” and “worst” stator clocking positions, and testing over a range of Reynolds numbers are also presented.
Part two of this paper describes the numerical simulations performed in support of the experimental test program described in part one. Time-accurate Navier-Stokes flow analyses have been completed for the five different turbine stator positions tested. Details of the computational procedure and results are presented. Analysis results include predictions of instantaneous and time-average mid-span airfoil and turbine performance, as well as gas conditions throughout the flow field. An initial understanding of the turbine performance improvement mechanism is described.
Transition in a Separation Bubble
Authors: Malkiel E. , Mayle R. E. 
Published: February 2015

In the interest of being able to predict separating-reattaching flows, it is necessary to have an accurate model of transition in separation bubbles. An experimental investigation of the process of turbulence development in a separation bubble shows that transition occurs within the separated shear layer. A comparison of simultaneous velocity traces from probes separated in the lateral direction suggests that Kelvin-Helmholtz waves, which originate in the laminar shear layer, do not break down to turbulence simultaneously spanwise when they proceed to agglomerate. The streamwise development of intermittency in this region, can be characterized by turbulent spot theory with a high dimensionless spot production rate. Moreover, the progression of intermittency along the centerline of the shear layer is similar to that in attached boundary layer transition. The transverse development of intermittency is also remarkably similar to that in attached boundary layers.
The parameters obtained from these measurements agree with correlations which were previously deduced from turbulence intensity measurements.
3D Unsteady Flow and Forces in Centrifugal Impellers With Circumferential Distortion of the Outlet Static Pressure
Authors: Fatsis Antonios , Pierret Stephane , Van den Braembussche René 
Published: February 2015

This paper describes the numerical investigation of the centrifugal impeller response to downstream static pressure distortions imposed by volutes at off-design operations. An unsteady 3D Euler solver with non-reflecting upstream and downstream boundary conditions and phase-lagged periodicity conditions is used for this purpose.
The mechanisms governing the unsteady flow field are analysed. A parametric study shows the influence of the acoustic Strouhal number on the amplitude of the flow perturbations. Radial forces calculated on backward leaned and radial ending centrifugal impellers, show non-negligible influence of the impeller geometry.
Applications of Accurate Isentropic Exponent Determination for Fuel Gas Measurement
Authors: Pack David J. , Edwards Terry J. , Fawcett Derek 
Published: February 2015

This paper discusses the determination and application of the isentropic exponent to the various thermodynamic processes found in a high pressure natural gas transmission system.
Increasing demands for more precise measurement of natural gas, coupled with the need for greater efficiency and accountability of transportation and processing operations had led to our research and development efforts into the more precise measurement of gas flow, and the determination of gas thermodynamic properties including isentropic exponent.
The isentropic exponent has many applications, some of which include:
• the determination of the expansion factor ϵ, for calcuation of flow using an orifice or venturi type meter;
• the volumetric efficiency in a reciprocating compressor;
• the determination of the compression head for a centrigual compressor;
• the engine power required for the set given conditions for gas compressor;
• the calculation of discharge temperatures for compressors; and
• the direct measurement of gas density.
As can be appreciated, the application of an incorrect value for the isentropic exponent represents an error in the parameter determined. For large volume gas flows, this can translate into a significant cost penalty.
Effects of Free Stream Turbulence on the Instantaneous Heat Transfer in a Wall Jet Flow
Authors: Yavuzkurt Savash 
Published: February 2015

This is a preliminary study in order to understand how free stream turbulence increases the heat transfer. Effects of free stream turbulence on the instantaneous heat transfer were investigated in a wall jet flow. Heat transfer traces obtained by a hot film probe flush-mounted with the surface showed an intermittent structure with definite peaks at certain time intervals. Number of peaks per unit time increased with increasing turbulence intensity.
A wall jet test rig was designed and built. The initial thickness and the velocity of the wall jet were 10 cm and 24.4 m/s respectively. The hot film probe which was flush with the surfaces was positioned at 10 cm intervals on the surface in the flow direction. The profiles of mean velocity and axial component of the Reynolds stress were measured with a horizontal hot wire probe. Space correlation coefficients for u′ and q′ were obtained in the vertical direction to the wall.
This paper concentrates on the effects of turbulence level on the instantaneous heat transfer at the wall. It is speculated that intermittent structure of the heat transfer traces are related to burst phenomena and increase in heat transfer is due to increased ejections (bursts) at the wall with increasing turbulence levels.
Reheat and Regenerative Gas Turbines for Feed Water Repowering of Steam Power Plant
Authors: Negri di Montenegro G. , Gambini M. , Peretto A. 
Published: February 2015

This study is concerned with the repowering of existing steam power plants (SPP) by gas turbine (GT) units. The energy integration between SPP and GT is analyzed taking into particular account the employment of simple and complex cycle gas turbines. With regard to this, three different gas turbine has been considered: simple Brayton cycle, regenerative cycle and reheat cycle. Each of these cycles has been considered for feed water repowering of three different existing steam power plants. Moreover, the energy integration between the above plants has been analyzed taking into account three different assumptions for the SPP off-design conditions. In particular it has been established to keep the nominal value for steam turbine power output or for steam flow-rate at the steam turbine inlet or, finally, for steam flow-rate in the condenser.
The numerical analysis has been carried out by the employment of numerical models regarding SPP and GT, developed by the authors. These models have been here properly connected to evaluate the performance of the repowered plants.
The results of the investigation have revealed the interest of considering the use of complex cycle gas turbines, especially reheat cycles, for the feed water repowering of steam power plants. It should be taken into account that these energy advantages are determined by a repowering solution, i.e. feed water repowering which, although it is attractive for its simplicity, do not generally allows, with Brayton cycle, a better exploitation of the energy system integration in comparison with other repowering solutions. Besides these energy considerations, an analysis on the effects induced by repowering in the working parameters of existing components is also explained.
Identification of Mechanical Alterations From Their Effect on Performance of a Radial Compressor
Authors: Mathioudakis K. , Tsalavoutas A. 
Published: February 2015

An experimental study of the influence of mechanical alterations in a stage of a radial compressor with a vaned diffuser is presented. The mechanical alterations considered correspond to changes which can be produced by the occurrence of faults or deterioration of the compressor. They include the insertion of an inlet obstruction, an obstruction in a diffuser passage, increase of impeller tip clearance, and impeller fouling.
The change in the compressor performance parameters, from the reference condition, is established from the experimental results. These changes are referred to the overall stage performance but also to its components, impeller, and diffuser. In order to establish diagnostic abilities, appropriate indices are introduced. The behaviour of these indices is related to the altered stage conditions and the possibility of using them for identifying the stage condition is demonstrated.
Characteristic Time Modeling of NOx Emissions and Combustion Efficiency for a Staged Combustion Ramjet
Authors: Rich John T. , Mellor Arthur M. 
Published: February 2015

The semi–empirical characteristic time model (CTM), in which algebraic equations based on first principles have been validated, primarily for turbine engines, for the correlation of combustor behavior (NOx and CO emissions, combustion efficiency, lean blowoff, and lean lightoff) is examined for its applicability to staged combustion ramjets. The CTM was chosen as some success has been observed in collapsing data from different turbine combustors and in predicting performance for other configurations using a single set of model constants. Its independent parameters are times characteristic of turbulent mixing, chemistry, and fuel spray evaporation. These times are expressed in terms of combustor geometry, inlet conditions, fuel properties, and injector design.
Tests of the ramjet combustor were conducted at United Technologies Research Center with varying inlet temperature, pressure, equivalence ratio and combustion length, and the predictions are compared with the measurements. First, however, significant model development was conducted because of a number of design differences between the staged combustion concept and the configurations with which the model was originally validated. A method for computing the fraction of total air flow participating in combustion at the various fuel injection locations is postulated. The results obtained in this study are encouraging, particularly for NOx, and suggest additional tests required for staged combustion CTM development.
Extended Duration Thermal Stability Test of Improved Thermal Stability Jet Fuels
Authors: Dieterle Gordon L. , Binns Kenneth E. 
Published: February 2015

A single-pass, dual heat exchanger system called the Extended Duration Thermal Stability Test (EDTST) system was developed for evaluating jet fuel thermal stability. Various JP-8 fuels and thermal stability additives have been evaluated in the system. The test results indicate that additives can substantially improve the thermal stability of conventional jet fuels. Relationships of bulk and wetted wall temperatures on coking deposits that form in heated tubes have also been evaluated.
To date, tests conducted with EDTST have verified that additives can improve the thermal stability of JP-8 fuels. The goal of operating at wetted wall temperatures of 260°C (500°F) has been achieved. The goal for bulk fuel temperatures of 218°C (425°F) with no deposits has not been achieved. Additional additive candidates are to be evaluated in the EDTST system to identify additives that meet both the wetted wall and bulk fuel temperature goals of this program. However, if the bulk temperature goal cannot be totally achieved, the JP-8 fuel specification will most probably be changed to take advantage of the wetted wall temperature improvement already demonstrated by a JP-8+100 additive candidate.
Aerodynamics of a Centrifugal Compressor Impeller With Transonic Inlet Conditions
Authors: Krain H. , Hoffmann B. , Pak H. 
Published: February 2015

Performance and laser measurement results are presented for a transonic centrifugal compressor stage, equipped with a backswept rotor designed for 586 m/s tip speed and a mean relative inlet tip Mach number of 1.30.
The flow field features of the rotor are analysed in detail with the help of laser measurements and the results obtained from a 3D viscous calculation. Both laser measurements and calculations are carried out for the impeller’s design point and a comparison between measured and calculated data is presented for four measurement planes representing the inlet, exit and channel flow conditions. The maximum relative Mach number is found to be 1.45 and a jet/wake type flow exists in the rear part of the flow channel with the wake concentrating in the shroud region. For the operating point investigated, the wake development is due more to the strong shroud curvature in the meridional plane than to a shock induced boundary layer separation. Laser measurements and calculations point to a significant flow displacement in the impeller exit region caused by the wake flow. The theoretical results indicate that a flow separation occurs also at the front side of the vaneless diffuser.
Experimental Investigation in Annular Compressor Cascades at Transonic Flow Conditions
Authors: Schulz K. , Dalbert P. , Bölcs A. 
Published: February 2015

The paper describes flow measurements in an annular compressor cascade at sub- and supersonic inlet flow conditions. The investigation is concentrated on the evolution of the flow field along the blade passage.
A homogeneous flow could be realized in the test section at midspan with carefully directed suction by a splitter downstream of the blade passage.
Two typical compressor cascades (Multiple circular arc profile (MCA) and controlled diffusion (C.D.)) have been investigated at similar inlet flow conditions in the whole operating range with a maximum relative inlet Mach number of about 1.3.
Detailed flow measurements have been performed over several axial and radial positions along the whole blade passage. The velocity vectors have been measured with a Laser-2-Focus anemometer and the total pressure with miniature pilot-probes. Cascade overall performance, blade-surface-pressure-distributions and flow-visualization are presented.
The obtained results show that the blade shape has a strong influence on the loss behavior especially at off design conditions and on the shock system influencing the whole flow field of the blade row. Different boundary layer evolution on the suction side (measured with Laser-2-Focus) causes the shock to be fixed or in fluctuation resulting in different losses (shock-, profile-, overall losses).