bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hypoxic pulmonary vasoconstriction, carotid body function and erythropoietin production in adult rats perinatally exposed to hyperoxia
Authors: Prieto‐Lloret Jesus , Ramirez Maria , Olea Elena , Moral‐Sanz Javier , Cogolludo Angel , Castañeda Javier , Yubero Sara , Agapito Teresa , Gomez‐Niño Angela , Rocher Asuncion , Rigual Ricardo , Obeso Ana , Perez‐Vizcaino Francisco , González Constancio 
Published: April 2015

Key points
Adult animals that have been perinatally exposed to oxygen‐rich atmospheres (hyperoxia), recalling those used for oxygen therapy in infants, exhibit a loss of hypoxic pulmonary vasoconstriction, whereas vasoconstriction elicited by depolarizing agents is maintained.
Loss of pulmonary hypoxic vasoconstriction is not linked to alterations in oxygen‐sensitive K+ currents in pulmonary artery smooth muscle cells.
Loss of hypoxic vasoconstriction is associated with early postnatal oxidative damage and corrected by an antioxidant diet.
Perinatal hyperoxia damages carotid body chemoreceptor cell function and the antioxidant diet does not reverse it. The hypoxia‐elicited increase in erythropoietin plasma levels is not affected by perinatal hyperoxia.
The potential clinical significance of the findings in clinical situations such as pneumonia, chronic obstructive pulmonary disease or general anaesthesia is considered.
AbstractAdult mammalians possess three cell systems that are activated by acute bodily hypoxia: pulmonary artery smooth muscle cells (PASMC), carotid body chemoreceptor cells (CBCC) and erythropoietin (EPO)‐producing cells. In rats, chronic perinatal hyperoxia causes permanent carotid body (CB) atrophy and functional alterations of surviving CBCC. There are no studies on PASMC or EPO‐producing cells. Our aim is to define possible long‐lasting functional changes in PASMC or EPO‐producing cells (measured as EPO plasma levels) and, further, to analyse CBCC functional alterations. We used 3‐ to 4‐month‐old rats born and reared in a normal atmosphere or exposed to perinatal hyperoxia (55–60% O2 for the last 5–6 days of pregnancy and 4 weeks after birth). Perinatal hyperoxia causes an almost complete loss of hypoxic pulmonary vasoconstriction (HPV), which was correlated with lung oxidative status in early postnatal life and prevented by antioxidant supplementation in the diet. O2‐sensitivity of K+ currents in the PASMC of hyperoxic animals is normal, indicating that their inhibition is not sufficient to trigger HPV. Perinatal hyperoxia also abrogated responses elicited by hypoxia on catecholamine and cAMP metabolism in the CB. An increase in EPO plasma levels elicited by hypoxia was identical in hyperoxic and control animals, implying a normal functioning of EPO‐producing cells. The loss of HPV observed in adult rats and caused by perinatal hyperoxia, comparable to oxygen therapy in premature infants, might represent a previously unrecognized complication of such a medical intervention capable of aggravating medical conditions such as regional pneumonias, atelectases or general anaesthesia in adult life.
Description of an Industry–University Liaison: Rolls-Royce Scottish Factories–Glasgow University 1968–84
Authors: Maccallum N. R. L. , Reford F. S. 
Published: April 2015

The paper describes the liaison that has developed between Rolls-Royce Limited (Scottish Factories) and the Department of Mechanical Engineering of the University of Glasgow and indicates the benefits that have been obtained by both sides.
Of benefit to the University have been stimulating contacts with industry, from which have come topics for meaningful investigations, both in projects by undergraduates and in research by postgraduates and staff. Students at the University have also benefited by being able to visit Rolls-Royce’s Scottish Factories, and have Rolls-Royce staff give lectures to the Engineering Society.
One advantage to Rolls-Royce is that students at Glasgow University have had frequent contacts with the Company and are aware of its aims and achievements. Also, there has been technical benefit to the Company from the general research and from several specific studies carried out on a consultancy basis.
Assessment of a Failure Probability Prediction Technique for Ceramic Heat Exchanger Components
Authors: Smith Kenneth O. , Poeppel Roger B. 
Published: April 2015

A study was conducted to establish analytical design techniques for predicting the failure probability of ceramic heat exchanger components. Three test specimen geometries representing subscale components of an axial flow, tubular ceramic heat exchanger were selected for evaluation. Failure probability predictions for the specimens subjected to mechanical loads were made using finite element stress and two-parameter Weibull analyses. Weibull parameters for sintered alpha-SiC were determined using as-sintered flexure bars in four-point-bend strength tests.
Assessments of the prediction accuracy were made by failure testing populations of the three specimen geometries fabricated using sintered alpha–SiC. Tests were conducted at ambient conditions and with a rapid loading rate. Experimental results indicate that reasonably accurate failure probability predictions can be made.
A General Program for the Prediction of the Transient Performance of Gas Turbines
Authors: Pilidis P. , Maccallum N. R. L. 
Published: April 2015

The paper describes a general program which has been developed for the prediction of the transient performance of gas turbines. The program is based on the method of continuity of mass flow. It has been applied successfully to a wide range of aero gas turbines, ranging from single to three-spool and from simple jet to bypass types with or without mixed exhausts. The results for three of these engine types are illustrated. Computing times are reasonable, increasing with the complexity of the engine.
A parallel paper describes the inclusion of thermal effects in the prediction program.
Fan Blade Flutter: Single Blade Instability or Blade to Blade Coupling?
Authors: Széchényi Edmond 
Published: April 2015

Different types of fan blade flutter occur at the various compressor flow regimes. Sub/transonic stall flutter and two forms of supersonic started flow flutter have been studied in a straight cascade wind tunnel. Results show clearly that these three common forms of flutter can exist as single-degree-of-freedom (single-blade instabilities). Cascade effects, though at times important, are never the only flutter mechanism: flutter limits are essentially controlled by single-blade aeroelastic coefficients, though blade-to-blade coupling arising from cascade effects can modify these limits according to the mode order.
Thus, contrary to widespread practice, the fundamental approach to flutter problems should lie at least as much in the study of single blade flutter as in that of unsteady cascade effects. The two should anyhow best be considered separately when searching for a better physical insight.
Blade Vibration on Centrifugal Compressors: Blade Response to Different Excitation Conditions
Authors: Haupt U. , Bammert K. , Rautenberg M. 
Published: April 2015

Results and analysis of blade vibration measurements on a high pressure ratio / high mass flow centrifugal compressor made with strain gages and using multichannel telemetry are described for compressors with 3 different types of vaned diffusers. Considerable high frequency blade excitation and vibration of the shallow region near the impeller outlet were observed. Initial progress to predict this dangerous excitation caused by the diffuser vanes was made with the help of FE computations using a simplified element system consisting of the vibrating zones of a 90° sector of the impeller. Satisfactory agreement with measured vibration data was achieved.
The influence of rotating stall on blade excitation was investigated using different types of vaned diffusers leading to different numbers of rotating stall zones and variations in the rotational speed of the cells. Blade vibration intensity due to surge in conjunction with variations of the diffuser is also considered.
Holographic interferometry was successfully applied to blade vibration measurements on compressors in operation. The investigation was aimed at studying the occurrence of blade modes and the vibratory behavior of the different blades near the interesting inlet zone. The occurrence of different constellations of blade modes at a resonance point and at an operating point far from resonance was demonstrated.
The Effect of Thermal Matching on the Thermodynamic Performance of Gas Turbine and IC Engine Cogeneration Systems
Authors: Baughn J. W. , Bagheri N. 
Published: April 2015

Computer models have been used to analyze the thermodynamic performance of a gas turbine (GT) cogeneration system and an internal combustion engine (IC) cogeneration system. The purpose of this study was to determine the effect of thermal matching of the load (i.e., required thermal energy) and the output steam fraction (fraction of the thermal output, steam and hot water, which is steam) on the thermodynamic performance of typical cogeneration systems at both full and partial output.
The thermodynamic parameters considered were; the net heat rate (NHR), the power to heat ratio (PHR), and the fuel savings rate (FSR). With direct use (the steam fractions being different); the NHR of these two systems is similar at full output, the NHR of the IC systems is lower at partial output, and the PHR and the FSR of the GT systems is lower than the IC systems over the full range of operating conditions. With thermal matching (to produce a given steam fraction) the most favorable NHR, PHR, and FSR depends on the method of matching the load to the thermal output.
An Experimental Investigation of Response of a Turbojet Engine to Inlet Distortion
Authors: Fuqun Chen , Wenlan Li , Zongyuan Wang , Mengzi Cong 
Published: April 2015

A study of the response of a turbojet engine to the steady-state and the turbulence-type dynamic inlet distortion is presented in this paper. The steady-state distortion is generated by a 180° extent, 36 mesh screen, and the turbulence-type dynamic distortion by a 180° extent plate with 50% blockage ratio at the engine face. This plate can produce a very strong pressure fluctuation at the engine face. The statistical analysis shows that the APD of pressure fluctuation follows approximately the Normal Distribution except those cases near rotating stall or surge.
Results from testing show: 1) inlet distortion generated by screen will produce a classical-surge or deep-surge (defined in ref. 1); 2) the degree of distortion by screen can change the mode of surge, e.g. from the classical-surge to the deep-surge and vice versa; 3) both the inlet distortion and the decrease in first-stage-turbine-nozzle area will change the compressor performance maps; 4) the turbulence-type dynamic distortion causes a “drift-surge” (defined in ref. 2).
Gas Turbines in Cogeneration: Overall Analysis and Numerical Predictions
Authors: Manfrida G. , Stecco S. S. , Galletti A. 
Published: April 2015

A methodology for the performance analysis of gas turbines for cogeneration applications is presented. Energy and exergy balances allow presentation of data in terms of either conventional or second-law parameters, as well as examination of the trends with respect to cycle variables and cogeneration options.
The results show that, even though gas turbines (and particularly regenerative solutions) are very flexible for cogeneration purposes, care has to be exercised in matching thermal energy production conditions and cycle variables in order to achieve optimal performance.
Aerodynamic Research on Straight Wall Annular Diffuser for Turbofan Augmentor
Authors: Xie Q. M. , Gu J. G. 
Published: April 2015

The effect of non-uniform inlet velocity and temperature profile on the aerodynamic performance of straight wall annular diffuser for turbofan augmentor has been investigated.
The distribution of static pressure, stagnation pressure and temperature has been measured, thus pressure recovery coefficient, velocity profile and temperature profile at different axial station along the diffuser center line can be determined.
The experimental results showed that the momentum ratio ρ¯eV¯e2/ρ¯iV¯i2 of two streams across the diffuser inlet flow splitter is the non-dimensional flow parameter controlling diffuser aerodynamic performance. Thus, it is possible to simulate turbofan augmentor annular diffuser perfomance by using low temperature air flow aerodynamic test under the condition that the diffusers are of similar geometry, have the same inlet velocity profile and maintain the momentum ratio constant.
A correlation for the velocity distribution in the diffuser was also obtained.
Investigation and Experiment on Optimizing Angles of Variable Stator of Axial Flow Compressor
Authors: Lihua Wu , Fusheng Huang , Feng Liu , Yanli Wang 
Published: April 2015

This paper presents the calculation of optimal restagger and test method for ten-stage subsonic axial flow compressor with four rows of variable stator. The test results show that both are in close agreement.
The test results show that the overall compressor performance with optimal restaggers was significantly improved in comparison with the original. The efficiency at mid-speed increased by 12.7%. Surge margin reaches 31.2%. The total range of operation for compressor was expanded by 34%.
A Correlation for the Secondary Deviation Angle
Authors: Massardo Aristide , Satta Antonio 
Published: April 2015

This paper describes a correlation for the evaluation of the spanwise distribution of the secondary deviation angle. This correlation is made through the use of a theoretical method for the calculation of secondary flow which includes the effects of viscosity.
The correlation considers the influence of the spacing and height of the blade, inlet and outlet flow angles, inlet boundary layers and velocity ratio.
The results are compared with the experimental data of various turbine cascade. The agreement is good for most of the cases.
A Cost-Effective Performance Development of the PT6A-65 Turboprop Compressor
Authors: Yoshinaka Tsukasa , Thue Kenneth S. 
Published: April 2015

The largest member of the PT6 turboprop engine family, the PT6A-65, was developed in the early 1980’s and went into production in September 1982. The compressor for this engine consisted of four new axial stages combined with an existing centrifugal stage on a single shaft. This paper gives a brief description of the studies leading up to the choice of the compressor configuration and a more detailed examination of the development of the chosen compressor to the required performance level.
The development of this compressor presented a two-fold technical challenge. Firstly, the limited space in the small compressor gas path did not permit the effective use of conventional total pressure and temperature probes for performance evaluation. Secondly, the short time available for development excluded some attractive corrective measures such as the redesign of some of the axial blade rows because the time required would have jeopardized the meeting of the tight development deadline. The first problem was overcome by a combination of limited wall static pressure measurements and an extensive use of numberical flow analysis codes. This approach proved to be quite cost-effective. The second was solved by the adaptation of an existing fully analytically-designed research axial stage to the first stage position in the axial compressor.
Gas Turbine Driven Centrifugal Compressors for Gas Storage and Withdrawal Applications
Authors: Hornberger Horst , Wockenfuss Albrecht , Schmidt Klaus D. 
Published: April 2015

The increasing acceptance of natural gas as primary energy in different market segments and the variance in consumption between the seasons require more and more buffer storage capacity, because of contracted constant gas supply quantities.
The surplus gas becoming available during the summer time can be stored and withdrawn during the winter time for covering peak demands.
Based on these facts, the gas distribution companies utilize exploited gas fields for gas storage by drilling additional wells and installing gas compression facilities.
Such a compression duty with a wide range in flow and discharge pressure requires a great flexibility of the compression equipment, including high reliability and availability during operation periods.
SIC Radial Turbine Rotor Development — Material, Design and Fabrication Influences
Authors: Langer Manfred , Siebels Johann E. , Heinrich Hartmut , Schwetz Karl A. 
Published: April 2015

With reference to two batches of rotors, the discussion of component development results shows the problem areas in the fabrication, quality inspection and testing of ceramic radial rotors.
Following the evaluation of the present results, future development work must concentrate on the improvement of
- material quality (microstructure, strength)
- component fabrication, i.e. injection molding - binder removal - sintering
- mechanical finishing
- joining techniques.
Numerical Computation of Three-Dimensional Rotational Inviscid Subsonic Flows, Using the Decomposition of the Flow Field Into a Potential and a Rotational Part
Authors: Chaviaropoulos P. , Giannakoglou K. , Papailiou K. D. 
Published: April 2015

The strongly rotational, three-dimensional, steady, inviscid, subsonic flow field in ducts is calculated using the decomposition of the mass flux vector field into a potential and a rotational part.
The resulting formulation requires the solution of two elliptic equations and a procedure for handling the transport of vorticity. A modified strongly implicit finite difference procedure is used for the solution of the elliptic equations, while the transport equations are handled in their Lagrangean form. In the present work, the algorithm, the boundary conditions and the convergence characteristics of the solution are discussed. Numerical results are presented for a rectangular elbow of 90 degrees of turning.
A Study of the Effect of Deterioration on Compressor Surge Margin in Constant-Speed, Single-Shaft Gas Turbine Engines
Authors: Dundas Robert E. 
Published: April 2015

A mathematical model of a constant-speed single-shaft gas turbine was devised using a typical compressor map. Performance calculations were performed at various ambient temperatures based on a standard temperature control system for a number of possible component deterioration modes. The effects on compressor operating line were determined.
It was found that only two modes of deterioration; reduction of compressor flow capacity either through fouling or through erosion and closing of turbine nozzle diaphragms, moved the operating line toward surge. Inlet filter clogging must also be minimized in order to avoid surge because resulting distortion can induce stall and surge.
Experimental Unsteady Shock-Boundary Layer Interaction at Single Blades and in Linear Cascades
Authors: Gallus H. E. , Broichhausen K.-D. , Henne J. M. 
Published: April 2015

Self-excited vibrations of transonic blading in turbomachines are partly due to unsteady viscous flow effects and shock-boundary layer interaction. To investigate the unsteady flow, experiments have been performed in a transonic windtunnel at single blades and in a cascade, where the central blade is either mounted elastically or driven by electromagnetic shakers to torsional vibration.
The unsteady flow is measured by a stroboscopic schlieren-method including high-speed movies and a recently developed laser-density gradient-technique. The vibration of the blade is controlled by strain gauges.
The test results reveal:
- severe shock wave and boundary layer oscillations occur with separation alternating between shock-induced and trailing edge separation,
- the unsteadiness of the flow largely depends on Mach- and Reynolds number,
- with pitching vibration of the blade, forced and self-excited shock wave oscillations interfere with each other.
Multiaxial Life Prediction System for Turbine Components
Authors: Arvanitis S. T. , Symko Y. B. , Tadros R. N. 
Published: April 2015

The objective of this paper is to present a complete 3–D life prediction system which was developed for turbine engine components. It will primarily deal with turbine blades and vanes which are subjected to hostile thermal and combustion environments under load which creates cyclic and/or steady multiaxial stress and strain fields. All of the above factors combined are detrimental to the service life of these components and need very careful consideration at the design stage.
The developed multiaxial system for a mission includes evaluation of transient metal temperatures, corresponding elastic and inelastic strains, creep strains and subsequently creep/fatigue lives. The calculations are performed using the ductility exhaustion method. The maximum principal normal strain ranges used in the life analysis are found by a developed procedure for a multi-axial system. The concept is based on analyzing all of the time steps computed in the mission, in order to develop the maximum principal normal strain range whose direction and magnitude is strictly a function of the component geometry and mission loading. The mission creep is then developed by maximizing a cumulative creep function. Directional consistency is maintained in accumulating creep/fatigue damage with respect to the incurred multiaxial stress and strain fields. Also the most damaging mission modes (creep or fatigue) will be separated. Further development in the model includes the capability of analytically obtaining the fatigue curve for any ratio (R) of minimum to maximum strain using baseline fatigue material properties (R=−1.0). Application of the model to an actual uncooled vane correlates well with test rig development experience.
A Simple Calculation Method for Ratio of Relative Velocity Within Centrifugal Impeller Channel
Authors: Mizuki Shimpei , Watanabe Ichiro 
Published: April 2015

A simple but accurate method of calculating ratio of relative velocities within centrifugal impeller channels is proposed using a one-dimensional flow model, whose major parameters are specific speed, non-dimensional root-mean square radius of the inducer inlet, slip factor, flow coefficient and flow angle at impeller exit. After the non dimensional relative velocity at inducer inlet and that at impeller exit are derived, the ratio of relative velocity at impeller exit to that at inducer inlet is obtained. In addition to this, the ratio is divided into two parts: one ratio for the inducer portion and another ratio for the radial portion of the impeller channel.
The computations are conducted both for adiabatic inviscid flow and for two conditions assumed for viscous flow, in which one used an empirical relationship between the total pressure ratio and the peripheral speed of impeller and the other used experimental values for the total pressure ratio as a funtion of the flow rate. By the present simple method, the non-dimensional relative velocities as well as the ratios of the relative velocities for the inlets and the exits of an inducer and an impeller channel are calculated accurately.