bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hyperbaric oxygen therapy activates hypoxia‐inducible factor 1 (HIF‐1), which contributes to improved wound healing in diabetic mice
Authors: Sunkari Vivekananda Gupta , Lind Folke , Botusan Ileana Ruxandra , Kashif Abad , Liu Zhao‐Jun , Ylä‐Herttuala Seppo , Brismar Kerstin , Velazquez Omaida , Catrina Sergiu‐Bogdan 
Published: December 2014

AbstractHyperbaric oxygen (HBO) therapy has been used as an adjunctive therapy for diabetic foot ulcers, although its mechanism of action is not completely understood. Recently, it has been shown that HBO mobilizes the endothelial progenitor cells (EPCs) from bone marrow that eventually will aggregate in the wound. However, the gathering of the EPCs in diabetic wounds is impaired because of the decreased levels of local stromal‐derived factor‐1α (SDF‐1α). Therefore, we investigated the influence of HBO on hypoxia‐inducible factor 1 (HIF‐1), which is a central regulator of SDF‐1α and is down‐regulated in diabetic wounds. The effects of HBO on HIF‐1α function were studied in human dermal fibroblasts, SKRC7 cells, and HIF‐1α knock‐out and wild‐type mouse embryonic fibroblasts using appropriate techniques (Western blot, quantitative polymerase chain reaction, and luciferase hypoxia‐responsive element reporter assay). Cellular proliferation was assessed using H3‐thymidine incorporation assay. The effect of HIF in combination with HBOT was tested by inoculating stable HIF‐1α‐expressing adenovirus (Adv‐HIF) into experimental wounds in db/db mice exposed to HBO. HBO activates HIF‐1α at several levels by increasing both HIF‐1α stability (by a non‐canonical mechanism) and activity (as shown both by induction of relevant target genes and by a specific reporter assay). HIF‐1α induction has important biological relevance because the induction of fibroblast proliferation in HBO disappears when HIF‐1α is knocked down. Moreover, the local transfer of stable HIF‐1α‐expressing adenovirus (Adv‐HIF) into experimental wounds in diabetic (db/db mice) animals has an additive effect on HBO‐mediated improvements in wound healing. In conclusion, HBO stabilizes and activates HIF‐1, which contributes to increased cellular proliferation. In diabetic animals, the local transfer of active HIF further improves the effects of HBO on wound healing.
Measurement Uncertainties Encountered During Gas Turbine Driven Compressor Field Testing
Authors: Brun Klaus , Kurz Rainer 
Published: December 2014

Field testing of gas turbine compressor packages requires the accurate determination of efficiency, capacity, head, power and fuel flow in sometimes less than ideal working environments. Nonetheless, field test results have significant implication for the compressor and gas turbine manufacturers and their customers. Economic considerations demand that the performance and efficiency of an installation are verified to assure a project’s return on investment. Thus, for the compressor and gas turbine manufacturers, as well as for the end-user, an accurate determination of the field performance is of vital interest. This paper describes an analytic method to predict the measurement uncertainty and, thus, the accuracy, of field test results for gas turbine driven compressors. Namely, a method is presented which can be employed to verify the validity of field test performance results.
The equations governing the compressor and gas turbine performance uncertainties are rigorously derived and results are numerically compared to actual field test data. Typical field test measurement uncertainties are presented for different sets of instrumentation. Test parameters that correlate to the most significant influence on the performance uncertainties are identified and suggestions are provided on how to minimize their measurement errors. The effect of different equations of state on the calculated performance is also discussed.
Results show that compressor efficiency uncertainties can be unacceptably high when some basic rules for accurate testing are violated. However, by following some simple measurement rules and maintaining commonality of the gas equations of state, the overall compressor package performance measurement uncertainty can be limited and meaningful results can be achieved.
Turbomachinery Blade Design Using a Navier-Stokes Solver and Artificial Neural Network
Authors: Pierret Stéphane , Van den Braembussche R. A. 
Published: December 2014

This paper describes a knowledge-based method for the automatic design of more efficient turbine blades. An Artificial Neural Network (ANN) is used to construct an approximate model (response surface) using a database containing Navier Stokes solutions for all previous designs. This approximate model is used for the optimization, by means of Simulated Annealing (SA), of the blade geometry which is then analyzed by a Navier-Stokes solver.
This procedure results in a considerable speed-up of the design process by reducing both the interventions of the operator and the computational effort. It is also shown how such a method allows the design of more efficient blades while satisfying both the aerodynamic and mechanical constraints. The method has been applied to different types of 2D turbine blades of which three examples are presented in this paper.
Investigation of Detailed Film Cooling Effectiveness and Heat Transfer Distributions on a Gas Turbine Airfoil
Authors: Drost U. , Bölcs A. 
Published: December 2014

In the present study film cooling effectiveness and heat transfer were systematically investigated on a turbine NGV airfoil employing the transient liquid crystal technique and a multiple regression procedure. Tests were conducted in a linear cascade at exit Reynolds numbers of 0.52e6, 1.02e6 and 1.45e6 and exit Mach numbers of 0.33, 0.62 and 0.8, at two mainstream turbulence intensities of 5.5% and 10%. The film cooling geometry consisted of a single compound angle row on the pressure side (PS), and a single or a double row on the suction side (SS). Foreign gas injection was used to obtain a density ratio of approximately 1.65, while air injection yielded a density ratio of unity. Tests were conducted for blowing ratios of 0.25 to 2.3 on the SS, and 0.55 to 7.3 on the PS.
In general film cooling injection into a laminar BL showed considerably higher effectiveness in the near hole region, as compared to a turbulent BL. While mainstream turbulence had only a weak influence on SS cooling, higher effectiveness was noted on the PS at high turbulence due to increased lateral spreading of the coolant. Effects of mainstream Mach and Reynolds number were attributed to changes of the BL thickness and flow acceleration. Higher density coolant yielded higher effectiveness on both SS and PS, whereas heat transfer ratios were increased on the SS and decreased on the PS. Comparison of the single and double row cooling configurations on the SS revealed a better film cooling performance of the double row due to an improved film coverage and delayed jet separation.
The Use of Case-Based Reasoning Technology to Aid Fault Isolation in a Modern Gas Turbine Engine Design
Authors: Hargrave S. M. , Fleming P. J. 
Published: December 2014

The increasing numbers of commercial decision support tools based on Case-Based Reasoning (CBR) technology reflects the interest in the use of this technology to aid fault diagnosis, not only in gas turbine applications but also in the wider engineering domain. CASSIOPEE from CFM and ARIADNE from British Airways are but two examples of these types of support tool in the civil gas turbine engine arena. They reflect the trend of developing such systems from a historical database of maintenance arisings and necessarily apply to older engine designs. Further characteristics of which include older and less sophisticated aircraft maintenance systems, which provide limited diagnostic information and rely more heavily upon the experience of maintenance personnel to isolate engine faults successfully. It is this diagnostic experience which these CBR tools have attempted to capture and emulate; the case for a CBR-based tool in this instance is well proven.
More recent aircraft design have resulted in a more comprehensive on-board maintenance systems to aid maintenance personnel diagnose airframe and engine faults. Such an approach should rely less heavily upon the experience of the maintenance crew to isolate a fault successfully. The paper reports on the design and development of two CBR-based maintenance decision support tools for the Rolls-Royce Trent 800 and RB211-524 engines. One system is currently undergoing a trial to refine the design of the maintenance case base (the database over which the CBR engine searches to match the current fault symptoms to a historical event). The lessons learned from this field trial and future prospects for such a CBR-based maintenance aid are discussed.
Sawmill, Wood Waste Fuelled, 100% Recuperated, 5 MW Gas Turbine Co-Generation Plant
Authors: Lefcort Malcolm D. , Skodje E. L. S. (Ted) 
Published: December 2014

Sawmills in the Canadian province of British Columbia (BC) will soon be confronted with a collective wood waste disposal problem (bark, sawdust and shavings) of about 3 Million bone dry tonne/y at an average wet basis moisture content of about 45%. About 40 existing sawmill beehive burners presently incinerate this waste. Emissions from these beehive burners exceed current provincial particulate limits. Markets for the waste — board plants, sawdust digesters, charcoal plants, etc. — are limited. The economics of 25 to 50 MW wood-fired, steam power plants is poor. 6¢/kW.h is needed to finance a plant; the major utility offers 2¢/kW.h.
This paper describes a 3 MW to 5 MW, Nuovo Pignone PGT-5 co-generation plant fuelled by the 2000°F (1093°C) exhaust from a Heuristic EnvirOcycler, a two-stage, wood waste incinerator. The exhaust meets BC’s particulate limit of 0.052 grains/dscf (120 mg/Nm3). 37 to 65 Million Btu/h (39 to 68 GJ/h) of waste heat can be recovered from the system exhausts. In this application the PGT-5’s external combustion chamber is replaced by a “recuperator”, i.e., a high temperature, gas-to-air, heat exchanger.
Two variations of the basic system are examined. One features a larger than necessary EnvirOcycler to generate additional steam in the waste heat boiler. The other variation discusses heating 1,550°F (843°C) air from the recuperator up to 1,796°F (980°C) with natural gas. The extra power generated can cost as little as 1.9¢/kW.h.
Physics of Airfoil Clocking in a High-Speed Axial Compressor
Authors: Dorney Daniel J. , Sharma Om P. , Gundy-Burlet Karen L. 
Published: December 2014

Axial compressors have inherently unsteady flow fields because of relative motion between rotor and stator airfoils. This relative motion leads to viscous and inviscid (potential) interactions between blade rows. As the number of stages increases in a turbomachine, the buildup of convected wakes can lead to progressively more complex wake/wake and wake/airfoil interactions. Variations in the relative circumferential positions of stators or rotors can change these interactions, leading to different unsteady forcing functions on airfoils and different compressor efficiencies. In addition, as the Mach number increases the interaction between blade rows can be intensified due to potential effects. In the current study an unsteady, quasi-three-dimensional Navier-Stokes analysis has been used to investigate the unsteady aerodynamics of stator clocking in a 1-1/2 stage compressor, typical of back stages used in high-pressure compressors of advanced commercial jet engines. The effects of turbulence have been modeled with both algebraic and two-equation models. The results presented include steady and unsteady surface pressures, efficiencies, boundary layer quantities and turbulence quantities.
The main contribution of the current work has been to show that airfoil clocking can produce significant performance variations at the Mach numbers associated with an engine operating environment. In addition, the growth of turbulence has been quantified to aid in the development of models for the multi-stage steady analyses used in design systems.
Development of the Next Generation Gas Turbine Based Jet Air Start Unit for the US Navy
Authors: Zoccoli Michael J. , Cheeseman William H. 
Published: December 2014

Main powerplants for aircraft in the US Navy inventory typically require a source of pneumatic power in order to initiate the engine start sequence. The equipment which is used as the source for this power is termed “UNIJASU”, or Universal Jet Aircraft Start Unit.
UNIJASU is a fully self-contained, transportable source of ground power which may be adapted to both land or carrier-based operations. At the nucleus of this unit is a modified T53 aircraft gas turbine, originally developed and fielded by the Lycoming Turbine Engine Division of Stratford Conn. In the current application, the T53 has been re-configured as a gas generator with specific provisions for extensive operation in a marine environment. Using the bleed machine concept, up to 30% of the engine massflow (equating to roughly 420 air horsepower) can be delivered to an aircraft starter upon demand. The present production source for the T53 engine is the AlliedSignal Engine Company, located at Phoenix, Az.
As of the writing date (mid-1997), the US Navy is in the process of procuring its next generation air start units via contract to AlliedSignal. This paper describes the salient features of a rigorous two-phase development program starting with the initial adaptation of the aircraft turbine engine to a naval ground power unit, and culminating with over 6000hrs of system level testing, inclusive of actual field evaluations.
Flow Measurements Behind the Inlet Guide Vane of a Centrifugal Compressor
Authors: Kassens I. , Rautenberg M. 
Published: December 2014

In a centrifugal compressor adjustable inlet guide vanes (IGV) in front of the impeller are used to regulate the pressure ratio and the mass flow. The stationary measurement of the velocity profile in front of the impeller with different angles of the IGV displays shock losses at the inlet edge of blade of the impeller. In the partial-load region (e.g. partial-load efficiency) the radial distribution of the flow influences considerably the performance of the impeller.
The tested compressor consists of an adjustable IGV with straight vanes, a shrouded impeller and a vaneless, parallel diffuser. In the first measurement location, behind the IGV, total pressure, static pressure and flow angle were measured with a 5-hole cylinder probe. In the second measurement location, in front of the impeller, the measurement of the total pressure was carried out with a Kiel probe and the flow angle with a Cobra probe accordingly the static wall pressure was measured.
Taking into consideration the fundamental thermodynamical equations it was possible to determine the velocity profiles because of the measured distributions of the flow angle in these two measurement locations. For different angles of the IGV and with various mass flows the distributions of the deflection defect behind the IGV are described. Starting with the measured distributions of the flow in front of the impeller the flow angles at the impeller inlet are calculated and the distributions of the incidence angle at the impeller inlet are figured out.
Characteristics of Heat Transfer in Rotating Cavities
Authors: Jerhamre Anders , Eriksson Lars-Erik 
Published: December 2014

In rotating cavities the driving temperature difference for heat transfer is not easy to define or estimate. Traditionally, some reference temperature, here called bulk temperature, is used. This bulk temperature is closely connected to the heat transfer coefficient. In order to determine these characteristics, the assumption that the wall heat flux is linearly proportional to the temperature difference between wall and inlet air, is used. The slope is equal to the heat transfer coefficient and the x-intercept gives the difference between bulk temperature and inlet temperature. The validity of this assumption is thoroughly investigated by solving the Reynolds averaged Navier-Stokes equations for compressible, axisymmetric flow with a low Reynolds number k-ϵ-model. Rotational and buoyancy effects, which may introduce a non-linear relationship and also affect the local bulk temperature, are all taken into account in the CFD model.
Three different cases were investigated: one simple corotating disk cavity; one simple rotor-stator cavity, and finally one real engine application cavity. The rotational Reynolds numbers, mass flow rates and temperature differences were varied.
Results indicate that the Linear assumption is valid for a range of wall temperatures but not for regions where the local wall temperature affects the flow field, e.g. in corners. Furthermore, when the flow field undergoes a drastic change, new heat transfer characteristics must be determined, or be used with care. Since the heat transfer coefficient and bulk temperature are uniquely determined by the flow field, and not by the local wall temperature, it is not necessary to make a coupled, continuous calculation of the flow field and thermal distribution in the structure.
Fault Detection and Accommodation in Real Time Embedded Full Authority Digital Electronic Engine Controls
Authors: Martucci Angelo 
Published: December 2014

Fault Detection and Accommodation Logic easily occupies at least fifty percent of the real time embedded software application program in the contemporary Full Authority Digital Electronic Engine Control (FADEC). Indeed, if a layman were to look at the logic distribution in a FADEC he might think the main purpose of the FADEC was to detect failures! This, of course, is not the case. It is true, however, that real world applications must be programmed to deal with the inevitable fact that system failures will occur. The success of the application program then depends not only on how well it controls the engine, but how well it detects, isolates and accommodates failures. In other words, the fault tolerance of an application is just as important as the robustness of the control algorithms.
Over the past two decades many basic Fault Detection and Accommodation (FDA) techniques have been developed and have become commonplace in FADECs. These techniques have been developed in such a way as to maximize an application’s Built In Test (BIT) effectiveness for both “hard”, “soft”, and intermittent failures, while minimizing failure annunciation due to “false alarm” events. These techniques have been implemented in both hardware and software.
This paper will present and discuss these basic FDA techniques for input signals, output signals, processors, memory devices and communication devices. Many of the newer FDA techniques will also be discussed. An overview of the key components of FDA, and the established “norms” for effective FDA will be added for completeness. Since the structure of FDA is dependent upon system architecture, the system under consideration is chosen as the Dual-Channel Full Authority Digital Electronic Engine Control. This is the configuration that is most commonly used in commercial and military engine control applications.
Steady-State and Dynamic Performance Prediction of an Indirect Fired Gas Turbine Plant
Authors: Crosa G. , Fantini L. , Ferrari G. , Pizzimenti L. , Trucco A. 
Published: December 2014

The paper presents the first results of a research, in progress at the Istituto di Macchine e Sistemi Energetici of Genova University, about a gas-steam combined cycle with indirect fired gas-turbine.
The study has dealt with the gas turbine plant which is the most innovative part of the process. To select the design point of every component, a thermodynamic parametric analysis over a large range of pressure ratios and a large range of mass flow ratio through the two characteristic by-passes has been developed.
The off-design performances of the gas plant have been investigated and finally a proposal of control system has been made, tested using a simple mathematical model, able to analyse in the time domain the dynamic behaviour of the controlled gas plant.
Analysis of Tip Leakage Effects in a High Subsonic Annular Compressor Cascade
Authors: Bonhommet-Chabanel C. , Gerolymos G. A. 
Published: December 2014

This paper presents both experimental and numerical results of tip leakage effects in a High Speed Annular Cascade. The influence of the clearance size has been investigated. For validation purposes and a better understanding of the 3-D phenomena, a comparison of the measurements with three-dimensional Navier-Stokes computations using a k-ε closure with a low-Reynolds approach has been performed.
The high speed annular cascade facility has been specifically designed for studying tip leakage flows at the rear of high pressure compressors. In the vicinity of the clearance, the inlet swirl angle, created by a scroll, is of 60° from the axial direction and the Mach number is about 0.60. The blades are cantilevered (fixed on the casing with a clearance gap at the rotating inner wall). In order to obtain a picture of the flow field as complete as possible, different kinds of measurements have been used. 3D velocity measurements within the blade passages have been performed by means of a 3-D Laser Doppler Anemometer system. Furthermore, a five-hole probe with long stem was also used in the blade passage.
The experimental data are quite detailed and self-consistent. A leakage vortex can clearly be identified and, within the blade passage, seems to be responsible for a region of overturning above it. The clearance size has a direct impact on the inception point of the phenomena and on the direction and strength of the leakage vortex. The calculation was found to reproduce the same trends as the experiment and give good quantitative comparisons, although it overestimates the leakage effect at blade exit.
Intercooled and Brayton Cycle Gas Turbines for Steam Power Plant Hot Windbox Repowering
Authors: Negri di Montenegro G. , Gambini M. , Peretto A. 
Published: December 2014

In the present paper the performance of a hot windbox repowering steam power plant are evaluated.
A methodology has been developed to determine the mass flow rate range of gas turbine exhaust gas injected into a steam generator of an existing steam power plant.
The study allowed to evaluate the performance of the repowered plant for different gas turbine available on the market.
By utilizing the same methodology, this repowering solution was also investigated employing an intercooler gas turbine that, in the state of art, may be realistically proposed.
It resulted that the hot windbox repowering with Brayton cycle gas turbine supplies a considerably higher power output and efficiency than those of the steam power plant before the repowering.
The employing of an intercooled gas turbine provides further improvements of power and efficiency with respect to the repowered plant using the Brayton cycle gas turbine.
Air System Correlations: Part 2 — Rotating Holes and Two Phase Flow
Authors: Zimmermann H. , Kutz J. , Fischer R. 
Published: December 2014

Three important subjects of the physics of air systems have been chosen:
Part 1: Labyrinth Seals
Part 2: Rotating Holes and Two Phase Flow
In these fields many new papers are available. Correlations out of the literature for the discharge coefficients of rotating holes which include the most important parameters are compared and discussed. For two phase flow simple correlations for engineering purposes are recommended, especially for vent lines of aero engines. It is concluded that much more effort is required in order to push knowledge beyond the state of current literature which is partly controversial and not comprehensive enough for computerized engineering.