bluuebunny/crossref_metadata_2025_split huggingface dataset:
Boundary Layer Effects on the Transonic Flow in a Straight Turbine Cascade
Authors: Štastný M. , Šafařík P. 
Published: March 2015

The analysis presented here deals with two subjects related to the transonic flow in a straight turbine cascade:
1) turbulization of the suction side boundary layer and its subsequent development along the profile
2) influence of side wall boundary layers on cascade flows.
The turbulization effect of supersonic compression on the boundary layers which accompany transonic expansion on the suction side of the profile is investigated by independent methods. Both the experimental results and the calculation confirm the loss of stability of the laminar boundary layer and its subsequent transition into turbulence in the region of an adverse pressure gradient. Also the possibility of reverse transition of turbulent boundary layer in a subsequent strong favourable pressure gradient is investigated.
The contraction effect of the wind tunnel side wall boundary layers is expressed by means of the AVDR factor over a wide range of flow regimes determined by the incidence angle and the Mach number. A correction of the exit flow angle from the cascade is made to obtain a purely 2D flow although it is apparent that the measured exit angle values and the exit angle obtained for a 2D flow differ considerably.
Transonic Flow Through Turbine Cascades With Nonuniform Pitch
Authors: Kurz R. 
Published: March 2015

The flow behind linear turbine cascades with uniform and nonuniform pitches was investigated both theoretically and experimentally.
A calculation procedure based on an Euler–code for nonuniform pitch to chord ratios is presented. Experimental data were obtained by using a Laser–2–Focus measurement system and Kiel probes. Outlet Laval numbers range from 0.7 to 1.0, corresponding to Reynolds numbers from 380,000 to 700,000. The pitch–to–chord ratio of the investigated configurations reaches from 0.771 to 0.877.
Non-Steady Flow Measurements Inside a Hydrodynamic Torque Converter by Hot-Film Anemometry
Authors: Browarzik V. , Grahl K. G. 
Published: March 2015

The overall-characteristics of hydrodynamic torque converters have been discussed often, although there is little knowledge about the flow field inside the circuit. During former investigations at our institute flow measurements have been made and a CFD-program was developed to calculate the flow through the guide vanes and the pump impeller.
Our present studies now examine the non-steady flow field at the inlet and outlet of the pump and the turbine impeller by means of hot-film anemometry and a computer based measuring system. The measuring techniques have been developed and now measurements are made at different operating points. Later the measurements will be performed with special regard to non-steady changes of operating conditions.
The paper describes the test facilities, the measuring equipment and the techniques used to evaluate the measured data. First results of test measurements are presented.
Optimization of a Multistage Axial Compressor Stochastic Approach
Authors: Egorov I. N. 
Published: March 2015

A procedure of a multistage axial compressor (MAC) parameters optimization in stochastic setting has been offered. The procedure allows to obtain a stable solution from the point of view of its practical realization. A concept of robustness (stability) of turbomachine optimum design has been introduced, and the criteria of stability degree evaluation of complex technical objects optimum solution have been also suggested.
With reference to determining optimum laws to control the rows of MAC, modeled in 2-D axisymmetric setting, there are presented the results of the comparative analysis of the solutions obtained both with using the traditional (deterministic) approach and the proposed stochastic setting, which allows to increase the possibility to realize the technical solution by more than two times. Analysis of the results shows that the value of optimization criterion obtained in stochastic setting doesn’t practically worsen the value of optimization criterion obtained in deterministic approach.
The Dynamic Characteristics of a High Pressure Turbine Stage in a Transient Wind Tunnel
Authors: Sheard A. G. , Dietz A. J. , Ainsworth R. W. 
Published: March 2015

A new transient facility for the study of time averaged and unsteady aerodynamics and heat transfer in a high pressure turbine was recently commissioned. During the facility design a high priority was placed on ease of access to the turbine blading to facilitate the development of blade mounted instrumentation. The turbine disc was cantilevered on a shaft by a thin annular link, with the shaft passing back through the disc to a single row and matched pair of relatively closely spaced bearings. The bearings were originally designed for use in a marine gas turbine. Due to the facility’s novel mode of operation the bearings were working well beyond some of their original design limits, primarily due to the high turbine acceleration and the high speed/low load condition at the end of facility operation.
During the facility design a programme of work was undertaken to predict its dynamic performance. This was continued during commissioning to measure actual facility performance. In this paper the predicted dynamic performance of the disc/shaft assembly and its bearing system are presented. The programme of work undertaken during the facility commissioning phase to ascertain actual dynamic performance is described, and the results discussed. Finally, the technique developed to field balance the rotating assembly following changes to blade instrumentation is described.
A Binary Gas Composition Sensor to Measure Impermeable Wall Concentration in Film Cooling Experiments
Authors: Seffal R. , Schwarz S. G. , Walker S. J. 
Published: March 2015

A binary gas composition sensor has been developed to measure impermeable wall effectiveness with the foreign gas injection technique. The sampled gas is drawn at a controlled flow rate over a platinum hot wire connected to an anemometer circuit. A change in composition of the gas flowing over the wire results in a change in the heat loss to the gas and, hence, the anemometer output voltage. The sensitivity of a prototype sensor with a 6.1 mm platinum hot wire length has been found to be 0.278 V/% helium at a mass concentration of 2% He.
The sensor has been tested in a film cooling experiment in which an air-helium mixture (helium mass concentration 2%) was injected through a slot along a flat surface. A series of sensors placed downstream of the injection slot measured the foreign gas wall concentrations. The effectiveness results deduced from the anemometer output voltages compare very well to those of classical film cooling experiments in the literature.
The use of the binary gas composition sensor in film cooling experiments has the advantage of simulating adiabatic walls without the disadvantages of the inability to reduce the effectiveness data during the film cooling test and the requirement of an expensive gas chromatograph.
Digital Control Retrofit of an Industrial Gas Turbine
Authors: Metzger Alan , Kness Tena 
Published: March 2015

As worldwide power requirements increase, power generation facilities must begin to think more closely about the reliability of existing units. In order to enhance plant capability, many power producers are considering control upgrades to aging equipment as an alternative to adding new machinery.
This paper details an advanced digital control system coupled with a progressive valving scheme and a unique man-machine interface that features the following:
(1) increased unit reliability due to the replacement of the pneumatic control system with a state-of-the-art, digital controller and an electro-hydraulic fuel valve,
(2) cooler, more predictable start-ups achieved by removing the relay sequencer and substituting an advanced software-driven sequencer,
(3) an intuitive, color graphics operator control station that offers trending, archiving, and rapid configuration.
The scope of this paper will describe this system as it applies to a Westinghouse 191G gas turbine. This unit is located at a peaking facility in Astoria, New York. The control retrofit was successfully completed in June 1991.
Balance of Moments for Hypersonic Vehicles
Authors: Kremer Frans G. J. 
Published: March 2015

Ramjet engines propelling hypersonic flight vehicles will be highly integrated into the vehicle, resulting in strong interactions between the vehicle and the engine. An assessment of these interactions in relation to the flight mission is made by simple but adequate modeling of the flight vehicle aerodynamics and the engine performance. Especially moments associated with the propulsion system are of interest.
This paper deals with the pitch moments introduced by the ramjet related forces, which are evaluated by one-dimensional engine performance and by modeling of the inlet and nozzle flow. Furthermore, it discusses the balance of moments for the first stage of a two stage transportation system for an ascent trajectory.
Powder Metallurgy Repair of Turbine Components
Authors: Ellison K. A. , Lowden P. , Liburdi J. 
Published: March 2015

An advanced powder metallurgy repair process called Liburdi Powder Metallurgy (LPM)1 has been developed for the repair, overlay or joining nickel and cobalt-based high temperature alloys. This process involves mechanical cleaning, followed by the application and consolidation of a filler metal powder which has substantially the same composition as the base metal, and produces joints with mechanical properties similar to those of the parent material.
While previous activated braze or “wide-gap” repair processes have been limited to clearances of approximately 1 mm, the LPM technique has the ability to bridge larger gaps of over 5 mm. In addition, the LPM joints contain significantly lower concentrations of melting point depressants such as silicon and boron than conventional wide-gap repair techniques and exhibit superior microstructural features.
The characteristics and typical applications of the LPM process for blade and vane repairs are highlighted and the results of laboratory and engine tests are discussed.
Assessing the Economics of Industrial Gas Turbine Cogeneration Applications
Authors: Hill Jane P. 
Published: March 2015

Gas turbines are often used at industrial plants to generate electricity. However, turbines convert a greater portion of the input fuel into waste heat than into electricity. The degree to which this waste heat can be captured and used to produce steam, hot water, or simply hot air for drying, greatly improves the overall efficiency of the turbine system. This process is called cogeneration. There is no question that cogeneration can improve overall efficiencies. The question is whether cogeneration can be accomplished in an economic manner.
This paper presents a straight-forward methodology for comparing the costs and benefits associated with cogeneration. All costs and savings are converted to a consistent before tax cent per kilowatt-hour basis. The inconsistencies encountered with simple payback analysis are avoided, as well as the complexities of discounted cash flow analysis. The effects of income taxes, depreciation, financing, and cogeneration load factor are incorporated.
Turbine Cascade Optimization Against Particle Deposition
Authors: Kladas D. D. , Georgiou D. P. 
Published: March 2015

Modern turbine cascades are usually being optimized for minimum total pressure losses. Gas turbines, however, operating in dirty environments or using coal–derived fuels need cascades that minimize the deposition, erosion and corrosion (DEC) implications of the particle–laden gas. This can be achieved by altering certain geometrical key–parameters of cascades and blades which influence the particle deposition rate, while keeping the inlet and outlet velocities and angles fixed. Since reference cascades have already been optimized for minimum aerodynamic losses, the associated loss increase penalty is accounted for.
Two stator and two rotor cascades were optimized by a penalty function method. The results suggest that solid particle deposition rates can be minimized by as much as 40 per cent while keeping profile losses to acceptable limits in both stator and rotor cascades for the particle size range 0.1 to 1 μm.
Experimental Study of Mixed Compression Air-Intake for Hypersonic Airbreathing Engines
Authors: Sakata Kimio , Yanagi Ryoji , Murakami Akira , Shindo Shigemi , Honami Shinji , Tanaka Atsushige , Shiraishi Ksazuo 
Published: March 2015

Supersonic air-intake for Mach number higher than 2.5 is being investigated with experimental, analytical and computational methods. The study is performed in a part of the joint research program led by National Aerospace Laboratory (NAL) on the hypersonic airbreathing turbo-engines with subsonic ram combustion. The wind tunnel models are designed in two-dimensional mixed compression type with multi-shock system and tested in NAL’s Mach 4 supersonic wind tunnel. Pressure measurements and flow visualization by schlieren method, oil-flow and vapor screen techniques are being done.
Here, the test results of Mach 4 and Mach 5 models are discussed. The Mach 4 model is fixed geometry with 5-shock system and the Mach 5 one is variable geometry with 6-shock and an isentropic compression surface. An expansion fore-plate was installed at the Mach 5 model inlet to accelerate the air-speed at the entry. The bleed systems at throat, ramp and cowl are adopted and evaluated in terms of pressure recovery and stability. Importance of establishment of the internal shock wave system, reduction of upstream Mach number of terminal shock wave and suppression of flow separation at diffusers are found. It is also found that ramp bleed is effective to confirm intake start and to minimize shock/boundary layer interaction.
Technical and Economical Aspects of Using Gas Turbine Technology in Eastern Europe Including the Commonwealth of Independent States (CIS)
Authors: Boehm B. , Marks R.-R. 
Published: March 2015

An overview of the installed electrical generating capacity in the entire Eastern European region is given along with the plants intended for expansion to meet the forecasted system load demands.
The emphasis with future power plants in the region will be attached to attaining considerably higher generating efficiency and operating availability than are presently being achieved, as well as to directly reducing pollutant emissions to protect the environment more effectively.
Modern Western technology will be adopted on a certain scale to meet the objectives of better economy and ecological conservation. In many cases this will be accomplished by cooperating with Western companies to ensure long-term technology transfer. In particular, many of the new power plants required will be built in the form of combined-cycle installations. Gas turbines may in some cases be retrofitted to existing reheat steam boiler/turbine units (topping or repowering) to improve overall station efficiency.
Particular power plant projects in Eastern Europe including the Commonwealth of Independent States are presented as examples of typical solutions to achieving the goals that are so important to the region.
Impact of Ceramic Components in Gas Turbines for Industrial Cogeneration
Authors: Anson D. , Sheppard W. J. , Parks W. P. 
Published: March 2015

A development thrust for the adoption of ceramic components in industrial gas turbines, now being sponsored by the U.S. Department of Energy, may have a considerable impact on the growth rate and ultimate capacity of the cogeneration sector.
The economic justification for cogeneration rests on the ability to undercut the cost of purchased power after taking credit for the useful heat recovery, and it is frequently marginal after consideration of fuel, maintenance, and pollution control devices. After reviewing briefly the factors contributing to the economic viability of cogeneration systems, this paper presents arguments to show how the use of ceramics in industrial gas turbine can be instrumental in reducing installation and operating costs. Improved gas turbines based on ceramic materials technology also will provides means for meeting environmental protection requirements without the use of back end flue gas treatment, and will be able to utilize byproduct industrial gaseous and liquid fuels more effectively. These improvements can increase substantially the economic return from cogeneration systems, and are expected to result in increased cogeneration capacity and a sustained market for industrial gas turbines.
Predictions are made of the size of the U.S. industrial gas turbine cogeneration market. The annual fuel savings resulting from displacement of utility generation capacity could amount to 2 × 1017 joules (2 × 1014 Btu’s) by the year 2010.
A Study of Transient Response of Flexible Rotors in High Speed Turbomachinery
Authors: Pavelic V. , Amano R. S. 
Published: March 2015

In many applications the design operating range of the turbomachinery may be well above the rotor first critical speed which leads to the problem of insuring that the turbomachinery performs with a stable, low-level amplitude of vibration.
Under certain conditions of high speed and loading the rotor system can start orbiting in its bearing at a rate which is less than the rotor angular speed, and this phenomena is commonly known as whirling or whipping action. This whipping action may produce additional undesirable dynamic loads on the overall flexible assembly and eventually destroy the rotor. Some of this action is also transient in nature.
Whirling is a self-exited vibration caused mainly by the fluid bearings and by the internal friction damping of the rotor. To understand this occurrence, a general dynamic mathematical model was derived considering also the complete viscous characteristic of hydrodynamic journal bearings.
The general equations of motions of the system are obtained from Lagrange’s equation of motion. The system kinetic, potential, and dissipation functions are determined based on the generalized coordinates of the system.
The journal displacements are related to the overall dynamics of the rotor using deformable bearings. The loads acting at the journals of the shaft are integrated from the fluid film pressure distribution in the journal bearings using mobility method.
A unique mathematical model is formulated and solved. This model includes the elastic and inertial properties of the flexible rotor, the elastic, damping and inertial properties of supports and the hydrodynamic characteristics of the journal bearings.
The equations of motions result in a system of nonlinear second order differential equations which are solved by using finite difference method. The solution of the equations of motions is used to plot maps of motion of journal centers.
A computer program was implemented to aid in the solution of the system of equations and to verify analytical model. The computer program used test data available in literature and the results were compared to be very good.
The analytical model and results obtained in this study can be of great help to designers of high speed turbomachinery.
Efficacy of Skin and Nasal Povidone-Iodine Preparation against Mupirocin-Resistant Methicillin-Resistant Staphylococcus aureus and S. aureus within the Anterior Nares
Authors: Anderson Michele J. , David Maren L. , Scholz Matt , Bull Sally J. , Morse Dan , Hulse-Stevens Michelle , Peterson Marnie L. 
Published: March 2015

ABSTRACT

Mupirocin decolonization of nasal
Staphylococcus aureus
prior to surgery decreases surgical-site infections; however, treatment requires 5 days, compliance is low, and resistance occurs. In 2010, 3M Company introduced povidone-iodine (PVP-I)-based skin and nasal antiseptic (Skin and Nasal Prep [SNP]). SNP has rapid, broad-spectrum antimicrobial activity. We tested SNP's efficacy using full-thickness tissue (porcine mucosal [PM] and human skin) explant models and human subjects. Prior to or following infection with methicillin-resistant
Staphylococcus aureus
(MRSA) (mupirocin sensitive and resistant), explants were treated with Betadine ophthalmic preparation (Bet), SNP, or mupirocin (Bactroban nasal ointment [BN]) or left untreated. One hour posttreatment, explants were washed with phosphate-buffered saline (PBS) plus 2% mucin. One, 6, or 12 h later, bacteria were recovered and enumerated. Alternatively, following baseline sampling, human subjects applied two consecutive applications of SNP or saline to their anterior nares. One, 6, and 12 h after application of the preparation (postprep), nasal swabs were obtained, and
S. aureus
was enumerated. We observed that treatment of infected PM or human skin explants with SNP resulted in >2.0 log
10
CFU reduction in MRSA, regardless of mupirocin sensitivity, which was significantly different from the values for BN- and Bet-treated explants and untreated controls 1 h, 6 h, and 12 h after being washed with PBS plus mucin. Swabbing the anterior nares of human subjects with SNP significantly reduced resident
S. aureus
compared to saline 1, 6, and 12 h postprep. Finally, pretreatment of PM explants with SNP, followed by a mucin rinse prior to infection, completely prevented MRSA infection. We conclude that SNP may be an attractive alternative for reducing the bioburden of anterior nares prior to surgery.
The Assembly of GM1 Glycolipid- and Cholesterol-Enriched Raft-Like Membrane Microdomains Is Important for Giardial Encystation
Authors: De Chatterjee Atasi , Mendez Tavis L. , Roychowdhury Sukla , Das Siddhartha 
Published: March 2015

ABSTRACT

Although encystation (or cyst formation) is an important step of the life cycle of
Giardia
, the cellular events that trigger encystation are poorly understood. Because membrane microdomains are involved in inducing growth and differentiation in many eukaryotes, we wondered if these raft-like domains are assembled by this parasite and participate in the encystation process. Since the GM1 ganglioside is a major constituent of mammalian lipid rafts (LRs) and known to react with cholera toxin B (CTXB), we used Alexa Fluor-conjugated CTXB and GM1 antibodies to detect giardial LRs. Raft-like structures in trophozoites are located in the plasma membranes and on the periphery of ventral discs. In cysts, however, they are localized in the membranes beneath the cyst wall. Nystatin and filipin III, two cholesterol-binding agents, and oseltamivir (Tamiflu), a viral neuraminidase inhibitor, disassembled the microdomains, as evidenced by reduced staining of trophozoites with CTXB and GM1 antibodies. GM1- and cholesterol-enriched LRs were isolated from
Giardia
by density gradient centrifugation and found to be sensitive to nystatin and oseltamivir. The involvement of LRs in encystation could be supported by the observation that raft inhibitors interrupted the biogenesis of encystation-specific vesicles and cyst production. Furthermore, culturing of trophozoites in dialyzed medium containing fetal bovine serum (which is low in cholesterol) reduced raft assembly and encystation, which could be rescued by adding cholesterol from the outside. Our results suggest that
Giardia
is able to form GM1- and cholesterol-enriched lipid rafts and these raft domains are important for encystation.