Optimization of residual heat removal pump axial thrust and axial bearing

International Nuclear Information System (INIS)

Schubert, F.

1996-01-01

The residual heat removal (RHR) pumps of German 1300 megawatt pressurized-water reactor (PWR) power plants are of the single stage end suction type with volute casing or with diffuser and forged circular casing. Due to the service conditions the pumps have to cover the full capacity range as well as a big variation in suction static pressure. This results in a big difference in the axial thrust that has to be borne by the axial bearing. Because these pumps are designed to operate without auxiliary systems (things that do not exist can not fail), they are equipped with antifriction bearings and sump oil lubrication. To minimize the heat production within the bearing casing, a number of PWR plants have pumps with combined axial/radial bearings of the ball type. Due to the fact that the maximum axial thrust caused by static pressure and hydrodynamic forces on the impeller is too big to be borne by that type of axial bearing, the impellers were designed to produce a hydrodynamic axial force that counteracts the static axial force. Thus, the resulting axial thrust may change direction when the static pressure varies

Optimization of residual heat removal pump axial thrust and axial bearing

Energy Technology Data Exchange (ETDEWEB)

Schubert, F.

1996-12-01

The residual heat removal (RHR) pumps of German 1300 megawatt pressurized-water reactor (PWR) power plants are of the single stage end suction type with volute casing or with diffuser and forged circular casing. Due to the service conditions the pumps have to cover the full capacity range as well as a big variation in suction static pressure. This results in a big difference in the axial thrust that has to be borne by the axial bearing. Because these pumps are designed to operate without auxiliary systems (things that do not exist can not fail), they are equipped with antifriction bearings and sump oil lubrication. To minimize the heat production within the bearing casing, a number of PWR plants have pumps with combined axial/radial bearings of the ball type. Due to the fact that the maximum axial thrust caused by static pressure and hydrodynamic forces on the impeller is too big to be borne by that type of axial bearing, the impellers were designed to produce a hydrodynamic axial force that counteracts the static axial force. Thus, the resulting axial thrust may change direction when the static pressure varies.

Bulk-Flow Analysis of Hybrid Thrust Bearings for Advanced Cryogenic Turbopumps

Science.gov (United States)

SanAndres, Luis

1998-01-01

A bulk-flow analysis and computer program for prediction of the static load performance and dynamic force coefficients of angled injection, orifice-compensated hydrostatic/hydrodynamic thrust bearings have been completed. The product of the research is an efficient computational tool for the design of high-speed thrust bearings for cryogenic fluid turbopumps. The study addresses the needs of a growing technology that requires of reliable fluid film bearings to provide the maximum operating life with optimum controllable rotordynamic characteristics at the lowest cost. The motion of a cryogenic fluid on the thin film lands of a thrust bearing is governed by a set of bulk-flow mass and momentum conservation and energy transport equations. Mass flow conservation and a simple model for momentum transport within the hydrostatic bearing recesses are also accounted for. The bulk-flow model includes flow turbulence with fluid inertia advection, Coriolis and centrifugal acceleration effects on the bearing recesses and film lands. The cryogenic fluid properties are obtained from realistic thermophysical equations of state. Turbulent bulk-flow shear parameters are based on Hirs' model with Moody's friction factor equations allowing a simple simulation for machined bearing surface roughness. A perturbation analysis leads to zeroth-order nonlinear equations governing the fluid flow for the thrust bearing operating at a static equilibrium position, and first-order linear equations describing the perturbed fluid flow for small amplitude shaft motions in the axial direction. Numerical solution to the zeroth-order flow field equations renders the bearing flow rate, thrust load, drag torque and power dissipation. Solution to the first-order equations determines the axial stiffness, damping and inertia force coefficients. The computational method uses well established algorithms and generic subprograms available from prior developments. The Fortran9O computer program hydrothrust runs

Thermal–Hydrodynamic Behaviour of Coated Pivoted Pad Thrust Bearings: Comparison between Babbitt, PTFE and DLC

OpenAIRE

Konstantinos Katsaros; Dimitrios A. Bompos; Pantelis G. Nikolakopoulos; Stephanos Theodossiades

2018-01-01

The hydrodynamic lubrication and thermal analysis of tilting pad thrust bearings has been a major subject for many studies in the field of tribology. There is only a limited number of studies regarding thrust bearings with coated surfaces. The purpose of this study is to build a parametric, iterative algorithm in order to perform a complete thermal and hydrodynamic lubrication analysis for pivoted pad thrust bearings with coatings. The analytical model is mainly based on the energy, continuit...

On the Design of Tilting-Pad Thrust Bearings

DEFF Research Database (Denmark)

Heinrichson, Niels

2007-01-01

Pockets are often machined in the surfaces of tilting-pad thrust bearings to allow for hydrostatic jacking in the start-up phase. Pockets and other recesses in the surfaces of bearing pads influence the pressure distribution and thereby the position of the pivot resulting in the most advantageous...... based on the Reynolds equation are used. They include the effects of variations of viscosity with temperature and the deformation of the bearing pads due to pressure and thermal gradients. The models are validated using measurements. Tilting-pad bearings of standard design are studied and the influences...... of the friction loss. Both this bearing and the bearing design with enclosed recesses in the high-pressure regions of the pads suffer from a higher sensitivity to the position of the pivot. The design of such bearing is therefore no trivial task....

Field Tests on Hydrodynamic and Hybrid Operation of a Bidirectional Thrust Bearing of a Pump-Turbine

Directory of Open Access Journals (Sweden)

Michał Wasilczuk

2017-12-01

Full Text Available In vertical shaft pump turbines operating in pumped storage power plants an important role is played by a thrust bearing. Due to the bidirectional character of operation, thrust bearing tilting pads have to be supported symmetrically, which is known to be unfavourable from the point of view of their performance. Large thrust bearings have to be carefully designed so as to minimise excessive thermo-elastic pad deformations. The research into fluid film thrust bearings has been quite extensive over the years, comprising theoretical studies of bearing properties with the use of more and more sophisticated calculation codes. On the other hand, the availability of experimental field data on bearing operation is limited, for obvious reasons. In this paper the authors present part of the results of extensive field tests of a large bearing of a pump-turbine they have conducted in a pumped storage power plant. Hopefully this data will be of interest to other researchers to compare theoretical predictions to measurement data.

On the Design of Tilting-Pad Thrust Bearings

OpenAIRE

Heinrichson, Niels; Santos, Ilmar

2007-01-01

Pockets are often machined in the surfaces of tilting-pad thrust bearings to allow for hydrostatic jacking in the start-up phase. Pockets and other recesses in the surfaces of bearing pads influence the pressure distribution and thereby the position of the pivot resulting in the most advantageous pad convergence ratio. In this thesis, a theoretical approach is applied in the attempt to quantify the influence of recesses in the pad surfaces. The recesses may be relatively deep and enclosed as ...

Thermal–Hydrodynamic Behaviour of Coated Pivoted Pad Thrust Bearings: Comparison between Babbitt, PTFE and DLC

Directory of Open Access Journals (Sweden)

Konstantinos Katsaros

2018-05-01

Full Text Available The hydrodynamic lubrication and thermal analysis of tilting pad thrust bearings has been a major subject for many studies in the field of tribology. There is only a limited number of studies regarding thrust bearings with coated surfaces. The purpose of this study is to build a parametric, iterative algorithm in order to perform a complete thermal and hydrodynamic lubrication analysis for pivoted pad thrust bearings with coatings. The analytical model is mainly based on the energy, continuity and Navier–Stokes equations, which are solved numerically with the Semi-Implicit Method for Pressure Linked Equations Consistent (SIMPLEC method. The analysis focuses on a single pivoted pad of the thrust bearing. The thermal properties of the coating material are taken into account and the resulting thermal and flow fields are solved. The basic hydrodynamic and tribological characteristics are calculated for an uncoated, a Babbitt coated, a PTFE coated and a diamond like carbon (DLC coated pivoted pad thrust bearing. The pressure and the film thickness distribution, as well as the load capacity and the frictional forces, are determined for several pad positions and velocities of the rotor. A mineral oil lubricant is used to estimate the shear thinning or thickening effects on the pad tribological performance. The results indicate that pads coated with PTFE and DLC show lower friction forces compared to the common steel and Babbitt applications. At the same time, the DLC coating seems to affect the bearing’s flow and thermal fields less than the PTFE, making it more suitable for thrust bearings applications.

Measurements versus Predictions for a Hybrid (Hydrostatic Plus Hydrodynamic) Thrust Bearing for a Range of Orifice Diameters

Science.gov (United States)

2010-05-01

Type of Lubrication for a Tilting Pad Thrust Bearing ,” ASME Journal of Lubrication Technology, 96 Ser F (1), pp. 22-27. [9] Gregory, R.S., 1974...1986, “Measurements of Maximum Temperature in Tilting - Pad Thrust Bearings ,” Technical Preprints - Presented at the ASLE 41st Annual Meeting. (ASLE...Safar [7] provides a modified Reynolds number analysis on hydrostatic thrust bearing performance parameters including the effects of tilt . Finally, San

Analysis of oil lubricated, fluid film, thrust bearings with allowance for temperature dependent viscosity

Science.gov (United States)

Pan, C. H. T.; Malanoski, S. B.

1972-01-01

A preliminary design study was performed to seek a fluid-film thrust bearing design intended to be part of a high-speed, hybrid (rolling element/fluid film) bearing configuration. The base line used is a design previously tested. To improve the accuracy of theoretical predictions of load capacity, flow rate, and friction power loss, an analytical procedure was developed to include curvature effects inherent in thrust bearings and to allow for the temperature rise in the fluid due to viscous heating. Also, a narrow-groove approximation in the treatment of the temperature field was formulated to apply the procedure to the Whipple thrust bearing. A comparative trade-off study was carried out assuming isothermal films; its results showed the shrouded-step design to be superior to the Whipple design for the intended application. An extensive parametric study was performed, employing isoviscous calculations, to determine the optimized design, which was subsequently recalculated allowing for temperature effects.

Analysis of a Thrust Bearing with Flexible Pads and Flexible Supports

DEFF Research Database (Denmark)

Klit, Peder; Thomsen, Kim

2007-01-01

A theoretical analysis of a hydrodynamic thrust bearing is presented. The bearing investigated is used in an ndustrial product. The lubricant is water, but the results are valid also for other lubricants.At first the results from a 1-dimensional model for the fluid film forces and the associated...... deformation of the bearing geometry is presented. This model enlightens the influence of pad flexibility and support location and flexibility. Subsequently results from a 2-dimensional model of the bearing is presented. The model is used to carry out an optimization of the bearing design, and the obtained...

Establishing design criteria for crankshaft thrust bearings in gasoline and diesel engines by computer simulations and experiments. Crankshaft thrust bearing design - final report; Auslegungskriterien fuer Kurbelwellenaxiallager in Otto- und Dieselmotoren durch rechnergestuetzte Simulation und experimentelle Untersuchungen. Axialgleitlagerauslegung - Abschlussbericht

Energy Technology Data Exchange (ETDEWEB)

Hunsicker, W. [Fachhochschule Mannheim (Germany). Inst. fuer Tribologie; Backhaus, K. [Univ. GH Kassel (Germany). Inst. fuer Maschinenelemente und Konstruktionstechnik; Schubert, W. [KS Gleitlager GmbH, Papenburg (Germany)

2004-07-01

Aim of the research-project was it to increase the calculation safety of crank shaft thrust bearings in combustion engines. The project was divided in two parts: (1) A simulation program to analyze the load bearing capacity of axial bearings under mixed lubrication has been developed at the Institut fuer Maschinenelemente und Konstruktionstechnik, University of Kassel. This part of the research-project has been presented at the FVV Herbsttagung in 2003. (2) The test runs with original parts were carried out on a newly designed thrust bearing test rig at the Institut fuer Tribologie, University of Applied Sciences in Mannheim. The following presentation shows the results of part 2. The experimental results show the influence of rotational frequency, load, bearing material, lateral run-out of the tread of the crankshaft and groove pattern. These test runs will help to dimension thrust bearings more efficiently. (orig.)

Numerical research on rotating speed influence and flow state distribution of water-lubricated thrust bearing

International Nuclear Information System (INIS)

Deng Xiao; Deng Liping; Huang Wei

2015-01-01

Water-lubricated thrust bearing is one of the key parts in canned motor pump, for example, the RCP in AP1000, and it functions to balance axial loads. A calculation model which can handle all flow state lubrication performance for water-lubricated thrust bearing has been presented. The model first includes laminar and turbulent Reynolds' equation. Then to get continuous viscosity coefficients cross critical Reynolds number, a transition zone which ranges based on engineering experience is put up, through which Hermite interpolation is employed. The model is numerically solved in finite difference method with uniform grids. To accelerate the calculation process, multigrid method and line relaxation is adopted within the iteration procedure. A medium sized water-lubricated tilting pad thrust bearing is exampled to verify the calculation model. Results suggest that as rotating speed enlarges, lubrication state distribution of the thrust bearing gradually tends to turbulent lubrication from the intersection corner of pad outer diameter and pad inlet to the opposite, minimum water film thickness increases approximately linearly, maximum water film pressure has little change, meanwhile the friction power grows nearly in exponential law which could result in bad effect by yielding much more heat. (author)

Numerical analysis of all flow state lubrication performance of water-lubricated thrust bearing

International Nuclear Information System (INIS)

Deng Xiao; Deng Liping; Huang Wei; Liu Lizhi; Zhao Xuecen; Liu Songya

2015-01-01

A model enabling all different flow state lubrication performance simulation and analysis for water-lubricated thrust bearing is presented, considering the temperature influence and elastic deformation. Lubrication state in the model is changed directly from laminar lubrication to turbulent lubrication once Reynolds number exceeds the critical Reynolds number. The model is numerically solved and results show that temperature variation is too little to influence the lubrication performance; the elastic deformation can slightly reduce the load carrying capacity of the thrust bearing; and the turbulent lubrication can remarkably improve the load carrying capacity. (authors)

Design charts for arbitrarily pivoted, liquid-lubricated flat-sector-pad thrust bearing

Science.gov (United States)

Etsion, I.

1977-01-01

A flat, sector-shaped geometry for a liquid-lubricated thrust bearing is analyzed considering both the pitch and roll of the pad. Results are presented in design charts that enable a direct approach to the design of point- and line-pivoted, tilting pad bearings. A comparison is made with the Mitchell bearing approximation and it is found that this approximation always overestimates load capacity.

Improvement of Thrust Bearing Calculation Considering the Convectional Heating within the Space between the Pads

OpenAIRE

Monika Chmielowiec-Jablczyk; Andreas Schubert; Christian Kraft; Hubert Schwarze; Michal Wodtke; Michal Wasilczuk

2018-01-01

A modern thrust bearing tool is used to estimate the behavior of tilting pad thrust bearings not only in the oil film between pad and rotating collar, but also in the space between the pads. The oil flow in the space significantly influences the oil film inlet temperature and the heating of pad and collar. For that reason, it is necessary to define an oil mixing model for the space between the pads. In the bearing tool, the solutions of the Reynolds equation including a cavitation model, the ...

Dynamic Characteristics of Rotors on Passive and Active Thrust Fluid-film Bearings with Fixed Pads

Directory of Open Access Journals (Sweden)

Babin Alexander

2018-01-01

Full Text Available Application of fluid-film bearings in rotor machines in many cases could have no alternative due to obvious advantages when compared to roller element bearings. Integration of information technology in mechanical engineering resulting in emergence of a new field of research – mechatronic bearings which allowed tracking condition of the most important parts of a machine and adjusting operational parameters of the system. Application of servo valves to control the flow rate through a fluid-film bearing is the most universal and simple way of rotor’s position control due to relative simplicity of modelling and absence of need to radically change the design of conventional hydrodynamic bearings. In the present paper numerical simulations of passive (conventional as opposed to mechatronic and active hybrid thrust fluid-film bearings with a central feeding chamber are presented, that are parts of a mechatronic rotor-bearing node. Numerical model of an active thrust bearing is based on solution of equations of hydrodynamics, rotor dynamics and an additional model of a servo valve. Various types of control have been investigated: P, PI and PID control, and the dynamic behaviour of a system has been estimated under various loads, namely static, periodic and impulse. A design of a test rig has been proposed to study passive and active thrust fluid-film bearings aimed at, among other, validation of numerical results of active bearings simulation.

GAS BEARING

Science.gov (United States)

Skarstrom, C.W.

1960-09-01

A gas lubricated bearing for a rotating shaft is described. The assembly comprises a stationary collar having an annular member resiliently supported thereon. The collar and annular member are provided with cooperating gas passages arranged for admission of pressurized gas which supports and lubricates a bearing block fixed to the rotatable shaft. The resilient means for the annular member support the latter against movement away from the bearing block when the assembly is in operation.

Improvement of Thrust Bearing Calculation Considering the Convectional Heating within the Space between the Pads

Directory of Open Access Journals (Sweden)

Monika Chmielowiec-Jablczyk

2018-02-01

Full Text Available A modern thrust bearing tool is used to estimate the behavior of tilting pad thrust bearings not only in the oil film between pad and rotating collar, but also in the space between the pads. The oil flow in the space significantly influences the oil film inlet temperature and the heating of pad and collar. For that reason, it is necessary to define an oil mixing model for the space between the pads. In the bearing tool, the solutions of the Reynolds equation including a cavitation model, the energy equation and the heat transfer equation are done iteratively with the finite volume method by considering a constant flow rate. Both effects—laminar/turbulent flow and centrifugal force—are considered. The calculation results are compared with measurements done for a flooded thrust bearing with nominal eight tilting pads with an outer diameter of 180 mm. The heat convection coefficients for the pad surfaces mainly influence the pad temperature field and are adjusted to the measurement results. In the following paper, the calculation results for variable space distances, influence of different parameters on the bearing behavior and operating condition at high load are presented.

The Influence of Injection Pockets on the Performance of Tilting-Pad Thrust Bearings: Part I – Theory

DEFF Research Database (Denmark)

Heinrichson, Niels; Santos, Ilmar

2006-01-01

This is Part I of a two-part series of papers describing the effects of high pressure injection pockets on the operating conditions of tilting-pad thrust bearings. A numerical model based on the Reynolds equation is developed extending the three dimensional thermo-elasto-hydrodynamic (TEHD......) analysis of tilting-pad thrust bearings to include the effects of high pressure injection and recesses in the bearing pad. The model is applied to the analysis of an existing bearing of large dimensions and the influence of the pocket is analyzed. It is shown that a shallow pocket positively influences...... the performance of the bearing as it has characteristics similar to those of a parallel step bearing....

Design and fabrication of gas bearings for Brayton cycle rotating unit

Science.gov (United States)

Frost, A.; Tessarzik, J. M.; Arwas, E. B.; Waldron, W. D. (Editor)

1973-01-01

Analysis, design, and testing of two types of pivoted pad journal bearings and a spiral-grooved thrust bearing suitable for direct installation into the NASA 2 to 15 KW Brayton Cycle Rotating Unit (BRU) have been accomplished. Both types of tilting pad bearing assemblies are of the preloaded type, consisting of three pads with one pad flexibly mounted. One type utilizes a non-conforming pivot, while the other replaces the conventional spherical pivot with a cruciform flexible member. The thrust bearing is flexure mounted to accommodate static machine mislinement. Test results indicate that both types of journal bearings should satisfy the requirements imposed by the BRU. Hydrostatic tests of the spiral-grooved thrust bearing showed it to be free of pneumatic hammer with as many as 24 orifices over the BRU pressure and load range.

Condition monitoring of thrust ball bearings using continuous AE

Czech Academy of Sciences Publication Activity Database

Chlada, Milan; Nohal, L.; Převorovský, Zdeněk

2016-01-01

Roč. 26, č. 2 (2016), A14-A14 ISSN 1213-3825. [Europen Conference on Acoustic Emission Testing /32./. 07.09.2016-09.09.2016, Praha] Grant - others:NETME Centre Plus - národní program udržitelnosti(CZ) LO1202 Institutional support: RVO:61388998 Keywords : continuous acoustic emission * rolling contact fatigue * thrust ball bearing * histogram of counting periods * wavelet analysis Subject RIV: BI - Acoustic s

The Influence of Injection Pockets on the Performance of Tilting-Pad Thrust Bearings - Part I: Theory

DEFF Research Database (Denmark)

Heinrichson, Niels; Santos, Ilmar; Fuerst, Axel

2007-01-01

This is Part I of a two-part series of papers describing the effects of high-pressure injection pockets on the operating conditions of tilting-pad thrust bearings. In Part I a numerical model based on the Reynolds equation is developed extending the threedimensional thermoelastohydrodynamic (TEHD......) analysis of tilting-pad thrust bearings to include the effects of high-pressure injection and recesses in the bearing pads. The model is applied to the analysis of an existing bearing of large dimensions and the influence of the pocket is analyzed. In the analysis, the high-pressure oil injection used...... for hydrostatic jacking is turned off (i.e., only the effect of the pocket is studied). It is shown that a shallow pocket positively influences the performance of the bearing because it has characteristics similar to those of a Rayleigh-step bearing. In Part II of the paper (Heinrichson, N., Fuerst, A...

An approach to evaluate capacitance, capacitive reactance and resistance of pivoted pads of a thrust bearing

Science.gov (United States)

Prashad, Har

1992-07-01

A theoretical approach is developed for determining the capacitance and active resistance between the interacting surfaces of pivoted pads and thrust collar, under different conditions of operation. It is shown that resistance and capacitive reactance of a thrust bearing decrease with the number of pads times the values of these parameters for an individual pad, and that capacitance increases with the number of pads times the capacitance of an individual pad. The analysis presented has a potential to diagnose the behavior of pivoted pad thrust bearings with the angle of tilt and the ratio of film thickness at the leading to trailing edge, by determining the variation of capacitance, resistance, and capacitive reactance.

Comparison Between Predictions and Measurements of Performance Characteristics for an Eight Pocket Hybrid (Combination Hydrostatic and Hydrodynamic) Thrust Bearing

Science.gov (United States)

2008-12-03

STB stainless steel housing. Drive End Thrust Collar Free End Splash Guard Slave Thrust Bearing Face STB Flange Figure 12: Exploded view of slave...Bulk Flow Analysis of Hybrid Thrust Bearing for Process Fluid Applications.” ASME Trans., Journal of Tribology , January, Vol. 122 (1), pp. 170-180...ASME Journal of Tribology , Vol. 123, pp. 768-776 [5] San Andrés, L., (2006), “MEEN 626 Notes 2 Derivation of the Classical Reynolds Equation for

Optimal design of Tilting-Pad Thrust Bearings with High Pressure Injection Pockets

DEFF Research Database (Denmark)

Heinrichson, Niels; Santos, Ilmar

2006-01-01

A thermo-elasto-hydrodynamic(TEHD) model based on the Reynolds equation has been used to study the effect of oil injection pockets on the performance of tilting pad thrust bearings. The optimal position of the pivot both with respect to load carrying capacity and minimal power consumption is seen...

Experimental Determination of Exhaust Gas Thrust, Special Report

Science.gov (United States)

Pinkel, Benjamin; Voss, Fred

1940-01-01

This investigation presents the results of tests made on a radial engine to determine the thrust that can be obtained from the exhaust gas when discharged from separate stacks and when discharged from the collector ring with various discharge nozzles. The engine was provided with a propeller to absorb the power and was mounted on a test stand equipped with scales for measuring the thrust and engine torque. The results indicate that at full open throttle at sea level, for the engine tested, a gain in thrust horsepower of 18 percent using separate stacks, and 9.5 percent using a collector ring and discharge nozzle, can be expected at an air speed of 550 miles per hour.

Maintenance free gas bearing helium blower for nuclear plant

Science.gov (United States)

Molyneaux, A., Dr; Harris, M., Prof; Sharkh, S., Prof; Hill, S.; de Graaff, T.

2017-08-01

This paper describes the design, testing and operation of novel helium blowers used to recirculate the helium blanketing gas in the nuclear reactor used as a neutron source at the Institut Laue Langevan, Grenoble, France. The laser sintered shrouded centrifugal wheel operates at speeds up to 45000 rpm supported on helium lubricated hydrodynamic spiral groove bearings, and is driven by a sensorless permanent magnet motor. The entire machine is designed to keep the helium gas (polluted by a small amount of D2O) out of contact with any iron or copper materials which would contribute to the corrosion of parts of the circuit. It is designed to have zero maintenance during a lifetime of 40,000 hours of continuous operation. This paper will describe the spiral groove journal and thrust bearings. Design and manufacture of the 1 kW motor and centrifugal wheel will be explained including their CFD and FEA analyses. Measurements of rotor displacement will be presented showing the behaviour under factory testing as well as details of the measured centrifugal wheel and motor performances. Two machines are incorporated into the circuit to provide redundancy and the first blower has been in continuous operation since Jan 2015. The blower was designed, manufactured, assembled and tested in the UK using predominantly UK suppliers.

Defect diagnosis and root cause analysis for thrust roller bearing of centrifugal charging pump

International Nuclear Information System (INIS)

Guo Yi

2012-01-01

The centrifugal charging pump is one of the most important equipment for Nuclear power plant which requires very high reliability, during C9 fuel-cycle, the continuous high level vibration alarm happened on the centrifugal charging pump B, we diagnosed its faults correctly and selected the right operation mode and right time to dismantle it which ensure the safety and economic benefits of Nuclear power plant, and through deeply analysis the root causes of thrust bearing defaults, we can learn much from it especially for the diagnosis and analysis to the bearing faults which is common for rotating equipment. (author)

Laminar motion of the incompressible fluids in self-acting thrust bearings with spiral grooves.

Science.gov (United States)

Velescu, Cornel; Popa, Nicolae Calin

2014-01-01

We analyze the laminar motion of incompressible fluids in self-acting thrust bearings with spiral grooves with inner or external pumping. The purpose of the study is to find some mathematical relations useful to approach the theoretical functionality of these bearings having magnetic controllable fluids as incompressible fluids, in the presence of a controllable magnetic field. This theoretical study approaches the permanent motion regime. To validate the theoretical results, we compare them to some experimental results presented in previous papers. The laminar motion of incompressible fluids in bearings is described by the fundamental equations of fluid dynamics. We developed and particularized these equations by taking into consideration the geometrical and functional characteristics of these hydrodynamic bearings. Through the integration of the differential equation, we determined the pressure and speed distributions in bearings with length in the "pumping" direction. These pressure and speed distributions offer important information, both quantitative (concerning the bearing performances) and qualitative (evidence of the viscous-inertial effects, the fluid compressibility, etc.), for the laminar and permanent motion regime.

Laminar Motion of the Incompressible Fluids in Self-Acting Thrust Bearings with Spiral Grooves

Directory of Open Access Journals (Sweden)

Cornel Velescu

2014-01-01

Full Text Available We analyze the laminar motion of incompressible fluids in self-acting thrust bearings with spiral grooves with inner or external pumping. The purpose of the study is to find some mathematical relations useful to approach the theoretical functionality of these bearings having magnetic controllable fluids as incompressible fluids, in the presence of a controllable magnetic field. This theoretical study approaches the permanent motion regime. To validate the theoretical results, we compare them to some experimental results presented in previous papers. The laminar motion of incompressible fluids in bearings is described by the fundamental equations of fluid dynamics. We developed and particularized these equations by taking into consideration the geometrical and functional characteristics of these hydrodynamic bearings. Through the integration of the differential equation, we determined the pressure and speed distributions in bearings with length in the “pumping” direction. These pressure and speed distributions offer important information, both quantitative (concerning the bearing performances and qualitative (evidence of the viscous-inertial effects, the fluid compressibility, etc., for the laminar and permanent motion regime.

High Specific Stiffness Shafts and Advanced Bearing Coatings for Gas Turbine Engines Final Report CRADA No. TC-1089-95

Energy Technology Data Exchange (ETDEWEB)

Barbee, Troy [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Chin, Herbert [United Technologies Corporation, East Hartford, CT (United States)

2017-11-09

At the time of the CRADA, the largest in-service gas-turbine aircraft engines strove for increased thrust and power density to meet the requirements for take-off thrust, given the increase in take-off gross weight (TOGW) associated with longer range transport requirements. The trend in modem turbo shaft engines was toward turbine shafts with higher and higher length-to-diameter ratios, which reduced the shaft critical speed. Using co nventional shaft materials, this lead to shafts that needed to operate near or above sensitive shaft bending critical speeds, therefore requiring multiple bearings and/ or multiple squeeze-film dampers to control the dynamic response. Using new materials and d esign concepts this project demonstrated the use of new shaft materials which could provide increased shaft speed range above existing maximum engine speeds without encountering a critic al speed event and high vector deflections. This increased main shaft speed also resulted in decreased bearing life associated with lower heat dissipation and higher centrifugal forces. Thus, a limited effort was devoted to feasibility of higher performance bearing coatings to mitigate the speed effects.

A Rotary Microactuator Supported on Encapsulated Microball Bearings using an Electro-Pneumatic Thrust Balance

Science.gov (United States)

2009-01-01

Additionally, high-speed air bearings have been demonstrated in micromotors (55 000 rpm) and micro-turbomachinery (2 million rpm) [7, 8]. While...without thrust balances [11]. For applications requiring continuous rotation ( micromotors and micropumps) this hydrostatic balancing force can be...conditions for stable actuation of the micromotor leading to maximum speeds. In addition to increased speed, this device demonstrates a substantial

A Foil Thrust Bearing Test Rig for Evaluation of High Temperature Performance and Durability

Science.gov (United States)

2008-04-01

composed of similar elements used in journal bearings, but are designed to support a shaft axially. Often, discrete compliant pads are attached... shaft designed to mate with a test thrust runner. The runner is mounted to the shaft with four high strength bolts, and an interference fit ensures...attached to the drive is able to stop the spindle quickly through dynamic braking of the shaft rotational energy. This spindle arrangement has

Technical Development Path for Gas Foil Bearings

Science.gov (United States)

Dellacorte, Christopher

2016-01-01

Foil gas bearings are in widespread commercial use in air cycle machines, turbocompressors and microturbine generators and are emerging in more challenging applications such as turbochargers, auxiliary power units and propulsion gas turbines. Though not well known, foil bearing technology is well over fifty years old. Recent technological developments indicate that their full potential has yet to be realized. This paper investigates the key technological developments that have characterized foil bearing advances. It is expected that a better understanding of foil gas bearing development path will aid in future development and progress towards more advanced applications.

Modelling of Rotor-gas bearings for Feedback Controller Design

DEFF Research Database (Denmark)

Theisen, Lukas Roy Svane; Niemann, Hans Henrik

2014-01-01

Controllable rotor-gas bearings are popular oering adaptability, high speed operation, low friction and clean operation. Rotor-gas bearings are however highly sensitive to disturbances due to the low friction of the injected gas. These undesirable damping properties call for controllers, which ca...... and are shown to accurately describe the dynamical behaviour of the rotor-gas bearing. Design of a controller using the identied models is treated and experiments verify the improvement of the damping properties of the rotor-gas bearing.......Controllable rotor-gas bearings are popular oering adaptability, high speed operation, low friction and clean operation. Rotor-gas bearings are however highly sensitive to disturbances due to the low friction of the injected gas. These undesirable damping properties call for controllers, which can...... be designed from suitable models describing the relation from actuator input to measured shaft position. Current state of the art models of controllable gas bearings however do not provide such relation, which calls for alternative strategies. The present contribution discusses the challenges for feedback...

A numerical model for design and optimization of surface textures for tilting pad thrust bearings

OpenAIRE

Gropper, Daniel; Harvey, Terence; Wang, Ling

2018-01-01

A numerical model based on the Reynolds equation to study textured tilting pad thrust bearings considering mass-conserving cavitation and thermal effects is presented. A non-uniform and adaptive finite volume method is utilized and two methods are compared and selected regarding their efficiency in handling discontinuities; specifically placing additional nodes closely around discontinuities and directly incorporating discontinuities in the discrete system. Multithreading is applied to improv...

Modeling of Hybrid Permanent Magnetic-Gas Bearings

DEFF Research Database (Denmark)

Morosi, Stefano; Santos, Ilmar

2009-01-01

Modern turbomachinery applications require nowadays ever-growing rotational speeds and high degree of reliability. It then becomes natural to focus the attention of the research to contact-free bearings elements. The present alternatives focus on gas lubricated journal bearings or magnetic bearings....... In the present paper, a detailed mathematical modeling of the gas bearing based on the compressible form of the Reynolds equation is presented. Perturbation theory is applied in order to identify the dynamic characteristic of the bearing. Due to the simple design of the magnetic bearings elements - being...... the rotor equilibrium position can be made independent on the rotational speed and applied load; it becomes function of the passive magnetic bearing offset. By adjusting the offset it is possible to significantly influence the dynamic coefficients of the hybrid bearing....

Lateral Vibration of Hydroelectric Generating Set with Different Supporting Condition of Thrust Pad

Directory of Open Access Journals (Sweden)

Xiaohui Si

2011-01-01

Full Text Available The variations of the supporting condition, which change the stiffness of tilting pad thrust bearing, may alter the dynamic behavior of the rotor system. The effects of supporting condition of thrust pad on the lateral vibration of a hydroelectric generating set are investigated in this paper. The action of a thrust bearing is described as moments acting on the thrust collar, and the tilting stiffness coefficients of thrust bearing are calculated. A model based on typical beam finite element method is established to calculate the dynamic response, and the effects of supporting conditions such as elastic oil tank support, different heights of the thrust pads with rigid support are discussed. The results reveal that the influence of thrust bearing is small when the elastic oil tanks work normally. When the supporting conditions turn to be rigid due to the oil leakage, the differences of thrust pad heights have evident influence on the load distribution of the thrust pads; while the effects on the tilting stiffness of the thrust bearing and the amplitude of the lateral shaft vibration is small when the maximum load on thrust pads is smaller than the allowable value.

Lateral Vibration of Hydroelectric Generating Set with Different Supporting Condition of Thrust Pad

OpenAIRE

Si, Xiaohui; Lu, Wenxiu; Chu, Fulei

2011-01-01

The variations of the supporting condition, which change the stiffness of tilting pad thrust bearing, may alter the dynamic behavior of the rotor system. The effects of supporting condition of thrust pad on the lateral vibration of a hydroelectric generating set are investigated in this paper. The action of a thrust bearing is described as moments acting on the thrust collar, and the tilting stiffness coefficients of thrust bearing are calculated. A model based on typical beam finite element ...

Performance of integrated retainer rings in silicon micro-turbines with thrust style micro-ball bearings

International Nuclear Information System (INIS)

Hergert, Robert J; Holmes, Andrew S; Hanrahan, Brendan; Ghodssi, Reza

2013-01-01

This work explores the performance of different silicon retainer ring designs when integrated into silicon micro-turbines (SMTs) incorporating thrust style bearings supported on 500 µm diameter steel balls. Experimental performance curves are presented for SMTs with rotor diameters of 5 mm and 10 mm, each with five different retainer designs varying in mechanical rigidity, ball pocket shape and ball complement. It was found that the different retainer designs yielded different performance curves, with the closed pocket designs consistently requiring lower input power for a given rotation speed, and the most rigid retainers giving the best performance overall. Both 5 mm and 10 mm diameter devices have shown repeatable performance at rotation speeds up to and exceeding 20 000 RPM with input power levels below 2 W, and devices were tested for over 2.5 million revolutions without failure. Retainer rings are commonly used in macro-scale bearings to ensure uniform spacing between the rolling elements. The integration of retainers into micro-bearings could lower costs by reducing the number of balls required for stable operation, and also open up the possibility of ‘smart’ bearings with integrated sensors to monitor the bearing status. (paper)

Stabilizing Gas Bearings In Free-Piston Machines

Science.gov (United States)

Dhar, Manmohan

1995-01-01

Gas bearings and clearance seals between pistons and cylinders in free-piston machines designed to reduce undesired dynamic forces and torques on pistons, gas bearings, and cylinders. Circumferential grooves and drain galleries added to piston or cylinder in improved design. Provides stabilization without significant reduction in length of seal, or significant increase in leakage and consequent reduction of efficiency.

Stabilizing gas bearing in free piston machines

Science.gov (United States)

Dhar, Manmohan (Inventor)

1992-01-01

In a free piston engine, to reduce dynamic loads on the reciprocating elements caused by a time varying pressure gradient across the gas bearing and close clearance seals provided therein, drain galleries are incorporated at the ends of the gas bearings to isolate the same, and circumferentially spaced grooves are incorporated in the close clearance seal region.

Study of superconducting magnetic bearing applicable to the flywheel energy storage system that consist of HTS-bulks and superconducting-coils

International Nuclear Information System (INIS)

Seino, Hiroshi; Nagashima, Ken; Tanaka, Yoshichika; Nakauchi, Masahiko

2010-01-01

The Railway Technical Research Institute conducted a study to develop a superconducting magnetic bearing applicable to the flywheel energy-storage system for railways. In the first step of the study, the thrust rolling bearing was selected for application, and adopted liquid-nitrogen-cooled HTS-bulk as a rotor, and adopted superconducting coil as a stator for the superconducting magnetic bearing. Load capacity of superconducting magnetic bearing was verified up to 10 kN in the static load test. After that, rotation test of that approximately 5 kN thrust load added was performed with maximum rotation of 3000rpm. In the results of bearing rotation test, it was confirmed that position in levitation is able to maintain with stability during the rotation. Heat transfer properties by radiation in vacuum and conductivity by tenuous gas were basically studied by experiment by the reason of confirmation of rotor cooling method. The experimental result demonstrates that the optimal gas pressure is able to obtain without generating windage drag. In the second stage of the development, thrust load capacity of the bearing will be improved aiming at the achievement of the energy capacity of a practical scale. In the static load test of the new superconducting magnetic bearing, stable 20kN-levitation force was obtained.

The evaluation of the micro-tracks and micro-dimples on the tribological characteristics of thrust ball bearings.

Science.gov (United States)

Amanov, Auezhan; Pyoun, Young-Shik; Cho, In-Shik; Lee, Chang-Soon; Park, In-Gyu

2011-01-01

One of the primary remedies for tribological problems is surface modification. The reduction of the friction between the ball and the raceway of bearings is a very important goal of the development of bearing technology. A low friction has a positive effect in terms of the extension of the fatigue life, avoidance of a temperature rise, and prevention of premature failure of bearings. Therefore, this research sought to investigate the effects of micro-tracks and micro-dimples on the tribological characteristics at the contact point between the ball and the raceway of thrust ball bearings (TBBs). The ultrasonic nanocrystal surface modification (UNSM) technology was applied using different intervals (feed rates) to the TBB raceway surface to create micro-tracks and micro-dimples. The friction coefficient after UNSM at 50 microm intervals showed marked sensitivity and a significant reduction of 30%. In this study, the results showed that more micro-dimples yield a lower friction coefficient.

Modelling and Identification for Control of Gas Bearings

DEFF Research Database (Denmark)

Theisen, Lukas Roy Svane; Niemann, Hans Henrik; Santos, Ilmar

2015-01-01

Gas bearings are popular for their high speed capabilities, low friction and clean operation, but suffer from poor damping, which poses challenges for safe operation in presence of disturbances. Enhanced damping can be achieved through active lubrication techniques using feedback control laws....... Such control design requires models with low complexity, able to describe the dominant dynamics from actuator input to sensor output over the relevant range of operation. The mathematical models based on first principles are not easy to obtain, and in many cases, they cannot be directly used for control design...... to industrial rotating machinery with gas bearings and to allow for subsequent control design. The paper shows how piezoelectric actuators in a gas bearing are efficiently used to perturb the gas film for identification over relevant ranges of rotational speed and gas injection pressure. Parameter...

Magnetic bearings promise reduced operation and maintenance costs

International Nuclear Information System (INIS)

Jones, G.

1990-01-01

Magnetic bearings are being incorporated into the design of the US DoE modular high temperature gas cooled reactor. The virtually maintenance-free bearing technology may have potential in other nuclear applications. In an active magnetic bearing, a stationary electromagnet (stator) and a rotating ferrous material (rotor) are used to allow a shaft to be suspended in a magnetic field. The position of the shaft is maintained dynamically using position sensors to provide a continuous feedback through a control and amplifier system to the electromagnetic poles which are used to suspend the shaft. Two separate systems are required: an axial positioning system, or thrust bearing, and a pair of radial positioning systems, or journal bearings. (author)

The Influence of Injection Pockets on the Performance of Tilting-Pad Thrust Bearings - Part II: Comparison Between Theory and Experiment

DEFF Research Database (Denmark)

Heinrichson, Niels; Fuerst, Axel; Santos, Ilmar

2007-01-01

This is Part II of a two-part series of papers describing the effects of high-pressure injection pockets on the operating conditions of tilting-pad thrust bearings. The paper has two main objectives. One is an experimental investigation of the influence of an oil injection pocket on the pressure...... and without oil injection) on the pressure distribution and oil film thickness. Measurements of the distribution of pressure and oil film thickness are presented for tilting-pad thrust bearing pads of approx. 100 cm^2 surface area. Two pads are measured in a laboratory test rig at loads of approx. 1.5 MPa...... and approx. 4.0 MPa and velocities of up to 33 m/s. One pad has a plain surface. The other pad has a conical injection pocket at the pivot point and a leading-edge taper. The measurements are compared to theoretical values obtained using a three-dimensional thermoelastohydrodynamic (TEHD) numerical model...

Direct Monte Carlo simulation of nanoscale mixed gas bearings

Directory of Open Access Journals (Sweden)

Kyaw Sett Myo

2015-06-01

Full Text Available The conception of sealed hard drives with helium gas mixture has been recently suggested over the current hard drives for achieving higher reliability and less position error. Therefore, it is important to understand the effects of different helium gas mixtures on the slider bearing characteristics in the head–disk interface. In this article, the helium/air and helium/argon gas mixtures are applied as the working fluids and their effects on the bearing characteristics are studied using the direct simulation Monte Carlo method. Based on direct simulation Monte Carlo simulations, the physical properties of these gas mixtures such as mean free path and dynamic viscosity are achieved and compared with those obtained from theoretical models. It is observed that both results are comparable. Using these gas mixture properties, the bearing pressure distributions are calculated under different fractions of helium with conventional molecular gas lubrication models. The outcomes reveal that the molecular gas lubrication results could have relatively good agreement with those of direct simulation Monte Carlo simulations, especially for pure air, helium, or argon gas cases. For gas mixtures, the bearing pressures predicted by molecular gas lubrication model are slightly larger than those from direct simulation Monte Carlo simulation.

The Influence of Injection Pockets on the Performance of Tilting-Pad Thrust Bearings: Part II – Comparison Between Theory and Experiment

DEFF Research Database (Denmark)

Heinrichson, Niels; Santos, Ilmar

2006-01-01

This is Part II of a two-part series of papers describing the effects of high pressure injection pockets on the operating conditions of tilting-pad thrust bearings. Measurements of the distribution of pressure and oil film thickness are presented for tilting-pad thrust bearing pads of approximately...... 100 cm2 surface area. Two pads are measured in a laboratory test-rig at loads of approximately 0.5, 1.5 and 4.0 MPa and velocities of up to 33 m/s. One pad has a plain surface. The other pad has a conical injection pocket at the pivot point and a leading edge taper. The measurements are compared...... to theoretical values obtained using a three dimensional thermo-elasto-hydrodynamic (TEHD) numerical model. At low and intermediate loads the theoretical pressure distribution corresponds well to the measured values for both pads although the influence of the pocket is slightly underestimated. At high loads...

Optimization design of turbo-expander gas bearing for a 500W helium refrigerator

Science.gov (United States)

Li, S. S.; Fu, B.; Y Zhang, Q.

2017-12-01

Turbo-expander is the core machinery of the helium refrigerator. Bearing as the supporting element is the core technology to impact the design of turbo-expander. The perfect design and performance study for the gas bearing are essential to ensure the stability of turbo-expander. In this paper, numerical simulation is used to analyze the performance of gas bearing for a 500W helium refrigerator turbine, and the optimization design of the gas bearing has been completed. And the results of the gas bearing optimization have a guiding role in the processing technology. Finally, the turbine experiments verify that the gas bearing has good performance, and ensure the stable operation of the turbine.

Operating experience of gas bearing helium circulators in HTGR development facility

International Nuclear Information System (INIS)

Shimomura, H.; Kawaji, S.; Fujisaki, K.; Ihizuka, T.

1988-01-01

The large scale helium gas test facility (HENDEL) has been constructed and operated since March 1982 at the Japan Atomic Energy Research Institute to develop HTGR components. The five electric driven gas circulators with dynamic gas bearings are used to circulate the helium gas of 4MPa and 400 deg. C in loops for their compactness, gas tightness, easy maintenance and free from gas contamination. All of these circulators are variable speed types of 3,000 to 12,000 rpm and have the same gas bearings and electric motors. The four machines among them are equipped with centrifugal impeller and one other machine has regenerative type, and the weight of both type rotors are nearly the same. After the troubles and repairing, both type of circulators were tested and the vibration characteristics were measured as preventing maintenance. From the test and measurements of the circulators, it was presumed that the first trouble on regenerative type was caused from excess unbalance force by falling off of a small pin from the rotating part and the second severe trouble on it was caused by the whipping in gas bearing. The static load on tilting pads indicated close relations to occurrence of the whirling through the measurements. It is recognized that fine balancing of the rotors and delicate clearance adjustment of the bearings are very important for the rotor stability and that the mechanism should be designed and machined so precise as to be adjustable. As the gas bearing would be damaged in an instantaneously short time, the monitoring technique for it should be so fast and predictive as to prevent serious damage. Through the tests, the vibration spectrum monitoring method seems to be predictive and useful for early detection of the shaft instability. It will be concluded that the gas bearing machine is an excellent system in its design philosophy, however, it also needs highly precise machining and delicate maintenance technique. 4 refs, 10 figs, 1 tab

Big bearings. Unsung hero; Kyodaina jikuuke. Hitome ni tsukanai hatarakimono

Energy Technology Data Exchange (ETDEWEB)

Nanba, S. [Koyo Seiko Co. Ltd., Osaka (Japan)

1997-03-05

This paper introduces examples of the use of big bearings. Bearings are divided largely into those used for radial load supporting and those used for thrust load supporting, while big bearings are often used for the latter usage. Thrust bearings include a cutter heat supporting bearing for tunnel excavator working underground, in addition to those used for swing motion of parabolic antennas and tower cranes. A bearing used in an excavator has an outer diameter of about half that of the excavator. The outer diameter of a shielding machine practically used in tunnel drilling currently has an outer diameter of 14,140 mm, and the outer diameter of the bearing is 7200 mm (bearing weighing 45 tons). Other big thrust bearings may include a swing tower swinging thrust bearing used in a continuous casting facility. Big radial bearings are used in iron and steel making facilities. This paper describes two examples of bearings used in this application. A spherical roller bearing to support converter trunion should be of an ultra big size to withstand total weight of about 1400 tons composed of a converter weight and weight of steel to be processed. A four-row cylindrical roller bearing to support the backup roll of a thick plate rolling mill is a bearing with durability against large loads to support reduction rolls whose size have become increasingly large. 2 refs., 5 figs.

Auxiliary bearing design considerations for gas cooled reactors

International Nuclear Information System (INIS)

Penfield, S.R. Jr.; Rodwell, E.

2001-01-01

The need to avoid contamination of the primary system, along with other perceived advantages, has led to the selection of electromagnetic bearings (EMBs) in most ongoing commercial-scale gas cooled reactor (GCR) designs. However, one implication of magnetic bearings is the requirement to provide backup support to mitigate the effects of failures or overload conditions. The demands on these auxiliary or 'catcher' bearings have been substantially escalated by the recent development of direct Brayton cycle GCR concepts. Conversely, there has been only limited directed research in the area of auxiliary bearings, particularly for vertically oriented turbomachines. This paper explores the current state-of-the-art for auxiliary bearings and the implications for current GCR designs. (author)

Investigations of Slip Effect on the Performance of Micro Gas Bearings and Stability of Micro Rotor-Bearing Systems

Directory of Open Access Journals (Sweden)

Jieyu Chen

2007-08-01

Full Text Available Incorporating the velocity slip effect of the gas flow at the solid boundary, theperformance and dynamic response of a micro gas-bearing-rotor system are investigated inthis paper. For the characteristic length scale of the micro gas bearing, the gas flow in thebearing resides in the slip regime rather than in the continuum regime. The modifiedReynolds equations of different slip models are presented. Gas pressure distribution and loadcarrying capacity are obtained by solving the Reynolds equations with finite differentmethod (FDM. Comparing results from different models, it is found that the second orderslip model agrees reasonably well with the benchmarked solutions obtained from thelinearized Boltzmann equation. Therefore, dynamic coefficients derived from the secondorder slip model are employed to evaluate the linear dynamic stability and vibrationcharacteristics of the system. Compared with the continuum flow model, the slip effectreduces dynamic coefficients of the micro gas bearing, and the threshold speed for stableoperation is consequently raised. Also, dynamic analysis shows that the system responseschange with variation of the operating parameters including the eccentricity ratio, therotational speed, and the unbalance ratio.

On The Modeling Of Hybrid Aerostatic - Gas Journal Bearings

DEFF Research Database (Denmark)

Morosi, Stefano; Santos, Ilmar

2010-01-01

of a compressible fluid film journal bearing. Control forces are generated by injecting pressurized air into the bearing gap through orifices located on the bearing walls. A modified form of the compressible Reynolds equation for active lubrication is derived. By solving this equation, stiffness and damping......Gas journal bearing have been increasingly adopted in modern turbo-machinery applications, as they meet the demands of operation at higher rotational speeds, in clean environment and great efficiency. Due to the fact that gaseous lubricants, typically air, have much lower viscosity than more...

On The Modelling Of Hybrid Aerostatic - Gas Journal Bearings

DEFF Research Database (Denmark)

Morosi, Stefano; Santos, Ilmar

2011-01-01

modeling for hybrid lubrication of a compressible fluid film journal bearing. Additional forces are generated by injecting pressurized air into the bearing gap through orifices located on the bearing walls. A modified form of the compressible Reynolds equation for active lubrication is derived. By solving......Gas journal bearing have been increasingly adopted in modern turbo-machinery applications, as they meet the demands of operation at higher rotational speeds, in clean environment and great efficiency. Due to the fact that gaseous lubricants, typically air, have much lower viscosity than more...

Characterization and measurement of hybrid gas journal bearings

Science.gov (United States)

Lawrence, Tom Marquis

This thesis concentrates on the study of hybrid gas journal bearings (bearings with externally pressurized mass addition). It differs from most work in that it goes back to "basics" to explore the hydrodynamic phenomena in the bearing gap. The thesis compares geometrically identical bearings with 2 configurations of external pressurization, porous liners where mass-addition compensation is varied by varying the liner's permeability, and bushings with 2 rows of 6 feedholes where the mass-addition compensation is varied by the feedhole diameter. Experimentally, prototype bearings with mass-addition compensation that spans 2 orders of magnitude with differing clearances are built and their aerostatic properties and mass addition characteristics are thoroughly tested. The fundamental equations for compressible, laminar, Poiseuille flow are used to suggest how the mass flow "compensation" should be mathematically modeled. This is back-checked against the experimental mass flow measurements and is used to determine a mass-addition compensation parameter (called Kmeas) for each prototype bushing. In so doing, the methodology of modeling and measuring the mass addition in a hybrid gas bearing is re-examined and an innovative, practical, and simple method is found that makes it possible to make an "apples-to-apples" comparison between different configurations of external pressurization. This mass addition model is used in conjunction with the Reynolds equation to perform theory-based numerical analysis of virtual hybrid gas journal bearings (CFD experiments). The first CFD experiments performed use virtual bearings modeled to be identical to the experimental prototypes and replicate the experimental work. The results are compared and the CFD model is validated. The ontological significance of appropriate dimensionless similitude parameters is re-examined and a, previously lacking, complete set of similitude factors is found for hybrid bearings. A new practical method is

Lateral Dynamics of Flexible Rotors Supported by Controllable Gas Bearings Theory & Experiment

DEFF Research Database (Denmark)

Pierart Vásquez, Fabián Gonzalo; Santos, Ilmar

2015-01-01

Active gas bearings might represent a mechatronic answer to the growing industrial need for high performance turbomachinery. In this framework, the paper gives a theoretical and experimental contribution to the improvement of lateral dynamics of rotating machines. The work aims at demonstrating...... theoretically as well as experimentally the feasibility of applying active lubrication to gas journal bearings. The operation principle is to generate active forces by regulating the radial injection of a compressible lubricant (gas) by means of piezoelectric actuators mounted on the back of the bearing sleeve....... The active control principle is built using eddy-current sensor signals to detect the lateral motion of the rotor. A feedback law is used to couple the lateral dynamics of a flexible rotor-bearing system with the pneumatic and dynamic characteristics of a piezoelectric actuated valve system. A proportional...

Recent research and development of bearings for helium circulator

International Nuclear Information System (INIS)

Taniguchi, S.; Ezaki, Z.; Kawaguchi, K.; Matsumura, N.; Kozima, M.

1988-01-01

This paper mainly describes recent studies and successful applications of water lubricated bearing and gas lubricated bearing. Both types of bearing seem to be suitable for a turbo machine installed in an atomic energy plant - such as the helium circulator of a HTGR - not to be affected by radioactivity, so we have been attracted by them for about 10 years. The former was investigated theoretically taking account of turbulent flow due to the low viscosity of water, and compared with the experimental data. Good agreement was obtained, and a successful example applied to a small-sized high speed air compressor is shown. The latter was investigated using a large-sized bearing test rig simulated to an actual machine. The tilting pad journal bearing and the tilting pad thrust bearing were taken and improved for some aspects. These bearings have been taken into service on an actual circulator and are now operating successfully. Currently, a magnetic bearing is being studied to pay special attention to endurance for an earthquake and catcher bearing system. We would like to have an opportunity to present these results in the near future. (author). 5 refs, 15 figs, 2 tabs

Enhancing damping of gas bearings using linear parameter-varying control

DEFF Research Database (Denmark)

Theisen, Lukas Roy Svane; Niemann, Hans Henrik; Galeazzi, Roberto

2017-01-01

systems to regulate the injection pressure of the fluid. Due to the strong dependencies of system performance on system parameters, the sought controller should be robust over a large range of operational conditions. This paper addresses the damping enhancement of controllable gas bearings through robust...... control approaches. Through an extensive experimental campaign the paper evaluates two robust controllers, a linear parametervarying (LPV) controller and ∞ controller, on their capability to guarantee stability and performance of a gas bearing across the large operational envelopes in rotational speed...

燃气喷射推力矢量喷管气固两相流数值模拟%Numerical simulation of gas-particle flow in hot gas injection thrust vector nozzle

Institute of Scientific and Technical Information of China (English)

刘辉; 邢玉明

2013-01-01

利用Euler-Lagrangian方法模拟了固体火箭发动机燃气喷射推力矢量喷管气固两相内流场,研究了固体颗粒对喷管推力矢量性能的影响,气相采用Roe格式和MUSCL (monotone upstream-centred schemes for conservation laws)插值进行空间2阶迎风离散,时间推进采用隐式时间格式；固体颗粒相采用随机轨道模型计算颗粒轨迹,并与气相进行双向耦合.结果表明:固体颗粒的存在使弓形激波强度增强,但降低了推力矢量角和推力系数；颗粒质量分数相同时,粒径越大,推力矢量角和推力系数越大；颗粒直径相同时,颗粒质量分数越大,推力矢量角和推力系数越小.%The gas-particle inner flowfield of gas injection thrust vector nozzle in solid rocket engine was simulated using Euler-Lagrangian method, and the effect of solid particle on thrust vector performance was studied. The Roe scheme and monotone upstream-centred schemes for conservation laws (MUSCL) method were used for secondary-order accuracy spatial discretization for gas phase, and the implicit scheme was employed for time marching. The stochastic trajectory model and two-way coupled with gas phase were employed for particle phase. The results indicate that the strength of bow shock is increased due to solid particles, but the thrust vector angle and thrust coefficient are decreased; thrust vector angle and thrust coefficient increase with the particle diameter increasing under the same mass fraction of particle condition; thrust vector angle and thrust coefficient decrease with the mass fraction of particle increasing under the same particle diameter condition.

Effect of boundary conditions on the performances of gas-lubricated micro journal bearing

International Nuclear Information System (INIS)

Wang Sheng; Lei Kangbin; Kiwamu, Kase; Luo Xilian; Gu Zhaolin

2010-01-01

As significant components of micromechanics, gas-lubricated microbearings are more prevalent for their special advantages than other types. The fluid dynamics of the microbearing is different from their larger cousins due to the noncontinuum effect and surface-dominated effect, which may make the Navier-Stokes equations invalid. In this paper, by considering the accommodation coefficients on journal (α i ) and that on bearing (α o ) separately, the microbearings with different bearing numbers under the assumption of large L/D (length to diameter) are simulated using direct simulation Monte Carlo (DSMC) program incorporated with a Volume-CAD software. The diffuse reflection model and Cercignani-Lampis-Lord (CLL) model are applied to model the molecule-surface interaction. The flow field characteristics, as well as the performances of gas-lubricated journal bearings including load-carrying capacity, attitude angle and bearing drag are obtained. The results reveal that α i and α o have different effects to flow field characteristics and bearing performances. The bearing number has significantly impact on the bearing performances. The method developed in this paper would be very useful for designing and evaluating the gas-lubricated journal microbearing.

Experimental Grey Box Model Identification of an Active Gas Bearing

DEFF Research Database (Denmark)

Theisen, Lukas Roy Svane; Pierart Vásquez, Fabián Gonzalo; Niemann, Hans Henrik

2014-01-01

in a dynamic model of an active gas bearing and subsequent control loop design. A grey box model is determined based on experiments where piezo actuated valves are used to perturb the journal and hence excite the rotor-bearing system. Such modelling from actuator to output is shown to effciently support...

Active lubrication applied to radial gas journal bearings. Part 1: Modeling

DEFF Research Database (Denmark)

Morosi, Stefano; Santos, Ilmar

2011-01-01

Active bearings represent a mechatronic answer to the growing industrial need to high performance turbomachinery. The present contribution aims at demonstrate the feasibility of applying active lubrication to gas journal bearings. The principle of operation is to generate active forces by regulat...

Dynamic Stability Study of Static Gas Bearing for Small Cryogenic Turbo-Expander

International Nuclear Information System (INIS)

Wang Xuemin; Zhuang Ming; Zhang Qiyong; Li Shanshan; Fu Bao

2011-01-01

An experimental method is presented to analyze the dynamic stability of the gas bearing for small cryogenic turbo-expanders. The rotation imbalance response and the shape of the rotor orbit were obtained for different speeds up to 110,000 rpm, and the critical speed of the rotor-bearing system was determined by a Bode diagram. An FFT signal analytical method was applied to identify the resonance frequency, and the waterfall plot was presented. During the whole process of speeding up to the designed speed of 110,000 rpm, the rotor-bearing works stably with no whirl instability, which is validated in a waterfall plot. Also, the tested rotor-bearing model was analyzed theoretically. It was proved that the experimental results were highly consistent with those of theoretical calculations. Thus the experimental method proposed here to analyze the dynamic stability of the gas bearing is feasible. (fusion engineering)

Greenhouse gas mitigation can reduce sea-ice loss and increase polar bear persistence

Science.gov (United States)

Amstrup, Steven C.; Deweaver, E.T.; Douglas, David C.; Marcot, B.G.; Durner, George M.; Bitz, C.M.; Bailey, D.A.

2010-01-01

On the basis of projected losses of their essential sea-ice habitats, a United States Geological Survey research team concluded in 2007 that two-thirds of the worlds polar bears (Ursus maritimus) could disappear by mid-century if business-as-usual greenhouse gas emissions continue. That projection, however, did not consider the possible benefits of greenhouse gas mitigation. A key question is whether temperature increases lead to proportional losses of sea-ice habitat, or whether sea-ice cover crosses a tipping point and irreversibly collapses when temperature reaches a critical threshold. Such a tipping point would mean future greenhouse gas mitigation would confer no conservation benefits to polar bears. Here we show, using a general circulation model, that substantially more sea-ice habitat would be retained if greenhouse gas rise is mitigated. We also show, with Bayesian network model outcomes, that increased habitat retention under greenhouse gas mitigation means that polar bears could persist throughout the century in greater numbers and more areas than in the business-as-usual case. Our general circulation model outcomes did not reveal thresholds leading to irreversible loss of ice; instead, a linear relationship between global mean surface air temperature and sea-ice habitat substantiated the hypothesis that sea-ice thermodynamics can overcome albedo feedbacks proposed to cause sea-ice tipping points. Our outcomes indicate that rapid summer ice losses in models and observations represent increased volatility of a thinning sea-ice cover, rather than tipping-point behaviour. Mitigation-driven Bayesian network outcomes show that previously predicted declines in polar bear distribution and numbers are not unavoidable. Because polar bears are sentinels of the Arctic marine ecosystem and trends in their sea-ice habitats foreshadow future global changes, mitigating greenhouse gas emissions to improve polar bear status would have conservation benefits throughout

Greenhouse gas mitigation can reduce sea-ice loss and increase polar bear persistence.

Science.gov (United States)

Amstrup, Steven C; Deweaver, Eric T; Douglas, David C; Marcot, Bruce G; Durner, George M; Bitz, Cecilia M; Bailey, David A

2010-12-16

On the basis of projected losses of their essential sea-ice habitats, a United States Geological Survey research team concluded in 2007 that two-thirds of the world's polar bears (Ursus maritimus) could disappear by mid-century if business-as-usual greenhouse gas emissions continue. That projection, however, did not consider the possible benefits of greenhouse gas mitigation. A key question is whether temperature increases lead to proportional losses of sea-ice habitat, or whether sea-ice cover crosses a tipping point and irreversibly collapses when temperature reaches a critical threshold. Such a tipping point would mean future greenhouse gas mitigation would confer no conservation benefits to polar bears. Here we show, using a general circulation model, that substantially more sea-ice habitat would be retained if greenhouse gas rise is mitigated. We also show, with Bayesian network model outcomes, that increased habitat retention under greenhouse gas mitigation means that polar bears could persist throughout the century in greater numbers and more areas than in the business-as-usual case. Our general circulation model outcomes did not reveal thresholds leading to irreversible loss of ice; instead, a linear relationship between global mean surface air temperature and sea-ice habitat substantiated the hypothesis that sea-ice thermodynamics can overcome albedo feedbacks proposed to cause sea-ice tipping points. Our outcomes indicate that rapid summer ice losses in models and observations represent increased volatility of a thinning sea-ice cover, rather than tipping-point behaviour. Mitigation-driven Bayesian network outcomes show that previously predicted declines in polar bear distribution and numbers are not unavoidable. Because polar bears are sentinels of the Arctic marine ecosystem and trends in their sea-ice habitats foreshadow future global changes, mitigating greenhouse gas emissions to improve polar bear status would have conservation benefits throughout

Cascading Tesla Oscillating Flow Diode for Stirling Engine Gas Bearings

Science.gov (United States)

Dyson, Rodger

2012-01-01

Replacing the mechanical check-valve in a Stirling engine with a micromachined, non-moving-part flow diode eliminates moving parts and reduces the risk of microparticle clogging. At very small scales, helium gas has sufficient mass momentum that it can act as a flow controller in a similar way as a transistor can redirect electrical signals with a smaller bias signal. The innovation here forces helium gas to flow in predominantly one direction by offering a clear, straight-path microchannel in one direction of flow, but then through a sophisticated geometry, the reversed flow is forced through a tortuous path. This redirection is achieved by using microfluid channel flow to force the much larger main flow into this tortuous path. While microdiodes have been developed in the past, this innovation cascades Tesla diodes to create a much higher pressure in the gas bearing supply plenum. In addition, the special shape of the leaves captures loose particles that would otherwise clog the microchannel of the gas bearing pads.

Another Look at Rocket Thrust

Science.gov (United States)

Hester, Brooke; Burris, Jennifer

2012-01-01

Rocket propulsion is often introduced as an example of Newton's third law. The rocket exerts a force on the exhaust gas being ejected; the gas exerts an equal and opposite force--the thrust--on the rocket. Equivalently, in the absence of a net external force, the total momentum of the system, rocket plus ejected gas, remains constant. The law of…

Dynamic behavior of air lubricated pivoted-pad journal-bearing, rotor system. 2: Pivot consideration and pad mass

Science.gov (United States)

Nemeth, Z. N.

1972-01-01

Rotor bearing dynamic tests were conducted with tilting-pad journal bearings having three different pad masses and two different pivot geometries. The rotor was vertically mounted and supported by two three-pad tilting-pad gas journal bearings and a simple externally pressurized thrust bearing. The bearing pads were 5.1 cm (2.02 in.) in diameter and 2.8 cm (1.5 in.) long. The length to diameter ratio was 0.75. One pad was mounted on a flexible diaphragm. The bearing supply pressure ranged from 0 to 690 kilonewtons per square meter (0 to 100 psig), and speeds ranged to 38,500 rpm. Heavy mass pad tilting-pad assemblies produced three rotor-bearing resonances above the first two rotor critical speeds. Lower supply pressure eliminated the resonances. The resonances were oriented primarily in the direction normal to the diaphragm.

Closed loop identification of a piezoelectrically controlled radial gas bearing: Theory and experiment

DEFF Research Database (Denmark)

Sekunda, André Krabdrup; Niemann, Hans Henrik; Poulsen, Niels Kjølstad

2018-01-01

Gas bearing systems have extremely small damping properties. Feedback control is thus employed to increase the damping of gas bearings. Such a feedback loop correlates the input with the measurement noise which in turn makes the assumptions for direct identification invalid. The originality...... of this article lies in the investigation of the impact of using different identification methods to identify a rotor-bearing systems’ dynamic model when a feedback loop is active. Two different identification methods are employed. The first method is open loop Prediction Error Method, while the other method...

Thrust augmentation for a small turbojet engine

OpenAIRE

Hackaday, Gary L.

1999-01-01

Approved for public release; distribution is unlimited A Sophia J450 (nine pounds of thrust) gas turbine engine was used first to examine the thrust augmentation generated using an ejector shroud. Experimental results obtained with and without the ejector were compared with performance predicted using an engine code and a one-dimensional ejector analysis. The engine code was revised to incorporate a radial turbine and the correct compressor map. Thrust augmentation of 3-10% was measured an...

The R and D D's bearing test benches

International Nuclear Information System (INIS)

Vialettes, J.M.

1997-01-01

In power generation plants, rotating machines are involved in energy transformation processes and safety systems. The bearings supporting the rotors and the thrust bearings play a crucial role in the reliability of these machines. The phenomena encountered straddle several disciplines: hydrodynamics, tribology, thermomechanics, materials and vibrations in a specific environment, namely: thin fluid film, solid mechanical components and shaft rotation. Means of analysing the behaviour of these components (bearings and thrust bearings) have been developed and implemented. These consists of the EDYOS (Etude Dynamique des Organes de Supportage) code for dynamically studying bearing devices and several related bench tests. In reality, in order to understand the complex physical phenomena encountered in these components, it is vital to carry out analyses and experimental validations. Since these investigations cannot be carried out on actual machines, test benches have been built which can subject the sample bearings to the equivalent stresses. (author)

Improvement of Dynamic Performance of Hybrid Gas Bearings via Adjustable Lubrication

DEFF Research Database (Denmark)

Pierart Vásquez, Fabián Gonzalo; Santos, Ilmar

2013-01-01

and the pressure and velocity fields in the injection nozzle are compared. The simplified theoretical model has been validated against the CFD results and experimentally using a test rig. The test rig consists of a flexible rotor supported by a ball bearing and a controllable hybrid gas bearing. The results show...

High-BTU gas production from tar-bearing hot coke oven gas over iron catalyst

Energy Technology Data Exchange (ETDEWEB)

L.Y. Li; K. Morishita; T. Takarada [Gunma University, Gunma (Japan). Department of Biological and Chemical Engineering

2005-07-01

To utilize the tar-bearing hot coke oven gas (the by-product of coke making process) more effectively, a process was developed by converting the hot coke oven gas into a methane rich high-BTU gas over iron-bearing catalysts. The catalytic behaviour of Indonesian limonite ore was mainly discussed. For a reference, a conventional nickel catalyst (Ni/Al{sub 2}O{sub 3}) was employed. Laboratory scale tests were carried out in a two-stage fixed-bed reactor at ambient pressure. A bituminous coal sample was heated at first stage, the volatiles was carried by feed gas and decomposed at second stage. The limonite promoted hydropyrolysis of coal volatiles similar to Ni/Al{sub 2}O{sub 3} catalyst. High yields of total product gas and methane were obtained at 50 vol.% hydrogen atmosphere with a feed gas of 60 ml min{sup -1} hydrogen and 60 ml min{sup -1} nitrogen. After experiments, hydrocarbons heavier than ethane were not observed. Also that, carbon balance was more than 99.8% in coal char, product gases and carbon deposits. It was considered that coal volatiles converted into light gases and carbon almost completely in catalyst bed. Yields of product gas and methane depended upon catalytic temperature. At 923 K, the maximum yield of product gas was achieved at 74.3% for limonite catalyst on carbon balance with methane 83.2 vol.% of the carbonaceous gas products. Comparing with limonite, Fe/Al{sub 2}O{sub 3} and BOF dust samples showed low activities on coal volatiles catalytic decomposition. 21 refs., 5 figs., 3 tabs.

Assessment of undiscovered conventional oil and gas resources in the Wyoming Thrust Belt Province, Wyoming, Idaho, and Utah, 2017

Science.gov (United States)

Schenk, Christopher J.; Mercier, Tracey J.; Tennyson, Marilyn E.; Woodall, Cheryl A.; Brownfield, Michael E.; Le, Phuong A.; Klett, Timothy R.; Gaswirth, Stephanie B.; Finn, Thomas M.; Marra, Kristen R.; Leathers-Miller, Heidi M.

2018-02-16

Using a geology-based assessment methodology, the U.S. Geological Survey estimated mean undiscovered, technically recoverable resources of 26 million barrels of oil and 700 billion cubic feet of gas in the Wyoming Thrust Belt Province, Wyoming, Idaho, and Utah.

INFLUENCE OF AXIAL COMPRESSOR STAGE SPATIAL OPTIMIZATION ON THRUST-ECONOMICAL CHARACTERISTICS OF CARGO AIRCRAFT GAS TURBINE ENGINE

Directory of Open Access Journals (Sweden)

L.G. Volyanskaya

2005-02-01

Full Text Available  The article considers the research results of D-27 gas turbine engine thrust-economical characteristics change due to of axial compressor flow path optimization. The applied procedure of optimization takes into account a difference in the shapes of axial compressor stage blades at rest and design mode, redistribution of kinetic energy losses along the blade height. The estimation of parameters of a gas flow in the stage flow path is made by the solution of Navier-Stokes equation complete set.

From Hybrid to Actively-Controlled Gas Lubricated Bearings – Theory and Experiment

DEFF Research Database (Denmark)

Morosi, Stefano

bearings, tilting pad and flexure pivot gas bearings. These solutions proved to be effective in improving static and dynamic properties of the bearings, however issues related to the manufacturing and accuracy of predictions has so far limited their applications. Another drawback is that passive bearings......-rig are backed by a comprehensive mathematical model that couples a finite element model of a flexible rotor, a thermohydrodynamic model based on a modified form of the Reynold’s equation for hybrid aerostatic-aerodynamic lubrication of compressible fluid, a piezoelectric injection system and a proportional...

Analysis of gas turbine engines using water and oxygen injection to achieve high Mach numbers and high thrust

Science.gov (United States)

Henneberry, Hugh M.; Snyder, Christopher A.

1993-01-01

An analysis of gas turbine engines using water and oxygen injection to enhance performance by increasing Mach number capability and by increasing thrust is described. The liquids are injected, either separately or together, into the subsonic diffuser ahead of the engine compressor. A turbojet engine and a mixed-flow turbofan engine (MFTF) are examined, and in pursuit of maximum thrust, both engines are fitted with afterburners. The results indicate that water injection alone can extend the performance envelope of both engine types by one and one-half Mach numbers at which point water-air ratios reach 17 or 18 percent and liquid specific impulse is reduced to some 390 to 470 seconds, a level about equal to the impulse of a high energy rocket engine. The envelope can be further extended, but only with increasing sacrifices in liquid specific impulse. Oxygen-airflow ratios as high as 15 percent were investigated for increasing thrust. Using 15 percent oxygen in combination with water injection at high supersonic Mach numbers resulted in thrust augmentation as high as 76 percent without any significant decrease in liquid specific impulse. The stoichiometric afterburner exit temperature increased with increasing oxygen flow, reaching 4822 deg R in the turbojet engine at a Mach number of 3.5. At the transonic Mach number of 0.95 where no water injection is needed, an oxygen-air ratio of 15 percent increased thrust by some 55 percent in both engines, along with a decrease in liquid specific impulse of 62 percent. Afterburner temperature was approximately 4700 deg R at this high thrust condition. Water and/or oxygen injection are simple and straightforward strategies to improve engine performance and they will add little to engine weight. However, if large Mach number and thrust increases are required, liquid flows become significant, so that operation at these conditions will necessarily be of short duration.

Maximum Recoverable Gas from Hydrate Bearing Sediments by Depressurization

KAUST Repository

Terzariol, Marco

2017-11-13

The estimation of gas production rates from hydrate bearing sediments requires complex numerical simulations. This manuscript presents a set of simple and robust analytical solutions to estimate the maximum depressurization-driven recoverable gas. These limiting-equilibrium solutions are established when the dissociation front reaches steady state conditions and ceases to expand further. Analytical solutions show the relevance of (1) relative permeabilities between the hydrate free sediment, the hydrate bearing sediment, and the aquitard layers, and (2) the extent of depressurization in terms of the fluid pressures at the well, at the phase boundary, and in the far field. Close form solutions for the size of the produced zone allow for expeditious financial analyses; results highlight the need for innovative production strategies in order to make hydrate accumulations an economically-viable energy resource. Horizontal directional drilling and multi-wellpoint seafloor dewatering installations may lead to advantageous production strategies in shallow seafloor reservoirs.

Hydrostatic and hybrid bearing design

CERN Document Server

Rowe, W B

1983-01-01

Hydrostatic and Hybrid Bearing Design is a 15-chapter book that focuses on the bearing design and testing. This book first describes the application of hydrostatic bearings, as well as the device pressure, flow, force, power, and temperature. Subsequent chapters discuss the load and flow rate of thrust pads; circuit design, flow control, load, and stiffness; and the basis of the design procedures and selection of tolerances. The specific types of bearings, their design, dynamics, and experimental methods and testing are also shown. This book will be very valuable to students of engineering des

Bearing construction for refrigeration compresssor

Science.gov (United States)

Middleton, Marc G.; Nelson, Richard T.

1988-01-01

A hermetic refrigeration compressor has a cylinder block and a crankshaft rotatable about a vertical axis to reciprocate a piston in a cylinder on the cylinder block. A separate bearing housing is secured to the central portion of the cylinder block and extends vertically along the crankshaft, where it carries a pair of roller bearings to journal the crankshaft. The crankshaft has a radially extending flange which is journaled by a thrust-type roller bearing above the bearing housing to absorb the vertical forces on the crankshaft so that all three of the roller bearings are between the crankshaft and the bearing housing to maintain and control the close tolerances required by such bearings.

An Assessment of Gas Foil Bearing Scalability and the Potential Benefits to Civilian Turbofan Engines

Science.gov (United States)

Bruckner, Robert J.

2010-01-01

Over the past several years the term oil-free turbomachinery has been used to describe a rotor support system for high speed turbomachinery that does not require oil for lubrication, damping, or cooling. The foundation technology for oil-free turbomachinery is the compliant foil bearing. This technology can replace the conventional rolling element bearings found in current engines. Two major benefits are realized with this technology. The primary benefit is the elimination of the oil lubrication system, accessory gearbox, tower shaft, and one turbine frame. These components account for 8 to 13 percent of the turbofan engine weight. The second benefit that compliant foil bearings offer to turbofan engines is the capability to operate at higher rotational speeds and shaft diameters. While traditional rolling element bearings have diminished life, reliability, and load capacity with increasing speeds, the foil bearing has a load capacity proportional to speed. The traditional applications for foil bearings have been in small, lightweight machines. However, recent advancements in the design and manufacturing of foil bearings have increased their potential size. An analysis, grounded in experimentally proven operation, is performed to assess the scalability of the modern foil bearing. This analysis was coupled to the requirements of civilian turbofan engines. The application of the foil bearing to larger, high bypass ratio engines nominally at the 120 kN (approx.25000 lb) thrust class has been examined. The application of this advanced technology to this system was found to reduce mission fuel burn by 3.05 percent.

A superconducting thrust-bearing system for an energy storage flywheel

Energy Technology Data Exchange (ETDEWEB)

Coombs, T.A.; Cansiz, A.; Campbell, A.M. [IRC in Superconductivity, Cambridge (United Kingdom)

2002-05-01

We have constructed a bearing system for an energy storage flywheel. This bearing system uses a combination of permanent magnets and superconductors in an arrangement commonly termed as an Evershed bearing. In an Evershed system there are in fact two bearings which act in concert. In our system we have one bearing constructed entirely out of permanent magnets acting in attraction. This system bears the weight of the flywheel (43.6 kg) but would not, on its own, be stable. Stability is provided by a superconducting bearing which is formed by the interaction between the magnetic field of a permanent magnet sited on the rotor and superconductors on the stator. This overall arrangement is stable over a range of levitation heights and has been tested at rotation speeds of up to around 12 Hz (the maximum speed is dictated by the drive system not the bearing system). There is a sharp resonance peaking at between 2 and 3 Hz and spin down tests indicate that the equivalent coefficient of friction is of the order of 10{sup -5}. The rate of change of velocity is, however, not constant so the drag is clearly not solely frictional. The position of the resonance is dictated by the stiffness of the bearing relative to the mass of the flywheel but the amplitude of the resonance is dictated by the variation in magnitude of the magnetic field of the permanent magnets. Large magnets are (at present) fabricated in sections and this leads to a highly inhomogeneous field. The field has been smoothed by using a combination of iron which acts passively and copper which provides magnetic shielding due to the generation of eddy currents and therefore acts as an 'active' component. Calculations based on the spin down tests indicate that the resultant variation in field is of the order of 3% and measurements are being carried out to confirm this. (author)

Electronegative Gas Thruster - Direct Thrust Measurement Project

Science.gov (United States)

Dankanich, John (Principal Investigator); Aanesland, Ane; Polzin, Kurt; Walker, Mitchell

2015-01-01

This effort is an international collaboration and academic partnership to mature an innovative electric propulsion (EP) thruster concept to TRL 3 through direct thrust measurement. The initial target application is for Small Satellites, but can be extended to higher power. The Plasma propulsion with Electronegative GASES (PEGASES) concept simplifies ion thruster operation, eliminates a neutralizer requirement and should yield longer life capabilities and lower cost implementation over conventional gridded ion engines. The basic proof-of concept has been demonstrated and matured to TRL 2 over the past several years by researchers at the Laboratoire de Physique des Plasma in France. Due to the low maturity of the innovation, there are currently no domestic investments in electronegative gas thrusters anywhere within NASA, industry or academia. The end product of this Center Innovation Fund (CIF) project will be a validation of the proof-of-concept, maturation to TRL 3 and technology assessment report to summarize the potential for the PEGASES concept to supplant the incumbent technology. Information exchange with the foreign national will be one-way with the exception of the test results. Those test results will first go through a standard public release ITAR/export control review, and the results will be presented in a public technical forum, and the results will be presented in a public technical forum.

ELEMENT DESIGN FOR AN INKJET SYSTEM OF HYDROSTATIC GAS BEARING CONTROL

Directory of Open Access Journals (Sweden)

T. E. Il'ina

2015-09-01

Full Text Available Subject of Study. The paper discusses the concept of inkjet systems application, also known as pneumonics, for automatic hydrostatic gas bearing control. Inkjet systems have the advantages over traditional control systems in those problems where the speed of traditional mechanical, electrical or hydraulic servomotors is not enough. Control of the shaft position in gas bearing with forced gas supply into the gap between the shaft and the bearing is typical for this class of problems. In this case, control means the pressure changing or flow rate of gas supplied to the gap by at least one of three axes at a frequency higher than the nominal speed of the shaft. Thus, high speed of response is required from the system. The objective of this work is to design a discrete jet element, testing of its geometry and switching characteristics. Main Results. The discrete inkjet element for oil-free non-contact transmission working on the refrigerant was designed. Relay transition process was modeled in the inkjet element with the use of numerical methods. The switching time has reached 0.2-0.3 ms; this is one order less than the requirements of aircraft control systems, which typically operate at a frequency of about 200 Hz. It is shown that periodic oscillations with high frequency occur when the control signal is injected with insufficient level of pressure. Therefore, a separate design task is to determine the minimum pressure allowable in the control channel.

Static Load Distribution in Ball Bearings

Science.gov (United States)

Ricci, Mario

2010-01-01

A numerical procedure for computing the internal loading distribution in statically loaded, single-row, angular-contact ball bearings when subjected to a known combined radial and thrust load is presented. The combined radial and thrust load must be applied in order to avoid tilting between inner and outer rings. The numerical procedure requires the iterative solution of Z + 2 simultaneous nonlinear equations - where Z is the number of the balls - to yield an exact solution for axial and radial deflections, and contact angles. Numerical results for a 218 angular-contact ball bearing have been compared with those from the literature and show significant differences in the magnitudes of the ball loads, contact angles, and the extent of the loading zone.

Rupture of a high pressure gas or steam pipe in a tunnel: a preliminary investigation of the jet thrust exerted on a tunnel barrier

International Nuclear Information System (INIS)

Baum, M.R.

1988-04-01

On power plant, if a high pressure pipe containing high temperature gas or steam were to rupture, sensitive equipment necessary for safety shutdown of the plant could possibly be incapacitated if exposed to the subsequent high temperature environment. In many plant configurations the high pressure pipework is contained in tunnels where it is possible to construct barriers which isolate one section of the plant from another, thereby restricting the spread of the high temperature fluid/air mixture. This paper describes a preliminary experimental investigation of the magnitude of the thrust likely to be exerted on such barriers by a gas jet issuing from the failed pipe. Measurements of the thrust exerted on a flat plate by normal impingement of a highly underexpanded gas jet are in agreement with a semi-quantitative analysis assuming conservation of the axial momentum of the jet. (author)

Experimental contribution to the study of gas bearings

International Nuclear Information System (INIS)

Gobert, G.

1962-01-01

Developments for gas-lubricated bearings are discussed. The study of how the fluid film behaves compared to what one can expect is discussed. Various devices are described which have allowed us to go up to peripheral velocity greater than 400 m/s, leading to rotational speed of several thousand revolutions per second. This is obtained by using an automatic setting for the distance between fixed and rotating walls. (author) [fr

スパイラルグルーブ気体軸受の動的負荷容量 - グルーブ深さの影響 -

OpenAIRE

浦, 晟; 中嶋, 明; 前田, 正継; 森高, 秀四郎

1982-01-01

The spiral groove thrust bearing can be operated at the dynamic stable condition and furthermore can bring a large load capacity comparing with the other type of gas bearing such as the Rayleigh pad or the tilting pad types. Accordingly this type of gas bearing has been used as a practical one for a thrust gas bearing of rotary performance. Although the principle and its function have been studied much enough on their theoretical points, it is quite difficult at present to get the plentiful e...

Micromechanical investigation of sand migration in gas hydrate-bearing sediments

Science.gov (United States)

Uchida, S.; Klar, A.; Cohen, E.

2017-12-01

Past field gas production tests from hydrate bearing sediments have indicated that sand migration is an important phenomenon that needs to be considered for successful long-term gas production. The authors previously developed the continuum based analytical thermo-hydro-mechanical sand migration model that can be applied to predict wellbore responses during gas production. However, the model parameters involved in the model still needs to be calibrated and studied thoroughly and it still remains a challenge to conduct well-defined laboratory experiments of sand migration, especially in hydrate-bearing sediments. Taking the advantage of capability of micromechanical modelling approach through discrete element method (DEM), this work presents a first step towards quantifying one of the model parameters that governs stresses reduction due to grain detachment. Grains represented by DEM particles are randomly removed from an isotropically loaded DEM specimen and statistical analyses reveal that linear proportionality exists between the normalized volume of detached solids and normalized reduced stresses. The DEM specimen with different porosities (different packing densities) are also considered and statistical analyses show that there is a clear transition between loose sand behavior and dense sand behavior, characterized by the relative density.

Model-Based Control Design for Flexible Rotors Supported by Active Gas Bearings - Theory & Experiment

DEFF Research Database (Denmark)

Pierart Vásquez, Fabián Gonzalo

, abundant and clean. Nevertheless, this technology has important drawbacks: the low viscosity of the lubricant results in a low load carrying capacity and gas bearings also presents low damping properties, which often lead to a reduced stability range and make dangerous running close to, or across...... theoretical model for active gas bearings, with special attention to the modelling of the injection system. Secondly, experimentally validate the improved mathematical model in terms of static properties (journal equilibrium position and resulting aerodynamic forces) and dynamic properties (natural...

Operating experience with gas-bearing circulators in a high-pressure helium loop

International Nuclear Information System (INIS)

Sanders, J.P.; Gat, U.; Young, H.C.

1988-01-01

A high-pressure engineering test loop has been designed and constructed at the Oak Ridge National Laboratory for circulating helium through a test chamber at temperatures to 1,000 deg. C. The purpose of this loop is to determine the thermal and structural performance of proposed components for the primary loops of gas-cooled nuclear reactors. Three gas-bearing circulators, mounted in series, provide a maximum volumetric flow of 0.47 m 3 /s and a maximum head of 78 kJ/kg at operating pressures from 0.1 to 10.7 MPa. Control of gaseous impurities in the circulating gas was the significant operating requirement that dictated the choice of a circulator that is lubricated by the circulating gas. The motor for each circulator is contained within the pressure boundary, and it is cooled by circulating the gas in the motor cavity over water-cooled coils. Each motor is rated at 200 kW at a speed of 23,500 rpm. The circulators have been operated in the loop for more than 5,000 h. The flow of the gas in the loop is controlled by varying the speed of the circulators through the use of individual 250-kVA, solid state power supplies that can be continuously varied in frequency from 50 to 400 Hz. To prevent excessive wear on the gas bearings during startup, the circulator motor accelerates the rotor to 3,000 rpm in less than one second. During operation, no problems associated with the gas bearings, per se, were encountered; however, related problems pointed to design considerations that should be included in future applications of circulators of this type. The primary test that has been conducted in this loop required sustained operation for several weeks without interruption. After a number of unscheduled interruptions, the operating goals were attained. During part of this period, the loop was operated with only two circulators installed in the pressure vessels with a guard installed in the third vessel to protect the closure flange from the gas temperatures. Unattended

Failure of GIMBAL bearing in directional GYRO

International Nuclear Information System (INIS)

Pervaiz, R.; Baig, N.A.; Shahid, M.; Ahmad, A.; Chohan, G.Y.

2003-01-01

This paper relates to the directional gyro of a sensing device used in indigenously developed surface-to-surface missile. The assembling of more than one thousand components in the form of several sub assemblies including hundreds of silver solders of this device was done in the hundred-thousands-class clean room according to assembly procedure. Whereas more than twenty bearings including gimbals bearings were assembled in the ten-thousands-class clean room after inspection/ testing them on beating testing system as per routine. The device was entered in testing and adjustment phase after successful completion of assembly work. The directional gyro qualified all the tests except the most critical one, the drift-rate. The drift-rate of outer gimbal was 60% more than permissible limit whereas drift-rate of inner gimbal was found O.K. It was diagnosed that at least one inner gimbal bearing out of two had some problem. The results were same after rebalancing of gimbals three times. The directional gyro was disassembled in clean room and the radial-thrust-bearing was recovered and flange bearing which are inner gimbal bearings. They were checked on bearing testing system and it was found that flange-bearing had more friction than permissible limit and hence rejected but radial thrust bearing were declared O.K. The gyro was reassembled with new O.K. flange bearing and the assembly work was completed in all respects. The sensing device qualified all the tests including the drift-rate. This case study is being presented to emphasize the importance of careful assembly of gyro in clean environment. (author)

Distinguishing thrust sequences in gravity-driven fold and thrust belts

Science.gov (United States)

Alsop, G. I.; Weinberger, R.; Marco, S.

2018-04-01

Piggyback or foreland-propagating thrust sequences, where younger thrusts develop in the footwalls of existing thrusts, are generally assumed to be the typical order of thrust development in most orogenic settings. However, overstep or 'break-back' sequences, where later thrusts develop above and in the hangingwalls of earlier thrusts, may potentially form during cessation of movement in gravity-driven mass transport deposits (MTDs). In this study, we provide a detailed outcrop-based analysis of such an overstep thrust sequence developed in an MTD in the southern Dead Sea Basin. Evidence that may be used to discriminate overstep thrusting from piggyback thrust sequences within the gravity-driven fold and thrust belt includes upright folds and forethrusts that are cut by younger overlying thrusts. Backthrusts form ideal markers that are also clearly offset and cut by overlying younger forethrusts. Portions of the basal detachment to the thrust system are folded and locally imbricated in footwall synclines below forethrust ramps, and these geometries also support an overstep sequence. However, new 'short-cut' basal detachments develop below these synclines, indicating that movement continued on the basal detachment rather than it being abandoned as in classic overstep sequences. Further evidence for 'synchronous thrusting', where movement on more than one thrust occurs at the same time, is provided by displacement patterns on sequences of thrust ramp imbricates that systematically increases downslope towards the toe of the MTD. Older thrusts that initiate downslope in the broadly overstep sequence continue to move and therefore accrue greater displacements during synchronous thrusting. Our study provides a template to help distinguish different thrust sequences in both orogenic settings and gravity-driven surficial systems, with displacement patterns potentially being imaged in seismic sections across offshore MTDs.

Bifurcation and nonlinear dynamic analysis of a flexible rotor supported by relative short gas journal bearings

International Nuclear Information System (INIS)

Wang, C.-C.; Jang, M.-J.; Yeh, Y.-L.

2007-01-01

This paper studies the bifurcation and nonlinear behaviors of a flexible rotor supported by relative short gas film bearings. A time-dependent mathematical model for gas journal bearings is presented. The finite difference method with successive over relation method is employed to solve the Reynolds' equation. The system state trajectory, Poincare maps, power spectra, and bifurcation diagrams are used to analyze the dynamic behavior of the rotor and journal center in the horizontal and vertical directions under different operating conditions. The analysis reveals a complex dynamic behavior comprising periodic and subharmonic response of the rotor and journal center. This paper shows how the dynamic behavior of this type of system varies with changes in rotor mass and rotational velocity. The results of this study contribute to a further understanding of the nonlinear dynamics of gas film rotor-bearing systems

An effective medium inversion algorithm for gas hydrate quantification and its application to laboratory and borehole measurements of gas hydrate-bearing sediments

Science.gov (United States)

Chand, S.; Minshull, T.A.; Priest, J.A.; Best, A.I.; Clayton, C.R.I.; Waite, W.F.

2006-01-01

The presence of gas hydrate in marine sediments alters their physical properties. In some circumstances, gas hydrate may cement sediment grains together and dramatically increase the seismic P- and S-wave velocities of the composite medium. Hydrate may also form a load-bearing structure within the sediment microstructure, but with different seismic wave attenuation characteristics, changing the attenuation behaviour of the composite. Here we introduce an inversion algorithm based on effective medium modelling to infer hydrate saturations from velocity and attenuation measurements on hydrate-bearing sediments. The velocity increase is modelled as extra binding developed by gas hydrate that strengthens the sediment microstructure. The attenuation increase is modelled through a difference in fluid flow properties caused by different permeabilities in the sediment and hydrate microstructures. We relate velocity and attenuation increases in hydrate-bearing sediments to their hydrate content, using an effective medium inversion algorithm based on the self-consistent approximation (SCA), differential effective medium (DEM) theory, and Biot and squirt flow mechanisms of fluid flow. The inversion algorithm is able to convert observations in compressional and shear wave velocities and attenuations to hydrate saturation in the sediment pore space. We applied our algorithm to a data set from the Mallik 2L–38 well, Mackenzie delta, Canada, and to data from laboratory measurements on gas-rich and water-saturated sand samples. Predictions using our algorithm match the borehole data and water-saturated laboratory data if the proportion of hydrate contributing to the load-bearing structure increases with hydrate saturation. The predictions match the gas-rich laboratory data if that proportion decreases with hydrate saturation. We attribute this difference to differences in hydrate formation mechanisms between the two environments.

Aqueous process for recovering sulfur from hydrogen sulfide-bearing gas

Science.gov (United States)

Basu, Arunabha

2015-05-05

A process for recovering sulfur from a hydrogen sulfide-bearing gas utilizes an aqueous reaction medium, a temperature of about 110-150.degree. C., and a high enough pressure to maintain the aqueous reaction medium in a liquid state. The process reduces material and equipment costs and addresses the environmental disadvantages associated with known processes that rely on high boiling point organic solvents.

FIRST OPERATING RESULTS OF A DYNAMIC GAS BEARING TURBINE IN AN INDUSTRIAL HYDROGEN LIQUEFIER

International Nuclear Information System (INIS)

Bischoff, S.; Decker, L.

2010-01-01

Hydrogen has been brought into focus of industry and public since fossil fuels are depleting and costs are increasing dramatically. Beside these issues new high-tech processes in the industry are in need for hydrogen at ultra pure quality. To achieve these requirements and for efficient transportation, hydrogen is liquefied in industrial plants. Linde Gas has commissioned a new 5.5 TPD Hydrogen liquefier in Leuna, Germany, which has been engineered and supplied by Linde Kryotechnik. One of the four expansion turbines installed in the liquefaction process is equipped with dynamic gas bearings. Several design features and operational characteristics of this application will be discussed. The presentation will include results of efficiency and operational reliability that have been determined from performance tests. The advantages of the Linde dynamic gas bearing turbine for future use in hydrogen liquefaction plants will be shown.

Fast discharging homopolar drum-type generator with gas bearing and flexible copper-fiber brushes

International Nuclear Information System (INIS)

Kibardin, A.S.; Komin, A.V.; Sojkin, V.F.; Frolkin, V.I.

1984-01-01

The description and results of testing schock-excited homopolar generator (SEHG) with a drum-type rotor, a gas bearing and flexible copper-fiber brushes are presented. SEHG has a magnetic core with two excitation coils with the designed field of 1.8-2 T in the gap. The drum-type titanium rotor has 80 kg, is 0.5 m in diameter, 0.25 m length and 0.05 m thick. SEHG power is 3.6 MJ, overall dimensions are 0.8x1 m. Single- and double-row bearings, representing an aluminium shell of 15 mm thick, established inside an external backward current lead and isolated from it, are used to control serviceability of a radial gas-static bearing, which is a support for an SEHG rotor. The bearing surface was covered with the colloidal graphite and had one or two rows by 24 openings for swelling. Brush units represent a bronze brush ring, containing 44 copper-fiber brushes. Tests results confirm serviceability of copper-fiber brushes with quite large dimensions and permit to count on producing the 2.4 MA electric discharge and 12 ms pulse rise time

Rotating head for air, gas and mud drilling

Energy Technology Data Exchange (ETDEWEB)

Pruitt, A.B.

1983-05-17

A rotating head assembly having roller thrust bearings rotatably journaling an inner barrel is provided with pump means for continuous forced circulation of lubricating oil to, and around, the thrust bearings during operation. A lubricating oil chamber substantially surrounds the bearings, which chamber is effectively sealed against leakage of oil fluids, and other debris, into the chamber and lubricating oil out of the chamber. The lower end of the rotatably journaled inner barrel is provided with a stripper rubber structured to enable use of the head with drill pipe of diverse outer diameters.

A 10 nN resolution thrust-stand for micro-propulsion devices

Energy Technology Data Exchange (ETDEWEB)

Chakraborty, Subha; Courtney, Daniel G.; Shea, Herbert, E-mail: herbert.shea@epfl.ch [Microsystems for Space Technologies Laboratory (LMTS), Ecole Polytechnique Federale de Lausanne (EPFL), Neuchatel (Switzerland)

2015-11-15

We report on the development of a nano-Newton thrust-stand that can measure up to 100 μN thrust from different types of microthrusters with 10 nN resolution. The compact thrust-stand measures the impingement force of the particles emitted from a microthruster onto a suspended plate of size 45 mm × 45 mm and with a natural frequency over 50 Hz. Using a homodyne (lock-in) readout provides strong immunity to facility vibrations, which historically has been a major challenge for nano-Newton thrust-stands. A cold-gas thruster generating up to 50 μN thrust in air was first used to validate the thrust-stand. Better than 10 nN resolution and a minimum detectable thrust of 10 nN were achieved. Thrust from a miniature electrospray propulsion system generating up to 3 μN of thrust was measured with our thrust-stand in vacuum, and the thrust was compared with that computed from beam diagnostics, obtaining agreement within 50 nN to 150 nN. The 10 nN resolution obtained from this thrust-stand matches that from state-of-the-art nano-Newton thrust-stands, which measure thrust directly from the thruster by mounting it on a moving arm (but whose natural frequency is well below 1 Hz). The thrust-stand is the first of its kind to demonstrate less than 3 μN resolution by measuring the impingement force, making it capable of measuring thrust from different types of microthrusters, with the potential of easy upscaling for thrust measurement at much higher levels, simply by replacing the force sensor with other force sensors.

Space shuttle orbit maneuvering engine reusable thrust chamber program

Science.gov (United States)

Senneff, J. M.

1975-01-01

Reusable thrust chamber and injector concepts were evaluated for the space shuttle orbit maneuvering engine (OME). Parametric engine calculations were carried out by computer program for N2O4/amine, LOX/amine and LOX/hydrocarbon propellant combinations for engines incorporating regenerative cooled and insulated columbium thrust chambers. The calculation methods are described including the fuel vortex film cooling method of combustion gas temperature control, and performance prediction. A method of acceptance of a regeneratively cooled heat rejection reduction using a silicone oil additive was also demonstrated by heated tube heat transfer testing. Regeneratively cooled thrust chamber operation was also demonstrated where the injector was characterized for the OME application with a channel wall regenerative thrust chamber. Bomb stability testing of the demonstration chambers/injectors demonstrated recovery for the nominal design of acoustic cavities. Cavity geometry changes were also evaluated to assess their damping margin. Performance and combustion stability was demonstrated of the originally developed 10 inch diameter combustion pattern operating in an 8 inch diameter thrust chamber.

Robust control for constant thrust rendezvous under thrust failure

Directory of Open Access Journals (Sweden)

Qi Yongqiang

2015-04-01

Full Text Available A robust constant thrust rendezvous approach under thrust failure is proposed based on the relative motion dynamic model. Firstly, the design problem is cast into a convex optimization problem by introducing a Lyapunov function subject to linear matrix inequalities. Secondly, the robust controllers satisfying the requirements can be designed by solving this optimization problem. Then, a new algorithm of constant thrust fitting is proposed through the impulse compensation and the fuel consumption under the theoretical continuous thrust and the actual constant thrust is calculated and compared by using the method proposed in this paper. Finally, the proposed method having the advantage of saving fuel is proved and the actual constant thrust switch control laws are obtained through the isochronous interpolation method, meanwhile, an illustrative example is provided to show the effectiveness of the proposed control design method.

Effects of Attenuation of Gas Hydrate-bearing Sediments on Seismic Data: Example from Mallik, Northwest Territories, Canada

Science.gov (United States)

Bellefleur, G.; Riedel, M.; Brent, T.

2007-05-01

Wave attenuation is an important physical property of hydrate-bearing sediments that is rarely taken into account in site characterization with seismic data. We present a field example showing improved images of hydrate- bearing sediments on seismic data after compensation of attenuation effects. Compressional quality factors (Q) are estimated from zero-offset Vertical Seismic Profiling data acquired at Mallik, Northwest Territories, Canada. During the last 10 years, two internationally-partnered research drilling programs have intersected three major intervals of sub-permafrost gas hydrates at Mallik, and have successfully extracted core samples containing significant amount of gas hydrates. Individual gas hydrate intervals are up to 40m in thickness and are characterized by high in situ gas hydrate saturation, sometimes exceeding 80% of pore volume of unconsolidated clastic sediments having average porosities ranging from 25% to 40%. The Q-factors obtained from the VSP data demonstrate significant wave attenuation for permafrost and hydrate- bearing sediments. These results are in agreement with previous attenuation estimates from sonic logs and crosshole data at different frequency intervals. The Q-factors obtained from VSP data were used to compensate attenuation effects on surface 3D seismic data acquired over the Mallik gas hydrate research wells. Intervals of gas hydrate on surface seismic data are characterized by strong reflectivity and effects from attenuation are not perceptible from a simple visual inspection of the data. However, the application of an inverse Q-filter increases the resolution of the data and improves correlation with log data, particularly for the shallowest gas hydrate interval. Compensation of the attenuation effects of the permafrost likely explains most of the improvements for the shallow gas hydrate zone. Our results show that characterization of the Mallik gas hydrates with seismic data not corrected for attenuation would tend to

WAVELET-BASED ALGORITHM FOR DETECTION OF BEARING FAULTS IN A GAS TURBINE ENGINE

Directory of Open Access Journals (Sweden)

Sergiy Enchev

2014-07-01

Full Text Available Presented is a gas turbine engine bearing diagnostic system that integrates information from various advanced vibration analysis techniques to achieve robust bearing health state awareness. This paper presents a computational algorithm for identifying power frequency variations and integer harmonics by using wavelet-based transform. The continuous wavelet transform with  the complex Morlet wavelet is adopted to detect the harmonics presented in a power signal. The algorithm based on the discrete stationary wavelet transform is adopted to denoise the wavelet ridges.

Comparison of Models for the Steady-State Analysis of Tilting-Pad Thrust Bearings

DEFF Research Database (Denmark)

Heinrichson, Niels; Santos, Ilmar

2005-01-01

Prediction of the minimum oil film thickness and the maximum temperature on the surface of the bearing pad is crucial in the design and dimensioning of bearings. Friction loss, oil bath temperature and pad deflection are other parameters of interest. Depending on the desired information a numerical...... for the groove between pads and the oil bath temperature from energy equilibrium for the entire bearing. The main theoretical contribution of this paper is the elaboration and comparison of 7 different mathematical models of increasing complexity. The results are compared to experimental data for steady......-state operation of a 228 mm outer diameter bearing. It is found that for the given bearing a two dimensional model is sufficient to estimate the minimum oil film thickness and the maximum temperature on the pad surface. Three dimensional modelling does not improve the quality of the results....

Development of superconducting magnetic bearing using superconducting coil and bulk superconductor

Energy Technology Data Exchange (ETDEWEB)

Seino, H; Nagashima, K; Arai, Y [Railway Technical Research Institute, Hikari-cho 2-8-38, Kokubunji-shi, Tokyo (Japan)], E-mail: seino@rtri.or.jp

2008-02-01

The authors conducted a study on superconducting magnetic bearing, which consists of superconducting rotor and stator to apply the flywheel energy-storage system for railways. In this study, high temperature bulk superconductor (HTS bulk) was combined with superconducting coils to increase the load capacity of the bearing. In the first step of the study, the thrust rolling bearing was selected for application by using liquid nitrogen cooled HTS bulk. 60mm-diameter HTS bulks and superconducting coil which generated a high gradient of magnetic field by cusp field were adopted as a rotor and a stator for superconducting magnetic bearing, respectively. The results of the static load test and the rotation test, creep of the electromagnetic forces caused by static flux penetration and AC loss due to eccentric rotation were decreased to the level without any problems in substantial use by using two HTS bulks. In the result of verification of static load capacity, levitation force (thrust load) of 8900N or more was supportable, and stable static load capacity was obtainable when weight of 460kg was levitated.

Development of superconducting magnetic bearing using superconducting coil and bulk superconductor

International Nuclear Information System (INIS)

Seino, H; Nagashima, K; Arai, Y

2008-01-01

The authors conducted a study on superconducting magnetic bearing, which consists of superconducting rotor and stator to apply the flywheel energy-storage system for railways. In this study, high temperature bulk superconductor (HTS bulk) was combined with superconducting coils to increase the load capacity of the bearing. In the first step of the study, the thrust rolling bearing was selected for application by using liquid nitrogen cooled HTS bulk. 60mm-diameter HTS bulks and superconducting coil which generated a high gradient of magnetic field by cusp field were adopted as a rotor and a stator for superconducting magnetic bearing, respectively. The results of the static load test and the rotation test, creep of the electromagnetic forces caused by static flux penetration and AC loss due to eccentric rotation were decreased to the level without any problems in substantial use by using two HTS bulks. In the result of verification of static load capacity, levitation force (thrust load) of 8900N or more was supportable, and stable static load capacity was obtainable when weight of 460kg was levitated

Thrust Vectoring of a Continuous Rotating Detonation Engine by Changing the Local Injection Pressure

International Nuclear Information System (INIS)

Liu Shi-Jie; Lin Zhi-Yong; Sun Ming-Bo; Liu Wei-Dong

2011-01-01

The thrust vectoring ability of a continuous rotating detonation engine is numerically investigated, which is realized via increasing local injection stagnation pressure of half of the simulation domain compared to the other half. Under the homogeneous injection condition, both the flow-field structure and the detonation wave propagation process are analyzed. Due to the same injection condition along the inlet boundary, the outlines of fresh gas zones at different moments are similar to each other. The main flow-field features under thrust vectoring cases are similar to that under the baseline condition. However, due to the heterogeneous injection system, both the height of the fresh gas zone and the pressure value of the fresh gas in the high injection pressure zone are larger than that in the low injection pressure zone. Thus the average pressure in half of the engine is larger than that in the other half and the thrust vectoring adjustment is realized. (fundamental areas of phenomenology(including applications))

Hydrate bearing clayey sediments: Formation and gas production concepts

KAUST Repository

Jang, Jaewon; Santamarina, Carlos

2016-01-01

Hydro-thermo-chemo and mechanically coupled processes determine hydrate morphology and control gas production from hydrate-bearing sediments. Force balance, together with mass and energy conservation analyses anchored in published data provide robust asymptotic solutions that reflect governing processes in hydrate systems. Results demonstrate that hydrate segregation in clayey sediments results in a two-material system whereby hydrate lenses are surrounded by hydrate-free water-saturated clay. Hydrate saturation can reach ≈2% by concentrating the excess dissolved gas in the pore water and ≈20% from metabolizable carbon. Higher hydrate saturations are often found in natural sediments and imply methane transport by advection or diffusion processes. Hydrate dissociation is a strongly endothermic event; the available latent heat in a reservoir can sustain significant hydrate dissociation without triggering ice formation during depressurization. The volume of hydrate expands 2-to-4 times upon dissociation or CO2single bondCH4 replacement. Volume expansion can be controlled to maintain lenses open and to create new open mode discontinuities that favor gas recovery. Pore size is the most critical sediment parameter for hydrate formation and gas recovery and is controlled by the smallest grains in a sediment. Therefore any characterization must carefully consider the amount of fines and their associated mineralogy.

Hydrate bearing clayey sediments: Formation and gas production concepts

KAUST Repository

Jang, Jaewon

2016-06-20

Hydro-thermo-chemo and mechanically coupled processes determine hydrate morphology and control gas production from hydrate-bearing sediments. Force balance, together with mass and energy conservation analyses anchored in published data provide robust asymptotic solutions that reflect governing processes in hydrate systems. Results demonstrate that hydrate segregation in clayey sediments results in a two-material system whereby hydrate lenses are surrounded by hydrate-free water-saturated clay. Hydrate saturation can reach ≈2% by concentrating the excess dissolved gas in the pore water and ≈20% from metabolizable carbon. Higher hydrate saturations are often found in natural sediments and imply methane transport by advection or diffusion processes. Hydrate dissociation is a strongly endothermic event; the available latent heat in a reservoir can sustain significant hydrate dissociation without triggering ice formation during depressurization. The volume of hydrate expands 2-to-4 times upon dissociation or CO2single bondCH4 replacement. Volume expansion can be controlled to maintain lenses open and to create new open mode discontinuities that favor gas recovery. Pore size is the most critical sediment parameter for hydrate formation and gas recovery and is controlled by the smallest grains in a sediment. Therefore any characterization must carefully consider the amount of fines and their associated mineralogy.

The R and D D`s bearing test benches; Les bancs d`essais de paliers de la DER

Energy Technology Data Exchange (ETDEWEB)

Vialettes, J.M. [Service Ensembles de Production, Departement Machines, Direction des Etudes et Recherches, Electricite de France (EDF), 92 - Clamart (France)

1997-01-01

In power generation plants, rotating machines are involved in energy transformation processes and safety systems. The bearings supporting the rotors and the thrust bearings play a crucial role in the reliability of these machines. The phenomena encountered straddle several disciplines: hydrodynamics, tribology, thermomechanics, materials and vibrations in a specific environment, namely: thin fluid film, solid mechanical components and shaft rotation. Means of analysing the behaviour of these components (bearings and thrust bearings) have been developed and implemented. These consists of the EDYOS (Etude Dynamique des Organes de Supportage) code for dynamically studying bearing devices and several related bench tests. In reality, in order to understand the complex physical phenomena encountered in these components, it is vital to carry out analyses and experimental validations. Since these investigations cannot be carried out on actual machines, test benches have been built which can subject the sample bearings to the equivalent stresses. (author) 14 figs.

A six degree-of-freedom thrust sensor for a labscale hybrid rocket

Science.gov (United States)

Wright, Ann M.; Wright, Andrew B.; Born, Traig; Strickland, Ryan

2013-12-01

A six degree-of-freedom thrust sensor was designed, constructed, calibrated, and tested using the labscale hybrid rocket at the University of Arkansas at Little Rock. The system consisted of six independent legs: one parallel to the axis of symmetry of the rocket for main thrust measurement, two vertical legs near the nozzle end of the rocket, one vertical leg near the oxygen input end of the rocket, and two separated horizontal legs near the nozzle end. Each leg was composed of a rotational bearing, a load cell, and a universal joint above and below the load cell. The leg was designed to create point contact along only one direction and minimize the non-axial forces applied to the load cell. With this system, force in each direction and moments for roll, pitch, and yaw can be measured. The system was calibrated and tested using a labscale hybrid rocket using gaseous oxygen and hydroxyl-terminated polybutadiene solid fuel. The thrust stand proved to be stable during calibration tests. Thrust force vector components and roll, pitch, and yaw moments were calculated for test firings with an oxygen mass flow rate range of 0.0174-0.0348 kg s-1.

Lateral vibration control of a flexible overcritical rotor via an active gas bearing – Theoretical and experimental comparisons

DEFF Research Database (Denmark)

Pierart Vásquez, Fabián Gonzalo; Santos, Ilmar

2016-01-01

The lack of damping of radial gas bearings leads to high vibration levels of a rotor supported by this type of bearing when crossing resonant areas. This is even more relevant for flexible rotors, as studied in this work. In order to reduce these high vibration levels, an active gas bearing...... is proposed. The control action of this active bearing is selected based on two different strategies: a simple proportional integral derivative controller and an optimal controller. Both controllers are designed based on a theoretical model previously presented. The dynamics of the flexible rotor are modelled......-based controllers are compared against experimental results, showing good agreement. Theoretical and experimental results show a significant increase in the damping ratio of the system, enabling the flexible rotor to run safely across the critical speeds and up to 12,000rev/min, i.e. 50 percent over the second...

Emission of soil gas radon concentration around main central thrust in Ukhimath (Rudraprayag) region of Garhwal Himalaya

International Nuclear Information System (INIS)

Aswal, Sunita; Kandari, Tushar; Bourai, A.A.; Ramola, R.C.; Sahoo, B.K.

2016-01-01

In this paper, the result of systematic measurement of the soil gas radon concentrations is discussed and the background values are defined along and around the Main Central Thrust (MCT) in Ukhimath region of Garhwal Himalaya, India. The Ukhimath region is being subjected to intense neotectonic activities like earthquake and landslide. For the systematic study, the measurement has been done in grid pattern form along and across the MCT. The soil gas radon concentrations were measured using RAD7 with appropriate accessories and followed proper protocol proposed by the manufacturer. The soil gas concentration was measured at different depths 10, 30 and 50 cm with a wide range of different points from the MCT. At 10 cm depth, the soil gas radon concentration was found to vary from 125 to 800 Bq m -3 with an average of 433 Bq m -3 ; at 30 cm, it was found to vary from 203 to 32 500 Bq m -3 with an average of 2387 Bq m -3 ; and at 50 cm, it was found to vary from 1330 to 46 000 Bq m -3 with an average of 15 357 Bq m -3 . The data analysis clearly reveals anomalous values along the fault. (authors)

A constitutive mechanical model for gas hydrate bearing sediments incorporating inelastic mechanisms

KAUST Repository

Sánchez, Marcelo

2016-11-30

Gas hydrate bearing sediments (HBS) are natural soils formed in permafrost and sub-marine settings where the temperature and pressure conditions are such that gas hydrates are stable. If these conditions shift from the hydrate stability zone, hydrates dissociate and move from the solid to the gas phase. Hydrate dissociation is accompanied by significant changes in sediment structure and strongly affects its mechanical behavior (e.g., sediment stiffenss, strength and dilatancy). The mechanical behavior of HBS is very complex and its modeling poses great challenges. This paper presents a new geomechanical model for hydrate bearing sediments. The model incorporates the concept of partition stress, plus a number of inelastic mechanisms proposed to capture the complex behavior of this type of soil. This constitutive model is especially well suited to simulate the behavior of HBS upon dissociation. The model was applied and validated against experimental data from triaxial and oedometric tests conducted on manufactured and natural specimens involving different hydrate saturation, hydrate morphology, and confinement conditions. Particular attention was paid to model the HBS behavior during hydrate dissociation under loading. The model performance was highly satisfactory in all the cases studied. It managed to properly capture the main features of HBS mechanical behavior and it also assisted to interpret the behavior of this type of sediment under different loading and hydrate conditions.

High-resolution well-log derived dielectric properties of gas-hydrate-bearing sediments, Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope

Science.gov (United States)

Sun, Y.; Goldberg, D.; Collett, T.; Hunter, R.

2011-01-01

A dielectric logging tool, electromagnetic propagation tool (EPT), was deployed in 2007 in the BPXA-DOE-USGS Mount Elbert Gas Hydrate Stratigraphic Test Well (Mount Elbert Well), North Slope, Alaska. The measured dielectric properties in the Mount Elbert well, combined with density log measurements, result in a vertical high-resolution (cm-scale) estimate of gas hydrate saturation. Two hydrate-bearing sand reservoirs about 20 m thick were identified using the EPT log and exhibited gas-hydrate saturation estimates ranging from 45% to 85%. In hydrate-bearing zones where variation of hole size and oil-based mud invasion are minimal, EPT-based gas hydrate saturation estimates on average agree well with lower vertical resolution estimates from the nuclear magnetic resonance logs; however, saturation and porosity estimates based on EPT logs are not reliable in intervals with substantial variations in borehole diameter and oil-based invasion.EPT log interpretation reveals many thin-bedded layers at various depths, both above and below the thick continuous hydrate occurrences, which range from 30-cm to about 1-m thick. Such thin layers are not indicated in other well logs, or from the visual observation of core, with the exception of the image log recorded by the oil-base microimager. We also observe that EPT dielectric measurements can be used to accurately detect fine-scale changes in lithology and pore fluid properties of hydrate-bearing sediments where variation of hole size is minimal. EPT measurements may thus provide high-resolution in-situ hydrate saturation estimates for comparison and calibration with laboratory analysis. ?? 2010 Elsevier Ltd.

Shaping low-thrust trajectories with thrust-handling feature

Science.gov (United States)

Taheri, Ehsan; Kolmanovsky, Ilya; Atkins, Ella

2018-02-01

Shape-based methods are becoming popular in low-thrust trajectory optimization due to their fast computation speeds. In existing shape-based methods constraints are treated at the acceleration level but not at the thrust level. These two constraint types are not equivalent since spacecraft mass decreases over time as fuel is expended. This paper develops a shape-based method based on a Fourier series approximation that is capable of representing trajectories defined in spherical coordinates and that enforces thrust constraints. An objective function can be incorporated to minimize overall mission cost, i.e., achieve minimum ΔV . A representative mission from Earth to Mars is studied. The proposed Fourier series technique is demonstrated capable of generating feasible and near-optimal trajectories. These attributes can facilitate future low-thrust mission designs where different trajectory alternatives must be rapidly constructed and evaluated.

Thrust and torque characteristics based on a new cutter-head load model

Science.gov (United States)

Liu, Jianqin; Ren, Jiabao; Guo, Wei

2015-07-01

Full face rock tunnel boring machine(TBM) has been widely used in hard rock tunnels, however, there are few published theory about cutter-head design, and the design criteria of cutter-head under complex geological is not clear yet. To deal with the complex relationship among geological parameters, cutter parameters, and operating parameters during tunneling processes, a cutter-head load model is established by using CSM(Colorado school of mines) prediction model. Force distribution on cutter-head under a certain geology is calculated with the new established load model, and result shows that inner cutters bear more force than outer cutters, combining with disc cutters abrasion; a general principle of disc cutters' layout design is proposed. Within the model, the relationship among rock uniaxial compressive strength(UCS), penetration and thrust on cutter-head are analyzed, and the results shows that with increasing penetration, cutter thrust increases, but the growth rate slows and higher penetration makes lower special energy(SE). Finally, a fitting mathematical model of ZT(ratio of cutter-head torque and thrust) and penetration is established, and verified by TB880E, which can be used to direct how to set thrust and torque on cutter-head. When penetration is small, the cutter-head thrust is the main limiting factor in tunneling; when the penetration is large, cutter-head torque is the major limiting factor in tunneling. Based on the new cutter-head load model, thrust and torque characteristics of TBM further are researched and a new way for cutter-head layout design and TBM tunneling operations is proposed.

Greenhouse gas mitigation can reduce sea-ice loss and increase polar bear persistence

Science.gov (United States)

Steven C. Amstrup; Eric T. DeWeaver; David C. Douglas; Bruce G. Marcot; George M. Durner; Cecilia M. Bitz; David A. Bailey

2010-01-01

On the basis of projected losses of their essential sea-ice habitats, a United States Geological Survey research team concluded in 2007 that two-thirds of the world's polar bears (Ursus maritimus) could disappear by mid-century if business-as-usual greenhouse gas emissions continue. That projection, however, did not consider the possible...

Gas Migration Processes through the Gas Hydrate Stability Zone at Four-Way Closure Ridge Offshore SW Taiwan

Science.gov (United States)

Kunath, P.; Chi, W. C.; Berndt, C.; Liu, C. S.

2016-12-01

We have used 3D P-Cable seismic data from Four-Way-Closure Ridge, a NW-SE trending anticlinal ridge within the lower slope domain of accretionary wedge, to investigate the geological constraints influencing the fluid migration pattern in the shallow marine sediments. In the seismic data, fluid migration feature manifests itself as high reflection layers of dipping strata, which originate underneath a bottom simulating reflector (BSR) and extend towards the seafloor. Shoaling of the BSR near fluid migration pathways indicates a focused fluid flux, perturbing the temperature field. Furthermore, seafloor video footage confirmed the presence of recent methane seepage above seismically imaged fluid migration pathways. We plan to test two hypotheses for the occurrence of these fluid migration pathways: 1) the extensional regime under the anticlinal ridge crest caused the initiation of localized fault zones, acting as fluid conduits in the gas hydrate stability zone (GHSZ). 2) sediment deformation induced by focused fluid flow and massive growth and dissolution of gas hydrate, similar to processes controlling the evolution of pockmarks on the Nigerian continental margin. We suggest that these processes may be responsible for the formation of a massive hydrate core in the crest of the anticline, as inferred from other geophysical datasets. Triggering process for fluid migration cannot be clearly defined. However, the existence of blind thrust faults may help to advect deep-seated fluids. This may be augmented by biogenic production of shallow gas underneath the ridge, where the excess of gas enables the coexistence of gas, water, and gas hydrate within the GHSZ. Fluid migration structures may exists because of the buoyancy of gas-bearing fluids. This study shows a potential model on how gas-bearing fluids migrate upward towards structural highs, which might occur in other anticlinal structures around the world. Keywords: P-Cable, gas-hydrate, fluid flow, fault-related fold

Dielectric Barrier Discharge (DBD) Plasma Actuators Thrust-Measurement Methodology Incorporating New Anti-Thrust Hypothesis

Science.gov (United States)

Ashpis, David E.; Laun, Matthew C.

2014-01-01

We discuss thrust measurements of Dielectric Barrier Discharge (DBD) plasma actuators devices used for aerodynamic active flow control. After a review of our experience with conventional thrust measurement and significant non-repeatability of the results, we devised a suspended actuator test setup, and now present a methodology of thrust measurements with decreased uncertainty. The methodology consists of frequency scans at constant voltages. The procedure consists of increasing the frequency in a step-wise fashion from several Hz to the maximum frequency of several kHz, followed by frequency decrease back down to the start frequency of several Hz. This sequence is performed first at the highest voltage of interest, then repeated at lower voltages. The data in the descending frequency direction is more consistent and selected for reporting. Sample results show strong dependence of thrust on humidity which also affects the consistency and fluctuations of the measurements. We also observed negative values of thrust or "anti-thrust", at low frequencies between 4 Hz and up to 64 Hz. The anti-thrust is proportional to the mean-squared voltage and is frequency independent. Departures from the parabolic anti-thrust curve are correlated with appearance of visible plasma discharges. We propose the anti-thrust hypothesis. It states that the measured thrust is a sum of plasma thrust and anti-thrust, and assumes that the anti-thrust exists at all frequencies and voltages. The anti-thrust depends on actuator geometry and materials and on the test installation. It enables the separation of the plasma thrust from the measured total thrust. This approach enables more meaningful comparisons between actuators at different installations and laboratories. The dependence on test installation was validated by surrounding the actuator with a large diameter, grounded, metal sleeve.

EMISSION OF SOIL GAS RADON CONCENTRATION AROUND MAIN CENTRAL THRUST IN UKHIMATH (RUDRAPRAYAG) REGION OF GARHWAL HIMALAYA.

Science.gov (United States)

Aswal, Sunita; Kandari, Tushar; Sahoo, B K; Bourai, A A; Ramola, R C

2016-10-01

In this paper, the result of systematic measurement of the soil gas radon concentrations is discussed and the background values are defined along and around the Main Central Thrust (MCT) in Ukhimath region of Garhwal Himalaya, India. The Ukhimath region is being subjected to intense neotectonic activities like earthquake and landslide. For the systematic study, the measurement has been done in grid pattern form along and across the MCT. The soil gas radon concentrations were measured using RAD7 with appropriate accessories and followed proper protocol proposed by the manufacturer. The soil gas concentration was measured at different depths 10, 30 and 50 cm with a wide range of different points from the MCT. At 10 cm depth, the soil gas radon concentration was found to vary from 125 to 800 Bq m -3 with an average of 433 Bq m -3 ; at 30 cm, it was found to vary from 203 to 32 500 Bq m -3 with an average of 2387 Bq m -3 ; and at 50 cm, it was found to vary from 1330 to 46 000 Bq m -3 with an average of 15 357 Bq m -3 The data analysis clearly reveals anomalous values along the fault. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Grain-scale imaging and compositional characterization of cryo-preserved India NGHP 01 gas-hydrate-bearing cores

Science.gov (United States)

Stern, Laura A.; Lorenson, T.D.

2014-01-01

We report on grain-scale characteristics and gas analyses of gas-hydrate-bearing samples retrieved by NGHP Expedition 01 as part of a large-scale effort to study gas hydrate occurrences off the eastern-Indian Peninsula and along the Andaman convergent margin. Using cryogenic scanning electron microscopy, X-ray spectroscopy, and gas chromatography, we investigated gas hydrate grain morphology and distribution within sediments, gas hydrate composition, and methane isotopic composition of samples from Krishna–Godavari (KG) basin and Andaman back-arc basin borehole sites from depths ranging 26 to 525 mbsf. Gas hydrate in KG-basin samples commonly occurs as nodules or coarse veins with typical hydrate grain size of 30–80 μm, as small pods or thin veins 50 to several hundred microns in width, or disseminated in sediment. Nodules contain abundant and commonly isolated macropores, in some places suggesting the original presence of a free gas phase. Gas hydrate also occurs as faceted crystals lining the interiors of cavities. While these vug-like structures constitute a relatively minor mode of gas hydrate occurrence, they were observed in near-seafloor KG-basin samples as well as in those of deeper origin (>100 mbsf) and may be original formation features. Other samples exhibit gas hydrate grains rimmed by NaCl-bearing material, presumably produced by salt exclusion during original hydrate formation. Well-preserved microfossil and other biogenic detritus are also found within several samples, most abundantly in Andaman core material where gas hydrate fills microfossil crevices. The range of gas hydrate modes of occurrence observed in the full suite of samples suggests a range of formation processes were involved, as influenced by local in situconditions. The hydrate-forming gas is predominantly methane with trace quantities of higher molecular weight hydrocarbons of primarily microbial origin. The composition indicates the gas hydrate is Structure I.

A six degree-of-freedom thrust sensor for a labscale hybrid rocket

International Nuclear Information System (INIS)

Wright, Ann M; Born, Traig; Strickland, Ryan; Wright, Andrew B

2013-01-01

A six degree-of-freedom thrust sensor was designed, constructed, calibrated, and tested using the labscale hybrid rocket at the University of Arkansas at Little Rock. The system consisted of six independent legs: one parallel to the axis of symmetry of the rocket for main thrust measurement, two vertical legs near the nozzle end of the rocket, one vertical leg near the oxygen input end of the rocket, and two separated horizontal legs near the nozzle end. Each leg was composed of a rotational bearing, a load cell, and a universal joint above and below the load cell. The leg was designed to create point contact along only one direction and minimize the non-axial forces applied to the load cell. With this system, force in each direction and moments for roll, pitch, and yaw can be measured. The system was calibrated and tested using a labscale hybrid rocket using gaseous oxygen and hydroxyl-terminated polybutadiene solid fuel. The thrust stand proved to be stable during calibration tests. Thrust force vector components and roll, pitch, and yaw moments were calculated for test firings with an oxygen mass flow rate range of 0.0174–0.0348 kg s −1 . (paper)

Sedimentological Properties of Natural Gas Hydrates-Bearing Sands in the Nankai Trough and Mallik Areas

Science.gov (United States)

Uchida, T.; Tsuji, T.; Waseda, A.

2009-12-01

The Nankai Trough parallels the Japanese Island, where extensive BSRs have been interpreted from seismic reflection records. High resolution seismic surveys have definitely indicated gas hydrate distributions, and drilling the MITI Nankai Trough wells in 2000 and the METI Tokai-oki to Kumano-nada wells in 2004 have revealed subsurface gas hydrate in the eastern part of Nankai Trough. In 1998 and 2002 Mallik wells were drilled at Mackenzie Delta in the Canadian Arctic that also clarified the characteristics of gas hydrate-dominant sandy layers at depths from 890 to 1110 m beneath the permafrost zone. During the field operations, the LWD and wire-line well log data were continuously obtained and plenty of gas hydrate-bearing sand cores were recovered. Subsequence sedimentological and geochemical analyses performed on those core samples revealed the crucial geologic controls on the formation and preservation of natural gas hydrate in sediments. Pore-space gas hydrates reside in sandy sediments mostly filling intergranular porosity. Pore waters chloride anomalies, core temperature depression and core observations on visible gas hydrates confirm the presence of pore-space gas hydrates within moderate to thick sandy layers, typically 10 cm to a meter thick. Sediment porosities and pore-size distributions were obtained by mercury porosimetry, which indicate that porosities of gas hydrate-bearing sandy strata are approximately 45 %. According to grain size distribution curves, gas hydrate is dominant in fine- to very fine-grained sandy strata. Gas hydrate saturations are typically up to 80 % in pore volume throughout most of the hydrate-dominant sandy layers, which are estimated by well log analyses as well as pore water chloride anomalies. It is necessary for investigating subsurface fluid flow behaviors to evaluate both porosity and permeability of gas hydrate-bearing sandy sediments, and the measurements of water permeability for them indicated that highly saturated

High speed, self-acting, face-contact shaft seal has low leakage and very low wear

Science.gov (United States)

Zuk, J.; Ludwig, L. P.; Johnson, R. L.

1972-01-01

Design adds gas thrust bearing to face of conventional face seal. Bearing lifts seal's carbon face out of contact after startup and establishes thin gas film between sealing surfaces. Operating pressure and speed capabilities are greater than those of conventional face seals.

Active lubrication applied to radial gas journal bearings. Part 2: Modelling improvement and experimental validation

DEFF Research Database (Denmark)

Pierart, Fabián G.; Santos, Ilmar F.

2016-01-01

Actively-controlled lubrication techniques are applied to radial gas bearings aiming at enhancing one of their most critical drawbacks, their lack of damping. A model-based control design approach is presented using simple feedback control laws, i.e. proportional controllers. The design approach...... by finite element method and the global model is used as control design tool. Active lubrication allows for significant increase in damping factor of the rotor-bearing system. Very good agreement between theory and experiment is obtained, supporting the multi-physic design tool developed....

A Novel Integral 5-DOFs Hybrid Magnetic Bearing with One Permanent Magnet Ring Used for Turboexpander

Directory of Open Access Journals (Sweden)

Bangcheng Han

2014-01-01

Full Text Available We propose a novel combined five-degrees-of-freedom (5-DOFs hybrid magnetic bearing (HMB with only one permanent magnet ring (PMR used for turboexpanders. It has two radial magnetic bearing (RMB units; each has four poles and one thrust magnetic bearing (TMB to control 5-DOFs. Based on one PMR, the bias flux of the two radial magnetic bearing units and the one thrust magnetic bearing unit is constructed. As a result, ultra-high-speed, lower power loss, small size, and low cost can be achieved. Furthermore, the equivalent magnetic circuit method and 3D finite element method (FEM are used to model and analyze the combined 5-DOFs HMB. The force-current, force-position, torque-coil currents, the torque-angle position, and the stiffness models of the combined 5-DOFs HMB are given. Moreover, its coupling problems between the RMB units and the AMB unit are also proposed in this paper. An example is given to clarify the mathematical models and the coupling problems, and the linearized models are proposed for the follow-up controller design.

Load responsive hydrodynamic bearing

Science.gov (United States)

Kalsi, Manmohan S.; Somogyi, Dezso; Dietle, Lannie L.

2002-01-01

A load responsive hydrodynamic bearing is provided in the form of a thrust bearing or journal bearing for supporting, guiding and lubricating a relatively rotatable member to minimize wear thereof responsive to relative rotation under severe load. In the space between spaced relatively rotatable members and in the presence of a liquid or grease lubricant, one or more continuous ring shaped integral generally circular bearing bodies each define at least one dynamic surface and a plurality of support regions. Each of the support regions defines a static surface which is oriented in generally opposed relation with the dynamic surface for contact with one of the relatively rotatable members. A plurality of flexing regions are defined by the generally circular body of the bearing and are integral with and located between adjacent support regions. Each of the flexing regions has a first beam-like element being connected by an integral flexible hinge with one of the support regions and a second beam-like element having an integral flexible hinge connection with an adjacent support region. A least one local weakening geometry of the flexing region is located intermediate the first and second beam-like elements. In response to application of load from one of the relatively rotatable elements to the bearing, the beam-like elements and the local weakening geometry become flexed, causing the dynamic surface to deform and establish a hydrodynamic geometry for wedging lubricant into the dynamic interface.

Operation and design selection of high temperature superconducting magnetic bearings

International Nuclear Information System (INIS)

Werfel, F N; Floegel-Delor, U; Riedel, T; Rothfeld, R; Wippich, D; Goebel, B

2004-01-01

Axial and radial high temperature superconducting (HTS) magnetic bearings are evaluated by their parameters. Journal bearings possess advantages over thrust bearings. High magnetic gradients in a multi-pole permanent magnet (PM) configuration, the surrounding melt textured YBCO stator and adequate designs are the key features for increasing the overall bearing stiffness. The gap distance between rotor and stator determines the specific forces and has a strong impact on the PM rotor design. We report on the designing, building and measuring of a 200 mm prototype 100 kg HTS bearing with an encapsulated and thermally insulated melt textured YBCO ring stator. The encapsulation requires a magnetically large-gap (4-5 mm) operation but reduces the cryogenic effort substantially. The bearing requires 3 l of LN 2 for cooling down, and about 0.2 l LN 2 h -1 under operation. This is a dramatic improvement of the efficiency and in the practical usage of HTS magnetic bearings

Authigenic rhodochrosite from a gas hydrate-bearing structure in Lake Baikal

Science.gov (United States)

Krylov, Alexey A.; Hachikubo, Akihiro; Minami, Hirotsugu; Pogodaeva, Tatyana V.; Zemskaya, Tamara I.; Krzhizhanovskaya, Mariya G.; Poort, Jeffrey; Khlystov, Oleg M.

2018-02-01

Early diagenetic carbonates are rare in Lake Baikal. Siderite (Fe carbonate) concretions in the sediments were discovered only recently. Here, we discuss the first finding of rhodochrosite concretions (Mn carbonate) discovered in the near-bottom sediments of the gas hydrate-bearing seepage structure St. Petersburg-2 in the deep water environment of the Central Baikal Basin. The crystal lattice of rhodochrosite contains iron and calcium substituting to manganese. Based on pore water geochemistry and of δ 13C values of rhodochrosite (- 23.3 and - 29.4‰), carbon dioxide (+ 3.8 to - 16.1‰) and methane (- 63.2 to - 67.8‰), we show that carbonate crystallization most likely occurred during microbial anaerobic oxidation of organic matter, and that part of the oxygen making up the rhodochrosite seems to be derived from the 18O-rich water released from dissociating gas hydrates.

The thrust belts of Western North America

Energy Technology Data Exchange (ETDEWEB)

Moulton, F.C.

1993-08-01

Most of the Basin and Range physiographic province of western North America is now believed to be part of the overthrust. The more obvious overthrust belt along the eastern edge of the Basin and Range Province is named the Sevier orogenic belt, where older rocks are observed thrust onto younger rocks. More detailed surface geological mapping, plus deep multiple-fold geophysical work and many oil and gas wildcat wells, have confirmed an east-vergent shortened and stacked sequence is present in many places in the Basin and Range. This western compressive deformed area in east central Nevada is now named the Elko orogenic belt by the U.S. Geological Survey. This older compressed Elko orogenic belt started forming approximately 250 m.y. ago when the North American plate started to move west as the Pangaea supercontinent started to fragment. The North American plate moved west under the sediments of the Miogeocline that were also moving west. Surface-formed highlands and oceanic island arcs on the west edge of the North American plate restricted the westward movement of the sediments in the Miogeocline, causing east-vergent ramp thrusts to form above the westward-moving North American plate. The flat, eastward-up-cutting thrust assemblages moved on the detachment surfaces.

A microNewton thrust stand for average thrust measurement of pulsed microthruster.

Science.gov (United States)

Zhou, Wei-Jing; Hong, Yan-Ji; Chang, Hao

2013-12-01

A torsional thrust stand has been developed for the study of the average thrust for microNewton pulsed thrusters. The main body of the thrust stand mainly consists of a torsional balance, a pair of flexural pivots, a capacitive displacement sensor, a calibration assembly, and an eddy current damper. The behavior of the stand was thoroughly studied. The principle of thrust measurement was analyzed. The average thrust is determined as a function of the average equilibrium angle displacement of the balance and the spring stiffness. The thrust stand has a load capacity up to 10 kg, and it can theoretically measure the force up to 609.6 μN with a resolution of 24.4 nN. The static calibrations were performed based on the calibration assembly composed of the multiturn coil and the permanent magnet. The calibration results demonstrated good repeatability (less than 0.68% FSO) and good linearity (less than 0.88% FSO). The assembly of the multiturn coil and the permanent magnet was also used as an exciter to simulate the microthruster to further research the performance of the thrust stand. Three sets of force pulses at 17, 33.5, and 55 Hz with the same amplitude and pulse width were tested. The repeatability error at each frequency was 7.04%, 1.78%, and 5.08%, respectively.

Modified effective medium model for gas hydrate bearing,clay-dominated sediments in the Krishna-Godavari Basin

Digital Repository Service at National Institute of Oceanography (India)

Sriram, G.; Dewangan, P.; Ramprasad, T.

.D., 1990. Nonlinear elasticity and pressure-dependent wave speeds in granular media. Proc. R. Soc. London. Ser. A Math. Phys. Sci. 430, 105–131. Guerin, G., Goldberg, D., 2005. Modeling of acoustic wave dissipation in gas hydrate-bearing sediments...

Experimental investigations of active air bearings

DEFF Research Database (Denmark)

Santos, Ilmar; Morosi, Stefano

2012-01-01

Along with traditional oil lubrication, increasing demand for high-speed applications has renewed attention to gas bearings technology. Traditional aerostatic and aerodynamic gas lubrication has been widely used in a variety of applications, ranging from high-speed spindles to micro and meso......-scale turbomachinery. The present paper deals with experimental rotordynamic testing of a flexible rotor supported by hybrid aerostaticaerodynamic gas journal bearing equipped with an electronic radial air injection system. From a rotordynamic point of view there are two phenomena that limit the widespread...... of traditional gas lubrication: 1) Low damping makes operation across critical speed dangerous, as even low level of unbalance can generate large vibration responses. This is especially problematic for gas bearing applications, which often operate in the supercritical region. Moreover, 2) An upper bound...

Coupled numerical modeling of gas hydrates bearing sediments from laboratory to field-scale conditions

Science.gov (United States)

Sanchez, M. J.; Santamarina, C.; Gai, X., Sr.; Teymouri, M., Sr.

2017-12-01

Stability and behavior of Hydrate Bearing Sediments (HBS) are characterized by the metastable character of the gas hydrate structure which strongly depends on thermo-hydro-chemo-mechanical (THCM) actions. Hydrate formation, dissociation and methane production from hydrate bearing sediments are coupled THCM processes that involve, amongst other, exothermic formation and endothermic dissociation of hydrate and ice phases, mixed fluid flow and large changes in fluid pressure. The analysis of available data from past field and laboratory experiments, and the optimization of future field production studies require a formal and robust numerical framework able to capture the very complex behavior of this type of soil. A comprehensive fully coupled THCM formulation has been developed and implemented into a finite element code to tackle problems involving gas hydrates sediments. Special attention is paid to the geomechanical behavior of HBS, and particularly to their response upon hydrate dissociation under loading. The numerical framework has been validated against recent experiments conducted under controlled conditions in the laboratory that challenge the proposed approach and highlight the complex interaction among THCM processes in HBS. The performance of the models in these case studies is highly satisfactory. Finally, the numerical code is applied to analyze the behavior of gas hydrate soils under field-scale conditions exploring different features of material behavior under possible reservoir conditions.

An application of gain-scheduled control using state-space interpolation to hydroactive gas bearings

DEFF Research Database (Denmark)

Theisen, Lukas Roy Svane; Camino, Juan F.; Niemann, Hans Henrik

2016-01-01

with a gain-scheduling strategy using state-space interpolation, which avoids both the performance loss and the increase of controller order associated to the Youla parametrisation. The proposed state-space interpolation for gain-scheduling is applied for mass imbalance rejection for a controllable gas...... bearing scheduled in two parameters. Comparisons against the Youla-based scheduling demonstrate the superiority of the state-space interpolation....

Superconducting Meissner effect bearings for cryogenic turbomachines, phase 2

Science.gov (United States)

Valenzuela, Javier A.; Martin, Jerry L.

1994-02-01

This is the final report of a Phase 2 SBIR project to develop Meissner effect bearings for miniature cryogenic turbomachines. The bearing system was designed for use in miniature cryogenic turboexpanders in reverse-Brayton-cycle cryocoolers. The cryocoolers are designed to cool sensors on satellites. Existing gas bearings for this application run in a relatively warm state. The heat loss from the bearings into the shaft and into the cold process gas imposes a penalty on the cycle efficiency. By using cold Meissner effect bearings, this heat loss could be minimized, and the input power per unit of cooling for these cryocoolers could be reduced. Two bearing concepts were explored in this project. The first used an all-magnetic passive radial suspension to position the shaft over a range of temperatures from room temperature to 77 K. This bearing concept was proven to be feasible, but impractical for the miniature high-speed turbine application since it lacked the required shaft positioning accuracy. A second bearing concept was then developed. In this concept, the Meissner effect bearings are combined with self-acting gas bearings. The Meissner effect bearing provides the additional stiffness and damping required to stabilize the shaft at low temperature, while the gas bearing provides the necessary accuracy to allow very small turbine tip clearances (5mm) and high speeds (greater than 500,000 rpm).

Thrust augmentation in tandem flapping foils by foil-wake interaction

Science.gov (United States)

Anderson, Erik; Lauder, George

2006-11-01

Propulsion by pitching and heaving airfoils and hydrofoils has been a focus of much research in the field of biologically inspired propulsion. Organisms that use this sort of propulsion are self-propelled, so it is difficult to use standard experimental metrics such as thrust and drag to characterize performance. We have constructed a flapping foil robot mounted in a flume on air-bearings that allows for the determination of self-propelled speed as a metric of performance. We have used a pair of these robots to examine the impact of an upstream flapping foil on a downstream flapping foil as might apply to tandem fins of a swimming organism or in-line swimming of schooling organisms. Self-propelled speed and a force transducer confirmed significant thrust augmentation for particular foil-to-foil spacings, phase differences, and flapping frequencies. Flow visualization shows the mechanism to be related to the effective angle of attack of the downstream foil due to the structure of the wake of the upstream foil. This confirms recent computational work and the hypotheses by early investigators of fish fluid dynamics.

Integral finite element analysis of turntable bearing with flexible rings

Science.gov (United States)

Deng, Biao; Liu, Yunfei; Guo, Yuan; Tang, Shengjin; Su, Wenbin; Lei, Zhufeng; Wang, Pengcheng

2018-03-01

This paper suggests a method to calculate the internal load distribution and contact stress of the thrust angular contact ball turntable bearing by FEA. The influence of the stiffness of the bearing structure and the plastic deformation of contact area on the internal load distribution and contact stress of the bearing is considered. In this method, the load-deformation relationship of the rolling elements is determined by the finite element contact analysis of a single rolling element and the raceway. Based on this, the nonlinear contact between the rolling elements and the inner and outer ring raceways is same as a nonlinear compression spring and bearing integral finite element analysis model including support structure was established. The effects of structural deformation and plastic deformation on the built-in stress distribution of slewing bearing are investigated on basis of comparing the consequences of load distribution, inner and outer ring stress, contact stress and other finite element analysis results with the traditional bearing theory, which has guiding function for improving the design of slewing bearing.

Development of an indirect counterbalanced pendulum optical-lever thrust balance for micro- to millinewton thrust measurement

International Nuclear Information System (INIS)

Grubišić, A N; Gabriel, S B

2010-01-01

This paper describes the design and testing of an indirect hanging pendulum thrust balance using a laser-optical-lever principle to provide micro- to millinewton thrust measurement for the development of electric propulsion systems. The design philosophy allows the selection of the total thrust range in order to maximize resolution through a counterbalanced pendulum principle, as well as passive magnetic damping in order to allow relatively rapid transient thrust measurement. The balance was designed for the purpose of hollow cathode microthruster characterization, but could be applied to other electric propulsion devices in the thrust range of micro- to millinewtons. An initial thrust characterization of the T5 hollow cathode is presented

Spacing of Imbricated Thrust Faults and the Strength of Thrust-Belts and Accretionary Wedges

Science.gov (United States)

Ito, G.; Regensburger, P. V.; Moore, G. F.

2017-12-01

The pattern of imbricated thrust blocks is a prominent characteristic of the large-scale structure of thrust-belts and accretionary wedges around the world. Mechanical models of these systems have a rich history from laboratory analogs, and more recently from computational simulations, most of which, qualitatively reproduce the regular patterns of imbricated thrusts seen in nature. Despite the prevalence of these patterns in nature and in models, our knowledge of what controls the spacing of the thrusts remains immature at best. We tackle this problem using a finite difference, particle-in-cell method that simulates visco-elastic-plastic deformation with a Mohr-Coulomb brittle failure criterion. The model simulates a horizontal base that moves toward a rigid vertical backstop, carrying with it an overlying layer of crust. The crustal layer has a greater frictional strength than the base, is cohesive, and is initially uniform in thickness. As the layer contracts, a series of thrust blocks immerge sequentially and form a wedge having a mean taper consistent with that predicted by a noncohesive, critical Coulomb wedge. The widths of the thrust blocks (or spacing between adjacent thrusts) are greatest at the front of the wedge, tend to decrease with continued contraction, and then tend toward a pseudo-steady, minimum width. Numerous experiments show that the characteristic spacing of thrusts increases with the brittle strength of the wedge material (cohesion + friction) and decreases with increasing basal friction for low (laws that will illuminate the basic physical processes controlling systems, as well as allow researchers to use observations of thrust spacing as an independent constraint on the brittle strength of wedges as well as their bases.

Experimental study on the thrust modulation performance of powdered magnesium and CO2 bipropellant engine

Science.gov (United States)

Li, Chao; Hu, Chunbo; Zhu, Xiaofei; Hu, Jiaming; Li, Yue; Hu, Xu

2018-06-01

Powdered Mg and CO2 bipropellant engine providing a practical demonstration of in situ resource utilization (ISRU) for Mars Sample Return (MSR) mission seems to be feasible by current investigations. However, essential functions of the engine to satisfy the complicated ballistics requirements such as thrust modulation and multiple pulse have not been established yet. The aim of this experimental study is to evaluate the engine's thrust modulation feasibility and to investigate its thrust modulation characteristics. A powdered Mg and CO2 bipropellant engine construction aiming to achieve thrust modulation ability was proposed. A mass flow rate calibration experiment to evaluate the gas-solid mass flow rate regulating performance was conducted before fire tests. Fire test result shows that the engine achieved successful ignition as well as self-sustaining combustion; Thrust modulation of the engine is feasible, detail thrust estimating result of the test shows that maximum thrust is 135.91 N and the minimum is 5.65 N with a 22.11 thrust modulation ratio, moreover, the transportation period is quick and the thrust modulation ratio is adjustable. At the same time, the powder feed system reaches a two-step flow rate regulating with a modulation ratio of 4.5-5. What' more, caused by the uneven engine working conditions, there is an obvious difference in combustion efficiency value, maximum combustion efficiency of the powdered Mg and CO2 bipropellant engine is 80.20%.

Lubrication of Space Shuttle Main Engine Turbopump Bearings

Science.gov (United States)

Gibson, Howard; Munafo, Paul (Technical Monitor)

2001-01-01

The Space Shuttle has three main engines that are used for propulsion into orbit. These engines are fed propellants by four turbopumps on each engine. A main element in the turbopump is the bearings supporting the rotor that spins the turbine blades and the pump impeller. These bearings are required to spin at very high speeds, support radial and thrust loads, and have high wear resistance without the benefit of lubrication. The liquid hydrogen and oxygen propellants flow through the bearings to cool the surfaces. The volatile nature of the propellants excludes any conventional means of lubrication. Lubrication for these bearings is provided by the ball separator inside the bearing. The separator is a composite material that supplies a transfer film of lubrication to the rings and balls. New separator materials and lubrication schemes have been investigated at Marshall Space Flight Center in a bearing test rig with promising results. Hybrid bearings with silicon nitride balls have also been evaluated. The use of hybrid, silicon nitride ball bearings in conjunction -with better separator materials has shown excellent results. The work that Marshall has done is being utilized in turbopumps flying on the space shuttle fleet and will be utilized in future space travel. This result of this work is valuable for all aerospace and commercial applications where high-speed bearings are used.

Angular-contact ball-bearing internal load estimation algorithm using runtime adaptive relaxation

Science.gov (United States)

Medina, H.; Mutu, R.

2017-07-01

An algorithm to estimate internal loads for single-row angular contact ball bearings due to externally applied thrust loads and high-operating speeds is presented. A new runtime adaptive relaxation procedure and blending function is proposed which ensures algorithm stability whilst also reducing the number of iterations needed to reach convergence, leading to an average reduction in computation time in excess of approximately 80%. The model is validated based on a 218 angular contact bearing and shows excellent agreement compared to published results.

Gas Bearing Control for Safe Operation in Critical Speed Regions - Experimental Verification

DEFF Research Database (Denmark)

Theisen, Lukas R. S.; Niemann, Hans H.; Galeazzi, Roberto

2015-01-01

supported by gas bearings to extend their operating range. Using H∞-design methods, active lubrication techniques are proposed to enhance the damping, which in turn reduces the vibrations to a desired safe level. The control design is validated experimentally on a laboratory test rig, and shown to allow...... and deceleration patterns and avoidance of operation near the critical speeds, which is a limiting factor during operation, specially during run-downs. An approach for reducing the vibrations is by feedback controlled lubrication. This paper addresses the challenge of reducing vibrations in rotating machines...

Existence of equilibria in articulated bearings

Science.gov (United States)

Buscaglia, G.; Ciuperca, I.; Hafidi, I.; Jai, M.

2007-04-01

The existence of equilibrium solutions for a lubricated system consisting of an articulated body sliding over a flat plate is considered. Though this configuration is very common (it corresponds to the popular tilting-pad thrust bearings), the existence problem has only been addressed in extremely simplified cases, such as planar sliders of infinite width. Our results show the existence of at least one equilibrium for a quite general class of (nonplanar) slider shapes. We also extend previous results concerning planar sliders.

The experimental study on efficiency improvement of turbo machinery supported with magnetic bearings

International Nuclear Information System (INIS)

Park, In Hwang; Park, Young Ho; Han, Dong Chul

2007-01-01

To implement a conventional electromagnetic bearing in small turbo machinery, it has problems such as load capacity and size. Therefore, in this paper, these problems are resolved by using a permanent magnet biased electromagnetic bearing as a thrust bearing of small turbo machinery. Because the flux path of the bearing is designed by reluctance path modulation using an electromagnet and a permanent magnet, the bearing improves upon non-linearity, power consumption, size and load capacity of a conventional electromagnetic bearing. Test rotating the shaft over 500,000DN were carried out to verify the performance of the proposed small turbo machinery. In addition, the relationships between mass flow rate and pressure rise were measured as changing the tip clearance to verify the feasibility of efficiency improvement and active surge control and these results were compared with theoretical results

Neogene deformation of thrust-top Rzeszów Basin (Outer Carpathians, Poland)

Science.gov (United States)

Uroda, Joanna

2015-04-01

The Rzeszów Basin is a 220 km2 basin located in the frontal part of Polish Outer Carpathians fold-and-thrust belt. Its sedimentary succession consist of ca. 600 m- thick Miocene evaporates, litoral and marine sediments. This basin developed between Babica-Kąkolówka anticline and frontal thrust of Carpathian Orogen. Rzeszów thrust-top basin is a part of Carpathian foreland basin system- wedge-top depozone. The sediments of wedge -top depozone were syntectonic deformed, what is valuable tool to understand kinematic history of the orogen. Analysis of field and 3D seismic reflection data showed the internal structure of the basin. Seismic data reveal the presence of fault-bend-folds in the basement of Rzeszów basin. The architecture of the basin - the presence of fault-releated folds - suggest that the sediments were deformed in last compressing phase of Carpathian Orogen deformation. Evolution of Rzeszów Basin is compared with Bonini et.al. (1999) model of thrust-top basin whose development is controlled by the kinematics of two competing thrust anticlines. Analysis of seismic and well data in Rzeszów basin suggest that growth sediments are thicker in south part of the basin. During the thrusting the passive rotation of the internal thrust had taken place, what influence the basin fill architecture and depocentre migration opposite to thrust propagation. Acknowledgments This study was supported by grant No 2012/07/N/ST10/03221 of the Polish National Centre of Science "Tectonic activity of the Skole Nappe based on analysis of changes in the vertical profile and depocentre migration of Neogene sediments in Rzeszów-Strzyżów area (Outer Carpathians)". Seismic data by courtesy of the Polish Gas and Oil Company. References Bonini M., Moratti G., Sani F., 1999, Evolution and depocentre migration in thrust-top basins: inferences from the Messinian Velona Basin (Northern Apennines, Italy), Tectonophysics 304, 95-108.

Thrust distribution for attitude control in a variable thrust propulsion system with four ACS nozzles

Science.gov (United States)

Lim, Yeerang; Lee, Wonsuk; Bang, Hyochoong; Lee, Hosung

2017-04-01

A thrust distribution approach is proposed in this paper for a variable thrust solid propulsion system with an attitude control system (ACS) that uses a reduced number of nozzles for a three-axis attitude maneuver. Although a conventional variable thrust solid propulsion system needs six ACS nozzles, this paper proposes a thrust system with four ACS nozzles to reduce the complexity and mass of the system. The performance of the new system was analyzed with numerical simulations, and the results show that the performance of the system with four ACS nozzles was similar to the original system while the mass of the whole system was simultaneously reduced. Moreover, a feasibility analysis was performed to determine whether a thrust system with three ACS nozzles is possible.

Bears and pipeline construction in Alaska

Energy Technology Data Exchange (ETDEWEB)

Follmann, E.H.; Hechtel, J.L. (Univ. of Alaska Fairbanks, AK (USA))

1990-06-01

Serious problems were encountered with bears during construction of the 1274-km trans-Alaska oil pipeline between Prudhoe Bay and Valdez. This multi-billion-dollar project traversed both black bear (Ursus americanus Pallas) and grizzly bear (U. arctos L.) habitat throughtout its entire length. Plans for dealing with anticipated problems with bears were often inadequate. Most (71%) problems occurred north of the Yukon River in a previously roadless wilderness where inadequate refuse disposal and widespread animal feeding created dangerous situations. Of the 192 officially reported bear problems associated with the Trans-Alaska Pipeline System (TAPS) (1971-1979), about 65% involved the presence of bears in camps or dumps, 13% the feeding of bears on garbage or handouts, 10% property damage or economic loss, 7% bears under and in buildings, and only 5% charges by bears. Remarkably, no bear-related injuries were reported, suggesting that bears became accustomed to people and did not regard them as a threat. Following construction of the TAPS there have been proposals for pipelines to transport natural gas from Prudhoe Bay to southern and Pacific-rim markets. Based on past experience, some animal control measures were developed during the planning phase for the authorized gas pipeline route in Alaska. Fences installed around 100-person survey camps were found to be effective in deterring bears in two traditionally troublesome areas. 16 refs., 7 figs., 1 tab.

The Development of Open Water-lubricated Polycrystalline Diamond (PCD) Thrust Bearings for Use in Marine Hydrokinetic (MHK) Energy Machines

Energy Technology Data Exchange (ETDEWEB)

Cooley, Craig, H.; Khonsari, Michael,, M; Lingwall, Brent

2012-11-28

Polycrstalline diamond (PCD) bearings were designed, fabricated and tested for marine-hydro-kinetic (MHK) application. Bearing efficiency and life were evaluated using the US Synthetic bearing test facility. Three iterations of design, build and test were conducted to arrive at the best bearing design. In addition life testing that simulated the starting and stopping and the loading of real MHK applications were performed. Results showed polycrystalline diamond bearings are well suited for MHK applications and that diamond bearing technology is TRL4 ready. Based on life tests results bearing life is estimated to be at least 11.5 years. A calculation method for evaluating the performance of diamond bearings of round geometry was also investigated and developed. Finally, as part of this effort test bearings were supplied free of charge to the University of Alaska for further evaluation. The University of Alaska test program will subject the diamond bearings to sediment laden lubricating fluid.

The technology of the bearings used in the nuclear power generation system turbine generator units

International Nuclear Information System (INIS)

Vialettes, J.M.; Rossato, M.

1997-01-01

A bearing consists of all the stationary part which allow the relative motion in rotation or in translation, of a shaft line. Inside the bearing there is a journal bearing with a metallic anti-friction coating (the babbitt metal). The high power turbine generator unit rotors are supported by smooth transversal journal bearings fed with oil which fills the empty space and runs along the shaft. The technologies used for the bearings and the thrust bearings of the turbine generator units and the various shaft lines of the French CP0/CP1- and CP2/1300 MW-type nuclear power plants are described. The experience feedback is then discussed in terms of the dynamics of the shaft line, i.e. vibrational problems, the influence of the alignment and the babbitt metal incidents. (author)

Miniature Centrifugal Compressor

Science.gov (United States)

Sixsmith, Herbert

1989-01-01

Miniature turbocompressor designed for reliability and long life. Cryogenic system includes compressor, turboexpander, and heat exchanger provides 5 W of refrigeration at 70 K from 150 W input power. Design speed of machine 510,000 rpm. Compressor has gas-lubricated journal bearings and magnetic thrust bearing. When compressor runs no bearing contact and no wear.

Steady state characteristics of an adjustable hybrid gas bearing – Computational fluid dynamics, modified Reynolds equation and experimental validation

DEFF Research Database (Denmark)

Pierart Vásquez, Fabián Gonzalo; Santos, Ilmar

2015-01-01

To include the effect of external pressurization in hybrid gas bearings an extra term is added to Reynolds Equation to accommodate the gas jet. Two cases are considered: cylindrical and annular flow profiles. Validation of theoretical results obtained using the modified version of Reynolds equation....... By introducing such coefficients into the modified Reynolds equation, good agreement with experiments is achieved in terms of journal equilibrium position and resulting aerodynamic forces....

Thrust Measurement of Dielectric Barrier Discharge (DBD) Plasma Actuators: New Anti-Thrust Hypothesis, Frequency Sweeps Methodology, Humidity and Enclosure Effects

Science.gov (United States)

Ashpis, David E.; Laun, Matthew C.

2014-01-01

We discuss thrust measurements of Dielectric Barrier Discharge (DBD) plasma actuators devices used for aerodynamic active flow control. After a review of our experience with conventional thrust measurement and significant non-repeatability of the results, we devised a suspended actuator test setup, and now present a methodology of thrust measurements with decreased uncertainty. The methodology consists of frequency scans at constant voltages. The procedure consists of increasing the frequency in a step-wise fashion from several Hz to the maximum frequency of several kHz, followed by frequency decrease back down to the start frequency of several Hz. This sequence is performed first at the highest voltage of interest, then repeated at lower voltages. The data in the descending frequency direction is more consistent and selected for reporting. Sample results show strong dependence of thrust on humidity which also affects the consistency and fluctuations of the measurements. We also observed negative values of thrust, or "anti-thrust", at low frequencies between 4 Hz and up to 64 Hz. The anti-thrust is proportional to the mean-squared voltage and is frequency independent. Departures from the parabolic anti-thrust curve are correlated with appearance of visible plasma discharges. We propose the anti-thrust hypothesis. It states that the measured thrust is a sum of plasma thrust and anti-thrust, and assumes that the anti-thrust exists at all frequencies and voltages. The anti-thrust depends on actuator geometry and materials and on the test installation. It enables the separation of the plasma thrust from the measured total thrust. This approach enables more meaningful comparisons between actuators at different installations and laboratories. The dependence on test installation was validated by surrounding the actuator with a grounded large-diameter metal sleeve. Strong dependence on humidity is also shown; the thrust significantly increased with decreasing humidity, e

Micro thrust and heat generator

Science.gov (United States)

Garcia, E.J.

1998-11-17

A micro thrust and heat generator have a means for providing a combustion fuel source to an ignition chamber of the micro thrust and heat generator. The fuel is ignited by a ignition means within the micro thrust and heat generator`s ignition chamber where it burns and creates a pressure. A nozzle formed from the combustion chamber extends outward from the combustion chamber and tappers down to a narrow diameter and then opens into a wider diameter where the nozzle then terminates outside of said combustion chamber. The pressure created within the combustion chamber accelerates as it leaves the chamber through the nozzle resulting in pressure and heat escaping from the nozzle to the atmosphere outside the micro thrust and heat generator. The micro thrust and heat generator can be microfabricated from a variety of materials, e.g., of polysilicon, on one wafer using surface micromachining batch fabrication techniques or high aspect ratio micromachining techniques (LIGA). 30 figs.

Basic Characteristics and Design of a Novel Hybrid Magnetic Bearing for Wind Turbines

Directory of Open Access Journals (Sweden)

Yanjun Yu

2016-11-01

Full Text Available This paper proposes a five-degree-of-freedom (5-DOF hybrid magnetic bearing (HMB for direct-drive wind turbines, which can realize suspension in the 4-DOF radial and 1-DOF axial directions. Only two sets of radial control windings are employed in the proposed HMB because only one set of radial control windings can achieve the 2-DOF suspension in the radial direction. Unlike the traditional active thrust magnetic bearings, this paper uses a cylindrical rotor core without a large thrust disc in the novel HMB. The numbers of the controller, power amplifier and system volume can be reduced in the magnetic suspension system. This paper also presents the structure and basic characteristics of the proposed magnetic bearing. A precision equivalent magnetic circuit analysis of the permanent magnet ring and control magnetic field is conducted in this study, in consideration of the non-uniform distribution of magnetic density. Accordingly, the mathematical models, including the suspension force expression, are derived based on the accurate equivalent magnetic circuit. The basic principle of the structure parameter design is presented, based on the given key parameters. The accuracy of the analytical method is further validated by 3D finite element analysis.

Rotordynamics of automotive turbochargers. Linear and nonlinear rotordynamics - Bearing design - Rotor balancing

Energy Technology Data Exchange (ETDEWEB)

Nguyen-Schaefer, Hung [Bosch Mahle Turbo Systems GmbH und Co. KG, Stuttgart (Germany)

2012-11-01

Describes the rotordynamics of automotive turbochargers. Requires only a minimum of mathematical background. Written by an R and D expert from industry. This book deals with rotordynamics of automotive turbochargers while encompassing the analysis of the dynamics of rotating machines at very high rotor speeds of 300,000 rpm and above. This interdisciplinary field involves 1. thermodynamics and turbo-matching knowledge to compute working conditions of turbochargers, 2. fluid and bearing dynamics to calculate various operating thrust loads and to design the rotating floating ring bearings (two-oil-film bearings), and 3. tribology to improve the rotor stability and to reduce the bearing friction. Mathematical background in modeling and simulation methods is necessary; however, the prerequisites have been kept to a minimum. The book addresses both practitioners working in the field of rotordynamics of automotive turbochargers and graduate students in mechanical engineering.

In situ thermal conductivity of gas-hydrate-bearing sediments of the Mallik 5L-38 well

Science.gov (United States)

Henninges, J.; Huenges, E.; Burkhardt, H.

2005-11-01

Detailed knowledge about thermal properties of rocks containing gas hydrate is required in order to quantify processes involving gas hydrate formation and decomposition in nature. In the framework of the Mallik 2002 program, three wells penetrating a continental gas hydrate occurrence under permafrost were successfully equipped with permanent fiber-optic distributed temperature sensing cables. Temperature data were collected over a 21-month period after completing the wells. Thermal conductivity profiles were calculated from the geothermal data as well as from a petrophysical model derived from the available logging data and application of mixing law models. Results indicate that thermal conductivity variations are mainly lithologically controlled with a minor influence from hydrate saturation. Average thermal conductivity values of the hydrate-bearing sediments range between 2.35 and 2.77 W m-1 K-1. Maximum gas hydrate saturations can reach up to about 90% at an average porosity of 0.3.

Propeller thrust analysis using Prandtl's lifting line theory, a comparison between the experimental thrust and the thrust predicted by Prandtl's lifting line theory

Science.gov (United States)

Kesler, Steven R.

The lifting line theory was first developed by Prandtl and was used primarily on analysis of airplane wings. Though the theory is about one hundred years old, it is still used in the initial calculations to find the lift of a wing. The question that guided this thesis was, "How close does Prandtl's lifting line theory predict the thrust of a propeller?" In order to answer this question, an experiment was designed that measured the thrust of a propeller for different speeds. The measured thrust was compared to what the theory predicted. In order to do this experiment and analysis, a propeller needed to be used. A walnut wood ultralight propeller was chosen that had a 1.30 meter (51 inches) length from tip to tip. In this thesis, Prandtl's lifting line theory was modified to account for the different incoming velocity depending on the radial position of the airfoil. A modified equation was used to reflect these differences. A working code was developed based on this modified equation. A testing rig was built that allowed the propeller to be rotated at high speeds while measuring the thrust. During testing, the rotational speed of the propeller ranged from 13-43 rotations per second. The thrust from the propeller was measured at different speeds and ranged from 16-33 Newton's. The test data were then compared to the theoretical results obtained from the lifting line code. A plot in Chapter 5 (the results section) shows the theoretical vs. actual thrust for different rotational speeds. The theory over predicted the actual thrust of the propeller. Depending on the rotational speed, the error was: at low speeds 36%, at low to moderate speeds 84%, and at high speeds the error increased to 195%. Different reasons for these errors are discussed.

Quantitative monitoring of gas flooding in oil-bearing reservoirs using a pulsed neutron tool

International Nuclear Information System (INIS)

Ruhovets, N.; Wyatt, D.F. Jr.

1991-01-01

This paper reports on quantitative monitoring of gas flooding in oil bearing reservoirs which is unique in that saturations of three fluids (gas, oil and water) in the effective pore space have to be determined, while in most other applications saturation behind casing is determined only for two fluids: hydrocarbons and water. A new method has been developed to monitor gas flooding of oil reservoirs. The method is based on computing two porosities: true effective (base) porosity determined before gas flooding, and apparent effective (monitor) porosity determined after gas flooding. The base porosity is determined from open and/or cased hole porosity logs run before the flooding. When open hole logs are available, the cased hole porosity logs are calibrated against open hole log. The monitor porosity is determined from one of the cased hole porosity logs, such as a neutron log or count rate ratio curve from a pulsed neutron log run after the gas flooding. The base and monitor porosities provide determination of the hydrogen index of the reservoir fluid after the flooding. This hydrogen index is then used to determine saturation of the flood agent after flooding. Water saturation after flooding can be determined from the equation which relates neutron total cross section (Σm) to volumetric constituent cross sections, using Σm values from a monitor run (after flooding)

Mu rhythm desynchronization by tongue thrust observation

Directory of Open Access Journals (Sweden)

Kotoe eSakihara

2015-09-01

Full Text Available We aimed to investigate the mu rhythm in the sensorimotor area during tongue thrust observation and to obtain an answer to the question as to how subtle non-verbal orofacial movement observation activates the sensorimotor area. Ten healthy volunteers performed finger tap execution, tongue thrust execution, and tongue thrust observation. The electroencephalogram was recorded from 128 electrodes placed on the scalp, and regions of interest were set at sensorimotor areas. The event-related desynchronization (ERD and event-related synchronization (ERS for the mu rhythm (8–13 Hz and beta (13−25 Hz bands were measured. Tongue thrust observation induced mu rhythm ERD, and the ERD was detected at the left hemisphere regardless whether the observed tongue thrust was toward the left or right. Mu rhythm ERD was also recorded during tongue thrust execution. However, temporal analysis revealed that the ERD associated with tongue thrust observation preceded that associated with execution by approximately 2 s. Tongue thrust observation induces mu rhythm ERD in sensorimotor cortex with left hemispheric dominance.

Analysis of thrust/torque signature of MOV

International Nuclear Information System (INIS)

Ryu, Ho Geun; Park, Seong Keun; Kim, Dae Woong

2001-01-01

For the evaluation of operability of MOV(Motor Operated Valve), the precision prediction of thrust/torque acting on the valve is important. In this paper, the analytical prediction method of thrust/torque was proposed. The design basis stem thrust calculation typically considers the followings: packing thrust, stem rejection load, design basis differential pressure load. In general, test results show that temperature, pressure, fluid type, and differential pressure, independently and combination, all have an effect on the friction factor. The prediction results of thrust/torque are well agreement with dynamic test results

Experimental Investigation of Friction Effect on Liner Model Rolling Bearings for Large Diameter Thrust Bearing Design

Directory of Open Access Journals (Sweden)

S. Babu

2012-12-01

Full Text Available Studying friction coefficient has significant importance, especially when dealing with high load and temperature applications that have frequent starting and stopping points. Towards that, two sets of angular contact Linear Model Mockup Bearings (LMMB were designed and fabricated. This linear model assembly was made up of high precision, grounded raceways (AISI 4140 and commercially purchased balls (AISI 52100. The experimental studies were carried out by placing different number of balls between the raceways under different loads at dry lubricating condition. The static friction coefficients were measured using two different experiments: viz gravitation-based experiment and direct linear force measurement experiment. And Digital Image Correlation (DIC technique was used to find the stiffness of LMMB set.

Polyethylene glycol drilling fluid for drilling in marine gas hydrates-bearing sediments: an experimental study

Energy Technology Data Exchange (ETDEWEB)

Jiang, G.; Liu, T.; Ning, F.; Tu, Y.; Zhang, L.; Yu, Y.; Kuang, L. [China University of Geosciences, Faculty of Engineering, Wuhan (China)

2011-07-01

Shale inhibition, low-temperature performance, the ability to prevent calcium and magnesium-ion pollution, and hydrate inhibition of polyethylene glycol drilling fluid were each tested with conventional drilling-fluid test equipment and an experimental gas-hydrate integrated simulation system developed by our laboratory. The results of these tests show that drilling fluid with a formulation of artificial seawater, 3% bentonite, 0.3% Na{sub 2}CO{sub 3}, 10% polyethylene glycol, 20% NaCl, 4% SMP-2, 1% LV-PAC, 0.5% NaOH and 1% PVP K-90 performs well in shale swelling and gas hydrate inhibition. It also shows satisfactory rheological properties and lubrication at temperature ranges from -8 {sup o}C to 15 {sup o}C. The PVP K-90, a kinetic hydrate inhibitor, can effectively inhibit gas hydrate aggregations at a dose of 1 wt%. This finding demonstrates that a drilling fluid with a high addition of NaCl and a low addition of PVP K-90 is suitable for drilling in natural marine gas-hydrate-bearing sediments. (authors)

Polyethylene Glycol Drilling Fluid for Drilling in Marine Gas Hydrates-Bearing Sediments: An Experimental Study

Directory of Open Access Journals (Sweden)

Lixin Kuang

2011-01-01

Full Text Available Shale inhibition, low-temperature performance, the ability to prevent calcium and magnesium-ion pollution, and hydrate inhibition of polyethylene glycol drilling fluid were each tested with conventional drilling-fluid test equipment and an experimental gas-hydrate integrated simulation system developed by our laboratory. The results of these tests show that drilling fluid with a formulation of artificial seawater, 3% bentonite, 0.3% Na2CO3, 10% polyethylene glycol, 20% NaCl, 4% SMP-2, 1% LV-PAC, 0.5% NaOH and 1% PVP K-90 performs well in shale swelling and gas hydrate inhibition. It also shows satisfactory rheological properties and lubrication at temperature ranges from −8 °C to 15 °C. The PVP K-90, a kinetic hydrate inhibitor, can effectively inhibit gas hydrate aggregations at a dose of 1 wt%. This finding demonstrates that a drilling fluid with a high addition of NaCl and a low addition of PVP K-90 is suitable for drilling in natural marine gas-hydrate-bearing sediments.

Reservoir characteristics of coal-shale sedimentary sequence in coal-bearing strata and their implications for the accumulation of unconventional gas

Science.gov (United States)

Wang, Yang; Zhu, Yanming; Liu, Yu; Chen, Shangbin

2018-04-01

Shale gas and coalbed methane (CBM) are both considered unconventional natural gas and are becoming increasingly important energy resources. In coal-bearing strata, coal and shale are vertically adjacent as coal and shale are continuously deposited. Research on the reservoir characteristics of coal-shale sedimentary sequences is important for CBM and coal-bearing shale gas exploration. In this study, a total of 71 samples were collected, including coal samples (total organic carbon (TOC) content >40%), carbonaceous shale samples (TOC content: 6%-10%), and shale samples (TOC content TOC content. Clay and quartz also have a great effect on the porosity of shale samples. According to the FE-SEM image technique, nanoscale pores in the organic matter of coal samples are much more developed compared with shale samples. For shales with low TOC, inorganic minerals provide more pores than organic matter. In addition, TOC content has a positive relationship with methane adsorption capacity, and the adsorption capacity of coal samples is more sensitive than the shale samples to temperature.

Experimental investigation of gas aerostatic bearings

Czech Academy of Sciences Publication Activity Database

Steinbauer, P.; Šika, Z.; Kozánek, Jan; Šimek, J.

2008-01-01

Roč. 3, - (2008), s. 769-776 ISSN 1335-2393 R&D Projects: GA ČR GA101/06/1787 Institutional research plan: CEZ:AV0Z20760514 Keywords : aerostatic bearing * experimental identification * measurement Subject RIV: BI - Acoustics

Thrusting and back-thrusting as post-emplacement kinematics of the Almora klippe: Insights from Low-temperature thermochronology

Science.gov (United States)

Patel, R. C.; Singh, Paramjeet; Lal, Nand

2015-06-01

Crystalline klippen over the Lesser Himalayan Sequence (LHS) in the Kumaon and Garhwal regions of NW-Himalaya, are the representative of southern portion of the Main Central Thrust (MCT) hanging wall. These were tectonically transported over the juxtaposed thrust sheets (Berinag, Tons and Ramgarh) of the LHS zone along the MCT. These klippen comprise of NW-SE trending synformal folded thrust sheet bounded by thrusts in the south and north. In the present study, the exhumation histories of two well-known klippen namely Almora and Baijnath, and the Ramgarh thrust sheet, in the Kumaon and Garhwal regions vis-a-vis Himalayan orogeny have been investigated using Apatite Fission Track (AFT) ages. Along a ~ 60 km long orogen perpendicular transect across the Almora klippe and the Ramgarh thrust sheet, 16 AFT cooling ages from the Almora klippe and 2 from the Ramgarh thrust sheet have been found to range from 3.7 ± 0.8 to 13.2 ± 2.7 Ma, and 6.3 ± 0.8 to 7.2 ± 1.0 Ma respectively. From LHS meta-sedimentary rocks only a single AFT age of 3.6 ± 0.8 Ma could be obtained. Three AFT ages from the Baijnath klippe range between 4.7 ± 0.5 and 6.6 ± 0.8 Ma. AFT ages and exhumation rates of different klippen show a dynamic coupling between tectonic and erosion processes in the Kumaon and Garhwal regions of NW-Himalaya. However, the tectonic processes play a dominant role in controlling the exhumation. Thrusting and back thrusting within the Almora klippe and Ramgarh thrust sheet are the post-emplacement kinematics that controlled the exhumation of the Almora klippe. Combining these results with the already published AFT ages from the crystalline klippen and the Higher Himalayan Crystalline (HHC), the kinematics of emplacement of the klippen over the LHS and exhumation pattern across the MCT in the Kumaon and Garhwal regions of NW-Himalaya have been investigated.

Influence of surface texturing on the performance of tilting pad thrust bearings

OpenAIRE

Gropper, Daniel; Wang, Ling; Harvey, Terry J.; Meck, Klaus-Dieter; Gviniashvili, Vladimir

2016-01-01

Surface textures have been shown to have the potential of enhancing the performance of hydrodynamic bearings and many other applications. However, a comprehensive literature review by the authors has revealed that the application of surface texturing is still limited due to major challenges, such as the complexity of computational models and the large variety of operating conditions encountered in conventional industrial applications. In the present work, the potential of surface texturing fo...

Thrust Performance Evaluation of a Turbofan Engine Based on Exergetic Approach and Thrust Management in Aircraft

Science.gov (United States)

Yalcin, Enver

2017-05-01

The environmental parameters such as temperature and air pressure which are changing depending on altitudes are effective on thrust and fuel consumption of aircraft engines. In flights with long routes, thrust management function in airplane information system has a structure that ensures altitude and performance management. This study focused on thrust changes throughout all flight were examined by taking into consideration their energy and exergy performances for fuel consumption of an aircraft engine used in flight with long route were taken as reference. The energetic and exergetic performance evaluations were made under the various altitude conditions. The thrust changes for different altitude conditions were obtained to be at 86.53 % in descending direction and at 142.58 % in ascending direction while the energy and exergy efficiency changes for the referenced engine were found to be at 80.77 % and 84.45 %, respectively. The results revealed here can be helpful to manage thrust and reduce fuel consumption, but engine performance will be in accordance with operation requirements.

Program for tests on magnetic bearing suspended rotor dynamics for gas turbine high temperature reactor (GTHTR300)

International Nuclear Information System (INIS)

Takada, Shoji; Takizuka, Takakazu; Kunitomi, Kazuhiko; Kosugiyama, Shinichi; Yan, Xing

2003-01-01

A program for test on rotor dynamics was planned for the turbo-machine of the Gas Turbine High Temperature Reactor (GTHTR300). The rotor system of the turbo-machine consists of a turbo-compressor rotor and a generator rotor connected with a flexible coupling, each suspended with two radial magnetic bearings. The rotors, which are flexible rotors, pass over the critical speeds of bending mode. The magnetic bearing is required to have a high load capacity, about 10 times larger than any built thus far to support a flexible rotor. In the rotor design, the standard limit of the vibration amplitude of 75 μm at the rated rotational speed of 3,600 rpm was fulfilled by optimizing the stiffness of the magnetic bearings. A test apparatus was designed to verify the design of the magnetic bearing suspended turbo-machine rotor of the GTHTR300. The test apparatus is composed of 1/3-scale test rotors, which are connected with a flexible coupling and driven by a variable speed motor. The test magnetic bearing was designed within the state-of-the-art technology to have a load capacity about 1/10 of that of the actual one. The test rotors were designed to closely simulate the critical speeds and vibration modes of the actual ones. This paper shows the test apparatus and the test plan for the magnetic bearing suspended rotor system. The present study is entrusted from the Ministry of Education, Culture, Sports, Science and Technology of Japan. (author)

Hydraulic and Mechanical Effects from Gas Hydrate Conversion and Secondary Gas Hydrate Formation during Injection of CO2 into CH4-Hydrate-Bearing Sediments

Science.gov (United States)

Bigalke, N.; Deusner, C.; Kossel, E.; Schicks, J. M.; Spangenberg, E.; Priegnitz, M.; Heeschen, K. U.; Abendroth, S.; Thaler, J.; Haeckel, M.

2014-12-01

The injection of CO2 into CH4-hydrate-bearing sediments has the potential to drive natural gas production and simultaneously sequester CO2 by hydrate conversion. The process aims at maintaining the in situ hydrate saturation and structure and causing limited impact on soil hydraulic properties and geomechanical stability. However, to increase hydrate conversion yields and rates it must potentially be assisted by thermal stimulation or depressurization. Further, secondary formation of CO2-rich hydrates from pore water and injected CO2 enhances hydrate conversion and CH4 production yields [1]. Technical stimulation and secondary hydrate formation add significant complexity to the bulk conversion process resulting in spatial and temporal effects on hydraulic and geomechanical properties that cannot be predicted by current reservoir simulation codes. In a combined experimental and numerical approach, it is our objective to elucidate both hydraulic and mechanical effects of CO2 injection and CH4-CO2-hydrate conversion in CH4-hydrate bearing soils. For the experimental approach we used various high-pressure flow-through systems equipped with different online and in situ monitoring tools (e.g. Raman microscopy, MRI and ERT). One particular focus was the design of triaxial cell experimental systems, which enable us to study sample behavior even during large deformations and particle flow. We present results from various flow-through high-pressure experimental studies on different scales, which indicate that hydraulic and geomechanical properties of hydrate-bearing sediments are drastically altered during and after injection of CO2. We discuss the results in light of the competing processes of hydrate dissociation, hydrate conversion and secondary hydrate formation. Our results will also contribute to the understanding of effects of temperature and pressure changes leading to dissociation of gas hydrates in ocean and permafrost systems. [1] Deusner C, Bigalke N, Kossel E

Magnetic bearings for free-piston Stirling engines

Science.gov (United States)

Curwen, P. W.; Fleming, D. P.; Rao, D. K.; Wilson, D. S.

1992-01-01

The feasibility and efficacy of applying magnetic bearings to free-piston Stirling-cycle power conversion machinery currently being developed for long-term space missions are assessed. The study was performed for a 50-kWe Reference Stirling Space Power Converter (RSSPC) which currently uses hydrostatic gas bearings to support the reciprocating displacer and power piston assemblies. Active magnetic bearings of the attractive electromagnetic type are feasible for the RSSPC power piston. Magnetic support of the displacer assembly would require unacceptable changes to the design of the current RSSPC. However, magnetic suspension of both displacer and power piston is feasible for a relative-displacer version of the RSSPC. Magnetic suspension of the RSSPC power piston can potentially increase overall efficiency by 0.5 to 1 percent (0.1 to 0.3 efficiency points). Magnetic bearings will also overcome several operational concerns associated with hydrostatic gas bearing systems. These advantages, however, are accompanied by a 5 percent increase in specific mass of the RSSPC.

Nonlinear dynamics of a vectored thrust aircraft

DEFF Research Database (Denmark)

Sørensen, C.B; Mosekilde, Erik

1996-01-01

With realistic relations for the aerodynamic coefficients, numerical simulations are applied to study the longitudional dynamics of a thrust vectored aircraft. As function of the thrust magnitude and the thrust vectoring angle the equilibrium state exhibits two saddle-node bifurcations and three...

Windage Power Loss in Gas Foil Bearings and the Rotor-Stator Clearance of High Speed Generators Operating in High Pressure Environments

Science.gov (United States)

Bruckner, Robert J.

2009-01-01

Closed Brayton Cycle (CBC) and Closed Supercritical Cycle (CSC) engines are prime candidates to convert heat from a reactor into electric power for robotic space exploration and habitation. These engine concepts incorporate a permanent magnet starter/generator mounted on the engine shaft along with the requisite turbomachinery. Successful completion of the long-duration missions currently anticipated for these engines will require designs that adequately address all losses within the machine. The preliminary thermal management concept for these engine types is to use the cycle working fluid to provide the required cooling. In addition to providing cooling, the working fluid will also serve as the bearing lubricant. Additional requirements, due to the unique application of these microturbines, are zero contamination of the working fluid and entirely maintenance-free operation for many years. Losses in the gas foil bearings and within the rotor-stator gap of the generator become increasingly important as both rotational speed and mean operating pressure are increased. This paper presents the results of an experimental study, which obtained direct torque measurements on gas foil bearings and generator rotor-stator gaps. Test conditions for these measurements included rotational speeds up to 42,000 revolutions per minute, pressures up to 45 atmospheres, and test gases of nitrogen, helium, and carbon dioxide. These conditions provided a maximum test Taylor number of nearly one million. The results show an exponential rise in power loss as mean operating density is increased for both the gas foil bearing and generator windage. These typical "secondary" losses can become larger than the total system output power if conventional design paradigms are followed. A nondimensional analysis is presented to extend the experimental results into the CSC range for the generator windage.

Toward the problem of oil and gas bearing capacity of the East Tom-Kolyvan structural zone (Western Siberia)

International Nuclear Information System (INIS)

Stolbova, N F; Maerkov, P O

2014-01-01

The vast depression in the east Tom-Kolyvan folded zone (West Siberia) has been identified by the geophysical data. The well which uncovered 4000 m deep profile of the Jurassic and Paleozoic deposits has been drilled. The relevance of the research is the oil/gas-bearing capacity evaluation of the discovered depression in this West Siberia area

Alternative model of thrust-fault propagation

Science.gov (United States)

Eisenstadt, Gloria; de Paor, Declan G.

1987-07-01

A widely accepted explanation for the geometry of thrust faults is that initial failures occur on deeply buried planes of weak rock and that thrust faults propagate toward the surface along a staircase trajectory. We propose an alternative model that applies Gretener's beam-failure mechanism to a multilayered sequence. Invoking compatibility conditions, which demand that a thrust propagate both upsection and downsection, we suggest that ramps form first, at shallow levels, and are subsequently connected by flat faults. This hypothesis also explains the formation of many minor structures associated with thrusts, such as backthrusts, wedge structures, pop-ups, and duplexes, and provides a unified conceptual framework in which to evaluate field observations.

Gas turbine drives

Energy Technology Data Exchange (ETDEWEB)

1981-01-01

Developments in gas turbine drives are reviewed, e.g., low weight per unit power and thrust-weight ratio, fast availability of the maximum speed, absolute resistance to cold and to droplet formation vibrationeless run, and low exhaust gas temperatures. Applications in aeronautic engineering (turbofan), power stations, marine propulsion systems, railways and road transportation vehicles are mentioned.

Metaheuristic and Machine Learning Models for TFE-731-2, PW4056, and JT8D-9 Cruise Thrust

Science.gov (United States)

Baklacioglu, Tolga

2017-08-01

The requirement for an accurate engine thrust model has a major antecedence in airline fuel saving programs, assessment of environmental effects of fuel consumption, emissions reduction studies, and air traffic management applications. In this study, utilizing engine manufacturers' real data, a metaheuristic model based on genetic algorithms (GAs) and a machine learning model based on neural networks (NNs) trained with Levenberg-Marquardt (LM), delta-bar-delta (DBD), and conjugate gradient (CG) algorithms were accomplished to incorporate the effect of both flight altitude and Mach number in the estimation of thrust. For the GA model, the analysis of population size impact on the model's accuracy and effect of number of data on model coefficients were also performed. For the NN model, design of optimum topology was searched for one- and two-hidden-layer networks. Predicted thrust values presented a close agreement with real thrust data for both models, among which LM trained NNs gave the best accuracies.

Thrust Control Loop Design for Electric-Powered UAV

Science.gov (United States)

Byun, Heejae; Park, Sanghyuk

2018-04-01

This paper describes a process of designing a thrust control loop for an electric-powered fixed-wing unmanned aerial vehicle equipped with a propeller and a motor. In particular, the modeling method of the thrust system for thrust control is described in detail and the propeller thrust and torque force are modeled using blade element theory. A relation between current and torque of the motor is obtained using an experimental setup. Another relation between current, voltage and angular velocity is also obtained. The electric motor and the propeller dynamics are combined to model the thrust dynamics. The associated trim and linearization equations are derived. Then, the thrust dynamics are coupled with the flight dynamics to allow a proper design for the thrust loop in the flight control. The proposed method is validated by an application to a testbed UAV through simulations and flight test.

Design of multi-input multi-output controller for magnetic bearing which suspends helium gas-turbine generator rotor for high temperature gas cooled reactor

International Nuclear Information System (INIS)

Takada, Shoji; Funatake, Yoshio; Inagaki, Yoshiyuki

2009-01-01

A design of a MIMO controller, which links magnetic forces of multiple magnetic bearings by feedback of multiple measurement values of vibration of a rotor, was proposed for the radial magnetic bearings for the generator rotor of helium gas turbine with a power output of 300 MWe. The generator rotor is a flexible rotor, which passes over the forth critical speed. A controller transfer function was derived at the forth critical speed, in which the bending vibration mode is similar to the one which is excited by unbalance mass to reduce a modeling error. A 1404-dimensional un-symmetric coefficient matrix of equation of state for the rotating rotor affected by Jayro effect was reduced by a modal decomposition using Schur decomposition to reduce a reduction error. The numerical results showed that unbalance response of rotor was 53 and 80 μm p-p , respectively, well below the allowable limits both at the rated and critical speeds. (author)

Tribo-characteristics of self-lubricating ball bearings for the LE-7 liquid hydrogen rocket-turbopump

Science.gov (United States)

Nosaka, Masataka; Oike, Mamoru; Kikuchi, Masataka; Kamijo, Kenjiro; Tajiri, Masanori

1993-07-01

The tribo characteristics of self-lubricating 40-mm-bore ball bearings with a retainer of glass cloth-polytetrafluoroethylene (PTFE) laminate, which has elliptical pockets with a large pocket clearance, were tested under thrust loads at speeds up to 50,000 rpm, 2 million DN, in liquid hydrogen (LH2) and in liquid nitrogen (LN2). During testing, the bearing torque, outer-race temperature, and electric resistance between the inner and outer races were monitored to verify the formation and rupture of a PTFE transfer film. Testing showed that the bearings having the elliptical retainer pockets were superior to the conventional bearings with circular pockets. It was determined that, at the maximum inner race spinning velocity of about 5 m/s, a PTFE transfer film could sustain the maximum Hertz stress, up to about 2000 N/sq mm, in LH2, without severe film rupture resulting in bearing seizure. In LN2, the critical load capacity of PTFE transfer film with bearing seizure was about 2700 N/sq mm.

Big Bear Exploration Ltd. 1998 annual report

International Nuclear Information System (INIS)

1999-01-01

During the first quarter of 1998 Big Bear completed a purchase of additional assets in the Rainbow Lake area of Alberta in which light oil purchase was financed with new equity and bank debt. The business plan was to immediately exploit these light oil assets, the result of which would be increased reserves, production and cash flow. Although drilling results in the first quarter on the Rainbow Lake properties was mixed, oil prices started to free fall and drilling costs were much higher than expected. As a result, the company completed a reduced program which resulted in less incremental loss and cash flow than it budgeted for. On April 29, 1998, Big Bear entered into agreement with Belco Oil and Gas Corp. and Moan Investments Ltd. for the issuance of convertible preferred shares at a gross value of $15,750,000, which shares were eventually converted at 70 cents per share to common equity. As a result of the continued plunge in oil prices, the lending value of the company's assets continued to fall, requiring it to take action in order to meet its financial commitments. Late in the third quarter Big Bear issued equity for proceeds of $11,032,000 which further reduced the company's debt. Although the company has been extremely active in identifying and pursuing acquisition opportunities, it became evident that Belco Oil and Gas Corp. and Big Bear did nor share common criteria for acquisitions, which resulted in the restructuring of their relationship in the fourth quarter. With the future of oil prices in question, Big Bear decided that it would change its focus to that of natural gas and would refocus ts efforts to acquire natural gas assets to fuel its growth. The purchase of Blue Range put Big Bear in a difficult position in terms of the latter's growth. In summary, what started as a difficult year ended in disappointment

Thermal conductivity of hydrate-bearing sediments

Science.gov (United States)

Cortes, Douglas D.; Martin, Ana I.; Yun, Tae Sup; Francisca, Franco M.; Santamarina, J. Carlos; Ruppel, Carolyn D.

2009-01-01

A thorough understanding of the thermal conductivity of hydrate-bearing sediments is necessary for evaluating phase transformation processes that would accompany energy production from gas hydrate deposits and for estimating regional heat flow based on the observed depth to the base of the gas hydrate stability zone. The coexistence of multiple phases (gas hydrate, liquid and gas pore fill, and solid sediment grains) and their complex spatial arrangement hinder the a priori prediction of the thermal conductivity of hydrate-bearing sediments. Previous studies have been unable to capture the full parameter space covered by variations in grain size, specific surface, degree of saturation, nature of pore filling material, and effective stress for hydrate-bearing samples. Here we report on systematic measurements of the thermal conductivity of air dry, water- and tetrohydrofuran (THF)-saturated, and THF hydrate–saturated sand and clay samples at vertical effective stress of 0.05 to 1 MPa (corresponding to depths as great as 100 m below seafloor). Results reveal that the bulk thermal conductivity of the samples in every case reflects a complex interplay among particle size, effective stress, porosity, and fluid-versus-hydrate filled pore spaces. The thermal conductivity of THF hydrate–bearing soils increases upon hydrate formation although the thermal conductivities of THF solution and THF hydrate are almost the same. Several mechanisms can contribute to this effect including cryogenic suction during hydrate crystal growth and the ensuing porosity reduction in the surrounding sediment, increased mean effective stress due to hydrate formation under zero lateral strain conditions, and decreased interface thermal impedance as grain-liquid interfaces are transformed into grain-hydrate interfaces.

Bearing development program for a 25 kWe solar-powered organic Rankine-cycle engine

Science.gov (United States)

Nesmith, B.

1985-01-01

The bearing development program is summarized for a 25-kWe power conversion subsystem (PCS) consisting of an organic Rankine-cycle engine, and permanent magnetic alternator (PMA) and rectifier to be used in a 100-kWe point-focusing distributed receiver solar power plant. The engine and alternator were hermetically sealed and used toluene as the working fluid. The turbine, alternator, and feed pump (TAP) were mounted on a single shaft operating at speeds up to 60,000 rev/min. Net thermal-to-electric efficiencies in the range of 21 to 23% were demonstrated at the maximum working fluid temperature of 400 C (750 F). A chronological summary of the bearing development program is presented. The primary causes of bearing wear problems were traced to a combination of rotordynamic instability and electrodynamic discharge across the bearing surfaces caused by recirculating currents from the PMA. These problems were resolved by implementing an externally supplied, flooded-bearing lubrication system and by electrically insulating all bearings from the TAP housing. This program resulted in the successful development of a stable, high-speed, toluene-lubricated five-pad tilting-pad journal bearing and Rayleigh step thrust bearing system capable of operating at all inclinations between horizontal and vertical.

Shock unsteadiness in a thrust optimized parabolic nozzle

Science.gov (United States)

Verma, S. B.

2009-07-01

This paper discusses the nature of shock unsteadiness, in an overexpanded thrust optimized parabolic nozzle, prevalent in various flow separation modes experienced during start up {(δ P0 /δ t > 0)} and shut down {(δ P0/δ t The results are based on simultaneously acquired data from real-time wall pressure measurements using Kulite pressure transducers, high-speed schlieren (2 kHz) of the exhaust flow-field and from strain-gauges installed on the nozzle bending tube. Shock unsteadiness in the separation region is seen to increase significantly just before the onset of each flow transition, even during steady nozzle operation. The intensity of this measure ( rms level) is seen to be strongly influenced by relative locations of normal and overexpansion shock, the decrease in radial size of re-circulation zone in the back-flow region, and finally, the local nozzle wall contour. During restricted shock separation, the pressure fluctuations in separation region exhibit periodic characteristics rather than the usually observed characteristics of intermittent separation. The possible physical mechanisms responsible for the generation of flow unsteadiness in various separation modes are discussed. The results are from an experimental study conducted in P6.2 cold-gas subscale test facility using a thrust optimized parabolic nozzle of area-ratio 30.

Thermal barrier coatings (TBC's) for high heat flux thrust chambers

Science.gov (United States)

Bradley, Christopher M.

The last 30 years materials engineers have been under continual pressure to develop materials with a greater temperature potential or to produce configurations that can be effectively cooled or otherwise protected at elevated temperature conditions. Turbines and thrust chambers produce some of the harshest service conditions for materials which lead to the challenges engineers face in order to increase the efficiencies of current technologies due to the energy crisis that the world is facing. The key tasks for the future of gas turbines are to increase overall efficiencies to meet energy demands of a growing world population and reduce the harmful emissions to protect the environment. Airfoils or blades tend to be the limiting factor when it comes to the performance of the turbine because of their complex design making them difficult to cool as well as limitations of their thermal properties. Key tasks for space transportation it to lower costs while increasing operational efficiency and reliability of our space launchers. The important factor to take into consideration is the rocket nozzle design. The design of the rocket nozzle or thrust chamber has to take into account many constraints including external loads, heat transfer, transients, and the fluid dynamics of expanded hot gases. Turbine engines can have increased efficiencies if the inlet temperature for combustion is higher, increased compressor capacity and lighter weight materials. In order to push for higher temperatures, engineers need to come up with a way to compensate for increased temperatures because material systems that are being used are either at or near their useful properties limit. Before thermal barrier coatings were applied to hot-section components, material alloy systems were able to withstand the service conditions necessary. But, with the increased demand for performance, higher temperatures and pressures have become too much for those alloy systems. Controlled chemistry of hot

Multiscale characterization of White Etching Cracks (WEC) in a 100Cr6 bearing from a thrust bearing test rig

DEFF Research Database (Denmark)

Danielsen, Hilmar Kjartansson; Guzmán, F. Gutiérrez; Dahl, Kristian Vinter

2017-01-01

A common cause for premature bearing failures in wind turbine gearboxes are the so-called White Etching Cracks (WEC). These undirected, three-dimensional cracks are bordered by regions of altered microstructure and ultimately lead to a cracking or spalling of the raceway. An accelerated WEC test...... significant grain refinement. Atom probe tomography showed the microstructure in the undamaged zone has a plate-like martensitic structure with carbides, while no carbides were detected in the WEA where the microstructure consisted of equiaxed 10 nm grains. A three dimensional characterisation of WEC network...

A bibliographic survey of bearings for nuclear reactors

International Nuclear Information System (INIS)

Nemoto, Masaaki; Okamoto, Yoshizo

1977-03-01

In development of a multi-purpose high-temperature gas cooled reactor, design of its mechanical elements is essential. Machinery must be safely operable in the high temperature (1,000 0 C), high pressure (40kg/cm 2 ) helium environment for long time. A bibliographic review in this connection with technical reports, books, journals and patents, is presented, using NSA. As an element of the machinery bearings are classified into several categories, a bibliography on gas-lubricated bearings for 207 documents is given in chronical order. (auth.)

Initiation process of a thrust fault revealed by analog experiments

Science.gov (United States)

Yamada, Yasuhiro; Dotare, Tatsuya; Adam, Juergen; Hori, Takane; Sakaguchi, Hide

2016-04-01

We conducted 2D (cross-sectional) analog experiments with dry sand using a high resolution digital image correlation (DIC) technique to reveal initiation process of a thrust fault in detail, and identified a number of "weak shear bands" and minor uplift prior to the thrust initiation. The observations suggest that the process can be divided into three stages. Stage 1: characterized by a series of abrupt and short-lived weak shear bands at the location where the thrust will be generated later. Before initiation of the fault, the area to be the hanging wall starts to uplift. Stage 2: defined by the generation of the new thrust and its active displacement. The location of the new thrust seems to be constrained by its associated back-thrust, produced at the foot of the surface slope (by the previous thrust). The activity of the previous thrust turns to zero once the new thrust is generated, but the timing of these two events is not the same. Stage 3: characterized by a constant displacement along the (new) thrust. Similar minor shear bands can be seen in the toe area of the Nankai accretionary prism, SW Japan and we can correlate the along-strike variations in seismic profiles to the model results that show the characteristic features in each thrust development stage.

Evaluation of cermet materials suitable for lithium lubricated thrust bearings for high temperature operation

Science.gov (United States)

Sinclair, J. H.; Hendrixson, W. H.

1974-01-01

Cerment materials (HfC - 10 wt% W; HfC - 10 wt% TaC - 10 wt%W; HfC - 2 wt% CbC - 8 wt% Mo;Hfn - 10 wt% W; Hfn - 10 wt% TaN - 10 wt% W; and ZrC - 17 wt% W) were evaluated for possible use as lithium-lubricated bearings in the control system of a nuclear reactor. Tests of compatibility with lithium were made in T-111 (Ta-8W-2Hf) capsules at temperatures up to 1090 C. The tendencies of HfC-TaC-W, HfC-CbC-Mo, and HfN-W to bond to themselves and to the refractory alloys T-111 and TZM when enclosed in lithium-filled capsules under a pressure of 2000 psi at 980 and 1200 C for 1933 hours were evaluated. Thermal expansion characteristics were determined for the same three materials from room temperature to 1200 C. On the basis of these tests, HfC-10 TaC-10W and HfN-10W were selected as the best and second best candidates, respectively, of the materials tested for the bearing application.

Nanonewton thrust measurement of photon pressure propulsion using semiconductor laser

Science.gov (United States)

Iwami, K.; Akazawa, Taku; Ohtsuka, Tomohiro; Nishida, Hiroyuki; Umeda, Norihiro

2011-09-01

To evaluate the thrust produced by photon pressure emitted from a 100 W class continuous-wave semiconductor laser, a torsion-balance precise thrust stand is designed and tested. Photon emission propulsion using semiconductor light sources attract interests as a possible candidate for deep-space propellant-less propulsion and attitude control system. However, the thrust produced by photon emission as large as several ten nanonewtons requires precise thrust stand. A resonant method is adopted to enhance the sensitivity of the biflier torsional-spring thrust stand. The torsional spring constant and the resonant of the stand is 1.245 × 10-3 Nm/rad and 0.118 Hz, respectively. The experimental results showed good agreement with the theoretical estimation. The thrust efficiency for photon propulsion was also defined. A maximum thrust of 499 nN was produced by the laser with 208 W input power (75 W of optical output) corresponding to a thrust efficiency of 36.7%. The minimum detectable thrust of the stand was estimated to be 2.62 nN under oscillation at a frequency close to resonance.

Thrust evaluation of magneto plasma sail that obtains an electromagnetic thrust from the solar wind

International Nuclear Information System (INIS)

Kajimura, Yoshihiro; Funaki, Ikkoh; Usui, Hideyuki; Yamakawa, Hiroshi

2011-01-01

Magneto Plasma Sail (MPS) is a propulsion system used in space, which generates its force by the interaction between the solar wind and an inflated magnetic field via a plasma injection. The quantitative evaluation of the thrust increment generated by injecting a plasma jet with a β in less than unity was conducted by three-dimensional hybrid particle-in-cell (PIC) simulations in an ion inertia scale. The injected plasma β in is 0.02 and the ratio of Larmor radius of injected ion to the representative length of the magnetic field is 0.5 at the injection point. In this situation, the obtained thrust of the MPS is 1.6 mN compared with the 0.2 mN of the thrust obtained by the pure magnetic sail since the induced current region on magnetosphere expanded by the magnetic inflation. (author)

Transient analysis of blowdown thrust force under PWR LOCA

International Nuclear Information System (INIS)

Yano, Toshikazu; Miyazaki, Noriyuki; Isozaki, Toshikuni

1982-10-01

The analytical results of blowdown characteristics and thrust forces were compared with the experiments, which were performed as pipe whip and jet discharge tests under the PWR LOCA conditions. The blowdown thrust forces obtained by Navier-Stokes momentum equation about a single-phase, homogeneous and separated two-phase flow, assuming critical pressure at the exit if a critical flow condition was satisfied. The following results are obtained. (1) The node-junction method is useful for both the analyses of the blowdown thrust force and of the water hammer phenomena. (2) The Henry-Fauske model for subcooled critical flow is effective for the analysis of the maximum thrust force under the PWR LOCA conditions. The jet thrust parameter of the analysis and experiment is equal to 1.08. (3) The thrust parameter of saturated blowdown has the same one with the value under pressurized condition when the stagnant pressure is chosen as the saturated one. (4) The dominant terms of the blowdown thrust force in the momentum equation are the pressure and momentum terms except that the acceleration term has large contribution only just after the break. (5) The blowdown thrust force in the analysis greatly depends on the selection of the exit pressure. (author)

Design and Operating Characteristics of High-Speed, Small-Bore, Angular-Contact Ball Bearings

Science.gov (United States)

Pinel, Stanley I.; Signer, Hans R.; Zaretsky, Erwin V.

1998-01-01

The computer program SHABERTH was used to analyze 35-mm-bore, angular-contact ball bearings designed and manufactured for high-speed turbomachinery applications. Parametric tests of the bearings were conducted on a high-speed, high-temperature bearing tester and were compared with the computer predictions. Four bearing and cage designs were studied. The bearings were lubricated either by jet lubrication or through the split inner ring with and without outer-ring cooling. The predicted bearing life decreased with increasing speed because of increased operating contact stresses caused by changes in contact angle and centrifugal load. For thrust loads only, the difference in calculated life for the 24 deg. and 30 deg. contact-angle bearings was insignificant. However, for combined loading, the 24 deg. contact-angle bearing gave longer life. For split-inner-ring bearings, optimal operating conditions were obtained with a 24 deg. contact angle and an inner-ring, land-guided cage, using outer-ring cooling in conjunction with low lubricant flow rates. Lower temperature and power losses were obtained with a single-outer-ring, land-guided cage for the 24 deg. contact-angle bearing having a relieved inner ring and partially relieved outer ring. Inner-ring temperatures were independent of lubrication mode and cage design. In comparison with measured values, reasonably good engineering correlation was obtained using the computer program SHABERTH for predicted bearing power loss and for inner- and outer-ring temperatures. The Parker formula for XCAV (used in SHABERTH, a measure of oil volume in the bearing cavity) may need to be refined to reflect bearing lubrication mode, cage design, and location of cage-controlling land.

Distributed deformation in the Zagros fold-and-thrust belt: insights from geomorphology

Science.gov (United States)

Obaid, Ahmed; Allen, Mark

2017-04-01

The Zagros fold-and-thrust belt is part of the active Arabia-Eurasia collision zone, and is an excellent region to study the interactions of tectonics and landscape. In this work we present results of a geomorphic analysis covering the entire range, coupled with more detailed analysis of the Kirkuk Embayment, Iraq. This particular region is a low elevation, low relief region of the Zagros, important for the enormous oil and gas reserves held in late Cenozoic anticlinal traps. Constraints from published earthquake focal mechanisms and hydrocarbon industry sub-surface data are combined with original fieldwork observations in northern Iraq, to produce a new regional cross-section and structural interpretation for the Kirkuk Embayment. We find that overall late Cenozoic shortening across the Embayment is on the order of 5%, representing only a few km. This deformation takes place on a series of anticlines, which are interpreted as overlying steep, planar, basement thrusts. These thrusts are further interpreted as reactivated normal faults, on the basis of (rare) published seismic data. The regional earthquake record confirms the basement involvement, although detachments within the sedimentary succession are also important, especially within the Middle Miocene Fat'ha Formation. Overall, the Zagros is sometimes represented as having a few major thrusts each persistent for 100s of km along the strike of the range. However, these faults are very rarely associated with major structural relief and/or surface fault ruptures during earthquakes. We have analysed the hypsometry of the range and find only gradational changes in the hypsometric integral of drainage basins across strike. This contrasts with regions such as the eastern Tibetan Plateau, where published analysis has revealed abrupt changes, correlating with the surface traces of active thrusts. Our interpretation is that the hypsometry of the Zagros reflects distributed deformation on numerous smaller faults, rather

Aircraft Engine Thrust Estimator Design Based on GSA-LSSVM

Science.gov (United States)

Sheng, Hanlin; Zhang, Tianhong

2017-08-01

In view of the necessity of highly precise and reliable thrust estimator to achieve direct thrust control of aircraft engine, based on support vector regression (SVR), as well as least square support vector machine (LSSVM) and a new optimization algorithm - gravitational search algorithm (GSA), by performing integrated modelling and parameter optimization, a GSA-LSSVM-based thrust estimator design solution is proposed. The results show that compared to particle swarm optimization (PSO) algorithm, GSA can find unknown optimization parameter better and enables the model developed with better prediction and generalization ability. The model can better predict aircraft engine thrust and thus fulfills the need of direct thrust control of aircraft engine.

Experimental Investigations of Decentralised Control Design for The Stabilisation of Rotor-Gas Bearings

DEFF Research Database (Denmark)

Theisen, Lukas Roy Svane; Galeazzi, Roberto; Niemann, Hans Henrik

2015-01-01

frequencies. Active lubrication of the journal during operations could enhance the damping and stabilisation characteristics of the sytems, and this could be achieved by means of stabilising controllers. This paper investigates the feasibility of using reduced order models obtained through Grey......-Box identification for the design of stabilising controllers, capable of enabling the active lubrication of the journal. The root locus analysis shows that two different control solutions are feasible for the dampening of the first two eigenfrequencies of the rotor-gas bearing in the horizontal and vertical...... directions. Hardening and softening P-lead controllers are designed based on the models experimentally identified, and salient features of both controllers are discussed. Both controllers are implemented and validated on the physical test rig. Experimental results confirm the validity of the proposed...

Hydrodynamic aspects of thrust generation in gymnotiform swimming

Science.gov (United States)

Shirgaonkar, Anup A.; Curet, Oscar M.; Patankar, Neelesh A.; Maciver, Malcolm A.

2008-11-01

The primary propulsor in gymnotiform swimmers is a fin running along most of the ventral midline of the fish. The fish propagates traveling waves along this ribbon fin to generate thrust. This unique mode of thrust generation gives these weakly electric fish great maneuverability cluttered spaces. To understand the mechanical basis of gymnotiform propulsion, we investigated the hydrodynamics of a model ribbon-fin of an adult black ghost knifefish using high-resolution numerical experiments. We found that the principal mechanism of thrust generation is a central jet imparting momentum to the fluid with associated vortex rings near the free edge of the fin. The high-fidelity simulations also reveal secondary vortex rings potentially useful in rapid sideways maneuvers. We obtained the scaling of thrust with respect to the traveling wave kinematic parameters. Using a fin-plate model for a fish, we also discuss improvements to Lighthill's inviscid theory for gymnotiform and balistiform modes in terms of thrust magnitude, viscous drag on the body, and momentum enhancement.

Measuring Model Rocket Engine Thrust Curves

Science.gov (United States)

Penn, Kim; Slaton, William V.

2010-01-01

This paper describes a method and setup to quickly and easily measure a model rocket engine's thrust curve using a computer data logger and force probe. Horst describes using Vernier's LabPro and force probe to measure the rocket engine's thrust curve; however, the method of attaching the rocket to the force probe is not discussed. We show how a…

Use of structured surfaces for friction and wear control on bearing surfaces

International Nuclear Information System (INIS)

Wang, Ling

2014-01-01

Surface texturing with purposely made regular micropatterns on flat or curved surfaces, as opposed to random roughness inherited from machining processes, has attracted significant attention in recent years. At the 2013 World Tribology Congress in Turin alone there were over 40 presentations related to surface texturing for tribological applications, from magnetic hard discs and hydrodynamic bearings to artificial joints. Although surface texturing has been reported being successfully applied in industrial applications such as seals, pistons, and thrust pad bearings, the demand for robust design is still high. Etsion has recently reviewed the modeling research mainly conducted by his group Etsion I (2013 Friction 1 195–209). This paper aims to review the state-of-the-art development of surface texturing made by a wider range of researchers. (topical review)

Using U-Th-Pb petrochronology to determine rates of ductile thrusting: Time windows into the Main Central Thrust, Sikkim Himalaya

Science.gov (United States)

Mottram, Catherine M.; Parrish, Randall R.; Regis, Daniele; Warren, Clare J.; Argles, Tom W.; Harris, Nigel B. W.; Roberts, Nick M. W.

2015-07-01

Quantitative constraints on the rates of tectonic processes underpin our understanding of the mechanisms that form mountains. In the Sikkim Himalaya, late structural doming has revealed time-transgressive evidence of metamorphism and thrusting that permit calculation of the minimum rate of movement on a major ductile fault zone, the Main Central Thrust (MCT), by a novel methodology. U-Th-Pb monazite ages, compositions, and metamorphic pressure-temperature determinations from rocks directly beneath the MCT reveal that samples from 50 km along the transport direction of the thrust experienced similar prograde, peak, and retrograde metamorphic conditions at different times. In the southern, frontal edge of the thrust zone, the rocks were buried to conditions of 550°C and 0.8 GPa between 21 and 18 Ma along the prograde path. Peak metamorphic conditions of 650°C and 0.8-1.0 GPa were subsequently reached as this footwall material was underplated to the hanging wall at 17-14 Ma. This same process occurred at analogous metamorphic conditions between 18-16 Ma and 14.5-13 Ma in the midsection of the thrust zone and between 13 Ma and 12 Ma in the northern, rear edge of the thrust zone. Northward younging muscovite 40Ar/39Ar ages are consistently 4 Ma younger than the youngest monazite ages for equivalent samples. By combining the geochronological data with the >50 km minimum distance separating samples along the transport axis, a minimum average thrusting rate of 10 ± 3 mm yr-1 can be calculated. This provides a minimum constraint on the amount of Miocene India-Asia convergence that was accommodated along the MCT.

Uranium favorability of tertiary rocks in the Badger Flats, Elkhorn Thrust Area, Park and Teller Counties, Colorado

International Nuclear Information System (INIS)

Young, P.; Mickle, D.G.

1976-10-01

Uranium potential of Tertiary rocks in the Badger Flats--Elkhorn Thrust area of central Colorado is closely related to a widespread late Eocene erosion surface. Most uranium deposits in the area are in the Eocene Echo Park Alluvium and Oligocene Tallahassee Creek Conglomerate, which were deposited in paleodrainage channels on or above this surface. Arkosic detritus within the channels and overlying tuffaceous sedimentary rocks of the Antero and Florissant Formations of Oligocene age and silicic tuffs within the volcanic units provide abundant sources of uranium that could be concentrated in the channels where carbonaceous debris facilitates a reducing environment. Anomalous soil, water, and stream-sediment samples near the Elkhorn Thrust and in Antero basin overlie buried channels or are offset from them along structural trends; therefore, uranium-bearing ground water may have moved upward from buried uranium deposits along faults. The area covered by rocks younger than the late Eocene erosion surface, specifically the trends of mapped or inferred paleochannels filled with Echo Park Alluvium and Tallahassee Creek Conglomerate, and the Antero Formation are favorable for the occurrence of uranium deposits

Axisymmetric thrust-vectoring nozzle performance prediction

International Nuclear Information System (INIS)

Wilson, E. A.; Adler, D.; Bar-Yoseph, P.Z

1998-01-01

Throat-hinged geometrically variable converging-diverging thrust-vectoring nozzles directly affect the jet flow geometry and rotation angle at the nozzle exit as a function of the nozzle geometry, the nozzle pressure ratio and flight velocity. The consideration of nozzle divergence in the effective-geometric nozzle relation is theoretically considered here for the first time. In this study, an explicit calculation procedure is presented as a function of nozzle geometry at constant nozzle pressure ratio, zero velocity and altitude, and compared with experimental results in a civil thrust-vectoring scenario. This procedure may be used in dynamic thrust-vectoring nozzle design performance predictions or analysis for civil and military nozzles as well as in the definition of initial jet flow conditions in future numerical VSTOL/TV jet performance studies

Investigation of the mechanical behaviour of gas-hydrate bearing clayey sediments from the Gulf of Guinea using in-situ geotechnical measurements

Science.gov (United States)

Taleb, F.; Garziglia, S.; Sultan, N.

2017-12-01

Expanding needs for energy resources and concerns about climate change have moved industrial and academic interests towards regions where specific thermobaric conditions allow the formation of gas hydrates (GH). While significant advances have been made to characterize the fabric and structure of these metastable geo-compounds, considerable uncertainty remains regarding the impact of their mechanical properties on the seafloor morphology and stability. This is particularly true for gas hydrates-bearing fine-grained sediments, which remain challenging to preserve or synthesise prior to laboratory testing. As a step towards understanding the mechanical consequences of the concentration and distribution of GH in this type of sediments, this work uses acoustic and geotechnical in situ measurements collected in a high gas flux system offshore Nigeria. Acoustic measurements of compressional wave velocity were shown to be convenient means of both detecting and quantifying gas hydrates in marine sediments. Geotechnical data derived from piezocone readings and their distribution in normalised soil classification charts allowed identifying distinct features of gas hydrates-bearing clayey sediments; such as a mechanical behaviour sharing similarities with that of cemented clays. Correlations between acoustic and piezocone data showed that the stiffness and strength tend to generally increase with increasing GH concentrations. However, several sediment intervals sharing the same hydrates concentration have revealed different features of mechanical behaviour. This was linked to the presence of various GH morphologies within the marine sediments such as groups of hydrate veins or massive hydrate nodules. This in-situ approach allowing both understanding the heterogeneous distribution of GH and characterising their host sediment seems key to assess the potential link between seafloor stability and GH dissociation/dissolution caused by human activities or by natural environmental

A Three-Dimensional Foil Bearing Performance Map Applied to Oil-Free Turbomachinery

Science.gov (United States)

2009-04-01

stress brought on by excessive viscous power loss; therefore a map that graphically relates component and system-level parameters (bearing size, applied...Introduction Foil bearings are self-acting, hydrodynamic gas bearings that use air as their working fluid . Their use in rotating systems eliminates the...weight, maintenance requirements, speed, and temperature limitations associated with conventional oil-lubricated rotor supports (i.e., bearings, dampers

Forecasting sandstone uranium deposits in oil-and-gas bearing basins

International Nuclear Information System (INIS)

Pechenkin, I.

2014-01-01

The interrelation between oxidation and reduction processes in the carbonaceous strata of Paleogene age was first studied in the 1950s in deposit of the Fergana depression. The presence of pre-ore and post-ore epigenesis of petroleum series was established. Part of uranium mineralization was found to be covered with fluid oil. In the middle of the 1960s in the Sabirsay deposit (Uzbekistan) in primary red-coloured continental sediment of Cretaceous age were studied pre-ore reduction changes, which caused economic uranium mineralization in contrasting geochemical barrier. Further research showed that multidirectional epigenetic processes had changed repeatedly. Later, in the 1970s, American geologists studying uranium deposits in the oil-and-gas bearing Texas Plain reached similar conclusions. From their point of view, in the Benevides deposit the main zones of mineralization tend to be located near the boundary where the zones of oxidation in the strata wedge in, developing in epigenetically reduced formations. A second post-mineral reduction was registered in a number of rock bodies. The complexity of the processes is determined by the double role of hydrocarbon fluids and the products of their dissolution. On the one hand, bituminization of permeable strata as well as pyritization, chloritization, dolomitization and other alterations associated with it create favourable geochemical conditions of a reducing character for a subsequent concentration of ore and nonmetal raw materials. On the other hand, intrusion of bitumen and its dissolution in the aeration zone leads to the burial of the mineralization which formed earlier and disappearance of all traces of its formation (epigenetic oxidation zoning). Thus forecasting and subsequent prospecting become impeded. The established sequence of epigenetic alterations allows us to carry out specialized mapping in productive regions, uncovering hidden parts of epigenetic oxidation zoning and “buried” mineralization

Thrust sensing for small UAVs

Science.gov (United States)

Marchman, Christopher Scott

Unmanned aerial vehicles (UAVs) have become prevalent in both military and civilian applications. UAVs have many size categories from large-scale aircraft to micro air vehicles. The performance, health, and efficiency for UAVs of smaller sizes can be difficult to assess and few associated instrumentation systems have been developed. Thrust measurements on the ground can characterize systems especially when combined with simultaneous motor power measurements. This thesis demonstrates the use of strain measurements to measure the thrust produced by motor/propeller combinations for such small UAVs. A full-bridge Wheatstone circuit and electrical resistance strain gauges were used in conjunction with constant-stress cantilever beams for static tests and dynamic wind tunnel tests. An associated instrumentation module monitored power from the electric motor. Monitoring the thrust data over time can provide insights into optimal propeller and motor selection and early detection of problems such as component failure. The approach provides a system for laboratory or field measurements that can be scaled for a wide range of small UAVs.

Identifying polar bear resource selection patterns to inform offshore development in a dynamic and changing Arctic

Science.gov (United States)

Wilson, Ryan R.; Horne, Jon S.; Rode, Karyn D.; Regehr, Eric V.; Durner, George M.

2014-01-01

Although sea ice loss is the primary threat to polar bears (Ursus maritimus), little can be done to mitigate its effects without global efforts to reduce greenhouse gas emissions. Other factors, however, could exacerbate the impacts of sea ice loss on polar bears, such as exposure to increased industrial activity. The Arctic Ocean has enormous oil and gas potential, and its development is expected to increase in the coming decades. Estimates of polar bear resource selection will inform managers how bears use areas slated for oil development and to help guide conservation planning. We estimated temporally-varying resource selection patterns for non-denning adult female polar bears in the Chukchi Sea population (2008–2012) at two scales (i.e., home range and weekly steps) to identify factors predictive of polar bear use throughout the year, before any offshore development. From the best models at each scale, we estimated scale-integrated resource selection functions to predict polar bear space use across the population's range and determined when bears were most likely to use the region where offshore oil and gas development in the United States is slated to occur. Polar bears exhibited significant intra-annual variation in selection patterns at both scales but the strength and annual patterns of selection differed between scales for most variables. Bears were most likely to use the offshore oil and gas planning area during ice retreat and growth with the highest predicted use occurring in the southern portion of the planning area. The average proportion of predicted high-value habitat in the planning area was >15% of the total high-value habitat for the population during sea ice retreat and growth and reached a high of 50% during November 2010. Our results provide a baseline on which to judge future changes to non-denning adult female polar bear resource selection in the Chukchi Sea and help guide offshore development in the region. Lastly, our study provides a

Tracing the Origins of Nitrogen Bearing Organics Toward Orion KL with Alma

Science.gov (United States)

Carroll, Brandon; Crockett, Nathan; Wilkins, Olivia H.; Bergin, Edwin; Blake, Geoffrey

2017-06-01

A comprehensive analysis of a broadband 1.2 THz wide spectral survey of the Orion Kleinmann-Low nebula (Orion KL) has shown that nitrogen bearing complex organics trace systematically hotter gas than O-bearing organics toward this source. The origin of this O/N dichotomy remains a mystery. If complex molecules originate from grain surfaces, N-bearing species may be more difficult to remove from grain surfaces than O-bearing organics. Theoretical studies, however, have shown that hot (T=300 K) gas phase chemistry can produce high abundances of N-bearing organics while suppressing the formation of O-bearing complex molecules. In order to distinguish these distinct formation pathways we have obtained extremely high angular resolution observations of methyl cyanide (CH_3CN) using the Atacama Large Millimeter/Submillimeter Array (ALMA) toward Orion KL. By simultaneously imaging ^{13}CH_3CN and CH_2DCN we map the temperature structure and D/H ratio of CH_3CN. We will present updated results of these observations and discuss their implications for the formation of N-bearing organics in the interstellar medium.

On the stability analysis of flexible rotors supported by Hybrid Aerostatic - Gas Journal Bearings

DEFF Research Database (Denmark)

Morosi, Stefano; Santos, Ilmar

Modern turbo-machinery applications, high speed machine tools, laboratory equipment require nowadays ever-growing rotational speeds and high degree of precision and reliability. Gas journal bearing have been in many extents employed as they meet the demands of performing at high speeds, in clean...... environment and great efficiency. However, the drawback are inherent poor carrying capacity and dynamic characteristics of passive systems, which often translate to a reduced range of stability. In order to enhance these characteristics, one solution is to combine the hydrodynamic effect with the addition...... form of the compressible Reynolds equation for active lubrication is derived. Particular attention is given to the injections terms and a comparison is carried on between fully nonlinear and linearized expressions. By solving this equation, stiffness and damping coefficients can be determined...

Dynamic Imbalance Would Counter Offcenter Thrust

Science.gov (United States)

Mccanna, Jason

1994-01-01

Dynamic imbalance generated by offcenter thrust on rotating body eliminated by shifting some of mass of body to generate opposing dynamic imbalance. Technique proposed originally for spacecraft including massive crew module connected via long, lightweight intermediate structure to massive engine module, such that artificial gravitation in crew module generated by rotating spacecraft around axis parallel to thrust generated by engine. Also applicable to dynamic balancing of rotating terrestrial equipment to which offcenter forces applied.

'Dodo' and 'Baby Bear' Trenches

Science.gov (United States)

2008-01-01

NASA's Phoenix Mars Lander's Surface Stereo Imager took this image on Sol 11 (June 5, 2008), the eleventh day after landing. It shows the trenches dug by Phoenix's Robotic Arm. The trench on the left is informally called 'Dodo' and was dug as a test. The trench on the right is informally called 'Baby Bear.' The sample dug from Baby Bear will be delivered to the Phoenix's Thermal and Evolved-Gas Analyzer, or TEGA. The Baby Bear trench is 9 centimeters (3.1 inches) wide and 4 centimeters (1.6 inches) deep. The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

Thrust calculation of electric solar wind sail by particle-in-cell simulation

Energy Technology Data Exchange (ETDEWEB)

Hoshi, Kento [Kyoto Univ. (Japan). Dept. of Electrical Engineering; Kojima, Hirotsugu; Yamakawa, Hiroshi [Kyoto Univ. (Japan). Research Inst. for Sustainable Humanosphere; Muranaka, Takanobu [Chukyo Univ., Nagoya (Japan). Dept. of Electrical Engineering

2016-07-01

In this study, thrust characteristics of an electric solar wind sail were numerically evaluated using full threedimensional particle-in-cell (PIC) simulation. The thrust obtained from the PIC simulation was lower than the thrust estimations obtained in previous studies. The PIC simulation indicated that ambient electrons strongly shield the electrostatic potential of the tether of the sail, and the strong shield effect causes a greater thrust reduction than has been obtained in previous studies. Additionally, previous expressions of the thrust estimation were modified by using the shielded potential structure derived from the present simulation results. The modified thrust estimation agreed very well with the thrust obtained from the PIC simulation.

Thrust calculation of electric solar wind sail by particle-in-cell simulation

International Nuclear Information System (INIS)

Hoshi, Kento; Kojima, Hirotsugu; Yamakawa, Hiroshi; Muranaka, Takanobu

2016-01-01

In this study, thrust characteristics of an electric solar wind sail were numerically evaluated using full threedimensional particle-in-cell (PIC) simulation. The thrust obtained from the PIC simulation was lower than the thrust estimations obtained in previous studies. The PIC simulation indicated that ambient electrons strongly shield the electrostatic potential of the tether of the sail, and the strong shield effect causes a greater thrust reduction than has been obtained in previous studies. Additionally, previous expressions of the thrust estimation were modified by using the shielded potential structure derived from the present simulation results. The modified thrust estimation agreed very well with the thrust obtained from the PIC simulation.

Radiometric Dating of Folds: A new approach to determine the timing of deformation at shallow-crustal conditions, with examples from the Mexican Fold-Thrust Belt

Science.gov (United States)

Fitz Diaz, E.; van der Pluijm, B. A.

2012-12-01

We are developing a robust method to obtain absolute ages of folds that were formed at shallow crustal conditions. The method takes advantage of illite neocrystallization in folded, clay-bearing layers and the ability to obtain accurate retention and total gas ages from small size fractions using encapsulated Ar analysis, analogous to prior work on fault gouge dating. We illustrate our approach in folded Cretaceous shale-bentonitic layers that are interbedded with carbonates of the Zimapán and the Tampico-Misantla cretaceous basins in central-eastern Mexico. Basinal carbonates were buried by syntectonic turbidites and inverted during the formation of the Mexican Fold-Thrust in the Late Cretaceous. Results were obtained from four chevron folds that are representative of different stages of deformation, burial/temperature conditions and location within this thin-skinned orogenic wedge: two from the Zimapán Basin (Folds 1 and 2) in the west and two from the Tampico-Misantla Basin (Folds 3 and 4) in the east. Mineralogic compositions and variations in illite-polytypes, crystallite-size (CS) and Ar/Ar ages were obtained from size fractions in limbs and hinges of folded layers. Ar retention ages produce a folding age of ~81 Ma for Fold 1 and ~69 Ma for Fold 2, which are fully consistent with stratigraphic limits from syn-orogenic turbidities and observed overprinting events in the Mexican Fold-Thrust Belt. The total gas age of Fold 3, on the easternmost margin of the Tampico-Misantla Basin is similar to that of Fold 2, indicating that the second event is regional in scale. In addition to presenting a new, reliable method to constrain the timing of local deformation, we interpret folding and associated clay neo-mineralization in terms of the regional burial history, and localization and propagation of deformation within a heterogeneous orogenic wedge involving progressive deformation of two basins separated by a platform block.

Kinematic evolution of fold and thrust belts. Insights from experimental modeling

International Nuclear Information System (INIS)

Ueta, Keiichi

2011-01-01

Physical experiments were performed to gain a better understanding on the kinematic evolution of fold and thrust belts. The present study focuses on deformation of sedimentary cover caused by thrust and reverse movements along the basement fault. Our physical models comprise dry quartz sand representing brittle sedimentary rock and viscous silicone polymer representing overpressured mudstone. Computerized X-ray tomography was applied to the experiments to analyze the kinematic evolution of fold and thrust belts. In the sand models, the width of deformation zone above thrust was wider than that above reverse fault, because back thrust developed on the hanging wall of reverse fault. Within the physical models composed of dry sand and silicone polymer, minor folds and thrusts with minor displacement developed on the footwall of the major monoclinal flexure. These results compare well with the geometry and kinematic evolution of the fold and thrust belts in Japan. (author)

Combined high and low-thrust geostationary orbit insertion with radiation constraint

Science.gov (United States)

Macdonald, Malcolm; Owens, Steven Robert

2018-01-01

The sequential use of an electric propulsion system is considered in combination with a high-thrust propulsion system for application to the propellant-optimal Geostationary Orbit insertion problem, whilst considering both temporal and radiation flux constraints. Such usage is found to offer a combined propellant mass saving when compared with an equivalent high-thrust only transfer. This propellant mass saving is seen to increase as the allowable transfer duration is increased, and as the thrust from the low-thrust system is increased, assuming constant specific impulse. It was found that the required plane change maneuver is most propellant-efficiently performed by the high-thrust system. The propellant optimal trajectory incurs a significantly increased electron flux when compared to an equivalent high-thrust only transfer. However, the electron flux can be reduced to a similar order of magnitude by increasing the high-thrust propellant consumption, whilst still delivering an improved mass fraction.

Tribological study on machine elements of HTGR components

International Nuclear Information System (INIS)

Nemoto, M.; Asanabe, S.; Kawaguchi, K.; Ono, S.; Oyamada, T.

1980-01-01

There are some tribological features peculiar to machines used in a high-temperature gas-cooled reactor (HTGR) plant. In this kind of plant, water-lubricated bearing combined with the buffer gas sealing system and/or gas-lubricated bearings are often applied in order to prevent degrading of the purity of coolant helium gas. And, it is essential for the reliability and safety design of the sliding members in the HTGR to obtain fundamental data on their friction and wear in high-temperature helium atmosphere. In this paper, the results of tests on these bearings and sliding members are introduced, which are summarized as follows: (1) Water-lubricated shrouded step thrust bearing and buffer gas sealing system were tested separately under the conditions simulated to those of circulators used in commercial plants. The results showed that each elements satisfies the requirements. (2) A hydrostatically gas-lubricated, pivoted pad journal bearing with a moat-shaped rectangular groove is found to be promising for use as a high-load bearing, which is indispensable for the development of a large-type circulator. (3) Use of ceramic coating and carbon graphite materials is effective for the prevention of adhesive wear which is apt to occur in metal-to-metal combinations. (author)

Tribological study on machine elements of HTGR components

International Nuclear Information System (INIS)

Nemoto, Masaaki; Ono, Shigeharu; Asanabe, Sadao; Kawaguchi, Katsuyuki; Oyamada, Tetsuya.

1981-11-01

There are some tribological features peculiar to machines used in a high-temperature gas-cooled reactor (HTGR) plant. In this kind of plant, water-lubricated bearing combined with the buffer gas sealing system and/or gas-lubricated bearings are often applied in order to prevent degrading of the purity of coolant helium gas. And, it is essential for the reliability and safety design of the sliding members in the HTGR to obtain fundamental data on their friction and wear in high-temperature helium atmosphere. In this paper, the results of tests on these bearings and sliding members are introduced, which are summarized as follows: (1) Water-lubricated shrouded step thrust bearing and buffer gas sealing system were tested separately under the condition simulated to those of circulators used in commercial plants. The results showed that each elements satisfies the requirements. (2) A hydrostatically gas-lubricated, pivoted pad journal bearing with a moat-shaped rectangular groove is found to be promising for use as a high-load bearing, which is indispensable for the development of a large-type circulator. (3) Use of ceramic coating and carbon graphite materials is effective for the prevention of adhesive wear which is apt to occur in metal-to-metal combinations. (author)

Quadcopter thrust optimization with ducted-propeller

Directory of Open Access Journals (Sweden)

Kuantama Endrowednes

2017-01-01

Full Text Available In relation to quadcopter body frame model, propeller can be categorized into propeller with ducted and without ducted. This study present differences between those two using CFD (Computational Fluid Dynamics method. Both categories utilize two blade-propeller with diameter of 406 (mm. Propeller rotation generates acceleration per time unit on the volume of air. Based on the behavior of generated air velocity, ducted propeller can be modeled into three versions. The generated thrust and performance on each model were calculated to determine the best model. The use of ducted propeller increases the total weight of quadcopter and also total thrust. The influence of this modeling were analyzed in detail with variation of angular velocity propeller from 1000 (rpm to 9000 (rpm. Besides the distance between propeller tip and ducted barrier, the size of ducted is also an important part in thrust optimization and total weight minimization of quadcopter.

Measurement of Impulsive Thrust from a Closed Radio Frequency Cavity in Vacuum

Science.gov (United States)

White, Harold; March, Paul; Lawrence, James; Vera, Jerry; Sylvester, Andre; Brady, David; Bailey, Paul

2016-01-01

A vacuum test campaign evaluating the impulsive thrust performance of a tapered RF test article excited in the TM212 mode at 1,937 megahertz (MHz) has been completed. The test campaign consisted of a forward thrust phase and reverse thrust phase at less than 8 x 10(exp -6) Torr vacuum with power scans at 40 watts, 60 watts, and 80 watts. The test campaign included a null thrust test effort to identify any mundane sources of impulsive thrust, however none were identified. Thrust data from forward, reverse, and null suggests that the system is consistently performing with a thrust to power ratio of 1.2 +/- 0.1 mN/kW.

Research on dynamics and experiments about auxiliary bearings for the helium circulator of the 10 MW high temperature gas-cooled reactor

International Nuclear Information System (INIS)

Zhao, Yulan; Yang, Guojun; Liu, Xingnan; Shi, Zhengang; Zhao, Lei

2016-01-01

Highlights: • The research in this paper is based on the AMB helium circulator of HTR-10. • The dynamic rotor performance is analyzed by processing experimental data. • The mechanical bearing without lubrication can be applied in the HTR-10 system. - Abstract: The 10 MW high-temperature gas-cooled reactor (HTR-10) was constructed by the Institute of Nuclear and New Energy Technology (INET) of Tsinghua University. The auxiliary bearing is utilized in this system to meet particular requirements for the reactor. The main role of the auxiliary bearing is to constrain rotor displacements and also to support the rotor when the rotor drops down, which is caused by the active magnetic bearing (AMB) failure. The auxiliary bearing needs to endure huge impact, rapid angular acceleration and thermal shock. On the one hand, complex geometrical constructions and forces applied on the system bring difficulties and restrictions to establish an appropriate model to reveal the actual dynamic process. On the other hand, large volumes of data obtained from experiments show velocities and displacements of the rotor during the rotor drop process and then can indicate the actual dynamic interactions to a great extent. The research in this paper is based on the test rig of the AMB helium circulator of HTR-10. This paper aims to analyze the dynamic performance and contact forces of the rotor by processing experimental data. A measurement to estimate forces developed due to impacts of the rotor and the auxiliary bearings is presented. It is of great significance and provides certain foundation to elaborate the rotor drop process for the AMB helium circulator of HTR-10.

High thrust-to-power ratio micro-cathode arc thruster

Directory of Open Access Journals (Sweden)

Joseph Lukas

2016-02-01

Full Text Available The Micro-Cathode Arc Thruster (μCAT is an electric propulsion device that ablates solid cathode material, through an electrical vacuum arc discharge, to create plasma and ultimately produce thrust in the μN to mN range. About 90% of the arc discharge current is conducted by electrons, which go toward heating the anode and contribute very little to thrust, with only the remaining 10% going toward thrust in the form of ion current. A preliminary set of experiments were conducted to show that, at the same power level, thrust may increase by utilizing an ablative anode. It was shown that ablative anode particles were found on a collection plate, compared to no particles from a non-ablative anode, while another experiment showed an increase in ion-to-arc current by approximately 40% at low frequencies compared to the non-ablative anode. Utilizing anode ablation leads to an increase in thrust-to-power ratio in the case of the μCAT.

14 CFR 25.904 - Automatic takeoff thrust control system (ATTCS).

Science.gov (United States)

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Automatic takeoff thrust control system... Automatic takeoff thrust control system (ATTCS). Each applicant seeking approval for installation of an engine power control system that automatically resets the power or thrust on the operating engine(s) when...

Active magnetic bearing for use in compressors and other turbomachinery

International Nuclear Information System (INIS)

Hennau, J.N.

1989-01-01

Active magnetic bearings and dry gas seals are now in operation on quite a number of compressors, turbines and generators, proving than an oil-free system is actually working and that furthermore, it has merits in energy savings, rotor dynamic monitoring and improved reliability. The technology of active magnetic bearing has been developed mainly in France after the Second World War for space application, but soon there appeared the large possibilities in industrial applications starting with the vacuum industry (turbomolecular pump), followed by the machine tool industry (high power and high speed milling and grinding spindles) and the large turbomachinery field (centrifugal compressors, blowers, steam and gas turbines, turbogenerators). Merits of the active magnetic bearing vary from one application to another, but they all derive from the fact that we have no contact between the rotor and the stator and that the electronic control of the bearings can cope with the rotor dynamics and provide useful information on the operating conditions

Dynamic Model for Thrust Generation of Marine Propellers

DEFF Research Database (Denmark)

Blanke, Mogens; Lindegaard, Karl-Petter; Fossen, Thor I.

2000-01-01

Mathematical models of propeller thrust and torque are traditionally based on steady state thrust and torque characteristics obtained in model basin or cavitation tunnel tests. Experimental results showed that these quasi steady state models do not accurately describe the transient phenomena in a...

Simulation of a multistage fractured horizontal well in a water-bearing tight fractured gas reservoir under non-Darcy flow

Science.gov (United States)

Zhang, Rui-Han; Zhang, Lie-Hui; Wang, Rui-He; Zhao, Yu-Long; Huang, Rui

2018-06-01

Reservoir development for unconventional resources such as tight gas reservoirs is in increasing demand due to the rapid decline of production in conventional reserves. Compared with conventional reservoirs, fluid flow in water-bearing tight gas reservoirs is subject to more nonlinear multiphase flow and gas slippage in nano/micro matrix pores because of the strong collisions between rock and gas molecules. Economic gas production from tight gas reservoirs depends on extensive application of water-based hydraulic fracturing of horizontal wells, associated with non-Darcy flow at a high flow rate, geomechanical stress sensitivity of un-propped natural fractures, complex flow geometry and multiscale heterogeneity. How to efficiently and accurately predict the production performance of a multistage fractured horizontal well (MFHW) is challenging. In this paper, a novel multicontinuum, multimechanism, two-phase simulator is established based on unstructured meshes and the control volume finite element method to analyze the production performance of MFHWs. The multiple interacting continua model and discrete fracture model are coupled to integrate the unstimulated fractured reservoir, induced fracture networks (stimulated reservoir volumes, SRVs) and irregular discrete hydraulic fractures. Several simulations and sensitivity analyses are performed with the developed simulator for determining the key factors affecting the production performance of MFHWs. Two widely applied fracturing models, classic hydraulic fracturing which generates long double-wing fractures and the volumetric fracturing aimed at creating large SRVs, are compared to identify which of them can make better use of tight gas reserves.

Comparison of Physical Properties of Marine and Arctic Gas-Hydrate-Bearing Deposits

Science.gov (United States)

Winters, W. J.; Walker, M.; Collett, T. S.; Bryant, S. L.; Novosel, I.; Wilcox-Cline, R.; Bing, J.; Gomes, M. L.

2009-12-01

Gas hydrate (GH) occurs in both marine settings and in arctic environments within a wide variety of sediment types. Grain-size analyses from both environments indicate that intrinsic host-sediment properties have a strong influence on gas-hydrate distribution and morphologic characteristics. Depending on the amount formed or dissociated, gas hydrate can significantly change in situ sediment acoustic, mechanical, and hydraulic properties. The U.S. Geological Survey, in cooperation with the U.S. Dept. of Energy, BP Expl.-Alaska, Nat. GH Prog. of India, Canadian Geological Survey, Int. Ocean Drilling Program, Japan Oil Gas and Metals Nat. Corp., Japan Pet. Expl. Co., Int. Marine Past Global Changes Study (IMAGES) program, and Paleoceanography of the Atlantic and Geochemistry (PAGE) program, determined physical properties from marine and arctic sediments and their relation to the presence of GH. At two arctic sites, the Mount Elbert well on the Alaskan North Slope and the Mallik wells on the Mackenzie Delta, NWT, >10-m thick gas-hydrate-bearing (GHB) sandy deposits are capped by finer-grained sediments that may reduce gas migration. In the Mount Elbert well, average median grain sizes (MGS) for the two thickest GHB deposits are 65 and 60 µm. Finer-grained (average MGS of 9 and 28 µm) sediments have plug permeabilities that are 300 and 14 times smaller than underlying GHB sediment. Average MGS of GHB sediment from the Mallik 2L well is ~ 111 µm, compared to overlying sediment with an average MGS of ~ 32 µm. Gas hydrate morphology in the Gulf of Mexico (GOM) and offshore India is substantially more complex than in the arctic, and is related to pervasive, although not exclusive, finer-grained deposits. Massive, several-cm thick, GH layers were recovered in piston cores in the northern GOM, in sediment with little visible lithologic variability (average MGS ~ 0.8 µm). In wells off the east coast of India, GH was present in sand-rich, fractured clay, and reservoirs

Foil Bearing Coating Behavior in CO₂

Energy Technology Data Exchange (ETDEWEB)

Walker, Matthew [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Kruizenga, Alan Michael [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Pasch, James Jay [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Fleming, Darryn [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2017-08-01

The Sandia S-CO₂ Recompression Closed Brayton Cycle (RCBC) utilizes a series of gas foil bearings in its turbine-alternator-compressors. At high shaft rotational speed these bearings allow the shaft to ride on a cushion of air. Conversely, during startup and shutdown, the shaft rides along the foil bearing surface. Low-friction coatings are used on bearing surfaces in order to facilitate rotation during these periods. An experimental program was initiated to elucidate the behavior of coated bearing foils in the harsh environments of this system. A test configuration was developed enabling long duration exposure tests, followed by a range of analyses relevant to their performance in a bearing. This report provides a detailed overview of this work. The results contained herein provide valuable information in selecting appropriate coatings for more advanced future bearing-rig tests at the newly established test facility in Sandia-NM.

The Design of High Reliability Magnetic Bearing Systems for Helium Cooled Reactor Machinery

International Nuclear Information System (INIS)

Swann, M.; Davies, N.; Jayawant, R.; Leung, R.; Shultz, R.; Gao, R.; Guo, Z.

2014-01-01

The requirements for magnetic bearing equipped machinery used in high temperature, helium cooled, graphite moderated reactor applications present a set of design considerations that are unlike most other applications of magnetic bearing technology in large industrial rotating equipment, for example as used in the oil and gas or other power generation applications. In particular, the bearings are typically immersed directly in the process gas in order to take advantage of the design simplicity that comes about from the elimination of ancillary lubrication and cooling systems for bearings and seals. Such duty means that the bearings will usually see high temperatures and pressures in service and will also typically be subject to graphite particulate and attendant radioactive contamination over time. In addition, unlike most industrial applications, seismic loading events become of paramount importance for the magnetic bearings system, both for actuators and controls. The auxiliary bearing design requirements, in particular, become especially demanding when one considers that the whole mechanical structure of the magnetic bearing system is located inside an inaccessible pressure vessel that should be rarely, if ever, disassembled over the service life of the power plant. Lastly, many machinery designs for gas cooled nuclear power plants utilize vertical orientation. This circumstance presents its own unique requirements for the machinery dynamics and bearing loads. Based on the authors’ experience with machine design and supply on several helium cooled reactor projects including Ft. St. Vrain (US), GT-MHR (Russia), PBMR (South Africa), GTHTR (Japan), and most recently HTR-PM (China), this paper addresses many of the design considerations for such machinery and how the application of magnetic bearings directly affects machinery reliability and availability, operability, and maintainability. Remote inspection and diagnostics are a key focus of this paper. (author)

Analyzing structural variations along strike in a deep-water thrust belt

Science.gov (United States)

Totake, Yukitsugu; Butler, Robert W. H.; Bond, Clare E.; Aziz, Aznan

2018-03-01

We characterize a deep-water fold-thrust arrays imaged by a high-resolution 3D seismic dataset in the offshore NW Borneo, Malaysia, to understand the kinematics behind spatial arrangement of structural variations throughout the fold-thrust system. The seismic volume used covers two sub-parallel fold trains associated with a series of fore-thrusts and back-thrusts. We measured fault heave, shortening value, fold geometries (forelimb dip, interlimb angle and crest depth) along strike in individual fold trains. Heave plot on strike projection allows to identify individual thrust segments showing semi-elliptical to triangular to bimodal patterns, and linkages of these segments. The linkage sites are marked by local minima in cumulative heave. These local heave minima are compensated by additional structures, such as small imbricate thrusts and tight folds indicated by large forelimb dip and small interlimb angle. Complementary profiles of the shortening amount for the two fold trains result in smoother gradient of total shortening across the structures. We interpret this reflects kinematic interaction between two fold-thrust trains. This type of along-strike variation analysis provides comprehensive understanding of a fold-thrust system and may provide an interpretative strategy for inferring the presence of complex multiple faults in less well-imaged parts of seismic volumes.

NASA Fixed Wing Project Propulsion Research and Technology Development Activities to Reduce Thrust Specific Energy Consumption

Science.gov (United States)

Hathaway, Michael D.; DelRasario, Ruben; Madavan, Nateri K.

2013-01-01

This paper presents an overview of the propulsion research and technology portfolio of NASA Fundamental Aeronautics Program Fixed Wing Project. The research is aimed at significantly reducing the thrust specific fuel/energy consumption of notional advanced fixed wing aircraft (by 60 % relative to a baseline Boeing 737-800 aircraft with CFM56-7B engines) in the 2030-2035 time frame. The research investments described herein are aimed at improving propulsive efficiency through higher bypass ratio fans, improving thermal efficiency through compact high overall pressure ratio gas generators, and exploring the potential benefits of boundary layer ingestion propulsion and hybrid gas-electric propulsion concepts.

Measurement and calculation of dynamic coefficients in hydrodynamic bearings of gas films; Medicion y calculo de coeficientes dinamicos en cojinetes hidrodinamicos de peliculas de gas

Energy Technology Data Exchange (ETDEWEB)

Ruiz, Rafael O.; Di Liscia, Marcelo H.; Diaz, Sergio E. [Universidad Simon Bolivar, Sartendejas, Baruta (Venezuela)

2007-11-15

The identification of the dynamic coefficients in air bearings is fundamental for a suitable roto-dynamic analysis. The present paper shows the development of an algorithm that allows the direct obtaining of the dynamic coefficients in hydrodynamic air bearings as much of numerical form as experimental. The testing bench used consists of two magnetic bearings, which support the rotor in their ends and work as well as actuators allowing inducing controlled orbits in the rotor. The test bearing is located between the magnetic bearings. The dynamic forces generated in the air bearing are registered from three load cells. The algorithm was developed in a commercial code of graphical programming, through which the signals can be collected, controlled and processed. The nonlinear behavior of this type of bearings makes difficult the calculation of the dynamic coefficients, therefore the processing of the signals in frequencial space facilitates, in a certain way, its handling. On the other hand, the numerical model was compared with the experimental results obtaining acceptable approaches in magnitude as well as in behavior. The numerical dynamic coefficients calculation was realized solving the Reynolds differential equation for a compressible fluid in the thickness of the gas film, taking into consideration the fluid mass flow that is introduced, as well as the pressure loss suffered by the same in passing through the feeding orifices. The numerical methods utilized include the solution of the differential equation of Reynolds for finite differences, the calculation of the profile realizing successive iterations and the calculation of the hydrodynamics forces through the Simpson numerical integration. The numerical dynamic coefficients were found applying a minimum squared technique to the hydrodynamic stresses generated in simulating an orbit of the rotor at a determined frequency and velocity, allowing in this way the calculation of the synchronous and asynchronous

A Literature Survey to Identify Potentially Volatile Iodine-Bearing Species Present in Off-Gas Streams

Energy Technology Data Exchange (ETDEWEB)

Bruffey, S. H. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Spencer, B. B. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Strachan, D. M. [Strata-G, Knoxville, TN (United States); Jubin, R. T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Soelberg, N. R. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Riley, B. J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2015-06-30

Four radionuclides have been identified as being sufficiently volatile in the reprocessing of nuclear fuel that their gaseous release needs to be controlled to meet regulatory requirements (Jubin et al. 2011, 2012). These radionuclides are 3H, 14C, 85Kr, and 129I. Of these, 129I has the longest half-life and potentially high biological impact. Accordingly, control of the release of 129I is most critical with respect to the regulations for the release of radioactive material in stack emissions. It is estimated that current EPA regulations (EPA 2010) would require any reprocessing plant in the United States to limit 129I release to less than 0.05 Ci/MTIHM for a typical fuel burnup of 55 gigawatt days per metric tonne (GWd/t) (Jubin 2011). The study of inorganic iodide in off-gas systems has been almost exclusively limited to I2 and the focus of organic iodide studies has been CH3I. In this document, we provide the results of an examination of publically available literature that is relevant to the presence and sources of both inorganic and organic iodine-bearing species in reprocessing plants. We especially focus on those that have the potential to be poorly sequestered with traditional capture methodologies. Based on the results of the literature survey and some limited thermodynamic modeling, the inorganic iodine species hypoiodous acid (HOI) and iodine monochloride (ICl) were identified as potentially low-sorbing iodine species that could present in off-gas systems. Organic species of interest included both short chain alkyl iodides such as methyl iodide (CH3I) and longer alkyl iodides up to iodododecane (C10H21I). It was found that fuel dissolution may provide conditions conducive to HOI formation and has been shown to result in volatile long-chain alkyl iodides, though these may not volatilize until later in the reprocessing sequence. Solvent extraction processes were found to be significant sources of various organic iodine-bearing species; formation of these

Eastern slopes grizzly bear project

Energy Technology Data Exchange (ETDEWEB)

NONE

2001-01-01

The cumulative effects of human activities on the grizzly bears in the central Canadian Rockies are not well known. As a result, a project was initiated in 1994 to address the urgent requirement for accurate scientific information on the habitat and populations of grizzly bears in the area of the Banff National Park and Kananaskis Country. This area is probably the most heavily used and developed area where the grizzly still survives. The information gathered throughout the course of this study will be used to better protect and manage the bears and other sensitive carnivores in the region. Using telemetry, researchers are monitoring 25 grizzly bears which were radio-collared in a 22,000 square-kilometer area in the upper Bow Valley drainage of the eastern Alberta slopes. The researchers involved in the project are working with representatives from Husky Oil and Talisman Energy on the sound development of the Moose Mountain oil and gas field without adversely affecting the grizzly bear population. Information collected over seven years indicated that the grizzly bears have few and infrequent offspring. Using the information gathered so far, the location of the Moose Mountain to Jumping Pound pipeline was carefully selected, since the bears recover very slowly from high mortality, and also considering that the food and cover had already been compromised by the high number of roads, trails and other human activities in the area. The status of the population and habitat of the grizzly bear will be assessed upon the conclusion of the field research phase in 2001. Models will be updated using the data obtained during eight years and will assist in the understanding of complex variables that affect grizzly bears.

Physical Properties of Gas Hydrates: A Review

Energy Technology Data Exchange (ETDEWEB)

Gabitto, Jorge [Prairie View A& M University; Tsouris, Costas [ORNL

2010-01-01

Methane gas hydrates in sediments have been studied by several investigators as a possible future energy resource. Recent hydrate reserves have been estimated at approximately 1016?m3 of methane gas worldwide at standard temperature and pressure conditions. In situ dissociation of natural gas hydrate is necessary in order to commercially exploit the resource from the natural-gas-hydrate-bearing sediment. The presence of gas hydrates in sediments dramatically alters some of the normal physical properties of the sediment. These changes can be detected by field measurements and by down-hole logs. An understanding of the physical properties of hydrate-bearing sediments is necessary for interpretation of geophysical data collected in field settings, borehole, and slope stability analyses; reservoir simulation; and production models. This work reviews information available in literature related to the physical properties of sediments containing gas hydrates. A brief review of the physical properties of bulk gas hydrates is included. Detection methods, morphology, and relevant physical properties of gas-hydrate-bearing sediments are also discussed.

Aircraft Horizontal Thrust Measurement Facility

Data.gov (United States)

Federal Laboratory Consortium — This facility is designed to support the DoD mission by providing unique air vehicle installed engine performance (thrust output) measurements. This system consists...

A Determinate Model of Thrust-Augmenting Ejectors

Science.gov (United States)

Whitley, N.; Krothapalli, A.; van Dommelen, L.

1996-01-01

A theoretical analysis of the compressible flow through a constant-area jet-engine ejector in which a primary jet mixes with ambient fluid from a uniform free stream is pursued. The problem is reduced to a determinate mathematical one by prescribing the ratios of stagnation properties between the primary and secondary flows. For some selections of properties and parameters more than one solution is possible and the meaning of these solutions is discussed by means of asymptotic expansions. Our results further show that while under stationary conditions the thrust-augmentation ratio assumes a value of 2 in the large area-ratio limit, for a free-stream Mach number greater than 0.6 very little thrust augmentation is left. Due to the assumptions made, the analysis provides idealized values for the thrust-augmentation ratio and the mass flux entrainment factor.

Thermal conductivity measurements in unsaturated hydrate-bearing sediments

Science.gov (United States)

Dai, Sheng; Cha, Jong-Ho; Rosenbaum, Eilis J.; Zhang, Wu; Seol, Yongkoo

2015-08-01

Current database on the thermal properties of hydrate-bearing sediments remains limited and has not been able to capture their consequential changes during gas production where vigorous phase changes occur in this unsaturated system. This study uses the transient plane source (TPS) technique to measure the thermal conductivity of methane hydrate-bearing sediments with various hydrate/water/gas saturations. We propose a simplified method to obtain thermal properties from single-sided TPS signatures. Results reveal that both volume fraction and distribution of the pore constituents govern the thermal conductivity of unsaturated specimens. Thermal conductivity hysteresis is observed due to water redistribution and fabric change caused by hydrate formation and dissociation. Measured thermal conductivity increases evidently when hydrate saturation Sh > 30-40%, shifting upward from the geometric mean model prediction to a Pythagorean mixing model. These observations envisage a significant drop in sediment thermal conductivity when residual hydrate/water saturation falls below ~40%, hindering further gas production.

Early history and reactivation of the rand thrust, southern California

Science.gov (United States)

Postlethwaite, Clay E.; Jacobson, Carl E.

The Rand thrust of the Rand Mountains in the northwestern Mojave Desert separates an upper plate of quartz monzonite and quartzofeldspathic to amphibolitic gneiss from a lower plate of metagraywacke and mafic schist (Rand Schist). The Rand thrust is considered part of the regionally extensive Vincent/Chocolate Mountain thrust system, which is commonly believed to represent a Late Cretaceous subduction zone. The initial direction of dip and sense of movement along the Vincent/Chocolate Mountain thrust are controversial. Microfabrics of mylonites and quartzites from the Rand Mountains were analyzed in an attempt to determine transport direction for this region, but the results are ambiguous. In addition, the southwestern portion of the Rand thrust was found to have been reactivated as a low-angle normal fault after subduction. Reactivation might have occurred shortly after subduction, in which case it could account for the preservation of high-pressure mineral assemblages in the Rand Schist, or it could be related to mid-Tertiary extension in the western United States. In either event, the reactivation might be responsible for the complicated nature of the microfabrics. The Rand Schist exhibits an inverted metamorphic zonation. Isograds in the schist are not significantly truncated by the reactivated segment of the Rand thrust. This indicates that other segments of the Vincent/Chocolate Mountain thrust should be re-evaluated for the possibility of late movement, even if they show an apparently undisturbed inverted metamorphic zonation.

Thrust Stand for Vertically Oriented Electric Propulsion Performance Evaluation

Science.gov (United States)

Moeller, Trevor; Polzin, Kurt A.

2010-01-01

A variation of a hanging pendulum thrust stand capable of measuring the performance of an electric thruster operating in the vertical orientation is presented. The vertical orientation of the thruster dictates that the thruster must be horizontally offset from the pendulum pivot arm, necessitating the use of a counterweight system to provide a neutrally-stable system. Motion of the pendulum arm is transferred through a balance mechanism to a secondary arm on which deflection is measured. A non-contact light-based transducer is used to measure displacement of the secondary beam. The members experience very little friction, rotating on twisting torsional pivots with oscillatory motion attenuated by a passive, eddy current damper. Displacement is calibrated using an in situ thrust calibration system. Thermal management and self-leveling systems are incorporated to mitigate thermal and mechanical drifts. Gravitational restoring force and torsional spring constants associated with flexure pivots provide restoring moments. An analysis of the design indicates that the thrust measurement range spans roughly four decades, with the stand capable of measuring thrust up to 12 N for a 200 kg thruster and up to approximately 800 mN for a 10 kg thruster. Data obtained from calibration tests performed using a 26.8 lbm simulated thruster indicated a resolution of 1 mN on 100 mN-level thrusts, while those tests conducted on 200 lbm thruster yielded a resolution of roughly 2.5 micro at thrust levels of 0.5 N and greater.

Thrust stand for vertically oriented electric propulsion performance evaluation

Energy Technology Data Exchange (ETDEWEB)

Moeller, Trevor [University of Tennessee Space Institute, Tullahoma, Tennessee 37388 (United States); Polzin, Kurt A. [NASA, Marshall Space Flight Center, Huntsville, Alabama 35812 (United States)

2010-11-15

A variation of a hanging pendulum thrust stand capable of measuring the performance of an electric thruster operating in the vertical orientation is presented. The vertical orientation of the thruster dictates that the thruster must be horizontally offset from the pendulum pivot arm, necessitating the use of a counterweight system to provide a neutrally stable system. Motion of the pendulum arm is transferred through a balance mechanism to a secondary arm on which deflection is measured. A noncontact light-based transducer is used to measure displacement of the secondary beam. The members experience very little friction, rotating on twisting torsional pivots with oscillatory motion attenuated by a passive, eddy-current damper. Displacement is calibrated using an in situ thrust calibration system. Thermal management and self-leveling systems are incorporated to mitigate thermal and mechanical drifts. Gravitational force and torsional spring constants associated with flexure pivots provide restoring moments. An analysis of the design indicates that the thrust measurement range spans roughly four decades, with the stand capable of measuring thrust up to 12 N for a 200 kg thruster and up to approximately 800 mN for a 10 kg thruster. Data obtained from calibration tests performed using a 26.8 lbm simulated thruster indicated a resolution of 1 mN on 100 mN level thrusts, while those tests conducted on a 200 lbm thruster yielded a resolution of roughly 2.5 mN at thrust levels of 0.5 N and greater.

Thrust stand for vertically oriented electric propulsion performance evaluation

International Nuclear Information System (INIS)

Moeller, Trevor; Polzin, Kurt A.

2010-01-01

A variation of a hanging pendulum thrust stand capable of measuring the performance of an electric thruster operating in the vertical orientation is presented. The vertical orientation of the thruster dictates that the thruster must be horizontally offset from the pendulum pivot arm, necessitating the use of a counterweight system to provide a neutrally stable system. Motion of the pendulum arm is transferred through a balance mechanism to a secondary arm on which deflection is measured. A noncontact light-based transducer is used to measure displacement of the secondary beam. The members experience very little friction, rotating on twisting torsional pivots with oscillatory motion attenuated by a passive, eddy-current damper. Displacement is calibrated using an in situ thrust calibration system. Thermal management and self-leveling systems are incorporated to mitigate thermal and mechanical drifts. Gravitational force and torsional spring constants associated with flexure pivots provide restoring moments. An analysis of the design indicates that the thrust measurement range spans roughly four decades, with the stand capable of measuring thrust up to 12 N for a 200 kg thruster and up to approximately 800 mN for a 10 kg thruster. Data obtained from calibration tests performed using a 26.8 lbm simulated thruster indicated a resolution of 1 mN on 100 mN level thrusts, while those tests conducted on a 200 lbm thruster yielded a resolution of roughly 2.5 mN at thrust levels of 0.5 N and greater.

Forecasting of reservoir pressures of oil and gas bearing complexes in northern part of West Siberia for safety oil and gas deposits exploration and development

Science.gov (United States)

Gorbunov, P. A.; Vorobyov, S. V.

2017-10-01

In the paper the features of reservoir pressures changes in the northern part of West Siberian oil-and gas province are described. This research is based on the results of hydrodynamic studies in prospecting and explorating wells in Yamal-Nenets Autonomous District. In the Cenomanian, Albian, Aptian and in the top of Neocomian deposits, according to the research, reservoir pressure is usually equal to hydrostatic pressure. At the bottom of the Neocomian and Jurassic deposits zones with abnormally high reservoir pressures (AHRP) are distinguished within Gydan and Yamal Peninsula and in the Nadym-Pur-Taz interfluve. Authors performed the unique zoning of the territory of the Yamal-Nenets Autonomous District according to the patterns of changes of reservoir pressures in the section of the sedimentary cover. The performed zoning and structural modeling allow authors to create a set of the initial reservoir pressures maps for the main oil and gas bearing complexes of the northern part of West Siberia. The results of the survey should improve the efficiency of exploration drilling by preventing complications and accidents during this operation in zones with abnormally high reservoir pressures. In addition, the results of the study can be used to estimate gas resources within prospective areas of Yamal-Nenets Autonomous District.

78 FR 2990 - Bear Creek Storage Company, L.L.C.; Notice of Request Under Blanket Authorization

Science.gov (United States)

2013-01-15

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. CP13-34-000] Bear Creek..., 2012, Bear Creek Storage Company, L.L.C. (Bear Creek), 569 Brookwood Village, Suite 749, Birmingham....208, 157.213 and 157.216 of the Commission's Regulations under the Natural Gas Act, and Bear Creek's...

The paradox of vertical σ2 in foreland fold and thrust belts

Science.gov (United States)

Tavani, Stefano

2014-05-01

Occurrence of aesthetically appealing thrust systems and associated large scale anticlines, in both active and fossil foreland fold and thrust belts, is commonly interpreted as an evidence for Andersonian compressional framework. Indeed, these structures would testify for a roughly vertical σ3. Such a correlation between thrusts occurrence and stress field orientation, however, frequently fails to explain denser observations at a smaller scale. The syn-orogenic deformation meso-structures hosted in exposed km-scale thrust-related folds, in fact, frequently and paradoxically witness for a syn-thrusting strike-slip stress configuration, with a near-vertical σ2 and a sub-horizontal σ3. This apparent widespread inconsistency between syn-orogenic meso-structures and stress field orientation is here named "the σ2 paradox". A possible explanation for such a paradox is provided by inherited extensional deformation structures commonly developed prior to thrusting, in the flexural foreland basins located ahead of fold and thrust belts. Thrust nucleation and propagation is facilitated and driven by the positive inversion of the extensional inheritances, and their subsequent linkage. This process eventually leads to the development of large reverse fault zones and can occur both in compressive and strike-slip stress configurations.

Oil and gas planning and development in Alberta : new approaches to integrate grizzly bear conservation

Energy Technology Data Exchange (ETDEWEB)

Stenhouse, G. [Foothills Model Forest Grizzly Bear Research Program, AB (Canada)

2007-07-01

This paper reported on a grizzly bear research program that was initiated in the province of Alberta to provide new knowledge and tools to ensure the long term survival of grizzly bears on a multiple use landscape. The Foothills Model Forest (FMF) Grizzly Bear Research Program was formed by scientists from across Canada from a variety of scientific disciplines. A strong partner base has been created to allow the FMF's research efforts to span the entire current distribution of grizzly bear habitat in Alberta. The FMF has provided new large scale seamless maps of grizzly bear habitat and, using detailed grizzly bear GPS movement data, has constructed and tested models that can identify key grizzly bear habitat. This presentation focused on the results of 9 years of applied research and described the new tools and models that are now available to program partners in Alberta. The products are currently being used by both industry and government in Alberta as new standards in landscape management planning in grizzly bear habitat. The author suggested that the approach taken with grizzly bears in Alberta could be used and adapted for a variety of wildlife species in the north. figs.

Electromagnetic calibration system for sub-micronewton torsional thrust stand

Science.gov (United States)

Lam, J. K.; Koay, S. C.; Cheah, K. H.

2017-12-01

It is critical for a micropropulsion system to be evaluated. Thrust stands are widely recognised as the instrument to complete such tasks. This paper presents the development of an alternative electromagnetic calibration technique for thrust stands. Utilising the commercially made voice coils and permanent magnets, the proposed system is able to generate repeatable and also consistent steady-state calibration forces at over four orders of magnitude (30 - 23000 μN). The system is then used to calibrate a custom-designed torsional thrust stand, where its inherent ability in ease of setup is well demonstrated.

A new method for optimization of low-thrust gravity-assist sequences

Science.gov (United States)

Maiwald, V.

2017-09-01

Recently missions like Hayabusa and Dawn have shown the relevance and benefits of low-thrust spacecraft concerning the exploration of our solar system. In general, the efficiency of low-thrust propulsion is one means of improving mission payload mass. At the same time, gravity-assist maneuvers can serve as mission enablers, as they have the capability to provide "free energy." A combination of both, gravity-assist and low-thrust propulsion, has the potential to generally improve mission performance, i.e. planning and optimization of gravity-assist sequences for low-thrust missions is a desirable asset. Currently no established methods exist to include the gravity-assist partners as optimization variable for low-thrust missions. The present paper explains how gravity-assists are planned and optimized, including the gravity-assist partners, for high-thrust missions and discusses the possibility to transfer the established method, based on the Tisserand Criterion, to low-thrust missions. It is shown how the Tisserand Criterion needs to be adapted using a correction term for the low-thrust situation. It is explained why this necessary correction term excludes an a priori evaluation of sequences and therefore their planning and an alternate approach is proposed. Preliminary results of this method, by application of a Differential Evolution optimization algorithm, are presented and discussed, showing that the method is valid but can be improved. Two constraints on the search space are briefly presented for that aim.

Sedimentation of Jurassic fan-delta wedges in the Xiahuayuan basin reflecting thrust-fault movements of the western Yanshan fold-and-thrust belt, China

Science.gov (United States)

Lin, Chengfa; Liu, Shaofeng; Zhuang, Qitian; Steel, Ronald J.

2018-06-01

Mesozoic thrusting within the Yanshan fold-and-thrust belt of North China resulted in a series of fault-bounded intramontane basins whose infill and evolution remain poorly understood. In particular, the bounding faults and adjacent sediment accumulations along the western segments of the belt are almost unstudied. A sedimentological and provenance analysis of the Lower Jurassic Xiahuayuan Formation and the Upper Jurassic Jiulongshan Formation have been mapped to show two distinctive clastic wedges: an early Jurassic wedge representing a mass-flow-dominated, Gilbert-type fan delta with a classic tripartite architecture, and an late Jurassic shoal-water fan delta without steeply inclined strata. The basinward migration of the fan-delta wedges, together with the analysis of their conglomerate clast compositions, paleocurrent data and detrital zircon U-Pb age spectra, strongly suggest that the northern-bounding Xuanhuan thrust fault controlled their growth during accumulation of the Jiulongshan Formation. Previous studies have suggested that the fan-delta wedge of the Xiahuayuan Formation was also syntectonic, related to movement on the Xuanhua thrust fault. Two stages of thrusting therefore exerted an influence on the formation and evolution of the Xiahuayuan basin during the early-late Jurassic.

Electronics Engineering Department Thrust Area report FY'84

International Nuclear Information System (INIS)

Minichino, C.; Phelps, P.L.

1984-01-01

This report describes the work of the Electronics Engineering Department Thrust Areas for FY'84: diagnostics and microelectronic engineering; signal and control engineering; microwave and pulsed power engineering; computer-aided engineering; engineering modeling and simulation; and systems engineering. For each Thrust Area, an overview and a description of the goals and achievements of each project is provided

Primary electric propulsion thrust subsystem definition

Science.gov (United States)

Masek, T. D.; Ward, J. W.; Kami, S.

1975-01-01

A review is presented of the current status of primary propulsion thrust subsystem (TSS) performance, packaging considerations, and certain operational characteristics. Thrust subsystem related work from recent studies by Jet Propulsion Laboratories (JPL), Rockwell and Boeing is discussed. Existing performance for 30-cm thrusters, power processors and TSS is present along with projections for future improvements. Results of analyses to determine (1) magnetic field distributions resulting from an array of thrusters, (2) thruster emitted particle flux distributions from an array of thrusters, and (3) TSS element failure rates are described to indicate the availability of analytical tools for evaluation of TSS designs.

Role of wing morphing in thrust generation

Directory of Open Access Journals (Sweden)

Mehdi Ghommem

2014-01-01

Full Text Available In this paper, we investigate the role of morphing on flight dynamics of two birds by simulating the flow over rigid and morphing wings that have the characteristics of two different birds, namely the Giant Petrel and Dove Prion. The simulation of a flapping rigid wing shows that the root of the wing should be placed at a specific angle of attack in order to generate enough lift to balance the weight of the bird. However, in this case the generated thrust is either very small, or even negative, depending on the wing shape. Further, results show that morphing of the wing enables a significant increase in the thrust and propulsive efficiency. This indicates that the birds actually utilize some sort of active wing twisting and bending to produce enough thrust. This study should facilitate better guidance for the design of flapping air vehicles.

Laboratory Studies on the Formation of Carbon-Bearing Molecules in Extraterrestrial Environments: From the Gas Phase to the Solid State

Science.gov (United States)

Jamieson, C. S.; Guo, Y.; Gu, X.; Zhang, F.; Bennett, C. J.; Kaiser, R. I.

2006-01-01

A detailed knowledge of the formation of carbon-bearing molecules in interstellar ices and in the gas phase of the interstellar medium is of paramount interest to understand the astrochemical evolution of extraterrestrial environments (1). This research also holds strong implications to comprehend the chemical processing of Solar System environments such as icy planets and their moons together with the atmospheres of planets and their satellites (2). Since the present composition of each interstellar and Solar System environment reflects the matter from which it was formed and the processes which have changed the chemical nature since the origin (solar wind, planetary magnetospheres, cosmic ray exposure, photolysis, chemical reactions), a detailed investigation of the physicochemical mechanisms altering the pristine environment is of paramount importance to grasp the contemporary composition. Once these underlying processes have been unraveled, we can identify those molecules, which belonged to the nascent setting, distinguish molecular species synthesized in a later stage, and predict the imminent chemical evolution of, for instance, molecular clouds. Laboratory experiments under controlled physicochemical conditions (temperature, pressure, chemical composition, high energy components) present ideal tools for simulating the chemical evolution of interstellar and Solar System environments. Here, laboratory experiments can predict where and how (reaction mechanisms; chemicals necessary) in extraterrestrial environments and in the interstellar medium complex, carbon bearing molecules can be formed on interstellar grains and in the gas phase. This paper overviews the experimental setups utilized in our laboratory to mimic the chemical processing of gas phase and solid state (ices) environments. These are a crossed molecular beams machine (3) and a surface scattering setup (4). We also present typical results of each setup (formation of amino acids, aldehydes, epoxides

Multi-Axis Thrust Measurements of the EO-1 Pulsed Plasma Thruster

Science.gov (United States)

Arrington, Lynn A.; Haag, Thomas W.

1999-01-01

Pulsed plasma thrusters are low thrust propulsive devices which have a high specific impulse at low power. A pulsed plasma thruster is currently scheduled to fly as an experiment on NASA's Earth Observing-1 satellite mission. The pulsed plasma thruster will be used to replace one of the reaction wheels. As part of the qualification testing of the thruster it is necessary to determine the nominal thrust as a function of charge energy. These data will be used to determine control algorithms. Testing was first completed on a breadboard pulsed plasma thruster to determine nominal or primary axis thrust and associated propellant mass consumption as a function of energy and then later to determine if any significant off-axis thrust component existed. On conclusion that there was a significant off-axis thrust component with the bread-board in the direction of the anode electrode, the test matrix was expanded on the flight hardware to include thrust measurements along all three orthogonal axes. Similar off-axis components were found with the flight unit.

An Advanced Microturbine System with Water-Lubricated Bearings

Directory of Open Access Journals (Sweden)

Susumu Nakano

2009-01-01

Full Text Available A prototype of the next-generation, high-performance microturbine system was developed for laboratory evaluation. Its unique feature is its utilization of water. Water is the lubricant for the bearings in this first reported application of water-lubricated bearings in gas turbines. Bearing losses and limitations under usage conditions were found from component tests done on the bearings and load tests done on the prototype microturbine. The rotor system using the water-lubricated bearings achieved stable rotating conditions at a rated rotational speed of 51,000 rpm. An electrical output of 135 kW with an efficiency of more than 33% was obtained. Water was also utilized to improve electrical output and efficiency through water atomizing inlet air cooling (WAC and a humid air turbine (HAT. The operation test results for the WAC and HAT revealed the WAC and HAT operations had significant effects on both electrical output and electrical efficiency.

Steroid hormone profile in female polar bears (Ursus maritimus)

DEFF Research Database (Denmark)

Gustavson, Lisa; Jenssen, Bjørn Munro; Bytingsvik, Jenny

2015-01-01

The polar bear is an iconic Arctic species, threatened by anthropogenic impacts such as pollution and climate change. Successful reproduction of polar bears depends on a functioning steroid hormone system, which is susceptible to effects of persistent organic pollutants. The present study...... is the first study to report circulating concentrations of nine steroid hormones (i.e., estrogens, androgens and progestagens) in female polar bears (Ursus maritimus). The aim of the study was to investigate the effects of age, condition, location and reproductive status on steroid profile in female polar...... bears. Levels of pregnenolone (PRE), progesterone, androstenedione (AN), dehydroepiandrosterone (DHEA), testosterone, dihydrotestosterone, estrone (E1), 17α-estradiol (αE2) and 17β-estradiol (βE2) were quantified in blood (serum) of free-living female polar bears (n = 15) from Svalbard, Norway, by gas...

Global Optimization of Low-Thrust Interplanetary Trajectories Subject to Operational Constraints

Science.gov (United States)

Englander, Jacob Aldo; Vavrina, Matthew; Hinckley, David

2016-01-01

Low-thrust electric propulsion provides many advantages for mission to difficult targets-Comets and asteroids-Mercury-Outer planets (with sufficient power supply)Low-thrust electric propulsion is characterized by high power requirements but also very high specific impulse (Isp), leading to very good mass fractions. Low-thrust trajectory design is a very different process from chemical trajectory.

Thrust Area Report, Engineering Research, Development and Technology

Energy Technology Data Exchange (ETDEWEB)

Langland, R. T.

1997-02-01

The mission of the Engineering Research, Development, and Technology Program at Lawrence Livermore National Laboratory (LLNL) is to develop the knowledge base, process technologies, specialized equipment, tools and facilities to support current and future LLNL programs. Engineering`s efforts are guided by a strategy that results in dual benefit: first, in support of Department of Energy missions, such as national security through nuclear deterrence; and second, in enhancing the nation`s economic competitiveness through our collaboration with U.S. industry in pursuit of the most cost- effective engineering solutions to LLNL programs. To accomplish this mission, the Engineering Research, Development, and Technology Program has two important goals: (1) identify key technologies relevant to LLNL programs where we can establish unique competencies, and (2) conduct high-quality research and development to enhance our capabilities and establish ourselves as the world leaders in these technologies. To focus Engineering`s efforts technology {ital thrust areas} are identified and technical leaders are selected for each area. The thrust areas are comprised of integrated engineering activities, staffed by personnel from the nine electronics and mechanical engineering divisions, and from other LLNL organizations. This annual report, organized by thrust area, describes Engineering`s activities for fiscal year 1996. The report provides timely summaries of objectives, methods, and key results from eight thrust areas: Computational Electronics and Electromagnetics; Computational Mechanics; Microtechnology; Manufacturing Technology; Materials Science and Engineering; Power Conversion Technologies; Nondestructive Evaluation; and Information Engineering. Readers desiring more information are encouraged to contact the individual thrust area leaders or authors. 198 refs., 206 figs., 16 tabs.

A pressure core ultrasonic test system for on-board analysis of gas hydrate-bearing sediments under in situ pressures.

Science.gov (United States)

Yang, Lei; Zhou, Weihua; Xue, Kaihua; Wei, Rupeng; Ling, Zheng

2018-05-01

The enormous potential as an alternative energy resource has made natural gas hydrates a material of intense research interest. Their exploration and sample characterization require a quick and effective analysis of the hydrate-bearing cores recovered under in situ pressures. Here a novel Pressure Core Ultrasonic Test System (PCUTS) for on-board analysis of sediment cores containing gas hydrates at in situ pressures is presented. The PCUTS is designed to be compatible with an on-board pressure core transfer device and a long gravity-piston pressure-retained corer. It provides several advantages over laboratory core analysis including quick and non-destructive detection, in situ and successive acoustic property acquisition, and remission of sample storage and transportation. The design of the unique assembly units to ensure the in situ detection is demonstrated, involving the U-type protecting jackets, transducer precession device, and pressure stabilization system. The in situ P-wave velocity measurements make the detection of gas hydrate existence in the sediments possible on-board. Performance tests have verified the feasibility and sensitivity of the ultrasonic test unit, showing the dependence of P-wave velocity on gas hydrate saturation. The PCUTS has been successfully applied for analysis of natural samples containing gas hydrates recovered from the South China Sea. It is indicated that on-board P-wave measurements could provide a quick and effective understanding of the hydrate occurrence in natural samples, which can assist further resource exploration, assessment, and subsequent detailed core analysis.

A pressure core ultrasonic test system for on-board analysis of gas hydrate-bearing sediments under in situ pressures

Science.gov (United States)

Yang, Lei; Zhou, Weihua; Xue, Kaihua; Wei, Rupeng; Ling, Zheng

2018-05-01

The enormous potential as an alternative energy resource has made natural gas hydrates a material of intense research interest. Their exploration and sample characterization require a quick and effective analysis of the hydrate-bearing cores recovered under in situ pressures. Here a novel Pressure Core Ultrasonic Test System (PCUTS) for on-board analysis of sediment cores containing gas hydrates at in situ pressures is presented. The PCUTS is designed to be compatible with an on-board pressure core transfer device and a long gravity-piston pressure-retained corer. It provides several advantages over laboratory core analysis including quick and non-destructive detection, in situ and successive acoustic property acquisition, and remission of sample storage and transportation. The design of the unique assembly units to ensure the in situ detection is demonstrated, involving the U-type protecting jackets, transducer precession device, and pressure stabilization system. The in situ P-wave velocity measurements make the detection of gas hydrate existence in the sediments possible on-board. Performance tests have verified the feasibility and sensitivity of the ultrasonic test unit, showing the dependence of P-wave velocity on gas hydrate saturation. The PCUTS has been successfully applied for analysis of natural samples containing gas hydrates recovered from the South China Sea. It is indicated that on-board P-wave measurements could provide a quick and effective understanding of the hydrate occurrence in natural samples, which can assist further resource exploration, assessment, and subsequent detailed core analysis.

Cryogenic liquid resettlement activated by impulsive thrust in space-based propulsion system

Science.gov (United States)

Hung, R. J.; Shyu, K. L.

1991-01-01

The purpose of present study is to investigate the most efficient technique for propellant resettling through the minimization of propellant usage and weight penalties. Comparison between the constant reverse gravity acceleration and impulsive reverse gravity acceleration to be used for the activation of propellant resettlement shows that impulsive reverse gravity thrust is superior to constant reverse gravity thrust for liquid reorientation in a reduced gravity environment. Comparison among impulsive reverse gravity thrust with 0.1, 1.0, and 10 Hz frequencies for liquid-filled level in the range between 30 to 80 percent shows that the selection of a medium frequency of 1.0 Hz impulsive thrust over the other frequency ranges of impulsive thrust is the most proper.

Bearing compartment seal systems for turbomachinery in direct-cycle HTGR power plants

International Nuclear Information System (INIS)

Adams, R.G.; Boenig, F.H.; Pfeifer, G.D.

1977-10-01

The direct-cycle High-Temperature Gas-Cooled Reactor (HTGR) employs a closed gas-turbine cycle with the primary reactor coolant (helium) as the working fluid. Design studies on this type of plant, carried out since 1971, have demonstrated, among other points, the advantages of the integrated arrangement, in which power from the cycle is transmitted to the electric generators by turbomachines completely enclosed in the reactor pressure vessel. A result of this arrangement is that the bearings are entirely enclosed within the primary coolant system of the reactor. An important aspect of the design of the turbomachinery is its prevention or minimization of the ingress of lubricants into the primary coolant system and its prevention of ingress of primary coolant into the bearing compartments. The design studies, which included thorough conceptual designs of the turbomachinery with emphasis on bearings and seals and their support systems showed that total exclusion of lubricant requires extremely complex seals and seal support systems. The variation of system low-end pressure with control actuation and the requirement that the bearing cavity pressure follow these variations were proved to further complicate the service system. The tolerance of even relatively minute amounts of entering lubricant during control transients will allow considerable simplification. This paper discusses the above-mentioned problems and their solutions in tracing the design evolution of a satisfactory bearing-compartment seals and service system. The resulting system appears to be feasible on the basis of experience with industrial gas turbines

Crustal scale geometry of the Zagros fold–thrust belt, Iran

OpenAIRE

McQuarrie, Nadine

2004-01-01

Balanced cross-sections across the Zagros fold–thrust belt in Iran are used to analyze the geometry of deformation within the sedimentary cover rocks, and to test the hypothesis of basement involved thrusting throughout the fold–thrust belt. Although the Zagros deformation front is a relatively rectilinear feature, the sinuous map-view morphology of the mountain front is a result of a 6 km structural step in the regional elevation of the Asmari Limestone that produces a pronounced step in top...

Pressurized subsampling system for pressured gas-hydrate-bearing sediment: Microscale imaging using X-ray computed tomography

International Nuclear Information System (INIS)

Jin, Yusuke; Konno, Yoshihiro; Nagao, Jiro

2014-01-01

A pressurized subsampling system was developed for pressured gas hydrate (GH)-bearing sediments, which have been stored under pressure. The system subsamples small amounts of GH sediments from cores (approximately 50 mm in diameter and 300 mm in height) without pressure release to atmospheric conditions. The maximum size of the subsamples is 12.5 mm in diameter and 20 mm in height. Moreover, our system transfers the subsample into a pressure vessel, and seals the pressure vessel by screwing in a plug under hydraulic pressure conditions. In this study, we demonstrated pressurized subsampling from artificial xenon-hydrate sediments and nondestructive microscale imaging of the subsample, using a microfocus X-ray computed tomography (CT) system. In addition, we estimated porosity and hydrate saturation from two-dimensional X-ray CT images of the subsamples

Self-lubricating fluid bearing assembly

International Nuclear Information System (INIS)

Kapich, D.D.

1981-01-01

A sealed self-lubricating fluid bearing assembly is described for circulating fluid in the form of a gas coolant in a nuclear reactor, the power for the circulator being provided by a shaft located within the primary containment vessel. In such a system the reactor coolant is isolated from the fluid region at the far end of the drive shaft. (U.K.)

Pliocene episodic exhumation and the significance of the Munsiari thrust in the northwestern Himalaya

Science.gov (United States)

Stübner, Konstanze; Grujic, Djordje; Dunkl, István; Thiede, Rasmus; Eugster, Patricia

2018-01-01

The Himalayan thrust belt comprises three in-sequence foreland-propagating orogen-scale faults, the Main Central thrust, the Main Boundary thrust, and the Main Frontal thrust. Recently, the Munsiari-Ramgarh-Shumar thrust system has been recognized as an additional, potentially orogen-scale shear zone in the proximal footwall of the Main Central thrust. The timing of the Munsiari, Ramgarh, and Shumar thrusts and their role in Himalayan tectonics are disputed. We present 31 new zircon (U-Th)/He ages from a profile across the central Himachal Himalaya in the Beas River area. Within a ∼40 km wide belt northeast of the Kullu-Larji-Rampur window, ages ranging from 2.4 ± 0.4 Ma to 5.4 ± 0.9 Ma constrain a distinct episode of rapid Pliocene to Present exhumation; north and south of this belt, zircon (U-Th)/He ages are older (7.0 ± 0.7 Ma to 42.2 ± 2.1 Ma). We attribute the Pliocene rapid exhumation episode to basal accretion to the Himalayan thrust belt and duplex formation in the Lesser Himalayan sequence including initiation of the Munsiari thrust. Pecube thermokinematic modelling suggests exhumation rates of ∼2-3 mm/yr from 4-7 to 0 Ma above the duplex contrasting with lower (middle-late Miocene exhumation rates. The Munsiari thrust terminates laterally in central Himachal Pradesh. In the NW Indian Himalaya, the Main Central thrust zone comprises the sheared basal sections of the Greater Himalayan sequence and the mylonitic 'Bajaura nappe' of Lesser Himalayan affinity. We correlate the Bajaura unit with the Ramgarh thrust sheet in Nepal based on similar lithologies and the middle Miocene age of deformation. The Munsiari thrust in the central Himachal Himalaya is several Myr younger than deformation in the Bajaura and Ramgarh thrust sheets. Our results illustrate the complex and segmented nature of the Munsiari-Ramgarh-Shumar thrust system.

Foothills model forest grizzly bear study : project update

Energy Technology Data Exchange (ETDEWEB)

NONE

2002-01-01

This report updates a five year study launched in 1999 to ensure the continued healthy existence of grizzly bears in west-central Alberta by integrating their needs into land management decisions. The objective was to gather better information and to develop computer-based maps and models regarding grizzly bear migration, habitat use and response to human activities. The study area covers 9,700 square km in west-central Alberta where 66 to 147 grizzly bears exist. During the first 3 field seasons, researchers captured and radio collared 60 bears. Researchers at the University of Calgary used remote sensing tools and satellite images to develop grizzly bear habitat maps. Collaborators at the University of Washington used trained dogs to find bear scat which was analyzed for DNA, stress levels and reproductive hormones. Resource Selection Function models are being developed by researchers at the University of Alberta to identify bear locations and to see how habitat is influenced by vegetation cover and oil, gas, forestry and mining activities. The health of the bears is being studied by researchers at the University of Saskatchewan and the Canadian Cooperative Wildlife Health Centre. The study has already advanced the scientific knowledge of grizzly bear behaviour. Preliminary results indicate that grizzlies continue to find mates, reproduce and gain weight and establish dens. These are all good indicators of a healthy population. Most bear deaths have been related to poaching. The study will continue for another two years. 1 fig.

Eastern slopes grizzly bear project : project update

Energy Technology Data Exchange (ETDEWEB)

NONE

2002-01-01

This report updates a study to examine the cumulative effects of human activities on the grizzly bears in the central Canadian Rockies. The project was initiated in 1994 to acquire accurate scientific information on the habitat and populations of grizzly bears in the area of the Banff National Park and Kananaskis Country. This area is probably the most heavily used and developed area where the grizzly still survives. The information gathered throughout the course of the study is used to better protect and manage the bears and other sensitive carnivores in the region. Using telemetry, researchers monitored 25 grizzly bears which were radio-collared in a 22,000 square-kilometer area in the upper Bow Valley drainage of the eastern Alberta slopes. The researchers worked with representatives from Husky Oil and Rigel Energy on the development of the Moose Mountain oil and gas field without adversely affecting the grizzly bear population. Information collected over eight years indicates that the grizzly bears have few and infrequent offspring. Using the information gathered thus far, the location of the Moose Mountain to Jumping Pound pipeline was carefully selected, since the bears suffer from high mortality, and the food and cover had already been compromised by the high number of roads, trails and other human activities in the area. The research concluded in November 2001 provides sufficient information to accurately asses the status of the grizzly bear population and habitat. The data will be analyzed and integrated in 2002 into models that reflect the variables affecting grizzly bears and a final report will be published.

Polar bears at risk

Energy Technology Data Exchange (ETDEWEB)

Norris, S.; Rosentrater, L.; Eid, P.M. [WWF International Arctic Programme, Oslo (Norway)

2002-05-01

Polar bears, the world's largest terrestrial carnivore, spend much of their lives on the arctic sea ice. This is where they hunt and move between feeding, denning, and resting areas. The world population, estimated at 22,000 bears, is made up of 20 relatively distinct populations varying in size from a few hundred to a few thousand animals. About 60 per cent of all polar bears are found in Canada. In general, the status of this species is stable, although there are pronounced differences between populations. Reductions in the extent and thickness of sea ice has lead the IUCN Polar Bear Specialist Group to describe climate change as one of the major threats facing polar bears today. Though the long-term effects of climate change will vary in different areas of the Arctic, impacts on the condition and reproductive success of polar bears and their prey are likely to be negative. Longer ice-free periods resulting from earlier break-up of sea ice in the spring and later formation in the fall is already impacting polar bears in the southern portions of their range. In Canada's Hudson Bay, for example, bears hunt on the ice through the winter and into early summer, after which the ice melts completely, forcing bears ashore to fast on stored fat until freeze-up in the fall. The time bears have on the ice to hunt and build up their body condition is cut short when the ice melts early. Studies from Hudson Bay show that for every week earlier that ice break-up occurs, bears will come ashore 10 kg lighter and in poorer condition. It is likely that populations of polar bears dividing their time between land and sea will be severely reduced and local extinctions may occur as greenhouse gas emissions continue to rise and sea ice melts. Expected changes in regional weather patterns will also impact polar bears. Rain in the late winter can cause maternity dens to collapse before females and cubs have departed, thus exposing occupants to the elements and to predators. Such

Analysis of Fault Spacing in Thrust-Belt Wedges Using Numerical Modeling

Science.gov (United States)

Regensburger, P. V.; Ito, G.

2017-12-01

Numerical modeling is invaluable in studying the mechanical processes governing the evolution of geologic features such as thrust-belt wedges. The mechanisms controlling thrust fault spacing in wedges is not well understood. Our numerical model treats the thrust belt as a visco-elastic-plastic continuum and uses a finite-difference, marker-in-cell method to solve for conservation of mass and momentum. From these conservation laws, stress is calculated and Byerlee's law is used to determine the shear stress required for a fault to form. Each model consists of a layer of crust, initially 3-km-thick, carried on top of a basal décollement, which moves at a constant speed towards a rigid backstop. A series of models were run with varied material properties, focusing on the angle of basal friction at the décollement, the angle of friction within the crust, and the cohesion of the crust. We investigate how these properties affected the spacing between thrusts that have the most time-integrated history of slip and therefore have the greatest effect on the large-scale undulations in surface topography. The surface position of these faults, which extend through most of the crustal layer, are identifiable as local maxima in positive curvature of surface topography. Tracking the temporal evolution of faults, we find that thrust blocks are widest when they first form at the front of the wedge and then they tend to contract over time as more crustal material is carried to the wedge. Within each model, thrust blocks form with similar initial widths, but individual thrust blocks develop differently and may approach an asymptotic width over time. The median of thrust block widths across the whole wedge tends to decrease with time. Median fault spacing shows a positive correlation with both wedge cohesion and internal friction. In contrast, median fault spacing exhibits a negative correlation at small angles of basal friction (laws that can be used to predict fault spacing in

Detachments in Shale: Controlling Characteristics on Fold-Thrust Belt Style

Science.gov (United States)

Hansberry, Rowan; King, Ros; Collins, Alan; Morley, Chris

2013-04-01

Fold-thrust belts occur across multiple tectonic settings where thin-skinned deformation is accommodated by one or more detachment zones, both basal and within the fold-thrust belt. These fold-thrust belts exhibit considerable variation in structural style and vergence depending on the characteristics (e.g. strength, thickness, and lithology) and number of detachment zones. Shale as a detachment lithology is intrinsically weaker than more competent silts and sands; however, it can be further weakened by high pore pressures, reducing resistance to sliding and; high temperatures, altering the rheology of the detachment. Despite the implications for petroleum exploration and natural hazard assessment the precise nature by which detachments in shale control and are involved in deformation in fold-thrust belts is poorly understood. Present-day active basal detachment zones are usually located in inaccessible submarine regions. Therefore, this project employs field observations and sample analysis of ancient, exhumed analogues to document the nature of shale detachments (e.g. thickness, lithology, dip and dip direction, deformational temperature and thrust propagation rates) at field sites in Thailand, Norway and New Zealand. X-ray diffraction analysis of illite crystallinity and oxygen stable isotopes analysis are used as a proxy for deformational temperature whilst electron-backscatter diffraction analysis is used to constrain microstructural deformational patterns. K-Ar dating of synkinematic clay fault gouges is being applied to date the final stages of activity on individual faults with a view to constraining thrust activation sequences. It is not possible to directly measure palaeo-data for some key detachment parameters, such as pore pressure and coefficients of friction. However, the use of critical taper wedge theory has been used to successfully infer internal and basal coefficients of friction and depth-normalized pore pressure within a wedge and at its base

Gas turbine electric generator

International Nuclear Information System (INIS)

Nemoto, Masaaki; Yuhara, Tetsuo.

1993-01-01

When troubles are caused to a boundary of a gas turbine electric generator, there is a danger that water as an operation medium for secondary circuits leaks to primary circuits, to stop a plant and the plant itself can not resume. Then in the present invention, helium gases are used as the operation medium not only for the primary circuits but also for the secondary circuits, to provide so-called a direct cycle gas turbine system. Further, the operation media of the primary and secondary circuits are recycled by a compressor driven by a primary circuit gas turbine, and the turbine/compressor is supported by helium gas bearings. Then, problems of leakage of oil and water from the bearings or the secondary circuits can be solved, further, the cooling device in the secondary circuit is constituted as a triple-walled tube structure by way of helium gas, to prevent direct leakage of coolants into the reactor core even if cracks are formed to pipes. (N.H.)

A study of variable thrust, variable specific impulse trajectories for solar system exploration

Science.gov (United States)

Sakai, Tadashi

A study has been performed to determine the advantages and disadvantages of variable thrust and variable Isp (specific impulse) trajectories for solar system exploration. There have been several numerical research efforts for variable thrust, variable Isp, power-limited trajectory optimization problems. All of these results conclude that variable thrust, variable Isp (variable specific impulse, or VSI) engines are superior to constant thrust, constant Isp (constant specific impulse; or CSI) engines. However, most of these research efforts assume a mission from Earth to Mars, and some of them further assume that these planets are circular and coplanar. Hence they still lack the generality. This research has been conducted to answer the following questions: (1) Is a VSI engine always better than a CSI engine or a high thrust engine for any mission to any planet with any time of flight considering lower propellant mass as the sole criterion? (2) If a planetary swing-by is used for a VSI trajectory, is the fuel savings of a VSI swing-by trajectory better than that of a CSI swing-by or high thrust swing-by trajectory? To support this research, an unique, new computer-based interplanetary trajectory calculation program has been created. This program utilizes a calculus of variations algorithm to perform overall optimization of thrust, Isp, and thrust vector direction along a trajectory that minimizes fuel consumption for interplanetary travel. It is assumed that the propulsion system is power-limited, and thus the compromise between thrust and Isp is a variable to be optimized along the flight path. This program is capable of optimizing not only variable thrust trajectories but also constant thrust trajectories in 3-D space using a planetary ephemeris database. It is also capable of conducting planetary swing-bys. Using this program, various Earth-originating trajectories have been investigated and the optimized results have been compared to traditional CSI and high

14 CFR 23.934 - Turbojet and turbofan engine thrust reverser systems tests.

Science.gov (United States)

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Turbojet and turbofan engine thrust... CATEGORY AIRPLANES Powerplant General § 23.934 Turbojet and turbofan engine thrust reverser systems tests. Thrust reverser systems of turbojet or turbofan engines must meet the requirements of § 33.97 of this...

Peak thrust operation of linear induction machines from parameter identification

Energy Technology Data Exchange (ETDEWEB)

Zhang, Z.; Eastham, T.R.; Dawson, G.E. [Queen`s Univ., Kingston, Ontario (Canada). Dept. of Electrical and Computer Engineering

1995-12-31

Various control strategies are being used to achieve high performance operation of linear drives. To maintain minimum volume and weight of the power supply unit on board the transportation vehicle, peak thrust per unit current operation is a desirable objective. True peak thrust per unit current through slip control is difficult to achieve because the parameters of linear induction machines vary during normal operation. This paper first develops a peak thrust per unit current control law based on the per-phase equivalent circuit for linear induction machines. The algorithm for identification of the variable parameters in induction machines is then presented. Application to an operational linear induction machine (LIM) demonstrates the utility of this algorithm. The control strategy is then simulated, based on an operational transit LIM, to show the capability of achieving true peak thrust operation for linear induction machines.

Static, Dynamic, and Thermal Properties of Compressible Fluid Film Journal Bearings

DEFF Research Database (Denmark)

Paulsen, Bo Terp; Morosi, Stefano; Santos, Ilmar

2011-01-01

fluid film journal bearing, in order to identify when this type of analysis should be of concern. Load capacity, stiffness, and damping coefficients are determined by the solution of the standard Reynolds equation coupled to the energy equation. Numerical investigations show how bearing geometry......, and work great efficiency. A great deal of literature has concentrated on the analysis and prediction of the static and dynamic performance of gas bearings, assuming isothermal conditions. The present contribution presents a detailed mathematical modeling for nonisothermal lubrication of a compressible...

Altitude-Wind-Tunnel Investigation of a 4000-Pound-Thrust Axial-Flow Turbojet Engine. II - Operational Characteristics. II; Operational Characteristics

Science.gov (United States)

Fleming, William A.

1948-01-01

An investigation was conducted in the Cleveland altitude wind tunnel to determine the operational characteristics of an axial flow-type turbojet engine with a 4000-pound-thrust rating over a range of pressure altitudes from 5,000 to 50,OOO feet, ram pressure ratios from 1.00 to 1.86, and temperatures from 60 deg to -50 deg F. The low-flow (standard) compressor with which the engine was originally equipped was replaced by a high-flow compressor for part of the investigation. The effects of altitude and airspeed on such operating characteristics as operating range, stability of combustion, acceleration, starting, operation of fuel-control systems, and bearing cooling were investigated. With the low-flow compressor, the engine could be operated at full speed without serious burner unbalance at altitudes up to 50,000 feet. Increasing the altitude and airspeed greatly reduced the operable speed range of the engine by raising the minimum operating speed of the engine. In several runs with the high-flow compressor the maximum engine speed was limited to less than 7600 rpm by combustion blow-out, high tail-pipe temperatures, and compressor stall. Acceleration of the engine was relatively slow and the time required for acceleration increased with altitude. At maximum engine speed a sudden reduction in jet-nozzle area resulted in an immediate increase in thrust. The engine started normally and easily below 20,000 feet with each configuration. The use of a high-voltage ignition system made possible starts at a pressure altitude of 40,000 feet; but on these starts the tail-pipe temperatures were very high, a great deal of fuel burned in and behind the tail-pipe, and acceleration was very slow. Operation of the engine was similar with both fuel regulators except that the modified fuel regulator restricted the fuel flow in such a manner that the acceleration above 6000 rpm was very slow. The bearings did not cool properly at high altitudes and high engine speeds with a low

BEARS: Radioactive ion beams at LBNL

International Nuclear Information System (INIS)

Powell, J.; Guo, F.Q.; Haustein, P.E.

1998-01-01

BEARS (Berkeley Experiments with Accelerated Radioactive Species) is an initiative to develop a radioactive ion-beam capability at Lawrence Berkeley National Laboratory. The aim is to produce isotopes at an existing medical cyclotron and to accelerate them at the 88 inch Cyclotron. To overcome the 300-meter physical separation of these two accelerators, a carrier-gas transport system will be used. At the terminus of the capillary, the carrier gas will be separated and the isotopes will be injected into the 88 inch Cyclotron's Electron Cyclotron Resonance (ECR) ion source. The first radioactive beams to be developed will include 20-min 11 C and 70-sec 14 O, produced by (p,n) and (p,α) reactions on low-Z targets. A test program is currently being conducted at the 88 inch Cyclotron to develop the parts of the BEARS system. Preliminary results of these tests lead to projections of initial 11 C beams of up to 2.5 x 10 7 ions/sec and 14 O beams of 3 x 10 5 ions/sec

Strength Estimation for Hydrate-Bearing Sediments From Direct Shear Tests of Hydrate-Bearing Sand and Silt

Science.gov (United States)

Liu, Zhichao; Dai, Sheng; Ning, Fulong; Peng, Li; Wei, Houzhen; Wei, Changfu

2018-01-01

Safe and economic methane gas production, as well as the replacement of methane while sequestering carbon in natural hydrate deposits, requires enhanced geomechanical understanding of the strength and volume responses of hydrate-bearing sediments during shear. This study employs a custom-made apparatus to investigate the mechanical and volumetric behaviors of carbon dioxide hydrate-bearing sediments subjected to direct shear. The results show that both peak and residual strengths increase with increased hydrate saturation and vertical stress. Hydrate contributes mainly the cohesion and dilatancy constraint to the peak strength of hydrate-bearing sediments. The postpeak strength reduction is more evident and brittle in specimens with higher hydrate saturation and under lower stress. Significant strength reduction after shear failure is expected in silty sediments with high hydrate saturation Sh ≥ 0.65. Hydrate contribution to the residual strength is mainly by increasing cohesion at low hydrate saturation and friction at high hydrate saturation. Stress state and hydrate saturation are dominating both the stiffness and the strength of hydrate-bearing sediments; thus, a wave velocity-based peak strength prediction model is proposed and validated, which allows for precise estimation of the shear strength of hydrate-bearing sediments through acoustic logging data. This method is advantageous to geomechanical simulators, particularly when the experimental strength data of natural samples are not available.

Thrust and jet directional control using the Coanda effect

Directory of Open Access Journals (Sweden)

Alexandru DUMITRACHE

2018-06-01

Full Text Available The application of the Coandă effect to the directional control of a jet or thrust is presented. Deviation of the thrust force by direct flow can be achieved by using the Coandă effect to change the angle of the primary jet engine exhaust nozzle. Major interest in the study of this phenomenon is caused by the possibility of using this effect for aircrafts with short take-off and landing, for thrust vectoring. The numerical investigations are performed using a RANS solver with an adequate turbulence model, showing a change of the jet direction. Thus, the conditions and the limits within which one can benefit from the advantages of Coandă-type flows are determined.

MHD thrust vectoring of a rocket engine

Science.gov (United States)

Labaune, Julien; Packan, Denis; Tholin, Fabien; Chemartin, Laurent; Stillace, Thierry; Masson, Frederic

2016-09-01

In this work, the possibility to use MagnetoHydroDynamics (MHD) to vectorize the thrust of a solid propellant rocket engine exhaust is investigated. Using a magnetic field for vectoring offers a mass gain and a reusability advantage compared to standard gimbaled, elastomer-joint systems. Analytical and numerical models were used to evaluate the flow deviation with a 1 Tesla magnetic field inside the nozzle. The fluid flow in the resistive MHD approximation is calculated using the KRONOS code from ONERA, coupling the hypersonic CFD platform CEDRE and the electrical code SATURNE from EDF. A critical parameter of these simulations is the electrical conductivity, which was evaluated using a set of equilibrium calculations with 25 species. Two models were used: local thermodynamic equilibrium and frozen flow. In both cases, chlorine captures a large fraction of free electrons, limiting the electrical conductivity to a value inadequate for thrust vectoring applications. However, when using chlorine-free propergols with 1% in mass of alkali, an MHD thrust vectoring of several degrees was obtained.

Computing Analysis of Bearing Elements of Launch Complex Aggregates for Space Rocket "Soyuz-2.1v"

Directory of Open Access Journals (Sweden)

V. A. Zverev

2014-01-01

Full Text Available The research is devoted to the computational analysis of bearing structures of launch system aggregates, which are designed for the prelaunch preparation and launch security of space rocket (SR "SOYUZ-2" of 1B stage. The bearing structures taken under consideration are the following: supporting trusses (ST, bearing arms (BA, the upper cable girder (UCG, the umbilical mast (UM. The SR “SOYUZ-2" of 1B stage has the characteristics of the propulsion unit (PU thrust, different from those of the "Soyuz" family space rockets exploited before.The paper presents basic modeling principles to calculate units and their operating loadings. The body self-weight and the influence of a gas-dynamic jet of "SOYUZ-2.1B" propulsion unit have been considered as a load of units. Parameters of this influence are determined on the basis of impulse stream fields and of deceleration temperatures calculated for various SR positions according to the specified path of its ascent and demolition.Physical models of the aggregates and calculations are based on the finite elements method and super-elements method using “SADAS” software package developed at the chair SM8 of Bauman Moscow State Technical University.Fields of nodal temperatures distribution in the ST, BA, UCG, UM models, and fields of tension in finite elements as well represent the calculation results.Obtained results revealed the most vulnerable of considered starting system aggregates, namely UM, which was taken for local durability calculation. As an example, this research considers calculation of local durability in the truss branches junction of UM rotary part, for which the constructive strengthening has been offered. For this node a detailed finite-element model built in the model of UM rotary part has been created. Calculation results of local durability testify that the strengthened node meets durability conditions.SR developers used calculation results of launch system aggregates for the space

Development of a Ceramic Rolling Contact Bearing for High Temperature Use

Science.gov (United States)

1961-07-11

operation) suspended in a gas stream was suprlied sufficient hardness, stability, and strength in through a tube in the bearing housing and was ex- an...and microfine MOS2, dried and screened, was supplied radial bearing mounting surfaces was less than to the bearing at an average rate of about 0.16...L.UBRICANT B ATMOSPHERE I".LlT TUBE DRILL TS5.ULAiT. INT. SEAL B TAP ONE KOLE I*G1-TEtMPjRAIUNE AS 45- TO SHEAR PIN SLOT FOR TTREAO END FLOW FOR HEATINM OP

Complex thrusting at the toe of the Nankai accretionary prism, NanTroSEIZE Kumano transect

Science.gov (United States)

Moore, G. F.; Park, J.; Kodaira, S.; Kaneda, Y.

2009-12-01

Seismic reflection data collected over the past 10 years by the Institute for Research on Earth Evolution (IFREE) of Japan Agency for Marine Earth Science and Technology (JAMSTEC) image a zone of complex thrusting at the toe of the Nankai accretionary prism south of Kii Peninsula, Honshu, Japan. The frontal part of the Nankai prism west of Shionomisaki Canyon (SC) at ~136° E, including the Muroto and Ashizuri Transects off Shikoku, is generally formed of imbricate thrusts with spacing of ~ 1-3 km that dip ~25-35° landward and sole into a prominent décollement. Out-of-sequence thrusts (OOSTs) are usually restricted to the landward margin of this imbricate thrust zone. East of SC, in the Kumano Transect area, the imbricate thrust zone is bounded on its seaward edge by a frontal thrust block that is ~5-6 km wide and consists of several OOSTs. The frontal thrust dips ~5-10° under this ~2-4 km thick block, emplacing this thrust sheet over the trench floor. The number and character of thrusts within the frontal thrust block vary laterally along strike. The 2006 Kumano 3D seismic data set images details of one segment of this complex frontal thrust block. Out-of-sequence faulting has led to underplating of several smaller thrust slices and movement along oblique ramps has led to a complex pattern of faulting that cannot be recognized in even closely-spaced 2D seismic lines. The frontal thrust block is further modified by subduction of seamounts and ridges that have caused large slumps of material from the block.

Aircraft gas turbines

Energy Technology Data Exchange (ETDEWEB)

Arai, M [Kawasaki Heavy Industries Ltd., Kobe (Japan)

1995-03-01

Recently the international relationship has been playing an important role in the research, development and production of the aircraft gas turbine. The YSX, which is supposed to be the 100-seat class commercial aircraft, has been planned by Japan Aircraft Development (JADC) as an international cooperative project. Recently many western aeroengine companies have offered the collaboration of small turbofan engines which would be installed on YSX to Japanese aeroengine companies (IHI, KHI and MHI). The YSX is powered by 16,000-20,000 1bs thrust class engines. As for medium turbofan engine (V2500), the V 2500 family of 22,000 to 30,000 1bs thrust has been developed since 1983 through international collaboration by seven aeroengine companies in five nations. In this paper, the recent Japan`s activities of the research, development and production with viewing the world-wide movement, are described. 6 figs.

Developing stochastic model of thrust and flight dynamics for small UAVs

Science.gov (United States)

Tjhai, Chandra

This thesis presents a stochastic thrust model and aerodynamic model for small propeller driven UAVs whose power plant is a small electric motor. First a model which relates thrust generated by a small propeller driven electric motor as a function of throttle setting and commanded engine RPM is developed. A perturbation of this model is then used to relate the uncertainty in throttle and engine RPM commanded to the error in the predicted thrust. Such a stochastic model is indispensable in the design of state estimation and control systems for UAVs where the performance requirements of the systems are specied in stochastic terms. It is shown that thrust prediction models for small UAVs are not a simple, explicit functions relating throttle input and RPM command to thrust generated. Rather they are non-linear, iterative procedures which depend on a geometric description of the propeller and mathematical model of the motor. A detailed derivation of the iterative procedure is presented and the impact of errors which arise from inaccurate propeller and motor descriptions are discussed. Validation results from a series of wind tunnel tests are presented. The results show a favorable statistical agreement between the thrust uncertainty predicted by the model and the errors measured in the wind tunnel. The uncertainty model of aircraft aerodynamic coefficients developed based on wind tunnel experiment will be discussed at the end of this thesis.

Why style matters - uncertainty and structural interpretation in thrust belts.

Science.gov (United States)

Butler, Rob; Bond, Clare; Watkins, Hannah

2016-04-01

Structural complexity together with challenging seismic imaging make for significant uncertainty in developing geometric interpretations of fold and thrust belts. Here we examine these issues and develop more realistic approaches to building interpretations. At all scales, the best tests of the internal consistency of individual interpretations come from structural restoration (section balancing), provided allowance is made for heterogeneity in stratigraphy and strain. However, many existing balancing approaches give misleading perceptions of interpretational risk - both on the scale of individual fold-thrust (trap) structures and in regional cross-sections. At the trap-scale, idealised models are widely cited - fault-bend-fold, fault-propagation folding and trishear. These make entirely arbitrary choices for fault localisation and layer-by-layer deformation: precise relationships between faults and fold geometry are generally invalidated by real-world conditions of stratigraphic variation and distributed strain. Furthermore, subsurface predictions made using these idealisations for hydrocarbon exploration commonly fail the test of drilling. Rarely acknowledged, the geometric reliability of seismic images depends on the assigned seismic velocity model, which in turn relies on geological interpretation. Thus iterative approaches are required between geology and geophysics. The portfolio of commonly cited outcrop analogues is strongly biased to examples that simply conform to idealised models - apparently abnormal structures are rarely described - or even photographed! Insight can come from gravity-driven deep-water fold-belts where part of the spectrum of fold-thrust complexity is resolved through seismic imaging. This imagery shows deformation complexity in fold forelimbs and backlimbs. However, the applicability of these, weakly lithified systems to well-lithified successions (e.g. carbonates) of many foreland thrust belts remains conjectural. Examples of

Quadcopter Attitude and Thrust Simulation Based on Simulink Platform

Directory of Open Access Journals (Sweden)

Endrowednes Kuantama

2015-12-01

Full Text Available Orientation of quadcopter axes relative to reference line direction of motion will result in attitude and every movement is controlled regulated by each rotor’s thrust. Mathematical equation based on Euler formula and 3D simulation using Matlab/Simulink software platform are used to model quadcopter movement. Change of attitude, position and thrust of each rotor can be seen through this simulation movement.

Impacts of Hydrate Distribution on the Hydro-Thermo-Mechanical Properties of Hydrate-Bearing Sediments

Science.gov (United States)

Dai, S.; Seol, Y.

2015-12-01

In general, hydrate makes the sediments hydraulically less conductive, thermally more conductive, and mechanically stronger; yet the dependency of these physical properties on hydrate saturation varies with hydrate distribution and morphology. Hydrate distribution in sediments may cause the bulk physical properties of their host sediments varying several orders of magnitude even with the same amount of hydrate. In natural sediments, hydrate morphology is inherently governed by the burial depth and the grain size of the host sediments. Compare with patchy hydrate, uniformly distributed hydrate is more destructive to fluid flow, yet leads to higher gas and water permeability during hydrate dissociation due to the easiness of forming percolation paths. Water and hydrate have similar thermal conductivity values; the bulk thermal conductivity of hydrate-bearing sediments depends critically on gas-phase saturation. 60% of gas saturation may result in evident thermal conductivity drop and hinder further gas production. Sediments with patchy hydrate yield lower stiffness than that with cementing hydrate but higher stiffness than that with pore filling and loading bearing hydrate. Besides hydrate distribution, the stress state and loading history also play an important role in the mechanical behavior of hydrate-bearing sediments.

Idaho Nuclear Technology and Engineering Center Sodium-Bearing Waste Treatment Research and Development FY-2002 Status Report

Energy Technology Data Exchange (ETDEWEB)

Herbst, Alan Keith; Deldebbio, John Anthony; Mc Cray, John Alan; Kirkham, Robert John; Olson, Lonnie Gene; Scholes, Bradley Adams

2002-09-01

The Idaho National Engineering and Environmental Laboratory (INEEL) is considering several optional processes for disposal of liquid sodium-bearing waste. During fiscal year 2002, immobilization-related research included of grout formulation development for sodium-bearing waste, absorption of the waste on silica gel, and off-gas system mercury collection and breakthrough using activated carbon. Experimental results indicate that sodium-bearing waste can be immobilized in grout at 70 weight percent and onto silica gel at 74 weight percent. Furthermore, a loading of 11 weight percent mercury in sulfur-impregnated activated carbon was achieved with 99.8% off-gas mercury removal efficiency.

HI-bearing Ultra Diffuse Galaxies in the ALFALFA Survey

Science.gov (United States)

Leisman, Lukas; Janowiecki, Steven; Jones, Michael G.; ALFALFA Almost Darks Team

2018-01-01

The Arecibo Legacy Fast ALFA (Arecibo L-band Feed Array) extragalactic HI survey, with over 30,000 high significance extragalactic sources, is well positioned to locate gas-bearing, low surface brightness sources missed by optical detection algorithms. We investigate the nature of a population of HI-bearing sources in ALFALFA with properties similar to "ultra-diffuse" galaxies (UDGs): galaxies with stellar masses of dwarf galaxies, but radii of L* galaxies. These "HI-bearing ultra-diffuse" sources (HUDS) constitute a small, but pertinent, fraction of the dwarf-mass galaxies in ALFALFA. They are bluer and have more irregular morphologies than the optically-selected UDGs found in clusters, and they appear to be gas-rich for their stellar mass, indicating low star formation efficiency. To illuminate potential explanations for the extreme properties of these sources we explore their environments and estimate their halo properties. We conclude that environmental mechanism are unlikely the cause of HUDS' properties, as they exist in environments equivalent to that of the other ALFALFA sources of similar HI-masses, however, we do find some suggestion that these HUDS may reside in high spin parameter halos, a potential explanation for their "ultra-diffuse" nature.

Measurements of energy distribution and thrust for microwave plasma coupling of electrical energy to hydrogen for propulsion

Science.gov (United States)

Morin, T.; Chapman, R.; Filpus, J.; Hawley, M.; Kerber, R.; Asmussen, J.; Nakanishi, S.

1982-01-01

A microwave plasma system for transfer of electrical energy to hydrogen flowing through the system has potential application for coupling energy to a flowing gas in the electrothermal propulsion concept. Experimental systems have been designed and built for determination of the energy inputs and outputs and thrust for the microwave coupling of energy to hydrogen. Results for experiments with pressure in the range 100 microns-6 torr, hydrogen flow rate up to 1000 micronmoles/s, and total absorbed power to 700 w are presented.

Seafloor expression and shallow structure of a fold-and-thrust system, Isfjorden, west Spitsbergen

Directory of Open Access Journals (Sweden)

Maria Blinova

2012-09-01

Full Text Available A detailed map of the structure of the west Spitsbergen fold-and-thrust belt in the Isfjorden area, Spitsbergen, is presented. The map was constructed from a dense grid of two-dimensional multichannel reflection seismic and bathymetric data. Joint interpretation of two data sets allowed a comparison of tectonic structures detected along the uppermost parts of the seismic sections and those reflected in the morphology of the seafloor. Three major, predominantly north-west–south-east striking faults were identified. The westernmost fault (T1 is a hinterland-directed (most likely out of sequence thrust, while the central and easternmost faults (T2 and T3 are foreland-directed (in-sequence thrusts. The thrusts divide Isfjorden into three subareas. Subarea 1 is bounded by thrust faults T1 and T2 and comprises Tertiary rocks surrounded by Jurassic–Cretaceous strata. The structural signature of Subarea 1 is that of a system of hinterland- and foreland-directed thrust faults, resulting in a seafloor relief characterized by parallel ridges and troughs. Subarea 2 is limited by thrust faults T2 and T3 and shows Jurassic–Cretaceous outcrops on the seafloor. Subarea 3 is situated east of the main thrust fault T3 and mainly involves outcrops of Triassic–Jurassic rocks. Together, Subareas 2 and 3 are dominated by foreland-directed, north-west–south-east and NNW–SSE-striking thrusts that are hardly detectable in bathymetric data.

Implications of rapid environmental change for polar bear behavior and sociality

Science.gov (United States)

Atwood, Todd C.

2017-01-01

Historically, the Arctic sea ice has functioned as a structural barrier that has limited the nature and extent of interactions between humans and polar bears (Ursus maritimus). However, declining sea ice extent, brought about by global climate change, is increasing the potential for human-polar bear interactions. Loss of sea ice habitat is driving changes to both human and polar bear behavior—it is facilitating increases in human activities (e.g., offshore oil and gas exploration and extraction, trans-Arctic shipping, recreation), while also causing the displacement of bears from preferred foraging habitat (i.e., sea ice over biologically productive shallow) to land in some portions of their range. The end result of these changes is that polar bears are spending greater amounts of time in close proximity to people. Coexistence between humans and polar bears will require imposing mechanisms to manage further development, as well as mitigation strategies that reduce the burden to local communities.

Relationships between basin architecture, basin closure, and occurrence of sulphide-bearing schists: an example from Tampere Schist Belt, Finland

DEFF Research Database (Denmark)

Kalliomäki, Henrik; Torvela, Taija; Moreau, Julien

, therefore, offers an excellent opportunity to examine the volcano-sedimentary evolution of an ancient marginal basin, and the mechanics of and strain distribution during its subsequent closure. The aim of this study is to investigate the structural development and the architecture of a part of the TSB...... in more detail, including the relationships between the volcano-sedimentary sequences, the tectonic structures, and the sulphide-bearing schist horizons. Important insights are gained into understanding the mechanisms of the basin closure and the localisation of the sulphide mineralisation within......, in order to accommodate the crustal shortening during basin closure. Furthermore, it is suggested that there is a genetic relationship between the interpreted palaeothrusts and the sulphide-bearing schist horizons in the study area: early, gently dipping thrusts acted as both channels and traps...

In bear country: peaceful co-existence with a touchy wilderness icon starting to look possible

Energy Technology Data Exchange (ETDEWEB)

Podlubny, J.

2002-10-07

How oil and gas companies have harnessed location data maps and satellite communication technology to help resource developers to map out new roads and pipelines in the grizzly bear habitat of western Alberta is described. The high-tech approach is part of the Foot Hills Model Forest Grizzly Bear Study project, operating out of Hinton, Alberta, which focuses on the effects of industrial activity on the Alberta grizzly bear. Since the project's inception three years ago a library of data has been collected with a tool known as the GPS collar. This collar attached to more than 70 bears enabled scientists to add new dimensions of precision and intimacy to the tracking of grizzly bears. The maps created from data captured by the collars have been used by forestry and oil and gas industry personnel to help establish working relationships with grizzly bears by using the information as a guide to decisions on which routes are best suited for road and pipeline projects, i.e. which ones can be forecast to have the least effect on bears. The study is the first that has generated scientific information which is being used in a practical way to help preserve grizzly bears in the wild. At least one pipeline route has been changed when the company found out, through the mapping technology, that an area affected by the originally proposed route was an important grizzly bear habitat. The information also has been used in conjunction with developing new roads, mining locations and other activities that involve grizzly bear habitats. In addition to these practical industry-related applications the study also focuses on collecting new information about grizzly bears, clearing up bear myths, making discoveries about bear DNA, creating new trapping techniques and the best drugs to use when putting on collars and ear tags.

Duplex geometry: an example from the Moine Thrust Belt

Science.gov (United States)

Bowler, S.

1987-04-01

The geometry and microstructure of a small duplex formed in one bed from the Moine Thrust Belt of northwest Scotland is reported. The structure is seen in oblique section, within the Cambrian Pipe-rock, in an area of low strain. A range of movement direction indicators are present in the structure. An early grain shape fabric developed close to the roof thrust is taken as the best estimate of the overall movement direction towards 287°. Slickensides in the gouge developed on movement planes within the duplex show varied orientations on a given plane, and are not considered useful indicators of thrust transport direction. Branch lines exposed converge and diverge, suggesting little lateral continuity of the exposed structure. The microstructures present within the structure indicate an increase in localised deformation, and in cataclastic behavior as the duplex evolved. Early layer parallel shear is ubiquitous, giving rise to an elongate grain shape fabric close to bedding surfaces. In early formed horses, a layer-parallel, oblate grain shape fabric, which shows localised slip zones, is overprinted by gouge formation. Later formed horses show only fracturing and gouge development. This sequence is attributed to stick-slip behavior in the propagation or displacement of the original fault, now the floor thrust.

Equivalence ratio and constriction effects on RBCC thrust augmentation

Science.gov (United States)

Koupriyanov, M.; Etele, J.

2011-06-01

A theoretical analysis of a variable area rocket based combined cycle engine with and without simultaneous mixing and combustion is presented. The flowfield is solved using a steady, quasi-one-dimensional, inviscid control volume formulation with combustion effects included via a generalized equilibrium calculation. Compression augmentation is shown to be sensitive to the equivalence ratio within the primary rocket chamber, where ejector section performance is greatest at both low and high equivalence ratios but near a minimum at stoichiometric conditions. The thrust generated by the RBCC engine compared to that generated by the same rocket in isolation can be increased by as much as 12% at constriction ratios of between 45% and 50%. Thrust augmentation is also shown to vary with equivalence ratio, where for a fixed geometry the maximum thrust is generated at equivalence ratios slightly below unity.

Real Gas Effects on the Performance of Hydrocarbon-fueled Pulse Detonation Engines

Science.gov (United States)

Povinelli, Louis A.; Yungster, Shaye

2003-01-01

This paper presents results for a single-pulse detonation tube wherein the effects of high temperature dissociation and the subsequent recombination influence the sensible heat release available for providing propulsive thrust. The study involved the use of ethylene and air at equivalence ratios of 0.7 and 1.0. The real gas effects on the sensible heat release were found to be significantly large so as to have an impact on the thrust, impulse and fuel consumption of a PDE.

A systematic review of thrust manipulation for non-surgical shoulder conditions.

Science.gov (United States)

Minkalis, Amy L; Vining, Robert D; Long, Cynthia R; Hawk, Cheryl; de Luca, Katie

2017-01-01

Although many conservative management options are available for patients with non-surgical shoulder conditions, there is little evidence of their effectiveness. This review investigated one manual therapy approach, thrust manipulation, as a treatment option. A systematic search was conducted of the electronic databases from inception to March 2016: PubMed, PEDro, ICL, CINAHL, and AMED. Two independent reviewers conducted the screening process to determine article eligibility. Inclusion criteria were manuscripts published in peer-reviewed journals with human participants of any age. The intervention included was thrust, or high-velocity low-amplitude, manipulative therapy directed to the shoulder and/or the regions of the cervical or thoracic spine. Studies investigating secondary shoulder pain or lacking diagnostic confirmation procedures were excluded. Methodological quality was assessed using the PEDro scale and the Cochrane risk-of-bias tool. The initial search rendered 5041 articles. After screening titles and abstracts, 36 articles remained for full-text review. Six articles studying subacromial impingement syndrome met inclusion criteria. Four studies were randomized controlled trials (RCTs) and 2 were uncontrolled clinical studies. Five studies included 1 application of a thoracic spine thrust manipulation and 1 applied 8 treatments incorporating a shoulder joint thrust manipulation. Statistically significant improvements in pain scores were reported in all studies. Three of 4 RCTs compared a thrust manipulation to a sham, and statistical significance in pain reduction was found within the groups but not between them. Clinically meaningful changes in pain were inconsistent; 3 studies reported that scores met minimum clinically important difference, 1 reported scores did not, and 2 were unclear. Four studies found statistically significant improvements in disability; however, 2 were RCTs and did not find statistical significance between the active and sham

Bearing system

Science.gov (United States)

Kapich, Davorin D.

1987-01-01

A bearing system includes backup bearings for supporting a rotating shaft upon failure of primary bearings. In the preferred embodiment, the backup bearings are rolling element bearings having their rolling elements disposed out of contact with their associated respective inner races during normal functioning of the primary bearings. Displacement detection sensors are provided for detecting displacement of the shaft upon failure of the primary bearings. Upon detection of the failure of the primary bearings, the rolling elements and inner races of the backup bearings are brought into mutual contact by axial displacement of the shaft.

Impact of pore-water freshening on clays and the compressibility of hydrate-bearing reservoirs during production

Energy Technology Data Exchange (ETDEWEB)

Jang, Junbong [U.S. Geological Survey, Woods Hole, MA; Cao, Shuang [Louisiana State University, Baton Rouge, LA; Waite, William [U.S. Geological Survey, Woods Hole, MA; Jung, Jongwon [Chungbuk National University, Cheongju-si, Chungbuk, South Korea

2017-06-25

Gas production efficiency from natural hydrate-bearing sediments depends in part on geotechnical properties of fine-grained materials, which are ubiquitous even in sandy hydrate-bearing sediments. The responses of fine-grained material to pore fluid chemistry changes due to freshening during hydrate dissociation could alter critical sediment characteristics during gas production activities. We investigate the electrical sensitivity of fine grains to pore fluid freshening and the implications of freshening on sediment compression and recompression parameters.

Test Results for a Non-toxic, Dual Thrust Reaction Control Engine

Science.gov (United States)

Robinson, Philip J.; Veith, Eric M.; Turpin, Alicia A.

2005-01-01

A non-toxic, dual thrust reaction control engine (RCE) was successfully tested over a broad range of operating conditions at the Aerojet Sacramento facility. The RCE utilized LOX/Ethanol propellants; and was tested in steady state and pulsing modes at 25-lbf thrust (vernier) and at 870-lbf thrust (primary). Steady state vernier tests vaned chamber pressure (Pc) from 0.78 to 5.96 psia, and mixture ratio (MR) from 0.73 to 1.82, while primary steady state tests vaned Pc from 103 to 179 psia and MR from 1.33 to 1.76. Pulsing tests explored EPW from 0.080 to 10 seconds and DC from 5 to 50 percent at both thrust levels. Vernier testing accumulated a total of 6,670 seconds of firing time, and 7,215 pulses, and primary testing accumulated a total of 2,060 seconds of firing time and 3,646 pulses.

Applying the anisotropy of magnetic susceptibility technique to the study of the tectonic evolution of the West Spitsbergen Fold-and-Thrust Belt

Directory of Open Access Journals (Sweden)

Katarzyna Dudzisz

2016-12-01

Full Text Available We demonstrate the use of the anisotropy of magnetic susceptibility (AMS method to determine the orientation of the principal tectonic strain directions developed during the formation of the West Spitsbergen Fold-and-Thrust Belt (WSFTB. The AMS measurements and extensive rock-magnetic studies of the Lower Triassic rocks reported here were focused on the recognition of the magnetic fabric, the identification of ferromagnetic minerals and an estimation of the influence of ferro- and paramagnetic minerals on magnetic susceptibility. At most sites, the paramagnetic minerals controlled the magnetic susceptibility, and at only one site the impact of ferromagnetic minerals was higher. The AMS technique documented the presence of different types of magnetic fabrics within the sampled sites. At two sites, a normal (Kmin perpendicular to the bedding magnetic fabric of sedimentary origin was detected. This was associated with a good clustering of the maximum AMS axes imposed by tectonic strain. The Kmax magnetic lineation directions obtained here parallel the general NNW–SSE trend of the WSFTB fold axial traces and thrust fronts. The two other investigated sites possessed mixed and inverted fabrics, the latter of which appear to reflect the presence of iron-bearing carbonates.

Late thrusting extensional collapse at the mountain front of the northern Apennines (Italy)

Science.gov (United States)

Tavani, Stefano; Storti, Fabrizio; Bausã, Jordi; MuñOz, Josep A.

2012-08-01

Thrust-related anticlines exposed at the mountain front of the Cenozoic Appenninic thrust-and-fold belt share the presence of hinterlandward dipping extensional fault zones running parallel to the hosting anticlines. These fault zones downthrow the crests and the backlimbs with displacements lower than, but comparable to, the uplift of the hosting anticline. Contrasting information feeds a debate about the relative timing between thrust-related folding and beginning of extensional faulting, since several extensional episodes, spanning from early Jurassic to Quaternary, are documented in the central and northern Apennines. Mesostructural data were collected in the frontal anticline of the Sibillini thrust sheet, the mountain front in the Umbria-Marche sector of the northern Apennines, with the aim of fully constraining the stress history recorded in the deformed multilayer. Compressional structures developed during thrust propagation and fold growth, mostly locating in the fold limbs. Extensional elements striking about perpendicular to the shortening direction developed during two distinct episodes: before fold growth, when the area deformed by outer-arc extension in the peripheral bulge, and during a late to post thrusting stage. Most of the the extensional deformation occurred during the second stage, when the syn-thrusting erosional exhumation of the structures caused the development of pervasive longitudinal extensional fracturing in the crestal sector of the growing anticline, which anticipated the subsequent widespread Quaternary extensional tectonics.

Engineering research, development and technology: Thrust area report FY 91

International Nuclear Information System (INIS)

1991-01-01

The mission of the Engineering Research, Development, and Technology Program at Lawrence, Livermore National Laboratory (LLNL) is to develop the technical staff and the technology needed to support current and future LLNL programs. To accomplish this mission, the Engineering Research, Development, and Technology Program has two important goals: (1) to identify key technologies and (2) conduct high quality work to enhance our capabilities in these key technologies. To help focus our efforts, we identify technology thrust areas and select technical leaders for each area. The thrust areas are integrated engineering activities and, rather than being based on individual disciplines, they are staffed by personnel from Electronics Engineering, Mechanical Engineering, and other LLNL organizations, as appropriate. The thrust area leaders are expected to establish strong links to LLNL program leaders and to industry; to use outside and inside experts to review the quality and direction of the work; to use university contacts to supplement and complement their efforts; and to be certain that we are not duplicating the work of others. The thrust area leader is also responsible for carrying out the work that follows from the Engineering Research, Development, and Technology Program so that the results can be applied as early as possible to the needs of LLNL programs. This annual report, organized by thrust area, describes activities conducted within the Program for the fiscal year, 1991. Its intent is to provide timely summaries of objectives, theories, methods, and results

Detection of gas hydrate with downhole logs and assessment of gas hydrate concentrations (saturations) and gas volumes on the Blake Ridge with electrical resistivity log data

Science.gov (United States)

Collett, T.S.; Ladd, J.

2000-01-01

Let 164 of the Ocean Drilling Program was designed to investigate the occurrence of gas hydrate in the sedimentary section beneath the Blake Ridge on the southeastern continental margin of North America. Site 994, and 997 were drilled on the Blake Ridge to refine our understanding of the in situ characteristics of natural gas hydrate. Because gas hydrate is unstable at surface pressure and temperature conditions, a major emphasis was placed on the downhole logging program to determine the in situ physical properties of the gas hydrate-bearing sediments. Downhole logging tool strings deployed on Leg 164 included the Schlumberger quad-combination tool (NGT, LSS/SDT, DIT, CNT-G, HLDT), the Formation MicroScanner (FMS), and the Geochemical Combination Tool (GST). Electrical resistivity (DIT) and acoustic transit-time (LSS/SDT) downhole logs from Sites 994, 995, and 997 indicate the presence of gas hydrate in the depth interval between 185 and 450 mbsf on the Blake Ridge. Electrical resistivity log calculations suggest that the gas hydrate-bearing sedimentary section on the Blake Ridge may contain between 2 and 11 percent bulk volume (vol%) gas hydrate. We have determined that the log-inferred gas hydrates and underlying free-gas accumulations on the Blake Ridge may contain as much as 57 trillion m3 of gas.

Subacute effects of cervicothoracic spinal thrust/non-thrust in addition to shoulder manual therapy plus exercise intervention in individuals with subacromial impingement syndrome: a prospective, randomized controlled clinical trial pilot study.

Science.gov (United States)

Wright, Alexis A; Donaldson, Megan; Wassinger, Craig A; Emerson-Kavchak, Alicia J

2017-09-01

To determine the subacute effects of cervicothoracic spinal thrust/non-thrust in addition to shoulder non-thrust plus exercise in patients with subacromial pathology. This was a randomized, single blinded controlled trial pilot study. This trial was registered at ClinicalTrials.gov (NCT01753271) and reported according to Consolidated Standards of Reporting Trials requirements. Patients were randomly assigned to either shoulder treatment plus cervicothoracic spinal thrust/non-thrust or shoulder treatment-only group. Primary outcomes were average pain intensity (Numeric Pain Rating Scale) and physical function (Shoulder Pain and Disability Index) at 2 weeks, 4 weeks, and patient discharge. 18 patients, mean age 43.1(15.8) years satisfied the eligibility criteria and were analyzed for follow-up data. Both groups showed statistically significant improvements in both pain and function at 2 weeks, 4 weeks, and discharge. The between-group differences for changes in pain or physical function were not significant at any time point. The addition of cervicothoracic spinal thrust/non-thrust to the shoulder treatment-only group did not significantly alter improvement in pain or function in patients with subacromial pathology. Both approaches appeared to provide an equally notable benefit. Both groups improved on all outcomes and met the criteria for clinical relevance for both pain and function. 2b.

A feasibility assessment of magnetic bearings for free-piston Stirling space power converters

Science.gov (United States)

Curwen, Peter W.; Rao, Dantam K.; Wilson, Donald R.

1992-01-01

This report describes a design and analysis study performed by Mechanical Technology Incorporated (MTI) under NASA Contract NAS3-26061. The objective of the study was to assess the feasibility and efficacy of applying magnetic bearings to free-piston Stirling-cycle power conversion machinery of the type currently being evaluated for possible use in long-term space missions. The study was performed for a 50-kWe Reference Stirling Space Power Converter (RSSPC) system consisting of two 25-kWe free-piston Stirling engine modules. Two different versions of the RSSPC engine modules have been defined under NASA Contract NAS3-25463. These modules currently use hydrostatic gas bearings to support the reciprocating displacer and power piston assemblies. Results of this study show that active magnetic bearings of the attractive electromagnetic type are technically feasible for RSSPC application provided that wire insulation with 60,000-hr life capability at 300 C can be developed for the bearing coils. From a design integration standpoint, both versions of the RSSPC were found to be conceptually amenable to magnetic support of the power piston assembly. However, only one version of the RSSPC was found to be amendable to magnetic support of the displacer assembly. Unacceptable changes to the basic engine design would be required to incorporate magnetic displacer bearings into the second version. Complete magnetic suspension of the RSSPC can potentially increase overall efficiency of the Stirling cycle power converter by 0.53 to 1.4 percent (0.15 to 0.4 efficiency points). Magnetic bearings will also overcome several operational concerns associated with hydrostatic gas bearing systems. However, these advantages are accompanied by a 5 to 8 percent increase in specific mass of the RSSPC, depending on the RSSPC version employed. Additionally, magnetic bearings are much more complex, both mechanically and particularly electronically, than hydrostatic bearings. Accordingly, long

Advances in Thrust-Based Emergency Control of an Airplane

Science.gov (United States)

Creech, Gray; Burken, John J.; Burcham, Bill

2003-01-01

Engineers at NASA's Dryden Flight Research Center have received a patent on an emergency flight-control method implemented by a propulsion-controlled aircraft (PCA) system. Utilizing the preexisting auto-throttle and engine-pressure-ratio trim controls of the airplane, the PCA system provides pitch and roll control for landing an airplane safely without using aerodynamic control surfaces that have ceased to function because of a primary-flight-control-system failure. The installation of the PCA does not entail any changes in pre-existing engine hardware or software. [Aspects of the method and system at previous stages of development were reported in Thrust-Control System for Emergency Control of an Airplane (DRC-96-07), NASA Tech Briefs, Vol. 25, No. 3 (March 2001), page 68 and Emergency Landing Using Thrust Control and Shift of Weight (DRC-96-55), NASA Tech Briefs, Vol. 26, No. 5 (May 2002), page 58.]. Aircraft flight-control systems are designed with extensive redundancy to ensure low probabilities of failure. During recent years, however, several airplanes have exhibited major flight-control-system failures, leaving engine thrust as the last mode of flight control. In some of these emergency situations, engine thrusts were successfully modulated by the pilots to maintain flight paths or pitch angles, but in other situations, lateral control was also needed. In the majority of such control-system failures, crashes resulted and over 1,200 people died. The challenge lay in creating a means of sufficient degree of thrust-modulation control to safely fly and land a stricken airplane. A thrust-modulation control system designed for this purpose was flight-tested in a PCA an MD-11 airplane. The results of the flight test showed that without any operational control surfaces, a pilot can land a crippled airplane (U.S. Patent 5,330,131). The installation of the original PCA system entailed modifications not only of the flight-control computer (FCC) of the airplane but

EFFECTS OF SMALL THRUST ON THE MOTION OF AN ARTIFICIAL EARTH SATELLITE

OpenAIRE

TAKEUCHI, Sumio; 武内, 澄夫

1982-01-01

Perturbative effects of small thrust on the motion of an artificial earth satellite are investigated. The Lagrange planetary equations in Gaussian form are applied to determine the variations of the orbital elements. Also, equations of motion expressed in terms of different components of the thrust acceleration are used. It is assumed that the small thrust acceleration is a function of time and expressible as a linear combination of a polynomial and a composite set of all sines and cosines. B...

Neural network analysis of crosshole tomographic images: The seismic signature of gas hydrate bearing sediments in the Mackenzie Delta (NW Canada)

Science.gov (United States)

Bauer, K.; Pratt, R. G.; Haberland, C.; Weber, M.

2008-10-01

Crosshole seismic experiments were conducted to study the in-situ properties of gas hydrate bearing sediments (GHBS) in the Mackenzie Delta (NW Canada). Seismic tomography provided images of P velocity, anisotropy, and attenuation. Self-organizing maps (SOM) are powerful neural network techniques to classify and interpret multi-attribute data sets. The coincident tomographic images are translated to a set of data vectors in order to train a Kohonen layer. The total gradient of the model vectors is determined for the trained SOM and a watershed segmentation algorithm is used to visualize and map the lithological clusters with well-defined seismic signatures. Application to the Mallik data reveals four major litho-types: (1) GHBS, (2) sands, (3) shale/coal interlayering, and (4) silt. The signature of seismic P wave characteristics distinguished for the GHBS (high velocities, strong anisotropy and attenuation) is new and can be used for new exploration strategies to map and quantify gas hydrates.

Anomalous Thrust Production from an RF Test Device Measured on a Low-Thrust Torsion Pendulum

Science.gov (United States)

Brady, David; White, Harold G.; March, Paul; Lawrence, James T.; Davies, Frank J.

2014-01-01

This paper describes the eight-day August 2013 test campaign designed to investigate and demonstrate viability of using classical magnetoplasmadynamics to obtain a propulsive momentum transfer via the quantum vacuum virtual plasma. This paper will not address the physics of the quantum vacuum plasma thruster, but instead will describe the test integration, test operations, and the results obtained from the test campaign. Approximately 30-50 micro-Newtons of thrust were recorded from an electric propulsion test article consisting primarily of a radio frequency (RF) resonant cavity excited at approximately 935 megahertz. Testing was performed on a low-thrust torsion pendulum that is capable of detecting force at a single-digit micronewton level, within a stainless steel vacuum chamber with the door closed but at ambient atmospheric pressure. Several different test configurations were used, including two different test articles as well as a reversal of the test article orientation. In addition, the test article was replaced by an RF load to verify that the force was not being generated by effects not associated with the test article. The two test articles were designed by Cannae LLC of Doylestown, Pennsylvania. The torsion pendulum was designed, built, and operated by Eagleworks Laboratories at the NASA Johnson Space Center of Houston, Texas. Approximately six days of test integration were required, followed by two days of test operations, during which, technical issues were discovered and resolved. Integration of the two test articles and their supporting equipment was performed in an iterative fashion between the test bench and the vacuum chamber. In other words, the test article was tested on the bench, then moved to the chamber, then moved back as needed to resolve issues. Manual frequency control was required throughout the test. Thrust was observed on both test articles, even though one of the test articles was designed with the expectation that it would not

Thrust initiation and its control on tectonic wedge geometry: An insight from physical and numerical models

Science.gov (United States)

Bose, Santanu; Mandal, Nibir; Saha, Puspendu; Sarkar, Shamik; Lithgow-Bertelloni, Carolina

2014-10-01

We performed a series of sandbox experiments to investigate the initiation of thrust ramping in tectonic wedges on a mechanically continuous basal decollement. The experiments show that the decollement slope (β) is the key factor in controlling the location of thrust initiation with respect to the backstop (i.e. tectonic suture line). For β = 0, the ramping begins right at the backstop, followed by sequential thrusting in the frontal direction, leading to a typical mono-vergent wedge. In contrast, the ramp initiates away from the backstop as β > 0. Under this boundary condition an event of sequential back thrusting takes place prior to the onset of frontal thrust progression. These two-coupled processes eventually give rise to a bi-vergent geometry of the thrust wedge. Using the Drucker-Prager failure criterion in finite element (FE) models, we show the location of stress intensification to render a mechanical basis for the thrust initiation away from the backstop if β > 0. Our physical and FE model results explain why the Main Central Thrust (MCT) is located far away from the Indo-Tibetan plate contact (ITSZ) in the Himalayan fold-and-thrust belts.

Numerical Estimation Method for the NonStationary Thrust of Pulsejet Ejector Nozzle

Directory of Open Access Journals (Sweden)

A. Yu. Mikushkin

2016-01-01

Full Text Available The article considers a calculation method for the non-stationary thrust of pulsejet ejector nozzle that is based on detonation combustion of gaseous fuel.To determine initial distributions of the thermodynamic parameters inside the detonation tube was carried out a rapid analysis based on x-t-diagrams of motion of glowing combustion products. For this purpose, the section with transparent walls was connected to the outlet of the tube to register the movement of products of combustion.Based on obtained images and gas-dynamic and thermodynamic equations the velocity distribution of the combustion products, its density, pressure and temperature required for numerical analysis were calculated. The world literature presents data on distribution of parameters, however they are given only for direct initiation of detonation at the closed end and for chemically "frozen" gas composition. The article presents the interpolation methods of parameters measured at the temperatures of 2500-2800K.Estimation of the thermodynamic parameters is based on the Chapman-Jouguet theory that the speed of the combustion products directly behind the detonation wave front with respect to the wave front is equal to the speed of sound of these products at a given point. The method of minimizing enthalpy of the final thermodynamic state was used to calculate the equilibrium parameters. Thus, a software package «IVTANTHERMO», which is a database of thermodynamic properties of many individual substances in a wide temperature range, was used.An integral thrust was numerically calculated according to the ejector nozzle surface. We solved the Navier-Stokes equations using the finite-difference Roe scheme of the second order. The combustion products were considered both as an inert mixture with "frozen" composition and as a mixture in chemical equilibrium with the changing temperature. The comparison with experimental results was made.The above method can be used for rapid

Radial loads and axial thrusts on centrifugal pumps

International Nuclear Information System (INIS)

Anon.

1986-01-01

The proceedings of a seminar organised by the Power Industries Division of the IMechE are presented in this text. Complete contents: Review of parameters influencing hydraulic forces on centrifugal impellers; The effect of fluid forces at various operation conditions on the vibrations of vertical turbine pumps; A review of the pump rotor axial equilibrium problem - some case studies; Dynamic hydraulic loading on a centrifugal pump impeller; Experimental research on axial thrust loads of double suction centrifugal pumps; A comparison of pressure distribution and radial loads on centrifugal pumps; A theoretical and experimental investigation of axial thrusts within a multi-stage centrifugal pump

Beryllium satellite thrust cone design, manufacture and test

International Nuclear Information System (INIS)

Schneiter, H.; Chandler, D.

1977-01-01

Pre-formed beryllium sheet material has been used in the design, manufacturing and test of a satellite thrust cone structure. Adhesive bonding was used for attachment of aluminium flanges and conical segment lap strips. Difficulties in beryllium structure design such as incompatibilities with aluminium and handling problems are discussed. Testing to optimize beryllium-beryllium and beryllium-aluminium adhesive bonds is described. The completed thrust cone assembly has been subjected to static load testing and the results are presented. A summary of the relative merits of the use of beryllium in satellite structures is given with recommendations for future users. (author)

Soil cover of gas-bearing areas

Science.gov (United States)

Mozharova, N. V.

2010-08-01

Natural soils with disturbed functioning parameters compared to the background soils with conservative technogenic-pedogenic features were distinguished on vast areas above the artificial underground gas storages in the zones of spreading and predominant impact of hydrocarbon gases. The disturbance of the functioning parameters is related to the increase in the methane concentration, the bacterial oxidation intensity and destruction, and the complex microbiological and physicochemical synthesis of iron oxides. The technogenic-pedogenic features include neoformations of bacteriomorphic microdispersed iron oxides. The impurity components consist of elements typical for biogenic structures. New soil layers, horizons, specific anthropogenically modified soils, and soil-like structures were formed on small areas in the industrial zones of underground gas storages due to the mechanical disturbance, the deposition of drilling sludge, and the chemical contamination. Among the soils, postlithogenic formations were identified—chemotechnosols (soddy-podzolic soils and chernozems), as well as synlithogenic ones: strato-chemotechnosols and stratochemoembryozems. The soil-like bodies included postlithogenic soil-like structures (chemotechnozems) and synlithogenic ones (strato-chemotechnozems). A substantive approach was used for the soil diagnostics. The morphological and magnetic profiles and the physical, chemical, and physicochemical properties of the soils were analyzed. The micromorphological composition of the soil magnetic fraction was used as a magnetic label.

Lower extremity thrust and non-thrust joint mobilization for patellofemoral pain syndrome: a case report.

Science.gov (United States)

Simpson, Brad G; Simon, Corey B

2014-05-01

A 40-year old female presented to physical therapy with a one-year history of insidious right anteromedial and anterolateral knee pain. Additionally, the patient had a history of multiple lateral ankle sprains bilaterally, the last sprain occurring on the right ankle 1 year prior to the onset of knee pain. The patient was evaluated and given a physical therapy diagnosis of patellofemoral pain syndrome (PFPS), with associated talocrural and tibiofemoral joint hypomobility limiting ankle dorsiflexion and knee extension, respectively. Treatment included a high-velocity low amplitude thrust manipulation to the talocrural joint, which helped restore normal ankle dorsiflexion range of motion. The patient also received tibiofemoral joint non-thrust manual therapy to regain normal knee extension mobility prior to implementing further functional progression exercises to her home program (HEP). This case report highlights the importance of a detailed evaluation of knee and ankle joint mobility in patients presenting with anterior knee pain. Further, manual physical therapy to the lower extremity was found to be successful in restoring normal movement patterns and pain-free function in a patient with chronic anterior knee pain.

North Aegean core complexes, the gravity spreading of a thrust wedge

NARCIS (Netherlands)

Kydonakis, Konstantinos; Brun, Jean Pierre; Sokoutis, Dimitrios

2015-01-01

The North Aegean core complexes developed in middle Eocene soon after the end of continental block convergence and piling up of the Hellenic Thrust Wedge. They formed during back-arc extension, driven by the Hellenic slab rollback, at the back of the thrust wedge. A series of scaled laboratory

The Characteristics of Fluid Potential in Mud Diapirs Associated with Gas Hydrates in the Okinawa Trough

Directory of Open Access Journals (Sweden)

Ning Xu

2006-01-01

Full Text Available Many mud diapirs have been identified in the southern Okinawa Trough from a seismic survey using R/V KEXUE I in 2001. The movement and accumulation of free gas related to mud diapirs are discussed in detail by an analysis of fluid potential which is based upon velocity data. It can be found that free gas moves from the higher fluid potential strata to the lower ones and the gas hydrate comes into being during free gas movement meeting the proper criteria of temperature and pressure. In fact, gas hydrates have been found in the upper layers above the mud diapirs and in host rocks exhibiting other geophysical characteristics. As the result of the formation of the gas hydrate, the free gas bearing strata are enclosed by the gas hydrate bearing strata. Due to the high pressure anomalies of the free gas bearing strata the fluid potential increases noticeably. It can then be concluded that the high fluid potential anomaly on the low fluid potential background may be caused by the presence of the free gas below the gas hydrate bearing strata.

Distillation of oil-bearing minerals

Energy Technology Data Exchange (ETDEWEB)

1952-05-21

In the process of distilling oil-bearing minerals such as oil shale which disintegrates during distillation, wherein the subdivided minerals are subjected to a distillation temperature in the form of a highly turbulent dense mass fluidized by an upwardly flowing gasiform medium in a distillation zone and the heat required by the distillation is supplied by burning solid distillation residue with a combustion-supporting gas in the form of a fluidized mass of solids in a separate combustion zone at a temperature substantially higher than the distillation temperature and returning solid combustion residue substantially at the higher temperature to the distillation zone. The steps of starting up the process which consists of maintaining in the distillation and combustion zones dense turbulent fluidized beds of non-disintegrating solids, circulating the non-disintegrating solids between said beds, heating the circulating solids by an auxiliary heat supply until the bed in the distillation zone has reached at least the distillation temperature, thereafter charging fresh oil-bearing minerals to the bed in the distillation zone, continuing the circulation, withdrawing solids which have passed through the combustion zone at a rate adequate to maintain a solids balance, supplying the combustion-supporting gas to the combustion zone to cause the combustion of the residue, and discontinuing the auxilary heating when sufficient heat for the distillation is being generated in the combustion zone.

Geologic Assessment of Undiscovered Oil and Gas Resources of the North Cuba Basin, Cuba

Science.gov (United States)

Schenk, Christopher J.

2010-01-01

Petroleum generation in the North Cuba Basin is primarily the result of thrust loading of Jurassic and Cretaceous source rocks during formation of the North Cuba fold and thrust belt in the Late Cretaceous to Paleogene. The fold and thrust belt formed as Cuban arc-forearc rocks along the leading edge of the Caribbean plate translated northward during the opening of the Yucatan Basin and collided with the passive margin of southern North America in the Paleogene. Petroleum fluids generated during thrust loading migrated vertically into complex structures in the fold and thrust belt, into structures in the foreland basin, and possibly into carbonate reservoirs along the margins of the Yucatan and Bahama carbonate platforms. The U.S. Geological Survey (USGS) defined a Jurassic-Cretaceous Composite Total Petroleum System (TPS) and three assessment units (AU)-North Cuba Fold and Thrust Belt AU, North Cuba Foreland Basin AU, and the North Cuba Platform Margin Carbonate AU-within this TPS based mainly on structure and reservoir type (fig. 1). There is considerable geologic uncertainty as to the extent of petroleum migration that might have occurred within this TPS to form potential petroleum accumulations. Taking this geologic uncertainty into account, especially in the offshore area, the mean volumes of undiscovered resources in the composite TPS of the North Cuba Basin are estimated at (1) 4.6 billion barrels of oil (BBO), with means ranging from an F95 probability of 1 BBO to an F5 probability of 9 BBO; and (2) 8.6 trillion cubic feet of of gas (TCFG), of which 8.6 TCFG is associated with oil fields, and about 1.2 TCFG is in nonassociated gas fields in the North Cuba Foreland Basin AU.

MATERIALS PERFORMANCE TARGETED THRUST FY 2004 PROJECTS

International Nuclear Information System (INIS)

DOE

2005-01-01

The Yucca Mountain site was recommended by the President to be a geological repository for commercial spent nuclear fuel and high-level radioactive waste. The multi-barrier approach was adopted for assessing and predicting system behavior, including both natural barriers and engineered barriers. A major component of the long-term strategy for safe disposal of nuclear waste is first to completely isolate the radionuclides in waste packages for long times and then to greatly retard the egress and transport of radionuclides from penetrated packages. The goal of the Materials Performance Targeted Thrust program is to further enhance the understanding of the role of engineered barriers in waste isolation. In addition, the Thrust will explore technical enhancements and seek to offer improvements in materials costs and reliability

NATURAL BARRIERS TARGETED THRUST FY 2004 PROJECTS

International Nuclear Information System (INIS)

NA

2005-01-01

This booklet contains project descriptions of work performed by the Department of Energy (DOE), Office of Civilian Radioactive Waste Management (OCRWM), Office of Science and Technology and International's (OSTandI) Natural Barriers Targeted Thrust during Fiscal Year (FY) 2004. The Natural Barriers Targeted Thrust is part of OSTandI's Science and Technology Program which supports the OCRWM mission to manage and dispose of high-level radioactive waste and spent nuclear fuel in a manner that protects health, safety, and the environment; enhances national and energy security; and merits public confidence. In general, the projects described will continue beyond FY 2004 assuming that the technical work remains relevant to the proposed Yucca Mountain Repository and sufficient funding is made available to the Science and Technology Program

14 CFR Appendix I to Part 25 - Installation of an Automatic Takeoff Thrust Control System (ATTCS)

Science.gov (United States)

2010-01-01

... Appendix I to Part 25—Installation of an Automatic Takeoff Thrust Control System (ATTCS) I25.1General. (a... crew to increase thrust or power. I25.2Definitions. (a) Automatic Takeoff Thrust Control System (ATTCS... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Installation of an Automatic Takeoff Thrust...

Journal bearing

Science.gov (United States)

Menke, John R.; Boeker, Gilbert F.

1976-05-11

1. An improved journal bearing comprising in combination a non-rotatable cylindrical bearing member having a first bearing surface, a rotatable cylindrical bearing member having a confronting second bearing surface having a plurality of bearing elements, a source of lubricant adjacent said bearing elements for supplying lubricant thereto, each bearing element consisting of a pair of elongated relatively shallowly depressed surfaces lying in a cylindrical surface co-axial with the non-depressed surface and diverging from one another in the direction of rotation and obliquely arranged with respect to the axis of rotation of said rotatable member to cause a flow of lubricant longitudinally along said depressed surfaces from their distal ends toward their proximal ends as said bearing members are rotated relative to one another, each depressed surface subtending a radial angle of less than 360.degree., and means for rotating said rotatable bearing member to cause the lubricant to flow across and along said depressed surfaces, the flow of lubricant being impeded by the non-depressed portions of said second bearing surface to cause an increase in the lubricant pressure.

Low-Thrust Orbital Transfers in the Two-Body Problem

Directory of Open Access Journals (Sweden)

A. A. Sukhanov

2012-01-01

Full Text Available Low-thrust transfers between given orbits within the two-body problem are considered; the thrust is assumed power limited. A simple method for obtaining the transfer trajectories based on the linearization of the motion near reference orbits is suggested. Required calculation accuracy can be reached by means of use of a proper number of the reference orbits. The method may be used in the case of a large number of the orbits around the attracting center; no averaging is necessary in this case. The suggested method also is applicable to the cases of partly given final orbit and if there are constraints on the thrust direction. The method gives an optimal solution to the linearized problem which is not optimal for the original nonlinear problem; the difference between the optimal solutions to the original and linearized problems is estimated using a numerical example. Also examples illustrating the method capacities are given.

Thrust generation by a heaving flexible foil: Resonance, nonlinearities, and optimality

Science.gov (United States)

Paraz, Florine; Schouveiler, Lionel; Eloy, Christophe

2016-01-01

Flexibility of marine animal fins has been thought to enhance swimming performance. However, despite numerous experimental and numerical studies on flapping flexible foils, there is still no clear understanding of the effect of flexibility and flapping amplitude on thrust generation and swimming efficiency. Here, to address this question, we combine experiments on a model system and a weakly nonlinear analysis. Experiments consist in immersing a flexible rectangular plate in a uniform flow and forcing this plate into a heaving motion at its leading edge. A complementary theoretical model is developed assuming a two-dimensional inviscid problem. In this model, nonlinear effects are taken into account by considering a transverse resistive drag. Under these hypotheses, a modal decomposition of the system motion allows us to predict the plate response amplitude and the generated thrust, as a function of the forcing amplitude and frequency. We show that this model can correctly predict the experimental data on plate kinematic response and thrust generation, as well as other data found in the literature. We also discuss the question of efficiency in the context of bio-inspired propulsion. Using the proposed model, we show that the optimal propeller for a given thrust and a given swimming speed is achieved when the actuating frequency is tuned to a resonance of the system, and when the optimal forcing amplitude scales as the square root of the required thrust.

Cenozoic structural evolution, thermal history, and erosion of the Ukrainian Carpathians fold-thrust belt

Science.gov (United States)

Nakapelyukh, Mykhaylo; Bubniak, Ihor; Bubniak, Andriy; Jonckheere, Raymond; Ratschbacher, Lothar

2018-01-01

The Carpathians are part of the Alpine-Carpathian-Dinaridic orogen surrounding the Pannonian basin. Their Ukrainian part constitutes an ancient subduction-accretion complex that evolved into a foreland fold-thrust belt with a shortening history that was perpendicular to the orogenic strike. Herein, we constrain the evolution of the Ukrainian part of the Carpathian fold-thrust belt by apatite fission-track dating of sedimentary and volcanic samples and cross-section balancing and restoration. The apatite fission-track ages are uniform in the inner―southwestern part of the fold-thrust belt, implying post-shortening erosion since 12-10 Ma. The ages in the leading and trailing edges record provenance, i.e., sources in the Trans-European suture zone and the Inner Carpathians, respectively, and show that these parts of the fold-thrust were not heated to more than 100 °C. Syn-orogenic strata show sediment recycling: in the interior of the fold-thrust belt―the most thickened and most deeply eroded nappes―the apatite ages were reset, eroded, and redeposited in the syn-orogenic strata closer to the fore- and hinterland; the lag times are only a few million years. Two balanced cross sections, one constructed for this study and based on field and subsurface data, reveal an architecture characterized by nappe stacks separated by high-displacement thrusts; they record 340-390 km shortening. A kinematic forward model highlights the fold-thrust belt evolution from the pre-contractional configuration over the intermediate geometries during folding and thrusting and the post-shortening, erosional-unloading configuration at 12-10 Ma to the present-day geometry. Average shortening rates between 32-20 Ma and 20-12 Ma amounted to 13 and 21 km/Ma, respectively, implying a two-phased deformation of the Ukrainian fold-thrust belt.

Estimation of debonded area in bearing babbitt metal by C-Scan method

Energy Technology Data Exchange (ETDEWEB)

Jung, Gye-jo; Park, Sang-ki [Korea Electric Power Research Inst., Taejeon (Korea); Cha, Seok-ju [Korea South Eastern Power Corp., Seoul (Korea). GEN Sector; Park, Young-woo [Chungnam National Univ., Taejeon (Korea). Mechatronics

2006-07-01

The debonding area which had a complex boundary was imaged with a immersion technique, and the acoustic image was compared with the actual area. The amplitude information from focused transducer can discriminate between a defected boundary area and a sound interface of dissimilar metal. The shape of irregular boundary and area was processed by a histogram equalization, after that, through the clustering and labelling, it makes the defect area cleared. Each pixel has ultrasonic intensity rate and represents a position data. The estimation error in measuring debonding area was within 4% by image processing technique. The validity of this immersion method and image equalizing technique has been done for the inspection of power plant turbine's thrust bearings. (orig.)

Camshaft bearing arrangement

Energy Technology Data Exchange (ETDEWEB)

Aoi, K.; Ozawa, T.

1986-06-10

A bearing arrangement is described for the camshaft of an internal combustion engine or the like which camshaft is formed along its length in axial order with a first bearing surface, a first cam lobe, a second bearing surface, a second cam lobe, a third bearing surface, a third cam lobe and a fourth bearing surface, the improvement comprising first bearing means extending around substantially the full circumference of the first bearing surface and journaling the first bearing surface, second bearing means extending around substantially less than the circumference of the second bearing surface and journaling the second bearing surface, third bearing means extending around substantially less than the circumference of the third bearing surface and journaling the third bearing surface, and fourth bearing means extending around substantially the full circumference of the fourth bearing surface and journaling the first bearing surface.

Rarefied gas electro jet (RGEJ) micro-thruster for space propulsion

International Nuclear Information System (INIS)

Blanco, Ariel; Roy, Subrata

2017-01-01

This article numerically investigates a micro-thruster for small satellites which utilizes plasma actuators to heat and accelerate the flow in a micro-channel with rarefied gas in the slip flow regime. The inlet plenum condition is considered at 1 Torr with flow discharging to near vacuum conditions (<0.05 Torr). The Knudsen numbers at the inlet and exit planes are ∼0.01 and ∼0.1, respectively. Although several studies have been performed in micro-hallow cathode discharges at constant pressure, to our knowledge, an integrated study of the glow discharge physics and resulting fluid flow of a plasma thruster under these low pressure and low Knudsen number conditions is yet to be reported. Numerical simulations of the charge distribution due to gas ionization processes and the resulting rarefied gas flow are performed using an in-house code. The mass flow rate, thrust, specific impulse, power consumption and the thrust effectiveness of the thruster are predicted based on these results. The ionized gas is modelled using local mean energy approximation. An electrically induced body force and a thermal heating source are calculated based on the space separated charge distribution and the ion Joule heating, respectively. The rarefied gas flow with these electric force and heating source is modelled using density-based compressible flow equations with slip flow boundary conditions. The results show that a significant improvement of specific impulse can be achieved over highly optimized cold gas thrusters using the same propellant. (paper)

Auxiliary bearing design and rotor dynamics analysis of blower fan for HTR-10

International Nuclear Information System (INIS)

Gao Mingshan; Yang Guojun; Xu Yang; Zhao Lei; Yu Suyuan

2005-01-01

The electromagnetic bearing instead of ordinary mechanical bearing was chosen to support the rotor in the blower fan system with helium of 10 MW high temperature gas-cooled test reactor (HTR-10), and the auxiliary bearing was applied in the HTR-10 as the backup protector. When the electromagnetic bearing doesn't work suddenly for the power broken, the auxiliary bearing is used to support the falling rotor with high rotating speed. The rotor system will be protected by the auxiliary bearing. The design of auxiliary bearing is the ultimate safeguard for the system. This rotor is vertically mounted to hold the blower fan. The rotor's length is about 1.5 m, its weight is about 240 kg and the rotating speed is about 5400 r/min. Auxiliary bearing design and rotor dynamics analysis are very important for the design of blower fan to make success. The research status of the auxiliary bearing was summarized in the paper. A sort of auxiliary bearing scheme was proposed. MSC.Marc was selected to analyze the vibration mode and the natural frequency of the rotor. The scheme design of auxiliary bearing and analysis result of rotor dynamics offer the important theoretical base for the protector design and control system of electromagnetic bearing of the blower fan. (authors)

a Revision to the Tectonics of the Flores Back-Arc Thrust Zone, Indonesia?

Science.gov (United States)

Tikku, A. A.

2011-12-01

The Flores and Bali Basins are continental basins in the Flores back-arc thrust zone associated with Eocene subduction of the Indo-Australian plate beneath the Sunda plate followed by Miocene to present-day inversion/thrusting. The basins are east of Java and north of the islands of Bali, Lombok, Sumbawa and Flores in the East Java Sea area of Indonesia. The tectonic interpretation of these basins is based on seismic, bathymetry and gravity data and is also supported by present-day GPS measurements that demonstrate subduction is no longer active across the Flores thrust zone. Current thinking about the area is that the Flores Basin (on the east end of the thrust zone) had the most extension in the back-arc thrust and may be a proto-oceanic basin, though the option of a purely continental extensional basin can not be ruled out. The Bali Basin (on the west end of the thrust zone) is thought to be shallower and have experienced less continental thinning and extension than the Flores Basin. Depth to basement estimates from recently collected marine magnetic data indicate the depth of the Bali Basin may be comparable to the depth of the Flores Basin. Analysis of the marine magnetic data and potential implications of relative plate motions will be presented.

Control-Volume Analysis Of Thrust-Augmenting Ejectors

Science.gov (United States)

Drummond, Colin K.

1990-01-01

New method of analysis of transient flow in thrust-augmenting ejector based on control-volume formulation of governing equations. Considered as potential elements of propulsion subsystems of short-takeoff/vertical-landing airplanes.

Faulting of gas-hydrate-bearing marine sediments - contribution to permeability

Science.gov (United States)

Dillon, William P.; Holbrook, W.S.; Drury, Rebecca; Gettrust, Joseph; Hutchinson, Deborah; Booth, James; Taylor, Michael

1997-01-01

Extensive faulting is observed in sediments containing high concentrations of methane hydrate off the southeastern coast of the United States. Faults that break the sea floor show evidence of both extension and shortening; mud diapirs are also present. The zone of recent faulting apparently extends from the ocean floor down to the base of gas-hydrate stability. We infer that the faulting resulted from excess pore pressure in gas trapped beneath the gas hydrate-beating layer and/or weakening and mobilization of sediments in the region just below the gas-hydrate stability zone. In addition to the zone of surface faults, we identified two buried zones of faulting, that may have similar origins. Subsurface faulted zones appear to act as gas traps.

Calculation methods for steadily loaded, off-set pivot, tilting pad thrust bearings. (Guide to use of computer program A9235.)

Science.gov (United States)

1992-12-01

ESDU 92035 provides details of a FORTRAN program that implements the calculation method of ESDU 83004. It allows performance analysis of an existing design, or the design of a bearing dimensions, subject to any space constraint, are recommended. The predicted performance includes the lubricant film thickness under load, its temperature and flow rate, the power loss, and the bearing temperature. Recommendations are also made on surface finish. Warning messages are output in the following cases, for each of which possible remedial actions are suggested: drain or pad temperature too high, churning losses too great, film thickness too small, pad number too high, ratio or inner to outer pad radius too large, flow rate too great, lubricant or pad temperature outside usable range. A lubricant database is provided that may be extended or edited. The program applies to Newtonian lubricants in laminar flow. Worked examples illustrate the use of the program.

Formation of submarine gas hydrates

Energy Technology Data Exchange (ETDEWEB)

Soloviev, V.; Ginsburg, G.D. (Reserch Institute of Geology and Mineral Resources of the Ocean ' ' VNII Okeangeologia' ' , St. Petersburg (Russian Federation))

1994-03-01

Submarine gas hydrates have been discoverd in the course of deep-sea drilling (DSDP and ODP) and bottom sampling in many offshore regions. This paper reports on expeditions carried out in the Black, Caspian and Okhotsk Seas. Gas hydrate accumulations were discovered and investigated in all these areas. The data and an analysis of the results of the deep-sea drilling programme suggest that the infiltration of gas-bearing fluids is a necessary condition for gas hydrate accumulation. This is confirmed by geological observations at three scale levels. Firstly, hydrates in cores are usually associated with comparatively coarse-grained, permeable sediments as well as voids and fractures. Secondly, hydrate accumulations are controlled by permeable geological structures, i.e. faults, diapirs, mud volcanos as well as layered sequences. Thirdly, in the worldwide scale, hydrate accumulations are characteristic of continental slopes and rises and intra-continental seas where submarine seepages also are widespread. Both biogenic and catagenic gas may occur, and the gas sources may be located at various distances from the accumulation. Gas hydrates presumably originate from water-dissolved gas. The possibility of a transition from dissolved gas into hydrate is confirmed by experimental data. Shallow gas hydrate accumulations associated with gas-bearing fluid plumes are the most convenient features for the study of submarine hydrate formation in general. These accumulations are known from the Black, Caspian and Okhotsk Seas, the Gulf of Mexico and off northern California. (au) (24 refs.)

Parametric studies on floating pad journal bearing for high speed cryogenic turboexpanders

Science.gov (United States)

Jain, A.; Jadhav, M. M.; Karimulla, S.; Chakravarty, A.

2017-12-01

Most modern medium and large capacity helium liquefaction/refrigeration plants employ high speed cryogenic turboexpanders in their refrigeration/liquefaction cycles as active cooling devices. The operating speed of these turboexpanders is in the range of 3000-5000 Hz and hence specialized types of bearings are required. Floating pad journal bearing, which is a special type of tilting pad journal bearing, where mechanical pivots are absent and pads are fully suspended in gas, can be a good solution for stable operation of these high speed compact rotors. The pads are separated from shaft as well as from housing by fluid film between them, and both these sides of pad are interconnected by a network of feed holes. The work presented in this article aims to characterize floating pad journal bearings through parametric studies. The steady state performance characteristics of the bearing are represented by load capacity, stiffness coefficients and heat generation rate of the bearing. The geometrical parameters such as bearing clearances, preload of pads, etc. are varied and performance characteristics of the floating pad journal bearing are studied and presented. The dependence of stiffness coefficients on rotational speed of shaft is also analyzed.

Flywheel Energy Storage System Suspended by Hybrid Magnetic Bearing

Science.gov (United States)

Owusu-Ansah, Prince; Hu, Yefa; Misbawu, Adam

This work presents a prototype flywheel energy storage system (FESS) suspended by hybrid magnetic bearing (HMB) rotating at a speed of 20000rpm with a maximum storage power capacity of 30W with a maximum tip speed of 300m/s. The design presented is an improvement of most existing FESS, as the design incorporates a unique feature in that the upper and the lower rotor and stator core are tapered which enhances larger thrust and much lower radial force to be exerted on the system. Without any adverse effect being experienced by the model. The work also focuses on the description of developing a prototype FESS suspended by HMB using solid works as a basis of developing in the nearer future a more improved FESS suspended by HMB capable of injecting the ever increasing high energy demand situation in the 21st century and beyond.

Research on axial thrust of the waterjet pump based on CFD under cavitation conditions

International Nuclear Information System (INIS)

Shen, Z H; Pan, Z Y

2015-01-01

Based on RANS equations, performance of a contra-rotating axial-flow waterjet pump without hydrodynamic cavitation state had been obtained combined with shear stress transport turbulence model. Its cavitation hydrodynamic performance was calculated and analysed with mixture homogeneous flow cavitation model based on Rayleigh-Plesset equations. The results shows that the cavitation causes axial thrust of waterjet pump to drop. Furthermore, axial thrust and head cavitation characteristic curve is similar. However, the drop point of the axial thrust is postponed by 5.1% comparing with one of head, and the critical point of the axial thrust is postponed by 2.6%

Research on axial thrust of the waterjet pump based on CFD under cavitation conditions

Science.gov (United States)

Shen, Z. H.; Pan, Z. Y.

2015-01-01

Based on RANS equations, performance of a contra-rotating axial-flow waterjet pump without hydrodynamic cavitation state had been obtained combined with shear stress transport turbulence model. Its cavitation hydrodynamic performance was calculated and analysed with mixture homogeneous flow cavitation model based on Rayleigh-Plesset equations. The results shows that the cavitation causes axial thrust of waterjet pump to drop. Furthermore, axial thrust and head cavitation characteristic curve is similar. However, the drop point of the axial thrust is postponed by 5.1% comparing with one of head, and the critical point of the axial thrust is postponed by 2.6%.

Automatic control of a primary electric thrust subsystem

Science.gov (United States)

Macie, T. W.; Macmedan, M. L.

1975-01-01

A concept for automatic control of the thrust subsystem has been developed by JPL and participating NASA Centers. This paper reports on progress in implementing the concept at JPL. Control of the Thrust Subsystem (TSS) is performed by the spacecraft computer command subsystem, and telemetry data is extracted by the spacecraft flight data subsystem. The Data and Control Interface Unit, an element of the TSS, provides the interface with the individual elements of the TSS. The control philosophy and implementation guidelines are presented. Control requirements are listed, and the control mechanism, including the serial digital data intercommunication system, is outlined. The paper summarizes progress to Fall 1974.

A circumpolar monitoring framework for polar bears

Science.gov (United States)

Vongraven, Dag; Aars, Jon; Amstrup, Steven C.; Atkinson, Stephen N.; Belikov, Stanislav; Born, Erik W.; DeBruyn, T.D.; Derocher, Andrew E.; Durner, George M.; Gill, Michael J.; Lunn, Nicholas J.; Obbard, Martyn E.; Omelak, Jack; Ovsyanikov, Nikita; Peacock, Elizabeth; Richardson, E.E.; Sahanatien, Vicki; Stirling, Ian; Wiig, Øystein

2012-01-01

Polar bears (Ursus maritimus) occupy remote regions that are characterized by harsh weather and limited access. Polar bear populations can only persist where temporal and spatial availability of sea ice provides adequate access to their marine mammal prey. Observed declines in sea ice availability will continue as long as greenhouse gas concentrations rise. At the same time, human intrusion and pollution levels in the Arctic are expected to increase. A circumpolar understanding of the cumulative impacts of current and future stressors is lacking, long-term trends are known from only a few subpopulations, and there is no globally coordinated effort to monitor effects of stressors. Here, we describe a framework for an integrated circumpolar monitoring plan to detect ongoing patterns, predict future trends, and identify the most vulnerable polar bear subpopulations. We recommend strategies for monitoring subpopulation abundance and trends, reproduction, survival, ecosystem change, human-caused mortality, human–bear conflict, prey availability, health, stature, distribution, behavioral change, and the effects that monitoring itself may have on polar bears. We assign monitoring intensity for each subpopulation through adaptive assessment of the quality of existing baseline data and research accessibility. A global perspective is achieved by recommending high intensity monitoring for at least one subpopulation in each of four major polar bear ecoregions. Collection of data on harvest, where it occurs, and remote sensing of habitat, should occur with the same intensity for all subpopulations. We outline how local traditional knowledge may most effectively be combined with the best scientific methods to provide comparable and complementary lines of evidence. We also outline how previously collected intensive monitoring data may be sub-sampled to guide future sampling frequencies and develop indirect estimates or indices of subpopulation status. Adoption of this framework

Growth of the Zagros Fold-Thrust Belt and Foreland Basin, Northern Iraq, Kurdistan

Science.gov (United States)

Koshnaw, Renas; Horton, Brian; Stockli, Daniel; Barber, Douglas; Ghalib, Hafidh; Dara, Rebwar

2016-04-01

The Zagros orogenic belt in the Middle Eastern segment of the Alpine-Himalayan system is among the youngest seismically active continental collision zones on Earth. However, due to diachronous and incremental collision, the precise ages and kinematics of shortening and deposition remain poorly understood. The Kurdistan region of the Zagros fold-thrust belt and foreland basin contains well-preserved Neogene wedge-top and foredeep deposits that include clastic nonmarine fill of the Upper Fars, Lower Bakhtiari, and Upper Bakhtiari Formations. These deposits record significant information about orogenic growth, fold-thrust dynamics, and advance of the deformation front. Thermochronologic and geochronologic data from thrust sheets and stratigraphic archives combined with local earthquake data provide a unique opportunity to address the linkages between surface and subsurface geologic relationships. This research seeks to constrain the timing and geometry of exhumation and deformation by addressing two key questions: (1) Did the northwestern Zagros fold-thrust belt evolve from initial thin-skinned shortening to later thick-skinned deformation or vice-versa? (2) Did the fold-thrust belt advance steadily under critical/supercritical wedge conditions involving in-sequence thrusting or propagate intermittently under subcritical conditions with out-of-sequence deformation? From north to south, apatite (U-Th)/He ages from the Main Zagros Thrust, the Mountain Front Flexure (MFF), and additional frontal thrusts suggest rapid exhumation by ~10 Ma, ~5 Ma, and ~8 Ma respectively. Field observations and seismic sections indicate progressive tilting and development of growth strata within the Lower Bakhtiari Formation adjacent to the frontal thrusts and within the Upper Bakhtiari Formation near the MFF. In the Kurdistan region of Iraq, a regional balanced cross section constrained by new thermochronometric results, proprietary seismic reflection profiles, and earthquake hypocenters

Reliability and validity of a tool to measure the severity of tongue thrust in children: the Tongue Thrust Rating Scale.

Science.gov (United States)

Serel Arslan, S; Demir, N; Karaduman, A A

2017-02-01

This study aimed to develop a scale called Tongue Thrust Rating Scale (TTRS), which categorised tongue thrust in children in terms of its severity during swallowing, and to investigate its validity and reliability. The study describes the developmental phase of the TTRS and presented its content and criterion-based validity and interobserver and intra-observer reliability. For content validation, seven experts assessed the steps in the scale over two Delphi rounds. Two physical therapists evaluated videos of 50 children with cerebral palsy (mean age, 57·9 ± 16·8 months), using the TTRS to test criterion-based validity, interobserver and intra-observer reliability. The Karaduman Chewing Performance Scale (KCPS) and Drooling Severity and Frequency Scale (DSFS) were used for criterion-based validity. All the TTRS steps were deemed necessary. The content validity index was 0·857. A very strong positive correlation was found between two examinations by one physical therapist, which indicated intra-observer reliability (r = 0·938, P reliability (r = 0·892, P validity of the TTRS. The TTRS is a valid, reliable and clinically easy-to-use functional instrument to document the severity of tongue thrust in children. © 2016 John Wiley & Sons Ltd.

NATURAL BARRIERS TARGETED THRUST FY 2004 PROJECTS

Energy Technology Data Exchange (ETDEWEB)

NA

2005-07-27

This booklet contains project descriptions of work performed by the Department of Energy (DOE), Office of Civilian Radioactive Waste Management (OCRWM), Office of Science and Technology and International's (OST&I) Natural Barriers Targeted Thrust during Fiscal Year (FY) 2004. The Natural Barriers Targeted Thrust is part of OST&I's Science and Technology Program which supports the OCRWM mission to manage and dispose of high-level radioactive waste and spent nuclear fuel in a manner that protects health, safety, and the environment; enhances national and energy security; and merits public confidence. In general, the projects described will continue beyond FY 2004 assuming that the technical work remains relevant to the proposed Yucca Mountain Repository and sufficient funding is made available to the Science and Technology Program.

A Simple Method to Measure Nematodes' Propulsive Thrust and the Nematode Ratchet.

Science.gov (United States)

Bau, Haim; Yuan, Jinzhou; Raizen, David

2015-11-01

Since the propulsive thrust of micro organisms provides a more sensitive indicator of the animal's health and response to drugs than motility, a simple, high throughput, direct measurement of the thrust is desired. Taking advantage of the nematode C. elegans being heavier than water, we devised a simple method to determine the propulsive thrust of the animals by monitoring their velocity when swimming along an inclined plane. We find that the swimming velocity is a linear function of the sin of the inclination angle. This method allows us to determine, among other things, the animas' propulsive thrust as a function of genotype, drugs, and age. Furthermore, taking advantage of the animals' inability to swim over a stiff incline, we constructed a sawteeth ratchet-like track that restricts the animals to swim in a predetermined direction. This research was supported, in part, by NIH NIA Grant 5R03AG042690-02.

Investigation on Thrust and Moment Coefficients of a Centrifugal Turbomachine

Directory of Open Access Journals (Sweden)

Bo Hu

2018-04-01

Full Text Available In radial pumps and turbines, the centrifugal through-flow in both the front and the back chambers is quite common. It strongly impacts the core swirl ratio, pressure distribution, axial thrust and frictional torque. In order to investigate these relationships experimentally, a test rig was designed at the University of Duisburg-Essen and described in this paper. Based on both the experimental and numerical results, correlations are determined to predict the impacts of the centrifugal through-flow on the core swirl ratio, the thrust coefficient and the moment coefficient. Two correlations respectively are determined to associate the core swirl ratio with the local through-flow coefficient for both Batchelor type flow and Stewartson type flow. The correlations describing the thrust coefficient and the moment coefficient in a rotor-stator cavity with centripetal through-flow (Hu et al., 2017 are modified for the case of centrifugal through-flow. The Daily and Nece diagram distinguishing between different flow regimes in rotor-stator cavities is extended with a through-flow coordinate into 3D. The achieved results provide a comprehensive data base which is intended to support the calculation of axial thrust and moment coefficients during the design process of radial pumps and turbines in a more accurate manner.

Separability of drag and thrust in undulatory animals and machines

Science.gov (United States)

Bale, Rahul; Shirgaonkar, Anup A.; Neveln, Izaak D.; Bhalla, Amneet Pal Singh; Maciver, Malcolm A.; Patankar, Neelesh A.

2014-12-01

For nearly a century, researchers have tried to understand the swimming of aquatic animals in terms of a balance between the forward thrust from swimming movements and drag on the body. Prior approaches have failed to provide a separation of these two forces for undulatory swimmers such as lamprey and eels, where most parts of the body are simultaneously generating drag and thrust. We nonetheless show that this separation is possible, and delineate its fundamental basis in undulatory swimmers. Our approach unifies a vast diversity of undulatory aquatic animals (anguilliform, sub-carangiform, gymnotiform, bal-istiform, rajiform) and provides design principles for highly agile bioinspired underwater vehicles. This approach has practical utility within biology as well as engineering. It is a predictive tool for use in understanding the role of the mechanics of movement in the evolutionary emergence of morphological features relating to locomotion. For example, we demonstrate that the drag-thrust separation framework helps to predict the observed height of the ribbon fin of electric knifefish, a diverse group of neotropical fish which are an important model system in sensory neurobiology. We also show how drag-thrust separation leads to models that can predict the swimming velocity of an organism or a robotic vehicle.

Estimating pore-space gas hydrate saturations from well log acoustic data

Science.gov (United States)

Lee, Myung W.; Waite, William F.

2008-07-01

Relating pore-space gas hydrate saturation to sonic velocity data is important for remotely estimating gas hydrate concentration in sediment. In the present study, sonic velocities of gas hydrate-bearing sands are modeled using a three-phase Biot-type theory in which sand, gas hydrate, and pore fluid form three homogeneous, interwoven frameworks. This theory is developed using well log compressional and shear wave velocity data from the Mallik 5L-38 permafrost gas hydrate research well in Canada and applied to well log data from hydrate-bearing sands in the Alaskan permafrost, Gulf of Mexico, and northern Cascadia margin. Velocity-based gas hydrate saturation estimates are in good agreement with Nuclear Magneto Resonance and resistivity log estimates over the complete range of observed gas hydrate saturations.

Uncertainties in forecasting the response of polar bears to global climate change

Science.gov (United States)

Douglas, David C.; Atwood, Todd C.; Butterworth, Andy

2017-01-01

Several sources of uncertainty affect how precisely the future status of polar bears (Ursus maritimus) can be forecasted. Foremost are unknowns about the future levels of global greenhouse gas emissions, which could range from an unabated increase to an aggressively mitigated reduction. Uncertainties also arise because different climate models project different amounts and rates of future warming (and sea ice loss)—even for the same emission scenario. There are also uncertainties about how global warming could affect the Arctic Ocean’s food web, so even if climate models project the presence of sea ice in the future, the availability of polar bear prey is not guaranteed. Under a worst-case emission scenario in which rates of greenhouse gas emissions continue to rise unabated to century’s end, the uncertainties about polar bear status center on a potential for extinction. If the species were to persist, it would likely be restricted to a high-latitude refugium in northern Canada and Greenland—assuming a food web also existed with enough accessible prey to fuel weight gains for surviving onshore during the most extreme years of summer ice melt. On the other hand, if emissions were to be aggressively mitigated at the levels proposed in the Paris Climate Agreement, healthy polar bear populations would probably continue to occupy all but the most southern areas of their contemporary summer range. While polar bears have survived previous warming phases—which indicate some resiliency to the loss of sea ice habitat—what is certain is that the present pace of warming is unprecedented and will increasingly expose polar bears to historically novel stressors.

Engineering Research and Development and Technology thrust area report FY92

Energy Technology Data Exchange (ETDEWEB)

Langland, R.T.; Minichino, C. [eds.

1993-03-01

The mission of the Engineering Research, Development, and Technology Program at Lawrence Livermore National Laboratory (LLNL) is to develop the technical staff and the technology needed to support current and future LLNL programs. To accomplish this mission, the Engineering Research, Development, and Technology Program has two important goals: (1) to identify key technologies and (2) to conduct high-quality work to enhance our capabilities in these key technologies. To help focus our efforts, we identify technology thrust areas and select technical leaders for each area. The thrust areas are integrated engineering activities and, rather than being based on individual disciplines, they are staffed by personnel from Electronics Engineering, Mechanical Engineering, and other LLNL organizations, as appropriate. The thrust area leaders are expected to establish strong links to LLNL program leaders and to industry; to use outside and inside experts to review the quality and direction of the work; to use university contacts to supplement and complement their efforts; and to be certain that we are not duplicating the work of others. This annual report, organized by thrust area, describes activities conducted within the Program for the fiscal year 1992. Its intent is to provide timely summaries of objectives, theories, methods, and results. The nine thrust areas for this fiscal year are: Computational Electronics and Electromagnetics; Computational Mechanics; Diagnostics and Microelectronics; Emerging Technologies; Fabrication Technology; Materials Science and Engineering; Microwave and Pulsed Power; Nondestructive Evaluation; and Remote Sensing and Imaging, and Signal Engineering.

Engineering Research and Development and Technology thrust area report FY92

International Nuclear Information System (INIS)

Langland, R.T.; Minichino, C.

1993-03-01

The mission of the Engineering Research, Development, and Technology Program at Lawrence Livermore National Laboratory (LLNL) is to develop the technical staff and the technology needed to support current and future LLNL programs. To accomplish this mission, the Engineering Research, Development, and Technology Program has two important goals: (1) to identify key technologies and (2) to conduct high-quality work to enhance our capabilities in these key technologies. To help focus our efforts, we identify technology thrust areas and select technical leaders for each area. The thrust areas are integrated engineering activities and, rather than being based on individual disciplines, they are staffed by personnel from Electronics Engineering, Mechanical Engineering, and other LLNL organizations, as appropriate. The thrust area leaders are expected to establish strong links to LLNL program leaders and to industry; to use outside and inside experts to review the quality and direction of the work; to use university contacts to supplement and complement their efforts; and to be certain that we are not duplicating the work of others. This annual report, organized by thrust area, describes activities conducted within the Program for the fiscal year 1992. Its intent is to provide timely summaries of objectives, theories, methods, and results. The nine thrust areas for this fiscal year are: Computational Electronics and Electromagnetics; Computational Mechanics; Diagnostics and Microelectronics; Emerging Technologies; Fabrication Technology; Materials Science and Engineering; Microwave and Pulsed Power; Nondestructive Evaluation; and Remote Sensing and Imaging, and Signal Engineering

Aircraft gas turbines

Energy Technology Data Exchange (ETDEWEB)

Sekido, T [Ishikawajima-Harima Heavy Industries, Co. Ltd., Tokyo (Japan)

1994-03-01

Current developmental activities of aircraft gas turbines in Japan are reviewed. V2500-A5 engine with thrust of 30,000 LBF is scheduled to be used for real aircraft in 1994, and intensive developmental activities are also proceeding in larger engines over 90,000 LBF. Recently, developmental programs of engines for 75-100 seat aircraft have been actively discussed, and Japanese engine makers are having discussions towards international collaboration. Such engines will be high bypass turbofans of 12,000-22,000 LBF. Development of SST/HST engines in a speed range from subsonic to Mach 5 is under the initiative of the Agency of Industrial Science and Technology. The Technical Research and Development Institute of Japan, Defence Agency achieved the target thrust of 3.4 tons in the small turbofan engine program, and the small turboshaft engine for small helicopters is also under development. Both National Aerospace Laboratory (NAL) and Institute of Space and Aeronautical Science (ISAS) are now conducting the research programs on turbo-ramjet engines under a component test phase. 1 fig.

Low eddy loss axial hybrid magnetic bearing with gimballing control ability for momentum flywheel

International Nuclear Information System (INIS)

Tang, Jiqiang; Sun, Jinji; Fang, Jiancheng; Shuzhi Sam, Ge

2013-01-01

For a magnetically suspended momentum flywheel (MSMF), the spinning rotor can be tilted by a pair of the presented axial hybrid magnetic bearing (AHMB) with eight poles and rotates around the radial axes to generate a large torque to maneuver the spacecraft. To improve the control performance and gimballing control ability of the AHMB, characteristics such as magnetic suspension force, angular stiffness and tilting momentum are researched. These segmented stator poles cause the magnetic density in the thrust rotor plate to be uneven unavoidably and the rotational loss is large at high speed, but we optimized the stator poles configuration and caused the thrust rotor plate formed by bulk DT4C and laminated material to make the magnetic density in the thrust rotor plate change less and be smoother. Laminated material such as 1J50 film with a thickness of 0.1 mm can make the variation of the magnetic density in DT4C become very small and the eddy loss of it be negligible, but the stress produced in the “O” shape stacks by reeling has a bad effect on its power loss. Nanocrystalline can reduce eddy losses and is not affected by the reeling process. Based on the AHBM consisting of the stator with eight improved poles and the presented thrust rotor plate with DT4 and nanocrystalline, the rotational loss of 5-DOF magnetically suspended momentum flywheel with angular momentum of 15 N m s at 5000 rpm has reduced from 23.4 W to 3.2 W, which proved that this AHMB has low eddy loss for the gimballing control ability. - Highlights: ► Control methods of rotor driven by AHMBs and their characteristics are researched. ► Optimized stator and rotor of AHMB reduce its eddy losses greatly. ► Presented the factors affecting the eddy losses of AHMBs. ► The good performances of AHMB with low eddy loss are proved by experiments.

Ambient Pressure Test Rig Developed for Testing Oil-Free Bearings in Alternate Gases and Variable Pressures

Science.gov (United States)

Bauman, Steven W.

1990-01-01

The Oil-Free Turbomachinery research team at the NASA Glenn Research Center is conducting research to develop turbomachinery systems that utilize high-speed, high temperature foil (air) bearings that do not require an oil lubrication system. Such systems combine the most advanced foil bearings from industry with NASA-developed hightemperature solid-lubricant technology. New applications are being pursued, such as Oil- Free turbochargers, auxiliary power units, and turbine propulsion systems for aircraft. An Oil-Free business jet engine, for example, would be simpler, lighter, more reliable, and less costly to purchase and maintain than current engines. Another application is NASA's Prometheus mission, where gas bearings will be required for the closed-cycle turbine based power-conversion system of a nuclear power generator for deep space. To support these applications, Glenn's Oil-Free Turbomachinery research team developed the Ambient Pressure Test Rig. Using this facility, researchers can load and heat a bearing and evaluate its performance with reduced air pressure to simulate high altitude conditions. For the nuclear application, the test chamber can be purged with gases such as helium to study foil gas bearing operation in working fluids other than air.

Development of active magnetic bearings and ferrofluid seals toward oil free sodium pumps

International Nuclear Information System (INIS)

Sreedhar, B.K.; Kumar, R. Nirmal; Sharma, Prashant; Ruhela, Shivprakash; Philip, John; Sundarraj, S.I.; Chakraborty, N.; Mohana, M.; Sharma, Vijay; Padmakumar, G.; Nashine, B.K.; Rajan, K.K.

2013-01-01

Sodium centrifugal pumps employ conventional oil cooled bearings and mechanical seals to support the rotor assembly outside sodium and to seal the cover gas from the atmosphere. Although engineered safety features are incorporated in the design and detailed operational procedures formulated to ensure that no oil contamination of sodium can occur, there have been incidents of oil ingress into sodium. A design variant that eliminates the need for oil in top bearings and seals is therefore a promising option. This paper discusses the work in progress to develop a magnetic bearing and ferrofluid seal combination that can achieve this purpose

Experimental contribution to the study of gas bearings; Contribution experimentale a l'etude des paliers a gaz

Energy Technology Data Exchange (ETDEWEB)

Gobert, G

1962-07-01

Developments for gas-lubricated bearings are discussed. The study of how the fluid film behaves compared to what one can expect is discussed. Various devices are described which have allowed us to go up to peripheral velocity greater than 400 m/s, leading to rotational speed of several thousand revolutions per second. This is obtained by using an automatic setting for the distance between fixed and rotating walls. (author) [French] Le present travail debute par un apercu de l'etat actuel des connaissances sur le processus de la lubrification, notamment sur les paliers a lubrification par gaz. Apres une analyse effectuee au moyen des recentes theories de R. Comolet sur le film fluide entre disques paralleles, nous decrivons des machines dont les charges axiales et radiales specialement etudiees ont permis, au moyen d'un reglage automatique des jeux entre parois fixes et parois tournantes, d'atteindre des vitesses peripheriques superieures a 400 m/s correspondant a des vitesses de plusieurs milliers de tours par seconde. (auteur)

Morphotectonics of the central Muertos thrust belt and Muertos Trough (northeastern Caribbean)

Science.gov (United States)

Granja, Bruna J.L.; ten Brink, Uri S.; Carbó-Gorosabel, Andrés; Muñoz-Martín, A.; Gomez, Ballesteros M.

2009-01-01

Multibeam bathymetry data acquired during the 2005 Spanish R/V Hesp??rides cruise and reprocessed multichannel seismic profiles provide the basis for the analysis of the morphology and deformation in the central Muertos Trough and Muertos thrust belt. The Muertos Trough is an elongated basin developed where the Venezuelan Basin crust is thrusted under the Muertos fold-and-thrust belt. Structural variations along the Muertos Trough are suggested to be a consequence of the overburden of the asymmetrical thrust belt and by the variable nature of the Venezuelan Basin crust along the margin. The insular slope can be divided into three east-west trending slope provinces with high lateral variability which correspond to different accretion stages: 1) The lower slope is composed of an active sequence of imbricate thrust slices and closed fold axes, which form short and narrow accretionary ridges and elongated slope basins; 2) The middle slope shows a less active imbricate structure resulting in lower superficial deformation and bigger slope basins; 3) The upper slope comprises the talus region and extended terraces burying an island arc basement and an inactive imbricate structure. The talus region is characterized by a dense drainage network that transports turbidite flows from the islands and their surrounding carbonate platform areas to the slope basins and sometimes to the trough. In the survey area the accommodation of the ongoing east-west differential motion between the Hispaniola and the Puerto Rico-Virgin Islands blocks takes place by means of diffuse deformation. The asymmetrical development of the thrust belt is not related to the geological conditions in the foreland, but rather may be caused by variations in the geometry and movement of the backstop. The map-view curves of the thrust belt and the symmetry of the recesses suggest a main north-south convergence along the Muertos margin. The western end of the Investigator Fault Zone comprises a broad band of

The cislunar low-thrust trajectories via the libration point

Science.gov (United States)

Qu, Qingyu; Xu, Ming; Peng, Kun

2017-05-01

The low-thrust propulsion will be one of the most important propulsion in the future due to its large specific impulse. Different from traditional low-thrust trajectories (LTTs) yielded by some optimization algorithms, the gradient-based design methodology is investigated for LTTs in this paper with the help of invariant manifolds of LL1 point and Halo orbit near the LL1 point. Their deformations under solar gravitational perturbation are also presented to design LTTs in the restricted four-body model. The perturbed manifolds of LL1 point and its Halo orbit serve as the free-flight phase to reduce the fuel consumptions as much as possible. An open-loop control law is proposed, which is used to guide the spacecraft escaping from Earth or captured by Moon. By using a two-dimensional search strategy, the ON/OFF time of the low-thrust engine in the Earth-escaping and Moon-captured phases can be obtained. The numerical implementations show that the LTTs achieved in this paper are consistent with the one adopted by the SMART-1 mission.

Sulfur-Bearing Phases Detected by Evolved Gas Analysis of the Rocknest Aeolian Deposit, Gale Crater, Mars

Science.gov (United States)

Mcadam, Amy Catherine; Franz, Heather Bryant

2014-01-01

The Sample Analysis at Mars (SAM) instrument suite detected SO2, H2S, OCS, and CS2 from approx.450 to 800 C during evolved gas analysis (EGA) of materials from the Rocknest aeolian deposit in Gale Crater, Mars. This was the first detection of evolved sulfur species from a Martian surface sample during in situ EGA. SO2(approx. 3-22 micro-mol) is consistent with the thermal decomposition of Fe sulfates or Ca sulfites, or evolution/desorption from sulfur-bearing amorphous phases. Reactions between reduced sulfur phases such as sulfides and evolved O2 or H2O in the SAM oven are another candidate SO2 source. H2S (approx.41-109 nmol) is consistent with interactions of H2O, H2 and/or HCl with reduced sulfur phases and/or SO2 in the SAM oven. OCS (approx.1-5 nmol) and CS2(approx.0.2-1 nmol) are likely derived from reactions between carbon-bearing compounds and reduced sulfur. Sulfates and sulfites indicate some aqueous interactions, although not necessarily at the Rocknest site; Fe sulfates imply interaction with acid solutions whereas Ca sulfites can form from acidic to near-neutral solutions. Sulfides in the Rocknest materials suggest input from materials originally deposited in a reducing environment or from detrital sulfides from an igneous source. The presence of sulfides also suggests that the materials have not been extensively altered by oxidative aqueous weathering. The possibility of both reduced and oxidized sulfur compounds in the deposit indicates a nonequilibrium assemblage. Understanding the sulfur mineralogy in Rocknest materials, which exhibit chemical similarities to basaltic fines analyzed elsewhere on Mars, can provide insight in to the origin and alteration history of Martian surface materials.

Static investigation of two fluidic thrust-vectoring concepts on a two-dimensional convergent-divergent nozzle

Science.gov (United States)

Wing, David J.

1994-01-01

A static investigation was conducted in the static test facility of the Langley 16-Foot Transonic Tunnel of two thrust-vectoring concepts which utilize fluidic mechanisms for deflecting the jet of a two-dimensional convergent-divergent nozzle. One concept involved using the Coanda effect to turn a sheet of injected secondary air along a curved sidewall flap and, through entrainment, draw the primary jet in the same direction to produce yaw thrust vectoring. The other concept involved deflecting the primary jet to produce pitch thrust vectoring by injecting secondary air through a transverse slot in the divergent flap, creating an oblique shock in the divergent channel. Utilizing the Coanda effect to produce yaw thrust vectoring was largely unsuccessful. Small vector angles were produced at low primary nozzle pressure ratios, probably because the momentum of the primary jet was low. Significant pitch thrust vector angles were produced by injecting secondary flow through a slot in the divergent flap. Thrust vector angle decreased with increasing nozzle pressure ratio but moderate levels were maintained at the highest nozzle pressure ratio tested. Thrust performance generally increased at low nozzle pressure ratios and decreased near the design pressure ratio with the addition of secondary flow.

A calibration mechanism based on the principles of the Michelson interferometer micro-thrust test device

Science.gov (United States)

Yan, Biao; Wang, Hai; Yang, Chunlai; Wen, Li

2017-08-01

A micro-thrust test system based on Michelson interferometer was proposed and tested. The relationship between thrust and output voltage of the calibration component in the system was calculated and verified with numerical modeling. The fitting function of the calibration component was obtained, which will be tested during future thrust test experiments.

High Thrust-to-Power Annular Engine Technology

Science.gov (United States)

Patterson, Michael J.; Thomas, Robert E.; Crofton, Mark W.; Young, Jason A.; Foster, John E.

2015-01-01

Gridded ion engines have the highest efficiency and total impulse of any mature electric propulsion technology, and have been successfully implemented for primary propulsion in both geocentric and heliocentric environments with excellent ground/in-space correlation of performance. However, they have not been optimized to maximize thrust-to-power, an important parameter for Earth orbit transfer applications. This publication discusses technology development work intended to maximize this parameter. These activities include investigating the capabilities of a non-conventional design approach, the annular engine, which has the potential of exceeding the thrust-to-power of other EP technologies. This publication discusses the status of this work, including the fabrication and initial tests of a large-area annular engine. This work is being conducted in collaboration among NASA Glenn Research Center, The Aerospace Corporation, and the University of Michigan.

Kinematics of swimming and thrust production during powerstroking bouts of the swim frenzy in green turtle hatchlings

Directory of Open Access Journals (Sweden)

David T. Booth

2014-09-01

Full Text Available Hatchling sea turtles emerge from nests, crawl down the beach and enter the sea where they typically enter a stereotypical hyperactive swimming frenzy. During this swim the front flippers are moved up and down in a flapping motion and are the primary source of thrust production. I used high-speed video linked with simultaneous measurement of thrust production in tethered hatchlings, along with high-speed video of free swimming hatchlings swimming at different water speeds in a swim flume to investigate the links between kinematics of front flipper movement, thrust production and swimming speed. In particular I tested the hypotheses that (1 increased swimming speed is achieved through an increased stroke rate; (2 force produced per stroke is proportional to stroke amplitude, (3 that forward thrust is produced during both the down and up phases of stroking; and (4 that peak thrust is produced towards the end of the downstroke cycle. Front flipper stroke rate was independent of water speed refuting the hypothesis that swimming speed is increased by increasing stroke rate. Instead differences in swimming speed were caused by a combination of varying flipper amplitude and the proportion of time spent powerstroking. Peak thrust produced per stroke varied within and between bouts of powerstroking, and these peaks in thrust were correlated with both flipper amplitude and flipper angular momentum during the downstroke supporting the hypothesis that stroke force is a function of stroke amplitude. Two distinct thrust production patterns were identified, monophasic in which a single peak in thrust was recorded during the later stages of the downstroke, and biphasic in which a small peak in thrust was recorded at the very end of the upstroke and this followed by a large peak in thrust during the later stages of the downstroke. The biphasic cycle occurs in ∼20% of hatchlings when they first started swimming, but disappeared after one to two hours of

Amplitude Effects on Thrust Production for Undulatory Swimmers

Science.gov (United States)

Gater, Brittany; Bayandor, Javid

2017-11-01

Biological systems offer novel and efficient solutions to many engineering applications, including marine propulsion. It is of interest to determine how fish interact with the water around them, and how best to utilize the potential their methods offer. A stingray-like fin was chosen for analysis due to the maneuverability and versatility of stingrays. The stingray fin was modeled in 2D as a sinusoidal wave with an amplitude increasing from zero at the leading edge to a maximum at the trailing edge. Using this model, a parametric study was performed to examine the effects of the fin on surrounding water in CFD simulations. The results were analyzed both qualitatively, in terms of the pressure contours on the fin and vorticity in the trailing wake, and quantitatively, in terms of the resultant forces on the fin. The amplitude was found to have no effect on the average thrust during steady swimming, when the wave speed on the fin was approximately equal to the swimming speed. However, amplitude was shown to have a significant effect on thrust production when the fin was accelerating. This finding suggests that for undulatory swimmers, amplitude is less useful for controlling swimming speed, but can be used to great effect for augmenting thrust during acceleration.

Development of solid-gas equilibrium propulsion system for small spacecraft

Science.gov (United States)

Chujo, Toshihiro; Mori, Osamu; Kubo, Yuki

2017-11-01

A phase equilibrium propulsion system is a kind of cold-gas jet in which the phase equilibrium state of the fuel is maintained in a tank and its vapor is ejected when a valve is opened. One such example is a gas-liquid equilibrium propulsion system that uses liquefied gas as fuel. This system was mounted on the IKAROS solar sail and has been demonstrated in orbit. The system has a higher storage efficiency and a lighter configuration than a high-pressure cold-gas jet because the vapor pressure is lower, and is suitable for small spacecraft. However, the system requires a gas-liquid separation device in order to avoid leakage of the liquid, which makes the system complex. As another example of a phase equilibrium propulsion system, we introduce a solid-gas equilibrium propulsion system, which uses a sublimable substance as fuel and ejects its vapor. This system has an even lower vapor pressure and does not require such a separation device, instead requiring only a filter to keep the solid inside the tank. Moreover, the system is much simpler and lighter, making it more suitable for small spacecraft, especially CubeSat-class spacecraft, and the low thrust of the system allows spacecraft motion to be controlled precisely. In addition, the thrust level can be controlled by controlling the temperature of the fuel, which changes the vapor pressure. The present paper introduces the concept of the proposed system, and describes ejection experiments and its evaluation. The basic function of the proposed system is demonstrated in order to verify its usefulness.

Robotic Pectoral Fin Thrust Vectoring Using Weighted Gait Combinations

Directory of Open Access Journals (Sweden)

John S. Palmisano

2012-01-01

Full Text Available A method was devised to vector propulsion of a robotic pectoral fin by means of actively controlling fin surface curvature. Separate flapping fin gaits were designed to maximize thrust for each of three different thrust vectors: forward, reverse, and lift. By using weighted combinations of these three pre-determined main gaits, new intermediate hybrid gaits for any desired propulsion vector can be created with smooth transitioning between these gaits. This weighted gait combination (WGC method is applicable to other difficult-to-model actuators. Both 3D unsteady computational fluid dynamics (CFD and experimental results are presented.

Analysis of the Impacts of Bearing on Vibration Characteristics of Rotor

Directory of Open Access Journals (Sweden)

Peiji Yang

2017-01-01

Full Text Available Aiming at a Top Gas Recovery Turbine Unit (TRT with double support rotor and the extending disk end, theoretical and experimental analysis about influence of cylindrical bearing and four-lobe bearing on vibration of TRT rotor system are conducted in this paper. The results indicate that vibration of the rotor supported by cylindrical bearing is more stable than that supported by four-lobe bearing at the driving end (DE and the nondriving end (NDE. The amplitude of rotor is supported by both of these types of bearing increases as the speed increases at the NDE, while the amplitude of the DE remains unchanged. Comparing with the result of theoretical analysis, the practical test results are more consistent with the theoretical response analysis conducted by applying unbalanced mass at the extending disk end. This paper presents an analysis method of the critical characteristics of a double support rotor system with the extending disk end and provides reference value for dealing with vibration fault of double support rotor system with the extending disk end.

Grizzly bear

Science.gov (United States)

Schwartz, C.C.; Miller, S.D.; Haroldson, M.A.; Feldhamer, G.; Thompson, B.; Chapman, J.

2003-01-01

The grizzly bear inspires fear, awe, and respect in humans to a degree unmatched by any other North American wild mammal. Like other bear species, it can inflict serious injury and death on humans and sometimes does. Unlike the polar bear (Ursus maritimus) of the sparsely inhabited northern arctic, however, grizzly bears still live in areas visited by crowds of people, where presence of the grizzly remains physically real and emotionally dominant. A hike in the wilderness that includes grizzly bears is different from a stroll in a forest from which grizzly bears have been purged; nighttime conversations around the campfire and dreams in the tent reflect the presence of the great bear. Contributing to the aura of the grizzly bear is the mixture of myth and reality about its ferocity. unpredictable disposition, large size, strength, huge canines, long claws, keen senses, swiftness, and playfulness. They share characteristics with humans such as generalist life history strategies. extended periods of maternal care, and omnivorous diets. These factors capture the human imagination in ways distinct from other North American mammals. Precontact Native American legends reflected the same fascination with the grizzly bear as modern stories and legends (Rockwell 1991).

Orbital and angular motion construction for low thrust interplanetary flight

Science.gov (United States)

Yelnikov, R. V.; Mashtakov, Y. V.; Ovchinnikov, M. Yu.; Tkachev, S. S.

2016-11-01

Low thrust interplanetary flight is considered. Firstly, the fuel-optimal control is found. Then the angular motion is synthesized. This motion provides the thruster tracking of the required by optimal control direction. And, finally, reaction wheel control law for tracking this angular motion is proposed and implemented. The numerical example is given and total operation time for thrusters is found. Disturbances from solar pressure, thrust eccentricity, inaccuracy of reaction wheels installation and errors of inertia tensor are taken into account.

Thermohydrodynamic analysis of airfoil bearing based on bump foil structure

Directory of Open Access Journals (Sweden)

S.Y. Maraiy

2016-09-01

Full Text Available The load carrying capacity of the gas foil bearing depends on the material properties and the configuration of the underlying bump strip’s structure. This paper presents three different cases for selecting the dimensions of the foil bearing to guarantee the highest possible load carrying capacity. It focuses on three main parameters that affect the compliance number; these parameters are the length of bump in θ direction, the pitch of bump foil, and the thickness of bump foil. It also studies the effect of changing these parameters on load carrying capacity according to both isothermal and thermohydrodynamic approaches.

Malaysian industry enters the gas era

International Nuclear Information System (INIS)

Buckman, David.

1992-01-01

Malaysia's petroleum industry is looking forward to an expansionary period until the end of the century, with the role of gas being greatly enhanced. The state oil firm Petronas sees increasing oil and gas reserves, making fuller use of abundant gas reserves, an exploration thrust into deepwater areas and the intensification of environmental protection as some of the points of emphasis in its current programme. The state firm president Tan Sri Datuk Azizan Zainul Abidin says that in the past few years a national economic growth rate of 8 percent has resulted in rising energy demand. Economic growth is projected to continue, so that an increase in power demand can be expected for the next few years. 'Fortunately, we are experiencing the same bullish trend in oil exploration and development,' he says. (author)

Low-Thrust Bipropellant Engine Technology.

Science.gov (United States)

1980-08-01

Non-Destructive Testing OD Outside Diameter xv tr. GLOSSARY (cont.J ODE One Dimensional Equilibrium ODK One Dimensional Kinetics Pc Thrust Chamber...performance (280 sec steady- state, 220 sec pulsing) have not yet been collectively achieved, but should be obtainable with further development activities...even at nozzle area ratios up to 400:1. The influence of nozzle kinetics (i.e., equilibrium versus frozen flow and ODK ) are noted to be a much more

Experimental measurement of dolphin thrust generated during a tail stand using DPIV

Science.gov (United States)

Wei, Timothy; Fish, Frank; Williams, Terrie; Wu, Vicki; Sherman, Erica; Misfeldt, Mitchel; Ringenberg, Hunter; Rogers, Dylan

2016-11-01

The thrust generated by dolphins doing tail stands was measured using DPIV. The technique entailed measuring vortex strength associated with the tail motion and correlating it to above water video sequences showing the amount of the dolphin's body that was being lifted out of the water. The underlying drivers for this research included: i) understanding the physiology, hydrodynamics and efficiency of dolphin locomotion, ii) developing non-invasive measurement techniques for studying marine swimming and iii) quantifying the actual propulsive capabilities of these animals. Two different bottlenose dolphins at the Long Marine Lab at UC-Santa Cruz were used as test subjects. Application of the Kutta-Joukowski Theorem on measured vortex circulations yielded thrust values that were well correlated with estimates of dolphin body weight being supported above water. This demonstrates that the tail motion can be interpreted as a flapping hydrofoil that can generate a sustained thrust roughly equal to the dolphin's weight. Videos of DPIV measurements overlaid with the dolphins will be presented along with thrust/weight data.

Hydrodynamic thrust generation and power consumption investigations for piezoelectric fins with different aspect ratios

Science.gov (United States)

Shahab, S.; Tan, D.; Erturk, A.

2015-12-01

Bio-inspired hydrodynamic thrust generation using piezoelectric transduction has recently been explored using Macro-Fiber Composite (MFC) actuators. The MFC technology strikes a balance between the actuation force and structural deformation levels for effective swimming performance, and additionally offers geometric scalability, silent operation, and ease of fabrication. Recently we have shown that mean thrust levels comparable to biological fish of similar size can be achieved using MFC fins. The present work investigates the effect of length-to-width (L/b) aspect ratio on the hydrodynamic thrust generation performance of MFC cantilever fins by accounting for the power consumption level. It is known that the hydrodynamic inertia and drag coefficients are controlled by the aspect ratio especially for L/bdrag coefficients from the vibration response to harmonic actuation for the first bending mode. Experiments are then conducted for various actuation voltage levels to quantify the mean thrust resultant and power consumption levels for different aspect ratios. Variation of the thrust coefficient of the MFC bimorph fins with changing aspect ratio is also semi-empirically modeled and presented.

Gas geochemistry studies at the gas hydrate occurrence in the permafrost environment of Mallik (NWT, Canada)

Science.gov (United States)

Wiersberg, T.; Erzinger, J.; Zimmer, M.; Schicks, J.; Dahms, E.; Mallik Working Group

2003-04-01

We present real-time mud gas monitoring data as well as results of noble gas and isotope investigations from the Mallik 2002 Production Research Well Program, an international research project on Gas Hydrates in the Northwest Territories of Canada. The program participants include 8 partners; The Geological Survey of Canada (GSC), The Japan National Oil Corporation (JNOC), GeoForschungsZentrum Potsdam (GFZ), United States Geological Survey (USGS), United States Department of the Energy (USDOE), India Ministry of Petroleum and Natural Gas (MOPNG)/Gas Authority of India (GAIL) and the Chevron-BP-Burlington joint venture group. Mud gas monitoring (extraction of gas dissolved in the drill mud followed by real-time analysis) revealed more or less complete gas depth profiles of Mallik 4L-38 and Mallik 5L-38 wells for N_2, O_2, Ar, He, CO_2, H_2, CH_4, C_2H_6, C_3H_8, C_4H10, and 222Rn; both wells are approx. 1150 m deep. Based on the molecular and and isotopic composition, hydrocarbons occurring at shallow depth (down to ˜400 m) are mostly of microbial origin. Below 400 m, the gas wetness parameter (CH_4/(C_2H_6 + C_3H_8)) and isotopes indicate mixing with thermogenic gas. Gas accumulation at the base of permafrost (˜650 m) as well as δ13C and helium isotopic data implies that the permafrost inhibits gas flux from below. Gas hydrate occurrence at Mallik is known in a depth between ˜890 m and 1100 m. The upper section of the hydrate bearing zone (890 m--920 m) consists predominantly of methane bearing gas hydrates. Between 920 m and 1050 m, concentration of C_2H_6, C_3H_8, and C_4H10 increases due to the occurrence of organic rich sediment layers. Below that interval, the gas composition is similar to the upper section of the hydrate zone. At the base of the hydrate bearing zone (˜1100 m), elevated helium and methane concentrations and their isotopic composition leads to the assumption that gas hydrates act as a barrier for gas migration from below. In mud gas

Effects of irregular basement structure on the geometry and emplacement of frontal thrusts and duplexes in the Quebec Appalachians: Interpretations from well and seismic reflection data

Science.gov (United States)

Konstantinovskaya, E.; Malo, M.; Badina, F.

2014-12-01

Irregular basement geometry may affect thrust propagation in foreland fold-thrust belts creating a perturbation in structural continuity of hydrocarbon fields. Here we investigate how the irregular pattern of normal faults, along with the presence of uplifts and transverse faults in the Grenvillian basement has influenced the geometry and emplacement of frontal thrusts and duplexes in the parautochthonous domain of the southern Quebec Appalachians during the middle-late Ordovician Taconian orogeny. Integration of data from surface geology, wells, and 2D and 3D seismic reflection surveys into a regional-scale structural model is used to reconstruct the 3D geometry and emplacement history of one- and two-horse duplexes in the Joly-Saint-Flavien gas storage area. The normal hinterland to foreland sequence of thrusting in this area is complicated by the differential emplacement of tectonic slices along strike of the orogenic front, starting in the SW and developing subsequently to the NE within each structural level. The shortening related to duplex emplacement decreases laterally over the distance of 20 km from - 49% in the SW (Joly area) to - 31% in the NE (Saint-Flavien area). Duplex emplacement resulted from the differential forward propagation, deflexion and vertical-axis rotation of the roof thrust (Logan's Line), which, in turn, has been induced by the presence of frontal uplift and transverse faults in the basement. The structural-lithological analysis of tectonic slices and restoration of their initial location allows us to consider the lower slice of the Joly duplex as a structural trap comparable to the fractured reservoir in lower Ordovician dolomites of the Saint-Flavien duplex.

77 FR 70423 - Black Bear Hydro Partners, LLC and Black Bear Development Holdings, LLC and Black Bear SO, LLC...

Science.gov (United States)

2012-11-26

... Bear Hydro Partners, LLC and Black Bear Development Holdings, LLC and Black Bear SO, LLC; Notice of..., 2012, Black Bear Hydro Partners, LLC, sole licensee (transferor) and Black Bear Development Holdings, LLC and Black Bear SO, LLC (transferees) filed an application for the partial the transfer of licenses...

Camera Layout Design for the Upper Stage Thrust Cone

Science.gov (United States)

Wooten, Tevin; Fowler, Bart

2010-01-01

Engineers in the Integrated Design and Analysis Division (EV30) use a variety of different tools to aid in the design and analysis of the Ares I vehicle. One primary tool in use is Pro-Engineer. Pro-Engineer is a computer-aided design (CAD) software that allows designers to create computer generated structural models of vehicle structures. For the Upper State thrust cone, Pro-Engineer was used to assist in the design of a layout for two camera housings. These cameras observe the separation between the first and second stage of the Ares I vehicle. For the Ares I-X, one standard speed camera was used. The Ares I design calls for two separate housings, three cameras, and a lighting system. With previous design concepts and verification strategies in mind, a new layout for the two camera design concept was developed with members of the EV32 team. With the new design, Pro-Engineer was used to draw the layout to observe how the two camera housings fit with the thrust cone assembly. Future analysis of the camera housing design will verify the stability and clearance of the camera with other hardware present on the thrust cone.

Antiproton Powered Gas Core Fission Rocket

International Nuclear Information System (INIS)

Kammash, Terry

2005-01-01

Extensive research in recent years has demonstrated that 'at rest' annihilation of antiprotons in the uranium isotope U238 leads to fission at nearly 100% efficiency. The resulting highly-ionizing, energetic fission fragments can heat a suitable medium to very high temperatures, making such a process particularly suitable for space propulsion applications. Such an ionized medium, which would serve as a propellant, can be confined by a magnetic field during the heating process, and subsequently ejected through a magnetic nozzle to generate thrust. The gasdynamic mirror (GDM) magnetic configuration is especially suited for this application since the underlying confinement principle is that the plasma be of such density and temperature as to make the ion-ion collision mean free path shorter than the plasma length. Under these conditions the plasma behaves like a fluid, and its escape from the system is analogous to the flow of a gas into vacuum from a vessel with a hole. For the system we propose we envisage radially injecting atomic or U238 plasma beam at a pre-determined position and axially pulsing an antiproton beam which upon interaction with the uranium target gives rise to near isotropic ejection of fission fragments with a total mass of 212 amu and total energy of about 160 MeV. These particles, along with the annihilation products (i.e. pions and muons) will heat the background U238 gas - inserted into the chamber just prior to the release of the antiproton - to one keV temperature. Preliminary analysis reveals that such a propulsion system can produce a specific impulse of about 3000 seconds at a thrust of about 50 kN. When applied to a round trip Mars mission, we find that such a journey can be accomplished in about 142 days with 2 days of thrusting and requiring only one gram of antiprotons to achieve it

Experimental demonstration of ion extraction from magnetic thrust chamber for laser fusion rocket

Science.gov (United States)

Saito, Naoya; Yamamoto, Naoji; Morita, Taichi; Edamoto, Masafumi; Nakashima, Hideki; Fujioka, Shinsuke; Yogo, Akifumi; Nishimura, Hiroaki; Sunahara, Atsushi; Mori, Yoshitaka; Johzaki, Tomoyuki

2018-05-01

A magnetic thrust chamber is an important system of a laser fusion rocket, in which the plasma kinetic energy is converted into vehicle thrust by a magnetic field. To investigate the plasma extraction from the system, the ions in a plasma are diagnosed outside the system by charge collectors. The results clearly show that the ion extraction does not strongly depend on the magnetic field strength when the energy ratio of magnetic field to plasma is greater than 4.3, and the magnetic field pushes back the plasma to generate a thrust, as previously suggested by numerical simulation and experiments.

Phylogeography of mitochondrial DNA variation in brown bears and polar bears.

Science.gov (United States)

Shields, G F; Adams, D; Garner, G; Labelle, M; Pietsch, J; Ramsay, M; Schwartz, C; Titus, K; Williamson, S

2000-05-01

We analyzed 286 nucleotides of the middle portion of the mitochondrial cytochrome b gene of 61 brown bears from three locations in Alaska and 55 polar bears from Arctic Canada and Arctic Siberia to test our earlier observations of paraphyly between polar bears and brown bears as well as to test the extreme uniqueness of mitochondrial DNA types of brown bears on Admiralty, Baranof, and Chichagof (ABC) islands of southeastern Alaska. We also investigated the phylogeography of brown bears of Alaska's Kenai Peninsula in relation to other Alaskan brown bears because the former are being threatened by increased human development. We predicted that: (1) mtDNA paraphyly between brown bears and polar bears would be upheld, (2) the mtDNA uniqueness of brown bears of the ABC islands would be upheld, and (3) brown bears of the Kenai Peninsula would belong to either clade II or clade III of brown bears of our earlier studies of mtDNA. All of our predictions were upheld through the analysis of these additional samples. Copyright 2000 Academic Press.

Phylogeography of mitochondrial DNA variation in brown bears and polar bears

Science.gov (United States)

Shields, Gerald F.; Adams, Deborah; Garner, Gerald W.; Labelle, Martine; Pietsch, Jacy; Ramsay, Malcolm; Schwartz, Charles; Titus, Kimberly; Williamson, Scott

2000-01-01

We analyzed 286 nucleotides of the middle portion of the mitochondrial cytochrome b gene of 61 brown bears from three locations in Alaska and 55 polar bears from Arctic Canada and Arctic Siberia to test our earlier observations of paraphyly between polar bears and brown bears as well as to test the extreme uniqueness of mitochondrial DNA types of brown bears on Admiralty, Baranof, and Chichagof (ABC) islands of southeastern Alaska. We also investigated the phylogeography of brown bears of Alaska's Kenai Peninsula in relation to other Alaskan brown bears because the former are being threatened by increased human development. We predicted that: (1) mtDNA paraphyly between brown bears and polar bears would be upheld, (2) the mtDNA uniqueness of brown bears of the ABC islands would be upheld, and (3) brown bears of the Kenai Peninsula would belong to either clade II or clade III of brown bears of our earlier studies of mtDNA. All of our predictions were upheld through the analysis of these additional samples.

Thrust Augmentation by Airframe-Integrated Linear-Spike Nozzle Concept for High-Speed Aircraft

Directory of Open Access Journals (Sweden)

Hidemi Takahashi

2018-02-01

Full Text Available The airframe-integrated linear-spike nozzle concept applied to an external nozzle for high-speed aircraft was evaluated with regard to the thrust augmentation capability and the trim balance. The main focus was on the vehicle aftbody. The baseline airframe geometry was first premised to be a hypersonic waverider design. The baseline aftbody case had an external nozzle comprised of a simple divergent nozzle and was hypothetically replaced with linear-spike external nozzle configurations. Performance evaluation was mainly conducted by considering the nozzle thrust generated by the pressure distribution on the external nozzle surface at the aftbody portion calculated by computer simulation at a given cruise condition with zero angle of attack. The thrust performance showed that the proposed linear-spike external nozzle concept was beneficial in thrust enhancement compared to the baseline geometry because the design of the proposed concept had a compression wall for the exhaust flow, which resulted in increasing the wall pressure. The configuration with the boattail and the angled inner nozzle exhibited further improvement in thrust performance. The trim balance evaluation showed that the aerodynamic center location appeared as acceptable. Thus, benefits were obtained by employing the airframe-integrated linear-spike external nozzle concept.

Engineering Research, Development and Technology, FY95: Thrust area report

Energy Technology Data Exchange (ETDEWEB)

NONE

1996-02-01

The mission of the Engineering Research, Development, and Technology Program at Lawrence Livermore National Laboratory (LLNL) is to develop the knowledge base, process technologies, specialized equipment, tools and facilities to support current and future LLNL programs. Engineering`s efforts are guided by a strategy that results in dual benefit: first, in support of Department of Energy missions, such as national security through nuclear deterrence; and second, in enhancing the nation`s economic competitiveness through their collaboration with US industry in pursuit of the most cost-effective engineering solutions to LLNL programs. To accomplish this mission, the Engineering Research, Development, and Technology Program has two important goals: (1) identify key technologies relevant to LLNL programs where they can establish unique competencies, and (2) conduct high-quality research and development to enhance their capabilities and establish themselves as the world leaders in these technologies. To focus Engineering`s efforts, technology thrust areas are identified and technical leaders are selected for each area. The thrust areas are comprised of integrated engineering activities, staffed by personnel from the nine electronics and mechanical engineering divisions, and from other LLNL organizations. This annual report, organized by thrust area, describes Engineering`s activities for fiscal year 1995. The report provides timely summaries of objectives methods, and key results from eight thrust areas: computational electronics and electromagnetics; computational mechanics; microtechnology; manufacturing technology; materials science and engineering; power conversion technologies; nondestructive evaluation; and information engineering.

THCM Coupled Model for Hydrate-Bearing Sediments: Data Analysis and Design of New Field Experiments (Marine and Permafrost Settings)

Energy Technology Data Exchange (ETDEWEB)

Sanchez, Marcelo J. [Texas A & M Univ., College Station, TX (United States); Santamarina, J. Carlos [King Abdullah Univ. of Science and Technology (Saudi Arabia)

2017-02-14

Gas hydrates are solid compounds made of water molecules clustered around low molecular weight gas molecules such as methane, hydrogen, and carbon dioxide. Methane hydrates form under pressure (P) and temperature (T) conditions that are common in sub-permafrost layers and in deep marine sediments. Stability conditions constrain the occurrence of gas hydrates to submarine sediments and permafrost regions. The amount of technically recoverable methane trapped in gas hydrate may exceed 104tcf. Gas hydrates are a potential energy resource, can contribute to climate change, and can cause large-scale seafloor instabilities. In addition, hydrate formation can be used for CO2 sequestration (also through CO2-CH4 replacement), and efficient geological storage seals. The experimental study of hydrate bearing sediments has been hindered by the very low solubility of methane in water (lab testing), and inherent sampling difficulties associated with depressurization and thermal changes during core extraction. This situation has prompted more decisive developments in numerical modeling in order to advance the current understanding of hydrate bearing sediments, and to investigate/optimize production strategies and implications. The goals of this research has been to addresses the complex thermo-hydro-chemo-mechanical THCM coupled phenomena in hydrate-bearing sediments, using a truly coupled numerical model that incorporates sound and proven constitutive relations, satisfies fundamental conservation principles. Analytical solutions aimed at verifying the proposed code have been proposed as well. These tools will allow to better analyze available data and to further enhance the current understanding of hydrate bearing sediments in view of future field experiments and the development of production technology.

F-15B ACTIVE with thrust vectoring nozzles on test stand

Science.gov (United States)

1995-01-01

This November 13, 1995, photograph of the F-15 Advanced Controls Technology for Integrated Vehicles (ACTIVE) at NASA's Dryden Flight Research Center, Edwards, California, shows the thrust stand being used for ground testing of a new thrust-vectoring concept involving two new Pratt & Whitney nozzles that can turn up to 20 degrees in any direction. These nozzles give the aircraft thrust control in the pitch (up and down) and yaw (left and right) directions. This will reduce drag and increase fuel economy or range as compared with conventional aerodynamic controls, which increase the retarding forces (drag) acting upon the aircraft. These tests could lead to significant performance increases for military and commercial aircraft. The research program is the product of a collaborative effort by NASA, the Air Force's Wright Laboratory, Pratt & Whitney, and McDonnell Douglas Aerospace.

A Novel Noncontact Ultrasonic Levitating Bearing Excited by Piezoelectric Ceramics

Directory of Open Access Journals (Sweden)

He Li

2016-10-01

Full Text Available A novel ultrasonic levitating bearing excited by three piezoelectric transducers is presented in this work. The transducers are circumferentially equispaced in a housing, with their center lines going through the rotation center of a spindle. This noncontact bearing has the ability to self-align and carry radical and axial loads simultaneously. A finite element model of the bearing is built in ANSYS, and modal analysis and harmonious response analysis are conducted to investigate its characteristics and driving parameters. Based on nonlinear acoustic theory and a thermodynamic theory of ideal gas, the radical and lateral load-carrying models are built to predict the bearing’s carrying capacity. In order to validate the bearing’s levitation force, a test system is established and levitating experiments are conducted. The experimental data match well with the theoretical results. The experiments reveal that the maximum radical and axial levitating loads of the proposed bearing are about 15 N and 6 N, respectively, when the piezoelectric transducers operate at a working frequency of 16.11 kHz and a voltage of 150 Vp-p.

Hydrate-Bearing Clayey Sediments: Morphology, Physical Properties, Production and Engineering/Geological Implications

Energy Technology Data Exchange (ETDEWEB)

Dai, Sheng [Georgia Tech Research Corporation, Atlanta, GA (United States); Santamarina, J. Carlos [King Abdulaziz Univ., Jeddah (Saudi Arabia)

2017-12-30

Fine-grained sediments host more than 90 percent of global gas hydrate accumulation. However, hydrate formation in clay-dominated sediments is less understood and characterized than other types of hydrate occurrence. There is an inadequate understanding of hydrate formation mechanisms, segregation structures, hydrate lens topology, system connectivity, and physical macro-scale properties of clay-dominated hydrate-bearing sediments. This situation hinders further analyses of the global carbon budget as well as engineering challenges/solutions related to hydrate instability and production. This project studies hydrate-bearing clay-dominated sediments with emphasis on the enhanced fundamental understanding of hydrate formation and resulting morphology, the development laboratory techniques to emulate natural hydrate formations, the assessment of analytical tools to predict physical properties, the evaluation of engineering and geological implications, and the advanced understanding of gas production potential from finegrained sediments.

Numerical analysis of magnetically suspended rotor in HTR-10 helium circulator being dropped into auxiliary bearings

International Nuclear Information System (INIS)

Zhao Jingxiong; Yang Guojun; Li Yue; Yu Suyuan

2012-01-01

Active magnetic bearings (AMB) have been selected to support the rotor of primary helium circulator in commercial 10 Mega-Walt High Temperature Gas-cooled Reactor (HTR-10). In an AMB system, the auxiliary bearings are necessary to protect the AMB components in case of losing power. This paper performs the impact simulation of Magnetically Suspended Rotor in HTR-10 Helium Circulator being dropped into the auxiliary bearings using the finite element program ABAQUS. The dynamic response and the strain field of auxiliary bearings are analyzed. The results achieved by the numerical analysis are in agreement with the experiment results. Therefore, the feasibility of the design of auxiliary bearing and the possibility of using the AMB system in the HTR are proved. (authors)

Introgressive hybridization: brown bears as vectors for polar bear alleles.

Science.gov (United States)

Hailer, Frank

2015-03-01

The dynamics and consequences of introgression can inform about numerous evolutionary processes. Biologists have therefore long been interested in hybridization. One challenge, however, lies in the identification of nonadmixed genotypes that can serve as a baseline for accurate quantification of admixture. In this issue of Molecular Ecology, Cahill et al. (2015) analyse a genomic data set of 28 polar bears, eight brown bears and one American black bear. Polar bear alleles are found to be introgressed into brown bears not only near a previously identified admixture zone on the Alaskan Admiralty, Baranof and Chichagof (ABC) Islands, but also far into the North American mainland. Elegantly contrasting admixture levels at autosomal and X chromosomal markers, Cahill and colleagues infer that male-biased dispersal has spread these introgressed alleles away from the Late Pleistocene contact zone. Compared to a previous study on the ABC Island population in which an Alaskan brown bear served as a putatively admixture-free reference, Cahill et al. (2015) utilize a newly sequenced Swedish brown bear as admixture baseline. This approach reveals that brown bears have been impacted by introgression from polar bears to a larger extent (up to 8.8% of their genome), than previously known, including the bear that had previously served as admixture baseline. No evidence for introgression of brown bear into polar bear is found, which the authors argue could be a consequence of selection. Besides adding new exciting pieces to the puzzle of polar/brown bear evolutionary history, the study by Cahill and colleagues highlights that wildlife genomics is moving from analysing single genomes towards a landscape genomics approach. © 2015 John Wiley & Sons Ltd.

Miniature Gas-Turbine Power Generator

Science.gov (United States)

Wiberg, Dean; Vargo, Stephen; White, Victor; Shcheglov, Kirill

2003-01-01

A proposed microelectromechanical system (MEMS) containing a closed- Brayton-cycle turbine would serve as a prototype of electric-power generators for special applications in which high energy densities are required and in which, heretofore, batteries have been used. The system would have a volume of about 6 cm3 and would operate with a thermal efficiency >30 percent, generating up to 50 W of electrical power. The energy density of the proposed system would be about 10 times that of the best battery-based systems now available, and, as such, would be comparable to that of a fuel cell. The working gas for the turbine would be Xe containing small quantities of CO2, O2, and H2O as gaseous lubricants. The gas would be contained in an enclosed circulation system, within which the pressure would typically range between 5 and 50 atm (between 0.5 and 5 MPa). The heat for the Brayton cycle could be supplied by any of a number of sources, including a solar concentrator or a combustor burning a hydrocarbon or other fuel. The system would include novel heat-transfer and heat-management components. The turbine would be connected to an electric power generator/starter motor. The system would include a main rotor shaft with gas bearings; the bearing surfaces would be made of a ceramic material coated with nanocrystalline diamond. The shaft could withstand speed of 400,000 rpm or perhaps more, with bearing-wear rates less than 10(exp -)4 those of silicon bearings and 0.05 to 0.1 those of SiC bearings, and with a coefficient of friction about 0.1 that of Si or SiC bearings. The components of the system would be fabricated by a combination of (1) three-dimensional xray lithography and (2) highly precise injection molding of diamond-compatible metals and ceramic materials. The materials and fabrication techniques would be suitable for mass production. The disadvantages of the proposed system are that unlike a battery-based system, it could generate a perceptible amount of sound, and

Archie's Saturation Exponent for Natural Gas Hydrate in Coarse-Grained Reservoirs

Science.gov (United States)

Cook, Ann E.; Waite, William F.

2018-03-01

Accurately quantifying the amount of naturally occurring gas hydrate in marine and permafrost environments is important for assessing its resource potential and understanding the role of gas hydrate in the global carbon cycle. Electrical resistivity well logs are often used to calculate gas hydrate saturations, Sh, using Archie's equation. Archie's equation, in turn, relies on an empirical saturation parameter, n. Though n = 1.9 has been measured for ice-bearing sands and is widely used within the hydrate community, it is highly questionable if this n value is appropriate for hydrate-bearing sands. In this work, we calibrate n for hydrate-bearing sands from the Canadian permafrost gas hydrate research well, Mallik 5L-38, by establishing an independent downhole Sh profile based on compressional-wave velocity log data. Using the independently determined Sh profile and colocated electrical resistivity and bulk density logs, Archie's saturation equation is solved for n, and uncertainty is tracked throughout the iterative process. In addition to the Mallik 5L-38 well, we also apply this method to two marine, coarse-grained reservoirs from the northern Gulf of Mexico Gas Hydrate Joint Industry Project: Walker Ridge 313-H and Green Canyon 955-H. All locations yield similar results, each suggesting n ≈ 2.5 ± 0.5. Thus, for the coarse-grained hydrate bearing (Sh > 0.4) of greatest interest as potential energy resources, we suggest that n = 2.5 ± 0.5 should be applied in Archie's equation for either marine or permafrost gas hydrate settings if independent estimates of n are not available.

Tail thrust of bluefish Pomatomus saltatrix at different buoyancies, speeds, and swimming angles.

Science.gov (United States)

Ogilvy, C S; DuBois, A B

1982-06-01

1. The tail thrust of bluefish Pomatomus saltatrix was measured using a body accelerometer at different water speeds, buoyancies, and angles of water flow to determine the contribution of tail thrust in overcoming parasitic drag, induced drag, and weight directed along the track. The lengths and weights of the fish averaged 0.52 m and 1.50 kg respectively. 2. The tail thrust overcoming parasitic drag in Newtons, as measured during neutral buoyancy, was: 0.51 x speed + 0.15, with a standard error of estimate of 0.09 N. 3. When buoyancy was altered by the introduction or removal of air from a balloon implanted in the swim bladder, the tail thrust was altered by an amount of the same order as the value calculated for the induced drag of the pectoral fins. 4. The component of weight directed backward along the track was the weight in water multiplied by the sine of the angle of the swimming tunnel relative to horizontal. When this force was added to the calculated induced drag and tail thrust measured at neutral buoyancy, the rearward force equal to the tail thrust, at 45 ml negative buoyancy, 0.5 m s-1, and 15 degrees head up, was 0.12 N due to weight + 0.05 N due to induced drag + 0.40 N due to parasitic drag = 0.57 N total rearward force. 5. The conditions required for gliding were not achieved in our bluefish because the drag exceeded the component of the weight in water directed forward along the track at speeds above the stalling speed of the pectoral fins.

Examination and vibration characteristics of gas circulator (B1) of HENDEL

International Nuclear Information System (INIS)

Shimomura, Hiroaki; Izawa, Naoki; Ihzuka, Takayuki; Kawaji, Satoshi; Kunitama, Takehiko; Hayashi, Haruyoshi; Kobayashi, Toshiaki; Katoh, Michio

1985-06-01

An examination and vibration measurements were conducted on the gas bearing type high speed helium gas circulator after the failure on April 1984 and the repairing on August 1984. The examination made clear that the cause of the failure and scratching of gas bearing pads and journal shaft was found. The vibrational spectra showed a clear difference between failed and repaired conditions, and a frequency analysis technique by means of fast Fourier transform and a small-scale computer is expected as a useful method of diagnosis for circulators. A conceptual scheme of gas circulator diagnostic system based on above principle is shown, and a basic process of diagnostic software is described. (author)

OFFICE OF SCIENCE AND TECHNOLOGY AND INTERNATIONAL, NATURAL BARRIERS THRUST OVERVIEW

International Nuclear Information System (INIS)

B. Bodvarsson; Y. Tsang

2006-01-01

The Natural Barriers Thrust supports scientific studies of the natural system at the proposed repository site of Yucca Mountain. It stresses the realistic representation of the natural system with respect to processes and parameters, by means of laboratory, field, and modeling studies. It has the objectives to demonstrate that the natural barriers can make large contributions to repository performance, supporting the multiple-barrier concept for geological disposal of high-level radioactive waste; and to reduce the overall cost of repository development by elimination of unnecessary engineered components, given the demonstrated natural barriers performance. In this overview we enumerate the research projects within the Natural Barriers Thrust grouped under five elements: (1) Drift Seepage, (2) In-drift Environment, (3) Drift Shadow, (4) Unsaturated Zone Flow and Transport, and (5) Saturated Zone Flow and Transport. The long-term strategic plan of the Natural Barriers Thrust and some key results are also briefly described

A double pendulum plasma thrust balance and thrust measurement at a tandem mirror exhaust