WorldWideScience

Sample records for piston ring wear

  1. Wear Analysis of Top Piston Ring to Reduce Top Ring Reversal Bore Wear

    Directory of Open Access Journals (Sweden)

    P. Ilanthirayan

    2017-12-01

    Full Text Available The piston rings are the most important part in engine which controls the lubricating oil consumption and blowby of the gases. The lubricating film of oil is provided to seal of gases towards crankcase and also to give smooth friction free translatory motion between rings and liner. Of the three rings present top ring is more crucial as it does the main work of restricting gases downwards the crankcase. Boundary lubrication is present at the Top dead centre (TDC and Bottom dead centre (BDC of the liner surface. In addition to this, top ring is exposed to high temperature gases which makes the oil present near the top ring to get evaporated and decreasing its viscosity, making metal-metal contact most of the time. Due to this at TDC, excess wear happens on the liner which is termed as Top ring reversal bore wear. The wear rate depends upon many parameters such as lubrication condition, viscosity index, contact type, normal forces acting on ring, geometry of ring face, surface roughness, material property. The present work explores the wear depth for different geometries of barrel ring using Finite Element model with the help of Archard wear law and the same is validated through experimentation. The study reveals that Asymmetric barrel rings have less contact pressure which in turn reduces the wear at Top dead centre.

  2. Investigation of piston ring – cylinder liner dry wear using a block-on-ring test rig

    DEFF Research Database (Denmark)

    Bihlet, Uffe; Klit, Peder; Felter, Christian L.

    Characterization of the wear of piston rings and cylinder liner is an important aspect of large two stroke diesel engine design. Two major wear mechanisms exist; corrosive wear and mechanical wear. This paper deals with the most aggressive form of the latter, which is known as scuffing. Different...... that ceramic coating on the piston ring decreases the dry wear rate of both piston ring and liner, while the coefficient of friction is increased....

  3. Study of wear in piston ring of the vehicle engine using thin layer activation technique

    International Nuclear Information System (INIS)

    Khan, I.H.; Farooq, M.; Ghiyas-ud-Din; Gul, S.; Qureshi, R.M.; Jin Joon Ha; Wallace, G.

    2004-01-01

    Thin Layer Activation (TLA) technique was used to investigate piston ring wear of a six cylinders vehicle engine at various engine speeds and load conditions. The activated ring was installed in cylinder no.5 of the engine at middle position (compression ring). Monitoring was carried out on-line (extremely on the engine block) using 'Thin Layer Difference Method'. The calibration curve of the activity profile was prepared with the help of activation parameters determined at the time of ring activation in particle accelerator. The results show that the piston ring wear varies from 0.309 micron/hour to 0.404 micron/hour at given engine speed and load conditions. (author)

  4. Standard guide for measuring the wear volumes of piston ring segments run against flat coupons in reciprocating wear tests

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2011-01-01

    1.1 This guide covers and describes a profiling method for use accurately measuring the wear loss of compound-curved (crowned) piston ring specimens that run against flat counterfaces. It does not assume that the wear scars are ideally flat, as do some alternative measurement methods. Laboratory-scale wear tests have been used to evaluate the wear of materials, coatings, and surface treatments that are candidates for piston rings and cylinder liners in diesel engines or spark ignition engines. Various loads, temperatures, speeds, lubricants, and durations are used for such tests, but some of them use a curved piston ring segment as one sliding partner and a flat or curved specimen (simulating the cylinder liner) as its counterface. The goal of this guide is to provide more accurate wear measurements than alternative approaches involving weight loss or simply measuring the length and width of the wear marks. 1.2 This standard does not purport to address all of the safety concerns, if any, associated with its ...

  5. Stirling engine piston ring

    Science.gov (United States)

    Howarth, Roy B.

    1983-01-01

    A piston ring design for a Stirling engine wherein the contact pressure between the piston and the cylinder is maintained at a uniform level, independent of engine conditions through a balancing of the pressure exerted upon the ring's surface and thereby allowing the contact pressure on the ring to be predetermined through the use of a preloaded expander ring.

  6. Researches on the Piston Ring

    Science.gov (United States)

    Ehihara, Keikiti

    1944-01-01

    In internal combustion engines, steam engines, air compressors, and so forth, the piston ring plays an important role. Especially, the recent development of Diesel engines which require a high compression pressure for their working, makes, nowadays, the packing action of the piston ring far more important than ever. Though a number of papers have been published in regard to researches on the problem of the piston ring, none has yet dealt with an exact measurement of pressure exerted on the cylinder wall at any given point of the ring. The only paper that can be traced on this subject so far is Mr. Nakagawa's report on the determination of the relative distribution of pressure on the cylinder wall, but the measuring method adopted therein appears to need further consideration. No exact idea has yet been obtained as to how the obturation of gas between the piston and cylinder, the frictional resistance of the piston, and the wear of the cylinder wall are affected by the intensity and the distribution of the radial pressure of the piston ring. Consequently, the author has endeavored, by employing an apparatus of his own invention, to get an exact determination of the pressure distribution of the piston ring. By means of a newly devised ring tester, to which piezoelectricity of quartz was applied, the distribution of the radial pressure of many sample rings on the market was accurately determined. Since many famous piston rings show very irregular pressure distribution, the author investigated and achieved a manufacturing process of the piston ring which will exert uniform pressure on the cylinder wall. Temperature effects on the configuration and on the mean spring power have also been studied. Further, the tests were performed to ascertain how the gas tightness of the piston ring may be affected by the number or spring power. The researches as to the frictional resistance between the piston ring and the cylinder wall were carried out, too. The procedure of study, and

  7. A study on the piston ring wear in automotive engine Seat 1500 CA by means of radioactive tracer technique; Estudio del desgaste de segmentos en motor Seat 1500 CA mediante trazadores radiactivos

    Energy Technology Data Exchange (ETDEWEB)

    Val Cob, M del; Chul, Y; Fuentes Figuera de Vargas, J.

    1971-07-01

    The iron side wear in the chromium-plated top compression ring has been a matter of interest for the engine makers and it has been required by them to investigate the wear characteristics of the chromium-plated piston ring. Meanwhile, Bureau of Nuclear Energy in Spain (Junta de Energia Nuclear) and Seat Car Manufacturing Company (Sociedad Espanola de Automoviles de Turismo) agreed to study the wear characteristics of chromium-plated piston ring of type CA gasoline engine for Seat 1500 car by means of radioactive tracer technique. (Author) 9 refs.

  8. Integral Ring Carbon-Carbon Piston

    Science.gov (United States)

    Northam, G. Burton (Inventor)

    1999-01-01

    An improved structure for a reciprocating internal combustion engine or compressor piston fabricate from carbon-carbon composite materials is disclosed. An integral ring carbon-carbon composite piston, disclosed herein, reduces the need for piston rings and for small clearances by providing a small flexible, integral component around the piston that allows for variation in clearance due to manufacturing tolerances, distortion due to pressure and thermal loads, and variations in thermal expansion differences between the piston and cylinder liner.

  9. Development of a model capable of predicting the performance of piston ring-cylinder liner-like tribological interfaces

    DEFF Research Database (Denmark)

    Felter, C.L.; Vølund, A.; Imran, Tajammal

    2010-01-01

    Friction in the piston ring package (piston, piston rings, and liner) is a major source of power consumption in large two-stroke marine diesel engines. In order to improve the frictional and wear performance, knowledge about the tribological interface between piston rings and liner is needed...

  10. Double acting stirling engine piston ring

    Science.gov (United States)

    Howarth, Roy B.

    1986-01-01

    A piston ring design for a Stirling engine wherein the contact pressure between the piston and the cylinder is maintained at a uniform level, independent of engine conditions through a balancing of the pressure exerted upon the ring's surface and thereby allowing the contact pressure on the ring to be predetermined through the use of a preloaded expander ring.

  11. Design of Piston Ring Friction Tester Apparatus

    DEFF Research Database (Denmark)

    Klit, Peder

    2006-01-01

    One of the major prerequisites for calculating piston ring friction is a good description of the tribological situation. Piston rings operate in three different lubrication regimes and the theoretical models should be capable to describe this. A very important condition for describing the frictio......One of the major prerequisites for calculating piston ring friction is a good description of the tribological situation. Piston rings operate in three different lubrication regimes and the theoretical models should be capable to describe this. A very important condition for describing...... the frictional behavior of a piston ring correctly is knowledge about the amount of lubricant present. For piston rings the external load may be established by measuring the pressure distribution, i.e. the pressure drop in the piston ring package. Speed and temperature may also be established. The amount...... available is reflected in the friction absorbed in the bearing. The following properties will be measured: Oil fillm thickness - along liner (axial variation), oil film thickness - along piston ring (circumferential variation), piston tilt, temperature of piston rings and liner, pressure at piston lands...

  12. Mathematical Model of Piston Ring Sealing in Combustion Engine

    Directory of Open Access Journals (Sweden)

    Koszałka Grzegorz

    2015-01-01

    Full Text Available This paper presents a mathematical model of piston-rings-cylinder sealing (TPC of a combustion engine. The developed model is an itegrated model of gas flow through gaps in TPC unit, displacements and twisting motions of piston rings in ring grooves as well as generation of oil film between ring face surfaces and cylinder liner. Thermal deformations and wear of TPC unit elements as well as heat exchange between flowing gas and surrounding walls, were taken into account in the model. The paper contains descriptions of: assumptions used for developing the model, the model itself, its numerical solution as well as its computer application for carrying out simulation tests.

  13. Multi technical analysis of wear mechanisms in axial piston pumps

    Science.gov (United States)

    Schuhler, G.; Jourani, A.; Bouvier, S.; Perrochat, J.-M.

    2017-05-01

    Axial piston pumps convert a motor rotation motion into hydraulic or pneumatic power. Their compactness and efficiency of approximately 0.9 make them suitable for actuation applications especially in aeronautics. However, they suffer a limited life due to the wear of their components. In the literature, studies of axial piston pumps deal with contact between its different elements under lubrication conditions. Nevertheless, they are more focused on analytic or numerical approaches. This study consists in an experimental analysis of worn pump components to highlight and understand wear mechanisms. Piston shoes are central components in the axial piston pump since they are involved in three tribological contacts. These three contacts are thereby studied: piston shoes/swashplate, piston shoes/pistons and piston shoes/shoes hold down plate (SHDP). To perform this analysis, helicopter hydraulic pumps after different operating times have been studied. The wear damage mechanisms and wear debris are analysed using SEM observations. 3D surface roughness measurements are then used to characterize worn surfaces. The observations reveal that in the contact between shoes and swashplate, the main wear mechanism is three-body abrasive wear due to coarse carbides removal. Between shoes and pistons, wear occurs in a less severe way and is mainly due to the debris generated in the first contact and conveyed by the lubricating fluid. In the third contact, the debris are also the prime cause of the abrasive wear and the generation of deep craters in the piston shoes.

  14. Lubrication of Piston Rings in Large 2–and 4–stroke Diesel Engines

    DEFF Research Database (Denmark)

    Felter, Christian Lotz

    Piston rings are vital components of any internal combustion engine, and their performance affect important properties such as frictional losses, oil consumption, and wear of parts. This thesis deals with the lubrication of piston rings from a theoretical point of view. Predictions are made using...

  15. Experimental Investigation of Piston Rings for Internal Combustion Engines

    DEFF Research Database (Denmark)

    Christiansen, Jens; Klit, Peder; Vølund, Anders

    2007-01-01

    One of the major prerequisites for calculating piston ring friction is a good description of the tribological situation. A very important condition for describing the frictional behavior of a piston ring correctly is knowledge about the amount of lubricant present. For piston rings the external...... forces are small compared to the rest of the acting forces the main design idea is to fix the piston, while the cylinder liner moves. This approach makes it simple to measure the parameters mentioned above by putting the instrumentation in the piston. The aim of this paper is describe the tribological...

  16. Experimental Piston Ring Tribology for Marine Diesel Engines

    DEFF Research Database (Denmark)

    Klit, Peder; Vølund, Anders

    2008-01-01

    A very important condition for describing the frictional behavior of a piston ring correctly is knowledge about the amount of lubricant present. It is often assumed that piston rings operate under fully flooded conditions, but this is not the case in real life operation. In large two-stroke engin...

  17. TRIBOLOGICAL PERFORMANCE OF PISTON RING IN MARINE DIESEL ENGINE

    DEFF Research Database (Denmark)

    Imran, Tajammal; Klit, Peder; Felter, Christian

    From a tribology point of view, it is the two dead centers that are the main area of interest for experimental study of piston rings in large marine diesel engines. Therefore, in this work the performance of piston rings is studied to mark the importance of the two dead centers. A test rig based...

  18. Piston ring lubrication and hydrocarbon emissions from internal combustion engines

    Energy Technology Data Exchange (ETDEWEB)

    Froelund, K.

    1997-11-01

    Is it the intention with this project to improve the existing hydrocarbon emission model at the Institute by combining it with a model for predicting the piston ring lubrication. The piston ring lubrication model should be experimentally verified to ensure the validity of the model. The following items were the objectives of the current study: Develop a piston ring lubrication model. This implies the development of a ring-pack gas flow model; Examine the response of the piston ring lubrication model to changing engineer conditions. Especially, it would be interesting to look at the engine warm-up phase since this is the phase where the engine-out emissions are highest and where the commonly used three way catalyst is not capable of converting the engine-out emissions, thereby leading the engine-out emissions directly out in to the environment with the exhaust gases; In order to verify the piston ring lubrication model the lubricant distribution on the cylinder liner should be investigated experimentally. Here again it would be of great interesting to look at the engine warm-up phase; The piston ring lubrication model should be adjusted for application together with the new hydrocarbon emission model for SI-engines at the Institute in order to increase the accuracy of the latter; The piston ring lubrication model could be used for describing the transport of PAH`s in diesel engines. (EG)

  19. Computational Modelling of Piston Ring Dynamics in 3D

    Directory of Open Access Journals (Sweden)

    Dlugoš Jozef

    2014-12-01

    Full Text Available Advanced computational models of a piston assembly based on the level of virtual prototypes require a detailed description of piston ring behaviour. Considering these requirements, the piston rings operate in regimes that cannot, in general, be simplified into an axisymmetric model. The piston and the cylinder liner do not have a perfect round shape, mainly due to machining tolerances and external thermo-mechanical loads. If the ring cannot follow the liner deformations, a local loss of contact occurs resulting in blow-by and increased consumption of lubricant oil in the engine. Current computational models are unable to implement such effects. The paper focuses on the development of a flexible 3D piston ring model based on the Timoshenko beam theory using the multibody system (MBS. The MBS model is compared to the finite element method (FEM solution.

  20. Tribological Performance of Different Geometries of Piston Rings in Marine Diesel Engines

    DEFF Research Database (Denmark)

    Imran, Tajammal; Klit, Peder; Felter, Christian

    Friction in the piston ring package (piston, piston rings and liner) is a major source of power consumption in two stroke marine diesel engines. It is well-known that a typical piston ring operates under full separation in the mid-part of the stroke, and in the mixed lubrication regime at the dead...

  1. Translational velocity oscillations of piston generated vortex rings

    Science.gov (United States)

    Kumar, Manoj; Arakeri, J. H.; Shankar, P. N.

    1995-11-01

    Experimental results are presented that show that the translational velocities of piston generated vortex rings often undergo oscillations, similar to those recently discovered for drop generated rings. An attempt has been made to minimize uncertainties by utilizing both dye and hydrogen bubbles for visualization and carefully repeating measurements on the same ring and on different realizations under the same nominal piston conditions. The results unambiguously show that under most conditions, both for laminar and turbulent rings and for rings generated from pipes and orifices, the oscillations are present. The present results, together with the earlier results on drop generated rings, give support to the view that translational velocity oscillations are probably an inherent feature of translating vortex ring fields.

  2. Fluorocarbon seal replaces metal piston ring in low density gas environment

    Science.gov (United States)

    Morath, W. D.; Morgan, N. E.

    1967-01-01

    Reinforced fluorocarbon cupseal, which provides an integral lip-type seal, replaces the metal piston rings in piston-cylinder configurations used in the compression of low density gases. The fluorocarbon seal may be used as cryogenic compressor piston seals.

  3. Investigation of preparation technique and tribological properties of CrN piston rings coatings

    International Nuclear Information System (INIS)

    Cai Zhihai; Zhang Ping; Zhao Junjun; Du Jun; Niu Qingyin

    2009-01-01

    By using multi-ion plating, CrN films were made on surface of piston rings to improve its tribological properties and service life. Effects of nitrogen content to prepare the film on hardness and phase structure were studied. The high-temperature tribological properties of Cr plating and CrN films were compared with CETR friction tester. The results show that nitrogen partial pressure significantly affects the mechanical properties of CrN films. With increasing N 2 partial pressure, preferential growth orientation of the film changed from Cr 2 N(211) to CrN(220) phase, leading to two hardness peaks corresponding to the Cr 2 N and CrN phases,respectively. Having higher high-temperature wear resistance and lower friction coefficient than Cr plating, the CrN films are suitable for piston rings under high temperature conditions. (authors)

  4. Contribution of developing advanced engineering methods in interdisciplinary studying the piston rings from 1.6 spark ignited Ford engine at Technical University of Cluj-Napoca

    Science.gov (United States)

    -Aurel Cherecheş, Ioan; -Ioana Borzan, Adela; -Laurean Băldean, Doru

    2017-10-01

    Study of construction and wearing process in the case of piston-rings and other significant components from internal combustion engines leads at any time to creative and useful optimizing ideas, both in designing and manufacturing phases. Main objective of the present paper is to realize an interdisciplinary research using advanced methods in piston-rings evaluation of a common vehicle on the streets which is Ford Focus FYDD. Specific objectives are a theoretical study of the idea for advanced analysis method in piston-rings evaluation and an applied research developed in at Technical University from Cluj-Napoca with the motor vehicle caught in the repairing process.

  5. The Tribological Performance of CrMoN/MoS2 Solid Lubrication Coating on a Piston Ring

    Directory of Open Access Journals (Sweden)

    Yuelan Di

    2017-05-01

    Full Text Available In order to improve the tribological properties of an engine piston ring and enhance its service life, magnetron sputtering technology and low temperature ion sulphurizing treatment technology were used to prepare CrMoN/MoS2 solid lubricant coating on the surface of an engine piston ring. The morphologies and compositions of the surface and cross-section of the sulfuration layer were analyzed by field emission scanning electron microscopy (FESEM, and wear property under high load, high speed and high temperature conditions were tested by a SRV®4 friction and wear testing machine. The results show that the CrMoN/MoS2 composite coatings appear as a dense grain structure, and the coating is an ideal solid lubrication layer that possesses an excellent high temperature wear resistance, reducing the engine operating temperature abrasion effectively and prolonging the service life of the engine.

  6. Wear Performance of Bionic Dimpled-Shape Pistons of Mud Pump

    Directory of Open Access Journals (Sweden)

    Xuejing Cheng

    2017-01-01

    Full Text Available The piston is one of the parts that most easily become worn out and experience failure in mud pumps for well drilling. By imitating the body surface morphology of the dung beetle, this paper proposed a new type (BW-160 of mud pump piston that had a dimpled shape in the regular layout on the piston leather cup surface and carried out a performance test on the self-built test rig. Firstly, the influence of different dimple diameters on the service life of the piston was analyzed. Secondly, the analysis of the influence of the dimple central included angle on the service life of the piston under the same dimple area density was obtained. Thirdly, the wear of the new type of piston under the same wear time was analyzed. The experimental results indicated that the service life of the piston with dimples on the surface was longer than that of L-Standard pistons, and the maximum increase in the value of service life was 92.06%. Finally, the Workbench module of the software ANSYS was used to discuss the wear-resisting mechanism of the new type of piston.

  7. Thin layer activation (TLA) experiment of piston ring F.J product by using nuclear facility proton beam 12.5 MeV

    International Nuclear Information System (INIS)

    Sudarmono; Silakhuddin

    2002-01-01

    The experiment of thin layer activation of piston ring F.J product, was done. The purpose of this experiment are to measure material wearing level by using concentration method. The experiment was carried out by activated piston ring proton beam with energy 12,5 MeV and beam current 1 μA for 30 minutes then was continued by wearing process. The measurement of the wear result activity was carried out by pouring the total of volume of lubricant oil for radioactivity measurement. Measurement of the activity level used the gamma spectroscopy. The minimum wearing duration that can detects a wear was 5 hours. The activity count was 1.230 pulse per 30 seconds which is in accordance with a wear in order of 8 mg of Fe material on 1 liter oil lubricant, this result is same with the result of T. Delvigne namely is less than 10 mgr

  8. Material Characterization and Real-Time Wear Evaluation of Pistons and Cylinder Liners of the Tiger 131 Military Tank

    OpenAIRE

    Saeed, Adil; Khan, Zulfiqar Ahmad; Hadfield, Mark; Davies, S.

    2013-01-01

    Material characterisation and wear evaluation of the original and replacement pistons and cylinder-liners of Tiger 131 is reported. Original piston and cylinder-liner were operative in the Tigers’ engine during WWII. The replacement piston and cylinder-liner were used as substitutes and were obtained after failure in two hours of operation in the actual engine. Material characterisation revealed that the original piston was aluminium silicon hypereutectic alloy whereas the replacement piston ...

  9. Effects of Surface Irregularities on Piston Ring-Cylinder Tribo Pair of a Two Stroke Motor Engine in Hydrodynamic Lubrication

    Directory of Open Access Journals (Sweden)

    A. Zavos

    2015-03-01

    Full Text Available Tribological parameters such as friction, lubrication and wear influence strongly the engine component's life. In this study, a piston ring-cylinder system simulated taking into account the surface modifications under fully flooded lubrication and normal engine conditions. The hydrodynamic pressure field solved based on the Navier Stokes equations by Fluid Structure Interaction analysis. A real experimental data of piston ring-cylinder was used from a two stroke motor engine 50 cc. The surface irregularities are measured by 3D coordinate measurement machine while the engine has been worked about 4000 hours. The friction force, the hydrodynamic pressure, the oil film and the mechanical stresses were predicted for different engine conditions. Results show that the worn profile ring reduces the friction as well as the mechanical stresses increased. Surface condition of worn top ring was observed after a metallurgical profile analysis.

  10. Development and verification of a reciprocating test rig designed for investigation of piston ring tribology

    DEFF Research Database (Denmark)

    Pedersen, Michael Torben; Imran, Tajammal; Klit, Peder

    2009-01-01

    This paper describes the development and verification of a reciprocating test rig, which was designed to study the piston ring tribology. A crank mechanism is used to generate a reciprocating motion for a moving plate, which acts as the liner. A stationary block acting as the ring package is loaded......, which is suitable for the study of piston ring tribology....

  11. The highlighting of an internal combustion engine piston ring radial oscillations

    Directory of Open Access Journals (Sweden)

    Djallel ZEBBAR

    2016-06-01

    Full Text Available This paper deals with the definition of the lube-oil film thickness in the piston ring cylinder liner junction of an internal combustion engine. At first, a mathematical model for the estimation of the film thickness is established. It is used to point out the oscillating motion of the piston ring normal to the cylinder wall. For the first time, has been highlighted and analytically evaluated the oscillating behavior of the piston ring in its housing in the radial direction. Furthermore, it is demonstrated that the radial oscillations frequency is a function of piston ring stiffness, material and geometry.

  12. Performance Degradation Analysis of Aviation Hydraulic Piston Pump Based on Mixed Wear Theory

    Directory of Open Access Journals (Sweden)

    C. Zhang

    2017-06-01

    Full Text Available This paper focuses on the mathematical modeling of axial piston pump through dividing the failure development of friction pair into lubrication, mixed lubrication and abrasion. Directing to the wedge-shaped oil film between cylinder block and valve plate, the support force distribution under the temperature variance was obtained. Considering the rough peak of valve plate, the contact load model is built under plastic deformation and elastic deformation and the corresponding wear volume is calculated. Computing the wear and tear along the counter-clockwise, the total amount of friction and wear can be calculated. Simulation and preliminary wear particle monitoring test indicates that proposed modeling and analysis can effectively reflect the real abrasion process of hydraulic piston pump.

  13. Diagnosing wear and tear of piston packing in car hydraulic shock absorbers

    Directory of Open Access Journals (Sweden)

    Janusz GARDULSKI

    2009-01-01

    Full Text Available The paper presents method of diagnosing hydraulic shock absorber with wear and tear of piston packing. There are diagrams of shock absorbers for different cases of tightness reduction. Damping characteristics for different cases of reduction in tightness are shown at the end of article.

  14. Novel Tribotester for Cylinder Liner/Piston Ring Contacts of Two Stroke Marine Diesel Engines

    DEFF Research Database (Denmark)

    Pedersen, Michael Torben; Imran, Tajammal; Klit, Peder

    2009-01-01

    A good tribological description for the cylinder liner and piston ring materials is always desired in order to achieve an improved combination of the materials. The piston ring package in a two-stroke-diesel engine operates in three lubrication regimes and the materials must be characterized...... in relation to this before a final selection is made. A tribo-test-apparatus is developed to study the tribological performance and to rank the different combinations of cylinder liner and piston ring materials of two stroke marine diesel engines. The test apparatus is based on the block-on-ring principle...

  15. The intermetallic bonding between a ring carrier and aluminum piston alloy

    Directory of Open Access Journals (Sweden)

    Manasijevic, Srećko

    2015-09-01

    Full Text Available This paper presents the results of investigating the formation of intermetallic bond between a ring carrier and aluminum piston alloy. The ring carrier is made of austenitic cast iron (Ni-Resist in order to increase the wear resistance of the first ring groove and applied in highly loaded diesel engines. Metallographic examination of the quality of alfin bond was done. A metallographic investigation using an optical microscope in combination with the SEM/EDS analysis of the quality of the intermetallic bonding layer was done. The test results show that can be made successfully as well as the formation of metal connection (alfin bond between the ring carrier and aluminum piston alloy.El artículo presenta los resultados de la investigación sobre la formación de una unión intermetálica entre el portasegmento y la aleación de aluminio del pistón. El portasegmento es una fundición de hierro austenítico (Ni-Resist con el fin de aumentar la resistencia al desgaste de la unión Al-fin del primer segmento y se utiliza en motores diésel altamente cargados. Se realizó un examen metalográfico de la unión intermetálica, mediante un microscopio óptico en combinación con SEM/EDS. Los satisfactorios resultados obtenidos muestran la formación de contacto metálico (unión Al-fin del primer segmento entre el portasegmento y la aleación de aluminio del pistón.

  16. Investigation of Different Piston Ring Curvatures on Lubricant Transport along Cylinder Liner in Large Two-Stroke Marine Diesel Engines

    DEFF Research Database (Denmark)

    Overgaard, Hannibal Christian; Klit, Peder; Vølund, Anders

    2016-01-01

    A theoretical investigation of the hydrodynamic lubrication of the top compression piston ring in a large two-stroke marine diesel engine is presented. The groove mounted piston ring is driven by the reciprocal motion of the piston. The ring shape follows a circular geometry and the effect...

  17. Investigation of different piston ring curvatures on lubricant transport along cylinder liner in large two-stroke marine diesel engines

    DEFF Research Database (Denmark)

    Overgaard, H; Klit, P; Vølund, A

    2017-01-01

    A theoretical investigation of the hydrodynamic lubrication of the top compression piston ring in a large two-stroke marine diesel engine is presented. The groove mounted piston ring is driven by the reciprocal motion of the piston. The ring shape follows a circular geometry and the effect...

  18. Standard test method for conducting friction tests of piston ring and cylinder liner materials under lubricated conditions

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2011-01-01

    1.1 This test method covers procedures for conducting laboratory bench-scale friction tests of materials, coatings, and surface treatments intended for use in piston rings and cylinder liners in diesel or spark-ignition engines. The goal of this procedure is to provide a means for preliminary, cost-effective screening or evaluation of candidate ring and liner materials. A reciprocating sliding arrangement is used to simulate the contact that occurs between a piston ring and its mating liner near the top-dead-center position in the cylinder where liquid lubrication is least effective, and most wear is known to occur. Special attention is paid to specimen alignment, running-in, and lubricant condition. 1.2 This test method does not purport to simulate all aspects of a fired engine’s operating environment, but is intended to serve as a means for preliminary screening for assessing the frictional characteristics of candidate piston ring and liner material combinations in the presence of fluids that behave as u...

  19. Pistonics

    DEFF Research Database (Denmark)

    Perram, John W.; Præstgaard, Eigil; Smith, Edgar R.

    2011-01-01

    is proportional to its internal energy. We report molecular dynamics experiments with ideal gas particles and show that they can exchange energy with their container. We then construct a dynamical system modelling the motion of the piston and heat transfer to the surroundings when the piston is released...... to the dynamical system can make it resemble a quasi-static process. We then generalise the dynamical system to a two-compartment adiabatic cylinder in which the gases in the two chambers are separated by a movable piston. We show that, if the piston is subjected to infinitesimal kinetic friction, in all cases...

  20. PISTON

    Energy Technology Data Exchange (ETDEWEB)

    Sewell, Christopher Meyer [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-01-08

    This presentation was a part of the guest lecture series for graduate classes at the University of Oregon on many-core visualization. It discussed a practical introduction to high-level data parallelism using thrust and PISTON; presented an overview of PISTON and PINION; provided tutorial examples; additional details on research results.

  1. Experimental Investigation of Piston Rings for Internal Combustion Engines

    DEFF Research Database (Denmark)

    Klit, Peder; Vølund, Anders

    2008-01-01

    absorbed in the bearing. Since the frictional forces are small compared to the rest of the acting forces the rig is designed such that the piston is fixed while the cylinder liner moves. This approach makes it simple to measure the parameters mentioned above by putting the instrumentation in the piston...

  2. Syntheses and Tribological Property of CrMoN/MoS2 Multilayer Films on Piston Rings of Heavy Vehicle Engine

    Institute of Scientific and Technical Information of China (English)

    WANG Xiancheng; LI Qi; LI Ruoting; DI Yuelan

    2016-01-01

    In order to prolong the service life of piston rings of heavy vehicle engine and decrease the friction and wear of piston rings and cylinder liner, CrMoN/MoS2 multilayer iflms were deposited on the surface of rings by magnetron sputtering and low temperature ion sulfuration. FESEM equipped with EDX was adopted to analyze the compositions and morphologies of surface, cross-section, and wear scars of the multilayer iflms. The nano-hardness and Young’s modulus of the iflms were measured by a nano tester. Tribological properties of the iflms were tested by an SRV®4 wear tester. The experimental results indicate that the structures of the multilayer films are dense and compact. The films possess nano hardness value of approximately 26.7 GPa and superior ability of plastic deformation resistance. The multilayer iflms can activate solid lubricating, and possess an excellent antifriction and wear resistance under the conditions of heavy load, high frequency, high temperature, and dynamic load.

  3. PROSPECTS OF MANUFACTURE OF PISTON RINGS INTERNAL COMBUSTION ENGINES OF POWDER MATERIALS ON THE BASE OF IRON

    Directory of Open Access Journals (Sweden)

    B. M. Musaibov

    2013-01-01

    Full Text Available Development and production of piston rings made of sintered materials on the basis of iron powder metallurgy is an innovative way. In the application of this technology reduces the consumption of material and costs for the production of piston rings 30-40% in comparison with the traditional methods of their manufacture

  4. An Improved Lubrication Model between Piston Rings and Cylinder Liners with Consideration of Liner Dynamic Deformations

    Directory of Open Access Journals (Sweden)

    Guoxing Li

    2017-12-01

    Full Text Available The friction pair of piston rings and cylinder liner is one of the most important friction couplings in an internal combustion engine. It influences engine efficiency and service life. Under the excitation of piston slaps, the dynamic deformation of cylinder liner is close to the surface roughness magnitudes, which can affect the friction and lubrication performance between the piston rings and cylinder assemblies. To investigate the potential influences of structural deformations to tribological behaviours of cylinder assemblies, the dynamic deformation of the inner surface due to pistons slaps is obtained by dynamic simulations, and then coupled into an improved lubrication model. Different from the traditional lubrication model which takes the pressure stress factor and shear stress factor to be constant, the model proposed in this paper calculated these factors in real time using numerical integration to achieve a more realistic simulation. Based on the improved piston rings and cylinder liner lubrication model, the minimum oil film thickness and friction force curves are obtained for an entire work cycle. It shows that the friction force obtained from the improved model manifests clear oscillations in each stoke, which is different from the smoothed profiles predicted traditionally. Moreover, the average amplitude of the friction forces also shows clear reduction.

  5. Influence of oil starvation on piston ring oil film thickness; Junkatsuyu kyokyuryo fusoku ga ring yumaku ni ataeru eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Hiruma, M [Musashi Institute of Technology, Tokyo (Japan). Hydrogen Energy Research Center; Takiguchi, M [Musashi Institute of Technology, Tokyo (Japan)

    1997-10-01

    An analytical behavior of the piston ring oil film has been carried out theoretically under the condition where sufficient lubrication oil dose not exist. Phenomena have been studied on the oil film when plural rings slide together on the surface of cylinder with a new concept in addition to the well-known assumptions. In particular, a comparison has been made on the friction force with the data obtained by the floating liner method. 5 refs., 9 figs.

  6. A new production technique for wear resistant ring-hammers

    Directory of Open Access Journals (Sweden)

    Li Shifeng

    2011-11-01

    Full Text Available Based on a great number of laboratory experiments, a new technique has been developed for producing wear resistant ring-hammers. In this technology, lost foam casting with iron sand was combined to make mold; a special alloy was used to inoculate the molten steel, and proper heat treatment was used to further improve mechanical properties of wear resistant ring-hammers. The influence of this new production technology on the microstructure and mechanical properties of wear resistant ring-hammers was studied. Results show that iron sand molding, having the inherent characteristic of sand molding, changes the type of metallic compounds, refines crystal grains and increases the fineness of microstructure. Practical experience verified that the properties of the ring-hammers produced with this new technique are as follows: tensile strength (Rm 720 MPa, impact toughness (ak > 210 J•cm-2 and hardness > 200 HB. After water quenching from 1,080℃ (holding for 4 h and tempering at 320℃ for 3 h, the best wear resistance is obtained, and the wear resistance is 1.6 times higher than that of common high manganese ring-hammers.

  7. Investigation of friction characteristics in segmented piston ring liner assembly of IC engine

    Directory of Open Access Journals (Sweden)

    Tejaskumar Chaudhari

    2016-09-01

    Full Text Available The friction at the piston ring cylinder liner assembly (PRLA is a major contributor in the total friction losses in the I.C. engine. New materials, coatings and high-tech machining processes that previously were considered to be too expensive and therefore only used in complex applications are today becoming more affordable. A significant amount of the total power loss in a modern automotive engine is due to the Friction interaction between the top compression ring and the cylinder liner, especially at the TDC and BDC where boundary lubrication exists. The change in piston speed is accompanied with change the lubrication regime in the cylinder, which results change in friction between the ring and the liner during the entire stroke of the piston. Theoretical modelling of friction force from the various sources of friction will be compared to experimental results for analysing the tribological characteristics. The appropriate sample of piston ring and cylinder liner pair is developed for studying the different tribological parameters on Reciprocating Tribometer. The variable parameters are engine speed, oil viscosity, and load. The experimental results and observations are studied under different operating conditions in speed ranges from 300 rpm to 1500 rpm with constant load of 60 N. It can be seen that as speed increases, the friction force and friction coefficient also decreases.

  8. Lead-free, bronze-based surface layers for wear resistance in axial piston hydraulic pumps

    Energy Technology Data Exchange (ETDEWEB)

    Vetterick, Gregory Alan [Iowa State Univ., Ames, IA (United States)

    2010-01-01

    Concerns regarding the safety of lead have provided sufficient motivation to develop substitute materials for the surface layer on a thrust bearing type component known as a valve plate in axial piston hydraulic pumps that consists of 10% tin, 10% lead, and remainder cooper (in wt. %). A recently developed replacement material, a Cu-10Sn-3Bi (wt.%) P/M bronze, was found to be unsuitable as valve plate surface layer, requiring the development of a new alloy. A comparison of the Cu-1-Sn-10Pb and Cu-10Sn-3Bi powder metal valve plates showed that the differences in wear behavior between the two alloys arose due to the soft phase bismuth in the alloy that is known to cause both solid and liquid metal embrittlement of copper alloys.

  9. Some study on radiation resistance and reliability of piston ring of waste gas compressor for fast breeder experimental reactor

    International Nuclear Information System (INIS)

    Muramatsu, Takio; Hidaka, Tsukasa

    1976-01-01

    In the fast breeder experimental reactor ''Joyo'', the gaseous wastes such as reactor cover argon, reactor seal nitrogen gas, fuel handling waste gas etc. shall be collected, compressed and storaged for decaying their activity. Compressors applied in the above process have new type oilless piston rings of Teflon filled with graphite, which might be affected by radioactivity of the waste gases. This report deals with some study on the gamma iradiation effects on the plastic piston rings such as tensile strength, elongation, shock and hardness effects under several irradiation doses and on durability test of the irradiated piston rings under the same compression ratio. (auth.)

  10. Research on the effect of wear-ring clearances to the axial and radial force of a centrifugal pump

    International Nuclear Information System (INIS)

    Zhao, W G; Qi, C X; Li, Y B; He, M Y

    2013-01-01

    Varying of the wear-ring clearance not only has a distinct effect on the volumetric loss of the centrifugal pump, but also on the performance of the centrifugal pump including the axial and radial forces. Comparing with the experimental studies, numerical simulation methods have some special advantages, such as the low cost, fast and high efficiency, and convenient to get the detailed structure of the internal flow characteristics, so it has been widely used in the fluid machinery study in recent years. In order to study the effect of wear-ring clearance on the force performance of the centrifugal pump, based on the Reynolds Time-Averaged N-S equations and RNG k-ε turbulence model, a centrifugal pump with three variable styles of the wear-rings was simulated: Only the clearance of the front wear-ring was changed, only the clearance of the back wear-ring was changed and both were changed. Comparing with the experiment, numerical results show a good agreement. In the three changing styles of the clearance, the variable of the clearance of front wear-ring has the most influence on the axial force of the centrifugal pump, while has tiny effect on the radial force for all the conditions

  11. Analysis of oil consumption in cylinder of diesel engine for optimization of piston rings

    Science.gov (United States)

    Zhang, Junhong; Zhang, Guichang; He, Zhenpeng; Lin, Jiewei; Liu, Hai

    2013-01-01

    The performance and particulate emission of a diesel engine are affected by the consumption of lubricating oil. Most studies on oil consumption mechanism of the cylinder have been done by using the experimental method, however they are very costly. Therefore, it is very necessary to study oil consumption mechanism of the cylinder and obtain the accurate results by the calculation method. Firstly, four main modes of lubricating oil consumption in cylinder are analyzed and then the oil consumption rate under common working conditions are calculated for the four modes based on an engine. Then, the factors that affect the lubricating oil consumption such as working conditions, the second ring closed gap, the elastic force of the piston rings are also investigated for the four modes. The calculation results show that most of the lubricating oil is consumed by evaporation on the liner surface. Besides, there are three other findings: (1) The oil evaporation from the liner is determined by the working condition of an engine; (2) The increase of the ring closed gap reduces the oil blow through the top ring end gap but increases blow-by; (3) With the increase of the elastic force of the ring, both the left oil film thickness and the oil throw-off at the top ring decrease. The oil scraping of the piston top edge is consequently reduced while the friction loss between the rings and the liner increases. A neural network prediction model of the lubricating oil consumption in cylinder is established based on the BP neural network theory, and then the model is trained and validated. The main piston rings parameters which affect the oil consumption are optimized by using the BP neural network prediction model and the prediction accuracy of this BP neural network is within 8%, which is acceptable for normal engineering applications. The oil consumption is also measured experimentally. The relative errors of the calculated and experimental values are less than 10%, verifying the

  12. Nonlinear quantum piston for the controlled generation of vortex rings and soliton trains

    KAUST Repository

    Pinsker, Florian; Berloff, Natalia G.; Pé rez-Garcí a, Ví ctor M.

    2013-01-01

    We propose a simple way to generate nonlinear excitations in a controllable way by managing interactions in Bose-Einstein condensates. Under the action of a quantum analog of a classical piston, the condensed atoms are pushed through the trap, generating vortex rings infully three-dimensional condensates or soliton trains in quasi-one-dimensional scenarios. The vortex rings form due to transverse instability of the shock-wave train, enhanced and supported by the energy transfer between waves. We elucidate in what sense the self-interactions within the atom cloud define the properties of the generated vortex rings and soliton trains. Based on the quantum-piston scheme we study the behavior of two-component Bose-Einstein condensates and analyze how the presence of an additional superfluid influences the generation of vortex rings or solitons in the other component, and vice versa. Finally, we show the dynamical emergence of skyrmions within two-component systems in the immiscible regime. © 2013 American Physical Society.

  13. Nonlinear quantum piston for the controlled generation of vortex rings and soliton trains

    KAUST Repository

    Pinsker, Florian

    2013-05-29

    We propose a simple way to generate nonlinear excitations in a controllable way by managing interactions in Bose-Einstein condensates. Under the action of a quantum analog of a classical piston, the condensed atoms are pushed through the trap, generating vortex rings infully three-dimensional condensates or soliton trains in quasi-one-dimensional scenarios. The vortex rings form due to transverse instability of the shock-wave train, enhanced and supported by the energy transfer between waves. We elucidate in what sense the self-interactions within the atom cloud define the properties of the generated vortex rings and soliton trains. Based on the quantum-piston scheme we study the behavior of two-component Bose-Einstein condensates and analyze how the presence of an additional superfluid influences the generation of vortex rings or solitons in the other component, and vice versa. Finally, we show the dynamical emergence of skyrmions within two-component systems in the immiscible regime. © 2013 American Physical Society.

  14. USAHA PENURUNAN PERSENTASE CACAT RING PISTON TIPE 4JA1 PADA PROSES HABANAKASHI MESIN BESLY

    Directory of Open Access Journals (Sweden)

    E.V. Yuliana Wibisono

    2007-01-01

    Full Text Available One of the programs that can be used to improve the quality is Six Sigma program using DMAIC method. The research is performed at PT Baninusa Indonesia (PT. BN producing the 2nd type of 4JA1 piston ring. The program is implemented to decrease the defect proportion The production process performance and the problem priority are known from the CTQ itself. The fish bone diagram is used to determine the causes of the problem. The improvement is performed by determination of the best process parameter through the fullfactorial experiment design. The result is significantly decrease defect proportion by 2.682%. Abstract in Bahasa Indonesia : Salah satu program peningkatan kualitas yang dapat mengakomodasi tuntutan peningkatan kualitas adalah program Six Sigma dengan menggunakan metode DMAIC. Penelitian dilakukan pada PT.Baninusa Indonesia (PT.BN, salah satu perusahaan yang memproduksi produk ring piston tipe 4JA1 jenis 2nd ring. Program digunakan untuk menurunkan persentase cacat produk. Dari CTQ yang ada dapat diketahui kinerja proses produksi saat ini dan prioritas permasalahan. Fish bone diagram digunakan untuk akar penyebab masalah Tindakan perbaikan yang dipilih adalah menentukan parameter proses terbaik dengan menggunakan metode eksperimen full factorial. Hasil penerapan parameter proses tersebut menunjukkan pengurangan yang signifikan terhadap persentase cacat sebesar 2,682%. Kata kunci: metoda six sigma, DMAIC, perbaikan kualitas, karakteristik kualitas kritis, diagram fish bone.

  15. Calculation of Oil Film Thickness from Damping Coefficients for a Piston Ring in an Internal Combustion Engine

    DEFF Research Database (Denmark)

    Christiansen, Jens; Klit, Peder; Vølund, Anders

    2007-01-01

    engine. The basic idea is to use the fluid film damping coefficients to estimate the film thickness variation for a piston ring under cyclic varying load. Reynolds Equation is solved for a piston ring and the oil film thickness is determined. In this analysis hydrodynamic lubrication is assumed......In 1966 Jorgen W. Lund published an approach to find the dynamic coefficients of a journal bearing by a first order perturbation of the Reynold's equation. These coefficients made it possible to perform a rotor-bearing stability analysis for a statically loaded bearing. In the mid seventies Jorgen...

  16. Engine including a piston member having a high top ring groove

    Energy Technology Data Exchange (ETDEWEB)

    Weber, R.L.; Kamman, K.R.; Ballheimer, B.; Shoup, S.G.

    1990-07-17

    This patent describes an improvement in an engine. It is of the type having a block defining an upper bore, a cylinder liner located in the block bore and defining a piston bore, a cylinder head connected to the block, and a piston assembly including a steel piston member disposed for reciprocation in the piston bore.

  17. Lubricant transport across the piston ring with flat and triangular lubrication injection profiles on the liner in large two-stroke marine diesel engines

    DEFF Research Database (Denmark)

    Overgaard, H.; Klit, P.; Vølund, A.

    2018-01-01

    A theoretical investigation of the lubricant transport across the top compression piston ring in a large two-stroke marine diesel engine is presented. A numerical model for solving Reynolds equation between the piston ring and cylinder liner based on the finite difference method in one dimension...

  18. An Electron-Diffraction Examination of Cast-Iron Piston Rings from Single-Cylinder Aircraft-Engine Tests

    Science.gov (United States)

    1945-02-01

    found t; a great extent on thn ueed cylinder barrel ( SAE 4140 steel) and to a lesser extent on the top ohrmne- plated ring of the aesembl.yafter it had...on the used cylinder barrel (W 4140 steel) used in the tests and, to a lesser extent, on the used top chrome-platedring of the piston assembly. The

  19. Effect of Cylinder Liner Oil Grooves Shape on Two-Stroke Marine Diesel Engine's Piston Ring Friction Force

    Directory of Open Access Journals (Sweden)

    Salaheldin A. Mohamad

    2015-02-01

    Full Text Available The dimensions, area densities, and geometry of macroscale surface textures may affect the performance of hydrodynamic lubrication interface. Reported in this paper are the investigations of the effect of surface textures bottom shapes on the friction forces between piston ring and cylinder liner for two-stroke marine diesel engine, using numerically generated textures and average Reynolds equation. These textures are on the cylinder liner surface in the form of circumferential oil grooves with different aspect ratios and different area densities. The hydrodynamic pressure distribution is also calculated using Reynolds boundary condition. The results revealed that the bottom shape could positively affect the friction between moving surfaces, as it could provide a microwedge or microstep bearing that tends to enhance the lubrication condition between piston ring and cylinder liner.

  20. Standard test method for ranking resistance of plastics to sliding wear using block-on-ring wear test—cumulative wear method

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2003-01-01

    1.1 This test method covers laboratory procedures for determining the resistance of plastics to sliding wear. The test utilizes a block-on-ring friction and wear testing machine to rank plastics according to their sliding wear characteristics against metals or other solids. 1.2 An important attribute of this test is that it is very flexible. Any material that can be fabricated into, or applied to, blocks and rings can be tested. Thus, the potential materials combinations are endless. In addition, the test can be run with different gaseous atmospheres and elevated temperatures, as desired, to simulate service conditions. 1.3 Wear test results are reported as the volume loss in cubic millimetres for the block and ring. Materials of higher wear resistance will have lower volume loss. 1.4 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only. 1.5 This standard does not purport to address all of the safety concerns, if any, associated with it...

  1. Standard test method for ranking resistance of materials to sliding wear using block-on-ring wear test

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2005-01-01

    1.1 This test method covers laboratory procedures for determining the resistance of materials to sliding wear. The test utilizes a block-on-ring friction and wear testing machine to rank pairs of materials according to their sliding wear characteristics under various conditions. 1.2 An important attribute of this test is that it is very flexible. Any material that can be fabricated into, or applied to, blocks and rings can be tested. Thus, the potential materials combinations are endless. However, the interlaboratory testing has been limited to metals. In addition, the test can be run with various lubricants, liquids, or gaseous atmospheres, as desired, to simulate service conditions. Rotational speed and load can also be varied to better correspond to service requirements. 1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only. Wear test results are reported as the volume loss in cubic millimetres for both the block and ring. Materials...

  2. Ceramics Technology Project database: September 1991 summary report. [Materials for piston ring-cylinder liner for advanced heat/diesel engines

    Energy Technology Data Exchange (ETDEWEB)

    Keyes, B.L.P.

    1992-06-01

    The piston ring-cylinder liner area of the internal combustion engine must withstand very-high-temperature gradients, highly-corrosive environments, and constant friction. Improving the efficiency in the engine requires ring and cylinder liner materials that can survive this abusive environment and lubricants that resist decomposition at elevated temperatures. Wear and friction tests have been done on many material combinations in environments similar to actual use to find the right materials for the situation. This report covers tribology information produced from 1986 through July 1991 by Battelle columbus Laboratories, Caterpillar Inc., and Cummins Engine Company, Inc. for the Ceramic Technology Project (CTP). All data in this report were taken from the project's semiannual and bimonthly progress reports and cover base materials, coatings, and lubricants. The data, including test rig descriptions and material characterizations, are stored in the CTP database and are available to all project participants on request. Objective of this report is to make available the test results from these studies, but not to draw conclusions from these data.

  3. Wear Resistance of Piston Sleeve Made of Layered Material Structure: MMC A356R, Anti-Abrasion Layer and FGM Interface

    Directory of Open Access Journals (Sweden)

    Hernik Szymon

    2016-09-01

    Full Text Available The aim of this paper is the numerical analysis of the one of main part of car engine – piston sleeve. The first example is for piston sleeve made of metal matrix composite (MMC A356R. The second improved material structure is layered. Both of them are comparison to the classical structure of piston sleeve made of Cr-Ni stainless steel. The layered material structure contains the anti-abrasion layer at the inner surface of piston sleeve, where the contact and friction is highest, FGM (functionally graded material interface and the layer of virgin material on the outer surface made of A356R. The complex thermo-elastic model with Archard's condition as a wear law is proposed. The piston sleeve is modelling as a thin walled cylindrical axisymmetric shell. The coupled between the formulation of thermo-elasticity of cylindrical axisymmetric shell and the Archard’s law with functionally changes of local hardness is proposed.

  4. Analysis of optimisation method for a two-stroke piston ring using the Finite Element Method and the Simulated Annealing Method

    Science.gov (United States)

    Kaliszewski, M.; Mazuro, P.

    2016-09-01

    Simulated Annealing Method of optimisation for the sealing piston ring geometry is tested. The aim of optimisation is to develop ring geometry which would exert demanded pressure on a cylinder just while being bended to fit the cylinder. Method of FEM analysis of an arbitrary piston ring geometry is applied in an ANSYS software. The demanded pressure function (basing on formulae presented by A. Iskra) as well as objective function are introduced. Geometry definition constructed by polynomials in radial coordinate system is delivered and discussed. Possible application of Simulated Annealing Method in a piston ring optimisation task is proposed and visualised. Difficulties leading to possible lack of convergence of optimisation are presented. An example of an unsuccessful optimisation performed in APDL is discussed. Possible line of further optimisation improvement is proposed.

  5. Development of wear resistant ceramic coatings for diesel engine components

    Energy Technology Data Exchange (ETDEWEB)

    Haselkorn, M.H. (Caterpillar, Inc., Peoria, IL (United States))

    1992-04-01

    Improved fuel economy and a reduction of emissions can be achieved by insulation of the combustion chamber components to reduce heat rejection. However, insulating the combustion chamber components will also increase the operating temperature of the piston ring/cylinder liner interface from approximately 150{degree}C to over 300{degree}C. Existing ring/liner materials can not withstand these higher operating temperatures and for this reason, new materials need to be developed for this critical tribological interface. The overall goal of this program is the development of piston ring/cylinder liner material pairs which would be able to provide the required friction and wear properties at these more severe operating conditions. More specifically, this program first selected, and then evaluated, potential d/wear resistant coatings which could be applied to either piston rings an or cylinder liners and provide, at 350{degree}C under lubricated conditions, coefficients of friction below 0.1 and wear rates of less than 25 {times} lO{sup {minus}6} mm/hour. The processes selected for applying the candidate wear resistant coatings to piston rings and/or cylinder liners were plasma spraying, chemical vapor, physical vapor and low temperature arc vapor deposition techniques as well as enameling techniques.

  6. Free piston inertia compressor

    Science.gov (United States)

    Richards, W.D.C.; Bilodeau, D.; Marusak, T.; Dutram, L. Jr.; Brady, J.

    A free piston inertia compressor comprises a piston assembly including a connecting rod having pistons on both ends, the cylinder being split into two substantially identical portions by a seal through which the connecting rod passes. Vents in the cylinder wall are provided near the seal to permit gas to escape the cylinder until the piston covers the vent whereupon the remaining gas in the cylinder functions as a gas spring and cushions the piston against impact on the seal. The connecting rod has a central portion of relatively small diameter providing free play of the connecting rod through the seal and end portions of relatively large diameter providing a limited tolerance between the connecting rod and the seal. Finally, the seal comprises a seal ring assembly consisting of a dampener plate, a free floating seal at the center of the dampener plate and a seal retainer plate in one face of the dampener plate.

  7. Carbon/Carbon Pistons for Internal Combustion Engines

    Science.gov (United States)

    Taylor, A. H.

    1986-01-01

    Carbon/carbon piston performs same function as aluminum pistons in reciprocating internal combustion engines while reducing weight and increasing mechanical and thermal efficiencies of engine. Carbon/carbon piston concept features low piston-to-cylinder wall clearance - so low piston rings and skirts unnecessary. Advantages possible by negligible coefficient of thermal expansion of carbon/carbon.

  8. Modeling the lubrication, dynamics, and effects of piston dynamic tilt of twin-land oil control rings in internal combustion engines

    Energy Technology Data Exchange (ETDEWEB)

    Tian, T.; Wong, V.W.

    2000-01-01

    A theoretical model was developed to study the lubrication, friction, dynamics, and oil transport of twin-land oil control rings (TLOCR) in internal combustion engines. A mixed lubrication model with consideration of shear-thinning effects of multigrade oils was used to describe the lubrication between the running surfaces of the two lands and the liner. Oil squeezing and asperity contact were both considered for the interaction between the flanks of the TLOCR and the ring groove. Then, the moments and axial forces from TLOCR/liner lubrication and TLOCR/groove interaction were coupled into the dynamic equations of the TLOCR. Furthermore, effects of piston dynamic tilt were considered in a quasi three-dimensional manner so that the behaviors of the TLOCR at different circumferential location could be studied. As a first step, variation of the third land pressure was neglected. The model predictions were illustrated via an SI engine. One important finding is that around thrust and anti-thrust sides, the difference between the minimum oil film thickness of two lands can be as high as several micrometers due to piston dynamic tilt. As a result, at thrust and anti-thrust sides, significant oil can pass under one land of the TLOCR along the bore, although the other land perfectly seals the bore. Then, the capabilities of the model were further explained by studying the effects of ring tension and torsional resistance on the lubrication and oil transport between the lands and the liner. The effects of oil film thickness on the flanks of the ring groove on the dynamics of the TLOCR were also studied. Friction results show that boundary lubrication contributes significantly to the total friction of the TLOCR.

  9. Thin Layer Activation (TLA) Analysis for Wear Study of Automotive Component

    International Nuclear Information System (INIS)

    Hendiko, E.B.; Nur, M.; Priyono; Suryanto; Silakhuddin

    2000-01-01

    The measurement of surface losses of motor cycle piston ring, the automotive component was carried out. The piston ring is activated by proton beam from cyclotron with energy 12.5 MeV and beam current 1 μA for 30 minutes. The piston ring was installed to the machine and then operated for several times. The method to measured surface loss of piston ring due to wear by concentration, i.e. measured the activity of wear products in the lubricant oil with gamma spectrometry. The measurement the depth layer surface losses used the calibration curve from The Calibration Software Wear, Corrosion And Degradation Monitoring With TLA by Utaja of Iron (Fe) foil was activated by energy proton 12.5 MeV. The surface losses level of piston ring to be 50 hours operated was be 45.0 μm before half-life time correction and 57.0 μm after half-life time correction, its corresponding with count rate lubricant oil activity is 9.04 x 10 -4 μCi before half-life time correction and 1.12 x 10 -3 μCi after half-life time correction. (author)

  10. Pistons and engine testing

    CERN Document Server

    GmbH, Mahle

    2012-01-01

    The ever-increasing demands placed on combustion engines are just as great when it comes to this centerpiece - the piston. Achieving less weight or friction, or even greater wear resistance, requires in-depth knowledge of the processes taking place inside the engine, suitable materials, and appropriate design and machining processes for pistons, including the necessary testing measures. It is no longer possible for professionals in automotive engineering to manage without specific know-how of this kind, whether they work in the field of design, development, testing, or maintenance. This techni

  11. Development of wear resistant ceramic coatings for diesel engine components. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Haselkorn, M.H. [Caterpillar, Inc., Peoria, IL (United States)

    1992-04-01

    Improved fuel economy and a reduction of emissions can be achieved by insulation of the combustion chamber components to reduce heat rejection. However, insulating the combustion chamber components will also increase the operating temperature of the piston ring/cylinder liner interface from approximately 150{degree}C to over 300{degree}C. Existing ring/liner materials can not withstand these higher operating temperatures and for this reason, new materials need to be developed for this critical tribological interface. The overall goal of this program is the development of piston ring/cylinder liner material pairs which would be able to provide the required friction and wear properties at these more severe operating conditions. More specifically, this program first selected, and then evaluated, potential d/wear resistant coatings which could be applied to either piston rings an or cylinder liners and provide, at 350{degree}C under lubricated conditions, coefficients of friction below 0.1 and wear rates of less than 25 {times} lO{sup {minus}6} mm/hour. The processes selected for applying the candidate wear resistant coatings to piston rings and/or cylinder liners were plasma spraying, chemical vapor, physical vapor and low temperature arc vapor deposition techniques as well as enameling techniques.

  12. Pistons and engine testing

    CERN Document Server

    2016-01-01

    The ever-increasing demands placed on combustion engines are just as great when it comes to this centerpiece—the piston. Achieving less weight or friction, or even greater wear resistance, requires in-depth knowledge of the processes taking place inside the engine, suitable materials, and appropriate design and manufacturing processes for pistons, including the necessary testing measures. It is no longer possible for professionals in automotive engineering to manage without specific expertise of this kind, whether they work in the field of design, development, testing, or maintenance. This technical book answers these questions in detail and in a very clear and comprehensible way. In this second, revised edition, every chapter has been revised and expanded. The chapter on “Engine testing”, for example, now include extensive results in the area of friction power loss measurement and lube oil consumption measurement. Contents Piston function, requirements, and types Design guidelines Simulation of the ope...

  13. Piston-Skirt Lubrication System For Compressor

    Science.gov (United States)

    Schroeder, Edgar C.; Burzynski, Marion, Jr.

    1994-01-01

    Piston-skirt lubrication system provides steady supply of oil to piston rings of gas compressor. No need for oil-filled crankcase or external oil pump. Instead, part of each piston acts as its own oil pump circulating oil from reservoir. Annular space at bottom of piston and cylinder constitutes working volume of small oil pump. Depending on application, reservoir open to atmosphere, or sealed and pressurized in bellows to prevent contact between oil and atmosphere. Filter removes particles worn away from piston rings and cylinder wall during normal operation.

  14. Analysis of the piston ring/liner oil film development during warm-up for an SI-engine

    DEFF Research Database (Denmark)

    Frølund, Kent; Schramm, Jesper; Tian, T.

    2001-01-01

    A one-dimensional ring-pack lubrication model developed at MIT is applied to simulate the oil film behavior during the warm-up period of a Kohler spark ignition engine. This is done by making assumptions for the evolution of the ail temperatures during warm-up and that the oil control ring during...

  15. Studies on the friction and wear properties of synchronizer rings and gear cones; Shinkuro kiko ni okeru masatsu mamo tokusei ni kansuru kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Hayashi, K; Kunoki, T [COSMO Research Institute, Tokyo (Japan)

    1997-10-01

    The influence of materials of synchronizer rings, automotive gear oils and sulfur-phosphorus EP additives on the friction and wear properties of synchromesh system was studied by using a synchromesh friction tester. As a result, the durability was decreased by using the synchronizer ring made of copper alloys. The initial friction performance estimated by using the synchronizer ring made of resin have influence on EP additives, in particular some kinds of phosphorus type additives. 3 refs., 12 figs.

  16. Double bowl piston

    Science.gov (United States)

    Meffert, Darrel Henry; Urven, Jr., Roger Leroy; Brown, Cory Andrew; Runge, Mark Harold

    2007-03-06

    A piston for an internal combustion engine is disclosed. The piston has a piston crown with a face having an interior annular edge. The piston also has first piston bowl recessed within the face of the piston crown. The first piston bowl has a bottom surface and an outer wall. A line extending from the interior annular edge of the face and tangent with the outer wall forms an interior angle greater than 90 degrees with the face of the piston. The piston also has a second piston bowl that is centrally located and has an upper edge located below a face of the piston crown.

  17. The effect of surface roughness on the performances of liner-piston ...

    African Journals Online (AJOL)

    The effect of surface roughness on the performances of liner-piston ring contact in internal combustion engine. ... The surface roughness between the liner and the piston rings, plays an ... EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT

  18. Single-piston alternative to Stirling engines

    International Nuclear Information System (INIS)

    Glushenkov, Maxim; Sprenkeler, Martin; Kronberg, Alexander; Kirillov, Valeriy

    2012-01-01

    Highlights: ► Thermodynamic analysis of an unconventional heat engine. ► The engine has a number of advantages compared to state-of-the-art Stirling engines. ► The engine can to be fuelled with “difficult” fuels and used for micro-CHP systems. ► The energy conversion efficiency can be as high as 40–50%. ► A prototype of the engine was demonstrated. -- Abstract: Thermodynamic analysis of an unconventional heat engine was performed. The engine studied has a number of advantages compared to state-of-the-art Stirling engines. The main advantage of the engine proposed is its simplicity. A power piston is integral with a displacer and a heat regenerator. It allows solving the problem of the high-temperature sealing of the piston and the displacer typical of all types of Stirling engines. In addition the design proposed provides ideal use of the displacer volume eliminating heat losses from outside gas circuit. Both strokes of the piston are working ones in contrary to any other types of piston engines. The engine can be considered as maintenance-free as it has no piston rings or any other rubbing components requiring lubrication. The only seal is contactless and wear free. It is located in the cold part of the cylinder. As a result the leakage rate in operation can be one-two orders of magnitude as small as that in Stirling engines. Balancing of the engine is much easy compared to Stirling engines with two reciprocating masses because of the only moving part inside the engine cylinder. The engine suits ideally to be fuelled with “difficult” fuels such as bio oil and can be used as a prime mover for micro-CHP systems. The thermodynamic model developed incorporates non-ideal features of the cycle, such as specific regenerator efficiency, dead volumes and other geometrical parameters of the engine. The model shows that the energy efficiency is highly sensitive to regenerator performance. For realistic geometric and operating parameters and the

  19. Application of charged particle activation for testing machine part wear

    International Nuclear Information System (INIS)

    Kosimova, M.; Tendera, P.

    1985-01-01

    The results of application of the charge particle activation method to investigate machine part wear are presented. Study of radionuclide activity and yield has been carried out at the U-120M isochronous cyclotron by means of the method of iron foil piles from 20 to 100 μm in thick. Protons and deuterons have been used. Wear measurement is based on determination of wear particle activity in a butyric medium. An example of the results of a bench test of activated piston rings and cylinder liner of the engine for trucks is given. The method of surface activation is shown to be acceptable for studying machine part wear under the regular service conditions, especially on the stage of the primary investigations and development, when sampling structural materials and estimating different lubricating oil applicability

  20. Millisecond bearing wear

    International Nuclear Information System (INIS)

    Blatchley, C.; Sioshansi, P.

    1987-01-01

    Radionuclides have been widely used for many purposes in medicine, metals, transportation, manufacturing and research. Approximately 200 artificially produced nuclides are commercially available from reactors or accelerator sources. Another 400 or so have properties which may make them useful if satisfactory methods of production can be developed. One of the most economically important industrial applications of radionuclides has been in wear measurement and condition monitoring in reciprocating engines. The general techniques developed for this purpose have also been applied in a number of other areas besides engine or lubrication studies. The wear of floor wax applied to linoleum, for example, has been measured by mixing shortlived radionuclides in the wax. In those applications where the material is tagged and then followed, the radionuclides are termed ''tracers,'' similar to the medical tracer materials used to measure uptake or metabolism of biologically active chemicals in the body. The alternate function for the radionuclides is to act as ''markers'' which indicate the amount of material which is remaining at the location of the original activation. Both approaches require that the debris removed from the surface must be carried away from the original site. The first application of radioactive tracers as a diagnostic tool in engines was in 1949. In this technique, an entire wearing part such as a piston ring or gear was first exposed to neutrons in a nuclear reactor. This caused the entire volume of the part to become radioactive. The part was next installed and exposed to wear in the operating engine. Detectors placed near the oil line, an oil filter or a sediment trap then determined the amount of debris from the part by counting the gamma rays escaping from the debris

  1. Reciprocating piston pump system with screw drive

    Science.gov (United States)

    Perkins, Gerald S. (Inventor); Moore, Nicholas R. (Inventor)

    1981-01-01

    A pump system of the reciprocating piston type is described, which facilitates direct motor drive and cylinder sealing. A threaded middle potion of the piston is engaged by a nut connected to rotate with the rotor of an electric motor, in a manner that minimizes loading on the rotor by the use of a coupling that transmits torque to the nut but permits it to shift axially and radially with respect to the rotor. The nut has a threaded hydrostatic bearing for engaging the threaded piston portion, with an oil-carrying groove in the nut being interrupted. A fluid emitting seal located at the entrance to each cylinder, can serve to center the piston within the cylinder, wash the piston, and to aid in sealing. The piston can have a long stroke to diameter ratio to minimize reciprocations and wear on valves at high pressures. The voltage applied to the motor can be reversed prior to the piston reaching the end of its stroke, to permit pressure on the piston to aid in reversing the motor.

  2. Piston rod seal for a Stirling engine

    Science.gov (United States)

    Shapiro, Wilbur

    1984-01-01

    In a piston rod seal for a Stirling engine, a hydrostatic bearing and differential pressure regulating valve are utilized to provide for a low pressure differential across a rubbing seal between the hydrogen and oil so as to reduce wear on the seal.

  3. Analytical and experimental investigation of ringless-piston concept. Interim report, September 1986-December 1987

    Energy Technology Data Exchange (ETDEWEB)

    Dickey, D.W.; Wood, C.D.

    1987-12-01

    The purpose of this project was to analytically and experimentally investigate the concept of a ringless-piston internal-combustion engine. A joint objective was to design, build, and test a ringless piston to improve ringless-piston engine performance. A computer model was developed to predict ringed and ringless-piston engine performance. Experimental performance data were then collected by operating a small, liquid-cooled, two-stroke gasoline engine with and without the piston ring on the stock aluminum and Southwest Research Institute prototype steel piston. The experimental performance data were then compared with the results of the computer model. The results showed that a piston engine can operate without piston rings.

  4. Piston-rotaxanes as molecular shock absorbers.

    Science.gov (United States)

    Sevick, E M; Williams, D R M

    2010-04-20

    We describe the thermomechanical response of a new molecular system that behaves as a shock absorber. The system consists of a rodlike rotaxane connected to a piston and tethered to a surface. The response of this system is dominated by the translational entropy of the rotaxane rings and can be calculated exactly. The force laws are contrasted with those for a rigid rod and a polymer. In some cases, the rotaxanes undergo a sudden transition to a tilted state when compressed. These piston-rotaxanes provide a potential motif for the design of a new class of materials with a novel thermomechanical response.

  5. Limitation of Piston Centre Shift in Free Piston Stirling Engines

    Energy Technology Data Exchange (ETDEWEB)

    Van der Woude, R.R. [ECN Energy in the Built Environment and Networks, Petten (Netherlands)

    2006-09-15

    Piston centre shift is one of the phenomena setting Free Piston engines apart from traditional kinematic engines. In kinematic engines the piston centre position is determined by the design of the engine's internal mechanisms. In Free Piston engines however, the piston's mid-stroke position is determined by the balance of forces acting on the piston, in particular flexure and gas pressure forces. As a result, a mean pressure difference across the piston emerging during engine operation will cause the piston mid-stroke position to shift away from the geometrical centre. This process will continue until a new balance is reached with the flexure forces counteracting the new mean pressure balance. Yet, before the new equilibrium is reached, the resulting piston centre shift may have grown to such an extent that piston overstrokes have become inevitable. In order to limit piston centre shift and prevent piston overstrokes, several solutions have been proposed in the past. Popular solutions include ingenious mechanisms to vent gas between the spaces separated by the piston, in an attempt to limit the pressure difference. Enatec however has adopted a different approach by applying a precisely determined clearance between the piston and cylinder. With the right shape the clearance effectively limits the mean pressure difference across the piston and therefore limits the extent of the piston centre drift. Taking benefit of tightly controlled tolerances of both piston and cylinder, Enatec has demonstrated the effectiveness of this simple concept in series produced engines.

  6. Cooled spool piston compressor

    Science.gov (United States)

    Morris, Brian G. (Inventor)

    1993-01-01

    A hydraulically powered gas compressor receives low pressure gas and outputs a high pressure gas. The housing of the compressor defines a cylinder with a center chamber having a cross-sectional area less than the cross-sectional area of a left end chamber and a right end chamber, and a spool-type piston assembly is movable within the cylinder and includes a left end closure, a right end closure, and a center body that are in sealing engagement with the respective cylinder walls as the piston reciprocates. First and second annual compression chambers are provided between the piston enclosures and center housing portion of the compressor, thereby minimizing the spacing between the core gas and a cooled surface of the compressor. Restricted flow passageways are provided in the piston closure members and a path is provided in the central body of the piston assembly, such that hydraulic fluid flows through the piston assembly to cool the piston assembly during its operation. The compressor of the present invention may be easily adapted for a particular application, and is capable of generating high gas pressures while maintaining both the compressed gas and the compressor components within acceptable temperature limits.

  7. Analytical and experimental investigation of ringless-piston concept. Final report, September 1986-November 1987

    Energy Technology Data Exchange (ETDEWEB)

    Dickey, D.W.; Wood, C.D.

    1988-03-01

    The purpose of this project was to analytically and experimentally investigate the concept of a ringless-piston internal combustion engine. A joint objective was to design, build, and test a ringless piston to improve ringless piston engine performance. A computer model was developed to predict ringed and ringless piston engine performance. Experimental performance data were then collected by operating a small, liquid-cooled, two-stroke gasoline engine with and without the piston ring on the stock aluminum and Southwest Research Institute prototype steel piston. The experimental performance data were then compared with the results of the computer model. The results showed that a piston engine can operate without piston rings. Ringless-piston engine power and efficiency were found to be defined by the expression C/NBS, where C = piston-to-bore diametrical clearance, N = engine speed in rpm, B = engine bore, and S = engine stroke. There was good agreement between predicted and measured performance reperformance can be improved by using piston and liner materials that have similar coefficients of thermal expansion.

  8. The development and testing of ceramic components in piston engines. Final report

    Energy Technology Data Exchange (ETDEWEB)

    McEntire, B.J. [Norton Co., Northboro, MA (United States). Advanced Ceramics Div.; Willis, R.W.; Southam, R.E. [TRW, Inc., Cleveland, OH (United States)

    1994-10-01

    Within the past 10--15 years, ceramic hardware has been fabricated and tested in a number of piston engine applications including valves, piston pins, roller followers, tappet shims, and other wear components. It has been shown that, with proper design and installation, ceramics improve performance, fuel economy, and wear and corrosion resistance. These results have been obtained using rig and road tests on both stock and race engines. Selected summaries of these tests are presented in this review paper.

  9. Simulations geometric structures of the stepped profile bearing surface of the piston

    Directory of Open Access Journals (Sweden)

    Wroblewski Emil

    2017-01-01

    Full Text Available The main node piston-pin-piston rings are most responsible for the formation of mechanical losses. It is advisable to reduce friction losses in the piston-cylinder group lead to an increase in the overall efficiency of the engine and thus reduce the fuel consumption. The method to reduce the area covered by the oil film is a modification of the bearing surface of the piston by adjusting the profile. In this paper the results of simulation for the stepped microgeometry piston bearing surface are presented.

  10. Development of high pressure-high vacuum-high conductance piston valve for gas-filled radiation detectors

    International Nuclear Information System (INIS)

    Prasad, D N; Ayyappan, R; Kamble, L P; Singh, J P; Muralikrishna, L V; Alex, M; Balagi, V; Mukhopadhyay, P K

    2008-01-01

    Gas-filled radiation detectors need gas filling at pressures that range from few cms of mercury to as high as 25kg/cm 2 at room temperature. Before gas-filling these detectors require evacuation to a vacuum of the order of ∼1 x 10 -5 mbar. For these operations of evacuation and gas filling a system consisting of a vacuum pump with a high vacuum gauge, gas cylinder with a pressure gauge and a valve is used. The valve has to meet the three requirements of compatibility with high-pressure and high vacuum and high conductance. A piston valve suitable for the evacuation and gas filling of radiation detectors has been designed and fabricated to meet the above requirements. The stainless steel body (80mmx160mm overall dimensions) valve with a piston arrangement has a 1/2 inch inlet/outlet opening, neoprene/viton O-ring at piston face and diameter for sealing and a knob for opening and closing the valve. The piston movement mechanism is designed to have minimum wear of sealing O-rings. The valve has been hydrostatic pressure tested up to 75bars and has Helium leak rate of less than 9.6x10 -9 m bar ltr/sec in vacuum mode and 2x10 -7 mbar ltr/sec in pressure mode. As compared to a commercial diaphragm valve, which needed 3 hours to evacuate a 7 litre chamber to 2.5x10 -5 mbar, the new valve achieved vacuum 7.4x10 -6 mbar in the same time under the same conditions

  11. Wear mechanisms of toughened zirconias

    International Nuclear Information System (INIS)

    Becker, P.C.; Libsch, T.A.; Rhee, S.K.

    1985-01-01

    The dry friction and wear behavior of toughened zirconias against hardened steel was studied using the falex ring and block technique. Three experimental ZrO 2 -Y 2 O 3 ceramics and two commerical ZrO 2 -MgO ceramics were investigated. Each ceramic was tested at 500 and 2000 rpm at normal loads in the range 2.3 to 40.8 kg. Significant trends in the friction and wear data were found correlating composition, test speeds, and loads. Microstructural examination of the ring, ceramic block, and wear debris has shown that the wear process is very complex and incorporates a number of mechanisms

  12. Features of Load and Wear of Main Propulsion Devices on Sea-Going Ships with Piston Combustion Engines and Their Impact on Changes in Technical States of the Systems

    Directory of Open Access Journals (Sweden)

    Girtler Jerzy

    2017-12-01

    Full Text Available The paper presents the specificity of operation of propulsion systems of seagoing ships which causes the need to control the load on them, especially on their engines called main engines. The characteristics of the load on the propulsion systems, especially on the main engines as well as on the shaft lines and propellers driven by the engines, along with the process of wear in tribological joints (sliding tribological systems of the machines have been described herein. Using examples of typical types of wear (both linear and volumetric for the tribological systems of this sort, interpretation of states of their wear has been provided with regards to the wear levels defined as acceptable, unacceptable and catastrophic. The following hypotheses have been formulated: 1 hypothesis explaining necessity to consider the loads on the systems under operation as stochastic processes; 2 hypothesis explaining a possibility of considering the processes as stationary; and 3 hypothesis explaining why it can be assumed that a given technical state of any tribological system can be considered as dependent only on the directly preceding state and stochastically independent of the states that existed earlier. Accepting the hypotheses as true, a four-state continuous-time semi-Markov process has been proposed in the form of a model of changes in condition of a propulsion system (PS of any ship. The model includes the most significant states affecting safety of a ship at sea, such as: s0 - PS ability state, s1 - PS disability state due to damage to the main engine (ME, s2 - PS disability state due to damage to the shaft line (SL and s3 - PS disability state due to damage to the propeller (P. Probability of occurrence (changes of the states has also been demonstrated.

  13. OIL SLUGS FOR PRODUCTION OF PISTON RING

    Directory of Open Access Journals (Sweden)

    V. F. Bevza

    2008-01-01

    Full Text Available The developed technological process of continuously cyclic casting by frosting allows to receive high-quality hollow cylindrical slugs of cast iron for production of critical parts. 

  14. Numerical Simulation of Piston Ring Lubrication

    DEFF Research Database (Denmark)

    Felter, Christian Lotz

    2006-01-01

    on solids and the equilibrium of stresses on the free surface. It is assumed that the surrounding gas phase has zero viscosity. Surface tension can be included in the model if necessary. The contact point where the three phases solid, liquid, and gas intersect is updated based on the velocity of the solid...

  15. Free-piston engine

    Science.gov (United States)

    Van Blarigan, Peter

    2001-01-01

    A combustion system which can utilize high compression ratios, short burn durations, and homogeneous fuel/air mixtures in conjunction with low equivalence ratios. In particular, a free-piston, two-stroke autoignition internal combustion engine including an electrical generator having a linear alternator with a double-ended free piston that oscillates inside a closed cylinder is provided. Fuel and air are introduced in a two-stroke cycle fashion on each end, where the cylinder charge is compressed to the point of autoignition without spark plugs. The piston is driven in an oscillating motion as combustion occurs successively on each end. This leads to rapid combustion at almost constant volume for any fuel/air equivalence ratio mixture at very high compression ratios. The engine is characterized by high thermal efficiency and low NO.sub.x emissions. The engine is particularly suited for generating electrical current in a hybrid automobile.

  16. Coefficient of friction and wear rate effects of different composite nanolubricant concentrations on Aluminium 2024 plate

    Science.gov (United States)

    Zawawi, N. N. M.; Azmi, W. H.; Redhwan, A. A. M.; Sharif, M. Z.

    2017-10-01

    Wear of sliding parts and operational machine consistency enhancement can be avoided with good lubrication. Lubrication reduce wear between two contacting and sliding surfaces and decrease the frictional power losses in compressor. The coefficient of friction and wear rate effects study were carried out to measure the friction and anti-wear abilities of Al2O3-SiO2 composite nanolubricants a new type of compressor lubricant to enhanced the compressor performances. The tribology test rig employing reciprocating test conditions to replicate a piston ring contact in the compressor was used to measure the coefficient of friction and wear rate. Coefficient of friction and wear rate effects of different Al2O3-SiO2/PAG composite nanolubricants of Aluminium 2024 plate for 10-kg load at different speed were investigated. Al2O3 and SiO2 nanoparticles were dispersed in the Polyalkylene Glycol (PAG 46) lubricant using two-steps method of preparation. The result shows that the coefficient friction and wear rate of composite nanolubricants decreased compared to pure lubricant. The maximum reduction achievement for friction of coefficient and wear rate by Al2O3-SiO2 composite nanolubricants by 4.78% and 12.96% with 0.06% volume concentration. Therefore, 0.06% volume concentration is selected as the most enhanced composite nanolubricants with effective coefficient of friction and wear rate reduction compared to other volume concentrations. Thus, it is recommended to be used as the compressor lubrication to enhanced compressor performances.

  17. Non-adiabatic pumping in an oscillating-piston model

    Science.gov (United States)

    Chuchem, Maya; Dittrich, Thomas; Cohen, Doron

    2012-05-01

    We consider the prototypical "piston pump" operating on a ring, where a circulating current is induced by means of an AC driving. This can be regarded as a generalized Fermi-Ulam model, incorporating a finite-height moving wall (piston) and non-trivial topology (ring). The amount of particles transported per cycle is determined by a layered structure of phase space. Each layer is characterized by a different drift velocity. We discuss the differences compared with the adiabatic and Boltzmann pictures, and highlight the significance of the "diabatic" contribution that might lead to a counter-stirring effect.

  18. Cooled-Spool Piston Compressor

    Science.gov (United States)

    Morris, Brian G.

    1994-01-01

    Proposed cooled-spool piston compressor driven by hydraulic power and features internal cooling of piston by flowing hydraulic fluid to limit temperature of compressed gas. Provides sufficient cooling for higher compression ratios or reactive gases. Unlike conventional piston compressors, all parts of compressed gas lie at all times within relatively short distance of cooled surface so that gas cooled more effectively.

  19. Dry piston coal feeder

    Science.gov (United States)

    Hathaway, Thomas J.; Bell, Jr., Harold S.

    1979-01-01

    This invention provides a solids feeder for feeding dry coal to a pressurized gasifier at elevated temperatures substantially without losing gas from the gasifier by providing a lock having a double-acting piston that feeds the coals into the gasifier, traps the gas from escaping, and expels the trapped gas back into the gasifier.

  20. A Piston-Rotaxane with Two Potential Stripes: Force Transitions and Yield Stresses

    Directory of Open Access Journals (Sweden)

    Edith M. Sevick

    2013-10-01

    Full Text Available We examine a rod piston-rotaxane system, where the positions of several mobile rings on the axle are controlled by an external force acting on one of the rings. This allows us to access the translational entropy of the rings. For a simple rotaxane molecule with an axle that has uniform ring-axle interactions along its length, the molecule behaves like a miniature piston filled with a one-dimensional ideal gas. We then examine the effect of two stripes on the axle, having different ring-axle interactions with the mobile rings, so that one section is of high energy (repulsive for the rings and another section is of lower energy (or attractive. This kind of rotaxane can exhibit rapid changes in displacement or force, and in particular, this molecule can exhibit a yield stress in which the piston suddenly compresses under a small increase in the applied force.

  1. Interring Gas Dynamic Analysis of Piston in a Diesel Engine considering the Thermal Effect

    Directory of Open Access Journals (Sweden)

    Wanyou Li

    2015-01-01

    Full Text Available Understanding the interaction between ring dynamics and gas transport in ring pack systems is crucial and needs to be imperatively studied. The present work features detailed interring gas dynamics of piston ring pack behavior in internal combustion engines. The model is developed for a ring pack with four rings. The dynamics of ring pack are simulated. Due to the fact that small changes in geometry of the grooves and lands would have a significant impact on the interring gas dynamics, the thermal deformation of piston has been considered during the ring pack motion analysis in this study. In order to get the temperature distribution of piston head more quickly and accurately, an efficient method utilizing the concept of inverse heat conduction is presented. Moreover, a sensitive analysis based on the analysis of partial regression coefficients is presented to investigate the effect of groove parameters on blowby.

  2. Wear rate quantifying in real-time using the charged particle surface activation

    Science.gov (United States)

    Alexandreanu, B.; Popa-Simil, L.; Voiculescu, D.; Racolta, P. M.

    1997-02-01

    Surface activation, commonly known as Thin Layer Activation (TLA), is currently employed in over 30 accelerator laboratories around the world for wear and/or corrosion monitoring in industrial plants [1-6]. TLA was primarily designed and developed to meet requirements of potential industrial partners, in order to transfer this technique from research to industry. The method consists of accelerated ion bombardment of a surface of interest, e.g., a machine part subjected to wear. Loss of material owing to wear, erosive corrosion or abrasion is characterized by monitoring the resultant changes in radioactivity. In principle, depending upon the case at hand, one may choose to measure either the remnant activity of the component of interest or to monitor the activity of the debris. For applications of the second type, especially when a lubricating agent is involved, dedicated installations have been constructed and adapted to an engine or a tribological testing stand in order to assure oil circulation around an externally placed detection gauge. This way, the wear particles suspended in the lubricant can be detected and the material loss rates quantified in real time. Moreover, in specific cases, such as the one presented in this paper, remnant activity measurements prove to be useful tools for complementary results. This paper provides a detailed presentation of such a case: in situ resistance-to-wear testing of two types of piston rings.

  3. Spherical Casimir pistons

    Energy Technology Data Exchange (ETDEWEB)

    Dowker, J S, E-mail: dowker@man.ac.uk [Theory Group, School of Physics and Astronomy, University of Manchester, Manchester (United Kingdom)

    2011-08-07

    A piston is introduced into a spherical lune Casimir cavity turning it into two adjacent lunes separated by the (hemispherical) piston. On the basis of zeta-function regularization, the vacuum energy of the arrangement is finite for conformal propagation in spacetime. For even spheres this energy is independent of the angle of the lune. For odd dimensions it is shown that for all Neumann, or all Dirichlet, boundary conditions the piston is repelled or attracted by the nearest wall if d = 3, 7, ... or if d = 1, 5, ... , respectively. For hybrid N-D conditions these requirements are switched. If a mass is added, divergences arise which render the model suspect. The analysis, however, is relatively straightforward and involves the Barnes zeta function. The extension to finite temperatures is made and it is shown that for the 3, 7, ... series of odd spheres, the repulsion by the walls continues but that, above a certain temperature, the free energy acquires two minima symmetrically placed about the midpoint.

  4. Spherical Casimir pistons

    International Nuclear Information System (INIS)

    Dowker, J S

    2011-01-01

    A piston is introduced into a spherical lune Casimir cavity turning it into two adjacent lunes separated by the (hemispherical) piston. On the basis of zeta-function regularization, the vacuum energy of the arrangement is finite for conformal propagation in spacetime. For even spheres this energy is independent of the angle of the lune. For odd dimensions it is shown that for all Neumann, or all Dirichlet, boundary conditions the piston is repelled or attracted by the nearest wall if d = 3, 7, ... or if d = 1, 5, ... , respectively. For hybrid N-D conditions these requirements are switched. If a mass is added, divergences arise which render the model suspect. The analysis, however, is relatively straightforward and involves the Barnes zeta function. The extension to finite temperatures is made and it is shown that for the 3, 7, ... series of odd spheres, the repulsion by the walls continues but that, above a certain temperature, the free energy acquires two minima symmetrically placed about the midpoint.

  5. [Lubricant-free piston compressors for mechanized medical instruments].

    Science.gov (United States)

    Sabitov, V Kh; Repin, V A; Kil'kinov, A A

    1988-01-01

    Piston compressor without lubrication with air blow to packing rings by plunger, disposed in subpiston space, is recommended as the basic scheme of construction of a power supply unit for medical pneumatic tooling. The construction reduces a leak of the compressive medium, increasing the efficiency of a compressor and seal reliability.

  6. 49 CFR 229.55 - Piston travel.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Piston travel. 229.55 Section 229.55... Piston travel. (a) Brake cylinder piston travel shall be sufficient to provide brake shoe clearance when... piston travel may not exceed 11/2 inches less than the total possible piston travel. The total possible...

  7. Free-piston cutting machine

    Science.gov (United States)

    Ciccarelli, Gaby; Subudhi, Manomohan; Hall, Robert E.

    2000-01-01

    A cutting machine includes a gun barrel for receiving a projectile. A compression tube is disposed in flow communication with the barrel and includes a piston therein. A reservoir is disposed in flow communication with the tube and receives a first gas under pressure. A second gas fills the compression tube on a front face of the piston. And, the pressurized first gas is discharged into the tube on a back face of the piston to accelerate the piston through the tube for compressing the second gas, and in turn launching the projectile through the barrel to impact a workpiece.

  8. Thermal Fluctuations in Casimir Pistons

    Science.gov (United States)

    Lomnitz, M.; Villarreal, C.

    2012-07-01

    We present analytical and simple expressions to determine the free energy, internal energy, entropy, as well as the pressure acting at the interface of a perfectly conducting rectangular Casimir piston. We show that infrared divergencies linear in temperature become cancelled within the piston configuration, and show a continuous behavior consistent with intuitive expectations.

  9. A new strategy for wear and corrosion measurements using ion beam based techniques

    International Nuclear Information System (INIS)

    Dudu, D.; Popa, V.; Racolta, P.M.; Voiculescu, Dana

    2001-01-01

    An efficient and precise method for wear testing is Thin Layer Activation (TLA), which is based on the production of a thin layer of radioisotopes in the component surface by bombardment with a charged particle beam. These radioisotopes decay by emitting a characteristic gamma radiation that can be detected with thallium activated sodium iodide NaI(Tl) detectors. Since the material loss due to wear or corrosion is directly proportional to the loss in radioactivity of the activated surface, the wear/corrosion can be monitored in real time. Alternatively, the increase of the activity of the removed material debris collected in an oil bath of engine or in a filter also gives a measure of wear. The application of TLA and UTLA (ultra TLA - by recoil implantation) techniques presupposes establishing the optimum working and measuring conditions for the following steps: irradiation, post irradiation, and 'in situ' measurements. Having in view the diversity of components subjected to wear or corrosion to TLA-based investigations, dedicated beam lines for in-air or vacuum irradiation and translating/rotating target holders were developed by the U-120 Cyclotron of IFIN-HH. The modified IFIN-HH U-120 cyclotron from Bucharest is a classical variable energy machine that can accelerate protons up to 14 MeV, deuterons up to 13.5 MeV, and alpha particles up to 27 MeV. At this machine, TLA has mainly been used for studies of various parts of running machines on test benches such as piston - rings and linear cylinders. Also lubricant characterization studies were conducted here. The main advantage of TLA compared to conventional techniques for wear measurements is its ability to perform continuous in situ wear measurements of engine components, such as cylinder liners and piston rings, without the need to dismantle the components investigated. In addition high wear sensitivity and resolution of wear down to nano meters dimensions is guaranteed. Although the level of activity used in

  10. Piston engines and gas turbines

    Energy Technology Data Exchange (ETDEWEB)

    Shmelev, V.M.

    1999-07-01

    The concept of a free piston engine utilising overlean fuel-air mixture and using entropy rising compression is examined. An analysis was made of engine operation. The high compression parameters can be reached under compression of the mixture by a free piston to ensure the space heat release occurs from the mixture is not capable to self-combustion. It is shown that two stage entropy rising compression allows to reduce the final compression pressure and increase a perfomance of the piston engine. (orig.)

  11. 49 CFR 230.76 - Piston travel.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Piston travel. 230.76 Section 230.76... Tenders Brake and Signal Equipment § 230.76 Piston travel. (a) Minimum piston travel. The minimum piston travel shall be sufficient to provide proper brake shoe clearance when the brakes are released. (b...

  12. Dynamically balanced, hydraulically driven compressor/pump apparatus for resonant free piston Stirling engines

    Science.gov (United States)

    Corey, John A.

    1984-05-29

    A compressor, pump, or alternator apparatus is designed for use with a resonant free piston Stirling engine so as to isolate apparatus fluid from the periodically pressurized working fluid of the Stirling engine. The apparatus housing has a first side closed by a power coupling flexible diaphragm (the engine working member) and a second side closed by a flexible diaphragm gas spring. A reciprocally movable piston is disposed in a transverse cylinder in the housing and moves substantially at right angles relative to the flexible diaphragms. An incompressible fluid fills the housing which is divided into two separate chambers by suitable ports. One chamber provides fluid coupling between the power diaphragm of the RFPSE and the piston and the second chamber provides fluid coupling between the gas spring diaphragm and the opposite side of the piston. The working members of a gas compressor, pump, or alternator are driven by the piston. Sealing and wearing parts of the apparatus are mounted at the external ends of the transverse cylinder in a double acting arrangement for accessibility. An annular counterweight is mounted externally of the reciprocally movable piston and is driven by incompressible fluid coupling in a direction opposite to the piston so as to damp out transverse vibrations.

  13. Study on the engine oil's wear based on the flash point

    Science.gov (United States)

    Niculescu, R.; Iorga-Simăn, V.; Trică, A.; Clenci, A.

    2016-08-01

    Increasing energy performance of internal combustion engines is largely influenced by frictional forces that arise between moving parts. Thus, in this respect, the nature and quality of the engine oil used is an important factor. Equally important is the effect of various engine injection strategies upon the oil quality. In other words, it's of utmost importance to maintain the quality of engine oil during engine's operation. Oil dilution is one of the most common causes that lead to its wear, creating lubrication problems. Moreover, at low temperatures operating conditions, the oil dilution with diesel fuel produces wax. When starting the engine, this may lead to lubrication deficiencies and even oil starvation with negative consequences on the engine mechanism parts wear (piston, rings and cylinders) but also crankcase bearings wear.Engine oil dilution with diesel fuel have several causes: wear of rings and/or injectors, late post-injection strategy for the sake of particulate filter regeneration, etc.This paper presents a study on the degree of deterioration of engine oils as a result of dilution with diesel fuel. The analysed oils used for this study were taken from various models of engines equipped with diesel particulate filter. The assessment is based on the determination of oil flash point and dilution degree using the apparatus Eraflash produced by Eralytics, Austria. Eraflash measurement is directly under the latest and safest standards ASTM D6450 & D7094), which are in excellent correlation with ASTM D93 Pensky - Martens ASTM D56 TAG methods; it uses the Continuous Closed Cup method for finding the Flash Point (CCCFP).

  14. Cast Hybrid Composites Designated for Air Compressor Pistons

    Directory of Open Access Journals (Sweden)

    Dolata A. J.

    2016-06-01

    Full Text Available The main purpose of the investigations was to develop the phase composition of the composite assuming that the component selection criterion will be the formability of piston work surfaces during the machining. Wear resistance under the friction conditions was assumed as the additional parameter for the assessment of composite material. In the study were used AlSi7Mg/SiC+Cg and AlSi7Mg/SiC+GR hybrid composites prepared by the stir casting method.

  15. A Linear Electromagnetic Piston Pump

    Science.gov (United States)

    Hogan, Paul H.

    Advancements in mobile hydraulics for human-scale applications have increased demand for a compact hydraulic power supply. Conventional designs couple a rotating electric motor to a hydraulic pump, which increases the package volume and requires several energy conversions. This thesis investigates the use of a free piston as the moving element in a linear motor to eliminate multiple energy conversions and decrease the overall package volume. A coupled model used a quasi-static magnetic equivalent circuit to calculate the motor inductance and the electromagnetic force acting on the piston. The force was an input to a time domain model to evaluate the mechanical and pressure dynamics. The magnetic circuit model was validated with finite element analysis and an experimental prototype linear motor. The coupled model was optimized using a multi-objective genetic algorithm to explore the parameter space and maximize power density and efficiency. An experimental prototype linear pump coupled pistons to an off-the-shelf linear motor to validate the mechanical and pressure dynamics models. The magnetic circuit force calculation agreed within 3% of finite element analysis, and within 8% of experimental data from the unoptimized prototype linear motor. The optimized motor geometry also had good agreement with FEA; at zero piston displacement, the magnetic circuit calculates optimized motor force within 10% of FEA in less than 1/1000 the computational time. This makes it well suited to genetic optimization algorithms. The mechanical model agrees very well with the experimental piston pump position data when tuned for additional unmodeled mechanical friction. Optimized results suggest that an improvement of 400% of the state of the art power density is attainable with as high as 85% net efficiency. This demonstrates that a linear electromagnetic piston pump has potential to serve as a more compact and efficient supply of fluid power for the human scale.

  16. Sibling cycle piston and valving method

    Science.gov (United States)

    Mitchell, Matthew P. (Inventor); Bauwens, Luc (Inventor)

    1990-01-01

    A double-acting, rotating piston reciprocating in a cylinder with the motion of the piston providing the valving action of the Sibling Cycle through the medium of passages between the piston and cylinder wall. The rotating piston contains regenerators ported to the walls of the piston. The piston fits closely in the cylinder at each end of the cylinder except in areas where the wall of the cylinder is relieved to provide passages between the cylinder wall and the piston leading to the expansion and compression spaces, respectively. The piston reciprocates as it rotates. The cylinder and piston together comprise an integral valve that seqentially opens and closes the ports at the ends of the regenerators alternately allowing them to communicate with the expansion space and compression space and blocking that communication. The relieved passages in the cylinder and the ports in the piston are so arranged that each regenerator is sequentially (1) charged with compressed working gas from the compression space; (2) isolated from both expansion and compression spaces; (3) discharged of working gas into the expansion space; and (4) simultaneously charged with working gas from the expansion space while being discharged of working gas into the compression space, in the manner of the Sibling Cycle. In an alterate embodiment, heat exchangers are external to the cylinder and ports in the cylinder wall are alternately closed by the wall of the piston and opened to the expansion and compression spaces through relieved passages in the wall of the reciprocating, rotating piston.

  17. Two piston V-type Stirling engine

    Science.gov (United States)

    Corey, John A.

    1987-01-01

    A two piston Stirling engine which includes a heat exchanger arrangement placing the cooler and regenerator directly adjacent the compression space for minimal cold duct volume; a sealing arrangement which eliminates the need for piston seals, crossheads and piston rods; and a simplified power control system.

  18. Heat flows in piston compressors

    NARCIS (Netherlands)

    Lekic, U.; Kok, J.B.W.; van der Meer, T.H.; van Steenhoven, A.A.; Stoffels, G.G.M.

    2008-01-01

    Piston compressors are widely used in today's engineering applications. Among the most important applications is however the compression of thermal carrier gas in Rankine and Stirling refrigeration cycles. Fluids used in these cycles are commonly Ammonia and Helium. In order to improve the design

  19. Experimental Verification of Oil Whirl of Piston in Axial Piston Pmmp and Motor

    OpenAIRE

    田中, 嘉津彦; 中原, 綱光; 京極, 啓史

    1999-01-01

    Piston motion which interacts with lubrication characteristics including friction force between the piston and cylinder has been measured in order to prove the oil whirl phenomena in an axial piston pump and motor which had been found theoretically in the previous paper. The piston motion has been measured by means of eddy current displacement sensors, comparing with calculated results. It has been verified that the piston has whirled in the cylinder under certain operating conditions and spe...

  20. Remaining useful life prediction based on the Wiener process for an aviation axial piston pump

    Directory of Open Access Journals (Sweden)

    Xingjian Wang

    2016-06-01

    Full Text Available An aviation hydraulic axial piston pump’s degradation from comprehensive wear is a typical gradual failure model. Accurate wear prediction is difficult as random and uncertain characteristics must be factored into the estimation. The internal wear status of the axial piston pump is characterized by the return oil flow based on fault mechanism analysis of the main frictional pairs in the pump. The performance degradation model is described by the Wiener process to predict the remaining useful life (RUL of the pump. Maximum likelihood estimation (MLE is performed by utilizing the expectation maximization (EM algorithm to estimate the initial parameters of the Wiener process while recursive estimation is conducted utilizing the Kalman filter method to estimate the drift coefficient of the Wiener process. The RUL of the pump is then calculated according to the performance degradation model based on the Wiener process. Experimental results indicate that the return oil flow is a suitable characteristic for reflecting the internal wear status of the axial piston pump, and thus the Wiener process-based method may effectively predicate the RUL of the pump.

  1. Engine piston assembly and forged piston member therefor having a cooling recess

    Energy Technology Data Exchange (ETDEWEB)

    Cooper, B.C.; Erickson, K.L.; Green, J.A.; Nyez, D.S.

    1989-09-19

    This patent describes a forged steel piston member for reciprocating movement in an engine. It comprises: an upper portion of substantially cylindrical shape and having a central axis, a top surface, a tubular wall depending from the top surface and having a peripheral groove adapted to receive a sealing ring, a lower end surface, and an inwardly facing wall surface extending upwardly from the lower end surface. The upper portion further includes an outwardly facing wall surface spaced radially inwardly from the inwardly facing wall surface and a downwardly facing transition portion blendingly associated with the inwardly and outwardly facing wall surfaces to collectively define an annular cooling recess, the transition portion being elevational spaced a relatively short distance from the top surface; and the inwardly facing wall surface being a machined surface of revolution about the central axis integral or one-piece forging.

  2. Tooth wear

    Directory of Open Access Journals (Sweden)

    Tušek Ivan

    2014-01-01

    Full Text Available Tooth wear is the loss of dental hard tissue that was not caused by decay and represents a common clinical problem of modern man. In the etiology of dental hard tissue lesions there are three dominant mechanisms that may act synergistically or separately:friction (friction, which is caused by abrasion of exogenous, or attrition of endogenous origin, chemical dissolution of dental hard tissues caused by erosion, occlusal stress created by compression and flexion and tension that leads to tooth abfraction and microfracture. Wear of tooth surfaces due to the presence of microscopic imperfections of tooth surfaces is clinically manifested as sanding veneers. Tribology, as an interdisciplinary study of the mechanisms of friction, wear and lubrication at the ultrastructural level, has defined a universal model according to which the etiopathogenesis of tooth wear is caused by the following factors: health and diseases of the digestive tract, oral hygiene, eating habits, poor oral habits, bruxism, temporomandibular disorders and iatrogenic factors. Attrition and dental erosion are much more common in children with special needs (Down syndrome. Erosion of teeth usually results from diseases of the digestive tract that lead to gastroesophageal reflux (GER of gastric juice (HCl. There are two basic approaches to the assessment of the degree of wear and dental erosion. Depending on the type of wear (erosion, attrition, abfraction, the amount of calcium that was realised during the erosive attack could be determined qualitatively and quantitatively, or changes in optical properties and hardness of enamel could be recorded, too. Abrasion of teeth (abrasio dentium is the loss of dental hard tissue caused by friction between the teeth and exogenous foreign substance. It is most commonly provoked by prosthetic dentures and bad habits, while its effect depends on the size of abrasive particles and their amount, abrasive particle hardness and hardness of tooth

  3. Tooth wear

    OpenAIRE

    Tušek Ivan; Tušek Jasmina

    2014-01-01

    Tooth wear is the loss of dental hard tissue that was not caused by decay and represents a common clinical problem of modern man. In the etiology of dental hard tissue lesions there are three dominant mechanisms that may act synergistically or separately:friction (friction), which is caused by abrasion of exogenous, or attrition of endogenous origin, chemical dissolution of dental hard tissues caused by erosion, occlusal stress created by compression and flexion and tension that leads to toot...

  4. Improvement in thermal fatigue resistance of cast iron piston; Chutetsu piston no tainetsu hiro sekkei

    Energy Technology Data Exchange (ETDEWEB)

    Amano, K; Uosaki, Y; Takeshige, N [Mazda Motor Corp., Hiroshima (Japan)

    1997-10-01

    Cast iron piston is superior in reduction of diesel engine emission to aluminum piston because of its characteristic of heat insulation. In order to study thermal fatigue characteristics of cast iron, thermal fatigue tests were carried out on two kinds of ferrite ductile cast iron. Differences between cast iron piston and aluminum piston in thermal fatigue resistance have been investigated by using FEM analysis. 5 refs., 14 figs., 1 tab.

  5. Development of bushing material with higher corrosion and wear resistance; Taishoku taimamosei dogokin bush zairyo no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Kira, T; Yokota, H; Kamiya, S [Taiho Kogyo Co. Ltd., Osaka (Japan)

    1997-10-01

    Recent diesel engines require a higher performance and a longer life. Due to higher cylinder pressure, the operating load and temperature of piston pin bushings become higher. Therefore, higher load capacity, higher wear resistance and higher corrosion resistance are required for piston pin bushings. For this reason, we have studied the effect of components added to copper alloy upon the corrosion resistance and the effect of hard particles dispersed in copper matrix upon the wear resistance and the influence of hard particles on the machinablity of materials. Based on the experimental results, we have developed a new bushing material improving wear and corrosion resistance. 17 figs., 3 tabs.

  6. Fluid structure interaction in piston diaphragm pumps

    NARCIS (Netherlands)

    Van Rijswick, R.; Van Rhee, C.

    2013-01-01

    Piston diaphragm pumps are used world-wide for the transport of aggressive and/or abrasive fluids in the chemical, mining and mineral processing industries. Figure 1 shows a cross section of a piston diaphragm pump as is used in the mining and mineral processing industries for the transport of

  7. On the validity range of piston theory

    CSIR Research Space (South Africa)

    Meijer, M-C

    2015-06-01

    Full Text Available The basis of linear piston theory in unsteady potential flow is used in this work to develop a quantitative treatment of the validity range of piston theory. In the limit of steady flow, velocity perturbations from Donov’s series expansion...

  8. Investigation on the radial micro-motion about piston of axial piston pump

    Science.gov (United States)

    Xu, Bing; Zhang, Junhui; Yang, Huayong; Zhang, Bin

    2013-03-01

    The limit working parameters and service life of axial piston pump are determined by the carrying ability and lubrication characteristic of its key friction pairs. Therefore, the design and optimization of the key friction pairs are always a key and difficult problem in the research on axial piston pump. In the traditional research on piston/cylinder pair, the assembly relationship of piston and cylinder bore is simplified into ideal cylindrical pair, which can not be used to analyze the influences of radial micro-motion of piston on the distribution characteristics of oil-film thickness and pressure in details. In this paper, based on the lubrication theory of the oil film, a numerical simulation model is built, taking the influences of roughness, elastic deformation of piston and pressure-viscosity effect into consideration. With the simulation model, the dynamic characteristics of the radial micro-motion and pressure distribution are analyzed, and the relationships between radial micro-motion and carrying ability, lubrication condition, and abrasion are discussed. Furthermore, a model pump for pressure distribution measurement of oil film between piston and cylinder bore is designed. The comparison of simulation and experimental results of pressure distribution shows that the simulation model has high accuracy. The experiment and simulation results demonstrate that the pressure distribution has peak values that are much higher than the boundary pressure in the piston chamber due to the radial micro-motion, and the abrasion of piston takes place mainly on the hand close to piston ball. In addition, improvement of manufacturing roundness and straightness of piston and cylinder bore is helpful to improve the carrying ability of piston/cylinder pair. The proposed research provides references for designing piston/cylinder pair, and helps to prolong the service life of axial piston pump.

  9. The Analysis of Secondary Motion and Lubrication Performance of Piston considering the Piston Skirt Profile

    Directory of Open Access Journals (Sweden)

    Yanjun Lu

    2018-01-01

    Full Text Available The work performance of piston-cylinder liner system is affected by the lubrication condition and the secondary motion of the piston. Therefore, more and more attention has been paid to the secondary motion and lubrication of the piston. In this paper, the Jakobson-Floberg-Olsson (JFO boundary condition is employed to describe the rupture and reformation of oil film. The average Reynolds equation of skirt lubrication is solved by the finite difference method (FDM. The secondary motion of piston-connecting rod system is modeled; the trajectory of the piston is calculated by the Runge-Kutta method. By considering the inertia of the connecting rod, the influence of the longitudinal and horizontal profiles of piston skirt, the offset of the piston pin, and the thermal deformation on the secondary motion and lubrication performance is investigated. The parabolic longitudinal profile, the smaller top radial reduction and ellipticities of the middle-convex piston, and the bigger bottom radial reduction and ellipticities can effectively reduce the secondary displacement and velocity, the skirt thrust, friction, and the friction power loss. The results show that the connecting rod inertia, piston skirt profile, and thermal deformation have important influence on secondary motion and lubrication performance of the piston.

  10. Tooth wear and wear investigations in dentistry.

    Science.gov (United States)

    Lee, A; He, L H; Lyons, K; Swain, M V

    2012-03-01

    Tooth wear has been recognised as a major problem in dentistry. Epidemiological studies have reported an increasing prevalence of tooth wear and general dental practitioners see a greater number of patients seeking treatment with worn dentition. Although the dental literature contains numerous publications related to management and rehabilitation of tooth wear of varying aetiologies, our understanding of the aetiology and pathogenesis of tooth wear is still limited. The wear behaviour of dental biomaterials has also been extensively researched to improve our understanding of the underlying mechanisms and for the development of restorative materials with good wear resistance. The complex nature of tooth wear indicates challenges for conducting in vitro and in vivo wear investigations and a clear correlation between in vitro and in vivo data has not been established. The objective was to critically review the peer reviewed English-language literature pertaining to prevalence and aetiology of tooth wear and wear investigations in dentistry identified through a Medline search engine combined with hand-searching of the relevant literature, covering the period between 1960 and 2011. © 2011 Blackwell Publishing Ltd.

  11. 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.

  12. Development and Experimental Investigation of a Two-Stroke Opposed-Piston Free-Piston Engine

    OpenAIRE

    Schneider, Stephan; Chiodi, Marco; Friedrich, Horst E.; Bargende, Michael

    2016-01-01

    The proposed paper deals with the development process and initial measurement results of an opposed-piston combustion engine for application in a Free-Piston Linear Generator (FPLG). The FPLG, which is being developed at the German Aerospace Center (DLR), is an innovative internal combustion engine for a fuel based electrical power supply. With its arrangement, the pistons freely oscillate between the compression chamber of the combustion unit and a gas spring with no mechanical coupling like...

  13. Ring Theory

    CERN Document Server

    Jara, Pascual; Torrecillas, Blas

    1988-01-01

    The papers in this proceedings volume are selected research papers in different areas of ring theory, including graded rings, differential operator rings, K-theory of noetherian rings, torsion theory, regular rings, cohomology of algebras, local cohomology of noncommutative rings. The book will be important for mathematicians active in research in ring theory.

  14. Method and means for repairing injection fuel pump pistons

    Energy Technology Data Exchange (ETDEWEB)

    Ash, E.G.; Tompkins, M.J. Jr.

    1988-06-07

    This patent describes an improvement in timing pistons for rotary fuel injection pumps of the type having a die cast aluminum housing. The housing has a cylindrical chamber, a steel piston, the piston being received in the chamber, means for reciprocating the piston lengthwise of the chamber, an aluminum jacket surrounding the piston and extending the full length thereof, the jacket being rigidly secured to the piston. The jacket has an exterior surface hard coat anodized to the hardness of about 60-70 Rockwell (C scale) as the means of preventing galling due to the reciprocal movement of the aluminum jacket piston within the aluminum chamber.

  15. Drift stabilizer for reciprocating free-piston devices

    Science.gov (United States)

    Ward, William C.; Corey, John A.; Swift, Gregory W.

    2003-05-20

    A free-piston device has a stabilized piston drift. A piston having a frequency of reciprocation over a stroke length and with first and second sides facing first and second variable volumes, respectively, for containing a working fluid defining an acoustic wavelength at the frequency of reciprocation. A bypass tube waveguide connects the first and second variable volumes at all times during reciprocation of the piston. The waveguide has a relatively low impedance for steady flow and a relatively high impedance for oscillating flow at the frequency of reciprocation of the piston, so that steady flow returns fluid leakage from about the piston between the first and second volumes while oscillating flow is not diverted through the waveguide. Thus, net leakage about the piston is returned during each stroke of the piston while oscillating leakage is not allowed and pressure buildup on either the first or second side of the piston is avoided to provide a stable piston location.

  16. Free Piston Problem for Isentropic Gas Dynamics

    OpenAIRE

    Takeno, Shigeharu

    1995-01-01

    We consider the existence of the generalized solution for a free piston problem for isentropic gas dynamics. By the compensated compactness theory, we can show that an approximate solution converges to a generalized solution.

  17. Integrated Free-Piston Generators: An Overview

    Energy Technology Data Exchange (ETDEWEB)

    Arshad, Waqas M.; Thelin, Peter; Sadarangani, Chandur [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Electrical Machines and Power Electronics; Baeckstroem, Thomas [ABB Group Services-Corporate Research, Vaesteraas (Sweden)

    2002-08-01

    The free-piston generator is an energy conversion device that integrates a combustion engine and an electrical generator into a single unit. Thereby the intermediary crankshaft stage present in conventional hybrid topologies is eliminated. This has benefits in efficiency, weight reduction, robustness, variable compression operation and multi-fuel possibilities. This paper presents the free-piston generator concepts, along with the expected benefits and drawbacks. A literature survey is provided. Results from a simplified combustion modeling process are presented in terms of piston motion profiles. These have implications upon the dimensioning and selection of an appropriate electrical machine. Specifications for the electrical machine are outlined. Some distinct electrical machine solutions are presented and discussed. An application of the free-piston generator in a series hybrid vehicle is also proposed.

  18. Interaction of Vortex Ring with Cutting Plate

    Science.gov (United States)

    Musta, Mustafa

    2015-11-01

    The interaction of a vortex ring impinging on a thin cutting plate was made experimentally using Volumetric 3-component Velocitmetry (v3v) technique. The vortex rings were generated with piston-cylinder vortex ring generator using piston stroke-to-diameter ratios and Re at 2-3 and 1500 - 3000, respectively. The cutting of vortex rings below center line leads to the formation of secondary vortices on each side of the plate which is look like two vortex rings, and a third vortex ring propagates further downstream in the direction of the initial vortex ring, which is previously showed by flow visualization study of Weigand (1993) and called ``trifurcation''. Trifurcation is very sensitive to the initial Reynolds number and the position of the plate with respect to the vortex ring generator pipe. The present work seeks more detailed investigation on the trifurcation using V3V technique. Conditions for the formation of trifurcation is analyzed and compared with Weigand (1993). The formed secondary vortex rings and the propagation of initial vortex ring in the downstream of the plate are analyzed by calculating their circulation, energy and trajectories.

  19. Rotary piston blood pumps: past developments and future potential of a unique pump type.

    Science.gov (United States)

    Wappenschmidt, Johannes; Autschbach, Rüdiger; Steinseifer, Ulrich; Schmitz-Rode, Thomas; Margreiter, Raimund; Klima, Günter; Goetzenich, Andreas

    2016-08-01

    The design of implantable blood pumps is either based on displacement pumps with membranes or rotary pumps. Both pump types have limitations to meet the clinical requirements. Rotary piston blood pumps have the potential to overcome these limitations and to merge the benefits. Compared to membrane pumps, they are smaller and with no need for wear-affected membranes and valves. Compared to rotary pumps, the blood flow is pulsatile instead of a non-physiological continuous flow. Furthermore, the risk of flow-induced blood damage and platelet activation may be reduced due to low shear stress to the blood. The past developments of rotary piston blood pumps are summarized and the main problem for long-term application is identified: insufficient seals. A new approach with seal-less drives is proposed and current research on a simplified rotary piston design is presented. Expert commentary: The development of blood pumps focuses mainly on the improvement of rotary pumps. However, medical complications indicate that inherent limitations of this pump type remain and restrict the next substantial step forward in the therapy of heart failure patients. Thus, research on different pump types is reasonable. If the development of reliable drives and bearings succeeds, rotary piston blood pumps become a promising alternative.

  20. Uji Unjuk Kerja Pompa Pedal Multi Piston

    OpenAIRE

    Sukwanputra, Firman Yoko; Soegihardjo, Oegik

    2003-01-01

    Multi piston pedal pump is classified under reciprocating pump. This pump is generally designed for applications that require high capacity with low head. This pump is used for shallow well or to pump water in the system with low static and dynamic head. This experiment will examine the performance of multi piston pedal pump with capacity 3000 liter/hour. Two parameters, volumetric efficiency and overall efficiency will be examined during the experiment. The goal is to know the actual perform...

  1. Experimental study on the influence of the rotating cylinder and circling pistons on churning losses in axial piston pumps

    OpenAIRE

    Zhang, Junhui; Li, Ying; Xu, Bing; Pan, Min; Lv, Fei

    2017-01-01

    Pressure and performance requirements of axial piston pumps and the proportion of churning losses in axial piston pumps increase significantly with increasing speed. To investigate the primary distribution of churning losses in axial piston pumps at various ranges of speed, a test rig was set up in which other friction losses can be eliminated, thus making it possible to investigate the net churning losses in an axial piston pump. The influence of the rotating cylinder block and pistons on ch...

  2. Study of improvement in 1st ring`s gas-seal; Top ring no gas seal seino kojo no kento

    Energy Technology Data Exchange (ETDEWEB)

    Ando, H; Tateishi, Y; Fujimura, K; Hitosugi, H [Nippon Piston Ring Co. Ltd., Tokyo (Japan)

    1997-10-01

    The authors studied the effect of an angle of 1st ring twist on the amount of blow-by concerning higher speed/higher output engines for motorcycles. As a result, the authors found the twist made the ring restrained in a ring groove of piston , and confirmed its suitable range for blow-by. By means of the developed optimization method, the authors have achieved significant reduction in blow-by at high engine speed. 1 ref., 9 figs., 2 tabs.

  3. Drive piston assembly for a valve actuator assembly

    Science.gov (United States)

    Sun, Zongxuan

    2010-02-23

    A drive piston assembly is provided that is operable to selectively open a poppet valve. The drive piston assembly includes a cartridge defining a generally stepped bore. A drive piston is movable within the generally stepped bore and a boost sleeve is coaxially disposed with respect to the drive piston. A main fluid chamber is at least partially defined by the generally stepped bore, drive piston, and boost sleeve. First and second feedback chambers are at least partially defined by the drive piston and each are disposed at opposite ends of the drive piston. At least one of the drive piston and the boost sleeve is sufficiently configured to move within the generally stepped bore in response to fluid pressure within the main fluid chamber to selectively open the poppet valve. A valve actuator assembly and engine are also provided incorporating the disclosed drive piston assembly.

  4. Analysis of piston behavior according to eccentricity ratio of disk in bent-axis type piston pump

    International Nuclear Information System (INIS)

    Baek, Il Hyun; Cho, Ihn Sung; Jung, Jae Youn; Hong, Lu

    2008-01-01

    To improve the performance of the bent-axis type axial piston pump driven by the tapered piston, it is necessary to know the driving characteristics and mechanism of the tapered piston and the cylinder block. Since each piston not only rotates on its axis and reciprocates in the cylinder bore but also revolves around the axis of the driving shaft, it is difficult to analyze the driving mechanism theoretically. The theoretical mechanism for the bent-axis type axial piston pump is studied by using the geometrical method. The driving range of the tapered piston is determined by theoretical equations. The results show that the cylinder block is driven by one tapered piston in a limited range and the core parameters such as the tilting angle of the piston and the ahead delay angle influence performance of the bent-axis type axial piston pump

  5. Immersion piston for producing crude oil and liquids from boreholes

    Energy Technology Data Exchange (ETDEWEB)

    Fekete, I; Hornyos, J

    1967-02-09

    When using a free piston to pump an oil well, oil and gas accumulates above and below the piston; upon venting the gas pressure above the piston, the gas pressure below it drives the piston and the oil above it to the surface. In the past, such pistons were too heavy and did not run tight in the tubing, causing loss of efficiency and high gas consumption. According to this invention, the piston is made of aluminum or plastic; it consists of at least 2 parts flexibly connected by wire rope or plastic strings, and is equipped with a labyrinth gasket and a paraffin scraper. (3 claims)

  6. Application of wear resistant spraying for diesel engine; Diesel kikan eno taimamo yosha no tekiyo

    Energy Technology Data Exchange (ETDEWEB)

    Kitajima, Y. [Mitsui Engineering and Shipbuliding Co. Ltd., Tokyo (Japan)

    1999-03-31

    Diesel engines used widely as propelling engines of ships have increasingly been provided with a high output and a high thermal efficiency; their structural members, particularly, the component parts for combustion chambers are therefore used under severe conditions, giving rise to the need of surface treatment and surface reforming of the members. Parts for marine diesel engines are huge, so that the technology applicable to the surface treatment and reforming are limited in point of facility and cost; therefore, most suitable is thermal spraying. This paper primarily discusses, among marine diesel engines, a 2-cycle low-speed engine with a 260-980mm bore used for the main engine of a merchant ship such as a container ship, bulk carrier or a tanker, and a 4-cycle medium-speed engine with a 300-420mm bore used for the main engine of a naval vessel; the paper explains the application status of a thermal spraying technology which is in progress to cope with the high output and high thermal efficiency of the diesel engines, explaining particularly the story of the development and the technological features of the wear resistant thermal spraying, which has been put to practical use, on the cylinder liner and the piston ring of the 4-cycle medium-speed engine. (NEDO)

  7. Abrasive wear of intermetallics

    International Nuclear Information System (INIS)

    Hawk, J.A.; Alman, D.E.; Wilson, R.D.

    1995-01-01

    The US Bureau of Mines is investigating the wear behavior of a variety of advanced materials. Among the many materials under evaluation are intermetallic alloys based on the compounds: Fe 3 Al, Ti 3 Al, TiAl, Al 3 Ti, NiAl and MoSi 2 . The high hardness, high modulus, low density, and superior environmental stability of these compounds make them attractive for wear materials. This paper reports on the abrasive wear of alloys and composites based on the above compounds. The abrasive wear behavior of these alloys and composites are compared to other engineering materials used in wear applications

  8. Free piston space Stirling technology program

    Science.gov (United States)

    Dochat, G. R.; Dhar, M.

    1989-01-01

    MTI recently completed an initial technology feasibility program for NASA by designing, fabricating and testing a space power demonstrator engine (SPDE). This program, which confirms the potential of free-piston Stirling engines, provided the major impetus to initiate a free-piston Stirling space engine (SSE) technology program. The accomplishments of the SPDE program are reviewed, and an overview of the SSE technology program and technical status to date is provided. It is shown that progress in both programs continues to justify its potential for either nuclear or solar space power missions.

  9. Acoustic emission testing of piston check valves

    International Nuclear Information System (INIS)

    Stewart, D.L.

    1994-01-01

    Based on test experience at Comanche Peak Unit 1, an acoustic emission data evaluation matrix for piston check valves has been developed. The degradations represented in this matrix were selected based on Edwards piston check valve failure data reported in the Nuclear Plant Reliability Data System. Evidence to support this matrix was collected from site test data on a variety of valve types. Although still under refinement, the matrix provides three major attributes for closure verification, which have proven useful in developing test procedures for inservice testing and preventing unnecessary disassembly

  10. Optimised intake stroke analysis for flat and dome head pistons ...

    African Journals Online (AJOL)

    Optimised intake stroke analysis for flat and dome head pistons. ... in understanding the performance characteristics optioned between flat head and dome head pistons in engine design. ... EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT

  11. Aluminum Matrix Composite (AlSi7Mg2Sr0.03/SiCp) Pistons Obtained by Mechanical Mixing Method

    Science.gov (United States)

    2017-01-01

    Metal matrix composites are undoubtedly a group of advanced engineering materials. Compared to unreinforced matrix material, they are characterized by increased strength, greater stiffness, increased wear resistance, better mechanical properties and dimensional stability at elevated temperatures as well as lower density. Due to its very favorable tribological properties for many years research has been conducted on the application of MMC in friction node. The article presents important technological aspects related to the production and properties of composite pistons. Under industrial conditions, a composite suspension (AlSi7Mg2Sr0.03/SiCp 10 vol %) was prepared to allow casting of the semi-finished pistons series. Machining parameters of the working surfaces of the piston were selected on the basis of the turning test made on PCD, PCNM and uncoated carbide tools. The tribological properties of the composite pistons were determined on the basis of the pin-on-disc and the abrasion wear. The scuffing tests carried out under real operating conditions have confirmed the possibility of using composite pistons in air compressors. PMID:29283419

  12. Aluminum Matrix Composite (AlSi7Mg2Sr0.03/SiCp Pistons Obtained by Mechanical Mixing Method

    Directory of Open Access Journals (Sweden)

    Maciej Dyzia

    2017-12-01

    Full Text Available Metal matrix composites are undoubtedly a group of advanced engineering materials. Compared to unreinforced matrix material, they are characterized by increased strength, greater stiffness, increased wear resistance, better mechanical properties and dimensional stability at elevated temperatures as well as lower density. Due to its very favorable tribological properties for many years research has been conducted on the application of MMC in friction node. The article presents important technological aspects related to the production and properties of composite pistons. Under industrial conditions, a composite suspension (AlSi7Mg2Sr0.03/SiCp 10 vol % was prepared to allow casting of the semi-finished pistons series. Machining parameters of the working surfaces of the piston were selected on the basis of the turning test made on PCD, PCNM and uncoated carbide tools. The tribological properties of the composite pistons were determined on the basis of the pin-on-disc and the abrasion wear. The scuffing tests carried out under real operating conditions have confirmed the possibility of using composite pistons in air compressors.

  13. Staged combustion with piston engine and turbine engine supercharger

    Science.gov (United States)

    Fischer, Larry E [Los Gatos, CA; Anderson, Brian L [Lodi, CA; O'Brien, Kevin C [San Ramon, CA

    2011-11-01

    A combustion engine method and system provides increased fuel efficiency and reduces polluting exhaust emissions by burning fuel in a two-stage combustion system. Fuel is combusted in a piston engine in a first stage producing piston engine exhaust gases. Fuel contained in the piston engine exhaust gases is combusted in a second stage turbine engine. Turbine engine exhaust gases are used to supercharge the piston engine.

  14. Predictive piston motion control in a free-piston internal combustion engine

    Energy Technology Data Exchange (ETDEWEB)

    Mikalsen, R.; Jones, E.; Roskilly, A.P. [Sir Joseph Swan Institute for Energy Research, Newcastle University, Newcastle upon Tyne, NE1 7RU England (United Kingdom)

    2010-05-15

    A piston motion controller for a free-piston internal combustion engine is presented. To improve dynamic performance in the control of the piston motion and engine compression ratio, the controller response is determined from a prediction of engine top dead centre error rather than the measured value from the previous cycle. The proposed control approach showed superior performance compared with that of standard PI feedback control known from the literature due to a reduced control action time delay. The manipulation of fuel injection timing to reduce in-cylinder pressure peaks and cycle-to-cycle variations was also studied, indicating that with the piston motion estimation, the injection timing is a powerful control variable for this purpose. (author)

  15. Fluid structure interaction in piston diaphragm pumps

    NARCIS (Netherlands)

    van Rijswick, R.J.A.

    2017-01-01

    Piston diaphragm pumps are used world-wide to transport abrasive and/or aggressive slurries against high discharge pressures in the mining, mineral processing and power industries. Limitation of excessive deformation of the diaphragm is of utmost importance for eliminating fatigue failures of the

  16. Aircraft Piston Engine Exhaust Emission Symposium

    Science.gov (United States)

    1976-01-01

    A 2-day symposium on the reduction of exhaust emissions from aircraft piston engines was held on September 14 and 15, 1976, at the Lewis Research Center in Cleveland, Ohio. Papers were presented by both government organizations and the general aviation industry on the status of government contracts, emission measurement problems, data reduction procedures, flight testing, and emission reduction techniques.

  17. 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.

  18. How Hot Can a Fire Piston Get?

    Science.gov (United States)

    Scott-Brown, J. A.; Cunningham, O. A.; Goad, B. C.

    2010-01-01

    The fire piston is just a sealed syringe containing a small amount of tinder. When the plunger is forced downwards, the air inside is compressed and heats up, setting fire to the tinder. It has been used as a convenient and portable way of starting fires "over a wide area from northern Burma and Siam through the Malay Peninsula and the Malayan…

  19. From aluminium pistons to steel pistons in trucks and ships; Von Aluminium- zum Stahlgrosskolben bei Nkw und Schiffen

    Energy Technology Data Exchange (ETDEWEB)

    Kortas, J. [Mahle GmbH, Markgroeningen (Germany). Produktkonstruktion Grossmotorenkomponenten

    2005-11-01

    This article is intended to show the development from one-piece aluminum pistons to composite pistons made from forged steel. With the Mahle pistons completely produced from forged steel, process-safe peak cylinder pressures of 25 MPa can be achieved. The steel piston development was initiated in the commercial vehicle sector and then extended to large engines with cylinder diameters up to 480 mm. (orig.)

  20. Polymer wear evaluation

    DEFF Research Database (Denmark)

    Lagerbon, Mikkel; Sivebæk, Ion Marius

    2012-01-01

    Polymer wear plays an increasing role in manufacturing of machine parts for e.g. medical devices. Some of these have an expected lifetime of five to eight years during which very little wear of the components is acceptable. Too much wear compromises the dosage accuracy of the device and thereby...... the safety of the patients. Prediction of the wear of polymers is complicated by the low thermal conductivity of this kind of material. It implies that any acceleration of testing conditions by increased contact pressure and/or sliding velocity will make the polymer fail due to exaggerated heat buildup....... This is not the kind of wear observed in medical devices. In the present work a method was developed capable of evaluating the wear progression in polymer-polymer contacts. The configuration of the setup is injection moulded specimens consisting of an upper part having a toroid shape and a lower flat part. The sliding...

  1. Vortex Ring Interaction with a Heated Screen

    Science.gov (United States)

    Smith, Jason; Krueger, Paul S.

    2008-11-01

    Previous examinations of vortex rings impinging on porous screens has shown the reformation of the vortex ring with a lower velocity after passing through the screen, the creation of secondary vortices, and mixing. A heated screen could, in principle, alter the vortex-screen interaction by changing the local liquid viscosity and density. In the present investigation, a mechanical piston-cylinder vortex ring generator was used to create vortex rings in an aqueous sucrose solution. The rings impinged on a screen of horizontal wires that were heated using electrical current. The flow was visualized with food color and video imaging. Tests with and without heat were conducted at a piston stroke-to-jet diameter ratio of 4 and a jet Reynolds number (Re) of 1000. The vortex rings slowed after passing through the screen, but in tests with heat, they maintained a higher fraction of their before-screen velocity due to reduction in fluid viscosity near the wires. In addition, small ``fingers'' that developed on the front of the vortex rings as they passed through the screen exhibited positive buoyancy effects in the heated case.

  2. Black rings

    International Nuclear Information System (INIS)

    Emparan, Roberto; Reall, Harvey S

    2006-01-01

    A black ring is a five-dimensional black hole with an event horizon of topology S 1 x S 2 . We provide an introduction to the description of black rings in general relativity and string theory. Novel aspects of the presentation include a new approach to constructing black ring coordinates and a critical review of black ring microscopics. (topical review)

  3. White Ring; White ring

    Energy Technology Data Exchange (ETDEWEB)

    Aoki, H.; Yuzawa, H. [Nikken Sekkei Ltd., Osaka (Japan)

    1998-01-05

    White Ring is a citizen`s gymnasium used for figure skating and short track speed skating games of 18th Winter Olympic Games in 1998. White Ring is composed of a main-arena and a sub-arena. For the main-arena with an area 41mtimes66m, an ice link can be made by disengaging the potable floor and by flowing brine in the bridged polystyrene pipes embedded in the concrete floor. Due to the fortunate groundwater in this site, well water is used for the outside air treatment energy in 63% during heating and in 35% during cooling. Ammonia is used as a cooling medium for refrigerating facility. For the heating of audience area in the large space, heat load from the outside is reduced by enhancing the heat insulation performance of the roof of arena. The audience seats are locally heated using heaters. For the White Ring, high quality environment is realized for games through various functions of the large-scale roof of the large space. Success of the big event was expected. 15 figs., 4 tabs.

  4. Cylinder head seal for piston engines especially internal combustion engines. Zylinderkopfdichtung fuer Hubkolbenmaschinen, insbesondere Brennkraftmaschinen

    Energy Technology Data Exchange (ETDEWEB)

    Kubis, H.; Winter, J.

    1991-01-17

    The invention concerns a cylinder head seal for reciprocating piston engines especially internal combustion engines and preferentially those with cylinder sleeves. With performances of internal combustion engines encreasing all the time it is becoming more and more difficult to seal the cylinder heat. The invention proposes a ring seal whose sides are plastically deformed when the cylinder headed screws are tightened. The inner deformations of the cylinder head resulting from the pressure forces inside the cylinder are compensated by means of elastic spring action of the combustion chamber sealing ring. The dimension of land, groove and sides are matched in such a way as to prevent any seal squeezing during plastification which would result in a deformation of the cylinder sleeve. The ring can therefore be set directly into the centering of the cylinder sleeve. Separate centering devices are not required.

  5. Casimir pistons with general boundary conditions

    Directory of Open Access Journals (Sweden)

    Guglielmo Fucci

    2015-02-01

    Full Text Available In this work we analyze the Casimir energy and force for a scalar field endowed with general self-adjoint boundary conditions propagating in a higher dimensional piston configuration. The piston is constructed as a direct product I×N, with I=[0,L]⊂R and N a smooth, compact Riemannian manifold with or without boundary. The study of the Casimir energy and force for this configuration is performed by employing the spectral zeta function regularization technique. The obtained analytic results depend explicitly on the spectral zeta function associated with the manifold N and the parameters describing the general boundary conditions imposed. These results are then specialized to the case in which the manifold N is a d-dimensional sphere.

  6. Evaluation of dry sliding wear behavior of silicon particles reinforced aluminum matrix composites

    International Nuclear Information System (INIS)

    Sun Zhiqiang; Zhang Di; Li Guobin

    2005-01-01

    This paper reports a study on the wear property of powder metallurgy aluminum matrix composites 9Si/Al-Cu-Mg. A on rock wear-testing machine is used to evaluate the wear property of the composites, in which a GCrl5 steel ring is used as the counter face material. The wear behavior of the composites under different conditions is studied. The optical microscope and scanning electron microscope are used to analyze the worn surfaces and the subsurface of the composites in order to research the wear mechanism of the composites. Results indicate that the weight loss of the composite were lower than that of the matrix alloy

  7. Multiple Cylinder Free-Piston Stirling Machinery

    Science.gov (United States)

    Berchowitz, David M.; Kwon, Yong-Rak

    In order to improve the specific power of piston-cylinder type machinery, there is a point in capacity or power where an advantage accrues with increasing number of piston-cylinder assemblies. In the case of Stirling machinery where primary energy is transferred across the casing wall of the machine, this consideration is even more important. This is due primarily to the difference in scaling of basic power and the required heat transfer. Heat transfer is found to be progressively limited as the size of the machine increases. Multiple cylinder machines tend to preserve the surface area to volume ratio at more favorable levels. In addition, the spring effect of the working gas in the so-called alpha configuration is often sufficient to provide a high frequency resonance point that improves the specific power. There are a number of possible multiple cylinder configurations. The simplest is an opposed pair of piston-displacer machines (beta configuration). A three-cylinder machine requires stepped pistons to obtain proper volume phase relationships. Four to six cylinder configurations are also possible. A small demonstrator inline four cylinder alpha machine has been built to demonstrate both cooling operation and power generation. Data from this machine verifies theoretical expectations and is used to extrapolate the performance of future machines. Vibration levels are discussed and it is argued that some multiple cylinder machines have no linear component to the casing vibration but may have a nutating couple. Example applications are discussed ranging from general purpose coolers, computer cooling, exhaust heat power extraction and some high power engines.

  8. Cylinder with differential piston for mass measurements

    Energy Technology Data Exchange (ETDEWEB)

    Bordeaşu, I.; Bălăşoiu, V. [Universitatea Politehnica din Timişoara, Timosoara (Romania); Hadă, A. [UniversitateaPolitehnicaBucureşti, Bucureşti (Romania); Popoviciu, M. [Academy of Romanian ScientistsTimişoara Branch (Romania)

    2007-07-01

    The paper presents a cylinder with differential piston, adapted for measuring the weight of fixed objects such as: fuel tanks (regardless of their capacity), bunkers and silos for all kind of materials, or mobile objects such as: automobiles, trucks, locomotives and railway cars. Although, the cylinder with differential piston is used on a large scale in hydraulic drive or hydraulic control circuits, till now it was not used as constituent part for weight measurements devices. The novelty of the present paper is precisely the use of the device for such purposes. Based on a computation algorithm, the paper presents the general design (assembly), of the device used for weighing important masses (1…. 100 tones). The fundamental idea consist in the fact that, a mass over 10 tones may be weighted with a helicoidally spring subjected to an axial force between 0 and 3000 N, with a deflection of about 30 mm. Simultaneously with the mechanical part, the electronic recording system is also described. The great advantage of the presented device consist in the fact that it can be used in heavy polluted atmosphere or difficult topographic conditions as a result of both the small dimensions and the protection systems adopted. Keywords: cylinder hydraulic with differential piston, hydrostatic pressure, measuring devices.

  9. Hearing results using the SMart piston prosthesis.

    Science.gov (United States)

    Fayad, Jose N; Semaan, Maroun T; Meier, Josh C; House, John W

    2009-12-01

    SMart, a newly introduced piston prosthesis for stapedotomy, is a nitinol-based, heat-activated, self-crimping prosthesis. We review our hearing results and postoperative complications using this self-crimped piston prosthesis and compare them with those obtained using stainless steel or platinum piston prostheses. Audiometric results using the SMart piston are identical to those obtained using a conventional piston prosthesis. Retrospective chart review. Private neurotologic tertiary referral center. The 416 ears reviewed included 306 with a SMart prosthesis and 110 conventional prostheses. 61% were women. Mean follow-up time was 5.6 (standard deviation [SD], 6.3 mo) and 6.9 months (SD, 7.0 mo) for the 2 groups, respectively. Stapedotomy using the SMart or a conventional (non-SMart) prosthesis. Audiometric hearing results, including pure-tone average (PTA) and air-bone gap (ABG), and prevalence of postoperative complications. Mean postoperative PTA was 32.6 (SD, 16.8) dB for the SMart group and 29.4 (SD, 13.5) dB for the non-SMart group, with ABGs of 7.6 (SD, 8.9) and 6.0 (SD, 5.2) dB, respectively. Mean change (decrease) in ABG was 18.7 (SD, 13.1) dB for the SMart group and 19.9 (SD, 10.3) dB for the non-SMart group. High-frequency bone PTAs showed overclosure of 2.0 (SD, 7.9) dB for the SMart group and 3.6 (SD, 8.6) dB for the non-SMart group. Postoperative vertigo and tinnitus were infrequent. No significant differences in these audiometric outcomes or complication rates were noted between groups. There was no significant difference in rate of gap closure to within 10 dB (78.3 versus 84.2%, SMart and non-SMart, respectively) or 20 dB (94.2 and 98.0%). Compared with conventional stapes prostheses, the nitinol-based SMart is a safe and reliable stapes prosthesis that eliminates manual crimping without significantly altering the audiometric outcome. Complications are rare, but longer follow-up is needed before establishing long-term stability.

  10. Vortex rings

    CERN Document Server

    Akhmetov, D G

    2009-01-01

    This text on vortex rings covers their theoretical foundation, systematic investigations, and practical applications such as the extinction of fires at gushing oil wells. It pays special attention to the formation and motion of turbulent vortex rings.

  11. Improving Power Density of Free-Piston Stirling Engines

    Science.gov (United States)

    Briggs, Maxwell H.; Prahl, Joseph M.; Loparo, Kenneth A.

    2016-01-01

    Analyses and experiments demonstrate the potential benefits of optimizing piston and displacer motion in a free-piston Stirling Engine. Isothermal analysis shows the theoretical limits of power density improvement due to ideal motion in ideal Stirling engines. More realistic models based on nodal analysis show that ideal piston and displacer waveforms are not optimal, often producing less power than engines that use sinusoidal piston and displacer motion. Constrained optimization using nodal analysis predicts that Stirling engine power density can be increased by as much as 58 percent using optimized higher harmonic piston and displacer motion. An experiment is conducted in which an engine designed for sinusoidal motion is forced to operate with both second and third harmonics, resulting in a piston power increase of as much as 14 percent. Analytical predictions are compared to experimental data and show close agreement with indirect thermodynamic power calculations, but poor agreement with direct electrical power measurements.

  12. Improving Free-Piston Stirling Engine Power Density

    Science.gov (United States)

    Briggs, Maxwell H.

    2016-01-01

    Analyses and experiments demonstrate the potential benefits of optimizing piston and displacer motion in a free piston Stirling Engine. Isothermal analysis shows the theoretical limits of power density improvement due to ideal motion in ideal Stirling engines. More realistic models based on nodal analysis show that ideal piston and displacer waveforms are not optimal, often producing less power than engines that use sinusoidal piston and displacer motion. Constrained optimization using nodal analysis predicts that Stirling engine power density can be increased by as much as 58% using optimized higher harmonic piston and displacer motion. An experiment is conducted in which an engine designed for sinusoidal motion is forced to operate with both second and third harmonics, resulting in a maximum piston power increase of 14%. Analytical predictions are compared to experimental data showing close agreement with indirect thermodynamic power calculations, but poor agreement with direct electrical power measurements.

  13. A numerical simulation of the piston cooling in view of consumption capabilities and enhanced power density; Numerische Simulation der Kolbenkuehlung im Hinblick auf Verbrauchspotentiale und erhoehte Leistungsdichte

    Energy Technology Data Exchange (ETDEWEB)

    Lutz, Johannes [BMW Group, Muenchen (Germany)

    2012-11-01

    To meet stringent emission regulations and high power requirements, peak cylinder pressures and specific power of petrol engines have increased dramatically in recent years. Nevertheless, regarding customer expectations and in the interest of driving dynamics, modern engines should still adhere to the established wide speed range, resulting in higher thermal loading of in-cylinder components such as piston. To ensure durability and reliability, it is vital for piston cooling concepts to keep maximum temperatures securely below an acceptable limit. In addition, reducing piston cooling at part load can help to gain efficiency and decrease fuel consumption. These exacting demands on the cooling concept require an exact analysis of thermal boundary conditions and their influence on the piston temperature. While good verified models for the combustion simulation already exist, the thermal cooling boundaries involve a greater level of uncertainty. The reason for this lies in the inadequately investigated heat transfer conditions on the piston undercrown and the running surface at present, due to complex fluid dynamics of the oil jet cooling and strong ring movements during a load cycle. This study refines the thermal boundary conditions and leads to precise knowledge of the transient and averaged heat flow through the piston and the cylinder liner. Based on these results, optimized cooling strategies to gain efficiency can be developed with the help of well validated one dimensional thermal engine models. (orig.)

  14. CORROSION AND WEAR PROPERTIES OF MATERIALS USED FOR MINCED MEAT PRODUCTION

    DEFF Research Database (Denmark)

    Jellesen, Morten Stendahl; Hansen, Martin Otto Laver; Hilbert, Lisbeth Rischel

    2009-01-01

    measurements. Combined sliding wear and corrosion conditions have been simulated in laboratory using a block-on-ring setup allowing for electrochemical measurements. Detailed information concerning the mechanism of possible material degradation is provided by these results, together with microstructural...

  15. Improving Free-Piston Stirling Engine Specific Power

    Science.gov (United States)

    Briggs, Maxwell H.

    2015-01-01

    This work uses analytical methods to demonstrate the potential benefits of optimizing piston and/or displacer motion in a Stirling engine. Isothermal analysis was used to show the potential benefits of ideal motion in ideal Stirling engines. Nodal analysis is used to show that ideal piston and displacer waveforms are not optimal in real Stirling engines. Constrained optimization was used to identify piston and displacer waveforms that increase Stirling engine specific power.

  16. The research on flow pulsation characteristics of axial piston pump

    Science.gov (United States)

    Wang, Bingchao; Wang, Yulin

    2017-01-01

    The flow pulsation is an important factor influencing the axial piston pump performance. In this paper we implement modeling and simulation of the axial piston pump with AMESim software to explore the flow pulsation characteristics under various factors . Theory analysis shows the loading pressure, angular speed, piston numbers and the accumulator impose evident influence on the flow pulsation characteristics. This simulation and analysis can be used for reducing the flow pulsation rate via properly setting the related factors.

  17. A review of free-piston engine history and applications

    Energy Technology Data Exchange (ETDEWEB)

    Mikalsen, R.; Roskilly, A.P. [School of Marine Science and Technology, University of Newcastle upon Tyne, Newcastle upon Tyne NE1 7RU (United Kingdom)

    2007-10-15

    This document reviews the history of free-piston internal combustion engines, from the air compressors and gas generators used in the mid-20th century through to recent free-piston hydraulic engines and linear electric generators. Unique features of the free-piston engine are presented and their effects on engine operation are discussed, along with potential advantages and disadvantages compared to conventional engines. The paper focuses mainly on developed engines where operational data has been reported. Finally, the potential of the free-piston engine is evaluated and the most promising designs identified. (author)

  18. Wear testing and finite element analysis of nitrile rubber (NBR) hand pump seals

    OpenAIRE

    Alkadhimi, Fadel

    2015-01-01

    The use of Nitrile Butadiene Rubber NBR as seal in machines has increased in recent years. NBR is considered as the standard material for sealing and NBR owes its many applications to a range of special mechanical properties. However, the non-linear mechanical properties and incompressible behaviour of NBR make the analysis of NBR very difficult. The literature review highlighted the fact that the most common technical cause of hand pump failures was the wear of the piston seals. The contact ...

  19. THE COURSE IN TESTING THE WEARING OUT OF MUD PUMPS PARTS

    Directory of Open Access Journals (Sweden)

    Davorin Matanović

    1989-12-01

    Full Text Available Piston and cylinder are such parts in the mud pumps which cause the greatest expences due to the work stoppage of drilling rig. To reduce so caused expences it is necessary to produce spare parts of better quality. In determining the abrasion wear resistance for chosen materials, so called dry sand/rubber wheel abrasion test as an ASTM standard has been used (the paper is published in Croatian.

  20. Free Piston Double Diaphragm Shock Tube

    OpenAIRE

    OGURA, Eiji; FUNABIKI, Katsushi; SATO, Shunichi; ABE, Takashi; 小倉, 栄二; 船曳, 勝之; 佐藤, 俊逸; 安部, 隆士

    1997-01-01

    A free piston double diaphragm shock tube was newly developed for generation of high Mach number shock wave. Its characteristics was investigated for various operation parameters; such as a strength of the diaphragm at the end of the comparession tube, an initial pressure of low pressure tube, an initial pressure of medium pressure tube and the volume of compression tube. Under the restriction of fixed pressures for the driver high pressure tube (32×10^5Pa) and the low pressure tube (40Pa) in...

  1. Stability analysis of free piston Stirling engines

    Science.gov (United States)

    Bégot, Sylvie; Layes, Guillaume; Lanzetta, François; Nika, Philippe

    2013-03-01

    This paper presents a stability analysis of a free piston Stirling engine. The model and the detailed calculation of pressures losses are exposed. Stability of the machine is studied by the observation of the eigenvalues of the model matrix. Model validation based on the comparison with NASA experimental results is described. The influence of operational and construction parameters on performance and stability issues is exposed. The results show that most parameters that are beneficial for machine power seem to induce irregular mechanical characteristics with load, suggesting that self-sustained oscillations could be difficult to maintain and control.

  2. DESIGN AND CONSTRUCTION OF A HYDRAULIC PISTON

    OpenAIRE

    Santos De la Cruz, Eulogio; Rojas Lazo, Oswaldo; Yenque Dedios, Julio; Lavado Soto, Aurelio

    2014-01-01

    A hydraulic system project includes the design, materials selection and construction of the hydraulic piston, hydraulic circuit and the joint with the pump and its accesories. This equiment will be driven by the force of moving fluid, whose application is in the devices of machines, tools, printing, perforation, packing and others. El proyecto de un sistema hidráulico, comprende el diseño, selección de materiales y construcción del pistón hidráulico, circuito hidráulico y el ensamble con l...

  3. Quantum optomechanical piston engines powered by heat

    Science.gov (United States)

    Mari, A.; Farace, A.; Giovannetti, V.

    2015-09-01

    We study two different models of optomechanical systems where a temperature gradient between two radiation baths is exploited for inducing self-sustained coherent oscillations of a mechanical resonator. From a thermodynamic perspective, such systems represent quantum instances of self-contained thermal machines converting heat into a periodic mechanical motion and thus they can be interpreted as nano-scale analogues of macroscopic piston engines. Our models are potentially suitable for testing fundamental aspects of quantum thermodynamics in the laboratory and for applications in energy efficient nanotechnology.

  4. Quantum optomechanical piston engines powered by heat

    International Nuclear Information System (INIS)

    Mari, A; Farace, A; Giovannetti, V

    2015-01-01

    We study two different models of optomechanical systems where a temperature gradient between two radiation baths is exploited for inducing self-sustained coherent oscillations of a mechanical resonator. From a thermodynamic perspective, such systems represent quantum instances of self-contained thermal machines converting heat into a periodic mechanical motion and thus they can be interpreted as nano-scale analogues of macroscopic piston engines. Our models are potentially suitable for testing fundamental aspects of quantum thermodynamics in the laboratory and for applications in energy efficient nanotechnology. (paper)

  5. High Temperature Dry Sliding Friction and Wear Performance of Laser Cladding WC/Ni Composite Coating

    Directory of Open Access Journals (Sweden)

    YANG Jiao-xi

    2016-06-01

    Full Text Available Two different types of agglomerate and angular WC/Ni matrix composite coatings were deposited by laser cladding. The high temperature wear resistance of these composite coatings was tested with a ring-on-disc MMG-10 apparatus. The morphologies of the worn surfaces were observed using a scanning electron microscopy (SEM equipped with an energy dispersive spectroscopy (EDS for elemental composition. The results show that the high temperature wear resistance of the laser clad WC/Ni-based composite coatings is improved significantly with WC mass fraction increasing. The 60% agglomerate WC/Ni composite coating has optimal high temperature wear resistance. High temperature wear mechanism of 60% WC/Ni composite coating is from abrasive wear of low temperature into composite function of the oxidation wear and abrasive wear.

  6. Fatigue Analysis of the Piston Rod in a Kaplan Turbine Based on Crack Propagation under Unsteady Hydraulic Loads

    International Nuclear Information System (INIS)

    Liu, X; Luo, Y Y; Wang, Z W

    2014-01-01

    As an important component of the blade-control system in Kaplan turbines, piston rods are subjected to fluctuating forces transferred by the turbines blades from hydraulic pressure oscillations. Damage due to unsteady hydraulic loads might generate unexpected down time and high repair cost. In one running hydropower plant, the fracture failure of the piston rod was found twice at the same location. With the transient dynamic analysis, the retainer ring structure of the piston rod existed a relative high stress concentration. This predicted position of the stress concentration agreed well with the actual fracture position in the plant. However, the local strain approach was not able to explain why this position broke frequently. Since traditional structural fatigue analyses use a local stress strain approach to assess structural integrity, do not consider the effect of flaws which can significantly degrade structural life. Using linear elastic fracture mechanism (LEFM) approaches that include the effect of flaws is becoming common practice in many industries. In this research, a case involving a small semi-ellipse crack was taken into account at the stress concentration area, crack growth progress was calculated by FEM. The relationship between crack length and remaining life was obtained. The crack propagation path approximately agreed with the actual fracture section. The results showed that presence of the crack had significantly changed the local stress and strain distributions of the piston rod compared with non-flaw assumption

  7. Fatigue Analysis of the Piston Rod in a Kaplan Turbine Based on Crack Propagation under Unsteady Hydraulic Loads

    Science.gov (United States)

    Liu, X.; Y Luo, Y.; Wang, Z. W.

    2014-03-01

    As an important component of the blade-control system in Kaplan turbines, piston rods are subjected to fluctuating forces transferred by the turbines blades from hydraulic pressure oscillations. Damage due to unsteady hydraulic loads might generate unexpected down time and high repair cost. In one running hydropower plant, the fracture failure of the piston rod was found twice at the same location. With the transient dynamic analysis, the retainer ring structure of the piston rod existed a relative high stress concentration. This predicted position of the stress concentration agreed well with the actual fracture position in the plant. However, the local strain approach was not able to explain why this position broke frequently. Since traditional structural fatigue analyses use a local stress strain approach to assess structural integrity, do not consider the effect of flaws which can significantly degrade structural life. Using linear elastic fracture mechanism (LEFM) approaches that include the effect of flaws is becoming common practice in many industries. In this research, a case involving a small semi-ellipse crack was taken into account at the stress concentration area, crack growth progress was calculated by FEM. The relationship between crack length and remaining life was obtained. The crack propagation path approximately agreed with the actual fracture section. The results showed that presence of the crack had significantly changed the local stress and strain distributions of the piston rod compared with non-flaw assumption.

  8. Stable Operation and Electricity Generating Characteristics of a Single-Cylinder Free Piston Engine Linear Generator: Simulation and Experiments

    Directory of Open Access Journals (Sweden)

    Huihua Feng

    2015-01-01

    Full Text Available We present a novel design of a single-cylinder free piston engine linear generator (FPELG incorporating a linear motor as a rebound device. A systematic simulation model of this FPELG system was built containing a kinematic and dynamic model of the piston and mover, a magneto-electric model of the linear generator, a thermodynamic model of the single-cylinder engine, and a friction model between the piston ring and cylinder liner. Simulations were performed to understand the relationships between pre-set motor parameters and the running performance of the FPELG. From the simulation results, it was found that a motor rebound force with a parabolic profile had clear advantages over a force with a triangular profile, such as a higher running frequency and peak cylinder pressure, faster piston motion, etc. The rebound position and the amplitude of rebound force were also determined by simulations. The energy conversion characteristics of the generator were obtained from our FPELG test rig. The parameters of intake pressure, motor frequency, and load resistance were varied over certain ranges, and relationships among these three parameters were obtained. The electricity-generating characteristic parameters include output power and system efficiency, which can measure the quality of matching the controllable parameters. The output power can reach 25.9 W and the system efficiency can reach 13.7%. The results in terms of matching parameters and electricity-generating characteristics should be useful to future research in adapting these engines to various operating modes.

  9. LINC-NIRVANA piston control elements

    Science.gov (United States)

    Brix, Mario; Pott, Jörg-Uwe; Bertram, Thomas; Rost, Steffen; Borelli, Jose Luis; Herbst, Thomas M.; Kuerster, Martin; Rohloff, Ralf-Rainer

    2010-07-01

    We review the status of hardware developments related to the Linc-Nirvana optical path difference (OPD) control. The status of our telescope vibration measurements is given. We present the design concept of a feed-forward loop to damp the impact of telescope mirror vibrations on the OPD seen by Linc-Nirvana. At the focus of the article is a description of the actuator of the OPD control loop. The weight and vibration optimized construction of this actuator (aka piston mirror) and its mount has a complex dynamical behavior, which prevents classical PI feedback control from delivering fast and precise motion of the mirror surface. Therefore, an H-; optimized control strategy will be applied, custom designed for the piston mirror. The effort of realizing a custom controller on a DSP to drive the piezo is balanced by the outlook of achieving more than 5x faster servo bandwidths. The laboratory set-up to identify the system, and verify the closed loop control performance is presented. Our goal is to achieve 30 Hz closed-loop control bandwidth at a precision of 30 nm.

  10. Symmetry of the Adiabatic Condition in the Piston Problem

    Science.gov (United States)

    Anacleto, Joaquim; Ferreira, J. M.

    2011-01-01

    This study addresses a controversial issue in the adiabatic piston problem, namely that of the piston being adiabatic when it is fixed but no longer so when it can move freely. It is shown that this apparent contradiction arises from the usual definition of adiabatic condition. The issue is addressed here by requiring the adiabatic condition to be…

  11. NEW SOLUTIONS FOR THE CONSTRUCTION OF DRILLING PISTON PUMPS VALVES

    Directory of Open Access Journals (Sweden)

    Рима Явдатовна Абдюкова

    2016-08-01

    Full Text Available The article consideres theoretical and practical researches aimed to develop a new design of the valve pairs of drill piston pump. The result of the research is a new design of the drill piston pump valve according to the specified requirements.

  12. Fluid powered linear piston motor with harmonic coupling

    Science.gov (United States)

    Raymond, David W.

    2016-09-20

    A motor is disclosed that includes a module assembly including a piston that is axially cycled. The piston axial motion is coupled to torque couplers that convert the axial motion into rotary motion. The torque couplers are coupled to a rotor to rotate the rotor.

  13. Optical wear monitoring

    Science.gov (United States)

    Kidane, Getnet S; Desilva, Upul P.; He, Chengli; Ulerich, Nancy H.

    2016-07-26

    A gas turbine includes first and second parts having outer surfaces located adjacent to each other to create an interface where wear occurs. A wear probe is provided for monitoring wear of the outer surface of the first part, and includes an optical guide having first and second ends, wherein the first end is configured to be located flush with the outer surface of the first part. A fiber bundle includes first and second ends, the first end being located proximate to the second end of the optical guide. The fiber bundle includes a transmit fiber bundle comprising a first plurality of optical fibers coupled to a light source, and a receive fiber bundle coupled to a light detector and configured to detect reflected light. A processor is configured to determine a length of the optical guide based on the detected reflected light.

  14. Reduction of HCCI combustion noise through piston crown design

    DEFF Research Database (Denmark)

    Pedersen, Troels Dyhr; Schramm, Jesper

    2010-01-01

    . The largest and most consistent reduction in noise level was however achieved with a diesel bowl type piston. The increased surface area as well as the larger crevice volumes of the experimental piston crowns generally resulted in lower IMEP than the flat piston. While the crevice volumes can be reduced...... away from the engine. The experiments were conducted in a diesel engine that was run in HCCI combustion mode with a fixed quantity of DME as fuel. The results show that combustion knock is effectively suppressed by limiting the size of the volume in which the combustion occurs. Splitting...... the compression volume into four smaller volumes placed between the perimeter of the piston and the cylinder liner increased the noise to a higher level than that generated with a flat piston crown. This was due to resonance between the four volumes. Using eight volumes instead decreased the noise. The noise...

  15. CFD Analysis of an Axial Piston Pump

    OpenAIRE

    Kumar, Sushil

    2010-01-01

    Premi extraordinari doctorat curs 2009-2010, àmbit d’Enginyeria Industrial En el ámbito de la Oleohidráulica, las bombas de pistón poseen los diseños más sofisticados, de hecho, las bombas de pistones son las únicos capaces de trabajar a altas presiones, además de poseer el mejor rendimiento de todo el grupo de bombas existentes. Sin embargo, cabe señalar que todos los diseños de las bombas de pistón, se basan principalmente en la experiencia de los diseñadores, por lo tanto no existen her...

  16. The Effect of Uniform Background Flow on Vortex Ring Formation and Pinch-off

    Science.gov (United States)

    Krueger, Paul S.; Dabiri, John O.; Gharib, Morteza

    2002-11-01

    Experimental investigations of vortex ring formation are extended to include the effects of a uniform background flow, in a manner relevant to the locomotion of aquatic animals utilizing jet propulsion. Gharib et. al. [J. Fluid Mech. 360, 121 (1998)] generated vortex rings using a piston/cylinder apparatus with relatively large discharge times to demonstrate that the vortex ring at the leading edge of the jet attains its maximum circulation at a piston stroke-to-diameter ratio L/D of 4. This "formation number" is robust over a range of piston motions and cylinder boundary conditions, and can be explained in terms of the Kelvin-Benjamin variational principle. To determine the effect of background flow on formation number and pinch-off of the leading vortex ring, uniform co-flow is established in a large annulus surrounding the vortex generator. The ratio of co-flow velocity to piston velocity is varied between 0 and 1. In addition, the co-flow is initiated at times both before and after the start of vortex ring formation. We present results for stroke ratios L/D = 2 and L/D = 8, in order to discern effects of the co-flow on the leading vortex ring in isolation and in the presence of a trailing jet.

  17. Multiscale Modeling of Wear Degradation

    KAUST Repository

    Moraes, Alvaro; Ruggeri, Fabrizio; Tempone, Raul; Vilanova, Pedro

    2014-01-01

    Cylinder liners of diesel engines used for marine propulsion are naturally subjected to a wear process, and may fail when their wear exceeds a specified limit. Since failures often represent high economical costs, it is utterly important to predict

  18. Transient Characteristics of Free Piston Vuilleurnier Cycle Heat Pumps

    Science.gov (United States)

    Matsue, Junji; Fujimoto, Norioki; Shirai, Hiroyuki

    A dynamic analysis of a free piston Vuilleumier cycle heat pump was performed using a time-stepping integration method to investigate transient characteristics under power controlling. The nonlinear relationship between displacement and force for pistons was taken into account for the motion of reciprocating components. The force for pistons is mainly caused by the pressure change of working gas varying with piston displacements; moreover nonlinear viscous dissipative force due to the oscillating flow of working gas in heat exchangers and discontinuous damping force caused by solid friction at piston seals and rod seals are included. The displacements of pistons and pressure changes in the Vuilleumier cycle heat pump were integrated by an ideal isothermal thermodynamic relationship. It was assumed that the flow friction was proportional to the kinematic pressure of working gas, and that the solid friction at the seals was due to the functions of the working gas pressure and the tension of seal springs. In order to investigate the transient characteristics of a proposed free piston Vuilleumier cycle heat pump machine when hot-side working gas temperatures and alternate force were changed, some calculations were performed and discussed. These calculation results make clear transient characteristics at starting and power controlling. It was further found that only a small amount of starter power is required in particular conditions. During controlling, the machine becomes unstable when there is ar elatively large reduction in cooling or heating power. Therefore, an auxiliary device is additionally needed to obtain stable operation, such as al inear motor.

  19. Loss terms in free-piston Stirling engine models

    Science.gov (United States)

    Gordon, Lloyd B.

    1992-01-01

    Various models for free piston Stirling engines are reviewed. Initial models were developed primarily for design purposes and to predict operating parameters, especially efficiency. More recently, however, such models have been used to predict engine stability. Free piston Stirling engines have no kinematic constraints and stability may not only be sensitive to the load, but also to various nonlinear loss and spring constraints. The present understanding is reviewed of various loss mechanisms for free piston Stirling engines and how they have been incorporated into engine models is discussed.

  20. The Casimir effect for pistons with transmittal boundary conditions

    Science.gov (United States)

    Fucci, Guglielmo

    2017-11-01

    This work focuses on the analysis of the Casimir effect for pistons subject to transmittal boundary conditions. In particular we consider, as piston configuration, a direct product manifold of the type I × N where I is a closed interval of the real line and N is a smooth compact Riemannian manifold. By utilizing the spectral zeta function regularization technique, we compute the Casimir energy of the system and the Casimir force acting on the piston. Explicit results for the force are provided when the manifold N is a d-dimensional sphere.

  1. Vortex Ring Dynamics in Radially Confined Domains

    Science.gov (United States)

    Stewart, Kelley; Niebel, Casandra; Jung, Sunghwan; Vlachos, Pavlos

    2010-11-01

    Vortex ring dynamics have been studied extensively in semi-infinite quiescent volumes. However, very little is known about vortex-ring formation in wall-bounded domains where vortex wall interaction will affect both the vortex ring pinch-off and propagation velocity. This study addresses this limitation and studies vortex formation in radially confined domains to analyze the affect of vortex-ring wall interaction on the formation and propagation of the vortex ring. Vortex rings were produced using a pneumatically driven piston cylinder arrangement and were ejected into a long cylindrical tube which defined the confined downstream domain. A range of confinement domains were studied with varying confinement diameters Velocity field measurements were performed using planar Time Resolved Digital Particle Image Velocimetry (TRDPIV) and were processed using an in-house developed cross-correlation PIV algorithm. The experimental analysis was used to facilitate the development of a theoretical model to predict the variations in vortex ring circulation over time within confined domains.

  2. ring system

    African Journals Online (AJOL)

    1,3,2-DIAZABORACYCLOALKANE. RING SYSTEM. Negussie Retta" and Robert H. Neilson. 'Department of Chemistry, Addis Ababa University, P.O. Box 1176, Addis Ababa, Ethiopia. Department of Chemistry, Texas Christian University.

  3. Planetary Rings

    Science.gov (United States)

    Nicholson, P. D.

    2001-11-01

    A revolution in the studies in planetary rings studies occurred in the period 1977--1981, with the serendipitous discovery of the narrow, dark rings of Uranus, the first Voyager images of the tenuous jovian ring system, and the many spectacular images returned during the twin Voyager flybys of Saturn. In subsequent years, ground-based stellar occultations, HST observations, and the Voyager flybys of Uranus (1986) and Neptune (1989), as well as a handful of Galileo images, provided much additional information. Along with the completely unsuspected wealth of detail these observations revealed came an unwelcome problem: are the rings ancient or are we privileged to live at a special time in history? The answer to this still-vexing question may lie in the complex gravitational interactions recent studies have revealed between the rings and their retinues of attendant satellites. Among the four known ring systems, we see elegant examples of Lindblad and corotation resonances (first invoked in the context of galactic disks), electromagnetic resonances, spiral density waves and bending waves, narrow ringlets which exhibit internal modes due to collective instabilities, sharp-edged gaps maintained via tidal torques from embedded moonlets, and tenuous dust belts created by meteoroid impact onto parent bodies. Perhaps most puzzling is Saturn's multi-stranded, clumpy F ring, which continues to defy a simple explanation 20 years after it was first glimpsed in grainy images taken by Pioneer 11. Voyager and HST images reveal a complex, probably chaotic, dynamical interaction between unseen parent bodies within this ring and its two shepherd satellites, Pandora and Prometheus. The work described here reflects contributions by Joe Burns, Jeff Cuzzi, Luke Dones, Dick French, Peter Goldreich, Colleen McGhee, Carolyn Porco, Mark Showalter, and Bruno Sicardy, as well as those of the author. This research has been supported by NASA's Planetary Geology and Geophysics program and the

  4. Experimental Evaluation of the Free Piston Engine - Linear Alternator (FPLA)

    Energy Technology Data Exchange (ETDEWEB)

    Leick, Michael T. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Moses, Ronald W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-03-01

    This report describes the experimental evaluation of a prototype free piston engine - linear alternator (FPLA) system developed at Sandia National Laboratories. The opposed piston design wa developed to investigate its potential for use in hybrid electric vehicles (HEVs). The system is mechanically simple with two - stroke uniflow scavenging for gas exchange and timed port fuel injection for fuel delivery, i.e. no complex valving. Electrical power is extracted from piston motion through linear alternators wh ich also provide a means for passive piston synchronization through electromagnetic coupling. In an HEV application, this electrical power would be used to charge the batteries. The engine - alternator system was designed, assembled and operated over a 2 - year period at Sandia National Laboratories in Livermore, CA. This report primarily contains a description of the as - built system, modifications to the system to enable better performance, and experimental results from start - up, motoring, and hydrogen combus tion tests.

  5. Pump having pistons and valves made of electroactive actuators

    Science.gov (United States)

    Bar-Cohen, Yoseph (Inventor)

    1997-01-01

    The present invention provides a pump for inducing a displacement of a fluid from a first medium to a second medium, including a conduit coupled to the first and second media, a transducing material piston defining a pump chamber in the conduit and being transversely displaceable for increasing a volume of the chamber to extract the fluid from the first medium to the chamber and for decreasing the chamber volume to force the fluid from the chamber to the second medium, a first transducing material valve mounted in the conduit between the piston and the first medium and being transversely displaceable from a closed position to an open position to admit the fluid to the chamber, and control means for changing a first field applied to the piston to displace the piston for changing the chamber volume and for changing a second field applied to the first valve to change the position of the first valve.

  6. Piston pump and method of reducing vapor lock

    Science.gov (United States)

    Phillips, Benjamin A.; Harvey, Michael N.

    2000-02-15

    A pump includes a housing defining a cavity, at least one bore, a bore inlet, and a bore outlet. The bore extends from the cavity to the outlet and the inlet communicates with the bore at a position between the cavity and the outlet. A crankshaft is mounted in supports and has an eccentric portion disposed in the cavity. The eccentric portion is coupled to a piston so that rotation of the crankshaft reciprocates the piston in the bore between a discharge position an intake position. The bore may be offset from an axis of rotation to reduce bending of the piston during crankshaft rotation. During assembly of the pump, separate parts of the housing can be connected together to facilitate installation of internal pumping components. Also disclosed is a method of reducing vapor lock by mixing vapor and liquid portions of a substance and introducing the mixture into a piston bore.

  7. Dynamics of a massive piston in an ideal gas

    International Nuclear Information System (INIS)

    Chernov, N I; Lebowitz, J L; Sinai, Yakov G

    2002-01-01

    This survey is a study of a dynamical system consisting of a massive piston in a cubic container of large size L filled with an ideal gas. The piston has mass M∼L 2 and undergoes elastic collisions with N∼L 3 non-interacting gas particles of mass m=1. It is found that under suitable initial conditions there is a scaling regime with time and space scaled by L in which the motion of the piston and the one-particle distribution of the gas satisfy autonomous coupled equations (hydrodynamic equations) such that in the limit L→∞ the mechanical trajectory of the piston converges in probability to the solution of the hydrodynamic equations for a certain period of time. There is also a heuristic discussion of the dynamics of the system on longer intervals of time

  8. optimised intake stroke analysis for flat and dome head pistons

    African Journals Online (AJOL)

    user

    The piston models were meshed using tetrahedral mesh of base size 0.001m. ... applied to simulate the actual intake stroke process for normal operating conditions and initial conditions. ... simulation of optimization characteristics has followed.

  9. Structural design of Stirling engine with free pistons

    Science.gov (United States)

    Matusov, Jozef; Gavlas, Stanislav; Malcho, Milan

    2014-08-01

    Stirling engine is a device that converts thermal energy to mechanical work, which is mostly used to drive a generator of electricity. Advantage of Stirling engine is that it works with closed-cycle, where working medium is regularly cooled and heated, which acts on the working piston. This engine can be made in three modifications - alpha, beta, gamma. This paper discusses the design of the gamma Stirling engine with free pistons.

  10. Ensuring Steady Operation of Free-Piston Generator

    Directory of Open Access Journals (Sweden)

    Pavel Nemecek

    2006-02-01

    Full Text Available This paper describes Free-Piston Generator (FPG model and its control for achieving steady operation. A FPG is a special type of combustion engine representing a new approach concerning the conversion of the chemical energy of hydrocarbon fuel into electrical energy. Unlike conventional engines, this type of engine does not use a crankshaft, and generates electric energy directly by a linear movement of pistons.

  11. Feasibility of free piston generation unit for electrical power provision

    Energy Technology Data Exchange (ETDEWEB)

    Harvey, R.; Roskilly, A.; Shaw, R.; French, C. [Newcastle Univ. (United Kingdom)

    2000-07-01

    Free piston linear engines offer the capability of providing power without the need to convert reciprocating motion into rotary motion. This allows for the utilisation of higher peak pressures during the combustion process and thus improves efficiency. The objective of this paper is to outline the potential benefits of a Free Piston Generator (FPG) and discuss the feasibility of this technology as a potential platform for electrical power provision. (authors)

  12. Radial-piston pump for drive of test machines

    Science.gov (United States)

    Nizhegorodov, A. I.; Gavrilin, A. N.; Moyzes, B. B.; Cherkasov, A. I.; Zharkevich, O. M.; Zhetessova, G. S.; Savelyeva, N. A.

    2018-01-01

    The article reviews the development of radial-piston pump with phase control and alternating-flow mode for seismic-testing platforms and other test machines. The prospects for use of the developed device are proved. It is noted that the method of frequency modulation with the detection of the natural frequencies is easily realized by using the radial-piston pump. The prospects of further research are given proof.

  13. Ensuring Steady Operation of Free-Piston Generator

    OpenAIRE

    Pavel Nemecek

    2006-01-01

    This paper describes Free-Piston Generator (FPG) model and its control for achieving steady operation. A FPG is a special type of combustion engine representing a new approach concerning the conversion of the chemical energy of hydrocarbon fuel into electrical energy. Unlike conventional engines, this type of engine does not use a crankshaft, and generates electric energy directly by a linear movement of pistons.

  14. A rolling-gliding wear simulator for the investigation of tribological material pairings for application in total knee arthroplasty

    OpenAIRE

    Richter, Berna I; Ostermeier, Sven; Turger, Anke; Denkena, Berend; Hurschler, Christof

    2010-01-01

    Abstract Background Material wear testing is an important technique in the development and evaluation of materials for use in implant for total knee arthroplasty. Since a knee joint induces a complex rolling-gliding movement, standardised material wear testing devices such as Pin-on-Disc or Ring-on-Disc testers are suitable to only a limited extent because they generate pure gliding motion only. Methods A rolling-gliding wear simulator was thus designed, constructed and implemented, which sim...

  15. Nuclear piston engine and pulsed gaseous core reactor power systems

    International Nuclear Information System (INIS)

    Dugan, E.T.

    1976-01-01

    The investigated nuclear piston engines consist of a pulsed, gaseous core reactor enclosed by a moderating-reflecting cylinder and piston assembly and operate on a thermodynamic cycle similar to the internal combustion engine. The primary working fluid is a mixture of uranium hexafluoride, UF 6 , and helium, He, gases. Highly enriched UF 6 gas is the reactor fuel. The helium is added to enhance the thermodynamic and heat transfer characteristics of the primary working fluid and also to provide a neutron flux flattening effect in the cylindrical core. Two and four-stroke engines have been studied in which a neutron source is the counterpart of the sparkplug in the internal combustion engine. The piston motions which have been investigated include pure simple harmonic, simple harmonic with dwell periods, and simple harmonic in combination with non-simple harmonic motion. The results of the conducted investigations indicate good performance potential for the nuclear piston engine with overall efficiencies of as high as 50 percent for nuclear piston engine power generating units of from 10 to 50 Mw(e) capacity. Larger plants can be conceptually designed by increasing the number of pistons, with the mechanical complexity and physical size as the probable limiting factors. The primary uses for such power systems would be for small mobile and fixed ground-based power generation (especially for peaking units for electrical utilities) and also for nautical propulsion and ship power

  16. Fluid Dynamics in Rotary Piston Blood Pumps.

    Science.gov (United States)

    Wappenschmidt, Johannes; Sonntag, Simon J; Buesen, Martin; Gross-Hardt, Sascha; Kaufmann, Tim; Schmitz-Rode, Thomas; Autschbach, Ruediger; Goetzenich, Andreas

    2017-03-01

    Mechanical circulatory support can maintain a sufficient blood circulation if the native heart is failing. The first implantable devices were displacement pumps with membranes. They were able to provide a sufficient blood flow, yet, were limited because of size and low durability. Rotary pumps have resolved these technical drawbacks, enabled a growing number of mechanical circulatory support therapy and a safer application. However, clinical complications like gastrointestinal bleeding, aortic insufficiency, thromboembolic complications, and impaired renal function are observed with their application. This is traced back to their working principle with attenuated or non-pulsatile flow and high shear stress. Rotary piston pumps potentially merge the benefits of available pump types and seem to avoid their complications. However, a profound assessment and their development requires the knowledge of the flow characteristics. This study aimed at their investigation. A functional model was manufactured and investigated with particle image velocimetry. Furthermore, a fluid-structure interaction computational simulation was established to extend the laboratory capabilities. The numerical results precisely converged with the laboratory measurements. Thus, the in silico model enabled the investigation of relevant areas like gap flows that were hardly feasible with laboratory means. Moreover, an economic method for the investigation of design variations was established.

  17. Adiabatic liquid piston compressed air energy storage

    Energy Technology Data Exchange (ETDEWEB)

    Petersen, Tage [Danish Technological Institute, Aarhus (Denmark); Elmegaard, B. [Technical Univ. of Denmark. DTU Mechanical Engineering, Kgs. Lyngby (Denmark); Schroeder Pedersen, A. [Technical Univ. of Denmark. DTU Energy Conversion, Risoe Campus, Roskilde (Denmark)

    2013-01-15

    This project investigates the potential of a Compressed Air Energy Storage system (CAES system). CAES systems are used to store mechanical energy in the form of compressed air. The systems use electricity to drive the compressor at times of low electricity demand with the purpose of converting the mechanical energy into electricity at times of high electricity demand. Two such systems are currently in operation; one in Germany (Huntorf) and one in the USA (Macintosh, Alabama). In both cases, an underground cavern is used as a pressure vessel for the storage of the compressed air. Both systems are in the range of 100 MW electrical power output with several hours of production stored as compressed air. In this range, enormous volumes are required, which make underground caverns the only economical way to design the pressure vessel. Both systems use axial turbine compressors to compress air when charging the system. The compression leads to a significant increase in temperature, and the heat generated is dumped into the ambient. This energy loss results in a low efficiency of the system, and when expanding the air, the expansion leads to a temperature drop reducing the mechanical output of the expansion turbines. To overcome this, fuel is burned to heat up the air prior to expansion. The fuel consumption causes a significant cost for the storage. Several suggestions have been made to store compression heat for later use during expansion and thereby avoid the use of fuel (so called Adiabatic CAES units), but no such units are in operation at present. The CAES system investigated in this project uses a different approach to avoid compression heat loss. The system uses a pre-compressed pressure vessel full of air. A liquid is pumped into the bottom of the vessel when charging and the same liquid is withdrawn through a turbine when discharging. In this case, the liquid works effectively as a piston compressing the gas in the vessel, hence the name &apos

  18. Experimental confirmation of the design to minimize vibration and wear in 61-pin wire-spaced EBR-II subassemblies

    International Nuclear Information System (INIS)

    Fukuda, S.K.

    1978-05-01

    Examinations of HEDL 61-pin subassemblies comprised of 5.84 mm (0.230) inch diameter mixed-oxide fuel pins with 1.02 mm (0.040'') diameter spacer wire (PNL-9, -10, -11, HEDL-N-E, -N-F), showed severe cladding and spacer wire wear after irradiation in EBR-II. A comparison of a large number of design, fabrication, and irradiation parameters for all of the HEDL subassemblies indicated that the porosity per ring of fuel pins correlated significantly with the occurrence of wear on the fuel pins. The porosity per ring is the clearance between the flat-to-flat pin bundle dimension and the inner hex can dimension divided by the number of hexagonal fuel pin rings in the subassembly. The porosity per ring for PNL-9, -10, -11 and HEDL-N-E was 0.15 mm/ring (6 mils/ring) and 0.18 mm/ring (7 mils/ring) for the HEDL-N-F subassembly. Since the original FTR subassembly design had a porosity/ring spread of 0.04 mm/ring to 0.16 mm/ring (1.67 to 6.11 mils/ring) an additional series of irradiation tests was conducted to confirm that a tighter fuel pin bundle would eliminate the wear

  19. On the Influence of Piston and Cylinder Density in Tribodynamics of a Radial Piston Digital Fluid Power Displacement Motor

    DEFF Research Database (Denmark)

    Johansen, Per; Roemer, Daniel Beck; Andersen, Torben O.

    2015-01-01

    -stroke displacement simulations are used as basis for the parametric analysis. From the parametric analysis a change, in the minimum film thickness as function of piston and cylinder density, is shown for certain operating modes of the digital fluid power displacement motor. This indicate a need for careful....... In this paper the influence of the inertia term on the lubrication gaps of a radial piston motor are studied by a parametric analysis of the piston and cylinder density in a multibody tribodynamic simulation model. The motor is modeled as a digital fluid power displacement machine and a series of full...... assessment of the applicability, of the force balance condition, if it is used in multibody tribodynamic simulations of radial piston digital fluid power displacement motors....

  20. Preliminary results from a four-working space, double-acting piston, Stirling engine controls model

    Science.gov (United States)

    Daniele, C. J.; Lorenzo, C. F.

    1980-01-01

    A four working space, double acting piston, Stirling engine simulation is being developed for controls studies. The development method is to construct two simulations, one for detailed fluid behavior, and a second model with simple fluid behaviour but containing the four working space aspects and engine inertias, validate these models separately, then upgrade the four working space model by incorporating the detailed fluid behaviour model for all four working spaces. The single working space (SWS) model contains the detailed fluid dynamics. It has seven control volumes in which continuity, energy, and pressure loss effects are simulated. Comparison of the SWS model with experimental data shows reasonable agreement in net power versus speed characteristics for various mean pressure levels in the working space. The four working space (FWS) model was built to observe the behaviour of the whole engine. The drive dynamics and vehicle inertia effects are simulated. To reduce calculation time, only three volumes are used in each working space and the gas temperature are fixed (no energy equation). Comparison of the FWS model predicted power with experimental data shows reasonable agreement. Since all four working spaces are simulated, the unique capabilities of the model are exercised to look at working fluid supply transients, short circuit transients, and piston ring leakage effects.

  1. Storage Rings

    International Nuclear Information System (INIS)

    Fischer, W.

    2010-01-01

    Storage rings are circular machines that store particle beams at a constant energy. Beams are stored in rings without acceleration for a number of reasons (Tab. 1). Storage rings are used in high-energy, nuclear, atomic, and molecular physics, as well as for experiments in chemistry, material and life sciences. Parameters for storage rings such as particle species, energy, beam intensity, beam size, and store time vary widely depending on the application. The beam must be injected into a storage ring but may not be extracted (Fig. 1). Accelerator rings such as synchrotrons are used as storage rings before and after acceleration. Particles stored in rings include electrons and positrons; muons; protons and anti-protons; neutrons; light and heavy, positive and negative, atomic ions of various charge states; molecular and cluster ions, and neutral polar molecules. Spin polarized beams of electrons, positrons, and protons were stored. The kinetic energy of the stored particles ranges from 10 -6 eV to 3.5 x 10 12 eV (LHC, 7 x 10 12 eV planned), the number of stored particles from one (ESR) to 1015 (ISR). To store beam in rings requires bending (dipoles) and transverse focusing (quadrupoles). Higher order multipoles are used to correct chromatic aberrations, to suppress instabilities, and to compensate for nonlinear field errors of dipoles and quadrupoles. Magnetic multipole functions can be combined in magnets. Beams are stored bunched with radio frequency systems, and unbunched. The magnetic lattice and radio frequency system are designed to ensure the stability of transverse and longitudinal motion. New technologies allow for better storage rings. With strong focusing the beam pipe dimensions became much smaller than previously possible. For a given circumference superconducting magnets make higher energies possible, and superconducting radio frequency systems allow for efficient replenishment of synchrotron radiation losses of large current electron or positron beams

  2. Effect of oil around the pin boss bearing on bearing friction force; Piston pin jikuukebu kinbo no junkatsuyu ga masatsuryoku ni oyobosu eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Takiguchi, M; Suhara, T; Ato, S; Someya, T [Musashi Institute of Technology, Tokyo (Japan)

    1997-10-01

    Piston pin bearings are engine parts placed under severe lubricating condition because of the high unit load and temperature and the low sliding speeds. Therefore, they are vulnerable to many lubrication problems such as abnormal wear, scuffs and seizures. In our recent study, the bearing friction were measured using a original measuring device and it was found out that the lubricating conditions of piston pin boss bearings are non-fluid lubrication due to the oil starvation. In this study, we have also measured the lubricating oil behavior around the pin boss bearing using a special cylinder with glass window, and analyzed the relationship between the friction force and the oil behavior at the pin boss bearings in a actual operating gasoline engine. 2 refs., 9 figs., 1 tab.

  3. Topological rings

    CERN Document Server

    Warner, S

    1993-01-01

    This text brings the reader to the frontiers of current research in topological rings. The exercises illustrate many results and theorems while a comprehensive bibliography is also included. The book is aimed at those readers acquainted with some very basic point-set topology and algebra, as normally presented in semester courses at the beginning graduate level or even at the advanced undergraduate level. Familiarity with Hausdorff, metric, compact and locally compact spaces and basic properties of continuous functions, also with groups, rings, fields, vector spaces and modules, and with Zorn''s Lemma, is also expected.

  4. Ring accelerators

    International Nuclear Information System (INIS)

    Gisler, G.; Faehl, R.

    1983-01-01

    We present two-dimensional simulations in (r-z) and r-theta) cylinderical geometries of imploding-liner-driven accelerators of rings of charged particles. We address issues of azimuthal and longitudinal stability of the rings. We discuss self-trapping designs in which beam injection and extraction is aided by means of external cusp fields. Our simulations are done with the 2-1/2-D particle-in-cell plasma simulation code CLINER, which combines collisionless, electromagnetic PIC capabilities with a quasi-MHD finite element package

  5. MOCEAN SURF WEAR -MALLISTO

    OpenAIRE

    Lehtovaara, Hanna

    2013-01-01

    Surffi on urheilulaji, jossa kuljetaan aallon päällä surffilaudalla. Surffaus on lähtöisin Polynesiasta, mutta nykypäivänä surffausta harrastetaan ympäri maailmaa. Opinnäytetyö käsittelee surf wear -malliston suunnittelua ja toteuttamista omalle toi-minimelle Mocean. Työn tavoitteena oli suunnitella toimiva, mutta myös trendikäs mallisto naissurffareille. Mallisto sisältää bikineitä, surffipaitoja legginsejä ja shortseja. Mallisto on suunniteltu naissurffareille, jotka surffaavat lämpimis...

  6. Wear Particle Atlas. Revised

    Science.gov (United States)

    1982-06-28

    Superintendent NOTICE Reproduction of this document in any form by other than naval activities is/Jotbvlhorized except isys^iedcil approval of the SecretarWof...constant. •.■, -1 "if -w \\ SÄNPLlWi V» IVf Figure 3.1.1.1 Simplified Oil Path Ref 21 Scott. D, McCullagh. PJ and Campbell GW Condition Monitoring...Wear Particles in Human Synovial Fluid Arthritis and Rheumatism, 24 (1981) 912-918 30 Evans. C H .andTew W P isolationof Biological Materials

  7. Modernizing the 5G 100/8 piston compressor by means of directly streaming valves

    Energy Technology Data Exchange (ETDEWEB)

    Tsvetanov, Ts.; Stoyanov, I.

    1988-02-01

    Deals with 5G 100/8 air compressors which, despite long service and lack of spare parts, are still widely used in Bulgarian underground coal mines. K-4-10 ring-type valves are in particularly short supply; maintenance engineers have been forced to modify the compresors. Initially, Bulgarian KP-3.1 valves with direct air streaming replaced the K-4-10; these were later replaced by PIK-220 and PIK-220A valves. Tests on overhauled compressors have shown that replacing the KP-3.1 with the PIK-220 or PIK-220A can result in a saving of up to 100,000 kWh of electricity per compressor. Details of reconstruction and testing of piston compressors are included. 10 refs.

  8. Gas action effect of free piston Stirling engine

    International Nuclear Information System (INIS)

    Mou, Jian; Li, Wei; Li, Jinze; Hong, Guotong

    2016-01-01

    Highlights: • The gas action effect is analyzed by the method of rotation vector decomposition. • Gas force can be decomposed into motivation force and spring or inertia force. • The optimal phase angles of displacements to pressure wave have been found. - Abstract: Gas action effect of free piston Stirling engine (FPSE) is very important to solve the key problem of start-up and find the way to increase its efficiency. The gas force is a key force to free FPSE. In this paper, the gas action effect has been analyzed by the method of rotation vector decomposition. It is found that the gas forces of piston and displacer can be decomposed into two forces, one component acts as motivation force resisting the damping force to output power, the other acts as spring force or inertia force according to the phase angle of pressure wave to displacements of the displacer and piston. Only when the motivation components of both piston and displacer resist their damping forces, will the FPSE be start-up and work stably. And only when the spring force is approximately equal to inertia force of piston, will the piston need the smallest gas spring force and nearly all the gas force be put for the alternator, meanwhile the engine outputs the maximum work. In the perfect condition, the optimal phase angle of the reciprocating movements of the displacer and piston ahead of the pressure wave are 180° and 90° respectively. The analyses above are verified by a series of experiments on a FPSE designed by our laboratory.

  9. Wear of polymers and composites

    CERN Document Server

    Abdelbary, Ahmed

    2015-01-01

    In the field of tribology, the wear behaviour of polymers and composite materials is considered a highly non-linear phenomenon. Wear of Polymers and Composites introduces fundamentals of polymers and composites tribology. The book suggests a new approach to explore the effect of applied load and surface defects on the fatigue wear behaviour of polymers, using a new tribometer and thorough experiments. It discusses effects of surface cracks, under different static and cyclic loading parameters on wear, and presents an intelligent algorithm, in the form of a neural network, to map the relations

  10. Friction and wear calculation methods

    CERN Document Server

    Kragelsky, I V; Kombalov, V S

    1981-01-01

    Friction and Wear: Calculation Methods provides an introduction to the main theories of a new branch of mechanics known as """"contact interaction of solids in relative motion."""" This branch is closely bound up with other sciences, especially physics and chemistry. The book analyzes the nature of friction and wear, and some theoretical relationships that link the characteristics of the processes and the properties of the contacting bodies essential for practical application of the theories in calculating friction forces and wear values. The effect of the environment on friction and wear is a

  11. Oxygen fugacity and piston cylinder capsule assemblies

    Science.gov (United States)

    Jakobsson, S.

    2011-12-01

    A double capsule assembly designed to control oxygen fugacity in piston cylinder experiments has been tested at 1200 °C and 10 kbar. The assembly consists of an outer Pt-capsule containing a solid buffer (Ni-NiO or Co-CoO plus H2O) and an inner AuPd-capsule containing the sample, H2O and a Pt-wire. To prevent direct contact with the buffer phases the AuPd-capsule is embedded in finely ground Al2O3 along with some coarser, fractured Al2O3 facilitating fluid inclusion formation. No water loss is observed in the sample even after 48 hrs but a slight increase in water content is observed in longer duration runs due to oxygen and hydrogen diffusion into the AuPd-capsule. Carbon from the furnace also diffuses through the outer Pt-capsule but reacts with H2O in the outer capsule to form CO2 and never reaches the inner capsule. Oxygen fugacity of runs in equilibrium with the Ni-NiO and Co-CoO buffers was measured by analyzing the Fe content of the Pt-wire in the sample1 and by analyzing Fe dissolved in the AuPd capsule2. The second method gives values that are in good agreement with established buffer whereas results from the first method are one half to one log units higher than the established values. References 1. E. Medard, C. A. McCammon, J. A. Barr, T. L. Grove, Am. Mineral. 93, 1838 (2008). 2. J. Barr, T. Grove, Contrib. Mineral. Petrol. 160, 631 (2010)

  12. Wear-resistant ball bearings for space applications

    Science.gov (United States)

    Boving, H.; Hintermann, H. E.; Hanni, W.; Bondivenne, E.; Boeto, M.; Conde, E.

    1977-01-01

    Ball bearings consisting of steel parts of which the rings are coated with hard, wear resistant, chemical vapor deposited TiC are described. Experiments conducted in ultrahigh vacuum, using cages of various materials with self-lubricating properties, show that such bearings are suitable for space applications. The results of laboratory tests on the ESA Meteosat Radiometer Focalizing mechanism, which contains six coated bearings, are summarized.

  13. Ring interferometry

    CERN Document Server

    Malykin, Grigorii B; Zhurov, Alexei

    2013-01-01

    This monograph is devoted to the creation of a comprehensive formalism for quantitative description of polarized modes' linear interaction in modern single-mode optic fibers. The theory of random connections between polarized modes, developed in the monograph, allows calculations of the zero shift deviations for a fiber ring interferometer. The monograph addresses also the

  14. Instantaneous heat flux flowing into piston top-land surface of D.I. diesel engine; DI diesel kikan no piston top land bu eno shunji netsuryusoku

    Energy Technology Data Exchange (ETDEWEB)

    Taguma, M [Zexel Corp., Tokyo (Japan); Inui, M; Enomoto, Y; Hagihara, Y [Musashi Institute of Technology, Tokyo (Japan); Koyama, T [Mitsubishi Motors Co., Tokyo (Japan)

    1997-10-01

    The thermal loads of the piston top-land surface in D.I. diesel engine during actual operation is not cleared. The authors fixed thin film thermocouples in the top-land center of a standard piston, and measured the instantaneous heat fluxes in that place. As a result, the authors made clear the thermal loads of the piston top-land surface in a cycle, and confirmed presence of the flame inflow to the piston top-land center. In addition, the authors made clear the thermal loads of the piston top-land surface in EGR operation. 4 refs., 8 figs.

  15. Assessment of wear facets produced by the ACTA wear machine

    DEFF Research Database (Denmark)

    Benetti, Ana R; Larsen, Liselotte; Dowling, Adam H

    2016-01-01

    . The mean wear depth was measured using the traditionally employed 2D and compared with the 3D profilometric (digital) techniques. Data were submitted to analyses of variance, Tukey's post hoc tests and Independent Samples Student's t-tests (where appropriate) at p...OBJECTIVE: To investigate the use of a three-dimensional (3D) digital scanning method in determining the accuracy of the wear performance parameters of resin-based composites (RBCs) determined using a two-dimensional (2D) analogue methodology following in-vitro testing in an Academisch Centrum...... for Tandheelkunde Amsterdam (ACTA) wear machine. METHODS: Specimens compatible with the compartments of the ACTA wear machine specimen wheel (n=10) were prepared from one commercial and four experimental RBCs. The RBC specimens were rotated against an antagonist wheel in a food-like slurry for 220,000 wear cycles...

  16. Free-piston reciprocating cryogenic expander utilizing phase controller

    Science.gov (United States)

    Cha, Jeongmin; Park, Jiho; Kim, Kyungjoong; Jeong, Sangkwon

    2017-02-01

    In a free-piston expander which eliminates mechanical linkages, a prescribed behaviour of the free-piston movement is the key to an expander performance. In this paper, we have proposed an idea of reducing complexity of the free-piston expander. It is to replace both multiple solenoid valves and reservoirs that are indispensable in a previous machine with a combination of a single orifice-reservoir assembly. It functions as a phase controller like that of a pulse tube refrigerator so that it generates time-delay of pressure variation between the warm-end and the reservoir resulting in the intended expansion of the cold-end volume down to the pre-set reservoir pressure. The modeling of this unique free-piston reciprocating expander utilizing phase controller is developed to understand and predict the performance of the new-type expander. Additionally, the operating parameters are analysed at the specified conditions to enable one to develop a more efficient free-piston type cryogenic expander.

  17. 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.

  18. The provision of clearances accuracy in piston - cylinder mating

    Science.gov (United States)

    Glukhov, V. I.; Shalay, V. V.

    2017-08-01

    The paper is aimed at increasing the quality of the pumping equipment in oil and gas industry. The main purpose of the study is to stabilize maximum values of productivity and durability of the pumping equipment based on the selective assembly of the cylinder-piston kinematic mating by optimization criterion. It is shown that the minimum clearance in the piston-cylinder mating is formed by maximum material dimensions. It is proved that maximum material dimensions are characterized by their own laws of distribution within the tolerance limits for the diameters of the cylinder internal mirror and the outer cylindrical surface of the piston. At that, their dispersion zones should be divided into size groups with a group tolerance equal to half the tolerance for the minimum clearance. The techniques for measuring the material dimensions - the smallest cylinder diameter and the largest piston diameter according to the envelope condition - are developed for sorting them into size groups. Reliable control of the dimensions precision ensures optimal minimum clearances of the piston-cylinder mating in all the size groups of the pumping equipment, necessary for increasing the equipment productivity and durability during the production, operation and repair processes.

  19. Three-dimensional Casimir piston for massive scalar fields

    International Nuclear Information System (INIS)

    Lim, S.C.; Teo, L.P.

    2009-01-01

    We consider Casimir force acting on a three-dimensional rectangular piston due to a massive scalar field subject to periodic, Dirichlet and Neumann boundary conditions. Exponential cut-off method is used to derive the Casimir energy. It is shown that the divergent terms do not contribute to the Casimir force acting on the piston, thus render a finite well-defined Casimir force acting on the piston. Explicit expressions for the total Casimir force acting on the piston is derived, which show that the Casimir force is always attractive for all the different boundary conditions considered. As a function of a - the distance from the piston to the opposite wall, it is found that the magnitude of the Casimir force behaves like 1/a 4 when a→0 + and decays exponentially when a→∞. Moreover, the magnitude of the Casimir force is always a decreasing function of a. On the other hand, passing from massless to massive, we find that the effect of the mass is insignificant when a is small, but the magnitude of the force is decreased for large a in the massive case.

  20. New monobolt piston design for large engines; Neues Monobolt-Kolbendesign fuer Grossmotoren

    Energy Technology Data Exchange (ETDEWEB)

    Estrum, T.; Kortas, J.; Geissler, C. [Mahle GmbH, Markgroeningen (Germany). Profitcenter Grossmotorenkomponenten

    2008-07-15

    High-load pistons for modern, powerful large diesel and gas engines require increasingly more compact and lightweight designs. Due to the low installation height, less room remains for the required screw length in traditional large-bore piston designs, where the piston crown is screwed to the piston skirt. With the new development of the compact monobolt piston design, the Mahle Large Engine Components Profit Center succeeded in satisfying the requirements for an extremely low installation height of a composite piston, while allowing high mechanical and thermal loads. (orig.)

  1. Tyre and road wear prediction

    NARCIS (Netherlands)

    Lupker, H.A.

    2003-01-01

    Both tyre wear and road polishing are complex phenomenon, which are obviously strongly related; the energy that polishes the road is the energy that wears the tyre. The both depend non-linearly on numerous parameters, like materials used, vehicle and road usage, environmental conditions (i.e.

  2. Wear Process Analysis of the Polytetrafluoroethylene/Kevlar Twill Fabric Based on the Components’ Distribution Characteristics

    Directory of Open Access Journals (Sweden)

    Gu Dapeng

    2017-12-01

    Full Text Available Polytetrafluoroethylene (PTFE/Kevlar fabric or fabric composites with excellent tribological properties have been considered as important materials used in bearings and bushing, for years. The components’ (PTFE, Kevlar, and the gap between PTFE and Kevlar distribution of the PTFE/Kevlar fabric is uneven due to the textile structure controlling the wear process and behavior. The components’ area ratio on the worn surface varying with the wear depth was analyzed not only by the wear experiment, but also by the theoretical calculations with our previous wear geometry model. The wear process and behavior of the PTFE/Kevlar twill fabric were investigated under dry sliding conditions against AISI 1045 steel by using a ring-on-plate tribometer. The morphologies of the worn surface were observed by the confocal laser scanning microscopy (CLSM. The wear process of the PTFE/Kevlar twill fabric was divided into five layers according to the distribution characteristics of Kevlar. It showed that the friction coefficients and wear rates changed with the wear depth, the order of the antiwear performance of the previous three layers was Layer III>Layer II>Layer I due to the area ratio variation of PTFE and Kevlar with the wear depth.

  3. RE-1000 free-piston Stirling engine update

    Science.gov (United States)

    Schreiber, J. G.

    1985-01-01

    A free piston Stirling engine was tested. The tests performed over the past several years on the single cylinder engine were designed to investigate the dynamics of a free piston Stirling engine. The data are intended to be used primarily for computer code validation. The tests designed to investigate the sensitivity of the engine performance to variations in working space pressure, heater and cooler temperatures, regenerator porosity, power piston mass and displacer dynamics were completed. In addition, some data were recorded with alternate working fluids. A novel resonant balance system for the engine was also tested. Some preliminary test results of the tests performed are presented along with an outline of future tests to be run with the engine coupled to a hydraulic output unit. A description of the hydraulic output unit is given.

  4. A computational study of free-piston diesel engine combustion

    Energy Technology Data Exchange (ETDEWEB)

    Mikalsen, R.; Roskilly, A.P. [Sir Joseph Swan Institute for Energy Research, Newcastle University, Devonshire Building, Newcastle upon Tyne, NE1 7RU (United Kingdom)

    2009-07-15

    This paper investigates the in-cylinder gas motion, combustion process and nitrogen oxide formation in a free-piston diesel engine and compares the results to those of a conventional engine, using a computational fluid dynamics engine model. Enhanced radial gas flow (squish and reverse squish) around top dead centre is found for the free-piston engine compared to a conventional engine, however it is found that this has only minor influence on the combustion process. A higher heat release rate from the pre-mixed combustion phase due to an increased ignition delay was found, along with potential reductions in nitrogen oxides emissions formation for the free-piston engine. (author)

  5. Motion characteristic of a free piston linear engine

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Jin; Li, Qingfeng; Huang, Zhen [Key Laboratory for Power Machinery and Engineering of Ministry of Education, Shanghai Jiao Tong University, Shanghai, 200240 (China)

    2010-04-15

    A mathematical model of a free piston linear engine is established. The motion characteristics as well as the natural frequency map of the free piston are established. Then, its motion characteristics are successfully explained from the oscillation point. The full simulation model is built up in Matlab/Simulink for a better understanding of its motion features. The results show that the free piston system is a forced vibration system with variable damping coefficient and stiffness. Its steady-state response of periodical excitation is convergent which means that the system is stable under the periodical combustion. Furthermore, it has some unique features which are different from those of traditional Internal Combustion (IC) engines. (author)

  6. Fabrication, microstructural characterization and wear characteristics of A380 alloy-alumina composites

    KAUST Repository

    Nurani, Sheikh Jaber

    2016-03-10

    To obtain better mechanical and tribological properties than aluminium alloys aluminium is reinforced with alumina particles making aluminium metal matrix composites. In this work scrap piston A380 alloy was used as the matrix alloy. Alumina particles were added by 5%, 10% and 15% into matrix alloy respectively to form desired composites by stir casting technique. Pin on disc wear testing machine with counter surface as steel disc of hardness HRC 32 and surface roughness of 0.62 μm was used to conduct the wear test. In result composites showed superior wear resistance property over A380 alloy. The effect of load, sliding speed and sliding distance on wear behaviour were also examined in this study. Wear mechanism was identified from the worn surface. Both optical and scanning electron microscope (SEM) of the composites was performed to determine the microstructures. Optical micrograph shows grain size decreases with addition of alumina particles. EDS analysis was performed to confirm the presence of α-Al matrix, primary Si particles and intermetallic. As a general method, phase compositions were analyzed by using a scanning electron microscope (SEM) equipped with an energy dispersive spectroscopy (EDS). Optical microstructures were consistent with the SEM micrographs. © 2015 IEEE.

  7. Mechanical seal having a double-tier mating ring

    Science.gov (United States)

    Khonsari, Michael M.; Somanchi, Anoop K.

    2005-09-13

    An apparatus and method to enhance the overall performance of mechanical seals in one of the following ways: by reducing seal face wear, by reducing the contact surface temperature, or by increasing the life span of mechanical seals. The apparatus is a mechanical seal (e.g., single mechanical seals, double mechanical seals, tandem mechanical seals, bellows, pusher mechanical seals, and all types of rotating and reciprocating machines) comprising a rotating ring and a double-tier mating ring. In a preferred embodiment, the double-tier mating ring comprises a first and a second stationary ring that together form an agitation-inducing, guided flow channel to allow for the removal of heat generated at the seal face of the mating ring by channeling a coolant entering the mating ring to a position adjacent to and in close proximity with the interior surface area of the seal face of the mating ring.

  8. Experimental Study on the WavePiston Wave Energy Converter

    DEFF Research Database (Denmark)

    Pecher, Arthur; Kofoed, Jens Peter; Angelelli, E.

    This report presents the results of an experimental study of the power performance of the WavePiston wave energy converter. It focuses mainly on evaluating the power generating capabilities of the device and the effect of the following issues: Scaling ratios PTO loading Wave height and wave period...... dependency Oblique incoming waves Distance between plates During the study, the model supplied by the client, WavePiston, has been rigorously tested as all the anticipated tests have been done thoroughly and during all tests, good quality data has been obtained from all the sensors....

  9. Limiting density ratios in piston-driven compressions

    International Nuclear Information System (INIS)

    Lee, S.

    1985-07-01

    By using global energy and pressure balance applied to a shock model it is shown that for a piston-driven fast compression, the maximum compression ratio is not dependent on the absolute magnitude of the piston power, but rather on the power pulse shape. Specific cases are considered and a maximum density compression ratio of 27 is obtained for a square-pulse power compressing a spherical pellet with specific heat ratio of 5/3. Double pulsing enhances the density compression ratio to 1750 in the case of linearly rising compression pulses. Using this method further enhancement by multiple pulsing becomes obvious. (author)

  10. Heat Analysis of Liquid piston Compressor for Hydrogen Applications

    DEFF Research Database (Denmark)

    Kermani, Nasrin Arjomand; Rokni, Masoud

    2014-01-01

    A new hydrogen compression technology using liquid as the compression piston is investigated from heat transfer point of view. A thermodynamic model, simulating a single compression stroke, is developed to investigate the heat transfer phenomena inside the compression chamber. The model is develo......A new hydrogen compression technology using liquid as the compression piston is investigated from heat transfer point of view. A thermodynamic model, simulating a single compression stroke, is developed to investigate the heat transfer phenomena inside the compression chamber. The model...

  11. Continuing Development for Free-Piston Stirling Space Power Systems

    Science.gov (United States)

    Peterson, Allen A.; Qiu, Songgang; Redinger, Darin L.; Augenblick, John E.; Petersen, Stephen L.

    2004-02-01

    Long-life radioisotope power generators based on free-piston Stirling engines are an energy-conversion solution for future space applications. The high efficiency of Stirling machines makes them more attractive than the thermoelectric generators currently used in space. Stirling Technology Company (STC) has been developing free-piston Stirling machines for over 30 years, and its family of Stirling generators is ideally suited for reliable, maintenance-free operation. This paper describes recent progress and status of the STC RemoteGen™ 55 W-class Stirling generator (RG-55), presents an overview of recent testing, and discusses how the technology demonstration design has evolved toward space-qualified hardware.

  12. Assembly for electrical conductivity measurements in the piston cylinder device

    Science.gov (United States)

    Watson, Heather Christine [Dublin, CA; Roberts, Jeffrey James [Livermore, CA

    2012-06-05

    An assembly apparatus for measurement of electrical conductivity or other properties of a sample in a piston cylinder device wherein pressure and heat are applied to the sample by the piston cylinder device. The assembly apparatus includes a body, a first electrode in the body, the first electrode operatively connected to the sample, a first electrical conductor connected to the first electrode, a washer constructed of a hard conducting material, the washer surrounding the first electrical conductor in the body, a second electrode in the body, the second electrode operatively connected to the sample, and a second electrical conductor connected to the second electrode.

  13. Use of radioisotopes for monitoring the operating conditions of marine Diesel engines

    International Nuclear Information System (INIS)

    Backofen, R.; Strickert, H.

    1981-01-01

    For assessing wear in marine Diesel engines a two-sample activation technique has been developed. The procedure is described, taking the determination of wear of piston rings in the running engine as an example

  14. CAD/CAM/CAI Application for High-Precision Machining of Internal Combustion Engine Pistons

    Directory of Open Access Journals (Sweden)

    V. V. Postnov

    2014-07-01

    Full Text Available CAD/CAM/CAI application solutions for internal combustion engine pistons machining was analyzed. Low-volume technology of internal combustion engine pistons production was proposed. Fixture for CNC turning center was designed.

  15. Comparison of Heavy-Duty Scuffing Behavior between Chromium-Based Ceramic Composite and Nickel-Chromium-Molybdenum-Coated Ring Sliding against Cast Iron Liner under Starvation

    Directory of Open Access Journals (Sweden)

    Yan Shen

    2017-10-01

    Full Text Available A running-in and starved lubrication experiment is designed to investigate the heavy-duty scuffing behavior of piston ring coatings against cast iron (Fe cylinder liner using the piston ring reciprocating liner test rig. The scuffing resistance of the piston ring with the chromium-based ceramic composite coating (CKS, and that with the thermally sprayed nickel-chromium-molybdenum coating (NCM is compared at different nominal pressures (40~100 MPa and temperatures (180~250 °C. With the failure time as a criterion, the rank order is as follows: NCM/Fe > CKS/Fe. Before the scoring occurs at the interface of the piston ring and cylinder liner (PRCL, the cast iron liner enters into a “polish wear” stage, and iron-based adhesive materials begin to form on the piston ring surface. With the macroscopic adhesion formation, the plastic shearing cycle causes surface damages mainly due to abrasive effects for the CKS/Fe pairs and adhesive effects for the NCM/Fe pairs.

  16. The control of a free-piston engine generator. Part 2: Engine dynamics and piston motion control

    Energy Technology Data Exchange (ETDEWEB)

    Mikalsen, R.; Roskilly, A.P. [Sir Joseph Swan Institute for Energy Research, Newcastle University, Newcastle upon Tyne, NE1 7RU England (United Kingdom)

    2010-04-15

    Free-piston engines are under investigation by a number of research groups due to potential fuel efficiency and exhaust emissions advantages over conventional technology. The main challenge with such engines is the control of the piston motion, and this has not yet been fully resolved for all types of free-piston engines. This paper builds on the fundamental investigations presented in the accompanying paper and investigates the dynamics of the engine and the feasibility of classical control approaches. The response of the engine to rapid load changes are investigated using decentralised PID, PDF and disturbance feedforward. It is found that the engine is sensitive to rapid load changes but that in constant power applications standard control techniques provide satisfactory performance. The influence of cycle-to-cycle variations in the combustion process are investigated, but not found to be critical for engine operation. (author)

  17. The influence oil film lubrication of the piston-cylinder dynamic

    Directory of Open Access Journals (Sweden)

    Adriana Tokar

    2008-10-01

    Full Text Available An analytical study of the dynamics of a piston in a reciprocating engine was conducted. The equation of Reynolds and moving of piston are derived. The analysis, which incorporates a hydrodynamic lubrication model, was applied to M501 diesel engine. The results of this study indicate that piston dynamics were found to be sensitive to piston-cylinder bore clearance, location of the wrist pin and lubricant viscosity, underscoring their importance in engine design.

  18. Corneal ring infiltration in contact lens wearers

    Directory of Open Access Journals (Sweden)

    Seyed Ali Tabatabaei

    2017-01-01

    Full Text Available To report a case of atypical sterile ring infiltrates during wearing soft silicone hydrogel contact lens due to poor lens care. A 29-year-old woman presented with complaints of pain, redness, and morning discharge. She was wearing soft silicone hydrogel contact lens previously; her current symptoms began 1 week before presentation. On examination, best-corrected visual acuity was 20/40 in that eye. Slit-lamp examination revealed dense, ring-shaped infiltrate involving both the superficial and deep stromal layers with lucid interval to the limbus, edema of the epithelium, epithelial defect, and vascularization of the superior limbus. Cornea-specific in vivo laser confocal microscopy (Heidelberg Retina Tomograph 2 Rostock Cornea Module, HRT 2-RCM, Heidelberg Engineering GmbH, Dossenheim, Germany revealed Langerhans cells and no sign of Acanthamoeba or fungal features, using lid scraping and anti-inflammatory drops; her vision completely recovered. We reported an atypical case of a sterile corneal ring infiltrate associated with soft contact lens wearing; smear, culture, and confocal microscopy confirmed a sterile inflammatory reaction.

  19. Environmentally friendly, oil-free free piston engine. Displacement engines in distributed energy systems. Research funding decision. Subproject: Free piston engine. Final report; Ympaeistoeystaevaellinen, oeljytoen vapaamaentaemoottori. Syrjaeytysmoottoriprosessit hajautetussa energiahuollossa. Lineaarimoottori-osaprojekti. Loppuraportti

    Energy Technology Data Exchange (ETDEWEB)

    Larjola, J.; Honkatukia, J.; Sallinen, P.

    2005-07-01

    A free piston engine suitable for small-scale energy production in distributed energy systems was preliminarily designed in this project, including a manufacturing survey as well. The properties of the engine were simulated using a simulation program developed in this project, and the results were utilized in preliminary constructional design. The engine simulation program was developed by combining and modifying the source codes of the simulation and calculation programs obtained from Helsinki University of Technology, Tampere University of Technology, and Lappeenranta University of Technology. Because of the contact-free labyrinth seal used in the piston, the efficiency of the motor is about 5 percentage points lower than the efficiency of a conventional motor with oil-lubricated piston rings. On the other hand, the lack of bearing losses, and the lack of losses associated with a crankshaft system and a gearbox, as well as the lack of lubrication oil expenses, compensates this effect. As a net result, it can be estimated, that the operating expenses of this new motor could be about one percentage point lower than with a conventional motor; that is, the new motor would be slightly better than the conventional one. An oil-free free piston engine is particularly suitable for distributed energy systems using natural gas, biogas, or liquid fuel made from biomass. Because it is completely oil-free, it is very environmentally friendly, and its exhaust gases are completely free of oil residuals which are causing problems in normal gas motors. In principle the oil-free free piston engine could be used also in road vehicles which are provided with an electric power transmission system. This could enable a complete oil-free traffic system, where DME (dimethyl ether) or alcohol produced from domestic biomass would be used as a fuel. The distribution of this kind of a fuel would be easier with the present service station network than the distribution of hydrogen. Because this

  20. Rubber glove wearing device

    International Nuclear Information System (INIS)

    Nozaki, Tatsuo; Takada, Kaoru.

    1994-01-01

    Rubber groves are attached each to an upper end of a glove putting vessel having an air-sucking hole on the bottom by enlarging an opening end of the rubber glove and turning back the inside to the outside. When the sucking device is operated, air in the glove putting device is sucked and the rubber glove is expanded by an atmospheric pressure. After expansion of the rubber glove to some extent, the sucking device is stopped, and presence or absence of failures of the rubber glove is confirmed by shrinkage of the rubber glove and by an indication value of a pressure gauge for detecting the pressure change in the vessel. Then, a hand is inserted to the expanded rubber glove, and a detaching switch in the vessel is pushed by a finger tip. A detaching piece at the upper end of the vessel is protruded outwardly to enlarge the turned-back portion of the rubber glove to easily release the rubber glove from the putting vessel, and the rubber glove is put on. This enables to wear the rubber glove and conduct failure test simultaneously. Further, a user can put on the rubber glove without touching the outside of the rubber glove. (I.N.)

  1. An approximate solution for spherical and cylindrical piston problem

    Indian Academy of Sciences (India)

    the growth and decay of shock strengths for spherical and cylindrical pistons starting from a non-zero ... conditions at an appropriate level, a new theory of shock dynamics (NTSD) has been proposed (Ravindran and ..... sive, its packing density etc. which are not included in our mathematical formulation, it may explain the ...

  2. On the design of lubricant free piston compressors

    NARCIS (Netherlands)

    Owczarek, P.

    2010-01-01

    This thesis describes the development on long lifetime and an efficient piston compressor operating in a clean environment where oil lubrication must be excluded. Particularly in cooling systems including cryocoolers the presence of oil is a well known problem. A growing number of applications of

  3. Electromagnetic liquid pistons for capillarity-based pumping

    Science.gov (United States)

    Malouin, Bernard; Olles, Joseph; Cheng, Lili; Hirsa, Amir; Vogel, Michael

    2011-11-01

    Two adjoining ferrofluid droplets can behave as an electronically-controlled oscillator or switch by an appropriate balance of magnetic, capillary, and inertial forces. Their motion can be exploited to displace a surrounding liquid, forming electromagnetic liquid pistons. Such ferrofluid pistons can pump a precise volume of liquid via finely tunable amplitudes or resonant frequencies with no solid moving parts. Here we demonstrate the use of these liquid pistons in capillarity-dominated systems for variable focal distance liquid lenses with nearly perfect spherical interfaces. These liquid/liquid lenses feature many promising qualities not previously realized together in a liquid lens, including large apertures, immunity to evaporation, invariance to orientation relative to gravity, and low driving voltages. The dynamics of these liquid pistons is examined, with experimental measurements showing good agreement with a spherical cap model. A centimeter-scale lens was shown to respond in excess of 30 Hz, with resonant frequencies over 1 kHz predicted for scaled down systems.

  4. Probability analysis of dynamical effects of axial piston hydraulic motor

    OpenAIRE

    Sapietova Alzbeta; Dekys Vladimír; Sapieta Milan; Sulka Peter; Gajdos Lukas; Rojek Izabela

    2018-01-01

    The paper presents an analysis of impact force on stopper screw in axial piston hydraulic motor. The solution contains probabilistic description of input variables. If the output parameters of probabilistic solution are compared with arbitrary values and values acquired by analytical solution, the probability of proper operation of the device can be evaluated.

  5. Closing the innovation cycle in lightweighting compressor pistons technolog

    NARCIS (Netherlands)

    Wentzel, C.; Eijk, A.; Groenewegen, G.; Bergsma, O.

    2016-01-01

    What started out as an exercise in exploring the weight reduction potential of those allegedly “heavy recip crossheads”, turned out to be a fast leap towards implementation of a new hybrid material concept for very lightweight pistons. This was enabled by a next phase in the EFRC R&D group research

  6. Closing the innovation cycle in lightweighting compressor pistons technology

    NARCIS (Netherlands)

    Wentzel, C.M.; Eijk, A.; Groenewegen, G.; Bergsma, O.K.

    2016-01-01

    What started out as an exercise in exploring the weight reduction potential of those allegedly “heavy recip crossheads”, turned out to be a fast leap towards implementation of a new hybrid material concept for very lightweight pistons. This was enabled by a next phase in the EFRC R&D group

  7. Spherical-wave expansions of piston-radiator fields.

    Science.gov (United States)

    Wittmann, R C; Yaghjian, A D

    1991-09-01

    Simple spherical-wave expansions of the continuous-wave fields of a circular piston radiator in a rigid baffle are derived. These expansions are valid throughout the illuminated half-space and are useful for efficient numerical computation in the near-field region. Multipole coefficients are given by closed-form expressions which can be evaluated recursively.

  8. Microstructure and wear characteristics on Al alloy matrix composite reinforced with Ni perform

    Energy Technology Data Exchange (ETDEWEB)

    Park, Won Jo; Park, Cheol Hong; Kim, Hyung Jin; Huh, Sun Chul [Gyeongsang National University, Tongyeong, (Korea, Republic of)

    2012-06-15

    Al based composite reinforced with Nickel is used for diesel engine piston, because the thermal properties, strength and corrosion resistant are for better than Al alloy alone. For processing, the intermetallic compounds of Ni and Al improves wear resistance due to its high hardness. Existing process methods for MMC (metal matrix composite) using preform were manufactured under high-pressure. However, this causes deformation of the preform or weaknesses in the completed MMC. Low-pressure infiltration can prevent these problems, and there is an advantage of cost reduction in of production with small-scale of production equipment. In this study, the microstructure and wear characteristics of Al-based composite with Ni preform as reinforcement with low-pressure infiltration was analyzed.

  9. Influence of Pressure Build-Up Time of Compression Chamber on Improving the Operation Frequency of a Single-Piston Hydraulic Free-Piston Engine

    Directory of Open Access Journals (Sweden)

    Hai-bo Xie

    2013-01-01

    Full Text Available A single-piston hydraulic free-piston engine with a two-cylinder four-stroke diesel engine as its driver is introduced. It takes the free-piston assembly a certain time to move after the pressure in the compression chamber starts to increase. The time difference between the pressure increasing and the piston starting to move is defined as the pressure build-up time. The characteristics of the pressure build-up time and its influence on the performance of the free-piston engine are introduced and analyzed. Based on the basic law of dynamics of the free-piston assembly, the parameters which influence the pressure build-up time are analyzed. And then improvement and optimization are proposed to shorten the pressure build-up time.

  10. Erosive tooth wear in children

    NARCIS (Netherlands)

    Carvalho, T.S.; Lussi, A.; Jaeggi, T.; Gambon, D.L.; Lussi, A.; Ganss, C.

    2014-01-01

    Erosive tooth wear in children is a common condition. Besides the anatomical differences between deciduous and permanent teeth, additional histological differences may influence their susceptibility to dissolution. Considering laboratory studies alone, it is not clear whether deciduous teeth are

  11. A comparative reliability analysis of free-piston Stirling machines

    Science.gov (United States)

    Schreiber, Jeffrey G.

    2001-02-01

    A free-piston Stirling power convertor is being developed for use in an advanced radioisotope power system to provide electric power for NASA deep space missions. These missions are typically long lived, lasting for up to 14 years. The Department of Energy (DOE) is responsible for providing the radioisotope power system for the NASA missions, and has managed the development of the free-piston power convertor for this application. The NASA Glenn Research Center has been involved in the development of Stirling power conversion technology for over 25 years and is currently providing support to DOE. Due to the nature of the potential missions, long life and high reliability are important features for the power system. Substantial resources have been spent on the development of long life Stirling cryocoolers for space applications. As a very general statement, free-piston Stirling power convertors have many features in common with free-piston Stirling cryocoolers, however there are also significant differences. For example, designs exist for both power convertors and cryocoolers that use the flexure bearing support system to provide noncontacting operation of the close-clearance moving parts. This technology and the operating experience derived from one application may be readily applied to the other application. This similarity does not pertain in the case of outgassing and contamination. In the cryocooler, the contaminants normally condense in the critical heat exchangers and foul the performance. In the Stirling power convertor just the opposite is true as contaminants condense on non-critical surfaces. A methodology was recently published that provides a relative comparison of reliability, and is applicable to systems. The methodology has been applied to compare the reliability of a Stirling cryocooler relative to that of a free-piston Stirling power convertor. The reliability analysis indicates that the power convertor should be able to have superior reliability

  12. Wear mechanisms of coated hardmetals

    International Nuclear Information System (INIS)

    Richter, V.

    2001-01-01

    In the paper several aspects of the wear mechanisms of coated hardmetals, ceramics and super-hard materials (CBN) in machining cast iron are discussed, with particular attention being given to high-speed machining of different cast iron grades. The influence of machining parameters, microstructure, composition and mechanical and chemical properties of the cutting tool and the work-piece material on wear are considered. (author)

  13. Novel Ring-Configuration Double-Acting Free-Piston Stirling Convertor, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA SBIR-2015 Topic S3.01 seeks to evaluate and advance Stirling convertors as a potentially more efficient alternative to the radioisotope-heated thermoelectric...

  14. Gear Tooth Wear Detection Algorithm

    Science.gov (United States)

    Delgado, Irebert R.

    2015-01-01

    Vibration-based condition indicators continue to be developed for Health Usage Monitoring of rotorcraft gearboxes. Testing performed at NASA Glenn Research Center have shown correlations between specific condition indicators and specific types of gear wear. To speed up the detection and analysis of gear teeth, an image detection program based on the Viola-Jones algorithm was trained to automatically detect spiral bevel gear wear pitting. The detector was tested using a training set of gear wear pictures and a blind set of gear wear pictures. The detector accuracy for the training set was 75 percent while the accuracy for the blind set was 15 percent. Further improvements on the accuracy of the detector are required but preliminary results have shown its ability to automatically detect gear tooth wear. The trained detector would be used to quickly evaluate a set of gear or pinion pictures for pits, spalls, or abrasive wear. The results could then be used to correlate with vibration or oil debris data. In general, the program could be retrained to detect features of interest from pictures of a component taken over a period of time.

  15. Numerical simulation of two-piston light gas gun for pellet injection in tokamaks

    International Nuclear Information System (INIS)

    Shi Yumei; He Yaling; Chen Zhongqi; Wu Peiyi

    1995-01-01

    Analysing the shortcoming of the single-piston light gas gun, the author uses the method of characteristics to estimate the performance of the two-piston light gas gun, and compare it with the single-piston gun, the result shows that two-piston gun has advantage on the aspect of the pressure pulse that promotes the pellet. The effects of some important parameters are also discussed. This work provides the theoretical basis for the design and optimization of two-piston light gas gun

  16. Critical component wear in heavy duty engines

    CERN Document Server

    Lakshminarayanan, P A

    2011-01-01

    The critical parts of a heavy duty engine are theoretically designed for infinite life without mechanical fatigue failure. Yet the life of an engine is in reality determined by wear of the critical parts. Even if an engine is designed and built to have normal wear life, abnormal wear takes place either due to special working conditions or increased loading.  Understanding abnormal and normal wear enables the engineer to control the external conditions leading to premature wear, or to design the critical parts that have longer wear life and hence lower costs. The literature on wear phenomenon r

  17. Vortex ring formation at the open end of a shock tube: A particle image velocimetry study

    Science.gov (United States)

    Arakeri, J. H.; Das, D.; Krothapalli, A.; Lourenco, L.

    2004-04-01

    The vortex ring generated subsequent to the diffraction of a shock wave from the open end of a shock tube is studied using particle image velocimetry. We examine the early evolution of the compressible vortex ring for three-exit shock Mach numbers, 1.1, 1.2, and 1.3. For the three cases studied, the ring formation is complete at about tUb/D=2, where t is time, Ub is fluid velocity behind shock as it exits the tube and D is tube diameter. Unlike in the case of piston generated incompressible vortex rings where the piston velocity variation with time is usually trapezoidal, in the shock-generated vortex ring case the exit fluid velocity doubles from its initial value Ub before it slowly decays to zero. At the end of the ring formation, its translation speed is observed to be about 0.7 Ub. During initial formation and propagation, a jet-like flow exists behind the vortex ring. The vortex ring detachment from the tailing jet, commonly referred to as pinch-off, is briefly discussed.

  18. Coupled dynamic-multidimensional modelling of free-piston engine combustion

    Energy Technology Data Exchange (ETDEWEB)

    Mikalsen, R. [Sir Joseph Swan Institute for Energy Research, Newcastle University, Newcastle upon Tyne NE1 7RU (United Kingdom); Roskilly, A.P. [Sir Joseph Swan Institute for Energy Research, Newcastle University, Newcastle upon Tyne NE1 7RU (United Kingdom)], E-mail: tony.roskilly@ncl.ac.uk

    2009-01-15

    Free-piston engines are under investigation by a number of research groups worldwide, as an alternative to conventional technology in applications such as electric and hydraulic power generation. The piston dynamics of the free-piston engine differ significantly from those of conventional engines, and this may influence in-cylinder gas motion, combustion and emissions formation. Due to the complex interaction between mechanics and thermodynamics, the modelling of free-piston engines is not straight-forward. This paper presents a novel approach to the modelling of free-piston engines through the introduction of solution-dependent mesh motion in an engine CFD code. The particular features of free-piston engines are discussed, and the model for engine dynamics implemented in the CFD code is described. Finally, the coupled solver is demonstrated through the modelling of a spark ignited free-piston engine generator.

  19. Coupled dynamic-multidimensional modelling of free-piston engine combustion

    International Nuclear Information System (INIS)

    Mikalsen, R.; Roskilly, A.P.

    2009-01-01

    Free-piston engines are under investigation by a number of research groups worldwide, as an alternative to conventional technology in applications such as electric and hydraulic power generation. The piston dynamics of the free-piston engine differ significantly from those of conventional engines, and this may influence in-cylinder gas motion, combustion and emissions formation. Due to the complex interaction between mechanics and thermodynamics, the modelling of free-piston engines is not straight-forward. This paper presents a novel approach to the modelling of free-piston engines through the introduction of solution-dependent mesh motion in an engine CFD code. The particular features of free-piston engines are discussed, and the model for engine dynamics implemented in the CFD code is described. Finally, the coupled solver is demonstrated through the modelling of a spark ignited free-piston engine generator

  20. Piston surface heat transfer during combustion in large marine diesel engines

    DEFF Research Database (Denmark)

    Jensen, Michael Vincent; Walther, Jens Honore

    2010-01-01

    In the design process of large marine diesel engines information on the maximum heat load on the piston surface experienced during the engine cycle is an important parameter. The peak heat load occurs during combustion when hot combustion products impinge on the piston surface. Although the maximum...... heat load is only present for a short time of the total engine cycle, it is a severe thermal load on the piston surface. At the same time, cooling of the piston crown is generally more complicated than cooling of the other components of the combustion chamber. This can occasionally cause problems...... with burning off piston surface material. In this work the peak heat load on the piston surface of large marine diesel engines during combustion was investigated. Measurements of the instantaneous surface temperature and surface heat flux on pistons in large marine engines are difficult due to expensive...

  1. Kayser-Fleischer Rings

    Science.gov (United States)

    ... Support Contacts Lab Tracker/Copper Calculator Stories Programs & Research ... About Everything you need to know about Wilson Disease Kayser-Fleischer Rings Definition Kayser-Fleischer Ring: Clinical sign. Brownish-yellow ring visible around the corneo- ...

  2. Externally heated valve engine a new approach to piston engines

    CERN Document Server

    Kazimierski, Zbyszko

    2016-01-01

    This book reports on a novel approach for generating mechanical energy from different, external heat sources using the body of a typical piston engine with valves. By presenting simple yet effective numerical models, the authors show how this new approach, which combines existing internal combustion technology with a lubrication system, is able to offer an economic solution to the problem of mechanical energy generation in piston engines. Their results also show that a stable heat generation process can be guaranteed outside of the engine. The book offers a detailed report on physical and numerical models of 4-stroke and 2-stroke versions of the EHVE together with different models of heat exchange, valves and results of their simulations. It also delivers the test results of an engine prototype run in laboratory conditions. By presenting a novel theoretical framework and providing readers with extensive knowledge of both the advantages and challenges of the method, this book is expected to inspire academic re...

  3. Palm Power Free-Piston Stirling Engine Control Electronics

    Science.gov (United States)

    Keiter, Douglas E.; Holliday, Ezekiel

    2007-01-01

    A prototype 35We, JP-8 fueled, soldier-wearable power system for the DARPA Palm Power program has been developed and tested by Sunpower. A hermetically-sealed 42We Sunpower Free-Piston Stirling Engine (FPSE) with integral linear alternator is the prime mover for this system. To maximize system efficiency over a broad range of output power, a non-dissipative, highly efficient electronic control system which modulates engine output power by varying piston stroke and converts the AC output voltage of the FPSE into 28Vdc for the Palm Power end user, has been designed and demonstrated as an integral component of the Palm Power system. This paper reviews the current status and progress made in developing the control electronics for the Palm Power system, in addition to describing the operation and demonstrated performance of the engine controller in the context of the current JP-8 fueled Palm Power system.

  4. New generation of free-piston shock tunnels

    Science.gov (United States)

    Morrison, W. R. B.; Stalker, R. J.; Duffin, J.

    1990-01-01

    Consideration is given to three free-piston driven hypersonic tunnels under construction that will greatly enhance existing test capabilities. The tunnel being built at Caltech will feature energy capabilities about 40 percent higher than those of the world's largest operational free-piston tunnel to date. The second tunnel under construction will allow full-size engine hardware at near-orbital speeds. The third facility is a high-performance expansion tube that will be capable of generating high enthalpy flows at speeds of up to 9 km/sec. It will provide flows with dissociation levels much lower than are attainable with a reflected shock tunnel, approaching actual flight conditions. A table shows the tunnels' characteristics.

  5. Some design features of CO2 swing piston expander

    International Nuclear Information System (INIS)

    Guan Haiqing; Ma Yitai; Li Minxia

    2006-01-01

    CO 2 is a potential substitute for synthesized refrigerants with favorable environmental properties. To improve the coefficient of performance (COP) of CO 2 heat pump systems, a swing piston expander prototype has been developed for replacing the throttling valve based on the thermodynamic analysis of the operating conditions of a CO 2 transcritical cycle. The measures on reducing the loss of friction and leakage are paramount important to improve the efficiency of the expander. The performance of the CO 2 swing expander prototype was actually tested in a CO 2 transcritical cycle water-to-water heat pump test rig, and the test results illustrate that the isentropic efficiency of the prototype can be more than 28% when running steadily and up to a maximum of about 44%. Some operating characteristics of the swing piston expander are presented according to the analysis of the test results

  6. Critical needs for piston engine overhaul centre in Malaysia

    Science.gov (United States)

    Khairuddin, M. H.; Yahya, M. Y.; Johari, M. K.

    2017-12-01

    Piston engine overhaul centre (PEOC) is the branch of aviation Maintenance, Repair and Overhaul (MRO) providers, which plays a pivotal role in maintaining the fleet of business and commercial aircraft in the world. The centre typically offers three main MRO capabilities: airframe, engine and component services. Companies holding a PEOC(s) are all subjected to stringent procedures and conditions regulated and audited by the International Civil Aviation Organization. Currently, piston engine maintenance and repair for Asian countries is conducted only in Singapore. The focus of this study is to establish the needs for a PEOC in Malaysia, which will cater almost all small local aircraft companies such as transport and flying school companies.

  7. Experiments on the WavePiston, Wave Energy Converter

    DEFF Research Database (Denmark)

    Angelelli, E.; Zanuttigh, B.; Kofoed, Jens Peter

    2011-01-01

    This paper analyses the performance of a new Wave Energy Converter (WEC) of the Oscillating Water Column type (OWC), named WavePiston. This near-shore floating device is composed of plates (i.e. energy collectors) sliding around a cylinder, that is placed perpendicular to the shore. Tests...... in the wave basin at Aalborg University allowed to investigate power production in the North Sea typical wave climate, with varying design parameters such as plate dimensions and their mutual distance. The power produced per meter by each collector is about the 5% of the available wave power. Experimental...... results and survivability considerations suggest that the WavePiston would be particularly suited for installations in milder seas. An example application is therefore presented in the Mediterranean Sea, off-shore the island of Sicily. In this case, each collector harvests the 10% of the available wave...

  8. A study of wear in refrigerating machines using thin layer activation

    International Nuclear Information System (INIS)

    Hammer, P.; Eichhorn, K.; Eifrig, C.

    1986-01-01

    Wear is studied in a ball-and-socket joint of a newly developed refrigerating machine. Using deuteron activation a 15 μm deep Co-57 layer is generated at the ring-shaped friction area in the steel socket of the joint. The measurement of the Co-57 intensity of the wear particles held back on an oil filter provides information about the wear rate of the socket during machine operation. The measurement of the Co-57 contaminations occuring in the individual parts of the machine at the end of the test gives information about the distribution of the wear particles in the machine and about the material transfer in the ball-and-socket joint. (author)

  9. The effects of retained austenite on dry sliding wear behavior of carburized steels

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyung-Jun [Research Inst. of Industrial Science and Technology, Steel Products Dept., Pohang (Korea, Republic of); Kweon, Young-Gak [Research Inst. of Industrial Science and Technology, Steel Products Dept., Pohang (Korea, Republic of)

    1996-04-01

    Ring-on-square tests on two kinds of low-alloy carburized steel which were AISI 8620 and 4140 were carried out to study the dry sliding wear behavior. The influence of different retained austenite level of 6% to 40% was evaluated while trying to eliminate other factors. Test results show that the effects of grain size and carburized steel species are negligible in dry sliding wear behavior. While the influence of retained austenite is negligible at 20 kg load condition, wear resistance is decreased at 40 kg load condition as the retained austenite level is increased from 6% to 30%. However, wear resistance is again increased above about 30% of retained austenite level at 40 kg load condition. (orig.)

  10. ASSOCIATIVE RINGS SOLVED AS LIE RINGS

    Directory of Open Access Journals (Sweden)

    M. B. Smirnov

    2011-01-01

    Full Text Available The paper has proved that an associative ring which is solvable of a n- class as a Lie ring has a nilpotent ideal of the nilpotent class not more than 3×10n–2  and a corresponding quotient ring satisfies an identity [[x1, x2, [x3, x4

  11. Free piston variable-stroke linear-alternator generator

    Science.gov (United States)

    Haaland, Carsten M.

    1998-01-01

    A free-piston variable stroke linear-alternator AC power generator for a combustion engine. An alternator mechanism and oscillator system generates AC current. The oscillation system includes two oscillation devices each having a combustion cylinder and a flying turnbuckle. The flying turnbuckle moves in accordance with the oscillation device. The alternator system is a linear alternator coupled between the two oscillation devices by a slotted connecting rod.

  12. A magnetically driven piston pump for ultra-clean applications

    Science.gov (United States)

    LePort, F.; Neilson, R.; Barbeau, P. S.; Barry, K.; Bartoszek, L.; Counts, I.; Davis, J.; deVoe, R.; Dolinski, M. J.; Gratta, G.; Green, M.; Díez, M. Montero; Müller, A. R.; O'Sullivan, K.; Rivas, A.; Twelker, K.; Aharmim, B.; Auger, M.; Belov, V.; Benitez-Medina, C.; Breidenbach, M.; Burenkov, A.; Cleveland, B.; Conley, R.; Cook, J.; Cook, S.; Craddock, W.; Daniels, T.; Dixit, M.; Dobi, A.; Donato, K.; Fairbank, W.; Farine, J.; Fierlinger, P.; Franco, D.; Giroux, G.; Gornea, R.; Graham, K.; Green, C.; Hägemann, C.; Hall, C.; Hall, K.; Hallman, D.; Hargrove, C.; Herrin, S.; Hughes, M.; Hodgson, J.; Juget, F.; Kaufman, L. J.; Karelin, A.; Ku, J.; Kuchenkov, A.; Kumar, K.; Leonard, D. S.; Lutter, G.; Mackay, D.; MacLellan, R.; Marino, M.; Mong, B.; Morgan, P.; Odian, A.; Piepke, A.; Pocar, A.; Prescott, C. Y.; Pushkin, K.; Rollin, E.; Rowson, P. C.; Schmoll, B.; Sinclair, D.; Skarpaas, K.; Slutsky, S.; Stekhanov, V.; Strickland, V.; Swift, M.; Vuilleumier, J.-L.; Vuilleumier, J.-M.; Wichoski, U.; Wodin, J.; Yang, L.; Yen, Y.-R.

    2011-10-01

    A magnetically driven piston pump for xenon gas recirculation is presented. The pump is designed to satisfy extreme purity and containment requirements, as is appropriate for the recirculation of isotopically enriched xenon through the purification system and large liquid xenon time projection chamber of EXO-200. The pump, using sprung polymer gaskets, is capable of pumping more than 16 standard liters per minute of xenon gas with 750 Torr differential pressure.

  13. Nonstationary heat flow in the piston of the turbocharged engine

    Directory of Open Access Journals (Sweden)

    Piotr GUSTOF

    2010-01-01

    Full Text Available In this study the numeric computations of nonstationary heat flow in form of temperature distribution on characteristic surfaces of the piston of the turbocharged engine at the beginning phase its work was presented. The computations were performed for fragmentary load engine by means of the two-zone combustion model, the boundary conditions of III kind and the finite elements method (FEM by using of COSMOS/M program.

  14. Formation Number Of Laminar Vortex Rings. Numerical Simulations

    International Nuclear Information System (INIS)

    Rosenfeld, M.; Rambod, E.; Gharib, M.

    1998-01-01

    The formation time scale of axisymmetric vortex rings is studied numerically for relatively long discharge times. Experimental findings on the existence and universality of a formation time scale, referred to as the formation number, are confirmed. The formation number is indicative of the time a vortex ring acquires its maximal circulation. For vortex rings generated by impulsive motion of a piston, the formation number was found experimentally to be approximately 4. Numerical extension of the experimental study to thick shear layers indicates that the scaled circulation of the pinched-off vortex is relatively insensitive of the details of the formation process, such as the velocity program, velocity profile or vortex generator geometry. In contrast, the formation number does depend on the velocity profile

  15. Multiscale Modeling of Wear Degradation

    KAUST Repository

    Moraes, Alvaro; Ruggeri, Fabrizio; Tempone, Raul; Vilanova, Pedro

    2016-01-01

    Cylinder liners of diesel engines used for marine propulsion are naturally subjected to a wear process, and may fail when their wear exceeds a specified limit. Since failures often represent high economical costs, it is utterly important to predict and avoid them. In this work [4], we model the wear process using a pure jump process. Therefore, the inference goal here is to estimate: the number of possible jumps, its sizes, the coefficients and the shapes of the jump intensities. We propose a multiscale approach for the inference problem that can be seen as an indirect inference scheme. We found that using a Gaussian approximation based on moment expansions, it is possible to accurately estimate the jump intensities and the jump amplitudes. We obtained results equivalent to the state of the art but using a simpler and less expensive approach.

  16. Multiscale Modeling of Wear Degradation

    KAUST Repository

    Moraes, Alvaro; Ruggeri, Fabrizio; Tempone, Raul; Vilanova, Pedro

    2015-01-01

    Cylinder liners of diesel engines used for marine propulsion are naturally subjected to a wear process, and may fail when their wear exceeds a specified limit. Since failures often represent high economical costs, it is utterly important to predict and avoid them. In this work [4], we model the wear process using a pure jump process. Therefore, the inference goal here is to estimate: the number of possible jumps, its sizes, the coefficients and the shapes of the jump intensities. We propose a multiscale approach for the inference problem that can be seen as an indirect inference scheme. We found that using a Gaussian approximation based on moment expansions, it is possible to accurately estimate the jump intensities and the jump amplitudes. We obtained results equivalent to the state of the art but using a simpler and less expensive approach.

  17. Multiscale Modeling of Wear Degradation

    KAUST Repository

    Moraes, Alvaro

    2015-01-07

    Cylinder liners of diesel engines used for marine propulsion are naturally subjected to a wear process, and may fail when their wear exceeds a specified limit. Since failures often represent high economical costs, it is utterly important to predict and avoid them. In this work [4], we model the wear process using a pure jump process. Therefore, the inference goal here is to estimate: the number of possible jumps, its sizes, the coefficients and the shapes of the jump intensities. We propose a multiscale approach for the inference problem that can be seen as an indirect inference scheme. We found that using a Gaussian approximation based on moment expansions, it is possible to accurately estimate the jump intensities and the jump amplitudes. We obtained results equivalent to the state of the art but using a simpler and less expensive approach.

  18. Multiscale Modeling of Wear Degradation

    KAUST Repository

    Moraes, Alvaro

    2014-01-06

    Cylinder liners of diesel engines used for marine propulsion are naturally subjected to a wear process, and may fail when their wear exceeds a specified limit. Since failures often represent high economical costs, it is utterly important to predict and avoid them. In this work [4], we model the wear process using a pure jump process. Therefore, the inference goal here is to estimate: the number of possible jumps, its sizes, the coefficients and the shapes of the jump intensities. We propose a multiscale approach for the inference problem that can be seen as an indirect inference scheme. We found that using a Gaussian approximation based on moment expansions, it is possible to accurately estimate the jump intensities and the jump amplitudes. We obtained results equivalent to the state of the art but using a simpler and less expensive approach.

  19. Multiscale Modeling of Wear Degradation

    KAUST Repository

    Moraes, Alvaro

    2016-01-06

    Cylinder liners of diesel engines used for marine propulsion are naturally subjected to a wear process, and may fail when their wear exceeds a specified limit. Since failures often represent high economical costs, it is utterly important to predict and avoid them. In this work [4], we model the wear process using a pure jump process. Therefore, the inference goal here is to estimate: the number of possible jumps, its sizes, the coefficients and the shapes of the jump intensities. We propose a multiscale approach for the inference problem that can be seen as an indirect inference scheme. We found that using a Gaussian approximation based on moment expansions, it is possible to accurately estimate the jump intensities and the jump amplitudes. We obtained results equivalent to the state of the art but using a simpler and less expensive approach.

  20. Maximum Work of Free-Piston Stirling Engine Generators

    Science.gov (United States)

    Kojima, Shinji

    2017-04-01

    Using the method of adjoint equations described in Ref. [1], we have calculated the maximum thermal efficiencies that are theoretically attainable by free-piston Stirling and Carnot engine generators by considering the work loss due to friction and Joule heat. The net work done by the Carnot cycle is negative even when the duration of heat addition is optimized to give the maximum amount of heat addition, which is the same situation for the Brayton cycle described in our previous paper. For the Stirling cycle, the net work done is positive, and the thermal efficiency is greater than that of the Otto cycle described in our previous paper by a factor of about 2.7-1.4 for compression ratios of 5-30. The Stirling cycle is much better than the Otto, Brayton, and Carnot cycles. We have found that the optimized piston trajectories of the isothermal, isobaric, and adiabatic processes are the same when the compression ratio and the maximum volume of the same working fluid of the three processes are the same, which has facilitated the present analysis because the optimized piston trajectories of the Carnot and Stirling cycles are the same as those of the Brayton and Otto cycles, respectively.

  1. Development of an accelerating piston implosion-driven launcher

    International Nuclear Information System (INIS)

    Huneault, J; Loiseau, J; Higgins, A J

    2014-01-01

    The ability to soft-launch projectiles to velocities exceeding 10 km/s is of interest for a number of scientific fields, including orbital debris impact testing and equation of state research. Current soft-launch technologies have reached a performance plateau below this operating range. In the implosion-driven launcher (ILD) concept, explosives are used to dynamically compress a light driver gas to significantly higher pressures and temperatures than the propellant of conventional light-gas guns. The propellant of the IDL is compressed through the linear implosion of a pressurized tube. The imploding tube behaves like a piston which travels into the light gas at the explosive detonation velocity, thus forming an increasingly long column of shock-compressed gas which can be used to propel a projectile. The McGill designed IDL has demonstrated the ability to launch a 0.1-g projectile to 9.1 km/s. This work will focus on the implementation of a novel launch cycle in which the explosively driven piston is accelerated in order to gradually increase driver gas compression, thus maintaining a relatively constant projectile driving pressure. The theoretical potential of the concept as well as the experimental development of an accelerating piston driver will be examined.

  2. Aluminium matrix heterophase composites for air compressor pistons

    Directory of Open Access Journals (Sweden)

    M.Dyzia

    2011-04-01

    Full Text Available The article presents the results of surface test of composite shaped in the permanent mould casting process. As part of the research anddevelopment project realized in the Department of Materials Technology at the Silesian University of Technology, a pilot plant scale stand was built to manufacture of more than 50 kg suspensions in a single technological cycle. Made in industrial conditions castings to form in the five inner core mould mounted in GM110 permanent mould casting machine confirmed the possibility of the shaping the composite pistons. Castings made from composite suspension AlSi7Mg/SiC and AlSi7Mg/SiC + Cg according to the technology procedure were classified as correct and devoted to the proper machining forming working surfaces of the piston to the air compressor. Comparative tests were performed for the casting of unreinforced AlSi7Mg alloy and composite castings. To assess the ability to fill the mold cavity and the accuracy of mapping used in contour shape FRT analysis of the distance between the grooves on the surface of the piston skirt. Studies have confirmed the differences in the fluidity of alloy matrix and composites suspensions. The difference in the accuracy of the dimensional mapping mould does not disqualify of composite materials, all castings are classified as correct and used for machining.

  3. Wear of micro end mills

    DEFF Research Database (Denmark)

    Bissacco, Giuliano; Hansen, Hans Nørgaard; De Chiffre, Leonardo

    2005-01-01

    This paper addresses the important issue of wear on micro end mills considering relevant metrological tools for its characterization and quantification. Investigation of wear on micro end mills is particularly difficult and no data are available in the literature. Small worn volumes cause large...... part. For this investigation 200 microns end mills are considered. Visual inspection of the micro tools requires high magnification and depth of focus. 3D reconstruction based on scanning electron microscope (SEM) images and stereo-pair technique is foreseen as a possible method for quantification...

  4. Calculation of wear (f.i. wear modulus) in the plastic cup of a hip joint prosthesis

    NARCIS (Netherlands)

    Ligterink, D.J.

    1975-01-01

    The wear equation is applied to the wear process in a hip joint prosthesis and a wear modulus is defined. The sliding distance, wear modulus, wear volume, wear area, contact angle and the maximum normal stress were calculated and the theoretical calculations applied to test results. During the wear

  5. Development of high-performance sintered friction material for synchronizer ring; Koseino shoketsu synchronizer ring masatsu zairyo no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Miyajima, K; Fuwa, Y; Okajima, H; Yoshikawa, K [Toyota Motor Corp., Aichi (Japan); Nakamura, M [Japan Powder Metallurgy Co. Ltd., Tokyo (Japan)

    1997-10-01

    Increasing vehicle speed and power, high-performance synchronizer ring of manual transmission is required. We develop double layer sintered synchronizer ring for high performance and cost reduction. The main structure is consisted of ferrous sinter for high strength. In this paper, friction materials of sintered synchronizer ring are studied. We can get the good friction and anti-wear property by means of hard particles (FeTi, ZrO2), solid lubricant (Graphite) and suitable porosity in brass sinter matrix. And we also achieve high joining strength between double layers adding Cu-P material. 6 refs., 13 figs., 2 tabs.

  6. Measurement of fluid film thickness on the valve plate in oil hydraulic axial piston pumps (I): bearing pad effects

    International Nuclear Information System (INIS)

    Kim, Jong Ki; Jung, Jae Youn

    2003-01-01

    The tribological mechanism between the valve plate and the cylinder block in oil hydraulic axial piston pumps plays an important role on high power density. In this study, the fluid film thickness between the valve plate and the cylinder block was measured with discharge pressure and rotational speed by use of a gap sensor, and a slip ring system in the operating period. To investigate the effect of the valve plate shapes, we designed two valve plates with different shapes: the first valve plate was without a bearing pad, while the second valve plate had a bearing pad. It was found that both valve plates behaved differently with respect to the fluid film thickness characteristics. The leakage flow rates and the shaft torque were also experimented in order to clarify the performance difference between the valve plate without a bearing pad and the valve plate with a bearing pad. From the results of this study, we found out that in the oil hydraulic axial piston pumps, the valve plate with a bearing pad showed better film thickness contours than the valve plate without a bearing pad

  7. Should School Nurses Wear Uniforms?

    Science.gov (United States)

    Journal of School Health, 2001

    2001-01-01

    This 1958 paper questions whether school nurses should wear uniforms (specifically, white uniforms). It concludes that white uniforms are often associated with the treatment of ill people, and since many people have a fear reaction to them, they are not necessary and are even undesirable. Since school nurses are school staff members, they should…

  8. Wear resistance of cast iron

    Directory of Open Access Journals (Sweden)

    S. Pietrowski

    2008-10-01

    Full Text Available In this paper investigations of abrasive and adhesive wear resistance of different cast iron grades have been presented. Examinations showed, that the most advantageous pair of materials is the cast iron – the hardened steel with low-tempered martensite. It was found, that martensitic nodular cast iron with carbides is the most resistant material.

  9. The control of a free-piston engine generator. Part 1: Fundamental analyses

    Energy Technology Data Exchange (ETDEWEB)

    Mikalsen, R.; Roskilly, A.P. [Sir Joseph Swan Institute for Energy Research, Newcastle University, Newcastle upon Tyne, NE1 7RU, England (United Kingdom)

    2010-04-15

    Free-piston engines are under investigation by a number of research groups due to potential fuel efficiency and exhaust emissions advantages over conventional technology. The main challenge with such engines is the control of the piston motion, and this has not yet been fully resolved for all types of free-piston engines. This paper discusses the basic features of a single piston free-piston engine generator under development at Newcastle University and investigates engine control issues using a full-cycle simulation model. Control variables and disturbances are identified, and a control strategy is proposed. It is found that the control of the free-piston engine is a challenge, but that the proposed control strategy is feasible. Engine speed control does, however, represent a challenge in the current design. (author)

  10. Wear performance of laser processed tantalum coatings

    Energy Technology Data Exchange (ETDEWEB)

    Dittrick, Stanley; Balla, Vamsi Krishna; Bose, Susmita; Bandyopadhyay, Amit, E-mail: amitband@wsu.edu

    2011-12-01

    This first generation investigation evaluates the in vitro tribological performance of laser-processed Ta coatings on Ti for load-bearing implant applications. Linear reciprocating wear tests in simulated body fluid showed one order of magnitude less wear rate, of the order of 10{sup -4} mm{sup 3}(N.m){sup -1}, for Ta coatings compared to Ti. Our results demonstrate that Ta coatings can potentially minimize the early-stage bone-implant interface micro-motion induced wear debris generation due to their excellent bioactivity comparable to that of hydroxyapatite (HA), high wear resistance and toughness compared to popular HA coatings. Highlights: {yields} In vitro wear performance of laser processed Ta coatings on Ti was evaluated. {yields} Wear tests in SBF showed one order of magnitude less wear for Ta coatings than Ti. {yields} Ta coatings can minimize early-stage micro-motion induced wear debris generation.

  11. Alternative loop rings

    CERN Document Server

    Goodaire, EG; Polcino Milies, C

    1996-01-01

    For the past ten years, alternative loop rings have intrigued mathematicians from a wide cross-section of modern algebra. As a consequence, the theory of alternative loop rings has grown tremendously. One of the main developments is the complete characterization of loops which have an alternative but not associative, loop ring. Furthermore, there is a very close relationship between the algebraic structures of loop rings and of group rings over 2-groups. Another major topic of research is the study of the unit loop of the integral loop ring. Here the interaction between loop rings and group ri

  12. Health effects associated with exposure to radioactively contaminated gold rings

    International Nuclear Information System (INIS)

    Baptiste, M.S.; Rothenberg, R.; Nasca, P.C.; Janerich, D.T.; Stutzman, C.D.; Rimawi, K.; O'Brien, W.; Matuszek, J.

    1984-01-01

    This study was designed to assess the health risks associated with exposure to radioactively contaminated gold rings. A group of 135 exposed individuals, who were identified through a statewide jewelry screening program, were studied to determine the frequency of carcinoma and other skin problems on the ring finger. Severity of skin problems increased with increasing length of wear. Forty-one of the exposures were associated with mild to severe skin problems. Nine of the individuals studied were diagnosed as having histologically confirmed squamous cell carcinomas at the site of exposure. The incidence of skin cancer on the ring finger was eleven times that expected for men and forty-five times that expected for women. These data indicate that physicians who have patients with skin lesions of the ring finger should be aware of the possibility of exposure to a radioactive gold ring

  13. Extended Analytic Linear Model of Hydraulic Cylinder With Respect Different Piston Areas and Volumes

    OpenAIRE

    Petr KOŇAŘÍK

    2009-01-01

    Standard analytic linear model of hydraulic cylinder usually comes from assumptions of identical action piston areas on both sides of hydraulic cylinder (double piston rod) and suitable operation point, which is usually chosen in the middle of piston. By reason of that volumes inside of cylinder are than same. Moreover for control of that arrangement of hydraulic cylinder, usually controlled by 4/3 servovalve, the same mount of flows comes in and comes out to each of chambers of hydraulic cyl...

  14. Calculation of parameters of radial-piston reducer based on the use of functional semantic networks

    Directory of Open Access Journals (Sweden)

    Pashkevich V.M.

    2016-12-01

    Full Text Available The questions of сalculation of parameters of radial-piston reducer are considered in this article. It is used the approach which is based technologies of functional semantic networks. It is considered possibility applications of functional se-mantic networks for calculation of parameters of radial-piston reducer. Semantic networks to calculate the mass of the radial piston reducer are given.

  15. Measurement of Wear in Radial Journal Bearings

    NARCIS (Netherlands)

    Ligterink, D.J.; Ligterink, D.J.; de Gee, A.W.J.

    1996-01-01

    this article, the measurement of wear in radial journal bearings is discussed, where a distinction is made between stationary and non-stationary contact conditions. Starting with Holm/Archard's wear law, equations are derived for the calculation of the specific wear rate k of the bearing material as

  16. Backside wear in modern total knee designs.

    Science.gov (United States)

    Jayabalan, Prakash; Furman, Bridgette D; Cottrell, Jocelyn M; Wright, Timothy M

    2007-02-01

    Although modularity affords various options to the orthopedic surgeon, these benefits come at a price. The unintended bearing surface between the back surface of the tibial insert and the metallic tray results in micromotion leading to polyethylene wear debris. The objective of this study was to examine the backside wear of tibial inserts from three modern total knee designs with very different locking mechanisms: Insall-Burstein II (IB II), Optetrak, and Advance. A random sample of 71 inserts were obtained from our institution's retrieval collection and examined to assess the extent of wear, depth of wear, and wear damage modes. Patient records were also obtained to determine patient age, body mass index, length of implantation, and reason for revision. Modes of wear damage (abrasion, burnishing, scratching, delamination, third body debris, surface deformation, and pitting) were then scored in each zone from 0 to 3 (0 = 0%, 1 = 0-10%, 2 = 10-50%, and 3 = >50%). The depth of wear was subjectively identified as removal of manufacturing identification markings stamped onto the inferior surface of the polyethylene. Both Advance and IB II polyethylene inserts showed significantly higher scores for backside wear than the Optetrak inserts. All IB II and Advance implants showed evidence of backside wear, whereas 17% (5 out of 30) of the retrieved Optetrak implants had no observable wear. There were no significant differences when comparing the depth of wear score between designs. The locking mechanism greatly affects the propensity for wear and should be considered when choosing a knee implant system.

  17. 3-D steady state thermomechanical analysis of a piston of a direct injection diesel engine

    International Nuclear Information System (INIS)

    Abid, M.; Bannikov, M.G.; Ali, H.

    2005-01-01

    Piston of internal combustion engine is subjected to the coupled action of the thermal and the mechanical loads. Piston distortion due to temperature nonuniformities has a significant impact on the piston component of the engine friction. In regions of high heat flux, thermal stresses can reach levels that would cause fatigue cracking. Any change of engine design and/or operating conditions resulting in an increased heat flux through the piston may cause engine performance deterioration and even engine failure. This work presents a three-dimensional finite element analysis of a piston of a high power direct injection diesel engine. The goal of such analysis was the prediction of the piston behavior in conditions of the increased brake mean effective pressure and engine speed. Thermal and mechanical loads required for analysis were obtained from the engine cycle simulation. Thermal boundary conditions were determined in the form of the cycle averaged temperature of combustion chamber content and cycle averaged spatially distributed heat transfer coefficients. Mechanical load was represented by the combined gas pressure and inertia forces. Using ANSYS software temperature and stress distributions within the piston body as well as piston deformation were obtained. Analysis was performed for separate as well as combined load. It was shown that contribution of mechanical load is insignificant and can be neglected. Main emphasis is given to scuffing and strength analysis of the piston. Results obtained at various thermal loads are discussed. (author)

  18. Assessment of 25 kW free-piston Stirling technology alternatives for solar applications

    Science.gov (United States)

    Erbeznik, Raymond M.; White, Maurice A.; Penswick, L. B.; Neely, Ronald E.; Ritter, Darren C.; Wallace, David A.

    1992-01-01

    The final design, construction, and testing of a 25-kW free-piston advanced Stirling conversion system (ASCS) are examined. The final design of the free-piston hydraulic ASCS consists of five subsystems: heat transport subsystem (solar receiver and pool boiler), free-piston hydraulic Stirling engine, hydraulic subsystem, cooling subsystem, and electrical and control subsystem. Advantages and disadvantages are identified for each technology alternative. Technology alternatives considered are gas bearings vs flexure bearings, stationary magnet linear alternator vs moving magnetic linear alternator, and seven different control options. Component designs are generated using available in-house procedures to meet the requirements of the free-piston Stirling convertor configurations.

  19. Dynamic response characteristics evaluation of hydrostatic bearing in hydraulic piston pump/motor

    International Nuclear Information System (INIS)

    Ham, Young Bog; Yun, So Nam; Kim, Dong Soo; Choi, Byoung Oh; Kim, Sung Dong

    2001-01-01

    In swash plate type axial piston hydraulic pump and motor, the piston shoe is periodically pressurized with square function shape by supply pressure load as rotation of cylinder barrel. Therefore the recess pressure ono bottom part of piston shoe is suddenly increase through orifice in the piston shoe. In this study, we simulated that the frequency response of the recess pressure against with change of supply pressure with analysis tool. Also, we evaluate the dynamic response characteristics of overbalanced hydrostatic bearing with change of the orifice diameter

  20. Unsteady response of flow system around balance piston in a rocket pump

    Science.gov (United States)

    Kawasaki, S.; Shimura, T.; Uchiumi, M.; Hayashi, M.; Matsui, J.

    2013-03-01

    In the rocket engine turbopump, a self-balancing type of axial thrust balancing system using a balance piston is often applied. In this study, the balancing system in liquid-hydrogen (LH2) rocket pump was modeled combining the mechanical structure and the flow system, and the unsteady response of the balance piston was investigated. The axial vibration characteristics of the balance piston with a large amplitude were determined, sweeping the frequency of the pressure fluctuation on the inlet of the balance piston. This vibration was significantly affected by the compressibility of LH2.

  1. Analysis and dynamical modeling of a piston valve for a wave energy converter

    OpenAIRE

    Cruz Gispert, Albert

    2014-01-01

    The Ocean Grazer, a novel wave energy converter, has been proposed by the University of Groningen. The system can collect and store multiple forms of ocean energy, with a pistontype hydraulic pump as its core technology. In this work, the dynamical behavior of a piston valve for use in the piston pump system is studied. In order to gain insight into the dynamical behavior of the piston-type hydraulic pump, a simulation model is developed to describe the movement of the piston v...

  2. Coupled hydrodynamic-structure analysis of piston motion in reciprocating compressors

    International Nuclear Information System (INIS)

    Moon, Seung Ju; Cho, Jin Rae; Ryu, Sung Hyon

    2003-01-01

    The piston slap phenomenon is one of the major noise source of reciprocating compressors used in household electric appliances. In response to public demand, strict regulations are increasingly being imposed on the allowable noise level which is caused mostly by household electric appliances. In this paper, the dynamic behavior of suction and discharge valves are analytically calculated and the lubricant behavior between piston and cylinder are investigated using two-dimensional Reynolds equation. And the piston slap caused by the piston secondary motion is investigated by the finite element method

  3. Advantages and disadvantages of composite pistons for small power combustion engines

    Directory of Open Access Journals (Sweden)

    Andrzej POSMYK

    2007-01-01

    Full Text Available The results of technological and metallographic investigations of small dimensions, low power combustion engines piston has been presented. Semi-finished pistons has been produced by gravitations casting of composite material with EN-AC-47000 alloy matrix +15% Al2O3P and EN-AW-6061 alloy matrix +22% Al2O3P. Some small casting defects have been detected during the cutting process of piston made of composite material with EN-AC-47000 alloy matrix +15% Al2O3P. These defects were sources of micro perforations. In the piston made of EN-AW-6061 alloy matrix has been any defects detected.

  4. Assessment of wear dependence parameters in complex model of cutting tool wear

    Science.gov (United States)

    Antsev, A. V.; Pasko, N. I.; Antseva, N. V.

    2018-03-01

    This paper addresses wear dependence of the generic efficient life period of cutting tools taken as an aggregate of the law of tool wear rate distribution and dependence of parameters of this law's on the cutting mode, factoring in the random factor as exemplified by the complex model of wear. The complex model of wear takes into account the variance of cutting properties within one batch of tools, variance in machinability within one batch of workpieces, and the stochastic nature of the wear process itself. A technique of assessment of wear dependence parameters in a complex model of cutting tool wear is provided. The technique is supported by a numerical example.

  5. Development of Cone Wedge Ring Expansion Test to Evaluate Mechanical Properties of Clad Tubing Structure

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jy-An John [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-10-01

    To determine the hoop tensile properties of irradiated fuel cladding in a hot cell, a cone wedge ring expansion test method was developed. A four-piece wedge insert was designed with tapered angles matched to the cone shape of a loading piston. The ring specimen was expanded in the radial direction by the lateral expansion of the wedges under the downward movement of the piston. The advantages of the proposed method are that implementation of the test setup in a hot cell is simple and easy, and that it enables a direct strain measurement of the test specimen from the piston’s vertical displacement soon after the wedge-clad contact resistance is initiated.

  6. Free-piston Stirling technology for space power

    International Nuclear Information System (INIS)

    Slaby, J.G.

    1994-01-01

    An overview is presented of the NASA Lewis Research Center free-piston Stirling engine activities directed toward space power. This work is being carried out under NASA's new Civil Space Technology Initiative (CSTI). The overall goal of CSTI's High Capacity Power element is to develop the technology base needed to meet the long duration, high capacity power requirements for future NASA space missions. The Stirling cycle offers an attractive power conversion concept for space power needs. Discussed in this paper is the completion of the Space Power Demonstrator Engine (SPDE) testing - culminating in the generation of 25 kW of engine power from a dynamically-balanced opposed-piston Stirling engine at a temperature ratio of 2.0. Engine efficiency was approximately 22 percent. The SPDE recently has been divided into two separate single-cylinder engines, called Space Power Research Engines (SPRE), that now serve as test beds for the evaluation of key technology disciplines. These disciplines include hydrodynamic gas bearings, high-efficiency linear alternators, space qualified heat pipe heat exchangers, oscillating flow code validation, and engine loss understanding. The success of the SPDE at 650 K has resulted in a more ambitious Stirling endeavor - the design, fabrication, test and evaluation of a designed-for-space 25 kW per cylinder Stirling Space Engine (SSE). The SSE will operate at a hot metal temperature of 1050 K using superalloy materials. This design is a low temperature confirmation of the 1300 K design. It is the 1300 K free-piston Stirling power conversion system that is the ultimate goal; to be used in conjunction with the SP-100 reactor. The approach to this goal is in three temperature steps. However, this paper concentrates on the first two phases of this program - the 650 K SPDE and the 1050 K SSE

  7. Vacuum stress and closed paths in rectangles, pistons and pistols

    International Nuclear Information System (INIS)

    Fulling, S A; Kaplan, L; Kirsten, K; Liu, Z H; Milton, K A

    2009-01-01

    Rectangular cavities are solvable models that nevertheless touch on many of the controversial or mysterious aspects of the vacuum energy of quantum fields. This paper is a thorough study of the two-dimensional scalar field in a rectangle by the method of images, or closed classical (or optical) paths, which is exact in this case. For each point r and each specularly reflecting path beginning and ending at r, we provide formulae for all components of the stress tensor T μν (r), for all values of the curvature coupling constant ξ and all values of an ultraviolet cutoff parameter. Arbitrary combinations of Dirichlet and Neumann conditions on the four sides can be treated. The total energy is also investigated, path by path. These results are used in an attempt to clarify the physical reality of the repulsive (outward) force on the sides of the box predicted by calculations that neglect both boundary divergences and the exterior of the box. Previous authors have studied 'piston' geometries that avoid these problems and have found the force to be attractive. We consider a 'pistol' geometry that comes closer to the original problem of a box with a movable lid. We find again an attractive force, although its origin and detailed behavior are somewhat different from the piston case. However, the pistol (and the piston) model can be criticized for extending idealized boundary conditions into short distances where they are physically implausible. Therefore, it is of interest to see whether leaving the ultraviolet cutoff finite yields results that are more plausible. We then find that the force depends strongly on a geometrical parameter; it can be made repulsive, but only by forcing that parameter into the regime where the model is least convincing physically

  8. Influence of nitrogen ion implantation on wear studied by a new laboratory wear test

    Energy Technology Data Exchange (ETDEWEB)

    Szilagyi, E.; Paszti, F.; Vertessy, Z. (Central Research Inst. for Physics, Hungarian Academy of Sciences, Budapest (Hungary))

    1991-05-01

    A new laboratory wear test is developed in which the wear trace is measured by Rutherford backscattering spectrometry. The advantage of the new test is that the wear rate is directly determinable. The new test setup has been used to study the effects of nitrogen implantation on the wear processes on 115CrV3 steel. The wear rate decreases by a factor of 2 at 4x10{sup 17} N{sup +}/cm{sup 2} implanted dose. (orig.).

  9. β Style Free-Piston Stirling Engine Control System Research

    Directory of Open Access Journals (Sweden)

    Xu Jian

    2016-01-01

    Full Text Available For the Free-Piston Stirling Engines (FPSE control system, a three -phase bridge circuit is reused as the system output about rectifier and start inverter. When FPSE system is in the power stage, the double closed loop control strategy and optimization algorithm of PI control parameters is adopted to ensure the highest system transmission efficiency under the requirements of the system output power and guarantee the stability of the running system. The simulation results prove the effectiveness of the above research content.

  10. An introductory model of a one-piston engine

    International Nuclear Information System (INIS)

    GlarIa, Jaime; Wendler, Thomas; Goodwin, Graham

    2005-01-01

    Reciprocating internal combustion engine models have the antithetical goals of accurately describing complex nonlinear behaviour and being simple enough for such purposes as automatic control and online diagnosis. A one-piston four-stroke engine is modelled here by recursively stating simple physical equations. To do that, the domestic ideas of domination and dependence are called as methodological tools for modelling, since they hand out necessary and sufficient equations with few manoeuvres, allocate simulations with the same characteristic and, hopefully, provide a fine way to understanding. The resulting model reveals both steady cycles and transient behaviour

  11. Piston cylinder cell for high pressure ultrasonic pulse echo measurements

    Energy Technology Data Exchange (ETDEWEB)

    Kepa, M. W., E-mail: mkepa@staffmail.ed.ac.uk; Huxley, A. D. [SUPA, Centre for Science at Extreme Conditions and School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3JZ (United Kingdom); Ridley, C. J.; Kamenev, K. V. [Centre for Science at Extreme Conditions and School of Engineering, University of Edinburgh, Edinburgh EH9 3FD (United Kingdom)

    2016-08-15

    Ultrasonic techniques such as pulse echo, vibrating reed, or resonant ultrasound spectroscopy are powerful probes not only for studying elasticity but also for investigating electronic and magnetic properties. Here, we report on the design of a high pressure ultrasonic pulse echo apparatus, based on a piston cylinder cell, with a simplified electronic setup that operates with a single coaxial cable and requires sample lengths of mm only. The design allows simultaneous measurements of ultrasonic velocities and attenuation coefficients up to a pressure of 1.5 GPa. We illustrate the performance of the cell by probing the phase diagram of a single crystal of the ferromagnetic superconductor UGe{sub 2}.

  12. A liquid helium piston pump with a superconducting drive

    International Nuclear Information System (INIS)

    Schmidt, C.

    1984-01-01

    This chapter describes a bellows pump where the driving force is achieved by an arrangement of three superconducting coils. The pump was designed for use in the supercritical helium flow circuit of the LCT-conductor test facility. The main advantage of the superconducting drive, compared to conventional pumps with external drive, is the compact design. Force transferring parts between 4.2 K and room temperature are not necessary. The pump was tested in a closed loop arrangement. The superconducting drive for a piston pump consists of a moving coil in a constant background field. Other coil configurations and the upscaling of the pump design are discussed

  13. Free-Piston Stirling Machine for Extreme Temperatures

    Science.gov (United States)

    Wood, James Gary (Inventor)

    2013-01-01

    A free piston Stirling machine including a thermal buffer tube extending from the machine's expansion space and surrounded by its heat rejector and its regenerator, a displacer cylinder extending from the thermal buffer tube to the compression space and surrounded by the heat rejecting heat exchanger, and a displacer that reciprocates within an excursion limit that extends into the regenerator by no more than 20% of the length of the regenerator during normal operation and preferably within excursion limits that are substantially the length of the heat rejector.

  14. Wear resistance and electrical properties of functionally graded epoxy-resin/silica composites

    International Nuclear Information System (INIS)

    Rihan, Y. A.; Abd El-Bary, B.

    2012-12-01

    In this paper graded Silica/Epoxy composite fabricated by controlled mold filling to obtain a stepwise graded structure. The generated graded structure was controlled by the w 1% content of silica particulates of size range from (45 μm-250 μm). Microstructural characterization was conducted using Scanning Electron Microscope (SEM). Electrical properties were conducted in High Voltage-Lab using Sphere-Plate Electrode System and Insulating resistance equipment s. Wear characteristics were studied using Block-on-Ring wear testing machine for the different layers of the graded silica/epoxy composites, The prepared materials are used as coating materials for the floors of chemical laboratories. (Author)

  15. Impact of the Dapivirine Vaginal Ring on Sexual Experiences and Intimate Partnerships of Women in an HIV Prevention Clinical Trial: Managing Ring Detection and Hot Sex.

    Science.gov (United States)

    Laborde, Nicole D; Pleasants, Elizabeth; Reddy, Krishnaveni; Atujuna, Millicent; Nakyanzi, Teopista; Chitukuta, Miria; Naidoo, Sarita; Palanee-Phillips, Thesla; Baeten, Jared M; Montgomery, Elizabeth T

    2018-02-01

    Vaginally-inserted HIV prevention methods have been reported to impact the sexual experience for women and their partners, and hence impacts acceptability of and adherence to the method. We analyzed in-depth interviews and focus group discussions about participants' sexual experiences while wearing the ring, collected during the MTN-020/ASPIRE phase 3 safety and effectiveness trial of a dapivirine vaginal ring for HIV prevention in Malawi, South Africa, Uganda, and Zimbabwe. Most women reported that partners did not feel the ring during sex, however, women felt they had to manage their partners' interaction with or reaction to the ring. In maintaining positive relationships, women were concerned about partners' discovering ring use and about ensuring that partners had a good sexual experience with them. Finally women were concerned about how they themselves experienced sex with the ring. Some found that the ring made the vaginal environment more desirable for their partners and themselves.

  16. Impact of the Dapivirine Vaginal Ring on Sexual Experiences and Intimate Partnerships of Women in an HIV Prevention Clinical Trial: Managing Ring Detection and Hot Sex

    Science.gov (United States)

    Pleasants, Elizabeth; Reddy, Krishnaveni; Atujuna, Millicent; Nakyanzi, Teopista; Chitukuta, Miria; Naidoo, Sarita; Palanee-Phillips, Thesla; Baeten, Jared M.; Montgomery, Elizabeth T.

    2018-01-01

    Vaginally-inserted HIV prevention methods have been reported to impact the sexual experience for women and their partners, and hence impacts acceptability of and adherence to the method. We analyzed in-depth interviews and focus group discussions about participants’ sexual experiences while wearing the ring, collected during the MTN-020/ASPIRE phase 3 safety and effectiveness trial of a dapivirine vaginal ring for HIV prevention in Malawi, South Africa, Uganda, and Zimbabwe. Most women reported that partners did not feel the ring during sex, however, women felt they had to manage their partners’ interaction with or reaction to the ring. In maintaining positive relationships, women were concerned about partners’ discovering ring use and about ensuring that partners had a good sexual experience with them. Finally women were concerned about how they themselves experienced sex with the ring. Some found that the ring made the vaginal environment more desirable for their partners and themselves. PMID:29151197

  17. Friction and wear in sodium

    International Nuclear Information System (INIS)

    Hoffman, N.J.; Droher, J.J.

    1973-01-01

    In the design of a safe and reliable sodium-cooled reactor one of the more important problem areas is that of friction and wear of components immersed in liquid sodium or exposed to sodium vapor. Sodium coolant at elevated temperatures may severely affect most oxide-bearing surface layers which provide corrosion resistance and, to some extent, lubrication and surface hardness. Consequently, accelerated deterioration may be experienced on engaged-motion contact surfaces, which could result in unexpected reactor shutdown from component malfunction or failure due to galling and seizure. An overall view of the friction and wear phenomena encountered during oscillatory rubbing of surfaces in high-temperature, liquid-sodium environments is presented. Specific data generated at the Liquid Metal Engineering Center (LMEC) on this subject is also presented. (U.S.)

  18. Wear of rolling element bearings in sodium

    International Nuclear Information System (INIS)

    Campbell, C.S.

    1976-01-01

    Rolling element bearings and related mechanisms are attractive for service in liquid sodium but it is not clear what minimum wear rate can be anticipated. For axially loaded angular contact bearings rotation is incompatible with pure rolling on both races and wear arises from the resulting ball spin. The initial pressure distributions and sizes of the contact ellipses can be calculated but will change with bearing wear. However, the most effective distribution for producing wear would be for the full loads to be borne on the tips of the contact areas, whose maximum length is given by examination of the race wear tracks. A calculation on such a basis should set a lower limit for the wear coefficient. Both the torque and instantaneous wear rate of a bearing will be similar functions of the integral over the contact areas of the product of contact pressure and radius from the ball spin axis. A better estimate of wear coefficient should be obtained by relating the average torque, the average wear, the initial torque and the initial wear where the conditions are known. Analysis of tests in sodium at 400 0 C of high speed steel and Stellite bearings by these methods indicates specific wear rates of the order of 10 -15 m 3 /N-m, not unduly out of line with the range of values found in conventional sliding tests

  19. Development of velocity interferometer and its application to piston motion measurement in a compression tube of freepiston shock tube; Sokudo kanshokei no kaihatsu to sono jiyu piston shogekihakan no asshuku kannai no piston undo no keisoku eno oyo ni kansuru kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Koremoto, K.; Hashimoto, T. [Tohoku University, Sendai (Japan); Takayama, K. [Tohoku University, Sendai (Japan). Inst. of Fluid Science; Ito, K [National Aerospace Laboratory, Tokyo (Japan)

    1999-10-25

    A free piston shock tunnel has been intensively used as a hypersonic flow ground test facility and its characteristics depend sensitively upon the piston motion in its compression tube. The continuous measurement of the piston motion in its compression tube was studied in an analogue facility in which a piston motion in a 50mm dia. and 2000mm long compression tube was measured continuously and accurately from its start to the collision with bumper section. To achieve it a velocity interferometer was developed particularly to measure the piston speed in it. Then piston motions were successfully measured and result agreed very well with numerical result. (author)

  20. Fluoridation and tooth wear in Irish adults.

    LENUS (Irish Health Repository)

    Burke, F M

    2010-10-01

    The aim of this study was to determine the prevalence of tooth wear in adults in Ireland and its relationship with water fluoridation. The National Survey of Adult Oral Health was conducted in 2000\\/2001. Tooth wear was determined using a partial mouth examination assessing the upper and lower anterior teeth. A total of 2456 subjects were examined. In this survey, increasing levels and severity of tooth wear were associated with ageing. Men were more affected by tooth wear and were more likely to be affected by severe tooth wear than women. It was found that age, and gender were significant predictors of tooth wear (P < 0.01). Overall, there was no significant relationship between fluoridation and tooth wear in this study.

  1. Piston Aviation Fuel Initiative (PAFI) – A Review

    Science.gov (United States)

    Thanikasalam, K.; Rahmat, M.; Fahmi, A. G. Mohammad; Zulkifli, A. M.; Shawal, N. Noor; Ilanchelvi, K.; Ananth, M.; Elayarasan, R.

    2018-05-01

    Aviation gasoline (Avgas) has remained unchanged for seventy years and the existing fleet of piston aircraft was designed to be compatible with its chemical and physical properties to achieve superior levels of safety. Tetra-ethyl lead (TEL) is an octane-enhancing metal additive used in aviation gasoline to prevent knocking. Studies have shown that lead causes brain damage in children reducing their IQ and cardiovascular difficulties and kidney failure in adults. Friends of the Earth (FOE) petitioned the Environmental Protection Agency (EPA) in 2006 to make a finding that lead emissions from general aviation (GA) aircraft cause to public health endangerment or carry out studies and issue a report on its findings. PAFI was set up by Federal Aviation Administration (FAA) to find most suitable unleaded replacements for Avgas to recognize best unleaded fuel that have the capacity to in fact satisfy the requirements of the present aircraft fleet while additionally considering the creation, dispersion, cost, availability, environmental impacts. This study will technically review PAFI and broaden the limited knowledge on piston aviation fuels in Malaysia by giving a comprehensive analysis and possible gap in reciprocation aviation engine market in Malaysia.

  2. Application of the free piston concept to Vuilleumier heat pumps

    Energy Technology Data Exchange (ETDEWEB)

    Ruether, J.; Kuehl, H.D.; Schulz, S. [Dortmund Univ. (Germany). Inst. fuer Thermodynamik

    2000-07-01

    In this contribution the 64 different possible set-ups of the oscillation system for the two displacers of a {beta}-type free piston Vuilleumier heat pump are discussed. Many of these alternatives can be disregarded as they are unable to oscillate in a self-sustaining mode. To decide about this ability the differential equations describing the system dynamics are derived. For simplicity reasons damping is neglected. Furthermore some practical aspects and the starting behaviour of the machine are taken into account. Based on this analysis the best configuration was chosen to be realised as a modification of the FPV2 free piston Vuilleumier heat pump. The new design is described and first experimental results of the modified version are presented. (orig.) [German] Ausgehend von der Gesamtheit aller moeglichen Schwingungssysteme fuer das Kolbensystem einer Freikolben-Vuilleumier-Waermepumpe wird der Weg zu einem fuer den Einsatz in der Heizungstechnik geeigneten Konzept beschrieben. Wesentliches Kriterium ist dabei die Faehigkeit zur selbsterregten Schwingung, die anhand der die Kinematik des Systems beschreibenden Differentialgleichungen beurteilt wird. Dabei kann der Einfluss der Daempfung unberuecksichtigt bleiben. Praktische Ueberlegungen und insbesondere das Startverhalten der entsprechenden Konfigurationen werden ebenfalls beruecksichtigt. Das auf Grundlage der obigen Kriterien ausgewaehlte Kolbensystem wird durch Modifikation der FPV2 Freikolben-Vuilleumier-Waermepumpe realisiert. Entsprechende Umbauarbeiten sowie erste Betriebserfahrungen und Messdaten werden vorgestellt. (orig.)

  3. New 5 Kilowatt Free-piston Stirling Space Convertor Developments

    Science.gov (United States)

    Brandhorst, Henry W., Jr.; Chapman, Peter A., Jr.

    2007-01-01

    The NASA Vision for Exploration of the moon may someday require a nuclear reactor coupled with a free-piston Stirling convertor at a power level of 30-40 kW. In the 1990s, Mechanical Technology Inc. s Stirling Engine Systems Division (some of whose Stirling personnel are now at Foster-Miller, Inc.) developed a 25 kW free piston Stirling Space Power Demonstrator Engine under the SP-100 program. This system consisted of two 12.5 kW engines connected at their hot ends and mounted in tandem to cancel vibration. Recently, NASA and DoE have been developing dual 55 W and 80 W Stirling convertor systems for potential use with radioisotope heat sources. Total test times of all convertors in this effort exceed 120,000 hours. Recently, NASA began a new project with Auburn University to develop a 5 kW, single convertor for potential use in a lunar surface reactor power system. Goals of this development program include a specific power in excess of 140 W/kg at the convertor level, lifetime in excess of five years and a control system that will safely manage the convertors in case of an emergency. Auburn University awarded a subcontract to Foster-Miller, Inc. to undertake development of the 5 kW Stirling Convertor Assembly. The characteristics of the design along with progress in developing the system will be described.

  4. A free-piston Stirling cryocooler using metal diaphragms

    Science.gov (United States)

    Caughley, Alan; Sellier, Mathieu; Gschwendtner, Michael; Tucker, Alan

    2016-12-01

    A novel concept for a free-piston Stirling cryocooler has been proposed. The concept uses a pair of metal diaphragms to seal and suspend the displacer of a free-piston Stirling cryocooler. The diaphragms allow the displacer to move without rubbing or moving seals, potentially resulting in a long-life mechanism. When coupled to a metal diaphragm pressure wave generator, the system produces a complete Stirling cryocooler with no rubbing parts in the working gas space. Initial modelling of this concept using the Sage modelling tool indicates the potential for a useful cryocooler. A proof-of-concept prototype was constructed and achieved cryogenic temperatures. A second prototype was designed and constructed using the experience gained from the first. The prototype produced 29 W of cooling at 77 K and reached a no-load temperature of 56 K. Sage predicted the macroscopic behaviour of the prototype well but did not provide sufficient insights to improve performance significantly. This paper presents details of the development, modelling and testing of the proof-of-concept prototype and a second, improved prototype.

  5. Advanced Controller Developed for the Free-Piston Stirling Convertor

    Science.gov (United States)

    Gerber, Scott S.

    2005-01-01

    A free-piston Stirling power convertor is being considered as an advanced power-conversion technology for future NASA deep-space missions requiring long-life radioisotope power systems. The NASA Glenn Research Center has identified key areas where advanced technologies can enhance the capability of Stirling energy-conversion systems. One of these is power electronic controls. Current power-conversion technology for Glenn-tested Stirling systems consists of an engine-driven linear alternator generating an alternating-current voltage controlled by a tuning-capacitor-based alternating-current peak voltage load controller. The tuning capacitor keeps the internal alternator electromotive force (EMF) in phase with its respective current (i.e., passive power factor correction). The alternator EMF is related to the piston velocity, which must be kept in phase with the alternator current in order to achieve stable operation. This tuning capacitor, which adds volume and mass to the overall Stirling convertor, can be eliminated if the controller can actively drive the magnitude and phase of the alternator current.

  6. Free-piston Stirling technology for space power

    Science.gov (United States)

    Slaby, Jack G.

    1989-01-01

    An overview is presented of the NASA Lewis Research Center free-piston Stirling engine activities directed toward space power. This work is being carried out under NASA's new Civil Space Technology Initiative (CSTI). The overall goal of CSTI's High Capacity Power element is to develop the technology base needed to meet the long duration, high capacity power requirements for future NASA space missions. The Stirling cycle offers an attractive power conversion concept for space power needs. Discussed here is the completion of the Space Power Demonstrator Engine (SPDE) testing-culminating in the generation of 25 kW of engine power from a dynamically-balanced opposed-piston Stirling engine at a temperature ratio of 2.0. Engine efficiency was approximately 22 percent. The SPDE recently has been divided into two separate single-cylinder engines, called Space Power Research Engine (SPRE), that now serve as test beds for the evaluation of key technology disciplines. These disciplines include hydrodynamic gas bearings, high-efficiency linear alternators, space qualified heat pipe heat exchangers, oscillating flow code validation, and engine loss understanding.

  7. Cold starting characteristics analysis of hydraulic free piston engine

    International Nuclear Information System (INIS)

    Zhang, Shuanlu; Zhao, Zhenfeng; Zhao, Changlu; Zhang, Fujun; Wang, Shan

    2017-01-01

    The cold start characteristic of hydraulic free piston diesel engine may affect its stable operation. Therefore the specific cold start characteristics, such as BDC or TDC positions, pressure in-cylinder, heat release rate, should be investigated in detail. These parameters fluctuate in some regularity in the cod start process. With the development of the free piston engine prototype and the establishment of test bench, the results are obtained. For the dynamic results, the fluctuation range of TDC and BDC positions is 8 mm and decreases with time. The thermodynamic results show that the combustion process is not stable and the pressure in-cylinder fluctuates largely in the cold start process. In addition, the combustion is rapid and knock happens inevitably. In order to investigate the reasons, a CFD model is established for temperature analysis in-cylinder and heat transfer conditions. It is found that higher start wall temperature will lead to more uniform temperature distribution. The delay period may decreases and heat release will move forward. This reason is analyzed by thermodynamic derivation based on the first law of thermodynamics. Finally, the improvement suggestions of cold start strategy are proposed. - Highlights: • The cold start behaviors of HFPE are investigated in detail. • CFD method is used for simulating temperature distribution in start process. • Thermodynamic derivation uncovers the compression temperature distribution. • The improvement suggestions of cold start strategy are proposed.

  8. Real-time estimation of differential piston at the LBT

    Science.gov (United States)

    Böhm, Michael; Pott, Jörg-Uwe; Sawodny, Oliver; Herbst, Tom; Kürster, Martin

    2014-07-01

    In this paper, we present and compare different strategies to minimize the effects of telescope vibrations to the differential piston (OPD) for LINC/NIRVANA at the LBT using an accelerometer feedforward compensation approach. We summarize why this technology is of importance for LINC/NIRVANA, but also for future telescopes and instruments. We outline the estimation problem in general and its specifics at the LBT. Model based estimation and broadband filtering techniques can be used to solve the estimation task, each having its own advantages and disadvantages, which will be discussed. Simulation results and measurements at the LBT are shown to motivate and support our choice of the estimation algorithm for the instrument LINC/NIRVANA. We explain our laboratory setup aimed at imitating the vibration behaviour at the LBT in general, and the M2 as main contributor in particular, and we demonstrate the controller's ability to suppress vibrations in the frequency range of 8 Hz to 60 Hz. In this range, telescope vibrations are the most dominant disturbance to the optical path. For our measurements, we introduce a disturbance time series which has a frequency spectrum comparable to what can be measured at the LBT on a typical night. We show promising experimental results, indicating the ability to suppress differential piston induced by telescope vibrations by a factor of about 5 (RMS), which is significantly better than any currently commissioned system.

  9. Computer Aided Design of Kaplan Turbine Piston with\tSolidWorks

    Directory of Open Access Journals (Sweden)

    Camelia Jianu

    2010-10-01

    Full Text Available The paper presents the steps for 3D computer aided design (CAD of Kaplan turbine piston made in SolidWorks.The present paper is a tutorial for a Kaplan turbine piston 3D geometry, which is dedicaded to the Parts Sketch and Parts Features design and Drawing Geometry and Drawing Annotation.

  10. Computer Aided Design of Kaplan Turbine Piston with SolidWorks

    OpenAIRE

    Camelia Jianu

    2010-01-01

    The paper presents the steps for 3D computer aided design (CAD) of Kaplan turbine piston made in SolidWorks.The present paper is a tutorial for a Kaplan turbine piston 3D geometry, which is dedicaded to the Parts Sketch and Parts Features design and Drawing Geometry and Drawing Annotation.

  11. 76 FR 54373 - Airworthiness Directives; Austro Engine GmbH Model E4 Diesel Piston Engines

    Science.gov (United States)

    2011-09-01

    ... diesel piston engines, with high-pressure (HP) fuel pump, part number (P/N) E4A- 30-100-000, installed... Airworthiness Directives; Austro Engine GmbH Model E4 Diesel Piston Engines AGENCY: Federal Aviation... pressure supply for excessive oscillations to determine if high-pressure (HP) fuel pumps have been exposed...

  12. Durability, Performance, and Emission of Diesel Engines Using Carbon Fiber Piston and Liner

    Science.gov (United States)

    Afify, E. M.; Roberts, W. L.

    1999-01-01

    This report summarizes the research conducted by NC State University in investigating the durability, performance and emission of a carbon fiber piston and liner in our single cylinder research Diesel engine. Both the piston and liner were supplied to NC State University by NASA LaRC and manufactured by C-CAT under a separate contract to NASA LaRC. The carbon-carbon material used to manufacture the piston and liner has significantly lower thermal conductivity, coefficient of thermal expansion, and superior strength characteristics at elevated temperatures when compared to conventional piston materials such as aluminum. The results of the carbon-carbon fiber piston testing were compared to a baseline configuration, which used a conventional aluminum piston in a steel liner. The parameters measured were the brake specific fuel consumption, ignition delay, frictional horsepower, volumetric efficiency, and durability characteristics of the two pistons. Testing was performed using a naturally aspirated Labeco Direct Injection single cylinder diesel engine. Two test cases were performed over a range of loads and speeds. The fixed test condition between the aluminum and carbon-carbon piston configurations was the brake mean effective pressure. The measured data was the fuel consumption rate, volumetric efficiency, load, speed, cylinder pressure, needle lift, and exhaust gas temperature. The cylinder pressure, and fuel consumption, exhaust gas temperature, and needle lift were recorded using a National Instruments DAQ board and a PC. All test cases used Diesel no. 2 for fuel.

  13. Energy efficient piston configuration for effective air motion – A CFD study

    International Nuclear Information System (INIS)

    Gnana Sagaya Raj, Antony Raj; Mallikarjuna, Jawali Maharudrappa; Ganesan, Venkitachalam

    2013-01-01

    Highlights: ► All piston crown show similar flow pattern for experimental and simulated studies. ► Piston position plays a predominant role in the air pattern inside the cylinder. ► The flat bowl piston shows higher TKE compared to all other piston crown shape. ► The turbulence intensity and length scale are higher for flat bowl piston. ► The quantitative error between the CFD and PIV analysis is about 5%. -- Abstract: Air motion inside the cylinder is very important from the point of view of energy efficiency. In this direction, piston configuration plays a very crucial role. This study is concerned with the CFD analysis of in-cylinder air motion coupled with the comparison of predicted results with the experimental results available in the literature. Four configurations viz., flat, inclined, centre bowl and inclined offset bowl pistons have been studied. For numerical analysis STAR-CD CFD software has been used. Experimental results available in the literature for comparison are obtained by PIV measurements. From this study, it is concluded that a centre bowl on flat piston is found to be the best from the point of view of tumble ratio, turbulent kinetic energy, turbulent intensity and turbulent length scale which play very important role in imparting proper air motion, there by increasing the energy efficiency of the engine.

  14. Hydraulic cylinder simulates parameters of a free piston engine; Hydraulikzylinder simuliert Groessen fuer einen Freikolbenmotor

    Energy Technology Data Exchange (ETDEWEB)

    Rinderknecht, Frank [DLR Deutsches Zentrum fuer Luft- und Raumfahrt e.V., Stuttgart (Germany). Inst. fuer Fahrzeugkonzepte

    2011-01-10

    Important data are obtained in the development of a free piston engine by a test stand with a hydraulic cylinder which first simulates the power curves and motion of the individual components, then induces the motion of the system piston, and finally ensures safety against undesired forces. (orig.)

  15. Rings in drugs.

    Science.gov (United States)

    Taylor, Richard D; MacCoss, Malcolm; Lawson, Alastair D G

    2014-07-24

    We have analyzed the rings, ring systems, and frameworks in drugs listed in the FDA Orange Book to understand the frequency, timelines, molecular property space, and the application of these rings in different therapeutic areas and target classes. This analysis shows that there are only 351 ring systems and 1197 frameworks in drugs that came onto the market before 2013. Furthermore, on average six new ring systems enter drug space each year and approximately 28% of new drugs contain a new ring system. Moreover, it is very unusual for a drug to contain more than one new ring system and the majority of the most frequently used ring systems (83%) were first used in drugs developed prior to 1983. These observations give insight into the chemical novelty of drugs and potentially efficient ways to assess compound libraries and develop compounds from hit identification to lead optimization and beyond.

  16. Birth Control Ring

    Science.gov (United States)

    ... Health Food & Fitness Diseases & Conditions Infections Drugs & Alcohol School & Jobs Sports Expert Answers (Q&A) Staying Safe Videos for Educators Search English Español Birth Control Ring KidsHealth / For Teens / Birth Control Ring What's ...

  17. Groups, rings, modules

    CERN Document Server

    Auslander, Maurice

    2014-01-01

    This classic monograph is geared toward advanced undergraduates and graduate students. The treatment presupposes some familiarity with sets, groups, rings, and vector spaces. The four-part approach begins with examinations of sets and maps, monoids and groups, categories, and rings. The second part explores unique factorization domains, general module theory, semisimple rings and modules, and Artinian rings. Part three's topics include localization and tensor products, principal ideal domains, and applications of fundamental theorem. The fourth and final part covers algebraic field extensions

  18. Demonstration of a free piston Stirling engine driven linear alternator, phase I report

    International Nuclear Information System (INIS)

    Goldwater, B.; Piller, S.; Rauch, J.; Cella, A.

    1977-01-01

    The results of the work performed under Phase I of the free piston Stirling engine demonstrator program are described. The objective of the program is to develop a 2 kW free piston Stirling engine/linear alternator energy conversion system, for an isotopic heat source, with a greater than 30% overall efficiency. Phase I was a 15-month effort to demonstrate the feasibility of the system through analysis and experimental testing of the individual components. An introduction to Stirling engines and the details of the tasks completed are presented in five major sections: (1) introduction to Stirling engine; (2) preliminary design of an advanced free piston Stirling demonstrator engine; (3) design and test of a 1 kWE output linear alternator; (4) test of a model free piston Stirling engine; and (5) development of a free piston Stirling engine computer simulation code

  19. Demonstration of a free piston Stirling engine driven linear alternator, phase I report

    Energy Technology Data Exchange (ETDEWEB)

    Goldwater, B.; Piller, S.; Rauch, J.; Cella, A.

    1977-03-30

    The results of the work performed under Phase I of the free piston Stirling engine demonstrator program are described. The objective of the program is to develop a 2 kW free piston Stirling engine/linear alternator energy conversion system, for an isotopic heat source, with a greater than 30% overall efficiency. Phase I was a 15-month effort to demonstrate the feasibility of the system through analysis and experimental testing of the individual components. An introduction to Stirling engines and the details of the tasks completed are presented in five major sections: (1) introduction to Stirling engine; (2) preliminary design of an advanced free piston Stirling demonstrator engine; (3) design and test of a 1 kWE output linear alternator; (4) test of a model free piston Stirling engine; and (5) development of a free piston Stirling engine computer simulation code.

  20. Corrosion Characteristics of Welding Zones Welded with 1.25Cr-0.5 Mo Filler Metal to Forged Steel for Piston Crown Material

    International Nuclear Information System (INIS)

    Jeong, Jae-Hyun; Lee, Sung-Yul; Lee, Myeong-Hoon; Moon, Kyung-Man; Baek, Tae-Sil

    2015-01-01

    A heavy oil of low quality has been mainly used in the diesel engine of the merchant ship as the oil price has been significantly jumped for several years. Thus, a combustion chamber of the engine has been often exposed to severely corrosive environment more and more because temperature of the exhaust gas of the combustion chamber has been getting higher and higher with increasing of using the heavy oil of low quality. As a result, wear and corrosion of the engine parts such as exhaust valve, piston crown and cylinder head surrounded with combustion chamber are more serious compared to the other parts of the engine. Therefore, an optimum repair welding for these engine parts is very important to prolong their lifetime in a economical point of view. In this study, 1.25Cr-0.5Mo filler metal was welded with SMAW method in the forged steel which would be generally used with piston crown material. And the corrosion properties of weld metal, heat affected and base metal zones were investigated using electrochemical methods such as measurement of corrosion potential, anodic polarization curves, cyclic voltammogram and impedance etc. in 35% H 2 SO 4 solution. The weld metal and base metal zones exhibited the highest and lowest values of hardness respectively. And, the corrosion resistance of the heat affected and weld metal zones was also increased than that of the base metal zone. Furthermore, it appeared that the corrosive products with red color and local corrosion like as a pitting corrosion were more frequently observed on the surface of the base metal zone compared to the heat affected and weld metal zones. Consequently, it is suggested that the mechanical and corrosion characteristics of the piston crown can be predominantly improved by repair welding method using the 1.25Cr-0.5Mo electrode

  1. Corrosion Characteristics of Welding Zones Welded with 1.25Cr-0.5 Mo Filler Metal to Forged Steel for Piston Crown Material

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Jae-Hyun; Lee, Sung-Yul; Lee, Myeong-Hoon; Moon, Kyung-Man [Korea Maritime University, Dong Sam-Dong,Yong Do-ku, Busan (Korea, Republic of); Baek, Tae-Sil [Pohang College, Pohang (Korea, Republic of)

    2015-04-15

    A heavy oil of low quality has been mainly used in the diesel engine of the merchant ship as the oil price has been significantly jumped for several years. Thus, a combustion chamber of the engine has been often exposed to severely corrosive environment more and more because temperature of the exhaust gas of the combustion chamber has been getting higher and higher with increasing of using the heavy oil of low quality. As a result, wear and corrosion of the engine parts such as exhaust valve, piston crown and cylinder head surrounded with combustion chamber are more serious compared to the other parts of the engine. Therefore, an optimum repair welding for these engine parts is very important to prolong their lifetime in a economical point of view. In this study, 1.25Cr-0.5Mo filler metal was welded with SMAW method in the forged steel which would be generally used with piston crown material. And the corrosion properties of weld metal, heat affected and base metal zones were investigated using electrochemical methods such as measurement of corrosion potential, anodic polarization curves, cyclic voltammogram and impedance etc. in 35% H{sub 2}SO{sub 4} solution. The weld metal and base metal zones exhibited the highest and lowest values of hardness respectively. And, the corrosion resistance of the heat affected and weld metal zones was also increased than that of the base metal zone. Furthermore, it appeared that the corrosive products with red color and local corrosion like as a pitting corrosion were more frequently observed on the surface of the base metal zone compared to the heat affected and weld metal zones. Consequently, it is suggested that the mechanical and corrosion characteristics of the piston crown can be predominantly improved by repair welding method using the 1.25Cr-0.5Mo electrode.

  2. Theoretical study of flow ripple for an aviation axial-piston pump with damping holes in the valve plate

    OpenAIRE

    Guan, Changbin; Jiao, Zongxia; He, Shouzhan

    2014-01-01

    Based on the structure of a certain type of aviation axial-piston pump’s valve plate which adopts a pre-pressurization fluid path (consisting a damping hole, a buffer chamber, and an orifice) to reduce flow ripple, a single-piston model of the aviation axial-piston pump is presented. This single-piston model comprehensively considers fluid compressibility, orifice restriction effect, fluid resistance in the capillary tube, and the leakage flow. Besides, the instantaneous discharge areas used ...

  3. A new methodology for predictive tool wear

    Science.gov (United States)

    Kim, Won-Sik

    An empirical approach to tool wear, which requires a series of machining tests for each combination of insert and work material, has been a standard practice for industries since early part of the twentieth century. With many varieties of inserts and work materials available for machining, the empirical approach is too experiment-intensive that the demand for the development of a model-based approach is increasing. With a model-based approach, the developed wear equation can be extended without additional machining experiments. The main idea is that the temperatures on the primary wear areas are increasing such that the physical properties of the tool material degrade substantially and consequently tool wear increases. Dissolution and abrasion are identified to be the main mechanisms for tool wear. Flank wear is predominantly a phenomenon of abrasion as evident by the presence of a scoring mark on the flank surface. Based on this statement, it is reasonable to expect that the flank-wear rate would increase with the content of hard inclusions. However, experimental flank wear results did not necessary correspond to the content of cementite phase present in the steels. Hence, other phenomena are believed to significantly affect wear behavior under certain conditions. When the cutting temperature in the flank interface is subjected to high enough temperatures, pearlitic structure austenizes. During the formation of a new austenitic phase, the existing carbon is dissolved into the ferrite matrix, which will reduce the abrasive action. To verify the austenitic transformation, turning tests were conducted with plain carbon steels. The machined surface areas are imaged using X-ray diffraction the Scanning Electron Microscope (SEM) and the Transmission Electron Microscope (TEM). On the other hand, crater wear occurs as a result of dissolution wear and abrasive wear. To verify the wear mechanisms of crater wear, various coating inserts as well as uncoated inserts were

  4. Wear mechanisms in ceramic hip implants.

    Science.gov (United States)

    Slonaker, Matthew; Goswami, Tarun

    2004-01-01

    The wear in hip implants is one of the main causes for premature hip replacements. The wear affects the potential life of the prosthesis and subsequent removals of in vivo implants. Therefore, the objective of this article is to review various joints that show lower wear rates and consequently higher life. Ceramics are used in hip implants and have been found to produce lower wear rates. This article discusses the advantages and disadvantages of ceramics compared to other implant materials. Different types of ceramics that are being used are reviewed in terms of the wear characteristics, debris released, and their size together with other biological factors. In general, the wear rates in ceramics were lower than that of metal-on-metal and metal-on-polyethylene combinations.

  5. Radiation tagging measures wear at speed

    International Nuclear Information System (INIS)

    Barrett, Jon.

    1994-01-01

    A new non-invasive technique for performing accelerated wear and corrosion analysis is particularly relevant to power transmission systems. Wear tests that would normally take days or weeks to complete can now be performed in hours. A tiny patch of the wearing component is made mildly radioactive and the drop in activity as material is worn away is monitored. Known as Thin Layer Activation (TLA), the technology was originally developed and pioneered in-house by the Atomic Energy Authority. Since then, the dominant partner has been the automotive sector where TLA has been used extensively for engine wear and lubrication performance analysis. However, TLA could be used in any wear or corrosion environment. Applications include wear analysis of machine tool cutting surfaces, pump impellers and brake linings to the corrosion monitoring of process plant and pipelines. (author)

  6. Free-piston engine-and-hydraulic pump for railway vehicles

    Directory of Open Access Journals (Sweden)

    A. F. Golovchuk

    2013-04-01

    Full Text Available Purpose. The development of the free-piston diesel engine-and-hydraulic pump for the continuously variable hydrostatical transmission of mobile power vehicles. Methodology. For a long time engine builders have been interesting in the problem of developing free piston engines, which have much bigger coefficient of efficiency (40…80%. Such engines don’t have the conversion of reciprocating motion for inner combustion engine piston into rotating motion of crankshaft, from which the engine torque is transferred to the power machine transmission. Free-piston engines of inner combustion don’t have the crank mechanism (CM that significantly reduces mechanical losses for friction. Such engines can be used as compressors. Free-piston engine compressor (FPEC – is a free-piston machine in which energy received from engine’s cylinder is being transferred direct to compressor’s pistons connected with operational pistons of engine without crank mechanism. Part of the pressed air is being consumed for engine cylinder drain and the other part is going to the consumer. Findings. The use of free-piston engines-and-hydraulic pumps as power-transmission plants of power vehicles (diesel locomotives, combine harvester, tractors, cars and other mobile and stationary power installations with the continuously variable transmissions allows cost effectiveness improvement and metal consumption reduction of these vehicles, since the cost effectiveness of FPE is higher by 25-30%, and the metal consumption is lower by 40-50%. Originality. One of the important advantages of the free-piston engines is their simplicity and engine balance. As a result of the crank mechanism absence their construction is much simplified and the vibrations, peculiar to the ordinary engines are eliminated. In such installation the engine pistons are directly connected through the rod to compressor pistons and therefore there are no losses in the bearing bushes. Practical value. The free-piston

  7. Determination of rail wear and short-time wear measurements of rails applying radioisotopes

    International Nuclear Information System (INIS)

    Grohmann, H.D.

    1981-01-01

    An energetic model has been developed for calculating rail wear. Short-time wear tests on rails after surface activation and following activity measurements showed a good agreement with the calculated values

  8. CFD Modeling of Free-Piston Stirling Engines

    Science.gov (United States)

    Ibrahim, Mounir B.; Zhang, Zhi-Guo; Tew, Roy C., Jr.; Gedeon, David; Simon, Terrence W.

    2001-01-01

    NASA Glenn Research Center (GRC) is funding Cleveland State University (CSU) to develop a reliable Computational Fluid Dynamics (CFD) code that can predict engine performance with the goal of significant improvements in accuracy when compared to one-dimensional (1-D) design code predictions. The funding also includes conducting code validation experiments at both the University of Minnesota (UMN) and CSU. In this paper a brief description of the work-in-progress is provided in the two areas (CFD and Experiments). Also, previous test results are compared with computational data obtained using (1) a 2-D CFD code obtained from Dr. Georg Scheuerer and further developed at CSU and (2) a multidimensional commercial code CFD-ACE+. The test data and computational results are for (1) a gas spring and (2) a single piston/cylinder with attached annular heat exchanger. The comparisons among the codes are discussed. The paper also discusses plans for conducting code validation experiments at CSU and UMN.

  9. Integrated two-cylinder liquid piston Stirling engine

    Science.gov (United States)

    Yang, Ning; Rickard, Robert; Pluckter, Kevin; Sulchek, Todd

    2014-10-01

    Heat engines utilizing the Stirling cycle may run on low temperature differentials with the capacity to function at high efficiency due to their near-reversible operation. However, current approaches to building Stirling engines are laborious and costly. Typically the components are assembled by hand and additional components require a corresponding increase in manufacturing complexity, akin to electronics before the integrated circuit. We present a simple and integrated approach to fabricating Stirling engines with precisely designed cylinders. We utilize computer aided design and one-step, planar machining to form all components of the engine. The engine utilizes liquid pistons and displacers to harness useful work from heat absorption and rejection. As a proof of principle of the integrated design, a two-cylinder engine is produced and characterized and liquid pumping is demonstrated.

  10. Integrated two-cylinder liquid piston Stirling engine

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ning; Rickard, Robert; Pluckter, Kevin; Sulchek, Todd, E-mail: todd.sulchek@me.gatech.edu [George W. Woodruff School of Mechanical Engineering and Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States)

    2014-10-06

    Heat engines utilizing the Stirling cycle may run on low temperature differentials with the capacity to function at high efficiency due to their near-reversible operation. However, current approaches to building Stirling engines are laborious and costly. Typically the components are assembled by hand and additional components require a corresponding increase in manufacturing complexity, akin to electronics before the integrated circuit. We present a simple and integrated approach to fabricating Stirling engines with precisely designed cylinders. We utilize computer aided design and one-step, planar machining to form all components of the engine. The engine utilizes liquid pistons and displacers to harness useful work from heat absorption and rejection. As a proof of principle of the integrated design, a two-cylinder engine is produced and characterized and liquid pumping is demonstrated.

  11. Heat transfer analysis of liquid piston compressor for hydrogen applications

    DEFF Research Database (Denmark)

    Kermani, Nasrin Arjomand; Rokni, Masoud

    2015-01-01

    A hydrogen compression technology using liquid as the compression piston is investigated from heat transfer point of view. A thermodynamic model, simulating a single compression stroke, is developed to investigate the heat transfer phenomena inside the compression chamber. The model is developed...... and through the walls, is investigated and compared with the adiabatic case. The results show that depending on heat transfer correlation, the hydrogen temperature reduces slightly between 0.2% and 0.4% compared to the adiabatic case, at 500bar, due to the large wall resistance and small contact area...... at the interface. Moreover, the results of the sensitivity analysis illustrates that increasing the total heat transfer coefficients at the interface and the wall, together with compression time, play key roles in reducing the hydrogen temperature. Increasing the total heat transfer coefficient at the interface...

  12. Free-piston Stirling component test power converter

    Science.gov (United States)

    Dochat, George; Dhar, Manmohan

    1991-01-01

    The National Aeronautics and Space Administration (NASA) has been evaluating free-piston Stirling power converters (FPSPCs) for use on a wide variety of space missions. They provide high reliability, long life, and efficient operation and can be coupled with all potential heat sources, various heat input and heat rejection systems, and various power management and distribution systems. FPSPCs can compete favorably with alternative power conversion systems over a range of hundreds of watts to megawatts. Mechanical Technology Incorporated (MTI) is developing FPSPC technology under contract to NASA Lewis Research Center and will demonstrate this technology in two full-scale power converters operating at space temperature conditions. The testing of the first of these, the component test power converter (CTPC), was initiated in Spring 1991 to evaluate mechanical operation at space operating temperatures. The CTPC design, hardware fabrication, and initial test results are reviewed.

  13. Preliminary Study of a Piston Pump for Cryogenic Fluids

    Science.gov (United States)

    Biermann, Arnold E.; Kohl, Robert C.

    1959-01-01

    Preliminary data are presented covering the performance of a low-speed, five-cylinder piston pump designed for handling boiling hydrogen. This pump was designed for a flow of 55 gallons per minute at 240 rpm with a discharge pressure of 135 pounds per square inch. Tests were made using JP-4 fuel, liquid nitrogen, and liquid hydrogen. Pump delivery and endurance characteristics were satisfactory for the range of operation covered. In connection with the foregoing pump development, the cavitation characteristics of a preliminary visual model, glass-cylinder pump and of a simple reciprocating disk were studied. Subcooling of approximately 0.60 F was obtained from the cavitation produced by reciprocating a disk in boiling nitrogen and in boiling water. The subcooling obtained in a similar manner with liquid hydrogen was somewhat less.

  14. Integrated two-cylinder liquid piston Stirling engine

    International Nuclear Information System (INIS)

    Yang, Ning; Rickard, Robert; Pluckter, Kevin; Sulchek, Todd

    2014-01-01

    Heat engines utilizing the Stirling cycle may run on low temperature differentials with the capacity to function at high efficiency due to their near-reversible operation. However, current approaches to building Stirling engines are laborious and costly. Typically the components are assembled by hand and additional components require a corresponding increase in manufacturing complexity, akin to electronics before the integrated circuit. We present a simple and integrated approach to fabricating Stirling engines with precisely designed cylinders. We utilize computer aided design and one-step, planar machining to form all components of the engine. The engine utilizes liquid pistons and displacers to harness useful work from heat absorption and rejection. As a proof of principle of the integrated design, a two-cylinder engine is produced and characterized and liquid pumping is demonstrated.

  15. Process gas generator feeding internal combustion piston engines

    Energy Technology Data Exchange (ETDEWEB)

    Iwantscheff, G; Kostka, H; Henkel, H J

    1978-10-26

    The invention relates to a process gas generator feeding gaseous fuel to internal combustion piston engines. The cylinder linings of the internal combustion engine are enclosed by the catalytic reaction chamber of the process gas generator which contains perforated sintered nozzle bricks as carriers of the catalysts needed for the conversion. The reaction chamber is surrounded by the exhaust gas chamber around which a tube coil is ound which feeds the fuel charge to the reaction chamber after evaporation and mixing with exhaust gas and air. The fuel which may be used for this purpose, e.g., is low-octane gasoline or diesel fuel. In the reaction chamber the fuel is catalytically converted at temperatures above 200/sup 0/C, e.g., into low-molecular paraffins, carbon monoxide and hydrogen. Operation of the internal combustion engine with a process gas generator greatly reduces the pollutant content of the exhaust gases.

  16. Friction & Wear Under Very High Electromagnetic Stress

    National Research Council Canada - National Science Library

    Cowan, Richard S; Danyluk, Steven; Moon, Francis; Ford, J. C; Brenner, Donald W

    2004-01-01

    This document summarizes initial progress toward advancing the fundamental understanding of the friction, wear and mechanics of interfaces subjected to extreme electromagnetic stress, high relative...

  17. Daily Water Requirements when Wearing Body Armor

    National Research Council Canada - National Science Library

    Montain, Scott

    2000-01-01

    .... This report presents the results of model simulations predicting the individual daily water requirements under a broad range of energy expenditures and weather conditions when wearing battle dress...

  18. 5-kWe Free-piston Stirling Engine Convertor

    Science.gov (United States)

    Chapman, Peter A.; Vitale, Nicholas A.; Walter, Thomas J.

    2008-01-01

    The high reliability, long life, and efficient operation of Free-Piston Stirling Engines (FPSEs) make them an attractive power system to meet future space power requirements with less mass, better efficiency, and less total heat exchanger area than other power convertor options. FPSEs are also flexible in configuration as they can be coupled with many potential heat sources and various heat input systems, heat rejection systems, and power management and distribution systems. Development of a 5-kWe Stirling Convertor Assembly (SCA) is underway to demonstrate the viability of an FPSE for space power. The design is a scaled-down version of the successful 12.5-kWe Component Test Power Converter (CTPC) developed under NAS3-25463. The ultimate efficiency target is 25% overall convertor efficiency (electrical power out over heat in). For the single cylinder prototype now in development, cost and time constraints required use of economical and readily available materials (steel versus beryllium) and components (a commercially available linear alternator) and thus lower efficiency. The working gas is helium at 150 bar mean pressure. The design consists of a displacer suspended on internally pumped gas bearings and a power piston/alternator supported on flexures. Non-contacting clearance seals are used between internal volumes. Heat to and from the prototype convertor is done via pumped liquid loops passing through shell and tube heat exchangers. The preliminary and detail designs of the convertor, controller, and support systems (heating loop, cooling loop, and helium supply system) are complete and all hardware is on order. Assembly and test of the prototype at Foster- Miller is planned for early 2008, when work will focus on characterizing convertor dynamics and steady-state operation to determine maximum power output and system efficiency. The device will then be delivered to Auburn University where assessments will include start-up and shutdown characterization and

  19. CFD analysis of a diaphragm free-piston Stirling cryocooler

    Science.gov (United States)

    Caughley, Alan; Sellier, Mathieu; Gschwendtner, Michael; Tucker, Alan

    2016-10-01

    This paper presents a Computational Fluid Dynamics (CFD) analysis of a novel free-piston Stirling cryocooler that uses a pair of metal diaphragms to seal and suspend the displacer. The diaphragms allow the displacer to move without rubbing or moving seals. When coupled to a metal diaphragm pressure wave generator, the system produces a complete Stirling cryocooler with no rubbing parts in the working gas space. Initial modelling of this concept using the Sage modelling tool indicated the potential for a useful cryocooler. A proof-of-concept prototype was constructed and achieved cryogenic temperatures. A second prototype was designed and constructed using the experience gained from the first. The prototype produced 29 W of cooling at 77 K and reached a no-load temperature of 56 K. The diaphragm's large diameter and short stroke produces a significant radial component to the oscillating flow fields inside the cryocooler which were not modelled in the one-dimensional analysis tool Sage that was used to design the prototypes. Compared with standard pistons, the diaphragm geometry increases the gas-to-wall heat transfer due to the higher velocities and smaller hydraulic diameters. A Computational Fluid Dynamics (CFD) model of the cryocooler was constructed to understand the underlying fluid-dynamics and heat transfer mechanisms with the aim of further improving performance. The CFD modelling of the heat transfer in the radial flow fields created by the diaphragms shows the possibility of utilizing the flat geometry for heat transfer, reducing the need for, and the size of, expensive heat exchangers. This paper presents details of a CFD analysis used to model the flow and gas-to-wall heat transfer inside the second prototype cryocooler, including experimental validation of the CFD to produce a robust analysis.

  20. Accomplishments in free-piston stirling tests at NASA GRC

    Science.gov (United States)

    Schreiber, Jeffrey G.; Skupinski, Robert C.

    2002-01-01

    A power system based on the Stirling Radioisotope Generator (SRG) has been identified for potential use on deep space missions, as well as for Mars rovers that may benefit from extended operation. The Department of Energy (DOE) has responsibility for developing the generator and the NASA Glenn Research Center (GRC) is supporting DOE in this effort. The generator is based on a free-piston Stirling power convertor that has been developed by the Stirling Technology Company (STC) under contract to DOE. The generator would be used as a high-efficiency alternative to the Radioisotope Thermoelectric Generators (RTGs) that have been used on many previous missions. The increased efficiency leads to a factor of 3 to 4 reduction in the inventory of plutonium required to heat the generator. GRC has been involved in the development of Stirling power conversion technology for over 25 years. The support provided to this project by GRC has many facets and draws upon the lab's scientists and engineers that have gained experience in applying their skills to the previous Stirling projects. This has created a staff with an understanding of the subtleties involved in applying their expertise to Stirling systems. Areas include materials, structures, tribology, controls, electromagnetic interference, permanent magnets, alternator analysis, structural dynamics, and cycle performance. One of the key areas of support to the project is in the performance testing of the free-piston Stirling convertors. Since these power convertors are the smallest, lowest power Stirling machines that have been tested at GRC, a new laboratory was equipped for this project. Procedures and test plans have been created, instrumentation and data systems developed, and Stirling convertors have been tested. This paper will describe the GRC test facility, the test procedures that are used, present some of the test results and outline plans for the future. .

  1. Layered clustering multi-fault diagnosis for hydraulic piston pump

    Science.gov (United States)

    Du, Jun; Wang, Shaoping; Zhang, Haiyan

    2013-04-01

    Efficient diagnosis is very important for improving reliability and performance of aircraft hydraulic piston pump, and it is one of the key technologies in prognostic and health management system. In practice, due to harsh working environment and heavy working loads, multiple faults of an aircraft hydraulic pump may occur simultaneously after long time operations. However, most existing diagnosis methods can only distinguish pump faults that occur individually. Therefore, new method needs to be developed to realize effective diagnosis of simultaneous multiple faults on aircraft hydraulic pump. In this paper, a new method based on the layered clustering algorithm is proposed to diagnose multiple faults of an aircraft hydraulic pump that occur simultaneously. The intensive failure mechanism analyses of the five main types of faults are carried out, and based on these analyses the optimal combination and layout of diagnostic sensors is attained. The three layered diagnosis reasoning engine is designed according to the faults' risk priority number and the characteristics of different fault feature extraction methods. The most serious failures are first distinguished with the individual signal processing. To the desultory faults, i.e., swash plate eccentricity and incremental clearance increases between piston and slipper, the clustering diagnosis algorithm based on the statistical average relative power difference (ARPD) is proposed. By effectively enhancing the fault features of these two faults, the ARPDs calculated from vibration signals are employed to complete the hypothesis testing. The ARPDs of the different faults follow different probability distributions. Compared with the classical fast Fourier transform-based spectrum diagnosis method, the experimental results demonstrate that the proposed algorithm can diagnose the multiple faults, which occur synchronously, with higher precision and reliability.

  2. Using IR Imaging of Water Surfaces for Estimating Piston Velocities

    Science.gov (United States)

    Gålfalk, M.; Bastviken, D.; Arneborg, L.

    2013-12-01

    The transport of gasses dissolved in surface waters across the water-atmosphere interface is controlled by the piston velocity (k). This coefficient has large implications for, e.g., greenhouse gas fluxes but is challenging to quantify in situ. At present, empirical k-wind speed relationships from a small number of studies and systems are often extrapolated without knowledge of model performance. It is therefore of interest to search for new methods for estimating k, and to compare the pros and cons of existing and new methods. Wind speeds in such models are often measured at a height of 10 meters. In smaller bodies of water such as lakes, wind speeds can vary dramatically across the surface through varying degrees of wind shadow from e.g. trees at the shoreline. More local measurements of the water surface, through wave heights or surface motion mapping, could give improved k-estimates over a surface, also taking into account wind fetch. At thermal infrared (IR) wavelengths water has very low reflectivity (depending on viewing angle) than can go below 1%, meaning that more than 99% is heat radiation giving a direct measurement of surface temperature variations. Using an IR camera at about 100 frames/s one could map surface temperature structures at a fraction of a mm depth even with waves present. In this presentation I will focus on IR imaging as a possible tool for estimating piston velocities. Results will be presented from IR field measurements, relating the motions of surface temperature structures to k calculated from other simultaneous measurements (flux chamber and ADV-Based Dissipation Rate), but also attempting to calculate k directly from the IR surface divergence. A relation between wave height and k will also be presented.

  3. A method for simultaneous determination of wear-resistance of structurally identical machine parts with mutual friction

    International Nuclear Information System (INIS)

    Valigura, V.; Volyn'ski, A.

    1979-01-01

    There are mechanisms in the technique, boundary state of separate parts of which is determined by the process of wear of three elements of the mechanism, made of the same material (for example antifriction bearings). The main concept of wear determination in the case of such a mechanism is to conduct measurements by means of simultaneous application of three different methods, for example: the method of roentgen-fluorescence; the tracer technique with application of activation by means of irradiation by different elementary particles, practically by means of neutrons and protons; the method of artifical bases application. In the paper the method is presented having been developed in the Institute of Working Machines of the Poznan Polytechnic. This method of simultaneous investigation in the wear process of bearing rings, inner and outer, and rolling elements of roller bearings. All these elements of bearings are made of LX-15 steel. The method developed, permits to determine the wear sufficient for practical purposes sensitivity [ru

  4. Elevated temperature wear of Al6061 and Al6061-20%Al{sub 2}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Singh, J.; Alpas, A.T. [Univ. of Windsor, Ontario (Canada)

    1995-04-01

    Both current and potential applications of particulate reinforced aluminum alloys involve components which are required to operate under sliding contact conditions at elevated temperatures. Examples include brake rotors, piston and cylinder liners in automotive engines where operating temperatures can reach 0.5--0.8 of the melting temperature of the matrix alloy. For this reason, study of the high temperature wear resistance of aluminum alloys reinforced by Al{sub 2}O{sub 3} or SiC particles is important. These studies are also of interest for the problem of die wear during hot extrusion of aluminum matrix composites and to rationalize the process of frictional welding involved in joining of the composites. Although the room temperature tribological and mechanical behaviors of aluminum matrix composites have received considerable attention, their high temperature properties have only recently started being considered. It has been shown that Al-Si-Mg (A356) alloys with or without SiC particles show a transition from mild to severe wear when a critical temperature (at about 0.4 T{sub m}, where T{sub m} is the melting temperature of aluminum) is reached as a result of frictional heating under dry sliding conditions. In this work, high temperature wear of A16061 and A16061-20%Al{sub 2}O{sub 3} was studied at temperatures between 25--500 C. The microstructural changes that occurred during wear have been delineated in order to understand the wear mechanisms that operate at high temperatures.

  5. Thermoacoustic model of a modified free piston Stirling engine with a thermal buffer tube

    International Nuclear Information System (INIS)

    Yang, Qin; Luo, Ercang; Dai, Wei; Yu, Guoyao

    2012-01-01

    This article presents a modified free-piston Stirling heat engine configuration in which a thermal buffer tube is added to sandwich between the hot and cold heat exchangers. Such a modified configuration may lead to an easier fabrication and lighter weight of a free piston. To analyze the thermodynamic performance of the modified free piston Stirling heat engine, thermoacoustic theory is used. In the thermoacoustic modelling, the regenerator, the free piston, and the thermal buffer tube are given at first. Then, based on linear thermoacoustic network theory, the thermal and thermodynamic networks are presented to characterize acoustic pressure and volume flow rate distributions at different interfaces, and the global performance such as the power output, the heat input and the thermal efficiency. A free piston Stirling heat engine with several hundreds of watts mechanical power output is selected as an example. The typical operating and structure parameters are as follows: frequency around 50 Hz, mean pressure around 3.0 MPa, and a diameter of free piston around 50 mm. From the analysis, it was found that the modified free-piston Stirling heat engine has almost the same thermodynamic performance as the original design, which indicates that the modified configuration is worthy to develop in future because of its mechanical simplicity and reliability.

  6. Open Loop Heat Pipe Radiator Having a Free-Piston for Wiping Condensed Working Fluid

    Science.gov (United States)

    Weinstein, Leonard M. (Inventor)

    2015-01-01

    An open loop heat pipe radiator comprises a radiator tube and a free-piston. The radiator tube has a first end, a second end, and a tube wall, and the tube wall has an inner surface and an outer surface. The free-piston is enclosed within the radiator tube and is capable of movement within the radiator tube between the first and second ends. The free-piston defines a first space between the free-piston, the first end, and the tube wall, and further defines a second space between the free-piston, the second end, and the tube wall. A gaseous-state working fluid, which was evaporated to remove waste heat, alternately enters the first and second spaces, and the free-piston wipes condensed working fluid from the inner surface of the tube wall as the free-piston alternately moves between the first and second ends. The condensed working fluid is then pumped back to the heat source.

  7. Heavy duty composite piston for Euro 6 and beyond; Verschraubte Nutzfahrzeugkolben fuer die Euro-6-Norm und folgende

    Energy Technology Data Exchange (ETDEWEB)

    Scharp, Rainer [Mahle GmbH, Stuttgart (Germany). Konstruktion Stahlkolben Europa Produktlinie Kolbensysteme

    2009-02-15

    Composite pistons have been the state of the art in large bore engines - such as large marine engines - since the 1960s. The thermal and mechanical load of these engines is typically higher than the load of truck engines. Additionally composite pistons are being used for large bore engines because of their durability and reliability. Based on the experience with composite pistons for large bore engines, Mahle was able to transfer this reliable bolting technology to steel pistons for commercial vehicles, the 'MonoXcomp' piston. (orig.)

  8. Performance analysis of a miniature free piston expander for waste heat energy harvesting

    International Nuclear Information System (INIS)

    Champagne, C.; Weiss, L.

    2013-01-01

    Highlights: • A novel free piston expander is experimentally analyzed for waste heat retrieval. • A variety of variables are analyzed using three separate experiments. • Lubrication of device is optimized with lower viscosity lubricants. • Circular cross sectional pistons show increased repeatability and sealing. - Abstract: Initial experimental analysis of a small-scale Free Piston Expander (FPE) is presented. In final form, the FPE will be a MEMS-based device capable of operation from low temperature waste heat sources. Currently, a millimeter scale device is constructed and tested to yield insight into critical operational parameters for use in later design and testing. Operating conditions are examined to increase operational performance. Piston stroke length and repeatability are considered. Optimized variables include piston length and mass, FPE shape and size, input pressure, and lubrication. Construction of this testbed device is via concentric copper tubing, allowing an effective baseline study of these determining parameters. Results show that, while thick lubricants seal well in static configurations, piston motion is decreased in dynamic testing, indicating leakage. By contrast, reduced viscosity lubricants prove ineffective as sealing agents during static conditions, however, yield increased piston motion in dynamic testing with little leakage around critical piston sealing surfaces. The trends established by the study of varying viscosity lubricants hold true for pistons of increasing mass and length as well. A mixture of isopropanol and water performed well in these tests, and represented a low viscosity sealing fluid, which was used in later repeatability tests. Repeatability tests were performed in a closed dynamic environment on FPE designs with multiple cross sectional shapes and areas. Results from these tests show that circular FPE’s are more precise than square FPE’s. The final closed system tests yield a pressure–volume curve

  9. Contact damage failure analyses of fretting wear behavior of the metal stem titanium alloy-bone cement interface.

    Science.gov (United States)

    Zhang, Lanfeng; Ge, Shirong; Liu, Hongtao; Wang, Qingliang; Wang, Liping; Xian, Cory J

    2015-11-01

    Although cemented titanium alloy is not favored currently in the Western world for its poor clinical and radiography outcomes, its lower modulus of elasticity and good biocompatibility are instrumental for its ability supporting and transforming physical load, and it is more suitable for usage in Chinese and Japanese populations due to their lower body weights and unique femoral characteristics. Through various friction tests of different cycles, loads and conditions and by examining fretting hysteresis loops, fatigue process curves and wear surfaces, the current study investigated fretting wear characteristics and wear mechanism of titanium alloy stem-bone cement interface. It was found that the combination of loads and displacement affected the wear quantity. Friction coefficient, which was in an inverse relationship to load under the same amplitude, was proportional to amplitudes under the same load. Additionally, calf serum was found to both lubricate and erode the wear interface. Moreover, cement fatigue contact areas appeared black/oxidative in dry and gruel in 25% calf serum. Fatigue scratches were detected within contact areas, and wear scars were found on cement and titanium surfaces, which were concave-shaped and ring concave/ convex-shaped, respectively. The coupling of thermoplastic effect and minimal torque damage has been proposed to be the major reason of contact damage. These data will be important for further studies analyzing metal-cement interface failure performance and solving interface friction and wear debris production issues. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Vibration isolation in a free-piston driven expansion tube facility

    Science.gov (United States)

    Gildfind, D. E.; Jacobs, P. A.; Morgan, R. G.

    2013-09-01

    The stress waves produced by rapid piston deceleration are a fundamental feature of free-piston driven expansion tubes, and wave propagation has to be considered in the design process. For lower enthalpy test conditions, these waves can traverse the tube ahead of critical flow processes, severely interfering with static pressure measurements of the passing flow. This paper details a new device which decouples the driven tube from the free-piston driver, and thus prevents transmission of stress waves. Following successful incorporation of the concept in the smaller X2 facility, it has now been applied to the larger X3 facility, and results for both facilities are presented.

  11. Directionality of sperm whale sonar clicks and its relation to piston radiation theory

    DEFF Research Database (Denmark)

    Beedholm, K.; Møhl, Bertel

    2006-01-01

    This paper investigates the applicability to sperm whales of the theory of sound radiating from a piston. The theory is applied to a physical model and to a series of sperm whale clicks. Results show that wave forms of off-axis signals can be reproduced by convolving an on-axis signal...... with the spatial impulse response of a piston. The angle of a recorded click can be estimated as the angle producing the spatial impulse response that gives the best match with the observation when convolved with the on-axis wave form. It is concluded that piston theory applies to sperm whale sonar click emission....

  12. Analysis and control of a hybrid vehicle powered by free-piston energy converter

    OpenAIRE

    Hansson, Jörgen

    2006-01-01

    The introduction of hybrid powertrains has made it possible to utilise unconventional engines as primary power units in vehicles. The free-piston energy converter (FPEC) is such an engine. It is a combination of a free-piston combustion engine and a linear electrical machine. The main features of this configuration are high efficiency and a rapid transient response. In this thesis the free-piston energy converter as part of a hybrid powertrain is studied. One issue of the FPEC is the generati...

  13. Theoretical study of flow ripple for an aviation axial-piston pump with damping holes in the valve plate

    Directory of Open Access Journals (Sweden)

    Guan Changbin

    2014-02-01

    Full Text Available Based on the structure of a certain type of aviation axial-piston pump’s valve plate which adopts a pre-pressurization fluid path (consisting a damping hole, a buffer chamber, and an orifice to reduce flow ripple, a single-piston model of the aviation axial-piston pump is presented. This single-piston model comprehensively considers fluid compressibility, orifice restriction effect, fluid resistance in the capillary tube, and the leakage flow. Besides, the instantaneous discharge areas used in the single-piston model have been calculated in detail. Based on the single-piston model, a multi-piston pump model has been established according to the simple hydraulic circuit. The single- and multi-piston pump models have been realized by the S-function in Matlab/Simulink. The developed multi-piston pump model has been validated by being compared with the numerical result by computational fluid dynamic (CFD. The effects of the pre-pressurization fluid path on the flow ripple and the instantaneous pressure in the piston chamber have been studied and optimized design recommendations for the aviation axial-piston pump have been given out.

  14. A study on the pressure ripple characteristics in a bent-axis type oil hydraulic piston pump

    International Nuclear Information System (INIS)

    Cho, Ihn Sung; Jung, Jae Youn

    2013-01-01

    To improve the performance of a bent-axis type axial piston pump driven by tapered pistons, it is necessary to know the pressure ripple characteristics. The purpose of this paper is to understand the effect on the pressure ripple characteristics, and to predict by comparing experimental and theoretical analysis results. The simulation model of a bent-axis type axial piston pump is developed in the AMESim environment using the geometrical dimension, and the driving mechanism of the piston pump, such as the stroke of pump, the velocity of piston, the instantaneous volumetric flow, the overlap area of valve plate opening to cylinder bore, the angle of notch, and so on. The results show that theoretical analysis results of the bent-axis type axial piston pump by using the AMESim approximate the pressure ripple characteristic of the test pump, and through this, simulations can be obtained that predict the performance characteristics of a bentaxis type axial piston pump.

  15. Token Ring Project

    Directory of Open Access Journals (Sweden)

    Adela Ionescu

    2007-01-01

    Full Text Available Ring topology is a simple configuration used to connect processes that communicate among themselves. A number of network standards such as token ring, token bus, and FDDI are based on the ring connectivity. This article will develop an implementation of a ring of processes that communicate among themselves via pipe links. The processes are nodes in the ring. Each process reads from its standard input and writes in its standard output. N-1 process redirects the its standard output to a standard input of the process through a pipe. When the ring-structure is designed, the project can be extended to simulate networks or to implement algorithms for mutual exclusion

  16. Resource-saving technology for manufacturing billets for piston’s rings

    Directory of Open Access Journals (Sweden)

    A. N. Krutilin

    2010-10-01

    Full Text Available Piston’s rings are one of the most critical parts of heavy-duty engines for wear-work in conditions of prolonged exposure of alternating loads and high temperatures. Currently in the world production of billets for piston’s rings is dominated by the two methods of casting: production of individual and oiling billets of gray and ductile cast iron in green-sand mold and shell mold and centrifugal casting method (intended primarily for oiling billets of ductile iron; the technology for individual production billets for piston’s rings with a diameter up to 250 mm, from 250 to 450 mm with individual and oiling ways, over 450 mm - preference of oiling billet. The best parameters of physical-mechanical and operational characteristics piston’s rings are in the case of manufacture of billets to the maximum extent approaching the configuration to the finished product. The rings made of shaped billets are characterized by uniform distribution of properties from the perimeter, provide a given diagram of pressures and full fit to the cylinder. Because of deficiencies of traditional methods of casting, continuous quality requirements for billets, the need for economy of material, fuel and energy resources, are finding new progressive technological processes of production of high-quality billets for piston’s rings. One of the most promising for piston rings billet is a method of casting consists of immersing the sand molds into the melt. It is interesting idea, expressed by A. Sutherland and subsequently patented in several countries in the way of casting method, called "immersion pouring technology" (ICT-Immersion Casting Technique [1]. Experiments, conducted in the laboratory of the Belarusian National Technical University, have identified significant shortcomings of immersion method of casting. When forms are immersing, have an intensive gassing in molten metal, and freezing of the metal on the out surface of the form. But despite some

  17. Truck tyre wear assessment and prediction

    NARCIS (Netherlands)

    Lupker, H.A.; Montanaro, F.; Donadio, D.; Gelosa, E.; Vis, M.A.

    2002-01-01

    Tyre wear is a complex phenomenon. It depends non-linearly on numerous parameters, like tyre compound and design, vehicle type and usage, road conditions and road surface characteristics, environmental conditions (e.g., temperature) and many others. Yet, tyre wear has many economic and ecological

  18. Prediction of wear rates in comminution equipment

    DEFF Research Database (Denmark)

    Jensen, Lucas Roald Dörig; Fundal, Erling; Møller, Per

    2010-01-01

    -resistant high chromium white cast iron (21988/JN/HBW555XCr21), a heat-treated wear resistant steel (Hardox 400) and a plain carbon construction steel (S235). Quartz, which accounts for the largest wear loss in the cement industry, was chosen as abrasive. Other process parameters such as velocity (1–7 m...

  19. Straylight Measurements in Contact Lens Wear

    NARCIS (Netherlands)

    van der Meulen, Ivanka J. E.; Engelbrecht, Leonore A.; van Vliet, Johannes M. J.; Lapid-Gortzak, Ruth; Nieuwendaal, Carla P.; Mourits, Maarten P.; Schlingemann, Reinier O.; van den Berg, Thomas J. T. P.

    2010-01-01

    Purpose: (1) To quantify the effect of contact lens wear on straylight in rigid and soft contact lens wearers and (2) to relate findings to morphological changes and subjective complaints. Methods: Straylight was measured using the Oculus C-Quant during contact lens wear and after contact lens

  20. Tooth Wear Inclination in Great Ape Molars.

    Science.gov (United States)

    Knight-Sadler, Jordan; Fiorenza, Luca

    2017-01-01

    Primate dietary diversity is reflected in their dental morphology, with differences in size and shape of teeth. In particular, the tooth wear angle can provide insight into a species' ability to break down certain foods. To examine dietary and masticatory information, digitized polygon models of dental casts provide a basis for quantitative analysis of wear associated with tooth attrition. In this study, we analyze and compare the wear patterns of Pongo pygmaeus, Gorilla gorillagorilla and Pan troglodytes schweinfurthii lower molars, focusing on the degree of inclination of specific wear facets. The variation in wear angles appears to be indicative of jaw movements and the specific stresses imposed on food during mastication, reflecting thus the ecology of these species. Orangutans exhibit flatter wear angles, more typical of a diet consisting of hard and brittle foods, while gorillas show a wear pattern with a high degree of inclination, reflecting thus their more leafy diet. Chimpanzees, on the other hand, show intermediate inclinations, a pattern that could be related to their highly variable diet. This method is demonstrated to be a powerful tool for better understanding the relationship between food, mastication and tooth wear processes in living primates, and can be potentially used to reconstruct the diet of fossil species. © 2017 S. Karger AG, Basel.

  1. Numerical prediction of car tire wear

    NARCIS (Netherlands)

    Lupker, H.A.; Cheli, F.; Braghin, F.; Gelosa, E.; Keckman, A.

    2004-01-01

    Due to their many economic and ecological implications, the possibility to predict tire wear is of major importance to tire manufacturers, fleet owners and governments. Based on these observations, in 2000, a three-year project named TROWS (Tire and Road Wear and Slip assessment was started. One of

  2. Vibrational characteristics and wear of fuel rods

    International Nuclear Information System (INIS)

    Schmugar, K.L.

    1977-01-01

    Fuel rod wear, due to vibration, is a continuing concern in the design of liquid-cooled reactors. In my report, the methodology and models that are used to predict fuel rod vibrational response and vibratory wear, in a light water reactor environment, are discussed. This methodology is being followed at present in the design of Westinghouse Nuclear Fuel. Fuel rod vibrations are expressed as the normal bending modes, and sources of rod vibration are examined with special emphasis on flow-induced mechanisms in the stable flow region. In a typical Westinghouse PWR fuel assembly design, each fuel rod is supported at multiple locations along the rod axis by a square-shaped 'grid cell'. For a fuel rod /grid support system, the development of small oscillatory motions, due to fluid flow at the rod/grid interface, results in material wear. A theoretical wear mode is developed using the Archard Theory of Adhesive Wear as the basis. Without question certainty, fretting wear becomes a serious problem if it progresses to the stage where the fuel cladding is penetrated and fuel is exposed to the coolant. Westinghouse fuel is designed to minimize fretting wear by limiting the relative motion between the fuel rod and its supports. The wear producing motion between the fuel rod and its supports occurs when the vibration amplitude exceeds the slippage threshold amplitude

  3. Radioisotopic measurement methods for determining the wear railway brake shoe and its rim wearing effect

    International Nuclear Information System (INIS)

    Doman, P.

    1979-01-01

    Under operating conditions the wear of brake shoe was tested by a measuring method based on the principle of radioisotopic thickness measurement. It is characteristic to the sensitivity of the method that the wear caused by the fast braking of a train (speed: 100 km/h) as well as the uneven wear distribution were determinable. Surface activating methods assuring the periodic and continuous evaluation were also developed. A test was performed with galvanic surface activation under operating conditions to determine the rim wearing effect of the brake shoe. Apart from the operational tests a new method based on activated wear measurement was also developed. (author)

  4. Token ring technology report

    CERN Document Server

    2013-01-01

    Please note this is a Short Discount publication. This report provides an overview of the IBM Token-Ring technology and products built by IBM and compatible vendors. It consists of two sections: 1. A summary of the design trade-offs for the IBM Token-Ring. 2. A summary of the products of the major token-ring compatible vendors broken down by adapters and components, wiring systems, testing, and new chip technology.

  5. Radioactive gold ring dermatitis

    International Nuclear Information System (INIS)

    Miller, R.A.; Aldrich, J.E.

    1990-01-01

    A superficial squamous cell carcinoma developed in a woman who wore a radioactive gold ring for more than 30 years. Only part of the ring was radioactive. Radiation dose measurements indicated that the dose to basal skin layer was 2.4 Gy (240 rad) per week. If it is assumed that the woman continually wore her wedding ring for 37 years since purchase, she would have received a maximum dose of approximately 4600 Gy

  6. Residual Stresses and Sliding Wear.

    Science.gov (United States)

    1982-05-25

    case of rolling contact, taking into account strain hardening during plastic deformation. ..-s calculations (forSAE 52100 at a hardness level of 58.5 R...can reach -800- 1000 MPa. If 033 was comparable to these values, it would indeed effect the wear rate. It is evident that an experimental deter...cc o 40 1 °2 00 I I +A ) S l~lll0 44MUK I CQ E3 e0 El 0 Uc 00 E3 (3 80 j40 c (vclq) SSHHI +ce ce mCQ ce (2E e0 4El EJ) E - 0 El 0 E0 .. t El 0 (vdNp

  7. Friction and wear behaviour of ion beam modified ceramics

    International Nuclear Information System (INIS)

    Lankford, J.; Wei, W.; Kossowsky, R.

    1987-01-01

    In the present study, the sliding friction coefficients and wear rates of carbide, oxide, and nitride materials for potential use as sliding seals (ring/liner) were measured under temparature, environmental, velocity, and loading conditions representative of a diesel engine. In addition, silicon nitride and partially stabilized zirconia discs were modified by ion mixing with TiNi, nickel, cobalt and chromium, and subsequently run against carbide pins, with the objective of producing reduced friction via solid lubrication at elevated temperature. Unmodified ceramic sliding couples were characterized at all temperatures by friction coefficients of 0.24 and above. However, the coefficient at 800 0 C in an oxidizing environment was reduced to below 0.1, for certain material combinations, by the ion implantation of TiNi or cobalt. This beneficial effect was found to derive from lubricious titanium, nickel, and cobalt oxides. (author)

  8. Analysis and Modelling of Electrode Wear in Resistance Spot Welding

    DEFF Research Database (Denmark)

    Madsen, Anders; Pedersen, Kim; Friis, Kasper Storgaard

    2010-01-01

    A model describing electrode wear as a function of weld number, initial tip diameter, truncated cone angle, welding current and electrode force is proposed. Excellent agreement between the model and experimental results is achieved, showing that the model can describe the change in electrode tip...... diameter with increasing weld number at different weld settings. Furthermore a method for measuring the worn tip diameter in a fast and robust manner is developed. The method relies on a well-known technique for capturing the electrode tip area by the use of carbon imprints and a new developed image...... a central cavity is formed and one where smaller pits are formed randomly across the electrode face. The influence of these two types of surface pits on the nugget size are investigated using the FE code SORPAS, revealing ring welds and undersized weld nuggets....

  9. Friction and wear behaviour of ion beam modified ceramics

    Science.gov (United States)

    Lankford, J.; Wei, W.; Kossowsky, R.

    1987-01-01

    In the present study, the sliding friction coefficients and wear rates of carbide, oxide, and nitride materials for potential use as sliding seals (ring/liner) were measured under temperature, environmental, velocity, and loading conditions representative of a diesel engine. In addition, silicon nitride and partially stabilized zirconia discs were modified by ion mixing with TiNi, nickel, cobalt and chromium, and subsequently run against carbide pins, with the objective of producing reduced friction via solid lubrication at elevated temperature. Unmodified ceramic sliding couples were characterized at all temperatures by friction coefficients of 0.24 and above. However, the coefficient at 800 C in an oxidizing environment was reduced to below 0.1, for certain material combinations, by the ion implantation of TiNi or cobalt. This beneficial effect was found to derive from lubricious titanium, nickel, and cobalt oxides.

  10. Physics of quantum rings

    International Nuclear Information System (INIS)

    Fomin, Vladimir M.

    2014-01-01

    Presents the new class of materials of quantum rings. Provides an elemental basis for low-cost high-performance devices promising for electronics, optoelectronics, spintronics and quantum information processing. Explains the physical properties of quantum rings to cover a gap in scientific literature. Presents the application of most advanced nanoengineering and nanocharacterization techniques. This book deals with a new class of materials, quantum rings. Innovative recent advances in experimental and theoretical physics of quantum rings are based on the most advanced state-of-the-art fabrication and characterization techniques as well as theoretical methods. The experimental efforts allow to obtain a new class of semiconductor quantum rings formed by capping self-organized quantum dots grown by molecular beam epitaxy. Novel optical and magnetic properties of quantum rings are associated with non-trivial topologies at the nanoscale. An adequate characterization of quantum rings is possible on the basis of modern characterization methods of nanostructures, such as Scanning Tunneling Microscopy. A high level of complexity is demonstrated to be needed for a dedicated theoretical model to adequately represent the specific features of quantum rings. The findings presented in this book contribute to develop low-cost high-performance electronic, spintronic, optoelectronic and information processing devices based on quantum rings.

  11. Modeling wear of cast Ti alloys.

    Science.gov (United States)

    Chan, Kwai S; Koike, Marie; Okabe, Toru

    2007-05-01

    The wear behavior of Ti-based alloys was analyzed by considering the elastic-plastic fracture of individual alloys in response to the relevant contact stress field. Using the contact stresses as the process driving force, wear was computed as the wear rate or volume loss as a function of hardness and tensile ductility for Ti-based cast alloys containing an alpha, alpha+beta or beta microstructure with or without the intermetallic precipitates. Model predictions indicated that wear of Ti alloys increases with increasing hardness but with decreasing fracture toughness or tensile ductility. The theoretical results are compared with experimental data to elucidate the roles of microstructure in wear and contrasted against those in grindability.

  12. The friction wear of electrolytic composite coatings

    International Nuclear Information System (INIS)

    Starosta, R.

    2002-01-01

    The article presents the results of investigation of wear of galvanic composite coatings Ni-Al 2 O 3 and Ni-41%Fe-Al 2 O 3 . The diameter of small parts of aluminium oxide received 0.5; 3; 5 μm. Investigations of friction sliding were effected on PT3 device at Technical University of Gdansk. Counter sample constituted a funnel made of steel NC6 (750 HV). Increase of wear coatings together with the rise of iron content in matrix is observed. The rise of sizes of ceramic particles caused decrease of wear of composite coatings, but rise of steel funnel wear. The friction coefficient increased after ceramic particle s were built in coatings. The best wear resistance characterized Ni-41%Fe-Al 2 O 3 coatings containing 2.2x10 6 mm -2 ceramic particles. (author)

  13. Tool Wear Monitoring Using Time Series Analysis

    Science.gov (United States)

    Song, Dong Yeul; Ohara, Yasuhiro; Tamaki, Haruo; Suga, Masanobu

    A tool wear monitoring approach considering the nonlinear behavior of cutting mechanism caused by tool wear and/or localized chipping is proposed, and its effectiveness is verified through the cutting experiment and actual turning machining. Moreover, the variation in the surface roughness of the machined workpiece is also discussed using this approach. In this approach, the residual error between the actually measured vibration signal and the estimated signal obtained from the time series model corresponding to dynamic model of cutting is introduced as the feature of diagnosis. Consequently, it is found that the early tool wear state (i.e. flank wear under 40µm) can be monitored, and also the optimal tool exchange time and the tool wear state for actual turning machining can be judged by this change in the residual error. Moreover, the variation of surface roughness Pz in the range of 3 to 8µm can be estimated by the monitoring of the residual error.

  14. Biologically Based Restorative Management of Tooth Wear

    Directory of Open Access Journals (Sweden)

    Martin G. D. Kelleher

    2012-01-01

    Full Text Available The prevalence and severity of tooth wear is increasing in industrialised nations. Yet, there is no high-level evidence to support or refute any therapeutic intervention. In the absence of such evidence, many currently prevailing management strategies for tooth wear may be failing in their duty of care to first and foremost improve the oral health of patients with this disease. This paper promotes biologically sound approaches to the management of tooth wear on the basis of current best evidence of the aetiology and clinical features of this disease. The relative risks and benefits of the varying approaches to managing tooth wear are discussed with reference to long-term follow-up studies. Using reference to ethical standards such as “The Daughter Test”, this paper presents case reports of patients with moderate-to-severe levels of tooth wear managed in line with these biologically sound principles.

  15. Predicting railway wheel wear under uncertainty of wear coefficient, using universal kriging

    International Nuclear Information System (INIS)

    Cremona, Marzia A.; Liu, Binbin; Hu, Yang; Bruni, Stefano; Lewis, Roger

    2016-01-01

    Railway wheel wear prediction is essential for reliability and optimal maintenance strategies of railway systems. Indeed, an accurate wear prediction can have both economic and safety implications. In this paper we propose a novel methodology, based on Archard's equation and a local contact model, to forecast the volume of material worn and the corresponding wheel remaining useful life (RUL). A universal kriging estimate of the wear coefficient is embedded in our method. Exploiting the dependence of wear coefficient measurements with similar contact pressure and sliding speed, we construct a continuous wear coefficient map that proves to be more informative than the ones currently available in the literature. Moreover, this approach leads to an uncertainty analysis on the wear coefficient. As a consequence, we are able to construct wear prediction intervals that provide reasonable guidelines in practice. - Highlights: • Wear prediction is of outmost importance for reliability of railway systems. • Wear coefficient is essential in prediction through Archard's equation. • A novel methodology is developed to predict wear and RUL. • Universal kriging is used for wear coefficient and uncertainty estimation. • A simulation study and a real case application are provided.

  16. Dynamic SEM wear studies of tungsten carbide cermets. [friction and wear experiments

    Science.gov (United States)

    Brainard, W. A.; Buckley, D. H.

    1975-01-01

    Dynamic friction and wear experiments were conducted in a scanning electron microscope. The wear behavior of pure tungsten carbide and composite with 6 and 15 weight percent cobalt binder was examined, and etching of the binder was done to selectively determine the role of the binder in the wear process. Dynamic experiments were conducted as the tungsten carbide (WC) and bonded WC cermet surfaces were transversed by a 50 micron radiused diamond stylus. These studies show that the predominant wear process in WC is fracture initiated by plastic deformation, and the wear of the etched cermets is similar to pure WC. The presence of the cobalt binder reduces both friction and wear. The cementing action of the cobalt reduces granular separation, and promotes a dense polished layer because of its low shear strength film-forming properties. The wear debris generated from unetched surface is approximately the same composition as the bulk.

  17. Dental wear, wear rate, and dental disease in the African apes.

    Science.gov (United States)

    Elgart, Alison A

    2010-06-01

    The African apes possess thinner enamel than do other hominoids, and a certain amount of dentin exposure may be advantageous in the processing of tough diets eaten by Gorilla. Dental wear (attrition plus abrasion) that erodes the enamel exposes the underlying dentin and creates additional cutting edges at the dentin-enamel junction. Hypothetically, efficiency of food processing increases with junction formation until an optimal amount is reached, but excessive wear hinders efficient food processing and may lead to sickness, reduced fecundity, and death. Occlusal surfaces of molars and incisors in three populations each of Gorilla and Pan were videotaped and digitized. The quantity of incisal and molar occlusal dental wear and the lengths of dentin-enamel junctions were measured in 220 adult and 31 juvenile gorilla and chimpanzee skulls. Rates of dental wear were calculated in juveniles by scoring the degree of wear between adjacent molars M1 and M2. Differences were compared by principal (major) axis analysis. ANOVAs compared means of wear amounts. Pearson correlation coefficients were calculated to compare the relationship between molar wear and incidence of dental disease. Results indicate that quantities of wear are significantly greater in permanent incisors and molars and juvenile molars of gorillas compared to chimpanzees. The lengths of dentin-enamel junctions were predominantly suboptimal. Western lowland gorillas have the highest quantities of wear and the most molars with suboptimal wear. The highest rates of wear are seen in Pan paniscus and Pan t. troglodytes, and the lowest rates are found in P.t. schweinfurthii and G. g. graueri. Among gorillas, G. b. beringei have the highest rates but low amounts of wear. Coefficients between wear and dental disease were low, but significant when all teeth were combined. Gorilla teeth are durable, and wear does not lead to mechanical senescence in this sample.

  18. A study on the development of engineering plastic piston used in the shock absorber

    Science.gov (United States)

    Kim, Young-Ho; Bae, Won-Byong; Lim, Dong-Ju; Suh, Yun-Soo

    1998-08-01

    A piston is an important component of the shock absorber which determines comfortable riding and handling. Conventional piston is made of metal powder that is pressed in a mold, and then sintered at high temperatures below the melting point before machining processes such as drilling, sizing and teflon banding. This study aims at cutting down cost and weight, and improving the process by replacing the traditional sintering process used for manufacturing the shock absorber with the injection molding process adopting engineering plastics as raw material. To analyze the injection molding process, we used the commercial program, MOLDFLOW, and obtained an optimal combination of the process parameters. In addition, by comparing the engineering plastic piston with the metal powder piston through the formability and the performance experiments, we confirmed the availability of this alternative process suggested.

  19. Adaptive individual-cylinder thermal state control using piston cooling for a GDCI engine

    Science.gov (United States)

    Roth, Gregory T; Husted, Harry L; Sellnau, Mark C

    2015-04-07

    A system for a multi-cylinder compression ignition engine includes a plurality of nozzles, at least one nozzle per cylinder, with each nozzle configured to spray oil onto the bottom side of a piston of the engine to cool that piston. Independent control of the oil spray from the nozzles is provided on a cylinder-by-cylinder basis. A combustion parameter is determined for combustion in each cylinder of the engine, and control of the oil spray onto the piston in that cylinder is based on the value of the combustion parameter for combustion in that cylinder. A method for influencing combustion in a multi-cylinder engine, including determining a combustion parameter for combustion taking place in in a cylinder of the engine and controlling an oil spray targeted onto the bottom of a piston disposed in that cylinder is also presented.

  20. Design and theoretical analysis of a sliding valve distribution radial piston pump

    Energy Technology Data Exchange (ETDEWEB)

    Tong, Guo; Shengdun, Zhao; Yanghuiwen, Yu [Xian Jiaotong University, Xian (China); Peng, Shang [Xian Engineering University of Armed Police Force, Xian (China)

    2016-01-15

    A Sliding valve distribution radial piston pump (SVDRPP) is presented. In this pump, a new distribution method that uses sliding valves to distribute oil for the piston chambers is developed. With this design, the disadvantages brought by the distribution shaft and the check valves (traditional distribution mechanisms), such as the poor stress state of the shaft and the energy waste for opening the check valves, are expected to be eliminated. In addition, a method of using pressure oil to accomplish the returning stroke of the piston is also proposed, which could be used to replace the usage of springs along with their shortcomings. A pump with five pistons is designed as an example to elaborate the structure and the working principle of SVDRPP. Furthermore, the flow characteristics of SVDRPP are studied, and the formulas of the displacement, the average flow rate and the instantaneous flow rate are deduced.

  1. Method of estimating time scales of atmospheric piston and its application at Dome C (Antarctica)

    International Nuclear Information System (INIS)

    Kellerer, A.; Sarazin, M.; Butterley, T.; Wilson, R.

    2007-01-01

    Temporal fluctuations of the atmospheric piston are critical for interferometers as they determine their sensitivity. We characterize an instrumental setup,termed the piston scope, that aims at measuring the atmospheric time constant, τ0, through the image motion in the focal plane of a Fizeau interferometer.High-resolution piston scope measurements have been obtained at the observatory of Paranal, Chile in April 2006. The derived atmospheric parameters are shown to be consistent with data from the astronomical site monitor, provided that the atmospheric turbulence is displaced along a single direction.The piston scope measurements of lower temporal and spatial resolution were recorded for what is believed to be the first time in February 2005 at the Antarctic site of Dome C. Their reanalysis in terms of the new data calibration sharpens the conclusions of a first qualitative examination [Appl. Opt. 45, 5709 (2006)

  2. Free-Piston Diesel-Fueled Linear Alternator for Auxiliary Power Unit Applications

    National Research Council Canada - National Science Library

    Atkinson, Christopher

    1999-01-01

    .... Previous studies of free-piston engine designs have indicated that they would be useful where linear power delivery could be used, such as in fluid power delivery, or in electrical energy applications.

  3. A thermodynamic study for the optimization of stable operation of free piston Stirling engines

    Energy Technology Data Exchange (ETDEWEB)

    Rogdakis, E.D.; Bormpilas, N.A.; Koniakos, I.K. [National Technical Univerisity, Athens (Greece). Dept. of Mechanical Engineering

    2004-03-01

    One of the most novel applications of the Stirling cycle is in the free piston configuration that was initially designed by W. Beale. In free piston Stirling engines (FPSEs), there are no mechanical linkages coupling the pistons or displacers, the motions of the reciprocating components follow the working gas pressure variations. Fillipo de Monte and G. Benvenuto have recently proposed a linearization technique of the dynamic balance equations. The aim of this paper is to predict the thermodynamic conditions for stable operation of FPSEs and their modeling. The equations of the angular velocity are solved analytically in terms of the working gas mass and the displacer-piston phase angle of the machine. Using the criterion of stable engine cyclic steady operation, a mathematically rigorous form is obtained for the main parameters of the engine. Furthermore, for simplicity reasons, thermodynamic magnitudes are obtained using the Schmidt analysis (isothermal model). (author)

  4. A thermodynamic study for the optimization of stable operation of free piston Stirling engines

    International Nuclear Information System (INIS)

    Rogdakis, E.D.; Bormpilas, N.A.; Koniakos, I.K.

    2004-01-01

    One of the most novel applications of the Stirling cycle is in the free piston configuration that was initially designed by W. Beale. In free piston Stirling engines (FPSEs), there are no mechanical linkages coupling the pistons or displacers, the motions of the reciprocating components follow the working gas pressure variations. Fillipo de Monte and G. Benvenuto have recently proposed a linearization technique of the dynamic balance equations. The aim of this paper is to predict the thermodynamic conditions for stable operation of FPSEs and their modeling. The equations of the angular velocity are solved analytically in terms of the working gas mass and the displacer-piston phase angle of the machine. Using the criterion of stable engine cyclic steady operation, a mathematically rigorous form is obtained for the main parameters of the engine. Furthermore, for simplicity reasons, thermodynamic magnitudes are obtained using the Schmidt analysis (isothermal model)

  5. Performance simulation of a spark ignited free-piston engine generator

    Energy Technology Data Exchange (ETDEWEB)

    Mikalsen, R.; Roskilly, A.P. [Sir Joseph Swan Institute for Energy Research, University of Newcastle upon Tyne, Newcastle upon Tyne, NE1 7RU (United Kingdom)

    2008-10-15

    Free-piston engines are under investigation by a number of research groups worldwide due to potential fuel efficiency and engine emissions advantages. The free-piston engine generator, in which a linear electric generator is fixed to the mover to produce electric power, has been proposed as an alternative prime mover for hybrid-electric vehicles. This paper investigates the performance of a spark ignited free-piston engine generator and compares it to a conventional engine using a computational fluid dynamics simulation model. The particular operating characteristics of the free-piston engine were not found to give noticeable performance advantages, and it is concluded that the main potential of this technology lies in the simplicity and flexibility of the concept. (author)

  6. An experimental study for the phase shift between piston and displacer in the Stirling cryocooler

    Energy Technology Data Exchange (ETDEWEB)

    Park, S. J.; Hong, Y. J.; Kim, H. B. [Korea Institute of Machinery and Materials, Taejon (Korea, Republic of); Son, H. K.; Yu, B. K. [Wooyoung Co., Ltd., Seoul (Korea, Republic of)

    2002-07-01

    The small cryocooler is being widely applied to the areas of infrared detector, superconductor filter, satellite communication, and cryopump. The cryocooler working on the Stirling cycle are characterized by small size, lightweight, low power consumption and high reliability. For these reasons, FPFD (Free Piston Free Displacer) Stirling cryocooler is widely used not only tactical infrared imaging camera but also medical diagnostic apparatus. In this study, Stirling cryocooler actuated by the dual linear motor is designed and manufactured. And, displacement of the piston is measured by LVDTs (Linear Variable Differential Transformers), displacement of the displacer is measured by laser optic method, and phase shift between piston and displacer is discussed. Finally, when the phase shift between displacements of the piston and displacer is 45 .deg., operating frequency is optimum and is decided by resonant frequency of the expander, mass and cross section area of the displacer and constant by friction and flow resistance.

  7. An experimental study for the phase shift between piston and displacer in the Stirling cryocooler

    International Nuclear Information System (INIS)

    Park, S. J.; Hong, Y. J.; Kim, H. B.; Son, H. K.; Yu, B. K.

    2002-01-01

    The small cryocooler is being widely applied to the areas of infrared detector, superconductor filter, satellite communication, and cryopump. The cryocooler working on the Stirling cycle are characterized by small size, lightweight, low power consumption and high reliability. For these reasons, FPFD (Free Piston Free Displacer) Stirling cryocooler is widely used not only tactical infrared imaging camera but also medical diagnostic apparatus. In this study, Stirling cryocooler actuated by the dual linear motor is designed and manufactured. And, displacement of the piston is measured by LVDTs (Linear Variable Differential Transformers), displacement of the displacer is measured by laser optic method, and phase shift between piston and displacer is discussed. Finally, when the phase shift between displacements of the piston and displacer is 45 .deg., operating frequency is optimum and is decided by resonant frequency of the expander, mass and cross section area of the displacer and constant by friction and flow resistance

  8. Design and theoretical analysis of a sliding valve distribution radial piston pump

    International Nuclear Information System (INIS)

    Tong, Guo; Shengdun, Zhao; Yanghuiwen, Yu; Peng, Shang

    2016-01-01

    A Sliding valve distribution radial piston pump (SVDRPP) is presented. In this pump, a new distribution method that uses sliding valves to distribute oil for the piston chambers is developed. With this design, the disadvantages brought by the distribution shaft and the check valves (traditional distribution mechanisms), such as the poor stress state of the shaft and the energy waste for opening the check valves, are expected to be eliminated. In addition, a method of using pressure oil to accomplish the returning stroke of the piston is also proposed, which could be used to replace the usage of springs along with their shortcomings. A pump with five pistons is designed as an example to elaborate the structure and the working principle of SVDRPP. Furthermore, the flow characteristics of SVDRPP are studied, and the formulas of the displacement, the average flow rate and the instantaneous flow rate are deduced

  9. A Space Cam Mechanism for Power Transmission of an Opposite-cylinder Piston Engine

    Directory of Open Access Journals (Sweden)

    Zhang Haoyue

    2015-01-01

    Full Text Available For the purpose of improving the engine’s power density, we put forward a new type of power transmission mechanism which is used for opposed-cylinder engine. The gas pressure acts on the cam through the piston and push rod, and the spindle rotation of external is driven by the cam. The design of spatial cam work surface is completed by using the enveloping theory of a family of space curves, the force between roller and cam is analyzed using dynamic analysis software. Under the condition of equal number, size and stroke of piston, the new one with larger power density is more compact in structure than the traditional power transmission mechanism, and the reaction force on either side of the main shaft and the acting force between pistons and cylinders are smaller than those in traditional one, which prolongs the service life of the pistons.

  10. Application of ceramic short fiber reinforced Al alloy matrix composite on piston for internal combustion engines

    Directory of Open Access Journals (Sweden)

    Wu Shenqing

    2010-11-01

    Full Text Available The preparation and properties of ceramic short fiber reinforced Al-Si alloy matrix composite and it’s application on the piston for internal combustion engines are presented. Alumina or aluminosilicate fibers reinforced Al-Si alloy matrix composite has more excellent synthetical properties at elevated temperature than the matrix alloys. A partially reinforced Al-Si alloy matrix composite piston produced by squeeze casting technique has a firm interface between reinforced and unreinforced areas, low reject rate and good technical tolerance. As a new kind of piston material, it has been used for mass production of about 400,000 pieces of automobile engines piston. China has become one of a few countries in which aluminum alloy matrix composite materials have been used in automobile industry and attained industrialization.

  11. Improvement of the low-speed friction characteristics of a hydraulic piston pump by PVD-coating of TiN

    International Nuclear Information System (INIS)

    Hong, Yeh Sun; Lee, Sang Yul; Kim, Sung Hun; Lim, Hyun Sik

    2006-01-01

    The hydraulic pump of an Electro-hydrostatic Actuator should be able to quickly feed large volume of oil into hydraulic cylinder in order to reduce the response time. On the other hand, it should be also able to precisely dispense small amount of oil through low-speed operation so that the steady state position control error of the actuator can be accurately compensated. Within the scope of axial piston type hydraulic pumps, this paper is focused on the investigation how the surface treatment of their cylinder barrel with TiN plasma coating can contribute to the reduction of the friction and wear rate of valve plate in the low-speed range with mixed lubrication. The results showed that the friction torque of the valve plate mated with a TiN-coated cylinder barrel could be reduced to 22% of that with an uncoated original one when load pressure was 300 bar and rotational speed 100 rpm. It means that the torque efficiency of the test pump was expected to increase more than 1.3% under the same working condition. At the same time, the wear rate of the valve plate could be reduced to 40∼50%

  12. Behaviour Of A Piston Corer From Accelerometers And New Insights On Quality Of The Recovery

    OpenAIRE

    Bourillet, Jean-francois; Damy, Gilbert; Dussud, Loic; Sultan, Nabil; Woerther, Patrice; Migeon, Sebastien

    2007-01-01

    Various observations pointed out that cores performed with gravity piston corer show signifi cant distortions mainly located at the top of the core. A series of 15 cores were performed at the same location on a submarine sand wave (Var canyon, France). Six different settings of the corer – three freefall heights and three slacks of the piston cable – were tested, including duplicates. Two accelerometers recorded simultaneously the movements of the core tube and the movements of the triggering...

  13. Control scheme for power modulation of a free piston Stirling engine

    Science.gov (United States)

    Dhar, Manmohan

    1989-01-01

    The present invention relates to a control scheme for power modulation of a free-piston Stirling engine-linear alternator power generator system. The present invention includes connecting an autotransformer in series with a tuning capacitance between a linear alternator and a utility grid to maintain a constant displacement to piston stroke ratio and their relative phase angle over a wide range of operating conditions.

  14. Fundamental test results of a hydraulic free piston internal combustion engine

    Energy Technology Data Exchange (ETDEWEB)

    Hibi, A.; Ito, T. [Toyohashi University of Technology (Japan). Dept. of Mechanical Engineering

    2004-10-01

    The hydraulic free piston internal combustion engine pump that has been constructed and tested in this work is the opposed piston, two-stroke cycle, uniflow scavenging, direct fuel injection, and compression ignition type. The opposed engine pistons reciprocate the hydraulic pump pistons directly and the hydraulic power to be used in the hydraulic motors is generated. The hydraulic pressure generated is substantially constant. The opposed free pistons rest after every gas cycle and hydraulic power is continuously supplied by a hydraulic accumulator during the free pistons' rest. The smaller the hydraulic flow output, the longer the duration of the rest. Every gas cycle is performed under a fixed working condition independent of hydraulic power output. The test results in this work indicate that the number of gas cycles per second of the free piston engine pump is directly proportional to hydraulic flow output. The opposed free pistons operate every 53.2 s when hydraulic flow output is 1.02 cm{sup 3}/s; at that time hydraulic power output is 0.0124 kW. Hydraulic thermal efficiency, the ratio of hydraulic energy produced to fuel energy consumed, has been measured in the range 0.0124 kW to 4.88 kW of hydraulic power output and it has become clear that hydraulic thermal efficiency in this range is constant. The measured value of hydraulic thermal efficiency is 31 per cent. It has been demonstrated that hydraulic thermal efficiency is kept constant even if hydraulic power output is very small. (author)

  15. Advanced Small Free-Piston Stirling Convertors for Space Power Applications

    Science.gov (United States)

    Wood, J. Gary; Lane, Neill

    2004-02-01

    This paper reports on the current status of an advanced 35 We free-piston Stirling convertor currently being developed under NASA SBIR Phase II funding. Also described is a further advanced and higher performance ~80 watt free-piston convertor being developed by Sunpower and Boeing/Rocketdyne for NASA under NRA funding. Exceptional overall convertor (engine plus linear alternator) thermodynamic performance (greater than 50% of Carnot) with specific powers around 100 We /kg appear reasonable at these low power levels.

  16. Free-piston linear generator and the development of a solid lubrication system

    OpenAIRE

    Virsik, Roman; Rinderknecht, Frank; Friedrich, Horst E.

    2017-01-01

    The free piston linear generator is a new electromechanical generator. It converts chemical energy into electrical energy by means of a combustion process, a linear generator and a gas spring. The free piston linear generator doesn´t use any crankshaft, which is responsible for a lot of losses. Thereby the technology aims to have better properties than other electromechanical generators: higher efficiency over wide range of operating points, better noise-vibration-harshness, package … This pu...

  17. Free piston linear generator in comparison to other range-extender technologies

    OpenAIRE

    Virsik, Roman; Heron, Alex

    2013-01-01

    The free piston linear generator is a new range-extender technology. It converts chemical energy into electrical energy by means of a combustion process and linear generator. Thereby the technology aims to have better properties than other range extenders. Therefore this publication deals with the explanation of the concept and the characteristics of a free piston linear generator and a comparison to other technologies. In order to compare the range extender systems, fuel cells, micro gas tur...

  18. An investigation of the fluid-structure interaction of piston/cylinder interface

    Science.gov (United States)

    Pelosi, Matteo

    The piston/cylinder lubricating interface represents one of the most critical design elements of axial piston machines. Being a pure hydrodynamic bearing, the piston/cylinder interface fulfills simultaneously a bearing and sealing function under oscillating load conditions. Operating in an elastohydrodynamic lubrication regime, it also represents one of the main sources of power loss due to viscous friction and leakage flow. An accurate prediction of the time changing tribological interface characteristics in terms of fluid film thickness, dynamic pressure field, load carrying ability and energy dissipation is necessary to create more efficient interface designs. The aim of this work is to deepen the understanding of the main physical phenomena defining the piston/cylinder fluid film and to discover the impact of surface elastic deformations and heat transfer on the interface behavior. For this purpose, a unique fully coupled multi-body dynamics model has been developed to capture the complex fluid-structure interaction phenomena affecting the non-isothermal fluid film conditions. The model considers the squeeze film effect due to the piston micro-motion and the change in fluid film thickness due to the solid boundaries elastic deformations caused by the fluid film pressure and by the thermal strain. The model has been verified comparing the numerical results with measurements taken on special designed test pumps. The fluid film calculated dynamic pressure and temperature fields have been compared. Further validation has been accomplished comparing piston/cylinder axial viscous friction forces with measured data. The model has been used to study the piston/cylinder interface behavior of an existing axial piston unit operating at high load conditions. Numerical results are presented in this thesis.

  19. EBT ring physics

    International Nuclear Information System (INIS)

    Uckan, N.A.

    1980-04-01

    This workshop attempted to evaluate the status of the current experimental and theoretical understanding of hot electron ring properties. The dominant physical processes that influence ring formation, scaling, and their optimal behavior are also studied. Separate abstracts were prepared for each of the 27 included papers

  20. Developmental Considerations on the Free-piston Stirling Power Convertor for Use in Space

    Science.gov (United States)

    Schreiber, Jeffrey G.

    2007-01-01

    Free-piston Stirling power conversion has been considered a candidate for radioisotope power systems for space for more than a decade. Prior to the free-piston Stirling architecture, systems were designed with kinematic Stirling engines with rotary alternators to convert heat to electricity. These systems were proposed with lightly loaded linkages to achieve the necessary life. When the free-piston configuration was initially proposed, it was thought to be attractive due to the relatively high conversion efficiency, acceptable mass, and the potential for long life and high reliability. These features have consistently been recognized by teams that have studied technology options for radioisotope power systems. Since free-piston Stirling power conversion was first considered for space power applications, there have been major advances in three general areas of development: demonstration of life and reliability, the success achieved by Stirling cryocoolers in flight, and the overall developmental maturity of the technology for both flight and terrestrial applications. Based on these advances, free-piston Stirling convertors are currently being developed for a number of terrestrial applications. They commonly operate with the power, efficiency, life, and reliability as intended, and much of the development now centers on system integration. This paper will summarize the accomplishments of free-piston Stirling power conversion technology over the past decade, review the status, and discuss the challenges that remain.

  1. Wear Characteristics of Metallic Biomaterials: A Review

    Science.gov (United States)

    Hussein, Mohamed A.; Mohammed, Abdul Samad; Al-Aqeeli, Naser

    2015-01-01

    Metals are extensively used in a variety of applications in the medical field for internal support and biological tissue replacements, such as joint replacements, dental roots, orthopedic fixation, and stents. The metals and alloys that are primarily used in biomedical applications are stainless steels, Co alloys, and Ti alloys. The service period of a metallic biomaterial is determined by its abrasion and wear resistance. A reduction in the wear resistance of the implant results in the release of incompatible metal ions into the body that loosen the implant. In addition, several reactions may occur because of the deposition of wear debris in tissue. Therefore, developing biomaterials with high wear resistance is critical to ensuring a long life for the biomaterial. The aim of this work is to review the current state of knowledge of the wear of metallic biomaterials and how wear is affected by the material properties and conditions in terms of the type of alloys developed and fabrication processes. We also present a brief evaluation of various experimental test techniques and wear characterization techniques that are used to determine the tribological performance of metallic biomaterials.

  2. The Amount of Wear in Attachment of Implant-Supported Overdentures in Mandible

    Directory of Open Access Journals (Sweden)

    Fariborz Vafaee

    2016-10-01

    Full Text Available Background and objectives: One of the simplest and cheapest attachments for overdentures, is the ball-type attachment, however, keeping it during the first year of prosthesis delivery and after that is one of the main concerns of dentists. The present study aimed to assess the wear of matrix in overdentures attachment supported by one, two and three implants in the mandible. Materials and methods: Thirty edentulous patients were randomly divided into three groups: the first group received a single implant in the midline of the lower mandible, the second group two implants in areas B and D, and the third group three implants in areas B, C, and D. The attachment used in patients’ prosthetic with single and two implants was O-ball/ring attachment and for patients with three implants, the treatment plan was ball bar-supported attachments. After placing the new matrix implant for each patient and obtaining their consent, the matrix wear was measured with CMM (Coordinate Measuring Machine device. To compare matrix wear after six months and one year, measurements were repeated. Data analysis, using ANOVA and multiple comparisons was down by Tukey Test. variance with repeated measures and Tukey test were used to compare the groups two-by-two. P.value less than 0.05 was set statistical significant. SPSS 16 software was used for data analysis. Results: The data obtained from the CMM device showed that the lowest mean matrix wear in the maximum single implant and maximum mean were in group two. Conclusion: Both time and the number of implants had a significant effect on the wear of the O-ring.

  3. Nano-funnels as electro-osmotic ``tweezers and pistons''

    Science.gov (United States)

    Wang, Yanqian; Panyukov, Sergey; Zhou, Jinsheng; Menard, Laurent D.; Ramsey, J. Michael; Rubinstien, Michael

    2014-03-01

    An electric field is used to force a DNA molecule into a nano-channel by compensating the free energy penalty that results from the reduced conformational entropy of the confined macromolecule. Narrow nano-channels require high critical electric fields to achieve DNA translocation, leading to short dwell times of DNA in these channels. We demonstrate that nano-funnels integrated with nano-channels reduce the free energy barrier and lower the critical electric field required for DNA translocation. A focused electric field within the funnel increases the electric force on the DNA, compresses the molecule, and increases the osmotic pressure at the nano-channel entrance. This ``electro-osmotic piston'' forces the molecule into the nano-channel at lower electric fields than those observed without the funnel. Appropirately designed nano-funnels can also function as tweezers that allow manipulation of the position of the DNA molecule. The predictions of our theory describing double-stranded DNA behavior in nano-funnel - nano-channel devices are consistent with experimental results. Thanks for the financial support from NSF (DMR-1309892, DMR-1121107, DMR-1122483), NIH (1-P50-HL107168, 1-P01-HL108808-01A1, R01HG02647), NHGRI and CF Foundation.

  4. Progress in High Power Free-Piston Stirling Convertor Development

    Science.gov (United States)

    Brandhorst, Henry W., Jr.; Kirby, Raymond L.; Chapman, Peter A.; Walter, Thomas J.

    2008-09-01

    The U.S. Space Exploration Policy has established a vision for human exploration of the moon and Mars. One option for power for future outposts on the lunar and Martian surfaces is a nuclear reactor coupled with a free-piston Stirling convertor at a power level of 30-40 kWe. A 25 kW convertor was developed in the 1990s under the SP-100 program. This system consisted of two 12.5 kWe engines connected at their hot ends and mounted in tandem to cancel vibration. Recently, NASA began a new project with Auburn University to develop a 5 kWe, single convertor for use in such a possible lunar power system. Goals of this development program include a specific power in excess of 140 We/kg at the convertor level, lifetime in excess of five years and a control system that will safely manage the convertors in case of an emergency. Foster-Miller, Inc. is developing the 5 kWe Stirling Convertor Assembly. The characteristics of the design along with progress in developing the system will be described.

  5. Advanced Controller for the Free-Piston Stirling Convertor

    Science.gov (United States)

    Gerber, Scott S.; Jamison, Mike; Roth, Mary Ellen; Regan, Timothy F.

    2004-01-01

    The free-piston Stirling power convertor is being considered as an advanced power conversion technology to be used for future NASA deep space missions requiring long life radioisotope power systems. This technology has a conversion efficiency of over 25%, which is significantly higher than the efficiency of the Radioisotope Thermal-electric Generators (RTG) now in use. The NASA Glenn Research Center has long been recognized as a leader in Stirling technology and is responsible for the development of advanced technologies that are intended to significantly improve key characteristics of the Stirling convertor. The advanced technologies identified for development also consider the requirements of potential future missions and the new capabilities that have become available in the associated technical areas. One of the key areas identified for technology development is the engine controller. To support this activity, an advanced controller is being developed for the Stirling power convertor. This controller utilizes active power factor correction electronics and microcontroller-based controls. The object of this paper is to present an overview of the advanced controller concept with modeling, simulation and hardware test data.

  6. New 5 Kilowatt Free-Piston Stirling Space Converter Developments

    Science.gov (United States)

    Brandhorst, Henry W.

    2007-01-01

    NASA has recently funded development of a 5 kW (or greater) free-piston Stirling conversion system for reactor power systems. A nominal 5 kW converter allows two of these units to be dynamically balanced. A group of three dual-convertor combinations would yield the desired 30 kW. The status of this program will be presented. Goals include a specific power in excess of 140 W/kg at the converter level, lifetime in excess of five years and AC output. The initial step is the design and development of a nominal 5 kW per cylinder Stirling converter assembly (SCA) which will serve as a prototype of one or more SCAs that will make up the final 30 kW Stirling Converter Power System. Assumed requirements for this new converter for lunar fission power systems will be presented. The primary objective of this development effort will be to demonstrate a 5 kW SCA that can be tested to validate the viability of Stirling technology for space fission surface power systems.

  7. The ecological quasi-turbine, the best of the piston and the turbine[The supremacy of piston engines questioned; La suprematie du moteur a pistons remise en cause]; La quasiturbine ecologique, le meilleur du piston et de la turbine

    Energy Technology Data Exchange (ETDEWEB)

    Saint-Hilaire, R.; Saint-Hilaire, Y.; Saint-Hilaire, G.; Saint-Hilaire, F.

    2001-07-01

    This book presents the theory that forms the basis for quasi-turbines. The quasi-turbine is the culmination of three modern engines: it takes its inspiration from the turbine, perfects the piston, and improves Wankel engines. The quasi-turbine eliminates idle time by modifying the allocations to the various engine strokes and by replacing the progressive torque impulses by plateau impulses. The quasi-turbine optimizes engine performance with an almost constant instantaneous engine torque. The quasi-turbine can be powered by different fuels, including fossil fuels, steam, solar thermal, hydrogen, or diesel. There are several constraints associated with the quasi-turbine theory, each of which was discussed in turn. The quasi-turbine consists of four carriages which support the pivots of four pivoting blades of a variable shaped rotor and which roll as a roller bearing on the interior contour wall of a skating rink-like surface. This surface is also referred to as the Saint-Hilaire confinement profile. Engine technology is improved by increasing the mobile components utilization factor, eliminating all dead times, eliminating the excessive volume during expansion or power stroke, optimizing engine time management, allowing less time for compression and exhaust strokes, and by allowing more time and volume for intake and expansion strokes. The quasi-turbine engine satisfies the criteria of the envisioned hydrogen engine of the future. figs.

  8. Gaussian process regression for tool wear prediction

    Science.gov (United States)

    Kong, Dongdong; Chen, Yongjie; Li, Ning

    2018-05-01

    To realize and accelerate the pace of intelligent manufacturing, this paper presents a novel tool wear assessment technique based on the integrated radial basis function based kernel principal component analysis (KPCA_IRBF) and Gaussian process regression (GPR) for real-timely and accurately monitoring the in-process tool wear parameters (flank wear width). The KPCA_IRBF is a kind of new nonlinear dimension-increment technique and firstly proposed for feature fusion. The tool wear predictive value and the corresponding confidence interval are both provided by utilizing the GPR model. Besides, GPR performs better than artificial neural networks (ANN) and support vector machines (SVM) in prediction accuracy since the Gaussian noises can be modeled quantitatively in the GPR model. However, the existence of noises will affect the stability of the confidence interval seriously. In this work, the proposed KPCA_IRBF technique helps to remove the noises and weaken its negative effects so as to make the confidence interval compressed greatly and more smoothed, which is conducive for monitoring the tool wear accurately. Moreover, the selection of kernel parameter in KPCA_IRBF can be easily carried out in a much larger selectable region in comparison with the conventional KPCA_RBF technique, which helps to improve the efficiency of model construction. Ten sets of cutting tests are conducted to validate the effectiveness of the presented tool wear assessment technique. The experimental results show that the in-process flank wear width of tool inserts can be monitored accurately by utilizing the presented tool wear assessment technique which is robust under a variety of cutting conditions. This study lays the foundation for tool wear monitoring in real industrial settings.

  9. Estimating Wear Of Installed Ball Bearings

    Science.gov (United States)

    Keba, John E.; Mcvey, Scott E.

    1993-01-01

    Simple inspection and measurement technique makes possible to estimate wear of balls in ball bearing, without removing bearing from shaft on which installed. To perform measurement, one observes bearing cage while turning shaft by hand to obtain integral number of cage rotations and to measure, to nearest 2 degrees, number of shaft rotations producing cage rotations. Ratio between numbers of cages and shaft rotations depends only on internal geometry of bearing and applied load. Changes in turns ratio reflect changes in internal geometry of bearing provided measurements made with similar bearing loads. By assuming all wear occurs on balls, one computes effective value for this wear from change in turns ratio.

  10. Minimization of PWR reactor control rods wear

    International Nuclear Information System (INIS)

    Ponzoni Filho, Pedro; Moura Angelkorte, Gunther de

    1995-01-01

    The Rod Cluster Control Assemblies (RCCA's) of Pressurized Water Reactors (PWR's) have experienced a continuously wall cladding wear when Reactor Coolant Pumps (RCP's) are running. Fretting wear is a result of vibrational contact between RCCA rodlets and the guide cards which provide lateral support for the rodlets when RCCA's are withdrawn from the core. A procedure is developed to minimize the rodlets wear, by the shuffling and axial reposition of RCCA's every operating cycle. These shuffling and repositions are based on measurement of the rodlet cladding thickness of all RCCA's. (author). 3 refs, 2 figs, 2 tabs

  11. Tool wear modeling using abductive networks

    Science.gov (United States)

    Masory, Oren

    1992-09-01

    A tool wear model based on Abductive Networks, which consists of a network of `polynomial' nodes, is described. The model relates the cutting parameters, components of the cutting force, and machining time to flank wear. Thus real time measurements of the cutting force can be used to monitor the machining process. The model is obtained by a training process in which the connectivity between the network's nodes and the polynomial coefficients of each node are determined by optimizing a performance criteria. Actual wear measurements of coated and uncoated carbide inserts were used for training and evaluating the established model.

  12. Effects of Material Combinations on Friction and Wear of PEEK/Steel Pairs under Oil-Lubricated Sliding Contacts

    Science.gov (United States)

    Akagaki, T.; Nakamura, T.; Hashimoto, Y.; Kawabata, M.

    2017-05-01

    The effects of material combinations on the friction and wear of PEEK/steel pairs are studied using blocks on a ring wear tester under oil-lubricated conditions. The rings are made of forged steel (SF540A) and a PEEK composite filled with 30 wt% carbon fibre. The surface roughness is 0.15 and 0.32 μm Ra, respectively. The blocks are also made of the same materials as the rings: the forged steel and the PEEK composite. Finished with an emery paper of #600, the surface roughness is 0.06 and 0.23 μm Ra, respectively. Sliding tests for 4 combinations of two materials are conducted. The load is increased up to 1177 N at 1 N s-1. The sliding velocity is varied in the range of 10 to 19 m s-1. In some cases, the ring temperature is measured with a thermocouple with a diameter of 0.5 mm, located 1 mm below the frictional surface. Results indicate that the forged steel’s ring and the PEEK composite’s block is the best combination among 4 combinations, because seizure does not occur under the increasing load up to 1177 N at the sliding velocity of 10-19 m s-1. In contrast, seizure occurs at 15 and 19 m s-1 in the other three combinations. However, the PEEK composite’s ring shows a lower friction coefficient as compared to the forged steel’s ring, when seizure does not occur. Wear scars are observed with a scanning electron microscope (SEM). The seizure mechanisms are then discussed.

  13. Application of x-ray diffraction techniques to the understanding of the dry sliding wear behaviour of aluminium and titanium

    International Nuclear Information System (INIS)

    Zoheir, N.; Ahmet, T.A.; Northwood, D.O.

    1996-01-01

    Dry sliding wear tests were performed on polycrystalline f.c.c. Al and h.c.p. Ti specimens using a block-on-ring type wear machine with a rotating ring made of 52100 bearing steel. The sliding speed was 0.13 m.s sup -l and the applied normal load was 10 N. The wear tests were performed on a single specimen in ambient conditions and the texture was evaluated during wear using an X-ray diffraction inverse pole figure technique at a range of sliding distances. Pole density distributions for the [0001] and [111) poles for of Ti and Al, respectively, were then determined from the inverse pole figures. The texture evolution during sliding wear was subsequently related to the friction and wear behaviour. For the aluminum sample, a (111) texture developed parallel to the worn surface with increasing sliding distance (a 6 fold increase in the (111) pole density as the sliding distance increases from 0 to 2714 m). The titanium sample (normal section) which had a preferred orientation with the basal poles, [0001), parallel to the contact surface prior to testing, an increase in wear, i.e. sliding distance, did not change the texture. However, for the transverse section of titanium, the basal pole, [0001), density parallel to the worn surface increased with increasing sliding distance. The shape of the coefficient of friction versus sliding distance curve is strongly influenced by crystallographic texturing. A drop in the coefficient of friction with the progressive development of the [111) and [0001) texture was observed for both Al and Ti (transverse section) specimens, respectively

  14. Lubrication of ceramics in ring/cylinder applications

    International Nuclear Information System (INIS)

    Gaydos, P.A.; Dufrane, K.F.

    1989-01-01

    In support of efforts to apply ceramics to advanced heat engines, a study was performed of the wear mechanisms of ceramics at the ring/cylinder interface. A laboratory apparatus was constructed to reproduce most of the conditions of an actual engine but used easily prepared ring and cylinder specimens to facilitate their fabrication. Plasma-sprayed coatings of Cr 2 O 3 and hypersonic flame-sprayed coatings of cobalt-bonded WC performed particularly well as ring coatings. Similar performance was obtained with these coatings operating against SiC, Si 3 N 4 , SiC whisker-reinforced Al 2 O 3 and Cr 2 O 2 coatings. The study demonstrated the critical need for lubrication and evaluated the performance of two available lubricants

  15. On the Laurent polynomial rings

    International Nuclear Information System (INIS)

    Stefanescu, D.

    1985-02-01

    We describe some properties of the Laurent polynomial rings in a finite number of indeterminates over a commutative unitary ring. We study some subrings of the Laurent polynomial rings. We finally obtain two cancellation properties. (author)

  16. FY1995 biodegradable medical devices with molecular piston function; 1995 nendo bunshi piston kino wo yusuru iryoyo tainai bunkaisei soshi

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-03-01

    The design of biodegradable medical devices with molecular piston function is examined by utilizing the structure of polyrotaxane. A polyrotaxane in which {beta}-cyclodextrins ({beta}-CDs) are threaded onto a block-copolymer of poly(ethylene glycol) (PEG) and poly(propylene glycol) (PPG) is synthesized, and its molecular dynamics is evaluated in terms of the movement of {beta}-CDs along the copolymer. Also, polyrotaxanes in which {alpha}-cyclodextrins ({alpha}-CDs) are threaded onto a PEG chain capped with biodegradable peptide moieties are synthesized, and their degradation characteristics concerning {alpha}-CD release behavior are clarified. Cellular response to these polyrotaxanes is examined as a bioactive molecule. The polyrotaxane composed of {beta}-CDs and the block-copolymer was synthesized, and both assembled and dispersed states of {alpha}-CDs were characterized along the copolymer in response to external stimulus (temperature). Further, the polyrotaxane composed of {alpha}-CDs and PEG were synthesize, and their facility as a drug carrier was evaluated in terms of the release of {alpha}-CDs triggered by the hydrolysis of terminal peptides. Also, these biodegradable polyrotaxanes were found to enhance the fluidity of plasma membranes and to regulate cellular activation (cytoplasmic calcium increase). Thus, the polyrotaxanes were concluded to be promising as novel biomaterials aiming for medical micromachines and polymeric drug carriers. (NEDO)

  17. New computational and experimental stress analysis method for the design decision on optimum piston configuration. Piston oryoku no computer simulation to shinshikenho ni yoru keijo saitekika

    Energy Technology Data Exchange (ETDEWEB)

    Anno, N; Sugita, J [Honda R and D, Co. Ltd., Saitama (Japan)

    1993-03-01

    Piston troubles are mostly caused by cracks generating in each part of a piston. The finite element method (FEM) has been used for stress analysis of the piston, but has not been applied enough to design optimum configurations due to too much time for making models. In this study, stress analysis was carried out by the boundary element method (BEM), with which it is easy to make models and to change configurations, with various improvements. In addition, methods to execute a thermal load fatigue test and an actual running test to confirm analytical results were also improved. BEASY was used as basic software for analysis by BEM, and some improvements such as reduction of CPU time and optimization of memory using methods were carried out. It was easy to change configurations of the models by BEM, and the effect of the change in the piston boss configuration upon the stress agreed well with the actual test result. Design and evaluation of the optimum configuration has become easier by feedback of the results of the newly developed thermal load fatigue test to the analysis by BEM. 5 refs., 12 figs., 2 tabs.

  18. Patterned CoCrMo and Al2 O3 surfaces for reduced free wear debris in artificial joint arthroplasty.

    Science.gov (United States)

    Tarabolsi, Mohamad; Klassen, Thomas; Mantwill, Frank; Gärtner, Frank; Siegel, Frank; Schulz, Arndt-Peter

    2013-12-01

    Surface wear of corresponding tribological pairings is still a major problem in the application of artificial joint surgery. This study aims at developing wear reduced surfaces to utilize them in total joint arthroplasty. Using a pico-second laser, samples of medical CoCrMo metal alloy and Al2 O3 ceramic were patterned by laser material removal. The subsequent tribological investigations employed a ring-on-disc method. The results showed that those samples with modified surfaces show less mass or volume loss than those with a regular, smooth surface. Using calf serum as lubricating medium, the volume loss of the structured CoCrMo samples was eight times lower than that of regular samples. By structuring Al2 O3 surfaces, the wear volume could be reduced by 4.5 times. The results demonstrate that defined surface channels or pits enable the local sedimentation of wear debris. Thus, the amount of free debris could be reduced. Fewer abrasives in the lubricated so-called three-body-wear between the contact surfaces should result in less surface damage. Apart from direct influences on the wear behavior, less amounts of free debris of artificial joints should also be beneficial for avoiding undesired reactions with the surrounding soft tissues. The results from this study are very promising. Future investigations should involve the use of simulators meeting the natural conditions in the joint and in vivo studies with living organisms. Copyright © 2013 Wiley Periodicals, Inc., a Wiley Company.

  19. The Wearing Out of Genre Materials

    Science.gov (United States)

    Russ, Joanna

    1971-01-01

    Scenes and plots wear out in three distinct stages: Innocence, Plausibility, and Decadence. Examines westerns, spy stories, nurse novels, detective stories, science fiction, pornography, avant-garde fiction, etc. (Author/RB)

  20. Eye Wear: MedlinePlus Health Topic

    Science.gov (United States)

    ... When You Exercise (National Institute on Aging) - PDF Topic Image MedlinePlus Email Updates Get Eye Wear updates by email What's this? GO Related Health Topics Refractive Errors National Institutes of Health The primary ...

  1. The model of the dependence of the abrasive wear value on the maximal linear wear

    Directory of Open Access Journals (Sweden)

    О.А. Вишневський

    2004-01-01

    Full Text Available  The relation of the contact area of the rubber roll with a sample and the maximal linear wear value is found. The mathematical model of the dependence of the wear volume weight value on the maximal dimple depth is presented with the friction on abrasive particles fixed nonrigidly. The relation of volume weight wear with the rubber roll contact surface area with a sample with the friction on abrasive particles fixed nonrigidly is established.

  2. Breakaway frictions of dynamic O-rings in mechanical seals

    Science.gov (United States)

    Lai, Tom; Kay, Peter

    1993-05-01

    Breakaway friction of a dynamic O-ring affects the mechanical seal's response to large axial shaft movement and face wear. However, little data exist to help designers. Therefore, a test rig was developed to measure breakaway friction. The research quantitatively shows the effects of lubrication with silicone grease and a change of surface finish. By using the Taguchi statistical experimental design method, the significance of test parameters was evaluated with a minimum number of tests. It was found that fluid pressure, dwell time, and O-ring percentage squeeze affect O-ring breakaway friction more than the O-ring cross sectional diameter and axial sliding speed within the range of values tested. The authors showed that breakaway friction increased linearly with pressure. However, O-rings made of different materials had significantly different increase rates, even if they had nominally the same durometer hardness. Breakaway friction also increased with logarithm of dwell time. Again, the increase rate depended strongly on the specific O-ring material tested. These observations led the authors to believe that the typical approach of generalizing data based on generic polymer type and durometer was inappropriate.

  3. Heavy ion storage rings

    International Nuclear Information System (INIS)

    Schuch, R.

    1987-01-01

    A brief overview of synchrotron storage rings for heavy ions, which are presently under construction in different accelerator laboratories is given. Ions ranging from protons up to uranium ions at MeV/nucleon energies will be injected into these rings using multiturn injection from the accelerators available or being built in these laboratories. After injection, it is planned to cool the phase space distribution of the ions by merging them with cold electron beams or laser beams, or by using stochastic cooling. Some atomic physics experiments planned for these rings are presented. 35 refs

  4. Faithfully quadratic rings

    CERN Document Server

    Dickmann, M

    2015-01-01

    In this monograph the authors extend the classical algebraic theory of quadratic forms over fields to diagonal quadratic forms with invertible entries over broad classes of commutative, unitary rings where -1 is not a sum of squares and 2 is invertible. They accomplish this by: (1) Extending the classical notion of matrix isometry of forms to a suitable notion of T-isometry, where T is a preorder of the given ring, A, or T = A^2. (2) Introducing in this context three axioms expressing simple properties of (value) representation of elements of the ring by quadratic forms, well-known to hold in

  5. Thin layer activation: measuring wear and corrosion

    International Nuclear Information System (INIS)

    Delvigne, T.; Leyman, D.; Oxorn, K.

    1995-01-01

    The technique known as thin layer activation (TLA) is explained and assessed in this article. Widely used, in for example the automotive industry, TLA allows on-line monitoring of the loss of matter from a critical surface, by wear erosion and corrosion. The technique offers extremely high sensitivity thus leading to reduced test times. On-line wear phenomena can be assessed during operation of a mechanical process, even through thick engine walls. (UK)

  6. Biocompatible wear-resistant thick ceramic coating

    Directory of Open Access Journals (Sweden)

    Vogt Nicola

    2016-09-01

    Full Text Available Sensitisation to immunologically active elements like chromium, cobalt or nickel and debris particle due to wear are serious problems for patients with metallic implants. We tested the approach of using a hard and thick ceramic coating as a wear-resistant protection of titanium implants, avoiding those sensitisation and foreign body problems. We showed that the process parameters strongly influence the coating porosity and, as a consequence, also its hardness.

  7. Third abrasive wear mode: is it possible?

    Directory of Open Access Journals (Sweden)

    Ronaldo Câmara Cozza

    2014-04-01

    Full Text Available The objective of this paper is to propose an initial discussion on the characterization of a third abrasive wear mode. The results obtained in a previous work [1] under different test conditions revealed the occurrence of the superposition of the “rolling” and “grooving” abrasive wear modes. This phenomenon was denoted “micro-rolling abrasion” due to the observation that “rolling abrasion” was found to act on “grooving abrasion”.

  8. Space Power Free-Piston Stirling Engine Scaling Study

    Science.gov (United States)

    Jones, D.

    1989-01-01

    The design feasibility study is documented of a single cylinder, free piston Stirling engine/linear alternator (FPSE/LA) power module generating 150 kW-electric (kW sub e), and the determination of the module's maximum feasible power level. The power module configuration was specified to be a single cylinder (single piston, single displacer) FPSE/LA, with tuning capacitors if required. The design requirements were as follows: (1) Maximum electrical power output; (2) Power module thermal efficiency equal to or greater than 20 percent at a specific mass of 5 to 8 kg/kW(sub e); (3) Heater wall temperature/cooler wall temperature = 1050 K/525 K; (4) Sodium heat-pipe heat transport system, pumped loop NaK (sodium-potassium eutectic mixture) rejection system; (5) Maximum power module vibration amplitude = 0.0038 cm; and (6) Design life = 7 years (60,000 hr). The results show that a single cylinder FPSE/LA is capable of meeting program goals and has attractive scaling attributes over the power range from 25 to 150 kW(sub e). Scaling beyond the 150 kW(sub e) power level, the power module efficiency falls and the power module specific mass reaches 10 kg/kW(sub e) at a power output of 500 kW(sub e). A discussion of scaling rules for the engine, alternator, and heat transport systems is presented, along with a detailed description of the conceptual design of a 150 kW(sub e) power module that meets the requirements. Included is a discussion of the design of a dynamic balance system. A parametric study of power module performance conducted over the power output range of 25 to 150 kW(sub e) for temperature ratios of 1.7, 2.0, 2.5, and 3.0 is presented and discussed. The results show that as the temperature ratio decreases, the efficiency falls and specific mass increases. At a temperature ratio of 1.7, the 150 kW(sub e) power module cannot satisfy both efficiency and specific mass goals. As the power level increases from 25 to 150 kW(sub e) at a fixed temperature ratio, power

  9. Pseudomembranous candidiasis in patient wearing full denture

    Directory of Open Access Journals (Sweden)

    Nurdiana Nurdiana

    2009-06-01

    Full Text Available Background: Oral candidiasis is a common opportunistic infection of the oral cavity caused by an overgrowth of Candida species, the commonest being Candida albicans. Candida albicans is a harmless commensal organism inhabiting the mouths but it can change into pathogen and invade tissue and cause acute and chronic disease. Dentures predispose to infection with Candida in as many as 65% of elderly people wearing full upper dentures. Purpose: The purpose of this case report is to discuss thrush in patient wearing full denture which rapidly developed. Case: This paper report a case of 57 year-old man who came to the Oral Medicine Clinic Faculty of Dentistry Airlangga University with clinical appearance of pseudomembranous candidiasis (thrush. Case Management: Diagnosis of this case is confirmed with microbiology examination. Patient was wearing full upper dentures, and from anamnesis known that patient wearing denture for 24 hours and he had poor oral hygiene. Patient was treated with topical (nystatin oral suspension and miconazole oral gel and systemic (ketoconazole antifungal. Patient also instructed not to wear his denture and cleaned white pseudomembrane on his mouth with soft toothbrush. Conclusion: Denture, habit of wearing denture for 24 hours, and poor oral hygiene are predisposing factors of thrush and it can healed completely after treated with topical and systemic antifungal.

  10. Grain size dependence of wear in ceramics

    International Nuclear Information System (INIS)

    Wu, C.C.; Rice, R.W.; Johnson, D.; Platt, B.A.

    1985-01-01

    Pin-On-Disk (POD), microwear tests of Al 2 O 3 , MgO, MgAl 2 O 4 , and ZrO 2 , most being dense and essentially single phase, showed the reciprocal of wear following a hall-petch type relationship. However, extrapolation to infinite grain size always gave a lower intercept than most or all single-crystal values; in particular, Al 2 O 3 data projects to a negative intercept. Initial macro wear tests of some of the same Al 2 O 3 materials also indicate a hall-petch type grain-size dependence, but with a greatly reduced grain-size dependence, giving a positive hall-petch intercept. Further, the macrowear grain-size dependence appears to decrease with increased wear. It is argued that thermal expansion anisotropy (of Al 2 O 3 ) significantly affects the grain size dependence of POD wear, in particular, giving a negative intercept, while elastic anisotropy is suggested as a factor in the grain-size dependence of the cubic (MgO, MgAl 2 O 4 , and ZrO 2 ) materials. The reduced grain-size dependence in the macrowear tests is attributed to overlapping wear tracks reducing the effects of enhanced wear damage, e.g., from elastic and thermal expansion anisotropies

  11. On arbitrarily graded rings

    Indian Academy of Sciences (India)

    58

    paper is devoted to the study of arbitrary rings graded through arbitrary sets. .... which recover certain multiplicative relations among the homogeneous components ... instance the case in which the grading set A is an Abelian group, where the ...

  12. The g-2 ring

    CERN Multimedia

    1974-01-01

    The precise measurement of "g-2", the anomalous magnetic moment of the muon, required a special muon storage ring with electrostatic focussing and very accurate knowledge of the magnetic bending field. For more details see under photo 7405430.

  13. [Liesegang's rings resembling helminthiasis].

    Science.gov (United States)

    Zámecník, M; Riedl, I

    1996-12-01

    So called Liesegang's rings are lamellar corpuscles which develop after periodical precipitation of oversaturated solutions in gel medium. They can occur in cysts, closed cavities, inflammatory exudates and necroses. They resemble parasitic eggs, larvae or adult forms. A case of 28-year-old woman is presented with many Liesegang's rings in a stuff from dilated renal calyx. Their preliminary evaluation considered helminths, especially Dioctophyma renale.

  14. Storage ring group summary

    International Nuclear Information System (INIS)

    King, N.M.

    1980-01-01

    The Storage Ring Group set out to identify and pursue salient problems in accelerator physics for heavy ion fusion, divorced from any particular reference design concept. However, it became apparent that some basic parameter framework was required to correlate the different study topics. As the Workshop progressed, ring parameters were modified and updated. Consequently, the accompanying papers on individual topics will be found to refer to slightly varied parameters, according to the stage at which the different problems were tackled

  15. The rings of Uranus

    Science.gov (United States)

    Elliot, J. L.; Dunham, E.; Mink, D.

    1977-01-01

    A description is given of the observation of five brief occultations of the star SAO 158687 which occurred both before and after its occultation by Uranus on March 10, 1977. The events were observed with a three-channel occultation photometer, attached to a 91-cm telescope. The observations indicate that at least five rings encircle the planet Uranus. Possible reasons for the narrowness of the Uranus rings are discussed.

  16. Design and preliminary test of heat isulated pistons for a diesel engine. Dieselmoottorin laempoeeristetyn maennaen suunnittelu ja esikokeet

    Energy Technology Data Exchange (ETDEWEB)

    Kojonen, M.; Pitkaenen, J.; Kleimola, M.

    1989-01-01

    This report describes the ceramic heat insulation of the combustion chamber of high speed diesel engines and results of tests carried out in one cylinder of a four-cylinder engine with two different heat insulated experimental pistons. The work is part of the research programme called 'Ceramic applications in mechanical engineering'. The research work is being done at Helsinki University of Technology in the Internal Combustion Engine Laboratory and is financed mainly by the Technology Development Centre TEKES. Valmet Oy Linnavuori Works has contributed to the work by supplying the test engine for the research. In the short literature review presented first. advantages of the combustion chamber insulation and design solutions for heat flow prevention are described. In the experimental part of the research two different experimental pistons with ceramic combustion chamber were designed for the Valmet 411 DSJ diesel engine with direct injection. One of the pistons was furnished with a steel piston head, which was fastened to the aluminium piston body. The ceramic combustion chamber bowl was inserted into the steel head. The other piston was developed from Kymenite cast iron, which made it possible to insert the piston bowl direct into the piston body. The aim of the experiments was to clarify the function ability and the necessary clearances of the piston constructions and to indicate the insulation ability of the combustion chamber by means of the temperature measurements of the cylinder liner, cylinder head and exhaust gas temperature.

  17. Free-Piston Stirling Power Conversion Unit for Fission Power System, Phase II Final Report

    Science.gov (United States)

    Wood, J. Gary; Stanley, John

    2016-01-01

    In Phase II, the manufacture and testing of two 6-kW(sub e)Stirling engines was completed. The engines were delivered in an opposed 12-kW(sub e) arrangement with a common expansion space heater head. As described in the Phase I report, the engines were designed to be sealed both hermetically and with a bolted O-ring seal. The completed Phase II convertor is in the bolted configuration to allow future disassembly. By the end of Phase II, the convertor had passed all of the final testing requirements in preparation for delivery to the NASA Glenn Research Center. The electronic controller also was fabricated and tested during Phase II. The controller sets both piston amplitudes and maintains the phasing between them. It also sets the operating frequency of the machine. Details of the controller are described in the Phase I final report. Fabrication of the direct-current to direct-current (DC-DC) output stage, which would have stepped down the main controller output voltage from 700 to 120 V(sub DC), was omitted from this phase of the project for budgetary reasons. However, the main controller was successfully built, tested with the engines, and delivered. We experienced very few development issues with this high-power controller. The project extended significantly longer than originally planned because of yearly funding delays. The team also experienced several hardware difficulties along the development path. Most of these were related to the different thermal expansions of adjacent parts constructed of different materials. This issue was made worse by the large size of the machine. Thermal expansion problems also caused difficulties in the brazing of the opposed stainless steel sodium-potassium (NaK) heater head. Despite repeated attempts Sunpower was not able to successfully braze the opposed head under this project. Near the end of the project, Glenn fabricated an opposed Inconel NaK head, which was installed prior to delivery for testing at Glenn. Engine

  18. A rolling-gliding wear simulator for the investigation of tribological material pairings for application in total knee arthroplasty

    Directory of Open Access Journals (Sweden)

    Denkena Berend

    2010-06-01

    Full Text Available Abstract Background Material wear testing is an important technique in the development and evaluation of materials for use in implant for total knee arthroplasty. Since a knee joint induces a complex rolling-gliding movement, standardised material wear testing devices such as Pin-on-Disc or Ring-on-Disc testers are suitable to only a limited extent because they generate pure gliding motion only. Methods A rolling-gliding wear simulator was thus designed, constructed and implemented, which simulates and reproduces the rolling-gliding movement and loading of the knee joint on specimens of simplified geometry. The technical concept was to run a base-plate, representing the tibia plateau, against a pivoted cylindrical counter-body, representing one femur condyle under an axial load. A rolling movement occurs as a result of the friction and pure gliding is induced by limiting the rotation of the cylindrical counter-body. The set up also enables simplified specimens handling and removal for gravimetrical wear measurements. Long-term wear tests and gravimetrical wear measurements were carried out on the well known material pairings: cobalt chrome-polyethylene, ceramic-polyethylene and ceramic-ceramic, over three million motion cycles to allow material comparisons to be made. Results The observed differences in wear rates between cobalt-chrome on polyethylene and ceramic on polyethylene pairings were similar to the differences of published data for existing material-pairings. Test results on ceramic-ceramic pairings of different frontal-plane geometry and surface roughness displayed low wear rates and no fracture failures. Conclusions The presented set up is able to simulate the rolling-gliding movement of the knee joint, is easy to use, and requires a minimum of user intervention or monitoring. It is suitable for long-term testing, and therefore a useful tool for the investigation of new and promising materials which are of interest for application in

  19. A rolling-gliding wear simulator for the investigation of tribological material pairings for application in total knee arthroplasty.

    Science.gov (United States)

    Richter, Berna I; Ostermeier, Sven; Turger, Anke; Denkena, Berend; Hurschler, Christof

    2010-06-15

    Material wear testing is an important technique in the development and evaluation of materials for use in implant for total knee arthroplasty. Since a knee joint induces a complex rolling-gliding movement, standardised material wear testing devices such as Pin-on-Disc or Ring-on-Disc testers are suitable to only a limited extent because they generate pure gliding motion only. A rolling-gliding wear simulator was thus designed, constructed and implemented, which simulates and reproduces the rolling-gliding movement and loading of the knee joint on specimens of simplified geometry. The technical concept was to run a base-plate, representing the tibia plateau, against a pivoted cylindrical counter-body, representing one femur condyle under an axial load. A rolling movement occurs as a result of the friction and pure gliding is induced by limiting the rotation of the cylindrical counter-body. The set up also enables simplified specimens handling and removal for gravimetrical wear measurements. Long-term wear tests and gravimetrical wear measurements were carried out on the well known material pairings: cobalt chrome-polyethylene, ceramic-polyethylene and ceramic-ceramic, over three million motion cycles to allow material comparisons to be made. The observed differences in wear rates between cobalt-chrome on polyethylene and ceramic on polyethylene pairings were similar to the differences of published data for existing material-pairings. Test results on ceramic-ceramic pairings of different frontal-plane geometry and surface roughness displayed low wear rates and no fracture failures. The presented set up is able to simulate the rolling-gliding movement of the knee joint, is easy to use, and requires a minimum of user intervention or monitoring. It is suitable for long-term testing, and therefore a useful tool for the investigation of new and promising materials which are of interest for application in knee joint replacement implants.

  20. A rolling-gliding wear simulator for the investigation of tribological material pairings for application in total knee arthroplasty

    Science.gov (United States)

    2010-01-01

    Background Material wear testing is an important technique in the development and evaluation of materials for use in implant for total knee arthroplasty. Since a knee joint induces a complex rolling-gliding movement, standardised material wear testing devices such as Pin-on-Disc or Ring-on-Disc testers are suitable to only a limited extent because they generate pure gliding motion only. Methods A rolling-gliding wear simulator was thus designed, constructed and implemented, which simulates and reproduces the rolling-gliding movement and loading of the knee joint on specimens of simplified geometry. The technical concept was to run a base-plate, representing the tibia plateau, against a pivoted cylindrical counter-body, representing one femur condyle under an axial load. A rolling movement occurs as a result of the friction and pure gliding is induced by limiting the rotation of the cylindrical counter-body. The set up also enables simplified specimens handling and removal for gravimetrical wear measurements. Long-term wear tests and gravimetrical wear measurements were carried out on the well known material pairings: cobalt chrome-polyethylene, ceramic-polyethylene and ceramic-ceramic, over three million motion cycles to allow material comparisons to be made. Results The observed differences in wear rates between cobalt-chrome on polyethylene and ceramic on polyethylene pairings were similar to the differences of published data for existing material-pairings. Test results on ceramic-ceramic pairings of different frontal-plane geometry and surface roughness displayed low wear rates and no fracture failures. Conclusions The presented set up is able to simulate the rolling-gliding movement of the knee joint, is easy to use, and requires a minimum of user intervention or monitoring. It is suitable for long-term testing, and therefore a useful tool for the investigation of new and promising materials which are of interest for application in knee joint replacement

  1. Wear-resistance of Aluminum Matrix Microcomposite Materials

    Directory of Open Access Journals (Sweden)

    M. Kandeva

    2011-03-01

    Full Text Available A procedure is developed for the study of wear of aluminum alloys AlSi7 obtained by casting, reinforced by TiC microparticles, before and after heat treatment. Tribological study is realized under conditions of friction on counterbody with fixed abrasive. Experimental results were obtained for mass wear, wear rate, wear intensity and wear-resistance of the alloys with different wt% of microparticles.

  2. Interaction of a vortex ring and a bubble

    Science.gov (United States)

    Jha, Narsing K.; Govardhan, Raghuraman N.

    2014-11-01

    Micro-bubble injection in to boundary layers is one possible method for reducing frictional drag of ships. Although this has been studied for some time, the physical mechanisms responsible for drag reduction using microbubbles in turbulent boundary layers is not yet fully understood. Previous studies suggest that bubble-vortical structure interaction seems to be one of the important physical mechanisms for frictional drag reduction using microbubbles. In the present work, we study a simplification of this problem, namely, the interaction of a single vortical structure, in particular a vortex ring, with a single bubble for better understanding of the physics. The vortex ring is generated using a piston-cylinder arrangement and the bubble is generated by connecting a capillary to an air pump. The bubble dynamics is directly visualized using a high speed camera, while the vorticity modification is measured using time resolved PIV. The results show that significant deformations can occur of both the bubble and the vortex ring. Effect of different non-dimensional parameters on the interaction will be presented in the meeting.

  3. Extended Analytic Linear Model of Hydraulic Cylinder With Respect Different Piston Areas and Volumes

    Directory of Open Access Journals (Sweden)

    Petr KOŇAŘÍK

    2009-06-01

    Full Text Available Standard analytic linear model of hydraulic cylinder usually comes from assumptions of identical action piston areas on both sides of hydraulic cylinder (double piston rod and suitable operation point, which is usually chosen in the middle of piston. By reason of that volumes inside of cylinder are than same. Moreover for control of that arrangement of hydraulic cylinder, usually controlled by 4/3 servovalve, the same mount of flows comes in and comes out to each of chambers of hydraulic cylinder. Presented paper deal with development of extended form of analytic linear model of single piston rod hydraulic cylinder which respects different action piston areas and volumes inside of chambers of hydraulic cylinder and also two different input flows of hydraulic cylinder. In extended model are also considered possibilities of different dead volumes in hoses and intake parts of hydraulic cylinder. Dead volume has impact on damping of hydraulic cylinder. Because the system of hydraulic cylinder is generally presented as a integrative system with inertia of second order: eq , we can than obtain time constants and damping of hydraulic cylinder for each of analytic form model. The model has arisen for needs of model fractionation on two parts. Part of behaviour of chamber A and part of behaviour of chamber B of cylinder. It was created for the reason of analysis and synthesis of control parameters of regulation circuit of multivalve control concept of hydraulic drive with separately controlled chamber A and B which could be then used for.

  4. Development of cryogenic free-piston reciprocating expander utilizing phase controller

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Jeong Min; Park, Ji Ho; Kim, Kyung Joong; Jeong, Sang Kwon [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2016-06-15

    A free-piston reciprocating expander is a device which operates without any mechanical linkage to a stationary part. Since the motion of the floating piston is only controlled by the pressure difference at two ends of the piston, this kind of expander may indispensably require a sophisticated active control system equipped with multiple valves and reservoirs. In this paper, we have suggested a novel design that can further reduce complexity of the previously developed cryogenic free-piston expander configuration. It is a simple replacement of both multiple valves and reservoirs by a combination of an orifice valve and a reservoir. The functional characteristic of the integrated orifice-reservoir configuration is similar to that of a phase controller applied in a pulse tube refrigerator so that we designate the one as a phase controller. Depending on the orifice valve size in the phase controller, the different PV work which affects the expander performance is generated. The numerical model of this unique free-piston reciprocating expander utilizing a phase controller is established to understand and analyze quantitatively the performance variation of the expander under different valve timing and orifice valve size. The room temperature experiments are carried out to examine the performance of this newly developed cryogenic expander.

  5. Development of cryogenic free-piston reciprocating expander utilizing phase controller

    International Nuclear Information System (INIS)

    Cha, Jeong Min; Park, Ji Ho; Kim, Kyung Joong; Jeong, Sang Kwon

    2016-01-01

    A free-piston reciprocating expander is a device which operates without any mechanical linkage to a stationary part. Since the motion of the floating piston is only controlled by the pressure difference at two ends of the piston, this kind of expander may indispensably require a sophisticated active control system equipped with multiple valves and reservoirs. In this paper, we have suggested a novel design that can further reduce complexity of the previously developed cryogenic free-piston expander configuration. It is a simple replacement of both multiple valves and reservoirs by a combination of an orifice valve and a reservoir. The functional characteristic of the integrated orifice-reservoir configuration is similar to that of a phase controller applied in a pulse tube refrigerator so that we designate the one as a phase controller. Depending on the orifice valve size in the phase controller, the different PV work which affects the expander performance is generated. The numerical model of this unique free-piston reciprocating expander utilizing a phase controller is established to understand and analyze quantitatively the performance variation of the expander under different valve timing and orifice valve size. The room temperature experiments are carried out to examine the performance of this newly developed cryogenic expander

  6. Piston-assisted proton pumping in Complex I of mitochondria membranes

    Science.gov (United States)

    Mourokh, Lev; Filonenko, Ilan

    2014-03-01

    Proton-pumping mechanism of Complex I remains mysterious because its electron and proton paths are well separated and the direct Coulomb interaction seems to be negligible. The structure of this enzyme was resolved very recently and its functionality was connected the shift of the helix HL. We model the helix as a piston oscillating between the protons and electrons. We assume that positive charges are accumulated near the edges of the helix. In the oxidized state, the piston is attracted to electrons, so its distance to the proton sites increases, the energy of these sites decreases and the sites can be populated. When electrons proceed to the drain, elastic forces return the piston to the original position and the energies of populated proton sites increase, so the protons can be transferred to the positive site of the membrane. In this work, we explore a simplified model when the interaction of the piston with electrons is replaced by a periodic force. We derive quantum Heisenberg equations for the proton operators and solve them jointly with the Langevin equation for the piston position. We show that the proton pumping is possible in such structure with parameters closely resembling the real system. We also address the feasibility of using such mechanism in nanoelectronics.

  7. Dynamic Pressure Gradient Model of Axial Piston Pump and Parameters Optimization

    Directory of Open Access Journals (Sweden)

    Shi Jian

    2014-01-01

    Full Text Available The unsteady pressure gradient can cause flow noise in prepressure rising of piston pump, and the fluid shock comes up due to the large pressure difference of the piston chamber and discharge port in valve plate. The flow fluctuation control is the optimization objective in previous study, which cannot ensure the steady pressure gradient. Our study is to stabilize the pressure gradient in prepressure rising and control the pressure of piston chamber approaching to the pressure in discharge port after prepressure rising. The models for nonoil shock and dynamic pressure of piston chamber in prepressure rising are established. The parameters of prepressure rising angle, cross angle, wrap angle of V-groove, vertex angle of V-groove, and opening angle of V-groove were optimized, based on which the pressure of the piston chamber approached the pressure in discharge port after prepressure rising, and the pressure gradient is more steady compared to the original parameters. The max pressure gradient decreased by 70.8% and the flow fluctuation declined by 21.4%, which showed the effectivness of optimization.

  8. Optimal paths of piston motion of irreversible diesel cycle for minimum entropy generation

    Directory of Open Access Journals (Sweden)

    Ge Yanlin

    2011-01-01

    Full Text Available A Diesel cycle heat engine with internal and external irreversibility’s of heat transfer and friction, in which the finite rate of combustion is considered and the heat transfer between the working fluid and the environment obeys Newton’s heat transfer law [q≈ Δ(T], is studied in this paper. Optimal piston motion trajectories for minimizing entropy generation per cycle are derived for the fixed total cycle time and fuel consumed per cycle. Optimal control theory is applied to determine the optimal piston motion trajectories for the cases of with piston acceleration constraint on each stroke and the optimal distribution of the total cycle time among the strokes. The optimal piston motion with acceleration constraint for each stroke consists of three segments, including initial maximum acceleration and final maximum deceleration boundary segments, respectively. Numerical examples for optimal configurations are provided, and the results obtained are compared with those obtained when maximizing the work output with Newton’s heat transfer law. The results also show that optimizing the piston motion trajectories could reduce engine entropy generation by more than 20%. This is primarily due to the decrease in entropy generation caused by heat transfer loss on the initial portion of the power stroke.

  9. Development of free-piston Stirling engine performance and optimization codes based on Martini simulation technique

    Science.gov (United States)

    Martini, William R.

    1989-01-01

    A FORTRAN computer code is described that could be used to design and optimize a free-displacer, free-piston Stirling engine similar to the RE-1000 engine made by Sunpower. The code contains options for specifying displacer and power piston motion or for allowing these motions to be calculated by a force balance. The engine load may be a dashpot, inertial compressor, hydraulic pump or linear alternator. Cycle analysis may be done by isothermal analysis or adiabatic analysis. Adiabatic analysis may be done using the Martini moving gas node analysis or the Rios second-order Runge-Kutta analysis. Flow loss and heat loss equations are included. Graphical display of engine motions and pressures and temperatures are included. Programming for optimizing up to 15 independent dimensions is included. Sample performance results are shown for both specified and unconstrained piston motions; these results are shown as generated by each of the two Martini analyses. Two sample optimization searches are shown using specified piston motion isothermal analysis. One is for three adjustable input and one is for four. Also, two optimization searches for calculated piston motion are presented for three and for four adjustable inputs. The effect of leakage is evaluated. Suggestions for further work are given.

  10. Geotribology - Friction, wear, and lubrication of faults

    Science.gov (United States)

    Boneh, Yuval; Reches, Ze'ev

    2018-05-01

    We introduce here the concept of Geotribology as an approach to study friction, wear, and lubrication of geological systems. Methods of geotribology are applied here to characterize the friction and wear associated with slip along experimental faults composed of brittle rocks. The wear in these faults is dominated by brittle fracturing, plucking, scratching and fragmentation at asperities of all scales, including 'effective asperities' that develop and evolve during the slip. We derived a theoretical model for the rate of wear based on the observation that the dynamic strength of brittle materials is proportional to the product of load stress and loading period. In a slipping fault, the loading period of an asperity is inversely proportional to the slip velocity, and our derivations indicate that the wear-rate is proportional to the ratio of [shear-stress/slip-velocity]. By incorporating the rock hardness data into the model, we demonstrate that a single, universal function fits wear data of hundreds of experiments with granitic, carbonate and sandstone faults. In the next step, we demonstrate that the dynamic frictional strength of experimental faults is well explained in terms of the tribological parameter PV factor (= normal-stress · slip-velocity). This factor successfully delineates weakening and strengthening regimes of carbonate and granitic faults. Finally, our analysis revealed a puzzling observation that wear-rate and frictional strength have strikingly different dependencies on the loading conditions of normal-stress and slip-velocity; we discuss sources for this difference. We found that utilization of tribological tools in fault slip analyses leads to effective and insightful results.

  11. Some Aspects of Ring Theory

    CERN Document Server

    Herstein, IN

    2011-01-01

    S. Amitsur: Associative rings with identities.- I.N. Herstein: Topics in ring theory.- N. Jacobson: Representation theory of Jordan algebras.- I. Kaplansky: The theory of homological dimension.- D. Buchsbaum: Complexes in local ring theory.- P.H. Cohn: Two topics in ring theory.- A.W. Goldie: Non-commutative localisation.

  12. Abrasive wear of ceramic wear protection at ambient and high temperatures

    Science.gov (United States)

    Varga, M.; Adam, K.; Tumma, M.; Alessio, K. O.

    2017-05-01

    Ceramic wear protection is often applied in abrasive conditions due to their excellent wear resistance. This is especially necessary in heavy industries conveying large amounts of raw materials, e.g. in steel industry. Some plants also require material transport at high temperatures and velocities, making the need of temperature stable and abrasion resistant wear protection necessary. Various types and wear behaviour of ceramic protection are known. Hence, the goal of this study is to identify the best suitable ceramic materials for abrasive conditions in harsh environments at temperatures up to 950°C and severe thermal gradients. Chamottes, known for their excellent thermal shock resistance are compared to high abrasion resistant ceramic wear tiles and a cost efficient cement-bounded hard compound. Testing was done under high-stress three-body abrasion regime with a modified ASTM G65 apparatus enabling for investigations up to ~950°C. Thereto heated abrasive is introduced into the wear track and also preheated ceramic samples were used and compared to ambient temperature experiments. Results indicate a significant temperature influence on chamottes and the hard compound. While the chamottes benefit from temperature increase, the cement-bounded hard compound showed its limitation at abrasive temperatures of 950°C. The high abrasion resistant wear tiles represented the materials with the best wear resistance and less temperature influence in the investigated range.

  13. Quantitive dynamical wear analysis and the convergent quest for significant wear reduction

    International Nuclear Information System (INIS)

    Sellschop, F.; Kirsch, J.; Derry, T.; Marcus, R.

    1984-01-01

    The maturing of nuclear physics has made the development of ion beam modification of materials possible, bringing new skills and prospects to the world of materials science. In the following paper an outline is given of the history of ion beam modification of materials (IBMM) and its use for altering the surface of metals to combat wear and friction, and monitoring wear in engines

  14. Wear mechanisms and friction parameters for sliding wear of micron-scale polysilicon sidewalls

    NARCIS (Netherlands)

    Alsem, D. H.; van der Hulst, R.; Stach, E. A.; Dugger, M. T.; De Hosson, J. Th. M.; Ritchie, R. O.

    As tribological properties are critical factors in the reliability of silicon-based microelectromechanical systems, it is important to understand what governs wear and friction. Average dynamic friction, wear volumes and morphology have been studied for polysilicon devices fabricated using the

  15. Ring correlations in random networks.

    Science.gov (United States)

    Sadjadi, Mahdi; Thorpe, M F

    2016-12-01

    We examine the correlations between rings in random network glasses in two dimensions as a function of their separation. Initially, we use the topological separation (measured by the number of intervening rings), but this leads to pseudo-long-range correlations due to a lack of topological charge neutrality in the shells surrounding a central ring. This effect is associated with the noncircular nature of the shells. It is, therefore, necessary to use the geometrical distance between ring centers. Hence we find a generalization of the Aboav-Weaire law out to larger distances, with the correlations between rings decaying away when two rings are more than about three rings apart.

  16. Experimental evaluation of the wear of the PEC type fuel element base. Tribological experimental studies in Na at high temperature

    International Nuclear Information System (INIS)

    D'Agraives, B.C.; Volcan, A.; Bacchilega, A.

    1978-01-01

    Tribological studies in sodium, related to the PEC-type fuel element design are presented. They are aimed at the simulation of friction and wear phenomena which are expected to occur on the surface of fuel element components undergoing solid-solid contact situations with variable loads and/or variable motions. In this first paper, a description of the preparatory work is given. Then, results related to long-duration experiments are shown with respect to the contact between the centering spherical ring belonging to the lower extension of the subassembly, and the cylindrical sleeve of the grid in which it takes place. After 1000 hours under loaded and vibrated conditions, in sodium at 400 0 C, the wear effects suffered by both contacting samples, are observed and evaluated. The stellite surfaces of the samples are damaged to a not-negligible extent and material transfers from the cylindrical sleeve onto the spherical ring occur

  17. Analysis of mechanism of carbide tool wear and control by wear process

    Directory of Open Access Journals (Sweden)

    Pham Hoang Trung

    2017-01-01

    Full Text Available The analysis of physic-mechanical and thermal physic properties of hard alloys depending on their chemical composition is conducted. The correlation of cutting properties and regularities of carbide tool wear with cutting conditions and thermal physic properties of tool material are disclosed. Significant influence on the tool wear of not only mechanical, but, in the first place, thermal physic properties of tool and structural materials is established by the researches of Russian scientists, because in the range of industrial used cutting speeds the cause of tool wear are diffusion processes. The directions of intensity decreasing of tool wear by determining rational processing conditions, the choice of tool materials and wear-resistant coating on tool surface are defined.

  18. Mapping Ring Particle Cooling across Saturn's Rings with Cassini CIRS

    Science.gov (United States)

    Brooks, Shawn M.; Spilker, L. J.; Edgington, S. G.; Pilorz, S. H.; Deau, E.

    2010-10-01

    Previous studies have shown that the rings' thermal inertia, a measure of their response to changes in the thermal environment, varies from ring to ring. Thermal inertia can provide insight into the physical structure of Saturn's ring particles and their regoliths. Low thermal inertia and quick temperature responses are suggestive of ring particles that have more porous or fluffy regoliths or that are riddled with cracks. Solid, coherent particles can be expected to have higher thermal inertias (Ferrari et al. 2005). Cassini's Composite Infrared Spectrometer has recorded millions of spectra of Saturn's rings since its arrival at Saturn in 2004 (personal communication, M. Segura). CIRS records far infrared radiation between 10 and 600 cm-1 (16.7 and 1000 µm) at focal plane 1 (FP1), which has a field of view of 3.9 mrad. Thermal emission from Saturn's rings peaks in this wavelength range. FP1 spectra can be used to infer ring temperatures. By tracking how ring temperatures vary, we can determine the thermal inertia of the rings. In this work we focus on CIRS observations of the shadowed portion of Saturn's rings. The thermal budget of the rings is dominated by the solar radiation absorbed by its constituent particles. When ring particles enter Saturn's shadow this source of energy is abruptly cut off. As a result, ring particles cool as they traverse Saturn's shadow. From these shadow observations we can create cooling curves at specific locations across the rings. We will show that the rings' cooling curves and thus their thermal inertia vary not only from ring to ring, but by location within the individual rings. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. Copyright 2010 California Institute of Technology. Government sponsorship acknowledged.

  19. Performance of ceramics in ring/cylinder applications

    International Nuclear Information System (INIS)

    Dufrane, K.F.; Glaeser, W.A.

    1987-01-01

    In support of the efforts to apply ceramics to advanced heat engines, a study is being performed of the performance of ceramics at the ring/cylinder interface of advanced (low heat rejection) engines. The objective of the study, managed by the Oak Ridge National Laboratory, is to understand the basic mechanisms controlling the wear of ceramics and thereby identify means for applying ceramics effectively. Attempts to operate three different zirconias, silicon carbide, silicon nitride, and plasma-sprayed ceramic coatings without lubrication have not been successful because of excessive friction and high wear rates. Silicon carbide and silicon nitride perform well at ambient temperatures with fully formulated mineral oil lubrication, but are limited to temperatures of 500F because of the lack of suitable liquid lubricants for higher temperatures

  20. The Rings of Saturn

    Science.gov (United States)

    Cuzzi, J. N.; Filacchione, G.; Marouf, E. A.

    2018-03-01

    One could become an expert on Saturn's iconic rings pretty easily in the early 1970s, as very little was known about them beyond the distinction between the A, B, and C rings, and the Cassini Division or "gap" between rings A and B (Alexander, 1962; Bobrov, 1970). Water ice was discovered spectroscopically on the ring particle surfaces, and radar and microwave emission observations proved that the particles must be centimeters to meters in size, consisting primarily, not just superficially, of water ice (Pollack, 1975). While a 2:1 orbital resonance with Mimas had long been suspected of having something to do with the Cassini Division, computers of the time were unable to model the subtle dynamical effects that we now know to dominate ring structure. This innocent state of affairs was exploded by the Voyager 1 and 2 encounters in 1980 and 1981. Spectacular images revealed filigree structure and odd regional color variations, and exquisitely detailed radial profiles of fluctuating particle abundance were obtained from the first stellar and radio occultations, having resolution almost at the scale of single particles. Voyager-era understanding was reviewed by Cuzzi et al. (1984) and Esposito et al. (1984). While the Voyager data kept ring scientists busy for decades, planning which led to the monumentally successful NASA-ESA-ASI Cassini mission, which arrived in 2004, had been under way even before Voyager got to Saturn. A review of pre-Cassini knowledge of Saturn's Rings can be found in Orton et al. (2009). This chapter will build on recent topical and process-specific reviews that treat the gamut of ring phenomena and its underlying physics in considerable detail (Colwell et al., 2009; Cuzzi et al., 2009; Horányi et al., 2009; Schmidt et al., 2009; Esposito, 2010; Tiscareno, 2013b; Esposito, 2014). We will follow and extend the general organization of Cuzzi et al. (2010), the most recent general discussion of Saturn's rings. For brevity and the benefit of the