scholarly journals New Designs of Magnetic Fluid Seals for Reciprocating Motion

2021 ◽  
Vol 28 (4) ◽  
pp. 151-159
Author(s):  
Leszek Matuszewski ◽  
Piotr Bela
Keyword(s):  
Magnetic Fluid ◽  
Operating Conditions ◽  
Linear Motion ◽  
Practical Application ◽  
Reciprocating Motion ◽  
Seal Failure ◽  
Hydraulic Cylinders ◽  
Sealing Mechanism ◽  
Carry Over ◽  
Sealing Gap

Abstract The operating conditions of magnetic fluid seals during reciprocating motion are so different from those observed in rotating motion that the use of their conventional structures for reciprocating motion seals yields no good results. The analysis of the sealing mechanism of magnetic fluid seals in reciprocating motion shows that the operation of these seals is affected by the carry-over phenomenon and magnetic fluid film deformation in the sealing gap, which depends on the velocity of the reciprocating motion. The reduced amount of magnetic fluid in the sealing gap caused by the reciprocating motion of the shaft is the main reason for seal failures. The paper presents a short characterisation of magnetic fluid sealing technology, the principle of sealing, the operation of the magnetic fluid and the seal failure mechanism in linear motion of the shaft. Moreover, some new structural designs of hybrid seals, being combinations of typical hydraulic seals with magnetic fluid seals for reciprocating motion, and some examples of magnetic fluid sealing structures for hydraulic cylinders and piston compressors which have practical application values are presented.

Experimental Inverstigations On the Pressure Fluctuations in the Sealing Gap of Dry Gas Seals with Embedded Pressure Sensors

2021 ◽  
Author(s):  
Jingjing Luo ◽  
Dieter Brillert
Keyword(s):  
High Speed ◽  
Gas Flow ◽  
Static Pressure ◽  
Pressure Sensors ◽  
Operating Conditions ◽  
Test Facility ◽  
Experimental Investigations ◽  
Mechanical Seals ◽  
Process Gas ◽  
Sealing Gap

Abstract Dry gas lubricated non-contacting mechanical seals (DGS), most commonly found in centrifugal compressors, prevent the process gas flow into the atmosphere. Especially when high speed is combined with high pressure, DGS is the preferred choice over other sealing alternatives. In order to investigate the flow field in the sealing gap and to facilitate the numerical prediction of the seal performance, a dedicated test facility is developed to carry out the measurement of key parameters in the gas film. Gas in the sealing film varies according to the seal inlet pressure, and the thickness of gas film depends on this fluctuated pressure. In this paper, the test facility, measurement methods and the first results of static pressure measurements in the sealing gap of the DGS obtained in the described test facility are presented. An industry DGS with three-dimensional grooves on the surface of the rotating ring, where experimental investigations take place, is used. The static pressure in the gas film is measured, up to 20 bar and 8,100 rpm, by several high frequency ultraminiature pressure transducers embedded into the stationary ring. The experimental results are discussed and compared with the numerical model programmed in MATLAB, the characteristic and magnitude of which have a good agreement with the numerical simulations. It suggests the feasibility of measuring pressure profiles of the standard industry DGS under pressurized dynamic operating conditions without altering the key components of the seal and thereby affecting the seal performance.

scholarly journals THE MAIN TEST RESULTS OF THE MI-2MSB HELICOPTER EQUIPPED WITH THE EXPERIMENTAL SYSTEM OF SMALL ARMS AND SERIES-PRODUCED SYSTEM OF UNGUIDED MISSILE ARMAMENT

2020 ◽  
pp. 26-32
Author(s):  
A. Berezniak ◽  
Т. Dudnik ◽  
O. Zakutko
Keyword(s):  
Experimental System ◽  
Operating Conditions ◽  
Test Results ◽  
Practical Application ◽  
Flight Crew ◽  
Small Arms ◽  
Functional Capabilities ◽  
Actual Volume ◽  
Type C ◽  
Missile System

The summarized results of special tests of the Mi-2MSB helicopter equipped with the experimental system of 12,7 mm small arms (as a part with series-produced machine guns NSVT-12,7) and the serial system of unguided missile armament (NAR type C-8) are presented. The actual volume of assessments of inspections and work performed during the tests is given. According to the results of processing the test materials, it was determined that the tactical range of the Mi-2MSB helicopter with the installed weapons system and boxes for collecting spent units (in the design provided for testing) at a takeoff mass of 3700 kg, at an altitude of not more than 300 m during combat mission in the area of the target for 5 minutes and the remaining fuel on the landing of 100 liters is (not less): version of combat equipment 2 × B8V8MSB (payload - 16 NAR) - 190 km; version of combat equipment 2 × NSVT-12.7 (payload - 600 rounds) - 200 km; version of combat equipment 2 × B8V8MSB + 2 × NSVT-12.7 (payload - 16 NAR and 600 rounds) - 155 The results of special tests practically showed that the Mi-2MSB helicopter, equipped with an aviation weapon system, in addition to the functional tasks defined for the basic Mi-2MSB helicopter, is able to provide: training and maintenance of skills for flight crew in the practical application of unguided aviation weapons and gun armaments in all types of maneuvering, defined by the tactics of army aviation; accomplishment of certain tasks on air support of columns of troops on the march and fire missions on destruction of enemy manpower, single unarmored and lightly armored targets such as car, armored personnel carrier, infantry fighting vehicle, boat, The main combat and functional capabilities in the actual operating conditions confirmed by the results of special tests as well as their validation of specified requirements make it possible (after eliminating the shortcomings identified in the test), to allow operation of Mi-2MSB helicopter in the entire operating range of heights and speeds equipped with aircraft weapons as part of the unguided missile system (NAR type C-8) and small arms system (as part of the series-produced machine guns NSVT-12.7)).

scholarly journals Development of a Hydraulic Parallel Link Force Display -Improvement of Manipulability Using a Disturbance Observer and its Application to a Master-slave System-

2003 ◽  
Vol 15 (4) ◽  
pp. 391-397 ◽  
Author(s):  
Shigeki Kudomi ◽  
◽  
Hironao Yamada ◽  
Takayoshi Muto ◽  
Keyword(s):  
Dynamic Performance ◽  
Load Force ◽  
Slave System ◽  
Disturbance Compensation ◽  
Practical Application ◽  
Hydraulic Cylinders ◽  
Six Dof ◽  
Parallel Link ◽  
Hydraulic Manipulator ◽  
Master Slave System

We previously developed a six-DOF parallel link force display that is actuated by six hydraulic cylinders. The manipulability of the display, however, was insufficient at first, because the dynamic performance of each cylinder was not necessarily the same as that of the others. To overcome this problem, in the present study we have applied disturbance compensation to improve manipulability. To demonstrate a practical application of this force display, we have also constituted a master-slave system in which the display is adopted as the master, and the same type of hydraulic manipulator is adopted as the slave. An operator manipulated the system so that the slave touched a flexible object serving as a load. Our experiments confirmed that the system was controlled with relatively good dynamic performance, and that the operator was able to feel the load force sensitively through the force display.

High-loaded sub-6 nm Pt1Co1 intermetallic compounds with high-efficient performance expression in PEMFCs

2021 ◽  
Author(s):  
Qingqing Cheng ◽  
Shuai Yang ◽  
Cehuang Fu ◽  
Liang-Liang Zou ◽  
Zhi-Qing Zou ◽  
...  
Keyword(s):  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Intermetallic Compounds ◽  
High Performance ◽  
Reduction Reaction ◽  
Operating Conditions ◽  
Practical Application ◽  
Efficient Performance ◽  
High Efficient ◽  
High Metal

High-loaded oxygen reduction reaction (ORR) Pt intermetallic compounds with high performance expression under PEMFC operating conditions are prerequisite for practical application. Nevertheless, high metal-loading would lead to the severe agglomeration...

Physically Motivated Simulation of Dynamic Hydraulic Seals

2019 ◽  
Author(s):  
Julian Angerhausen ◽  
Hubertus Murrenhoff ◽  
Bo N. J. Persson ◽  
Katharina Schmitz
Keyword(s):  
Total Solid ◽  
Qualitative Comparison ◽  
Theoretical Understanding ◽  
Detailed Understanding ◽  
Solid Friction ◽  
Hydraulic Cylinders ◽  
Machine Elements ◽  
Ring Seal ◽  
Sealing Mechanism ◽  
Oscillating Motion

Abstract Seals are crucial machine elements, for example in hydraulic cylinders. However, especially in regard to dynamic seals, the theoretical understanding of the sealing mechanism is still insufficient. A physically motivated simulation can help to gain a more detailed understanding. In this contribution a elastohydrodynamic (EHD) seal simulation is presented. It is directly implemented in the commercial Software ABAQUS. The fluid film is considered by implementing the Reynolds equation. For a physically motivated simulation Persson’s theory of contact mechanics and rubber friction is used to calculate the solid contribution to the total friction of a hydraulic seal. Simulations for an oscillating motion of a cylinder rod, sealed by an O-ring seal, are carried out for different velocities and pressures. A qualitative comparison between measurement and simulation is provided. Hysteresis effects and the contributions from both, adhesive and viscoelastic friction to the total solid friction are investigated. The physical origin of these effects is discussed in order to provide a detailed understanding of the dynamic sealing mechanism.

scholarly journals Activated persulfate by iron-based materials used for refractory organics degradation: a review

2020 ◽  
Vol 81 (5) ◽  
pp. 853-875 ◽  
Author(s):  
Yanjiao Gao ◽  
Pascale Champagne ◽  
David Blair ◽  
Ouwen He ◽  
Tiehong Song
Keyword(s):  
Transition Metals ◽  
Advanced Oxidation Processes ◽  
Ferric Iron ◽  
Operating Conditions ◽  
Zero Valent Iron ◽  
Practical Application ◽  
Treatment Research ◽  
Iron Based ◽  
Materials Used ◽  
Refractory Organics

Abstract Recently, the advanced oxidation processes (AOPs) based on sulfate radicals (SRs) for organics degradation have become the focus of water treatment research as the oxidation ability of SRs are higher than that of hydroxyl radicals (HRs). Since the AOP-SRs can effectively mineralize organics into carbon dioxide and water under the optimized operating conditions, they are used in the degradation of refractory organics such as dyes, pesticides, pharmaceuticals, and industrial additives. SRs can be produced by activating persulfate (PS) with ultraviolet, heat, ultrasound, microwave, transition metals, and carbon. The activation of PS in iron-based transition metals is widely studied because iron is an environmentally friendly and inexpensive material. This article reviews the mechanism and application of several iron-based materials, including ferrous iron (Fe2+), ferric iron (Fe3+), zero-valent iron (Fe0), nano-sized zero-valent iron (nFe0), materials-supported nFe0, and iron-containing compounds for PS activation to degrade refractory organics. In addition, the current challenges and perspectives of the practical application of PS activated by iron-based systems in wastewater treatment are analyzed and prospected.

scholarly journals The simulation model of the grapple loader operation

2019 ◽  
Vol 252 ◽  
pp. 05021
Author(s):  
Karol Tucki ◽  
Anna Bączyk ◽  
Remigiusz Mruk ◽  
Izabela Wielewska ◽  
Piotr Radziszewski
Keyword(s):  
Simulation Model ◽  
Shock Absorber ◽  
Operating Conditions ◽  
Real Object ◽  
Slight Reduction ◽  
The Real ◽  
Additional Load ◽  
Hydraulic Cylinders ◽  
Matlab Package

The main objective of the study was to develop a simulation model for the operation of the T-214 CYKLOP grapple loader using the MATLAB package. The created model allowed assessment of the behaviour of the real object in the operating conditions under variable loads and in the system overload. The simulation of the boom operation was carried out in four combinations: (1) at power take-off speed = 1000 rpm without load and (2) at 1000 kg load, (4) at power take-off speed = 540 rpm without load and (4) at 1000 kg load. The results show that the system works properly. The correct functioning of the system is evidenced by the fact that changes in force and acceleration occur on both pistons when only one of the cylinders is operating (the cylinder at rest acts as a shock absorber for the forces resulting from the inertia of the arms and the load). Apart from the increased forces on the pistons of the hydraulic cylinders, the additional load resulted in a slight reduction in acceleration values and an increase in the time needed to change the arm tilt angles.

The Comparison of Magnetic Leakage of Different Teeth Structures in Magnetic Fluid Seal

2011 ◽  
Vol 197-198 ◽  
pp. 314-317 ◽  
Author(s):  
Fei Fei Xing ◽  
De Cai Li ◽  
Wen Ming Yang ◽  
Xiao Long Yang
Keyword(s):  
Magnetic Field ◽  
Finite Element Method ◽  
Finite Element ◽  
Theoretical Model ◽  
Field Distribution ◽  
Magnetic Fluid ◽  
Magnetic Field Distribution ◽  
Two Sides ◽  
The Magnetic Field ◽  
Sealing Gap

Based on the theoretical model, magnetic field distribution of rectangular teeth, two-sides dilated shape and one-side dilated shape teeth structure with common other conditions were calculated using finite element method when the sealing gap was 0.1mm and 0.12mm. The comparison of their results with the same sealing gap showed that rectangular teeth structure had the highest magnetic leakage. Moreover, the magnetic field distribution of sealing structures with rectangular stages on both the shaft and pole pieces under the same design and sealing gap were also calculated using the same method, whose result was compared with rectangular stages on pole pieces only. The comparison showed that the former did not have higher pressure capability obviously but led to higher magnetic leakage.

scholarly journals The application of magnetic fluids in sealing nodes designed for operation in difficult conditions and in machines used in sea environment

2008 ◽  
Vol 15 (3) ◽  
pp. 49-58 ◽  
Author(s):  
Leszek Matuszewski ◽  
Zbigniew Szydło
Keyword(s):  
Magnetic Fluid ◽  
Sea Water ◽  
Water Environment ◽  
Colloidal Suspensions ◽  
Magnetic Fluids ◽  
Operating Conditions ◽  
Experimental Investigations ◽  
Design Activities ◽  
Pressure Water ◽  
Working Out

The application of magnetic fluids in sealing nodes designed for operation in difficult conditions and in machines used in sea environment Presented in article MF seals are being researched for sea technology purposes due to their excellent tightness and low resistance of motion. These features are most valuable for ring propellers and ship's main propeller shaft. There are more reasons why technologists payf significant attention for various MF seals applications in their difficult operating conditions. For instance, an advanced pumping systems are designed with contactless (screw or centrifugal) fluid seal used as the first stage seal and then the MF seal as the main seal. Further parts of the article contain discuss of the properties of magnetic fluids in the construction of MF seals. Sample of the few systems of magnetic fluid seals are presented, which have been researched lately in our laboratory including sea conditions. The magnetic fluids used in our seals are colloidal suspensions of magnetic nanoparticles. Undertaken earlier various systems selection for sea-water purposes forced us to focus on double sealing systems, in which the MF seal is used as the second seal following a conventional system especially adapted to co-operation with MF systems. This solution successfully limits direct contact of the sealed liquid with the magnetic fluid, and the entire sealing construction secures absolute tightness of the system. Using this solution we also can reduce costs by elements high accuracy avoidance. Research and design activities are carried out in the AGH Laboratory of Seals and Magnetic Fluid Applications together with Deep Water Department of Technical University of Gdansk over the use of magnetic fluid seals in sea water environment. These activities are oriented on working out MF seals able to work effectively in machines in which low-pressure water flow takes place. The objects of experimental investigations are seals having two different nominal diameters: 50 mm and 220 mm and two research rigs of different construction had to be built up. Works are scheduled to be continued.

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