Turbulence Intensity Characteristics of a Magnetoliquid Seal Interface in a Liquid Environment

In a liquid environment, the turbulence intensity of the interfacial layer between the magnetic and sealing medium fluids in magnetic liquid seals directly affects the layer stability. Reducing the maximum turbulence intensity of the fluid interface layer effectively improves the stability of the magnetic fluid rotary seal. In this study, we simulated magnetic fluid sealing devices with different structures in liquid environments using the FLUENT software. The simulation results were verified through experimental analyses of the turbulence intensity at the sealing interface. The maximum turbulence intensity of the liquid interface layer increased with increasing shaft speed. At the same speed, the turbulence intensity was maximized at the shaft interface before gradually decreasing in a multistage linear pattern along the radial direction. A magnetic liquid seal with an optimized structure (OS) in the liquid environment was designed based on these results. The maximum turbulence intensity of the liquid interface layer in the OS was independent of the rotation speed and was more than 20% lower than that that in the traditional structure. These results provide a reference for designing magnetic liquid sealing devices.

Microfluidics 5: PDMS Microchannel Bonding on Glass/PDMS v2

Microfluidic chips, made of PDMS, are one-side open when fabricated. Another layer of glass, PDMS, or etc is needed. Liquid seal is provided by complete covalent bonding between layers or by external forces like threads, magnets or similar factors. This protocol describes the covalent bonding of PDMS on glass by air plasma technique.

Microfluidics 5: PDMS Microchannel Bonding on Glass/PDMS v2

Microfluidic chips, made of PDMS, are one-side open when fabricated. Another layer of glass, PDMS, or etc is needed. Liquid seal is provided by complete covalent bonding between layers or by external forces like threads, magnets or similar factors. This protocol describes the covalent bonding of PDMS on glass by air plasma technique.

Effect of turbulence intensity of fluid medium interface layer on magnetic liquid seal in liquid environment

In a liquid environment, the instability of the interface layer of the rotating fluid medium is one of the main causes for the failure of magnetic liquid seals. The turbulence intensity of the interfacial layer between the magnetic and the sealing medium fluids in magnetic liquid seals directly affects the layer stability. Reducing the maximum turbulence intensity is an effective way to improve the stability of the magnetic fluid rotating seal. In this study, we simulated magnetic fluid sealing devices with different structures in liquid environments using FLUENT software. The simulation results are verified through experimental analyses and the turbulence intensity at the sealing interface is analyzed. We simulated the magnetic circuit using Maxwell software, and compared the difference between the optimized and traditional structures. The results show that the maximum turbulence intensity of the liquid interface layer increases with the increasing shaft speed. At the same speed, the turbulence intensity is maximized at the shaft interface before gradually decreasing in a multistage linear pattern along the radial direction. The turbulence intensity at the interface of the spindle is relatively large, which seriously affects the stability of the interface. Based on these results, the optimized structure (OS) of the magnetic liquid seal in the liquid environment is designed. The maximum turbulence intensity of the liquid interface layer in the OS is more than 20% lower than that in the traditional structure (TS), and it is independent of the rotation speed. The optimized and the traditional structures have the same magnetic induction intensity distribution at the sealing clearance. The maximum magnetic induction intensity of the OS is 6.25% higher than that of the traditional one. These results provide a reference for designing magnetic liquid sealing devices.

Studied on the effect of refueling rate on fuel system refueling based on STAR-CCM+

A model of fuel system which is with ORVR is established based on STAR CCM +, to study the influence of different refueling velocity on the formation of liquid seal in refueling process. The simulation results show that the increase of refueling rate leads to the formation of liquid seal in the process of fuel flow, but it will lead to the deterioration of refueling smoothness. When the refueling rate is 15L/min, there is no liquid seal formed at the bottom of the refueling pipe, because of the small gas resistance formed in the refueling process, and when the refueling flow rate reaches 37L/min, a stable dynamic liquid seal can be formed at the bottom of the refueling pipe but the fuel accumulation at the refueling port has taken place. When the refueling flow rate reaches40L/min and 45L/min, a stable dynamic liquid seal is formed at the bottom of the refueling pipe at 4s, but until 4 seconds, fuel has been submerged in the refueling muzzle. At 10 seconds, the fuel accumulation state is the same as 5 seconds, indicating that the gun PSO had taken happened.

Study on the Liquid Seal Discharge Process in an Over-Pressurized Accident

In an over pressure accident, one or more pressurizer safety (or relief) valves will open due to the rapid pressure rise process. Once the safety (or relief) valves are open, the liquid seal will be discharged, and this will generate great discharge force to the downstream pipes. Multi-level protection is chosen using pressurizer safety (or relief) valves with different setpoint in most of Nuclear Power Plant, especially in the self-designed Generation-III Nuclear Power Plants. As the over pressure accident progresses, one or more safety (or relief) valves will be open. The downstream pipes will experience one or more times of impacts, which will influence the arrangement of the pipes. The whole discharge process is very complex, and the key influence factors are the pressure rise rate, safety (or relief) valve opening time, liquid seal temperature and volume, and the arrangement of the downstream discharge pipes. In present paper, liquid seal discharge process in an over pressure accident is studied. The pressure rise rate is so fast that three safety (or relief) valves will open one after another, which will generate three impacts on the downstream discharge pipes. It is found that for a specific design of Nuclear Power Plant, well design of the safety (or relief) valve setpoint is very important to the discharge force analysis results.

Liquid seal for compact micropiston actuation at the capillary tip

Actuators at the tip of a submillimetric catheter could facilitate in vivo interventional procedures at cellular scales by enabling tissue biopsy and manipulation or supporting active micro-optics. However, the dominance of frictional forces at this scale makes classical mechanism problematic. Here, we report the design of a microscale piston, with a maximum dimension of 150 μm, fabricated with two-photon lithography onto the tip of 140-μm-diameter capillaries. An oil drop method is used to create a seal between the piston and the cylinder that prevents any leakage below 185-mbar pressure difference while providing lubricated friction between moving parts. This piston generates forces that increase linearly with pressure up to 130 μN without breaking the liquid seal. The practical value of the design is demonstrated with its integration with a microgripper that can grasp, move, and release 50-μm microspheres. Such a mechanism opens the way to micrometer-size catheter actuation.

The Innovated “Closed Chest Drainage System” of William Smoult Playfair (1871)

During the 19th century, the addition of the water-seal system to a closed chest drain was a major turning point in the history of thoracic surgery. German physician Gotthard Bülau seems to have invented and used his own closed chest drainage device with a liquid-seal system in 1875, and published it in the year 1891. But, in 1871, British physician William Smoult Playfair seems to have thought of the subaqueous drainage and used such drainage to treat the thoracic empyema in children. The British physician stresses in his texts the effectiveness of his method of fully draining the thoracic empyemas while simultaneously preventing air from entering the pleural cavity. An appropriate honor must be attributed to Playfair, who used a subaqueous chest drainage system and appears to be the first to publish such a method.