Ringed Seals Research Articles

Analysis on Sealing Performance for a New Type of Rubber Olecranon‐Shaped Sealing Ring in Pipe Jacking Joint

To address the easy damage of rubber sealing rings for pipe joints used in China’s first rock pipe jacking project, the launch of research concerning the optimization design of rubber ring structure was decided. However, modification based on the existing production mold was required, to prevent the construction period and cost from exceeding limits. Utilizing the optimization experience, the stress and waterproof property variations of rubber ring before and after optimization during the pipe translation and deflection were initially analyzed via the ADINA software. Meanwhile, the correct orientation of the ring optimization criteria was confirmed through the field test. Next, the effects of key structural parameters on the contact length and maximum contact pressure of rubber ring were quantified, thereby obtaining the sensitivity correlations between five key parameters of ring optimization to further establish the criteria for rubber ring optimization. The findings of this study offer safe construction suggestions for pipe jacking projects.

Improvement of shaft seal performance using hydrophilic elastomer by addition of CNF

To prevent leakage of subject fluid or ingress of surrounding material at a rotating shaft, shaft seals such as oil seals or mechanical seals are commonly assembled in a lot of mechanical devices. Although these shaft seals are commercially available and replaceable, it is not always successful to be used for water sealing because they cause high friction and wear or leakage due to low viscosity and poor lubricity of water. In the previous study, a seal ring made of hydrophilic elastomer was developed so that it promotes hydrated lubrication under the boundary lubrication mode. Also, the fiber reinforcement of the hydrophilic elastomer was introduced to improve its elasticity with original material properties. In this work, partially reinforced seal rings with layered structure in addition to uniformly reinforced seal rings were developed and evaluated by sealing performance test. The results suggested that partially reinforced seal ring showed both characteristics of each single layer depending on the operational condition.

Design and simulation of horizontal large shaft diameter seal based on magnetic fluid

As high-end equipment requires a higher and higher sealing effect, sealing forms such as packing seals expose problems such as considerable wear and high heat generated by friction. Based on the theoretical analysis of the instability at the liquid-liquid interface and the pressure resistance of the seal structure, considering the rotating speed of the rotating shaft, this paper reconstructs the formula for calculating the pressure resistance value of the seal structure. On this basis, a magnetic fluid seal structure is designed for a large horizontal shaft diameter in liquid. Based on the magnetic field analysis software Maxwell, the magnetic field of the magnetic fluid seal is analyzed, and the mapping relationship between the different tooth widths of the pole teeth, the size of the permanent magnet, and the difference in the magnetic induction intensity of the seal gap is obtained. Built in the ring seal test system, the pressure test of the horizontal large shaft diameter seal structure under different rotating speeds was carried out to verify the effectiveness of the seal structure. The results have specific theoretical research significance and engineering application value for designing and applying magnetic fluid seal structures.

Underwater noise impact of a ferry route on dive patterns of transiting Baltic ringed seals

Underwater noise impact of a ferry route on dive patterns of transiting Baltic ringed seals

Analysis of the O-rings that influence the performance of RCP hydrostatic seal based on TEH coupling method

A Multi-body contacting Thermal-Elastic-Hydro Model, MTEHM has been established in this study. And which has been applied to analysis the leakage behavior of No.1 seal of the RCP hydrostatic seal. The hydro-model is based on 2D Reynolds equation and programmed by M-code. An interface program written in C has been carried out. And which is used to transit the end face pressure value from hydro-model to elastic-solid model. The FEA multi-body contacting method has been taken into the elastic-solid model. And which is used to obtain the deformation angle of seal rings. An opening force ratio has been carried out as a convergent judgment of the multi-physics iterative coupling process. The influence of position of O-rings (on the back of seal rings and relative to the hydrostatic clamp rings) has been discussed. For test and verify the MTEHM, a testing rig has been established. It can be used to simulate a high temperature high pressure seal media with a temperature range from 22°C to 100°C and a pressure range from 0.1MPa to 22MPa. At last, a comparison of pressure-leakage data from Westinghouse, Saint Alban power plant and this study has been presented. And a variance analysis has been attached.

An investigation into the thermo-elasto-hydrodynamic effect of notched mechanical seals

A 3D thermo-elasto-hydrodynamic model is developed to analyze the sealing performance of a notched mechanical seal applied in the reactor coolant pump. In the model, the generalized Reynolds equation, the energy equation coupled with notch heat balance equation, the heat conduction equations, and the deformation equations of the sealing rings are iteratively solved by the finite element method. The film pressure and temperature distribution are obtained, and the deformation of the sealing rings is revealed to study the mechanism of the notched mechanical seals. A parameterized study is conducted to analyze the sealing performance under different operating conditions. As a comparison, the sealing performance of non-notched seals is also studied. The results show that the hydrostatic effect is dominant in the load-carrying capacity of the fluid film due to the radial mechanical and thermal deformations. The notch can cool the fluid film and influence the thermal deformation of seal rings. The sealing performance is sensitive to the pressure difference, ambient temperature, and rotational speed. It is suggested to set the notches on the softer sealing rings to acquire the greater hydrodynamic effect. Compared with the non-notched, the notched end face holds a better lubrication performance, especially under lower rotational speed.

Dynamic failure analysis of static seals under pressure fluctuation in an ultrahigh-pressure water piston pump

For ultrahigh-pressure piston pumps, in the reciprocating action of the piston, the fretting between the static face seal and the mating surface occurs with the change of the pressure in the piston chamber. This phenomenon will seriously affect the service life of the seal ring and lead to the failure of the pump. However, the failure of static seals used to seal ultrahigh-pressures is usually studied from the directions of shear, stress, or rubber material. These studies cannot explain the failure phenomenon of the sealing ring found in our experiment. This paper analyzed the failure of the face seal ring in a piston pump with a maximum pressure of 120 MPa. A two-dimensional axisymmetric finite element model was established based on the Mooney-Rivlin constitutive relation of the rubber material, and the fretting conditions of the sealing ring were analyzed. Combined with the wear scars observed by the scanning electron microscope the face seal ring’s dynamic failure mechanism on the ultrahigh-pressure piston pump was determined. A better sealing scheme was proposed and verified by the duration test of the pump, which provided a basis for the design of the sealing of the ultrahigh-pressure fluid with high-frequency fluctuations.

Experimental testing on the influence of shaft rotary lip seal misalignment for a marine hydro-kinetic turbine

Tidal energy has received considerable attention over the past decade due to its predictability and high power density. The research in the tidal turbine area has concentrated primarily on the improvement of the energy conversion efficiency. In contrast, the testing of the tidal turbine’s mechanical components has received less attention. In particular, the reliable operation of rotary seals is crucial to prevent water ingress into mechanical and electrical components. This paper outlines an experimental test campaign to investigate the effect of shaft misalignment. Both instantaneous temperature and pressure measurements were recorded from two rotary seals. It was shown the temperature inside the aligned seal increased until the seal chamber pressure became equal with the inlet water pressure. The wear on the lip seal rings was examined and the difference found to be between 3.28% and 19.61%. Inspection of the seal liners, showed the presence of strong wiping effects for the misaligned seal with maximum track width differences of between 52.94% and 97.60% being noted. The misaligned seal liner experienced wider wear tracks but were not as deep as the aligned seal with differences of between 37.55% and 103.13% being recorded.

Loimologically significant pinniped helminths in Chukotka

The purpose of the researchis study of pinniped helminth fauna in Chukotka, and the analysis of the fish of the main commercial families infected with pathogens of helminthozoonoses based on modern literature.Materials and methods. The helminths were collected in autumn of 2019 from pinnipeds caught in the Mechigmenskaya Guba of the Bering Sea in the Chukotka Autonomous Okrug by the method of partial helminthological dissection per Skryabin (gastrointestinal tract). Samples were examined from 6 walruses and 26 seals (13 spotted seals and 13 ringed seals). The helminths found were fixed in 70% alcohol. The helminth species were identified at the Department of Parasitology and Veterinary and Sanitary Examination of the MVA named after K. I. Skryabin using reference literature.Results and discussion. All pinnipeds were infected with nematodes of the family Anisakidae. Mature Pseudoterranova desipiens were found in the walrus (Infection Prevalence = 16.7% with Infection Intensity = 3 specimens/animal), mature Ps. desipiens, as well as Contracoecum osculatum and Anisakis simplex larvae (IP = 30.8% with II from 5 to 57 specimens) were found in the spotted seal, and Ps. desipiens larvae and mature Ps. desipiens were found in the ringed seal (IP = 15.4% with II from 1 to 4 specimens). Thus, only Ps. desipiens were represented by mature stages (females and males), and two other species of anisakids, C. osculatum and A. simplex, were found in the seals in the larval stage.

Hip and stifle joint anatomy of the Saimaa (Pusa hispida saimensis) and Baltic ringed seals (Pusa hispida botnica).

The anatomical architecture of the hip and stifle joints of the Saimaa ringed seal was determined by dissection to be similar to that of the Baltic ringed seal. There was no ligament of the femoral head in the hip joint. The lateral side of the stifle joint lacked a collateral ligament but the collateral ligament on the medial side was of considerable size. The medial meniscus was larger and thicker than the lateral meniscus. The asymmetrical anatomical architecture allows for much lateral movement during aquatic motion, but it is poorly adapted to terrestrial locomotion.

Ringed seal (Pusa hispida) breeding habitat on the landfast ice in northwest Alaska during spring 1983 and 1984.

There has been significant sea ice loss associated with climate change in the Pacific Arctic, with unquantified impacts to the habitat of ice-obligate marine mammals such as ringed seals (Pusa hispida). Ringed seals maintain breathing holes and excavate subnivean lairs on sea ice to provide protection from weather and predators during birthing, nursing, and resting. However, there is limited baseline information on the snow and ice habitat, distribution, density, and configuration of ringed seal structures (breathing holes, simple haul-out lairs, and pup lairs) in Alaska. Here, we describe historic field records from two regions of the eastern Chukchi Sea (Kotzebue Sound and Ledyard Bay) collected during spring 1983 and 1984 to quantify baseline ringed seal breeding habitat and map the distribution of ringed seal structures using modern geospatial tools. Of 490 structures located on pre-established study grids by trained dogs, 29% were pup lairs (25% in Kotzebue Sound and 33% in Ledyard Bay). Grids in Ledyard Bay had greater overall density of seal structures than those in Kotzebue Sound (8.6 structures/km2 and 7.1 structures/km2), but structures were larger in Kotzebue Sound. Pup lairs were located in closer proximity to other structures and characterized by deeper snow and greater ice deformation than haul-out lairs or simple breathing holes. At pup lairs, snow depths averaged 74.9 cm (range 37-132 cm), with ice relief nearby averaging 76 cm (range 31-183 cm), and ice deformation 29.9% (range 5-80%). We compare our results to similar studies conducted in other geographic regions and discuss our findings in the context of recent declines in extent and duration of seasonal cover of landfast sea ice and snow deposition on sea ice. Ultimately, additional research is needed to understand the effects of recent environmental changes on ringed seals, but our study establishes a baseline upon which future research can measure pup habitat in northwest Alaska.

Predictions of the thermo elastic deformation of dry gas seal rings in the hydrodynamic lubrication regime

Dry gas seals represent a significant advancement in turbo machinery due to their ability to handle high pressures and speeds without the use of external sealing fluids, such as oil or water, thus reducing contamination and increasing reliability. Despite their widespread use, internal working mechanisms are not fully understood to date, in particular regarding fluid film thickness prediction, which is an essential component of the seal design. The axial deflection of the rotating and stationary rings in a dry gas seal affects the development of the fluid film formed between the ring faces of the seal, influencing the performance of the seal during its operation, as well as leakage of the seal when it is at rest. The hydrodynamic and hydrostatic pressure fields of the fluid film, together with temperature gradients in the rings, induce axial deflection of these components. This in turn modifies the pressure field developed in the film. This paper focuses on establishing a methodology to couple the deformation field and the dynamic behavior of the fluid film (pressure and temperature fields) through numerical computations. Analytical relationships are employed to obtain the thermo-elastic deflection of the seal rings in the axial direction and this distortion is used in the numerical methodology to accelerate the prediction of the seal behavior. The coupled seal ring-fluid film dynamic system with 11° and 15° spiral angle is stable because the axial deflection calculated from numerical analysis produces a converging radial taper in the direction of the flow (producing a net opening force). An important result of this work is that the predicted magnitude of the axial deflection (as a result of pressure and temperature effects) under thermal and pressure loads on the stationary and rotating rings is smaller but of the same order of magnitude as the fluid film thickness.

Derivation of Ringed Seal (Phoca hispida) Induced Multipotent Stem Cells.

Induced pluripotent stem (iPS) cells have been produced just for a few species among order Carnivora: snow leopard, Bengal tiger, serval, jaguar, cat, dog, ferret, and American mink. We applied the iPS cell derivation protocol to the ringed seal (Phoca hispida) fibroblasts. The resulting cell line had the expression of pluripotency marker gene Rex1. Differentiation in embryoid body-like structures allowed us to register expression of AFP, endoderm marker, and Cdx2, trophectoderm marker, but not neuronal (ectoderm) markers. The cells readily differentiated into adipocytes and osteocytes, mesoderm cell types of origin. Transcriptome analysis allowed us to conclude that the cell line does not resemble human pluripotent cells, and, therefore, most probably is not pluripotent. Thus, we produced ringed seal multipotent stem cell line capable of differentiation into adipocytes and osteocytes.

Influence of Floating Ring Seal Working Condition Parameters on the Dynamic Characteristics of Transient Gas Film

The high requirements for sealing performance in high-speed rotating machinery has led to the design of floating seal with annular spiral groove that offer the advantages of low leakage and extended stability. However, efforts to model the dynamic performance of these floating seal have suffered from the great complexity of the flow field. The present work addresses this issue by establishing a transient Reynolds formulation of a floating seal with annular spiral groove in a rotating coordinate system based on the small perturbation method. In addition, the influence of radial eccentricity and film thickness on the solution divergence and calculation accuracy is calculated. The dynamic stiffness and dynamic damping matrixes are built. Then the variation rules of the dynamic stiffness and damping coefficient of the gas film with structure and working conditions are investigated in detail. The results show that the floating ring seal is more suitable for the service conditions of small film thickness, low pressure, high speed and large eccentricity. Accordingly, the results obtained lay a theoretical foundation for evaluating real-world applications of floating ring seal.

회전 억제용 플로팅 링 실을 사용한 7톤급 터보펌프의 실매질 시험 고주파 신호 분석

A floating ring seal in turbopump is frequently employed to control the leakage through the secondary flow passage. Depending on its shape and operating conditions of the turbopump, the floating ring seal can have excursive motions and such motions induce strong pressure fluctuations, wear, and frictional oxidation due to rubbing between impeller and pump casing. It affects pump inlet and outlet pressures resulting in unstable operation or, in severe cases, failure of the turbopump. In this study, high-frequency signals from an accelerometer and pressure fluctuation sensors installed on the LOX pump were measured. Frequency spectrums and Root Mean Square (RMS) values were calculated in the real-propellant test for 7-tonf turbopump using two types of floating ring seal, the normal floating ring seal and the anti-rotating floating ring seal. The specific instability frequencies were investigated, and visual inspection was conducted to estimate the structural and hydrodynamic stabilities for 7-tonf turbopump. In consequence, the anti-rotating floating ring seal is able to effectively reduce the unstable pressure fluctuations and the wear compared to the normal floating ring seal.

Effects of reinforcements on the hardness of composite seal rings

Composite seal rings are alternate high-performance materials for supplying to engines and compressors in several industries. Polytetrafluoroethylene (PTFE) and Polyetheretherketone (PEEK) seals reinforced by carbon powder and glass fibers were investigated. The seal specimens were heated at 150–200 °C for a duration of 24 h. The hardness and microstructure of specimens were observed after the test. Taguchi technique was used for design of experiment to analyzed the parameters that affected to the seal hardness. The hardness of all samples decreased when increasing temperature, and the hardness of PTFE and PEEK with carbon powder slightly increased after heating at higher temperature. The PEEK with 30% carbon showed the highest hardness compared to the others at temperature of 150 and 200 °C. The carbon reinforcements promoted increasing hardness of the composite seal rings. Besides, the reinforcements showed a good distribution in the composite matrix which was nearly the same as the microstructure of the compressor seal ring used in industrial parts.

Comparative examination of pinniped craniofacial musculature and its role in aquatic feeding.

Secondarily aquatic tetrapods have many unique morphologic adaptations for life underwater compared with their terrestrial counterparts. A key innovation during the land‐to‐water transition was feeding. Pinnipeds, a clade of air‐breathing marine carnivorans that include seals, sea lions, and walruses, have evolved multiple strategies for aquatic feeding (e.g., biting, suction feeding). Numerous studies have examined the pinniped skull and dental specializations for underwater feeding. However, data on the pinniped craniofacial musculoskeletal system and its role in aquatic feeding are rare. Therefore, the objectives of this study were to conduct a comparative analysis of pinniped craniofacial musculature and examine the function of the craniofacial musculature in facilitating different aquatic feeding strategies. We performed anatomic dissections of 35 specimens across six pinniped species. We describe 32 pinniped craniofacial muscles—including facial expression, mastication, tongue, hyoid, and soft palate muscles. Pinnipeds broadly conform to mammalian patterns of craniofacial muscle morphology. Pinnipeds also exhibit unique musculoskeletal morphologies—in muscle position, attachments, and size—that likely represent adaptations for different aquatic feeding strategies. Suction feeding specialists (bearded and northern elephant seals) have a significantly larger masseter than biters. Further, northern elephant seals have large and unique tongue and hyoid muscle morphologies compared with other pinniped species. These morphologic changes likely help generate and withstand suction pressures necessary for drawing water and prey into the mouth. In contrast, biting taxa (California sea lions, harbor, ringed, and Weddell seals) do not exhibit consistent craniofacial musculoskeletal adaptations that differentiate them from suction feeders. Generally, we discover that all pinnipeds have well‐developed and robust craniofacial musculature. Pinniped head musculature plays an important role in facilitating different aquatic feeding strategies. Together with behavioral and kinematic studies, our data suggest that pinnipeds’ robust facial morphology allows animals to switch feeding strategies depending on the environmental context—a critical skill in a heterogeneous and rapidly changing underwater habitat.

Inuit and Local Knowledge on the Marine Ecosystem in Ilulissat Icefjord, Greenland

The interview survey conducted in Ilulissat, Ilimanaq, and Qasigiannguit in Greenland during March–April 2019 showed that the local fishers are changing fishing strategies and adapting to a changing environment caused by climate change. The main fjord of Ilulissat Icefjord is usually filled with icebergs year-round, making it impossible to navigate. Currently, there are more ice clearing events in Ilulissat Icefjord during the winter than previously. The traditional pattern of going fishing using dogsled is changing and fishing from boats occurs, whenever the main fjord clears of ice. The poorer sea ice conditions in the southern branch of the fjord system, combined with the fact that it is increasingly challenging to reach fishing sites, have resulted in fishers from Qasigiannguit not going to the Icefjord as much as they used to. Ilulissat Icefjord is by any means considered important fishing and hunting ground by locals, as both Greenland halibut and ringed seals are known to be of larger size inside the fjord system, when compared to those caught in Disco Bay. The locals use Ilulissat Icefjord during a limited period of the year, and the fjord is therefore said to be protected from overexploitation. They observe the immediate effects of climate change from changes in the ice conditions, a change in the fjord's accessibility, and the occurrence of Atlantic cod, which were not present in the fjord system in such numbers before.

Effects of the inclination angles of DLC end face micro-texture on the tribological properties of dry gas seal rings

To improve the tribological performance of the seal rings in the dry gas seal, the elliptical micro-textures with different inclination angles (0°, 45°, 90°, 135°) were processed on the end face of SiC static rings by nanosecond laser. Diamond-like carbon (DLC) films were then deposited on the micro-textured end face. Under dry friction condition, the end-face friction and wear test was conducted to simulate the actual working state of the dry gas seal at start-up phase. The effects of micro-texture inclination angles and DLC phase change on the tribological properties of seal rings were investigated. The possible friction reduction mechanism was analyzed. The results show that compared with the smooth surface, the elliptical micro-texture can effectively improve the tribological properties of DLC films. At the same time, the inclination angle of the elliptical micro-texture has a remarkable influence on the tribological properties. When the micro-texture inclination angle is 90°, the static ring sample has the best friction reduction and wear resistance performance. Compared with the untextured sample, the average friction coefficient is reduced by 46.15%. The wear reduction characteristics of the textured end face are mainly contributed to the capturing effect of the texture on wear particles.

ANTIBODIES AGAINST INFLUENZA VIRUS TYPES A AND B IN CANADIAN SEALS.

Influenza viruses have been reported from marine mammals worldwide, particularly in pinnipeds, and have caused mass mortalities of seals in North America and Europe. Because influenza viruses in marine mammals can be zoonotic, our objective was to examine Canadian phocids for exposure to influenza A and B viruses in order to understand health risks to wild populations as well as to humans who consume or handle these animals. Blood was collected from 394 seals in eastern Canada from 1994 to 2005. Sera were screened for exposure to influenza viruses in three resident species of seals: harbour, Phoca vitulina (n=66); grey, Halichoerus grypus (n=82); ringed, Phoca hispida (n=2); and two migrant species: harp, Pagophilus groenlandica (n=206) and hooded, Cystophora cristata (n=38). Included were samples from captive grey (n=1) and harbour seals (n=8) at two aquaria. Sera were prescreened using indirect enzyme-linked immunosorbent assay (ELISA), and antibodies against influenza A virus were confirmed using a commercial competitive ELISA (IDEXX Europe B.V.). A subset of influenza A virus positive sera was used to determine common virus subtypes recognized by sera using reference strains. All positive sera in the indirect ELISA reacted with influenza A virus subtypes H3, H4, and H10 using a hemagglutination inhibition assay. Sera from harbour, grey, harp, and hooded seals had antibodies against influenza A and influenza B viruses (some cross-reactivity occurred). Overall, 33% (128/385) of wild seals were seropositive to influenza viruses, with the highest seroprevalence in harp (42%) followed by harbour (33%), grey (23%), and hooded (11%) seals. Antibodies were detected in both sexes and most age classes of wild seals. Two of eight captive harbour seals were seropositive to influenza B virus and four had cross-reactions to influenza A and B viruses. This study reports antibodies against influenza A and B viruses in four seal species from the same geographic area in eastern Canada.