Analysis on the escape phenomenon of oil mist from turbine lower guide bearing based on VOF model

To analyze the cause and mechanism of oil mist escaping from the lower guide bearing during the operation of a turbine, the oil-gas mixture in the lower guide bearing was numerically simulated by using the VOF two-phase flow model and the SST turbulence model. The influences of different sealing clearances and speeds on the flow field and the oil-gas distribution in the oil tank were studied, and the escaping characteristics of oil mist were analyzed. The results show that increasing the clearance of the labyrinth seal will reduce the pressure difference between the inside and outside of the oil tank and reduce the driving force for the escape of the oil mist. However, increasing the clearance will increase the turbulence of the flow field, the number and volume of bubbles in the lubricating oil, which will lead to the uneven distribution of oil and gas and reduce the motion stability of the lower guide bearing. The change of speed will affect the normal use of the shaft-collar pump. High speed will aggravate the generation of bubbles in the oil tank and increase the possibility of cavitation in the lower guide bearing structure. In engineering practices, it is necessary to comprehensively consider factors such as oil mist escape phenomenon, economic benefits, process manufacturing and assembly, and adopt the lower guide bearing structure with a suitable labyrinth seal clearance.

A Comparative Study on Covid-19 Corona Virus Variants: Alpha, Beta, Gamma, Delta: Review Paper

Here in this review paper we basically discuss about the two covid-19 originate hypothesis, one is zoonotic spill-over hypothesis and another is lab leak hypothesis. This lab leak hypothesis recently on news due to substantial evidence found by USA. There are other lab leak phenomenon happen in past like 1977 Russian flu, most critics believe in that time it was also a lab escape phenomenon. Our review paper is also focused on various covid variants, till now and there comparative study. Here in this paper, we attempt to find cause of the COVID origination, and also represent a comparative study of various SARS-COV2 variants. We also discussed how it seems in near future whether pandemic will end soon or we have to adopt to live with the virus? Keywords: Zoonotic Spillover hypothesis, Lab leak hypothesis, Alpha variant, Beta variant, Gamma variant, Delta variant, comparative study, pandemic, Covid-19, SARS-COV-2, Wuhan Institute of Virology, Wuhan Sea food market

Neurosymptomatic cerebrospinal fluid escape in HIV-2: a case report

Cerebrospinal fluid (CSF) escape phenomenon is widely studied and documented in HIV-1. However, hardly anything is known about progressive neurologic disease in otherwise well-controlled HIV-2 infection. We present a case of neurosymptomatic CSF escape in HIV-2 infection from India.

Chaotic Vibrations in Multi-Mass Discrete-Continuous Systems Torsionally Deformed with Local Nonlinearities

The paper deals with nonlinear vibrations in discrete-continuous mechanical systems consisting of rigid bodies connected by shafts torsionally deformed with local nonlinearities having hard or soft characteristics. The systems are loaded by an external moment harmonically changing in time. In the study the wave approach is used. Numerical results are presented for three-mass systems. In the study of regular vibrations in the case of a hard characteristic amplitude jumps are observed while in the case of a soft characteristic an escape phenomenon is observed. Irregular vibrations, including chaotic motions, are found for selected parameters of the systems.