Centrifugal pumps are used for different applications that include pressure boosting, wastewater, water supply, heating and cooling distribution and other industrial processes. This paper presents theoretical and experimental investigations of mechanical vibrations of a centrifugal pump. The flow in this pump, which induces pressure pulsations and mechanical vibrations, have been monitored. Vibration measurements and data collection (overall vibrations levels and frequency spectrum) were extracted from the system. In addition, one of the methods used to study vibration amplitudes for this pump is forced response analysis. To study and analyze the pump system, the finite element analysis software (ANSYS) was applied. Depending on the analysis performed and investigations outcomes, the system natural frequency coincides with the vane-pass frequency (VPF) hazardously. To attenuate the system’s vibration, a vibration control element was used. The vibration levels were reduced by a factor of 2 for a tuned element as obtained from a forced harmonic response analysis of the pump system with absorber. It is shown that the inserted element allows the centrifugal pump to work in a safe operating range without any interference with its operation.
In this article, strategies and writing tricks (the trick of “defamiliarization”, imagery) which in Nabokov’s short story A Guide to Berlin serve to design the image of the city and simultaneously to explore the world of values (axiological map of Berlin/Eden) are being interpreted. The author of this article proves that the semantics of the title guide is connected with the strategy of transition from empirical observation and one “fragment of space” to expression of a situation in which the subject of speech has found himself. Moreover, it is shown that the subjectivity of the observer, his way of experiencing the world and his creative sensitivity seem crucial in the story, because he evaluates the surrounding reality and in the “act of individual creativity” builds upon it yet another space – an unusual, transformed one, close to the emigrant/the author of the guidebook. Attention is also paid to the differentiation of two ways of perceiving the world and two types of consciousness: the artist’s/narrator’s and his listener’s (“average consciousness”).
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