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Abstract: The article makes an analysis of the experimental results regarding the noises and vibrations that appear in the operation of a centrifugal pump, both on the pump and the electric drive motor, as well as on the elements of the installation. Noises and vibrations have both mechanical and hydraulic causes, in close connection with the flow rate of fluid or with the occurrence of the cavitation phenomenon. The maximum values of the noises and vibrations are tracking, their compliance with the limits of the specific standards is verified, and in case of exceeding the values, remedial solutions are proposed. Monitoring the operation of hydraulic machines in installations has the purpose of a correct operation, but also of a preventive maintenance.
Keywords: Vibrations, noises, centrifugal pump, cavitation, maintenance
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1.Introduction
The appearance of vibrations in hydraulic machines is due to mechanical causes (imperfections in bearings, bearings, eccentricities, friction, etc.) and hydraulic (detachment of the boundary layer on the blades, cavitation operation, imbalance of hydraulic forces, etc.). Vibrations and noises emitted into the atmosphere by machines and installations consume additional energy and have a detrimental influence on the service life of this equipment. Vibrations and noises also have an unfavorable effect on human health.
Vibration analysis is important for pump fault detection and predictive maintenance and was studied by D. Jung in [1], D. Siano in [2] and others. Vibration and cavitation in pumps are directly related and have been previously studied in [3-8].
Ahmed Ramadhan Al-Obaidi in [3] says that the hydraulic and mechanical sources of vibration in centrifugal pumps occur as a result from several problems: flow distribution, high velocity, interaction between the impeller and the volute through the rotation of the impeller in the pump particularly at volute tongue region.
Hydraulic sources of vibration in centrifugal pumps include blades passing forces, hydraulic imbalance, recirculation flow, cavitation, system instabilities, or water hammer in installation pipes [4]. The pumping installation includes the centrifugal pump, the electrical motor and its piping system with pipes, elbows, fittings, and valves. J. Tuzson in [5] says that "even through regular operation conditions, various kinds of physical processes create vibration such as hydraulic interaction with the piping system, improper installation or maintenance, application for the...