Operational diagnostics of propulsion system in modern vessels

This article presents an analysis of vibration measurements of a ship’s Voith Schneider Propeller (VSP) system across the full range of the propulsion engine’s load. Determining the vibration parameters serves as a form of operational diagnostics for the structural components of this modern propulsion system. This form of diagnostics, based on the analysis of vibration accelerations in three directions relative to the ship’s axis as a carrier of information about potential malfunctions and damage, has not yet been given much attention in the literature. The limited number of descriptions and the lack of established vibration signatures for specific VSP malfunctions prompted an examination of the capabilities and benefits of using vibroacoustic methods to analyze the technical condition of a modern vessel’s propulsion system. As part of the research, vibration signals were measured and recorded during sea trials on two propulsion units simultaneously across all possible load ranges. Analysis of selected parameters revealed that the propulsion system under examination experiences load levels that, for the propellers in question, should be kept as brief as possible due to their destructive effects, manifested by exceeding permissible acceleration values. The recorded and processed acceleration signals in three directions X (L), Y (H) and Z (V) provide a picture of the exceedances of the permissible operating levels described in standards and the manufacturer’s documentation. Particular attention should be paid to the vibration velocity level in the measurement axis, the Z-direction (V), which shows the greatest variation compared to the other measurement directions. In this measurement direction, at a minimum propeller speed of 32 rpm, play in the drive system can be detected (presence of amplitude peaks), and at a maximum propeller speed of 99 rpm, the technical condition of the propeller can be assessed.