ISO 22098:2020 pdf download

ISO 22098:2020 pdf download.Ships and marine technology — Full-scale test method for propeller cavitation observation and hull pressure measurement
1 Scope
This document specifies a full-scale test method for propeller cavitation observation and hull pressure measurement. The objective of the test is to investigate the propeller cavitation behaviour and its effects on the hull vibration problems.
The test method comprises the specification of the test instrumentation and implementation,construction requirements to ensure structural safety, test and measurement procedures, and reporting documentation.
This document is applicable to ships in the following stages:
— before or during sea-trial, prior to delivery stage (vessels under constructions), and
— after delivery stage.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp
— IEC Electropedia: available at http://www.electropedia.org/
3.1 measured ship speed
ship’s speed during a speed run derived from the headway distance between start and end position and the elapsed time of the speed run
3.2 observation window
transparent window allowing to observe and investigate the occurrence of cavitation of a ship propeller
3.3 propeller plane
plane normal to the shaft axis and containing the propeller reference line, i.e. contain the reference point of the root section
3.4 ship speed
speed of the ship that is realised under stipulated conditions
Note 1 to entry: See also measured ship speed (3.1).
4.2.2 Cavitation observation method
A traditional method using a CCD camera with a stroboscopic lighting source has been commonly used for full-scale cavitation observation. Recently, a technique using a high-speed camera in daylight condition has been used. This technique minimizes the number of observation windows compared to the traditional method and enables to observe detailed motion of cavitation to study the phenomenological behaviour of the cavitation. Furthermore, instead of the existing observation window, a high-speed bore-scope technique has been used in consideration of relative installation time and cost reduction. The small penetrations needed for the bore-scope equipment can be drilled with the ship in a float condition, which reduces the installation time from days to hours and saves money from expensive ship docking operations. However, the high-speed bore-scope technique requires strong sun light and good water quality. The observation windows are more robust against the weather conditions and sea conditions. Thus, observation windows are still useful if there is sufficient construction time and space. Appropriate equipment should be selected depending on the purpose, situation and timing of the installation. Although frequency of image heavily depends on illumination condition, Table 1 shows several examples of various observation methods for full-scale propeller cavitation.