Propeller Blade Measurements for HMCS NIPIGON

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Authors
  1. Noble, D.J.
Corporate Authors
Defence R&D Canada - Atlantic, Dartmouth NS (CAN)
Abstract
This report describes results obtained for the differences in the blade geometry of the propellers of HMCS NIPIGON based on detailed blade measurements performed with a pitchometer and ultrasonic thickness measuring equipment. Visual inspection of the blades made while the ship was in dry dock for a previous sea trial revealed signs of significant surface wear and damage. The measurements were requested by DRDC Atlantic after the ship went out of service to determine if the geometric differences between the blades of each propeller could have caused the unexpectedly large differences in the cavitation inception performance of individual blades oberved during the sea trial. The results show significant differences in the key geometric parameters of blade sections, especially in the pitch angle, chord length and rake of measured sections at outer radii. Of the section differences obtained from the blade measurements, the pitch angle increases of more than two degrees relative to design approaching the blade tips are expected to have the largest effect on inception of cavitation in this region. Examination of the nose shapes of the leading edges on selected blades also revealed flats and overly sharp edges near locations where cavitation was observed to form during the sea trial. TRUNCATED

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Keywords
Cavitation inception;Blade measurements;Pitchometers;Ultrasonic measurement;Section thickness measurement;Blade geometry;Section geometry;HMCS Nipigon
Report Number
DRDC-ATLANTIC-TM-2002-093 — Technical Memorandum
Date of publication
01 Jun 2002
Number of Pages
126
DSTKIM No
CA021481
CANDIS No
518201
Format(s):
CD ROM

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