Measurements of Propeller-Induced Unsteady Surface Force and Pressures
Abstract
Results of an experimental investigation carried out in the 24-inch water tunnel are presented for the cavitating propeller-induced surface pressures and a reference-area surface force measured on a flat plate boundary representation of a nearby ship hull. Newly designed apparatus for the measurement of surface force on an instrumented disc is described in detail. It involves special dynamometry that can be used in a reverse mode so that the force disc can be driven as a mechanical shaker. A model of a seven-bladed propeller was run in a screen-generated simulation of the steep axial wake velocity distribution for a single screw ship. Results are displayed for the longitudinal and transverse distribution of the first three blade rate harmonic components of the unsteady pressure amplitudes and the unsteady disc force amplitudes at the blade tip clearances of 0.26 (diameter) and 0.41D, over a range of cavitation numbers. The unsteady pressure pulse amplitudes obtained in this work compare reasonably will with measured values obtained previously in a large water tunnel experiment using a complete scale model of the ship hull. The experimentally inferred blade rate harmonic component of cavity volume velocity from the reciprocity measurement agrees approximately with the prediction by the PUF-3 propeller anlaysis scheme. Keywords: Pressure amplitude; Surface force; Propeller excavitation; Reciprocity experiment; Cavity volume velocity; PUF (propeller-induced unsteady forces).
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1986
- Accession Number
- ADA177590
Entities
People
- David W Taylor
- John Mchugh
- Michael B. Wilson