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Viscous and Nuclei Effects on Hydrodynamic Loadings and Cavitation of a NACA 66 (MOD) Foil Section

Shen, Y. T. and Dimotakis, P. E. (1989) Viscous and Nuclei Effects on Hydrodynamic Loadings and Cavitation of a NACA 66 (MOD) Foil Section. Journal of Fluids Engineering, 111 (3). pp. 306-316. ISSN 0098-2202. http://resolver.caltech.edu/CaltechAUTHORS:20160602-174939023

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Abstract

A series of experiments has been conducted on a two-dimensional NACA 66 (MOD) foil to examine the effects of viscosity and nuclei on cavitation inception. In this paper the main discussions center on two foil angles having different types of pressure loadings to represent a propeller blade section operating at design and off-design conditions. At one degree design angle of attack the foil experiences a rooftop-type gradually varying pressure distribution. At three degrees off-design angle of attack the foil experiences a sharp suction pressure peak near the leading edge. Cebeci’s viscid/inviscid interactive code is used to compute the viscous scale effects on the development of the boundary layer, lift, drag and pressure distribution on the foil. Chahine’s multibubble interaction code is used to compute the effect of nuclei, test speeds, foil size and foil surface on traveling bubble cavitation. Both computer codes are found to agree satisfactorily with the experimental measurements reported here. Two assumptions commonly used to predict full scale surface cavitation from model tests are examined experimentally and theoretically. The first assumption states that cavitation inception occurs when the static pressure reaches the vapor pressure. On the contrary, the experiments showed that the water flowing over the foil surface sustained significant amounts of tension during inception of midchord bubble cavitation as well as leading edge sheet cavitation. The second assumption states that there is no scale effect on the values of negative minimum pressure coefficient. In the case of a rooftop-type pressure loading, the second assumption is supported by the pressure numerical calculations. However, in the case of a pressure loading with a strong suction peak near the leading edge the value of negative minimum pressure coefficient is as much as 12 to 15 percent lower on a model than at full scale.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1115/1.3243645DOIArticle
http://fluidsengineering.asmedigitalcollection.asme.org/article.aspx?articleid=1426893PublisherArticle
Additional Information:© 1989 ASME. Received August 09, 1988.
Group:GALCIT
Subject Keywords:Cavitation , Pressure , Design , Bubbles , Suction , Drag (Fluid dynamics) , Boundary layers , Vapor pressure , Measurement , Viscosity
Record Number:CaltechAUTHORS:20160602-174939023
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20160602-174939023
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:67617
Collection:CaltechAUTHORS
Deposited By: Paul Dimotakis
Deposited On:06 Jun 2016 20:45
Last Modified:21 Sep 2016 23:05

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