AN EXPERIMENTAL EVALUATION OF THREE METHODS FOR INCREASING THE LEADING EDGE THICKNESS OF SUPERCAVITATING PROPELLERS.
DAVID TAYLOR MODEL BASIN WASHINGTON D C HYDROMECHANICS LAB
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An experimental investigation of three methods of increasing the leading-edge thickness of supercavitating propeller sections was conducted. The purpose of the investigation was to determine which method could be used that would result in the least impairment of the hydrodynamic performance for a given increase of the leading-edge thickness. The three methods were 1 arbitrary thickening of the section beyond the bounds of the theoretical cavity 2 use of a greater angle of attack to increase the thickness of the theoretical cavity and, hence, the allowable section thickness and 3 addition of a parabolic thickness to both the face and back of the section. Five supercavitating propeller models incorporating these three methods of increasing the section thickness were tested in a water tunnel, for a range of various cavitation numbers and advance coefficients. The results indicate that parabolic thickening of the cavity is superior to the arbitrary thickening of the section beyond the theoretical cavity boundary. Use of an increased angle of attack leads to a greater loss of performance than do the other two methods, but it has excellent resistance to face cavitation and, therefore, is recommended where resistance to face cavitation is of great improtance. Author
- Marine Engineering