TUESDAY, 9th APRIL 2019
“MARINE PROPELLER GEOMETRY MODELLING
THROUGH B-SPLINES SURFACES”
RODRIGO PEREZ FERNANDEZ, MSc PhD CEng MSNAME MRINA MCOINE
SHIPBUILDING AREA MANAGER, SENER, SPAIN & PART TIME PROFESSOR OF POLYTECHNIC UNIVERSITY OF MADRID
Meeting to be held at
Lloyds Register, 71 Fenchurch Street London EC3M 4BS
at 17:30 for 18:15 hours (duration approximately 1 hour)
This presentation will introduce new design methodology for modelling the blades of ship propellers using B-splines surfaces that is a standard tool in CAD and Naval Architecture software products. Propeller blades of a ship are good examples of free form surfaces designed specifically considering several parameters that control their performance. Traditional tools for surface design in CAD such as control point manipulation are not appropriate for blade design, and the designers prefer to work with a collection of propeller parameters that ultimately represent its surface and that possess a clear hydrodynamic meaning. This method uses common design parameters of the geometry of propellers and produces a final B-spline surface for the geometry of the blades that can be used for the visualization, calculations and construction of the propeller. The method starts with the definition of a 3D grid of points that form the propeller blades based on the 2D definition of a series of cross-sectional profiles at several radial locations. These 3D points consider the inclination and the twist of the blades given by rake and pitch angles, quite common in the design procedures and different propeller diameters such as skew and blade thickness distribution.
Propeller blades are very thin objects with great changes of curvature and if standard B-spline techniques are used, they cannot be modelled well under a tolerance unless a large number of control points are used producing very complex surfaces.
The method stresses the fitting of the blade’s leading edge which has a great effect on the propeller behaviour and geometrically has a small curvature radius in comparison with the rest of the blades. The leading edge is difficult to reproduce with standard techniques.
ALL ARE WELCOME
Continuing Professional Development (CPD) Certificates will be available at the end of the meeting for attendees, if requested in advance.
PRE-BOOKING IS ESSENTIAL. PLEASE CONTACT THE SECRETARY FOR BOOKINGS AND CPD CERTIFICATES.
Secretary: Ms. Viviana Carta Phone: +44 7986 81 2506