THE COMPUTER-AIDED FUNCTIONAL DESIGN OF A MARINE PROPELLER

An existing propeller geometry is represented mathematically using a m ethod for computer-aided design known as the partial differential equa tion (RUE) method. Using this method of surface design ensures that th e propeller blade is completely defined and controlled by a small set of design parameters. This geometry may be analyzed using a panel meth od to obtain the flow past the blade, and a performance measure, in th is case the efficiency of the propeller, is obtained. Functional desig n of the propeller is achieved by allowing the design parameters to ch ange. Altering the design parameters will affect the efficiency, and h ence the set of design parameters which gives a propeller geometry of maximum efficiency is sought. This is achieved automatically through a numerical optimization routine which alters the design parameters. Th e advantage of this approach is that complex geometries may be represe nted in terms of a small parameter set which enables the effective imp lementation of the optimization routine. Constraints may also be impos ed to maintain feasible designs. In the case considered the usual desi gn constraints to delay and restrict the onset of cavitation are impos ed. However, additional requirements, requiring in themselves substant ial analysis, such as strength of the blade, may be considered.