CLT propellers - Theorical fundaments
The Contracted Loaded Tip propellers (CLT) are screw propellers with important load at the blade tips thanks to the fitting of end plates at the blade tips that actuate as a barrier avoiding the communication of water between both sides of the blades, and the appropiated design of the blade geometry and the radial load distribution. The end plates are positioned so as to cause a minimum viscous resistance and therefore are parallel to the incoming flow and shaped to the relative motion of the water, taking into account the fluid vein contraction.
The tip plate is located on the pressure side of the blade with the aim to obtain a higher overpressure downstream.
The underpressure on the suction side caused by a CLT propeller is much lower than for an equivalent conventional propeller whilst the overpressure on the downstream side is much higher.
The first theoretical developments and results of model tests on these type of propellers were published in 1976, reaching to the conception of the so called TVF (Tip Vortex Free) propellers.The CLT concept was developed in 1986 as a further step ahead.
Since 1976 a continuous effort on R&D has been made on tip loaded propellers by SISTEMAR’s technicians. As a result of the same together with the feed-back gained from the results of the numerous sea trials carried out, the quality and the reliability of the CLT propeller designs made by SISTEMAR have been continuously improving.
The theoretical fundaments of CLT propellers are explained in detail in the book entitled "Detailed design of ship propellers" by G.P. Gómez and J.G. Adalid. The developments and theories used for the design of CLT propellers are fully explained and demostrated in said book in a comprehensive way.