PANEL DISCUSSION-DUCTED PROPELLERS 



D. E. Ordway, Panel Chairman 

 Therm Advanced Research, Inc. 

 Ithaca, New York _ . 



The objectives established for discussion were to determine what applica- 

 tions are of current interest for the ducted propeller, to review the analytical 

 and experimental results that are available to meet the needs for these appli- 

 cations, and to recommend the future work required if any gaps are found. 

 Representatives from many different countries participated and, in view of 

 their diverse backgrounds, we hoped that such broad objectives could be 

 achieved in a realistic and comprehensive fashion. 



With regard to current interest in the ducted propeller, the response was 

 very enthusiastic and a number of applications were cited. These included pro- 

 pulsion for hovercraft, hydrofoil boats, ocean-going merchant ships and liners, 

 and several other high-speed craft. One specific suggestion was to consider 

 some kind of a ducted propeller for the Sidewall Craft Program sponsored by 

 the Joint Project Office of the U.S. Navy and Maritime Service. Design speeds 

 here range from 80 to 100 kt for sizes from 100 tons up. It turned out that work 

 along these lines is underway by Sogre'ah on what is called a "water-jet pro- 

 peller." This was reported on briefly. 



At the low-speed end, reference was made to V/STOL aircraft, such as the 

 Bell X-22A for carrier operation, and variable geometry for off-design per- 

 formance, to the classical tug-boat application or Kort nozzle, to dynamic posi- 

 tioning of research vessels and drilling and dredging rigs, and to lateral or bow 

 thrusters. Bow thrusters are really not ducted propellers but more of a conduit 

 propeller. Much interest was expressed in this area for stopping and emergency 

 braking, as well as maneuvering and stabilizing big cargo and passenger ships, 

 supertankers, ferries, cutters, and other vessels. Efforts here to date have been 

 limited to low speeds, but attention has now been turned to higher speeds. An- 

 other variation from the normal ducted propeller configuration of interest 

 touched upon was the noncylindrical nozzle to compensate for nonuniform inflow. 



Simultaneous with the above discussions, the associated advantages of the 

 ducted propeller for the different applications were reviewed in some depth. 

 Since most of these advantages are well known, e.g., compactness, efficiency, 

 static thrust increase, inlet flow control, etc., they will not be elaborated on. 



The second objective for discussion concerned the analytical and experi- 

 mental results that are available to meet different applications. In view of the 

 thorough coverage by J. Weissinger and D. Maass from Karlsruhe, W. B. Mor- 

 gan and E. B, Caster from NSRDC, and G. Dyne, C. A. Johnsson, and H. Lind- 

 gren from SSPA that was scheduled for the Session On Unconventional 



1598 



