Quandt 



One point of view I would like to emphasize here, is the effect of gravity. I 

 see that Dr. Quandt has excluded gravity effects and considers the flow in this 

 propeller steady and homogeneous. I am afraid that, at least with lower speeds 

 and higher water-to-air mass flow ratios, the flow will be unsteady. 



For the past two years we have been studying a two -phase propeller which 

 is based on the effect of gravity and which possibly can be used for the propul- 

 sion of slow and medium-speed ships. A model having a WL-length of 1.6 m 

 was made and tested. It was observed among other things that at least in this 

 case the two -phase flow was very unsteady. Results of these first tests will be 

 reported in ISP September issue. 



To study the scale effect of this propulsion we have built this spring another 

 geometrically similar model which has a WL-length of 6.4 m and total length of 

 10 m. This larger model was tested in open sea. It can be seen from Fig. D-1 

 that unsteadiness of this two -phase propeller even dominates the stern wave 

 system. 



Fig. Dl - Test boat equipped with two-phase 

 propulsion; waterline length 6.4 m, displace- 

 ment 6 tons 



Wartsila shipyard in Helsinki has also started research of this propulsion 

 and they have concentrated on the application of this propulsion to the lateral 

 thrust units. As a result of this research, a car ferry now under construction 

 in Finland will be equipped with two -phase bow-propeller. 



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