|M.Sc Student||Valensi Shlomit|
|Subject||Parametric Sea Trials of Marine Ramjet Engine Performance|
|Department||Department of Aerospace Engineering||Supervisor||Professor Emeritus Alon Gany|
Since the dawn of his creation, mankind tries to learn from nature how to move around efficiently. Marine propulsion is as ancient as terrestrial propulsion and originates in the prehistoric era; Aerial propulsion systems developed later. Notwithstanding, aerial and terrestrial propulsion seem more developed than marine propulsion.
The fastest marine creature known to man is the sailfish (Istiophorus Platypterus). Its cruise velocity reaches a top speed of 60 knots (110 km/h). The fastest ferryboat, the Australian “Luciano Federico L”, has a cruise velocity of 57 knots - slightly inferior to the Sailfish. It is true that man holds the velocity record at sea, but in vessels designated for extreme competitions and not for commercial purposes. The need for developing a compact and simple propulsion system, which will present a breakthrough in the field of commercial marine propulsion, is clear.
The objectives of this research are to perform sea trials and to accumulate data on new two-phase marine ramjet propulsion.
The marine ramjet is based on usage of water as the working fluid in the thrust generation process. Accelerating the working fluid is done by adding gaseous phase in the form of bubbles into the aqueous medium, thus creating a two-phase mixture of water-air, expanding through a nozzle, generating thrust. Adding the gaseous phase into the liquid significantly changes the physical characteristics of the bubbly medium in comparison to each one of the flow components on its own. This might manifest itself in flow development and nozzle design in high speed marine ramjet propulsion systems, in resemblance to avionic ramjet propulsion systems.
For the parametric sea trials two full-scale marine ramjet propulsion units were designed and assembled, and then mounted at the bottom of a test platform (boat). The open sea experiments included the use of a towing boat to determine the experimental boat resistance and the ramjet thrust for different cruise speeds and airflow rates. The results show good agreement with the theoretical performance calculations in the tested operating ranges, with typical dispersion around the average values. The considerable thrust increase with increasing cruise velocity was plainly demonstrated throughout the trials.
The quantitative results obtained during the sea trials indicate a real potential for a ramjet-based marine propulsion system.