An underwater “scramjet engine” (Jr IS guest blog by Jack Mershon)

I have always thought that one of the most outdated technologies we currently employ in the large scale is propellers for ships. While this isn’t a critical fault in our world it does lead to a lot of inefficiencies. Modern trade ships and super-tankers use millions of tons of fuel annually. This does a great deal of damage to the environment. Air travel was also largely propeller based at its inception, but since then several new types of engine have been developed. Most notably the Scramjet engine ingests air and mixes it with fuel at supersonic speed, exhausting the combustion results to produce thrust. This is a highly effective method of producing thrust, one which has been able to produce speeds of Mach 12. For reference, at Mach 12 one could travel the entire distance of the equator in less than three hours. I believe that it is possible to take some of the principles of the Scramjet engine and develop a version for generating thrust underwater.

My project was to simulate this new kind of underwater propulsion system to determine whether or not it could feasibly operate. I did this by working with legacy code provided by another student that simulated air flowing through a channel. I modified the code to simulate water flowing through the channel, and also added a simple structure to represent a simple Scramjet style water propulsion device, shown above as the red boxes. The simulated Scramjet water propulsion system used heat as a fuel source, this is done by simulating the result of water boiling so quickly it evaporates with explosive force. This is shown with the gray boxes in the center, within each of these the simulated water gets “kicked” in a random direction and gains a high speed. The results of my simulation were inconclusive but I did show that the Scramjet Structure had an effect on the operation of the system. I believe with enough tweaking this simulation would show that such a system would operate in the real world.

This Gif shows the operation of the simulation where the red outlined blocks are the Scramjet structure the grey outlined blocks are the energy input to the system, and the colors indicate the direction the water is flowing. The direction is given by a color wheel–for reference, light blue is directly to the right.
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