Engine and technique for generating an acoustic signal

A method for generating an acoustic signal in a fluid, the method comprising:

• vibrating a membrane of a device by repeating a thermodynamic process in the device, wherein the thermodynamic process includes:
• combining reactants inside a chamber of the device to generate heat inside the chamber;
• generating pressure inside the chamber from the generated heat;
• in response to generating the pressure, moving in a first direction a portion of a membrane of the engine;
• removing mass from inside the chamber to decrease the pressure inside the chamber;
• and
• in response to decreasing the pressure inside the chamber, moving the membrane portion in a second direction.

A system comprising:

• a buoy operable to float in a fluid;
• and
• a device coupled to the buoy and operable to generate in the fluid an acoustic signal having more than one period, the device including:
• a body having a cylindrical shape;
• a chamber disposed within the body and operable to contain a chemical reaction that generates heat to generate pressure inside the chamber;
• an intake valve operable to open the chamber to allow a reactant to be inserted into the chamber, and operable to close the chamber to cause the heat from the chemical reaction to generate pressure inside the chamber;
• an exhaust valve operable to open the chamber to release mass from inside the chamber to decrease pressure inside the chamber, and operable to close the chamber to cause the heat from the chemical reaction to generate pressure inside the chamber;
• a membrane having a portion that is operable to move in response to a pressure change inside the chamber, wherein the portion moves in a first direction while the pressure inside the chamber increases, and the portion moves in a second direction while the pressure inside the chamber decreases;
• and
• wherein the increase and decrease of pressure inside the chamber can be repeated by the device to vibrate the membrane portion in the first and the second directions to generate an acoustic signal having more than one period.