Integrated Resonance Tube Rocket Engine Ignition and Instability Suppression

Integrated Resonance Tube Rocket Engine Ignition and Instability Suppression

Docket: UAH-P-08005


Liquid rocket engines experience various difficulties, including ignition for engine restart in extreme low temperature and vacuum conditions, as well as acoustic noise and combustion instabilities, which can even couple with the fuel inflow and magnify themselves.

UAH researchers have developed an acoustic engine igniter that uses a resonance tube to not only ignite the propellant, but also to mitigate combustion instability. By placing the resonance tubes at appropriate locations within the combustion chamber, combustion instabilities can be avoided and acoustic noise can be reduced.

Using the resonance tube for ignition also allows for more efficient use of the fuel by enabling ignition to occur within milliseconds. This is especially advantageous for engines that require frequent restart at extremely low temperatures, such as Attitude Control Systems (ACS) in space.

A typical ACS is turned on and off frequently in the extreme conditions of space while in service. Thus, current attitude control systems avoid using liquid bi-propellant engines, and instead use the cold gas thruster or the hypergolic engine with lower performance. By eliminating the slow ignition problem of the liquid propellant engine, this invention allows it to be used in the ACS efficiently.


  • Rocket and satellite propulsion systems
  • Attitude control systems


  • No moving parts
  • High pressure ignition is achieved within milliseconds, even in the cold vacuum environment of space
  • Combustion instabilities are eliminated, and acoustic vibration is reduced by proper location and sizing of the resonance tubes within the combustion chamber
  • Ability to perform over the life of the engine
  • Simple design negates the need for additional valve fittings, and electronic ignition on the advanced ignition systems


  • State of Development: Prototype
  • Licensing Status: Available for licensing
  • Patent Status: Proprietary