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Combustion Devices

Combustion Devices designs, manufactures, and tests the injector, chamber, and nozzle that turn propellant into thrust. We bring together analysis and hands-on work to build hardware for the extreme conditions inside a liquid rocket engine.

From injector to nozzle

We turn the rocket’s size and performance goals into the geometry of the engine. Calculations and simulations guide the sizing of the injector, combustion chamber, throat, and nozzle. Each decision has to account for the propellants, operating pressures, and intense heat the hardware will face.

Engine cross-section showing the injector assembly, chamber, narrow throat, and expanding nozzle.
A view inside the engine, from the injector assembly to the nozzle exit.
Line plot of ambient specific impulse against mixture ratio, with a separate curve for each nozzle expansion ratio between 3.3 and 5.8.
A sweep of specific impulse against mixture ratio, one curve per expansion ratio. Trades like this one are how a chamber pressure and a nozzle size stop being assumptions.

From design to hardware

The work moves between CAD, modeling, and the machine shop. We manufacture engine components and bring the designs together as physical hardware ready for testing. Current development focuses on an ablative chamber to support rapid testing, with a lining that gradually wears away to protect the chamber from combustion heat.

Dimensioned shop drawing of the ablative engine nozzle washer, with a plan view, two section views, and an isometric in a Duke AERO title block.
A nozzle washer for the ablative engine, drawn for the shop.
A student operating a lathe while machining a metal part in the shop.
A cylindrical metal workpiece with machined grooves held in a lathe chuck.
Close-up of grooves and tool marks on a machined metal component.

Machining in the shop, from the lathe to the finished surface details.

Bringing the test together

Combustion Devices works with Fluid Systems and Electrical & Controls to match the engine with its propellant supply and test setup. Beyond the engine itself, we help develop the ignition system, test stand, and water deluge system that limits exhaust damage. Preparing for a hot fire means making those pieces work together.

Machined engine hardware bolted to a vertical test-stand support in the shop.
Engine hardware mounted on the test stand.