Next generation ramjet and scramjet engines will require fuels that improve upon the current state-of-the-art. JP-10 is a top contender for this application because it has a high energy density, a low freezing point, and it was the only air-breathing missile fuel used by the U.S. in 2005. However, its use has some serious drawbacks. It is a relatively poor endothermic heat sink and it has a poor flameholding capacity.

The objective of this project was to compare meaningful properties across fuels at relevant flight conditions for a supersonic vehicle.

To determine the specifics, we investigated fuel properties such as lean and rich flammability limits and combustion efficiency. We conducted a literature review to define system requirements, especially concerning the properties of the ramjet combustor inlet (pressure, temperature, velocity, and fuel-to-air ratio). The test article will be modular in design and provide optical access to the fuel injectors and the combustion chamber.

Design of the test article was then underway using chemistry, gas dynamics, fluid mechanics, prior research, and aerospace community rules of thumb.

The calculated and optimized parameters all come together in the 3D design. At this point, tradeoffs must be made between the ideal design and machining considerations. The below figures are various orientations of the combustion chamber CAD model.

Computational fluid dynamics software can aid in the design of test hardware. For example, we can model heat transfer through the fluids in the test chamber.

The test stand design phase is integral for the development of the infrastructure that provides the air and propellants to the test article at the desired conditions safely. The next step is to get the parts machined. After that, once parts are sized for the flow requirements, we can construct and install tubing, valves, regulators, tanks, orifices, wiring, and test articles into the facility shown below.