The Michigan Single Element Rocket Injector Experiment is a laboratory scale rocket engine with a single shear coaxial injector and optical access for laser-based diagnostic techniques. Its design is based on work done at Penn State and NASA Marshall.

The setup is of a modular design. It comprises of several solid sections and a windowed section that can be moved to various locations along the combustion chamber. The overall length of the chamber can be varied by the addition or removal of sections.

The figure below shows a schematic of the assembly, followed by a photograph of it. The rocket is comprised of sections including the injector assembly, the windowed section, the ignition block, a number of solid sections and the water-cooled nozzle assembly. The system is capable of chamber pressures up to 10 atmospheres.

Schematic diagram of the Single Element Rocket Injector Facility
Photograph of the setup without the nozzle assembly (for atmospheric cases)

The injector assembly contains a single shear coaxial injector. Oxidizer flows through the central tube surrounded by an annulus of fuel. The injector is a modular design that allows the inner tube and injector face plate to be modified.

Both reacting (H2/O2) and non-reacting (N2/N2) cases are run. Runtimes are limited to 12 seconds, of which 10 are used for data acquisition, to prevent overheating of the rocket during reacting cases.

The propellant delivery and control system has been designed with multiple redundancies to prevent any catastrophic failure of the entire system. The whole experiment is controlled remotely using LabVIEW. Mass flows are metered using calibrated choked orifices with pressure transducers and are controlled using a combination of regulator and needle valves. Due to a difficulty in setting the mass flow rates of the propellants when there is no flow through the system, an oxidizer vent valve and fuel burner are integrated to the system to allow the propellant to flow through the delivery system and bypass the combustion chamber. The utilization of this bypass allows a more accurate setting of the mass flow without forming a potentially dangerous combustible mixture in the rocket.

The propellant delivery system is controlled by a LabVIEW VI, which also acquires and stores experimental data.

Chamber conditions are characterized using OH* chemiluminescence, OH PLIF and high frequency pressure transducer.

The complete experimental setup