With the urge of not only the aerospace propulsion system industry, but all industries of engineering to improve each system into a more sustainable solution, a lot of different green propellant combinations have been investigated that are less toxic, and more eco-friendly, but however efficient at the same time. This is true for liquid bi-propellant systems as well. Due to the emergence of new propellant combinations, or with the demand for more energy-efficient propulsion systems, new types of ignitor systems, which are a significant element in a bi-propellant space propulsion system, or the improvement of the conventional systems to a more efficient one are being investigated. Following the demand for research in these sectors of propulsion systems, this MSc thesis focuses on the development of a liquid bi-propellant space propulsion ignition concept, which is optimised from the perspective of power, cost, and performance.

During the literature study phase of the thesis, several ignitor systems were investigated and the thermal wire ignitor concept was chosen to be the most suitable system for the study due to its reusability function, cost-effectiveness, mass/volume, and handling features. On top of that, after understanding the features of several fuel and oxidiser combinations, ethanol and HTP were chosen as the most optimal propellant combinations. These were shown to provide performance similar to conventional propellant combinations, such as in density-specific impulse, and most importantly, were considered an eco-friendly combination.

During the experimental phase of the MSc thesis research, the first experiment aimed to measure the resulting HTP temperature when it passes through a NiCr thermal wire mesh in a glass chamber, where the chamber itself is heated up with a wire wound around the external wall. This experiment showed that a resulting temperature of almost 400 deg C was achievable with 20 W of power applied to the wire mesh down to a value of 294.37 deg C for 5 W of power applied. The most interesting point is at a power value of 12.5 W, in which the HTP reaches a temperature value right above the auto-ignition temperature of ethanol, 375.65 degrees C.

The second experiment aimed in investigating the ignition behaviour of the fuel and HTP in an open environment. The results showed that at 12 W of power applied to the NiCr thermal wire mesh, which was in contact with a premixed fuel and oxidiser pool this time, combustion and self-sustained ignition were achieved with a sufficiently short amount of IDT (around 200 ms). Also, at 10 W of power applied, combustion occurred with HTP and Jet A, which was a reference fuel used with the purpose of showing that fuel types that have an auto-ignition temperature lower than ethanol are able to ignite at lower power consumption values. The self-sustained ignition was obtained at power values slightly higher than this, 12.5 W.

The last experiment aimed in investigating the ignition behaviour of the fuel and HTP in a closed environment, which also serves as a pressurised system. The results showed that at 10 W, the ethanol and HTP combination was able to combust and self-sustain. Also, at a value of 7.5 W, the Jet A fuel and HTP combination were able to combust and provide a self-sustainable ignition. They both showed that in a pressurised system, lower levels of power values are required in order for the same fuel and oxidiser combination to achieve combustion.

Simultaneously with the experiment conducted, a simulation of the HTP decomposition temperature in a glass chamber was done using the cross-platform finite element analysis, solver and multi-physics model software, COMSOL. The simulation was able to show that at power values of 20 W, as the HTP is injected in the glass chamber, the liquid was able to achieve a temperature of 589 degrees C but decreased drastically down to the initial temperature of the volume that was inputted in the software. This simulation was done using a mesh configuration named Normal, which is an automatically available mesh quality in the COMSOL software. Together with the same mesh quality, if 15 W of power is applied, the initial temperature that the HTP achieves is 492 degrees C and for 10 W, it is 394 degrees C. All the results presented matched the results of the experiment conducted. Lastly, 2 sensitivity analysis were performed in order to prove that the simulation was done properly.