Experimental study on the effect of rocket nozzle wall materials on the stability of methane

Within the MERIT project we study the characteristics of methane under conditions found in rocket nozzle cooling channels, i.e. elevated inflow temperature and a high single-sided heat load.

Background

In recent years there has been a growing interest in methane as an alternative rocket fuel due to its favorable specific gravity, storage temperature, and thermal stability, in addition to its ability to support In-Situ Resource Utilization. Within the MERIT project we study the characteristics of methane under conditions found in rocket nozzle cooling channels, i.e. elevated inflow temperature and a high single-sided heat load. The MERiT experimental facility has been established at HPT\EGI in cooperation with GKN Aerospace, and as part of ESA's Future Launcher Preparatory Program. The facility enables direct measurement of heat transfer and composition changes in methane under a range of conditions, especially those at the thermo-chemical stability limit of methane. The thermo-catalytic decomposition of methane, also known as pyrolysis, results in the creation of hydrogen and solid carbon in the methane fuel stream. One of the objectives of MERiT project is the in-situ quantification of this pyrolysis effect. As the catalytic properties of the wall material influence the pyrolysis process, the detectability of the process is affected as well. Therefore, the influence of different wall materials on the detectability of methane pyrolysis, given a sensor array developed at the department of Energy Technology, needs to be investigated before in-situ measurements in the MERiT experimental facility can be reliably conducted.

Thesis objectives

The aim of the thesis project is to continue the development of a small-scale pyrolysis setup, with which the effect of candidate nozzle wall materials on the pyrolysis process, as well as on the detectability of pyrolysis, can be investigated. The work will also include taking measurements of methane pyrolysis for different wall materials, as well as explaining and reporting the observed effects.

The specific objectives of this thesis are:

To perform a literature review on the catalytic properties of relevant materials on methane pyrolysis
To familiarize with
- The requirements for gas analysis of the MERiT facility as well as existing measurement results
- The current small pyrolysis setup and previous developments
To propose and implement improvements for the small pyrolysis setup
To prepare an experimental plan for material testing with the goal of reaching the pyrolysis inception conditions
To run experiments, collect and interpret data, and report this information.
To work together with researchers at Energy Technology to validate the measurement system for the operating conditions found in real rocket nozzle cooling channels