Anna Petrarolo

Combustion Visualization and Characterization of Liquefying Hybrid Rocket Fuels

Recent results of data evaluation techniques are summarized in this paper about optical investigations of the combustion behavior of different hybrid rocket fuels. They are analyzed by optical techniques in detail. Tests are performed in a 2D slab burner configuration with windows on two sides. Mainly liquefying Paraffin-based fuels including additives are tested in combination with gaseous oxygen (GOX). High speed video imaging enables the analysis of combustion phenomena at great detail. But at the same time a huge amount of data is created, that has to be evaluated carefully. Clearly, a manual analysis is rather time consuming and probably more susceptible to errors. Therefore, two different techniques are presented in this work, which are used within an automated video evaluation routine. First of all, the Proper Orthogonal Decomposition (POD) technique is applied. Its results deliver linearly uncorrelated variables which are the principal components of the flow field. This method enables a decomposition of the data set into mean, coherent and incoherent parts, thus recognizing the main structures of the flow field and the combustion flame appearing in the video data. Secondly, the Independent Component Analysis (ICA) technique is applied to the same data. It is able to search for statistically independent, or as independent as possible, structures hidden in the data, thus increasing the independence to higher statistical orders with respect to POD. The basis functions found with the ICA are expected to describe the essential structure of the data and to resemble some physical processes involved in the combustion. With both methods it is possible to compute spatial and temporal coefficients, which can be later analyzed by applying a Power Spectral Density (PSD) in order to obtain the excited frequencies and wavelengths during the combustion. Finally, the results of the two methods are compared in order to better understand and interpret them. A comparison between spatial and temporal ICA is also performed. The results collected so far and the comparison of both techniques show that their application is consistent and useful for the automated evaluation of combustion data.

Sounding Rocket "HEROS" - A Low-Cost Hybrid Rocket Technology Demonstrator

The inherent safety of hybrid rocket propulsion offers some unique advantages com- pared to solid and liquid propellant rocket engines. This makes it especially attractive for space tourism, Micro-launcher and hands-on experiments in the education of students. On November 8th, 2016 at 10:30 a.m. the hybrid sounding rocket HEROS 3 was launched from the ESRANGE Space Center to an apogee altitude of 32,300m (106,000 ft). This set a new altitude record for European student and amateur rocketry and a world altitude record for hybrid rockets built by students. The 7.5m long rocket was using Nitrous Oxide (N2O) and a Paraffin-based fuel to produce 10,000N of thrust. The dry mass of the rocket was only 75 kg thanks to a carbon fibre structure for the most part. The rocket performed the record breaking flight at perfect weather and visibility conditions, reaching a maximum airspeed of 720 m/s and Mach 2.3. The rocket performed a soft landing with two parachutes and can be reused. Flight data and engine performance data are published and analyzed. The flight data shows excellent stability of the rocket. Engine performance data proves very high efficiency and stable combustion as in the ground tests. The subsystem design and verification before the launch is reported. Engine and flight trajectory simulations show very good agreements with the flight data. Furthermore, the overall project, the rocket design, the subsystems as well as the launch campaign are presented here in detail.