• endoreattore
• etano
• FVP
• perossido di idrogeno

In recent years space missions become more ambitious so the need for
reducing the costs and increasing the capabilities of rocket systems
through the enhancement of their propulsion performance, safety and
reliability represents a major aspect in the development of competitive
space engines. A variety of factors have resulted in an increasing
interest in the exploration of alternatives to widely employed cryogenic
and hypergolic propellant combinations. These factors include heightened
sensitivity to cost, environmental concerns and personnel protection
from the hazards associated with the use of present highly toxic
propellants. The current standard in high-performing, storable
bipropellants is the combination of nitrogen tetroxide (NTO) and
hydrazines (N2H4, MMH and UDMH); these propellants are extremely toxic,
carcinogenic and explosive so they presents disproportionately high
costs especially for small and medium size satellites. In this range of
satellites, hydrogen peroxide (HP, H2O2) is widely recognized to be one
of the most promising non-toxic (“green”) storable propellants due to
its lower total costs. Hydrogen peroxide used as monopropellant has a
specific impulse of the order of 180 seconds but used as oxidizer in a
bipropellant engine it has a specific impulse of the same order of a
NTO- N2H4 system.
At the moment Alta S.p.A. is working on the development and testing of
advanced catalytic beds for H2O2 decomposition and their application to
monopropellant rocket thrusters. The expertise acquired in this sector
gave the possibility to analyze and assess the propulsive and
operational performance of innovative green bipropellant thrusters with
Fuel Vapour Pressurization (FVP) of hydrogen peroxide and ethane (C2H6),
where the catalytic reactor provides the oxidizing stream for C2H6
combustion. Fuel vapour pressurization systems consists in the use of
just one tank for both propellants and it exploit the high vapour
pressure of ethane to transfer both the fuel and the oxidizer into the
combustion chamber. This pressurization system provides a significant
reduction of the costs and of the overall system mass.
The present thesis is concerned with the conceptual analysis of the FVP
system, in particular with the analysis of the tank temperature and
pressure drift, and the preliminary measuring of a 50 N thruster
prototype.
Chapter 1 is an introduction about the performances of hydrogen peroxide
bipropellants rockets while in the chapter 2 are showed the physical and
chemical properties of hydrogen peroxide and ethane.
In chapter 3 is illustrated the analysis of the pressure drift of the
tank whit the hypothesis that the oxidizer-fuel ratio remain constant
during the mass extraction from the tank.
Chapter 4 shows the same analysis of chapter 3 but without the
hypothesis about the constancy of the oxidizer-fuel ratio; it also
illustrates the differences in the performance with the choice of the
mass regulation system.
Chapter 5 e 6 illustrate the design of the bipropellant rocket and the
performance’s analysis.
The first appendix describes the method used for evaluate the viscosity
and the thermal conductivity of the mixture of gas in the combustion
chamber, useful to calculate boundary layer and thermal parameters.
The thesis work is a part of an Alta’s wider project end it has been
carried out under the supervision of Prof. Luca d’Agostino, eng. Angelo
Pasini and eng. Lucio Torre