Specifics of small satellite propulsion. II

Abstract

Small space vehicle propulsion is not only a technological challenge of scaling systems down, but also a combination of fundamental physical constraints. Several of these constraints related to small cold-gas, resistojet, and chemical thrusters are discussed in this paper. In particular, the trades of small size nozzle and reaction chamber designs are considered. NOMENCLATUREa -sonic velocity, m/s A c h s , A cs and A e -reaction chamber surface, crosssection, and nozzle exit areas, m 2 c -effective exhaust velocity, m/ŝand d th -chamber and nozzle throat diameters respectively, m F -thrust, N h -heat transfer coefficient, W/m 2 /K H °f-enthalpy of formation, J/mol I sp -specific impulse, s I ^t -minimum impulse bit, mN-s k( T) -heat transfer coefficient, J/m 2 /K 1 L -characteristic body dimension, m l ch and l noz -reaction chamber and nozzle lengths respectively, m m -propellant mass flow rate, kg/s n -number density, number of molecules per unit volume in the gas, #_of_molecules/m 3 p a , p ch and p e -ambient, chamber, and nozzle exit pressure respectively, Pa R = 8.31441 J/mol/K -universal gas constant Q g and £)/,/ -heat generation due to exothermic chemical reaction and heat losses out of the thruster, J Q and Q hl -.rates of heat generation inside and heat loss out of the reaction chamber respectively, W r , r c and r, -radius-vector, nozzle throat and inlet radii of curvature, respectively, m Re -Reynolds number T ch -chamber temperature, K t and t p -time and pulse duration respectively, s u and u e -flow and exit (or exhaust) velocities, m/s u -mean flow velocity, m/s U -maximum flow velocity, m/s V ch -reaction chamber volume, m 3 W-thruster mass, gm x -distance from beginning of boundary-layer, m a-nozzle divergence half-angle, deg. /?-nozzle convergence half-angle, deg. Y -specific heat ratio 1 American Institute of Aeronautics and Astronautics Downloaded by Duke University on September 24, 2012 | http://arc.aiaa.org |

Effect of Ir crystallographic site on the catalytic performance of Ir-substituted barium hexaferrites for N2O decomposition

“…N 2 O is being considered as a promising green propellant due to a number of advantages, such as facilitating multiple propulsion modes, self-pressurizing, system simplicity as well as low-cost and good compatibility with common construction materials [1][2][3]. The chemistry for N 2 O as a propellant lies in the decomposition of N 2 O into N 2 and O 2 accompanies with a large amount of heat release and volume expansion, which can be used as propulsion power.…”

“…Quite different from the abatement of environmental pollutant N 2 O where the concentration of N 2 O is only in ppm level [4][5][6][7], the N 2 O used as the propellant must have a high-concentration, even being a pure chemical, so as to generate the propulsion power as high as possible. However, the decomposition of pure N 2 O is a highly exothermic reaction (the enthalpy is −82 kJ/mol) and leads to a temperature rise over 1000 • C [1,8]. For this special application, besides activity, the high-temperature stability of catalytic materials is also the main challenge for N 2 O decomposition applicable in propulsion systems.…”

Stabilization mechanism and crystallographic sites of Ru in Fe-promoted barium hexaaluminate under high-temperature condition for N2O decomposition

“…Quite different from the abatement of environmental pollutant N 2 O where the concentration of N 2 O is only in ppm level [4][5][6][7][8][9][10][11][12][13], the N 2 O used as the propellant must have a high-concentration, even being a pure chemical, so as to generate the propulsion power as high as possible. However, the decomposition of pure N 2 O is a highly exothermic reaction (the enthalpy is −82 kJ/mol) and leads to a temperature rise over 1000 • C [1,14]. Therefore, for the N 2 O decomposition applicable in propulsion systems, besides activity, the high-temperature stability of catalytic materials has become a paramount factor to be considered.…”

“…N 2 O is being considered as a promising green propellant used for small satellite propulsion systems, due to its low toxicity compared with traditional hydrazine propellant, as well as its capability for self-pressurizing and compatibility with the common construction materials [1][2][3]. The chemistry for N 2 O as a propellant lies in the decomposition of N 2 O into N 2 and O 2 accompanies with a large amount of heat release and volume expansion, which can be used as propulsion power.…”

Rhodium Supported on Silica-Stabilized Alumina for Catalytic Decomposition of N2O

“…Nitrous oxide (N 2 O) has received growing interest as a promising green propellant for small satellite propulsion due to its low toxicity, self pressurizing, and multi-mode propulsion [1,2]. The earlier successful experiences of using N 2 O as a propellant within a resisto-jet propulsion system on the UoSAT-12 mini-satellite and as the oxidizer for the hybrid engine powering ''Spaceship One'' have shown the great potential and feasibility of N 2 O as a green propellant for modern advanced propulsions.…”