Investigation Of The Burning Behaviour Of Aluminum-ice Solid Propellants

Solid rocket motors are favored for launch applications because of their simplicity andhigh thrust to weight ratio. Longer space missions and manned missions will require higherperformance propellants. Nano-scale aluminum is a high energy level metal fuel and theproblems of sustaining combustion has been solved, using it as rocket propellants is a newway to develop the green propulsion systems. It’s combustion form can be aluminum/water oraluminum/ice（ALICE） solid propellant. The aluminum/water combustion system has beenidentified as having high potential for propulsion applications. The ALICE is a kind of greencryogenic solid propellant, which possesses the characteristics of simple structure, highreliability and high impulse, besides, the cost is supposed to be further reduced. It thus has apotential application value.In this article, the thermodynamic performances of the ALICE in different O/F ratioconditions are calculated by Fortran program codes. The program codes is based on theminimum Gibbs free energy method and the energy characteristics are evaluated Themathematical and physical model of heat transfer in the combustion surface region of ALICEis derived and the temperature field is studied using numerical method. The burning ratecharacteristics are evaluated. The burning rate of ALICE is discussed using three differentmean methods to calculate the thermal conductivity coefficient and specific heat. The threemean methods are mass mean, volume mean and harmonic mean. Finally, the characteristicsof ALICE are summed up wholly. Theoretical basis for the practical application of ALICE isprovided. The main conclusions are as follows:1. With the thermodynamic calculation of ALICE, it is found that the main equilibriumproducts of combustion in the combustor and nozzle areH₂andAl₂O₃, in which the massfraction ofAl₂O₃is more than75%. The theoretical performance parameters of ALICE,such as burning temperature, specific impulse and thrust coefficient all have the same changerule which shows to decrease with increasing O/F ratio. The results show that the ALICE is ahigh energy level solid propellant, its maximum specific impulse can be about3300m/s, so itsuggests to be a propellant with strong application potential.2. Calculation results also show that, the burning rate of ALICE increases with thedecrease of the initial temperature, with a sharp increase occurs at273.15K, while decreases with the increase of O/F ratio. By analyzing the burning rate change rule of the conductivitycoefficient and specific heat of the ALICE propellant using three different mean methods, it isconcluded that the thermal conductivity coefficient and specific heat of propellant both havestrong influence on the burning rate. So, choosing a reasonable computing method for themixing zone physical parameters is very important to quantitatively evaluate the burning ratemodel. It is suggested that a volume mean method using each volume of the componentsshould be adopted to calculate the conductivity coefficient and specific heat of the ALICEpropellant.