液体噴進剤の比推力について

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The purpose of this paper is to calculate the performance of all sorts of liquid propellants composed of carbon, hydrogen, and oxygen atoms under the same conditions. As the combustion equation for each fuel (its general formula is given by C_mH_<2n>O_I) at a given mixed ratio with oxygen is determined by a fractional number n'=n/n+m indicating the composition of fuel and a parameter H' relating to the heat of formation of the reactant (exactly, H' is given by one-(m+n) th of the sum of the heat of formation of fuel and consumed liquid oxygen), it is more general to calculate the performance of propellants as a function of these two variables, n' and H', than to calculate the performance of the every kinds of propellants individually. Therefore these two variables have been adopted for the following calculations. In the first place, taking into account the five dissociation equilibrium relations, we have determined an accurate relation between the parameter H' and the combustion temperature T_c for a given n' value. Then, according to the method described by Penner, we have calculated the value of specific impulse Isp as a function of T_c. The procedure of this calculation is simplified by the graphical method and the trial and error method has not been used. The chamber pressure of 30 atmospheres, the expansion ratio of 30 : 1, and the frozen chemical equilibrium during the expansion process are also assumed. Similarly the combustion temperature Te and the specific impulse value I_<sp> for other n' values are calculated as a function of parameterH'. And from these calculations the combustion temperature T_c and the specific impulse value I_<sp> have been expressed in terms of n' at a given H' value. Figures 5 and 6 indicate the results of the calculations carried out on the stoichiometric mixture of fuels and the Oxidizer using some integer values of H' as parameters. To see the effect of imperfect combustion on the specific impulse values, similar calculations have been made on the eight different propellant system containing an excess of fuel over oxidizer. The results of the latter eight cases are represented in Figures 9 to 24. The performance of all sorts of fuels burning with the arbitrary amount of oxidizer are obtained from these charts immediately, when we know their composition n' and parameter H'. Some applications of these charts are also discussed. Specific impulse values of stoichiometric mixture of fuels and liquid oxygen are shown in Figure 36-b with a new parameter H" which is equal to the one-(m+n) th of the heat of formation of fuels only. The change of spcific impulse with the chain length of nparaffin (Figure 7), and the effect of the addition of water as coolant (Figure 8) are illustrated for the stoichiometric mixture with liquid oxygen. The most interesting application of these charts is the one relating to the change of specific impulse values with the increasing amount of fuel to the oxidizer. In the suitable range of Hf, specific impulse reaches to the maximum value when the optimum mixed ratio with oxidizer is used (Figures 25 to 34). For the same H' value, the fuels rich in hydrogen reach to their maximum values with an amount of oxidizer less than that of the fuels rich in carbon. And for the same composition n', fuels having higher H' values also reach to their maximum specific impulse value with an amount of oxidizer less than that of the fuels having lower H' values. Furthermore, when we make a chart of these maximum specific impulse values versus composition n' and parameter H" (Figure 36-a), we can obtain the maximum specific impulse values of all sorts of fuels mixed with an optimum amount of liquid oxygen, and we can determine what sort of fuels should have the highest values of specific impulse. Probably an optimum mixture of diacetylene and liquid oxygen is the best propellant, evaluating from the stand-point of the value of specific impulse. The applications of these charts are not limited to the cases of the combustion with oxygen, and the combustion of fuels with hydrogen peroxide are also discussed using these charts. Hydrogen peroxide is an excellent oxidizer, because the mixture of fuel and oxygen shows the very high combustion temperature, whereas the mixture of the same fuel and hydrogen peroxide shows the considerably lower combustion temperature and a little lower value of specific impulse (Figure 37).
宇宙航空研究開発機構の論文
1956-07-10

著者

倉谷健治
東京大学理工学研究所

液体噴進剤の比推力について

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