High-Output Combustion of Ethyl Alcohol and Air

Abstract

Abstract Test results, obtained under sponsorship of the Bureau of Ordnance, are reported for the combustion at 475 psia of air with a mixture of 92.5 per cent ethyl alcohol and 7.5 per cent water by mass. The exit-gas temperature was varied between 1350 F and 2050 F and was controlled through the introduction of excess fuel. A combustor design which gave combustion intensities up to 11 × 106 Btu/hr ft3 atm was employed. The experimental relations between gas temperature, fuel-air ratio, isentropic enthalpy drop obtainable from the combustion gas, gas composition, and thermodynamic properties of the combustion gas are given in detail. Theoretical results based upon the assumption of chemical equilibrium at the temperature of adiabatic combustion are in moderately good agreement with the measured results. It is inferred from the data that a condition approximating “frozen” equilibrium sets in at about 2500 F. Two methods of evaluating isentropic enthalpy drop were used and compared, one based principally upon the measurement of thrust, and the other based principally upon gas analyses. Small variations in combustor size and design were investigated. A discussion of the principles underlying the thrust method is given in an Appendix.