Actual form function derivation and its application in gun propellant combustion analysis

To analyze and evaluate the gun propellants with complex and fluctuating combustion process, a method of calculating the actual form function is derived. The Γ-ψ curve is inversely calculated to derive the ψ-Z curve, which is the actual form function. The actual form function based on the L-B curve is also derived in the same way. Spherical propellants and multi-perforated propellants were used as examples to verify the reliability of this method in judging the combustion progressivity of propellants. The results show that this method is reliable and can be used to observe and analyze the combustion process from another perspective. Its integral area Sψ serves as a quantitative means for evaluating the combustion progressivity. The propellant with lower Sψ value but not lower than 0.33 has better combustion progressivity. The internal ballistic parameters of many actual form functions were calculated by using the classical internal ballistic method. The results show that using Sψ to judge the progressive combustion property is accurate in most cases.