Nonsteady one-dimensional imploding detonations of cylindrical and spherical symmetry are analyzed by using a perturbation method. Nonsteady onedimensional equations are perturbed with respect to time through the parameter ε=1/n[(t0/t)n-1], which vanishes initially (at t=t0) while tends to infinity at the moment of collapse (at t=0). Then there result a series of ordinary differential equations and perturbed shock relations corresponding to the each exponent of ε. Applying the regularity condition similar to GUDERLEY'S to each differential equation, the perturbed detonation velocity up to the third order of ε is obtained in an explicit algebraic form. Different from the usual perturbed solution, the obtained detonation velocity provides the time-dependency identical with that for the self-similar solution when ε→∞. Consequently, the detonation velocity profile holds in the fairly wide range of implosion and shows a reasonable coincidence with the existing experiments.
Theoretical and experimental analyses are examined on the lifting characteristics of multipleskirts GEM with outer skirt. Since the flow pattern under the GEM is complex, simple theoretical analysis is made. Present theories give reasonably good agreement with testing data. Results show the effectiveness of the outer skirt on lifting power saving, depending on arrangements of the inner skirts.