Frequency of Hammershock Exceedances of Structural Design Parameters

摘要

The design of an intake structure for supersonic combat aircraft is highly dependent on assumptions to be defined in the early design phase and in the check stress and structural clearance phases, see ref. 1. The assumptions to be made are related mainly to the dynamic hammershock pressure wave and its dynamic behavior in terms of magnitude depending on pressure at the engine face, the shape of the intake/duct, the flight condition, the change of magnitude during its travel from the air intake to the engine along the duct to the forward intake and the effect of surge interaction in case of two neighborhood engine intake/ducts. The assumptions have to be based on an existing project and a statistical approach has to be chosen with respect to the probability of occurrence of the hammershock for flight hours of each aircraft and the complete aircraft fleet as well as the aircraft missions. Beside investigation about uncertainty the effects of dynamic response of the intake duct structure has to be carefully estimated during design.