Radial air inlet distortion restraining grating of ramjet engine and designing method of radial air inlet distortion restraining grating

The invention provides a radial air inlet distortion restraining grating of a ramjet engine and a designing method of the radial air inlet distortion restraining grating, and relates to a ramjet engine. The radial air inlet distortion restraining grating of the ramjet engine is provided with a first distortion restraining grating plate and a second distortion restraining grating plate which are stacked together coaxially, wherein the first distortion restraining grating plate consists of flexible spiral plates which surround a center drum; the second distortion restraining grating plate consists of radial scrolls of which the number is fixed; the geometric position of the second distortion restraining grating plate is fixed relative to the ramjet engine; and the first distortion restraining grating plate and the second distortion restraining grating plate are arranged on an inlet of a circular combustion chamber of the ramjet engine. The designing method of the radial air inlet distortion restraining grating comprises the following steps of determining a maximum radial distortion value DIS_R according to incoming flow conditions of different aircrafts; determining the minimum area ARmin of a ring for restraining the maximum radial distortion value DIS_R; determining the number of turns of the spiral plates of the first distortion restraining grating plate; and determining the number of the radial scrolls of the second distortion restraining grating plate. The number of the turns of the spiral plates is equal to the quotient of the area of the circle of the inlet of the circular combustion chamber and the ARmin, and the number of the radial scrolls is three times greater than that of the spiral plates of the first distortion restraining grating plate.