Design method of three-dimensional variable cross-section unilateral expansion nozzle with large lateral expansion angle

The invention belongs to the technical field of aero-engine nozzles, and particularly relates to a design method of a three-dimensional variable cross-section unilateral expansion nozzle with a large lateral expansion angle. Comprising the steps of 1, obtaining aerodynamic parameters and size constraint parameters of a spray pipe; 2, the side wall of the spray pipe is defined as a linear structure, and a lateral expansion angle is calculated; 3, defining the lower wall surface of the spray pipe as a linear structure, and calculating an expansion angle of the lower wall surface; 4, according to the shortest length spray pipe theory and a unilateral expansion spray pipe design method considering lateral expansion, a spray pipe upper wall surface configuration is obtained; 5, the upper wall face and the lower wall face of the spray pipe are directly truncated according to the length of the upper wall face of the spray pipe, a reference spray pipe configuration is obtained, whether the height of the upper wall fa