Variable-expansion-ratio spray pipe of single-chamber double-thrust solid rocket engine

The invention provides a variable-expansion-ratio spray pipe of a single-chamber double-thrust solid rocket engine. The variable-expansion-ratio spray pipe comprises an engine rear end socket, a rear end socket inner heat insulation layer, a long tail pipe, a long tail pipe inner heat insulation layer, a spray pipe shell, a throat liner assembly and a spray pipe expansion section. The nozzle expansion section is of a segmented structure with a front section and a rear section, and the rear section is made of a metal material which is easy to ablate. When the high pressure intensity of the single-chamber double-thrust engine is converted into the low pressure intensity, the expansion ratio of the spray pipe is automatically converted to adapt to the change of the pressure intensity of an outlet of the spray pipe, and the expansion ratio requirement for complete expansion of the single-chamber double-thrust solid rocket engine under different thrust sections is met. 本申请提供一种单室双推力固体火箭发动机可变扩张比喷管，包括发动机后封头、后封头内绝热层、长