Exhaust pipe, method for optimizing and designing exhaust pipe, and engine

An exhaust pipe, comprising:

• a first exhaust pipeline, which is arranged in a first direction;
• an EGR pipeline, which is arranged in a second direction, and an input end of which is communicated with an output end of the first exhaust pipeline, an included angle θ1 between the first direction and the second direction being smaller than 60°;
• a pre-turbine pipeline, wherein the pre-turbine pipeline, the EGR pipeline and the first exhaust pipeline are located in a first plane, and the pre-turbine pipeline is arranged in a third direction;
• the pre-turbine pipeline is communicated with a middle part of the EGR pipeline, an included angle θ2 between the third direction and the second direction is smaller than or equal to 90°, and a cross-sectional diameter D of the pre-turbine pipeline is 0.2-1 times a diameter of the first exhaust pipeline;
• and
• multiple second exhaust pipelines, output ends of the multiple second exhaust pipelines being all communicated with the pre-turbine pipeline.