Flow field calculation method for plume of multi-nozzle rocket or missile

The invention discloses a flow field calculation method for a plume of a multi-nozzle rocket or missile. The flow field calculation method comprises the following steps: constructing a grid for an internal combustion flow field calculation area of only one engine; calculating an internal combustion flow field of a rocket or missile engine to obtain detailed distribution of intrinsic parameters of the engine; constructing a grid for a flow field calculation area of the plume of the rocket or missile; calculating the flow field of the plume of the rocket or missile through research of the influence of reignition or different chemical reaction mechanisms on flow field characteristics of the plume of the rocket or missile. With adoption of the method, calculation is accurate, the influence of chemical reactions and internal combustion states of the engine can be considered sufficiently, the method can be used for researching the influence of reignition on the flow field characteristics of the plume, calculating grid construction is facilitated, all that is needed is to perform simulating calculation on the internal combustion flow field of one engine, and repeated calculation is avoided, so that large quantities of resources can be saved.