The invention discloses an active heat reduction design method for an aircraft
rudder shaft gap thermal environment, which comprises the following steps: calculating a
heat flow value of a head stationary point, selecting the most harsh moment of incoming flow to carry out thermal environment numerical
simulation on a whole aircraft, and obtaining a multiple relationship between a
rudder shaft gap local
heat flow peak value and an aircraft head
heat flow peak value; acquiring the change condition of a
rudder shaft gap local heat flow
peak value along a trajectory by the
multiple relation, determining a time period in which rudder shaft
thermal protection design needs to be carried out according to the change condition, determining a laminar
flow time period in the time period by a transition criterion, calculating the maximum Reynolds number in the laminar
flow time period, and calculating the maximum Reynolds number under the maximum Reynolds number. When the thickness of the boundary layer is 1 / x of the height of the rudder shaft gap, the corresponding object-surrounding
characteristic length is obtained, and finally, the
diamond-shaped forced transition tape is arranged at the position away from the
front edge of the rudder by the object-surrounding
characteristic length, so that the whole rudder shaft gap is in turbulent flow under the working condition that the thermal environment is relatively harsh, and the thermal environment heat flow peak value of the rudder shaft gap is greatly reduced.