secondary-flow-in-the-intake-ductRampCowlingRampCowlingSpeed vectors of theairflow in the plane ofthe engine intakePressure distribution(isobaric) in theairflow in the plane ofthe engine intakeFlow at cowling inletSide viewTop viewAirflowbreakaway(stall)HighLowCentrifugal forceRampCowlingRampCowling Direction ofrotor rotationSpeed vectors of theairflow in the plane ofthe engine intakePressure distribution(isobaric) in theairflow in the plane ofthe engine intakeInflowInflowInflowInflowFlow at cowling inletSide viewTop viewAirflowbreakaway(stall)HighLowSecondaryflowAreas of low flowenergyDirection ofrotor rotationRampCentrifugal forceAreas of low flowenergySide viewTop viewTypical secondary flow in the intake duct of aa modern fighter aircraft. Supersonic flight, smallinflow angleSubsonic flight, largeinflow angle