1. Technical Field
The present invention relates to an intake structure of an aircraft and, particularly, relates to a technique that is useful in suppressing a boundary layer from flowing into an intake.
2. Related Art
In designing a structure of an intake (an air intake) of an aircraft, the manner in which a boundary layer, which develops in front of the intake and on a surface of an airframe, is dealt with is important. Since the boundary layer is an airflow that has lost its energy due to friction with the surface of the airframe, when the boundary layer flows into the intake and is supplied to the engine, problems such as a decrease in engine performance occur.
Regarding the technique of preventing the boundary layer from flowing into the intake, a technique has been known for a long time in which a diverter (a wall screening the boundary layer) is provided between a gap, which is about the thickness of the boundary layer, provided between the intake and the surface of the airframe. While the technique employing the diverter is capable of allowing only the airflow outside the boundary layer to flow into the intake, problems such as decrease in airframe performance due to the weight and air resistance of the diverter itself occur.
Accordingly, in recent years, as a technique for removing the inflow of the boundary layer without resorting to a diverter, a diverterless intake in which a bump is provided on a surface of the airframe in front of the intake has been proposed and is in practical use (see U.S. Pat. No. 5,779,189, for example). In the above diverterless intake, the boundary layer is removed to the side of the intake with a pressure gradient created on the bump such that the boundary layer is suppressed from flowing into the intake.