Apparatus and method for passive purging of micro-perforated aerodynamic surfaces

A purging system for a porous skin having an internal suction cavity, the porous skin including a plurality of pores fluidly connecting the suction cavity to an external atmosphere, the purging system comprising:

• an air scoop configured to capture an external flow of the external atmosphere;
• and
• a diffuser fluidly connecting the air scoop to the suction cavity and being configured to duct the external flow to the suction cavity for discharge through the pores;
• the air scoop comprising a door assembly including:
• a first door;
• and
• a second door pivotably mounted to the first door;
• wherein:
• each one of the first and second doors is pivotable between open and closed positions and defining an opening when moved to the open position;
• the openings of the first and second doors facing in opposite directions;
• the first door opening being configured to capture the external flow for ducting through the diffuser toward the suction cavity for discharge through the pores into the external atmosphere;
• the second door being configured to draw the external flow through the pores and into the suction cavity for ducting through the diffuser for discharge through the second door opening into the external atmosphere.

A method of purging a laminar flow control system having a porous skin defining a leading edge of an airfoil oriented at a sweep angle, the porous skin having a suction cavity fluidly connected to an external atmosphere through a plurality of pores formed in the porous skin, the method comprising the steps of:

• deploying an air scoop into an external flow of the external atmosphere;
• ducting the external flow from the air scoop into the suction cavity;
• generating a cavity pressure overcoming surface tension in liquid trapped in the pores;
• and
• purging the pores by discharging the ducted flow through the pores.

An aircraft comprising:

• a purging system for a porous skin of an airfoil defining a leading edge of a swept airfoil and having an internal suction cavity, the porous skin including a plurality of pores fluidly connecting the suction cavity to an external atmosphere, the purging system including:
• an air scoop disposable into an external flow of the external atmosphere;
• and
• a diffuser fluidly connecting the air scoop to the suction cavity and being configured to duct the external flow to the suction cavity to generate cavity pressure for discharge through the pores;
• the leading edge having a sweep angle oriented such that the cavity pressure overcomes surface tension in liquid trapped in the pores.

An aircraft comprising:

• a purging system for a porous skin of an airfoil having an internal suction cavity, the porous skin including a plurality of pores fluidly connecting the suction cavity to an external atmosphere, the purging system including:
• an air scoop disposable into an external flow of the external atmosphere;
• and
• a diffuser fluidly connecting the air scoop to the suction cavity and being configured to duct the external flow to the suction cavity for discharge through the pores;
• the air scoop comprises a door assembly including:
• a first door;
• and
• a second door pivotably mounted to the first door;
• wherein:
• each one of the first and second doors is pivotable between open and closed positions and defining an opening when moved to the open position;
• the openings of the first and second doors facing in opposite directions;
• the first door opening being configured to capture the external flow for ducting through the diffuser toward the suction cavity for discharge through the pores into the external atmosphere;
• the second door being configured to draw the external flow through the pores and into the suction cavity for ducting through the diffuser for discharge through the second door opening into the external atmosphere.