Surface plasma discharge for controlling leading edge contamination and crossflow instabilities for laminar flow

An aircraft, comprising:

• an airfoil having a leading edge whereby air flow interacts with the leading edge to creates a first boundary layers, characterized by a Poll Reynolds number, along an attachment line and a second boundary layer, characterized by a cross flow Reynolds number, along diverging streamlines, and
• plasma discharge elements distributed along the attachment line, said plasma discharge elements being adapted to generate a plasma to volumetrically heat the first and second boundary layers, thereby maintaining the Poll Reynolds number below a first critical value along the attachment line and maintaining the cross flow Reynolds numbers below a second critical values along the streamlines to delay the onset of turbulent flow.

A method of delaying the transition to turbulent flow over an air foil having a leading edge, whereby air flow interacts with the leading edge to create a first boundary layer, characterized by a Poll Reynolds number, along an attachment line and a second boundary layer, characterized by a cross flow Reynolds number, along diverging streamlines, comprising the steps of:

• generating a plasma along the attachment line to volumetrically heat the boundary layers, thereby maintaining the Poll Reynolds number below a first critical value along the attachment line and maintaining the cross flow Reynolds number below a second critical value along the streamlines to delay the onset of turbulent flow.

A method of delaying the transition to turbulent flow over an airfoil having a leading edge, wherein air flow interacts with the leading edge to create a first boundary layer, characterized by a Poll Reynolds number, along an attachment line and a second boundary layer, characterized by a cross flow Reynolds number, along diverging streamlines, comprising the steps of:

• generating a plasma along the attachment line to volumetrically heat the first and second boundary layers;
• sensing the laminar or turbulent state of the air flow downstream for the plasma discharge, and
• controlling the plasma discharge, thereby maintaining the Poll Reynolds number below a first critical value along the attachment line and maintaining the cross flow Reynolds number below a second critical value along the streamlines to delay the onset of turbulent flow.