Aerodynamic structure with series of shock bumps
An aerodynamic structure ( 1 ) comprising a series of shock bumps ( 3 a , 3 b , 3 c ) extending from its surface. The shock bumps are distributed along a line ( 7 ) with a smaller mean angle of sweep than an unperturbed shock ( 4 ) which would form adjacent to the surface during transonic movement of the structure in the absence of the shock bumps. Instead of being distributed along the line of the unperturbed shock, the shock bumps are distributed along a line which is less swept than the mean angle of sweep of the unperturbed shock. When the structure is moved at a transonic speed; a shock forms adjacent to its surface and the shock bumps perturb the shock ( 9 ) so as to reduce its angle of sweep.
1. A method of operating an aerodynamic structure comprising a leading edge, a trailing edge and series of 3-D shock bumps extending from a surface of said structure, wherein the aerodynamic structure has a fifty percent chord line half way between the leading edge and the trailing edge, the fifty percent chord line has a first angle of sweep, each of the 3-D shock bumps have an apex positioned towards the trailing edge and aft of the fifty percent chord line, and the 3-D shock bumps are distributed along a line with a mean angle of sweep which is less than the first angle of sweep of the fifty percent chord line, wherein the method comprises:
flying the aerodynamic structure at a speed sufficient to form a shock on the wing, and
perturbing the shock at the surface with the series of 3-D shock bumps.
2. The method according to claim 1 wherein the 3-D shock bumps are aligned along the line and the perturbation of the shock is performed by the 3-D shock bumps aligned along the line.
3. The method according to claim 1 further comprising inducing with each of the 3-D shock bumps a smeared shock foot with a lambda wave pattern.
4. The method according to claim 1 wherein airflow over at least one of the 3-D shock bumps is attached during the perturbation of the shock.
5. The method of claim 1 wherein the 3-D shock bumps each correspond to a different one of points of inflection of the perturbed shock.
6. A method of perturbing a shock on an aerodynamic wing, the wing comprising a leading edge, a trailing edge and a series of three dimensional shock bumps extending from a surface of the wing, wherein the wing has a fifty percent chord line half way between the leading edge and the trailing edge, the fifty percent chord line has a first angle of sweep, each of the three dimensional shock bumps have an apex positioned between the trailing edge and the fifty percent chord line, and the three dimensional shock bumps are distributed along a line with a mean angle of sweep which is less than the first angle of sweep of the fifty percent chord line, the method comprising:
flying the wing at a speed sufficient to form a shock on the wing, and
perturbing the shock by the three dimensional shock bumps.
7. The method of claim 6 wherein the three dimensional shock bumps each correspond to a different one of points of inflections formed in the shock during the perturbation.
8. A method to perturb an aerodynamic shock attached to an aerodynamic wing, wherein the wing has a leading edge, a trailing edge, an outer surface extending between the leading edge and the trailing edge and three dimensional shock bumps extending from the outer surface of the wing, wherein the wing has a fifty percent chord line half way between the leading edge and the trailing edge, the fifty percent chord line has a first angle of sweep, each of the three dimensional shock bumps have an apex between the trailing edge and the fifty percent chord line, and the three dimensional shock bumps are aligned with a line having a mean angle of sweep less than the first angle of sweep, the method comprising:
flying the wing to form the aerodynamic shock attached to the wing, and
perturbing the shock by the three dimensional shock bumps, wherein the shock bumps cause the aerodynamic shock to have a stepped plan-form shape with points of inflection.
9. The method of claim 8 wherein the three dimensional shock bumps each correspond to a different one of the points of inflections in the shock during the perturbation.