Vortex strake device and method for reducing the aerodynamic drag of ground vehicles

An aerodynamic drag reduction device for a vehicle comprising:

• a plurality of small surfaces on the aft exterior surface of said vehicle,
• said plurality of said small surfaces are symmetrically positioned about said vehicle principle longitudinal axis,
• said plurality of said small surfaces are separated by an approximately equally space around the majority of the circumference of said vehicle,
• each of said small surfaces are at approximately the same longitudinal position on said vehicle,
• each of said small surfaces extends outward from the exterior surface of said vehicle a distance equal to the local boundary layer thickness on said vehicle in the region of said small surfaces,
• each of said small surfaces extends an equivalent distance perpendicularly outward from the exterior surface of said vehicle,
• each of said small surfaces that are adjacent to one another on either the right or left side of said vehicle are substantially parallel to one another,
• each of said small surfaces has a forward most edge that is pointed, each of said small surfaces are thin with a maximum thickness of 1.0 inches,
• each of said small surfaces has a minimum length equal to 5 times the local boundary layer thickness on said vehicle in the region of said small surfaces,
• each of said small surfaces is inclined a minimum of 10° to the local flow direction measured on said vehicle surface in the region of said small surfaces,
• each of said small surfaces being separated from and substantially parallel to one another allow each said small surface to generate a vortex of equivalent strength thereby the flow passing along the external surface of said vehicle in the region of and aft of said small surface is energized and thereby the external trailing wake flow of the vehicle is changed to a substantially steady symmetric wake flow field and drag is reduced.

An aerodynamic drag reduction device for use on a vehicle comprising:

• a plurality of surfaces attached to top and side exterior surfaces of the vehicle and toward the aft of the vehicle;
• wherein the surfaces are substantially equally spaced apart from each other and positioned about a principle longitudinal axis of the vehicle;
• wherein the surfaces each extend outward from the surface of the vehicle at a length substantially equal to the local boundary layer thickness on the vehicle in the region of the surfaces;
• and
• wherein the surfaces are substantially parallel to each other and are positioned at an angle of at least 10° to the airflow so that the surfaces generate a vortex of sufficient strength to energize the airflow passing along the external surface of the vehicle in the region of and aft to the surfaces to such a degree that the vehicle has a substantially steady symmetric wake flow field.