Wake stabilization device and method for reducing the aerodynamic drag of ground vehicles

• US 7,431,381 B2
• Filed: 09/11/2006
• Issued: 10/07/2008
• Est. Priority Date: 09/15/2005
• Status: Expired due to Fees

• Current Assignee: Richard Michael Wood
• Original Assignee: Richard Michael Wood
• Inventors: Wood, Richard Michael
• Primary Examiner(s): Pedder; Dennis H.
• Assistant Examiner(s): BLACK, MELISSA ANN
• Application Number:
  US11/519,493
• Publication Number:
  US 20070089531A1
• Time in Patent Office: 757 Days
• Field of Search: 296/180.1, 296/180.2, 296/180.3, 296/180.4
• US Class Current: 296/180.1
• CPC Class Codes: B62D 35/001 For commercial vehicles or tractor-trailer combinations, e.g. caravans

Abstract

An improved method and device for the reduction of aerodynamic drag and for improved performance of bluff base vehicles by increasing the pressure on the bluff base of the vehicle by controlling the wake flow and the interaction of the wake flow with the vehicle bluff base region. An improved method and device for generating a reduction in drag force on the bluff base of a body moving through a fluid. The apparatus consists of two opposing panels attached to the bluff base and aligned approximately parallel to the side edge of the bluff base and lying in a plane that is parallel to the vehicle centerline. The drag force reduction results from controlling the flow entering the bluff base trailing wake from the left side surface, right side surface, bottom surface, and top surfaces of the vehicle. The objects and advantages also extend to other applications in which an object, body, or vehicle is moving through either a gas or a fluid.

Claims

1. An apparatus for reducing the aerodynamic drag of a body having a bluff base, a top, a bottom, and two sides, the bluff base having a left half and a right half on either side of the centerline, the apparatus comprising:

a first substantially rectangular panel;

a second substantially rectangular panel;

each of the panels having a width, length, and thickness;

wherein the panels are symmetrically positioned about the centerline of the bluff base in opposition, wherein the first panel is attached lengthwise to the right-half of the bluff base and the second panel is attached lengthwise to the left-half of the bluff base so that the surface of the panels are parallel to the sides of the body and each panel'"'"'s width extends rearward from the body bluff base creating a lengthwise trailing edge, wherein each panel is inset at substantially similar distances from the respective sides of the body and no more than about 10 percent of the body width;

wherein the width of the panels is between about 15 and 25 percent of the body width, the thickness of the panels is no more than about three inches. and the length of the panels is substantially equivalent to the vertical height of the body bluff base;

wherein each of the first and second panels defines an outer surface facing in the same direction as the corresponding side of the body and an inward surface facing the opposing panel, and each of the first and second panels are configured, when exposed to a flow of air along the body, to trap a vortex at its outer surface adjacent to the bluff base and modify the strength of the vortex;

wherein each of the first and second panels are configured, when exposed to a flow of air along the body, to trap a vertically oriented vortex at its outer surface adjacent to the bluff base, enabling the flow across the body to expand as it exits the bluff base and further enabling a substantially steady and symmetric air flow as it exits the bluff base and the trailing edges of the panels;

wherein the body is a vehicle having swinging rear doors on the left-half and the right-half of the bluff base, and further comprising a control means connected between the bluff base and each panel for maintaining each panel in an operating position and for stowing each panel when not in use;

wherein said control means for maintaining each said panel in an operating position and for stowing each panel when not in use comprises

a first spring hinge system connecting first said panel leading edge to right side swinging rear door of said vehicle,

a second spring hinge system connecting second said panel leading edge to left side swinging rear door of said vehicle,

a control means to maintain each said panel in operating position includes spring hinge torsion force and mechanical stop means for preventing movement of said panels from rotating from said operating position towards outer most edges of said rear swinging doors,

a control means includes means to allow said panels to rotate from said operating position towards inner most edges of said rear swinging door when said rear swinging doors are opened and said panels contact side surfaces of said vehicle, and

a low friction system incorporated into each said panel trailing edge and onto each said vehicle side surface at a location coincident with the area of contact between said panels trailing edge and said vehicle side surfaces when said vehicle rear swing doors are opened.

2. An apparatus for reducing the aerodynamic drag of a body having a bluff base, a top, a bottom, and two sides, the bluff base having a left half and a right half on either side of the centerline, the apparatus comprising:

a first substantially rectangular panel;

a second substantially rectangular panel;

each of the panels having a width, length, and thickness;

wherein the panels are symmetrically positioned about the centerline of the bluff base in opposition, wherein the first panel is attached lengthwise to the right-half of the bluff base and the second panel is attached lengthwise to the left-half of the bluff base so that the surface of the panels are parallel to the sides of the body and each panel'"'"'s width extends rearward from the body bluff base creating a lengthwise trailing edge, wherein each panel is inset at substantially similar distances from the respective sides of the body and no more than about 10 percent of the body width;

wherein the width of the panels is between about 15 and 25 percent of the body width, the thickness of the panels is no more than about three inches. and the length of the panels is substantially equivalent to the vertical height of the body bluff base;

wherein each of the first and second panels defines an outer surface facing in the same direction as the corresponding side of the body and an inward surface facing the opposing panel, and each of the first and second panels are configured, when exposed to a flow of air along the body, to trap a vortex at its outer surface adjacent to the bluff base and modify the strength of the vortex;

wherein each of the first and second panels are configured, when exposed to a flow of air along the body, to trap a vertically oriented vortex at its outer surface adjacent to the bluff base, enabling the flow across the body to expand as it exits the bluff base and further enabling a substantially steady and symmetric air flow as it exits the bluff base and the trailing edges of the panels;

wherein the body is a vehicle having swinging rear doors on the left-half and the right-half of the bluff base, and further comprising a control means connected between the bluff base and each panel for maintaining each panel in an operating position and for stowing each panel when not in use;

wherein said control means comprises a first hinge system connecting first said panel leading edge to right side swinging rear door of said vehicle, a second hinge system connecting second said panel leading edge to left side swinging rear door of said vehicle;

a first pneumatic spring system connecting first said panel inward facing surface to right side swinging rear door of said vehicle,

a second pneumatic spring system connecting second said panel inward facing surface to left side swinging rear door of said vehicle,

said first pneumatic spring system is rotationally attached to inward facing surface of said right side panel and said second pneumatic spring system is rotationally attached to inward facing surface of said left side panel,

said first pneumatic spring system is rotationally attached to right side rear swinging door of said vehicle and said second pneumatic spring system is rotationally attached to left side rear swinging door of said vehicle,

a control means to maintain each said panel in the operating position includes compression from said pneumatic springs and mechanical stop means for preventing movement of said panels from rotating from said operating position towards outer most edges of said rear swinging doors,

a control means includes means to allow said panels to rotate from said operating position towards the inner most edges of said rear swinging doors when said rear swinging doors are opened and said panels contact side surfaces of said vehicle, and

a low friction system incorporated into each said panel trailing edge and onto each said vehicle side surface at a location coincident with the area of contact between said panels trailing edge and said vehicle side surfaces when said vehicle rear swing doors are opened.

3. An aerodynamic drag reduction device for use on a bluff base vehicle having a roll-up rear door encompassing the majority of the bluff base surface of the vehicle, the device comprising:

a pair of rear support plates rotationally attached to the side edges of the vehicle bluff base;

a pair of rearward extending panels, each attached to one of the rear support plates;

wherein the panels are positioned substantially symmetrically about the bluff base centerline and are substantially parallel to each other and to the side edges of the bluff base;

wherein the panels have a thickness of up to 3 inches and extend rearward a distance equal to each other and 15 to 25 percent of the body width;

wherein the panels have a length that is substantially similar to the vertical height of the bluff base;

wherein the panels are inset from the side edges of the vehicle bluff base at a distance of about 0 to 10 percent of the body width;

whereby the panels trap vortices on their outside surfaces in order to reduce drag.

4. The drag reduction device of claim 3, wherein the trailing edge of each panel is comprised of notches having a substantially rectangular shape, with each notch having a depth, length, space to the next adjacent notch, and inset from the panel edge, such that the dimensions of each are no more than 10% of the length of the panel.

5. The drag reduction device of claim 3, wherein the trailing edge of each panel is comprised of sawteeth having a substantially triangular shape, with each sawtooth having a depth, length, and inset from the panel edge, such that the dimensions of each are no more than 10% of the length of the panel.

6. The drag reduction device of claim 3, wherein the trailing edge of each panel is comprised of curves, with each curve having a depth, length, and inset from the panel edge, such that the dimensions of each are no more than 10% of the length of the panel.

7. The drag reduction device of claim 3, further comprising a stall strip attached to the trailing edge of each panel, wherein the thickness of the stall strip is no more than the panel thickness and the width of the stall strip is no more than 10% of the width of the panel.

8. The drag reduction device of claim 3, further comprising a gurney flap attached to the trailing edge of each panel, wherein the thickness of the gurney flap is no more than the panel thickness and the width of the gurney flap is no more than 10% of the width of the panel.

9. The drag reduction device of claim 3, wherein the leading edge of each panel is comprised of vent slots having a substantially rectangular shape, with each notch having width which is no more than 10% of the width of the panel.

10. The drag reduction device of claim 3, further comprising a plurality of micro vortex strakes attached to the side of each panel facing away from the vehicle center line and along the trailing edge of each panel, wherein the micro vortex strakes have a width W_VG of no more than 1% of the width of the panel, a length L_VGof no more than 5% of the width of the panel, space to the next adjacent strake S_VG of no more than 5% of the width of the panel, and are angled downward from the leading edge of the panel to the trailing edge at an angle α

_VG of no more than 10% from horizontal.

11. The drag reduction device of claim 3, wherein the support plates swing outward from the vehicle bluff base, and wherein the device further comprises hinges connecting each panel to the support plates.