초록 ▼

The present invention relates to the improvement of the aerodynamic properties of bluff-body shaped ground vehicles. A least one air modulator is assembled on the vehicle to modify an air flow around the vehicle, such that the drag on the vehicle is decreased. Each air modulator has an array of open

The present invention relates to the improvement of the aerodynamic properties of bluff-body shaped ground vehicles. A least one air modulator is assembled on the vehicle to modify an air flow around the vehicle, such that the drag on the vehicle is decreased. Each air modulator has an array of openings including a number of openings, which are arranged next to one another along an essentially straight line. A control unit controls the at least one air modulator output oscillating air from each opening such that air vortices are formed outside the opening. The at least one air modulator is arranged on the vehicle, such that these air vortices have axes that, in proximity to the opening, are essentially perpendicular to a forward driving direction of the vehicle.

대표청구항 ▼

The invention claimed is: 1. A ground vehicle having a body with an outer surface comprising a general front surface, a main upper surface, a bottom surface, two side surfaces and a rear surface, the vehicle having at least one airflow control system comprising: at least one air modulator having an

The invention claimed is: 1. A ground vehicle having a body with an outer surface comprising a general front surface, a main upper surface, a bottom surface, two side surfaces and a rear surface, the vehicle having at least one airflow control system comprising: at least one air modulator having an array of openings including a number of openings which are arranged next to one another along an essentially straight line, the air modulator of each of the at least one system is arranged on the vehicle with the array of openings having an orientation relative to the outer surface such that when the vehicle travels at a particular speed an amount of vortex shedding behind the rear surface is lower than if the vehicle had traveled at this speed without the at least one system; and a control unit adapted to control the air modulator to output oscillating air from each opening such that air vortices are created outside the opening where the air vortices have spin axes that are essentially parallel to the essentially straight line, wherein the vehicle comprises at least one flow amplification surface which is arranged on the vehicle downstream of the at least one air modulator relative to the air flow, and the at least one flow amplification surface is adapted to augment the air vortices, the flow amplification surface extending rewardly a distance, Λ, relative to the rear surface and the air modulator is arranged relative to the flow amplification surface such that the array of openings of the air modulator is positioned a distance, Λc, downstream of a flow separation line adjacent to the rear surface where flow separation would have occurred if no air vortices had been generated, resulting in that a surface over which air vortices from the air modulator may be amplified extends a distance, XTE, from the array of openings, where XTE=Λ−Λc. 2. The ground vehicle according to claim 1, wherein the array of openings includes a number of slots, each slot having a width and a length dimension where the length dimension is several factors larger than the width dimension, the slots are arranged next to one another along an essentially straight line parallel to each slot's length dimension. 3. The ground vehicle according to claim 2, wherein the slot width dimension lies in an interval from approximately 0.1 mm to approximately 10 mm. 4. The ground vehicle according to claim 2, wherein the slot length dimension lies in an interval from approximately 30 mm to approximately 300 mm. 5. The ground vehicle according to claim 1, wherein the array of openings includes a number of holes, each hole having an opening dimension in an interval from approximately 0.1 mm to approximately 10 mm. 6. The ground vehicle according to claim 1, wherein the at least one air modulator comprises a tubular element on which the array of openings is arranged, the tubular element including a modulating member extending along a substantial portion of an interior of the tubular element, the modulating member has a polygon shaped cross section, and the modulating member is rotatable around a symmetry axis thereof in response to a control signal from the control unit so as to produce the oscillating output of air. 7. The ground vehicle according to claim 1, wherein the at least one air modulator comprises at least one diaphragm arranged in a cavity adjoining at least one of the openings in the array of openings, each of the least one diaphragm is adapted to vibrate in response to a control signal from the control unit so as to produce the oscillating output of air. 8. The ground vehicle according to claim 1, wherein the at least one air modulator comprises at least one valve arranged to emit an active airflow from a compressed air system in response to a control signal from the control unit so as to produce the oscillating output of air. 9. The ground vehicle according to claim 1, wherein the control unit is adapted to control an air oscillating frequency of the air exiting from the array of openings in a range from approximately 5 Hz to approximately 500 Hz. 10. The ground vehicle according to claim 1, wherein the at least one air modulator is arranged essentially along an intersection line between the main upper surface and the rear surface. 11. The ground vehicle according to claim 1, further comprising a second air modulator, wherein the second air modulator is arranged essentially along an intersection line between the general front surface and the main upper surface. 12. The ground vehicle according to claim 1, wherein the vehicle comprises at least two airflow control systems of which a first system has a first air modulator arranged essentially along a first intersection line between a first side of the side surfaces and the rear surface, and a second system has a second air modulator arranged essentially along a second intersection line between a second side of the side surfaces and the rear surface. 13. The ground vehicle according to claim 1, wherein the at least one air modulator is arranged on the vehicle with the essentially straight line of the respective array of openings oriented essentially perpendicular to a forward driving direction of the vehicle. 14. The ground vehicle according to claim 13, wherein the at least one air modulator is arranged on the vehicle with the array of openings oriented such that each opening emits air in a main direction having an angle to the forward driving direction in an interval from approximately 90 degrees to approximately 175 degrees. 15. The ground vehicle according to claim 1, wherein the control unit is adapted to: receive a velocity signal representing a speed of the vehicle; and control the air modulator in response to the velocity signal, such that a relatively high vehicle speed results in a comparatively high output air oscillation frequency and a relatively low vehicle speed results in a comparatively low output air oscillation frequency. 16. The ground vehicle according to claim 1, wherein the control unit is adapted to: receive a velocity signal representing a speed of the vehicle; and control the air modulator in response to the velocity signal, such that a peak-to-peak amplitude of a speed of the air exiting from each opening is equivalent to approximately 0.5 times to approximately 10 times the speed. 17. The ground vehicle according to claim 1, wherein the vehicle comprises a compressed air system which is connected to the air modulator of at least one of the at least one air flow control system for supply of an active air flow to the array of openings. 18. The ground vehicle according to claim 1, wherein the distance Λc lies in an interval from about 0.01Λ to 0.60Λ. 19. The ground vehicle according to claim 1, wherein the distance Λc lies in an interval from about 0.05Λ to 0.30Λ.