System for controlling the aerodynamic drag of a motor-vehicle, adapted to cause separation of the boundary layer at a predetermined area of the motor-vehicle body, by the use of passive jets, and motor-vehicle provided with this system

摘要

A motor vehicle comprises a system for controlling the aerodynamic drag thereof by causing detachment of the boundary layer at a predetermined area of a part of the body thereof. The system comprises at least one component of the structure of the motor vehicle constituting a separate element rigidly connected to the structure, wherein the component defines an outer wall of the motor vehicle, wherein the outer wall (R) is made porous, with an orderly distribution of pores or holes (p).;The porous wall (R) closes externally a chamber obtained within the component (2, 3, 4) of the structure of the motor vehicle in such a way that, when the motor vehicle is travelling, a first part of the pores or holes (p) situated in an area of the aerodynamic field of the vehicle with higher relative pressure enables part of the flow of air that laps the vehicle to enter the chamber, whereas a part of the pores or holes (p) situated in an area of the aerodynamic field of the vehicle with lower relative pressure functions as outlet for the flow of air from the aforesaid chamber towards the outside of the vehicle in such a way as to generate jets of air that cause detachment of the boundary layer.;The position of the pores or holes (p) situated in an area of the aerodynamic field of the vehicle with lower relative pressure is chosen so as to determine detachment of the boundary layer in a desired area.