HRP20020312A2 - Moving vehicle active aerodynamic resistance reduction system - Google Patents

Description

The field of technology

According to the International Patent Classification (IPC), the invention can be classified into the following classes:

B60B 21/00 Rims

B60B 21/02 Characteristic in cross-section

B60B 3/10 Wheels with openings to imitate spoked wheels

Technical problem

The technical problem that is solved by this invention consists in the design solution of actively directing the air flow from the space between the bottom of the vehicle, the front wheels and the road to the outside, and actively directing the air flow into the negative pressure zone that exists immediately behind the vehicle in motion, with the aim of reducing the aerodynamic resistance of the vehicle in motion /aerodynamic buoyancy force and forces resulting from the slowed down flow of the air stream that occur in the space between the bottom of the moving vehicle, the wheels and the road and forces resulting from the negative pressure in the zone immediately behind the moving vehicle/, assuming that make changes in the vehicle construction, namely:

A. Basic changes:

- applied wheels with a rim designed as a propeller, which turns the rim into an axial air turbine that produces a forced flow of air in the direction from the inside to the outside for the front wheels, or from the outside to the inside for the rear wheels;

- moves the axis of the rear wheels towards the end of the vehicle (actually behind the basic volume of the vehicle) and adjusts the wheel suspension accordingly;

- constructs rims with the largest possible diameter (along with low-profile tires to make the active part of the system as efficient as possible), with the rear rims being far larger in diameter (25" or more), all with the aim of increasing the activated volume of air, thus efficiency.

B. Additional changes:

- redesign the brakes and wheel suspension system so that the air flow through the rim is not obstructed;

- raise the tail of the vehicle;

- aerodynamically shape all suspension and transmission elements located under the vehicle;

- reduce the roughness of the bottom of the vehicle.

State of the art

Well-known passive systems imply shaping the vehicle as close as possible to the ideal aerodynamic shape and the use of a "spoiler" system that (often unsuccessfully) passively directs the air flow and tries to influence the adhesion force of the vehicle's wheels to the road. The "tail" spoiler makes a bit more sense because it fills the volume of the tail of the airfoil that is missing in the form of a "truncated" droplet (underpressure zone behind the vehicle) and reduces the resultant force opposite to the direction of movement of the vehicle since the volume of the spoiler approaches the center of the zone and the forces are partially canceled.

Description of the solution to the technical problem

The primary goal of the invention is to reduce the aerodynamic resistance of the vehicle in motion.

The secondary goal of the invention is to increase the stability and controllability of the vehicle in motion and to reduce fuel consumption, as well as to improve the performance of the vehicle (maximum speed, acceleration).

The accompanying drawings, which are included in the description and form part of the description of the invention, illustrate the method of carrying out the invention and help explain the basic principles of the invention.

If we observe the movement of a body - a vehicle through the air medium (Figure 1), we see that the speed of the air flow is higher on the upper surface of the vehicle than on the lower surface, which results in the appearance of the force of aerodynamic lift. The reason for the above is the greater resistance to the flow of air through the zone of slowed air flow in the space between the bottom of the vehicle, the wheels and the pavement (due to the influence of the static pressure component, the roughness of the surface of the vehicle bottom, the resistance of the suspension assemblies, steering assemblies, etc., the influence of the roughness of the pavement, etc. ). The effect of the force of aerodynamic buoyancy on the vehicle in motion is a reduction in the force of adhesion of the wheels to the road, which increases the losses due to slippage of the drive wheels and reduces the controllability of the vehicle.

So, one part of the technical problem that we are looking at is the force of aerodynamic buoyancy and the force of resistance to the flow of air that occur in the space between the bottom of the vehicle in motion, the wheels and the road.

If we analyze the flow of the medium (air) through the zone of slowed air flow in the space between the bottom of the vehicle, the wheels and the road, with some simplifications, and if we ignore the influence of air compressibility and friction between air particles, we can view the situation as a laminar flow of the medium through two Bernoulli tubes ( Figure 2), where the sides of these pipes are made of wheels, and apply Bernoulli's law:

pdynam + pstat = const = p

ρv2/2 + pstat = const = p

Thus, the sum of the dynamic pressure - ρv2/2 and the static pressure - pstat is constant, which means that it is equal to the total pressure.

As the real air flow through the space between the bottom of the vehicle, the wheels and the pavement is not laminar but vortex, the speed of the flow slows down, which is why the dynamic component decreases, and the static component with a vector directed perpendicular to the direction of motion increases. As one side of the observed system is fixed (road), the static pressure component directed perpendicular to the road is actually added (minus the air compressibility coefficient) to the static pressure component directed perpendicular to the bottom of the vehicle. In other words, an "air cushion" is created under the vehicle.

The consequence of the above are two equally directed vector forces (opposite to the earth's gravity vector) - the force of aerodynamic buoyancy and the resultant force as the sum of the vectors of the static component of pressure when the air current flows through the space between the bottom of the vehicle, the wheels and the pavement.

So, if we manage to increase the speed of air flow in the space between the bottom of the vehicle, the wheels and the road, and on the other hand, if we reduce the volume of air flowing through the same space, the dynamic pressure component will increase and the static component will decrease. The consequence of this on the moving vehicle is twofold:

• both pressure components and their impact on the vehicle in motion are reduced, and thus the work required to overcome this resistance.

• the speed of the flow in the zone between the bottom of the vehicle and the road surface is increased, due to which the force of aerodynamic buoyancy and its influence on the vehicle in motion are reduced (losses due to slippage of the drive wheels and reduced vehicle controllability).

Here I must emphasize that the above mentioned refers to the front Bernoulli tube, while the situation with the rear one is somewhat different, so let's further analyze the motion of the body - the vehicle through the air medium.

If we observe any volume of water in a state when no force is acting on it (e.g. weightlessness), it will take the shape of a sphere, which is a consequence of the action of cohesion forces between water molecules and surface tension forces.

If we let one such sphere fall freely under the action of gravity through an air medium, the sphere deforms more and more in proportion to the speed of movement and takes the form of a droplet, which is the effect of the forces of aerodynamic resistance, on the one hand, and the forces of cohesion and surface tension (Figure 3) on the other side.

The droplet thus extends more and more until the moment when the cohesive forces are overcome and part of the volume separates and forms a new droplet. This process continues until the moment when the forces are balanced, and such droplets continue to move uniformly in the same direction.

If we now compare the motion of one such droplet with another body of the same mass - m and projection surface on a plane perpendicular to the direction of motion - A and of the same shape, but made of a solid with the same surface roughness as a water droplet, we will see that both bodies move in the same way speed (the same force acts on both bodies and they move uniformly in the same direction), which means that the aerodynamic resistance - R is the same for both bodies in motion (Figure 4).

In the following example, let's compare the motion of the same body, i.e. a rigid body in the shape of a droplet that moves uniformly in a direction through an air medium, with another body of the same mass - m and a projection surface on a plane perpendicular to the direction of motion - A and the same surface roughness, but which differs in shape only because it is a "trunk" - it lacks the "tail" of the droplet form. We will see that the body in the shape of a "truncated droplet" moves more slowly, which means that it has greater aerodynamic resistance. The size of the aerodynamic resistance of the body in the form of a "truncated droplet" - R2 will be proportional to the sum of the aerodynamic resistance of the body of the form of a regular droplet - R1 and the weight of water of a volume equal to the volume of the part of the form of a regular droplet that is missing from the body of the form of a "truncated droplet" - S (Figures 3 and 4) since the force required to produce the deformation of the form missing from the body of the "truncated droplet" form is proportional to the weight of that volume.

R2 ~ R1 + a m

R2 ~ R1 + a ρleads V

R2 ~ R1 + a ρlead Sh/3

Where R2 is the aerodynamic resistance of the body in the form of a "truncated" droplet; R1 - aerodynamic resistance of the body in the form of a regular droplet; a - acceleration (earth gravity); m - the mass of the volume of the part of the regular droplet form that is missing in the "truncated" droplet form; ρvode - density of water; V - the volume of the part of the form of a regular droplet that is missing in the form of a "truncated" droplet (simplified cone); S - the surface of the tail part of the "truncated" form of the droplet (cone base); h - height of the part of the form of a regular droplet that is missing in the form of a "truncated" droplet (cone height); Sh/3 - volume of the cone.

By optimizing the previous formula, with some experimental support, it would be possible to mathematically define Cx, the coefficient of aerodynamic drag:

Cx ~ R2 / R1 + a ρleads V

So, behind the body of the "truncated droplet" form that moves through the air medium, there is a resistance force opposite to the direction of motion, which is proportional to the weight of the volume of water that is missing in the body of the "truncated droplet" form compared to the body of the regular droplet form. The forces that we can call "forces of resistance of the truncated tail of the airfoil" are directed towards the center of the imaginary volume of the missing airfoil tail, acting on the surface - with a vector opposite to the direction of the body's movement, and cause a vortex in the air in that zone. All this increases resistance to body movement.

So, the second problem we are observing is the "forces of resistance of the truncated tail of the airfoil", i.e. the resultant force opposite to the direction of the vehicle's movement that occurs in the zone behind the vehicle in motion, and is the result of negative pressure due to the non-ideal shape of the vehicle's airfoil.

If we bring an additional volume of the medium (air current) into the zone behind the body moving through the air (or any other) medium, we will reduce the "resistance forces of the truncated tail of the airfoil" and the resultant force of resistance to movement. The aforementioned is achieved by the System of active reduction of the resistance to the movement of the vehicle.

The essence of the invention is to remove the largest possible volume of media (air in the case of road vehicles) from the zone of slowed air flow in the space between the bottom of the vehicle and the roadway, in proportion to the speed of the vehicle's movement, i.e. to bring the largest possible volume of media to the zone behind the moving vehicle , also directly proportional to the speed of the vehicle.

The novelty of the solution is the active direction of the air current flow from the space between the bottom of the vehicle, the front wheels and the road to the outside, and the active direction of the air current to the negative pressure zone that exists immediately behind the moving vehicle. The reduction of the vehicle's aerodynamic resistance is achieved by a rim designed in the shape of a propeller (1) (picture 5), which adds another function to the wheel.

So, in addition to the role of converting the circular rotation of the axle into straight-line motion of the vehicle and transferring the engine's power to the road, this wheel with a rim designed as a propeller also becomes an axial air turbine /blades (2)/ which produces a forced air flow in the direction from the inside to the outside at the front wheels, that is, from the outside to the inside for the rear wheels (Figure 6).

This increases the speed of air flow in the zone of slowed air flow between the front wheels, which reduces the force of aerodynamic lift and its impact on the vehicle in motion, and reduces both pressure components and their impact on the vehicle in motion, as well as the work required to overcome them.

On the other hand, by introducing an additional volume of air into the zone behind the vehicle in motion, we reduce the "force of resistance of the truncated tail of the airfoil" and the resulting force of resistance to movement and the swirling of the medium.

It should be emphasized here that the usability of the rim (1) is maximal because the rotation, which is the basic function of the wheel, is used, and all losses and resistances have already been calculated in this action.

The construction of the rim must meet the requirement of maximum air outflow from the zone of slowed air flow in the space between the bottom of the vehicle, the front wheels and the road, and maximum air inflow into the underpressure zone that occurs behind the vehicle in motion.

The basic guidelines in vehicle construction based on the principles stated here are (Figure 7):

• apply wheels with a rim designed as a propeller, whereby the rim also becomes an axial air turbine that produces forced air flow in the direction from the inside to the outside for the front wheels, or from the outside to the inside for the rear wheels;

• move the axis of the rear wheels towards the end of the vehicle (actually behind the basic volume of the vehicle) and adjust the wheel suspension accordingly;

• apply rims with the largest possible diameter (along with low-profile tires to make the active part of the system as efficient as possible), with the rear rims being much larger in diameter (25" or more), all with the aim of increasing the activated air volume;

• redesign the brakes and wheel suspension system so as not to obstruct the air flow through the rim;

• raise the tail of the vehicle;

• aerodynamically shape all suspension and transmission elements located under the vehicle;

• reduce the roughness of the bottom of the vehicle.

Claims (3)

1. System of active reduction of the aerodynamic resistance of the vehicle in motion, characterized by the fact that the vehicle contains: a pair of front wheels (3) with rims containing vanes that direct the flow of air from under the vehicle to the outside during the vehicle's movement, and a pair of rear wheels (4) with rims containing vanes that direct the flow of air from the outside under and behind the vehicle during vehicle movement. 2. System of active reduction of the aerodynamic resistance of the vehicle in motion according to the 1st claim, characterized in that the rim (1) contains vanes (2), which during the movement of the vehicle direct the flow of air under the vehicle outwards. 3. System of active reduction of the aerodynamic resistance of the vehicle in motion according to claim 1, characterized in that the rim (1) contains vanes (2), which during the movement of the vehicle direct the flow of air from the outside under the vehicle.