A kind of automobile active drag reduction device based on multi-position combination stable blowing and its drag reduction method

Abstract

A kind of automobile active drag reduction device based on multi-position combination stable blowing and its drag reduction method, including the air source assembly fixed in the bottom of automobile and the blowing assembly connected with air source assembly;Blowing assembly includes first blowing unit, second blowing unit and third blowing unit, in the spout of first blowing unit, second blowing unit and third blowing unit, all are provided with air flow pressure sensor for monitoring the real-time pressure of jet air flow, first blowing unit is long strip, is set on car along the bottom of automobile bumper transversely, second blowing unit is short strip, is set on car along the outside edge of automobile tail lamp, third blowing unit is long strip, is set between the roof of car and rear windshield transversely;The present application adopts continuous long and narrow structure as air outlet passage, blowing port is linearly continuous distribution along the extension direction of drag reduction wall surface, to ensure that air flow can be evenly sprayed along wall surface full length from structure, realize the full coverage of outflow area.

Description

Technical Field

[0001] This invention relates to the field of automotive aerodynamics, and in particular to an active drag reduction device and method for automobiles based on multi-position combined stable air blowing. Background Technology

[0002] Aerodynamic drag is one of the key factors affecting the driving range and energy efficiency of automobiles. With the rapid development of my country's electric vehicle industry, users' demand for driving range is constantly increasing. Reducing aerodynamic drag has become an important breakthrough in improving the energy efficiency of automobiles. When a car is driving at high speed, about 60%-80% of the energy consumption is used to overcome air resistance. Reducing aerodynamic drag can directly increase the driving range, reduce the frequency of charging, and enhance the user experience.

[0003] Existing drag reduction measures for automobiles are mostly passive, mainly by optimizing the body shape design, such as using streamlined bodies and hidden door handles to reduce wind resistance. However, passive drag reduction measures are constrained by the design of the body structure and passenger space, and their drag reduction potential is nearing its limit, making it difficult to meet the higher demands of electric vehicles for low energy consumption and long range. In addition, passive drag reduction measures cannot dynamically adjust the drag reduction strategy according to driving conditions, such as changes in vehicle speed and wind direction, and the drag reduction effect is unstable in complex driving environments.

[0004] Active drag reduction technology reduces drag by dynamically intervening in the airflow field around the vehicle body and has adaptive adjustment capabilities, making it a research hotspot in the field of automotive aerodynamic optimization. Among them, air-blowing drag reduction technology reduces form drag and induced drag by injecting airflow into key aerodynamic areas on the vehicle body surface, reshaping the flow field structure, suppressing airflow separation, and weakening vortex formation. However, existing air-blowing drag reduction technologies lack adaptation designs for the aerodynamic characteristics of the vehicle body, resulting in limited drag reduction efficiency and making it difficult to fully realize the technical advantages of active drag reduction.

[0005] Therefore, providing an active drag reduction device and method for automobiles based on multi-position combined stable blowing, which is adapted to the characteristics of automobile bodies and has a significant drag reduction effect, can solve the above-mentioned technical problems and has important engineering application value. Summary of the Invention

[0006] The purpose of this invention is to provide an active drag reduction device and method for automobiles based on multi-position combined stable air blowing. By opening a slit structure at the rear of the vehicle to blow air within a suitable range, the flow field at the rear of the vehicle body is effectively optimized, aerodynamic drag is reduced, and the vehicle's driving range and energy efficiency are improved.

[0007] The present invention provides an active drag reduction device for automobiles based on multi-position combined stable blowing, including an air source assembly fixed to the bottom of the automobile and a blowing assembly connected to the air source assembly;

[0008] The blowing assembly includes a first blowing unit, a second blowing unit, and a third blowing unit. Each of the first, second, and third blowing units is equipped with a gas pressure sensor for monitoring the real-time pressure of the jet gas. The first blowing unit is elongated and is horizontally installed on the car along the bottom of the car bumper. The second blowing unit is short and is installed on the car along the outer edge of the car taillight. The third blowing unit is elongated and is horizontally installed between the car roof and the rear windshield.

[0009] The vehicle-mounted controller is electrically connected to the airflow pressure sensor.

[0010] The first, second, and third air-blowing units of this invention are all elongated strip-shaped structures with slit-like nozzles that are continuous in the middle.

[0011] Furthermore, the gas source assembly includes a gas storage tank and a distribution channel. The gas storage tank is installed on the vehicle chassis. The gas storage tank and the distribution channel are connected through a gas transmission pipeline. The distribution channel is connected to the first air blowing unit, the second air blowing unit, and the third air blowing unit through a distribution pipe. Each of the distribution pipes is equipped with an electromagnetic flow control valve. The vehicle controller is electrically connected to the electromagnetic flow control valve.

[0012] Furthermore, the first air blowing unit includes a first air blowing port body, and a first horizontal mounting groove is provided at the bottom of the car bumper. A first rotating seat and a first fixed seat, which are fixedly connected to the car, are respectively provided at both ends of the first mounting groove. The first air blowing port body is connected to one end of the diverter pipe. The first rotating seat includes a first motor and a first rotating shaft. The first motor is fixed to the car. One end of the first rotating shaft is fixedly connected to the output end of the first motor. The other end of the first rotating shaft is fixedly connected to one end of the first air blowing port body. The other end of the first air blowing port body is rotatably connected to the first fixed seat.

[0013] Furthermore, the second air blowing unit includes a second air blowing port body, and a vertical second mounting groove is provided on the side of the taillight of the car. A second rotating seat and a second fixed seat are respectively provided at both ends of the second mounting groove and are fixedly connected to the car. The second air blowing port body is connected to one end of the split pipe. The second rotating seat includes a second motor and a second rotating shaft. The second motor is fixed on the car. One end of the second rotating shaft is fixedly connected to the output end of the second motor. The other end of the second rotating shaft is fixedly connected to one end of the second air blowing port body. The other end of the second air blowing port body is rotatably connected to the second fixed seat.

[0014] Furthermore, the third air blowing unit includes a third air blowing port body, and a transverse third mounting groove is provided on the vehicle between the roof and the rear windshield. A third rotating seat and a third fixed seat, which are fixedly connected to the vehicle, are respectively provided at both ends of the third mounting groove. The third air blowing port body is connected to one end of the diverter pipe. The third rotating seat includes a third motor and a third rotating shaft. The third motor is fixed on the vehicle. One end of the third rotating shaft is fixedly connected to the output end of the third motor. The other end of the third rotating shaft is fixedly connected to one end of the third air blowing port body. The other end of the third air blowing port body is rotatably connected to the third fixed seat.

[0015] Furthermore, the first air outlet body and the first mounting groove form a first flow guide groove, the second air outlet body and the second mounting groove form a second flow guide groove, and the third air outlet body and the third mounting groove form a third flow guide groove.

[0016] Furthermore, the edge of the first mounting groove is rounded, and the jet direction is downward in the vertical plane at an angle of 25° to 35° with the horizontal plane;

[0017] The second mounting groove has a rounded corner transition. The jet direction is at an angle of 55° to 65° downwards from the horizontal plane in the vertical plane, and at an angle of 25° to 35° outwards from the longitudinal axis of the vehicle in the horizontal plane.

[0018] The edge of the third mounting groove is rounded, and the jet direction is tangential to the surface of the rear windshield.

[0019] The present invention also provides a drag reduction method, comprising the following steps:

[0020] S1: Install the air blowing components at the bottom of the car bumper, the outer edge of the car taillights, and between the car roof and the windshield.

[0021] S2: Set the initial blowing parameters, including blowing speed v and blowing angle α, and perform aerodynamic performance tests according to different preset driving conditions;

[0022] S3: Establish a DriveAerFastback car model including the blowing slit, construct the flow field calculation domain, divide the grid and verify independence, use the Reynolds-averaged Navel-Stokes equations and the SSTk-ω turbulence model to calculate the flow field around the car body under different blowing parameters, and obtain the aerodynamic drag coefficient.

[0023] S4: Calculate the rate of change of aerodynamic drag coefficient before and after control under various working conditions, compare the drag reduction effect corresponding to different blowing speeds v and blowing angles α, and select the best combination of blowing parameters under different combinations of vehicle speed and wind speed.

[0024] The aerodynamic drag coefficient, drag coefficient change rate, and drag reduction efficiency are calculated using the formulas, where:

[0025] Aerodynamic drag coefficient:

[0026] Rate of change of drag coefficient: ∆C d = ×100%

[0027] Drag reduction efficiency:

[0028] In the formula: F d The aerodynamic drag on the vehicle, ΔF d The drag difference is expressed in N; ρ is the air density, expressed in kg / m³; U ∞ U represents the free-flow velocity. b The value represents the blowing speed amplitude, measured in m / s; A is the frontal area of ​​the car, i.e., the projected area of ​​the car body perpendicular to the direction of travel. b Indicates the blowing area, in m²; C d0 C is the aerodynamic drag coefficient under no-blowing control. d P is the aerodynamic drag coefficient under controlled air blowing. c P represents the power saved by steady-state blowing, measured in W. b The energy consumed by steady-state blowing is expressed in W; K is the total pressure loss, which is a constant, and its value is set to 5 according to the literature.

[0029] Furthermore, S2 includes the following steps:

[0030] S2.1: With the blowing angle α fixed, the blowing speed v is changed to correspond to a vehicle speed of 120km / h. The values ​​of v are 3.33m / s, 10m / s, and 16.67m / s, which are 0.1U respectively. ∞ 0.3U ∞ 0.5U ∞ ;

[0031] S2.2: With a fixed blowing speed v, change the blowing angle α. The angle is defined as follows: 0° is perpendicular to the vehicle surface, positive is biased towards the vehicle's driving direction, and negative is away from the driving direction. The blowing angle α is selected from several values ​​within the range of 0° to 60°.

[0032] The preset operating conditions include different vehicle speeds, with speeds ranging from 30 to 120 km / h.

[0033] Furthermore, S3 includes the following steps:

[0034] S3.1: Using the DriveAerFastback car model, import it into the aerodynamic simulation software STAR-CCM+ for geometry cleanup and simplification, and add air blowing components;

[0035] S3.2: Construct the computational domain for the flow field around the vehicle. The dimensions of the computational domain are set as follows: the length in front of the vehicle is 4 times the vehicle length, the length behind the vehicle is 6 times the vehicle length, the width is 10 times the vehicle width, and the height is 5 times the vehicle height. The ground is set as a moving wall to simulate the real driving state.

[0036] S3.3: Polyhedral meshes are used to divide the geometric model and computational domain. Mesh refinement is performed on key areas such as the vehicle surface and the air slit outlet. The mesh size is 5mm, and the mesh size of non-critical areas is gradually transitioned to 10-20mm. Mesh independence analysis is performed after meshing is completed.

[0037] S3.4: Set boundary conditions: The incoming flow boundary is set as a velocity inlet, the outlet boundary is set as a pressure outlet, and the vehicle surface and the blowing slit surface are set as no-slip walls. Numerical calculations are performed using the Reynolds-averaged Navel-Stokes equations and the SSTk-ω turbulence model to obtain the flow field results under no-blowing control and under different blowing parameters at v=0 and α=0°.

[0038] This invention discloses the following technical advantages: It provides an active drag reduction device and method for automobiles based on multi-position combined stable air blowing. By adopting a slit-type air blowing structure instead of the traditional multi-hole injection structure, the invention addresses the issue of airflow gaps between holes due to the discrete point jets of traditional multi-hole injection, which create localized high-resistance areas. This invention uses a continuous, elongated structure as the air outlet channel, with the air outlets linearly and continuously distributed along the drag-reducing wall, eliminating airflow gaps caused by hole spacing. Structurally, this ensures uniform airflow along the entire length of the wall, achieving full coverage of the outlet area, resulting in more uniform airflow and more stable drag reduction. The slit structure is simple to manufacture, has low cost, and uses lightweight aluminum alloy, thus not significantly increasing vehicle weight and meeting the lightweight requirements of new energy vehicles.

[0039] The installation position and parameters of the slit-type air blowing unit have been optimized through aerodynamic simulation to match the aerodynamic characteristics of the car body. The injection replenishes the boundary layer kinetic energy and suppresses airflow separation. This invention uses a segmented injection port design, determined through simulation experiments, mainly at the bottom of the rear bumper, the outer edge of the taillights, and the transition between the roof and the rear windshield. High-pressure airflow is precisely injected to the critical point of airflow separation on the car body. The injected airflow and the boundary layer airflow on the car body surface are superimposed in the same direction, replenishing the boundary layer airflow with kinetic energy and compensating for the energy loss during its flow through the car body. This allows the airflow to continuously flow close to the car body surface and avoids airflow separation. At the same time, the setting of the guide channel ensures that the velocity and pressure of the injected airflow are uniform and stable, avoiding boundary layer disturbances caused by excessively strong or weak local airflow. This can effectively suppress airflow separation around the car body, weaken vortex formation, and reduce aerodynamic drag from the root.

[0040] Meanwhile, the segmented slit layout and independent flow control design allow for flexible adjustment of the blowing intensity in each area according to different driving conditions, further enhancing drag reduction adaptability. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 This is a schematic diagram of the gas source component structure of the present invention;

[0043] Figure 2 This is a schematic diagram of the diversion tube structure of the present invention;

[0044] Figure 3 This is a schematic diagram of the side structure of the guide channel of the present invention;

[0045] Figure 4 This is a schematic diagram of the layout structure of the air blowing assembly of the present invention;

[0046] Figure 5 This is a schematic diagram of the flow field around the vehicle body when there is no air blowing control according to the present invention;

[0047] Figure 6 This is a schematic diagram of the flow field around the vehicle body when the present invention has air blowing control;

[0048] Figure 7 This is a schematic diagram of the boundary conditions of the simulation region;

[0049] Figure 8 This is a schematic diagram showing the jet direction of the first and second air blowing units.

[0050] Figure 9This is a schematic diagram showing the jet direction of the third blowing unit;

[0051] Among them, 1. gas storage tank; 2. distribution channel; 3. gas transmission pipeline; 4. distribution pipe; 5. first air blowing unit; 6. second air blowing unit; 7. third air blowing unit. Detailed Implementation

[0052] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0053] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0054] Example:

[0055] like Figures 1-7 As shown, the present invention provides an active drag reduction device for automobiles based on multi-position combined stable blowing, including an air source assembly fixed to the bottom of the automobile and a blowing assembly connected to the air source assembly.

[0056] The blowing assembly includes a first blowing unit 5, a second blowing unit 6, and a third blowing unit 7. A gas pressure sensor for monitoring the real-time pressure of the jet gas is provided in the middle of the nozzle of each of the first blowing unit 5, the second blowing unit 6, and the third blowing unit 7. The first blowing unit 5 is elongated and is horizontally installed on the car along the bottom of the car bumper. The second blowing unit 6 is short and is installed on the car along the outer edge of the taillight. The third blowing unit 7 is elongated and is horizontally installed between the roof of the car and the rear windshield.

[0057] The vehicle-mounted controller is electrically connected to the airflow pressure sensor.

[0058] In this embodiment, as Figure 1 As shown, the air source assembly includes an air storage tank 1 and a distribution channel 2. The air storage tank 1 is installed on the vehicle chassis. The air storage tank 1 and the distribution channel 2 are connected through an air supply pipe 3. The distribution channel 2 is connected to the first air blowing unit 5, the second air blowing unit 6, and the third air blowing unit 7 through a distribution pipe 4. An electromagnetic flow control valve is installed on each of the distribution pipes 4. The vehicle controller is electrically connected to the electromagnetic flow control valve.

[0059] In this embodiment, a pressure regulating valve is connected between the gas storage tank 1 and the gas transmission pipeline 3. The pressure regulating valve is an electronic proportional regulating valve with an adjustment range of 0.1-0.8 MPa.

[0060] Specifically, an installation space for the air tank 1 is reserved on the vehicle chassis. A spring damping bracket is installed to fix the air tank 1 for shock absorption and to prevent vibration damage during driving. The air tank 1 has a volume of 20L, a maximum working pressure of 0.8MPa, a rated output pressure of 0.8MPa, and a rated flow rate of 120L / min. The inner wall of the air tank 1 is coated with an epoxy resin anti-corrosion coating. A safety valve is installed at the top of the air tank 1, with an opening pressure threshold of 0.9MPa. After the air tank 1 is depleted, it is refilled by an air pump. A pressure sensor is also installed at the top of the air tank 1. The air supply pipe 3 and the diversion pipe 4 are arranged along the edge of the vehicle chassis and are fixed by clips to avoid friction with other chassis components. The air supply pipe 3 and the diversion pipe 4 are made of high-pressure resistant rubber tubing with an inner diameter of 12mm and a wall thickness of 2mm. They are connected to the diversion groove 2 through quick-connect fittings. The outer layer of the pipes is wrapped with a heat insulation layer, which is made of 3mm aluminum foil insulation cotton.

[0061] The gas storage tank 1 of this invention is connected to the diversion channel 2 to stabilize the airflow pressure. The diversion channel 2 divides the gas through the diversion pipe 4 to achieve uniform distribution of airflow. The airflow pressure sensor is used to monitor the real-time pressure of the jet airflow. The solenoid valve is used to regulate the airflow size of the branch pipe. The vehicle controller is integrated into the vehicle control system.

[0062] In this embodiment, the airflow pressure sensor is selected from the AOP100 / AEP series of Auson Electronics; the electromagnetic flow control valve is selected from the 2W / 2S series of Yongchuang solenoid valves; the vehicle controller includes a microcontroller unit (MCU) and a drive circuit. The vehicle controller acquires the real-time pressure signal of the airflow pressure sensor through the sensor acquisition interface and controls the opening of the solenoid valve through PWM or switch drive signals; the vehicle controller can communicate with the vehicle controller (VCU) through CAN or LIN bus.

[0063] In this embodiment, the first air blowing unit 5 includes a first air blowing port body. A first horizontal mounting groove is provided at the bottom of the car bumper. A first rotating seat and a first fixed seat, which are fixedly connected to the car, are respectively provided at both ends of the first mounting groove. The first air blowing port body is connected to one end of the diverter pipe 4. The first rotating seat includes a first motor and a first rotating shaft. The first motor is fixedly installed on the car. One end of the first rotating shaft is fixedly connected to the output end of the first motor. The other end of the first rotating shaft is fixedly connected to one end of the first air blowing port body. The other end of the first air blowing port body is rotatably connected to the first fixed seat.

[0064] In this embodiment, the first mounting groove is opened laterally along the bottom of the rear bumper of the car, with the starting end flush with the left end of the rear bumper and the ending end flush with the right end of the rear bumper; the groove opening is 1m long and 2.5cm wide, and the groove outlet edge is rounded with a radius of 0.5cm. The jet direction is along the longitudinal direction of the car and forms a 30° angle with the horizontal plane downward in the vertical plane (y plane). This angle is determined based on the simulation results of the tail downwash airflow suppression.

[0065] In this embodiment, the second air blowing unit 6 includes a second air blowing port body. A vertical second mounting groove is provided on the side of the taillight of the car. A second rotating seat and a second fixed seat, which are fixedly connected to the car, are respectively provided at both ends of the second mounting groove. The second air blowing port body is connected to one end of the diverter pipe 4. The second rotating seat includes a second motor and a second rotating shaft. The second motor is fixedly installed on the car. One end of the second rotating shaft is fixedly connected to the output end of the second motor. The other end of the second rotating shaft is fixedly connected to one end of the second air blowing port body. The other end of the second air blowing port body is rotatably connected to the second fixed seat.

[0066] In this embodiment, the second mounting slots are symmetrically arranged on the outer edges of the taillights on both sides of the vehicle. The slot opening of the second mounting slot is 0.18m long and 1.3cm wide. The jet direction is downward in the vertical plane (y-plane) at a 60° angle to the horizontal plane, and at a 30° angle outward from the longitudinal axis of the vehicle in the horizontal plane.

[0067] In this embodiment, the third air blowing unit 7 includes a third air blowing port body. A horizontal third mounting groove is provided on the vehicle between the roof and the rear windshield. A third rotating seat and a third fixed seat, which are fixedly connected to the vehicle, are respectively provided at both ends of the third mounting groove. The third air blowing port body is connected to one end of the diverter pipe 4. The third rotating seat includes a third motor and a third rotating shaft. The third motor is fixedly mounted on the vehicle. One end of the third rotating shaft is fixedly connected to the output end of the third motor. The other end of the third rotating shaft is fixedly connected to one end of the third air blowing port body. The other end of the third air blowing port body is rotatably connected to the third fixed seat.

[0068] In this embodiment, the third mounting slot is arranged laterally along the transition arc between the roof and the rear windshield, with the center of the slot located at the midpoint of the transition arc. The slot has a length of 0.9m and a width of 0.7cm, and the jet direction is strictly tangential to the surface of the rear windshield to control the thickening of the boundary layer of the rear windshield. The electromagnetic control valves on the diversion pipe 4 are all normally closed, with a rated working pressure of 0.8MPa.

[0069] In this embodiment, as Figure 2As shown, the first mounting slot, the second mounting slot, and the third mounting slot are all body slit structures. There are three diversion pipes 4, which are connected to the first mounting slot, the second mounting slot, and the third mounting slot respectively. At the air outlet where the diversion pipe 4 connects to the first mounting slot, the second mounting slot, and the third mounting slot, there are multiple diversion plates that are fixedly connected to the inner wall of the diversion pipe 4. The diversion pipe 4 is connected to the body slit by a snap or bolt. The size of the air outlet can be adjusted. This structure is a schematic diagram.

[0070] This invention uses a motor to drive a rotating shaft to adjust the rotation of the first air inlet body, the second air inlet body, and the third air inlet body, thereby adjusting the jet angle. The first motor, the second motor, and the third motor are all 9g motors such as MG90S and DS939MG.

[0071] In this invention, the first air inlet body, the second air inlet body, and the third air inlet body all have a structure with multiple guide plates. The multiple guide plates are evenly arranged and are made of lightweight, high-strength aluminum alloy material. Their length is 180-1000 mm and their width is 7-25 mm.

[0072] Specifically, the dimensions and installation positions of the first air inlet body, the second air inlet body, and the third air inlet body are shown in Table 1:

[0073] Table 1

[0074] Location Dimensions (length × width) First air inlet body Rear bumper 1000mm×25mm Second air inlet body Taillight edge 180mm×13mm The third air inlet body Top of rear of the car 900mm×7mm

[0075] In this embodiment, the first air outlet body and the first mounting groove form a first guide groove, the second air outlet body and the second mounting groove form a second guide groove, and the third air outlet body and the third mounting groove form a third guide groove.

[0076] Specifically, the guide channel is used to guide the airflow to be sprayed in a preset direction.

[0077] In this embodiment, the edge of the first mounting groove is rounded, and the jet direction is downward in the vertical plane at an angle of 25° to 35° with the horizontal plane;

[0078] The second mounting groove has a rounded corner transition. The jet direction is at an angle of 55° to 65° downwards from the horizontal plane in the vertical plane, and at an angle of 25° to 35° outwards from the longitudinal axis of the vehicle in the horizontal plane.

[0079] The edge of the third mounting groove is rounded, and the jet direction is tangential to the surface of the rear windshield.

[0080] In this embodiment, the blowing speed range is 0.1U. ∞ ~0.5U ∞ The optimal blowing speed is 0.3U. ∞ .

[0081] The present invention relates to an active drag reduction device for automobiles based on multi-position combined stable blowing. In use, the compressed airflow provided in the air tank is delivered to the diversion groove through the air supply pipeline, and then diverted to the corresponding first mounting groove, second mounting groove and third mounting groove through the diversion pipe. The angles of the first blowing port body, the second blowing port body and the third blowing port body are preset, and the air is ejected from the nozzle in the corresponding direction. The airflow of each branch is independently adjusted by the electromagnetic flow control valve.

[0082] The present invention also provides a drag reduction method, comprising the following steps:

[0083] S1: Install the air blowing components at the bottom of the car bumper, the outer edge of the car taillights, and between the car roof and the windshield.

[0084] S2: Set the initial blowing parameters, including blowing speed v and blowing angle α, and perform aerodynamic performance tests according to different preset driving conditions;

[0085] S3: Establish a DriveAerFastback car model including the blowing slit, construct the flow field calculation domain, divide the grid and verify independence, use the Reynolds-averaged Navel-Stokes equations and the SSTk-ω turbulence model to calculate the flow field around the car body under different blowing parameters, and obtain the aerodynamic drag coefficient.

[0086] S4: Calculate the rate of change of aerodynamic drag coefficient before and after control under various working conditions, compare the drag reduction effect corresponding to different blowing speeds v and blowing angles α, and select the best combination of blowing parameters under different combinations of vehicle speed and wind speed.

[0087] The aerodynamic drag coefficient, drag coefficient change rate, and drag reduction efficiency are calculated using the formulas, where:

[0088] Aerodynamic drag coefficient:

[0089] Rate of change of drag coefficient: ∆C d = ×100%

[0090] Drag reduction efficiency:

[0091] In the formula: F d The aerodynamic drag on the vehicle, ΔF d The drag difference is expressed in N; ρ is the air density, expressed in kg / m³; U ∞ U represents the free-flow velocity. b The value represents the blowing speed amplitude, measured in m / s; A is the frontal area of ​​the car, i.e., the projected area of ​​the car body perpendicular to the direction of travel. bIndicates the blowing area, in m²; C d0 C is the aerodynamic drag coefficient under no-blowing control. d P is the aerodynamic drag coefficient under controlled air blowing. c P represents the power saved by steady-state blowing, measured in W. b The energy consumed by steady-state blowing is expressed in W; K is the total pressure loss, which is a constant, and its value is set to 5 according to the literature.

[0092] In this embodiment, step S2 includes the following steps:

[0093] S2.1: With the blowing angle α fixed, the blowing speed v is changed to correspond to a vehicle speed of 120km / h. The values ​​of v are 3.33m / s, 10m / s, and 16.67m / s, which are 0.1U respectively. ∞ 0.3U ∞ 0.5U ∞ ;

[0094] S2.2: With a fixed blowing speed v, change the blowing angle α. The angle is defined as follows: 0° is perpendicular to the vehicle surface, positive is biased towards the vehicle's driving direction, and negative is away from the driving direction. The blowing angle α is selected from several values ​​within the range of 0° to 60°.

[0095] The preset operating conditions include different vehicle speeds, with speeds ranging from 30 to 120 km / h.

[0096] In this embodiment, to verify the drag reduction effect and energy efficiency of the device of the present invention, a flow simulation was performed on a DriveAerFastback car model equipped with the above-mentioned device. The specific simulation steps are as follows:

[0097] S3.1: Using the DriveAerFastback car model, import it into the aerodynamic simulation software STAR-CCM+ for geometry cleanup and simplification, add air blowing components, and ensure that the geometric model is consistent with the actual device;

[0098] S3.2: Construct the computational domain for the flow field around the vehicle. The dimensions of the computational domain are set as follows: the length in front of the vehicle is 4 times the vehicle length, the length behind the vehicle is 6 times the vehicle length, the width is 10 times the vehicle width, and the height is 5 times the vehicle height. The ground is set as a moving wall to simulate the real driving state.

[0099] S3.3: Polyhedral meshes are used to divide the geometric model and computational domain. Mesh refinement is performed on key areas such as the vehicle surface and the air slit outlet. The mesh size is 5mm, and the mesh size in non-critical areas is gradually transitioned to 10-20mm, eventually generating 28 million meshes. Mesh independence analysis is performed after meshing is completed.

[0100] S3.4: Setting Boundary Conditions: The inflow boundary is set as a velocity inlet, where 120 km / h corresponds to 33.33 m / s. The outlet boundary is set as a pressure outlet. The vehicle body surface and the blowing slit surface are set as no-slip walls. Numerical calculations are performed using the Reynolds-averaged Navel-Stokes equations and the SSTk-ω turbulence model. Simulations are performed on the flow field around the vehicle under no blowing control (v=0, α=0°) and under different blowing parameters. The aerodynamic drag coefficient, flow field velocity distribution, and pressure distribution are output as shown in Table 2.

[0101] Table 2

[0102]

[0103] As shown in Table 2, each air blowing unit has a significant drag reduction effect when working independently: Rear bumper bottom air blowing unit (0.3U) ∞ Drag reduction rate of 2%, taillight side edge air blowing unit (0.3U) ∞ The drag reduction rate is 1.6%, and the air blowing unit at the rear window transition (0.3U) ∞ The drag reduction rate is 3%; the drag reduction rate reaches 5.9% when combined with air blowing, and the maximum drag reduction rate is increased to 9.6% after angle optimization, with a drag reduction efficiency of 2.6, and the driving range is increased by 5%-10% under high-speed driving conditions;

[0104] like Figure 5 The diagram shows the flow field at the rear of the vehicle without airflow control. It is evident that there is a significant airflow separation region and strong vortices (longitudinal vortex pair intensity 700 / s²) at the rear of the vehicle, resulting in substantial aerodynamic drag. Figure 6 The diagram shows the tail flow field with air blowing control. The blowing parameters are the optimal values ​​for each blowing component, where the blowing component is a slot-type exciter: the air jet velocity of the blowing unit at the bottom of the rear bumper is 10 m / s (0.3U). ∞ The direction is along the longitudinal direction of the car and downwards at a 30° angle to the horizontal plane in the vertical plane (y-plane); the exhaust velocity of the taillight edge blowing unit is 10m / s (0.3U). ∞ The direction is downward in the vertical plane (y-plane) at a 60° angle to the horizontal plane, and at a 30° angle outward from the longitudinal axis of the vehicle in the horizontal plane; the air jet velocity of the rear window blowing unit is 10m / s (0.3U). ∞ The direction is tangential to the surface of the rear windshield. As can be clearly seen from the figure, after the air blowing control, the airflow separation phenomenon at the rear of the vehicle body is effectively suppressed, the vortex intensity is reduced to below 250 / s², and the flow field structure is more reasonable.

[0105] This invention effectively weakens the longitudinal vortex pair intensity at the rear of the vehicle, suppresses airflow separation, and reduces directional momentum loss through the synergistic flow field regulation effect of multi-position air blowing. At a vehicle speed of 120 km / h, the combined air blowing drag reduction rate is 5.9%, and the maximum drag reduction rate after optimization can reach 9.6%, with a drag reduction efficiency of 2.6.

[0106] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0107] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. An active drag reduction device for automobiles based on multi-position combined stable air blowing, characterized in that, It includes an air source assembly fixed to the bottom of the vehicle and an air blowing assembly connected to the air source assembly; The blowing assembly includes a first blowing unit (5), a second blowing unit (6), and a third blowing unit (7). Each of the first blowing unit (5), the second blowing unit (6), and the third blowing unit (7) is equipped with a gas pressure sensor for monitoring the real-time pressure of the jet gas. The first blowing unit (5) is long and is horizontally installed on the car along the bottom of the car bumper. The second blowing unit (6) is short and is installed on the car along the outer edge of the car taillight. The third blowing unit (7) is long and is horizontally installed between the car roof and the rear windshield. The vehicle-mounted controller is electrically connected to the airflow pressure sensor.

2. The active drag reduction device for automobiles based on multi-position combined stable blowing according to claim 1, characterized in that, The gas source assembly includes a gas storage tank (1) and a distribution channel (2). The gas storage tank (1) is installed on the vehicle chassis. The gas storage tank (1) and the distribution channel (2) are connected through a gas transmission pipe (3). The distribution channel (2) is connected to the first air blowing unit (5), the second air blowing unit (6) and the third air blowing unit (7) through a distribution pipe (4). An electromagnetic flow control valve is provided on each of the distribution pipes (4). The vehicle controller is electrically connected to the electromagnetic flow control valve.

3. The active drag reduction device for automobiles based on multi-position combined stable blowing according to claim 2, characterized in that, The first air blowing unit (5) includes a first air blowing port body. A first horizontal mounting groove is provided at the bottom of the car bumper. A first rotating seat and a first fixed seat that are fixedly connected to the car are respectively provided at both ends of the first mounting groove. The first air blowing port body is connected to one end of the diversion pipe (4). The first rotating base includes a first motor and a first rotating shaft. The first motor is fixed on the vehicle. One end of the first rotating shaft is fixedly connected to the output end of the first motor. The other end of the first rotating shaft is fixedly connected to one end of the first air inlet body. The other end of the first air inlet body is rotatably connected to the first fixed base.

4. The active drag reduction device for automobiles based on multi-position combined stable blowing according to claim 3, characterized in that: The second air blowing unit (6) includes a second air blowing port body. A vertical second mounting groove is provided on the side of the taillight of the car. A second rotating seat and a second fixed seat that are fixedly connected to the car are respectively provided at both ends of the second mounting groove. The second air blowing port body is connected to one end of the diversion pipe (4). The second rotating base includes a second motor and a second rotating shaft. The second motor is fixed on the vehicle. One end of the second rotating shaft is fixedly connected to the output end of the second motor. The other end of the second rotating shaft is fixedly connected to one end of the second air inlet body. The other end of the second air inlet body is rotatably connected to the second fixed base.

5. The active drag reduction device for automobiles based on multi-position combined stable blowing according to claim 4, characterized in that, The third air blowing unit (7) includes a third air blowing port body. A horizontal third mounting groove is provided on the car between the car roof and the rear windshield. A third rotating seat and a third fixed seat that are fixedly connected to the car are respectively provided at both ends of the third mounting groove. The third air blowing port body is connected to one end of the diversion pipe (4). The third rotating base includes a third motor and a third rotating shaft. The third motor is fixed on the vehicle. One end of the third rotating shaft is fixedly connected to the output end of the third motor, and the other end of the third rotating shaft is fixedly connected to one end of the third air inlet body. The other end of the third air inlet body is rotatably connected to the third fixed base.

6. The active drag reduction device for automobiles based on multi-position combined stable blowing according to claim 5, characterized in that, The first air inlet body and the first mounting groove form a first flow guide groove, the second air inlet body and the second mounting groove form a second flow guide groove, and the third air inlet body and the third mounting groove form a third flow guide groove.

7. The active drag reduction device for automobiles based on multi-position combined stable blowing according to claim 6, characterized in that, The first mounting groove has a rounded edge, and the jet direction is downward in the vertical plane at an angle of 25° to 35° with the horizontal plane; The second mounting groove has a rounded corner transition. The jet direction is at an angle of 55° to 65° downwards with the horizontal plane in the vertical plane, and at an angle of 25° to 35° outwards with the longitudinal axis of the vehicle in the horizontal plane. The edge of the third mounting groove is rounded, and the jet direction is tangential to the surface of the rear windshield.

8. A drag reduction method for an active drag reduction device for automobiles based on multi-position combined stable blowing according to any one of claims 1-7, characterized in that, Includes the following steps: S1: Install the air blowing components at the bottom of the car bumper, the outer edge of the car taillights, and between the car roof and the windshield. S2: Set the initial blowing parameters, including blowing speed v and blowing angle α, and perform aerodynamic performance tests according to different preset driving conditions; S3: Establish a DriveAerFastback car model including the blowing slit, construct the flow field calculation domain, divide the mesh and perform independence verification, calculate the flow field around the car body under different blowing parameters, and obtain the aerodynamic drag coefficient. S4: Calculate the rate of change of aerodynamic drag coefficient before and after control under various working conditions, compare the drag reduction effect corresponding to different blowing speeds v and blowing angles α, and select the best combination of blowing parameters under different combinations of vehicle speed and wind speed. The aerodynamic drag coefficient, drag coefficient change rate, and drag reduction efficiency are calculated using the formulas, where: Aerodynamic drag coefficient: Rate of change of drag coefficient: ∆C d = ×100% Drag reduction efficiency: In the formula: F d The aerodynamic drag on the vehicle, ΔF d The drag difference is expressed in N; ρ is the air density, expressed in kg / m³; U ∞ U represents the free-flow velocity. b The value represents the blowing speed amplitude, measured in m / s; A is the frontal area of ​​the car, i.e., the projected area of ​​the car body perpendicular to the direction of travel. b Indicates the blowing area, in m²; C d0 C is the aerodynamic drag coefficient under no-blowing control. d P is the aerodynamic drag coefficient under controlled air blowing. c P represents the power saved by steady-state blowing, measured in W. b The energy consumed by steady-state blowing is expressed in W; K is the total pressure loss, which is a constant, and its value is set to 5 according to the literature.

9. The drag reduction method of an active drag reduction device for automobiles based on multi-position combined stable blowing according to claim 8, characterized in that, S2 includes the following steps: S2.1: With the blowing angle α fixed, the blowing speed v is changed. For a vehicle speed of 120 km / h, v takes values ​​of 3.33 m / s, 10 m / s, and 16.67 m / s, which are respectively 0.1U ∞ 0.3U ∞ 0.5U ∞ ; S2.2: With a fixed blowing speed v, change the blowing angle α. The angle is defined as follows: 0° is perpendicular to the vehicle surface, positive is biased towards the vehicle's driving direction, and negative is away from the driving direction. The blowing angle α is selected from several values ​​within the range of 0° to 60°. The preset operating conditions include different vehicle speeds, with speeds ranging from 30 to 120 km / h.

10. The drag reduction method of an active drag reduction device for automobiles based on multi-position combined stable blowing according to claim 8, characterized in that, S3 includes the following steps: S3.1: Using the DriveAerFastback car model, import it into the aerodynamic simulation software STAR-CCM+ for geometry cleanup and simplification, and add air blowing components; S3.2: Construct the computational domain for the flow field around the vehicle. The dimensions of the computational domain are set as follows: the length in front of the vehicle is 4 times the vehicle length, the length behind the vehicle is 6 times the vehicle length, the width is 10 times the vehicle width, and the height is 5 times the vehicle height. The ground is set as a moving wall to simulate the real driving state. S3.3: Polyhedral meshes are used to divide the geometric model and computational domain. Mesh refinement is performed on key areas such as the vehicle surface and the air slit outlet. The mesh size is 5mm, and the mesh size of non-critical areas is gradually transitioned to 10-20mm. Mesh independence analysis is performed after meshing is completed. S3.4: Set boundary conditions: The incoming flow boundary is set as a velocity inlet, the outlet boundary is set as a pressure outlet, and the vehicle surface and the blowing slit surface are set as no-slip walls. Numerical calculations are performed using the Reynolds-averaged Navel-Stokes equations and the SSTk-ω turbulence model to obtain the flow field results under no-blowing control and under different blowing parameters at v=0 and α=0°.

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