Purpose

This study aims to achieve optimum flow separation control for a road vehicle using a reverse flow fan on rear side.

Design/methodology/approach

A full-length reverse flow fan array (fan’s air speed is 50% of the car’s speed) is attached throughout the width of the vehicle at rear edge corner.

Findings

The reverse flow fan array positioned at rear edge of car pushes the airflow against the car’s rear window. It creates the recirculation region and alters the pressure distribution. This reduces the lift coefficient by 150%, which becomes the downforce and reduces the drag coefficient by 22%. As the car speed increases, fan speed should also be increased for effective flow control.

Research limitations/implications

This active flow control method for 3D Ahmed car body has been studied computationally at low speed (40 m/s).

Practical implications

This design increases the downforce, thus gives better cornering speed and stability, and decreases the drag which improves fuel efficiency. It can be used for effective flow control of cars (hatchback/sedan). The findings can be applied to the bluff bodies, road vehicles, UAV and helicopter fuselage for flow separation control.

Originality/value

The fan array is attached on car’s rear side, which blows air against the car’s rear window. It alters the pressure distribution and aerodynamics forces favorably. But the existing high-speed fan used in a sports cars sucks the air from bottom and pushes it rearward, which increases both the traction force and drag.

中文翻译：

---

使用逆流风扇的车辆流量控制

目的

本研究旨在使用后侧逆流风扇实现道路车辆的最佳气流分离控制。

设计/方法论/途径

全长逆流风扇阵列（风扇风速为车速的 50%）安装在整个车辆宽度的后边缘角处。

发现

位于汽车后边缘的逆流风扇阵列将气流推向汽车后窗。它创建再循环区域并改变压力分布。这使升力系数降低了150%，变成了下压力，并使阻力系数降低了22%。随着汽车速度的增加，风扇速度也应该增加，以实现有效的流量控制。

研究局限性/影响

这种针对 3D Ahmed 车身的主动流量控制方法已在低速 (40 m/s) 下进行了计算研究。

实际影响

这种设计增加了下压力，从而提供更好的转弯速度和稳定性，并减少阻力，从而提高燃油效率。它可用于汽车（掀背车/轿车）的有效流量控制。研究结果可应用于钝体、道路车辆、无人机和直升机机身的流动分离控制。

原创性/价值

风扇阵列安装在汽车后侧，将空气吹向汽车后窗。它有利地改变压力分布和空气动力。但现有跑车中使用的高速风扇从底部吸入空气并将其向后推动，这增加了牵引力和阻力。