Passive Jet Flow Control for Vehicle Mirror Drag Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
External side view mirrors on motor vehicles create significant aerodynamic drag and noise due to their protruding shape, leading to increased fuel consumption and reduced efficiency, particularly in smaller vehicles, as they induce vortex shedding and turbulent flow conditions.
Innovation Solution
The implementation of low drag low noise devices that utilize passive jet flow control to manipulate air flow around the mirrors, creating directed jets that counteract base flow and reduce vortex shedding, thereby minimizing drag and noise by simulating a virtual trailing edge or 'boat-tail' effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external side view mirrors are used for vehicle operation, then visibility and safety are improved, but aerodynamic drag and noise increase significantly
Solution Approach 1:
The mirror assembly is divided into separate functional components: the mirror housing, the jet generation system, and the flow control elements. This segmentation allows independent optimization of each component - the mirror provides visibility while the jet system independently manages drag and noise without interfering with the mirror's primary function
Solution Approach 2:
A jet of fluid is introduced as an intermediary element between the oncoming flow and the mirror structure. This jet acts as a mediator that modifies the interaction between the airflow and the mirror, creating a virtual trailing edge that reduces vortex shedding and drag forces while allowing the mirror to maintain its visibility function
2Ease of operation
If external side view mirrors protrude from the vehicle cabin, then field of view is improved, but fuel efficiency decreases due to increased drag
Solution Approach 1:
The system uses pneumatic principles by generating and controlling a jet of fluid (air) to modify the aerodynamic flow around the mirror. This pneumatic intervention creates a low-pressure region that reduces pressure drag and suppresses vortex formation, thereby reducing the energy required to move the vehicle while maintaining the mirror's protruding position for optimal field of view
3Ease of manufacture
If mirrors have flat rear surfaces for structural simplicity, then manufacturing is easier, but vortex shedding and noise are generated
Solution Approach 1:
The system takes the harmful flat rear surface that causes vortex shedding and converts it into a beneficial feature by using the jet to create a virtual trailing edge. The flat surface remains structurally simple for easy manufacturing, but the jet transforms the harmful flow separation into a controlled flow pattern that reduces noise and drag, turning the original problem into an advantage
4Use of energy by moving object
If jet flow control is implemented to reduce drag and noise, then fuel efficiency is improved, but device complexity increases
Solution Approach 1:
The jet flow control system is designed to perform multiple functions simultaneously: it reduces drag, reduces noise, and creates a virtual trailing edge effect. By consolidating these multiple benefits into a single integrated system, the complexity increase is justified by the multiple performance improvements achieved without requiring separate systems for each function
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution effectively reduces drag and noise by altering the airflow around the mirrors, enhancing fuel efficiency and reducing the negative impact of vortex shedding, resulting in improved performance and reduced fuel consumption across various vehicle types.
Implementation Method 1
The implementation of low drag low noise devices that utilize passive jet flow control to manipulate air flow around the mirrors, creating directed jets that counteract base flow and reduce vortex shedding
Implementation Method 2
Drag and noise are a direct result of the flow conditions created by the shape of the side view mirrors. For example, flow conditions such as high turbulent pressure fluctuations and vortex shedding create drag, noise
Implementation Method 3
The jet(s) produced by the low drag low noise devices described herein act to counter base flow and reduce drag and noise by manipulating the flow of fluid (e.g., air) around the low drag low noise device to create directed jet(s) of air around the flat, or substantially flat, surface on the rear of the device (e.g., the mirror of a side view mirror) or the motor vehicle (e.g., rear end) creating a virtual trailing edge, or boat-tail, that reduces or removes vortex shedding
Data Source
AI summary
Low drag low noise devices are described herein that use passive jet flow control to reduce the drag and noise created by motor vehicles (e.g., motor vehicle side view mirrors and their main bodies) while the motor vehicles travel through a fluid. The low drag low noise devices described herein comprise a lengthwise axis, an outer body, and an inner body. The outer body and the inner body cooperatively define a channel through which fluid can pass during use.