Self-drafting Extension for Sub-sonic Vehicle Drag Reduction
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Solution Overview
Problem
Aerodynamic drag in sub-sonic terrestrial vehicles, such as SUVs and truck tractors, is increased due to non-ideal aerodynamic shaping, leading to reduced fuel efficiency.
Innovation Solution
A forward-projecting extension with a draft plate at its end is used to generate turbulence, reducing overall drag forces. The extension's length, draft plate size, and tilt are adjustable and controlled by a system measuring differential pressure, allowing for optimal performance adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the vehicle uses non-ideal aerodynamic shaping (e.g., vertical front profile), then ease of manufacture and aesthetic reasons are satisfied, but aerodynamic drag increases
Solution Approach 1:
The device segments the front profile modification into a separate, detachable extension component rather than requiring redesign of the entire vehicle body. This allows the vehicle to maintain its original non-ideal aerodynamic shaping while adding a focused turbulence-generating element at the front edge to reduce drag.
Solution Approach 2:
The extension acts as an intermediary element between the vehicle's non-ideal front profile and the airflow. It introduces controlled turbulence that serves as a mediator to reduce the adverse aerodynamic effects of the vertical front profile, thereby reducing drag without changing the vehicle's fundamental design.
2Loss of energy
If the extension length is increased to improve turbulence generation, then aerodynamic drag reduction improves, but device complexity and potential damage to objects increases
Solution Approach 1:
The extension incorporates telescoping sections that allow dynamic adjustment of its length. This enables the system to optimize turbulence generation by extending to the appropriate length for drag reduction while retracting when not in use to minimize complexity and potential damage risks.
Solution Approach 2:
The system changes the physical parameter of extension length dynamically through telescoping sections. By adjusting this parameter, the system optimizes turbulence generation for drag reduction while managing device complexity and safety considerations.
3Reliability
If the extension is made rigid for structural strength, then reliability improves, but damage to contacted objects increases
Solution Approach 1:
The extension is segmented into telescoping sections with break-away portions between them. This segmentation allows the structure to maintain reliability for its intended aerodynamic function while providing controlled failure points that prevent excessive force transmission to contacted objects.
Solution Approach 2:
The break-away portions serve as pre-designed weak points that absorb impact energy before it can be transmitted to other objects. This beforehand cushioning mechanism protects objects by sacrificing a non-critical structural element during potential collisions.
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
The solution effectively reduces aerodynamic drag in vehicles with non-ideal shapes, improving fuel efficiency without requiring a redesign for lower drag coefficients, and includes break-away sections for safety.
Implementation Method 1
The device is an extension that projects forward in the usual direction of motion of the vehicle a sufficient length to cause turbulence in front of the vehicle that results in a reduction of overall drag forces on the vehicle.
Data Source
AI summary
A self-drafting device for reducing the aerodynamic drag of sub-sonic vehicles includes an extension projecting forward from the vehicle in order to generate turbulence between a distal (forward) end of the extension and the vehicle itself, in order to reduce aerodynamic drag on the vehicle. The device may include a draft plate to increase the cross sectional area of the distal end and the draft plate may be tilted with respect to a vertical direction. The tilt, cross-sectional size and or extension of the device may be adjustable, and may be dynamically controlled by one or more motors during operation of the vehicle in conformity with a pressure profile across the vehicle that is measured using pressure sensors. The extension may be automatically retracted, e.g., a telescoping extension may be drawn under the hood of an automobile as the velocity of the vehicle decreases.