Lateral Wind-Diverting Fairing for Truck Cargo Box Drag Reduction
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Solution Overview
Problem
Existing vehicles with non-aerodynamic cargo boxes experience significant drag due to blunt geometry, particularly at high speeds, leading to increased power consumption and reduced fuel efficiency.
Innovation Solution
The invention involves air-diverting devices that redirect headwinds laterally around the sides of the cargo box instead of allowing them to flow upwards, using fairing assemblies and open-panel structures to minimize drag by reducing both form and frictional drag components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a blunt flat wall geometry is used for the cargo box front wall, then the manufacturing is simple and cost-effective, but the aerodynamic drag is substantially greater
Solution Approach 1:
The fairing is divided into multiple panels (typically three panels: two side panels and one center panel) that can be separately manufactured and then assembled. Each panel is a simpler, more manageable component that can be produced using standard manufacturing processes, while the assembled structure creates the aerodynamic shape needed to reduce drag on the cargo box front wall.
2Loss of energy
If curved streamlined surfaces are employed to reduce drag, then the aerodynamic efficiency improves, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The fairing panels are designed with curved surfaces that smoothly redirect airflow around the cargo box front wall. The curvature is optimized to create a streamlined shape that reduces form drag by minimizing flow separation and pressure differential, while the panels themselves maintain simple geometric forms that are manufacturable using conventional techniques.
3Device complexity
If the cargo box front wall is exposed to headwinds, then the vehicle structure is simple, but the power consumption increases cubically with wind speed
Solution Approach 1:
The fairing acts as an intermediary structure positioned between the vehicle cab and the cargo box front wall. It modifies the airflow pattern in this region by redirecting headwinds laterally around the sides of the cargo box, thereby reducing the direct impingement of high-speed air on the blunt front wall and decreasing the associated drag and power consumption.
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 approach reduces aerodynamic drag, resulting in potential fuel efficiency improvements of 1-2% for class 6-8 trucks, with configurations optimized for specific vehicle types based on operating conditions and cost-effectiveness.
Implementation Method 1
The displacement of air around a moving object creates a difference in pressure between the forward and trailing surfaces thereof, resulting in a drag force on the vehicle that is highly dependent on the relative wind speed acting thereon. Streamlining the vehicle surfaces can reduce the pressure differential developed thereon, thereby reducing form drag on the vehicle.
Implementation Method 2
Frictional drag forces also depend on the speed of wind impinging exposed vehicle surfaces, and arise from the contact of air moving over surfaces. Both these types of drag forces arise generally in proportion to the square of the relative wind speed, per the drag equation. Streamlined geometries are generally employed to reduce both of these components of drag force on various vehicle surfaces.
Data Source
AI summary
Aerodynamic fairing devices divert rising headwinds lifted over the top of a truck more laterally outwards to reduce vehicle drag. Embodiments include a truck cab roof mounted fairing, a streamlined truck cab roof, a fairing visor disposed on either cab roof fairing or on a streamlined truck cab roof, and a forwardly open-box sidewall assembly disposed on an upper portion of the front wall of a cargo box of a truck or semitrailer.