Aerodynamic Caps for Underbody Storage Box Drag Reduction
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Solution Overview
Problem
Underbody storage boxes on trucks and tractor-trailer rigs increase pressure drag and turbulence, leading to reduced fuel economy and increased emissions, as they are not aerodynamically optimized.
Innovation Solution
The integration of aerodynamic caps and a strake on the underbody storage box, featuring triangular side panels and angled front panels, reduces drag by smoothing airflow and minimizing pressure hotspots.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of stationary object
If underbody storage boxes are added to trucks, then cargo storage capacity is improved, but pressure drag and turbulence increase
Solution Approach 1:
The patent applies curved aerodynamic caps to the front and rear ends of the rectangular storage box. The caps feature rounded, curved surfaces that guide airflow smoothly around the box, replacing the sharp edges of the rectangular shape. This curvature reduces flow separation and turbulence, thereby decreasing pressure drag while preserving the box's storage volume.
Solution Approach 2:
The patent modifies the geometric parameters of the storage box by adding caps with specific curvature radii and angles. The front cap has a rounded leading edge with a specific radius of curvature, and the rear cap has a tapered shape with defined angles. These parameter changes optimize the box's aerodynamic performance, reducing drag coefficients while maintaining storage capacity.
2Force
If aerodynamic caps are added to storage boxes, then drag reduction is improved, but device complexity increases
Solution Approach 1:
The aerodynamic modification is segmented into separate, modular caps that can be independently manufactured and attached to the storage box. The front cap and rear cap are distinct components, each optimized for its specific location. This segmentation allows for simplified manufacturing and assembly, reducing overall device complexity while achieving drag reduction.
Solution Approach 2:
The aerodynamic caps serve as intermediary elements between the storage box and the surrounding airflow. Rather than redesigning the entire storage box structure, the caps act as intermediate components that modify airflow patterns. This approach simplifies the overall design by isolating the aerodynamic optimization to separate attachable components.
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 aerodynamic features result in a calculated 7% reduction in drag when combined with a strake, improving fuel economy and reducing emissions by enhancing airflow efficiency.
Implementation Method 1
Drag is a force that resists the movement of a body through a fluid... Pressure drag is a force that acts perpendicular to a surface. Pressure drag is a function of the surface area in the direction of travel as well as the velocity or speed at which the body is traveling.
Implementation Method 2
Pressure drag increases as the square of velocity so that doubling vehicle speed actually creates four times more pressure drag. On the other hand, pressure drag is directly related to surface area so that a ten percent reduction in surface area leads to a ten percent decrease in pressure drag.
Implementation Method 3
Pressure drag in land vehicles, and especially in trucks, is increased by pressure 'hot spots', such as beneath the undercarriage, behind the rear of the trailer or between the tractor and the trailer. These hot spots are generally regions of low pressure which causes air flowing over the vehicle to deviate from a streamlined path around the vehicle.
Data Source
AI summary
An underbody storage box assembly mountable beneath a vehicle body includes a storage box mountable to the underbody of the vehicle body, the storage box having a leading face and a trailing face in the direction of travel of the vehicle. The assembly is provided with a pair of like-configured aerodynamic caps, one mounted at the leading face of the storage box and the other mounted at the trailing face of the storage box. Each of the aerodynamic caps includes opposite side panels, each having a substantially triangular shape with a rear edge abutting the storage box, a base edge that is substantially perpendicular to the rear edge, and a front edge that is arranged at an acute angle relative to the base edge. A front panel is connected between the opposite side panels at the front edge.