Sloping Rear Trailer Section for Aerodynamic Drag Reduction
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Solution Overview
Problem
Conventional tractor-trailer combinations experience excessive aerodynamic drag due to the shape of the trailer, which leads to increased fuel consumption and reduced handling characteristics when attempts are made to improve aerodynamics, often at the cost of carrying capacity and increased weight.
Innovation Solution
The trailer design features a sloping rearward section that reduces the low-pressure zone behind the trailer, maintaining cargo capacity while incorporating adjustable wheel assemblies and landing gear for seamless loading and unloading at standard dock heights, thereby reducing aerodynamic drag.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the trailer shape is made more aerodynamic by adding panels or inflatable bladders, then aerodynamic drag is reduced, but weight increases and trailer length is significantly extended
Solution Approach 1:
The trailer body is divided into a forward horizontal section and a rearward sloping section, with the sloping section angled downward from front to rear. This segmentation allows the rearward section to reduce wake formation and aerodynamic drag while maintaining a compact overall length, avoiding the need for additional panels or bladders that would increase weight.
Solution Approach 2:
The rearward section of the trailer is configured to slope downward in the vertical dimension, creating an angled surface that redirects airflow more efficiently. This dimensional change allows the trailer to reduce aerodynamic drag through its geometry alone, without adding weight through additional components.
2Loss of energy
If the trailer shape is made more aerodynamic, then aerodynamic drag is reduced, but carrying capacity is reduced
Solution Approach 1:
The trailer body is divided into a forward horizontal section and a rearward sloping section, with the sloping section angled downward from front to rear. This segmentation allows the rearward section to reduce wake formation and aerodynamic drag while maintaining a compact overall length, avoiding the need for additional panels or bladders that would increase weight.
Solution Approach 2:
Only the rearward section of the trailer is configured with a downward slope, while the forward section maintains a standard horizontal configuration. This local modification optimizes aerodynamic performance at the rear where wake formation occurs, without compromising the overall cargo volume and carrying capacity of the trailer.
3Loss of energy
If the rearward end of the trailer is lowered to reduce aerodynamic drag, then drag forces are reduced, but docking height becomes non-standard
Solution Approach 1:
The wheel assembly is made movable along the trailer frame, allowing dynamic adjustment of the rearward end elevation. The wheel assembly can be positioned at a first location to lower the rearward end for optimized aerodynamics during transport, and at a second location to raise the rearward end to standard docking height for loading operations, thus resolving the contradiction between drag reduction and ease of docking.
Solution Approach 2:
The trailer design incorporates a downward slope in the vertical dimension at the rearward section, which reduces aerodynamic drag. The movable wheel assembly compensates for this vertical change by adjusting the elevation of the rearward end, allowing the trailer to maintain both the aerodynamic benefits of the sloped design and the operational requirement of standard docking height.
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 configuration effectively decreases aerodynamic drag while maintaining standard cargo capacity and facilitating easy loading/unloading, enhancing fuel efficiency and handling characteristics.
Implementation Method 1
the rearward section adjoins the forward section and slopes downwardly with respect to the forward section as it extends rearwardly thereof such that an angle is generated between the forward section bottom and the rearward section bottom
Implementation Method 2
current bluff bodies, such as trailer 24, which is suitable for use with tractors of the Class 8 type, suffer from a low-pressure zone at the rear of the trailer such that the air stream 50 suffers from early separation, resulting in a broad eddying wake 30 forming downstream of the separation
Data Source
AI summary
Trailers, such as semi-trailers, having configurations that improve the aerodynamic efficiency thereof are provided. In some examples, aerodynamically configured trailers are provided that maintain standard cargo capacity. To improve the aerodynamic efficiency, the rearward end of the trailer in some embodiments include a downward cant or slope. In use, the rearward cant or slope reduces the low-pressure region that trails the end of the trailer, thereby reducing pressure drag. In accordance with another aspect, to accommodate loading and unloading of the downwardly canting or sloping trailer, examples of the trailers may also be equipped with “sliding trailer axle” and/or extended travel landing gear so as to allow the trailer to interface with standard loading dock heights as well as rampless ground loading/unloading.