Directed Air System for Tractor Aerodynamic Drag Reduction
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Solution Overview
Problem
Conventional tractor-trailer combinations experience significant aerodynamic drag due to bluff body characteristics, particularly the abrupt transition at the leading edge of the tractor hood, leading to airflow separation and increased pressure losses.
Innovation Solution
A drag reduction system that generates and directs pressurized gas forwardly and outwardly from the front section of the vehicle, using exhausted gases or air flow from fans, to create a 'soft' fairing and reduce aerodynamic drag by minimizing airflow separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the front section of the tractor is designed with a bluff body shape (vertical front surface meeting horizontal top surface), then the structural simplicity and ease of manufacture are improved, but aerodynamic drag increases due to airflow separation at the leading edge
Solution Approach 1:
A directed air system acts as an intermediary between the ambient air and the bluff body front section. The system introduces a controlled stream of directed air that attaches to the hood top surface, serving as a mediator that prevents the separation of the main airflow from the abrupt geometric transition, thereby reducing pressure drag while maintaining the simple bluff body structure
Solution Approach 2:
The invention employs pneumatic principles by using a stream of directed air (gas flow) to control the aerodynamic behavior at the front section. The directed air stream creates a low-pressure region that attracts the ambient airflow to remain attached to the hood surface, utilizing fluid dynamics to mitigate the harmful effects of the bluff body geometry without requiring structural modification
2Object-affected harmful factors
If aerodynamic fairings are used to gradually increase the frontal area and blend smoothly with the trailer, then aerodynamic drag is reduced, but device complexity and manufacturing cost increase
Solution Approach 1:
The invention extracts the aerodynamic function from the physical structure. Instead of incorporating complex fairings that physically blend the tractor front with the trailer, the system extracts the drag-reduction function and achieves it through a directed air stream that creates a virtual aerodynamic profile, eliminating the need for additional physical components
Solution Approach 2:
The invention changes the parameter of airflow characteristics rather than modifying the geometric parameters of the vehicle structure. By controlling the direction, pressure, and velocity of the directed air stream, the system dynamically alters the effective aerodynamic profile of the tractor front, achieving drag reduction without changing the physical shape or adding complex structures
3Object-affected harmful factors
If the hood is sloped downwardly from the windshield to reduce abrupt transitions, then airflow separation is reduced, but packaging space for under-hood components is compromised
Solution Approach 1:
The directed air stream serves as an intermediary that compensates for the abrupt geometric transition caused by the conventional hood design. The controlled air flow attaches to the hood surface and prevents separation, allowing the maintenance of the traditional vertical-to-horizontal hood transition without compromising component packaging space
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 system effectively reduces aerodynamic drag by creating a stagnation region in front of the vehicle, resulting in lower pressure losses and improved fuel efficiency.
Implementation Method 1
A drag reduction system that generates and directs pressurized gas forwardly and outwardly from the front section of the vehicle
Implementation Method 2
The air flow passing over the front section, therefore, must negotiate an abrupt change in direction as the edge where the hood structure transitions from a substantially vertical orientation to a substantially horizontal orientation. This abrupt turn causes the flow to 'separate' from the top surface of the hood, forming a highly turbulent region of air
Data Source
AI summary
Systems and methods are disclosed for improving the aerodynamic efficiency (e.g., reduce drag) on vehicles, such as class 8 tractors. In some disclosed examples, the systems and methods utilize exhausted gases from an internal combustion engine of the vehicle to direct a stream of gas forwardly of the vehicle. In other disclosed examples, the systems and methods utilize generated air flow from, for example, electric fans, engine driven or pneumatically/hydraulically driven pumps, etc., to direct a stream of gas forwardly of the vehicle for reducing the aerodynamic drag on vehicles. In yet other disclosed examples, the systems and methods utilize a unique configuration of the vehicle's radiator fan(s) in order to direct a stream of gas forwardly of the vehicle.