Semi Trailer Major Drag Hypothesis

Hypothesis

If the height of the tractor-trailer model is increased, the drag forces opposing the tractor-trailer’s movement will increase correspondingly. This is due to the increased form drag forces resulting from an increased pressure differential between the front and rear of the tractor-trailer. This pressure differential will be larger because a greater amount of high-pressure air will accumulate in front of the vehicle, will attain a greater pressure and because the low pressure area behind the trailer will decrease in pressure and increase in size.
If the distance between the cab of the tractor and the trailer is reduced, the effect will be a reduction in the drag forces restricting the tractor-trailer’s motion. If the distance is increased, the drag forces will increase as well. This is because greater cab-trailer distances will result in more air becoming trapped in the resultant gap, thus negating the aerodynamic design of the tractor.
If a fabric sleeve is used to connect the cab of the tractor to the trailer, the drag forces associated with the cab-trailer distance will be reduced. This is because the sleeve will prevent the air flow from moving into the gap, instead encouraging it to flow smoothly over the trailer.

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Project Info References Acknowledgments Conclusion Sources of Error Further Research Overview Hypothesis Procedure Results Overview Background Objectives Hypothesis Construction/Details Testing Overview Background Plan	Hypothesis If the height of the tractor-trailer model is increased, the drag forces opposing the tractor-trailer’s movement will increase correspondingly. This is due to the increased form drag forces resulting from an increased pressure differential between the front and rear of the tractor-trailer. This pressure differential will be larger because a greater amount of high-pressure air will accumulate in front of the vehicle, will attain a greater pressure and because the low pressure area behind the trailer will decrease in pressure and increase in size. If the distance between the cab of the tractor and the trailer is reduced, the effect will be a reduction in the drag forces restricting the tractor-trailer’s motion. If the distance is increased, the drag forces will increase as well. This is because greater cab-trailer distances will result in more air becoming trapped in the resultant gap, thus negating the aerodynamic design of the tractor. If a fabric sleeve is used to connect the cab of the tractor to the trailer, the drag forces associated with the cab-trailer distance will be reduced. This is because the sleeve will prevent the air flow from moving into the gap, instead encouraging it to flow smoothly over the trailer. Move on to the Procedure page.