London Taxi opens £300M plant for range-extended EV taxis; announces second model, an LCV
ABS issues Approval in Principle for LNG-fueled design concept for bulker

Lawrence Livermore Lab researchers significantly boost truck fuel efficiency through improved aerodynamics

Lawrence Livermore National Laboratory (LLNL) researchers, as part of a Navistar SuperTruck I team, helped design a new type of tractor trailer truck that improves fuel economy by 124%, compared to heavy vehicles on the road today.

Seventy-four percent out of the 124% improvement comes from aerodynamic enhancements, while the rest comes from engine efficiency, tire rolling resistance, light weighting and other advancements. On a track test, the new SuperTruck I vehicle achieved 13 mpg (18.1 l/100 km), compared to a typical truck on the road that gets around 5.8 mpg (40.5 l/100 km).

Llnl

Fuel efficiency improves by 74% due to aerodynamic enhancements, equating to 21 billion gallons of diesel fuel saved, 210 million tons of reduced carbon dioxide emissions and $52 billion saved at an average diesel price of $2.51 per gallon annually.

For heavy vehicles, most of the engine’s usable energy goes into overcoming drag and rolling resistance at highway speeds. To combat this problem, the team used computer modeling to demonstrate new aerodynamic body shapes to significantly reduce drag.

Aerodynamic drag is caused from pressure differences around the vehicle—the gap between the tractor and the trailer, the underbody (between the trailer axle and wheels) and the trailer body (base).

The LLNL Generic Speed Form shape has demonstrated a breakthrough in aerodynamic performance of heavy vehicles.

—Kambiz Salari, a fluid dynamics researcher who heads the project

As reported at the DOE Merit Review in 2016, the LLNL Generic Speed Form 2 shows a strong enhanced sailing effect; the GSF2 aerodynamic performance is radically different from a typical heavy vehicle on the road. GSF2 can generate forward force at yaw due to the sailing effect, and demonstrates radical drag reduction.

Llnl2
Supertruck2_inside

The LLNL project is part of the Department of Energy (DOE) Heavy Vehicle Aerodynamic Drag Consortium R&D, which has led to the advances in fuel economy.

Salari and LLNL’s Jason Ortega, as part of Navistar’s SuperTruck I team, have helped improve the aerodynamic design of the SuperTruck. The truck also has other fuel efficiency improvements, such as a more efficient engine, better rolling resistance, fewer tires and other equipment.

The team has performed wind tunnel tests at the Air Force National Full-Scale Aerodynamics Complex (NFAC) at the NASA Ames Research Center and on-the-road testing using full-scale road conditions. The vehicles could be on the highway as soon as five years.

Partners for the SuperTruck I effort include Navistar, Wabash National, Bosch, Argonne National Laboratory, Michelin, Mekra Lang, Delco Remy, PPG Industries, Eaton and Sabic Global.

Future plans include: continuing tractor-trailer integration design for radical improvement in aerodynamic drag and fuel economy; continued use of experiments to design a more advanced integrated tractor-trailer; performing scaled experiments to design and validate the performance of aerodynamic add-on devices for integrated tractor-trailers and tankers; investigating fuel economy benefits of truck platooning (similar to a convoy) in collaboration with the National Renewable Energy Laboratory; and continued coordination of industry participation to design the next generation of highly aerodynamic heavy vehicles.

Resources

Comments

mahonj

Sounds great, but I wonder how easy it will be to load and unload them etc.
We keep hearing about this stuff, but it seems to happen very slowly in the real world.

ai_vin

the new SuperTruck I vehicle achieved 13 mpg

This duplicates the efforts, and results, of other "supertruck" projects I've seen over the years.

SJC

This is what we can do when we work together.
Synergy is more than the sum of the parts.

mahonj

@Al
Duplicates, builds on, replicates: all that is good if it builds a solid body of work that the truck firms can take and use.
The prize for getting this right is very big as there are a lot of trucks, burning a lot of fuel, in every country of the world.

GdB

Can someone explain the math behind zero drag for GSF2 at Yaw angle greater than 23 deg? It must be a tail wind? But the standard and correct way of presenting Cd should never allow negative Cd. Instead show lift and drag coefficient. It's misleading.

ai_vin

@GdB

No, it's not a "tail wind" - it's a "cross wind." The shape of the truck acts like a wing or sail that produces "lift" as well as drag and side forces. Cross wind when added to forward speed gives you an apparent wind at different yaw angles. The right yaw angle can produce more forward lift than rearward drag while any side forces are handled by the tires on the road.
https://en.wikipedia.org/wiki/Forces_on_sails

SatoruRyu

While an interesting and undeniable improvement some real world conflicts in reality..

1) Drop and hook being common practice. Which is all about minimization of driver down time of loading / unloading that can add 1-3 hours cutting into legally allowed time on road. Where after a period of time of combined idle break time / driving a mandatory sleeping period of 10 hours MUST happen mandated by law.

In theory you could mandate all trailers must be of such aerodynamic design yet the side skirts must accommodate shifting of 5th wheel forward or backward to balance the load to minimize road damage and / or handling.

2) The side skirts appear to be fully solid and ideally should be at most 75% solid with the remainder lower portion being a rubber or hinged design to mitigate curb damage or excessive road humps such as around railroad crossings. While it might make it across the tracks it could potentially destructively detach popping their tires and leaving a sizable portion of debris for a train and general civilian traffic.

3) The trucking industry itself is more than willing to edge out better mpg that mandating it isn't fully necessary as fuel is the second largest expense on a cost per mile basis. What an engineer thinks is ideal never accounts for what the person driving or repairing it has to encounter. Time off for repairs means increased costs in labor (highest expense per mile) and potential client contract violations where payment could be reduced.

Yes, they could outsource to final leg of travel to another driver within company or other company completely. Yet, for the downed driver majority get paid by the mile so he'll be taking the financial hit along with the company diverting funds to accommodate the disruption of service.

http://www.rtsfinancial.com/guides/trucking-calculations-formulas

To clarify, I'm not against all this but we must be realistic on how to properly introduce technology that is reliable and safe.

SJC

50% better is 6 MPG instead of 4 MPG, it all adds up.

James McLaughlin

"a typical truck on the road ... gets around 5.8 mpg" but post 2010 tractors might get >7 mpg more often (can anyone help me out here? I don't drive them). And the test track numbers are usually more optimistic than real-world numbers.

Still we are seeing good progress in long-haul configurations, and the trailer skirts are becoming ubiquitous in some markets so the most cost-effective techniques are making it through to the fleet quickly.

Personally, I am more interested in short-haul, where regenerative braking can dramatically improve efficiency and reduce brake dust. Urban transit buses are seeing some market penetration of EVs, but we need short-term incentives for big-payback applications like urban EV refuse trucks. The market volumes are small compared to passenger cars, making it difficult to make big engineering changes without external "encouragement".

SJC

Local delivery like FedEx, UPS and others could really reduce consumption and emissions by using DME hybrids. This is taking a while but progress is being made.

kcir

When stumbling upon this post I went to the source for the post, the 2016 and 2017 DOE Annual Merit Review reports. The subject DOE slides claim “radical drag reductions”, “breakthrough”, “aerodynamic sailing”, “enhanced sailing”, “performance is radically different” , etc… Indicating Nobel Prize type results. However nothing is further from the truth. The claims reflect a limited understanding of aerodynamics as well as the data obtained.

When a test is performed and results are presented there are three areas to assess, test process, data and findings. And there are 3 questions to ask; 1) is the test BAD or GOOD, 2) is the data BAD or GOOD and 3) are the findings BAD or GOOD. Where BAD and GOOD relate to the validity of the item in question. You can have a BAD test with GOOD data and the data can be used to present either BAD or GOOD findings. In fact you can have any combination of the three areas. GOOD findings can be presented for a BAD test that produced BAD data.

Back to the presented material. It appears to be a BAD test with BAD findings but some of the data may be GOOD and some may be BAD. Neither the post or the DOE review material provide sufficient details to determine the status of the data. The results do not show a “sailing effect” that generates a negative drag force. However we can look to peer reviewed published journal documents and NASA reports to decipher the results.

The force labeled drag is actually the axial force (ie body axis system). I know - the body axis is the drag resistive force for a ground vehicle. However, it is well known that a cross wind acting on an aerodynamic forebody will result in a reduction in axial force (see high speed train data) where the axial force can decrease with increasing crossflow. This same effects can be seen for a tapered closed afterbody. These trends are well know and well established by the aerodynamic rail and aircraft communities (not a new revelation). Despite these trends the total drag will not become negative, but will increase with yaw angle, for a constant forward speed. Note; in the current test the representative vehicle forward speed is reduced with increasing yaw angle such that at 90 deg yaw the test would be modeling a stationary vehicle with a cross wind.

The aerodynamics for the subject test body are quite complex are not fully corrected by the author. It is clear that data corrections are not accounting for the following errors in the reported drag force value; blockage at yaw, ground boundary layer, dynamic similitude, Reynolds number, wall interference, force transformation errors between the wind tunnel balance axis and the model axis systems,........


The comments to this entry are closed.