Supplier Spotlight

Video Exclusives

EV lap records

gtr

NIO showcases its blistering Nurburgring Nordschleife lap time, as it topples the existing record.


Hennessy Exorcist Dyno run

gtr

Is this the start of a new automotive power race? In response to Dodge's headline grabbing Demon, Hennessy has introduced the 1000whp, Camaro-based 'Exorcist'.

Click here/on image to watch video

Web Exclusives

« back to listing

Simulating 'realistic wind' for accurate fuel economy

Exa Corporation explains that with a 2% reduction in aerodynamic drag translating to a 1% improvement in real-world fuel economy, just how important realistic wind conditions in simulations

Submitted by: Exa Corporation

 

For a typical car driving at highway speeds, about 50% of the energy is spent to overcome the aerodynamic drag and the other 50% is required to overcome the mechanical losses (engine, transmission, tires, ancillary systems, etc.). This means that every 2% in aerodynamic drag reduction translates to a 1% improvement in fuel economy. As engines, transmissions and low rolling resistance tires become more efficient, especially in the case of electric vehicles, the reduction of vehicle aerodynamic drag under real world conditions on the road has increased impact on the fuel economy and driving range.

In the recent SAE paper (SAE 2015-01-1551) experimental on-road measurements were gathered by comparing the energy consumption of the vehicle with the characteristics of the on-road flow field including traffic turbulence and crosswind, as measured by a pitot-static probe mounted on the roof of the vehicle. The fluctuations in the measured wind are attributed mainly to turbulence caused by other vehicles on the road, while the measured yaw angle is attributed mainly to the prevailing crosswind and large-scale wind gusts. Figure 1 (below) shows the power consumption as a function of yaw angle. The data has been segmented by turbulence intensity, showing the influence of turbulence in addition to yaw angle as a source of drag. Lower turbulence intensities yielded a lower drag value. Conversely, data with high turbulence intensity levels indicated that added turbulence generally decreases yaw sensitivity to drag, but increases overall drag value.

The numerical simulations were carried out using Exa’s PowerFLOW. The realistic flow environment was modeled by including all the relevant traffic turbulence and wind structures that together make up the real on-road environment, including flow structures many times the size of the vehicle. These flow structures, specified at the inlet, evolved in time as they were transported downstream towards the vehicle. On top of these realistic wind fluctuations, a varying crosswind yaw angle was also added. The interaction between yaw angle, turbulence, and the vehicle flow field is illustrated in Figure 2 (below), where streamlines are colored by local yaw angle as they move through the domain. The realistic wind effects resulted in a drag increase of about ΔCD=+0.010, but also a slightly less steep yaw curve, indicating that the effect of realistic wind is more significant near zero yaw than at higher yaw angles.

Both the experimental and numerical data indicate a direct trend between environmental turbulence intensity and power consumption of the vehicle. Basically, this means that the real world conditions, including traffic turbulence and crosswind, will result in a reduction of the fuel economy of the vehicle. Therefore, improving the efficiency and performance of any vehicle on the open road requires that the main features of the real world conditions be included in the simulated environment.

 

23 November 2016

Read Latest Issue

International Engine of the Year Awards
Read Latest Issue
Read Latest Issue

Web Exclusive Articles

Lowering Friction in timing chain drive systems
DSM Engineering Plastics outlines the importance of timing chain drive systems in the overall role of the IC engine, and as regulators continue to press for more efficient engines timing chains are the one area that can yield further gains
Read Now

Engines on test: Lexus 2UR-GSE 5.0-liter V8
The 5.0-liter, naturally aspirated Lexus GS F is most definitely party up front, business out back; much like a reverse mullet. Only the Japanese super sedan carries it off with much, much more class - and dignity
Read Now

Exhaust gas temperature sensors: The future's digital
Patrice Flot, chief technical officer at CMR Group, considers the current approach to sensing exhaust gas temperature (EGT) on high horsepower engine platforms and the capabilities provided by new digital technology.
Read Now


Supplier Spotlight

Supplier SpotlightClick here for listings and information on leading suppliers covering all aspects of the engine technology industry. Want to see your company included? Contact aboobaker.tayub@ukimediaevents.com for more details.

فروشگاه اینترنتی فروشگاه اینترنتی سیستم همکاری در فروش کانال تلگرام چت روم دانلود فیلم مرکز خرید ایرانیان

Submit your industry opinion

Industry BlogDo you have an opinion you'd like to share with the engine technology community? We'd like to hear your views and opinions on the leading issues shaping the industry. Share your comments by sending up to 500 words to d.slavnich@ukimediaevents.com

Submit Your Recruitment Ad

Recruitment AdTo send us your recruitment advertising or to receive information on placing a banner please email aboobaker.tayub@ukimediaevents.com