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A new method for streamlining tractor-trailer trucks based on weakening turbulent vortices in regions of separated flow using a flexible surface Deturbulator tape patented by the author. Minimal Deturbulator application on the tractor-cab sides yielded 4% improved fuel mileage by de-energizing recirculating vortices in the tractor-trailer gap. The entire trailer, especially flatbeds with loads can be encapsulated within a quiescent separated bubble by extending Deturbulator application to the tractor. It makes the truck appear more streamlined to the airflow evidenced by 13-30% fuel economy improvement. The Deturbulator configured as a replaceable strip provides a cost effective fuel savings add-on for already streamlined class-8 tractors, which does not impede normal operations..

A new method for reducing aerodynamic drag of trucks and vans has been developed. It uses Deturbulator tape to transform separated turbulent wakes into stagnant virtually solid streamlining extensions attached to the vehicle. Constrained mode flow-induced surface oscillations of the 100-μm thick, passive, flexible-surface Deturbulator tape attenuates turbulent mixing by driving the turbulence to a pre-selected high frequency in the dissipation range. Wind tunnel tests indicated 80% drag reduction. Road tests on a minivan and pickup truck showed 15-20% increased highway fuel economy due to reduced drag. 6% reduction in overall fuel consumption was obtained for an operational Class-8tractor-semitrailer.

The effect of three different modes of acoustic excitation on an unsteady separating flow over a circular cylinder at a Reynolds number (Red) of about 1.5×105 has been investigated. The acoustic exciters included (I) a speaker mounted inside the cylinder and blowing through a narrow spanwise slot; (II) a circular piezo-electric acoustic transducer mounted flush with the surface; and (III) strip shaped flush mounted acoustic transducers. The first mode of excitation was judged most effective at about 1.3 kHz, based on changes in the time-averaged surface pressure distribution on the cylinder. The corresponding frequencies for (II) and (III) were 7 kHz and 2.25 kHz respectively. The transducers (II) and (III) did not introduce the blowing and suction effects of transducer (I). Transducer (II) increased the mean surface pressure slightly, while (I) and (III) reduced it.