Heavy trucks fuel savings using the SaOB actuator

This paper describes a development program taking small scale Aerodynamic laboratory experimental technology to full-scale road tests. The fuel saving concept is based on attaching a 135mm radius, quarter circle cross-section device, to the rear-side of truck-trailers. A full-scale conceptual prototype was designed and characterized by TAU and adopted as a full-scale adjustable and cost-effective prototype by ATDynamics. Bench-top tests at TAU validated the performance of the prototype as sufficient to warrant full-scale test success. Based on the bench-top tests it was decided that full scale inlet pressures of 3–6 psi at flow rates of 1–1.5 L/s per actuator are required. The full-scale prototype device comprised of some 100 suction and oscillatory blowing (SaOB) actuators’ array with a common compressed air supply. A positive displacement pump operated by a gasoline engine supplied the compressed air. As part of an ongoing ATD research project, a series of road tests were performed at the Goodyear Proving Ground, San Angelo, TX. Two identical trucks were tested. One truck-trailer was standard, while the other was equipped with the TAU-ATD device. Gauges located just downstream of the pump and at 5 locations along the supply ducts measured the supply pressures. Portable sensors measured the device suction pressure and pulsed blowing frequency. It was found that the pressure drop in the supply ducts was 10–15%. However, additional 35% pressure drop existed in the flexible tubes between the ducts and SaOB actuators. Out of the 81 possible configurations, determined by a 3 by 3 parameter space, 5 configurations were actually tested with valid results. One configuration, measured twice at a driving speed of 65MPH, provided 5% increase in fuel economy (not counting the input pump energy). This translates to a 1.75 L/100km savings or 1L/100km taking into account the flow power invested. This improvement was obtained with inlet pressure lower than 4 psi, marginal according to all previous tunnel and bench-top tests. Furthermore, it is still open how close to optimal is this device configuration. With significantly reduced pressure losses, resulting in 5–6 psi inlet pressure at 15% the current required input energy it is expected that 6–9% net fuel saving would be obtainable in future road tests, potentially leading to the most compact commercial product to date.