Aerodynamic drag reduction of a simplified squareback vehicle using steady blowing

• Published in: Experiments in fluids Vol. 53; no. 2; pp. 519 - 529
• Main Authors: Littlewood, R. P., Passmore, M. A.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.08.2012; Springer
• Subjects: Aerodynamic drag; Aerodynamics; Applied sciences; Automobiles; Automotive components; Automotive engineering; Blowing; Engineering; Engineering Fluid Dynamics; Engineering Thermodynamics; Exact sciences and technology; Fluid dynamics; Fluid- and Aerodynamics; Fundamental areas of phenomenology (including applications); Ground, air and sea transportation, marine construction; Heat and Mass Transfer; Instrumentation for fluid dynamics; Physics; Research Article; Road transportation and traffic; Wakes; Ride Height; Momentum Coefficient; Drag Reduction; Coanda Effect; Aerodynamic Drag; Drag reduction; Road vehicle; Test facility; Wind tunnel test; Hot wire anemometer; Speed measurement; Aerodynamics; Particle image velocimetry; Model test; Pressure measurement; Experimental study
• ISSN: 0723-4864; 1432-1114
• DOI: 10.1007/s00348-012-1306-4

A large contribution to the aerodynamic drag of a vehicle arises from the failure to fully recover pressure in the wake region, especially on squareback configurations. A degree of base pressure recovery can be achieved through careful shape optimisation, but the freedom of an automotive aerodynamicist to implement significant shape changes is limited by a variety of additional factors such styling, ergonomics and loading capacity. Active flow control technologies present the potential to create flow field modifications without the need for external shape changes and have received much attention in previous years within the aeronautical industry and, more recently, within the automotive industry. In this work the influence of steady blowing applied at a variety of angles on the roof trailing edge of a simplified ¼ scale squareback style vehicle has been investigated. Hot-wire anemometry, force balance measurements, surface pressure measurements and PIV have been used to investigate the effects of the steady blowing on the vehicle wake structures and the resulting body forces. The energy consumption of the steady jet is calculated and is used to deduce an aerodynamic drag power change. Results show that overall gains can be achieved; however, the large mass flow rate required restricts the applicability of the technique to road vehicles. Means by which the mass flow rate requirements of the jet may be reduced are discussed and suggestions for further work put forward.