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The demand for light weight vehicles continues to stimulate extensive research into the development of light weight casting alloys and optimization of their manufacturing processes. Of primary relevance are Aluminum (Al) and Magnesium (Mg) based alloys, which have successfully replaced selected iron based castings in automobiles. However, optimization of as-cast microstructure, processing and performance remains a challenge for some Al-based alloys. In this context, placement of chills in castings has been frequently used to locally manipulate the solidification conditions and microstructure of a casting. In this work, the effect of using an active copper chill on the residual strain profile of a sand-cast B319 aluminum alloy was investigated. Wedge-shaped castings were produced with three different cooling conditions: copper plate chill, copper pipe with cooling water and no chill (baseline).

The 9-meter wind tunnel of the National Research Council (NRC) of Canada is equipped with a boundary layer suction system, center belt and wheel rollers to simulate ground motion relative to test articles. Although these systems were originally commissioned for testing of full-scale automotive models, they are appropriately sized for ground simulation with half-scale tractor-trailer combinations. The size of the tunnel presents an opportunity to test half-scale commercial vehicles at full-scale Reynolds numbers with a model that occupies 3% of the test section cross-sectional area. This study looks at the effects of ground simulation on the force and pressure data of a half-scale model with rotating tractor wheels. A series of model changes, typical of a drag reduction program, were undertaken and each configuration was tested with both a fixed floor and with full-ground simulation to evaluate the effects of this technology on the total and incremental drag coefficients.