The Measurement of Wake and Gap Flows of the Generic Conventional Truck Model (GCM) using Three-Component PIV

Abstract

Particle Image Velocimetry (PIV) measurements were acquired in the wake of the trailer and in the gap between the tractor and trailer of the Generic Conventional Model (GCM) truck for the US Department of Energy. The data will be used both for validation of computational fluid dynamics (CFD) codes and for understanding the flow physics. The GCM is a 1/8^th-scale, moderate-fidelity model of a full-scale truck. The test was performed in the Army/NASA 7 × 10 wind tunnel at NASA Ames Research Center. Surface pressure and force measurements were made prior to the PIV measurements. PIV measurements were made at two yaw angles and at three horizontal planes for three model configurations, each at a free-stream velocity of 52 m/s (Mach 0.15), which corresponds to a Reynolds number of 1 × 10⁶, based on the width of the tractor. This paper discusses the PIV system, samples of flow data and some of the observed features that may have contributed to the measured drag.