Experimental measurements were performed in a model inlet pipe on the turbulentflow downstream of the throttle valve of a commercial motorcycle carburettor. The inlet pipe was made of a section of straight plexiglass tube to facilitate the access of hot-wire and pressure probes. Continuous dry air was drawn into the model to establish theflow. Theflow downstream of the partly opened throttle valve is found composed of a recirculation region, a three-dimensional jet stream and a wall boundary layer. Complex turbulent flow interactions among the recirculation region, the jet stream and the boundary layer are observed. This study clearly demonstrates that the jet stream, which includes a major portion of the.flow going downstream, shows similarity of axial velocity profiles on planes normal to the angular direction.

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This paper describes the development of a seven-axis probe manipulator which is now in service in a wind tunnel facility at the National Taiwan lnstiiute of Technology. The manipulator is composed of commercially available components, and is controlled by an IBM PC based servomotor controller that implements a robust control algorithm. A precision, non-contact calibration method is developed to align the probe manipulator with experimental coordinates and to measure some of the probe positioning errors. An absolute probe positioning accuracy better than 0.05 mm in all directions is achieved.Integrated with measurement Instruments and capable of translation a?d rotation in three orthogonal directions, this computer controlled probe manipulator provides a dramatic improvement in experimental capabilitv. as demonstrated by a flow fluctuation measurement.