Abstract
In this study, simultaneous measurement of the temperature at two points with cold-wire sensors is performed at three different downstream locations of a heated plane jet. The measurement apparatus consists of a wind tunnel, a skimmer, a side-wall, and a heater set at the blower intake of the wind tunnel. The temperature of the jet is controlled to become 5 K higher than the ambient fluid. A thin tungsten wire whose diameter is 3.0 μm is used as a sensor and is connected to the self-made constant current circuit. The output of the cold-wire sensor is compensated theoretically to increase the temporal resolution in the measurement. By applying the Karhunen-Loeve (KL) expansion in space and time, the development of the structure in the heated plane jet is investigated from the viewpoint of both space and frequency. Measurement results show that the dominant mode of the fluctuating temperature field in a plane jet expresses and relates to a flapping motion, which is the large-scale coherent vortex structure in the plane jet.
