PYROELECTRIC ANEMOMETRY - VECTOR AND SWIRL MEASUREMENTS

The characteristics of a vector pyroelectric anemometer that measures the orthogonal components of mass flow are presented. This anemometer consists of three measuring electrodes and two heater elements on a 6 mm X 6 mm chip that form two orthogonal linear anemometers. The charac teristics of a single pair of electrodes forming an in-line linear ane mometer are in good agreement with recent measurements and theory. A w all-mounted vector pyroelectric anemometer is used to measure the deca y of swirl in air flowing through a 45 mm inner diameter, 5 m long flo w system. The swirl flow is produced by a 90 degrees out-of-plane doub le elbow at the flow system inlet. The tube flow generated by a squirr el-cage fan has a Reynolds number of approximate to 24 000, well into the turbulent regime. Measurements are conducted at the wall at a unif orm distance along the length of the flow section for both straight an d swirl flow. The measured decay length is approximate to 40 pipe diam eters, in good agreement with measurements on water.