CTA measurements in turbulent flows in the presence of heat transfer

Data related to the development of and the measurement procedure for hot-wire probes, which are applicable to the measurement of nonisothermal flows in the vicinity of a wall, are analyzed. The difficulties encountered in measuring the three-dimensional characteristics of nonisothermal flows are examined. The relation between the angle of incidence of the hot-wire probes and the measurement results is studied. A sensor was designed with the hot wire parallel with the coil, and the sensor is applied to measurement of the mean velocity vector and turbulent energy in low-velocity nonisothermal turbulent air flows. The effects of vicinity of the heat conducting wall on the velocity measurements and of the prongs' thickness on the temperature measurements are investigated. The accuracy of the hot-wire velocity and temperature fluctuations measurements is evaluated. It is observed that the hot-wire measurement of velocity and temperature fluctuations are affected by: (1) the limited frequency resolution of the sensor, (2) the cooling and stabilizing effect of the prongs, and (3) the limited spatial resolution of the sensor.