A method for measuring temperature and velocity fluctuations in high-temperature turbulent flows

Since hot-wire anemometers cannot be used to measure temperature fluctuations in high-temperature turbulent flows, an attempt was made to develop such a method. It is shown that by using a water-cooled film-coated dielectric capillary as the sensor it is possible to measure not only temperature fluctuations but also velocity fluctuations in high-temperature turbulent gas jets. The capillary is 0.1 to 0.5 mm in diameter; it is coated with a thin-film (0.1 micron) of platinum or some other electrically conducting material, through which an electric current is passed. Placed in a high-temperature flow, the probe is heated by a current and by the flow itself; cooled by a liquid flowing through the capillary, the probe provides stable operation over prolonged periods of time. Fluctuations are measured by applying the voltages produced in the probe to an amplifier. The rms value of the fluctuating voltage-component is recorded with an electronic potentiometer.