Study on Tip Clearance Measurement System : 2nd Report, Characteristics of the System and Measurement

Abstract

Using the discharge-type blade tip clearance measurement system which was designed for testing, the following were clarified. According to Paschen's law, gas pressure exerts an effect on the measured values; however, the result of the experiment showed that the measured values were not affected by pressure with the minimum discharge voltage. It was confirmed that when the speed of the probe was high, sometimes the probe came in contact with the blade tip. Since there exists a time constant for voltage restoration in discharge signals, there is a limit beyond which the continuous signals can not be obtained. This was examined theoretically and confirmed experimentally. As a result of measuring the blade tip clearance at a peripheral speed of 400 m/s, the elongation of a rotating object due to peripheral speed could be measured.