MECHANICAL MEASUREMENTS: SPECIAL REFERENCE STANDARD AND CALIBRATION METHOD FOR INSTRUMENTS MEASURING AIRFLOW VELOCITY (DISCUSSION)

摘要

A description is given of the draft of α new norm -α method which has been developed for calibrating instruments that measure high subsonic and supersonic airflow velocities and which is based on the sue of a special reference standard (SRS) for the Mach-number unit w/ α within the range M=0.3-4.0 (where w is absolute velocity and a is sonic velocity). The reference standard reproduces the Mach-number unit with α standard deviation no greater that the deviation obtained from ten independent measurements S_M=0.002-0.0002M, which is equivalent to an error of absolute velocity S_W=(0.002-0.0002w) m/sec. Here, α is sonic velocity at the temperature of the flow. Working standards and control specimens are also examined. The errors made in their comparisons with the SRS and worrying instruments are stipulated along with the ranges of the allowable absolute errors of the working instruments.