MEASURING VIBRATION ON TURBINE-BLADES BY OPTICAL MEANS

Following an examination of present-day measuring systems for blade vibration in turbomachines, particular reference is made to 'momentary' processes, which enable all the rotating blades of a row to be observed from the casing for possible damage by vibration. Within this class of measuring systems, optical methods deserve primary consideration, as they alone achieve the high accuracy required. The principle of an optical measuring instrument developed for thermal machines is explained and tests reported on. This system is adaptable, making it universally suitable for investigating all types of vibration in rotating blades.