Device and method for measuring radial air gap with millimeter waves

摘要

The method involves continuously transmitting millimeter wave by a transmitter and receiver unit (60) accommodated in a region of a housing wall (100) of a turbine housing (10). The millimeter wave reflected at a radial outer edge (30) is received by the transmitter and receiver unit. A profile of the outer edge is detected in direction of movement of a turbine blade (20) by subsequent focusing with help of numeric process. The distance between a blade edge and the housing wall is determined by a phase analysis of the received millimeter wave.