Turbine blade displacement measuring method, comprises measuring variations in time taken for turbine tip to pass when blade is at specific angles

摘要

The time (t0-t1) between the first signal (t0) for the turbine shaft rotation position and the second signal (t1) for the passage of a turbine tip is measured for at least three specific turbine blade angles (alpha1-alpha3) and any variation in this time is recorded in relation to the turbine output. The angular velocity (gamma) is also recorded, whilst the time values (t0-t1) are used as starting values for calculating the blade tip position in terms of x and y-coordinates for its intersection points (S0-1, S0-2, S1-2) or a centre of rotation (P, P) for the blade. Step sequences (a-d) for a suitable number of cycles are prepared to obtain these values over the blade tip intersection points (S) as a function of the respective blade angle, in order to generate a tangent curve (20) for the blade tip edges or determine the centre of rotation for the blade. A sensor device (8) connected to the turbine shaft generates the first signal and a sensor device (16, 18) inside the turbine wheel chamber generates the second signal.