METHOD OF NONCONTACT MEASURING OF SCREW TRACTIVE FORCE IN COWL SCREW-FAN SYSTEM Russian patent published in 2009 - IPC G01L5/13 

FIELD: physics.

SUBSTANCE: invention can be used for estimation of screw tractive force and diagnostics of radial backlash dangerous value between end face of blade and cowl of the screw-fan system (SFS). Method is realised as follows. The screw blade is considered as elastic element of force-measuring system; tractive force is estimated on strain of the weighted blade leading to bias of its end face in a direction of flight concerning position, corresponding to quasi-static mode on which tractive force is not created and there is no blade strain at the same angular standing of the arbour of the screw. Strain is estimated on the basis of cumulative measuring of multicoordinate bias of end face of the weighted blade in the frame with the beginning in the centre of the data unit end face mounted on the cowl interior surface. Measurings are performed in noncontact manner, on the basis of the eddy current method using a cluster single-turn data unit. The components of biases of the blade end face are determined in gyration direction, in direction of radial backlash between end face and the cowl, in direction of flight for simultaneously gained target signals of measuring channels. By means of blade model as elastic device, the force operating on the blade guided along an axis of the screw is found. Similar evaluations are performed concerning all blades of the screw. The gained tractive powers on each blade are summarised and estimate of tractive force of the screw as a whole is obtained. The SFS safety operation estimation is given by results of comparison of value of the measured radial backlash to admissible level.

EFFECT: increase measuring process informativeness, simplification of means and measuring procedures, and decrease in spadework volume.