Dynamic strain is an important measuring parameter for analyzing and treating pipeline vibration problems in rocket engines.Methods for suppressing fiber Bragg grating(FBG)spectral distortion in low-temperature pipeline's dynamic strain measurement were studied.Three methods of packaging and installing FBG strain sensor,which are suitable for small pipeline with a diameter of no more than 30 mm,have been picked up and evaluated experimentally.The first method is bonding the whole stretched FBG and its both sides to the pipeline surface.The second method is bonding the both sides of stretched FBG to the pipeline surface.The third method is bonding the capillary tube covering stretched FBG and both sides of the FBG to the pipeline surface.In the liquid nitrogen test,four FBGs covered with capillary tubes did not undergo spectral peak splitting.Among them,reflection spectra of three FBGs had no more than 5%relative changes in the full width at half maxim(FWHM)and no more than 6%relative changes in peak intensity,which shows that spectral distortion was suppressed successfully.Measured result of FBG covered with capillary tube is consistent with the strain induced by thermal expansion of pipelines.The method bonding the capillary tube covering stretched FBG and both sides of the FBG is prospected to be applied to the dynamic strain measurement for rocket engines with small-diameter and low-temperature pipelines.
万方数据
维普
