Temperature Measurement Method of Falling Small Steel Balls Heated to a High Temperature by Using the Photographic Photometry Technique

Abstract

  In this paper, in order to clarify the temperature changes of falling small steel balls heated to a high temperature which simulate scattering particles produced during welding works, we have studied a method for continuous temperature measurement of the balls using the photographic phometry technique. The results are summarized as follows:
  1) The best combination of the low pass filter (j) and the high pass filter (k), can be determined using transmittance of filters and calculated transmitted energy.
  2) Denoting the flux of incident light and transmitted light through low pass and high pass filters as F₀, F_j and F_k respectively, flux ratios (F_j/F₀) and (F_j/F_k) are represented as a function of the temperature T and the exposure time Δt as follows:
  F_j/F₀=U(T, Δt), F_j/F_k=V(T, Δt)
  3) These two flux ratios can be determined experimentally by recording two line images of falling small steel balls heated to a high temperature using the best filter combination.
  4) By solving the above two equations, the temperature T can be obtained. It is confirmed that the best filter combination is effective for estimating the temperature of the balls.