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黑体空腔理论在一些作者的努力下,逐渐趋于完善。目前,正注意空腔理论的实际应用。一些人曾把空腔和辐射检测器联系起来,用近似方法计算了积分空腔发射率,但由于晕光区的存在,这种计算结果和真值不同。实际应用中,检测器不可能离开空腔开口处太远,因此,当检测器位于离腔口某个有限距离时,精确计算空腔发射率是有意义的。本文给出一种精确计算带盖板的圆锥和圆柱空腔的积分发射率方法,并且使用电子计算机计算了数值结果,同时和别德福德(Bedford,R.E.)的近似方法做了比较。结果表明:当H=0和H→∞时(此处H表示从空腔口到检测器间的距离),对相同的空腔,两种方法得到的积分发射率ε~c结果一致。而当H在实用范围内,特别是对于表面发射率较低的短圆柱空腔和半顶角较大的圆锥空腔而言,两种方法得到的ε~c值是不同的。
The theory of black-body cavity gradually tends to be perfect under the efforts of some authors. At present, attention is paid to the practical application of cavity theory. Some people have connected the cavity with the radiation detector and calculated the cavity emissivity in a similar way, but this calculation differs from the true value due to the halo area. In practice, the detector can not be too far away from the cavity opening, so it makes sense to accurately calculate the cavity emissivity when the detector is located at a finite distance from the cavity. In this paper, an accurate method for calculating the integral emissivity of conical and cylindrical cavities with a cover plate is given. The numerical results are calculated by computer and compared with the approximate method of Bedford, R.E. The results show that when H = 0 and H → ∞ (where H denotes the distance from the cavity port to the detector), the results of the integral emissivity ε ~ c obtained by the two methods are the same for the same cavity. The values of ε ~ c obtained by the two methods are different when H is in the practical range, especially for the short cylindrical cavity with lower surface emissivity and the larger conical cavity with the semi-top angle.