旋转不均匀度 在一定期间内压缩机驱动轴的最大和最小瞬时转速之差与其算术平均值之比值
Rotational unevenness is the ratio of the difference between the maximum and minimum instantaneous speeds of the compressor drive shaft within a certain period to their arithmetic mean
以上为机器翻译结果，长、整句建议使用 人工翻译 。