锅筒翻边开孔交变应力范围捷算法研究

Shortcut Method in Calculating the Alternating Stress Range for a Flanging Open Hole on Steam Drum

为解决我国固定式水管锅炉计算标准和相关研究中锅筒翻边开孔交变应力范围计算的复杂性。按该标准计算方法并结合计算工况下锅炉运行中峰谷应力变化特点,对捷算法计算公式进行了推导和实例验证;对固定式水管锅炉国家标准法计算步骤和计算物理量进行了比较,并对其在船舶动力锅炉上应用的可行性进行了分析;结合已有研究成果,对我国标准规定的锅筒五种开孔型式的捷算法交变应力范围计算公式进行了的适用分类。与我国标准相比,捷算法仅需对每一计算工况下考核点处峰谷值环向应力及其合成主应力进行计算,省略了每一计算工况下三个方向间主应力差的峰谷值计算、主应力差变化范围计算和交变应力范围取值计算。捷算法也适用于具有相同开孔结构和计算应力种类不多于我国标准中的船舶动力锅炉,克服了我国标准法的不足,具有理论和应用价值。

This paper aims to solve the complexity of calculating the alternating stress range for a flanging open hole on steam drum in the Chinese calculating standard of fixed water-tube boilers and related researches.According to this standard calculating method and by combining with the variation characteristics of the peak and valley stresses during a boiler operation under a calculating working condition,the formulas of shortcut method were derived and verified with an example.The comparison of calculating steps and calculating physical quantities with the Chinese standard method of fixed water-tube boilers and the applied feasibility analysis in marine power boilers were given.Combined with the existing research results,the applicable classification of formulas of the shortcut method for calculating the alternating stress range of five open pore types for boiler drum as specified in Chinese standard were reported.Compared with the Chinese standard,the shortcut method only needs to calculate the peak and valley values of both the hoop stresses at the checking point and their resultant principal stresses under each calculating working condition.The calculations under each calculating working condition including the peak and valley values of the principal stress difference between three directions,the variation ranges of principal stress difference and the determination of alternating stress range can be omitted.The shortcut method is also suitable for marine power boilers which have the same open pore structures and the calculating stress types no more than those in the Chinese standard.It overcomes the shortcomings of Chinese standard method,so it has theoretical and application values.