Steam turbine disk resource with initial defects of discharge openings area under creep

• Дата: 2015
• Автори: Шульженко, Н. Г., Гонтаровский, П. П., Матюхин, Ю. И.
• Формат: Стаття
• Мова: Russian
• Опубліковано: Journal of Mechanical Engineering 2015
• Теми: turbine; resource; creep; scattered damage; discharge openings; УДК 539.3; 621.165; турбина; ресурс; ползучесть; рассеянные повреждения; разгрузочные отверстия; турбіна; повзучість; розсіяні пошкодження; розвантажувальні отвори
• Онлайн доступ: https://journals.uran.ua/jme/article/view/46683
• Назва журналу: Journal of Mechanical Engineering

The impact of the hypothetical defects (nicks and scratches) in the steam discharge openings area of disc 2nd stage on medium pressure turbine K-300-240-2 rotor resource under creep is considered. Evaluation of disc damage in the area of openings is investigated with three-dimensional finite element method with simultaneously solving the linked creep and damage equations with two phenomenological parameters: scalar and vector, witch responsible for viscous and brittle failure of the material, respectively. It is shown that the presence of defects reduces the time to crack initiation, but increases the time of its evaluation to a critical size. Nick in the discharge opening is modeled by two damaged finite elements at the area of the median plane of the disk. And the scratch is modeled by number of damaged elements along the thickness of the disk surface. In case of occurrence of a crack during nicks is approximately three times less than in the absence of damage. The time of crack initiation caused by nicks is approximately three times less than in the absence of damage. The time of crack initiation is six times less in case of scratch, accordingly. However, the total resource in the first case is 60% compared with intact disk resource, and in the second case - 25%. Thus, the defect reduces the time until the crack, but increases the time of its evaluation to a critical size. Slight damage in the discharge openings area may have a significant impact on the disc resource.