No abstract

The abradable coatings had significantly enhanced turbomachinery performance by acting as a sacrificial seal between rotating blades and stationary casing. Further improvement in seal design to meet the higher energy demand and increase the service time has been the key challenge to solve in the gas turbine industry. Honeycomb seals have become the industry standard clearance seal technique due to their unique design and high structural strength with minimum weight. The present study proposes a concept to form a thermal shock resistance structure to achieve higher temperature capability and improve the reliability of high-temperature abradable seal structures for a hot gas path of turbines. A cavity layer of honeycomb seal structure made of SS 321 alloy was coated with advanced high-temperature ZrO 2 ? 7.5%Y 2 O 3 ? 4% polyester seal material using TriplexPro-210 plasma spray system. The integrity of a seal structure was assessed by a cross-sectional analysis and evaluation of the coating microstructure. Additionally, the micro-hardness test was performed to estimate coating fracture toughness, and finite element analysis was used to assess its thermo-mechanical performance. The concept proposed in this study should be further validated to develop the most capable innovative technology for advanced gas turbine abradable seal structures.

Материал древесины как природный полимер в зависимости от характера теплового движения может находиться в трех релаксационных состояниях: стеклообразном, в котором возможны только колебательные движения атомов в макромолекулах, высокоэластичном, в котором возможны колебательные движения звеньев и сегментов и их взаимная подвижность, вязкотекучем, в котором имеет место подвижность макромолекул и элементов надмолекулярной структуры в целом. Этим состояниям соответствуют агрегатные структуры: первому твердая, второму твердая и третьему жидкая. В тепловом поле при повышении температуры происходят переходы полимера из одного релаксационного состояния в другое. При охлаждении происходят переходы в обратном направлении. В пространственно градиентных температурных полях полимер может находиться одновременно в твердом и жидком состояниях. Представленным трем релаксационным состояниям полимера ставится в соответствие обобщенная модель вязко-упруго-пластического тела. Уравнения движения материала древесины построены на основании феноменологических представлений механики сплошной среды, замыкание уравнений выполнено на основе связи тензора напряжений с тензором деформаций в соответствии с выбранной реологической моделью для материала древесины как полимера. Уравнения построены для однородной сплошной среды, при переходе к неоднородной скалярные релаксационные параметры состояния полимера необходимо представлять в тензорной форме. Данное исследование может рассматриваться как элемент основ механики биополимеров. Wood material, as a natural polymer, depending on the nature of thermal motion can be in three relaxation States: glassy, in which only vibrational movements of atoms in macromolecules are possible highly elastic, in which vibrational movements of links and segments are possible, and their mutual mobility viscous, in which there is mobility of macromolecules and elements of supramolecular structure as a whole. These States correspond to aggregate structures: the first solid, the second solid and the third liquid. In the thermal field, when the temperature rises, the polymer transitions from one relaxation state to another. When cooled, transitions occur in the opposite direction. In spatially gradient temperature fields the polymer can be simultaneously in solid and liquid States. The generalized model of visco-elastic-plastic body is put in accordance with the presented three relaxation States of the polymer. The equations of motion of the material of wood is built on the basis of phenomenological concepts of continuum mechanics, the circuit equations is made on the basis of when the stress tensor with the strain tensor in accordance with the selected rheological model for wood material, like a polymer. The equations are constructed for a homogeneous continuous medium, in the transition to inhomogeneous scalar relaxation parameters of the polymer state must be represented in tensor form. This study can be considered as an element of the foundations of biopolymer mechanics.

The abradable coatings had significantly enhanced turbomachinery performance by acting as a sacrificial seal between rotating blades and stationary casing. Further improvement in seal design to meet the higher energy demand and increase the service time has been the key challenges to solve in the gas turbine industry. Honeycomb seals have become the industry standard clearance seal technique due to their unique design and high structural strength with minimum weight. The present study proposes a concept to form a thermal shock resistance structure to achieve higher temperature capability and improve the reliability of abradable seal structures. A cavity layer of honeycomb seal structure made of SS 321 alloy was coated with advanced high-temperature ZrO2+7.5%Y2O3+4% polyester seal material using TriplexPro-210 plasma spray system. The integrity of a seal structure was assessed by a cross-sectional analysis and evaluation of the coating microstructure. Additionally; the microhardness test was performed to estimate coating fracture toughness; and Object-Oriented Finite Element analysis was used to assess its thermo-mechanical performance. The concept proposed in this study should be further validated to develop the most capable innovative technology for advanced gas turbine abradable seal structures.

No abstract