Banca de QUALIFICAÇÃO: DIEGO ZILLI LIMA

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
DISCENTE : DIEGO ZILLI LIMA
DATA : 20/05/2022
HORA: 14:00
LOCAL: Videoconferência
TÍTULO:

Modal Analysis and Optimization of Integrated Bladed Disks with Applications to Centrifugal Compressors for Supercritical CO2

PÁGINAS: 90
GRANDE ÁREA: Engenharias
ÁREA: Engenharia Mecânica
SUBÁREA: Mecânica dos Sólidos
ESPECIALIDADE: Mecânica dos Corpos Sólidos, Elásticos e Plásticos
RESUMO:

The emission of carbon dioxide (CO2) is the main cause of the greenhouse effect. Thus, in addition to the direct reduction using new forms of energy, it is necessary to advance towards Carbon Capture, Storage and Utilization (CCSU) technologies. Both in transport and in employment in power cycles, the use of CO2 in supercritical state provides compact and efficient turbomachines. However, their properties have a highly nonlinear behavior near the critical point, making the design a challenging task. In relation to structural behavior, most of the failures of turbomachinery are directly related to fatigue, that has as principal cause the dynamical instability generated by vibrations. Then, with the aim of reducing the risk of failure, a methodology to identify possible resonance in the design phase was developed. The method adopted considered detailed prestressed modal analyses with the employment of the stress stiffening, spin softening and the gyroscopic effects, in parallel with Campbell diagram, Kushner’s equations and SAFE diagram. All the analysis procedure stablished was inserted in a structural design optimization process, that was realized with surrogate models to reduce the search time of the optimal geometry. The Kriging technique of response surface was used to obtain the metamodel. Single and multidisciplinary strategies were realized. In both, the resonance free condition was employed as objective and, in the multidisciplinary approach, were added structural constraints. Comparisons of different objective functions were made too. The results showed that it was possible to conduct detail prestressed modal analyses, with all the rotational effects and graphic tools to resonance identification in a single optimization loop. The validation cases also demonstrated that the computational tools were capable to represent the principal effects acting in rotating bladed disks. The use of structural constraints made the optimization more robust, obtaining geometries that reached the objective of mitigation of the resonance and reduced the mass and stress levels. Thus, consolidating the methodology to be employed in future works, like real structural project of centrifugal compressors operating with CO2 in supercritical state.

MEMBROS DA BANCA:
Presidente - Interno ao Programa - 3042266 - WALLACE GUSMAO FERREIRA
Membro Titular - Examinador(a) Interno ao Programa - 2312727 - DANIEL JONAS DEZAN
Membro Titular - Examinador(a) Interno ao Programa - 1604134 - CICERO RIBEIRO DE LIMA
Membro Suplente - Examinador(a) Interno ao Programa - 1850088 - REYOLANDO MANOEL LOPES REBELLO DA FONSECA BRASIL
Membro Suplente - Examinador(a) Externo ao Programa - 2336809 - CESAR MONZU FREIRE