Course detail
Dynamics IV - Selected Chapters
FSI-RRS Acad. year: 2022/2023 Winter semester
In the course the students will be acquainted with the basic dynamic properties and dynamic behavior of the components and parts of rotor systems. Specifically, with the shaft, non-linear constraints between the rotating and non-rotating parts, turbine and compressor blades and disks. Special attention is paid to the rotor eigen frequencies, mode shapes and critical speed prediction. Some tasks can be computationally demanding, especially in the time domain solutions. Therefore, the students will be introduced to methods of reducing degrees of freedom. The course will also pay attention to vibrations and noise, which are accompanying phenomena of working processes of all machinery. The course is focused on the basics of acoustics, measurement of acoustic quantities and computational modeling of vibroacoustic systems. In the exercises students will be introduced to the solution of vibroacoustic problems using numerical methods. In addition, students will be introduced to optimization methods.
Language of instruction
Czech
Number of ECTS credits
7
Supervisor
Learning outcomes of the course unit
Students will acquire basic theoretical knowledge in the field of rotor systems, degrees of freedom reduction, optimization and acoustics. They will learn about computational modeling of the rotors. They will learn to predict the resonant states and critical speeds of rotating machines and learn how to suppress them. Students will be able to reduce systems with many degrees of freedom, thus reducing computational time. Graduates will be able to analyze machine noise, identify sources of vibration and noise and implement active and passive methods of vibration and noise reduction. Students will acquire basic knowledge of optimization.
Prerequisites
Students must be able to solve the eigen value problem, solve the response in forced, steady and transient oscillations of systems with n degrees of freedom. Furthermore, the students must to have knowledge of the basics of nonlinear vibrations, and knowledge of the basics of experimental modal analysis. The student must know fundamentals of acoustics, matrix calculus, linear algebra, differential equations, fundamentals of the finite element method.
Planned learning activities and teaching methods
The course is taught through lectures explaining the basic principles and theory of the discipline. Exercises are focused on practical topics presented in lectures.
Assesment methods and criteria linked to learning outcomes
Active participation in seminars, obtaining at least 20 points of 40 possible, which can be obtained by elaborating partial tasks and their presentations and passing two seminar tests of the basic knowledge and solution of typical tasks from profiling areas of the subject (at least 30 points out of 60 must be gained). The specific form of the tests, types, number of tasks or questions and details of the assessment will be given by the lecturer during the semester. The final evaluation is given by the sum of the point according ECTS. For successful completion of the course it is necessary to obtain at least 50 points.
Aims
The students obtain the overview of the with selected parts of dynamics. It is the dynamics of rotors, methods of reduction and methods of optimization The aim of the course is also practical and theoretical analysis of machine noise, computational modeling of their components in order to reduce their vibrations and radiated acoustic energy.
Specification of controlled education, way of implementation and compensation for absences
Attendance at practical training is obligatory. Longer absence is compensated for by special tasks according to instructions of the tutor. Seminar credits are awarded on the condition of: active presence in the seminars, good results of seminar tests on basic knowledge, solution of additional tasks in case of longer excusable absence. Seminar tutor will specify the concrete form of these conditions in the first week of semester.
The study programmes with the given course
Programme N-IMB-P: Engineering Mechanics and Biomechanics, Master's
specialization IME: Engineering Mechanics, compulsory
Type of course unit
Lecture
26 hours, optionally
Teacher / Lecturer
Syllabus
1. Introduction to rotor systems, basic models of rotors
2. Undamped Laval (Jeffcott) rotor in rigid and flexible bearing supports
3. Laval (Jeffcott) rotor with external and internal damping. Roro stability
4. Joints between rotating and non-rotating parts (bearings, shock absorbers, sealing joints).
5. Vibration of bladed disks, Campbell diagram
6. Vibration of the non-attenuated rotor taking into account gyroscopic effects,
7. Rotor balancing
8. Methods of reduction of dynamic systems
9. Acoustic quantities, wave equation and its solution, mechanical and aerodynamic noise sources
10. Measurement of acoustic quantities
11. Deterministic models of vibroacoustic systems: finite element method (FEM), boundary element method (BEM)
12. Statistical models of vibroacoustic systems (statistical energy analysis SEA), hybrid models (FEM + SEA)
13. Optimization
Computer-assisted exercise
13 hours, compulsory
Teacher / Lecturer
Syllabus
1. Calculation of critical speeds using simple rotor models
2. Simulation of starting of electric motors in time domain
3. Simulation of electric motor start in frequency domain
4. Simulation of rotor bearing behavior
5. Vibration of disks and bladed disks
6. Modeling of bladed disks using cyclic symmetry
7. Effect of nonlinearities in bladed discs dynamic behavior
8. Degrees of freedom reduction: Examples in MATLAB, MSC Adams and ANSYS
9. Propagation of acoustic waves in free and enclosed space
10. Radiation of acoustic waves from vibrating body to free space, radiated acoustic power
11. Propagation of acoustic waves from a vibrating body into a acoustic cavity
12. Transmission of acoustic waves across different types of walls
13. Application of selected optimization methods