Course detail

Dynamics IV - Selected Chapters

FSI-RRSAcad. year: 2021/2022

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

Mode of study

Not applicable.

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.

Co-requisites

Not applicable.

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

Conditions for obtaining the course-unit credit: Active participation in seminars, obtaining at least 20 points of 40 possible, which can be obtained by elaborating partial tasks and their presentations. The point gain from the exercises is a part of the final classification of the subject. Exam: The exam is divided into two parts. The test classification is based on the classification of both parts. If one of the parts is graded with grade F, the final grade is F. The second part is a written solution of typical tasks from profiling areas of the subject. Up to 30 points can be obtained from this section. The specific form of the exam, types, number of examples 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 gain from the exercises and by the ECTS exam. For successful completion of the course it is necessary to obtain at least 50 points.

Course curriculum

Not applicable.

Work placements

Not applicable.

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.

Recommended optional programme components

Not applicable.

Prerequisites and corequisites

Not applicable.

Basic literature

Erwin Kramer: Dynamics of Rotors and Foundations , Springer Verlag, 1993.
Gasch, Pfutzner: Dynamika rotorů, SNTL Praha, 1980.

Recommended reading

Beer, G., Smith, I., Duenser, Ch.: The Boundary Element Method with Proramming, Springer-Verlag, 2008
Lyon, R. H., DeJong, R.G: Theory and Application of Statistical Energy Analysis, Butterwortth-Heinemann, Boston, 1995
Mišun, V.: Vibrace a hluk, Vysoké učení technické , Brno, 1998
Ohayon, R., Soize, C.: Structural Acoustic and Vibration, Academic Press, London, 1998

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Classification of course in study plans

  • Programme N-IMB-P Master's

    specialization IME , 2 year of study, winter semester, compulsory

Type of course unit

 

Lecture

26 hod., 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 hod., 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

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