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Acoustic Instabilities in Aerospace Propulsion

Acoustic Instabilities in Aerospace Propulsion. Instructor: Prof. R. I. Sujith, Department of Aerospace Engineering, IIT Madras. Introduction to acoustics and combustion driven oscillations. Derivation of the wave equation. Traveling wave solutions. Acoustic energy corollary. Impedance and admittance. Standing wave solutions. Reflection and transmission. Impedance tube technique. Effect of area and temperature variation on wave propagation. Wave equation in cylindrical coordinates and its applications. Basic principles of combustion driven oscillations. Rayleigh criteria. Mechanisms for instability in solid and liquid rockets, ramjets, gas turbines. Pulse combustors and their analysis using Galerkin technique. Modal analysis. Nonmodal stability analysis. Passive and active control of combustion instability. (from nptel.ac.in)

Lecture 08 - Impedance Tube Technique

Impedance tube, standing wave structure, amplitude and phase distributions, reflection coefficient.

Go to the Course Home or watch other lectures:

Lecture 01 - Introduction to Thermoacoustic Instabilities

Lecture 02 - Introduction to Acoustics, Conservation Equations

Lecture 03 - Wave Equation and its Solution in Time Domain

Lecture 04 - Harmonic Waves, Acoustic Energy Corollary

Lecture 05 - Standing Waves

Lecture 06 - Standing Waves 2

Lecture 07 - Power Flow and Acoustic Admittance

Lecture 08 - Impedance Tube Technique

Lecture 09 - Admittance and Standing Waves

Lecture 10 - Admittance, Stability and Attenuation

Lecture 11 - Attenuation: Continued Sound Propagation through Inhomogeneous Media 1

Lecture 12 - Sound Propagation through Inhomogeneous Media 2

Lecture 13 - Sound Propagation through Inhomogeneous Media 3

Lecture 14 - Multidimensional Acoustic Fields 1

Lecture 15 - Multidimensional Acoustic Fields 2

Lecture 16 - Interaction between Sound and Combustion

Lecture 17 - Reference Books, Derivation of Rayleigh Criteria

Lecture 18 - Effect of Heat Release on the Acoustic Field

Lecture 19 - Modal Analysis of Thermoacoustic Instability 1

Lecture 20 - Modal Analysis of Thermoacoustic Instability 2

Lecture 21 - Active Control of Thermoacoustic Instability

Lecture 22 - Toy Model for a Rijke Tube in Time Domain

Lecture 23 - Galerkin Technique for Thermoacoustics

Lecture 24 - Evolution Equation for Thermoacoustics

Lecture 25 - Nonlinear Analysis for Thermoacoustic Instability

Lecture 26 - Nonnormality, Transient Growth and Triggering Instability 1

Lecture 27 - Nonnormality, Transient Growth and Triggering Instability 2

Lecture 28 - Nonnormality, Transient Growth and Triggering Instability 3

Lecture 29 - Bifurcations

Lecture 30 - Premixed Flame Acoustic Interaction 1

Lecture 31 - Premixed Flame Acoustic Interaction 2

Lecture 32 - Combustion Instability due to Equivalence Ratio Fluctuation

Lecture 33 - Role of Hydrodynamic Instabilities 1

Lecture 34 - Role of Hydrodynamic Instabilities 2

Lecture 35 - Role of Hydrodynamic Instabilities 3

Lecture 36 - Active Control of Thermoacoustic Instability Revisited

Lecture 37 - Solid Propellant Combustion Instability 1

Lecture 38 - Solid Propellant Combustion Instability 2

Lecture 39 - Response of a Diffusion Flame to Acoustic Oscillations 1

Lecture 40 - Response of a Diffusion Flame to Acoustic Oscillations 2

Lecture 41 - Response of a Diffusion Flame to Acoustic Oscillations 3