THERMOACOUSTICS
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THERMOACOUSTICS. Optimisation of the Feedback Loop of the Thermoacoustic Travelling wave Engine. David Wee Shuon Tzern Yousif Abdalla Abakr David Hann Paul Riley. The Simplest form of a Travelling Wave Thermoacoustic Engine. Regenerator. Linear Alternator. Tuning Stub. Feed Back Loop.

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THERMOACOUSTICS

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Thermoacoustics

THERMOACOUSTICS

Optimisation of the Feedback Loop of the Thermoacoustic Travelling wave Engine

David Wee Shuon Tzern

Yousif Abdalla Abakr

David Hann

Paul Riley


Thermoacoustics

The Simplest form of a Travelling Wave Thermoacoustic Engine

Regenerator

Linear Alternator

Tuning Stub

Feed Back Loop

Limiting amplitude occurs when the amplification of the regenerator is equivalent to the power absorbed by the system

Total Power Absorbed = Power absorbed by Linear Alternator + System Losses


Thermoacoustics

SCORE -StoveTM

Thermoacoustic Engine

REQUIREMENT

Efficiency

Compact

INFLUENCING PARAMETER

Elbow Bends

An understanding of the Acoustic Transmission through bends is required in order to optimise the system


Thermoacoustics

MICROPHONE

Decomposition Method

Decomposition Transfer Function

Scattering Matrix Technique


Thermoacoustics

MICROPHONE Experimental Setup

Optimum Travelling wave Load


Thermoacoustics

MICROPHONE Experimental Setup

Investigated Bends


Thermoacoustics

Reynolds Number vs. Transmission Loss [%]

Legend

r = hydraulic radius (m)

R = radius of curvature

of elbow(m)

u = RMS particle velocity (ms-1)

c = speed of sound (ms-1)

ω = angular frequency (s-1)

ρ = density (kg/m3)

ν = kinematic viscousity (m2s-1)

Legend

r = hydraulic cross sectional

radius (m)

R = Radius of curvature

of elbow(m)

u = RMS particle velocity (ms-1)

c = Speed of sound (ms-1)

ω = angular frequency (s-1)

ν = kinematic viscousity (m2s-1)


Thermoacoustics

Dean Number vs. Transmission Power Loss [%]

Linear Loss Region

Non-Linear Loss Region


Thermoacoustics

PIV Experimental Setup

PIV=Particle Image Velocimetry


Thermoacoustics

PIV Experimental Setup


Thermoacoustics

PIV Experimental Setup


Thermoacoustics

Dean Number vs. Transmission Power Loss [%]

Linear Loss Region

Non-Linear Loss Region


Thermoacoustics

Dean Number vs. Transmission Power Loss [%]

Linear Loss Region

Non-Linear Loss Region

At Higher operating Amplitude such as that of the Engine, Losses may go up to 10% or more


Thermoacoustics

CONCLUSIONS

  • A monotonic relationship has been found between the Percentage Acoustic Transmission Loss and the Acoustic Dean Number. A critical Dean Number (≈1) above which the transmission losses increase significantly has been identified.

  • Particle Image Velocimetry is being used to investigate the transition to nonlinearity by consideration of the flow field.

  • Once verified this would prove an important breakthrough in the design of future feedback resonator loop for thermoacoustic systems by providing new information about

  • the additional losses at the elbow bends.


Thermoacoustics

THANK YOU


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