Passive control and sensitivity analysis of thermo-acoustic systems via adjoint equations
Duration: 25 mins 37 secs
Share this media item:
Embed this media item:
Embed this media item:
About this item
| Description: | This presentation describes the application of adjoint-based sensitivity analysis to a thermo-acoustic system. In a single calculation, this analysis shows how a passive feedback device will affect the frequency and growth rate of thermo-acoustic oscillations. This type of analysis opens up new possibilities for the passive control of combustion instability, which is one of the most persistent problems facing gas turbine and rocket engine manufacturers. |
|---|
| Created: | 2013-01-04 12:40 | ||||
|---|---|---|---|---|---|
| Collection: | Matthew Juniper conference presentations | ||||
| Publisher: | University of Cambridge | ||||
| Copyright: | Dr Matthew Juniper | ||||
| Language: | eng (English) | ||||
| Keywords: | combustion; instability; thermoacoustic; adjoint; global mode; hydrodynamic; passive control; sensitivity analysis; | ||||
| Credits: |
|
||||
| Abstract: | We apply adjoint-based sensitivity analysis to a time-delayed thermo-acoustic system: a Rijke tube containing a hot wire. We calculate how the growth rate and frequency of small oscillations about a base state are affected by a generic passive control element in the system (the structural sensitivity analysis). We illustrate the structural sensitivity by calculating the effect of a second hot wire with a small heat release parameter. In a single calculation, this shows how the second hot wire changes the growth rate and frequency of the small oscillations, as a function of its position in the tube. We then examine the components of the structural sensitivity in order to determine the passive control mechanism that has the strongest influence on the growth rate. We find that a force applied to the acoustic momentum equation in the opposite direction to the instantaneous velocity is the most stabilizing feedback mechanism. We also find that its effect is maximized when it is placed at the downstream end of the tube. This feedback mechanism could be supplied, for example, by an adiabatic mesh. The successful application of sensitivity analysis to thermo-acoustics opens up new possibilities for the passive control of thermo-acoustic oscillations by providing gradient information that can be combined with constrained optimization algorithms in order to reduce linear growth rates. |
|---|---|
Available Formats
| Format | Quality | Bitrate | Size | |||
|---|---|---|---|---|---|---|
| MPEG-4 Video | 480x360 | 401.37 kbits/sec | 75.31 MB | View | Download | |
| WebM | 480x360 | 155.12 kbits/sec | 29.12 MB | View | Download | |
| iPod Video | 480x360 | 407.67 kbits/sec | 76.49 MB | View | Download | |
| QuickTime | 384x288 | 135.7 kbits/sec | 25.46 MB | View | Download | |
| MP3 | 44100 Hz | 249.86 kbits/sec | 46.91 MB | Listen | Download | |
| Auto * | (Allows browser to choose a format it supports) | |||||