![Sample our Engineering & Technology journals, sign in here to start your access, latest two full volumes FREE to you for 14 days]({"type":"image" , "src" : "/sda/5933/TOC-Subject-Sample-2021-Engineering-Tech.jpg"})
ABSTRACT
This study investigated the effectiveness of implementing a plasma discharge to improve combustor dynamics and flame stability. Specifically, a nano-second pulsed plasma discharge (NSPD) was applied to a premixed gaseous fuel/air dump combustor for mitigation of dynamic combustion instabilities with a minimal NOX penalty. As a result, a significant reduction of pressure fluctuation level (2X to 4X) was observed at realistic low-power conditions of aero-engine combustors. The plasma power required for the reduction increased with increasing combustor inlet velocity and pressure. The change of fuel from methane to propane required significantly (2X) higher plasma power to achieve a similar noise reduction. The lean blowout limit was significantly extended due to the plasma; however, substantial incomplete combustion occurred in the extended regime. The incremental NOX production in the presence of the plasma was low (~ < 1EINOX); however, it increased with decreasing velocity and pressure, and increasing temperature.
Nomenclature
| [NO] | = | Molecular concentration of nitric oxide |
| 6 dB | = | Noise reduction: 50% noise reduction |
| CO | = | Carbon monoxide |
| CZ | = | Center zone of dump combustor |
| E | = | Electric field |
| E/n | = | Reduced electric field |
| EINOX | = | Emission Index NOX, g (NOX)/kg (fuel) |
| EMI | = | Electro-magnetic interference |
| LBO | = | Lean blowout |
| N2* | = | Excited electronic/vibrational states of molecular nitrogen |
| NOX | = | Oxides of nitrogen |
| NSPD | = | Nano-second pulsed plasma discharge |
| O | = | Order of magnitude |
| OH | = | Hydroxyl radical |
| ORZ | = | Outer recirculation zone of dump combustor |
| P | = | Pressure |
| P3 | = | Combustor inlet pressure |
| PLIF | = | Planar laser induced fluorescence |
| Relative Noise | = | Ratio of peak pressure fluctuation in the presence of NSPD to that in its absence |
| RR | = | Plasma repetition rate |
| RR6dB | = | Plasma repetition rate at 50% noise reduction |
| T | = | Temperature |
| T3 | = | Combustor inlet temperature |
| Texit_norm | = | Normalized and reduced combustor exit temperature |
| TLBO | = | Combustor exit temperature just before lean blowout |
| TNo_comb | = | Combustor exit temperature without combustion |
| TRL | = | Technology readiness level |
| V | = | Velocity |
| V3 | = | Combustor inlet bulk velocity |
| n | = | Number density of medium |
| p-p | = | Peak to peak |
| rms | = | Root mean squared |
| Φ | = | Equivalence ratio |
| ΦLBO | = | Lean blowout equivalence ratio |
| ΦNLBO | = | Near lean blowout equivalence ratio, ΦLBO + 0.01 |
| Φr | = | Reduced equivalence ratio |
| η | = | Combustion efficiency |
Acknowledgments
This work was supported by NASA under Grant No. NNX14AF53A with Dr. Koushik Datta as a technical officer. The PI would like to thank Drs. Jordan Snyder, Seung-Bum Kim, Lance Smith, Adam Holley, and Donald Hautman for their helpful comments. Also, we appreciate the efforts of Mr. John Costello and Mr. Jay Borst for the test and experiment setup.
Disclaimer
Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Aeronautics and Space Administration.