Effect of CH4–Air Ratios on Gas Explosion Flame Microstructure and Propagation Behaviors
Abstract
:1. Introduction
2. Results and Discussion
2.1. Flame Structure Characteristic Based on High Speed Schlieren Photographs
equivalence ratio | volume concentration | (cm/s) | δ (cm) | ρu/ρb | Ma |
---|---|---|---|---|---|
0.80 | 7.6% | 25.4 | 0.009 | 6.65 | 4.69 |
0.90 | 8.6% | 32.5 | 0.225 | 7.12 | 5.54 |
1.00 | 9.5% | 37.1 | 0.217 | 7.48 | 6.20 |
1.10 | 10.5% | 38.3 | 0.225 | 7.55 | 6.99 |
1.20 | 11.4% | 34.5 | 0.215 | 7.43 | 7.96 |
1.30 | 12.4% | 25.0 | 0.291 | 7.28 | 9.13 |
2.2. Flame Propagation Behavior on Different Equivalence Ratios
2.3. The Flame-Propagation Dynamics Characteristic on Different Flow Structure
3. Experimental Section
3.1. Experimental Apparatus
3.2. Experimental Procedure
- Methane volume concentration: 6%–14%;
- Ignition voltage: 30,000 V;
- Ignition time: 0.01 s;
- High speed camera meter frequency: 10,000 shooting frame/s;
- Data sampling frequency: 100 kHz.
4. Conclusions
- (1)
- The flame front structure transition was closely connected to the flame acceleration propagation process and flow character. The flame structure change was mainly due to the flow transition from laminar to turbulent.
- (2)
- The explosion flame was divided into laminar and turbulent stages. At different flame stages, the factors influencing flame propagation were different. The laminar flame propagation behavior was influenced mainly by gas inflation and pressure wave effects, while the turbulent flame speed was greatly dependent on turbulence intensity.
- (3)
- The turbulence intensity played an important role in peak value of explosive pressure and flame speed. On the case that it’s easier to form laminar-turbulent transition, the ideal explosive concentration would be easier to reach, which was the essential reason why the ideal explosive concentration differs under different test conditions.
Acknowledgments
References
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Chen, X.; Zhang, Y.; Zhang, Y. Effect of CH4–Air Ratios on Gas Explosion Flame Microstructure and Propagation Behaviors. Energies 2012, 5, 4132-4146. https://doi.org/10.3390/en5104132
Chen X, Zhang Y, Zhang Y. Effect of CH4–Air Ratios on Gas Explosion Flame Microstructure and Propagation Behaviors. Energies. 2012; 5(10):4132-4146. https://doi.org/10.3390/en5104132
Chicago/Turabian StyleChen, Xianfeng, Yin Zhang, and Ying Zhang. 2012. "Effect of CH4–Air Ratios on Gas Explosion Flame Microstructure and Propagation Behaviors" Energies 5, no. 10: 4132-4146. https://doi.org/10.3390/en5104132