The buoyancy effect on micro hydrogen jet flames in still air was numerially studied.The results show that when the jet velocity is relatively large(V≥0.2 m/s),the flame height,width and temperature decrease,whereas ...The buoyancy effect on micro hydrogen jet flames in still air was numerially studied.The results show that when the jet velocity is relatively large(V≥0.2 m/s),the flame height,width and temperature decrease,whereas the peak OH mass fraction increases significantly under normal gravity(g=9.8 m/s^2).For a very low jet velocity(e.g.,V=0.1 m/s),both the peak OH mass fraction and flame temperature under g=9.8 m/s^2 are lower than the counterparts under g=0 m/s^2.Analysis reveals that when V≥0.2 m/s,fuel/air mixing will be promoted and combustion will be intensified due to radial flow caused by the buoyancy effect.However,the flame temperature will be slightly decreased owing to the large amount of entrainment of cold air into the reaction zone.For V=0.1 m/s,since the heat release rate is very low,the entrainment of cold air and fuel leakage from the rim of tube exit lead to a significant drop of flame temperature.Meanwhile,the heat loss rate from fuel to inner tube wall is larger under g=9.8 m/s^2 compared to that under g=0 m/s^2.Therefore,the buoyancy effect is overall negative at very low jet velocities.展开更多
Thermal-analysis technique has proved highly effective not only in the qualitative identification of various carbonate minerals in carbonate rocks, but also in the quantitiative determination of them. Both qualitative...Thermal-analysis technique has proved highly effective not only in the qualitative identification of various carbonate minerals in carbonate rocks, but also in the quantitiative determination of them. Both qualitative identification and quantitative determination of carbonate minerals in carbonate rocks can be made based upon the DTA curves produced by various carbonate minerals during their decomposition at different temperatures, and the weight loss of CO2 escaped .from carbonate minerals respectively By comparing the results from artificially prepared sampling tests and the quantitative thermal analysis on Liaoning Sinian carbonate rocks with those from chemical calculation,we can see that the error is as small as below 2.50%. And thus, this technique is considered as one valid method with the advantages of simplibility in performance and reliability in the qualitative identification and quantitative determination of corbonate minerals in carbonate rocks.展开更多
基金Project(51576084)supported by the National Natural Science Foundation of China。
文摘The buoyancy effect on micro hydrogen jet flames in still air was numerially studied.The results show that when the jet velocity is relatively large(V≥0.2 m/s),the flame height,width and temperature decrease,whereas the peak OH mass fraction increases significantly under normal gravity(g=9.8 m/s^2).For a very low jet velocity(e.g.,V=0.1 m/s),both the peak OH mass fraction and flame temperature under g=9.8 m/s^2 are lower than the counterparts under g=0 m/s^2.Analysis reveals that when V≥0.2 m/s,fuel/air mixing will be promoted and combustion will be intensified due to radial flow caused by the buoyancy effect.However,the flame temperature will be slightly decreased owing to the large amount of entrainment of cold air into the reaction zone.For V=0.1 m/s,since the heat release rate is very low,the entrainment of cold air and fuel leakage from the rim of tube exit lead to a significant drop of flame temperature.Meanwhile,the heat loss rate from fuel to inner tube wall is larger under g=9.8 m/s^2 compared to that under g=0 m/s^2.Therefore,the buoyancy effect is overall negative at very low jet velocities.
文摘Thermal-analysis technique has proved highly effective not only in the qualitative identification of various carbonate minerals in carbonate rocks, but also in the quantitiative determination of them. Both qualitative identification and quantitative determination of carbonate minerals in carbonate rocks can be made based upon the DTA curves produced by various carbonate minerals during their decomposition at different temperatures, and the weight loss of CO2 escaped .from carbonate minerals respectively By comparing the results from artificially prepared sampling tests and the quantitative thermal analysis on Liaoning Sinian carbonate rocks with those from chemical calculation,we can see that the error is as small as below 2.50%. And thus, this technique is considered as one valid method with the advantages of simplibility in performance and reliability in the qualitative identification and quantitative determination of corbonate minerals in carbonate rocks.
