In combination with experimental research,numerical simulation is performed to investigate the influence law of the obstacles in a duct on the explosion flame of premixed coal gas and air. The numerical method uses up...In combination with experimental research,numerical simulation is performed to investigate the influence law of the obstacles in a duct on the explosion flame of premixed coal gas and air. The numerical method uses upwind WENO scheme and two-step chemical reaction model. The interaction mechanism is addressed between the compression wave from reflection on the right end of the duct and flame propagation. The reflected wave is found to result in the decrease of flame velocity. On this basis,we analyze the mechanism of the obstacles on flame as well as the law of flow field variation thus caused. The results suggest that,due to the obstacles,deflagration wave is repeatedly reflected,combustible gas mixture is fully compressed,temperature and pressure rise,chemical reaction speed increases,and hence flame intensity is strengthened. At the same time,a tripe point forms as a result of wall reflection of the deflagration wave from the obstacles and furthermore local flame speed increases. As the triple point propagates forward,the flame speed gradually decreases due to dissipation of energy. These conclusions provide a valuable theoretical foundation for the prediction of explosion field,prevention of fire and explosion and effective control of the com-bustion speed and flame propagation speed in detonation propulsion.展开更多
Multi-component seismic exploration technology, combining reflected PP- and converted PS-waves, is an effective tool for solving complicated oil and gas exploration problems. The improvement of converted wave resoluti...Multi-component seismic exploration technology, combining reflected PP- and converted PS-waves, is an effective tool for solving complicated oil and gas exploration problems. The improvement of converted wave resolution is one of the key problems. The main factor affecting converted wave resolution is the absorption of seismic waves in overlying strata. In order to remove the effect of absorption on converted waves, inverse Q filtering is used to improve the resolution. In this paper, we present a method to estimate the S-wave Q values from prestack converted wave gathers. Furthermore, we extend a stable and effective poststack inverse Q filtering method to prestack data which uses wave field continuation along the ray path to compensate for attenuation in prestack common shot PP- and PS-waves. The results of theoretical modeling prove that the method of estimating the S-wave Q values has high precision. The results from synthetic and real data prove that the stable inverse Q filtering method can effectively improve the resolution of prestack PP- and PS-waves.展开更多
基金supported by the New Century Excellent Talents of Ministry of Education (Grant No. NCET-08-0043)the National Natural Science Foundation of China (Grant No. 10625208)the Foundation of State Key Laboratory of Explosion Science and Technology (Grant No. YBKT09-06)
文摘In combination with experimental research,numerical simulation is performed to investigate the influence law of the obstacles in a duct on the explosion flame of premixed coal gas and air. The numerical method uses upwind WENO scheme and two-step chemical reaction model. The interaction mechanism is addressed between the compression wave from reflection on the right end of the duct and flame propagation. The reflected wave is found to result in the decrease of flame velocity. On this basis,we analyze the mechanism of the obstacles on flame as well as the law of flow field variation thus caused. The results suggest that,due to the obstacles,deflagration wave is repeatedly reflected,combustible gas mixture is fully compressed,temperature and pressure rise,chemical reaction speed increases,and hence flame intensity is strengthened. At the same time,a tripe point forms as a result of wall reflection of the deflagration wave from the obstacles and furthermore local flame speed increases. As the triple point propagates forward,the flame speed gradually decreases due to dissipation of energy. These conclusions provide a valuable theoretical foundation for the prediction of explosion field,prevention of fire and explosion and effective control of the com-bustion speed and flame propagation speed in detonation propulsion.
基金supported by the 863 Program(Grant No.2007AA06Z218)
文摘Multi-component seismic exploration technology, combining reflected PP- and converted PS-waves, is an effective tool for solving complicated oil and gas exploration problems. The improvement of converted wave resolution is one of the key problems. The main factor affecting converted wave resolution is the absorption of seismic waves in overlying strata. In order to remove the effect of absorption on converted waves, inverse Q filtering is used to improve the resolution. In this paper, we present a method to estimate the S-wave Q values from prestack converted wave gathers. Furthermore, we extend a stable and effective poststack inverse Q filtering method to prestack data which uses wave field continuation along the ray path to compensate for attenuation in prestack common shot PP- and PS-waves. The results of theoretical modeling prove that the method of estimating the S-wave Q values has high precision. The results from synthetic and real data prove that the stable inverse Q filtering method can effectively improve the resolution of prestack PP- and PS-waves.
