With the development of the offshore deep water oil industry many researchers are focusing on the vortex-induced vibrations （VIV） of deep risers. In the present work, Reynolds-averaged Navier-Stokes （RANS） equatio...With the development of the offshore deep water oil industry many researchers are focusing on the vortex-induced vibrations （VIV） of deep risers. In the present work, Reynolds-averaged Navier-Stokes （RANS） equations were combined with the SST κ-ω turbulent model to simulate the stream-wise and transverse motion of an elastically mounted cylinder with a low mass-ratio, a natural frequency ratio of fx/fy = 1 and an Re number between 5 300 and 32 000, The four-order Runge-Kutta method was applied to solve the oscillating equation of the cylinder. The relationship between reduced velocity and parameters of the cylinder, including the lift coefficient, the drag coefficient, displacement and the vortex structure were then compared with recent experimental results and discussed in detail. The present numerical simulation reproduced effects have been observed in experiments, such as the lock-in phenomenon, the hysteretic phenomenon and beating behavior.展开更多
The recovery of heavy oil by water flooding is 10% lower than that of conventional crude oil, so enhanced oil recovery （EOR） is of great significance for heavy oil. In this paper, foam flooding with a gas-liquid rat...The recovery of heavy oil by water flooding is 10% lower than that of conventional crude oil, so enhanced oil recovery （EOR） is of great significance for heavy oil. In this paper, foam flooding with a gas-liquid ratio （GLR） of 0.2：1 for the Zhuangxi heavy oil （325 mPa.s at 55 ℃） was performed on cores, sand packs and plate model. In sand pack tests, polymer enhanced foam flooding increased oil recovery by 39.8%, which was 11.4% higher than that for alkali/surfactant/polymer （ASP） flooding under the same conditions. Polymer enhanced foam flooding in plate models shows that the low GLR foam flooding increased oil recovery by about 30%, even when the extended water flooding was finished at 90% water cut. Moreover, it was discovered by microscopy that foam was more stable in heavy oil than in light oil. These results confirm that low GLR foam flooding is a promising technology for displacing conventional heavy oil.展开更多
In order to study component matching which exists in off-design situation at the initial design stage of turbine engine,by establishing performance analysis model of low bypass ratio mixed flow turbofan engine and com...In order to study component matching which exists in off-design situation at the initial design stage of turbine engine,by establishing performance analysis model of low bypass ratio mixed flow turbofan engine and components characteristic data,and by applying Newton-Raphson method to solve the nonlinear equations of offdesign points in flying envelop,the factors which affect matching between engine components are studied.The results show that low pressure turbine(LPT)must not operate in a critical condition,and the partial derivative(slope)of pressure ratio to similitude mass flow ratio of working point in LPT characteristic map affects the stability of engine.The smaller the slope is,the more stable the engine is.In addition,the engine is more stable when the fan characteristic map is steep.展开更多
针对烃类重整蒸汽制氢工艺转化气能量降级使用、原料气压缩功耗大的问题,提出了一种低碳烃膨胀透平集成制氢工艺。该工艺以炼油厂过剩低碳液态烃为原料,增压功耗较低,在转化炉出口设置膨胀透平,回收转化气的高温高压热能和压力能后再送...针对烃类重整蒸汽制氢工艺转化气能量降级使用、原料气压缩功耗大的问题,提出了一种低碳烃膨胀透平集成制氢工艺。该工艺以炼油厂过剩低碳液态烃为原料,增压功耗较低,在转化炉出口设置膨胀透平,回收转化气的高温高压热能和压力能后再送余热锅炉产汽,同时回收中变气余热以加热液相原料。使用Aspen Plus V11对新工艺进行了全流程模拟,探求其原料组成、反应压力、反应温度、蒸汽碳比对装置热效率、能耗和CO_(2)排放量的影响。基于模拟数据,采用非支配排序遗传算法NSGA-Ⅱ对新工艺进行了多变量多目标优化。计算表明,某液化石油气进料量为8.756 t/h的新工艺,最优操作工况下产氢2636.8 kg/h、发电8870.2 kW·h/h,生产1 t H_(2)综合能耗2892.9 kgoe、装置热效率71.63%、CO_(2)排放29984.6 kg/h,较优化前工况综合能耗降低、产氢量增加。展开更多
文摘With the development of the offshore deep water oil industry many researchers are focusing on the vortex-induced vibrations （VIV） of deep risers. In the present work, Reynolds-averaged Navier-Stokes （RANS） equations were combined with the SST κ-ω turbulent model to simulate the stream-wise and transverse motion of an elastically mounted cylinder with a low mass-ratio, a natural frequency ratio of fx/fy = 1 and an Re number between 5 300 and 32 000, The four-order Runge-Kutta method was applied to solve the oscillating equation of the cylinder. The relationship between reduced velocity and parameters of the cylinder, including the lift coefficient, the drag coefficient, displacement and the vortex structure were then compared with recent experimental results and discussed in detail. The present numerical simulation reproduced effects have been observed in experiments, such as the lock-in phenomenon, the hysteretic phenomenon and beating behavior.
基金support from the Innovation Team Program and New Century Excellent Talents Awards Program,the Ministry of Education of ChinaFok Ying Tung Education Foundation
文摘The recovery of heavy oil by water flooding is 10% lower than that of conventional crude oil, so enhanced oil recovery （EOR） is of great significance for heavy oil. In this paper, foam flooding with a gas-liquid ratio （GLR） of 0.2：1 for the Zhuangxi heavy oil （325 mPa.s at 55 ℃） was performed on cores, sand packs and plate model. In sand pack tests, polymer enhanced foam flooding increased oil recovery by 39.8%, which was 11.4% higher than that for alkali/surfactant/polymer （ASP） flooding under the same conditions. Polymer enhanced foam flooding in plate models shows that the low GLR foam flooding increased oil recovery by about 30%, even when the extended water flooding was finished at 90% water cut. Moreover, it was discovered by microscopy that foam was more stable in heavy oil than in light oil. These results confirm that low GLR foam flooding is a promising technology for displacing conventional heavy oil.
基金supported in part by the Fundamental Research Funds for the Central Universities(No.NZ2016103)
文摘In order to study component matching which exists in off-design situation at the initial design stage of turbine engine,by establishing performance analysis model of low bypass ratio mixed flow turbofan engine and components characteristic data,and by applying Newton-Raphson method to solve the nonlinear equations of offdesign points in flying envelop,the factors which affect matching between engine components are studied.The results show that low pressure turbine(LPT)must not operate in a critical condition,and the partial derivative(slope)of pressure ratio to similitude mass flow ratio of working point in LPT characteristic map affects the stability of engine.The smaller the slope is,the more stable the engine is.In addition,the engine is more stable when the fan characteristic map is steep.
文摘针对烃类重整蒸汽制氢工艺转化气能量降级使用、原料气压缩功耗大的问题,提出了一种低碳烃膨胀透平集成制氢工艺。该工艺以炼油厂过剩低碳液态烃为原料,增压功耗较低,在转化炉出口设置膨胀透平,回收转化气的高温高压热能和压力能后再送余热锅炉产汽,同时回收中变气余热以加热液相原料。使用Aspen Plus V11对新工艺进行了全流程模拟,探求其原料组成、反应压力、反应温度、蒸汽碳比对装置热效率、能耗和CO_(2)排放量的影响。基于模拟数据,采用非支配排序遗传算法NSGA-Ⅱ对新工艺进行了多变量多目标优化。计算表明,某液化石油气进料量为8.756 t/h的新工艺,最优操作工况下产氢2636.8 kg/h、发电8870.2 kW·h/h,生产1 t H_(2)综合能耗2892.9 kgoe、装置热效率71.63%、CO_(2)排放29984.6 kg/h,较优化前工况综合能耗降低、产氢量增加。
