建立了一种新的管状模型来模拟普通黑烟囱体的热液循环系统，分别用达西方程、湍流方程、Ergun方程和“浮压力差”方程来描述热液循环不同关键环节处的动力学系统，用一个温度场的对流一扩散方程来描述反应区的热能交换及系统的温度变...建立了一种新的管状模型来模拟普通黑烟囱体的热液循环系统，分别用达西方程、湍流方程、Ergun方程和“浮压力差”方程来描述热液循环不同关键环节处的动力学系统，用一个温度场的对流一扩散方程来描述反应区的热能交换及系统的温度变化规律．在联立几个方程并用有效的数值算法及Matlab语言编程求解后，得出了系统中温度、压力及物质流速随时间的变化曲线，并对黑烟囱体内部的动态热平衡和压力平衡进行了分析．在普通黑烟囱体系统模型的基础上进一步建立了巨型羽状流（巨羽流）生成的数学模型．选择胡安·德富卡（Juan de Fuca）洋脊热液喷口对巨羽流的形成进行了模拟，其结果与Baker根据实测数据估算的近似值吻合很好．在上述模型的基础上进一步探讨了巨羽状流形成的一系列条件及主要参数对巨羽流生成周期、温度和最大物质流速等的影响．主要结论如下：巨羽流系统可以由普通黑烟囱系统发展演化而成，其实际过程是普通黑烟囱流系统活动所形成的热液沉积在一定程度上会堵塞热液喷溢通道（相当于形成盖层），造成热液在海底之下积蓄和升温，从而导致浮压力差增大，经过2～3a（浮压力差达到盖层破裂极限值）则可形成巨羽流系统，巨羽流产生时的热源温度必须超过500℃，喷出热液的最高温度为413℃左右（与实际观测到的海底热液的最高温度一致）．当反应区热源温度增大时，产生巨羽流的临界时间明显变短（可能不到1a），而临界温度（巨羽流生成时的温度）及巨羽流的最大物质流速几乎不随其变化；随着渗透率的增大，巨羽流的最大物质流速也随之增大，但其增速随渗透率的进一步增大而变缓，并逐渐趋向一个相当于下渗流无摩擦阻力时的极限稳定值．展开更多
A method of combining the valve system program with the engine cycle modeling software to form a full set of working process modeling is submitted,not only considering the system as an independent part,but also as a p...A method of combining the valve system program with the engine cycle modeling software to form a full set of working process modeling is submitted,not only considering the system as an independent part,but also as a part of working process to evaluate comprehensively and indicate directly if the design is good or not.The designers can optimize the design by changing the engine structure,operation and the basic parameters of the cam on condition that the sysem should be stable so as to save large amounts of time and cost.Practical examples show that such a software package is an effective tool in optimizing the valve systems and performance of the machine.展开更多
A bottoming cycle system based on CO2 Brayton cycle is proposed to recover the engine exhaust heat. Its performance is compared with the conventional air Brayton cycle under five typical engine conditions. The results...A bottoming cycle system based on CO2 Brayton cycle is proposed to recover the engine exhaust heat. Its performance is compared with the conventional air Brayton cycle under five typical engine conditions. The results show that CO2 Brayton cycle proves to be superior to the air Brayton cycle in terms of the system net output power, thermal efficiency and recovery efficiency. In most cases, the recovery efficiency of CO2 Brayton cycle can be higher than 9% and the system has a better performance at the engine＇s high operating load, The thermal efficiency can be as large as 24.83% under 100% olaerating load, accordingly, the net outnut nower of 14.86 kW in nhtnined展开更多
文摘建立了一种新的管状模型来模拟普通黑烟囱体的热液循环系统，分别用达西方程、湍流方程、Ergun方程和“浮压力差”方程来描述热液循环不同关键环节处的动力学系统，用一个温度场的对流一扩散方程来描述反应区的热能交换及系统的温度变化规律．在联立几个方程并用有效的数值算法及Matlab语言编程求解后，得出了系统中温度、压力及物质流速随时间的变化曲线，并对黑烟囱体内部的动态热平衡和压力平衡进行了分析．在普通黑烟囱体系统模型的基础上进一步建立了巨型羽状流（巨羽流）生成的数学模型．选择胡安·德富卡（Juan de Fuca）洋脊热液喷口对巨羽流的形成进行了模拟，其结果与Baker根据实测数据估算的近似值吻合很好．在上述模型的基础上进一步探讨了巨羽状流形成的一系列条件及主要参数对巨羽流生成周期、温度和最大物质流速等的影响．主要结论如下：巨羽流系统可以由普通黑烟囱系统发展演化而成，其实际过程是普通黑烟囱流系统活动所形成的热液沉积在一定程度上会堵塞热液喷溢通道（相当于形成盖层），造成热液在海底之下积蓄和升温，从而导致浮压力差增大，经过2～3a（浮压力差达到盖层破裂极限值）则可形成巨羽流系统，巨羽流产生时的热源温度必须超过500℃，喷出热液的最高温度为413℃左右（与实际观测到的海底热液的最高温度一致）．当反应区热源温度增大时，产生巨羽流的临界时间明显变短（可能不到1a），而临界温度（巨羽流生成时的温度）及巨羽流的最大物质流速几乎不随其变化；随着渗透率的增大，巨羽流的最大物质流速也随之增大，但其增速随渗透率的进一步增大而变缓，并逐渐趋向一个相当于下渗流无摩擦阻力时的极限稳定值．
文摘A method of combining the valve system program with the engine cycle modeling software to form a full set of working process modeling is submitted,not only considering the system as an independent part,but also as a part of working process to evaluate comprehensively and indicate directly if the design is good or not.The designers can optimize the design by changing the engine structure,operation and the basic parameters of the cam on condition that the sysem should be stable so as to save large amounts of time and cost.Practical examples show that such a software package is an effective tool in optimizing the valve systems and performance of the machine.
基金Supported by the National Basic Research Program of China("973"Program,No.2011CB707201)the National Natural Science Foundation of China(No.51206117)
文摘A bottoming cycle system based on CO2 Brayton cycle is proposed to recover the engine exhaust heat. Its performance is compared with the conventional air Brayton cycle under five typical engine conditions. The results show that CO2 Brayton cycle proves to be superior to the air Brayton cycle in terms of the system net output power, thermal efficiency and recovery efficiency. In most cases, the recovery efficiency of CO2 Brayton cycle can be higher than 9% and the system has a better performance at the engine＇s high operating load, The thermal efficiency can be as large as 24.83% under 100% olaerating load, accordingly, the net outnut nower of 14.86 kW in nhtnined
