针对航海模拟器中船舶运动数学模型建立过程过于复杂、仿真的有效性难以验证的问题,结合船舶自身机动特点设计了一种新的船舶运动参数发生器,可生成航海模拟器所需的各船舶运动参数。首先,在响应模型的基础上,建立了基于线加速度和角速...针对航海模拟器中船舶运动数学模型建立过程过于复杂、仿真的有效性难以验证的问题,结合船舶自身机动特点设计了一种新的船舶运动参数发生器,可生成航海模拟器所需的各船舶运动参数。首先,在响应模型的基础上,建立了基于线加速度和角速度(linear acceleration and angular velocity,a&ω)的船舶运动模型。然后,通过船舶运动微分方程求解了船舶位置、速度、姿态、航向等运动参数信息。最后,提出相似度评估指标并将其应用于基于实测数据的仿真的验证。仿真验证结果表明,船舶运动参数发生器能有效地模拟船舶在多种机动状况下的运动,各船舶运动参数的相似度均在80%以上,是一种有效的航海模拟器的船舶运动模拟仿真研究方法。展开更多
In this paper, energy separation effect in a vortex tube has been investigated using a CFD model. Thenumerical simulation has been done due to the complex structure of flow. The governing equationshave been solved by ...In this paper, energy separation effect in a vortex tube has been investigated using a CFD model. Thenumerical simulation has been done due to the complex structure of flow. The governing equationshave been solved by FLUENT code in 2D and 3D compressible and turbulent model. The effects ofgeometrical and thermo-physical parameters have been investigated. The results have shown that theoptimum length to diameter ratio is from 25 to 35. Increasing the number of nozzles from 2 to 4 withconvergent shape is found to be an efficient configuration for the swirl generator. The optimum valueof orifice diameter to tube diameter ratio, for the maximum cold air temperature difference and efficiency,has been determined to be around 0.58. The results show that if the inlet pressure increases upto a critical value, the efficiency will increase. Nevertheless, if it increases to higher values, the efficiencywill decrease. Moreover, it is found out that increasing the cold fraction decreases the coldtemperature difference and efficiency.展开更多
A numerical model of delta-wing type vortex generator was developed in two steps.The first step was to obtain a parameterized model of the shedding vortex based on delta-wing theory,which relates the geometry paramete...A numerical model of delta-wing type vortex generator was developed in two steps.The first step was to obtain a parameterized model of the shedding vortex based on delta-wing theory,which relates the geometry parameters and flow field parameters to the strength of shedding vortex which directly decides the source term.In the second step,a method was proposed to add source terms into the flow control equations so that the shedding vortex could be simulated numerically.As soon as the numerical model was completed,two cases:One for a plate and another for an airfoil segment were investigated for test.Comparison showed that the flow field structure and aerodynamic performance agreed well with those obtained from cases with real vortex generators.展开更多
文摘针对航海模拟器中船舶运动数学模型建立过程过于复杂、仿真的有效性难以验证的问题,结合船舶自身机动特点设计了一种新的船舶运动参数发生器,可生成航海模拟器所需的各船舶运动参数。首先,在响应模型的基础上,建立了基于线加速度和角速度(linear acceleration and angular velocity,a&ω)的船舶运动模型。然后,通过船舶运动微分方程求解了船舶位置、速度、姿态、航向等运动参数信息。最后,提出相似度评估指标并将其应用于基于实测数据的仿真的验证。仿真验证结果表明,船舶运动参数发生器能有效地模拟船舶在多种机动状况下的运动,各船舶运动参数的相似度均在80%以上,是一种有效的航海模拟器的船舶运动模拟仿真研究方法。
文摘In this paper, energy separation effect in a vortex tube has been investigated using a CFD model. Thenumerical simulation has been done due to the complex structure of flow. The governing equationshave been solved by FLUENT code in 2D and 3D compressible and turbulent model. The effects ofgeometrical and thermo-physical parameters have been investigated. The results have shown that theoptimum length to diameter ratio is from 25 to 35. Increasing the number of nozzles from 2 to 4 withconvergent shape is found to be an efficient configuration for the swirl generator. The optimum valueof orifice diameter to tube diameter ratio, for the maximum cold air temperature difference and efficiency,has been determined to be around 0.58. The results show that if the inlet pressure increases upto a critical value, the efficiency will increase. Nevertheless, if it increases to higher values, the efficiencywill decrease. Moreover, it is found out that increasing the cold fraction decreases the coldtemperature difference and efficiency.
基金supported by the National Natural Science Foundation of China(Grant Nos.50836006,50976117)
文摘A numerical model of delta-wing type vortex generator was developed in two steps.The first step was to obtain a parameterized model of the shedding vortex based on delta-wing theory,which relates the geometry parameters and flow field parameters to the strength of shedding vortex which directly decides the source term.In the second step,a method was proposed to add source terms into the flow control equations so that the shedding vortex could be simulated numerically.As soon as the numerical model was completed,two cases:One for a plate and another for an airfoil segment were investigated for test.Comparison showed that the flow field structure and aerodynamic performance agreed well with those obtained from cases with real vortex generators.
