This paper describes the characteristics of liquefied natural gas （LNG） carriers briefly. The LNG carrier includes power plant selection, vapor treatment, liquid cargo tank type, etc. Two parameters fuel substitutio...This paper describes the characteristics of liquefied natural gas （LNG） carriers briefly. The LNG carrier includes power plant selection, vapor treatment, liquid cargo tank type, etc. Two parameters fuel substitution rate and recovery of boil of gas （BOG） volume to energy efficiency design index （EEDI） formula are added, and EEDI formula of LNG carriers is established based on ship EEDI formula. Then, based on steam turbine propulsion device of LNG carriers, mathematical models of LNG carriers＇ reference line value are established in this paper. By verification, the EEDI formula of LNG carriers described in this paper can provide a reference for LNG carrier EEDI calculation and green shipbuilding.展开更多
The interior comer flow theory is fundamental for liquid management in space. In this paper, the interior comer flow theory is modified by correction of the curvature and shape parameters based on geometry relationshi...The interior comer flow theory is fundamental for liquid management in space. In this paper, the interior comer flow theory is modified by correction of the curvature and shape parameters based on geometry relationship, so that it can be extended to a wide range of applications including different dihedral angles and contact angles. This modification is validated with the data provided by the references using capillary tube and drop tower. Besides, the errors between the theory and experiment value are analyzed for the case of small viscosity and the long-time flow, finding that the main reason causing the error is the transformation of the flow resistance along the flow path. At last, the theory of interior comer flow is applied to the primary design of the Propellant Management Device in satellite tank, and optimum design of the vanes is given in terms of maximum flow rate.展开更多
A study of flow rate limitation in an open wedge channel is reported in this paper. Under microgravity condition, the flow is controlled by the convection and the viscosity in the channel as well as the curvature of t...A study of flow rate limitation in an open wedge channel is reported in this paper. Under microgravity condition, the flow is controlled by the convection and the viscosity in the channel as well as the curvature of the liquid free surface. A maximum flow rate is achieved when the curvature cannot balance the pressure difference leading to a collapse of the free surface. A 1-dimensional theoretical model is used to predict the critical flow rate and calculate the shape of the free surface. Computa- tional Fluid Dynamics tool is also used to simulate the phenomenon. Results show that the 1-dimensional model overestimates the critical flow rate because extra pressure loss is not included in the governing equation. Good agreement is found in 3-dim- ensional simulation results. Parametric study with different wedge angles and channel lengths show that the critical flow rate increases with increasing the cross section area; and decreases with increasing the channel length. The work in this paper can help understand the surface collapsing without gravity and for the design in propellant management devices in satellite tanks.展开更多
Micro-rockets for propulsion of small spacecrafts exhibit significant differences with regard to their macroscale counterparts,mainly caused by the role of the viscous dissipation and heat transfer processes in the mi...Micro-rockets for propulsion of small spacecrafts exhibit significant differences with regard to their macroscale counterparts,mainly caused by the role of the viscous dissipation and heat transfer processes in the micron-sized scale.The goal of this work is to simulate the transient operation of a micro-rocket to investigate the effects of viscous heating on the flow and performance for four configurations of the expanding gas and wafer material.The modelling follows a multiphysics approach that solves the fluid and solid regions fully coupled.A contin- uum-based description that incorporates the effects of gas rarefaction through the micro-nozzle,viscous dissipa- tion and heat transfer at the solid-gas interface is presented.Non-equilibrium is addressed with the implementa- tion of a 2nd-order slip-model for the velocity and temperature at the walls.The results stress that solid-fluid cou- pling exerts a strong influence on the flowfield and performance as well as the effect of the wafer during the first instants of the transient in micro-rockets made of low and high thermal conductivity materials.展开更多
基金Foundation item： Supported by the National Special Fund for Agro-scientific Research in the Public Interest （No.201003024）, and the National Natural Science Foundation of China （No.51409042 No. 51209034）.
文摘This paper describes the characteristics of liquefied natural gas （LNG） carriers briefly. The LNG carrier includes power plant selection, vapor treatment, liquid cargo tank type, etc. Two parameters fuel substitution rate and recovery of boil of gas （BOG） volume to energy efficiency design index （EEDI） formula are added, and EEDI formula of LNG carriers is established based on ship EEDI formula. Then, based on steam turbine propulsion device of LNG carriers, mathematical models of LNG carriers＇ reference line value are established in this paper. By verification, the EEDI formula of LNG carriers described in this paper can provide a reference for LNG carrier EEDI calculation and green shipbuilding.
基金supported by the National Natural Science Foundation of China (Grant No. 50975280)the Program for New Century Excellent Talents in University of Ministry of Education of China (Grant No. NCET-08-0149)
文摘The interior comer flow theory is fundamental for liquid management in space. In this paper, the interior comer flow theory is modified by correction of the curvature and shape parameters based on geometry relationship, so that it can be extended to a wide range of applications including different dihedral angles and contact angles. This modification is validated with the data provided by the references using capillary tube and drop tower. Besides, the errors between the theory and experiment value are analyzed for the case of small viscosity and the long-time flow, finding that the main reason causing the error is the transformation of the flow resistance along the flow path. At last, the theory of interior comer flow is applied to the primary design of the Propellant Management Device in satellite tank, and optimum design of the vanes is given in terms of maximum flow rate.
文摘A study of flow rate limitation in an open wedge channel is reported in this paper. Under microgravity condition, the flow is controlled by the convection and the viscosity in the channel as well as the curvature of the liquid free surface. A maximum flow rate is achieved when the curvature cannot balance the pressure difference leading to a collapse of the free surface. A 1-dimensional theoretical model is used to predict the critical flow rate and calculate the shape of the free surface. Computa- tional Fluid Dynamics tool is also used to simulate the phenomenon. Results show that the 1-dimensional model overestimates the critical flow rate because extra pressure loss is not included in the governing equation. Good agreement is found in 3-dim- ensional simulation results. Parametric study with different wedge angles and channel lengths show that the critical flow rate increases with increasing the cross section area; and decreases with increasing the channel length. The work in this paper can help understand the surface collapsing without gravity and for the design in propellant management devices in satellite tanks.
基金as part of the micropropulsion activities in the Small Satellites Programme,funded by the Spanish Ministry of Defence
文摘Micro-rockets for propulsion of small spacecrafts exhibit significant differences with regard to their macroscale counterparts,mainly caused by the role of the viscous dissipation and heat transfer processes in the micron-sized scale.The goal of this work is to simulate the transient operation of a micro-rocket to investigate the effects of viscous heating on the flow and performance for four configurations of the expanding gas and wafer material.The modelling follows a multiphysics approach that solves the fluid and solid regions fully coupled.A contin- uum-based description that incorporates the effects of gas rarefaction through the micro-nozzle,viscous dissipa- tion and heat transfer at the solid-gas interface is presented.Non-equilibrium is addressed with the implementa- tion of a 2nd-order slip-model for the velocity and temperature at the walls.The results stress that solid-fluid cou- pling exerts a strong influence on the flowfield and performance as well as the effect of the wafer during the first instants of the transient in micro-rockets made of low and high thermal conductivity materials.
