Large-eddy simulation of spray combustion is under its rapid development.Different combustion models were used by different investigators.However,these models are less validated by detailed experimental data.In this p...Large-eddy simulation of spray combustion is under its rapid development.Different combustion models were used by different investigators.However,these models are less validated by detailed experimental data.In this paper,large-eddy simulation(LES)of ethanol spray-air combustion was made using an Eulerian-Lagrangian approach,a subgrid-scale kinetic energy stress model,and a filtered finite-rate combustion model,neglecting the sub-grid scale reaction rate.The simulation results are compared with experimental dada in the literature and validated in detail.The LES obtained statistically averaged gas temperature is in much better agreement with the experimental results than Reynolds averaged(RANS)modeling using the most complex probability density function(PDF)equation combustion model.The instantaneous LES results show the coherent structures of the shear region near the high-temperature flame zone and the fuel vapor concentration map,indicating that the droplets are concentrated in this shear region.The instantaneous temperature,oxygen and carbon dioxide concentration maps show the close interaction between the coherent structures and the combustion reaction.展开更多
To investigate the influence of wet conditions on vehicle braking behavior,a numerical-analytical method was proposed for the simulation of tire hydroplaning and frictional energy dissipation. First, a finite element ...To investigate the influence of wet conditions on vehicle braking behavior,a numerical-analytical method was proposed for the simulation of tire hydroplaning and frictional energy dissipation. First, a finite element model of tire hydroplaning was established using the coupled EulerianLagrangian method,including a pneumatic tire model and a textured asphalt pavement model. Then,the frictional force on the tire-pavement interface at different speeds was calculated by the model. Based on vehicle braking mechanism and frictional energy dissipation,a calculation method for braking distance was proposed based on a three-stage braking process. The proposed method was verified by comparing the calculated hydroplaning speed and braking distance with field test results.Then,vehicle braking distances and wet friction coefficients were calculated under different conditions. The results show that thinner water film,a more complex tread pattern and higher tire inflation pressure all contribute to the vehicle braking performance; moreover, the pavement texture has obvious influence on vehicle braking behavior,especially at a high speed. The proposed method shows great effectiveness in predicting vehicle braking behavior on wet asphalt pavements.展开更多
The leaders of the Meiji Restoration believed in their master, Yoshida Shoin （吉田松陰）, who claimed that in order for the islands of Japan not to be a colony of the powerful Western states, Japan had to conquer nea...The leaders of the Meiji Restoration believed in their master, Yoshida Shoin （吉田松陰）, who claimed that in order for the islands of Japan not to be a colony of the powerful Western states, Japan had to conquer nearby countries. This led to Japan’s invasion of the Ryukyu Islands, Taiwan, Korea, and Manchuria, which ultimately led to the Manchurian Incident of 1931, the Sino-Japanese War, and the Pacific War. Surprisingly, the subject and the timing of each and every one of these acts of war were in the same order of Yoshida Shoin’s proposal on preoccupancy. The Sino-Japanese war of 1894 was romanticized as clearing the barbaric culture by civilization, and the Russo-Japanese war of 1904 was romanticized as the realization of Eastern Peace. However, Japanese policies of aggressions were first deemed illegal by international law during the 1931 Manchurian Incident by the investigations of the League of Nations. The Japanese Empire received the recommendation by the League of Nations to restore to original state, but declined and exited from the League of Nations. Following their exit, they started the Sino-Japanese War and the Pacific War and eventually lost in 1945. The goal of the San Francisco Peace Treaty of 1951 was to punish Japan’s aggressions. However, as the Cold War between the East and the West started to arise in 1948, the punishment was eased, and their punishment for the aggressions on the Ryukyu Islands, Taiwan, and Korea was nearly unasked for. This paper examines the issues of the San Francisco Peace Treaty in the views of the international law of the League of Nations, established by Manley O. Hudson of Harvard University and others in U.S. academia and judiciary.展开更多
基金Supported by the National Natural Science Foundation of China(5073600,51266008)the Research Grant Council of Hong Kong(5105/08E,B-Q10H)
文摘Large-eddy simulation of spray combustion is under its rapid development.Different combustion models were used by different investigators.However,these models are less validated by detailed experimental data.In this paper,large-eddy simulation(LES)of ethanol spray-air combustion was made using an Eulerian-Lagrangian approach,a subgrid-scale kinetic energy stress model,and a filtered finite-rate combustion model,neglecting the sub-grid scale reaction rate.The simulation results are compared with experimental dada in the literature and validated in detail.The LES obtained statistically averaged gas temperature is in much better agreement with the experimental results than Reynolds averaged(RANS)modeling using the most complex probability density function(PDF)equation combustion model.The instantaneous LES results show the coherent structures of the shear region near the high-temperature flame zone and the fuel vapor concentration map,indicating that the droplets are concentrated in this shear region.The instantaneous temperature,oxygen and carbon dioxide concentration maps show the close interaction between the coherent structures and the combustion reaction.
基金The National Natural Science Foundation of China(No.51378121,51778139)
文摘To investigate the influence of wet conditions on vehicle braking behavior,a numerical-analytical method was proposed for the simulation of tire hydroplaning and frictional energy dissipation. First, a finite element model of tire hydroplaning was established using the coupled EulerianLagrangian method,including a pneumatic tire model and a textured asphalt pavement model. Then,the frictional force on the tire-pavement interface at different speeds was calculated by the model. Based on vehicle braking mechanism and frictional energy dissipation,a calculation method for braking distance was proposed based on a three-stage braking process. The proposed method was verified by comparing the calculated hydroplaning speed and braking distance with field test results.Then,vehicle braking distances and wet friction coefficients were calculated under different conditions. The results show that thinner water film,a more complex tread pattern and higher tire inflation pressure all contribute to the vehicle braking performance; moreover, the pavement texture has obvious influence on vehicle braking behavior,especially at a high speed. The proposed method shows great effectiveness in predicting vehicle braking behavior on wet asphalt pavements.
文摘The leaders of the Meiji Restoration believed in their master, Yoshida Shoin （吉田松陰）, who claimed that in order for the islands of Japan not to be a colony of the powerful Western states, Japan had to conquer nearby countries. This led to Japan’s invasion of the Ryukyu Islands, Taiwan, Korea, and Manchuria, which ultimately led to the Manchurian Incident of 1931, the Sino-Japanese War, and the Pacific War. Surprisingly, the subject and the timing of each and every one of these acts of war were in the same order of Yoshida Shoin’s proposal on preoccupancy. The Sino-Japanese war of 1894 was romanticized as clearing the barbaric culture by civilization, and the Russo-Japanese war of 1904 was romanticized as the realization of Eastern Peace. However, Japanese policies of aggressions were first deemed illegal by international law during the 1931 Manchurian Incident by the investigations of the League of Nations. The Japanese Empire received the recommendation by the League of Nations to restore to original state, but declined and exited from the League of Nations. Following their exit, they started the Sino-Japanese War and the Pacific War and eventually lost in 1945. The goal of the San Francisco Peace Treaty of 1951 was to punish Japan’s aggressions. However, as the Cold War between the East and the West started to arise in 1948, the punishment was eased, and their punishment for the aggressions on the Ryukyu Islands, Taiwan, and Korea was nearly unasked for. This paper examines the issues of the San Francisco Peace Treaty in the views of the international law of the League of Nations, established by Manley O. Hudson of Harvard University and others in U.S. academia and judiciary.
