A comparison of the results of a computational simulation and an experimental measurement indicates a good agreement between them: the bowed blade lowers the energy loss coefficient of engine by 11% in the simulation...A comparison of the results of a computational simulation and an experimental measurement indicates a good agreement between them: the bowed blade lowers the energy loss coefficient of engine by 11% in the simulation and by 13% in the measurement. To further discuss the application conditions of bowed blade in compressor, with incidence equal to zero and other boundary conditions unchanged, a computational investigations on four series of linear stators with different aerofoil turning angles are achieved. It is found that the bowed blade has much positive effect in high airfoil turning angle cascade, for example, the optimal retrofit of 30° bow angle highly reduces the energy loss coefficient by 17.9%, when the aerofoil turning angle is 59.5 °. But the optimal retrofit of 15° has only 0.7% reduction when the aerofoil turning angle is 39.5°, or even the compressor performance will get worse with the bow angle gradually increasing. Consequently, it is verified that the turning angle is one of the important factors to decide whether to apply the bowed blade into compressor at low Math number.展开更多
Recently,the demand for comprehension of mixed traffic in developing countries,particularly at roundabouts,which are highly interactive road junctions,has increased.Thus,we analyzed mixed traffic at roundabouts,consid...Recently,the demand for comprehension of mixed traffic in developing countries,particularly at roundabouts,which are highly interactive road junctions,has increased.Thus,we analyzed mixed traffic at roundabouts,considering Vietnam as a case study.The two main objectives of this study were to characterize the mixed traffic in Vietnam and to determine the microscopic characteristics of motorcycles at roundabouts.First,efforts were made to clarify the two constitutions of mixed traffic(the performance rule and the presence of small-sized vehicles),and the term“motorcycle-oriented mixed traffic”was defined.Even when satisfying the two fundamental constitutions,this traffic state has unique features,e.g.,only one type of non-lane-based vehicle(the motorcycle)and the predominance of motorcycles in the traffic composition(91.7%).Second,four microscopic characteristics of motorcycles were obtained from a large dataset:the motorcycles’continuous changes in speed,the relationship between the turning angle rate and the speed,the critical gap,and the following space.The relationship between the turning angle rate and the speed was first formulated as a power curve.The critical gap of motorcycles was estimated as a small value(1.25 s)in the case study.The following spaces varied with respect to the speed and had an oval shape.The smallest lateral and longitudinal dimensions were 1.5 and 1.74 m,respectively.While all the findings are meaningful,they are restricted to the case study(Ho Chi Minh City,Vietnam).展开更多
基金National Natural Science Foundation of China(50236020).
文摘A comparison of the results of a computational simulation and an experimental measurement indicates a good agreement between them: the bowed blade lowers the energy loss coefficient of engine by 11% in the simulation and by 13% in the measurement. To further discuss the application conditions of bowed blade in compressor, with incidence equal to zero and other boundary conditions unchanged, a computational investigations on four series of linear stators with different aerofoil turning angles are achieved. It is found that the bowed blade has much positive effect in high airfoil turning angle cascade, for example, the optimal retrofit of 30° bow angle highly reduces the energy loss coefficient by 17.9%, when the aerofoil turning angle is 59.5 °. But the optimal retrofit of 15° has only 0.7% reduction when the aerofoil turning angle is 39.5°, or even the compressor performance will get worse with the bow angle gradually increasing. Consequently, it is verified that the turning angle is one of the important factors to decide whether to apply the bowed blade into compressor at low Math number.
文摘Recently,the demand for comprehension of mixed traffic in developing countries,particularly at roundabouts,which are highly interactive road junctions,has increased.Thus,we analyzed mixed traffic at roundabouts,considering Vietnam as a case study.The two main objectives of this study were to characterize the mixed traffic in Vietnam and to determine the microscopic characteristics of motorcycles at roundabouts.First,efforts were made to clarify the two constitutions of mixed traffic(the performance rule and the presence of small-sized vehicles),and the term“motorcycle-oriented mixed traffic”was defined.Even when satisfying the two fundamental constitutions,this traffic state has unique features,e.g.,only one type of non-lane-based vehicle(the motorcycle)and the predominance of motorcycles in the traffic composition(91.7%).Second,four microscopic characteristics of motorcycles were obtained from a large dataset:the motorcycles’continuous changes in speed,the relationship between the turning angle rate and the speed,the critical gap,and the following space.The relationship between the turning angle rate and the speed was first formulated as a power curve.The critical gap of motorcycles was estimated as a small value(1.25 s)in the case study.The following spaces varied with respect to the speed and had an oval shape.The smallest lateral and longitudinal dimensions were 1.5 and 1.74 m,respectively.While all the findings are meaningful,they are restricted to the case study(Ho Chi Minh City,Vietnam).