In the design of Hydraulic Manifold Blocks (HMB), dynamic performance of inner pipeline networks usually should be evaluated. To meet the design requirements, dynamic characteristic simulation is often needed. Based o...In the design of Hydraulic Manifold Blocks (HMB), dynamic performance of inner pipeline networks usually should be evaluated. To meet the design requirements, dynamic characteristic simulation is often needed. Based on comprehensive study on the existing simulation methods, a new method combined of Power Bond Graph(PBG) and Computational Fluid Dynamic (CFD) is proposed. In this method, flow field of typical channels inside HMB is analyzed with CFD to obtain the local resistance coefficients. Then, with these coefficients, a new sectional lumped-parameter model including kinetic friction factor is developed using PBG. A typical HMB design example is given and the comparison between the simulation and the experimental results demonstrates the feasibility and effectiveness of the proposed method.展开更多
Optimization of airfoil characteristics such as lift and drag is essential for high efficiency wind turbine blade design. In this research, effects of airfoil lift and drag on blade power coefficients were investigate...Optimization of airfoil characteristics such as lift and drag is essential for high efficiency wind turbine blade design. In this research, effects of airfoil lift and drag on blade power coefficients were investigated by using of wind turbine blade design software, PROPID. Firstly, a wind turbine blade of 2MW class was designed with DU-serics airfoils in the inner part and with aNACA series airfoil as a main airfoil in the outer part. Lift distribution was set to have near L/D maximum at each span station. Then, lift and drag curves were modified to observe effect of L/D variation. Drag and lift change with constant L/D on blade power coefficient was also studied for sensitivity investigation. Each case was optimized with Newtonian iteration incorporated in PROPID. High design lift coefficient results in less chord length and twist angle to maintain same aerodynamic load level. And, power coefficient wasn＇t improved much with high L/D. During the process, optimal inputs such as lift distribution, design lift and induction factors were suggested. As results, it was found that L/D maximization was important to obtain high efficiency. For the L/D maximization, lift maximization was important to minimize structural weight, but decreasing drag didn＇t affect the blade shape.展开更多
Absolute commitment to reduce the impact of greenhouse gas emissions while increasing fuel efficiency and power density requires further enhancement of prime mover characteristics and special coatings, but mostly requ...Absolute commitment to reduce the impact of greenhouse gas emissions while increasing fuel efficiency and power density requires further enhancement of prime mover characteristics and special coatings, but mostly requires compliance with EEDI （energy efficiency design index） measures. For the container shipping industry this represents significant increases in fuel costs that can be mitigated above all by reduction of power demand, that is, of ship frictional resistance. In this respect, this paper discusses advantages attainable by application of the ACS （air cavity system） technology on the basis of recent KSRC （Krylov State Research Centre） studies Savings in operating costs yielded by the enhanced propulsion performance for ships fitted with this system are illustrated by a case study of a containership.展开更多
基金National Natural Science Foundation of China (No.50375023)
文摘In the design of Hydraulic Manifold Blocks (HMB), dynamic performance of inner pipeline networks usually should be evaluated. To meet the design requirements, dynamic characteristic simulation is often needed. Based on comprehensive study on the existing simulation methods, a new method combined of Power Bond Graph(PBG) and Computational Fluid Dynamic (CFD) is proposed. In this method, flow field of typical channels inside HMB is analyzed with CFD to obtain the local resistance coefficients. Then, with these coefficients, a new sectional lumped-parameter model including kinetic friction factor is developed using PBG. A typical HMB design example is given and the comparison between the simulation and the experimental results demonstrates the feasibility and effectiveness of the proposed method.
文摘Optimization of airfoil characteristics such as lift and drag is essential for high efficiency wind turbine blade design. In this research, effects of airfoil lift and drag on blade power coefficients were investigated by using of wind turbine blade design software, PROPID. Firstly, a wind turbine blade of 2MW class was designed with DU-serics airfoils in the inner part and with aNACA series airfoil as a main airfoil in the outer part. Lift distribution was set to have near L/D maximum at each span station. Then, lift and drag curves were modified to observe effect of L/D variation. Drag and lift change with constant L/D on blade power coefficient was also studied for sensitivity investigation. Each case was optimized with Newtonian iteration incorporated in PROPID. High design lift coefficient results in less chord length and twist angle to maintain same aerodynamic load level. And, power coefficient wasn＇t improved much with high L/D. During the process, optimal inputs such as lift distribution, design lift and induction factors were suggested. As results, it was found that L/D maximization was important to obtain high efficiency. For the L/D maximization, lift maximization was important to minimize structural weight, but decreasing drag didn＇t affect the blade shape.
文摘Absolute commitment to reduce the impact of greenhouse gas emissions while increasing fuel efficiency and power density requires further enhancement of prime mover characteristics and special coatings, but mostly requires compliance with EEDI （energy efficiency design index） measures. For the container shipping industry this represents significant increases in fuel costs that can be mitigated above all by reduction of power demand, that is, of ship frictional resistance. In this respect, this paper discusses advantages attainable by application of the ACS （air cavity system） technology on the basis of recent KSRC （Krylov State Research Centre） studies Savings in operating costs yielded by the enhanced propulsion performance for ships fitted with this system are illustrated by a case study of a containership.
