To reduce the wind-induced drag and improve the wind-resistance performance of a high-rise building, steady suction control is introduced into the building structure. Based on validation of the numerical methods by ex...To reduce the wind-induced drag and improve the wind-resistance performance of a high-rise building, steady suction control is introduced into the building structure. Based on validation of the numerical methods by experiment with suction control over the flow separation of a 3D backward-facing step, the Reynolds stress equation model is used to investigate the drag reduction (DR) properties of a high-rise building whose side faces are controlled by all-height suction. Effects of the orifice geometrical parameters and suction flux parameters on the DR and the separation control are analyzed, and the detailed flow fields are shown to clarify the mechanism of suction control. The results indicate that suction control is very effective in reducing the wind loads on the high-rise building model, and only the dimensionless suction flux dominates. Lastly, the power consumed and the counterforce induced by suction are discussed, the suction models become the "zero-drag" model under certain suction angles.展开更多
A bio-inspired suction cup actuated by shape memory alloy(SMA)for miniature wall climbing robots is developed based on studying characteristics of biological suction apparatus.Some fast control strategies are introduc...A bio-inspired suction cup actuated by shape memory alloy(SMA)for miniature wall climbing robots is developed based on studying characteristics of biological suction apparatus.Some fast control strategies are introduced to improve negative pressure response.Theoretic model of the suction cup is built,and simulation and experiments results indicate the effectiveness of the fast control strategies.The largest negative pressure of the suction cup can reach 14 000 Pa,and its generating and cancelling just need 5 s.Research results indicate the suction cup can be used as an adhesion mechanism for miniature wall climbing robots.展开更多
This paper presents a series of monotonically combined lateral loading tests to investigate the bearing capacity of the MSCs （modified suction caissons） in the saturated marine fine sand. The lateral loads were appl...This paper presents a series of monotonically combined lateral loading tests to investigate the bearing capacity of the MSCs （modified suction caissons） in the saturated marine fine sand. The lateral loads were applied under load- and displacement-controlled methods at the loading eccentricity ratios of 1.5, 2.0 and 2.5. Results show that, in the displacement-controlled test, the deflection-softening behavior of load-deflection curves for MSCs was observed, and the softening degree of the load-deflection response increased with the increasing external skirt length or the decreasing loading eccentricity. It was also found that the rotation center of the MSC at failure determined by the load-controlled method is slightly lower than that by the displacement-controlled method. The calculated MSC capacity based on the rotation center position in serviceability limit state is relatively conservative, compared with the calculated capacity based on the rotation center position in the ultimate limit state. In the limit state, the passive earth pressures opposite the loading direction under load- and displacement-controlled methods decrease by 46% and 74% corresponding to peak values, respectively; however, the passive earth pressures in the loading direction at failure only decrease by approximately 3% and 7%, compared with their peak values.展开更多
Highly accurate manufacture in machining industry can only be obtained with precise temperature control of the coolant （oil or water）.Machine tool with more accurate,stable and advanced the precision of the working ...Highly accurate manufacture in machining industry can only be obtained with precise temperature control of the coolant （oil or water）.Machine tool with more accurate,stable and advanced the precision of the working component cannot be developed without appropriate cooling.However,the machine tool coolers are facing the control hunting of cooling temperature and the dramatic variation of heat load in high-accuracy machining.The main objective of this study is to evaluate the influence of the hot-gas by-pass scheme and suction regulation for capacity control of a machine tool cooler system.In this study,experimental investigation on both hot-gas by-pass scheme and suction valve regulation for capacity control has been proposed.Effects of using capillary tube and thermostatic expansion valve along with different capacity control scheme have been investigated extensively in an environmental testing room.Cooling performance and power consumption of the cooler system have been measured and analyzed as well by comparing with different opening percentage of throttling valve under specific coolant temperature.The experimental results reveal that the power consumption will reduce slightly by capacity control using the hot-gas by-pass scheme but the coefficient of performance （COP） of the overall system will decrease.Lower coolant temperature will result in higher compressor power consumption as well.While conducting suction valve regulating for capacity control,energy-saving at 10%-12% can be obtained by using thermostatic expansion valve under different evaporator load.It also reveals that suction valve regulation along with adequate choice of thermostatic expansion valve can provide alternative choice for steady capacity control and substantial energy-saving.The proposed cooler systems with different capacity control schemes are not only more cost-effective than inverter driven system,but also can perform energy-saving and precise temperature control specific for high-accuracy machine tool cooling.展开更多
为提高双幅钢箱梁涡激振动性能,以某三跨钢箱连续梁桥为研究背景,提出了基于主动吸气控制的双幅钢箱梁涡激振动抑制措施。采用计算流体动力学方法研究了主动吸气控制措施对双幅钢箱梁涡激振动的抑制效果。结合Fluent用户自定义函数(user...为提高双幅钢箱梁涡激振动性能,以某三跨钢箱连续梁桥为研究背景,提出了基于主动吸气控制的双幅钢箱梁涡激振动抑制措施。采用计算流体动力学方法研究了主动吸气控制措施对双幅钢箱梁涡激振动的抑制效果。结合Fluent用户自定义函数(user defined function,UDF)和“动网格”技术,计算了双幅钢箱梁的涡激振动响应。通过对比风洞试验和数值模拟计算结果,验证了数值模拟方法的可靠性。从能量输入机制、流场等角度分析了主动吸气控制措施的抑振机理。研究结果表明,主动吸气控制措施能有效抑制双幅钢箱梁的涡激振动。吸气源的布置及吸气气流速率的大小均会影响对涡激振动的控制效果。吸气气流与回流相互作用,从而有效地抑制了桥梁的涡激振动。展开更多
基金Project (No. 59895410) supported by the National Natural Science Foundation of China
文摘To reduce the wind-induced drag and improve the wind-resistance performance of a high-rise building, steady suction control is introduced into the building structure. Based on validation of the numerical methods by experiment with suction control over the flow separation of a 3D backward-facing step, the Reynolds stress equation model is used to investigate the drag reduction (DR) properties of a high-rise building whose side faces are controlled by all-height suction. Effects of the orifice geometrical parameters and suction flux parameters on the DR and the separation control are analyzed, and the detailed flow fields are shown to clarify the mechanism of suction control. The results indicate that suction control is very effective in reducing the wind loads on the high-rise building model, and only the dimensionless suction flux dominates. Lastly, the power consumed and the counterforce induced by suction are discussed, the suction models become the "zero-drag" model under certain suction angles.
基金National Science and Technology Foundations of China(No.61075086,No.60875058)the Hi-Tech Research and Development Programof China(863 Program)(No.2009AA04Z221)
文摘A bio-inspired suction cup actuated by shape memory alloy(SMA)for miniature wall climbing robots is developed based on studying characteristics of biological suction apparatus.Some fast control strategies are introduced to improve negative pressure response.Theoretic model of the suction cup is built,and simulation and experiments results indicate the effectiveness of the fast control strategies.The largest negative pressure of the suction cup can reach 14 000 Pa,and its generating and cancelling just need 5 s.Research results indicate the suction cup can be used as an adhesion mechanism for miniature wall climbing robots.
基金supported by the National Natural Science Foundation of China(Grant Nos.51379118 and 51639002)SDUST Scientific Found(Grant No.2015KYTD104)
文摘This paper presents a series of monotonically combined lateral loading tests to investigate the bearing capacity of the MSCs （modified suction caissons） in the saturated marine fine sand. The lateral loads were applied under load- and displacement-controlled methods at the loading eccentricity ratios of 1.5, 2.0 and 2.5. Results show that, in the displacement-controlled test, the deflection-softening behavior of load-deflection curves for MSCs was observed, and the softening degree of the load-deflection response increased with the increasing external skirt length or the decreasing loading eccentricity. It was also found that the rotation center of the MSC at failure determined by the load-controlled method is slightly lower than that by the displacement-controlled method. The calculated MSC capacity based on the rotation center position in serviceability limit state is relatively conservative, compared with the calculated capacity based on the rotation center position in the ultimate limit state. In the limit state, the passive earth pressures opposite the loading direction under load- and displacement-controlled methods decrease by 46% and 74% corresponding to peak values, respectively; however, the passive earth pressures in the loading direction at failure only decrease by approximately 3% and 7%, compared with their peak values.
基金supported by Science Committee of Taiwan,China(Grant No. NSC 98-2622-E-167-029-CC3),and Industrial Technology Research Institute,Taiwan,China
文摘Highly accurate manufacture in machining industry can only be obtained with precise temperature control of the coolant （oil or water）.Machine tool with more accurate,stable and advanced the precision of the working component cannot be developed without appropriate cooling.However,the machine tool coolers are facing the control hunting of cooling temperature and the dramatic variation of heat load in high-accuracy machining.The main objective of this study is to evaluate the influence of the hot-gas by-pass scheme and suction regulation for capacity control of a machine tool cooler system.In this study,experimental investigation on both hot-gas by-pass scheme and suction valve regulation for capacity control has been proposed.Effects of using capillary tube and thermostatic expansion valve along with different capacity control scheme have been investigated extensively in an environmental testing room.Cooling performance and power consumption of the cooler system have been measured and analyzed as well by comparing with different opening percentage of throttling valve under specific coolant temperature.The experimental results reveal that the power consumption will reduce slightly by capacity control using the hot-gas by-pass scheme but the coefficient of performance （COP） of the overall system will decrease.Lower coolant temperature will result in higher compressor power consumption as well.While conducting suction valve regulating for capacity control,energy-saving at 10%-12% can be obtained by using thermostatic expansion valve under different evaporator load.It also reveals that suction valve regulation along with adequate choice of thermostatic expansion valve can provide alternative choice for steady capacity control and substantial energy-saving.The proposed cooler systems with different capacity control schemes are not only more cost-effective than inverter driven system,but also can perform energy-saving and precise temperature control specific for high-accuracy machine tool cooling.
文摘为提高双幅钢箱梁涡激振动性能,以某三跨钢箱连续梁桥为研究背景,提出了基于主动吸气控制的双幅钢箱梁涡激振动抑制措施。采用计算流体动力学方法研究了主动吸气控制措施对双幅钢箱梁涡激振动的抑制效果。结合Fluent用户自定义函数(user defined function,UDF)和“动网格”技术,计算了双幅钢箱梁的涡激振动响应。通过对比风洞试验和数值模拟计算结果,验证了数值模拟方法的可靠性。从能量输入机制、流场等角度分析了主动吸气控制措施的抑振机理。研究结果表明,主动吸气控制措施能有效抑制双幅钢箱梁的涡激振动。吸气源的布置及吸气气流速率的大小均会影响对涡激振动的控制效果。吸气气流与回流相互作用,从而有效地抑制了桥梁的涡激振动。
