This paper presents an investigation on the effect of probe support on the flow field of an axial compressor.The experiment is carried out in a large-scale low-speed research compressor.A cylindrical probe support int...This paper presents an investigation on the effect of probe support on the flow field of an axial compressor.The experiment is carried out in a large-scale low-speed research compressor.A cylindrical probe support intruding to 50% blade span was installed at 50% chord upstream from the rotor leading edge.The region from 5° to 32° off the probe support in the direction of rotation at the rotor outlet was measured with a 5-hole probe and a high-response total pressure probe.The experiment is performed at both near-design and near-stall points.The measuring results of 5-hole probe and high-response total pressure probe indicate that the probe blockage effect is different at different blade spans.The wake of the probe support weakens the leakage vortex intensity at the tip region,leading to greater total pressure rise.At near-design condition,the presence of probe support has a negative effect on the region from 75% to 92% span,while improves the flow field below 75% span.At near stall condition,the probe support has a negative effect on the region from 70% to 90% span,and almost has no influence on the flow field below 70% span.展开更多
China railways track structure II (CRTS II) slab ballastless track on bridge is one kind of track structures unique to China. Its main bearing component of longitudinal force is the continuous base plate rather than ...China railways track structure II (CRTS II) slab ballastless track on bridge is one kind of track structures unique to China. Its main bearing component of longitudinal force is the continuous base plate rather than rail. And the track-bridge interaction is weakened by the sliding layer installed between base plate and bridge deck. In order to study the dynamic response of CRTS II slab ballastless track on bridge under seismic action, a 3D nonlinear dynamic model for simply-supported bridges and CRTS II track was established, which considered structures such as steel rail, fasteners, track plate, mortar layer, base plate, sliding layer, bridge, consolidation, anchors, stoppers, etc. Then its force and deformation features under different intensities of seismic excitation were studied. As revealed, the seismic response of the system increases with the increase of seismic intensity. The peak stresses of rail, track plate and base plate all occur at the abutment or anchors. Both track plate and base plate are about to crack. Besides, the rapid relative displacement between base plate and bridge deck due to the small friction coefficient of sliding layer is beneficial to improve the seismic performance of the system. During the earthquake, a large vertical displacement appears in base plate which leads to frequent collisions between stoppers and base plate, as a result, stoppers may be damaged.展开更多
目前风机调频的研究主要基于仿真的方法,无法定量评估风机调频能力。针对这一现状,推导了减载与最大风能捕捉(maximum power point tracking, MPPT)两种方式下风机参与调频时系统的频率响应模型,并根据频率响应模型计算两种方式下频率...目前风机调频的研究主要基于仿真的方法,无法定量评估风机调频能力。针对这一现状,推导了减载与最大风能捕捉(maximum power point tracking, MPPT)两种方式下风机参与调频时系统的频率响应模型,并根据频率响应模型计算两种方式下频率最低点,通过频率最低点定量评估风机调频能力。在减载方式下,频率最低点可通过对系统频率响应模型直接进行反拉普拉斯变换得到;但在MPPT方式下因系统频率响应模型阶数较高而难以直接求出频率最低点,故提出一种利用非主导极点进行降阶的方法,并利用降阶模型计算出频率最低点。后计算频率最低点对调频控制器参数及风机初始转速的灵敏度,灵敏度结果表明频率最低点受到调频控制器参数与风机初始转速两个因素的影响:控制器参数增大可以提升系统频率最低点,而风机初始转速上升则会造成频率最低点下降。最后通过仿真验证了各因素对频率最低点的影响。展开更多
基金funded by the National Natural Science Foundation of China,Grant No.51161130525,51136003,and the 111 Project,No.B07009
文摘This paper presents an investigation on the effect of probe support on the flow field of an axial compressor.The experiment is carried out in a large-scale low-speed research compressor.A cylindrical probe support intruding to 50% blade span was installed at 50% chord upstream from the rotor leading edge.The region from 5° to 32° off the probe support in the direction of rotation at the rotor outlet was measured with a 5-hole probe and a high-response total pressure probe.The experiment is performed at both near-design and near-stall points.The measuring results of 5-hole probe and high-response total pressure probe indicate that the probe blockage effect is different at different blade spans.The wake of the probe support weakens the leakage vortex intensity at the tip region,leading to greater total pressure rise.At near-design condition,the presence of probe support has a negative effect on the region from 75% to 92% span,while improves the flow field below 75% span.At near stall condition,the probe support has a negative effect on the region from 70% to 90% span,and almost has no influence on the flow field below 70% span.
基金supported by the National Natural Science Foundation of China (Grant No. 51608542)Project of Science and Technology Research and Development Program of China Railway Corporation (Grant No.2015G001-G)
文摘China railways track structure II (CRTS II) slab ballastless track on bridge is one kind of track structures unique to China. Its main bearing component of longitudinal force is the continuous base plate rather than rail. And the track-bridge interaction is weakened by the sliding layer installed between base plate and bridge deck. In order to study the dynamic response of CRTS II slab ballastless track on bridge under seismic action, a 3D nonlinear dynamic model for simply-supported bridges and CRTS II track was established, which considered structures such as steel rail, fasteners, track plate, mortar layer, base plate, sliding layer, bridge, consolidation, anchors, stoppers, etc. Then its force and deformation features under different intensities of seismic excitation were studied. As revealed, the seismic response of the system increases with the increase of seismic intensity. The peak stresses of rail, track plate and base plate all occur at the abutment or anchors. Both track plate and base plate are about to crack. Besides, the rapid relative displacement between base plate and bridge deck due to the small friction coefficient of sliding layer is beneficial to improve the seismic performance of the system. During the earthquake, a large vertical displacement appears in base plate which leads to frequent collisions between stoppers and base plate, as a result, stoppers may be damaged.
文摘目前风机调频的研究主要基于仿真的方法,无法定量评估风机调频能力。针对这一现状,推导了减载与最大风能捕捉(maximum power point tracking, MPPT)两种方式下风机参与调频时系统的频率响应模型,并根据频率响应模型计算两种方式下频率最低点,通过频率最低点定量评估风机调频能力。在减载方式下,频率最低点可通过对系统频率响应模型直接进行反拉普拉斯变换得到;但在MPPT方式下因系统频率响应模型阶数较高而难以直接求出频率最低点,故提出一种利用非主导极点进行降阶的方法,并利用降阶模型计算出频率最低点。后计算频率最低点对调频控制器参数及风机初始转速的灵敏度,灵敏度结果表明频率最低点受到调频控制器参数与风机初始转速两个因素的影响:控制器参数增大可以提升系统频率最低点,而风机初始转速上升则会造成频率最低点下降。最后通过仿真验证了各因素对频率最低点的影响。
