This paper proposes a novel wake-induced vibration(WIV)-based energy harvesting system consisting of two bluff bodies.An inverted C-shaped bluff body is stationary installed at the upstream position to generate an int...This paper proposes a novel wake-induced vibration(WIV)-based energy harvesting system consisting of two bluff bodies.An inverted C-shaped bluff body is stationary installed at the upstream position to generate an interference wake street,and a cylinder bluff body equipped with a transducer is elastically suspended at the downstream position to harness WIV energy.The hydrodynamics and energy harvesting(EH)performance of the proposed system are investigated via experimental studies.The reduced velocity(U*)ranging from 2 to 14(the corresponding Reynolds number ranging from 15100 to 106200)is considered in the present study.It is found that the wake generated by the inverted C-shaped bluff body significantly affects the EH performance.Enlarging the opening angle(α)of the C-shaped bluff body increases the vibration amplitude of the downstream cylinder,thereby increasing the harvested power.When the spacing(L)between two bluff bodies is two times the cylinder diameter(D),the wake-induced vibration(WIV)mode is observed,while the combined WIV and wake galloping(WG)mode occurs whenαis 150°,and L equals 3D or 4D.The average drag coefficient becomes negative when L is 2D,3D,or 4D.By carefully configuring a C-shaped bluff body,the wake generated by it can bring an augmenting effect on the vibration of the downstream EH cylinder.For example,the RMS power output of the proposed EH system reaches a maximum of 0.31 W at U*=8 and L=4D,which is 300%greater than that of its traditional counterpart.Furthermore,after a number of case stud-ies,it is identified that the proposed EH system can achieve the best performance whenαis 150°and L=2D.展开更多
目的评估依据膀胱安全容量行间歇性导尿对骶上脊髓损伤患者下尿路功能的影响。方法 2019年1月至12月选取本院骶上脊髓损伤后下尿路功能障碍患者60例,随机分为对照组(n=30)和观察组(n=30)。对照组行间歇性导尿,导尿频率依据残余尿。观察...目的评估依据膀胱安全容量行间歇性导尿对骶上脊髓损伤患者下尿路功能的影响。方法 2019年1月至12月选取本院骶上脊髓损伤后下尿路功能障碍患者60例,随机分为对照组(n=30)和观察组(n=30)。对照组行间歇性导尿,导尿频率依据残余尿。观察组行间歇性导尿,导尿频率依据膀胱安全容量。比较两组最大逼尿肌压、残余尿、膀胱安全容量、尿路感染情况和逼尿肌厚度。结果治疗8周后,观察组最大逼尿肌压、残余尿减少,膀胱安全容量显著增加(t> 5.623, P <0.05),且均优于对照组(t> 2.242, P <0.05);逼尿肌厚度显著降低(t=7.871, P <0.05),且明显低于对照组(t=3.049, P <0.01),尿路感染次数少于对照组(χ^(2)=4.320, P=0.038)。结论依据膀胱安全容量行间歇性导尿,可以改善骶上脊髓损伤患者下尿路功能。展开更多
The vibration response of a free-hanging flexible riser induced by internal gas-liquid slug flow was studied experimentally in a small-diameter tube model based on Froude number criterion. The flow regime in a curved ...The vibration response of a free-hanging flexible riser induced by internal gas-liquid slug flow was studied experimentally in a small-diameter tube model based on Froude number criterion. The flow regime in a curved riser model and the response displacements of the riser were simultaneously recorded by high speed cameras. The gas superficial velocity ranges from 0.1 m/s to 0.6 m/s while the liquid superficial velocity from 0.06 m/s to 0.3 m/s.Severe slugging type 3, unstable oscillation flow and relatively stable slug flow were observed in the considered flow rates. Severe slugging type 3 characterized by premature gas penetration occurs at relatively low flow rates. Both the cycle time and slug length become shorter as the gas flow rate increases. The pressure at the riser base undergoes a longer period and larger amplitude of fluctuation as compared with the other two flow regimes. Additionally, severe slugging leads to the most vigorous in-plane vibration. However, the responses in the vertical and horizontal directions are not synchronized. The vertical vibration is dominated by the second mode while the horizontal vibration is dominated by the first mode. Similar to the vortex-induced vibration, three branches are identified as initial branch, build-up branch and descending branch for the response versus the mixture velocity of gas-liquid flow.展开更多
基金financially supported by the National Natural Science Foundation of China(Grant Nos.51977196,52277227,and52305135)Open Project of Henan Key Laboratory of Intelligent Manufacturing of Mechanical Equipment,Zhengzhou University of Light Industry(Grant No.IM202302)+3 种基金the Natural Science Foundation of Excellent Youth of Henan Province(Grant No.222300420076)the Science and Technology Research&Development Joint Foundation of Henan Province-Young Scientists(Grant No.225200810099)the Program for Science&Technology Innovation Talents in Universities of Henan Province(Grant No.23HASTIT010)the National Center for International Research of Subsea Engineering Technology and Equipment(Grant No.3132023366).
文摘This paper proposes a novel wake-induced vibration(WIV)-based energy harvesting system consisting of two bluff bodies.An inverted C-shaped bluff body is stationary installed at the upstream position to generate an interference wake street,and a cylinder bluff body equipped with a transducer is elastically suspended at the downstream position to harness WIV energy.The hydrodynamics and energy harvesting(EH)performance of the proposed system are investigated via experimental studies.The reduced velocity(U*)ranging from 2 to 14(the corresponding Reynolds number ranging from 15100 to 106200)is considered in the present study.It is found that the wake generated by the inverted C-shaped bluff body significantly affects the EH performance.Enlarging the opening angle(α)of the C-shaped bluff body increases the vibration amplitude of the downstream cylinder,thereby increasing the harvested power.When the spacing(L)between two bluff bodies is two times the cylinder diameter(D),the wake-induced vibration(WIV)mode is observed,while the combined WIV and wake galloping(WG)mode occurs whenαis 150°,and L equals 3D or 4D.The average drag coefficient becomes negative when L is 2D,3D,or 4D.By carefully configuring a C-shaped bluff body,the wake generated by it can bring an augmenting effect on the vibration of the downstream EH cylinder.For example,the RMS power output of the proposed EH system reaches a maximum of 0.31 W at U*=8 and L=4D,which is 300%greater than that of its traditional counterpart.Furthermore,after a number of case stud-ies,it is identified that the proposed EH system can achieve the best performance whenαis 150°and L=2D.
文摘目的评估依据膀胱安全容量行间歇性导尿对骶上脊髓损伤患者下尿路功能的影响。方法 2019年1月至12月选取本院骶上脊髓损伤后下尿路功能障碍患者60例,随机分为对照组(n=30)和观察组(n=30)。对照组行间歇性导尿,导尿频率依据残余尿。观察组行间歇性导尿,导尿频率依据膀胱安全容量。比较两组最大逼尿肌压、残余尿、膀胱安全容量、尿路感染情况和逼尿肌厚度。结果治疗8周后,观察组最大逼尿肌压、残余尿减少,膀胱安全容量显著增加(t> 5.623, P <0.05),且均优于对照组(t> 2.242, P <0.05);逼尿肌厚度显著降低(t=7.871, P <0.05),且明显低于对照组(t=3.049, P <0.01),尿路感染次数少于对照组(χ^(2)=4.320, P=0.038)。结论依据膀胱安全容量行间歇性导尿,可以改善骶上脊髓损伤患者下尿路功能。
基金financially supported by the National Natural Science Foundation of China(Grant No.11502220)the Youth Science&Technology Foundation of Sichuan Province(Grant No.2017JQ0055)the Youth Scientific and Technological Innovation Team of the Safety of Deep-Water Pipe Strings of Southwest Petroleum University(Grant No.2017CXTD06)
文摘The vibration response of a free-hanging flexible riser induced by internal gas-liquid slug flow was studied experimentally in a small-diameter tube model based on Froude number criterion. The flow regime in a curved riser model and the response displacements of the riser were simultaneously recorded by high speed cameras. The gas superficial velocity ranges from 0.1 m/s to 0.6 m/s while the liquid superficial velocity from 0.06 m/s to 0.3 m/s.Severe slugging type 3, unstable oscillation flow and relatively stable slug flow were observed in the considered flow rates. Severe slugging type 3 characterized by premature gas penetration occurs at relatively low flow rates. Both the cycle time and slug length become shorter as the gas flow rate increases. The pressure at the riser base undergoes a longer period and larger amplitude of fluctuation as compared with the other two flow regimes. Additionally, severe slugging leads to the most vigorous in-plane vibration. However, the responses in the vertical and horizontal directions are not synchronized. The vertical vibration is dominated by the second mode while the horizontal vibration is dominated by the first mode. Similar to the vortex-induced vibration, three branches are identified as initial branch, build-up branch and descending branch for the response versus the mixture velocity of gas-liquid flow.
