The aerodynamic design of a rigid-flexible coupling profile is the decisive factor for the flow-field quality of a supersonic free jet wind tunnel nozzle, and its mechanic dynamic features are the key for engineering ...The aerodynamic design of a rigid-flexible coupling profile is the decisive factor for the flow-field quality of a supersonic free jet wind tunnel nozzle, and its mechanic dynamic features are the key for engineering implementation of continuous Mach number regulations. To fulfill the requirements of a free jet inlet/engine compatibility test within a wide simulation envelop, both uniform flow-fields of continuous acceleration and deceleration are necessary. In this paper, the aerodynamic design methods of an expansion wall and machinery implementation plan for the halfflexible single jack nozzle were researched. The profile control in nozzle flexible plate design was studied with a rigid-flexible coupling method. Design and calculations were performed with the help of numerical simulation. The technique of axial free stretching of the flexible plate was used to improve the matching performance between the designed elasticity profile and the theoretical one, and the rigid-flexible coupling structure was calibrated by wind tunnel tests. Results indicate that the flexible plate aerodynamic design method used here is effective and feasible. Via rigidflexible coupling design, the flexible plate agrees with the rigid body very well, and continuous Mach number changes can be achieved during the tests. The nozzle’s exit flow-field uniformity meets the requirements of China Military Standard(GJB).展开更多
Performance characteristics of partially hydrolyzed polyacrylamide （HPAM） and cross- linked polymer （CLP, Cr^3＋ as the cross linker） solutions have been investigated. A Brookfield viscometer, rheometer, dynamic l...Performance characteristics of partially hydrolyzed polyacrylamide （HPAM） and cross- linked polymer （CLP, Cr^3＋ as the cross linker） solutions have been investigated. A Brookfield viscometer, rheometer, dynamic light scattering system, and core flow device have been used to measure the viscosity, viscoelasticity, polymer coil dimensions, molecular configuration, flow characteristics, and profile modification. The results show that, under conditions of high salinity and low HPAM and Cr^3＋ concentrations, cross-linking mainly occurred between different chains of the same HPAM molecule in the presence of Cr^3＋, and a cross-linked polymer （CLP） system with a local network structure was formed. Compared with an HPAM solution of the same concentration, the apparent viscosity of the CLP solution increased slightly or remained almost unchanged, but its viscoelasticity （namely storage modulus, loss modulus, and first normal stress difference） increased, and the resistance coefficient and residual resistance coefficient increased significantly. This indicates that the CLP solution exhibits a strong capability to divert the sequentially injected polymer flood from high-permeability zones to low- permeability zones in a reservoir. Under the same HPAM concentration conditions, the dimensions of polymer coils in the CLP solution increased slightly compared with the dimensions of polymer coils in HPAM solution, which were smaller than the rock pores, indicating that the cross-linked polymer solution was well adapted to reservoir rocks. Core flood experiments show that at the same cost of reagent, the oil recovery by CLP injection （HPAM-1, Cr^3＋ as the cross linker） is 3.1% to 5.2% higher than that by HPAM- 2 injection.展开更多
To solve the defects of bottom concave appearing in the extrusion experiments of complex hollow aluminium profiles,a 3D finite element model for simulating steady-state porthole die extrusion process was established b...To solve the defects of bottom concave appearing in the extrusion experiments of complex hollow aluminium profiles,a 3D finite element model for simulating steady-state porthole die extrusion process was established based on HyperXtrude software using Arbitrary Lagrangian–Eulerian(ALE)algorithm.The velocity distribution on the cross-section of the extrudate at the die exit and pressure distribution at different heights in the welding chamber were quantitatively analyzed.To obtain an uniformity of metal flow velocity at the die exit,the porthole die structure was optimized by adding baffle plates.After optimization,maximum displacement in the Y direction at the bottom of profile decreases from 1.1 to 0.15 mm,and the concave defects are remarkably improved.The research method provides an effective guidance for improving extrusion defects and optimizing the metal flow of complex hollow aluminium profiles during porthole die extrusion.展开更多
以L型双层共挤异型材为研究对象,采用Phan-Thien and Tanner(PTT)本构方程,应用Arrhenius方程来描述温度对黏度的影响,通过有限元方法分析了聚丙烯(PP)/聚苯乙烯(PS)熔体在气辅共挤口模内的三维黏弹非等温流动过程,对比分析了不同流率...以L型双层共挤异型材为研究对象,采用Phan-Thien and Tanner(PTT)本构方程,应用Arrhenius方程来描述温度对黏度的影响,通过有限元方法分析了聚丙烯(PP)/聚苯乙烯(PS)熔体在气辅共挤口模内的三维黏弹非等温流动过程,对比分析了不同流率下气辅共挤口模所需的最短气辅段长度,同时分析了口模出口面的剪切速率及第一法向应力差的分布情况。结果表明,气辅共挤并不能完全消除挤出胀大,但能极大限度地降低挤出胀大;通过分析流道内的压力、剪切速率及第一法向应力差分布可以确定一个合适的气辅段长度;随着熔体流率的增加,气辅共挤口模所需的最短气辅段长度也相应地增加,但增速并不明显。展开更多
基金supported by the National Natural Science Foundation of China (Nos. 90916023 and 51176075)
文摘The aerodynamic design of a rigid-flexible coupling profile is the decisive factor for the flow-field quality of a supersonic free jet wind tunnel nozzle, and its mechanic dynamic features are the key for engineering implementation of continuous Mach number regulations. To fulfill the requirements of a free jet inlet/engine compatibility test within a wide simulation envelop, both uniform flow-fields of continuous acceleration and deceleration are necessary. In this paper, the aerodynamic design methods of an expansion wall and machinery implementation plan for the halfflexible single jack nozzle were researched. The profile control in nozzle flexible plate design was studied with a rigid-flexible coupling method. Design and calculations were performed with the help of numerical simulation. The technique of axial free stretching of the flexible plate was used to improve the matching performance between the designed elasticity profile and the theoretical one, and the rigid-flexible coupling structure was calibrated by wind tunnel tests. Results indicate that the flexible plate aerodynamic design method used here is effective and feasible. Via rigidflexible coupling design, the flexible plate agrees with the rigid body very well, and continuous Mach number changes can be achieved during the tests. The nozzle’s exit flow-field uniformity meets the requirements of China Military Standard(GJB).
基金financial support from the National Key Technology R&D Program in the 12th Five Year Plan of PetroChina (No: 2011ZX05010-003-02)the National Key Technology R&D Program in the 12th Five Year Plan of CNOOC (No: 2011ZX05024-04-05-03)
文摘Performance characteristics of partially hydrolyzed polyacrylamide （HPAM） and cross- linked polymer （CLP, Cr^3＋ as the cross linker） solutions have been investigated. A Brookfield viscometer, rheometer, dynamic light scattering system, and core flow device have been used to measure the viscosity, viscoelasticity, polymer coil dimensions, molecular configuration, flow characteristics, and profile modification. The results show that, under conditions of high salinity and low HPAM and Cr^3＋ concentrations, cross-linking mainly occurred between different chains of the same HPAM molecule in the presence of Cr^3＋, and a cross-linked polymer （CLP） system with a local network structure was formed. Compared with an HPAM solution of the same concentration, the apparent viscosity of the CLP solution increased slightly or remained almost unchanged, but its viscoelasticity （namely storage modulus, loss modulus, and first normal stress difference） increased, and the resistance coefficient and residual resistance coefficient increased significantly. This indicates that the CLP solution exhibits a strong capability to divert the sequentially injected polymer flood from high-permeability zones to low- permeability zones in a reservoir. Under the same HPAM concentration conditions, the dimensions of polymer coils in the CLP solution increased slightly compared with the dimensions of polymer coils in HPAM solution, which were smaller than the rock pores, indicating that the cross-linked polymer solution was well adapted to reservoir rocks. Core flood experiments show that at the same cost of reagent, the oil recovery by CLP injection （HPAM-1, Cr^3＋ as the cross linker） is 3.1% to 5.2% higher than that by HPAM- 2 injection.
基金Project(U1664252) supported by the National Natural Science Foundation of ChinaProjects(31665004,31715011) supported by the Open Fund of State Key Laboratory of Advanced Design and Manufacture for Vehicle Body,China
文摘To solve the defects of bottom concave appearing in the extrusion experiments of complex hollow aluminium profiles,a 3D finite element model for simulating steady-state porthole die extrusion process was established based on HyperXtrude software using Arbitrary Lagrangian–Eulerian(ALE)algorithm.The velocity distribution on the cross-section of the extrudate at the die exit and pressure distribution at different heights in the welding chamber were quantitatively analyzed.To obtain an uniformity of metal flow velocity at the die exit,the porthole die structure was optimized by adding baffle plates.After optimization,maximum displacement in the Y direction at the bottom of profile decreases from 1.1 to 0.15 mm,and the concave defects are remarkably improved.The research method provides an effective guidance for improving extrusion defects and optimizing the metal flow of complex hollow aluminium profiles during porthole die extrusion.
文摘以L型双层共挤异型材为研究对象,采用Phan-Thien and Tanner(PTT)本构方程,应用Arrhenius方程来描述温度对黏度的影响,通过有限元方法分析了聚丙烯(PP)/聚苯乙烯(PS)熔体在气辅共挤口模内的三维黏弹非等温流动过程,对比分析了不同流率下气辅共挤口模所需的最短气辅段长度,同时分析了口模出口面的剪切速率及第一法向应力差的分布情况。结果表明,气辅共挤并不能完全消除挤出胀大,但能极大限度地降低挤出胀大;通过分析流道内的压力、剪切速率及第一法向应力差分布可以确定一个合适的气辅段长度;随着熔体流率的增加,气辅共挤口模所需的最短气辅段长度也相应地增加,但增速并不明显。
