Dynamic responses and damages of water-filled pre-pressurized metal tube impacted by mass

An account is given of some principal observations made from a series of experiments in which three-span pipe beams were subjected to central impact by indenters with different nose shapes. These pipes were filled and pre-pressurized with water in order to identify the main effects produced by the fluid–structure interaction. In comparison, the impact experiments of the pipes with no water were also carried out. The perforation failure modes and corresponding critical impact energies were obtained in different test conditions. The experimental results indicated that the critical perforation energy and the deformation of the wall of the pipe were significantly influenced by the presence of the water and the pressure.     

Efficient modeling of panel-like structures in perforation simulations

This paper presents results of numerical simulations for impact effects in panel-like structures using solid and shell element modeling techniques. Three examples from experiments in literature have been numerically analyzed. The nonlinear transient dynamic analysis code, LS-DYNA is used in the simulations to model projectiles and panel-like targets. It is found that models established for panel-like targets using solid shell elements cannot only save significant computational effort, but also produce good results as long as the panel-like targets satisfy certain conditions. A criterion that governs the validity of modeling panel-like targets with shell elements is proposed in the paper.     

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水力压裂几乎都是在套管井中进行的，射孔参数必然要影响到压裂施工参数设计，甚至影响到压裂效果。章将套管和岩石视为具有不同性能的两种材料，应用引进的CAD／CAE／CAM Pro/E有限元软件在SGI工作站上计算得到了射孔孔眼周围的应力分布，根据主应力方位可以确定压裂裂缝方位，结合岩石破裂准则可以得到水力压裂施工破裂压力。为优化射孔参数和设计压裂施工压力提供了分析方法。     

Influences of perforation ratio in characteristics of capacitive micromachined ultrasonic transducers in air

Capacitive micromachined ultrasonic transducers (CMUTs) with a perforated membrane have been fabricated and characterized in air. Two types of CMUT device have been fabricated having perforation ratio (area ratio of holes = AR) of 10% and 20%, and analyzed about electrical and mechanical characteristics. The perforation ratio (AR) of membrane substantially influences on the electrostatic force and mechanical restoring force of the device since it leads to the area variation of electrode and membrane, it subsequently influences on the sensitivity and frequency response of the CMUT device. The electrostatic force and mechanical restoring force were improved by decreasing the AR and increasing the DC bias voltage. The open-circuit sensitivity of a CMUT having AR 10% membrane, 8.45 μV/Pa, is larger than that of AR 20%, 4.07 μV/Pa at DC 15 V. Furthermore, the resonance behaviors were observed in the range of 60-80 kHz, and the resonance frequency could be changed by varying the applied DC voltage and AR.     

水平井复射高效增产的启示——以广64平4井为例

水平井是老油田开发后期挖潜剩余油的重要技术手段,但部分水平井经过一段时间的生产后,产能大幅下降且措施调整难度大,效果不明显。针对常规措施无效的水平井,二次射孔作业往往能收到较好的增产效果。     

Experimental study of perforation and cracking of water-filled aluminum tubes impacted by steel spheres

Water-filled aluminum tubes were subjected to impact by six steel spherical projectiles of different diameters at impact velocities of 40–200 m/s. The effects of the diameter of the steel projectiles and of the material properties of the tubes on cracking and perforation were discussed. Water decreased the wall strength of the aluminum alloy tubes, and the impact velocity at which a steel projectile first passes through the tube wall decreased with increasing diameter of the steel projectile. Using the velocity at which the steel projectile perforates the tube wall, empirical equations of the energies required to perforate the tube wall were derived. Also, the energy balance in the steel projectile during a collision is discussed referring to the pressure history in the filled water and the velocities of the steel projectile before and after collision.     

离心机转鼓强度计算规范中开孔系数的讨论

运用有限元分析软件ANSYS,对开孔后的离心机转鼓进行应力模拟计算,并与JB/T 8051-1996《离心机转鼓强度计算规范》得到的结果进行了对比分析。结果表明,规范中开孔系数的选取对转鼓应力的计算会带来一定的偏差,需要进一步的修正。     

Recent ICRF coupling experiments on EAST

Recent ion cyclotron resonance frequency(ICRF) coupling experiments for optimizing ICRF heating in high power discharge were performed on EAST. The coupling experiments were focus on antenna phasing and gas puffing, which were performed separately on two ports of the ion cyclotron resonance heating(ICRH) system of EAST. The antenna phasing was performed on the I-port antenna, which consists of four toroidally spaced radiating straps operating in multiple phasing cases; the coupling performance was better under low wave number ∣k_‖∣(ranging from 4.5 to 6.5). By fuelling the plasma from gas injectors, placed as uniformly spaced array from top to bottom at each side limiter of the B-port antenna, which works in dipole phasing, the coupling resistance of the B-port antenna increased obviously.Furthermore, the coupling resistance of the I-port antenna was insensitive to a smaller rate of gas puffing but when the gas injection rate was more than a certain value(1021 s~(-1)), a sharp increase in the coupling resistance of the I-port antenna occurred, which was mainly caused by the toroidal asymmetric boundary density arising from gas puffing. A more specific analysis is given in the paper.     

普光高酸性气田投产测试关键技术综述

在普光高酸性气田产能建设的过程中,气井的投产测试是一个非常关键的阶段。这个阶段的关键技术主要有高含硫气井入井液技术、完井管柱配套技术、长井段射孔工艺技术、长井段大规模酸压技术、合金油管作业技术、作业随钻录井技术、长时间试气测试技术。普光气田的投产实践证明只有这些关键技术的成功应用,才能确保高酸性气田投产测试的顺利实施,才能为高酸性气田的产能建设打下了坚实的技术基础。