摘要：During oil-gas well drilling and completion, downhole tools and apparatus should be conveyed to the destination to complete a series of downhole works. Downhole tractors have been used to convey tools in complex wellbores, however a very large tractive force is needed to carry more downhole tools to accomplish works with high efficiency. A novel serial active helical drive downhole tractor which has significantly improved performance compared with previous work is proposed. All previously reported helical drive downhole tractors need stators to balance the torque generated by the rotator. By contrast, the proposed serial downhole tractor does not need a stator; several rotator-driven units should only be connected to one another to achieve a tractive force multifold higher than that was previously reported. As a result, the length of a single unit is shortened, and the motion flexibility of the downhole tractor is increased. The major performance indicators, namely, gear ratio, velocity, and tractive force, are analyzed. Experimental results show that the maximum tractive force of a single-unit prototype with a length of 900 mm is 165.3 kg or 1620 N. The analysis and experimental results show that the proposed design has considerable potential for downhole works.

摘要：The ultra-low specific speed centrifugal blower is widely used in energy industries due to its features such as low flow rate,high pressure and low manufacturing cost. However,the width-to-diameter ratio of the above blower becomes relatively small to satisfy the needed operation condition and its performances are considerably degraded as a result of relatively high leakage,disc friction and passage friction loss consequently. The purpose of this paper is to improve its performance through the optimization design of the blade’s profile properly. Based on artificial neural networks (ANN) and hierarchical fair competition genetic algorithms with dynamic niche (HFCDN-GAs),the optimization design approach is established. By conjoining Bezier parameterization and FINE/TURBO solver,the optimized blade is designed by adjusting the profile gradually. An industrial ultra-low specific speed centrifugal blower with parallel hub and shroud has been selected as a reference case for optimization design. The performance investigations of the centrifugal blowers with different types of blades are conducted. The conclusions of the performance improvement of the optimized blade provide positive evidences in the application of the optimization design of the above blower blade.

摘要：Due to the fact that the turbine outlet temperature of aeroderivative three-shaft gas turbine is low,the conventional combined cycle is not suitable for three-shaft gas ***,the humid air turbine(HAT)cycle provides a new choice for aeroderivative gas turbine because the humidification process does not require high *** HAT cycle plants are all based on single-shaft gas turbines due to their simple structures,therefore converting aeroderivative three-shaft gas turbine into HAT cycle still lacks sufficient *** paper proposes a HAT cycle model on a basis of an aeroderivative three-shaft gas *** HAT cycle modelling of saturator,gas turbine and heat exchanger are carried out based on the modular modeling *** models are verified by simulations on the aeroderivative three-shaft gas *** results show that the studied gas turbine with original size and characteristics could not reach the original turbine inlet temperature because of the introduction of ***,the efficiency still increases by 0.16%when the HAT cycle runs at the designed power of the simple ***,simulations considering turbine modifications show that the efficiency could be significantly *** results obtained in the paper can provide reference for design and analysis of HAT cycle based on multi-shaft gas turbine especially the aeroderivative gas turbine.

摘要：Saturator is one of the core components of humid air turbine （HAT） and is the main feature of HAT making it different from other gas turbine cycles. Due to the lack of sufficient experience in commercial plant operation, HAT cycle has a great demand for modeling and simulation of the system and its components, especially the saturator, to provide reference for system design and optimization. The conventional saturator models are usually based on the theory of heat and mass transfer, which need two accurate coefficients to ensure convincing results. This work proposes a global heat and mass transfer coefficient based on cooling tower technology to model the saturator in small-scale HAT cycle. Compared with the experimental data, the simulation results show that the proposed model well predicts the dynamic humidity and temperature distribution characteristics of saturator at low air pressure and temperature.

摘要：蒲公英种子的良好飞行能力归功于其冠毛结构特征.以往研究主要集中于风从蒲公英种子的冠毛结构底部通过至顶部(简称为“一型风”)时,空气流动与种子的相互作用.然而,由于大气流和种子结构特征的多样性,蒲公英种子从花序头部脱落或空中飞行过程中,风从蒲公英冠毛结构顶部通过至底部(简称为“二型风”)的情况也很常见.但是,目前尚缺乏二型风情况下空气流动与种子相互作用的相关研究.本文中,我们通过数值模拟,考虑风速、冠毛结构角度和孔隙率的变化,研究和比较了在两种风型下冠毛结构模型的拖曳力系数和周围流场分布特征。结果表明:由于风向的反转,流场分布特征和拖曳力系数会发生显著变化.当风从第一型转为第二型时,冠毛丝对气流的干扰从背风侧移前至迎风侧,导致在第二型风时涡环大多数情况下附着在非扁平冠毛结构模型的中心圆盘上,而在第一型风时则发生涡环分离。当风从第一型变为第二型时,压力诱导的拖曳力对总拖曳力的贡献显著增加,从而增强了非扁平冠毛结构模型的拖曳力系数.然而,随着风速、冠毛结构角度和孔隙率的增加,这种增强作用会逐渐减弱.这些发现将有助于种子风驱扩散的定量预测,并为微型仿生飞行器的设计提供一定指导.

摘要：Carbonate-based electrolytes still retain their top preference in sodium-ion battery(SIB)as in lithium-ion battery(LIBs)owing to their cost-effectiveness and ***,extensive studies have consistently demonstrated a mismatch between the hard carbon(HC)anode and carbonate-based electrolytes[1,2].Specifically,as for lowconcentration carbonate-based electrolytes(LCEs).