Modeling air gun signatures in marine seismic exploration considering multiple physical factors

Based on analyzing the limit of Ziolkowski＇s bubble oscillation formulation,a new model with various physical factors is established to simulate air gun signatures fo marine seismic exploration.The practical effects of physical factors,such as heat transfe across the bubble wall,air gun port throttling,vertical rise of the bubble,fluid viscosity,and the existence of the air gun body were all taken into account in the new model.Compared with Ziolkowski＇s model,the signatures simulated by the new model,with small peak amplitude and rapid decay of bubble oscillation,are more consistent with actual signatures The experiment analysis indicates：（1）gun port throttling controls the peak amplitude of ai gun pulse;（2）since the hydrostatic pressure decreases when the bubble rises,the bubble oscillation period changes;（3）heat transfer and fluid viscosity are the main factors tha explain the bubble oscillation damping.

梳理机后部工艺技术结构的创新

为了实现精细梳理,提高梳棉的匀整精度和幅度,介绍梳理机后部喂棉梳理的工艺、结构以及棉层厚度检测技术的现状;分析棉纺梳理机及非织造梳理机在喂入棉层握持、纤维梳理和棉层厚度检测方面存在的不足,提出“薄喂快进”、精细梳理、均衡握持和精确检测的后部喂棉梳理工艺优化方案;创新设计出采用气囊式加压喂棉棉层细分段握持、棉层线密度液流传导检测技术以及梳理机后部喂入预牵伸工艺技术结构。指出:气加压喂棉层细分段握持与液流传导检测棉层厚度技术,可以更有效地握持超薄喂棉棉层、更精细地梳理小定量棉层、更精确地检测喂棉棉层的横向平均厚度;预牵伸工艺配合细分段握持技术为改善纤维取向度、实施“薄喂快进”及精细梳理工艺创造条件,为纤网、生条品质及后续工艺配置和成品质量的更优化创造软硬件条件。

Heat transfer and friction factor of Therminol liquid phase heat transfer fluid in a ribbed tube

Experiments and simulations on flow and heat transfer behavior of Therminol-55 liquid phase heat transfer fluid have been conducted in a ribbed tube with the outer diameter and inner diameter 25.0 and 20.0 mm,pitch and rib height of 4.5 and 1.0 mm.respectively.Experimental results show that the heat transfer and thermal performance of Therminol-55 liquid phase heat transfer fluid in the ribbed tube are considerably improved compared to those of the smooth tube.The Nusselt number increase with the increase of Reynolds number.The increase in heat transfer rate of the ribbed tube has a mean value of 2.24 times.Also,the pressure drop results reveal that the average friction factor of the ribbed tube is in a range of 2.4 and 2.8 times over the smooth tube.Numerical simulations of three-dimensional flow behavior of Therminol-55 liquid phase heat transfer fluid are carried out using three different turbulence models in the ribbed tube.The numerical results show that the heat transfer of ribbed tube is improved because vortices are generated behind ribs,which produce some disruptions to fluid flow and enhance heat transfer compared with smooth tube.The numerical results prove that the ribbed tube can improve heat transfer and fluid flow performances of Therminol liquid phase heat transfer fluid.

Study on Characteristics of Steady Flow Condensation Heat Transfer in a Tube under Zero－Gravitation

In this paper, the annular flow. model for in tube completed condensation is employed to predict the steady flow condensation heat transfer characteristics in a tube under zero-gravitation. In this easel it is proposed that vapor condenses on the liquid film surface. Due to the effect of surface tension, the liquid exists in the form of liquid film ring contacting wall; when the velocity of vapor core decreases to zerol the condensation process ends. Putting forward the physical and mathematical models, the problem is solved and the multi-order equation of the thickness of liquid film is obtained, which includes terms of the pressure gradient along axial direction, the friction force between vapor and liquid on interface. By computational calculation, this model can be used not only to predict the thickness of liquid film, the condensation pressure gradient along the axial direction, but also to determine the Nusselt number, the condensation length and the total flow pressure drop of condensation etc. At the end, the calculation results of the necessary condensation length are compared approximately with those from the experiments, which are obtained on the test set-up placed horizontally in gravitation field, and the deviation is analyzed.

An Investigation of the Swirling Flow and Heat Transfer in a Duct

This paper presents the results of experiments and numerical simulation of the turbulent swirling flow and heat transfer in a duct.The calculated results are in good agreement with data obtained by measurements.It is found that the swirling flow promotes heat transfer to the wall of the duct;the swirl numbers are dependent upon the vane exit angles of the swirler,distance from the swirler and the duct Reynolds number.But the decay of swirling flow in streamwise direction is related to local Reynolds numbers and is independent of the swirler exit angle.The swirl flow characteristics presented in this paper may be used for engineering purposes.

Fluorinated poly(fluorenyl ether)s with linear multi-cationic side chains for vanadium redox flow batteries

The cationic group distribution along the polymeric backbones of anion exchange membranes(AEMs)has significant influence on their microscopic morphology and anion conductivity.To develop high-performance AEMs for vanadium redox flow batteries(VRFBs),a series of poly(fluorenyl ether)samples bearing di-and tri-quaternary ammonium side chains with similar ion exchange capacities(IECs)were synthesized by grafting cationic alkyl chains with tertiary amine-containing poly(fluorenyl ether)precursors.The experimental results indicate that the introduction of the multi-cationic side chains facilitates the formation of micro-phase-separated morphologies and enhances anion conductivity.Moreover,the number of spacer atoms between the quaternary ammonium groups on the side chains affects the water uptake of the membranes,thus complicating the relationship between the density of cationic group distribution and anion conductivity.The poly(fluorenyl ether)s with dicationic side chains and six spacing atoms(DQA-PFE-C6)showed the highest anion conductivity.A VRFB assembled with DQA-PFE-C6 exhibited a maximum power density of 239.80 mW cm^−2 at 250 mA cm^−2,which is significantly higher than a VRFB assembled with Nafion 212.Therefore,side chain engineering is an effective chemical approach to enhance the properties of AEMs for VRFB applications.