南海北部Site 3A站位沉积物地球化学特征及其对甲烷渗漏的指示*

南海北部陆坡具有较好的水合物成藏潜力,而甲烷渗漏区的地球化学特征和沉积环境以及自生矿物的关系对天然气水合物的勘探和开采有重要指示意义。选取南海北部陆坡Site 3A站位柱状沉积物作为研究对象,通过对其主微量元素、五种形态的磷、不同形态的铁、铬还原硫（CRS）、硫同位素以及有机碳值等数据进行地球化学特征分析。结果表明,南海北部Site 3A站位柱状沉积物主要以200 cmbsf深度作为分界线,分成以有机质硫酸盐还原作用为主的上部和以甲烷厌氧氧化（AOM）作用为主的下部,对比上部,下部可指示黄铁矿含量的CRS含量增加,说明该站位存在AOM作用,200 cmbsf深度以下为硫酸盐-甲烷过渡带（SMTZ）。δCe在200 cmbsf深度以下呈现先增大后减小的趋势,说明200 cmbsf深度以下为偏碱性的还原环境。沉积物中的锰、自生磷灰石态磷（P_CFA）、铁结合磷（P_Fe）、可还原性铁（Fe_ox）、磁铁矿铁（Fe_mag）和碳酸盐铁（Fe_cab）的含量变化均受到了AOM作用的影响,下部沉积物中指示富镁方解石含量的Mg/Ca值较高,指示文石含量的Sr/Ca值无明显变化;同时,δ³⁴S并未出现明显的正偏现象,而200 cmbsf深度以下CRS和总硫（TS）的含量只是略有增加,说明该地区主要以低渗漏或甲烷扩散为主。     

Simulation,Experiment, and Optimization Method for Thermal Characteristics of Machine Tool

The thermal characteristic of a spindle system is simulated by the finite element method. Temperature field and thermal deformation of the spindle system were simulated considering the establishment method of an entity model as well as boundary conditions of a finite element model, such as heat source, heat transfer coefficient, and thermal contact resistance between joints. Effects of the spindle system on thermal characteristics of the whole machine were discussed. Accuracy of the simulation was verified and compared with test results. The study shows that the key areas of temperature rise are located at the spindle bearing and spindle motor; thermal deformations of Y and Z directions are large; thermal characteristics of the spindle system have little influence on other parts. Thermal characteristics of the spindle system were optimized by changing the structures and sizes of the cooling passage located at the spindle box, and effectiveness of the optimization was verified by finite element simulation. The research results provide guidance for thermal characteristic simulation and optimization of machining centers.     

南海北部天然气水合物沉积环境中自生矿物特征

南海北部陆坡发育的自生岩石矿物主要有碳酸盐岩、黄铁矿、石膏等,主要分布在天然气水合物最有潜力的区域,如西沙海槽、神狐海域、东沙西南和东北海域,以东沙东北部海域为自生矿物发育最密集区域。自生碳酸盐岩主要呈结核状、结壳状、烟囱状、块状等产出,神狐海域和东沙西南海域以白云石为主,西沙海槽以文石为主,东沙东北部主要以高镁方解石为主,具有较轻的碳同位素值和较重的氧同位素值;自生黄铁矿主要呈长条状,由草莓状黄铁矿组成,具有较大的硫同位素值,分布较为广泛;自生石膏主要呈球状或者块状,透明自形晶结构,分布在神狐及东沙海域部分站位。南海北部自生矿物的这些特点可为我国水合物勘探提供自生矿物方面的证据。     

Stress Analysis of a Borehole in Saturated Rocks Under in situ Mechanical,Hydrological and Thermal Interactions

Abstract

A novel approach is developed to represent coupled thermal-hydraulic-mechanical (THM) behavior of porous systems that incorporates the non-isothermal free and forced convection of a single component fluid in a non-boiling thermoelastic medium. The three-way simultaneous coupling between the THM triplet is currently linear, but no restriction is placed on incorporating material nonlinearities. The coupled PDEs are solved in space by grid-adaptive finite elements. The model is validated against solutions for linear non-isothermal consolidation of a column. We demonstrate the utility of the model by analyzing the behavior of a deep wellbore in a themoelastic medium circulated by a pressurized, but chilled fluid. Model results illustrate the significant importance of the cross-couplings between individual THM processes for the evaluation of wellbore stability.     

新型环形喷动床的喷动机制与喷动特性

在传统喷动床的基础上,设计出一种多喷口环形喷动形式的新型喷动床.实验研究了喷口型式、喷口速度、颗粒类型对这种喷动床床内密相喷动流化区高度、可喷动静止床层高度及床层压降等参数的影响情况.结果表明:颗粒在床内的喷动形式沿床高方向呈现独特分区现象;随着喷口速度的增加,密相喷动高度和可喷动静止床层高度也相应增加;在同样的静止床层高度的情况下,直向型式的喷口更易形成喷动,床层的最小喷动速度几乎与静止床层高度呈线性关系;当床内形成较稳定的喷动后,床层压降随喷口速度的变化不明显,可视为常数.     

Thermal Characteristics of Paraffin Wax for Solar Energy Storage

A thermal energy storage medium must meet the requirements of a stable storage material with high heat capacity. Heat storage based on the sensible heating of media such as water, rock, and earth represents the first generation of solar energy storage subsystems and technology for their utilization is well developed. However, recently the heat storage based on the latent heat associated with a change in phase of a material offers many advantages over sensible heat storage. The most important characteristic of such a subsystem is its sufficient storage capacity. The PCM (phase change material) behavior is visualized by constructing an idealized model thermal capacitor subjected to simulated solar system environmental conditions which include thermal cycling utilizing the latent heat of paraffin for heating and cooling. The proposed model of the capacitor is of a flat plate geometry consisting of two panel compartments forming the body of the capacitor containing the paraffin, leaving at their inner surfaces a thin passage allowing the water flow. The whole structure is assumed to be insulated to minimize heat loss. Analysis solution is used to generate data about the temperature distribution, the melt thickness, and the heat stored in the PCM under two conditions of: (a) constant mass flow rate tests for various water inlet temperatures, and (b) constant water inlet temperature for various mass flow rates. A FORTRAN computer program is constructed to perform the analysis. It is found that water outlet temperature increases with time until it becomes nearly equal to the inlet temperature. Increasing the mass flow rate for a given inlet temperature, decreases the time required for outlet temperature to reach a given value. Increasing inlet temperature for a given mass flow rate gives a very rapid decrease in the time required for the outlet water temperature to reach a given value. Instantaneous rate of heat storage is determined from the inlet-to-exit temperature differential and measured flow rate. This rate is then integrated numerically to determine the cumulative total energy stored as a function of time. It is found that the instantaneous rate of heat storage decreases till reaching a nearly constant value. The total or cumulative heat storage as a function of time, showed a nearly linear trend in the mid-range time, and it increased with increasing inlet temperature.     

热辐射下常用木材热解的动力学与燃烧特性

在热重分析仪上进行了空气气氛、不同升温速率下几种木材的热解动力学过程的研究.对不同升温速率以及木材种类对失重过程的DTG曲线的影响进行了深入分析,在热重实验的基础上建立了"双组分两阶段反应"模型来描述空气气氛下木材的热解动力学过程,并利用C-R方法求得了对应失重阶段的动力学参数.在火灾早期特性实验台上进行了4种木材在空气气氛、不同辐射热流下的热解与燃烧过程的特性研究,通过对高、低热流下几种木材表面温度变化、失重率以及着火时间等参数的对比,发现在较高热流下,固定碳含量相似的几种木材的反应机理及其表观热行为趋于一致.     

柴油机排气加热燃烧器热力特性数值模拟

针对柴油机微粒捕集器的热再生,设计了一套排气加热燃烧器,采用κ-ε湍流双方程模型、PDF燃烧模型对其燃烧过程进行数值模拟.结果表明,配风比例对燃烧过程影响较大,增大一、二次风比例导致点火困难,燃烧不稳定;喷射锥角、喷射压力和喷射位置对燃烧过程的影响次之,存在一个中间优化喷射锥角,当喷射压力达到一定值后,燃烧过程基本保持稳定.在发动机试验台架上对部分模拟结果进行了试验验证,结果表明模拟结果与试验结果基本一致.     

涡轮增压柴油机高排气背压下变工况性能的研究

本文提出了潜艇废气涡轮增压柴油机工作性能的计算方法和程序。在理论上,模拟研究了废气涡轮增压柴油机在高背压下变工况的性能。