目的 构建快速预测系统,提高场区尺度核事故后果评价计算精度和效率.方法 开展场区尺度范围内复杂下垫面周围风场和污染物扩散的快速预测方法研究,采用风场诊断模型和拉格朗日粒子扩散方法,以显式分辨建筑物和植被分布的方式,建立场区尺度快速预测系统;通过数值模拟理想和真实城市场区算例,并与风洞实验测量数据和计算流体力学数值结果进行比较,研究复杂下垫面对局地风场和污染物输运的影响.结果 快速预测系统能在约5 min时间内清晰的模拟出局地高分辨率风场以及污染物浓度分布信息,建立与地理信息软件的接口,并可以实现与中尺度气象预报模式的耦合;从计算准确性上看,系统对风场模拟效果良好,风速和风向的分数偏差分别为0.33和-0.08,模拟的浓度场的范围受风场影响较大,除个别低浓度点外,模拟和观测的浓度比值在0.05～3.40之间.结论 快速预测系统可以在保证计算精度的基础上,有效模拟出流场分布特征,提高计算效率,为核事故应急响应提供重要参考和依据.

The Weather Research and Forecasting (WRF) model with urban canopy model has been widely used to study atmospheric boundary layer processes and urbanization-related environmental issues. One of the most daunting challenges faced by the integrated WRF/urban modelling system is constraining the uncertainties in urban canopy parameters (UCPs) that represent the urban morphological characteristics. In this paper, we develop a dataset of three-dimensional (3-D) UCPs for Beijing by using vector-format building information in a Geographic Information System (GIS) environment and apply it to the integrated WRF/urban modelling system to investigate the effects of UCPs on the simulated meteorological variables against observations in clear-sky days. Moreover, the role of spatially-varying UCPs involved in the Building Effect Parameterization (BEP) in capturing the heterogeneous characteristics of 2-m surface air temperature and 10-m wind field in the urban areas are evaluated. In general, high-resolution dataset of UCPs improves the model skill in simulating the diurnal variations and spatial distributions of 2-m surface air temperature and 10-m wind speed in the urban canopy, especially for the BEP. WRF/BEP with gridded UCPs dataset shows a better performance in densely built-up areas, where the morphological and physical characteristics of urban surface are complex. It also performs better in capturing the characteristics of urban heat islands (UHIs) and weak wind zones (WWZs) in urban areas. Results show that introducing the 3-D UCPs dataset into the integrated WRF/urban modelling system is a simple and yet efficient way to enhance the modelling capabilities in urban areas and assist urban planners to deal with urban environmental issues.

With the intensification of pollution and urbanization, the aerosol radiation effect continues to play an important role in the urban boundary layer. In this paper, a winter pollution process in Beijing has been taken as an example, and a new aerosol vertical profile in the radiative parameterization scheme within the Weather Forecast Research and Forecasting (WRF) model has been updated to study the effect of aerosols on radiation and the boundary layer. Furthermore, the interactions among aerosols, urbanization, and planetary boundary layer (PBL) meteorology were discussed through a series of numerical experiments. The results show the following: (1) The optimization improves the performance of the model in simulating the distribution features of air temperature, humidity, and wind in Beijing. (2) The aerosols reduce the surface temperature by reducing solar radiation and increasing the temperature in the upper layer by absorbing or backscattering solar radiation. The changes in the PBL temperature lead to more stable atmospheric stratification, reducing the energy transfer from the surface and the height of the boundary layer. (3) With the increase in the aerosol optical depth, the atmospheric stratification most likely becomes stable over rural areas, most likely becomes stable over suburb areas, and has great difficultly becoming stable over urban areas. Aerosol radiative forcing, underlying urban surfaces, and the interaction between them are the main factors that affect the changes in the meteorological elements in the PBL.

近年来, 伴随污染和城市化进程的加剧, 气溶胶辐射效应对城市边界层的影响日益显著. 文章以北京地区一次冬季污染过程为例, 采用中尺度数值预报模式, 在优化辐射方案中气溶胶垂直廓线的基础上验证了模式的有效性, 分析了气溶胶对辐射和边界层的影响过程, 最后通过敏感性试验探究了气溶胶、城市化和气象要素间的相互关系. 结果表明: (1) 优化后的模式可以较好地模拟北京地区温度场、湿度场、风场的分布特征. (2) 气溶胶在大气中通过削减到达地面的入射短波辐射使地表温度降低, 通过对辐射的吸收或后向散射作用, 使高层温度升高, 温度场的变化使层结稳定性增强, 从而减少近地层的能量输送, 使边界层高度下降. (3) 随着气溶胶光学厚度的增加, 乡村地区最易变为稳定层结, 郊区较易变为稳定层结, 城区最难变为稳定层结, 且气溶胶辐射效应、城市下垫面以及二者的共同作用是影响城市边界层气象要素变化的主要原因.

In recent years, the impact of urbanization and air pollution on the radiation budget increased significantly. The radiation and automatic stations data (2013-01 and 2014-01) from the 325 m tower in TAP, the southern suburb observatory, Miyun meteorological tower and Shangdianzi regional atmospheric background station are used. Meanwhile, the visibility data of the southern suburb Observatory are used to distinguish the clear and pollution days. Results show that: (1) Judging from the month average data, incident shortwave radiation of pollution days of all stations are less than clear days, the maximum attenuation is 55. 8 W . m(-2), the maximum attenuation of direct radiation is 161. 1 W . m(-2), the maximum increase of scatter radiation is 72. 2 W . m(-2); the maximum increase of upward and downward long wave radiation is 85. 0 W . m(-2) and 70. 0 W . m(-2), respectively; The attenuation of long wave radiation has relationship with the pollution and temperature; Net radiation pollution days are less than the clear days in the daytime, which is opposite in the night. (2) From the comparison results of all stations, the attenuation of incident radiation in the southern suburbs (13. 2%) is higher than northern urban areas (7. 4%) due to air pollution, which is consistent with the distribution of pollutantsin Beijing-"North and South are two different worlds"; From the urban area to the northern suburban area, the attenuation rate of pollution of the long and short wave radiation gradually decreases. This study provides important observational basis for the research of interaction between air pollution and meteorological conditions.

The governing equations for heat transfer and fluid flow are often formulated in a general form for the simplification of discretization and programming, which has achieved great success in thermal science and engineering. Based on the analysis of the popular general form of governing equations, we found that energy conservation cannot be guaranteed when specific heat capacity is not constant, which may lead to unreliable results. A new concept of generalized density is put forward, based on which a new general form of governing equations is proposed to guarantee energy conservation. A number of calculation examples have been employed to verify validation and feasibility.

Coal reservoir has characteristics of the soft,brittle,easily-made powder,low porosity,low permeability,low pressure saturated layer,which makes the relationship between the productivity of coal bed methane well and the perforation parameters to be very complex.The complex mathematical model to reflect migration of coal bed methane production process and the impact of perforation parameters on the flow is established.Using numerical model compiled software,solution of the mathematical model is completed.By simulating production of coalbed methane well,the influenced law of the perforation parameters (including the hole depth,diameter, pore density,phase angle) to the coal-bed methane production are studied.The difference of it from the conventional gas reservoir is compared and the field trials and analysis are made.

When crude oil pipelines shut down for some reason,a YOYO system can be used between non-accident stations to make crude oil flow in round trips between stations to avoid coagulation accidents.The YOYO system consists of storage tanks and screw pumps respectively set up in two adjacent pumping stations.Its operation process is similar to forward and backward transmission technology,but the purposes are different.Workflow of the YOYO system is detailed,heat transfer mathematical models of its operation process are built and the initial conditions and height differences of forward and backward transmission are discussed.Based on a calculation case of pipe section,the temperature drop law of YOYO system during its running is discussed.The flow safety of oil pipeline with YOYO system is analyzed,and results indicate that the method is a potential safety measures for accidental pipeline.

A mathematical model for oil-gas multiphase transportation of submarine pipeline is established in this paper. Based on two-fluid model, the steady state equations are solved by fourth-order Runge-Kutta method. A number of computational examples are conducted to verify both model and program, showing that this numerical simulation method is an effective way for the steady state issue of submarine oil-gas two-phase mixing transportation.

原油管线一般采用加热方式输油.管线运行一段时期后,管道外防腐绝缘层会逐年老化,影响管线正常运行,因此需要有计划地安排防腐层大修.大修时,热油管线与土壤建立的稳定温度场遭到破坏,为了保证管线安全生产运行,常常需要对管线周围土壤温度场进行测量.以便监测管道内原油温度的变化.在本文中,详细查阅了大量有关热电偶和土壤温度场的资料,掌握了热电偶测温原理及测温方法,并在实践中进行应用.通过查阅前人关于土壤温度场的研究,对管道周围土壤温度的分布情况有了较为深刻的理解和认识,并分析了采用热电偶测温装置测得的土壤、大气温度数据,得到了管道周围土壤温度场分布的一般规律及其影响因素.