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131.
A numerical simulation of gas flow during coal/gas outbursts 总被引:2,自引:0,他引:2
Summary A model of the gas flow in airways during an instantaneous outburst of coal and gas is formulated and solved numerically using MacCormack's explicit finite-difference scheme. This model is based on the assumption that geological structures, in-situ stresses and high-gas-pressure gradients play important roles in initiating an outburst, with the gas content and gas-pressure gradients being the most dominant factors. The fluid-dynamic processes that occur after an outburst are computed by the numerical integration of the complete time-dependent Navier-Stokes equations. The mixture velocity, the density and the gas-concentration profiles in both time and space domains (immediately after an outburst) are presented. The global results are useful in gaining an improved understanding of gas-flow patterns during coal/gas outbursts and in determining the range of the disturbance so that effective methods of control can be developed.Nomenclature
a
speed of sound
-
C
gas concentration (mass)
-
C
v
specific heat at constant volume
-
C
p
specific heat at constant pressure
- CFL
Courant-Friedrichs-Lewy number
-
E
total energy of the mixture
-
F
the vector defined in Equation 27
-
G
the vector defined in Equation 28
-
h
entropy
-
h
i
entropy at inlet
-
J
xi
diffusion flux in the i-direction
-
k
thermal conductivity of a gas
-
M
Mach number
-
P
pressure of a mixture (the partial pressure of gas)
-
P
gas pressure
-
P
a
atmospheric pressure 相似文献
132.
Using the operational model(B model)of Beijing Meteorological Center,we do some of numerical experi-ments of crossing and rounding mountains in all velocity adjustment scheme,and study dynamic effect ofQinghai-Xizang Plateau and Rocky Mountains on lee cyclones.The results show that due to air flow roundthe Qinghai-Xizang Plateau,divergence is distributed in the shape of confluence which matches cyclogenesisarea and cyclonic track in East Asia.In the downstream of the Qinghai-Xizang Plateau,convergence inthe upper troposphere restrains cyclone development in the east of China mainland.In North America,air flow primarily crosses over Rocky Mountains.Air is adiabatically cooled when it flows upward in thewest flank of Rocky Mountains,while air is warmed when it flows downward in the lee side.The fact isimportant for the lee cyclogenesis and the lee frontogenesis of Rocky Mountains.Air flow crossing over RockyMountains is also the main cause for forming dryline in the mid-west of United States. 相似文献
133.
我国大气污染物远距离传输的估计——Ⅰ:轨迹分析 总被引:4,自引:1,他引:4
根据1979年1,4,7和10月的1500m高度的测风资料,利用二维流场,计算了通过北京、西安、兰州等10个城市空气块的轨迹。依据轨迹及其终点的分布讨论了不同季节对上述这些城市有影响的污染物的来向及以这些城市为源地的污染物的远距离输送问题。 相似文献
134.
山西寿阳—阳泉地区石炭—二叠系沉积环境及其沉积特征 总被引:1,自引:0,他引:1
本区石炭—二叠系是在海湾背景下发育的一套由滨海平原—三角洲平原—冲积平原沉积组成的海退层系。主要沉积环境是三角洲平原,其上部为冲积平原包括网状河和辫状河;下部为海湾(或分支间湾)、潮下碳酸盐岩、潮间介壳滩、碎屑岩潮坪及滨海沼泽湿地等。三角洲为河控浅水三角洲。上述沉积环境,随海水退却在时空上具明显的规律性变化。 相似文献
135.
136.
137.
Sheng Jifu Zhang Dequan Li YanInstitute of Mineral Deposits Chinese Academy of Geological Sciences Beijing Jiang M inxi 《《地质学报》英文版》1995,69(3):289-302
Physicochemical parameters of mineralization such as temperature, pressure, salinity, density, composition and boiling of ore fluids as well as pH, Eh, fo2 and reducing parameter in theprocess of mineralization of major ore deposits in the study district have been obtained by the authors through systematic observation and determination of characteristics and phase changes of fluid inclusions at different temperatures and analysis of gaseous and liquid phase compositions of the inclusions, thus providing a scientific basis for the division of mineralization-alteration stages, types of mineral deposits and minerogenetic series and the deepening of the knowledge about the ore-forming processes and mechanisms of mineral deposits. It is indicated that the deposits of the same type have similar fluid inclusion geochemical features and physicochemical parameters though they belong to different minerogenetic series, while the compositions of inclusions are not conditioned by deposit types but closely related to 相似文献
138.
综合排序法是处理n个待确定次序的对象,当对出k种方案时,作出合理排序的方法。本文介绍了秩的自然数编码法,算术平均综合排序法,地质加权综合排序法,不肯定结果的处理法,积矩阵的总秩和检验法等。这些都是名义型数据向有序型数据变换的方法,其中地质加权综合排序法最具实用意义。最后列举了应用实例。 相似文献
139.
从更广泛和较高的层次对地质时期地球表层的生命活动和环境变化进行多学科的综合性研究,在全球系统分析的基础上为“协调人类与自然关系”的战略主题提供决策依据。以高分辨率地层学框架的研究的基础,综合多种学科对事件、间事件及其载体和介质的定量研究,为生物与环境的耦合机制的认识及有关模式的建立提供科学依据。化石燃料作为事件产物,其分布规律亦为重要研究内容之一。 相似文献
140.
Jian Sheng 《Climate Dynamics》1995,12(2):125-140
The Madden-Julian oscillation (MJO) simulated by the Canadian Climate Centre general circulation model (CCC GCM) is identified
by a principal oscillation pattern (POP) analysis and compared with that observed in the real atmosphere. The results are
based upon two integrations of the CCC GCM, one with a parameterization of penetrative cumulus convection (EXP1) and the other
with a moist convective adjustment scheme (EXP2). The signal of MJO can be detected in both integrations as the first POP
of the 200 hPa velocity potential along the equator. The disturbances show a distinctive wave number one structure with the
strongest local amplitude found in the longitudes corresponding to the region of the Asian monsoon. The phase speed of the
eastward wave propagation is higher in the eastern Pacific and lower in the monsoon region where the convective activities
are strongest. These features are in good agreement with the observations. The energy spectrum of the velocity potential peaks
at the frequency corresponding to a period of about 38 days for EXP1, which is somewhat shorter compared to the observed periods
of 40–50 days. On the other hand, two spectral peaks can be clearly identified for EXP2, one with a period of 24 days and
the other with a much longer period, somewhere near 112 days. Both peaks appear statistically significant at 95% level. Long
term data of the observed atmosphere show little indication of such spectral separation. The horizontal patterns identified
by the POP analysis resemble to some extent the baroclinic response of tropical flow to a heat source travelling with the
speed of MJO. At the upper level, Rossby wave energy propagates westward with winds generally following the height contours,
whereas Kelvin wave energy propagates to the east from the heat source with strong cross-contour flow near the equator. At
the lower level, the patterns are essentially reversed. The model-generated precipitation and diabatic heating are examined
by compositing against the moving MJO. It is found in EXP2 that the composite heating distribution is coherent with the flow
pattern only in a certain sector of the equator, depending on whether the fast or slow mode is used to determine the reference
point. The composite vertical heating profile of a slower mode tends to have a maximum found at a lower level. The sensitivity
of simulated MJO to the cumulus convection scheme in the model is discussed.
Received: 19 December 1994 / Accepted: 11 July 1995 相似文献