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81.
Oil–water two-phase flow experiments were conducted in a 15 m long, 8.28 cm diameter, inclinable steel pipe using mineral oil (density of 830 kg/m3 and viscosity of 7.5 mPa s) and brine (density of 1060 kg/m3 and viscosity of 0.8 mPa s). Steady-state data on flow patterns, two-phase pressure gradient and holdup were obtained over the entire range of flow rates for pipe inclinations of −5°, −2°, −1.5°, 0°, 1°, 2° and 5°. The characterization of flow patterns and identification of their boundaries was achieved via observation of recorded movies and by analysis of the relative deviation from the homogeneous behavior. A stratified wavy flow pattern with no mixing at the interface was identified in downward and upward flow. Two gamma-ray densitometers allowed for accurate measurement of the absolute in situ volumetric fraction (holdup) of each phase for all flow patterns. Extensive results of holdup and two-phase pressure gradient as a function of the superficial velocities, flow pattern and inclinations are reported. The new experimental data are compared with results of a flow pattern dependent prediction model, which uses the area-averaged steady-state two-fluid model for stratified flow and the homogeneous model for dispersed flow. Prediction accuracies for oil/water holdups and pressure gradients are presented as function of pipe inclination for all flow patterns observed. There is scope for improvement for in particular dual-continuous flow patterns. 相似文献
82.
Xinhui Si Liancun ZhengXinxin Zhang Min LiJianhong Yang Ying Chao 《Applied mathematics and computation》2011,218(7):3515-3521
In this paper, the asymptotic solution for the similarity equation of the laminar flow in a porous pipe with suction at expanding and contracting wall has been obtained using the singular perturbation method. However, this solution neglects exponentially small terms in the matching process. To take into account these exponentially small terms, a method involving the inclusion of exponentially small terms in a perturbation series was used to find the two solutions analytically. The series involving the exponentially small terms and expansion ratio predicts dual solutions. Furthermore, the result indicates that the expansion ratio has much important influence on the solutions. When the expansion ratio is zero, it is a special case that Terrill has discussed. 相似文献
83.
建立了非均质气藏水平井三维渗流产能预测的数学模型,采用有限元方法对其进行求解,求解时将地质模型区块中不同空间位置处的渗透率值以及其它气藏物性参数分别布置到有限元模型的相应位置处的网格中,从而体现了三维空间中气藏的非均质特性.分析了非均质性对气藏水平井产能的影响.结果表明,气藏的非均质性对水平井的产气量影响很大,在相同的生产压差下,存在高渗透带的气藏水平井产量明显高于均质气藏水平井的产量;高渗透带条数越多、渗透率越大,导致气藏内压力消耗越小,水平井产量越高.最后,结合松辽盆地徐深层气田的地质特点和储层特性,给出了该气田的水平井产能预测实例.研究方法符合气藏的实际情况,为气藏水平井,特别是非均质气藏水平井的产能预测提供了一种行之有效的方法. 相似文献
84.
A conjugate gradient method (CGM) based on the inverse algorithm is used to estimate the unknown fouling-layer profile on the inner wall of a pipe system using simulated temperature measurements taken within the pipe wall. It is assumed that no prior information is available about the functional form of the unknown profile. Therefore, the procedure is classified as the function estimation in inverse calculation. The temperature data obtained from the direct problem are used to simulate the temperature measurements. The accuracy of the inverse analysis is examined using the simulated exact and inexact temperature measurements. The results show that the excellent estimation of the fouling-layer profile can be obtained for the test case considered in this study. The technique presented in this study can be used in a warning system to call for pipe maintenance when the thickness of fouling exceeds a predefined criterion. 相似文献
85.
This paper presents results from seven experimental facilities on the co-current flow of air and water in downward sloping pipes. As a function of the air flow rate, pipe diameter and pipe slope, the required water discharge to prevent air accumulation was determined. In case the water discharge was less than the required water discharge, the air accumulation and additional gas pocket head loss were measured. Results show that volumetric air discharge as small as 0.1% of the water discharge accumulate in a downward sloping section. The experimental data cover all four flow regimes of water-driven air transport: stratified, blow-back, plug and dispersed bubble flow. The analysis of the experimental results shows that different dimensionless numbers characterise certain flow regimes. The pipe Froude number determines the transition from blow-back to plug flow. The gas pocket head loss in the blow-back flow regime follows a pipe Weber number scaling. A numerical model for the prediction of the air discharge as a function of the relevant system parameters is proposed. The novelty of this paper is the presentation of experimental data and a numerical model that cover all flow regimes on air transport by flowing water in downward inclined pipes. 相似文献
86.
87.
由于气体钻水平井中岩屑受力状态与直井有很大不同,特另0是遇到井径扩大,更是携岩的关键点。因此,在分析了气体钻水平并岩屑运移特点以及建立环空连续性方程和动能方程的基础上,以实际并为例考虑了不同井径扩大率,数值模拟了其扩径段气固两相的流动状态,包括气固速度、岩屑浓度、压力分布等。研究结果表明:气体在经历扩径段时环空压力有个降落又回升的过程,随着井眼扩径系数的增大,压力下降又回升,所经历的长度会逐渐增长;扩径系数大于一定值时,扩径变径处存在一定区域的零流动区;扩径系数越大,低速区和回流区就越大越长,扩径下部区域越容易堆积岩屑,填充井眼。 相似文献
88.
89.
90.
We report laser oscillations in Cd II on 4d
95s
2
2
D
5/2 − 4d
105p
2
P
3/2 transition at 441.6 nm using laser produced tungsten plasma as a pumping source. Mach Zehnder interferometer is used to measure
electron density. Design and working of the crossed heat pipe used in the studies is discussed. 相似文献