Experimental Study On Flow Characteristics Of Slug Flow In The Vertical Bending Pipe

Slug flow is a flow of long bubbles and liquid slugs alternating in space and time. In oil-gas mixture transportation, slug flow frequently takes place. Because of instability in flow, it brings many problems for production safety in oil and gas field, such as strong vibration in pipelines, overflow from separator and flow accelerated corrosion in pipeline and so on. In order to increase the safety and optimize the conditions and operation of pipeline and oil-gas separators, it’s very important to analyze the characteristics of the slug flow regime.Relying on equipments and related instruments in multiphase flow lab in the Xi’an Shiyou university, the test-bed system about this paper has been put up successfully. The two phase flow experiment research is finished in inner diameter of 25 mm, different radius of curvature of the vertical bending pipe with air and water as medium, which is of great significance to perfect the slug flow in pipe and practical application. The main research contents and conclusions are as follows:Systematically studied the pressure and differential pressure fluctuation characteristics of slug flow in vertical bending pipe, the results show that slug flow pressure and differential pressure are present a kind of cyclical fluctuations in the same radius of curvature vertical bending. The signal showing a diversity of distribution unmoral, bimodal and multimodal, but the probability density distribution of differential pressure signal is mainly characterized by an unmoral distribution in the vertical bending pipe. Pressure and differential pressure of the probability density dispersion is commuted with superficial gas velocity and liquid velocity increases. Pressure of the power spectral density are the main frequency range change is not big, but the characteristic of the large amplitude; differential pressure of the power density are the main frequency range change is big, but the characteristic of the small amplitude.Relative velocity method is used to analyze and study the characteristic parameters of slug flow in the vertical bending, including the liquid slug velocity, the liquid slug length and the liquid slug frequency. The distribution of slug velocity accords with Gaussian distribution, and Gas superficial velocity is the main influence factors of liquid slug velocity. The distribution of slug length accords with lognormal distribution, and Gas superficial velocity is the main influence factors of liquid slug length. The distribution of slug frequency accords with Gaussian distribution, and liquid superficial velocity is the main influence factors of slug frequency. With the decrease of the vertical bending pipe radius of curvature, the liquid slug velocity, liquid slug length and the liquid slug frequency are reduced.