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

Liquid-gas slug flow as a familiar but harmful regime of two phase flow,which is playing a significant role in the multiphase flow researching field.Experimental investigations were carried out in a group of inner diameter 25 mm organic glass(PMMA)made vertical bend pipe.The vertical bend pipe with different arc length of 500 mm,600mm,700 mm,800mm.The every single kind of response characteristics were analyzed based on the experimental data by some mathematics tools.The main contents and conclusions of this research were given as follows:The pressure and differential pressure data signal response were systematically investigated in this research.The results showed that pressure and differential pressure have completely different signal characteristics.The increase of superficial gas or liquid velocity will both cause the increase of system pressure and differential pressure.The superficial liquid velocity will bring more obvious effect on slug frequency than superficial gas velocity does.The probability density distribution of vertical bending pipe pressure signal showed as a diversified distribution style,but with the vertical bend arc length's increase,the probability density distribution changed to unmoral and bimodal distribution style.For the differential pressure signal,its probability density distribution mostly showed as bimodal style.With the increase of arc length,bimodal style gradually changed to unmoral distribution style.In addition,with the increase of liquid or gas velocity,the dispersion of probability density distribution is enhanced.Differential pressure signal's power spectral density research showed that the increase of superficial gas or liquid velocity will extend the range of power frequency,and also will bring the increase of power spectral changing amplitude.With the increase of arc length,the power spectral density's changing range will got narrow down.A vertical bending pipe based comparison were carried out in this research.For the pressure signal,pressure fluctuation in horizontal pipe is smallest,and the fluctuation in vertical riser is biggest,the pressure in vertical bend pipe at the intermediate place of these pipe styles.On the other hand,the probability density distribution of pressure signal in vertical bend pipe is more disperse than in horizontal pipe.And the comparison of the probability density distribution of pressure signal in vertical bend and vertical riser didn't show anobvious change law.For the differential pressure signal's comparison,vertical riser has the smallest pressure drop fluctuation,while horizontal pipe has the biggest pressure drop fluctuation.The vertical bending pipe is also at the intermediate place between the other two kind of pipe styles.It also showed that the fluctuation both in vertical bending pipe and vertical riser will appeared some negative differential pressure value,which didn't appeared in horizontal pipe.Compare with signal data dispersion and amplitude in all three kinds of pipe styles,it showed that both data dispersion and amplitude of vertical bending pipe is between the other two kinds of pipes,which is bigger than the parameters in horizontal pipe and smaller than it in vertical riser.