Study On The Influence Factors Of The Dynamic Performance Of Praticulate-contaminated Oil Based On PIV Technology

Pipeline flow is widely used in various industrial fields.Inevitably,the oil will be mixed with particulate pollutants,so it is of great significance to know the movement characteristics and change trends of the particulate-contaminated oil.Only in this way can control the oil pollution and ensure the safe operation of the oil equipment.In this paper,the particulate-contaminated oil in the pipeline flow is taken as the research object.The experimental pipeline is a square tube with a length of 500 mm and a cross section of 40×40mm.Then the transient velocity data is obtained by Particle Image Velocimetry(PIV)technology.Moreover,the instantaneous velocity,the average velocity,the turbulence strength and the Reynolds stress is analyzed under the different stress condition and different particle pollution degree.Thereby,the dynamic performance change of the oil is obtained.According to the development process of the formation,growth and collapse of the vortex,the internal relationship between the vortex and the macroscopic motion characteristics of the oil is explored.The mechanism of the oil's dynamic performance change is also revealed.It lays a foundation for effectively mastering the state of oil particle pollution and achieving oil pollution control.The main works of the dissertation are as follows:(1)In this paper,Particle Image Velocimetry(PIV)system was built as an experimental platform.The scientific and reasonable experimental scheme is formulated to ensure the reliability and accuracy of the experimental data.Five sets of fluids with different particle sizes were formulated(Pollution degrees are: 17/12,18/13,19/13,19/14 and 20/16).Under the eight sets of system stress(0.10MPa-0.17MPa),the PIV experimental parameters were improved.The image spotter of different oil samples wasused on the PIV experimental platform.Then the transient velocity vector data of the flow field under each operating condition was obtained by using Insight 4G software for post-processing.(2)By using the Tecplot and Matlab software to analyze and process the transient velocity vector data,the influence of system stress on the dynamic performance of contaminated oil was obtained.It is found that the average velocity of the fluid increased with the increase of the system stress.After the stress rises,the flow becomes more turbulent and vortex begin to appear in the flow field.When the stress is small,the average velocity in the middle region of the flow field is the largest.While the stress gradually increases,the region with the highest average velocity in the flow field is transferred to the bottom of the pipeline.(3)By analyzing the flow field parameters obtained by the software and comparing the changes of the five groups of oils,the influence of the oil pollution degree on the dynamic performance was obtained.It was found that with the increase of oil pollution degree,there is a certain increase in both the lateral time-averaged velocity and the vertical time-averaged velocity.The number of particles in the oil mainly affects the time-averaged velocity in the middle and bottom regions,the effect on the top area is small.In addition,increasing the number of particles in the oil causes the up-throw phenomenon of the low-velocity fluid increase,which increases the Reynolds stress in the near wall region.(4)Based on the flow information under different pollution degrees and different stress conditions.Combining with the process of vortex generation,growth and collapse,the influence of the vortex development in the pipeline flow field is analyzed.The relationship between the dynamic characteristics of the vortex and the macroscopic motion of the oil is discussed.Moreover,the mechanism of the oil's dynamic change is revealed,which provides theoretical support for effectively obtaining the motion trajectory of particulate pollutants.