Pipe Flow Velocity Research Articles

A comprehensive analysis of the water distribution network by using waterGEMS software

Abstract Water is essential for various human activities, and the water need has dramatically increased with population growth and lifestyle changes. This increased demand underscores the importance of sustainable and efficient water management strategies. This study aimed to create robust, efficient systems to meet growing communities’ current and future water needs. WaterGEMS software was used to identify high- and low-pressure zones in junctions and assess water flow velocity in pipes to evaluate hydraulic performance. The results showed considerable differences in water demand, pressure, elevation, and hydraulic grade at various intersections. The minimum and maximum demand of 1.0 L/min and 19.0 L/min were found at J-2 and J-31, respectively. The elevation varied from 33.78 to 67.38 meters, with the lowest at J-20 and the highest at J-31. Hydraulic grade ranged from 39.40 to 110.04 meters, with the weakest at J-30 and the highest at J-41. Furthermore, the multi-linear regression model constructed to forecast head loss in the water distribution network had significant coefficients and an R-squared value of 0.965, indicating an excellent match to the data. All coefficients had significant p-values (p < 0.05), indicating the model’s reliability.

Stabilizing Pipe Flow by Flattening the Velocity Profile

It is important to control turbulence in industrial processes. Past experimental and numerical researches have shown that a turbulent puff in pipe flow can be removed or delayed by flattening the profile of the upstream velocity because a flattened velocity profile causes the point of inflection on it to collapse. The energy gradient theory has been developed to study turbulent transition, and the relevant studies have shown that turbulence arises due to the generation of singularities in the flow field. In pressure-driven flows like the pipe flow, the point of inflection on the velocity profile leads to the appearance of a singular point in the unsteady Navier–Stokes equation. In this study, the energy gradient theory is used to demonstrate why the point of inflection on the profile of velocity of pipe flow is the critical point for generating turbulence. Then, it is shown how flattening the velocity profile leads to the elimination of the point of inflection on the velocity profile of pipe flows to delay turbulent transition. It is also clarified why this technique is not effective at higher Reynolds number because the flattened velocity profile violates the criterion for flow stability relating to transition to turbulence.

Synchronization Optimization of Pipeline Layout and Pipe Diameter Selection in a Drip Irrigation Network System Based on the Jaya Algorithm

To address the complexity and high computational burden in the design of drip irrigation networks, the Jaya algorithm is utilized to study factors affecting project costs, including equipment and pipeline depreciation and the operation and management costs of the irrigation area. A mathematical model of synchronization optimal design of pipe layout and pipe diameter selection in a drip irrigation network system with constraints on pipe diameter, flow velocity, and pipe pressure is established. Using an irrigation district in Xinjiang, China, as an example, the Jaya algorithm optimization design program was run independently 50 times, and the relative deviation of each optimization result from the optimal solution was calculated. The results show that the annual cost per unit area o is reduced to 635.99 RMB/hm2, a 25.34% reduction compared to the original engineering program, and the investment-saving effect is obvious. The relative deviation is controlled within 3%, which shows that the algorithm has stable convergence performance and can meet the requirements of actual engineering design. The Jaya algorithm eliminates the need for parameter tuning, and it excels in cost savings, algorithm stability, and computational accuracy, making it an effective method for the single-objective optimization design of drip irrigation networks.

Performance analysis of spherically curbed hydrokinetic turbine arranged in ln-line array in a closed conduit

The present study aims to explore the applicability of hydrokinetic turbine (HKT) in a closed conduit. Spherically curbed Savonius HKT (SSHKT) was designed to calculate turbine performance (CP). Pipe flow velocity (V) is kept as 1.0, 2.0 and 3.0 m/s. Turbine performance declines as velocity increases, due to obstruction created by the turbine in the flow passage, flow instability, and separation. Performance of multiple SSHKTs was investigated installed in inline array. These turbines were arranged at varying distance of 2.5D, 3D, 3.5D, 4D, 4.5D and 5D, where D is the turbine diameter. The SSHKTs performed best at 3.5D irrespective of flow velocity. The number of the turbines increase the power production; however, efficiency of the system doesn't increase in that proportion. The CP of the first SSHKT was always higher compared to the next one along the array. In the pipeline, for single turbine, the high flow velocity causes a more significant pressure drop than the low flow velocity. At V = 1.0 m/s, the pressure drop for a single SSHKT is 8.52 %; whereas, at V = 2.0 m/s, the pressure drop is 28.69 %. Due to more blocked places in the arrayed turbines, the percentage pressure loss is greater.

Research on the erosion resistance characteristics of liquid-solid two-phase flow in high-pressure manifolds

During on-site throttling spray operations, the ground high-pressure manifold is subjected to the erosive effects of high-speed liquid-solid two-phase flow, which poses a high risk of erosive damage and eventual failure. In response to the erosive conditions caused by high-speed sand-carrying liquid-solid two-phase flow on the high-pressure manifold, an experimental apparatus for erosive testing was designed, taking into account key factors such as internal pressure loads. Microscopic erosive morphologies were observed in the experiments. Subsequently, numerical simulation methods were employed to investigate the identification of erosive danger zones and the influence of different installation angles, sand content, pipe flow velocities, and viscosity on erosive areas of the manifold.The research findings indicate that the microscopic morphological changes in erosive experiments align with the micro-cutting theory, which was successfully applied in simulation. Erosive danger zones are mainly distributed on the outer arch side, the curved arc connecting section, and the initial part of the outlet straight pipe. The erosive areas do not vary with changes in installation angles, sand content, and flow velocities. As viscosity increases, the erosive area shifts. The erosive rate is positively correlated with sand content and pipe flow velocity, and with increasing viscosity, the erosive rate on the first outer arch side shows an initial decrease followed by stabilization, while the second outer arch side exhibits an initial increase followed by stabilization. As the installation angle increases, the erosion rate on the second outer arch side first shows a stable trend and then decreases rapidly. At 75°, the erosion rate reaches the lowest.

Prediction of emergency-free operation of production wells with a horizontal termination under conditions of high removal of mechanical impurities on the example of the Severo-Komsomolskoe field

Relevance. As readily available oil reserves are developed and production technologies develop, oil and gas companies are gradually moving to the development of previously unprofitable assets. Over the past five years, several oil-and-gas condensate fields with oil rims have been put into operation in Western Siberia. Their development is further complicated by oil high viscosity and poor cementation of the reservoir rocks. Low values of critical drawdown do not allow oil to be produced without destruction of the productive formation, and mechanical impurities entering the well lead to spillage of perforation intervals and downhole equipment failures. The use of mathematical modeling in relation to the operation of wells in the conditions of the removal of mechanical impurities will make it possible to control production and select the optimal well operation mode. Aim. Forecasting the trouble-free operation of a production well under conditions of high removal of mechanical impurities. Objects. Producing oil wells; the subject of the study is the movement of solid particles in the wellbore of a production well, the relationship and dependence of formation of sand plugs on the operating parameters of the well. Methods. Theoretical research methods – analysis (analysis of models for calculating the critical flow velocity in a horizontal pipe (calculation of the critical velocity in a single-phase flow; calculation of the critical velocity in a multi-phase flow; calculation of the critical velocity based on the balance of forces)) and modeling (simulation of work wells with the removal of mechanical impurities). The totality and combination of these methods are adequate to the goals and objectives, the object and subject of the study of this work. Results. The problem of sand production is typical not only for fields that are in the late stages of development, but also for fields that have recently been put into operation. Sand shows up are a complicating factor in the operation of wells at the Severo-Komsomolskoe high-viscosity oil field located in Western Siberia. The main object of development of the studied field is a weakly cemented sandy layer. Oil production in such difficult areas requires a very careful approach to the choice of development system, to the selection of methods to deal with complications, including the choice of the right method to limit sanding. However, regardless of the approach taken to solve the problem of sand production, some rock will still flow into the well. To prevent the formation of sand plugs, it is necessary to understand the nature of the movement of solid particles along the wellbore. It is possible to assess whether a well is capable of carrying out solid particles from a horizontal section using modeling in specialized software products. Modeling of the well operation, taking into account the influence of mechanical impurities, made it possible to solve the following problems: 1) determine the fluid to carry rock particles out of the horizontal section; 2) identify the areas in which there is a risk of sand plugs; 3) present the dependence for calculating the critical speed for high-viscosity oil with different water cut; 4) assess how the water cut and gas factor affect well operation in conditions of high removal of mechanical impurities; 5) calculate the time of formation of sand plugs.

Experimental investigation of the motion states of coarse particles with sediment-laden flow in a horizontal pipe

This paper investigates coarse particle motion states via physical experiments of coarse particles and sediment-laden water or pure water flowing in a horizontal pipeline. The effects of coarse particle sizes, pipe flow velocities and coarse particle mass rates entering the pipeline are analyzed. The coarse particle motion can be divided into three regimes: plug, layer shift and mobile conveying. Regarding plug conveying, a particle plug is formed and moves as a head-to-tail transformation. Regarding mobile conveying, particles are in discrete contact with each other and move rapidly. The layer shift conveying is a transition stage, a continuous flat particle layer is formed at pipe bottom. The relationships among conveying regimes, instantaneous pressure, time-averaged pressure and fluctuating pressure features are clarified. A parameter is proposed to classify coarse particle motion states. Its accuracy is demonstrated using particle image velocimetry (PIV) and the relationships between conveying regimes and instantaneous pressure features.

GPU accelerated volumetric lattice Boltzmann model for image-based hemodynamics in portal hypertension

We are developing a new technique for monitoring portal hypertension by the pressure gradient between the portal vein and the inferior vena cava (PPG) based on non-invasive measurements (MRI images). Massive parametrization and classification are required to investigate the underlying relationship between the porosity and the stages of liver cirrhosis numerically, and the hepatic-portal venous system is a multi-scale system. Both of them need high computational costs. The suitability of the lattice Boltzmann method for GPU (Graphics Processing Unit) parallel computation provides an opportunity to overcome it. In this paper, we perform GPU parallelization and optimization for the volumetric lattice Boltzmann method with arbitrary geometry based on images. Three application cases, including pipe flow, hemodynamics in the portal venous system, and hemodynamics in a simple hepatic-portal venous system, are employed to prove the method can be applied in the hepatic-portal venous system based on accuracy and efficiency. The reliability of the model is qualitatively validated by the analytical solution of velocity and pressure difference distribution of pipe flow and quantitatively confirmed by the pulsatility of velocity and pressure difference that can be neglected in the portal venous system. The performance of the application cases is examined with Intel Broadwell E5-2683 v3@ 2.30 GHz (CPU) and NVIDIA Tesla V100 16GB (GPU). It shows the GPU algorithm for sparse geometry (SPARSE) has a similar speed to the regular GPU algorithm for dense geometry (DENSE) when the fluid volume fraction (q) is close to 1. And SPARSE speeds up to 2.2 times compared with DENSE when q is in the range of 0.19∼0.27. Meanwhile, the saving ratio of memory cost depends on q. For a numerical case in the hepatic-portal venous system, i.e., a large-scale system, parallel execution can be converged around half an hour with SPARSE, while the memory spills the limitation with DENSE with a single GPU. Hence, multi-GPU implementation is applied to release the limitation, and it can improve performance by increasing the number of GPU cards. In summary, the method presented in the paper is feasibility applied in the hepatic-portal venous system, laying the foundation of the new technique development.

Investigation on the Electrostatics Saturation of Flow Electrification in the Liquid Hydrogen Transportation

Research on the flow electrification characteristic is of paramount importance for ensuring the electrostatic safety of liquid hydrogen transportation systems. However, the discussion about electrostatic saturation in flow electrification has been lacking. To address this gap, a theoretical model governing the process of flow electrification is constructed which couples the charge conservation equation with the Navier-Stokes equations and applies the Neumann boundary conditions at the solid-liquid interface, and the application of this model is validated by existing experimental data with the simulation parameters of At and n being 9.08 × 1012 and 0.85 for liquid hydrogen. A comparison with benzene reveals that benzene almost reaches the electrostatic saturation state after flowing one meter, whereas the flow of liquid hydrogen remains in the linear growth stage. However, with an increase in pipe length, a gradual saturation trend emerges in the curves of streaming current versus flow distance when the flow distance exceeds 10 m. At the outlet, the corresponding streaming current and charge density are approximately 160 pA and 3 μC/m3, respectively, significantly higher than those observed at one-meter flow distance. Furthermore, the influences of pipe radius and flow velocity on the arrival of electrostatic saturation are analyzed, and the results show that increasing both the pipe radius and flow velocity leads to a delay in the arrival of electrostatic saturation and enhances the saturation value of the streaming current. In conclusion, this study thoroughly discusses the development of flow electrification along with the flow distance and the phenomenon of electrostatic saturation in the long-distance flow of liquid hydrogen, which is crucial for the safe transportation of liquid hydrogen over extended distances.

Determining the flow transition from laminar to turbulence using simple spin-echo magnetic resonance techniques

We have recently introduced a methodology to determine the average velocity and flow behavior index of laminar pipe flow of a power-law fluid using simple magnetic resonance (MR) techniques. In general, MR techniques are noninvasive and capable of working on optically opaque fluids. Knowledge of the average velocity and flow behavior index provides the information needed to reconstruct the flow velocity profile. However, as the flow velocity increases, the flow will begin to develop turbulence. For pipe flow of a particular fluid, the velocity profile is flatter in the center of the pipe at turbulent flow rates compared with laminar flow. An effective flow behavior index can approximate the time-averaged velocity profile, as the Reynolds number increases, as a fluid transitions from laminar to turbulent flow. Here, we show the results of testing the utility of such a simplification in monitoring that transition. For the present study, Reynolds numbers ranged from approximately 490 to 6800, which corresponds to flow rates of 200 to 2750 ml/min and average velocity of 5 to 80 cm/s. We found that visual inspection of the data would be sufficient to determine the state of the flow. With some external knowledge of the flow rate, the shape of the time-averaged velocity profile and eddy diffusivity can be estimated (and potentially also an average fluid particle acceleration).

Modelling of flow in backward erosion pipes

Backward erosion piping is an important failure mechanism that can affect the safety of water-retaining structure foundations, which results in the formation of shallow pipes at the interface of the cohesive layer and the sand layer. Pipe hydraulics provides a lot of valuable information about the erosion mechanism, but it had never been analysed systematically during equilibrium. This paper analyzes pipe hydraulics by combining the pipe flow model and numerical simulations of experiments. A single-phase pipe-flow model is presented that includes not only frictional and accelerational pressure drops, but also the pressure drop caused by inflow through the pipe wall. The pipe-flow model is included in pipe/aquifer coupling numerical models to achieve more accurate predictions of pressure drop and inflow distribution along the pipe. The predictions agree favourably with previously published experimental data. And the calculated pipe flow velocities, hydraulic regimes and gradients are analysed for different pipe lengths.

Stress effects on thermal conductivity of soils and heat transfer efficiency of energy piles in the saturated and unsaturated soils

Soils surrounding energy piles are often subjected to high overburden pressure. So far, the stress effects on the thermal conductivity of soils and hence the thermal performance of energy piles have not been well investigated. This study proposed a new model for the stress-dependent thermal conductivity of saturated and unsaturated soils. It was validated using the data from a series of new tests and the literature and is able to capture stress-induced variations of thermal conductivity. Then, it was applied to finite element analysis of energy piles’ heat transfer efficiency. The numerical results reveal that ignoring stress effects on thermal conductivity, as in the conventional analysis, underestimates the heat exchange rate between energy piles and ground. The underestimation is more significant for piles with a larger aspect ratio and a faster pipe flow velocity, especially when the ground is drier and more compressible. For example, when the pile is 0.6 m in diameter and 50 in aspect ratio, the underestimation is up to 18%, 15% and 4% for the clay, silt and sand, respectively. These results suggest that stress effects on thermal conductivity should be considered for better assessing the heat transfer efficiency of energy piles and other thermal geostructures.

Vulnerability hotspot mapping (VHM) of sewer pipes based on deterioration factors

ABSTRACT A decentralized, and sustainable sewer inspection plan at the city scale demands multiple inspection methods with different areas of impact. While sewer deterioration models offer great areas of impact, spatial mapping can assess the vulnerability of the system without prior knowledge of the pipe’s structural health condition. In this study, we assess and prioritize sewer deterioration factors such as pipe age, material, sewer type, node degree, flow velocity, and surface vegetation for vulnerability hotspot mapping of a sewer system in Dresden, Germany. The validation and sensitivity analyses revealed that flow velocity, pipe age, and surface vegetation are the most sensible factors to model, respectively. The linear model resulted in 76% efficiency and a mean squared error of 0.918 while it was improved with a random forest algorithm which points out vulnerability mapping potential as an early sewer inspection method at the city scale.

A novel approach to multi-path ultrasonic transit time flow meter based on measurement model analysis to improve accuracy

Ultrasonic transit time flow meter (UTTFM) is commonly used in a wide range of applications. It is commonly believed amongst researchers, industrialists, and standard committee members that due to nonuniform flow velocity distribution inside the pipe (flow velocity profile) the measured flow velocity using UTTFM needs to be corrected by the flow profile. Mathematical analysis of UTTFM measured quantity shows that UTTFM measures flow correctly when flow is fully developed or laminar. However, the measurement results using flow profile correction factor produces erroneous values. The UTTFM measurement model assessment shows, when flow is not fully developed, there are unknown quantities contributed by flow velocity in the axial and diametrical direction to measurement results. These unknown quantities lead to erroneous measurement results when it is simply corrected by flow profile. Assessment of the UTTFM error model shows that using multi-path UTTFM can significantly reduce the impact of the unaccounted quantities and improve accuracy. A novel approach to UTTFM design utilizing multiple acoustic paths (using different planes and transmitting angles) is proposed to reduce potential error for UTTFM. This approach is consistent with the general measurement modeling method with incomplete information recommended by JCGM GUM-6:2020.

Flow visualization simulation of cemented tailings backfill slurry by particle tracking technology

AbstractPipeline flow visualization of cemented tailings backfill slurry (CTBS) improves the safety and stability of transportation. High turbidity and low resolution make it difficult for conventional methods to monitor the particle distribution state of CTBS in a short period of time. Particle tracking technology (PTT) is used to simulate and investigate the flow characteristics of CTBS pipeline, combine with theoretical analysis to construct a CTBS pipeline visualization model, elaborate the particle distribution state when CTBS flows in the pipeline, and explore the effects of pipe diameter (PD), flow velocity (FV) and tailings gradation (TG) on the particle distribution. The results show that particle tracking technology is better applied to investigate the particle transport distribution characteristics of CTBS tailings. Three concepts of particle accumulated gravity Ga, static friction angle θ and diameter dividing line are defined, and the transport pipe is divided into light wear zone, medium wear zone and heavy wear zone. The increase in pipe diameter increases the content of fine particles at the pipe wall and the thickness of the lubrication layer becomes larger, which improves the safety and stability of CTBS transport. The increased flow velocity reduces the settling phenomenon of large size particles and improves the transport efficiency, which increases the pipeline transport resistance. Under good tailings grading conditions, a wide range of tailings grading is more suitable as backfill material. The results of the study illustrate the flow characteristics of the backfill slurry in the pipeline from the particle perspective and provide a theoretical basis for pipeline transportation research.

Degradation of sulfamethoxazole by chlorination in water distribution systems: Kinetics, toxicity, and antibiotic resistance genes

Sulfamethoxazole (SMX) is one of veterinary drugs and food additives, which has been frequently detected in surface waters in recent years and will cause damage to organisms. Therefore, SMX was selected as a target to be investigated, including the degradation kinetics, evolution of toxicity, and antibiotic resistance genes (ARGs) of SMX during chlorination in batch reactors and water distribution systems (WDS), to determine the optimal factors for removing SMX. In the range of investigated pH (6.3-9.0), the SMX degradation had the fastest rate at close to neutral pH. The chlorination of SMX was affected by the initial total free chlorine concentration, and the degradation of SMX was consistent with second-order kinetics. The rate constants in batch reactors are (2.23 ± 0.07) × 102 M-1 s-1 and (5.04 ± 0.30) × 10M-1 s-1 for HClO and ClO-1 , respectively. Moreover, the rate constants in WDS are (1.76 ± 0.07) × 102 M-1 s-1 and (4.06 ± 0.62) × 10M-1 s-1 , respectively. The degradation rate of SMX was also affected by pipe material, and the rate followed the following order: stainless-steel pipe (SS) > ductile iron pipe (DI) > polyethylene pipe (PE). The degradation rate of SMX in the DI increased with increasing flow rate, but the increase was limited. In addition, SMX could increase the toxicity of water initially, yet the toxicity reduced to the level of tap water after 2-h chlorination. And the relative abundance of ARGs (sul1 and sul2) of tap water samples was significantly increased under different chlorination conditions. PRACTITIONER POINTS: The degradation rate of SMX in batch reactor and WDS is different, and they could be described by first- or second-order kinetics. The degradation of SMX had the fastest rate at neutral pH. The degradation rate of SMX was also affected by pipe material and flow velocity. SMX increased the toxicity of water initially, yet the toxicity reduced after a 2-h chlorination. SMX increased the relative abundance of antibiotic resistance genes sul1 and sul2.

Rancang Bangun Pompa Hidram sebagai Solusi Sistem Pengairan di Daerah Perbukitan

Water is one of the natural resources needed by all living things. Not only for human and animal consumption but water is also needed by plants for the process of growth and development. In areas where the position is low (below sea level), water is very easy and often found. However, in contrast to hilly and mountainous areas. Generally, farmers rely on rainwater to meet crop water needs. Therefore, hydram pump technology is a solution for irrigation systems in hilly and mountainous areas. This study aims to design a hydram pump system with a two-valve system. This research was conducted through several stages, namely design, provision of tools and materials, functional design and structural design, and testing. The main material for making hydram pumps comes from PVC pipes with different diameters, namely ¾, 2, and 3 inches. The design of the hydram pump consists of several main components, namely the input pipe, output pipe, delivery valve, waste valve, and air tube. Based on the results of the type 2 valve hydram pump test, the resulting discharge data is 8 liters/minute. The flow velocity in the input pipe and the output pipe are 0.052 m/s and 0.42 m/s respectively. One of these differences is influenced by the diameter of the pipe, where the flow velocity is inversely proportional to the diameter of the pipe. The flow rates generated in the input pipe and output pipes are 1.33 x 10‑4 m3/s and 1.32 x 10‑4 m3/s respectively.

Measurement of bubble/slug velocity and size in vertical pipe based on optical cross-correlation method

Based on the principle of the cross-correlation, the method for measuring the velocity and size of bubbles in transparent gas-liquid two-phase flow in a vertical pipe is proposed by taking optical attenuation signal as the object. This method is used to measure the bubble velocity and size of transparent gas-liquid two-phase flow in vertical pipeline of two-phase flow experimental platform, and compared with synchronous measurement by image method. The experimental results show that the relative deviation of velocity and size between optical cross-correlation measurement and image method is less than 3% and 5%, respectively. The optical cross-correlation method can be used to measure the bubble velocity and size parameters of transparent gas-liquid two-phase flow in the vertical pipe without contact, and this method is suitable for industrial applications.

The effect of the liquid physical properties on the wave frequency and wave velocity of co-current gas-liquid stratified two-phase flow in a horizontal pipe

The aim of the present study was to investigate the effect of the liquid physical properties on the liquid film thickness, wave frequency, and wave velocity in co-current gas-liquid stratified two-phase flow in a horizontal pipe. The present experimental study was conducted using an acrylic pipe with an inner diameter of 26 mm and a length of 9500 mm. The superficial velocity of liquid (JL) and gas (JG) were 0.02 m/s to 0.1 m/s and 4 m/s to 16 m/s, respectively. A highspeed video camera was used to take the visual data which is then processed by the developed image processing techniques to obtain the time series data of the liquid film thickness. The probability distribution function (PDF) and discrete wavelet transform (DWT) were used to analyze the time series of the liquid film thickness. In addition, the data were also analyzed using the power spectral density (PSD) in order to obtain the wave frequency and the wave velocity. Next, the experimental correlations to predict the wave frequency and the wave velocity were developed using the dimensional analysis. From the time series of the liquid film thickness, the effect of the viscosity and surface tension on the shifting of scale and frequency of the wavelet decomposition level, as well as the frequency and velocity of the waves were clarified. In addition, a correlation to predict the frequency and velocity of waves has been successfully developed, in which the Martinelli parameter, the ratio of gas and liquid Reynold numbers, and the Weber number play the important roles in the correlation.

Continuous wavelet analysis and proper orthogonal decomposition on particle dynamics in a horizontal self-exited gas-solid two-phase pipe flow

The high-speed particle image velocimetry is applied to measure the particle velocities of a horizontal self-exited gas-solid two-phase pipe flow with soft fins at the air velocity of the minimum pressure drop. The detailed particle dynamics of using fins' cases are analyzed and compared with a conventional non-fin case. It is found that the particle accelerating process is delayed in the acceleration regime and the vertical particle velocity is decreased near the top part of fully-developed regime due to the effect of fins' oscillations. The continuous wavelet transform of axial particle fluctuation velocity suggests that the fins make the particle motions fall into a lower frequency range in the acceleration regime. In the fully-developed regime, the dominating frequencies of large-scale particle flows are decreased and the streaks appearing in the range of high frequency are weakened by using fins. The energy distributions of proper orthogonal decomposition (POD) modes indicate that the relative energy of POD mode1 is increased by using fins in both acceleration and fully-developed regimes, and the dominance is significantly enhanced by using fins in the fully-developed regime. The auto-correlation coefficients and central frequencies of POD modes exhibit that the dominating large-scale particle motion is enhanced by using fins, correspondingly, small-scale particle motion is suppressed. • The particle velocity of a horizontal self-exited gas-solid two-phase pipe flow is measured at minimum air velocity by PIV. • POD and continuous wavelet transform is adopted to analyze the particle fluctuation velocities. • The dominating frequencies of large-scale particle flows are decreased. • The streaks appears in the range of high frequency are weakened by using fins. • The dominance of POD mode 1 is significantly enhanced by using fins in the fully-developed regime.