Behavior Of Gas-liquid Two-phase Flow Research Articles

Progress on Numerical Simulation of Gas-Liquid Two-Phase Flow in Self-Priming Pump

The fundamentals of the design and operation of self-priming pumps, as indispensable equipment in industry, have been the focus of research in the field of fluid mechanics. This paper begins with a comprehensive background on self-priming pumps and gas-liquid two-phase flow, and it outlines recent advances in the field. Self-priming pumps within the gas-liquid two-phase flow state and the spatial and temporal evolution of the transient characteristics of self-priming pumps determine the self-priming pump self-absorption performance. Through mastery of the self-absorption mechanism, high-performance self-absorption pump products can be formed to provide theoretical support for the development of products. In current research, numerical simulation has become an important tool for analyzing and predicting the behavior of gas-liquid two-phase flow in self-priming pumps. This paper reviews existing numerical models of gas-liquid two-phase flow and categorizes them. Reviewing these models not only provides us with a comprehensive understanding of the existing research but also offers possible directions for future research. The complexity of gas–liquid interactions and their impact on pump performance is analyzed. Through these detailed discussions, we are able to identify the challenges in the simulation process and summarize what has been achieved. In order to further improve the accuracy and reliability of simulations, this paper introduces the latest simulation techniques and research methodologies, which provide new perspectives for a deeper understanding of gas-liquid two-phase flow. In addition, this paper investigates a variety of factors which affect the operating efficiency of self-priming pumps, including the design parameters, fluid properties, and operating conditions. Comprehensive consideration of these factors is crucial for optimizing pump performance. Finally, this paper summarizes the current research results and identifies the main findings and deficiencies. Based on this, the need to improve the accuracy of numerical simulations and to study the design parameters in depth to improve pump performance is emphasized.

Simulation of non-Newtonian fluid flow in a horizontal pipe

Microchannel reactors exhibit distinct gas-liquid two-phase flow behaviors compared to macro-scale channels, offering advantages like efficient heat and mass transfer, compact size, and low energy consumption. Sodium carboxymethyl cellulose (CMC) emerges as a potent stabilizer, enhancing mixing, homogenization and pipeline transport. Its judicious application reduces equipment strain, amplifies homogenization efficiency and finds diverse utility in food processing and beyond. However, incorrect employment bears the risk of compromised outcomes, potentially leading to product wastage. Consequently, investigating N2-CMC solution flow in microchannels holds paramount significance for elevating efficacy, minimizing usage, refining product quality and bolstering yield. In this study, we simulated the N2-CMC solution flow dynamics within an interleaved T-shaped microchannel using FLUENT which is a numerical simulation software. The simulation delved into alterations in gas-liquid two-phase flow patterns and pressure drops. We examined the impacts of liquid concentration and gas-liquid flow rate ratio on flow patterns, pressure drops and bubble lengths. The simulation results exhibited congruence with experimental data. Notably, elevated liquid concentrations correlated with higher pressure drops and elongated bubble lengths. Conversely, augmenting the gas-liquid flow rate ratio led to diminished pressure drops while elongating bubble lengths. These findings furnish insights into flow patterns and pressure drop behaviors for gas-non-Newtonian fluids within microchannels, forming a pivotal reference for microfluidic system design.

Examining the interfacial behavior of non-Newtonian gas-liquid two-phase flow in horizontal square microchannels

This study investigates the flow dynamics of a non-Newtonian two-phase flow within a horizontal square microchannel. The experimental apparatus employed an acrylic channel with a side length of 8 × 10−4 m. Nitrogen served as the test gas, and the test liquids consisted of water and CMC (Carboxymethylcellulose) aqueous solutions at concentrations of 0.2 and 0.4 %wt. The superficial velocity of working gas and liquids spanned ranges of 0.26–20 m/s and 0.05–1.0 m/s, respectively. A differential pressure transducer was used to measure pressure gradients, while a high-speed video camera captured the flow behavior for analysis with a custom image processing technique. Nonlinear regression statistical analysis was applied to establish the criteria for flow pattern transition. Furthermore, signal processing techniques such as PSD (Power Spectral Density), DWT (Discrete Wavelet Transform), ANN (Artificial Neural Network), and Kolmogorov entropy were employed to analyze the flow behavior based on the pressure gradient signals from the differential pressure transducers. Our findings reveal the occurrence of bubbly, slug, slug-annular, and churn flow patterns. The nonlinear regression statistical analysis offered ambiguous results for determining flow pattern transitions. However, an empirical coefficient was obtained for the nondimensional liquid height. Moreover, the empirical nondimensional liquid height aligned well with the experimental values. The PSD and DWT analysis corroborated each other in clearly characterizing the flow pattern based on pressure gradient fluctuation and wavelet energy. The Kolmogorov entropy effectively captured the chaotic flow pattern. Furthermore, the ANN analysis demonstrated a solid agreement between the predicted and actual flow patterns.

Numerical Simulation of Flow and Argon Bubble Distribution in a Continuous Casting Slab Mold under Different Argon Injection Modes

A three-dimensional model is established to investigate the effect of argon injection mode, argon flow rate and casting speed on the gas–liquid two-phase flow behavior inside a slab continuous casting mold. The Eulerian–Eulerian model is employed to simulate the gas–liquid flow, and the population balance model is applied to describe the bubble breakage and coalescence process in the mold. The numerical simulation results of the bubble size distribution are verified using the water model experiment. The results show that the flow field and bubble distribution are similar between the argon injection at the upper submerged entry nozzle (SEN) and tundish upper nozzle (TUN), while the number density is larger for the argon injection of TUN. The coalescence rate of bubbles and the bubble size inside the mold increase with increasing argon flow rate. When the argon flow rate exceeds 4 L/min, the flow pattern of liquid steel changes from double-roll flow to complex flow, with aggravation of the level fluctuation of the top surface near the SEN. When the casting speed increases, the bubble breakup rate increases and results in a decrease in the size of bubbles inside the mold. At a high casting speed, the flow pattern tends to form double-roll flow, and the liquid level at the narrow face of the top surface increases.

A comparison of gas-liquid two-phase flow behaviors between two offshore pipeline-riser systems with different geometric parameters: From view of flow pattern identification

The accuracy of data-driven flow pattern identification in gas-liquid two-phase flow depends on the quality of training data. If a high similarity of input parameters exists between the training and the application conditions, then, the trained identification model would be applicable. Aiming at pipeline-riser systems in offshore oil and gas fields, a comparative study of different laboratorial two-phase flow loops with different geometric parameters is performed. Statistical parameters commonly used for flow pattern identification are examined. Similarities and differences of parameter distribution in the feature domain are discussed. By analyzing the mean and amplitude scatter distributions, the feature region divisions for identification are determined. First through conditional judgment, and then through LS-SVM recognition, the identification model is constructed. The shortest sample length for effective identification of each flow pattern is analyzed through the relationship between the identification accuracy and the sample length. The typical severe slugging could be easily identified under different pipe geometry conditions even when the sample length is 1 s. The identification accuracies of oscillation, irregular and stable flow patterns vary under different application conditions.

Analysis and identification of gas-liquid two-phase flow pattern based on multi-scale power spectral entropy and pseudo-image encoding

Gas-liquid two-phase flow is closely related to the production and transportation of energy industries. A flow pattern analysis and identification method based on multi-scale power spectral entropy (MPSE) with pseudo-image encoding (PIE) is proposed. The resistance sensor array is used to collect gas-liquid two-phase flow information from the vertical upward pipeline, and the data is dimensionally reduced to simplify analysis. The MPSE is derived from the power spectrum of reduced-dimensional sequences to characterize the frequency domain complexity of the flow system at different scales. The optimal scale for spectral entropy analysis is further calculated to investigate the transition mechanism of gas-liquid two-phase flow patterns. In addition, the PIE algorithm is used to map the power spectrum into two-dimensional grayscale images to visualize the differences in frequency domain features of flow patterns. Combined with the deep learning model ResNeXt, the flow patterns are classified and compared with the traditional identification scheme. Results show that the proposed method can reveal the dynamic evolution behavior of gas-liquid two-phase flow from the frequency domain and achieve accurate identification of the flow patterns.

Effect of additional periodic motion on gas-liquid two-phase secondary flow behavior in inclined pipes

Secondary flow significantly changes the flow structure and increases flow resistance. The pipeline motion further contributes to the evolution of secondary flow. This study aims to elucidate the characteristics of two-phase secondary flow in inclined pipelines under additional periodic motion conditions. Based on the CFD technique, three-dimensional oscillating two-phase flow fields were simulated using the VOF model and dynamic mesh method. The focus was on four common flow patterns observed in inclined pipes, namely stratified flow, slug flow, turbulence flow, and transitional flow. The impact mechanisms of swaying, heaving, and coupling motion on the structural evolution, velocity profile, and relative intensity of secondary flow were analyzed. The results indicate that additional periodic motion exhibits a significant dominant behavior on secondary flow when the amplitude exceeds 1.0D. Heave motion has a more pronounced effect on the secondary flow structure. Additional periodic motion induces periodic evolution of secondary flow structure in stratified flow, with the evolution period aligning with the period of the additional motion. Under additional periodic motion, there is no one-to-one correspondence between secondary flow velocity and axial velocity. Additional motion significantly suppresses the axial velocity of slug flow. Furthermore, additional periodic motion significantly increases the relative intensity of secondary flow, exceeding 10%. When the amplitude is less than 1.5D, additional motion suppresses the relative intensity of secondary flow in turbulence flow and transitional flow.

Interfacial wave of the gas-liquid two-phase flow in unsaturated reservoir pores

Unsaturated reservoir pores exist widely in porous self-lubricating materials for the continuous consumption of lubricant. The complex gas-liquid two-phase flow behavior in the pores significantly affects the self-lubricating performance. In this paper, the two-phase flow model in unsaturated pores was established based on the Couple Level Set and Volume of Fluid method. Two kinds of porous materials with significantly different wettability, stainless steel and polytetrafluoroethylene (PTFE), were concerned. The two-phase flow behaviors were investigated to reveal the flow mechanism in the unsaturated pores. The different flow behaviors caused by the wettability of materials were quantitative characterization. Results show that, the gas rises with a convex interface in the stainless steel pore, and the bubble is generated after the contact line is pinned on the edge of the pore at 35 ms. While in the PTFE pore, the gas rises with a concave interface. And the gas profile changes from concave to convex after the contact line is pinned at 32 ms. In the two pores, the gas-liquid interface fluctuates periodically. In the hydrophilic stainless steel pore, the fluctuation amplitude decreases and finally tends to be stable with the increase of time. In the hydrophobic PTFE pore, the interface has constant fluctuation amplitude for the attraction between gas and the hole wall. The fluctuation of the gas-liquid interface has an important influence on the flow state of the lubricant film. The results help to clarify the two-phase flow mechanism within unsaturated pores, and provide guidance for the self-lubrication design of the porous materials.

Experimental visualization of the gas-liquid two-phase flow inside the multi-cavity during reciprocating motion

The piston cooling of engines are usually controlled by the “cocktail shake” mechanism inside the single cooling cavity, according to most studies of piston cooling published before. This paper researched on flow in multiple cooling cavities which are extensively used on pistons of low-speed engines, revealing that the flow in multi-cavity is quite different from that in a single cooling cavity. In this work, complete reciprocating cycles are captured to study the gas-liquid two-phase flow behavior of each cavity inside the multi-cavity piston, by conducting synchronous experiments using benchmarked high-speed camera and a real size piston. The effects of different engine speeds (40–64 rpm) and different inlet pressures (0.1–0.3 MPa) were investigated. Both the inner and annular cavities are cooled mainly by cocktail shaking, but two cooling mechanisms are observed in the outer cavity, the oscillatory effect and cyclonic effect, providing further development on piston cooling studies. The cyclonic effect enhances the heat transfer capacity of the sidewall surfaces. The coupling effect between multiple cavities produces a secondary mixing effect of the liquid and improves the overall turbulence. In this paper, a comprehensive analysis of the flow mechanism within a typical multi-cavity piston is presented.

Characterizing gas-liquid two-phase flow behavior using complex network and deep learning.

Gas-liquid two-phase flow is polymorphic and unstable, and characterizing its flow behavior is a major challenge in the study of multiphase flow. We first conduct dynamic experiments on gas-liquid two-phase flow in a vertical tube and obtain multi-channel signals using a self-designed four-sector distributed conductivity sensor. In order to characterize the evolution of gas-liquid two-phase flow, we transform the obtained signals using the adaptive optimal kernel time-frequency representation and build a complex network based on the time-frequency energy distribution. As quantitative indicators, global clustering coefficients of the complex network at various sparsity levels are computed to analyze the dynamic behavior of various flow structures. The results demonstrate that the proposed approach enables effective analysis of multi-channel measurement information for revealing the evolutionary mechanisms of gas-liquid two-phase flow. Furthermore, for the purpose of flow structure recognition, we propose a temporal-spatio convolutional neural network and achieve a classification accuracy of 95.83%.

High-performance microfluidic electrochemical reactor for efficient hydrogen evolution

Hydrogen production from water electrolysis provides an effective bridge between the existing energy system and the layout of green renewable energy. Electrochemical hydrogen gas evolution on the electrode surface will occupy the limited active sites thus significantly increasing the reaction overpotential. It is crucial to study and optimize the bubble behavior on the electrode surface to improve reaction efficiency and lower the energy loss. Herein, a microfluidic electrochemical reactor (MER) has been constructed to optimize the surface gas-liquid two-phase flow behavior during the gas evolution process. The obtained results demonstrate the feasibility of microfluidic design in manipulating the bubble behavior at the electrode interface accompanied with the self-generated gas-liquid two-phase flow, which can directly reduce the overpotentials by facilitating the mass transfer and refreshing catalytic active sites. Compared with conventional H-cell, state-of-the-art efficient and stable performance of hydrogen evolution has been achieved, where the increase in current density was more than 5 times. This work reveals a new strategy for guiding the design of the electrochemical reactor for water splitting.

Prediction of gas-liquid two-phase choke flow using Gaussian process regression

In the process of shale gas production, it is of great significance to select an appropriate mathematical method to accurately predict the gas flow rate of wellhead choke for the rational formulation of shale gas well production plan. Gas-liquid two-phase flow occurs in most of the time from the flowback to the production period in shale gas wells. Wellhead chokes play key roles in regulating the flowing rates of both the flowback fluid and shale gas. Therefore, it is important to study the law of two-phase choke flow clearly so as to accurately predict gas flow rate through wellhead chokes. Up to now, previous studies have proposed a variety of applicable empirical methods, including Gilbert-type correlation (GC), artificial neural network (ANN) and support vector machine (SVM). The analysis of training data and the establishment of accurate prediction models determine the accuracy of prediction. In this study, Gaussian process regression (GPR) was adopted to learn and predict the behavior of gas-liquid two-phase flow through wellhead chokes, and huge amounts of data collected from Chuannan Shale gas wells were used to verify the effectiveness of the GPR method. The prediction accuracy of the GPR method was compared with those of other methods like GC, ANN and SVM. In addition, we also compared the prediction accuracy of different kernel functions to select the best kernel function for GPR. The kernel functions considered are exponential function, squared exponential function, rational quadratic function and Matérn function. The results showed that GPR method is accurate and applicable for analyzing the behavior of gas-liquid two-phase flow through wellhead chokes, and GPR method with exponential kernel function could achieve greater prediction accuracy than other kernel functions.

Prediction of two phase flow behavior and mixing degree of liquid steel under reduced pressure

The behavior of gas-liquid two-phase flow in a vessel under reduced pressure was evaluated, and the deviation between the theoretical and measured concentration in the ladle was measured using a water model. The fluid flow trajectory and mixing behavior between the fresh and stale solutions in the vessel under different degrees of vacuum were predicted. The flow in the up-leg changed from a dispersed bubble flow regime to a coalescence bubble flow regime as the degree of vacuum decreased. After reaching the ultimate degree of vacuum, the flow was a discrete bubble flow regime if the amount of liquid in the vacuum chamber was greater than the processing capacity of the chamber. There were many dead zones and local circulation phenomena in the ladle. Even in the best mixing case in the experiment, there was an obvious deviation between the measured and theoretical conductivity values in the upper part of the ladle, and the difference increased as the degree of vacuum decreased.

Numerical investigation of gas-liquid two-phase flow in horizontal pipe with orifice plate

Gas-liquid two-phase flow in horizontal or vertical pipeline significantly impacts on the transportation process. In fact, in the pipeline for regulating the flow flux or pressure, orifice plate and other current limiting device are frequently encountered. The flow behaviors of two-phase flow thus become more complicated in the pipeline with orifice plate. In order to explore the characteristics of gas-liquid two-phase flow in the pipeline accompanied by orifice plate, the computational fluid dynamics (CFD) simulation with volume of fluid (VOF) method and SST k−ω eddy viscosity model were imposed to probe the transient two-phase flow in a horizontal pipeline. The reliability of the numerical method was verified by a case of annular multiphase flow in a pipeline. In our research, two transient simulations related to different liquid volume ratios were carried out to explore the developments of the flow regimes. In addition, fluctuations of the area-average fluid pressures acting on the orifice plate surfaces were also monitored. The frequency characteristics of pressure pulsations were extracted via non-uniform fast Fourier transform (NUFFT). The main results show that the jet could be produced after the liquid passes through the orifice plate, and the liquid volume ratio has significant effects on the gas-liquid two-phase flow behaviors, a higher ratio leads to a faster stable and fuller jet. The stability of jet could be reflected via the dimensionless velocity ratio. The gas-liquid two-phase flow in the pipe with orifice plate induces typical broadband excitation.

Prediction and management of hydrate reformation risk in pipelines during offshore gas hydrate development by depressurization

The hydrate reformation in marine gas hydrate production system can significantly affect the accuracy control of the production pressure differential and even cause pipeline blockage problems. In this paper, a transient temperature and pressure calculating model was established to predict the risk of hydrate reformation in production pipelines during offshore gas hydrate development, which considering the coupling interactions between the real-time drainage of electric submersible pump (ESP), the downhole preheating of electric induction heater (EIH), the wellbore multiphase flow and heat transfer. Using the model, the dynamic evolution laws of gas–liquid two-phase flow behaviors in different pipelines of mixed transportation, drainage and gas production were studied. Furthermore, the region of hydrate reformation in production pipelines was predicted quantitatively. The results indicate the risk of hydrate reformation in the drainage pipe is the highest relative to other pipes, and the main flow pattern in this pipe is bubbly flow. Besides, the conventional hydrate management method through inhibitor injection was applied to prevent the hydrate reformation. It can be found that the required Ethylene glycol (MEG) minimum concentration reaches 22% in order to completely eliminate the risk of hydrate reformation. To this end, a new hydrate management strategy by adding additional pumps and heaters was proposed, and the prevention effect of hydrate reformation in different scenarios was discussed in detail. The simulated results demonstrate that this method can effectively address the potential hydrate reformation risks without the use of inhibitors. This work will provide theoretical references for the hydrate flow assurance operations in marine gas hydrate production testing.

Multilayer limited penetrable visibility graph for characterizing the gas-liquid flow behavior

The research of the dynamical flow behavior of gas-liquid two-phase flow remains a challenge of great importance. We first carry out the vertical upward gas-liquid two-phase flow experiment in a 50 mm inner-diameter pipe and capture flow information via four-sector distributed conductance sensor. Then, we develop multilayer limited penetrable visibility graph (MLPVG) to analyze multichannel measurements, aiming to characterize the complicated flow behavior. We calculate two projection networks of MLPVG from two different perspectives (i.e. the overlapping information and the whole information). The ratio between the global clustering coefficients of these two projection networks is calculated as a quantitative indicator to characterize the multilayer network. We find that the proposed multilayer network measure can effectively characterize the evolution of gas-liquid flow, from randomly dispersed bubbles to periodically arisen gas slugs. The results suggest that our method can effectively fuse multichannel measurements and reveal the evolution of the complicated flow behavior.

Fundamental study on chaotic transition of two-phase flow regime and free surface instability in gas deaeration process

Deaeration is a process of eliminating aspirated air from liquid in hydraulic reservoirs to avoid cavitation in the downstream pump blades. The complex fluid dynamics associated with deaeration is investigated. The three-dimensional buoyancy driven chaotic behavior of gas-liquid interfacial two-phase flow is studied. Parametric study is executed to understand change in internal flow physics (bubble coalescence, disintegration, horizontal spread, bubble velocity etc.), strength of accelerating Rayleigh-Taylor instability, turbulent kinetic energy, amplitude of upward velocity near free surface, and rise in free surface level with the variation of parameters like incoming mixture flow rate, incoming volume fraction of air, liquid fill depth, and Atwood number. The computations show increment in cavitation, wavenumber and amplitude of upward velocity towards oscillating free surface with incoming flow rate (Re). Cavitation and free surface instability show incremental trend with volume fraction of incoming air forming a kink (cavitation reduces) due to bubble coalescence in a threshold range of volume fraction of incoming air. With the variation of Atwood number, initially cavitation reduces. But after a critical value (A*) of Atwood number, effect of bubble disintegration, and rise of cavitation become prominent, which is formulated with respect to incoming flow rate (Re). With liquid fill depth, cavitation shows a slight decrement with almost equal deaeration and constant wavelength of free surface oscillation at an increasing buoyancy driven upward velocity. Some glimpse of design solution to reduce the cavitation and enhance the deaeration is also studied and formulated to get better understanding.

Influence of the Diffusion Media Structure for the Bubble Distribution in Direct Formic Acid Fuel Cells

Direct formic acid fuel cells (DFAFCs) have received considerable attention because they can generate a higher power density compared to other direct liquid fuel cells. However, when generated CO2 bubbles are retained in the anode’s porous transport layer (PTL), the performance of the DFAFCs deteriorates. The gas–liquid two-phase flow behavior within a PTL is not clear; therefore, in this work the power-generation characteristics of DFAFCs using two types of PTL, carbon paper and carbon cloth, were investigated. It was found that the maximum current density was approximately 60 mA cm−2 higher with the carbon cloth than with the carbon paper. The CO2 bubble distribution in the anode’s PTLs was visualized by X-ray computed tomography and discuss the effects of the bubbles on the power-generation performance of DFAFCs. We found that interstices in a carbon-cloth PTL provided pathways for bubble migration and release to the channel, so that the bubbles did not deteriorate the power output. Bubble accumulation in a carbon-paper PTL led to a drop in power output, confirming that the structure of the PTL and the CO2 bubbles affect the power-generation characteristics.

Numerical simulation of gas-liquid two-phase flow in gas lift system

The gas-lift system has a lot of significant advantages in sewage treatment, deep well oil recovery, liquid metal cooled reactor and magnetohydrodynamic power converters. The densities of different liquid media and gas media have great influences on the performance of gas lift system. Therefore, based on Fluent simulation software, using Euler model and <i>k</i>-<i>ω</i> SST (shear stress transport) turbulence model, the gas-liquid two-phase flow behaviors in nitrogen-water, nitrogen-kerosene, nitrogen-mercury and air-water, argon-water, nitrogen-water of gas lift system are studied. The rules of gas volume fraction and liquid flow rate at lifting pipe, liquid radial velocity at lifting pipe outlet, promoting efficiency are analyzed. The results are shown as follows. 1) In the nitrogen-water, nitrogen-kerosene and nitrogen-mercury system, the higher the density of liquid medium, the smaller the gas volume fraction in the lifting pipe is; the greater the flow rate of lifting liquid, the higher the promoting efficiency is. 2) In the air-water, argon-water and nitrogen-water systems, the higher the density of gas medium, the smaller the gas volume fraction in the lifting pipe is; the larger the flow rate of lifting liquid, the smaller the peak value of promoting efficiency is. 3) With the increase of gas flow rate, the liquid radial velocity at the lifting pipe outlet increases with overall fluctuation rising. Finally, the liquid velocity near the center of pipe axis is large, near the pipe wall is small. These research results provide the scientific theoretical basis for optimizing the gas lifting technology in applications such as sewage treatment, deep well oil recovery, liquid metal cooled reactor and magnetohydrodynamic power converters.

Experimental and Numerical Study on Gas-Liquid Two-Phase Flow Behavior and Flow Induced Noise Characteristics of Radial Blade Pumps

Miniature drainage pumps with a radial blade are widely used in situations with critical constant head and low noise requests, but the stable operation state is often broken up by the entraining gas. In order to explore the internal flow characteristics under gas–liquid two phase flow, pump performance and emitted noise measurements were processed under different working conditions. Three-dimensional numerical calculations based on the Euler inhomogeneous model and obtained experimental boundaries were carried out under different inlet air void fractions (IAVFs). A hybrid numerical method was proposed to obtain the flow-induced emitted noise characteristics. The results show there is little influence on pump characteristics when the IAVF is less than 1%. The pump head slope degradation was found to increase with air content. The bubbles adhere to the impeller hub on the blade’s suction side and spread to the periphery with a big IAVF, leading to unstable operation. It is obvious that vortices appear inside the impeller flow passage as IAVF reaches 6.5%. The two-phase flow pattern has a small effect on the characteristic frequency distribution of pressure fluctuation and emitted noise, but the corresponding pulsation intensity and noise level will increase. The study could provide some reference for low noise design of the drainage pump.