State Laminar Flow Research Articles

Timescale dependent homogeneous assembly of lipid-polymer hybrid nanoparticles in laminar mixing for enhanced lung cancer treatment

The homogeneity of core–shell structure lipid-polymer hybrid nanoparticles (HNPs) is crucial for efficient intracellular cargo delivery. While microfluidic techniques have been recognized for their capabilities in precisely controlling the size and drug encapsulation efficiency, there is little research exploring the impact of mass transfer behavior within microchannels on the homogeneous assembly process of HNPs. Here, we manipulated the laminar flow state within TrM device to achieve controlled assembly of HNPs and explored a timescale dependent assembly technique to ensure the homogeneity of folate modified HNPs (FHNPs). Our founding indicate that this method enabled the control over the growth kinetics of PLGA cores within a timescale (τgrow) of 1–15 ms. The homogeneous ligand assembly on the surface of FHNPs can only be achieved when τgrow exceeds the timescale of functional lipid coating (τcoating). Compared to conventional bulk mixing methods, this strategy significantly reduces the risk of heterogeneous assembly in FHNPs fabrication and ensures consistent reproducibility across batches. The homogeneous FHNPs (HFHNPs) fabricated through this method exhibit precise control over particle size (ranging from 75 nm to 150 nm), low polydispersity index, and consistent core–shell structure. Furthermore, this strategy enhances the density of available folate ligands on the surface of FHNPs. In subsequent in vitro and in vivo anti-tumor assays, the icariside Ⅱ (IS) loaded HFHNPs (IS@HFHNPs) exhibited enhanced cellular uptake and tumor accumulation behavior. the timescale dependent homogeneous assembly method for HNPs developed in this research presents a promising avenue for maintaining quality in the synthesis of self-assembly composite nanomecidine.

Numerical Implementation of Boundary Conditions on Bubbles in a Microchannel with Stationary Laminar Flow

Numerical Implementation of Boundary Conditions on Bubbles in a Microchannel with Stationary Laminar Flow

Analytical approximations of laminar flow states above a curved wall heated from below

An analytical framework is developed for estimating wall-bounded plane laminar flow states above curved walls subject to external shear and heating. The framework is applicable to arbitrary lower-wall geometries with arbitrary temperature prescriptions. The study relies on perturbation expansions of flow states with respect to the inverse of the dimensionless channel wavelength. Exact closed-form solutions are obtained for systems of perturbation equations up to the third order, which have the freedom to allow for any flow constraint. As an application of the analytical framework, we examine flow states above two specific instances of wall geometries with long channel wavelengths. The approximated flow states shed insights into morphologies of laminar convection states at low shear rates (i.e. low Reynolds numbers).

Thermo‐hydraulic analysis of wavy microchannel heat sinks with porous fins based on field synergy principle

AbstractIn order to enlarge the area and intensity of convective heat transfer among the coolant and heated surface, the vertical fins of microchannel heat sinks (MCHSs) with microencapsulated phase change material slurry (MPCMS) as coolant are arranged into wavy porous channels to realize more heat being dissipated to the outside. The phase transition of microencapsulated particles in laminar flow state is described, and the Brinkman–Forchheimer–Darcy model based on volume average approach and the energy equation for local heat equilibrium are adopted to portray flow and heat transfer in porous medium. The impacts of geometrical parameters on flow and heat transfer behaviour of wavy porous MCHS are numerically analyzed, and performance evaluation factor (PEF) is defined to estimate the thermo‐hydraulic capability of heat exchanger. The numeric outcomes match well with the experiments. Results indicate that MPCMS has a significant heat transfer improvement in the newly designed channel configuration compared with the coolant fluid flowing in the straight microchannel. Based on field synergy principle, the comprehensive capability enhancement mechanism of MPCMS in new MCHS is explored, and its superior thermal performance can be attributed to the improvement of the synergistic degree among flow and temperature fields, and its reasonable structural design can effectively improve the heat rejection capacity in the limited space.

Effect of finned configuration of circular tube based on fluid-structure coupling on hydrogen flow characteristics

Nuclear thermal propulsion has the characteristics of high specific impulse, large thrust, green and efficient, and is the primary choice of manned deep space exploration propulsion system. Because the circulating flow of propellant hydrogen in the internal pipeline of the engine is always affected by the harsh environment of high temperature and high pressure, it is very important to study the flow characteristics of hydrogen in the pipeline, the heat exchange characteristics of hydrogen and pipeline and the deformation characteristics of pipeline under heat stress. In this paper, the flow phenomena of hot hydrogen in round tubes in a laminar flow state were analyzed by numerical simulation with COMSOL Mulitiphisics6.0, and the fluid-structure coupling between hot hydrogen fluid and pipe was investigated by a multi-physics field. It is concluded that the smoother the inner wall of the pipeline is, the smaller the hydrogen flow velocity is, the smaller the surface pressure of the pipe wall is, and the smaller the fluid extrusion and impact deformation of the pipe in the typical pipe with the inner fin is. It inspires studying the application of hot hydrogen flow and pipeline configuration in nuclear thermal rocket engines, including improving heat transfer energy and uniformity.

Effect and mechanism of solution flow rate during interfacial polymerization on morphology and performance of hollow fiber membranes

Interfacial polymerization (IP) using m-phenylenediamine and trimesoyl chloride (TMC) is an essential method for producing thin-film composite (TFC) membranes. Nevertheless, IP is highly sensitive to changes in process parameters, especially the TMC solutions flow rate during inside-out TFC hollow fibers (HF) production. Research on the impact of flow conditions (i.e., laminar vs. turbulent flows) of these organic solutions on the final membrane characteristics and corresponding mechanism is still lacking. This research tested different TMC flow rates (0.1–2 mL/min) to produce inside-out TFC HF. With a TMC flow rate increase, (i) the leaf-like structures of the polyamide (PA) layer decreased in size, (ii) the thickness of the PA layer slightly increased, and (iii) the pure water permeability decreased. However, the elemental composition, chemical bonds, and NaCl rejection remained stable. Different fluid regimes are considered to affect the performance of HF membranes by affecting the heat dissipation process during IP reaction. A TMC flow rate in the laminar flow state (i.e., low flow rates) is recommended for synthesizing HFs. The current research provides new insights into the IP reaction mechanism of HF membrane, thus offering valuable guidance to optimize and produce membrane products with better performance.

Experimental study on flow-induced vibration under laminar flow and turbulent flow transition state in helical coiled tube

This study investigates the vibration characteristics induced by single-phase flow at low velocities within helical coiled tube, encompassing laminar and turbulent flow transition regimes. Modal experiments were conducted to ascertain the natural frequencies in the radial and vertical directions within the helical coiled tube. The influence of fluid mass in tube on vibration was considered, revealing the fluid mass has a greater influence on the vibration frequency in the vertical direction. When the coil was filled with water, the radial natural frequency decreased by 0.1 Hz, while the vertical natural frequency decreased by 0.8 Hz.By simplifying the spiral coil into a spring system, the intrinsic causes of the influence of mass on the natural frequency are studied and verified with the experimental data. The results show that the radial natural frequency is only related to the local mass change of the pipe, while the vertical natural frequency is related to the static deformation of the system under the influence of gravity.By conducting single-phase flow induced vibration experiments inside the pipeline, the radial and vertical vibration response characteristics were obtained, and the modal experimental results were analyzed. Findings indicated larger vibration displacements when laminar flow prevailed within the tube, with radial RMS (Root Mean Square) at 10.1 μm and vertical RMS at 14.5 μm. After the transition to turbulent flow, significant reductions in vibration displacements were observed, reducing the radial RMS to 2.3 μm and vertical RMS to 5.5 μm.Based on statistical and frequency-domain analysis methods, the influence mechanism of secondary flow on the vibration of helical coils at low flow rates was revealed, and the importance of friction coupling was clarified. Moreover, this study considered the impact of fluid viscosity on vibration response and experimentally validated the critical role of friction coupling in exciting secondary flows.

A Simplified Approach for Calculating Heat Transfer Coefficients for Fluid Guiding Elements with Alternating Redirections of Flow

AbstractFluid guiding elements (FGEs), additive manufactured inserts that enhance heat transfer, have shown the potential to reduce the size of pipe‐in‐pipe heat exchangers up to a factor of 20. Due to their unique design, the calculation of the geometrical parameters for a specific application remains challenging and was initially solved by computationally expensive computational fluid dynamics simulations. This work presents a simplified approach, which treats the fluid and the FGE as pseudo‐homogeneous to enable the fast calculation of effective heat transfer coefficients. The approach is developed based on water in laminar flow state and subsequently tested with different fluids.

Rock Breaking Mechanism and Process Optimisation of Jet Cutting Basic Roof Rock under Submerged Jet Condition

The destruction of rock under the condition of a close submerged jet has become a hot topic of scientific research and engineering application in the past decade. With the unremitting efforts of a large number of experts and scholars around the world, gratifying progress has been made in the research of computational fluid dynamics (CFD) on the internal and external flow fields of the jet nozzle, the theoretical derivation of rock mechanics on the fracture initiation and propagation criteria of hydraulic fracturing, and the numerical simulation of jet erosion mechanism under the coupling of fluid and solid fields, however, for the rock mechanics hydraulic fracturing cutting engineering scale of non-oil drilling fracturing technology, the research on the fluid-solid coupling boundary conditions of fracturing fluid and hard dense rock under the flow state conditions of the submerged field inside and outside the borehole is not sufficient. In the calculation of the fluid-solid coupling boundary flow field under the non-submerged jet state, the control equation with Reynolds number between 2300-4000 shall be selected, while it belongs to the laminar flow state in the stage of hole sealing and pressurised fracturing. Therefore, Von-Mises equivalent plastic stress is selected in the mechanical model to calibrate the failure state of the rock-solid boundary, and the control equations of laminar flow and turbulent flow are selected to calibrate the fluid boundary. The mechanism of different stages of rock breaking by hydraulic fracturing jet can be further analysed in detail, and Comsol 6.0 multi-physical field simulation software is selected for verification. The research results will help deepen the understanding of rock breaking mechanism by jet and optimise the selection of parameters for field construction.

A New Water Film Depth Prediction Model for Pavement Surface Drainage

The prediction of the water film depth (WFD) on the road surface can help with road skid resistance research and reduce the risk associated with driving on rainy days. At present, there are many empirical and analytical models based on drainage length, slope, rainfall intensity and other parameters. Considering the influence of road surface runoff and starting from the Reynolds number formula of road surface water flow, a new road surface WFD calculation formula that considers the movement state of laminar water flow is derived. The results show that the changing trends of various parameters in the prediction model (drainage length, rainfall intensity, road slope) affecting WFD are consistent with those of the existing model. It is also found that the initial water film depth, initial speed of rainwater, and rainfall angle have little impact on WFD. The predicted value of the model has a suitable matching degree compared with the classical empirical model, which provides a new approach to the prediction of road water film depth.

Flume experiments of gravity flows: Transformation from sandy debris flows to turbidity currents with clay matrix separation

Sandy debris flows and high-density turbidity currents are two kinds of gravity flows that have been interpreted to produce massive sandstone deposits, yet no consensus has been reached on the depositional mechanism how the deposits should be subdivided. To show differences in the deposits resulting from these two contrastive types of gravity flows, we designed flume experiments (with sand concentrations ranging from 35 wt% to 55 wt%) to examine how gravity flow states and their associated depositional characteristics vary according to their sand:clay ratio and the gradient of slope across which the flows move. The results show that: (1) gravity flows generally occur with two distinct flow layers, consisting of a lower homogeneous mass flow (debris flow) and an overlying upper turbulent cloud (turbidity current). This indicates that flow transformation from a debris flow to a turbidity current is facilitated by low sand content and high slope gradient; (2) the deposited sand bodies contain lower and upper layers which are characterized by inverse and normal grading, respectively, and these are directly related to the bipartite flow state; (3) laminae dip in the direction of flow within the lower sediment layer and are associated with shear forces within the debris flow. We call this laminated structure “laminar sheared layers” and consider this indicative of the laminar flow state that characterizes debris flows; (4) the process of mixing of the flow with ambient fluid causes the clay matrix to separate from the lower debris flow sediments and be subsequently incorporated into the upper turbidity current sediments. This is the cause of the flow transformation. These observations show clearly that sandy debris flows are capable of depositing clean sand bodies. Most significantly, this study demonstrates that the laminar sheared layers are the key sedimentary feature which allows differentiation between sandy debris flow deposits and high-density turbidites, and reveals the occurrence of clay matrix separation, which is important for predicting high-quality oil and gas reservoirs from submarine fan deposits.

Расчет коэффициента местного сопротивления при изотермическом течении неньютоновской несжимаемой жидкости в цилиндрическом канале с внезапным сужением

The engineering calculation and construction of the extrusion tool in the form of cylindrical forming channels with sudden narrowing is associated with the determination of the coefficient of resistance of sudden narrowing and local pressure losses. The available theoretical and experimental data on the values of the resistance coefficient of sudden narrowing are contradictory, approximate in nature and, in some cases, do not take into account the rheological properties of the liquid. Their use to calculate local pressure losses under laminar flow conditions leads to significant errors. To eliminate the indicated problems, a mathematical statement of the problem of isothermal stationary laminar flow of non-Newtonian non-compressible fluid in an axisymmetric channel with sudden narrowing was formulated. The mathematical model of flow in spatial formulation is formalized in the form of equations for preserving momentum and mass. As a rheological model, the Carreau model is taken, taking into account the presence of finite viscosity values at marginal shear rates. The numerical solution of the problem was performed by the finite element method using the Comsol MultiphysicsTM CFD modeling package. As a result of the solution, the picture of the current of the non-Newtonian medium was restored in the form of the distribution of current lines, kinematic and dynamic flow parameters. The impact of Reynolds number on change of geometric characteristics of flow structure, kinematic and dynamic flow parameters was evaluated. Values of local resistance coefficient and pressure losses for overcoming sudden narrowing for selected flow modes are calculated. The results of computational experiments are summarized in the form of a criterion ratio for calculating the coefficient of local resistances depending on the Reynolds number.

Influence of hemisphere disturbance on laminar boundary layer at low Reynolds numbers

We experimentally investigate the two-dimensional flow characteristics caused by hemisphere disturbance in the laminar boundary layer, with the aim of analyzing the periodic vortex structures generated by the hemisphere at different freestream velocities. For flow fields with Reynolds numbers of ReD= 1919, 2386, and 2819, instantaneous snapshots of the streamwise–wall-normal plane and streamwise–spanwise plane are acquired by time-resolved particle image velocimetry. The velocity distribution near the hemisphere model in the laminar flow state and the conditions for the generation of periodic structures are discussed. Strong shear occurs in the dense area of velocity contours, including a stable horizontal shear layer and inclined shear layer of shedding vortex structures, and the Reynolds shear stress attains a local maximum. The feasibility of three frequency extraction methods for hemisphere disturbance is also compared, and the periodic structures corresponding to each frequency are analyzed in detail. At higher values of ReD, the disordered flow field is formed by a multi-frequency superposition. Spatial two-point cross correlation analysis, which can be regarded as a flow visualization of frequency spectrum analysis, illustrates that the correlation and periodicity of the coherent structures are strongest in the inclined shear layer. Spectral proper orthogonal decomposition appears to be more effective in capturing periodic information about the streamwise–spanwise plane of the hemisphere disturbance. The three frequency extraction methods show that with an increase in ReD gradually transforms the periodic vortex structures from a single frequency state to a multi-frequency superposition state.

CO2 capture using superhydrophobic ceramic membrane: Preparation and performance analysis

The application of membrane absorption for CO2 capture has been limited by membrane wetting. In this paper, tubular Al2O3 ceramic membranes (marked as M1 and M2) are hydrophobically modified by sol-gel and dip-coating method and then used for CO2 capture. The surface morphology, surface composition, wettability and flux are characterized in detail. The mass transfer performance of M1 and M2 is studied at different gas and liquid Reynolds numbers. After modification, the surface contact angle can reach as high as 170.7°. The carbon capture performance of the modified M1 and M2 is significantly improved. Under laminar flow condition, CO2 mass transfer coefficient increased from the initial 1.03 × 10−4 m/s to 14.59 × 10−4 m/s, and the CO2 capture efficiency increased from the initial 28.55%–98.55%. The mass transfer resistance of ceramic membrane contactor is also analyzed. The resistance of liquid phase plays a leading role in the mass transfer performance in laminar flow state. For non-wetting membrane, membrane thickness has little effect on the mass transfer performance. In addition, it is shown that the superhydrophobic M1 and M2 exhibit excellent corrosion resistance. The research in this paper shows that superhydrophobic ceramic membrane is more suitable for CO2 capture in industrial production.

Thermal analysis of modified solar-driven dual-evaporation Kalina system

In order to fulfill the further cascade utilization of mid-grade heat source and high efficient energy storage, the concept of dual-evaporation pressure has been adopted into a modified Kalina co-generation system, with the spiral baffle inserting the whole space of the temperature difference storage tank. The relative static/dynamic mathematics simulation has been conducted, to optimize the whole system. The influences of key parameters on the thermodynamic performance of the cycle have been discussed, including circulation multiple, super-heat degree as well as work and basic concentrations of solution. The results show that higher value of circulation multiple represents a negative factor for the system, and the optimal value is adopted as 5. While under the same heat source temperature, lower super-heat degree means a higher turbine inlet temperature and pressure, which will increase the thermal performance of the whole cycle. In addition, there exists optimal working pairs for the cycle under discussed condition. When work concentration is set as 0.375, 0.4, 0.425, 0.45, 0.475, the optimal matching basic concentration is 0.227, 0.244, 0.26, 0.272, 0.293, respectively. The optimal case study of proposed cycle shows that the thermal and exergy efficiency are found to be 32.66 % and 74.49 %, which are 20.1 %/33.3 % and 1.1 %/27.2 % higher than those of dual-evaporation pressure or conventional Kalina cycle. The cycle acquires higher thermal efficiency by realizing proper ammonia concentration and suitable temperature-difference in phase change processes to match heat source and cooling water, with the set of two evaporators to make the discharge temperature of heat source lower (92℃). What’s more, by forming a spiral channel in the large space of the cylinder, the fluid is evenly distributed and stayed in a laminar flow state, in which way the effective and stable temperature stratification is realized, stably providing the fluid with higher temperature. The collector efficiency appears lower at noon, higher at morning and night. The highest collect efficiency could be 64.7 %, with the lowest be 53.7 %. The charging temperature of storage tank could be 416 ℃, and the charging time could be around 2 h. The appearance of storage tank inserting spiral baffle is considerably better than that of the traditional double tank, with lower charging/discharging time (25.2 %/20 % shorter in time) and more intense temperature difference (5.1 % higher in charging temperature). In general, with the increase of the super-heat degree as well as the circulation multiple, the solar-to-power efficiency decreases rapidly, which could be up to 19.9 %.

Experimental investigation and machine learning modeling of heat transfer characteristics for water based nanofluids containing magnetic Fe3O4 nanoparticles

The convective heat transfer coefficients of Fe3O4 magnetic nanofluids in both laminar and turbulent flow states inside a pipe were determined as base values and adequately simulated using machine learning techniques. Three selected machine learning methods for the simulations were Multiple Linear Regression Analysis (MLR), Radial Basis Function-Backpropagation (RBF-BP), and Least Squares-Support Vector Machines (LS-SVM). Initially, MLR was employed to fit the polynomial equation, followed by the selection of the best RBF-BP model with 6 hidden layer neurons using the grid search cross-validation method. For the LS-SVM model, a kernel function of 0.3 and a regularization parameter of 100 were used. By conducting a detailed comparison of the numerical patterns of the accuracy evaluation parameters, the RBF-BP and LS-SVM models were evaluated, with the LS-SVM model demonstrating superiority. The main parameters in the Reynolds number-mass fraction simulation were the mean square error (MSE) and regression coefficient (R2), which obtained specific values of MSE= 0.34 and R2 = 0.99994 under laminar flow conditions. Similarly, in the Reynolds number-magnetic field strength simplification, the best values for laminar flow conditions were MSE= 3.85 and R2 = 0.99993. The validity and accuracy of the model predictions were further demonstrated through visual comparisons of simulated and experimental values using Three-Dimensional smoothed surface plots. The groundbreaking discoveries hold the potential to catalyze advancements and foster significant progress in the fields of machine learning and nanotechnology. As a valuable resource, these results play a crucial role in propelling further research and development efforts, thus making noteworthy contributions to the continuous growth and innovation in these cutting-edge disciplines.

Research on the audible acoustic field-enhanced heat transfer of double-pipe exchangers: Effect of laminar flow and turbulence, vertical and horizontal placement of pipes

The acoustic field is considered an efficient and reliable technique for enhancing convective heat transfer. This study investigates the optimal experimental conditions of acoustic field-enhanced heat transfer using an experimental platform for convective heat transfer in a double-pipe exchanger. The experiment mainly explored the enhancement effect of the acoustic field on heat transfer by comparing laminar flow and turbulent flow states, as well as the arrangement of horizontal and vertical pipes. Meanwhile, acoustic wave frequency and inlet temperature of the thermal fluid were also considered as experimental variables. The results showed that compared to the horizontal pipe which has the best reinforcement efficiency at a frequency of 0.6 kHz, the vertical pipe in the laminar flow condition showed a high heat transfer capacity in the range of 0.6–0.8 kHz, with the best reinforcement efficiency reaching up to 43.6%. The significant heat transfer enhancement effect is mainly because 0.6 kHz is close to the acoustic resonance frequency, which further enhances the heat transfer effect. In the turbulent flow condition, the effect of the acoustic field on enhancing heat transfer is obvious when the pipe is arranged horizontally, and the reinforcement efficiency reaches a maximum of 24.5% at a frequency of 0.7 kHz.

Effect of Flow Velocity on Laminar Flow in Microfluidic Chips.

Gel fibers prepared based on microfluidic laminar flow technology have important research value in constructing biomimetic scaffolds and tissue engineering. The key point of microfluidic laminar flow technology is to find the appropriate fluid flow rate in the micropipe. In order to explore the influence of flow rate on the laminar flow phenomenon of a microfluidic chip, a microfluidic chip composed of an intermediate main pipe and three surrounding outer pipes are designed, and the chip is prepared by photolithography and the composite molding method. Then, a syringe pump is used to inject different fluids into the microtubing, and the data of fluid motion are obtained through fluid dynamics simulation and finite element analysis. Finally, a series of optimal adjustments are made for different fluid composition and flow rate combinations to achieve the fluid's stable laminar flow state. It was determined that when the concentration of sodium alginate in the outer phase was 1 wt% and the concentration of CaCl2 in the inner phase was 0.1 wt%, the gel fiber prepared was in good shape, the flow rate was the most stable, and laminar flow was the most obvious when the flow rate of both was 1 mL/h. This study represents a preliminary achievement in exploring the laminar flow rate and fabricating gel fibers, thus offering significant reference value for investigating microfluidic laminar flow technology.

Theoretical and Experimental Flow Characteristics of a Large-Scale Annular Channel in Terms of Deformation Gradient, Eccentricity, and Water Compressibility

Hydraulic water plunger pumps have come to be widely used in coal mining, seawater desalination, and oil exploitation due to their high output pressure and large flow characteristics. In a high-pressure large-flow plunger pump, the leakage of the annular channel of the plunger pair is an essential factor affecting volume efficiency. The axial pressure gradient exists in the fluid inside the annular channel, resulting in the plunger and plunger sleeve forming similar funnel-like shapes. Moreover, the characteristics of large diameter, high working pressure, and low fluid viscosity of the plunger pump will lead to the complicated flow of the annular channel. The influence of eccentricity and structural deformation on leakage is difficult to evaluate. Therefore, considering the deformation gradient and eccentricity of the plunger pair and the compressibility of the water, the deformation equations and leakage equations of the annular channel under the laminar and turbulent flow state are derived in this study. The eccentricity and leakage of the annular channel under different pressure conditions are measured using a built sealing test bench. It is proved that the discrepancy between the calculated model and the experimental results is less than 6% under different pressures, which effectively predicts the sealing performance of plunger pumps. The results show that under the laminar flow condition, the effects of eccentricity, structural deformation, and medium compressibility on leakage are 148%, 4.92%, and 0.92%, respectively. In turbulent conditions, they were 31%, 2.84%, and 1.19%, respectively. Besides, the reasonable material pairing of the plunger friction pair can reduce the variation of leakage due to structural deformation.

Effect of synthetic jet on circular cylinder radiated noise in laminar flow state

This article focuses on the effect of active control via synthetic jets (SJs) on sound generated by a two-dimensional circular cylinder by using the acoustic analogy method. The cylinder is immersed in a uniform upstream flow, where the corresponding Reynolds number is 100 and the Mach number is 0.1. A pair of SJs is placed near the cylinder’s separation point issuing periodically varying forcing, with different combinations of forcing frequency and phase difference. The lattice Boltzmann method (LBM) is coupled with the multi-direct forcing immersed boundary method to solve the near-field flow dynamics. The mechanism of the sound generation lies in the fact that pressure pluses are induced by the periodic vortex shedding from the cylinder’s surface, i.e. dipoles. In the case with active flow control, extra monopoles are generated by the unsteady flow rate resulting from the SJs' periodic blow/suction. The interaction between monopoles and dipoles is confirmed to have a big influence on the acoustic field. The acoustic analogy method is used in various cases with a wide range of control parameters, because it has a considerably lower computational cost than the direct simulation method. Taking into account the effect of the monopole, the acoustic analogy method is developed for solving two-dimensional sound field by substituting the Green’s function. Results indicate that the primary lock-on and the secondary lock-on occur in the case of specified control parameters. The frequency of vortex shedding is related to the SJs’ frequency, deviating from the unforced frequency. Owing to the noise induced by flow, the frequency and phase difference of the SJs also have significant influence on sound field. The far-field noise is enlarged although the SJs reduce drag, due to the induced extra monopole, as well as the strengthened hydrodynamic fluctuation. Further increasing SJs’ frequency or reducing the phase difference will enlarge the far-field noise and make the directivity transformed from dipole to monopole, since the SJs’ self-noise is stronger. Moreover, it is found that the acoustic power increases approximately 4–18 dB compared with the unforced circular cylinder and the drag dipole is strengthened in all combinations of control parameters. This study deepens the understanding of the effect of SJs on sound field, and provides a reference for future studying the control strategies of suppressing noise generated from bluff bodies.