Journal Of Applied Fluid Mechanics
Volume:15 Issue: 2, Mar-Apr 2022

The numerical simulation of temporally accelerated flow subjected to Favorable and Adverse Pressure Gradients (FPG & APG) is represented. Two accelerations are considered and imposed on fully turbulent flow over a flat plate. The γ-SST model is implemented to define the boundary layer development, turbulence structures, and the wall functions responses to the external accelerated flow. The obtained results illustrate that the FPG condition accompanied by temporal acceleration can severely damp the fluctuations. So, an almost-laminar boundary layer develops near the wall, followed by a retransition to the higher turbulent state. However, the APG condition provides higher turbulence diffusion in a temporal accelerated flow. It makes the flow more orderly and more stable, although a re-laminarization is observable in this region excessively. Moreover, the applied condition disturbs the Reynolds stress correlation and generates semi-elliptic eddies because acceleration affects wall-normal fluctuations more severely than the streamwise ones. Also, a new represented acceleration parameter for this condition is compared with the acceleration parameter in spatially accelerated flow.

Experiments and numerical simulations are performed to study the cold flow field characteristics in a two-stage axial swirl combustion chamber. Large eddy simulation with dynamic turbulent kinetic energy sub-grid scale model is used to calculate the flow field, and particle image velocimetry is used to measure the turbulent flow field. The calculated results are found to be in a good agreement with the experiment results. Due to the shear layers and the density difference between CO2 and air flows, the central recirculation zone appears. With the increase of the ratio of flow velocity between inner and outer tubes, the central recirculation zone shrinks gradually, while the length and range of the angular recirculation zone increase continuously. The vortex structure develops in the axial and radial directions, and the vortex breakdown mostly occurs in the upstream regions. However, outside the central recirculation zone, only one shear layer is observed, and its vortex structure is almost extended up to the exit of the combustion chamber. In addition, precession vortex core is not seen in all the conditions.

In this manuscript, the analysis of buoyancy-driven heat transfer of copper-alumina/water hybrid nanofluid in a U-shaped enclosure under the influence of cavity inclination is extensively studied numerically. The dimensionless governing equations are formed by using dimensionless variables. The domain is discretized to a finite number of the Lagrange three-node triangular element, and the finite element method is employed with the Galerkin-weighted residual algorithm to compute and solve the problem. The Newton-Raphson method is employed as a convergence criterion for each iteration. Numerical and experimental validation of the previously published data is conducted with the present results to verify the stability and reliability of the numerical procedure and results. The effect of the lid tilting angle on the heat transfer performance of the enclosure is extensively explored in the manuscript. The streamlines, isotherms, local and average Nusselt numbers as well as the vertical and horizontal velocity of the fluid are plotted for a variation of the Rayleigh number up to 106. The analysis of the effect of fluid velocity on the fluid flow and thermal distribution pattern are discussed with relation to the overall heat transfer capability within the domain. It is found that hybrid nanofluid enhances the heat transfer rate within the enclosure. The highest heat transfer performance is at an inclination angle of 40°≤Θ≤ 60°. The results presented in the manuscript will be useful in the manufacturing processes involving electronics such as laptops and smartphones.

The blade inclination angle of soybean milk machine is a key geometric parameter for efficient crushing. For the purpose of obtaining optimal design, the gas-liquid two-phase flow field inside a soybean milk machine is simulated. The gas holdup from simulation is in agreement with the experiment. The simulation result shows that the lower blade A has a great influence on the internal flow field of soybean milk machine, while the upper blade B has a small influence on the flow field. As the angle l αA l  increases, the peak value of radial velocity decreases and moves to the interior of the cavity, so does the total pressure. When αA changes from -24° to -26°, the velocity vector at the bottom of the cavity changes from the connected state to the separated state, and the pressure difference between the up and the bottom surface of blade A becomes large. When αA = 24°, the flow field has the strongest turbulent kinetic energy and dissipation. When αB =28°, the pressure difference reaches the maximum. In summary, the best inclination angles are αAopt =-24° ∼ -26° and αBopt =28°, respectively.

Hydraulic systems are extensively used in industries. However, these systems must be free of contaminants to ensure their durability. When the contaminants entering the system are not removed with a suitable filter, sensitive parts such as pumps, motors, and actuators would be damaged. Therefore, hydraulic filters are critical elements in hydraulic systems. In this study, the flow and pressure drop in hydraulic filters were investigated experimentally and numerically. Although the main function of this device is to filter oil, it has many other functions in the system. Experiments were performed at eight Reynolds numbers in the range of 1250 ‒ 2350 at a constant viscosity. In the experiments, the pressure between the inlet and outlet of the filter was measured differently. The numerical results were used for detailed analysis of the flow after experimental verification. The analyses were performed using eight Reynolds numbers at laminar boundaries to examine the flow in the hydraulic filter. The results show that all surface areas of the filter element are not used homogeneously for fluid passage. The resultant pressure drop is due to the Dean vortex formed at the outlet of the hydraulic filter. The findings of this study can help better understand the flow recirculation regions that produce pressure drops and contaminant accumulation regions throughout a hydraulic filter from the inlet to the outlet of the flow path.

Determining the flow structure in the flanged diffuser shrouding designed to be used for a wind turbine, plays a vital role in improving efficiency in small-scale wind turbine technology. In this study, the flow structure in the curved type flanged diffuser was investigated in terms of water flow velocity increase, by using particle image velocimetry (PIV) measurements. The dimensionless magnitude of the resultant velocity determined at downstream and up radial regions as well as at the flange downstream of the curved type wind turbine shroud, revealed that resultant velocity was increased by a factor of 1.5. This increase of the wind velocity will result the wind energy interacting with the rotor blades to be enhanced by 3.38 times more. By the designed shrouding component to be used in micro wind turbines, it is also aimed to start the power generations in these types at a lower value of cut-in wind speed value.

Analysis of the velocity gradient of flocculators through Computational Fluid Dynamics (CFD) simulation can be essential to the optimization of hydraulic conditions in Water Treatment Plants. This study aims to simulate the velocity field in the last tank of a perforated tray-type flocculator and quantify locally velocity gradient (G) through CFD. This stage of flocculation has a higher risk of flocs rupture when there are not adequate conditions. Thus, simulations occurred at the flocculator current operational flow rate (7 ls-1), and at full capacity (9 ls-1). An alternative cost-effective and easy to implement modification was tested by increasing the number of orifices in the flocculator trays. As result, the velocity field indicates the formation of dead zones at the edges of the tank for all simulations, which facilitates short circuit occurrences. This is an indicator of reductions in water treatment efficiency. After structural modifications, simulations indicate a reduction in dead zone areas. Plus, as the flow rate increases, the maximum G inside the structure increases considerably (184 to 266 s-1), causing a risk for floc rupture. However, changing the number of orifices from 22 to 33 creates conditions for the flocculator to operate at higher flow rates without increasing the velocity gradient.

The sloshing phenomenon occurs in partially filled tankers due to sudden movement can affect the tank structure integrity and impair the dynamic stability of the tanker. The effects of sloshing phenomena in a spray mixture tank due to acceleration or deceleration of the agricultural vehicle is investigated under three filling levels of 25%, 50%, and 75%. The pressure time distributions on the tank wall were evaluated by using a multiphase transient model (water and air as an ideal gas) and a free surface flow in a homogeneous model. It was possible to verify the wave behavior of sloshing. The condition of 75% tank filling volume generated the highest pressure on the tank wall. The effectiveness of two types of vertical baffles in suppressing pressure was numerically investigated. Shear stress on the tank bottom wall under these proposed arrangements was analyzed by steady-state models and mechanical agitation, considering a filled tank. The proposed solution based on two partial vertical baffles and a central gap was the most effective. It promotes the higher reduction of wall impact pressure and other sloshing instabilities and maintains similar results of mixture agitation of the tank without baffles.

Unstart/restart phenomena induced by backpressure in a general inlet with a freestream of M = 2.7 are investigated in an in-draft supersonic quiet wind tunnel. The boundary layers are turbulent on the forebody while are laminar on the lip wall, which could mimick real flight conditions. The high-speed Schlieren imaging system and the nanoparticle-based planar laser scattering (NPLS) method are used to visualize the inlet flowfield. The inlet wall pressure is measured by high-frequency pressure transducers. The backpressure is reproduced by downstream transverse jets other than mechanical throttlers, which is more suitable to mimic backpressure caused by combustion. The high spatio-temporal resolution full-view images of inlet flow features during the complete unstart/restart process are captured, which are seldom seen before. The formation and disappearance process of massive boundary layer separation at the entrance of the unstarted inlet is observed. The backpressure transmits upstream through the shock wave/boundary layer interaction (SWBLI) regions. The shock structures change the angles and merge upstream to balance the pressure rise. The Mach shock reflection configuration is observed in both unstart/restart process, accompanied by the boundary layer separation extending to the leading edge. The experiment also revealed notable hysteresis in the unstart/restart process.

In this study, a novel fluidic jet actuator is designed to control flow separation on a NACA0015 airfoil at various angles of attack. The U-shaped jet actuator has two rectangular slots implemented near the leading edge of the airfoil. It is driven by a piston mechanism and operates at three excitation frequencies. Depending on the motion of the mechanism, a synchronized jet flow is generated by blowing and suction at the dual exits of the actuator slots. The experimental studies are carried out in a subsonic wind tunnel. The unsteady 2D Computational Fluid Dynamics simulations are performed by Detached Eddy Simulation with the SST k-ω turbulence model where measured jet velocities at the exits of the actuator slots are imposed as boundary conditions to mimic motion of the piston. The results at the on-mode and off-mode of the actuator are evaluated in terms of surface pressure coefficient distributions on the airfoil and averaged aerodynamic force coefficients. At low angles of attack, there is an adequate match between numerical and experimental results for the base flow without any control. At higher angles of attack, flow separation becomes considerably dominant and stall prevention by active flow control is detected especially at high excitation frequencies‎.

The objective of this research is to numerically investigate heat transfer and pressure drop characteristic ‎of a baffle assisted multi-jet impingement of air on a heated plate subjected to constant heat flux and ‎cross flow. Two baffle configurations were considered for the present study. An array of jets with 3 x 3 ‎configurations discharging from round orifices of diameter D=5 mm and with jet-to-heated plate distance ‎ranging from 2D to 3.5D were studied. SST k-ω turbulence model was used for numerical simulation to ‎examine the effect of blow ratio and baffle clearance on heat transfer and pressure drop characteristics. ‎Blow ratios of 0.25, 0.5, 0.75 and 1.0 and baffle clearances of 1 mm, 2 mm, and 3mm were considered ‎for CFD simulations. The split baffle configuration with baffle clearance of 3 mm is found to be more ‎advantageous when both heat transfer and pressure drop are considered. However, the segmented baffle ‎configuration with a baffle clearance of 1 mm gave better results for heat transfer alone. The present ‎study also deals with determination of optimal operating parameters with the help of Genetic Algorithm ‎and Artificial Neural Network. A pareto front was obtained for selecting the desired value of heat transfer ‎or pressure drop. It was found that Artificial Neural Network based predictions strongly agree with CFD ‎simulation results, and hence seems to be very useful in arriving at the optimum values of operating ‎parameters‎.

To improve the prediction accuracy of the surrogate model and reduce the calculation cost for hydraulic optimization design of centrifugal pump impeller, an inverse design and optimization method based on adaptive proper orthogonal decomposition (APOD) hybrid model was proposed. Initial samples were designed by perturbing blade control parameters of the original model. The samples were classified using the K-means clustering algorithm, and the adaptive samples were selected according to the category of the objective sample. The snapshot set is composed of blade shape parameters and the CFD flow field data in impeller, which is decomposed into a linear combination of orthogonal bases by the proper orthogonal decomposition (POD) method to predict the objective parameters. According to the objective load distribution, the low specific speed centrifugal pump was inversely designed by using the APOD model, and its initial blade was obtained. And then, the flow field corresponding to disturbed blade shape was predicted using the APOD method, so as to evaluate the gradient of the objective function to design variables. Finally, the initial blade was optimized by the gradient descent method. The results show that the APOD hybrid model method can be employed to accomplish the blade inverse design and the flow field prediction in the optimization design of centrifugal impeller, which significantly reduces the numerical calculation cost and improves the accuracy of the flow field prediction.

To assess unsteady vortex interaction between rim seal purge flow and upstream stator, numerical ‎investigations were conducted under different purge flow rates. The vortex distributions for the stator and ‎cavity were investigated and the interaction processes near the cavity exit, in particular the vorticity ‎change resulting from the ingress and egress, were analyzed. Results show the intensity of hub passage ‎vortex (HPV) and hub trailing shedding vortex (HTSV) at stator exit is decreased as a consequence of ‎enhancing blockage effects caused by the egress flow. However, when the purge flow rate increases, ‎from stator exit to downstream of cavity exit, the reduction in the intensity of two vortices is weakened as ‎the extrusion of egress flow thins their vortex tubes. The vortex inside the cavity is generated as the ‎combined effect of relative rotation of cavity walls and non-uniform circumferential pressure mainly ‎imposed by upstream stator. The ingress leads the positive axial vorticity near the stator hub to ingest into ‎the cavity and eject into the main passage due to the blockage of purge flow. Furthermore, the interaction ‎between the ingress of the mainstream and purge flow produces local negative axial vorticity. The egress ‎flow carries negative axial vorticity mainly originated from the rotational cavity wall, and enters into the ‎main flow passage near the rotating hub, then locations of HPV and HTSV move to the mid-span slightly ‎with the extrusion of egress flow‎.

The ducted fuel injection strategy is a method that significantly reduces soot emissions in direct injection compression ignition engines. Fuel is injected into the combustion chamber through a duct enhancing the air-fuel mixture. It guarantees more efficient combustion and less soot formation by reducing the equivalence ratio at the autoignition zone inside the combustion chamber. The effects of the duct fuel injection on the performance, combustion, and emission of the compression ignition engine were numerically investigated in this study. The duct geometries with varying diameters, lengths, and stand-off distances were examined to find the most appropriate size using an experimentally validated CFD model and detailed soot model. Results show that up to 66.7% reduction in soot emissions were observed with the usage of the ducted fuel injection strategy compared to conventional diesel combustion. In addition to reducing soot emissions, the ducted fuel injection strategy decreased CO and HC emissions by 20.4% and 7.8%, respectively. While the ducted fuel injection strategy reduces emissions, it does not decrease engine performance; on the contrary, it increases gross IMEP by 0.58%.

In this paper, an analytical investigation and 3D numerical simulation are presented for the breakup of floating non-Newtonian droplets in a non-Newtonian fluid. The considered geometry is a T-junction with unequal-width branches that can generate droplets with un-equal size. There is a very good agreement between the analytical solution and numerical simulation results obtained in this research. Various quantities such as branches flow rate ratio, branches velocity ratio, droplet’s length in each branch, the whole length of the droplet, vorticity and pressure have been investigated during the breakup process in this study. The results showed that the branches flow rate ratio and the branches velocity ratio were constant during the breakup process. It was also observed that the length of the droplet in each of the branches and the whole length of the droplet increased linearly during the breakup process. Also, the vorticity has its maximum at the breakup moment. ‎‎

When the hydrostatic workbench is running under high-speed overload conditions, the friction by-product is partially placed, causing the micro-gap oil film to be smaller, and the tribology is exposed. The oil film morphology of hydrostatic workbench directly affects its lubrication performance, and the oil film morphology is determined by deformation of bearing friction pairs and the oil film morphology is extremely difficult to obtain. This study will provide an acquisition method for the oil film morphology through the deformation of the bearing friction pair, and the deformation prediction of hydrostatic workbench having double rectangular cavities in heavy type vertical lathe has studied based on ANSYS WORKBENCH, and these are helpful to further investigate oil film shape under the working conditions of high-speed and heavy-load. The oil film clearance test rig was established, and the simulation results were verified, which verified the effectiveness of the proposed numerical simulation method. It can be concluded that the rotational speed has a greater impact on the oil film thickness than that of load, and the oil film thickness of downstream side is smaller than that of upstream side, and oil film thickness changes more quickly inside of oil sealing edge than that of outside, and the friction behavior and failure mechanism of this kind of bearing are proved.

Two models are compared for calculating the surface separation in a multiscale elastohydrodynamic lubricated line contact for the same operating conditions. In the studied line contact, the surface separation is very low so that the effect of the adsorbed boundary layer is significant. Model I principally takes the continuum fluid film as intervening between the two adsorbed boundary layers. Model II takes the continuous phase transition both along the flow direction and across the whole surface separation; in this model, in the Hertzian contact zone there is only the adsorbed boundary layer, while in most of the inlet zone there is only the continuum fluid film (by neglecting the adsorbed boundary layer). The analytical results show that for the same case these two models give the close surface separations. The equivalence of these two models is shown.

A hybrid Reynolds-averaged Navier-Stokes (RANS) large eddy simulation (LES) method is applied in this work. It called very-large-eddy simulation (VLES) turbulence closure model. The aim of this present study is firstly to validate the accuracy of this method for a specific engineering application (a trapped vortex combustor) and secondly to describe its flow characteristics. The trapped vortex combustor is a new concept that utilizes a large recirculation vortex to stabilize the flame. An accurate prediction of the turbulent flow is meaningful for the trapped vortex combustor. The time-averaged velocity, root-mean-square (rms) velocity, and flow pattern are compared with the experimental data. And the LES model, RANS BSL k-ω model, and RANS k-ɛ model are also applied for the simulation with different mesh resolutions. The results show that the VLES BSL k-ω model provides improved accuracy for velocity prediction. The classical large vortex structure for the trapped vortex combustor is captured qualitatively by the VLES BSL k-ω model also. In addition, the vortex breakdown and processing vortex cone are visualized using the Q-criterion. Furthermore, the VLES BSL k-ω model is not sensitive to the gird resolution. The VLES method is able to predict the turbulent flow of trapped vortex combustor relatively well‎.

This paper aims to investigate numerically linear stable waves at low wave steepness in shallow water using ANSYS Fluent software. The authors mainly determined how, when, and where a linear wave will reach its stable state in shallow water. The finite volume method is used to solve the Navier-Stokes equations. The inflow velocity method and the Dirichlet boundary condition are used to generate a suitable linear wave. Numerical damping is used at the end of the tank to reduce the reflection of the wave. The accuracy and stability of the waves are judged under wave height variation between the CFD results and the analytical results. The test has been conducted in four different cases (Case 1, Case 2, Case 3, and Case 4). Wave evolution and particle velocity are obtained in the velocity field to understand the wave stability in the numerical wave tank. Numerical data are captured from the free surface to compare the surface profile and wave velocity. The results have revealed that the accuracy, stability, and consistency of the linear waves are in good agreement with the analytical solution.  The relative error between the two results is 1.43% for Case 3. This research is a highly relevant source of information in realistic wave generation to design various practical systems such as wave energy converters, offshore marine structures, and many ocean engineering problems‎.

This study proposes and investigates the impact of a modification, accounting for the influence of vortices and flow properties on the liquid rupture, to improve the modeling of mass transfer rate in cavitation.  The threshold phase-change pressure is calculated by the fluid-saturated pressure at rest and the added vortex pressure term. The explicit simulation of the fully turbulent, homogeneous compressible, cavitating flow around the NACA0015 hydrofoil and the hemispherical body is performed. Saito cavitation model and Wilcox k-ω turbulence model are implemented for the evaluation of the proposed modification. The pressure coefficient distribution -Cp and cavitation behavior, including the vapor formation-collapse processes and the flow mechanism, are investigated. The analysis shows that the present modification, coupled the local flow viscosity with the vorticity magnitude, making the cavitation model better sensitive to the flow condition. The modification has a weak impact on the steady sheet cavitation around a hemispherical body but is the key factor underlying the improvement in the predicted complex flow around the NACA0015 hydrofoil. In that, the predicted -Cp and cavity structure around the hydrofoil is improved in comparison with the existing numerical data by other research groups and that by the Singhal turbulent pressure fluctuation model‎.

This research aims to investigate the vortex breakdown zone, the stability margin, and the fluid layers of the rotating flow between two vertical coaxial cylinders under the effect of thermal gradient and an axial magnetic field. The governing Navier-Stokes, temperature, and potential equations are solved using the finite-volume method. Three combinations of aspect ratios (γ) and Reynolds numbers (Re) are compared. The pumping action sets up a secondary circulation along the meridional plane of the annular gap. For certain combinations, the vortex breakdown bubble occurred near the inner wall. Bifurcation in form of multiple fluid layers becomes apparent when the temperature difference exceeds a critical value. These fluid layers play the role of thermal insulation and limit the heat transfer between the hot top and cold bottom of the coaxial cylinders. Both the vortex breakdown and fluid layers could be suppressed by the magnetic field; the increasing of Hartmann number (Ha) would reduce the number of fluid layers. Diagrams represent the effect of increasing Richardson number (Ri) on fluid layers are established. Then stability diagrams corresponding to the transition from the multiple fluid layers zone to the one fluid layer zone for increasing Prandtl number (Pr) are obtained.

A numerical simulation of global heat transfer process in three types of micro-channel heat exchangers was investigated in this paper: spiral double-pipe micro-channel heat exchanger (DPHE), cross-plate micro-channel heat exchanger (CPHE), and shell and tube micro-channel heat exchanger (STHE). The inner tubes of all three heat exchangers have a diameter of 1 mm and are charged with CO2 as refrigerant. A detailed analysis of the heat exchanger's global heat transfer process was carried out, which is entirely different for different structures. The heat transfer characteristics of supercritical CO2 were analyzed by considering the operating pressure, the refrigerant mass flux, the cooling water mass flux, and the heat exchanger refrigerant inlet temperature. The relationship between the CO2 heat transfer coefficient (hCO2) and CO2 bulk temperature (Tb,CO2) was analyzed in detail. The pseudo-critical temperature (Tpc) mainly determines where the peak CO2 heat transfer coefficient occurs. When Tb,CO2 < Tpc , the rise in Tb,CO2  is accompanied by an increase in the heat transfer coefficient, which reaches a maximum when Tb,CO2 is a little bit higher than the pseudo-critical temperature, the heat transfer coefficient curve begins to decline as  Tb,CO2 continues to rise. Higher peak heat transfer coefficients can be achieved at higher pressures. Increased refrigerant mass flux always results in larger heat transfer coefficients. The influence of the refrigerant inlet temperature of the heat exchanger in the Tb,CO2 < Tpc  region on the heat transfer coefficient is more significant than expected. In this study, different flow patterns on heat transfer due to different structures were compared. The best heat transfer was achieved using a spiral double-pipe micro-channel heat exchanger (DPHE). It consistently reaches the highest heat transfer and the lowest outlet temperature under the same operating conditions‎.

The effect of inlet type and length on the flow field was considered computationally for seven cyclone separators. The turbulent model was described by the Reynolds Stress Model (RSM). The air-water interface in underflow pipe and the spatial distribution of particles were tracked by the Volume of Fluid (VOF) model and Discrete Phase Model (DPM), respectively. Comparison investigations showed that inlet type and length had important impacts on flow field of cyclone. The instability flow field and back mixing phenomena were eliminated in symmetric double-inlet cyclone. The turbulent dissipation is obvious with a short inlet length. When it increased to 1.25D/2, the area and intensity of the turbulent dissipation tended to be stable. The optimum cyclone is the symmetric double-inlet with inlet length of 1.25D/2. When the particle diameter was larger than 5 μm, the complete separation could be realized.

This work presents the results of the development of a vertical axis wind turbine composed of variable geometry, plane blades, applied in operations with low wind speeds. The new concept of vertical axis wind turbine with variable opening blades is presented as an innovative prototype where mechanical details are important for the natural control of the openings of the blades. Theoretical, numerical and experimental analyzes are performed in the turbine called DEC® with the aim of determining the aerodynamic characteristics. An analysis of the behavior of the DEC® turbine consists of a numerical study carried out to calculate or drag coefficient, considering a range of opening positions of the opening at each moment to determine the power coefficient. A second numerical approach is to analyze the moment caused by the interaction between all the turbine blades, in which the effects of energy dissipation caused by the flow mats are considered. Then, the theoretical, numerical results are validated by tests performed using a model in the open wind tunnel, where the prototype is subjected to different wind speeds while maintaining rotation control. Suggestions are made to improve the mechanical and aerodynamic design of the innovative prototype. Finally, the DEC® turbine is expected to serve as an inspiration for creating other mechanical forms of passive or active control to improve variable aerodynamics applied in low-speed conditions.

It is well known that the pantograph, which works as a complex component of high-speed trains, is an important source of aerodynamic drag and aerodynamic noise of a high-speed train (HST) that can affect HST performance, comfort for passengers, and quietness of nearby communities. Thus, comprehensive studies on aerodynamic characteristics including aerodynamic drag and aerodynamic noise obtained by the pantograph need to be conducted. This work presents the aerodynamic characteristics including aerodynamic resistance and aerodynamic noise generated by the prototype pantograph of a high-speed train running at a speed of 300 km/h using numerical techniques of improved delayed detached-eddy simulation (IDDES) and acoustic finite element method (FEM). Then, the structure of the original pantograph is modified by wrapping the insulators, and the base frame, so that aerodynamic resistance and aerodynamic noise may be reduced as expected. Numerical results obtained from the pantograph without modification, with two modifications to the original design i.e. the base frame, and the insulators, are discussed. Compared to the original pantograph, the two modifications of the pantograph at the base frame and the support insulators are conducive to reducing the aerodynamic drag of the pantograph. However, the results also show that the modified insulator may not achieve considerable success in noise reduction. Only the modified base frame shows that noise is reduced significantly. Therefore, this suggests that the pantograph with base frame modification is a better choice for resistance and noise reduction.