Experimental Study Of Fluid Flow Research Articles

Simulation and Experimental Study of Fluid Flow and Solidification Behavior in Thin Slabs Continuous Casting Process under Secondary Electromagnetic Stirring

During the thin slab continuous casting process of silicon steel, electromagnetic stirring (EMS) can control the flow, heat transfer, and solidification of molten steel through electromagnetic force. Herein, a 3D mathematical model coupling the fluid flow, heat transfer, solidification, and the electromagnetic field is built. The effects of varied current intensities on the flow, heat transfer, and solidification of molten steel in the thin slab under secondary EMS are explored based on applying the electromagnetic brake in the mold region. In the findings, it is demonstrated that increasing the current intensity increases the flow rate and vorticity of the molten steel in the second cooling zone, eliminating the superheating phenomenon and improving the uniformity of the molten steel's temperature distribution. Meanwhile, based on the nucleation and growth parameters determined from thermal simulation experiments, the cellular automation finite‐element model is used to simulate the microstructure evolution during the solidification of thin slab. In the results, it is shown that the stirring energy increases when the current intensity increases, potentially promoting equiaxed crystal growth and grain refinement. Compared to the production sample, a reasonable qualitative agreement is achieved for the grain morphology, equiaxed crystal ratio, and columnar to equiaxed transition.

Experimental study of fluid flow and heat transfer of jet impingement in cross-flow with a vortex generator pair

The present paper investigates the fluid flow and heat transfer behaviors of jet impingement in cross-flow modified by a vortex generator pair (VGP). The velocity of the jet is kept at 12 m/s and that of the cross-flow is varied between 5 m/s and 8 m/s. The spacing between the jet and target surface is 4 times the jet diameter. Particle Image Velocimetry (PIV) and Liquid Crystal Thermography (LCT) are used to measure the flow field and heat transfer, respectively. The interaction of the cross-flow and jet produces various vortices, and the jet is shown to be deflected downstream by the cross-flow. The streamwise velocity of the jet increases with the cross-flow while the wall-normal velocity and turbulent kinetic energy are reduced close to the target wall. The overall effect is to decrease the impingement heat transfer. The presence of the vortex generator pair decreases the cross-flow momentum and induces the downwash flow upstream, which is favorable for the jet penetration. Thus the jet has higher impinging velocity towards the wall with elevated turbulent kinetic energy. This explains the heat transfer enhancement of the jet impingement in cross-flow due to the VGP. When the height of the VGP increases, the positive influence on the impingement becomes more evident. It demonstrates that the heat transfer on the target wall is dominated by the wall-normal velocity of the impingement and the turbulent kinetic energy, rather than the streamwise velocity along the cross-flow direction. The combined experimental results of the fluid flow and heat transfer can also be used for validating and improving numerical simulation methods.

Fluid Flow and Thin-Film Evolution near the Triple Line during Droplet Evaporation of Self-Rewetting Fluids.

The microscopic region near the triple line plays an important role in the heat and mass transfer of droplets, although the mechanisms of evaporation and internal flow remain unclear. This paper describes an experimental study of fluid flow and thin-film evolution near the triple line in sessile droplets of self-rewetting fluids, aqueous solutions of alcohols with the number of carbon atoms varying from 1 to 7, to analyze the influence of various factors on the mesoscale flows. The mechanism of internal flow for self-rewetting fluid droplets was different from that of conventional fluids, and hence, a novel expression of the in-plane average velocity was fitted for them. The temporal and spatial evolution of the thin-film thickness near the triple line during droplet evaporation was obtained by using a proposed subregion method, which was developed from an evanescent-wave-based multilayer nanoparticle image velocimetry technique. The self-rewetting fluids are conducive to increase the microscopic critical contact angle and the energy barrier of the contact line, which reduces the rate of thin-film thickness variation. The inhibited impact of self-rewetting fluids on evaporation increases gradually with an increasing number of carbon atoms.

Numerical and experimental study of fluid flow in simplified blade cascade with prescribed harmonic motion

In this paper, a numerical simulation and experimental measurements of compressible viscous fluid flow in simplified blade cascade are compared. The cascade consists of five flat plates three of which perform prescribed harmonic motion. The computed unsteady velocity field is compared with experimental measurements at selected points. Moreover, the power spectral density corresponding to the frequency of harmonic motion is computed for both the numerical and experimental data and compared. The numerical simulation was performed using the developed in-house CFD software based on the discontinuous Galerkin method, which offers high order of accuracy.

Numerical and experimental study of fluid flow in simplified blade cascade with prescribed harmonic motion

In this paper, a numerical simulation and experimental measurements of compressible viscous fluid flow in simplified blade cascade are compared. The cascade consists of five flat plates three of which perform prescribed harmonic motion. The computed unsteady velocity field is compared with experimental measurements at selected points. Moreover, the power spectral density corresponding to the frequency of harmonic motion is computed for both the numerical and experimental data and compared. The numerical simulation was performed using the developed in-house CFD software based on the discontinuous Galerkin method, which offers high order of accuracy.

Computational and Experimental Study of Fluid Flow and Heat Flow Characteristics in Porous Media

Shortage of energy is increasing day by day and we have to store energy for our future. Storage is a challenge in the current scenario and lot of research is being conducted to find an effective way to store energy. Packed beds are one of the promising and potential methods to store thermal energy. This paper describes an attempt that has been made to study the fluid flow and heat flow characteristics in porous media. CFD analysis and experiments have been carried out with air-alumina as the porous medium. Pressure drop, velocity distribution, temperature distribution and Effective thermal conductivity have been found out. Parametric studies have been done both in experimentation and in the CFD analysis. Both experimental and computational results seem to be in good agreement.

Experimental Study of Fluid Flow and Heat Transfer Characteristics of Rough Surface, Impinged by a Confined Laminar Slot Air Jet

Experimental Study of Fluid Flow and Heat Transfer Characteristics of Rough Surface, Impinged by a Confined Laminar Slot Air Jet

A simulation and experimental study of fluid flow and heat transfer on cylindrical oblique-finned heat sink

A novel cylindrical oblique fin minichannel heat sink was proposed to fit over cylindrical heat sources in the form of an enveloping jacket. The periodic cylindrical oblique fin causes the hydrodynamic boundary layer development to be reinitialized at the leading edge of the next downstream fin. This decreases the average thermal boundary layer thickness, enhances the heat transfer performance and yields negligible pressure drop penalty due to combined effect of thermal boundary layer re-development and flow mixing. Its cooling effectiveness is compared with conventional straight fin minichannel heat sinks through experimental and numerical approach for the Reynolds number ranged from 50 to 500. The results showed that the averaged Nusselt number, Nuave for the cylindrical oblique-cut fin minichannel heat sink increases up to 75.6% and the total thermal resistance decreases up to 59.1% when compared with the conventional straight fin minichannel heat sink. It is also found firstly that a flow recirculation zone will form at larger Reynolds number in the secondary channel however this recirculation is insignificant in the present low Reynolds number study. Heat transfer enhancement (ENu) and pressure drop penalty (Ef) show that a significant improvement of the cylindrical oblique fin minichannel over conventional straight fin minichannel overall.

Experimental Study of Fluid Flow and Heat Transfer in a Rectangular Channel with Novel Longitudinal Vortex Generators

Experimental Study of Fluid Flow and Heat Transfer in a Rectangular Channel with Novel Longitudinal Vortex Generators

Experimental study of fluid flow and heat transfer from a square prism approaching the wall of a wind tunnel

Experimental investigations of fluid flow and heat transfer have been carried out to study the effect of wall proximity due to flow separation around square prisms. Experiments have been carried for Reynolds number equal to 2.6∙104. The results are presented in the form of pressure coefficient, drag coefficient, and Nusselt numbers for various height ratios, blockage ratios, and angles of attack. The pressure coefficient distribution shows positive values on the front face, whereas on the rear face negative values are observed. The drag coefficient decreases with increase in angle of attack as the height ratio decreases, and its maximum value takes place at an angle of about 50°. Both the local and average Nusselt numbers decrease as the height ratio decreases.

Experimental study of fluid flow and heat transfer characteristics in the square channel with a perforation baffle

This work performed a detailed measurement of local heat transfer coefficients in a square channel with a perforation baffle by using the transient liquid crystal themography. The varied parameters were the Reynolds number, the baffle height, and the hole numbers on the perforation baffle. The results showed that the enhancements of local heat transfer appeared in the leading edge of the baffle due to the impinging effect, which was more significant when Reynolds number became larger or the baffle height became higher. Additionally, the heat transfer coefficients off center were better than those in the center at downstream of the baffle. It might be resulted from two secondary flows, which appeared off center after the airflow passed through the baffle. Baffles with various hole numbers but having same total hole area were also studied to find the heat transfer enhancement. The results depicted that the back facing step flow which had characteristics of backflow and flow reattachment had an important effect on the heat transfer characteristics at downstream of the baffle. Finally, the correlation for the location of the flow reattachment point ( X r) was proposed.

Experimental study of fluid flow in the entrance of a sinusoidal channel

An experimental flow visualization study of the entrance section of channels formed with sinusoidal plates was made. The experiments were conducted in a water tunnel and a laser illuminated particle tracking was used as the technique of flow visualization. The geometric parameters of the plates were maintained constant while the distance between plates, phase angle, and the Reynolds number were varied during the experiments. The flow regimes that were found in the experiments are steady, unsteady and significantly-mixed flows. Instabilities of the flow first appear near the exit of the channel, and move closer to the inlet waves as the Reynolds number grows, but in the first wave from inlet the flow is always steady. The results show that, for all other parameters fixed, the Reynolds number at which unsteady flow first appears grows with the distance between plates. The phase angle that best promotes unsteady flow depends on the average distance between plates: for certain average distance between plates, there is a phase angle that best disturbs the flow. For the set of parameters used in this experiment, a channel with eight waves is sufficiently long and the flow features presented in the first eight waves of a longer channel will be similar to what was observed here.

A Computational and Experimental Study of Fluid Flow in a De-duster

A three-dimensional computational fluid dynamics model with an RNG k-e model and second upwind scheme in the Fluent package was used to simulate the flowpattern in a de-duster. The model predictions for the flow field inside the dispersion device were compared with LDA measurements. The primary objectives are to understand such complex flow fields and to guide the development and optimisation of this de-duster. From the simulation results, the old prototype appears to have some disadvantages and shortcomings. A modification is proposed here to overcome some of these. The major new development in modification is the introduction of a second air inlet and the optimisation of the de-duster geometry. The modification will minimize the disadvantages and shortcomings identified so far.

Measurements of impinging jet flow and heat transfer on a semi-circular concave surface

An experimental study of fluid flow and heat transfer has been carried out for jet impingement cooling on a semi-circular concave surface. The distributions of mean velocity and velocity fluctuation on the concave surface have been measured in free, impinging and wall jet flow regions by using a Laser Doppler Anemometer. Local Nusselt numbers have also been measured. Variations of jet Reynolds numbers, the spacing between the nozzle and the target and the distance from the stagnation point in the circumferential direction have been considered. Emphasis has been placed on measuring turbulent jet flow characteristics including impinging and evolving wall jets and interpreting heat transfer data, particularly, the occurrence and its location of secondary peak in connection with data of measured mean velocity and velocity fluctuations on the concave surface.

Experimental Study of Fluid Flow through Model Fractures, No.2 Cylindrical Contact Areas

Experimental Study of Fluid Flow through Model Fractures, No.2 Cylindrical Contact Areas

An experimental study of fluid flow and heat transfer in decaying swirl through a heated annulus

The mean and turbulent structures of turbulent swirling flow in a heated annulus have been measured. Both forced and free vortex swirling flows were generated, and the outer wall of the test section was heated uniformly. The maximum swirl number was 1.39, Reynolds numbers were up to 200000, and heat input was 10.5 kW. Mean and turbulent velocity components, air and wall temperatures, and wall static pressures were all measured. Hot-film techniques were developed to measure turbulence. From these parameters, the flow and temperature fields, pressure distribution, and heat transfer coefficients were determined. The mechanisms of heat transfer were identified.

Experimental Study of Fluid Flow through Model Fractures

Experimental Study of Fluid Flow through Model Fractures

An Experimental Study of Fluid Flow in Disk Cavities

Results are presented for an experimental study of fluid flow in models of gas turbine disk cavities. Experiments were performed on 70-cm-dia disks for rotational Reynolds numbers up to 2.29 × 106. Velocity and pressure distributions are presented and compared to previous theoretical and experimental studies for a free disk, and an unshrouded plane Rotor–Stator disk system. Minimum coolant flow rates for the prevention of ingress, determined for the case of a simple axial rim seal, compare well with previously published data.

A numerical and experimental study of fluid flow in continuous casting mold

To study removal of nonmetallic inclusion in continuous casting mold, both flow visualized experiments and computer simulations were carried out using a 1/2 scale water model of the mold. The effect of port angle of submerged nozzle on the floatability of nonmetallic inclusion was also examined.

A Proposal on the Electric Tank Method for Study of a Symmetrical Aerofoil with a Rear Suction Slot and a Retractable Flap

An Experimental study of fluid flow past a symmetrical aerofoil with a rear suction slot and a retractable flap was described by D. M. Heughan in the October 1953 JOURNAL. The present note describes the electric tank method for studying the same problem. The experimental apparatus is shown in Fig. 1. A and B are electric poles along two of the edges of the tank which is filled with water. The poles A and B together with the central pole P are connected to an electric supply via a resistance R in such a way that the potential of P is intermediate between that of A and B. The aerofoil F is represented by a wooden block coated with paraffin wax and the pole P is located in such a way as to represent the sink in the suction slot. A voltmeter V records the potential at a point in the tank.