Tangential Velocity Research Articles

A hybrid approach portraying the dynamics of free convection condensation around a circular cylinder

We introduce a hybrid framework to model the fluid dynamics of free convection condensation of saturated steam outside a circular cylinder. The liquid film is modeled analytically, and the adjacent vapor flow field is resolved numerically. The model incorporates temperature-dependent thermophysical properties of the condensate. We explore the subtle role of Jakob number (Ja) and Weber number (We) in the two-phase flow and establish the criteria for dynamic similarity of the flow field with two new dimensionless numbers, viz., free-fall Reynolds number and similarity number. For fixed base Prandtl number of the condensate, the increases in the subcooling rate with Ja and the cylinder's surface area to volume ratio with We cause film thickening. We develop a theoretical correlation to predict the average film thickness (δm). We identify entrainment and bypass zones in the vapor flow field demarcated by a separating streamline. The entrainment zone's streamlines converge to the interface, yielding a net condensate drainage. The bypass streamlines never reach the interface and reduce the condensation efficiency. The results show that the tangential velocity is dominant within the liquid film, the radial velocity is dominant within the vapor flow field, and they are of the same order at the interface. We locate the point of flow separation influenced by a surface tension-induced adverse pressure gradient. The location of the flow separation point shifts upstream, and the separating streamlines become steeper with the increase in We. Our investigation reveals the zone of tangential flow reversal near the interface, promoted with increasing We.

The Proper Motion of the High Galactic Latitude Pulsar Calvera

Calvera (1RXS J141256.0+792204) is a pulsar of characteristic age 285 kyr at a high Galactic latitude of b = +37°, detected only in soft thermal X-rays. We measure a new and precise proper motion for Calvera using Chandra High Resolution Camera observations obtained 10 yr apart. We also derive a new phase-connected ephemeris using 6 yr of NICER data, including the astrometric position and proper motion as fixed parameters in the timing solution. Calvera is located near the center of a faint, circular radio ring that was recently discovered by LOFAR and confirmed as a supernova remnant (SNR) by the detection of γ-ray emission with Fermi Large Area Telescope. The proper motion of 78.5 ± 2.9 mas yr−1 at position angle 241.°3 ± 2.°2 (in Galactic coordinates) points away from the center of the ring, a result which differs markedly from a previous low-significance measurement, and greatly simplifies the interpretation of the SNR/pulsar association. It argues that the supernova indeed birthed Calvera <10 kyr ago, with an initial spin period close to its present value of 59 ms. The tangential velocity of the pulsar depends on its uncertain distance, v t = (372 ± 14)d 1 kpc km s−1, but is probably dominated by the supernova kick, while its progenitor could have been a runaway O or B star from the Galactic disk.

Analysis of the Effect of Structural Parameters on the Internal Flow Field of Composite Curved Inlet Body Hydrocyclone

Analysis of the Effect of Structural Parameters on the Internal Flow Field of Composite Curved Inlet Body Hydrocyclone

Slip due to kink propagation at the liquid–solid interface

In Couette flow, the liquid atoms adjacent to a solid substrate may have a finite average tangential velocity relative to the substrate. This so-called slip has been observed frequently. However, the particular molecular-level mechanisms that give rise to liquid slip are poorly understood. It is often assumed that liquid slip occurs by surface diffusion whereby atoms independently move from one substrate equilibrium site to another. We show that under certain conditions, liquid slip is due not to singular independent molecular motion, but to localized nonlinear waves that propagate at speeds that are orders of magnitude greater than the slip velocity at the liquid–solid interface. Using non-equilibrium molecular dynamics simulations, we find the properties of these waves and the conditions under which they are to be expected as the main progenitors of slip. We also provide a theoretical guide to the properties of these nonlinear waves by using an augmented Frenkel–Kontorova model. The new understanding provided by our results may lead to enhanced capabilities of the liquid–solid interface, for heat transfer, mixing, and surface-mediated catalysis.

Analysis and Experimental Study on the Influence of Louver Separation Device on the Sand Collection Efficiency of Wind Erosion Instrument

A wind erosion instrument is a core instrument for collecting sand particles in wind and sand flows and studying the laws of wind and sand movement. To study the influence of the internal structure of the wind erosion instrument on its sand collection efficiency, a built-in louver separation device was designed. Based on CFD and Fluent 2022 software, numerical analysis was conducted using an RNG k-ε model, and the discrete phase model (DPM) method was used to calculate the sand collection efficiency. The flow field analysis of the new wind–sand separator was carried out. The influence of blade inclination angle, blade thickness, and blade number on sand collection efficiency was studied using single-factor and response surface analysis methods. The optimal parameter combination was obtained as blade inclination angle of 30°, blade thickness of 1.25 mm, and blade number of 10. A simulation model was established based on the optimal combination parameters, and the performance of the wind erosion instrument before and after the addition of the louver separation device was compared. The simulation results show that adding a louver separation device can increase static pressure, alleviate short-circuit flow and back-mixing phenomena, and stabilize the flow field; increasing tangential velocity leads to an increase in particle centrifugal force; reduce axial velocity, prolong particle stagnation time, and minimize particle escape. The particle trajectory pattern is mostly a continuous spiral path, which is conducive to capturing particles and improving sand collection efficiency. Compared with the original structure, for particles with diameters ranging from 0.001–0.05 mm, 0.005–0.01 mm, 0.01–0.05 mm, 0.05–0.1 mm, and 0.1–0.5 mm, the addition of a louver separation device increased the sand collection efficiency by 32.74%, 22.55%, 33.17%, 11.45%, and 0.13%, respectively. When the wind speed is 13.8 m/s and the diameter range is 0.001–0.5 mm, the average sand collection efficiency obtained from simulation tests and wind tunnel tests is 86.18% and 84.32%, respectively, with an error of 2.2%. The simulation results are reliable. The research results show that adding a louver separation device can improve the sand collection efficiency of the wind erosion instrument, and has better overall performance compared to the original wind–sand separator. This study provides a basis for further research on the structure of wind erosion gauges and the environmental protection of farmland. Strengthening land management can effectively protect soil resources, reduce wind erosion, ensure the stability of the ecosystem, and lay the foundation for promoting the sustainable use of land.

Artificial intelligence neural network and fuzzy modelling of unsteady Sisko trihybrid nanofluids for cancer therapy with entropy insights

The main objective of the current endeavor is to monitor hypothetical processes utilizing a Sisko tri-hybrid fluid over a rotating disk with entropy generation suspended in Darcy-Forchheimer porous medium. Electro Magneto Hydro Dynamics (EMHD), non-linear thermal radiation and exponential and thermal- space dependent heat source/sink coefficients are considered with the intent of conceiving an Runge-Kutta-Fehlberg method with shooting procedures integrated with a combination of an Adaptive Neuro-Fuzzy Inference System (ANFIS) and Reptile Search Algorithm (RSA). Then, ANFIS-RSA, is used to predict the Nusselt number, skin friction co-efficient in radial and tangential velocities. Reliable self-similarity variables have reduced a non-linear partial differential set of equations into an ordinary differential equation. According to the empirical evidence, Sisko fluid parameter rises the radial velocity whereas for magnetic field and Darcy-Forchheimer the azimuthal and axial velocities visualizations decreasing trend, respectively. The entropy generation and Bejan number rises for electric and radiation effects. Also, ANFIS-RSA indicates that the model attained a high level of precision in terms of radial velocity (98.13%), tangential velocity (98.18%) and Nusselt number (98.91%). Thus, the longer rendering of the nanoparticles used here might, makes them potentially helpful for regulating the therapeutic impact in the management and treatment of cancer.

Soret and Dufour effects for unsteady flow with shapes and (Cu+Fe3O4)/(ethelene–glycol+methanol) between two stretchable rotating disks

The ongoing study looks at the multiple shapes of nanoparticles in an unsteady flow between two stretchable rotating disks. Unsteady flow of hybrid nanofluid takes place between the stretchable disks, using (ethelene–glycol+methanol) as the base fluid and (Cu+Fe3O4) as the hybrid nanofluid. This study uses three distinct forms of (Cu+Fe3O4) hybrid nanofluids: brick, blade, and cylinder. Using chosen similarity transmutations, corresponding mathematical expressions (partial differential equations) are transformed into nonlinear ordinary differential equations. The whole set of equations takes the shape of an ordinary differential equation depending on the boundary conditions, and the solution is numerically computed using the bvp4c MATLAB solver. The influence of multiple factors across the velocity field is illustrated graphically. To acquire tiny quantities of the unsteady factors S, the momentum boundary layer for all types of nanofluids becomes less and more conspicuous. We compared our findings to previous findings and discovered an intriguing pattern. The main discovery of this work is Dufour and Soret effect on the heat and concentration profile. The rise in the rotation and the unsteady parameter ends up with an increase in the tangential velocity. The temperature rises as the Brinkman number and heat source factors rise, and falls as the unsteady parameter S rises. The concentration falls as the Schmidt number and unsteady factor increase, but it increases as the activation energy increases.

An ADCP Attitude Dynamic Errors Correction Method Based on Angular Velocity Tensor and Radius Vector Estimation

An acoustic Doppler current profiler (ADCP) installed on a platform produces rotational tangential velocity as a result of variations in the platform’s attitude, with both the tangential velocity and radial orientation varying between each pulse’s transmission and reception by the transducer. These factors introduce errors into the measurements of vessel velocity and flow velocity. In this study, we address the errors induced by dynamic factors related to variations in attitude and propose an ADCP attitude dynamic error correction method based on angular velocity tensor and radius vector estimation. This method utilizes a low-sampling-rate inclinometer and compass data and estimates the angular velocity tensor based on a physical model of vessel motion combined with nonlinear least-squares estimation. The angular velocity tensor is then used to estimate the transducers’ radius vectors. Finally, the radius vectors are employed to correct the instantaneous tangential velocity within the measured velocities of the vessel and flow. To verify the effectiveness of the proposed method, field tests were conducted in a water pool. The results demonstrate that the proposed method surpasses the attitude static correction approach. In comparison with the ASC method, the average relative error in vessel velocity during free-swaying movement decreased by 20.94%, while the relative standard deviation of the error was reduced by 17.38%.

Darcy-Forchheimer magnetohydrodynamic flow of non-Newtonian Reiner-Rivlin hybrid nanofluid bounded by double-revolving disks

The applications of fluid flow and heat transfer between coaxial double-revolving disks are diverse and can be found in various engineering and scientific domains. In general, the utilization of engine oil ( EO) mixed with hybrid nanoparticles serves various purposes in engine cooling, such as maintaining viscosity-temperature properties, preventing corrosion, and achieving other cooling-related objectives. This investigation focuses on the Darcy-Forchheimer flow of a non-Newtonian Reiner-Rivlin hybrid nanofluid confined between double-revolving disks. The hybrid nanoparticles used include cadmium telluride ( CdTe) and titanium dioxide ( TiO2), combined with the base fluid engine oil. The dimensional flow equations are converted into dimensionless forms using suitable similarity transformations. Subsequently, a semi-analytical methodology known as the homotopy analysis method ( HAM) is utilized to tackle this problem. Graphs are used to determine the effects of the various flow parameters of the hybrid nanofluids on the velocities, temperature, skin friction coefficient, and the Nusselt number. After validating the findings against previous research, an attractive agreement was observed. Some major outcomes from this present problem are that axial, radial, and temperature profiles increase with the rise of the cross-viscosity parameter while the tangential velocity decreases. Radial velocity increased, and tangential velocity diminished with an enhanced magnetic field parameter. Radial velocity is increased for higher values of the dimensionless forced parameter. For higher values of the porosity parameter, the temperature profile improved. Also, the exploration of the Nusselt number and skin friction for the disks, incorporating the effects of a magnetic field and porous medium, reveals that skin friction for both disks increase with the rising Reynolds number and volume fraction of the cadmium telluride nanoparticles.

Comparative Analyses of Dynamic Characteristics of Gas Phase Flow Field Within Different Structural Cyclone Separators

The gas phase flow field inside a cyclone separator is crucial to the particle separation process. Previous studies have paid attention to the steady-state characteristics of the gas phase flow field, while research on its dynamic characteristics remains insufficient. Meanwhile, cyclone separators often adopt different structural forms according to the process requirements, the evolution laws of the dynamic characteristics flow field within them are still not well understood. Therefore, in this study, a hot-wire anemometer (HWA) was employed to measure the instantaneous tangential velocity of the gas phase flow fields within different structural cyclone separators (cylinder type, cylinder–cone (no hopper), and cylinder–cone (with hopper)). Comparative analyses and discussions were conducted regarding the dynamic characteristic distribution rules of the flow field in the time domain and the frequency domain. The results revealed that the dimensionless tangential velocity distributions of different types of cyclone separators all conformed to the Rankine vortex structure. The instantaneous tangential velocity fluctuated with low frequency and high amplitude, and the low-frequency velocity fluctuation exhibited a transfer behavior along the radial direction. Compared with the cylinder–cone-type cyclone separator, the tangential velocity in the cylinder-type cyclone separator fluctuated more greatly, and its quasi-periodic behavior was also more obvious. The time-averaged tangential velocity, the tangential velocity fluctuation intensity (Sd), and the dominant fluctuation frequency all had obvious attenuation along the axial direction in the cylinder-type cyclone separator, while the above-mentioned parameters had no attenuation along the axial direction in cylinder–cone-type cyclone separators. Additionally, the backflow from the hopper of the cylinder–cone-type cyclone separator (with hopper) led to an increase in the instantaneous tangential velocity fluctuation intensity of the local flow field near the dust outlet, as well as the occurrence of the “double dominant frequencies” phenomenon.

Heat and mass flux dynamics of tangent hyperbolic nanofluid flow with unsteady rotatory stretching disk over Darcy-Forchheimer porous medium

Abstract The purpose of the research is to examine a tangent hyperbolic nanofluid flowing in three dimensions (3D) axisymmetrically on an unsteady rotatory stretching disk over a Darcy-Forchheimer porous medium. First order initial value problems (IVPs) are generated from the governing partial differential equations (PDEs) through the use of similarity transformation and linearization. The Runge-Kutta sixth order (RK6) is utilized to solve the IVP system using the shooting technique and the built-in Python program ‘fsolve model10’. Articles that have already been published are used to validate the implemented approach. Graphs are used to examine how various parameters affect velocity, temperature, and concentration. Additionally, the behavior of heat, mass flux, and skin friction in response to different parameters is investigated. The study’s findings showed that as the Forchheimer number and velocity slip parameter increased, the nanofluid’s radial and tangential velocities decreased as well. As temperature and concentration slip parameters increase, correspondingly, thicker and thinner boundary layer structures are seen. The drag force in the tangential and radial direction behaves in the same manner. Both the rates of heat and mass transfers are initiated for an increase Eckert and Prandtl numbers and demotivated for power-law index number. The dissipation effect with radiation and chemical reaction plays a major role in heat and mass fluxes, respectively. The study can be used in various computer storage, coatings, lubricants, and coolants.

Extension of the local domain-free discretization method to large eddy simulation of compressible flows

Most of the flow problems encountered in practical engineering are wall-bounded turbulent flows at high Reynolds numbers. Wall-modeled large eddy simulation (WMLES) is one of the most viable approaches for predicting these realistic flows. Immersed boundary (IB) approach is an efficient computational technique to solve flow problems involving complex and/or moving geometries. This work extends a sharp-interface IB method, named the local domain-free discretion (DFD), to WMLES of compressible flows at high Reynolds numbers. An equilibrium wall model based on solving the simplified compressible turbulent boundary layer equations is utilized to alleviate the requirement of high near-wall mesh resolution. In conjunction with the approximate boundary conditions prescribed by the modeled wall shear stress and wall heat flux, the tangential velocity and temperature at an exterior dependent node are evaluated. Then, the closure of the discrete form of governing equations at an interior node in the immediate vicinity of the immersed wall is accomplished. A simple non-equilibrium correction of the wall shear stress provided by the equilibrium wall model is introduced explicitly. The WMLES/DFD method is applied to a supersonic zero-pressure-gradient turbulent boundary layer flow, a shock wave/flat-plate boundary layer interaction, a supersonic compression ramp flow and high-speed turbulent Couette flows with various thermal boundary conditions. The influence of grid resolution is investigated in the simulation of zero-pressure-gradient turbulent boundary layer flow. By comparing the computed results with the referenced experimental data and/or numerical results, the accuracy and ability of the WMLES/DFD method to simulate compressible turbulent flows are verified.

LES Validation on Near-Field Wingtip Vortex Evolution with Wind Tunnel Characterization at Low Reynolds Number

Wind tunnel tests are commonly used to visualize the trailing vortices, but tests involving advanced optical measurement techniques can be costly. Camera-based experiments are more affordable, but the low visibility caused by smoke particles and limitations of the upright view make vortex characterization and quantification challenging. In this paper, the proposed perspective upright correction allows adjustment of the slanted plane during post-processing. This technique has reduced the complexity of wind tunnel set-up, and yet yielding a more accurate result than the native upright view. Large Eddy Simulation (LES) is then utilized with proper mesh design within the vortex core volume to effectively capture the smaller scales features of the wingtip vortex and validate against the perspective upright corrected characterization from wind tunnel experiment. The vortex core defined by its maximum tangential velocity will be analyzed against the physical wake evolution captured in wind tunnel, providing insights into the relationship between these two methodologies. The demonstrated accuracy and credibility of the CFD model can ensure that the future simulations in the extended field can be accurately predicted and analyzed.

Parametric design of curved hydrocyclone using data points and its separation enhancement mechanism

Based on parametric design of curves using data points, two novel hydrocyclones were designed: Spline-Curved-Cone hydrocyclone (H2) and Expassoc-Curved-Cone hydrocyclone (H3). These designs are improvements on the traditional biconical hydrocyclone (H1). Numerical simulations and experimental validation by PIV measurement were used to investigate the effects of cone section profiles on the flow characteristics and separation efficiency. The results showed both H2 and H3 achieved higher separation efficiency than H1. Specifically, the highest efficiency of H3 increased by 24.71%, and that of H2 increased by 16.22% compared with H1. It was also found the curved design of cone section profile directly affects the tangential velocity distribution and pressure distribution of the flow field inside hydrocyclones. H3 exhibited better flow field stability and highest separation efficiency due to its optimized cone section space and flow structure. This study provides scientific basis and data support for the optimization and industrial application of the cylinder-on-cone hydrocyclones.

Testing the flux tube expansion factor

Context. The properties of the solar wind measured in situ in the heliosphere are largely controlled by energy deposition in the solar corona, which is in turn closely related to the properties of the coronal magnetic field. Previous studies have shown that long-duration and large-scale magnetic structures show an inverse relation between the solar wind velocity measured in situ near 1 au and the expansion factor of the magnetic flux tubes in the solar atmosphere. Aims. The advent of the Solar Orbiter mission offers a new opportunity to analyse the relation between solar wind properties measured in situ in the inner heliosphere and the coronal magnetic field. We exploit this new data in conjunction with models of the coronal magnetic field and the solar wind to evaluate the flux expansion factor and speed relation. Methods. We use a Parker-like solar wind model, the “isopoly” model presented in previous works, to describe the motion of the solar wind plasma in the radial direction and model the tangential plasma motion due to solar rotation with the Weber and Davis equations. Both radial and tangential velocities are used to compute the plasma trajectory and streamline from Solar Orbiter location sunward to the solar ‘source surface’ at rss. We then employed a potential field source surface (PFSS) model to reconstruct the coronal magnetic field below rss to connect wind parcels mapped back to the photosphere. Results. We found a statistically weak anti-correlation between the in situ bulk velocity and the coronal expansion factor, for about 1.5 years of solar data. Classification of the data by source latitude reveals different levels of anticorrelation, which is typically higher when Solar Orbiter magnetically connects to high latitude structures than when it connects to low latitude structures. We show the existence of a fast solar wind that originates in strong magnetic field regions at low latitudes and undergoes large expansion factor. We provide evidence that such winds become supersonic during the super-radial expansion (below rss) and are theoretically governed by a positive v–f correlation. We find that faster winds exhibit, on average, a flux tube expansion at a larger radius than slower winds. Conclusions. An anticorrelation between solar wind speed and expansion factor is present for solar winds originating in high latitude structures in solar minimum activity, typically associated with coronal hole-like structures, but this cannot be generalized to lower latitude sources. We have found extended time intervals of fast solar wind associated with both large expansion factors and strong photospheric magnetic fields. Therefore, the value of the expansion factor alone cannot be used to predict the solar wind speed. Other parameters, such as the height at which the expansion gradient is the strongest, must also be taken into account.

Improving compositional homogeneity of CF53 steel products by modifying their solidification structure and F-EMS intensity

In this article, based on the mechanism of stirring induced solute washing, the solidification characteristics of CF53 steel for camshafts were systematically studied through industrial casting tests and numerical simulations, focusing on the impact of solidification structure and final electromagnetic stirring (F-EMS) on solute distribution homogeneity in the core area of the bloom casting. The results indicate that excessive columnar crystal development, coupled with inappropriate use of F-EMS, can lead to significant negative segregation in the bloom, resulting in the formation of “white bands” in the following rolling bar products. Compared with weak stirring, strong stirring can affect solutes at deeper levels between dendrites. By reducing superheat and casting speed, expanding the equiaxed crystal zone in the bloom's centre, and carefully controlling the stirring intensity of F-EMS to position the molten steel washing in the equiaxed crystal zone, along with maintaining a maximum tangential velocity of 0.0041 m/s, a substantial improvement in solute distribution homogeneity within the bloom's core area was achieved. The carbon range can be reduced from 0.093% to 0.032%. These findings offer a theoretical foundation and practical suggestions for enhancing the quality of CF53 steel bloom castings and their hot-rolled bar products used in camshaft manufacture.

Mixing of inelastic non-Newtonian fluids with inlet swirl

In the present work, the tangential (swirl) velocity component is superimposed at the intake of a narrow fluidic cylindrical pipe to achieve the desired mixing of inelastic non-Newtonian fluids/solutes at the outlet. We discuss an analytical method for obtaining the swirl velocity profile, considering the nonlinear viscous effects for both shear-thinning and shear-thickening fluids, represented by the power-law model. We numerically solve the species transport equation, coupled with the analytically derived swirl velocity, using our in-house developed code for the concentration distribution in the flow field. The results show that the inlet swirl and an increase in the shear-thinning fluid property improve advection-dominated mixing. Additionally, higher Reynolds numbers significantly enhance advection's dominance, as more rotation leads to the generation of vortices, resulting in an engulfment flow (chaotic convection) based mixing. We demonstrate that considering the increase in the shear-thinning fluid property with swirl intake reduces the amount of mixing time required in the convective regime.

Flow field characteristic in a novel cyclone-granular bed coupled separator

The three-dimensional flow field in a novel cyclone-granular bed coupled separator was discussed experimentally with a five-hole probe system. The airflow behaviors in the annular space, separation space, and central outlet were addressed. Several significant phenomena (the squeezing effect, the top flow loop, and the rectification effect) were observed and analyzed. By comparing the three-dimensional velocity distribution in the coupled separator with different structure parameters (the coupling space index, rc=0.37/0.44), the combined effect between the two efficient gas purifiers was demonstrated and the importance of the tangential velocity was clarified. For this purpose, the equations for the tangential velocity at four circumferential positions were fitted using regression analysis with a wide array of experimental data and effectively characterized prior experimental outcomes.

Discovery of 118 New Ultracool Dwarf Candidates Using Machine-learning Techniques

We present the discovery of 118 new ultracool dwarf candidates, discovered using a new machine-learning tool, named SMDET, applied to time-series images from the Wide-field Infrared Survey Explorer. We gathered photometric and astrometric data to estimate each candidate’s spectral type, distance, and tangential velocity. This sample has a photometrically estimated spectral class distribution of 28 M dwarfs, 64 L dwarfs, and 18 T dwarfs. We also identify a T-subdwarf candidate, two extreme T-subdwarf candidates, and two candidate young ultracool dwarfs. Five objects did not have enough photometric data for any estimations to be made. To validate our estimated spectral types, spectra were collected for two objects, yielding confirmed spectral types of T5 (estimated T5) and T3 (estimated T4). Demonstrating the effectiveness of machine-learning tools as a new large-scale discovery technique.

Numerical study on the fluid flow and condensation heat transfer characteristics of two-phase NaCl-H2O fluids on the external swept spiral coil in a hydrothermal vent

The substantial thermal energy of two-phase NaCl-H2O hydrothermal fluids makes them a significant target for utilizing deep-sea energy. A fundamental understanding of the thermal performance of two-phase NaCl-H2O hydrothermal fluids during condensation is crucial for heat energy harnessing. It aims to obtain the flow and condensation heat transfer characteristics of two-phase NaCl-H2O fluids during the heat transfer process outside a spiral coil structure in this paper. The properties of the NaCl-H2O binary systems were adopted instead of pure water, and the salt transport equation was considered to reflect the impact of salinity change on heat transfer, making the simulation more representative of natural venting fluids. The results indicated a significant tangential velocity when the fluids externally swept the spiral coil. Secondly, the heat transfer area can be divided into the “normal region” and the “island region,” of which convection and condensation contribute to the heat transfer mechanisms. The “island region” formation was attributed to both vapor condensation and the spoiler effect caused by the spiral structure. Moreover, the heat flux increased with decreasing salinity in the “island region,” and a weak interaction was observed between heat flux and salinity in the “normal region.” Finally, the spiral structure's heat transfer performance was superior to the straight structure's. This investigation may provide a basis for designing and optimizing the heat transfer equipment for deep-sea hydrothermal extraction.