Liquid Flow Characteristics Research Articles

Effects of Non-Uniform Center-Flow Distribution and Cavitation on Continuous-Type Pintle Injectors

In this paper, the flow characteristics of a continuous-type liquid–liquid pintle injector are described, focusing on the differential impact of a non-uniform center-flow distribution on single- and bi-injection methodologies as well as the cavitation effect on the spray angle. Using cold-flow experiments, jet-type flows of the center propellant caused by a non-uniform flow distribution were observed during a single injection. This resulted in an augmented pressure drop, as opposed to the flow characteristics of uniform single-film injection. By contrast, bi-injection modalities exhibited a substantial reduction in the pressure drop of the center propellant, underscoring a more equitable flow distribution. Moreover, the occurrence of cavitation in the center propellant was found to markedly affect the spray angle. By considering the injection exit area reduction caused by cavitation, the spray-angle prediction accuracy increased. The findings of this study are expected to reveal the interplay between flow distribution and pressure drop as well as that between cavitation and the spray angle in pintle injectors. Through this understanding, this study provides crucial considerations for the development of more efficient propulsion systems.

Deep deoxidation of water in a miniaturized annular rotating device: Experimental investigation and machine learning modeling

Conventional gas–liquid devices exhibit limitations, including inadequate dispersion efficiency and significant backmixing, leading to low conversion and large equipment volume. Thus, a miniaturized annular rotating device (m-ARD) was proposed based on microscale effects and rotating flow field to achieve efficient gas–liquid mass transfer and high conversion. Nitrogen-oxygenated water was selected as the experimental system to evaluate the performance of the m-ARD. The gas–liquid flow characteristics were investigated. The analysis focused on examining the impact of different factors on deoxygenation efficiency. The deoxygenation performance was optimized and compared with different devices. The study found that the m-ARD enables a continuous counter-current gas–liquid flow mode, with superior mixing performance and a narrow residence time distribution. The deoxygenated water with an oxygen concentration as low as 0.14 ppm can be produced, with a volumetric mass transfer coefficient (kLa) of 0.26 s−1, a theoretical stage value of 4.22, and a handling capacity of 30 mL/min under optimized experimental conditions. In addition, kLa was predicted using an artificial neural network model and showed good agreement with the simulated values. This work provides a promising reactor for chemical reactions that require high conversions.

Experimental Study on the Performance and Internal Flow Characteristics of Liquid–Gas Jet Pump with Square Nozzle

In order to ascertain the impact of working water flow rate and inlet pressure on the performance of the liquid–gas jet pump with square nozzle, the pumping volume ratio and efficiency of the liquid–gas jet pump with square nozzle were experimentally investigated at different inlet pressures and working water flow rates. Furthermore, the internal flow characteristics of the liquid–gas jet pump with square nozzle were explored through the utilization of visualization technology in the self-designed square-nozzle liquid–gas jet pump experimental setup. The findings indicate that the pumping ratio of the liquid–gas jet pump increases in conjunction with an elevation in the inlet pressure. Liquid–gas jet pump efficiency is higher at lower inlet pressures, up to 42.48%, and drops rapidly as inlet pressure increases. The pumping volume ratio of the liquid–gas jet pump increases significantly as the working water flow rate increases, and the working water flow rate exerts a minimal effect on the working efficiency of the liquid–gas jet pump. In the context of extreme vacuum conditions, a considerable number of droplets undergo substantial reflux in the posterior section of the throat, with a notable absence of bubbles in the diffusion tube. The size and number of bubbles diminish gradually along the axial direction. The objective of this paper is to provide a reference point for determining the optimal operational parameters for a square-nozzle liquid–gas jet pump in a practical context.

Analytical investigation of convective phenomena with nonlinearity characteristics in nanostratified liquid film above an inclined extended sheet

Abstract This work focuses on the time-variant convective thin-film nanoliquid fluid flow and heat transfer over a stretching, inclined surface under the effect of magnetism for different energy technologies for sustainability. It is crucial to understand how solid materials can be treated with thin films while focusing on the actual ability to improve the body surface features for infiltration, shock resistance, rigidness, brightness, dispersal, absorption, or electrical efficiency. All of these improvements are invaluable, especially in the field of nanotechnology. As with any mass and thermal transport phenomena, the study breaks down important factors such as thermophoresis and Brownian movement, in an attempt to improve the energetic balance and lessen fuel consumption. Utilizing the mathematical model of the temporal evolution on the liquid film flow characteristics over an inclined surface, we obtain a system of nonlinear partial differential equations and convert it to a system of coupled ordinary differential equations appropriately. Finally, the results of the model problem computational analysis are produced using the Laplace Adomian decomposition method (LADM) and are shown both quantitatively and visually. During the flow analysis, the impact of specific flow parameters such as the magnetic, Brownian, and thermophoresis parameters are examined and found to be highly significant. Furthermore, it is found that the effects of ( M M ) and (Nt) factors on ( F F ), ( Φ \Phi ), and ( ϕ \phi ) lead to decreased conduction. Conversely, the thermal gradient within the liquid films rises in proportion to the (Nb) factor. This research is distinguished from similar attempts made in the past in terms of thin-film nanoliquid flow from inclined planes and application of LADM approach toward modeling. The findings have provided tangible use in coming up with new methods of cooling electronics gadgets, energy harvesting for solar energy, and eco-friendly industrial processes.

Effect of incoming flow conditions on air lubrication regimes

Different air phase regimes are formed by controlled air injection in a spatially developing flat plate turbulent boundary layer (TBL). The air is introduced via a slot type injector without the use of a backward-facing step or cavitator upstream of the air injection position. The effect of different incoming liquid flow characteristics on the different regimes is investigated by varying both the liquid freestream velocity and the incoming TBL thickness. The latter is realized through changing the position of the air injection along the length of the water tunnel facility. That resulted in a downstream distance based Reynolds number from 1 to 5 million. Three different air phase regimes are identified under different air flow rates and freestream velocities: the bubbly regime, the transitional, and the air layer regime. The morphological differences of each one are described and quantitative analysis is performed based on the non-wetted area in each condition. The incoming TBL as well as the flow around the air layer are measured with planar particle image velocimetry. The latter enabled the determination of the air layer thickness. In addition, the ratio of the air layer to the incoming boundary layer thickness tair/δ is also calculated (≈ 0.04 – 0.5). This is a significant dimensionless parameter for scaling, which indicates the extent to which the air layer is embedded within the incoming TBL. Depending on the incoming flow conditions, a two or three branch air layer is formed. The length of the air layer is found to increase with increasing liquid freestream velocities. A good agreement between the air layer length and a half gravity wave predicted by the dispersion relation is found. An increase of the air layer length is observed with a decreasing incoming TBL thickness. This is attributed to a decrease in the local mean velocity at the air–water interface due to the TBL growth. Finally, increasing the incoming TBL thickness delays the onset of the air layer regime.

Dynamics and heat-transfer characteristics of the liquid film flow in upward- and vertical-facing spray cooling

In this study, an experimental investigation was conducted on the dynamics and heat-transfer characteristics of liquid film flow for upward- and vertical-facing spray cooling. The heat-transfer performances at different inlet pressures, nozzle-to-surface distances, and heat flux inputs between the two orientations were compared, and the morphologies, wetted areas, and velocities of the isolated liquid films were quantitatively captured. The morphologies of the HFE-7100 liquid films and their distributions on the vertical and upward surfaces exhibited no significant differences. In most cases, the heat-transfer performance of the upward surface was slightly better than that of the vertical surface. Gravity affected the velocity of the isolated liquid films on a smooth vertical surface, whereas its effect was significantly suppressed on an unpolished surface. The Bond number of the isolated liquid film flow on the upward surface was verified to be naturally smaller than that on the vertical surface. Dimensionless groups, including the Bo, We, and Re numbers of the liquid film flow in spray cooling, were obtained to further account for the effect of gravity. The reason why the dimensionless groups presented such small orders was explained. The data map of liquid film flow (dimensionless groups) during spray cooling was further enriched.

Liquid–liquid flow characteristics and mass transfer enhancement in a Taylor–Couette microreactor

AbstractThe liquid–liquid immiscible flow and mass transfer were investigated in a novel Taylor–Couette microreactor (TCMR). Due to the rotation shear and microscale effects, each phase flowed in the form of helical strips/bands, instead of dispersion droplets as in conventional equipment. Based on the movement and inclination of the bands, the helical vortex (HV), mixed helical vortex (MHV) and stationary helical vortex (SHV) were distinguished. The characteristics of the regimes were strongly influenced by rotation speed and flow rate, but the specific surface area only slightly varied. The flow regimes also influenced the two phase mass transfer. It was shown that the mass transfer coefficient kLa monotonically increased with the rotation speed in the HV regime, while it slightly decreased when the flow shifted into the MHV/SHV regime. According to the parametric studies, empirical correlations were developed for the flow regime transition and mass transfer prediction.

Simultaneous measurement of velocity field of liquid–solid particle flow in pipelines and analysis of flow characteristics

The liquid–solid particle flow within a horizontal pipeline is a typical particle-laden flow. The interplay between loaded particles and carrier phase engenders significant complexities in the dynamic behavior of such flows. We investigated the dynamics of a liquid–solid particle flow featuring dilute, slightly buoyant, hundred-micron-sized spherical particles fully suspended in the turbulent flow in a pipe, where Re is 7038. Cases with solid volume fractions of 0, 2.67 × 10-4, 5.33 × 10-4, 8.00 × 10-4, 1.07 × 10-3 and 1.33 × 10-3 were considered in this study. Experimental measurement techniques were utilized to acquire images of particles in the two-phase flow across the entire flow field via optical field feedback. Particle image velocimetry (PIV) and particle tracking velocimetry (PTV) were employed to simultaneously obtain liquid-phase velocity fields and particle trajectories. This approach allowed for a comprehensive depiction of the velocity field of each phase. Subsequently, a detailed explanation and analysis of the flow characteristics of the liquid–solid particle flow were provided based on the distribution of macroscopic velocity fields, the microscopic vorticity field, particle velocity vectors, and velocity slip. As a result, it was found that with the addition of solid particles and an increase in volume concentration, the drag effect of the solid phase and the trend of accumulation near the lower wall caused a decrease in the liquid phase velocity profile and deformation of the parabolic shape. In the liquid–solid particle flow with a volume concentration of 1.33 × 10-3, compared to the single-liquid phase flow, the standard deviation of velocity in the central region increased from 0.0097 m/s to 0.0159 m/s, and in the near-wall region, it increased from 0.0257 m/s to 0.0347 m/s, representing increases of 1.54 times and 1.26 times respectively. The proportion of medium vortices increased from 17 % to 30 %, nearly doubling. This study actively explores the concurrent measurement and flow characteristics of liquid–solid particle flow.

Comparison between DNS and RANS approaches for liquid metal flows around a square rod bundle

The thermal-hydraulic characteristics of liquid metal flows around rod bundles are of great interest for the research and design of fourth generation nuclear reactors. Currently, a large research effort is aimed at the development of accurate numerical models for low Prandtl number fluid flows, since the data available in the literature are quite scarce. Direct Numerical Simulation (DNS) is undoubtedly the most accurate approach, but its large requirements of computational resources and time make it less practical than other simplified methods such as the Reynolds-Average Navier Stokes (RANS) approach. The present paper provides a comparison between numerical results of a flow of liquid Lead-Bismuth Eutectic (LBE) at Pr=0.031 around four vertical cylindrical rods arranged in a square lattice, obtained by DNS and RANS. Several turbulence models are considered, including the standard k−ε, k−ω SST, and two Reynolds stress models, namely the ones by Launder, Reece and Rodi (LRR), and Speziale, Sarkar and Gatski (SSG). The accuracy of these models is assessed by comparing the mean Nusselt number, the pressure drop, and local field distributions with those obtained by DNS.

Experimental study on the immersion liquid cooling performance of high-power data center servers

Highly dense and integrated data centers face key challenges of realizing efficient cooling and improved energy efficiency. To overcome these challenges, this study experimentally investigated the flow and heat transfer characteristics of single-phase immersion liquid cooling (SPILC) systems. The influence of two opposite coolant flow directions on the SPILC performance was examined. Furthermore, a correlation mechanism between coolant thermal properties and SPILC performance was established, along with a control chart for regulating the working conditions of SPILC systems. The results indicate that compared to a pro-gravity flow, an anti-gravity flow scheme reduces the chip case temperature and thermal resistance by 33.8% and 55.6%, respectively, while decreasing the power usage effectiveness (PUE) by 1.4%. Using coolant with the lowest viscosity reduces the chip case temperature and thermal resistance by 9.3% and 10.5%, respectively, while decreasing the PUE by 0.4%. Moreover, the cooling water temperature has a greater impact on the performance of SPILC systems than the volume flow rate of coolants. Additionally, this paper provides control charts for the cooling water temperature and coolant flow rate to improve the PUE while ensuring the safe operation of SPILC systems, with the highest chip temperature and total electricity consumption as indicators.

Study on Wear Characteristics of a Guide Vane Centrifugal Pump Based on CFD–DEM

Guide vane submersible centrifugal pumps are a kind of submersible pump, and the fluid inside the pump is often mixed with gravel and other impurities during operation, affecting the pump’s operating efficiency and life expectancy. However, past studies on solid–liquid two-phase flow (STF) and wear characteristics in guided vane centrifugal pumps have been limited to the particle trajectory and wear region distribution. These studies have lacked research on the effect of particles on the fluid flow and the specific amount of wear on the overflow components. Additionally, most of them have used the DPM discrete-phase model, which does not consider the particle–particle and particle–wall interactions. This paper is based on the CFD–DEM method, combined with the Archard wear model. A solid–liquid two-phase flow simulation is carried out for pumps with different particle sizes and particle shapes to analyze the particle movement inside the pump, the wear distribution and average wear amount of the overflow components, and the effect of particles on the turbulent kinetic energy of the fluid. The results show that the particles mainly collide with the leading and trailing edges of the impeller blades and the leading edge of the guide vane blades and form a buildup at the trailing edge of the concave surface of the guide vane blades, resulting in the wear being mainly distributed in these regions. With an increase in particle size and a decrease in sphericity, the average wear on the overflow components increases. The change of particle size directly affects the resistance of the fluid and the structure of the flow field, which has a large impact on the fluid flow pattern and generates large turbulent kinetic energy fluctuations. The shape of the particles only changes the structure of the local flow field, which has a small impact on the fluid flow pattern.

Accurate Liquid Level Measurement with Minimal Error: A Chaotic Observer Approach

This paper delves into precisely measuring liquid levels using a specific methodology with diverse real-world applications such as process optimization, quality control, fault detection and diagnosis, etc. It demonstrates the process of liquid level measurement by employing a chaotic observer, which senses multiple variables within a system. A three-dimensional computational fluid dynamics (CFD) model is meticulously created using ANSYS to explore the laminar flow characteristics of liquids comprehensively. The methodology integrates the system identification technique to formulate a third-order state–space model that characterizes the system. Based on this mathematical model, we develop estimators inspired by Lorenz and Rossler’s principles to gauge the liquid level under specified liquid temperature, density, inlet velocity, and sensor placement conditions. The estimated results are compared with those of an artificial neural network (ANN) model. These ANN models learn and adapt to the patterns and features in data and catch non-linear relationships between input and output variables. The accuracy and error minimization of the developed model are confirmed through a thorough validation process. Experimental setups are employed to ensure the reliability and precision of the estimation results, thereby underscoring the robustness of our liquid-level measurement methodology. In summary, this study helps to estimate unmeasured states using the available measurements, which is essential for understanding and controlling the behavior of a system. It helps improve the performance and robustness of control systems, enhance fault detection capabilities, and contribute to dynamic systems’ overall efficiency and reliability.

Study on flow and heat transfer characteristics of liquid metal flow in narrow rectangular channels under high heat flux

In order to improve the core power density of liquid metal reactors, narrow rectangular fuel assemblies are typically used, which have obvious advantages in heat transfer capacity. However, the flow and heat transfer characteristics in coolant passage need to be studied. In this article, the numerical simulation analysis model obtained earlier was applied to calculate the Nusselt number, friction factor, with different Reynolds number, Prandtl number, or Peclet number of lead bismuth flow in a narrow rectangular channel under high heat flux. A heating correction factor was proposed and a flow resistance model was established for high heat flux. The influencing factors of ultra-high flux reactor core, such as gap size, flow direction, single and double sided heating conditions, on the flow and heat transfer in narrow rectangular channels were explored. The results showed that gap size and aspect ratio have a certain impact on the Nu and f of narrow rectangular channels, but the influence is relatively small within the narrow rectangular channel condition range. The influence of flow direction on flow and heat transfer is minimal, the single and double sided heating conditions will bring about a difference of about 20% in Nu and a difference of about 2.5% in f. In addition, the type of liquid metal will also affect the results. The research can provide reference for the thermal design and optimization of ultra-high flux reactor cores.

Electroosmosis of viscoelastic fluids in pH-sensitive hydrophobic microchannels: Effect of surface charge-dependent slip length

We analytically investigated the electroosmotic flow characteristics of complex viscoelastic liquids within a charged hydrophobic microchannel, considering the pH and salt concentration-dependent surface charge effects in our analysis. We examined the variation of the electric-double layer (EDL) potential field, the surface charge-dependent slip (SCDS) length, the flow field, the viscosity ratio, and both normal and shear stresses in relation to the bulk pH, bulk salt concentration, and Deborah number of the solution. Our current findings indicate that, under strong flow resistance due to increased electrical attraction on counter ions, a highly basic solution with a high EDL potential magnitude results in a significant decrease in the slip length. Neglecting the effect of SCDS leads to an overestimation of flow velocity, with this overprediction being more pronounced for highly basic solutions. This overestimation diminishes as bulk salt concentration increases, particularly when compared to strongly acidic solutions. Furthermore, a noticeable increase in average velocity is observed as the Deborah number rises for highly basic solutions compared to highly acidic ones. This is attributed to the substantial reduction in apparent viscosity caused by the shear-thinning nature of the liquid at higher shear rates, supported by a larger zeta potential modulated strong electrical force for basic solutions. Additionally, we found that the intensity of shear and normal stresses tends to increase with bulk pH, primarily due to the rise in electric body force at higher zeta potential. These results can potentially inform the design and development of a compact, nonmoving electroosmotic pump for transporting biological species with varying physiological properties, such as solution pH. This technology could be applied in subsequent processes involving mixing, separation, flow-focusing for cell sorting, and other related applications.

Research on the mixing characteristics of the bottom blowing molten pool based on flow characteristics and mixing uniformity

In this study, a new method of combining lance–liquid flow characteristics and mixing uniformity is proposed to evaluate the stirring characteristics in the bottom blowing copper molten pool. A fluid simulation model of a bottom blowing molten pool was established, water was used to simulate the melt environment, and an experimental platform was set up for verification. The effects of swirl, multi-channel, and straight pipe spray on the lance–liquid stirring characteristics of the bottom-blown copper molten pool are compared through quantifying the flow characteristics and mixing uniformity. In addition, digital image processing technologies, such as image entropy variance and eddy current map entropy increase, are introduced. Through numerical simulation research, it is found that the transverse velocity of the swirl spray lance is the largest, which makes the rise time of the bubble increase to the greatest extent. Compared with the straight pipe spray, the swirl spray reduces the liquid splash height by 0.054 m, and the degree of vortex flow is higher. The lance phase stability is increased by 37.87%, and the maximum turbulent kinetic energy can be increased by 8.73%. The spray effect of the multi-channel spray is between the two. It is shown that the swirling spray lance can improve the stability of gas in the molten pool, enhance the uniformity of gas–liquid mixing, and improve the operation cycle and the smelting efficiency of the molten pool.

Computational analysis to examine the role of nanoparticle shape on operative usage of solar energy

In thermal power and manufacturing processes, solar energy utilization has grown extensively. This work investigates the heat diffusion characteristics of an unsteady Oldroyd-B hybrid nano liquid flow across an expanding cylinder. A constant magnetic field is applied in the radial path in the presence of radiant heating, generation, or sinks, and Cattaneo-Christov (CC) heat flow. Hybrid nano liquid composed of two distinct nanoparticles (CoFe2O4 and Fe3O4) embedded in ethylene glycol as the primary fluid. A mathematical model was established and reconstructed into a nonlinear ordinary differential equations (ODEs) system, utilizing the proper likeness conversion. The Matlab inbuilt bvp5c scheme determines the problem's numerical solution. We observed the instabilities in the flow and thermal area and also the local Nusselt number impacted by the pertinent dimensionless characteristics. The findings are addressed graphically and tabularly for several nanoparticle shapes (spherical, brick, and platelet). It has been discovered that spherical shapes are found to have a faster heat conduction rate than brick and platelet nanoparticle shapes for the considered flow case. While unsteadiness parameters tend to increase the temperature field, the augmentation of the temperature relaxation factor reduces the energy profile.

Influence of operating parameters on metal flow and thermal characteristics in an EMBr-single-ruler controlled CSP funnel-shaped mould

Electro-magnetic brake (EMBr), as a necessary technique to adjust the metal flow within the mould, has been extensively applied in the continuous casting (CC) production. The EMBr technique, if appropriately applied, can take the benefit of braking effect to weaken jet impingement effect, suppress fluid disturbance and stabilize surface fluctuation. As a result, to obtain a reasonable flow pattern within the CC mould, the braking performance of EMBr technique needs to be flexibly adjusted according to the variation of operational parameters. In this article, to obtain a braking performance of a commonly used EMBr-single-ruler technique within an optimal range, the effect of operating parameters on the metal liquid flow and thermal characteristics in a compact strip production (CSP) thin slab mould is described through a 3-D mathematical modeling of multi-physical field coupling. The results illustrate that the braking performance of the EMBr-single-ruler device is weakened with the increase of the casting speed or the mould width. For the effect of the casting speed and mould width on the metal flow with the application of an EMBr device, an optimum braking performance of the EMBr-single-ruler device can be obtained under the matching parameters of a magnetic induction intensity of 0.30 T and a casting speed of 4.5 m ∙ min‒1 together with a mould width of 1500 mm. Relative to the absence of the EMBr-single-ruler device, the maximum surface fluctuation height is controlled at 6.2 mm, and the mean surface temperature is raised to 1803.6 K. Based on these findings, we conclude that the proper utilization of the EMBr-single-ruler device can avoid the entrainment of flux powder and improve the melting performance of flux powder.

The Numerical Investigation of Solid–Liquid Two-Phase Flow Characteristics Inside and Outside a Newly Designed 3D Sediment Trap

Sediment transport serves as a link for material exchange between land and sea. Using sediment traps, we can observe the capture and transport processes of sediments. Based on the sediment particle size distribution characteristics in Jiaozhou Bay, this paper analyzes the influence of a newly designed 3D sediment trap on the water–sand two-phase flow process inside and outside a trap device during its operation. Meanwhile, under a certain concentration condition, a numerical formula model is researched and proposed to evaluate the impact of the device’s structure, the environmental flow speed, and the particle size on particle capture efficiency. This model is based on the CFD-DPM coupling in Fluent 2021R1 software, and the particle filtration process is solved using a combination of porous media and UDF functions. Finally, by analyzing the distribution of sediment movement in the fluid domain, two concepts, namely the percentage of particles entering the tube and the effective capture rate, are proposed. Suggestions for optimizing the structure of the trap are put forward to achieve optimal capture effects.

Numerical Simulation on Primary Breakup Characteristics of Liquid Jet in Oscillation Crossflow

In order to understand the breakup characteristics of a transverse liquid jet flow in an actual combustion chamber, a numerical study was conducted using the Volume of Fluid (VOF) method combined with grid adaptation technology. The study focused on the primary breakup characteristics of liquid jets under the conditions of a steady and oscillating air crossflow. The simulated mediums were set to water and air. The research findings revealed that fluctuations in the incoming gas velocity can influence the development speed of surface waves and the mode of jet breakup during the initial stage of jet development as compared to the steady condition. In both conditions, the surface waves were initially observed to appear within 1/4 T–2/4 T. The surface wave of the jet develops faster under steady conditions because the average velocity of the steady flow is higher than that of the oscillation flow during this stage. As a result, the fragmentation of the jet is primarily influenced by the surface wave. Under an oscillating flow, the rear of the jet begins to break up earlier due to the slower development of surface waves. The velocity of the oscillating air inflow increases over time, and the speed of surface wave development also increases, gradually leading to the dominance of surface-wave-induced jet breakup. In the second stage of air inflow oscillation, an “up and down slapping” phenomenon occurs at the tail of the jet. Additionally, increasing the air inflow velocity leads to a longer jet breakup length and a higher number of droplets near the jet column. Surface waves are observed on both the windward and leeward sides of the jet. The penetration depth of the jet fluctuates with changes in the crossflow velocity, and the response of the jet penetration depth to the velocity fluctuations in the transverse air is delayed by half a period.

On the unsteady cavitation characteristics of compressible liquid nitrogen flows through a venturi tube

In this paper, the unsteady cavitating flows of liquid nitrogen (LN2) through a three-dimensional (3D) venturi tube in different thermal cavitation modes are modeled based on the mixture multiphase model with the LES method and Sauer-Schnerr cavitation model. A numerical framework considering compressibility and the thermal effects of cryogenic fluids is developed, and the modified temperature-dependent Tait equations of state provide the mathematical closure. The numerical results are compared with those from previous experiments that we have conducted, and it is indicated that the simulations and experiments agree well. Condensation shock wave propagation is observed to be initiated by the impingement of the collapse-induced pressure waves from the previously shedding cloud, and details of the process are presented. The impacts of the thermal effect on the cavitation dynamics, especially the evolution of cavitation patterns and dynamic interactions between cavitation and vortex, are analyzed. The numerical results show that the formulation of condensation shock generated at the rear of the cavity varies with temperature. In addition to the pressure waves caused by shed vapor collapse, the violent mass transfer process at the closure region of the cavity releases a substantial quantity of latent heat, initiating further condensation towards the cavity as liquid temperature decreases. The entropy production theory is derived and implemented, and different entropy production terms are established in unsteady LN2 cavitating flow with different thermal effects to understand the interactions between cavitation and entropy production. The present study provides insight into the interactions of cavitation-condensation shock in the LN2 cavitating flow and contributes to a better understanding of the influences of thermal effects on cryogenic cavitation dynamics.