International Journal of Heat and Fluid Flow最新文献_第6页

Direct numerical simulation of turbulent flow over a wall-mounted cube placed inside a channel

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2024-12-18 DOI: 10.1016/j.ijheatfluidflow.2024.109708

Basheer A. Khan, Arun K. Saha

Direct numerical simulation (DNS) of a developing flow over a wall-mounted cube placed in a channel has been carried out at five different Reynolds numbers (

R e_{H}

) ranging from 500 to 5000 (based on the cube size and average streamwise velocity). The governing equations have been discretized using second-order spatial and temporal schemes. The influence of Reynolds number on separating shear layer transition caused by Kelvin

-

Helmholtz (

K H

) instabilities and the horseshoe vortices is addressed. We examine the topological characteristics of flow separation and reattachment phenomena at different Reynolds numbers and observe that the number of nodes and saddle points increases as the Reynolds number increases, resulting in the formation of additional recirculation regions. A large-scale Kármán vortex shedding is clearly discerned at

R e_{H} \geq 1000

, the frequency of which is found to drop with increasing Reynolds number. The analysis of turbulent kinetic energy production uncovers the presence of negative turbulence production, especially over the top/side surfaces as well as in the horseshoe vortex regime, which diminishes as the Reynolds number increases. Finally, the effect of the Reynolds number on the mean and fluctuating components of wall-shear stresses on each surface of the cube is discussed, and the results demonstrate that the Kelvin

-

Helmholtz rolls contribute significantly to the augmentation of the wall-shear stresses, particularly on the top and side surfaces.

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引用次数: 0

Investigation of the Local thermal Non-Equilibrium (LTNE) effects on magneto-natural convection of nano-encapsulated PCMs in an elliptical non-Darcian porous annulus

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2024-12-18 DOI: 10.1016/j.ijheatfluidflow.2024.109710

Tahar Tayebi , Hakan F. Öztop

Energy efficiency is primarily reliant on energy storage equipment, making it an essential technology in the current era. Thermal management, achieving a consistent temperature and adequate heat transfer through cooling, is crucial in these systems. This paper focuses on a careful analysis of the effects of Local Thermal Non-Equilibria (LTNE) on heat transfer and fluid flow by free convection in a non-Darcy porous medium saturated with a water-based suspension of Nano-Encapsulated Phase Change Materials (NEPCMs) enclosed within an elliptical annular space. This configuration is also subject to a horizontal magnetic field as a means of external control of the thermal process. The inner cylinder is kept at a higher temperature while the outer cylinder is kept at a lower temperature, resulting in convective circulation and allowing the encapsulated particles to absorb and release heat. The Darcy-Brinkman Forchheimer updated model is used to address the Navier-Stokes equations in their dimensionless form, which are then solved numerically using the finite volume method. The local thermal non-equilibrium in the porous medium, including the dimensionless interface heat transfer coefficient between the solid matrix and NEPCMS suspension (H) and thermal conductivity ratio (γ), has been analyzed for the strength of convective flow and heat transfer for the solid and fluid phases for various Stefan number (Ste) and core fusion temperature (θ_f) values. The investigation showed the importance of taking into account LTNE when improving heat transfer by natural convection process using encapsulated in nanoparticles materials (NEPCMs). The convective flow power is found to augment with H and diminish with γ. Furthermore, Nu_{s_avg} increases by 95.05% as H varies from 1 to 1000, and by about 157.5% as γ varies from 0.1 to 100. Meanwhile, Nu_{f_avg} increases by 17.18% with γ but decreases by 2.2% with H.

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引用次数: 0

Experimental study on water boiling heat transfer characteristics of microchannel surface in distributed jet array impingement with effusion slots

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2024-12-18 DOI: 10.1016/j.ijheatfluidflow.2024.109723

Xiaoyu Tang, Qiang Xu, Haoyuan Yu, Chenyu Pei, Liejin Guo

Distributed jet array impingement can improve the uneven temperature distribution and achieve high heat flux cooling. This paper experimentally investigated the two-phase heat transfer and pressure drop characteristics in a distributed jet array impingement on the microchannel surface. The test operating conditions were mass flux of 100 ∼ 200 kg/m²s, subcooling degree of 20 ∼ 40 K, jet-to-target spacing of 2 ∼ 4 mm, and atmospheric pressure at the outlet. The experimental results show that lowering subcooling from 40 K to 20 K enhances the heat transfer coefficient between 45.4 % and 57.2 % and a growth in the average pressure drop of 25.5 %. Increasing mass flux causes inlet and outlet pressure to fluctuate more sharply due to enhanced condensation. The pressure drop of single-phase forced convection and that of two-phase nucleated boiling display an opposite trend as mass flux increases. Reducing jet-to-target spacing to 2 mm exhibits a noticeable enhancement in pressure drop of more than 2.5 times, and the standard deviation of inlet pressure declines instead, indicating that decreasing jet-to-target spacing can attenuate flow instability. The coefficient of performance can be raised by increasing subcooling and jet-to-target spacing and reducing mass flux in the whole heat flux range. Expanding jet-to-target spacing from 2 mm to 4 mm can produce 105.5 % to 141.7 % higher the average coefficient of performance.

{"title":"Experimental study on water boiling heat transfer characteristics of microchannel surface in distributed jet array impingement with effusion slots","authors":"Xiaoyu Tang, Qiang Xu, Haoyuan Yu, Chenyu Pei, Liejin Guo","doi":"10.1016/j.ijheatfluidflow.2024.109723","DOIUrl":"10.1016/j.ijheatfluidflow.2024.109723","url":null,"abstract":"<div><div>Distributed jet array impingement can improve the uneven temperature distribution and achieve high heat flux cooling. This paper experimentally investigated the two-phase heat transfer and pressure drop characteristics in a distributed jet array impingement on the microchannel surface. The test operating conditions were mass flux of 100 ∼ 200 kg/m<sup>2</sup>s, subcooling degree of 20 ∼ 40 K, jet-to-target spacing of 2 ∼ 4 mm, and atmospheric pressure at the outlet. The experimental results show that lowering subcooling from 40 K to 20 K enhances the heat transfer coefficient between 45.4 % and 57.2 % and a growth in the average pressure drop of 25.5 %. Increasing mass flux causes inlet and outlet pressure to fluctuate more sharply due to enhanced condensation. The pressure drop of single-phase forced convection and that of two-phase nucleated boiling display an opposite trend as mass flux increases. Reducing jet-to-target spacing to 2 mm exhibits a noticeable enhancement in pressure drop of more than 2.5 times, and the standard deviation of inlet pressure declines instead, indicating that decreasing jet-to-target spacing can attenuate flow instability. The coefficient of performance can be raised by increasing subcooling and jet-to-target spacing and reducing mass flux in the whole heat flux range. Expanding jet-to-target spacing from 2 mm to 4 mm can produce 105.5 % to 141.7 % higher the average coefficient of performance.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"112 ","pages":"Article 109723"},"PeriodicalIF":2.6,"publicationDate":"2024-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140875","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Role of sinusoidal/linearly inner heating on the irreversibility of mixed convection in split lid-driven chamfered enclosures filled with thermal non-equilibrium permeable medium

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2024-12-16 DOI: 10.1016/j.ijheatfluidflow.2024.109715

Sameh E. Ahmed, Zehba A. Raizha

The current study aims to examine the mixed convection due to the movement of the upper-wall parts of chamfered enclosures that include obstacles having uniform/non-uniform inner temperature distributions. The irregular domain is filled by a heat-generating and permeable medium. The mixture has a temperature that differs from the included medium temperature (Two-energy equations model). Several cases are considered based on the inner heating modes: non-uniform sinusoidal heating, uniform heating mode, and non-uniform linear heating case. Also, several cases are examined based on the direction of the movement of the parts of the upper wall of the chamfered domain. An effective finite element (FE) technique based on the CBS-pressure algorithm is applied to solve the governing system with an implicit technique for the Darcy terms. The major findings revealed that the split-lid-driven irregular domain filled with thermal non-equilibrium medium with irregular inner temperature distributions has a significant role in controlling the flow and thermal fields. Also, the solid phase irreversibility gets its higher values in the sinusoidal inner heating mode while the cases where the split parts move in opposite directions cause the higher fluid friction. Moreover, for specific values of time (τ ≥ 1.5), the horizontal velocity shows an improvement up to 55 % in the uniform heating case compared to the sinusoidal heating case.

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引用次数: 0

Experimental and theoretical investigation on flash boiling spray of R134a under high temperature and high pressure

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2024-12-16 DOI: 10.1016/j.ijheatfluidflow.2024.109717

Fucheng Chang , Jiacheng Lou , Minglong Du , Xi Li , Hongwei Mao , He Hu , Huixiong Li

The flash boiling spray plays a crucial role in enhancing combustion efficiency and providing thermal protection, consequently ensuring the reliability and performance of aerospace propulsion systems, thus supporting effective space exploration and mission execution. This paper investigated the flash boiling spray and heat transfer characteristics of R134a under the conditions of initial pressure P₀ = 1.5–3.3 MPa (P₀/P_cr = 0.37–0.81) and initial temperature T₀ = 40–80 °C (T₀/T_cr = 0.84–0.94). The experimental results showed that the axial droplet temperature decreased exponentially. The radial droplet temperature was categorized into four types: “W”, “U”, “V”, and “I”, reflecting the competing influence of droplet evaporation and convective heat transfer at different positions. Increasing the initial pressure and the orifice aspect ratio, or decreasing the inlet subcooling promoted the flashing evaporation process, resulting in a more rapid decrease in axial droplet temperature. The flashing evaporation process was divided into superheat-controlled and evaporation-controlled stages, using the saturated temperature as the boundary parameters. Based on this foundation, an improved calculation model for the flash boiling spray in high-temperature and high-pressure liquids was established. The calculated results demonstrated that increasing droplet superheat or decreasing the initial droplet diameter led to a diminished axial droplet temperature, expedited flashing evaporation process, and reduced the critical time and critical distance. This study contributes to a deeper understanding of the mechanism and patterns of flash boiling spray in high-temperature and high-pressure working fluids, providing a reference for the optimization of the fuel supply process and ignition combustion process for rocket engine.

{"title":"Experimental and theoretical investigation on flash boiling spray of R134a under high temperature and high pressure","authors":"Fucheng Chang , Jiacheng Lou , Minglong Du , Xi Li , Hongwei Mao , He Hu , Huixiong Li","doi":"10.1016/j.ijheatfluidflow.2024.109717","DOIUrl":"10.1016/j.ijheatfluidflow.2024.109717","url":null,"abstract":"<div><div>The flash boiling spray plays a crucial role in enhancing combustion efficiency and providing thermal protection, consequently ensuring the reliability and performance of aerospace propulsion systems, thus supporting effective space exploration and mission execution. This paper investigated the flash boiling spray and heat transfer characteristics of R134a under the conditions of initial pressure <em>P</em><sub>0</sub> = 1.5–3.3 MPa (<em>P</em><sub>0</sub>/<em>P</em><sub>cr</sub> = 0.37–0.81) and initial temperature <em>T</em><sub>0</sub> = 40–80 °C (<em>T</em><sub>0</sub>/<em>T</em><sub>cr</sub> = 0.84–0.94). The experimental results showed that the axial droplet temperature decreased exponentially. The radial droplet temperature was categorized into four types: “W”, “U”, “V”, and “I”, reflecting the competing influence of droplet evaporation and convective heat transfer at different positions. Increasing the initial pressure and the orifice aspect ratio, or decreasing the inlet subcooling promoted the flashing evaporation process, resulting in a more rapid decrease in axial droplet temperature. The flashing evaporation process was divided into superheat-controlled and evaporation-controlled stages, using the saturated temperature as the boundary parameters. Based on this foundation, an improved calculation model for the flash boiling spray in high-temperature and high-pressure liquids was established. The calculated results demonstrated that increasing droplet superheat or decreasing the initial droplet diameter led to a diminished axial droplet temperature, expedited flashing evaporation process, and reduced the critical time and critical distance. This study contributes to a deeper understanding of the mechanism and patterns of flash boiling spray in high-temperature and high-pressure working fluids, providing a reference for the optimization of the fuel supply process and ignition combustion process for rocket engine.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"112 ","pages":"Article 109717"},"PeriodicalIF":2.6,"publicationDate":"2024-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140448","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Investigation on heat transfer and heat sink distribution of regeneration-transpiration combined cooling

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2024-12-16 DOI: 10.1016/j.ijheatfluidflow.2024.109722

Yuyang Bian , Xue Liu , Jiayue Zheng , Yanqi Diao , Weixing Zhou

A numerical model of regeneration-transpiration combined cooling is constructed to investigate the thermal protection characteristics. The influence of the coolant mass flow distribution ratio and non-uniform heat flux on the heat transfer performance is examined under both single-channel and parallel-channel configurations of the combined cooling system. In comparison to regeneration cooling, the combined cooling exhibits a significant enhancement in the cooling effect. Transpiration cooling can more effectively utilize the heat-carrying capacity of the coolant and assumes a predominant role in heat absorption within the combined cooling system. As the non-uniformity of the heat flux applied to the porous medium escalates, the non-uniformity of the transpiration coolant mass flux and the effective heat transfer coefficient rises, while the heat sink ratio of transpiration cooling to regeneration cooling declines. A negative feedback mechanism between the coolant mass flux and the thermal load is established in the parallel channels under a non-uniform thermal load, causing more coolant to flow towards the high-heat-flux region. With an increase in the non-uniformity of the thermal load in x direction, the disparities in velocity, coolant mass flow rate, and heat sink ratio distribution within the parallel channels of the combined cooling system become more pronounced.

{"title":"Investigation on heat transfer and heat sink distribution of regeneration-transpiration combined cooling","authors":"Yuyang Bian , Xue Liu , Jiayue Zheng , Yanqi Diao , Weixing Zhou","doi":"10.1016/j.ijheatfluidflow.2024.109722","DOIUrl":"10.1016/j.ijheatfluidflow.2024.109722","url":null,"abstract":"<div><div>A numerical model of regeneration-transpiration combined cooling is constructed to investigate the thermal protection characteristics. The influence of the coolant mass flow distribution ratio and non-uniform heat flux on the heat transfer performance is examined under both single-channel and parallel-channel configurations of the combined cooling system. In comparison to regeneration cooling, the combined cooling exhibits a significant enhancement in the cooling effect. Transpiration cooling can more effectively utilize the heat-carrying capacity of the coolant and assumes a predominant role in heat absorption within the combined cooling system. As the non-uniformity of the heat flux applied to the porous medium escalates, the non-uniformity of the transpiration coolant mass flux and the effective heat transfer coefficient rises, while the heat sink ratio of transpiration cooling to regeneration cooling declines. A negative feedback mechanism between the coolant mass flux and the thermal load is established in the parallel channels under a non-uniform thermal load, causing more coolant to flow towards the high-heat-flux region. With an increase in the non-uniformity of the thermal load in <em>x</em> direction, the disparities in velocity, coolant mass flow rate, and heat sink ratio distribution within the parallel channels of the combined cooling system become more pronounced.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"112 ","pages":"Article 109722"},"PeriodicalIF":2.6,"publicationDate":"2024-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140878","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Coaxial round water jet at velocity ratios close to unity, Part II: Vortex shedding and spectral analysis

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2024-12-14 DOI: 10.1016/j.ijheatfluidflow.2024.109681

D. Hasin , A. Mitra , R. van Hout

In part I of this study, planar time-resolved particle image velocimetry measurements were reported in the near-field of a coaxial jet at velocity ratios,

r_{u}

= 0.66, 1.0 and 1.32. At each

r_{u}

, at least two different Reynolds numbers, Re, were investigated. In part II of this study, instantaneous vortex characteristics are studied. Instantaneous swirling strength maps revealed “trains” of alternating sign vortices as a result of shear and wake instabilities. Their spatial distribution strongly depended on

r_{u}

. In contrast, Re effects on their size and number were small, but their circulation increased with Re as well as with

r_{u}

. The circulation of outer shear layer vortices collapsed when normalized by the outer jet’s diameter and jet exit velocity for all investigated conditions. No such scaling was found for inner shear layer vortices. Spectral analysis revealed distinct “islands” of high and low peak passage frequencies associated with the inner and outer shear layers, respectively, indicating that “lock-in” between inner and outer shear layers was absent. Strouhal numbers were similar for all Re and

r_{u}

and those based on momentum thicknesses indicated that inner and outer jets did not develop independently.

{"title":"Coaxial round water jet at velocity ratios close to unity, Part II: Vortex shedding and spectral analysis","authors":"D. Hasin , A. Mitra , R. van Hout","doi":"10.1016/j.ijheatfluidflow.2024.109681","DOIUrl":"10.1016/j.ijheatfluidflow.2024.109681","url":null,"abstract":"<div><div>In part I of this study, planar time-resolved particle image velocimetry measurements were reported in the near-field of a coaxial jet at velocity ratios, <span><math><msub><mrow><mi>r</mi></mrow><mrow><mi>u</mi></mrow></msub></math></span> = 0.66, 1.0 and 1.32. At each <span><math><msub><mrow><mi>r</mi></mrow><mrow><mi>u</mi></mrow></msub></math></span>, at least two different Reynolds numbers, Re, were investigated. In part II of this study, instantaneous vortex characteristics are studied. Instantaneous swirling strength maps revealed “trains” of alternating sign vortices as a result of shear and wake instabilities. Their spatial distribution strongly depended on <span><math><msub><mrow><mi>r</mi></mrow><mrow><mi>u</mi></mrow></msub></math></span>. In contrast, Re effects on their size and number were small, but their circulation increased with Re as well as with <span><math><msub><mrow><mi>r</mi></mrow><mrow><mi>u</mi></mrow></msub></math></span>. The circulation of outer shear layer vortices collapsed when normalized by the outer jet’s diameter and jet exit velocity for all investigated conditions. No such scaling was found for inner shear layer vortices. Spectral analysis revealed distinct “islands” of high and low peak passage frequencies associated with the inner and outer shear layers, respectively, indicating that “lock-in” between inner and outer shear layers was absent. Strouhal numbers were similar for all Re and <span><math><msub><mrow><mi>r</mi></mrow><mrow><mi>u</mi></mrow></msub></math></span> and those based on momentum thicknesses indicated that inner and outer jets did not develop independently.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"112 ","pages":"Article 109681"},"PeriodicalIF":2.6,"publicationDate":"2024-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140876","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A systematic review of flow instability influencing factors and mechanisms in supercritical fluids

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2024-12-14 DOI: 10.1016/j.ijheatfluidflow.2024.109677

Attiq Ur Rehman , Xiaocheng Du , Hassaan Ahmad , Dong Yang

Supercritical fluids (SCFs) offer promising potential for creating efficient, compact, and sustainable energy systems due to their ability to enhance heat transfer and enable more efficient power cycles. However, SCFs exhibit complex behaviors near their critical points, where small variations in temperature and pressure can lead to flow instability. Understanding and mitigating flow instability in SCFs is crucial for ensuring the safe and reliable operation of advanced energy systems. In this systematic review the research questions were formulated to identify the influencing factors, their effect, and strategies to tackle the SCFs flow instability. Although research on SCFs flow instability is limited, the review revealed that following influencing factors were investigated by researchers: flow direction, geometric parameters, inlet orifice coefficient, heat flux, mass flow rate, inlet temperature and pressure. These factors have significant effects on the SCFs flow instability which are summarized in detailed in the article. Additionally, this review discusses flow instability mitigation strategies, and associated challenges. The insights from this review highlight the needs for ongoing research and innovative approaches to enhance the safety of SCFs applications, paving the way for advancements in next-generation technologies.

{"title":"A systematic review of flow instability influencing factors and mechanisms in supercritical fluids","authors":"Attiq Ur Rehman , Xiaocheng Du , Hassaan Ahmad , Dong Yang","doi":"10.1016/j.ijheatfluidflow.2024.109677","DOIUrl":"10.1016/j.ijheatfluidflow.2024.109677","url":null,"abstract":"<div><div>Supercritical fluids (SCFs) offer promising potential for creating efficient, compact, and sustainable energy systems due to their ability to enhance heat transfer and enable more efficient power cycles. However, SCFs exhibit complex behaviors near their critical points, where small variations in temperature and pressure can lead to flow instability. Understanding and mitigating flow instability in SCFs is crucial for ensuring the safe and reliable operation of advanced energy systems. In this systematic review the research questions were formulated to identify the influencing factors, their effect, and strategies to tackle the SCFs flow instability. Although research on SCFs flow instability is limited, the review revealed that following influencing factors were investigated by researchers: flow direction, geometric parameters, inlet orifice coefficient, heat flux, mass flow rate, inlet temperature and pressure. These factors have significant effects on the SCFs flow instability which are summarized in detailed in the article. Additionally, this review discusses flow instability mitigation strategies, and associated challenges. The insights from this review highlight the needs for ongoing research and innovative approaches to enhance the safety of SCFs applications, paving the way for advancements in next-generation technologies.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"112 ","pages":"Article 109677"},"PeriodicalIF":2.6,"publicationDate":"2024-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140601","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Stability analysis of MHD thermo-capillary hybrid nanofluids in cylindrical flow within a porous medium

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2024-12-13 DOI: 10.1016/j.ijheatfluidflow.2024.109718

Zakir Hussain , Adeel Nauman , Mehboob Ali , Waqar Azeem Khan , Mohammed Kbiri Alaoui , Islam Mazahirul

This article consists of stability of Hydro-magnetic poiseuille flow through a cylinder having a porous medium by using hybrid nanofluids under the influence of a transverse magnetic field. Considering the mentioned activities, stability analysis is examined by varying the different parameters i.e. Reynolds number R, volume fraction φ, wave number k, and Hartmann number Ha. The result for the system of the equation is numerically obtained by using “The Cheybeshev Collocation method”. To search Eigenvalues from the generalized Orr-Sommerfleld equation, the algorithm “QZ” is used. The stability of said combination is evaluated by the graphs. The shear thinning effect for linear flow is destabilizing for small Pr but marginally increases the stability for higher Pr. Water-based nanofluid has a more stabilizing effect than kerosene oil, ethyl glycol, and engine oil. Simple shear influences the flow arrangements, thus allowing compression to stable or unstable the flow. While Renoylds number gets high will lead to growth, decreases the stability of flow. k and Ha have the stabilizing effect while Re and Pr destabilizes influence on the hybrid fluid flow.

{"title":"Stability analysis of MHD thermo-capillary hybrid nanofluids in cylindrical flow within a porous medium","authors":"Zakir Hussain , Adeel Nauman , Mehboob Ali , Waqar Azeem Khan , Mohammed Kbiri Alaoui , Islam Mazahirul","doi":"10.1016/j.ijheatfluidflow.2024.109718","DOIUrl":"10.1016/j.ijheatfluidflow.2024.109718","url":null,"abstract":"<div><div>This article consists of stability of Hydro-magnetic poiseuille flow through a cylinder having a porous medium by using hybrid nanofluids under the influence of a transverse magnetic field. Considering the mentioned activities, stability analysis is examined by varying the different parameters <em>i.e.</em> Reynolds number <em>R</em>, volume fraction <em>φ</em>, wave number <em>k,</em> and Hartmann number <em>Ha</em>. The result for the system of the equation is numerically obtained by using “The Cheybeshev Collocation method”. To search Eigenvalues from the generalized Orr-Sommerfleld equation, the algorithm “QZ” is used. The stability of said combination is evaluated by the graphs. The shear thinning effect for linear flow is destabilizing for small <em>Pr</em> but marginally increases the stability for higher <em>Pr</em>. Water-based nanofluid has a more stabilizing effect than kerosene oil, ethyl glycol, and engine oil. Simple shear influences the flow arrangements, thus allowing compression to stable or unstable the flow. While Renoylds number gets high will lead to growth, decreases the stability of flow. <em>k</em> and <em>Ha</em> have the stabilizing effect while <em>Re</em> and <em>Pr</em> destabilizes influence on the hybrid fluid flow.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"112 ","pages":"Article 109718"},"PeriodicalIF":2.6,"publicationDate":"2024-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140452","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Optimization of heat exchanger with biomimetic shark skin riblet structure using artificial neural network

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2024-12-13 DOI: 10.1016/j.ijheatfluidflow.2024.109720

Qi Jin , Xuemei Chen , Chaolei Yang , Xuanjie Wang , Fang Wang

This study presents an in-depth investigation into the design and performance optimization of louvered fin heat exchangers, drawing inspiration from the riblet structures found on shark skin. The louvered fin design targets the enhancement of heat transfer efficiency concurrent with the reduction of flow resistance. The findings indicate that the integration of shark skin riblet fin results in an 8.3% to 13% improvement in overall heat exchanger performance in comparison to straight fins. To maximize the overall performance, an Artificial Neural Network model was engaged to identify the optimal fin design parameters. The input variables were defined as riblet width, riblet height, and riblet number, with the output variable being the overall performance enhancement. The model demonstrated high predictive accuracy with a MAPE of 0.0885%, an R² of 0.991, and a RMSE of 0.00258 across the dataset. The optimal parameter values proposed by the ANN model for achieving the highest flow and heat transfer performance were identified which could provide significant insights for the optimization of louvered fin designs, aiming for superior heat transfer efficiency and minimized energy expenditure.

{"title":"Optimization of heat exchanger with biomimetic shark skin riblet structure using artificial neural network","authors":"Qi Jin , Xuemei Chen , Chaolei Yang , Xuanjie Wang , Fang Wang","doi":"10.1016/j.ijheatfluidflow.2024.109720","DOIUrl":"10.1016/j.ijheatfluidflow.2024.109720","url":null,"abstract":"<div><div>This study presents an in-depth investigation into the design and performance optimization of louvered fin heat exchangers, drawing inspiration from the riblet structures found on shark skin. The louvered fin design targets the enhancement of heat transfer efficiency concurrent with the reduction of flow resistance. The findings indicate that the integration of shark skin riblet fin results in an 8.3% to 13% improvement in overall heat exchanger performance in comparison to straight fins. To maximize the overall performance, an Artificial Neural Network model was engaged to identify the optimal fin design parameters. The input variables were defined as riblet width, riblet height, and riblet number, with the output variable being the overall performance enhancement. The model demonstrated high predictive accuracy with a MAPE of 0.0885%, an R<sup>2</sup> of 0.991, and a RMSE of 0.00258 across the dataset. The optimal parameter values proposed by the ANN model for achieving the highest flow and heat transfer performance were identified which could provide significant insights for the optimization of louvered fin designs, aiming for superior heat transfer efficiency and minimized energy expenditure.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"112 ","pages":"Article 109720"},"PeriodicalIF":2.6,"publicationDate":"2024-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140449","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0