International Journal of Heat and Fluid Flow最新文献

英文中文

Effects of fin shapes and orientations with cyclic heating and cooling on melting and solidification of PCM-filled closed space

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2025-01-16 DOI: 10.1016/j.ijheatfluidflow.2025.109753

Burak Kıyak , Hakan F. Öztop , Nirmalendu Biswas , Hakan Coşanay , Fatih Selimefendigil

Phase-change materials (PCMs) offer an effective way to store and release thermal energy to balance the supply and demand for energy. Both the melting and solidification processes have a major impact on how effectively energy storage works and also it is affected by the thermal conditions of the heating or cooling source. Thermal energy storage systems using (PCMs are often limited by slow melting and solidification rates. The current work explores a novel strategy of cyclic heating and cooling for improving the PCM melting and solidification process combined with variations in fin shapes and orientations, to address these inefficiencies. The fins are heated and cooled following cyclic heating and cooling pattern for three different cycle periods (CP) with same amplitude. As a result, PCM is subjected to cyclic heating and cooling. The finite volume method is employed to analyze the impact of cyclic heating–cooling cycles on PCM performance. An analysis is also conducted on the impact of the relative shape of fins—that is, flat, concave, and convex, positions—vertical and horizontal—on the melting and solidification process under three different cycle periods. By applying a finite volume-based computational approach, the numerical model is solved. It is observed that the overall thermal performance of PCM-based energy storage is modulated by the cyclic heating–cooling arrangements. With this, melting time is reduced by 47.1 % compared to horizontal fin arrangement. When the fin pair is arranged vertically (θ = 0°), with the increase in the cycle period to CP3, the amount of stored energy (during the heating cycle) is about 24.7 %. Similarly, the amount of stored energy recovery (during the cooling cycle) is about 43.6 %. When the fin pair is arranged horizontally (θ = 90°), the amount of energy stored is up to 10 % due to the increase in the cycle periods. Similarly, the amount of stored energy recovery (during the cooling cycle) is about 38.5 %. An improved fin designs, combined with cyclic heating–cooling strategies, present an effective solution to enhance PCM-based thermal energy storage systems.

{"title":"Effects of fin shapes and orientations with cyclic heating and cooling on melting and solidification of PCM-filled closed space","authors":"Burak Kıyak , Hakan F. Öztop , Nirmalendu Biswas , Hakan Coşanay , Fatih Selimefendigil","doi":"10.1016/j.ijheatfluidflow.2025.109753","DOIUrl":"10.1016/j.ijheatfluidflow.2025.109753","url":null,"abstract":"<div><div>Phase-change materials (PCMs) offer an effective way to store and release thermal energy to balance the supply and demand for energy. Both the melting and solidification processes have a major impact on how effectively energy storage works and also it is affected by the thermal conditions of the heating or cooling source. Thermal energy storage systems using (PCMs are often limited by slow melting and solidification rates. The current work explores a novel strategy of cyclic heating and cooling for improving the PCM melting and solidification process combined with variations in fin shapes and orientations, to address these inefficiencies. The fins are heated and cooled following cyclic heating and cooling pattern for three different cycle periods (CP) with same amplitude. As a result, PCM is subjected to cyclic heating and cooling. The finite volume method is employed to analyze the impact of cyclic heating–cooling cycles on PCM performance. An analysis is also conducted on the impact of the relative shape of fins—that is, flat, concave, and convex, positions—vertical and horizontal—on the melting and solidification process under three different cycle periods. By applying a finite volume-based computational approach, the numerical model is solved. It is observed that the overall thermal performance of PCM-based energy storage is modulated by the cyclic heating–cooling arrangements. With this, melting time is reduced by 47.1 % compared to horizontal fin arrangement. When the fin pair is arranged vertically (<em>θ</em> = 0°), with the increase in the cycle period to CP3, the amount of stored energy (during the heating cycle) is about 24.7 %. Similarly, the amount of stored energy recovery (during the cooling cycle) is about 43.6 %. When the fin pair is arranged horizontally (<em>θ</em> = 90°), the amount of energy stored is up to 10 % due to the increase in the cycle periods. Similarly, the amount of stored energy recovery (during the cooling cycle) is about 38.5 %. An improved fin designs, combined with cyclic heating–cooling strategies, present an effective solution to enhance PCM-based thermal energy storage systems.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"112 ","pages":"Article 109753"},"PeriodicalIF":2.6,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140605","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

Experimental investigation of droplet moving on a horizontal metal plate driven by cold airflow

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2025-01-16 DOI: 10.1016/j.ijheatfluidflow.2025.109747

Shuoshuo Wang, Shinan Chang, Weidong Yu, Ke Wu

The deformation and movement of droplets are a fundamental phenomenon in nature and industry. The droplet under shear airflow is involved in many aspects, and research on the droplet under different experimental conditions, such as airflow temperature, is still lacking. A series of experiments on droplet motion under different conditions were carried out. The speed and temperature of airflow ranged from 17.0 m/s to 35.0 m/s and −17.0 °C to 20.0 °C, respectively. The droplet volume varied from 5.0 to 40.0 μL. The droplet properties did not change under the cold airflow in the test time, which indicated that it did not freeze and remained liquid for a period of time. During the whole droplet motion in the view, no solidification is observed. The characteristic parameters including the position of the droplet centre, the wetting length, the droplet height and the difference between the cosines of the front contact angle and the rear contact angle (cah) of droplet were obtained by image post-processing. The maximum length ratio and the maximum height ratio of droplet deformation were discussed. The morphology of a droplet during its motion was classified into three regimes according to the droplet Reynolds number, S (sliding slightly), SS (sliding and moving), and SRS (sliding and rivulet formation, and separation). A map of the regimes of droplet motion under different conditions was obtained. It is found that when the Re_d is in a range from 0 to 25, the droplet motion is Regime I (S). With the Re_d increasing, the different regimes appeared. The order in which they appear is S, SS, and SRS. This study provides experimental reference data for the study of the droplet motion in different temperatures and shear of airflow.

{"title":"Experimental investigation of droplet moving on a horizontal metal plate driven by cold airflow","authors":"Shuoshuo Wang, Shinan Chang, Weidong Yu, Ke Wu","doi":"10.1016/j.ijheatfluidflow.2025.109747","DOIUrl":"10.1016/j.ijheatfluidflow.2025.109747","url":null,"abstract":"<div><div>The deformation and movement of droplets are a fundamental phenomenon in nature and industry. The droplet under shear airflow is involved in many aspects, and research on the droplet under different experimental conditions, such as airflow temperature, is still lacking. A series of experiments on droplet motion under different conditions were carried out. The speed and temperature of airflow ranged from 17.0 m/s to 35.0 m/s and −17.0 °C to 20.0 °C, respectively. The droplet volume varied from 5.0 to 40.0 μL. The droplet properties did not change under the cold airflow in the test time, which indicated that it did not freeze and remained liquid for a period of time. During the whole droplet motion in the view, no solidification is observed. The characteristic parameters including the position of the droplet centre, the wetting length, the droplet height and the difference between the cosines of the front contact angle and the rear contact angle (<em>cah</em>) of droplet were obtained by image post-processing. The maximum length ratio and the maximum height ratio of droplet deformation were discussed. The morphology of a droplet during its motion was classified into three regimes according to the droplet Reynolds number, S (sliding slightly), SS (sliding and moving), and SRS (sliding and rivulet formation, and separation). A map of the regimes of droplet motion under different conditions was obtained. It is found that when the Re<sub>d</sub> is in a range from 0 to 25, the droplet motion is Regime I (S). With the Re<sub>d</sub> increasing, the different regimes appeared. The order in which they appear is S, SS, and SRS. This study provides experimental reference data for the study of the droplet motion in different temperatures and shear of airflow.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"112 ","pages":"Article 109747"},"PeriodicalIF":2.6,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140899","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

Comparative analysis of heat transfer enhancement in nucleate pool boiling using different fin geometries

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2025-01-15 DOI: 10.1016/j.ijheatfluidflow.2025.109746

Keyhan Kouzegar Ghiyasi, Siamak Hossainpour

This study investigates the effect of surface geometry on nucleate pool boiling heat transfer, focusing on smooth, rectangular finned, and trapezoidal finned surfaces. Using the Volume of Fluid (VOF) method in a two-dimensional numerical analysis, the research provides comprehensive insights into bubble dynamics, including nucleation, growth, detachment, and liquid–vapor interactions. The study shows good agreement between the numerical model results and experimental data, confirming the accuracy and reliability of the VOF method in simulating complex boiling phenomena. The results indicate that finned surfaces significantly enhance heat transfer compared to smooth surfaces, with trapezoidal fins demonstrating the best performance. Trapezoidal fins improved by 133% in the heat transfer coefficient (HTC) and 210% in heat flux compared to smooth surfaces, attributed to their optimized geometry that enhances bubble dynamics and thermal efficiency. Rectangular fins also showed sensitivity to fin height and spacing changes, with improvements of up to 95% in HTC and 150% in heat flux. This study provides practical guidelines for designing advanced heat transfer surfaces, with significant applications in thermal management systems for industries such as power generation, cooling systems, and electronics.

{"title":"Comparative analysis of heat transfer enhancement in nucleate pool boiling using different fin geometries","authors":"Keyhan Kouzegar Ghiyasi, Siamak Hossainpour","doi":"10.1016/j.ijheatfluidflow.2025.109746","DOIUrl":"10.1016/j.ijheatfluidflow.2025.109746","url":null,"abstract":"<div><div>This study investigates the effect of surface geometry on nucleate pool boiling heat transfer, focusing on smooth, rectangular finned, and trapezoidal finned surfaces. Using the Volume of Fluid (VOF) method in a two-dimensional numerical analysis, the research provides comprehensive insights into bubble dynamics, including nucleation, growth, detachment, and liquid–vapor interactions. The study shows good agreement between the numerical model results and experimental data, confirming the accuracy and reliability of the VOF method in simulating complex boiling phenomena. The results indicate that finned surfaces significantly enhance heat transfer compared to smooth surfaces, with trapezoidal fins demonstrating the best performance. Trapezoidal fins improved by 133% in the heat transfer coefficient (HTC) and 210% in heat flux compared to smooth surfaces, attributed to their optimized geometry that enhances bubble dynamics and thermal efficiency. Rectangular fins also showed sensitivity to fin height and spacing changes, with improvements of up to 95% in HTC and 150% in heat flux. This study provides practical guidelines for designing advanced heat transfer surfaces, with significant applications in thermal management systems for industries such as power generation, cooling systems, and electronics.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"112 ","pages":"Article 109746"},"PeriodicalIF":2.6,"publicationDate":"2025-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140901","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

Natural convection through and over a heating porous medium: Towards high fidelity simulations of nuclear spent fuel pools

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2025-01-09 DOI: 10.1016/j.ijheatfluidflow.2024.109724

Victoria Hamtiaux , Pierre Ruyer , Yann Bartosiewicz

This paper presents a numerical investigation involving Direct Numerical Simulations (DNS) of natural convection occurring within mixed domains of porous and pure fluids, featuring an internally heated solid matrix. Our study does not aim to replicate 1:1 scale of Spent Fuel Pool (SFP) scenarios during Loss of Cooling Accidents (LOCA), but rather focuses on a reduced scale mock-up of such pool while keeping essential phenomena. By doing such, this study does provide valuable insights into the intricate dynamics of fluid flow and heat transfer in such prototypical configuration. We conduct a sensitivity analysis on the parameters driving the physical modeling of the porous medium, revealing the substantial influence of the drag on key features of the heat and mass transfers such as the Large-Scale Circulation (LSC), mass flow rates, temperatures within the porous medium, and overall heat transfer process. In a domain scaled to represent a reduced-scale SFP (1:200), we explore the effects of varying rack heights relative to the bottom wall. This variation significantly affects temperature distribution within both the bottom layer and the porous medium. Notably, when the racks make contact with the bottom wall, a dual-roll LSC pattern emerges. Additionally, we examine the consequences of non-uniform heat load distribution within the racks. This distribution leads to larger maximum temperatures within the most heated region of the porous medium. However, it also results in lower area-averaged temperatures due to increased horizontal diffusion and mixing. Consequently, the Nusselt number within the pure-fluid region is reduced compared to a scenario with uniform heat load distribution.

{"title":"Natural convection through and over a heating porous medium: Towards high fidelity simulations of nuclear spent fuel pools","authors":"Victoria Hamtiaux , Pierre Ruyer , Yann Bartosiewicz","doi":"10.1016/j.ijheatfluidflow.2024.109724","DOIUrl":"10.1016/j.ijheatfluidflow.2024.109724","url":null,"abstract":"<div><div>This paper presents a numerical investigation involving Direct Numerical Simulations (DNS) of natural convection occurring within mixed domains of porous and pure fluids, featuring an internally heated solid matrix. Our study does not aim to replicate 1:1 scale of Spent Fuel Pool (SFP) scenarios during Loss of Cooling Accidents (LOCA), but rather focuses on a reduced scale mock-up of such pool while keeping essential phenomena. By doing such, this study does provide valuable insights into the intricate dynamics of fluid flow and heat transfer in such prototypical configuration. We conduct a sensitivity analysis on the parameters driving the physical modeling of the porous medium, revealing the substantial influence of the drag on key features of the heat and mass transfers such as the Large-Scale Circulation (LSC), mass flow rates, temperatures within the porous medium, and overall heat transfer process. In a domain scaled to represent a reduced-scale SFP (1:200), we explore the effects of varying rack heights relative to the bottom wall. This variation significantly affects temperature distribution within both the bottom layer and the porous medium. Notably, when the racks make contact with the bottom wall, a dual-roll LSC pattern emerges. Additionally, we examine the consequences of non-uniform heat load distribution within the racks. This distribution leads to larger maximum temperatures within the most heated region of the porous medium. However, it also results in lower area-averaged temperatures due to increased horizontal diffusion and mixing. Consequently, the Nusselt number within the pure-fluid region is reduced compared to a scenario with uniform heat load distribution.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"112 ","pages":"Article 109724"},"PeriodicalIF":2.6,"publicationDate":"2025-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140903","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

Research on liquid-cooling structure for lithium-ion battery with bionic leaf-vein liquid channels

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2025-01-09 DOI: 10.1016/j.ijheatfluidflow.2025.109743

Runze Yan , Qinghai Zhao , Chao Zhang , Qingheng Tang , Honghui Li

Effective thermal management is crucial for the thermal safety and temperature uniformity of Lithium-ion batteries. Taking inspiration from the natural leaf-vein structure, this paper proposes a cold plate with novel internal bionic leaf-vein liquid channels. Three-dimensional cold plate models are established according to the contour of leaf-vein for multi-physical field numerical simulations. The effects of different flow rates and inlet/outlet arrangements on the heat transfer performance are investigated. The velocity, temperature, and pressure fields are calculated with the finite element method. Compared with the conventional rectangular flow channel, the results demonstrate that the maximum temperature of the cooling plate with the bionic-type structure is reduced by 10.17 K and the heat transfer efficiency is increased by 22.43 %. Finally, the properties of the test samples are compared to verify the numerical results. The proposed bionic leaf-vein cooling channels provide a positive direction for designing lithium-ion battery cooling systems to control the temperature distribution of the cell module.

{"title":"Research on liquid-cooling structure for lithium-ion battery with bionic leaf-vein liquid channels","authors":"Runze Yan , Qinghai Zhao , Chao Zhang , Qingheng Tang , Honghui Li","doi":"10.1016/j.ijheatfluidflow.2025.109743","DOIUrl":"10.1016/j.ijheatfluidflow.2025.109743","url":null,"abstract":"<div><div>Effective thermal management is crucial for the thermal safety and temperature uniformity of Lithium-ion batteries. Taking inspiration from the natural leaf-vein structure, this paper proposes a cold plate with novel internal bionic leaf-vein liquid channels. Three-dimensional cold plate models are established according to the contour of leaf-vein for multi-physical field numerical simulations. The effects of different flow rates and inlet/outlet arrangements on the heat transfer performance are investigated. The velocity, temperature, and pressure fields are calculated with the finite element method. Compared with the conventional rectangular flow channel, the results demonstrate that the maximum temperature of the cooling plate with the bionic-type structure is reduced by 10.17 K and the heat transfer efficiency is increased by 22.43 %. Finally, the properties of the test samples are compared to verify the numerical results. The proposed bionic leaf-vein cooling channels provide a positive direction for designing lithium-ion battery cooling systems to control the temperature distribution of the cell module.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"112 ","pages":"Article 109743"},"PeriodicalIF":2.6,"publicationDate":"2025-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140900","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

The ion current response of a laminar lifted non-premixed flame in a DC electric field

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2025-01-09 DOI: 10.1016/j.ijheatfluidflow.2024.109740

Yu-Ren Chien , Chiang Fu , Ying-Hao Liao

This study investigates the impact of a DC electric field on the lift-off height and ion current of a laminar lifted non-premixed jet flame. The experimental setup includes two horizontal electrodes that creates a vertical electric field aligned with the jet flow, with a positive field directing from the burner toward the downstream electrode. Results show that a DC electric field, regardless of polarity, reduces the flame lift-off height, with sufficiently strong fields causing flame reattachment. Flames with higher fuel flow rates exhibit larger lift-off heights and require stronger electric fields for reattachment, whereas lower flow rates are more sensitive to the applied field. Negative electric fields are more effective at reducing lift-off height and generating higher ion currents than positive fields. Ion current measurements reveal a strong correlation between field strength and flame reattachment, with ion current increasing significantly as the flame transitions from lift-off to reattachment. The study proposes a scaling relation between ion current, flame lift-off height, and electric field strength, demonstrating that ionic wind driven by the electric force plays a crucial role in flame stabilization. These findings suggest that DC electric fields offer a promising approach for controlling flame behavior, with potential applications in enhancing combustion efficiency and stability.

{"title":"The ion current response of a laminar lifted non-premixed flame in a DC electric field","authors":"Yu-Ren Chien , Chiang Fu , Ying-Hao Liao","doi":"10.1016/j.ijheatfluidflow.2024.109740","DOIUrl":"10.1016/j.ijheatfluidflow.2024.109740","url":null,"abstract":"<div><div>This study investigates the impact of a DC electric field on the lift-off height and ion current of a laminar lifted non-premixed jet flame. The experimental setup includes two horizontal electrodes that creates a vertical electric field aligned with the jet flow, with a positive field directing from the burner toward the downstream electrode. Results show that a DC electric field, regardless of polarity, reduces the flame lift-off height, with sufficiently strong fields causing flame reattachment. Flames with higher fuel flow rates exhibit larger lift-off heights and require stronger electric fields for reattachment, whereas lower flow rates are more sensitive to the applied field. Negative electric fields are more effective at reducing lift-off height and generating higher ion currents than positive fields. Ion current measurements reveal a strong correlation between field strength and flame reattachment, with ion current increasing significantly as the flame transitions from lift-off to reattachment. The study proposes a scaling relation between ion current, flame lift-off height, and electric field strength, demonstrating that ionic wind driven by the electric force plays a crucial role in flame stabilization. These findings suggest that DC electric fields offer a promising approach for controlling flame behavior, with potential applications in enhancing combustion efficiency and stability.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"112 ","pages":"Article 109740"},"PeriodicalIF":2.6,"publicationDate":"2025-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140161","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

Numerical investigation on thermal–hydraulic performance of an intercooler with bionic channel textures

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2025-01-08 DOI: 10.1016/j.ijheatfluidflow.2025.109744

Jin Wang , Jin Yao , Xuan Liang , Zhenxin Li , Fei Lu , Lidija Čuček , Dan Zheng

Intercoolers are widely employed in automotive applications, especially in turbocharged engines, to enhance engine power output by cooling the intake air, which improves combustion efficiency and reduces the risk of engine knock. This paper investigates three innovative bionic textures in channels to enhance the heat transfer characteristics of intercoolers. The thermal–hydraulic performance of the intercooler is optimized by analyzing the geometric parameters of the bionic texture structures. The investigated geometric parameters of this study are the height (h_c) and radius ratio (r) of the bionic crab surface texture, the groove length (s) and groove height (h_s) of the bionic shark-skin texture as well as fish scale opening angle (α) and the inclination angle (β) of the bionic fish scale texture. The application of bionic textures in channels leads to a maximum increment of 14.95% in the heat transfer performance for the intercooler. This paper compares the thermal–hydraulic performance of the three bionic channel textures. Among the three bionic textures, the bionic crab shell texture demonstrates the optimal comprehensive performance, improving the JF factor by up to 15.02%. The increment in the JF factor achieved by the bionic crab shell texture is 175.95% and 42.35% higher than the maximum increments achieved by the bionic fish scale and bionic shark-skin textures, respectively. The application of nature-inspired designs to thermal systems offers a new pathway to enhance heat transfer in intercoolers. The results provide theoretical guidance for designing high-performance intercoolers with excellent thermal–hydraulic performance. By bridging bio-inspired design with heat exchangers, this study provides innovative solutions for more efficient cooling systems in automotive and industrial applications.

{"title":"Numerical investigation on thermal–hydraulic performance of an intercooler with bionic channel textures","authors":"Jin Wang , Jin Yao , Xuan Liang , Zhenxin Li , Fei Lu , Lidija Čuček , Dan Zheng","doi":"10.1016/j.ijheatfluidflow.2025.109744","DOIUrl":"10.1016/j.ijheatfluidflow.2025.109744","url":null,"abstract":"<div><div>Intercoolers are widely employed in automotive applications, especially in turbocharged engines, to enhance engine power output by cooling the intake air, which improves combustion efficiency and reduces the risk of engine knock. This paper investigates three innovative bionic textures in channels to enhance the heat transfer characteristics of intercoolers. The thermal–hydraulic performance of the intercooler is optimized by analyzing the geometric parameters of the bionic texture structures. The investigated geometric parameters of this study are the height (<em>h<sub>c</sub></em>) and radius ratio (<em>r</em>) of the bionic crab surface texture, the groove length (<em>s</em>) and groove height (<em>h</em><sub>s</sub>) of the bionic shark-skin texture as well as fish scale opening angle (<em>α</em>) and the inclination angle (<em>β</em>) of the bionic fish scale texture. The application of bionic textures in channels leads to a maximum increment of 14.95% in the heat transfer performance for the intercooler. This paper compares the thermal–hydraulic performance of the three bionic channel textures. Among the three bionic textures, the bionic crab shell texture demonstrates the optimal comprehensive performance, improving the <em>JF</em> factor by up to 15.02%. The increment in the <em>JF</em> factor achieved by the bionic crab shell texture is 175.95% and 42.35% higher than the maximum increments achieved by the bionic fish scale and bionic shark-skin textures, respectively. The application of nature-inspired designs to thermal systems offers a new pathway to enhance heat transfer in intercoolers. The results provide theoretical guidance for designing high-performance intercoolers with excellent thermal–hydraulic performance. By bridging bio-inspired design with heat exchangers, this study provides innovative solutions for more efficient cooling systems in automotive and industrial applications.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"112 ","pages":"Article 109744"},"PeriodicalIF":2.6,"publicationDate":"2025-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140905","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 coherent structures in the transport equation for the vorticity–temperature correlation

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2025-01-08 DOI: 10.1016/j.ijheatfluidflow.2024.109696

Shumpei Hara , Koji Fukudome , Kyoji Inaoka

Understanding scalar transport phenomena is crucial for effective turbulent mixing in various applications. However, this process is complex and challenging to grasp. Coherent structures offer insight into the mechanisms governing scalar dynamics in turbulent flows and can serve as a valuable tool for developing turbulence models. This study presents theoretical and numerical investigations of the transport equation for the vorticity–temperature correlation, known as “scalicity.” The transport equation for scalicity was derived through order estimation. Direct numerical simulations of turbulent-plane Couette flows with passive scalar transport were conducted. A notable spanwise-averaged scalicity fluctuation component was identified in the viscous and buffer layers. This component was analyzed by examining the high correlation between spanwise vorticity and temperature fluctuations, evaluating quadrant contributions, and decomposing the terms. Visualization of the instantaneous field with spanwise scalicity fluctuations highlighted the cyclical relationship between velocity streaks and longitudinal vortices and the unstable wall vorticity layer in turbulent heat transfer. Budget analysis of the transport equation provided insights into the velocity and temperature streaks associated with turbulent eddy structures.

{"title":"Role of coherent structures in the transport equation for the vorticity–temperature correlation","authors":"Shumpei Hara , Koji Fukudome , Kyoji Inaoka","doi":"10.1016/j.ijheatfluidflow.2024.109696","DOIUrl":"10.1016/j.ijheatfluidflow.2024.109696","url":null,"abstract":"<div><div>Understanding scalar transport phenomena is crucial for effective turbulent mixing in various applications. However, this process is complex and challenging to grasp. Coherent structures offer insight into the mechanisms governing scalar dynamics in turbulent flows and can serve as a valuable tool for developing turbulence models. This study presents theoretical and numerical investigations of the transport equation for the vorticity–temperature correlation, known as “scalicity.” The transport equation for scalicity was derived through order estimation. Direct numerical simulations of turbulent-plane Couette flows with passive scalar transport were conducted. A notable spanwise-averaged scalicity fluctuation component was identified in the viscous and buffer layers. This component was analyzed by examining the high correlation between spanwise vorticity and temperature fluctuations, evaluating quadrant contributions, and decomposing the terms. Visualization of the instantaneous field with spanwise scalicity fluctuations highlighted the cyclical relationship between velocity streaks and longitudinal vortices and the unstable wall vorticity layer in turbulent heat transfer. Budget analysis of the transport equation provided insights into the velocity and temperature streaks associated with turbulent eddy structures.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"112 ","pages":"Article 109696"},"PeriodicalIF":2.6,"publicationDate":"2025-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140902","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

The influence of air temperature on heat transfer coefficient under forced air-cooling conditions

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2025-01-06 DOI: 10.1016/j.ijheatfluidflow.2024.109741

Ziwei Xia , Minxiang Su , Shuai Li , Jiaxin Shi , Wei Yu

Employing a combined approach of offline experiments and numerical simulations, this study investigates the temperature distribution of steel rods under various air temperatures during forced air-cooling to elucidate the cooling mechanisms of steel rods. At a wind speed of 22 m/s, an increase in air temperature significantly reduces the convective heat transfer coefficient. Continuous airflow creates regions of low Reynolds numbers at the top of the rod and high Reynolds numbers along its sides, significantly enhancing the side convective heat transfer coefficient over the top. Empirical formulas for heat transfer coefficients at different rod positions were derived from experimental and simulation results and validated experimentally with a calculation error of less than 4 %.

引用次数: 0

Variations of stall mechanism induced by the changes of tip clearance size in a subsonic compressor rotor

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2025-01-04 DOI: 10.1016/j.ijheatfluidflow.2024.109742

Weiwei Cui , Yuqiang Liu , Long Zhang , Xinyuan Chen , Cuiping Wang

The clearance flow is closely linked to the tip flow characteristics and instability mechanisms of axial compressor rotor. Therefore, both experimental and numerical studies were conducted to investigate the influences of variations in clearance size on tip flow behaviors and instability mechanisms within a subsonic compressor rotor. The results show that the subsonic rotor has two distinct low-velocity zones due to tip leakage flow and suction surface separation at near-stall condition. As clearance size increases, suction surface separation decreases while tip leakage flow increases continuously. Within the small clearance size range (SCS range), the energy of leakage flow remains significantly lower than that of the surrounding mainstream at near-stall condition, leading it to be expelled from the tip channel by the mainstream. Thus, the substantial separation near suction surface induced by a pronounced positive angle of attack at leading edge, becomes the primary factor for tip flow instability in rotor at near-stall condition. Conversely, as clearance size further increased into large clearance size range (LCS range), suction surface separation nearly vanished near blade tip at near-stall condition, and the strong tip leakage vortex then dominates major disturbance in tip region. The low-velocity fluids generated by leakage vortex during unsteady fragmentation and dissipation obstructs the incoming mainstream in tip channel, contributing significantly to rotor stall. Consequently, it’s this progressively increasing leakage flow that leads to the stall margin of rotor showing an increasing and then decreasing trend in the clearance size monotonically increasing process, and fundamentally changes the stall inducing mechanism of the subsonic compressor rotor.

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