International Journal of Thermal Sciences最新文献

{"title":"The maximum ceiling temperature rise during moving train fire in subway tunnel: the influence of longitudinal ventilation","authors":"Shizhe Liu ,&nbsp;Chongguang Yue ,&nbsp;Weihao Kong ,&nbsp;Meng Yao ,&nbsp;Jingyun Xue ,&nbsp;Daqing Guang ,&nbsp;Xiaoling Wang ,&nbsp;Weiguang An","doi":"10.1016/j.ijthermalsci.2025.110025","DOIUrl":"10.1016/j.ijthermalsci.2025.110025","url":null,"abstract":"<div><div>Longitudinal ventilation systems are extensively found in subway tunneling projects due to their low cost and superior smoke extraction capabilities. However, when a moving train in a tunnel is on fire, its fire characteristics, especially the temperature distribution characteristics, will be complicated by the simultaneous effects of longitudinal ventilation and piston wind. A series of scaled-down experiments were carried out to examine the ceiling temperature rise characteristics in this case. The characteristics of the tunnel flow field under the combined influence of piston wind and longitudinal ventilation are revealed, and it is discovered that the ventilation wind direction and wind velocity are the main factors controlling the dimensionless maximum airflow velocity. Ventilation velocity, fire power, and vehicle speed impact the variation in ceiling temperature rise by altering flame geometry, smoke flow, and heat accumulation time. Under the downwind condition, the maximum ceiling temperature rise for some scenarios increases and then decreases with increasing ventilation velocity. Under the upwind condition, owing to the significant overlapping enhancement effect of the annular gap flow field, the ceiling temperature rise value decreases monotonically with the increase of ventilation wind velocity and vehicle speed, and it is always lower than the safe value. It is recommended that the daily longitudinal ventilation wind velocity is less than 5.4 m/s, and the wind velocity can be increased in the later phase of the fire to optimize the safety evacuation and rescue conditions. A prediction model of ceiling temperature rise based on the dimensionless theorem is established by introducing the convective heat transfer intensity factor and the barrier effect factor. The cross-experiment results show that its prediction accuracy is high. The research results are helpful for monitoring and controlling tunnel fires and providing guidance for evacuation and rescue.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"216 ","pages":"Article 110025"},"PeriodicalIF":4.9,"publicationDate":"2025-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144195650","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of ion mobility on electro-thermal convection: Linear stability analysis and numerical simulation","authors":"Shu-Yan Liu ,&nbsp;Yu-Xing Peng ,&nbsp;Yu Zhang ,&nbsp;Kang Luo ,&nbsp;Jian Wu ,&nbsp;Hong-Liang Yi","doi":"10.1016/j.ijthermalsci.2025.110033","DOIUrl":"10.1016/j.ijthermalsci.2025.110033","url":null,"abstract":"<div><div>In this work, a comprehensive investigation of Rayleigh-Bénard convection in an electric field is implemented based on linear stability analysis and numerical simulation. The effect of ion mobility represented by the ratio of negative and positive ion mobility (<em>K</em>_<em>r</em>) on the onset of flow instability and heat transfer enhancement is investigated. The stability analysis reveals that higher <em>K</em>_<em>r</em> values lead to a lower critical Rayleigh number (<em>Ra</em>_c), promoting earlier convection onset. A series of numerical simulations using the finite volume method with the EHD module is conducted across different <em>K</em>_<em>r</em> and <em>Ra</em> values, showing that a change in <em>K</em>_<em>r</em> not only initiates the flow without increasing the energy input, but also leads to the transition of the flow pattern and the structure of thermal plumes. Additionally, <em>K</em>_<em>r</em> significantly influences heat transfer efficiency: at <em>Ra</em> = 30000, increasing <em>K</em>_<em>r</em> from 1 to 10 leads to a 29 % increase in the Nusselt number (<em>Nu</em>). However, it is worth noting that the maximum velocity and heat transfer efficiency do not monotonically increase with <em>K</em>_<em>r</em>, suggesting that selecting an optimal working fluid is essential for practical applications. These findings highlight the critical role of ion mobility in driving convection and enhancing heat transfer in electro-thermal systems.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"216 ","pages":"Article 110033"},"PeriodicalIF":4.9,"publicationDate":"2025-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144194870","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of water temperature on ice melting characteristics under a bubbly flow","authors":"Zhongxin Liu,&nbsp;Xuan Zhang,&nbsp;Long Zhang,&nbsp;Runmiao Gao,&nbsp;Han Shi,&nbsp;Zekang Zhen,&nbsp;Mengjie Song","doi":"10.1016/j.ijthermalsci.2025.110034","DOIUrl":"10.1016/j.ijthermalsci.2025.110034","url":null,"abstract":"<div><div>Icing is widespread in the waters of cold regions, affecting the movement of ships, and effective de-icing methods are very necessary. The method of de-icing under a bubbly flow has the advantage of environmental protection and low energy consumption, and the effect of water temperature as a key factor deserves to be studied. An experimental set-up is designed to explore the ice melting process at different initial water temperatures ranging from 3–9 °C. Based on the experimental results, ice morphology, melting rate, heat transfer coefficient, and ice melting efficiency are analyzed. As the ice melts, a depression appears on the ice bottom surface and the depression profile gradually stabilizes with a change ratio of less than 10 %. The depression profiles at the same normalized time during under different water temperatures are almost identical, with a difference of less than 5 %. The melting rate decreases with increasing distance from the central axis in the beginning, while that in different locations gradually decreases to an almost equal constant due to the heat insulation of the remarkable bubble as the melting proceeds. The average melting rate in the height direction is linearly related to water temperature. The heat transfer coefficient is independent of water temperature. The heat transfer coefficient at each location of the ice bottom surface will gradually approach each other as melting proceeds. The findings are expected to be meaningful in the optimization of bubble de-icing systems.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"215 ","pages":"Article 110034"},"PeriodicalIF":4.9,"publicationDate":"2025-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144170171","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Flow boiling of water in a micro pin-fin heat sink at sub-atmospheric pressure","authors":"Wenjie Hu ,&nbsp;Yunlong Qiu ,&nbsp;Chuan Tong ,&nbsp;Weifang Chen ,&nbsp;Changju Wu","doi":"10.1016/j.ijthermalsci.2025.110032","DOIUrl":"10.1016/j.ijthermalsci.2025.110032","url":null,"abstract":"<div><div>Flow boiling of deionized water in a silicon-based micro pin-fin heat sink with sub-atmospheric outlet pressure are experimentally studied in this work. Experiments are conducted with a constant mass flow rate of 4 ml/min, a controlled outlet pressure ranging from 20 to 60 kPa, and effective heat flux up to 580 kW/m². The inlet temperature is controlled at 20 K below the saturation temperature corresponding to the outlet pressure. The effects of sub-atmospheric outlet pressure on the flow boiling characteristics are investigated and discussed. It is found that lower sub-atmospheric outlet pressure leads to higher pressure drop due to the significant reduction in vapor phase density. When the outlet thermodynamic quality is about 0.27, the pressure drop is about 14.87 kPa at <em>P</em>_<em>out</em> = 20 kPa, while it is only 8.50 kPa at <em>P</em>_<em>out</em> = 60 kPa. In the meantime, the average heat transfer coefficient at <em>P</em>_<em>out</em> = 60 kPa is approximately twice that at <em>P</em>_<em>out</em> = 20 kPa. Besides, a decreasing tendency of wall temperature along the flow direction is observed, which is caused by the decreasing tendency of saturation temperature along the micro pin-fin heat sink. Under lower outlet pressure condition, the heat transfer performance degradation occurs earlier. The flow boiling visualization results show that the rapid expansion behavior of upstream bubbles and the evaporation of the thin liquid film in the downstream area are the main flow boiling behaviors in micro pin-fin heat sink under outlet sub-atmospheric pressure. The expansion of upstream bubbles is an important driving force for the replenishment of downstream liquid.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"215 ","pages":"Article 110032"},"PeriodicalIF":4.9,"publicationDate":"2025-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144170170","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Research on the characteristics of turbine vane film cooling at low Reynolds numbers","authors":"Haichao Wang ,&nbsp;Yumeng Li ,&nbsp;Hongyi Fang ,&nbsp;Yuting Liao ,&nbsp;Song Liu","doi":"10.1016/j.ijthermalsci.2025.110015","DOIUrl":"10.1016/j.ijthermalsci.2025.110015","url":null,"abstract":"<div><div>Unmanned aerial vehicles and high-bypass-ratio engines typically operate at low Reynolds number(Re)conditions. It results in distinct film cooling characteristics for turbine vanes. This numerical study investigates the film cooling performance of four rows of film holes (S1 and S2 on the suction side, P1 and P2 on the pressure side) under low and high Re numbers (Re = 3.0 × 10⁴, 3.5 × 10⁵). The research focuses on the effects of blowing ratio (M = 0.2, 0.5, 1.0 for suction-side holes; M = 0.5, 1.0, 1.5 for pressure-side holes), mainstream turbulence intensity (Tu = 2.3 %, 15.7 %), and mainstream inlet Mach number (<em>Ma</em> = 0.0083, 0.15) on film cooling effectiveness and heat transfer coefficient ratios. The findings illustrate that, for suction-side film holes, when M = 0.2 and M = 0.5, the film cooling effectiveness at low Re number is significantly worse than at high Re number, but the difference decreases at larger blowing ratios (M = 1.0). Increasing mainstream Tu reduces the film cooling effectiveness at low Re number and increases the heat transfer coefficient ratio, whereas the opposite trend is observed at high Re number. At low Re number, the high <em>Ma</em> case increases the η values by 28–45 %, while this enhancement reverses at M = 1.0 at high Re number. For pressure-side film holes, the film cooling effectiveness at low Re number is poorer at small blowing ratios (M = 0.5), but superior at M = 1.0 and M = 1.5 compared to high Re number. An increase in Tu values leads to a decrease in the heat transfer coefficient ratio at both low and high Re numbers, although the response to turbulence intensity changes is less pronounced at low Re number. At both Re conditions, high <em>Ma</em> initially yields lower η than low <em>Ma</em> but eventually outperforms it. Overall, film cooling performance at low Re number is poorer and more sensitive to changes in turbulence intensity,yet demonstrates superior stability in film coverage across a wider range of applicable blowing ratios at a high <em>Ma</em> case.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"215 ","pages":"Article 110015"},"PeriodicalIF":4.9,"publicationDate":"2025-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144170232","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Condensation and boiling in the entrance region of horizontal and inclined smooth tubes","authors":"Vasyl Ruzaikin,&nbsp;Ivan Lukashov,&nbsp;Andrii Breus","doi":"10.1016/j.ijthermalsci.2025.110031","DOIUrl":"10.1016/j.ijthermalsci.2025.110031","url":null,"abstract":"<div><div>This manuscript presents the results of an experimental investigation into ammonia condensation and boiling in the entrance region of horizontal and inclined smooth tubes with an inner diameter (ID) of 11 mm. The study was conducted under saturation temperatures ranging from 55 °C to 65 °C, mass velocities between 60 and 120 kg m⁻² s⁻¹, and vapour qualities from 0.1 to 0.7. Two-phase flow pattern transitions were also examined using a transparent tube of ID 7.5 mm, equipped with ID 2 mm throttling orifice. Perturbation lengths were quantitatively evaluated for saturation temperatures between 35 °C and 55 °C, mass velocities of 80–160 kg m⁻² s⁻¹, and vapour qualities from 0.1 to 0.7. The results indicate that perturbation length is primarily determined by the initial two-phase flow pattern. The perturbation length remains unaffected by variations in saturation temperature, mass velocity, or vapour quality within the given flow pattern. In horizontal flow, the perturbation length does not exceed 23 hydraulic diameters (D) for stratified-wavy flows, and 15D for annular and annular-wavy flows. For vertical upflow, plug and churn flow regimes exhibit perturbation lengths of up to 24D, whereas annular and annular-wavy patterns remain stable beyond 20D. An L-junction does not significantly affect the flow pattern beyond a distance of 12D. In the entrance region, average condensation heat transfer coefficients (HTCs) are generally lower than those in the fully developed region at low mass velocities (&lt;120 kg m⁻² s⁻¹) and vapour qualities (&lt;0.7). For boiling, performance in the entrance region is comparable to that in the fully developed region at low mass velocities. However, at higher mass velocities (120 kg m⁻² s⁻¹), a slight reduction in boiling HTCs—approximately 10 %—was observed, which can be explained by the suppression of the nucleate boiling mechanism.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"215 ","pages":"Article 110031"},"PeriodicalIF":4.9,"publicationDate":"2025-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144169773","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of sub-atmospheric pressure on combustion and pyrolysis behavior of flame-retardant polyethylene","authors":"Hongsheng Xu,&nbsp;Heng Yu,&nbsp;Fukai Chu,&nbsp;Zhandong Wang,&nbsp;Weizhao Hu,&nbsp;Lei Song,&nbsp;Yuan Hu","doi":"10.1016/j.ijthermalsci.2025.110028","DOIUrl":"10.1016/j.ijthermalsci.2025.110028","url":null,"abstract":"<div><div>With the rapid increase in the number of cruise aircraft and high-altitude greenhouses, internal electrical cables and polyethylene films are often exposed to low-pressure environments. However, current flame-retardant designs for polyethylene do not sufficiently account for the effects of low-pressure conditions, under which the combustion behavior and flame-retardant effectiveness may change significantly, leading to a considerable risk of functional failure. This study systematically investigates the combustion and pyrolysis mechanisms of low-density polyethylene (LDPE) with varying intumescent flame retardant (FR) contents in a pressure range of 55 kPa–101 kPa. The findings reveal that FR significantly enhances char formation under sub-atmospheric pressures, reducing ignition time compared to pure LDPE. Decreased pressure leads to a marked increase in heat release rate (HRR) and a reduction in CO emissions, as measured by a cone calorimeter in a low-pressure chamber. Synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS) further reveals that low-pressure promotes the generation of more alkene and a higher proportion of long-chain pyrolysis products. Intumescent FR effectively reduce HRR, decrease CO production, and minimize the formation of saturated hydrocarbons under low-pressure conditions, while enhancing the char formation. Among these, a 35 wt% FR shows the best performance. However, ammonium polyphosphate, a common flame retardant, tends to make the material more susceptible to ignition. This work enhances the understanding of fire dynamics in low-pressure environments and provides a scientific foundation for designing safer, flame-retardant polyethylene materials tailored for sub-atmospheric applications.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"215 ","pages":"Article 110028"},"PeriodicalIF":4.9,"publicationDate":"2025-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144170169","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hydrothermal performance of turbulent flow in tubes with spherical dimples","authors":"Kazem Mashayekh ,&nbsp;Amin Etminan ,&nbsp;Kevin Pope ,&nbsp;Yuri S. Muzychka","doi":"10.1016/j.ijthermalsci.2025.110027","DOIUrl":"10.1016/j.ijthermalsci.2025.110027","url":null,"abstract":"<div><div>Engineers increasingly utilize dimpled tubes in thermal systems to enhance performance, with spherical dimples demonstrating the most significant impact. Simple and accurate correlations are essential for efficiently assessing the performance of newly designed or improved equipment. Extensive research has been conducted on spherical dimples; however, no study has comprehensively examined the combined effects of geometric parameters such as dimple diameter, dimple pitch, and dimple stars. This study uses numerical simulations to investigate the hydraulic and thermal performance of spherical dimpled tubes with varying geometric parameters, including dimple pitch, diameter, and the stars. New correlations for the Nusselt number (<em>Nu</em>), friction factor (fr), and performance evaluation criteria (PEC) are developed as functions of these parameters and the Reynolds number. The dimpled tube is analyzed under a constant heat flux of 10 kW/m². The study finds that increasing dimple pitch decreases <em>Nu</em>, fr, and PEC, with deviations ranging from 3 % to 40.5 %, 18.8 %–109.9 %, and −4.2 % to 12.6 %, respectively. Increasing dimple diameter and the number of stars increases <em>Nu</em> and fr, but the effect on PEC varies. Specifically, as dimple diameter increases, <em>Nu</em> changes by 13.1 %–89.3 %, fr rises by 51.9 %–509 %, and PEC varies between −20.2 % and 3.1 %. When the number of dimple stars increases, <em>Nu</em> changes by 21.3 %–45 %, fr increases from 58.7 % to 277.9 %, and PEC improves by 5.3 %–20 %. The results also show that, based on the dimple parameters and Reynolds number, the PEC number can reach a maximum of 1.4.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"215 ","pages":"Article 110027"},"PeriodicalIF":4.9,"publicationDate":"2025-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144169772","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Performance evaluation of a double-pipe heat exchanger using plain and rectangular-cut multi-channel twisted tapes","authors":"Jitendra Kumar,&nbsp;Mohammad Saud Afzal","doi":"10.1016/j.ijthermalsci.2025.109994","DOIUrl":"10.1016/j.ijthermalsci.2025.109994","url":null,"abstract":"<div><div>This study numerically investigates the hydrothermal performance of multi-channel twisted tapes (MCTTs), including plain and rectangular-cut trilobe, quadlobe, and pentalobe designs, inside a double pipe heat exchanger (DPHE). The objective is to enhance turbulent heat transfer while maintaining a feasible pressure drop. The finite volume approach is used to solve the steady-state Navier–Stokes and energy equations, that serve as the basis of the mathematical model. The realizable <span><math><mrow><mi>k</mi><mo>−</mo><mi>ϵ</mi></mrow></math></span> and SST <span><math><mrow><mi>k</mi><mo>−</mo><mi>ω</mi></mrow></math></span> models were employed for turbulence modeling. Assumptions include incompressible and steady-state water flow while neglecting thermal radiation, gravity, and chemical reactions. The study evaluates the heat exchangers by comparing the Nusselt number (Nu), friction factor (f), and thermal performance factor (TPF) against conventional twisted tapes and plain DPHE. The simulations consider a twist ratio of 3.0, a 39 mm pitch, constant cut depth of 4.4 mm, cut widths of 4.8 mm and 4.4 mm, and an edge length between two cuts measuring 6.5 mm and 13 mm. The study employed water as the working fluid and was performed in the turbulent flow regions, characterized by a range of 6000 to 20000. Water is assumed to be an incompressible, steady-state fluid, with constant density and flow rate, while neglecting thermal radiation, and gravity. The hot water exhibits a counterflow pattern within the inner side, with a mass flow rate that can vary whereas the cold water flows through the annular side at a consistent mass flow rate. In order to choose the appropriate turbulence model, the simulation results for a plain DPHE and a heat HX with conventional twisted tape (TT) were compared with available empirical correlations. Afterwards, the multi-channel twisted tapes (MCTTs) were simulated using the more precise model. Results show that MCTTs induce multiple swirling flows, enhancing fluid mixing and heat transmission. Among the tested designs, rectangular-cut trilobe twisted tape (RC-MCTT) at w<span><math><mo>=</mo></math></span>d <span><math><mo>=</mo></math></span> 4.4 mm achieved the highest Nu, with a 105%–170% increase over P-DPHE and 62%–94% over DPHE with typical TT. Similarly, the plain trilobe MCTT provided a 73%–150% improvement over P-DPHE and 37%–80% over DPHE with typical TT. The maximum TPF of 1.31 was observed for RC-MCTT at <span><math><mrow><mi>Re</mi><mo>=</mo><mn>6000</mn></mrow></math></span>. These findings confirm that rectangular-cut MCTTs significantly enhance heat transfer while maintaining a reasonable trade-off with pressure drop, making them a promising choice for industrial heat exchanger applications.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"215 ","pages":"Article 109994"},"PeriodicalIF":4.9,"publicationDate":"2025-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144170168","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study on the mechanism of enhanced heat transfer through punched vortex generators in the frame of convective transport equation of heat flux","authors":"Jiangbo Wang,&nbsp;Liangcai Zeng,&nbsp;Ting Fu","doi":"10.1016/j.ijthermalsci.2025.110024","DOIUrl":"10.1016/j.ijthermalsci.2025.110024","url":null,"abstract":"<div><div>In this work, the impact of the perforation technique of vortex generators on both local and overall heat transfer enhancement under laminar flow was examined in the frame of convective transport equation of heat flux. The research findings revealed that the intensity of heat flux transmission along the x-y-z directions was altered by the perforation method, with the z-direction experiencing the most significant influence. In the intermediate region between the two vortex generators and the near wall region, perforation did not alter the heat transfer behavior. At the position across the hole, the heat transfer rate was enhanced first and then inhibited since the fluid velocity changed. However, the increment in fluid velocity at the hole does not always facilitate heat flux transmission. Near the bottom surface, the jet flow achieved heat transfer enhancement by increasing fluid velocity. Conversely, near the top edge of the perforation, the jet flow enhanced heat transfer by augmenting the velocity gradient. Moreover, the jet flow generated by the perforations reduced the contribution of the longitudinal vortices' velocity to heat flux transmission, resulting in a decline in overall heat transfer.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"215 ","pages":"Article 110024"},"PeriodicalIF":4.9,"publicationDate":"2025-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144139110","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}