Pub Date : 2025-11-17DOI: 10.1016/j.ijheatfluidflow.2025.110141
Zengen Li , Haochun Zhang , Dong Zhang , Xi Luo , Yan Xia
The exponential increase of space debris will have serious consequences for the flight safety of nuclear-powered spacecraft. This research establishes a 2D calculation program 2D-INCHPR for in-direct contact heat pipe radiators. Based on the whale optimization algorithm, a multi objective optimization analysis of the radiator with multi parameter coupling is carried out. A space debris impact resistant radiator is devised without reducing heat transfer efficiency, providing a theoretical basis for structural optimization of space nuclear power system. The method of calculating alkali metal heat pipes transient and steady-state multi-physics coupling characteristics of in space nuclear power systems based on gas dynamics theory is extended to a 2D model of entire heat pipe domain. A 2D program 2D-NCAMHP is established for multi- physics coupling calculation of space alkali metal heat pipes. The optimized structural parameters of the radiation heat sink with low probability of space debris impact after optimization design are Lf = 0.0537 m, Tinl = 852.2493 K, lhpc = 1.9298 m, qm = 7.4340 kg·s-1. The thermal and hydraulic characteristics of alkali metal heat pipes were obtained through simulation analysis, which provides a theoretical basis for the optimization design of radiator structures in nuclear powered spacecraft.
空间碎片呈指数级增长，将对核动力航天器的飞行安全造成严重后果。本文建立了非直接接触热管散热器的二维计算程序2D- inchpr。基于鲸鱼优化算法，对多参数耦合的散热器进行了多目标优化分析。设计了一种不降低换热效率的空间碎片抗冲击散热器，为空间核动力系统结构优化提供了理论依据。将基于气体动力学理论的空间核动力系统碱金属热管瞬态和稳态多物理场耦合特性计算方法推广到整个热管域的二维模型。建立了用于空间碱金属热管多物理场耦合计算的二维程序2D- ncamhp。优化设计后低空间碎片撞击概率辐射散热器的优化结构参数为：Lf = 0.0537 m, Tinl = 852.2493 K, lhpc = 1.9298 m, qm = 7.4340 kg·s-1。通过仿真分析，获得了碱金属热管的热工特性，为核动力航天器散热器结构的优化设计提供了理论依据。
{"title":"Research on the optimal design of anti-collision heat pipe radiator for nuclear powered spacecraft","authors":"Zengen Li , Haochun Zhang , Dong Zhang , Xi Luo , Yan Xia","doi":"10.1016/j.ijheatfluidflow.2025.110141","DOIUrl":"10.1016/j.ijheatfluidflow.2025.110141","url":null,"abstract":"<div><div>The exponential increase of space debris will have serious consequences for the flight safety of nuclear-powered spacecraft. This research establishes a 2D calculation program 2D-INCHPR for in-direct contact heat pipe radiators. Based on the whale optimization algorithm, a multi objective optimization analysis of the radiator with multi parameter coupling is carried out. A space debris impact resistant radiator is devised without reducing heat transfer efficiency, providing a theoretical basis for structural optimization of space nuclear power system. The method of calculating alkali metal heat pipes transient and steady-state multi-physics coupling characteristics of in space nuclear power systems based on gas dynamics theory is extended to a 2D model of entire heat pipe domain. A 2D program 2D-NCAMHP is established for multi- physics coupling calculation of space alkali metal heat pipes. The optimized structural parameters of the radiation heat sink with low probability of space debris impact after optimization design are Lf = 0.0537 m, Tinl = 852.2493 K, lhpc = 1.9298 m, qm = 7.4340 kg·s-1. The thermal and hydraulic characteristics of alkali metal heat pipes were obtained through simulation analysis, which provides a theoretical basis for the optimization design of radiator structures in nuclear powered spacecraft.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"117 ","pages":"Article 110141"},"PeriodicalIF":2.6,"publicationDate":"2025-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145576073","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}
Pub Date : 2025-11-17DOI: 10.1016/j.ijheatfluidflow.2025.110147
Abdelrahman Ali, Ahmed A. Abdel-Rehim
Since energy demand increases as time passes, the utilization of photovoltaics (PV) becomes necessary and prevalent. However, one major issue of PVs is their poor energy conversion efficiency. As the temperature of the PV cell increases, its efficiency drops. The integration of phase change materials (PCMs) with PV systems helps in absorbing heat and improving system performance. In this study, a three-dimensional numerical model was developed to investigate the effect of the pyramidal enclosure geometry design for the PCM on the thermal and electrical performance of the PV. The study considers three different dimensions of the enclosure geometry, the effect of wind speed and the variation of incident solar irradiance according to real data in Cairo. RT-42 paraffin wax was used in the enclosures and tested under three different conditions: insulated PV back surface; cooled back surface with wind speed of 3 m/s; and transient cooling conditions. Results showed that the configuration with 24 enclosures reduced the temperature 17.92 % with the aid of PCM. For energy storage, the system with 6 enclosures achieved maximum thermal energy storage of 206.3 kJ/kg. The 15-enclosure system was optimized in which the total amount of PCM was reduced by 23.55 % while maintaining the same performance of the PV. The results of the current study indicate that the proposed design is promising for future work.
{"title":"Numerical investigation of pyramidal PCM enclosure design on photovoltaic thermal performance","authors":"Abdelrahman Ali, Ahmed A. Abdel-Rehim","doi":"10.1016/j.ijheatfluidflow.2025.110147","DOIUrl":"10.1016/j.ijheatfluidflow.2025.110147","url":null,"abstract":"<div><div>Since energy demand increases as time passes, the utilization of photovoltaics (PV) becomes necessary and prevalent. However, one major issue of PVs is their poor energy conversion efficiency. As the temperature of the PV cell increases, its efficiency drops. The integration of phase change materials (PCMs) with PV systems helps in absorbing heat and improving system performance. In this study, a three-dimensional numerical model was developed to investigate the effect of the pyramidal enclosure geometry design for the PCM on the thermal and electrical performance of the PV. The study considers three different dimensions of the enclosure geometry, the effect of wind speed and the variation of incident solar irradiance according to real data in Cairo. RT-42 paraffin wax was used in the enclosures and tested under three different conditions: insulated PV back surface; cooled back surface with wind speed of 3 m/s; and transient cooling conditions. Results showed that the configuration with 24 enclosures reduced the temperature 17.92 % with the aid of PCM. For energy storage, the system with 6 enclosures achieved maximum thermal energy storage of 206.3 kJ/kg. The 15-enclosure system was optimized in which the total amount of PCM was reduced by 23.55 % while maintaining the same performance of the PV. The results of the current study indicate that the proposed design is promising for future work.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"117 ","pages":"Article 110147"},"PeriodicalIF":2.6,"publicationDate":"2025-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145576072","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}
Pub Date : 2025-11-15DOI: 10.1016/j.ijheatfluidflow.2025.110146
Riguang Chi , Jiawei Wang , Haoran Ning , Yunyang Ye , Zhenkun Lu , Haishao Chen , Rui Yang
Thermal management remains a critical challenge for lithium-ion battery (LIB) packs in electric vehicles, particularly under diverse operating conditions. Addressing limitations in conventional pulsating heat pipe (PHP) designs, this study introduces a novel open-loop, series-connected L-shaped pulsating heat pipe (OL-LPHP) structure tailored to enhance thermal efficiency and adaptability. Comprehensive experiments were conducted using deionized water, methanol, and anhydrous ethanol as working fluids, examining the effects of heating power (30–90 W), cooling water temperature (20–30℃), filling ratio (10–20 %), and inclination angle (0–15°). Results identify methanol as the optimal working fluid, minimizing thermal resistance and ensuring stable operation. The system demonstrated a non-linear thermal resistance response to filling ratio and cooling temperature, with an optimal fill ratio of 15 % enabling efficient oscillatory flow. Under optimized conditions, the OL-LPHP maintained the battery pack temperature below 55.7 °C even at a maximum heating load of 90 W, well within the critical threshold of 60 °C. Furthermore, the design exhibited consistent performance across varying inclination angles, underscoring its robustness for real-world EV applications. This study bridges a significant research gap by integrating operational and environmental factors into PHP design, offering a high-efficiency, flexible solution for next-generation EV battery thermal management systems.
{"title":"Series-Connected Open-Loop L-shaped pulsating heat pipes for Lithium-Ion battery thermal Management: Experimental optimization of heat transfer performance in EV-Applicable scenarios","authors":"Riguang Chi , Jiawei Wang , Haoran Ning , Yunyang Ye , Zhenkun Lu , Haishao Chen , Rui Yang","doi":"10.1016/j.ijheatfluidflow.2025.110146","DOIUrl":"10.1016/j.ijheatfluidflow.2025.110146","url":null,"abstract":"<div><div>Thermal management remains a critical challenge for lithium-ion battery (LIB) packs in electric vehicles, particularly under diverse operating conditions. Addressing limitations in conventional pulsating heat pipe (PHP) designs, this study introduces a novel open-loop, series-connected L-shaped pulsating heat pipe (OL-LPHP) structure tailored to enhance thermal efficiency and adaptability. Comprehensive experiments were conducted using deionized water, methanol, and anhydrous ethanol as working fluids, examining the effects of heating power (30–90 W), cooling water temperature (20–30℃), filling ratio (10–20 %), and inclination angle (0–15°). Results identify methanol as the optimal working fluid, minimizing thermal resistance and ensuring stable operation. The system demonstrated a non-linear thermal resistance response to filling ratio and cooling temperature, with an optimal fill ratio of 15 % enabling efficient oscillatory flow. Under optimized conditions, the OL-LPHP maintained the battery pack temperature below 55.7 °C even at a maximum heating load of 90 W, well within the critical threshold of 60 °C. Furthermore, the design exhibited consistent performance across varying inclination angles, underscoring its robustness for real-world EV applications. This study bridges a significant research gap by integrating operational and environmental factors into PHP design, offering a high-efficiency, flexible solution for next-generation EV battery thermal management systems.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"117 ","pages":"Article 110146"},"PeriodicalIF":2.6,"publicationDate":"2025-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145525314","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}
Pub Date : 2025-11-15DOI: 10.1016/j.ijheatfluidflow.2025.110139
Nepal Chandra Roy, Susmita Halder Rumpa, Al Amin
Natural convective fluid flow and heat transfer of a Fe3O4-Al2O3-Cu/water ternary hybrid nanofluid within a trapezoidal enclosure with wavy sidewalls are analyzed here. A magnetic field is applied vertically, and multiple cold obstacles are added to modify natural convection phenomenon. The governing equations and boundary conditions are formulated according to the related assumptions. The mathematical problem is solved numerically using the finite difference method implemented in FORTRAN code. The primary objective is to investigate the effect of volume fraction with various shapes of Fe3O4 nanoparticles. The other parameters are the Rayleigh number (Ra), the Hartmann number (Ha) and the inclined wall angle of the trapezium. As per the results, the average Nusselt number increases with a higher volume fraction of spherical-shaped Fe3O4 nanoparticles. For higher Hartmann numbers, the flow intensity and average Nusselt number are found to decrease. On the other hand, the average Nusselt number increases with larger Rayleigh numbers and inclined wall angles of the trapezium. With the trapezoidal enclosure and wavy sidewalls various shapes in engineering applications can be designed, such as pipeline designs, convergence-divergence nozzles, wind tunnels, or various architectural constrictions.
{"title":"Natural convective ternary nanofluid flow in a trapezoidal wavy enclosure with multiple cold obstacles","authors":"Nepal Chandra Roy, Susmita Halder Rumpa, Al Amin","doi":"10.1016/j.ijheatfluidflow.2025.110139","DOIUrl":"10.1016/j.ijheatfluidflow.2025.110139","url":null,"abstract":"<div><div>Natural convective fluid flow and heat transfer of a <em>Fe</em><sub>3</sub><em>O</em><sub>4</sub>-<em>Al</em><sub>2</sub><em>O</em><sub>3</sub>-<em>Cu</em>/water ternary hybrid nanofluid within a trapezoidal enclosure with wavy sidewalls are analyzed here. A magnetic field is applied vertically, and multiple cold obstacles are added to modify natural convection phenomenon. The governing equations and boundary conditions are formulated according to the related assumptions. The mathematical problem is solved numerically using the finite difference method implemented in FORTRAN code. The primary objective is to investigate the effect of volume fraction with various shapes of <em>Fe</em><sub>3</sub><em>O</em><sub>4</sub> nanoparticles. The other parameters are the Rayleigh number (<em>Ra</em>), the Hartmann number (<em>Ha</em>) and the inclined wall angle of the trapezium. As per the results, the average Nusselt number increases with a higher volume fraction of spherical-shaped <em>Fe</em><sub>3</sub><em>O</em><sub>4</sub> nanoparticles. For higher Hartmann numbers, the flow intensity and average Nusselt number are found to decrease. On the other hand, the average Nusselt number increases with larger Rayleigh numbers and inclined wall angles of the trapezium. With the trapezoidal enclosure and wavy sidewalls various shapes in engineering applications can be designed, such as pipeline designs, convergence-divergence nozzles, wind tunnels, or various architectural constrictions.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"117 ","pages":"Article 110139"},"PeriodicalIF":2.6,"publicationDate":"2025-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145525313","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}
Pub Date : 2025-11-13DOI: 10.1016/j.ijheatfluidflow.2025.110142
Yue Yu , Chuncai Zhou , Feng Wang , Zhiguo Li , Xin Li , Guijian Liu
In the context of carbon peaking and carbon neutrality, achieving low-carbon emissions from coke ovens is of paramount importance. This study numerically investigated the combustion process of coke oven gas (COG) and blast furnace gas (BFG) within the heat flue of a coke oven, focusing on the effects of varying mixing ratios (M) of COG to BFG and different inlet angles of gas and air (α and β). Utilizing computational fluid dynamics (CFD), the velocity distribution, temperature field, and concentrations of CO and CO2 were predicted. The results show that an increase in the mixing ratio enhances flame height due to the entrainment effect, while a reduction in carbon content in the gas contributes to a decrease in overall carbon emissions. Specifically, when the mixing ratio M reaches 13 %, the combined molar concentrations of CO and CO2 at the outlet decrease to 2.632 × 10−1. Furthermore, it is observed that a delayed interaction time of gas and air at angle β, as opposed to an earlier interaction at angle α, promotes better vertical temperature uniformity within the heat flue. Nonetheless, variations in the inlet angle are found to have no significant impact on the total carbon concentration at the outlet.
{"title":"Comprehensive analysis of combustion characteristics and carbon oxides emission in mixing gas fired coke oven through CFD modeling","authors":"Yue Yu , Chuncai Zhou , Feng Wang , Zhiguo Li , Xin Li , Guijian Liu","doi":"10.1016/j.ijheatfluidflow.2025.110142","DOIUrl":"10.1016/j.ijheatfluidflow.2025.110142","url":null,"abstract":"<div><div>In the context of carbon peaking and carbon neutrality, achieving low-carbon emissions from coke ovens is of paramount importance. This study numerically investigated the combustion process of coke oven gas (COG) and blast furnace gas (BFG) within the heat flue of a coke oven, focusing on the effects of varying mixing ratios (<em>M</em>) of COG to BFG and different inlet angles of gas and air (α and β). Utilizing computational fluid dynamics (CFD), the velocity distribution, temperature field, and concentrations of CO and CO<sub>2</sub> were predicted. The results show that an increase in the mixing ratio enhances flame height due to the entrainment effect, while a reduction in carbon content in the gas contributes to a decrease in overall carbon emissions. Specifically, when the mixing ratio <em>M</em> reaches 13 %, the combined molar concentrations of CO and CO<sub>2</sub> at the outlet decrease to 2.632 × 10<sup>−1</sup>. Furthermore, it is observed that a delayed interaction time of gas and air at angle β, as opposed to an earlier interaction at angle α, promotes better vertical temperature uniformity within the heat flue. Nonetheless, variations in the inlet angle are found to have no significant impact on the total carbon concentration at the outlet.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"117 ","pages":"Article 110142"},"PeriodicalIF":2.6,"publicationDate":"2025-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145525289","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}
Pub Date : 2025-11-12DOI: 10.1016/j.ijheatfluidflow.2025.110121
Weiyan Liu , Jiacheng Lyu , Keqi Hu , Zhixin Zhu , Gaofeng Wang
To address computational challenges from densely clustered small cooling holes in aero-engine combustor liner simulations, this study uses equivalent jet modelling (point source and volumetric source approaches) and conducts numerical investigations on a multi-perforated flat plate and a laboratory-scale combustor, evaluating effects of source term models on flow, thermal distribution, and wall cooling. For the flat plate, the point source approach shows excessive jet orthogonality, underpredicting wall cooling coverage compared with the discrete holes configuration; the volumetric source maintains temperature distribution accuracy but predicts faster streamwise cooling coverage development. In combustor simulations, source term methods reduce grid counts by approximately 60 %. Point source and volumetric source reduce computational time by 50 % and 64 %, respectively, while ensuring accurate central cross-section velocity/temperature and outlet temperature/pressure predictions. Both methods achieve ±10 % streamwise wall temperature error. These findings confirm equivalent jet modelling balances computational efficiency and accuracy, with great potential for full-scale combustor simulations in engineering.
{"title":"Numerical investigation of effusion cooling characteristics in combustor liners: Point and volumetric source term modelling approaches","authors":"Weiyan Liu , Jiacheng Lyu , Keqi Hu , Zhixin Zhu , Gaofeng Wang","doi":"10.1016/j.ijheatfluidflow.2025.110121","DOIUrl":"10.1016/j.ijheatfluidflow.2025.110121","url":null,"abstract":"<div><div>To address computational challenges from densely clustered small cooling holes in aero-engine combustor liner simulations, this study uses equivalent jet modelling (point source and volumetric source approaches) and conducts numerical investigations on a multi-perforated flat plate and a laboratory-scale combustor, evaluating effects of source term models on flow, thermal distribution, and wall cooling. For the flat plate, the point source approach shows excessive jet orthogonality, underpredicting wall cooling coverage compared with the discrete holes configuration; the volumetric source maintains temperature distribution accuracy but predicts faster streamwise cooling coverage development. In combustor simulations, source term methods reduce grid counts by approximately 60 %. Point source and volumetric source reduce computational time by 50 % and 64 %, respectively, while ensuring accurate central cross-section velocity/temperature and outlet temperature/pressure predictions. Both methods achieve ±10 % streamwise wall temperature error. These findings confirm equivalent jet modelling balances computational efficiency and accuracy, with great potential for full-scale combustor simulations in engineering.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"117 ","pages":"Article 110121"},"PeriodicalIF":2.6,"publicationDate":"2025-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145525315","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}
Pub Date : 2025-11-12DOI: 10.1016/j.ijheatfluidflow.2025.110140
Lin Chen , Jiaxin Liu , Mengshuai Chen , Xuefen Yan , Atsuki Komiya , Rachid Bennacer
Supercritical carbon dioxide (sCO2) possesses unique physical properties in the critical region—characterized by high density, low viscosity, and strong solvation capacity—exhibiting critical flow and heat transfer behaviors in porous media that are crucial for applications such as carbon sequestration, soil remediation, and oil/gas recovery. This study systematically investigates the phase transition behavior, flow characteristics, and heat transfer mechanisms of CO2 during trans-critical processes in porous media through an integrated approach employing a visualization experimental platform, optical imaging techniques, and numerical simulations. Key findings reveal that during the trans-critical process: (1) an increase in inlet temperature suppresses the enhancing effect of back pressure on flow pressure drop, while elevated back pressure amplifies the impact of volumetric flow rate on flow pressure drop; (2) turbulent phenomena persist for 47.26 % of the entire trans-critical duration during the transition from liquid CO2 to supercritical state, accompanied by significant density gradient fluctuations at phase interfaces; (3) transient simulations of the trans-critical process demonstrate three heat transfer mechanisms: deteriorated heat transfer by phase chaos, enhanced heat transfer in transitional state, and drastically enhanced heat transfer in supercritical state. Furthermore, alterations in boundary conditions induce substantial numerical discrepancies in local heat transfer coefficients during periods of drastic fluctuation.
{"title":"Experimental and numerical analysis of high-pressure CO2 injection flow inside a homogeneous porous microchip model","authors":"Lin Chen , Jiaxin Liu , Mengshuai Chen , Xuefen Yan , Atsuki Komiya , Rachid Bennacer","doi":"10.1016/j.ijheatfluidflow.2025.110140","DOIUrl":"10.1016/j.ijheatfluidflow.2025.110140","url":null,"abstract":"<div><div>Supercritical carbon dioxide (sCO<sub>2</sub>) possesses unique physical properties in the critical region—characterized by high density, low viscosity, and strong solvation capacity—exhibiting critical flow and heat transfer behaviors in porous media that are crucial for applications such as carbon sequestration, soil remediation, and oil/gas recovery. This study systematically investigates the phase transition behavior, flow characteristics, and heat transfer mechanisms of CO<sub>2</sub> during <em>trans</em>-critical processes in porous media through an integrated approach employing a visualization experimental platform, optical imaging techniques, and numerical simulations. Key findings reveal that during the <em>trans</em>-critical process: (1) an increase in inlet temperature suppresses the enhancing effect of back pressure on flow pressure drop, while elevated back pressure amplifies the impact of volumetric flow rate on flow pressure drop; (2) turbulent phenomena persist for 47.26 % of the entire <em>trans</em>-critical duration during the transition from liquid CO<sub>2</sub> to supercritical state, accompanied by significant density gradient fluctuations at phase interfaces; (3) transient simulations of the <em>trans</em>-critical process demonstrate three heat transfer mechanisms: deteriorated heat transfer by phase chaos, enhanced heat transfer in transitional state, and drastically enhanced heat transfer in supercritical state. Furthermore, alterations in boundary conditions induce substantial numerical discrepancies in local heat transfer coefficients during periods of drastic fluctuation.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"117 ","pages":"Article 110140"},"PeriodicalIF":2.6,"publicationDate":"2025-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145525290","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}
Pub Date : 2025-11-10DOI: 10.1016/j.ijheatfluidflow.2025.110138
Yuan Wang, Jingjun Zhong , Wanyang Wu
As a bio-inspired technology, tip winglet has been widely employed in compressors to enhance aerodynamic performance and improve tip flow structures. This study investigates the transonic compressor stage and refines the design criteria for tip winglet by considering the effects of nonlinear thickness distribution on aerodynamic performance. A parametric modeling approach is utilized to design tip winglets with thickness variations along both the chordwise and spanwise directions. By comparing the flow fields of various tip winglet configurations with different thickness distributions against the baseline compressor stage, this study reveals both the similarities and differences in flow stabilization mechanisms induced by each design. The results indicate that positioning the maximum thickness of the tip winglet closer to the leading edge along the chordwise direction effectively suppresses the boundary layer separation near the suction side. In contrast, positioning the maximum thickness of the tip winglet closer to the trailing edge along the chordwise direction is more effective in reducing shock wave-tip leakage vortex interactions. Additionally, increasing the spanwise thickness of the tip winglet enhances its capability to extend the stable operating margin. Due to the favorable regulation of the rotor flow by the tip winglet, a chordwise thickness distribution shifted toward the trailing edge leads to improved flow in the stator region; this improvement occurs as the low-energy fluid is entrained by the mainstream and migrates toward the upper span of the stator vane, resulting in a gradual reduction of the high-entropy region. The optimal tip winglet design increases the stable operating margin by 38.05%.
{"title":"Flow control mechanism of tip winglets with nonlinear thickness distribution in Stage 37 compressor","authors":"Yuan Wang, Jingjun Zhong , Wanyang Wu","doi":"10.1016/j.ijheatfluidflow.2025.110138","DOIUrl":"10.1016/j.ijheatfluidflow.2025.110138","url":null,"abstract":"<div><div>As a bio-inspired technology, tip winglet has been widely employed in compressors to enhance aerodynamic performance and improve tip flow structures. This study investigates the transonic compressor stage and refines the design criteria for tip winglet by considering the effects of nonlinear thickness distribution on aerodynamic performance. A parametric modeling approach is utilized to design tip winglets with thickness variations along both the chordwise and spanwise directions. By comparing the flow fields of various tip winglet configurations with different thickness distributions against the baseline compressor stage, this study reveals both the similarities and differences in flow stabilization mechanisms induced by each design. The results indicate that positioning the maximum thickness of the tip winglet closer to the leading edge along the chordwise direction effectively suppresses the boundary layer separation near the suction side. In contrast, positioning the maximum thickness of the tip winglet closer to the trailing edge along the chordwise direction is more effective in reducing shock wave-tip leakage vortex interactions. Additionally, increasing the spanwise thickness of the tip winglet enhances its capability to extend the stable operating margin. Due to the favorable regulation of the rotor flow by the tip winglet, a chordwise thickness distribution shifted toward the trailing edge leads to improved flow in the stator region; this improvement occurs as the low-energy fluid is entrained by the mainstream and migrates toward the upper span of the stator vane, resulting in a gradual reduction of the high-entropy region. The optimal tip winglet design increases the stable operating margin by 38.05%.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"117 ","pages":"Article 110138"},"PeriodicalIF":2.6,"publicationDate":"2025-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145525312","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}
Pub Date : 2025-11-08DOI: 10.1016/j.ijheatfluidflow.2025.110134
A. Alvarez , C. Treviño , C. Sandoval , J. Lizardi , L. Martínez-Suástegui
Time-resolved particle image velocimetry (TR-PIV) is used to examine the unsteady and mean flow of three in-line turbulent jets impinging on a sinusoidally corrugated plate. Experiments are performed at Reynolds numbers of 3000 and 5000, with jet-to-jet spacing of , impingement distances of and 6, and corrugation phase angles and . Velocity fields in three spanwise planes () are analyzed using swirling strength and cross-spectral methods to identify helical and precessing instabilities, track vortex roll-up, breakdown, and reorganization, and their effects on mixing. Time-averaged flow fields and turbulence statistics, including Reynolds stresses and turbulent kinetic energy (TKE), quantify the influence of oscillatory structures. Reducing to 3 intensifies shear-layer vortices and crossflow entrainment, particularly at , forming persistent recirculation and thick windward shear layers. At , enhanced jet penetration and wall-jet development yield thinner shear layers and elevated TKE. A phase shift to introduces asymmetry and lateral imbalances, with smaller, displaced recirculation zones and redistributed Reynolds stresses. For , jets experience greater lateral deflection and more pronounced interaction with vortex structures; the upwash fountain becomes more unstable. At , vortex merging and a narrowed upwash indicate stronger crossflow suppression and reduced fountain strength. These results show that compared with flat-target configurations, surface corrugation reorganizes the jets’-crossflow interaction, enhancing vortex-induced mixing and turbulence generation.
{"title":"Oscillatory dynamics of confined turbulent jets impinging on corrugated targets","authors":"A. Alvarez , C. Treviño , C. Sandoval , J. Lizardi , L. Martínez-Suástegui","doi":"10.1016/j.ijheatfluidflow.2025.110134","DOIUrl":"10.1016/j.ijheatfluidflow.2025.110134","url":null,"abstract":"<div><div>Time-resolved particle image velocimetry (TR-PIV) is used to examine the unsteady and mean flow of three in-line turbulent jets impinging on a sinusoidally corrugated plate. Experiments are performed at Reynolds numbers of 3000 and 5000, with jet-to-jet spacing of <span><math><mrow><mi>L</mi><mo>/</mo><mi>D</mi><mo>=</mo><mn>5</mn></mrow></math></span>, impingement distances of <span><math><mrow><mi>H</mi><mo>/</mo><mi>D</mi><mo>=</mo><mn>3</mn></mrow></math></span> and 6, and corrugation phase angles <span><math><mrow><mi>ϕ</mi><mo>=</mo><mn>0</mn><mo>°</mo></mrow></math></span> and <span><math><mrow><mn>180</mn><mo>°</mo></mrow></math></span>. Velocity fields in three spanwise planes (<span><math><mrow><mi>Z</mi><mo>=</mo><mo>−</mo><mn>0</mn><mo>.</mo><mn>3</mn><mo>,</mo><mn>0</mn><mo>,</mo><mo>+</mo><mn>0</mn><mo>.</mo><mn>3</mn></mrow></math></span>) are analyzed using swirling strength and cross-spectral methods to identify helical and precessing instabilities, track vortex roll-up, breakdown, and reorganization, and their effects on mixing. Time-averaged flow fields and turbulence statistics, including Reynolds stresses and turbulent kinetic energy (TKE), quantify the influence of oscillatory structures. Reducing <span><math><mrow><mi>H</mi><mo>/</mo><mi>D</mi></mrow></math></span> to 3 intensifies shear-layer vortices and crossflow entrainment, particularly at <span><math><mrow><mi>R</mi><mi>e</mi><mo>=</mo><mn>3000</mn></mrow></math></span>, forming persistent recirculation and thick windward shear layers. At <span><math><mrow><mi>R</mi><mi>e</mi><mo>=</mo><mn>5000</mn></mrow></math></span>, enhanced jet penetration and wall-jet development yield thinner shear layers and elevated TKE. A phase shift to <span><math><mrow><mi>ϕ</mi><mo>=</mo><mn>180</mn><mo>°</mo></mrow></math></span> introduces asymmetry and lateral imbalances, with smaller, displaced recirculation zones and redistributed Reynolds stresses. For <span><math><mrow><mi>H</mi><mo>/</mo><mi>D</mi><mo>=</mo><mn>6</mn></mrow></math></span>, jets experience greater lateral deflection and more pronounced interaction with vortex structures; the upwash fountain becomes more unstable. At <span><math><mrow><mi>R</mi><mi>e</mi><mo>=</mo><mn>5000</mn></mrow></math></span>, vortex merging and a narrowed upwash indicate stronger crossflow suppression and reduced fountain strength. These results show that compared with flat-target configurations, surface corrugation reorganizes the jets’-crossflow interaction, enhancing vortex-induced mixing and turbulence generation.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"117 ","pages":"Article 110134"},"PeriodicalIF":2.6,"publicationDate":"2025-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145473576","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}
Pub Date : 2025-11-07DOI: 10.1016/j.ijheatfluidflow.2025.110136
S. Coroama , J. Vaquero , N. Renard , F. Chedevergne
Turbulent boundary layers (TBLs) developing beneath a highly turbulent free stream are ubiquitous in turbomachinary flows and come along with a substantial increase in skin friction and wall heat transfer. A precise numerical prediction of this kind of flow is then of paramount importance in this context. Nevertheless, classical RANS (Reynolds-Averaged Navier–Stokes) turbulence models have shown to fail in this regard. The present paper presents the development process and rationale behind a multi-scale model designed to capture free-stream turbulence (FST) effects. Starting from an in-depth insight at the physical mechanisms characterising the development of TBLs under strong FST, in particular the scale separation and inactive character of the large scales, modelling guidelines are obtained. The multi-scale approach to turbulence modelling then appears to offer a sound framework for a faithful reproduction of the complex physics involved in the interaction between FST and TBLs as opposed to classical single-scale models. The two-scale model developed in this work is presented in detail and special attention is paid to how the experimental observations are transcribed in the model. Extensive testing of the two-scale model on various datasets about TBLs developing under strong FST environment is undertaken and it is shown that our modelling choices greatly improve the predictions when compared to a single-scale model.
湍流边界层（TBLs）在高度湍流的自由流下发展，在涡轮机械流动中是普遍存在的，并且伴随着表面摩擦和壁面换热的显著增加。在这种情况下，对这种流动进行精确的数值预测是至关重要的。然而，经典的RANS （reynolds - average Navier-Stokes）湍流模型在这方面显示出失败。本文介绍了设计用于捕获自由流湍流（FST）效应的多尺度k−ω模型的发展过程和基本原理。从深入了解强FST下tbl发展的物理机制开始，特别是尺度分离和大尺度的非活性特征，获得了建模指南。与经典的单尺度模型相反，湍流模型的多尺度方法似乎提供了一个可靠的框架，可以忠实地再现FST和TBLs之间相互作用所涉及的复杂物理。详细介绍了在这项工作中开发的两尺度k−ω模型，并特别注意如何在模型中转录实验观测。对两尺度模型在强FST环境下发展的TBLs的各种数据集上进行了广泛的测试，结果表明，与单尺度k−ω模型相比，我们的建模选择大大改善了预测。
{"title":"A two-scale RANS turbulence model dedicated to predicting turbulent boundary layers under high free-stream turbulence","authors":"S. Coroama , J. Vaquero , N. Renard , F. Chedevergne","doi":"10.1016/j.ijheatfluidflow.2025.110136","DOIUrl":"10.1016/j.ijheatfluidflow.2025.110136","url":null,"abstract":"<div><div>Turbulent boundary layers (TBLs) developing beneath a highly turbulent free stream are ubiquitous in turbomachinary flows and come along with a substantial increase in skin friction and wall heat transfer. A precise numerical prediction of this kind of flow is then of paramount importance in this context. Nevertheless, classical RANS (Reynolds-Averaged Navier–Stokes) turbulence models have shown to fail in this regard. The present paper presents the development process and rationale behind a multi-scale <span><math><mrow><mi>k</mi><mo>−</mo><mi>ω</mi></mrow></math></span> model designed to capture free-stream turbulence (FST) effects. Starting from an in-depth insight at the physical mechanisms characterising the development of TBLs under strong FST, in particular the scale separation and <em>inactive</em> character of the large scales, modelling guidelines are obtained. The multi-scale approach to turbulence modelling then appears to offer a sound framework for a faithful reproduction of the complex physics involved in the interaction between FST and TBLs as opposed to classical single-scale models. The two-scale <span><math><mrow><mi>k</mi><mo>−</mo><mi>ω</mi></mrow></math></span> model developed in this work is presented in detail and special attention is paid to how the experimental observations are transcribed in the model. Extensive testing of the two-scale model on various datasets about TBLs developing under strong FST environment is undertaken and it is shown that our modelling choices greatly improve the predictions when compared to a single-scale <span><math><mrow><mi>k</mi><mo>−</mo><mi>ω</mi></mrow></math></span> model.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"117 ","pages":"Article 110136"},"PeriodicalIF":2.6,"publicationDate":"2025-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145473575","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}
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