International Journal of Heat and Fluid Flow最新文献

Characteristics of turbulent Taylor-Couette flow of low-viscosity fluid on plastron-covered superhydrophobic surface

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2025-03-10 DOI: 10.1016/j.ijheatfluidflow.2025.109805

Seongbin Ahn , Sungwon Jo , Woobin Song , Haeyeon Lee , Garam Ku , Minjae Kim , Dong Rip Kim , Simon Song

This study introduces a newly developed Taylor-Couette (TC) flow system designed to investigate flow dynamics in low-viscosity fluids, such as water, under fully turbulent conditions. To ensure precise drag measurements, the system accounts for mechanical friction from bearings and von Kármán torque (the torque generated by fluid motion in the gap between the end-plates of the cylinders), enabling accurate evaluation of TC torque. Utilizing exact counter-rotation conditions that produce featureless turbulence, we explored the drag reduction capabilities of a hybrid superhydrophobic surface (SHS) mounted on the inner cylinder, alongside visualizing the resultant plastron formations. For the first time, two-dimensional particle image velocimetry (2D PIV) was used near the wall to quantify drag reduction based on total shear stress derived from flow visualization on SHS in a TC flow system. The plastron-induced slip conditions led to significant shifts in bulk velocity within the TC gap. A detailed analysis of Reynolds stresses revealed substantial modifications in flow dynamics, including reduced peak Reynolds stress and increased near-wall Reynolds stress, while total shear stress decreased across the gap. Additionally, simultaneous visualization and assessment of the plastron provided novel insights into its role in enhancing drag reduction. These findings underscore the importance of accounting for bearing mechanical friction in torque measurements when using low-viscosity fluids and confirm the effectiveness of SHS in modifying turbulence for drag reduction. The results highlight the TC-PIV system’s robust capability for detailed fluid dynamics investigations and its potential to inform hydrodynamic drag reduction strategies.

{"title":"Characteristics of turbulent Taylor-Couette flow of low-viscosity fluid on plastron-covered superhydrophobic surface","authors":"Seongbin Ahn , Sungwon Jo , Woobin Song , Haeyeon Lee , Garam Ku , Minjae Kim , Dong Rip Kim , Simon Song","doi":"10.1016/j.ijheatfluidflow.2025.109805","DOIUrl":"10.1016/j.ijheatfluidflow.2025.109805","url":null,"abstract":"<div><div>This study introduces a newly developed Taylor-Couette (TC) flow system designed to investigate flow dynamics in low-viscosity fluids, such as water, under fully turbulent conditions. To ensure precise drag measurements, the system accounts for mechanical friction from bearings and von Kármán torque (the torque generated by fluid motion in the gap between the end-plates of the cylinders), enabling accurate evaluation of TC torque. Utilizing exact counter-rotation conditions that produce featureless turbulence, we explored the drag reduction capabilities of a hybrid superhydrophobic surface (SHS) mounted on the inner cylinder, alongside visualizing the resultant plastron formations. For the first time, two-dimensional particle image velocimetry (2D PIV) was used near the wall to quantify drag reduction based on total shear stress derived from flow visualization on SHS in a TC flow system. The plastron-induced slip conditions led to significant shifts in bulk velocity within the TC gap. A detailed analysis of Reynolds stresses revealed substantial modifications in flow dynamics, including reduced peak Reynolds stress and increased near-wall Reynolds stress, while total shear stress decreased across the gap. Additionally, simultaneous visualization and assessment of the plastron provided novel insights into its role in enhancing drag reduction. These findings underscore the importance of accounting for bearing mechanical friction in torque measurements when using low-viscosity fluids and confirm the effectiveness of SHS in modifying turbulence for drag reduction. The results highlight the TC-PIV system’s robust capability for detailed fluid dynamics investigations and its potential to inform hydrodynamic drag reduction strategies.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"114 ","pages":"Article 109805"},"PeriodicalIF":2.6,"publicationDate":"2025-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143579883","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

Design criteria and performance optimization of high-power micro heat sinks

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2025-03-08 DOI: 10.1016/j.ijheatfluidflow.2025.109797

Jiali Zhuo, Yuling Zhai, Hao Huang, Zhouhang Li

A three-dimensional mathematical model of micro heat sinks was developed to achieve efficient thermal management in microelectronic devices. Comprehensive design criteria based on the theory of heat transfer enhancement at the micro-scale are also proposed. On this basis, the size of the microchannel structure is designed, considering a fixed heat transfer area and heat flux. Then, a combination of a response surface approximation, an non-dominated sorting genetic algorithm, and k-means clustering are used to optimize the width and height of each microchannel. The designed structure size is combined with supercritical carbon dioxide (SCO₂) working fluid to optimize the thermal performance of micro heat sinks. The optimization results demonstrated that the clustering point I of the evaluation factor j/f_ave increased by 4.11 %, while the wall temperature T_w decreased by 4.69 %. Compared to the SCO₂ scenario, the pump power and total entropy generation were respectively 61.63 % and 6.9 % lower than those of water with a mass flow rate of 6000 kg/m²·s and an inlet temperature of 293 K. For inlet temperatures ranging from 303 K to 307 K, the evaluation factor values reported were 0.2405, 0.2018, 0.1045, 0.1453, and 0.1747 under a pressure of 7.6 MPa and flow rate of 4000 kg/m²·s. For mass flow rates ranging from 3000 kg/m²·s to 6000 kg/m²·s, values of j/f_ave were 0.0591, 0.1045, 0.1515, and 0.2084, indicating good thermal performance at relatively high mass flow rates. It was noted that as the distance from the critical point of the channel increases, the overall heat transfer performance is improved when the inlet temperature is less than the critical temperature.

{"title":"Design criteria and performance optimization of high-power micro heat sinks","authors":"Jiali Zhuo, Yuling Zhai, Hao Huang, Zhouhang Li","doi":"10.1016/j.ijheatfluidflow.2025.109797","DOIUrl":"10.1016/j.ijheatfluidflow.2025.109797","url":null,"abstract":"<div><div>A three-dimensional mathematical model of micro heat sinks was developed to achieve efficient thermal management in microelectronic devices. Comprehensive design criteria based on the theory of heat transfer enhancement at the micro-scale are also proposed. On this basis, the size of the microchannel structure is designed, considering a fixed heat transfer area and heat flux. Then, a combination of a response surface approximation, an non-dominated sorting genetic algorithm, and <em>k</em>-means clustering are used to optimize the width and height of each microchannel. The designed structure size is combined with supercritical carbon dioxide (SCO<sub>2</sub>) working fluid to optimize the thermal performance of micro heat sinks. The optimization results demonstrated that the clustering point I of the evaluation factor <em>j</em>/<em>f</em><sub>ave</sub> increased by 4.11 %, while the wall temperature <em>T<sub>w</sub></em> decreased by 4.69 %. Compared to the SCO<sub>2</sub> scenario, the pump power and total entropy generation were respectively 61.63 % and 6.9 % lower than those of water with a mass flow rate of 6000 kg/m<sup>2</sup>·s and an inlet temperature of 293 K. For inlet temperatures ranging from 303 K to 307 K, the evaluation factor values reported were 0.2405, 0.2018, 0.1045, 0.1453, and 0.1747 under a pressure of 7.6 MPa and flow rate of 4000 kg/m<sup>2</sup>·s. For mass flow rates ranging from 3000 kg/m<sup>2</sup>·s to 6000 kg/m<sup>2</sup>·s, values of <em>j</em>/<em>f</em><sub>ave</sub> were 0.0591, 0.1045, 0.1515, and 0.2084, indicating good thermal performance at relatively high mass flow rates. It was noted that as the distance from the critical point of the channel increases, the overall heat transfer performance is improved when the inlet temperature is less than the critical temperature.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"114 ","pages":"Article 109797"},"PeriodicalIF":2.6,"publicationDate":"2025-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143579884","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 visualization of dry regions formation for Falling-Film flow patterns

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2025-03-06 DOI: 10.1016/j.ijheatfluidflow.2025.109803

Prudviraj Kandukuri, Sandip Deshmukh, Supradeepan Katiresan

Water is essential for humans in everyday life, and plenty of fresh water is required for agricultural, chemical, industrial, and other domestic uses. Water scarcity is becoming increasingly prevalent in many regions and countries as they advance their respective growth lines. The predominant method employed in thermal desalination plants is the falling-film process due to its operational advantages. The present study examines the mapping of diverse flow patterns for heat transfer mechanisms across the horizontal tube bundle. An experimental test facility is developed, and a series of visualization experiments are conducted. The FLIR E60 infrared camera is employed to examine the liquid film behavior for different temperature profiles. The findings revealed that the droplet flow pattern induces wave-like wetting, whereas the column flow pattern induces liquid ring wetting on the tube wall. The tube wall temperature attains its maximum during droplet flow, regardless of the chosen tube spacing values. When the tube spacing is 10/20/30/40 mm, the maximum temperature of the liquid film is reached rapidly in the droplet flow, reaching values of 75.7 °C, 73 °C, 79.1 °C, 65.8 °C, 76.5 °C, 71.4 °C, 69.3 °C, and 74.2 °C, respectively, in comparison to other flow modes. The infrared photographic images show that the stabilizing tube has a faster heat transfer mechanism than the test tube. Furthermore, the liquid profile on the upper portion of the tube wall exhibits a faster evaporation rate than the lower one. The formation of dry spots on the test tubes and stabilizing tubes exhibited a distinct pattern due to distinct flow mode wetting phenomena for chosen working conditions. The research findings address various aspects of information on falling-film flow behavior and mapping of flow patterns to heat transfer mechanisms.

{"title":"Experimental visualization of dry regions formation for Falling-Film flow patterns","authors":"Prudviraj Kandukuri, Sandip Deshmukh, Supradeepan Katiresan","doi":"10.1016/j.ijheatfluidflow.2025.109803","DOIUrl":"10.1016/j.ijheatfluidflow.2025.109803","url":null,"abstract":"<div><div>Water is essential for humans in everyday life, and plenty of fresh water is required for agricultural, chemical, industrial, and other domestic uses. Water scarcity is becoming increasingly prevalent in many regions and countries as they advance their respective growth lines. The predominant method employed in thermal desalination plants is the falling-film process due to its operational advantages. The present study examinesthe mapping of diverse flow patterns for heat transfer mechanisms across the horizontal tube bundle. An experimental test facility is developed, and a series of visualization experiments are conducted. The FLIR E60 infrared camera is employed to examine the liquid film behavior for different temperature profiles. The findings revealed that the droplet flow pattern induces wave-like wetting, whereas the column flow pattern induces liquid ring wetting on the tube wall. The tube wall temperature attains its maximum during droplet flow, regardless of the chosen tube spacing values. When the tube spacing is 10/20/30/40 mm, the maximum temperature of the liquid film is reached rapidly in the droplet flow, reaching values of 75.7 °C, 73 °C, 79.1 °C, 65.8 °C, 76.5 °C, 71.4 °C, 69.3 °C, and 74.2 °C, respectively, in comparison to other flow modes. The infrared photographic images show that the stabilizing tube has a faster heat transfer mechanism than the test tube. Furthermore, the liquid profile on the upper portion of the tube wall exhibits a faster evaporation rate than the lower one. The formation of dry spots on the test tubes and stabilizing tubes exhibited a distinct pattern due todistinct flow mode wetting phenomena for chosen working conditions. The research findings address various aspects of information on falling-film flow behavior and mapping of flow patterns to heat transfer mechanisms.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"114 ","pages":"Article 109803"},"PeriodicalIF":2.6,"publicationDate":"2025-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143548914","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

GMDH and RSM models for prediction of heat transfer parameters in an ultrasonic vibrating fin-and-tube heat exchanger

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2025-03-04 DOI: 10.1016/j.ijheatfluidflow.2025.109795

M. Esfandyari , H. Sajjadi , A. Amiri Delouei

This study employed the Group Method of Data Handling (GMDH) and Response Surface Methodology (RSM) to predict key heat transfer parameters, including the Nusselt number (Nu), outlet temperature, heat flow, and convective heat transfer coefficient in a fin-and-tube heat exchanger (FTHX) subjected to ultrasonic vibrations. Experimental investigations were conducted with varying inlet temperatures (10–140 °C), flow rates (2–6 l/min), air velocities (0.1–4 m/s), and ultrasonic power levels (0 or 50 W). The models’ accuracy was validated against experimental data, showing high correlation coefficients exceeding 0.98. The GMDH model slightly outperformed the RSM model. The maximum absolute average relative error (AARE) was 0.0633, demonstrating the models’ precision. These findings provide valuable insights for optimizing thermal systems and enhancing heat transfer efficiency in heat exchangers through ultrasonic vibration.

引用次数: 0

Study on the influence of tube type and fluid flow channel on cooling heat transfer characteristics of supercritical CO2 in spirally grooved casing tubes

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2025-03-04 DOI: 10.1016/j.ijheatfluidflow.2025.109804

Dong Wang , Rongrong Zhou , Mengxue Li , Kangkang Zhang , Zilong Wang , Kang Li , Huaqiang Chu

This study investigates the heat transfer characteristics of supercritical CO₂ (SCO₂) in five different spirally grooved casing tubes and proposes a comprehensive evaluation factor to assess their overall performance, aiming to improve heat exchanger efficiency through optimizing tube designs. The Finite Volume Method is employed to simulate and compare five different spirally grooved configurations: three-start circular arc (Case A), four-start circular arc (Case B), four-start trapezoidal (Case C), four-start triangular (Case D), and six-start circular arc (Case E). The results show that when SCO₂ flows through the channel between the inner and outer tubes (channel 1), Case E exhibits the highest heat transfer coefficient, with a value of 2537.91 W·(m²·K)⁻¹. This is significantly higher than the other designs, with a maximum increase of 19.20 %, demonstrating its optimal performance in enhancing heat transfer efficiency. In the inner tube channel (channel 2), the average heat transfer coefficients for Case D and Case E are approximately equal, around 2410 W·(m²·K)⁻¹, which is 3.22 % higher on average than the other three designs, indicating impressive potential for optimizing the groove shape in channel 2. The pattern of SCO₂ flowing in channel 2 can effectively reduce the pressure drop gradient, with a maximum reduction of 27.60 %, thereby significantly improving the safety of the system. The flow pattern of SCO₂ in channel 2 of Case A exhibits the optimal comprehensive evaluation factor value (2.03). These scientific findings provide conducive insights for optimizing design of the SCO₂ heat exchangers.

{"title":"Study on the influence of tube type and fluid flow channel on cooling heat transfer characteristics of supercritical CO2 in spirally grooved casing tubes","authors":"Dong Wang , Rongrong Zhou , Mengxue Li , Kangkang Zhang , Zilong Wang , Kang Li , Huaqiang Chu","doi":"10.1016/j.ijheatfluidflow.2025.109804","DOIUrl":"10.1016/j.ijheatfluidflow.2025.109804","url":null,"abstract":"<div><div>This study investigates the heat transfer characteristics of supercritical CO<sub>2</sub> (SCO<sub>2</sub>) in five different spirally grooved casing tubes and proposes a comprehensive evaluation factor to assess their overall performance, aiming to improve heat exchanger efficiency through optimizing tube designs. The Finite Volume Method is employed to simulate and compare five different spirally grooved configurations: three-start circular arc (Case A), four-start circular arc (Case B), four-start trapezoidal (Case C), four-start triangular (Case D), and six-start circular arc (Case E). The results show that when SCO<sub>2</sub> flows through the channel between the inner and outer tubes (channel 1), Case E exhibits the highest heat transfer coefficient, with a value of 2537.91 W·(m<sup>2</sup>·K)<sup>−1</sup>. This is significantly higher than the other designs, with a maximum increase of 19.20 %, demonstrating its optimal performance in enhancing heat transfer efficiency. In the inner tube channel (channel 2), the average heat transfer coefficients for Case D and Case E are approximately equal, around 2410 W·(m<sup>2</sup>·K)<sup>−1</sup>, which is 3.22 % higher on average than the other three designs, indicating impressive potential for optimizing the groove shape in channel 2. The pattern of SCO<sub>2</sub> flowing in channel 2 can effectively reduce the pressure drop gradient, with a maximum reduction of 27.60 %, thereby significantly improving the safety of the system. The flow pattern of SCO<sub>2</sub> in channel 2 of Case A exhibits the optimal comprehensive evaluation factor value (2.03). These scientific findings provide conducive insights for optimizing design of the SCO<sub>2</sub> heat exchangers.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"114 ","pages":"Article 109804"},"PeriodicalIF":2.6,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143548915","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

Pore distribution and permeability principles for carbon fiber reinforced silicon carbide matrix composites with three-dimensional needled preform during the transpiration cooling process

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2025-03-04 DOI: 10.1016/j.ijheatfluidflow.2025.109799

Tao Ding , Xiaoxuan Chen , Ling Zhao , Hainan Zhang , Tian Zhao , Chaoyi Zhu , Shiyu Qian , Lingyun hou , Yi Zhang , Litong Zhang

Transpiration cooling problem in carbon fiber reinforced silicon carbide matrix composites (C/SiC) was studied based on the context of cooling of jet engine hot-end components. Pore distributions of C/SiC with different fiber preforms were compared, and the C/SiC with three-dimensional needled preform (3DN C/SiC) was selected. The pore structure of 3DN C/SiC was analyzed and studied by X-ray computed tomography scanning (CT), and its porosity was obtained based on the Archimedes’ principle. Finally, based on the Darcy–Forchheimer model, the pressure drop–flow rate curve was obtained and the permeability of 3DN C/SiC was calculated. By considering the influence of inertia and viscous forces, the characteristics and mechanism of the porous media flow inside 3DN C/SiC were analyzed. The results showed that 3DN C/SiC could achieve a permeability of 3.37 × 10^–12 m² under a porosity of 47.61 %, which was close to that of commonly used metal porous media. 3DN C/SiC also demonstrated good flow characteristics as a porous medium. Considering its other advantages, such as high temperature resistance, light weight, and high specific strength, 3DN C/SiC has excellent potential and prospects in jet-engine thermal protection systems.

{"title":"Pore distribution and permeability principles for carbon fiber reinforced silicon carbide matrix composites with three-dimensional needled preform during the transpiration cooling process","authors":"Tao Ding , Xiaoxuan Chen , Ling Zhao , Hainan Zhang , Tian Zhao , Chaoyi Zhu , Shiyu Qian , Lingyun hou , Yi Zhang , Litong Zhang","doi":"10.1016/j.ijheatfluidflow.2025.109799","DOIUrl":"10.1016/j.ijheatfluidflow.2025.109799","url":null,"abstract":"<div><div>Transpiration cooling problem in carbon fiber reinforced silicon carbide matrix composites (C/SiC) was studied based on the context of cooling of jet engine hot-end components. Pore distributions of C/SiC with different fiber preforms were compared, and the C/SiC with three-dimensional needled preform (3DN C/SiC) was selected. The pore structure of 3DN C/SiC was analyzed and studied by X-ray computed tomography scanning (CT), and its porosity was obtained based on the Archimedes’ principle. Finally, based on the Darcy–Forchheimer model, the pressure drop–flow rate curve was obtained and the permeability of 3DN C/SiC was calculated. By considering the influence of inertia and viscous forces, the characteristics and mechanism of the porous media flow inside 3DN C/SiC were analyzed. The results showed that 3DN C/SiC could achieve a permeability of 3.37 × 10<sup>–12</sup> m<sup>2</sup> under a porosity of 47.61 %, which was close to that of commonly used metal porous media. 3DN C/SiC also demonstrated good flow characteristics as a porous medium. Considering its other advantages, such as high temperature resistance, light weight, and high specific strength, 3DN C/SiC has excellent potential and prospects in jet-engine thermal protection systems.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"114 ","pages":"Article 109799"},"PeriodicalIF":2.6,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143548916","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

RANS investigation of incoming vortex on the tip leakage vortex breakdown in an aspirated compressor cascade

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2025-03-02 DOI: 10.1016/j.ijheatfluidflow.2025.109796

Xi Gao, Zhiyuan Cao, Bo Liu

Boundary layer suction is an efficient method for mitigating flow separation and enhancing the performance of a highly loaded compressor cascade. Nevertheless, in a compressor cascade with tip clearance, the high adverse-pressure gradient induced by suction can exert a negative impact on tip leakage vortex (TLV), leading to tip leakage vortex breakdown (TVB). In order to control TVB and enhance its performance, a vortex generator (VG) has been employed in an aspirated compressor cascade. The effect of the swirling direction of the incoming vortex induced by VG, suction flow rate, tip clearance size, and solidity were also investigated. The results reveal that TVB can occur even in a conventional compressor cascade with suction. For the newly designed compressor cascade, TVB can occur without suction, and the introduction of suction enhances TVB. After introducing an incoming vortex, TVB in the aspirated compressor cascade with suction is eliminated. The loss in the aspirated compressor cascade is reduced by 47.1% compared to that in the newly designed compressor cascade. The incoming vortex further reduces the loss by 1% compared to the aspirated compressor cascade due to the suppression of TVB. This outcome can be attributed to the fact that a co-rotating incoming vortex increases the core axial velocity of TLV and reduces its strength, thereby enabling TLV to withstand the high adverse pressure gradient induced by suction. It is worth noting that a counter-rotating incoming vortex enhances TVB, making it an unsuitable design for controlling TVB.

{"title":"RANS investigation of incoming vortex on the tip leakage vortex breakdown in an aspirated compressor cascade","authors":"Xi Gao, Zhiyuan Cao, Bo Liu","doi":"10.1016/j.ijheatfluidflow.2025.109796","DOIUrl":"10.1016/j.ijheatfluidflow.2025.109796","url":null,"abstract":"<div><div>Boundary layer suction is an efficient method for mitigating flow separation and enhancing the performance of a highly loaded compressor cascade. Nevertheless, in a compressor cascade with tip clearance, the high adverse-pressure gradient induced by suction can exert a negative impact on tip leakage vortex (TLV), leading to tip leakage vortex breakdown (TVB). In order to control TVB and enhance its performance, a vortex generator (VG) has been employed in an aspirated compressor cascade. The effect of the swirling direction of the incoming vortex induced by VG, suction flow rate, tip clearance size, and solidity were also investigated. The results reveal that TVB can occur even in a conventional compressor cascade with suction. For the newly designed compressor cascade, TVB can occur without suction, and the introduction of suction enhances TVB. After introducing an incoming vortex, TVB in the aspirated compressor cascade with suction is eliminated. The loss in the aspirated compressor cascade is reduced by 47.1% compared to that in the newly designed compressor cascade. The incoming vortex further reduces the loss by 1% compared to the aspirated compressor cascade due to the suppression of TVB. This outcome can be attributed to the fact that a co-rotating incoming vortex increases the core axial velocity of TLV and reduces its strength, thereby enabling TLV to withstand the high adverse pressure gradient induced by suction. It is worth noting that a counter-rotating incoming vortex enhances TVB, making it an unsuitable design for controlling TVB.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"114 ","pages":"Article 109796"},"PeriodicalIF":2.6,"publicationDate":"2025-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143527210","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 of grooved cylinder-airfoil interaction noise reduction at different Reynolds numbers

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2025-03-01 DOI: 10.1016/j.ijheatfluidflow.2024.109697

Chengchun Zhang , Xiaowei Sun , Wen Cheng , Chun Shen , Zhen Cui , Zhengyang Wu , Dong Liang

The grooved model, which is designed for the upstream cylinder, is intended to minimize the interaction noise generated by the cylinder-airfoil model. The impact of the grooved model on noise reduction performance is investigated at Reynolds number (Re) values of 2.6 × 10⁴, 5.3 × 10⁴, and 7.9 × 10⁴ through the application of large eddy simulation (LES). The results demonstrate that the grooved model has a negligible effect on performance at Re = 2.6 × 10⁴. However, as Re increases, the grooved model leads to a reduction in surface pressure pulsation on both the cylinder and airfoil surfaces, resulting in a decrease in peak noise levels of 4.2 dB and 17.7 dB, respectively. The overall sound pressure level (OASPL) is reduced by 3.2 dB and 10.8 dB, respectively. This noise reduction can be attributed to the decrease in shear stress on the cylinder surface with an increasing Re, which inhibits the formation of large-scale spanwise vortex structures in the wake of the cylinder and thus weakens the interaction between the wake and the airfoil. Dynamic mode decomposition (DMD) is used to analyze the modal characteristics of the flow field structure at Re = 7.9 × 10⁴, revealing that the first 7 modes of the smooth model exhibit high-energy, low-frequency characteristics, while the grooved model notably diminishes the intensity and scale of the vortices at the leading edge of the airfoil.

{"title":"Numerical investigation of grooved cylinder-airfoil interaction noise reduction at different Reynolds numbers","authors":"Chengchun Zhang , Xiaowei Sun , Wen Cheng , Chun Shen , Zhen Cui , Zhengyang Wu , Dong Liang","doi":"10.1016/j.ijheatfluidflow.2024.109697","DOIUrl":"10.1016/j.ijheatfluidflow.2024.109697","url":null,"abstract":"<div><div>The grooved model, which is designed for the upstream cylinder, is intended to minimize the interaction noise generated by the cylinder-airfoil model. The impact of the grooved model on noise reduction performance is investigated at Reynolds number (<em>Re</em>) values of 2.6 × 10<sup>4</sup>, 5.3 × 10<sup>4</sup>, and 7.9 × 10<sup>4</sup> through the application of large eddy simulation (LES). The results demonstrate that the grooved model has a negligible effect on performance at <em>Re</em> = 2.6 × 10<sup>4</sup>. However, as <em>Re</em> increases, the grooved model leads to a reduction in surface pressure pulsation on both the cylinder and airfoil surfaces, resulting in a decrease in peak noise levels of 4.2 dB and 17.7 dB, respectively. The overall sound pressure level (OASPL) is reduced by 3.2 dB and 10.8 dB, respectively. This noise reduction can be attributed to the decrease in shear stress on the cylinder surface with an increasing <em>Re</em>, which inhibits the formation of large-scale spanwise vortex structures in the wake of the cylinder and thus weakens the interaction between the wake and the airfoil. Dynamic mode decomposition (DMD) is used to analyze the modal characteristics of the flow field structure at <em>Re</em> = 7.9 × 10<sup>4</sup>, revealing that the first 7 modes of the smooth model exhibit high-energy, low-frequency characteristics, while the grooved model notably diminishes the intensity and scale of the vortices at the leading edge of the airfoil.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"112 ","pages":"Article 109697"},"PeriodicalIF":2.6,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143508706","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

Compressed representation of separation bubbles from a vast database

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2025-02-28 DOI: 10.1016/j.ijheatfluidflow.2025.109779

Virginia Bologna, Matteo Dellacasagrande, Davide Lengani, Daniele Simoni

The present work describes a wide experimental database of laminar separation bubbles formed on a flat plate for different Reynolds numbers, adverse pressure gradients and free-stream turbulence intensity levels. The database accounts for 72 different combinations of the aforementioned parameters, for which both short and long bubble types have been observed. For each flow case, a set of 6000 snapshots has been acquired using a fast response Particle Image Velocimetry system. In this work all the 72 × 6000 images have been used simultaneously to construct a large snapshot matrix containing both the statistical and the dynamic response of the bubble to the flow parameters variation. To handle such a large snapshot matrix, a parallelized version of the Proper Orthogonal Decomposition routine is presented to be adopted in High-Performance Computing environment. The reduction of the high dimensional database into a low-order model retaining few POD modes and coefficients has been obtained. Particularly, two subsets of modes capturing the time-averaged and dynamic response of the bubble have been detected based on the frequency spectra of the related coefficients. It will be shown that dimensionality can be reduced up to about 1%, while retaining the generalized response of a laminar separation bubble. The present work therefore shows the existence of a reduced state space over which the response of a LSB evolves for a wide range of the leading influencing parameters.

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引用次数: 0

Dissipation pressure quotient (DPQ): A refined approach for meshing of cerebral venous geometries for high-fidelity computational fluid dynamics

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2025-02-28 DOI: 10.1016/j.ijheatfluidflow.2025.109783

A.L. Haley , G. Sidora , N.M. Cancelliere , V.M. Pereira , D.A. Steinman

Recently we used high-fidelity computational fluid dynamics (CFD) simulations to demonstrate the relevance of high-frequency (

\sim 100 - 1000 Hz

) flow instabilities to clinical phenomena associated with cerebral venous disorders, such as pulsatile tinnitus (PT). We have previously demonstrated the challenges of a priori meshing of the tortuous venous sinus geometries and hence accurately computing the complex flow phenomena they engender, but also the invariance of bulk pressure phenomena with CFD resolution. Building on that work, here we propose a convergence criterion based on the viscous dissipation term from the work-energy relative pressure drop (WERP) form of the Navier–Stokes equations normalized by the total pressure drop – a quantity we term the dissipation-pressure quotient (DPQ). In the present study, DPQ was used to show, for three patient-specific geometries, that although qualitative differences in bulk flow patterns from a series of conventionally refined meshes were minimal, quantitatively the differences were not asymptotically converged. Nevertheless, the relative distribution of maximum viscous dissipation rate was comparable with mesh resolution, suggesting its use for identifying regions in the mesh requiring greater resolution a posteriori, even on under-resolved meshes, and marking them for refinement. Using DPQ as a convergence criterion, we show that this refinement strategy allows for more effective use of elements when executed from both moderate- and coarse-resolution starting meshes. Unlike conventional adaptive meshing, this strategy allows for multiple refinements to be run in parallel, permitting efficient verification studies within time frames necessary for clinical decision-making, and helps to overcome some of the guesswork involved with meshing of these complicated geometries, toward robust prediction of blood flow disturbances in cerebral venous disorders.

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引用次数: 0