International Journal of Heat and Fluid Flow最新文献_第4页

Investigations on the energy conversion characteristics and the prediction of power and efficiency of a multiphase pump under gas-liquid conditions

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2025-01-31 DOI: 10.1016/j.ijheatfluidflow.2025.109768

Chenyu Yang, Qiang Xu, Xiaoyu Dai, Xiaobin Su, Liejin Guo

During the long-term multiphase pressurization transport process, the multiphase pumps consume a large amount of energy. In order to evaluate the performances of multiphase pump reasonably and accurately under gas–liquid conditions for guiding the operation control and structural optimization to achieve energy saving and consumption reduction, the gas–liquid performances of a three-stage mixed-flow multiphase pump are experimentally studied in this paper. The influences of gas–liquid flow rate, pump-inlet gas volume fraction (GVF), pump-inlet pressure, rotational speed, stage number on the energy conversion characteristics of multiphase pump such as head, power and efficiency are comprehensively analyzed. It is discovered that the relative change rates of gas–liquid flow rate between the inlet and outlet of both the pump and the booster stage show an inverted U-shaped variation trend with the increase of pump-inlet GVF. Increasing the pump-inlet pressure, rotational speed and stage number can delay the occurrence of gas–liquid head deterioration in the direction of high GVF. Moreover, the increase of both pump-inlet pressure and rotational speed can achieve the synchronous improvement of the shaft power, useful power and efficiency of multiphase pump. Under different operating conditions, the useful power distribution ratio between the gas phase and the liquid phase follows the same monotonically increasing distribution law with the increase of pump-inlet GVF. The internal relationships between the head coefficient and the shaft power coefficient and the efficiency coefficient under gas–liquid conditions are established. Finally, the prediction models of the shaft power and efficiency of multiphase pump are developed. The prediction relative errors of both shaft power and efficiency are within ± 10 %.

{"title":"Investigations on the energy conversion characteristics and the prediction of power and efficiency of a multiphase pump under gas-liquid conditions","authors":"Chenyu Yang, Qiang Xu, Xiaoyu Dai, Xiaobin Su, Liejin Guo","doi":"10.1016/j.ijheatfluidflow.2025.109768","DOIUrl":"10.1016/j.ijheatfluidflow.2025.109768","url":null,"abstract":"<div><div>During the long-term multiphase pressurization transport process, the multiphase pumps consume a large amount of energy. In order to evaluate the performances of multiphase pump reasonably and accurately under gas–liquid conditions for guiding the operation control and structural optimization to achieve energy saving and consumption reduction, the gas–liquid performances of a three-stage mixed-flow multiphase pump are experimentally studied in this paper. The influences of gas–liquid flow rate, pump-inlet gas volume fraction (GVF), pump-inlet pressure, rotational speed, stage number on the energy conversion characteristics of multiphase pump such as head, power and efficiency are comprehensively analyzed. It is discovered that the relative change rates of gas–liquid flow rate between the inlet and outlet of both the pump and the booster stage show an inverted U-shaped variation trend with the increase of pump-inlet GVF. Increasing the pump-inlet pressure, rotational speed and stage number can delay the occurrence of gas–liquid head deterioration in the direction of high GVF. Moreover, the increase of both pump-inlet pressure and rotational speed can achieve the synchronous improvement of the shaft power, useful power and efficiency of multiphase pump. Under different operating conditions, the useful power distribution ratio between the gas phase and the liquid phase follows the same monotonically increasing distribution law with the increase of pump-inlet GVF. The internal relationships between the head coefficient and the shaft power coefficient and the efficiency coefficient under gas–liquid conditions are established. Finally, the prediction models of the shaft power and efficiency of multiphase pump are developed. The prediction relative errors of both shaft power and efficiency are within ± 10 %.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"112 ","pages":"Article 109768"},"PeriodicalIF":2.6,"publicationDate":"2025-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140613","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

Thermo-elastic model and surface evaporation model to Reveal the damage mechanism of melanocytes induced by laser ablation

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2025-01-30 DOI: 10.1016/j.ijheatfluidflow.2025.109763

Bin Chen , Yuqi Sun , Chunyang Xiao , Dong Li , Xiaojie Du , Guoxiang Wang , Weihui Zeng

This study aims to investigate the interaction between laser irradiation and melanosome particles in Ota’s nevus, as well as to elucidate the thermomechanical damage mechanism of melanin particles. Thermo-elastic and surface evaporation models were employed to simulate the effects of laser ablation on melanin. These models were utilized to analyze the pressure gradient at the melanosome-tissue interface and the formation of vaporization nuclei on melanosome surfaces. Experimental observations were conducted on a tattooed dorsal skin model to examine tissue cavitation and skin whitening. Transient laser heating induced a significant pressure gradient at the melanosome-tissue interface, contributing to mechanical damage. Pulse width exhibited minimal impact on surface evaporation when smaller than the thermal relaxation time of melanosome, while energy density determined the formation of vaporization nuclei. After laser irradiation with an energy density of 4–5 J/cm², the tissue undergoes vaporization caused by cavitation. Bubble formation resulting from surface vaporization of melanosome explained tissue cavitation and skin whitening. Melanosome particle clusters with smaller spacing exhibited higher peak temperatures and more intense phase transitions, leading to structural damage through rapid bubble expansion. Conversely, larger spacing between melanosome particles resulted in thermal diffusion within cells and overall cell thermal injury. When the particle spacing increased to 0.15 μm, it was observed that the region of microbubble formation in the melanocytes continued to expand, even in the absence of vaporization nuclei formation. Short pulsed laser irradiation effectively treats Ota’s nevus by inducing thermomechanical damage to melanosome particles.

{"title":"Thermo-elastic model and surface evaporation model to Reveal the damage mechanism of melanocytes induced by laser ablation","authors":"Bin Chen , Yuqi Sun , Chunyang Xiao , Dong Li , Xiaojie Du , Guoxiang Wang , Weihui Zeng","doi":"10.1016/j.ijheatfluidflow.2025.109763","DOIUrl":"10.1016/j.ijheatfluidflow.2025.109763","url":null,"abstract":"<div><div>This study aims to investigate the interaction between laser irradiation and melanosome particles in Ota’s nevus, as well as to elucidate the thermomechanical damage mechanism of melanin particles. Thermo-elastic and surface evaporation models were employed to simulate the effects of laser ablation on melanin. These models were utilized to analyze the pressure gradient at the melanosome-tissue interface and the formation of vaporization nuclei on melanosome surfaces. Experimental observations were conducted on a tattooed dorsal skin model to examine tissue cavitation and skin whitening. Transient laser heating induced a significant pressure gradient at the melanosome-tissue interface, contributing to mechanical damage. Pulse width exhibited minimal impact on surface evaporation when smaller than the thermal relaxation time of melanosome, while energy density determined the formation of vaporization nuclei. After laser irradiation with an energy density of 4–5 J/cm<sup>2</sup>, the tissue undergoes vaporization caused by cavitation. Bubble formation resulting from surface vaporization of melanosome explained tissue cavitation and skin whitening. Melanosome particle clusters with smaller spacing exhibited higher peak temperatures and more intense phase transitions, leading to structural damage through rapid bubble expansion. Conversely, larger spacing between melanosome particles resulted in thermal diffusion within cells and overall cell thermal injury. When the particle spacing increased to 0.15 μm, it was observed that the region of microbubble formation in the melanocytes continued to expand, even in the absence of vaporization nuclei formation. <em>Short pulsed</em> laser irradiation effectively treats Ota’s nevus by inducing thermomechanical damage to melanosome particles.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"112 ","pages":"Article 109763"},"PeriodicalIF":2.6,"publicationDate":"2025-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140614","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 study on heat and mass transfer characteristics in the spray zone for an improved closed-type heat source tower

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2025-01-29 DOI: 10.1016/j.ijheatfluidflow.2025.109761

Shuaijie Ding , Yi Zhang , Dan Zhou , Zheng Zhang , Maocheng Tian , Guanmin Zhang

It is of great scientific significance to strengthen the heat transfer process in the closed-type heat source tower by improving its structure and operation mode. In this study, an improved closed-type heat source tower was proposed, which uses spray zone instead of finned tube heat exchanger to solve the disadvantages of traditional heat exchanger such as high air flow resistance and local frost formation. On this basis, an improved transient numerical model of spray zone in the closed-type heat source tower was established, and the effects of mass flow rate, initial temperature of the spray solution, velocity and spray angle on heat and mass transfer characteristics were studied. The results show that the effect of velocity on the transfer rate of sensible and latent heat is different. When the velocity of humid air exceeds 1.2 m/s, it will cause the sensible heat transfer rate to decrease slightly; however, it promotes the transfer rate of latent heat significantly, resulting in greater dilution of the spray solution. When the spray angle is between 100° and 120°, the total heat transfer rate increases by about 6 % for every 10° increase in spray angle. However, excessive spray angle will cause the droplets to adhere to the wall, thus increasing latent heat transfer and weakening sensible heat transfer rates. Additionally, the mass flow rate of the spray solution has a significant impact on both sensible heat and latent heat transfer, but the initial temperature only has a remarkable influence on sensible heat transfer. Finally, the optimal combination of axial relative velocity, spray angle, mass flow rate and initial temperature of spray solution is given based on response surface analysis, which are 3.7 m/s, 102.9°, 1.5 kg/s and −7.4 °C, respectively.

{"title":"Numerical study on heat and mass transfer characteristics in the spray zone for an improved closed-type heat source tower","authors":"Shuaijie Ding , Yi Zhang , Dan Zhou , Zheng Zhang , Maocheng Tian , Guanmin Zhang","doi":"10.1016/j.ijheatfluidflow.2025.109761","DOIUrl":"10.1016/j.ijheatfluidflow.2025.109761","url":null,"abstract":"<div><div>It is of great scientific significance to strengthen the heat transfer process in the closed-type heat source tower by improving its structure and operation mode. In this study, an improved closed-type heat source tower was proposed, which uses spray zone instead of finned tube heat exchanger to solve the disadvantages of traditional heat exchanger such as high air flow resistance and local frost formation. On this basis, an improved transient numerical model of spray zone in the closed-type heat source tower was established, and the effects of mass flow rate, initial temperature of the spray solution, velocity and spray angle on heat and mass transfer characteristics were studied. The results show that the effect of velocity on the transfer rate of sensible and latent heat is different. When the velocity of humid air exceeds 1.2 m/s, it will cause the sensible heat transfer rate to decrease slightly; however, it promotes the transfer rate of latent heat significantly, resulting in greater dilution of the spray solution. When the spray angle is between 100° and 120°, the total heat transfer rate increases by about 6 % for every 10° increase in spray angle. However, excessive spray angle will cause the droplets to adhere to the wall, thus increasing latent heat transfer and weakening sensible heat transfer rates. Additionally, the mass flow rate of the spray solution has a significant impact on both sensible heat and latent heat transfer, but the initial temperature only has a remarkable influence on sensible heat transfer. Finally, the optimal combination of axial relative velocity, spray angle, mass flow rate and initial temperature of spray solution is given based on response surface analysis, which are 3.7 m/s, 102.9°, 1.5 kg/s and −7.4 °C, respectively.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"112 ","pages":"Article 109761"},"PeriodicalIF":2.6,"publicationDate":"2025-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140615","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

Passive Fluidic control of flow around circular cylinder

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2025-01-28 DOI: 10.1016/j.ijheatfluidflow.2025.109750

James Ramsay , Mathieu Sellier , Wei Hua Ho

Suction of the boundary layer is an effective means of delaying separation and reducing drag on external flows. However, if a pumping system is required to generate the suction, the weight and power consumption of the system can undo that benefit. ‘Autogenous’ (self-generating) suction control is a type of flow control that utilises the energy already within a flow (notably the pressure gradients) to drive the suction, thereby requiring no further energy to the system. This paper describes numerical studies that were performed on the flow around the circular cylinder in the 2D laminar range: Re = 40 (steady) and Re = 120 (unsteady). Suction and blowing control were implemented by imposed velocity boundary conditions. These controls were then modified using optimisation methods to generate arrangements of suction and blowing that can be passively generated by their pressure differential (i.e. Ps ≥ Pb). Steady and unsteady simulations were performed. It was found that at both Re = 40 and Re = 120 drag-reducing arrangements could be produced. At Re = 120 a reduction in drag of 4.3 % was found while maintaining a positive pressure differential from the suction to blowing loci. This approach for developing passive suction control can be applied to other bluff body flows and higher Reynolds numbers to design efficient optimised flow control although specifics of the control parameters may be slightly different.

{"title":"Passive Fluidic control of flow around circular cylinder","authors":"James Ramsay , Mathieu Sellier , Wei Hua Ho","doi":"10.1016/j.ijheatfluidflow.2025.109750","DOIUrl":"10.1016/j.ijheatfluidflow.2025.109750","url":null,"abstract":"<div><div>Suction of the boundary layer is an effective means of delaying separation and reducing drag on external flows. However, if a pumping system is required to generate the suction, the weight and power consumption of the system can undo that benefit. ‘Autogenous’ (self-generating) suction control is a type of flow control that utilises the energy already within a flow (notably the pressure gradients) to drive the suction, thereby requiring no further energy to the system. This paper describes numerical studies that were performed on the flow around the circular cylinder in the 2D laminar range: <em>Re</em> = 40 (steady) and <em>Re</em> = 120 (unsteady). Suction and blowing control were implemented by imposed velocity boundary conditions. These controls were then modified using optimisation methods to generate arrangements of suction and blowing that can be passively generated by their pressure differential (i.e. <em>Ps ≥ Pb</em>). Steady and unsteady simulations were performed. It was found that at both <em>Re</em> = 40 and <em>Re</em> = 120 drag-reducing arrangements could be produced. At <em>Re</em> = 120 a reduction in drag of 4.3 % was found while maintaining a positive pressure differential from the suction to blowing loci. This approach for developing passive suction control can be applied to other bluff body flows and higher Reynolds numbers to design efficient optimised flow control although specifics of the control parameters may be slightly different.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"112 ","pages":"Article 109750"},"PeriodicalIF":2.6,"publicationDate":"2025-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140617","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

Conjugate heat transfer simulation the impact of CMAS non-uniform deposition on the cooling effectiveness of a coated C3X vane

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2025-01-28 DOI: 10.1016/j.ijheatfluidflow.2025.109755

Xiao Tan, Li Shi, Rongli Deng, Liang Su, Jinfeng Peng, Jiasheng Song, Junjie Chen

This study developed a coupled heat transfer and deposit layer dynamic growth model to evaluate the nonuniform deposition behavior of CMAS particles and its impact on the cooling effectiveness of coated C3X high-pressure turbine vanes. Results show that particle accumulation creates protruding deposits at the leading edge and ridge-like deposits at the trailing edge. The low thermal conductivity of TBCs causes the coated vane’s surface temperature and deposit mass to rise significantly, approximately 27.0 K and 47 %, after 9000 h compared to the uncoated vane. Higher deposit surface temperatures increase pressure side temperatures, reducing heat transfer to the vane and lowering internal temperatures. In the absence of deposition, suction side temperatures decrease for both coated and uncoated vanes. Particle impacts increase linearly over time, influenced by diameter, with less effect for particles larger than 11 μm. The coated vane’s higher surface temperature results in a significantly higher particle deposition rate. After 9000 h, deposition efficiency for the coated vane rises from 2.96 % to 4.36 %. As deposition efficiency improves, overall cooling effectiveness increases over time, particularly at the leading and trailing edges, with the average increment rising from 9.4 % to 13 %.

{"title":"Conjugate heat transfer simulation the impact of CMAS non-uniform deposition on the cooling effectiveness of a coated C3X vane","authors":"Xiao Tan, Li Shi, Rongli Deng, Liang Su, Jinfeng Peng, Jiasheng Song, Junjie Chen","doi":"10.1016/j.ijheatfluidflow.2025.109755","DOIUrl":"10.1016/j.ijheatfluidflow.2025.109755","url":null,"abstract":"<div><div>This study developed a coupled heat transfer and deposit layer dynamic growth model to evaluate the nonuniform deposition behavior of CMAS particles and its impact on the cooling effectiveness of coated C3X high-pressure turbine vanes. Results show that particle accumulation creates protruding deposits at the leading edge and ridge-like deposits at the trailing edge. The low thermal conductivity of TBCs causes the coated vane’s surface temperature and deposit mass to rise significantly, approximately 27.0 K and 47 %, after 9000 h compared to the uncoated vane. Higher deposit surface temperatures increase pressure side temperatures, reducing heat transfer to the vane and lowering internal temperatures. In the absence of deposition, suction side temperatures decrease for both coated and uncoated vanes. Particle impacts increase linearly over time, influenced by diameter, with less effect for particles larger than 11 μm. The coated vane’s higher surface temperature results in a significantly higher particle deposition rate. After 9000 h, deposition efficiency for the coated vane rises from 2.96 % to 4.36 %. As deposition efficiency improves, overall cooling effectiveness increases over time, particularly at the leading and trailing edges, with the average increment rising from 9.4 % to 13 %.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"112 ","pages":"Article 109755"},"PeriodicalIF":2.6,"publicationDate":"2025-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140166","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 study of pressurization and flow characteristics of rotating detonation combustor by channel configuration and outlet contraction ratio

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2025-01-28 DOI: 10.1016/j.ijheatfluidflow.2025.109764

Zhanming Chen , Lvmeng Huang , Jinxuan Xu , Zhao Yang

To investigate the flow and pressurization characteristics of a rotating detonation combustor, numerical simulations were conducted in this study by analyzing the different channel configurations and a range of outlet contraction ratios. Different degrees of curved constriction channels were designed for comparison with a straight constriction channel. In addition, the effect on pressurization and flow was investigated by adjusting the combustion chamber’s outlet contraction ratio. The research indicated that the total pressure of a curved constriction channel was greater than that of a straight constriction channel. However, when a constriction channel with greater convergence was introduced, the outlet total pressure decreased. In addition, for the same constriction channel, the total pressure at the outlet increased with a decreasing outlet contraction ratio. Under the influence of the contraction effect, the continuous acceleration effect of the gas in the channel was improved, resulting in the critical sonic speed at the outlet. In summary, only a moderately curved constriction channel can achieve a better pressurization effect. When the outlet contraction ratio reached 0.75, the combustors total outlet pressure achieved its maximum, and the downstream continuous acceleration effect was optimal. This study provides a research basis for the pressurization characteristics of rotating detonation engines through numerical calculations.

{"title":"Numerical study of pressurization and flow characteristics of rotating detonation combustor by channel configuration and outlet contraction ratio","authors":"Zhanming Chen , Lvmeng Huang , Jinxuan Xu , Zhao Yang","doi":"10.1016/j.ijheatfluidflow.2025.109764","DOIUrl":"10.1016/j.ijheatfluidflow.2025.109764","url":null,"abstract":"<div><div>To investigate the flow and pressurization characteristics of a rotating detonation combustor, numerical simulations were conducted in this study by analyzing the different channel configurations and a range of outlet contraction ratios. Different degrees of curved constriction channels were designed for comparison with a straight constriction channel. In addition, the effect on pressurization and flow was investigated by adjusting the combustion chamber’s outlet contraction ratio. The research indicated that the total pressure of a curved constriction channel was greater than that of a straight constriction channel. However, when a constriction channel with greater convergence was introduced, the outlet total pressure decreased. In addition, for the same constriction channel, the total pressure at the outlet increased with a decreasing outlet contraction ratio. Under the influence of the contraction effect, the continuous acceleration effect of the gas in the channel was improved, resulting in the critical sonic speed at the outlet. In summary, only a moderately curved constriction channel can achieve a better pressurization effect. When the outlet contraction ratio reached 0.75, the combustors total outlet pressure achieved its maximum, and the downstream continuous acceleration effect was optimal. This study provides a research basis for the pressurization characteristics of rotating detonation engines through numerical calculations.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"112 ","pages":"Article 109764"},"PeriodicalIF":2.6,"publicationDate":"2025-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140610","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

Tooth surface contact temperature of spur-face gear drive in point contact considering heat flow distribution

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2025-01-28 DOI: 10.1016/j.ijheatfluidflow.2025.109759

Lingyun Zhu, Qingfu Guo, Bo Xu, Xiangfeng Gou

Point contact and line contact are two different contacts in gear transmission. The spur-face gear drive (SFGD) is a novel gear transmission characterized by its point contact. Its meshing point trajectories are determined by calculating the tooth surface equations and meshing equations, which are established based on the shaping of the face gear and the laws of point contact during meshing. The meshing characteristics in point contact are analyzed and the load distribution ratio of SFGD is calculated according to Hertzian elastic contact theory and its multi-state meshing characteristics. Time-varying oil film parameters and friction coefficients are obtained based on the Greenwood-Williamson model as rough tooth surfaces are analyzed. A calculation method of tooth surface contact temperature (TSCT) for SFGD with point contact is developed after its tooth surface flash temperature (TSFT) is improved based on Blok flash temperature theory as oil injection lubrication is considered by integrating tribology, heat transfer, and the principles of heat flow distribution in adhered lubricant. It indicates that TSFT and TSCT are resulted in tooth surface roughness, speed, load, and contact position. A finite element model is constructed when the three-dimensional unsteady heat conduction, heat flow and boundary condition are considered to verify the theoretical calculation methods of TSFT, TSCT and bulk temperature (BT). The trend of the simulation is very close to the one of theoretical calculation. TSCT at the mesh-in and mesh-out points are higher than that at other meshing positions. TSFT at the pitch point of pinion equals to 0. TSCT at the alternating meshing position between single-pair and double-pair teeth jump, which is caused by the load variation result in the change in the number of meshing teeth pairs. TSCT can be reduced by optimizing surface roughness and input parameters. It is a theoretical foundation for the thermal behavior analysis under lubricated conditions and a significant reference for design and optimization of point contact gear drives.

{"title":"Tooth surface contact temperature of spur-face gear drive in point contact considering heat flow distribution","authors":"Lingyun Zhu, Qingfu Guo, Bo Xu, Xiangfeng Gou","doi":"10.1016/j.ijheatfluidflow.2025.109759","DOIUrl":"10.1016/j.ijheatfluidflow.2025.109759","url":null,"abstract":"<div><div>Point contact and line contact are two different contacts in gear transmission. The spur-face gear drive (SFGD) is a novel gear transmission characterized by its point contact. Its meshing point trajectories are determined by calculating the tooth surface equations and meshing equations, which are established based on the shaping of the face gear and the laws of point contact during meshing. The meshing characteristics in point contact are analyzed and the load distribution ratio of SFGD is calculated according to Hertzian elastic contact theory and its multi-state meshing characteristics. Time-varying oil film parameters and friction coefficients are obtained based on the Greenwood-Williamson model as rough tooth surfaces are analyzed. A calculation method of tooth surface contact temperature (TSCT) for SFGD with point contact is developed after its tooth surface flash temperature (TSFT) is improved based on Blok flash temperature theory as oil injection lubrication is considered by integrating tribology, heat transfer, and the principles of heat flow distribution in adhered lubricant. It indicates that TSFT and TSCT are resulted in tooth surface roughness, speed, load, and contact position. A finite element model is constructed when the three-dimensional unsteady heat conduction, heat flow and boundary condition are considered to verify the theoretical calculation methods of TSFT, TSCT and bulk temperature (BT). The trend of the simulation is very close to the one of theoretical calculation. TSCT at the mesh-in and mesh-out points are higher than that at other meshing positions. TSFT at the pitch point of pinion equals to 0. TSCT at the alternating meshing position between single-pair and double-pair teeth jump, which is caused by the load variation result in the change in the number of meshing teeth pairs. TSCT can be reduced by optimizing surface roughness and input parameters. It is a theoretical foundation for the thermal behavior analysis under lubricated conditions and a significant reference for design and optimization of point contact gear drives.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"112 ","pages":"Article 109759"},"PeriodicalIF":2.6,"publicationDate":"2025-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140616","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Research on flow and heat transfer characteristics of microchannel heat sinks with fan-shaped cavities and circular ribs

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2025-01-27 DOI: 10.1016/j.ijheatfluidflow.2025.109758

Andong Wu, Qing Cheng, Han Wang

Microchannel heat sinks play a vital role in the heat dissipation of miniaturized and highly integrated electronic devices. In this paper, a novel microchannel heat sinks consisting of fan-shaped cavities and circular ribs (MC-FCR) and the flow and heat transfer characteristics are both studied numerically. With comparation with the traditional smooth straight microchannel (MC), the microchannel with fan-shaped cavities (MC-FC), and the microchannel with circular ribs (MC-CR), the average friction coefficient (f), Nusselt number (Nu) and thermal enhancement efficiency (η) with Reynolds numbers (Re) ranging from 100 to 1000 were mainly studied. The results show that the circular rib structure can increase the degree of turbulence in the microchannel effectively, and the fan-shaped cavity can guide the fluid to form vortices, which bring the average temperature down at least 20 K. In addition, the combination of circular ribs and fan-shaped cavities can improve heat transfer performance while reducing pressure drop, and facilitate the formation of more uniform fluid flow in the channel. Then the relative radius of circular rib (α) and ellipticity (β) are proposed for optimizing the global characteristics of MC-FCR, which results in the thermal enhancement efficiency η for MC-FCR with α = 0.5 and β = 0.5 can achieve 1.431 at Re = 300.

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引用次数: 0

Heat sink optimization with response surface methodology for single phase immersion cooling

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2025-01-27 DOI: 10.1016/j.ijheatfluidflow.2025.109745

Rahim Aytug Ozer

One of the biggest challenges to technological advancements is the inability to efficiently dissipate waste heat from electronic components, which negatively effect performance and reliability. Immersion cooling systems provide an effective alternative for thermal management due to their high cooling capacity, uniform heat distribution and economic advantages. This study focuses on enhancing the thermal efficiency of single-phase immersion cooling systems by optimizing the geometric parameters of a heat sink, a passive cooling method. The innovation of this work lies in the systematic optimization of three key parameters: fin height, channel width and heat flux. These parameters were varied at three levels and an experimental design was developed using response surface methodology (RSM), which involved conducting 15 experiments. The optimal values for maximum thermal performance were determined to be 2.0 mm for channel width, 13.8889 mm for fin height and 45898.98 W/m² for heat flux. The study reveals that the most influential parameters on thermal enhancement are channel width, fin height and heat flux respectively. The results demonstrate significant potential for improving thermal management in electronic cooling systems. Based on the findings, a reliable correlation for the enhancement rate is proposed, offering a practical tool for designing more efficient and sustainable cooling systems. This innovative approach contributes to the development of more effective thermal management solutions, with potential applications in industries such as electronics, power systems, and data centers.

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引用次数: 0

Study on atomization and evaporation characteristics of liquid jets under shock wave action in supersonic flow

IF 2.6 3区工程技术 Q2 ENGINEERING, MECHANICAL

International Journal of Heat and Fluid Flow

Pub Date : 2025-01-25 DOI: 10.1016/j.ijheatfluidflow.2025.109762

Yi Zhang , Ye Tian , Guangming Du

This paper focuses on investigating the impact of incident shocks on the atomization, evaporation, and diffusion characteristics of a liquid jet in supersonic flow. By adjusting the position of the shock wave generator, the interaction between the incident shock wave and the wall can be modified. The gas–liquid two-phase flow process is solved using the Euler-Lagrange method, allowing for the analysis of the atomization, evaporation, and mixing processes of kerosene. Through a thorough examination of the numerical simulation results, the underlying mechanisms by which shock waves affect the breakup and evaporation of kerosene are revealed. The findings indicate that the passage of the airflow through the incident shock wave leads to an increase in temperature and pressure. This, in turn, accelerates the evaporation process of kerosene droplets, resulting in a deeper penetration of kerosene vapor. The penetration depth can be increased by up to 39.7 %. Additionally, the decrease in airflow velocity after the shock and the formation of vortex structures in the flow field, caused by the incident shock, effectively enhance the diffusion and mixing of kerosene. These results provide valuable insights for improving the mixing characteristics of fuel atomization and evaporation, ultimately enhancing the subsequent combustion process.

{"title":"Study on atomization and evaporation characteristics of liquid jets under shock wave action in supersonic flow","authors":"Yi Zhang , Ye Tian , Guangming Du","doi":"10.1016/j.ijheatfluidflow.2025.109762","DOIUrl":"10.1016/j.ijheatfluidflow.2025.109762","url":null,"abstract":"<div><div>This paper focuses on investigating the impact of incident shocks on the atomization, evaporation, and diffusion characteristics of a liquid jet in supersonic flow. By adjusting the position of the shock wave generator, the interaction between the incident shock wave and the wall can be modified. The gas–liquid two-phase flow process is solved using the Euler-Lagrange method, allowing for the analysis of the atomization, evaporation, and mixing processes of kerosene. Through a thorough examination of the numerical simulation results, the underlying mechanisms by which shock waves affect the breakup and evaporation of kerosene are revealed. The findings indicate that the passage of the airflow through the incident shock wave leads to an increase in temperature and pressure. This, in turn, accelerates the evaporation process of kerosene droplets, resulting in a deeper penetration of kerosene vapor. The penetration depth can be increased by up to 39.7 %. Additionally, the decrease in airflow velocity after the shock and the formation of vortex structures in the flow field, caused by the incident shock, effectively enhance the diffusion and mixing of kerosene. These results provide valuable insights for improving the mixing characteristics of fuel atomization and evaporation, ultimately enhancing the subsequent combustion process.</div></div>","PeriodicalId":335,"journal":{"name":"International Journal of Heat and Fluid Flow","volume":"112 ","pages":"Article 109762"},"PeriodicalIF":2.6,"publicationDate":"2025-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140163","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