Pub Date : 2024-09-17DOI: 10.1177/09576509241282747
Malinee Sriariyanun, Elaiyarasan U, Sakthivel R, Baranitharan P, Atthasit Tawai, Arunkumar T
Biofuel is an alternative fuel for diesel engines which is necessary to reduce exhaust emissions and helps to balance the depletion of fossil fuels. This study details the synthesis of bio-diesel and bio-oil from stone apple seeds ( Aegle marmelos) through transesterification, direct oxygenate additive, and pyrolysis processes. The diesel engine is powered by the resulting stone apple methyl ester bio-diesel/diesel and bio-oil/diesel mixtures. In a test engine rig, the effectiveness and emission uniqueness of test fuel mixes were examined at various engine loads (EL = 3 kg–12 kg) and compression ratios (CR = 16–17.5) while maintaining a steady speed of 1500 r/min. Furthermore, engine performance and emissions for bio-diesel and bio-oil are measured and compared. The oxides of nitrogen (NOx) emission by bio-diesel and bio-oil opus were higher than neat diesel (FD). Also, carbon monoxide (CO) and hydrocarbon (HC) emissions were measured to be lower. The improvements of BTE by 4.87% and decrement of CO by 18.8%, HC by 13.26% were observed with the trans-esterified bio-diesel/diesel opus compared to diesel at a higher CR and rated load conditions. The engine analysis responses revealed that the FBD blend showed enhanced performance and lower emissions except NOx compared to diesel fuel. Hence, trans-esterified bio-diesel is a greater diesel alternative than FBDE and FBO.
{"title":"Studies on fuels and engine attributes powered by bio-diesel and bio-oil derived from stone apple seed (Aegle marmelos) for bioenergy","authors":"Malinee Sriariyanun, Elaiyarasan U, Sakthivel R, Baranitharan P, Atthasit Tawai, Arunkumar T","doi":"10.1177/09576509241282747","DOIUrl":"https://doi.org/10.1177/09576509241282747","url":null,"abstract":"Biofuel is an alternative fuel for diesel engines which is necessary to reduce exhaust emissions and helps to balance the depletion of fossil fuels. This study details the synthesis of bio-diesel and bio-oil from stone apple seeds ( Aegle marmelos) through transesterification, direct oxygenate additive, and pyrolysis processes. The diesel engine is powered by the resulting stone apple methyl ester bio-diesel/diesel and bio-oil/diesel mixtures. In a test engine rig, the effectiveness and emission uniqueness of test fuel mixes were examined at various engine loads (EL = 3 kg–12 kg) and compression ratios (CR = 16–17.5) while maintaining a steady speed of 1500 r/min. Furthermore, engine performance and emissions for bio-diesel and bio-oil are measured and compared. The oxides of nitrogen (NOx) emission by bio-diesel and bio-oil opus were higher than neat diesel (FD). Also, carbon monoxide (CO) and hydrocarbon (HC) emissions were measured to be lower. The improvements of BTE by 4.87% and decrement of CO by 18.8%, HC by 13.26% were observed with the trans-esterified bio-diesel/diesel opus compared to diesel at a higher CR and rated load conditions. The engine analysis responses revealed that the FBD blend showed enhanced performance and lower emissions except NOx compared to diesel fuel. Hence, trans-esterified bio-diesel is a greater diesel alternative than FBDE and FBO.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142261554","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-09-14DOI: 10.1177/09576509241283129
Mario Carta, Shahrokh Shahpar, Tiziano Ghisu
In the field of design and optimization of sophisticated geometries such as film-cooled turbine blades of modern jet engines, Computational Fluid Dynamics (CFD) simulation is commonly employed. As the pursuit for higher turbine entry temperatures intensifies, it becomes crucial for computational analyses to offer accurate predictions of metal temperatures and heat transfer coefficients on these critical components. This study investigates the impact of key physical factors that characterize the operation of these components on the accuracy of the computational model. In particular, the effects of including the exchange of thermal energy between the fluid and solid domains, as well as modelling the unsteady interaction between the rotor and stator are studied. The research focuses on a fully featured one-and-a-half stage high-pressure turbine of a commercial jet engine, utilizing proprietary software for conducting 3D Reynolds-Averaged Navier-Stokes flow simulations. To model the fluid-solid thermal interaction, steady-state Conjugate Heat Transfer (CHT) simulations are performed. The CHT results are then compared with experimental data obtained from a thermal paint test, achieving good levels of agreement. Additionally, phase-lag simulations are executed under adiabatic-wall conditions to evaluate the influence of stator-rotor interaction on near-wall gas temperatures. This work shows that, by modelling the periodic unsteadiness at the stator-rotor interface with a phase-lag technique, the maximum near-wall gas temperature prediction is significantly increased, sometimes more than 100K, with respect to the steady-state model one. Findings from this work also suggest that simplified “strip” source terms used to model the presence of film cooling hole rows on the surface of a blade can be used with satisfactory accuracy only for nominal conditions. The mass flows delivered by each source strip should not be linearly scaled based on mainstream quantities for use in different conditions, but they should be recalculated from scratch for the new conditions.
{"title":"Analysis of the aerothermal performance of modern commercial high-pressure turbine rotors using different levels of fidelity","authors":"Mario Carta, Shahrokh Shahpar, Tiziano Ghisu","doi":"10.1177/09576509241283129","DOIUrl":"https://doi.org/10.1177/09576509241283129","url":null,"abstract":"In the field of design and optimization of sophisticated geometries such as film-cooled turbine blades of modern jet engines, Computational Fluid Dynamics (CFD) simulation is commonly employed. As the pursuit for higher turbine entry temperatures intensifies, it becomes crucial for computational analyses to offer accurate predictions of metal temperatures and heat transfer coefficients on these critical components. This study investigates the impact of key physical factors that characterize the operation of these components on the accuracy of the computational model. In particular, the effects of including the exchange of thermal energy between the fluid and solid domains, as well as modelling the unsteady interaction between the rotor and stator are studied. The research focuses on a fully featured one-and-a-half stage high-pressure turbine of a commercial jet engine, utilizing proprietary software for conducting 3D Reynolds-Averaged Navier-Stokes flow simulations. To model the fluid-solid thermal interaction, steady-state Conjugate Heat Transfer (CHT) simulations are performed. The CHT results are then compared with experimental data obtained from a thermal paint test, achieving good levels of agreement. Additionally, phase-lag simulations are executed under adiabatic-wall conditions to evaluate the influence of stator-rotor interaction on near-wall gas temperatures. This work shows that, by modelling the periodic unsteadiness at the stator-rotor interface with a phase-lag technique, the maximum near-wall gas temperature prediction is significantly increased, sometimes more than 100K, with respect to the steady-state model one. Findings from this work also suggest that simplified “strip” source terms used to model the presence of film cooling hole rows on the surface of a blade can be used with satisfactory accuracy only for nominal conditions. The mass flows delivered by each source strip should not be linearly scaled based on mainstream quantities for use in different conditions, but they should be recalculated from scratch for the new conditions.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142261555","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-09-11DOI: 10.1177/09576509241283612
Huan Li, Shuguang Zuo, Siyue Chen
The integrated two-stage electric centrifugal compressors are most widely used in the present fuel cell vehicles. Air compressors influence the efficiency of fuel cell systems significantly, so it is crucial to improve the energy efficiency of centrifugal compressors. However, there is a lack of centrifugal compressor performance models that can reflect the thermodynamic characteristics of two-stage compression system, which is the main focus of this paper. In this paper, an analytical model of two-stage centrifugal compressor performance considering the thermodynamic characteristics of two-stage compression was first derived and experimentally validated. The single-stage centrifugal compressor model (SSCCM) can be treated as a lumped parameter model of the two-stage centrifugal compressor to predict the compressor performance. Therefore, the SSCCM and the two-stage centrifugal compressor model (TSCCM) were compared. The results show that the TSCCM is more accurate and robust. Furthermore, a novel compressor structure equipped with an intercooler in the inter-stage piping was proposed to improve the energy efficiency of the centrifugal compressor. Based on this novel structure, the TSCCM was modified. Finally, a quantitative analysis was performed to study the effect of an inter-stage intercooler on compressor efficiency. Compared to the original compressor without the inter-stage intercooler, the efficiency improvement by the inter-stage intercooler can be in the range of 3.29–3.97%, with power savings of 0.332–0.635 kW. The study can be used to support engineers and researchers in fast identifying effective solutions in terms of design for the next generation of centrifugal compressors.
{"title":"Analytical modeling and performance improvement of an electric two-stage centrifugal compressor for fuel cell vehicles","authors":"Huan Li, Shuguang Zuo, Siyue Chen","doi":"10.1177/09576509241283612","DOIUrl":"https://doi.org/10.1177/09576509241283612","url":null,"abstract":"The integrated two-stage electric centrifugal compressors are most widely used in the present fuel cell vehicles. Air compressors influence the efficiency of fuel cell systems significantly, so it is crucial to improve the energy efficiency of centrifugal compressors. However, there is a lack of centrifugal compressor performance models that can reflect the thermodynamic characteristics of two-stage compression system, which is the main focus of this paper. In this paper, an analytical model of two-stage centrifugal compressor performance considering the thermodynamic characteristics of two-stage compression was first derived and experimentally validated. The single-stage centrifugal compressor model (SSCCM) can be treated as a lumped parameter model of the two-stage centrifugal compressor to predict the compressor performance. Therefore, the SSCCM and the two-stage centrifugal compressor model (TSCCM) were compared. The results show that the TSCCM is more accurate and robust. Furthermore, a novel compressor structure equipped with an intercooler in the inter-stage piping was proposed to improve the energy efficiency of the centrifugal compressor. Based on this novel structure, the TSCCM was modified. Finally, a quantitative analysis was performed to study the effect of an inter-stage intercooler on compressor efficiency. Compared to the original compressor without the inter-stage intercooler, the efficiency improvement by the inter-stage intercooler can be in the range of 3.29–3.97%, with power savings of 0.332–0.635 kW. The study can be used to support engineers and researchers in fast identifying effective solutions in terms of design for the next generation of centrifugal compressors.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142201272","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-08-27DOI: 10.1177/09576509241277578
Xin Yan, Haibo Wang, Kun He
The periodic-cell model was proposed to simulate the successive contacts between the labyrinth fin and multiple honeycomb cells. With the experimental data, the finite-element-analysis (FEA) method with the periodic-cell model was validated. The effects of incursion parameters (i.e. incursion depth, incursion rate and sliding velocity) on the contact force, frictional temperature, material loss, and worn geometry of the honeycomb seal during the incursion process were studied. With the predicted worn geometry, the sealing performance degradation in the honeycomb seal was analyzed. The results showed that the proposed periodic-cell model has an excellent accuracy in predicting the wear behavior of honeycomb seal in rubbing events. The contact force between the honeycomb liner and labyrinth fin is pronounced especially at low sliding velocity and high incursion rate conditions, which increases the possibility of wear damage in the rotor part. At low sliding velocity and low incursion rate conditions, the frictional heat transferring to rotor part is increased, which increases the thermal stress near the contact region of the rotor part. As the clearance gap of honeycomb seal increases from 0.6 mm to 0.9 mm in the rubbing event, the leakage rate is increased by about 12%, and the carry-over effects downstream of the worn cells are increased.
{"title":"Investigations into rubbing wear behavior of honeycomb land against labyrinth fin with periodic-cell model","authors":"Xin Yan, Haibo Wang, Kun He","doi":"10.1177/09576509241277578","DOIUrl":"https://doi.org/10.1177/09576509241277578","url":null,"abstract":"The periodic-cell model was proposed to simulate the successive contacts between the labyrinth fin and multiple honeycomb cells. With the experimental data, the finite-element-analysis (FEA) method with the periodic-cell model was validated. The effects of incursion parameters (i.e. incursion depth, incursion rate and sliding velocity) on the contact force, frictional temperature, material loss, and worn geometry of the honeycomb seal during the incursion process were studied. With the predicted worn geometry, the sealing performance degradation in the honeycomb seal was analyzed. The results showed that the proposed periodic-cell model has an excellent accuracy in predicting the wear behavior of honeycomb seal in rubbing events. The contact force between the honeycomb liner and labyrinth fin is pronounced especially at low sliding velocity and high incursion rate conditions, which increases the possibility of wear damage in the rotor part. At low sliding velocity and low incursion rate conditions, the frictional heat transferring to rotor part is increased, which increases the thermal stress near the contact region of the rotor part. As the clearance gap of honeycomb seal increases from 0.6 mm to 0.9 mm in the rubbing event, the leakage rate is increased by about 12%, and the carry-over effects downstream of the worn cells are increased.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142201273","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-08-26DOI: 10.1177/09576509241275778
Awais Junejo, Sergio Chapela, Jacobo Porteiro, Yasir M. Al-Abdeli
Air staging in solid fuel combustion features widely in small scale domestic boilers to large scale moving grate combustors. Whilst the effects of air staging on the combustion characteristics of these systems are generally known, there is very little insight available into the role of secondary air on the flow and temperature field in the freeboard of batch-type fixed bed biomass combustors. Three-dimensional gas phase simulations using the Transition 𝑘kl-𝜔 and Finite Rate/Eddy Dissipation models were validated against freeboard temperatures and emissions (CO2 and O2) measured on the same set-up. Results show that secondary air at Qs/Qt ≥0.25 induces two recirculation zones, upstream and downstream of its injection point with maximum freeboard temperatures generally observed around these recirculation zones, if Qs/Qt drops to 0.12-0.18 only an upstream recirculation zone is observed until it diminishes by Qs/Qt = 0.06. However, there is a trade-off caused by what appears to be a cooling effect if Qs/Qt is increased between 0.25 and 0.71. Modelling results show that in reacting cases, unlike non-reacting modelling on the same geometry, the strength of the secondary air induced upstream recirculation zone appears significantly stronger.
{"title":"Secondary air induced flow structures and their interplay with the temperature field in fixed bed combustors","authors":"Awais Junejo, Sergio Chapela, Jacobo Porteiro, Yasir M. Al-Abdeli","doi":"10.1177/09576509241275778","DOIUrl":"https://doi.org/10.1177/09576509241275778","url":null,"abstract":"Air staging in solid fuel combustion features widely in small scale domestic boilers to large scale moving grate combustors. Whilst the effects of air staging on the combustion characteristics of these systems are generally known, there is very little insight available into the role of secondary air on the flow and temperature field in the freeboard of batch-type fixed bed biomass combustors. Three-dimensional gas phase simulations using the Transition 𝑘kl-𝜔 and Finite Rate/Eddy Dissipation models were validated against freeboard temperatures and emissions (CO<jats:sub>2</jats:sub> and O<jats:sub>2</jats:sub>) measured on the same set-up. Results show that secondary air at Q<jats:sub>s</jats:sub>/Q<jats:sub>t</jats:sub> ≥0.25 induces two recirculation zones, upstream and downstream of its injection point with maximum freeboard temperatures generally observed around these recirculation zones, if Q<jats:sub>s</jats:sub>/Q<jats:sub>t</jats:sub> drops to 0.12-0.18 only an upstream recirculation zone is observed until it diminishes by Q<jats:sub>s</jats:sub>/Q<jats:sub>t</jats:sub> = 0.06. However, there is a trade-off caused by what appears to be a cooling effect if Q<jats:sub>s</jats:sub>/Q<jats:sub>t</jats:sub> is increased between 0.25 and 0.71. Modelling results show that in reacting cases, unlike non-reacting modelling on the same geometry, the strength of the secondary air induced upstream recirculation zone appears significantly stronger.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2024-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142201205","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-08-22DOI: 10.1177/09576509241277241
Chang’an Wang, Yuanmao Chen, Maoyun Luo, Lin Zhao, Pengbo Zhao, Defu Che
Due to the deep stage of oxygen, the pulverized coal cannot be burned completely in the primary combustion zone, resulting in a high content of residual carbon. The residual carbon in ash has a potential effect on the melting characteristics of ash, while there is a lack of specific research on the effects of residual carbon on ash fusion characteristics of high-alkali coals. In the present study, synthetic ash was blended with residual carbon to study the impacts of residual carbon content, graphitization level of the carbon, and atmospheric condition on ash fusion characteristics. Thermogravimetric analyzers and ash melting point testers were used to study the thermogravimetric behavior of ash and the characteristic temperatures of ash fusion, and then analyze the changes in the mineral composition and micromorphology of slag using X-ray diffractometers and scanning electron microscopy. The experimental results reveal that the change in residual char content exerts a minor influence on the type of crystalline minerals within the ash, while it affects the relative content of various minerals. The softening temperature of the ash blended with activated carbon and graphite are 1234°C and 1242°C, respectively. The blending of activated carbon greatly promotes the generation of gehlenite (Ca2Al2SiO7, 1593°C) and inhibits the generation of merwinite (Ca3MgSi2O8, 1550°C), increasing the ash melting temperature. The ash fusion characteristic temperatures of the pure synthetic ash decrease with the enhancement of the reductive atmosphere. However, the ash fusion characteristic temperatures of the ash blended with carbon in strong reducing atmosphere are increased compared to those in weak reducing atmosphere because part of the carbon acts as a skeleton or reacts to form a carbon-silicon compound. The present study can offer improved knowledge to provide fundamental support for the combustion and utilization of high-alkali Zhundong coal under deep oxygen-staged conditions.
由于氧气阶段较深，煤粉在一次燃烧区不能完全燃烧，导致残炭含量较高。灰渣中的残炭对灰渣的熔融特性有潜在的影响，而残炭对高碱煤灰渣熔融特性的影响还缺乏专门的研究。本研究将合成灰与残炭混合，研究残炭含量、残炭石墨化程度和大气条件对灰熔融特性的影响。使用热重分析仪和灰熔点测试仪研究了灰的热重行为和灰熔融的特征温度，然后使用 X 射线衍射仪和扫描电子显微镜分析了矿渣矿物成分和微观形态的变化。实验结果表明，残炭含量的变化对灰渣中结晶矿物种类的影响较小，而对各种矿物相对含量的影响较大。掺入活性炭和石墨的灰的软化温度分别为 1234°C 和 1242°C。活性炭的掺入极大地促进了gehlenite（Ca2Al2SiO7，1593°C）的生成，抑制了merwinite（Ca3MgSi2O8，1550°C）的生成，从而提高了灰熔化温度。纯合成灰的灰熔融特征温度随着还原气氛的增强而降低。然而，与弱还原气氛相比，在强还原气氛中掺入碳的灰熔融特性温度会升高，这是因为部分碳起到了骨架的作用，或发生反应形成了碳硅化合物。本研究可为高碱准东煤在深氧阶段条件下的燃烧和利用提供基础支持。
{"title":"Experimental study on the effects of residual carbon on ash fusion characteristics of high-alkali Zhundong coal under deep oxygen-staged condition","authors":"Chang’an Wang, Yuanmao Chen, Maoyun Luo, Lin Zhao, Pengbo Zhao, Defu Che","doi":"10.1177/09576509241277241","DOIUrl":"https://doi.org/10.1177/09576509241277241","url":null,"abstract":"Due to the deep stage of oxygen, the pulverized coal cannot be burned completely in the primary combustion zone, resulting in a high content of residual carbon. The residual carbon in ash has a potential effect on the melting characteristics of ash, while there is a lack of specific research on the effects of residual carbon on ash fusion characteristics of high-alkali coals. In the present study, synthetic ash was blended with residual carbon to study the impacts of residual carbon content, graphitization level of the carbon, and atmospheric condition on ash fusion characteristics. Thermogravimetric analyzers and ash melting point testers were used to study the thermogravimetric behavior of ash and the characteristic temperatures of ash fusion, and then analyze the changes in the mineral composition and micromorphology of slag using X-ray diffractometers and scanning electron microscopy. The experimental results reveal that the change in residual char content exerts a minor influence on the type of crystalline minerals within the ash, while it affects the relative content of various minerals. The softening temperature of the ash blended with activated carbon and graphite are 1234°C and 1242°C, respectively. The blending of activated carbon greatly promotes the generation of gehlenite (Ca2Al2SiO7, 1593°C) and inhibits the generation of merwinite (Ca3MgSi2O8, 1550°C), increasing the ash melting temperature. The ash fusion characteristic temperatures of the pure synthetic ash decrease with the enhancement of the reductive atmosphere. However, the ash fusion characteristic temperatures of the ash blended with carbon in strong reducing atmosphere are increased compared to those in weak reducing atmosphere because part of the carbon acts as a skeleton or reacts to form a carbon-silicon compound. The present study can offer improved knowledge to provide fundamental support for the combustion and utilization of high-alkali Zhundong coal under deep oxygen-staged conditions.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142201206","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-08-10DOI: 10.1177/09576509241271873
Chuan Lin, Xiaojun Guo, Jiaman Luo
Regarding the relationship between wind power generation and meteorological factors, previous studies tend to focus on the correlation between them, but correlation does not imply causation. In this context, we propose to use a combination of time-lagged convergent cross mapping (CCM) and graph network theory to investigate the causal relationship between wind power generation and meteorological factors. The effectiveness of time-lagged CCM is demonstrated by applying it to three scenarios of strong linear correlation, weak linear correlation and no linear correlation, respectively, and comparing it with Standard CCM and time-lagged Pearson correlation coefficient (PCC). Time-lagged CCM can accurately identify the causal relationship between wind power generation and meteorological factors and quantitatively assess the variables' causal intensity. Further, combined with graph network theory, we constructed a causal pattern diagram. From it, we can find that the causal relationship and intensity between wind power generation and meteorological factors also change dynamically throughout the year, following a specific temporal causal chain law. This finding is conducive to establishing a more accurate wind power prediction model, especially in the model’s feature selection and feature relationship analysis.
{"title":"Causality analysis of meteorologically sensitive in offshore wind power generation based on the time-lagged convergent cross mapping","authors":"Chuan Lin, Xiaojun Guo, Jiaman Luo","doi":"10.1177/09576509241271873","DOIUrl":"https://doi.org/10.1177/09576509241271873","url":null,"abstract":"Regarding the relationship between wind power generation and meteorological factors, previous studies tend to focus on the correlation between them, but correlation does not imply causation. In this context, we propose to use a combination of time-lagged convergent cross mapping (CCM) and graph network theory to investigate the causal relationship between wind power generation and meteorological factors. The effectiveness of time-lagged CCM is demonstrated by applying it to three scenarios of strong linear correlation, weak linear correlation and no linear correlation, respectively, and comparing it with Standard CCM and time-lagged Pearson correlation coefficient (PCC). Time-lagged CCM can accurately identify the causal relationship between wind power generation and meteorological factors and quantitatively assess the variables' causal intensity. Further, combined with graph network theory, we constructed a causal pattern diagram. From it, we can find that the causal relationship and intensity between wind power generation and meteorological factors also change dynamically throughout the year, following a specific temporal causal chain law. This finding is conducive to establishing a more accurate wind power prediction model, especially in the model’s feature selection and feature relationship analysis.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2024-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141920341","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-08-09DOI: 10.1177/09576509241272832
Qingfeng Cong, Guoqiang Cheng, Kaiyuan Zhang, Zhigang Li, Jun Li, Xianglin Kong
Rim seals at the periphery of cavities can prevent high-temperature gas from ingesting into the disk cavity. The sealing performance of rim seals and ingestion mechanism for the counter-rotating cavity of a 1 + 1/2 counter-rotating turbine are studied by solving the three-dimensional unsteady Reynolds-averaged Navier–Stokes (URANS) equations via shear stress transfer (SST) turbulence model. The accuracy of the numerical method is verified by comparing with the experimental data. The sealing effectiveness in cavities and flow field in rim seal clearance of three rim seals are analyzed, and the impact factor of unsteady flow pattern is explored. The results show that, the sealing effectiveness [Formula: see text] of the disk cavity of LPR lipped rim seal is the highest within the full sealant flow rate [Formula: see text] range. When the non-dimensional sealant flow rate [Formula: see text] is 0.034, the sealing effectiveness [Formula: see text] at the high-pressure rotor (HPR) disk at r/b = 0.96 for LPR lipped rim seal is 10.96% higher than that of the axial seal which is the smallest; the sealing effectiveness [Formula: see text] on the low-pressure rotor (LPR) disk at r/b = 0.96 is 18.99% higher than that of HPR lipped rim seal. A clockwise Kelvin-Helmholtz (K-H) unstable vortex within the rim seal clearance is formed due to the large radial gradient of circumferential velocity. The existence of unstable vortices significantly changes the flow pattern of ingress and egress, which can block the axial clearance and reduce the amount of gas ingestion by reducing discharge coefficients. Affected by the supersonic flow inside HPR blades, shock waves occurred near the trailing edge of the HPR blades, including inner-extending shock (IES) and outer-extending shock (OES) and the non-axisymmetry of circumferential pressure coefficient [Formula: see text] at the trailing edge significantly increases. The K-H unstable vortex and non-axisymmetric circumferential distribution of the pressure coefficient [Formula: see text] jointly affect on the ingress and egress process. When the radial inward flow of the vortex is downstream of the high and low circumferential pressure, gas ingestion is enhanced and weakened, respectively.
{"title":"Numerical investigations on the sealing performance and ingestion mechanism of rim seals for a 1+1/2 counter-rotating turbine","authors":"Qingfeng Cong, Guoqiang Cheng, Kaiyuan Zhang, Zhigang Li, Jun Li, Xianglin Kong","doi":"10.1177/09576509241272832","DOIUrl":"https://doi.org/10.1177/09576509241272832","url":null,"abstract":"Rim seals at the periphery of cavities can prevent high-temperature gas from ingesting into the disk cavity. The sealing performance of rim seals and ingestion mechanism for the counter-rotating cavity of a 1 + 1/2 counter-rotating turbine are studied by solving the three-dimensional unsteady Reynolds-averaged Navier–Stokes (URANS) equations via shear stress transfer (SST) turbulence model. The accuracy of the numerical method is verified by comparing with the experimental data. The sealing effectiveness in cavities and flow field in rim seal clearance of three rim seals are analyzed, and the impact factor of unsteady flow pattern is explored. The results show that, the sealing effectiveness [Formula: see text] of the disk cavity of LPR lipped rim seal is the highest within the full sealant flow rate [Formula: see text] range. When the non-dimensional sealant flow rate [Formula: see text] is 0.034, the sealing effectiveness [Formula: see text] at the high-pressure rotor (HPR) disk at r/b = 0.96 for LPR lipped rim seal is 10.96% higher than that of the axial seal which is the smallest; the sealing effectiveness [Formula: see text] on the low-pressure rotor (LPR) disk at r/b = 0.96 is 18.99% higher than that of HPR lipped rim seal. A clockwise Kelvin-Helmholtz (K-H) unstable vortex within the rim seal clearance is formed due to the large radial gradient of circumferential velocity. The existence of unstable vortices significantly changes the flow pattern of ingress and egress, which can block the axial clearance and reduce the amount of gas ingestion by reducing discharge coefficients. Affected by the supersonic flow inside HPR blades, shock waves occurred near the trailing edge of the HPR blades, including inner-extending shock (IES) and outer-extending shock (OES) and the non-axisymmetry of circumferential pressure coefficient [Formula: see text] at the trailing edge significantly increases. The K-H unstable vortex and non-axisymmetric circumferential distribution of the pressure coefficient [Formula: see text] jointly affect on the ingress and egress process. When the radial inward flow of the vortex is downstream of the high and low circumferential pressure, gas ingestion is enhanced and weakened, respectively.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2024-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141922379","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-08-08DOI: 10.1177/09576509241272804
Nitin Kumar Jhankal, Arun Kumar
The present study emphasizes the experimental investigations of pressure fluctuations characteristics of the steady flow behavior in a low-head Francis turbine model operating under various load conditions. The experimental study was conducted on a scaled model of the Francis turbine with a runner diameter of 0.31847 m with a head of 17.66 m and operated at a speed of 950 rpm. The pressure fluctuations ranged their operating points from 70% during part load, 100% at the best efficiency point, to 110% under overload conditions. Pressure field measurements were conducted using miniature-type pressure sensors. Eight sensors were strategically placed at various locations, ranging from the spiral casing inlet to the draft tube. The outcomes facilitated identifying the sources of pressure fluctuations. Substantial pressure oscillation occurs on the model runner, vaneless space, and draft tube cone. The rotating vortex rope was formulated during the part load operation. The results show that the fundamental frequency of pressure fluctuations was 0.375 times the rotational runner frequency and strong pressure fluctuations were observed during part load operation.
{"title":"Experimental investigations of pressure fluctuations in low-head francis turbine model","authors":"Nitin Kumar Jhankal, Arun Kumar","doi":"10.1177/09576509241272804","DOIUrl":"https://doi.org/10.1177/09576509241272804","url":null,"abstract":"The present study emphasizes the experimental investigations of pressure fluctuations characteristics of the steady flow behavior in a low-head Francis turbine model operating under various load conditions. The experimental study was conducted on a scaled model of the Francis turbine with a runner diameter of 0.31847 m with a head of 17.66 m and operated at a speed of 950 rpm. The pressure fluctuations ranged their operating points from 70% during part load, 100% at the best efficiency point, to 110% under overload conditions. Pressure field measurements were conducted using miniature-type pressure sensors. Eight sensors were strategically placed at various locations, ranging from the spiral casing inlet to the draft tube. The outcomes facilitated identifying the sources of pressure fluctuations. Substantial pressure oscillation occurs on the model runner, vaneless space, and draft tube cone. The rotating vortex rope was formulated during the part load operation. The results show that the fundamental frequency of pressure fluctuations was 0.375 times the rotational runner frequency and strong pressure fluctuations were observed during part load operation.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141925534","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The volute-free centrifugal fans in ventilation applications are used to exhaust a large amount of air under the effect of the head loss in the ventilation pipeline system, thus, a high static pressure rise at a large flow rate of the fans is anticipated. The shroud of the conventional volute-free centrifugal fans has an axisymmetric geometry, that is, the height of the fan outlet is constant over the whole circumference. Considering the non-uniform flow in the blade passages, the shroud of a wavy geometry might help in improving the static pressure rise and efficiency of the fans at a large flow rate condition. In this work, we performed a numerical investigation on the internal flow of a volute-free centrifugal fan with a wavy shroud. The effect of the geometry of the wavy shroud, as quantified by the maximum height and profile, on the aerodynamic performance of the fan is explored, and the flow physics leading to the performance improvement are demonstrated through a detailed analysis of the patterns of the internal flow. The numerical results showed that compared with the baseline fan with an axisymmetric shroud, the fan with a wavy shroud could substantially improve the static pressure rise and efficiency at the large flow rate. The wavy shroud regulates the near-wall flow especially at the fan outlet; the fluctuation of the radial velocity, secondary flow, and reversed flow is greatly weakened, producing a uniform flow at the fan outlet. The fluctuation of the static pressure in the blade passages and on the shroud side of the fan outlet greatly decreases. Further analysis of the acoustic power level field indicates that the wavy shroud increases the acoustic power at the fan inlet but does not have a notable influence on that near the outlet.
{"title":"Improvement of aerodynamic performance of a volute-free centrifugal fan at a large flow rate using a wavy shroud","authors":"Hengjun Qin, Haijiang He, Ping Luo, Zhenli Zhang, Zhengdao Wang, Hui Yang, Yikun Wei, Wei Zhang","doi":"10.1177/09576509241272863","DOIUrl":"https://doi.org/10.1177/09576509241272863","url":null,"abstract":"The volute-free centrifugal fans in ventilation applications are used to exhaust a large amount of air under the effect of the head loss in the ventilation pipeline system, thus, a high static pressure rise at a large flow rate of the fans is anticipated. The shroud of the conventional volute-free centrifugal fans has an axisymmetric geometry, that is, the height of the fan outlet is constant over the whole circumference. Considering the non-uniform flow in the blade passages, the shroud of a wavy geometry might help in improving the static pressure rise and efficiency of the fans at a large flow rate condition. In this work, we performed a numerical investigation on the internal flow of a volute-free centrifugal fan with a wavy shroud. The effect of the geometry of the wavy shroud, as quantified by the maximum height and profile, on the aerodynamic performance of the fan is explored, and the flow physics leading to the performance improvement are demonstrated through a detailed analysis of the patterns of the internal flow. The numerical results showed that compared with the baseline fan with an axisymmetric shroud, the fan with a wavy shroud could substantially improve the static pressure rise and efficiency at the large flow rate. The wavy shroud regulates the near-wall flow especially at the fan outlet; the fluctuation of the radial velocity, secondary flow, and reversed flow is greatly weakened, producing a uniform flow at the fan outlet. The fluctuation of the static pressure in the blade passages and on the shroud side of the fan outlet greatly decreases. Further analysis of the acoustic power level field indicates that the wavy shroud increases the acoustic power at the fan inlet but does not have a notable influence on that near the outlet.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141969294","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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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