Pub Date : 2023-11-24DOI: 10.1177/09576509231218043
Navam Shrivastava, A. Rai, Ali Abbas, Yexiang Xiao
High-head hydropower plants deploy Pelton turbines to harness energy; however, turbine components face severe abrasive erosion due to suspended sediments. The erosion of the Pelton injector leads to the degradation of the jet quality, reducing the turbine efficiency considerably. Recently, the erosion of an internal servomotor design of the injector has been studied numerically; however, the cavitation-erosion synergy was not explored. This study serves as the extension of the literature with an analysis of the hydro-abrasive erosion and inception of cavitation in an injector with an external servomotor of a high-head hydropower plant (HPP). A Eulerian-Lagrangian approach is used to study the effects of sediment properties and flow parameters on hydro-abrasive erosion; whereas, the Schnerr-Sauer model is used to analyze the inception of cavitation. Interestingly, an increase in particle size from 40 microns to 200 microns resulted in a 95.7% reduction in needle erosion; but, led to a two-fold increase in nozzle erosion. For an increase in the plant head from 200 m to 820 m, the increase in erosion rate of the nozzle and the needle is 4.36 and 1.4 times, respectively. Moreover, the possibility of cavitation in the Pelton injector also increases with an increase in the head of the HPP leading the injector to higher susceptibility to the synergic effect of cavitation and hydro-abrasive erosion. This study attempts to assist the hydropower development in high-head regions with a risk of high sediment flow and manage the existing plants efficiently.
{"title":"Analysis of hydro-abrasive erosion in a high-head Pelton turbine injector using a Eulerian-Lagrangian approach","authors":"Navam Shrivastava, A. Rai, Ali Abbas, Yexiang Xiao","doi":"10.1177/09576509231218043","DOIUrl":"https://doi.org/10.1177/09576509231218043","url":null,"abstract":"High-head hydropower plants deploy Pelton turbines to harness energy; however, turbine components face severe abrasive erosion due to suspended sediments. The erosion of the Pelton injector leads to the degradation of the jet quality, reducing the turbine efficiency considerably. Recently, the erosion of an internal servomotor design of the injector has been studied numerically; however, the cavitation-erosion synergy was not explored. This study serves as the extension of the literature with an analysis of the hydro-abrasive erosion and inception of cavitation in an injector with an external servomotor of a high-head hydropower plant (HPP). A Eulerian-Lagrangian approach is used to study the effects of sediment properties and flow parameters on hydro-abrasive erosion; whereas, the Schnerr-Sauer model is used to analyze the inception of cavitation. Interestingly, an increase in particle size from 40 microns to 200 microns resulted in a 95.7% reduction in needle erosion; but, led to a two-fold increase in nozzle erosion. For an increase in the plant head from 200 m to 820 m, the increase in erosion rate of the nozzle and the needle is 4.36 and 1.4 times, respectively. Moreover, the possibility of cavitation in the Pelton injector also increases with an increase in the head of the HPP leading the injector to higher susceptibility to the synergic effect of cavitation and hydro-abrasive erosion. This study attempts to assist the hydropower development in high-head regions with a risk of high sediment flow and manage the existing plants efficiently.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":"158 ","pages":""},"PeriodicalIF":1.7,"publicationDate":"2023-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139240759","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 : 2023-11-24DOI: 10.1177/09576509231219339
Q. Hassan, Sameer Algburi, A. Z. Sameen, H. M. Salman
The global pivot towards sustainable energy solutions necessitates a closer examination of green hydrogen production using renewable energy sources. This study aimed to assess the feasibility and efficiency of green hydrogen production on an industrial scale using solar and wind energy in Diyala city, Iraq. Experimental weather data, including solar irradiance, ambient temperature, and wind speed, were meticulously collected throughout 2022. The analysis indicated that, for wind energy, the optimum electrolyser capacity that matched a 1.5 MW wind turbine achieved a hydrogen production of 11,963 kg/year, with associated costs of $8.87/kg. In contrast, when focusing on solar energy, the ideal electrolyser capacity harmonizing with a 2 MW solar photovoltaic generated a notably higher hydrogen output of 94,432 kg/year at a more competitive cost of $6.33/kg. These findings underscore the potential economic advantages of solar-based green hydrogen production over wind-based methods in Diyala city. Furthermore, the significant difference in hydrogen production yields between the two methods emphasizes the need to optimize renewable infrastructure based on location-specific renewable resources. This study offers valuable insights into tailoring green hydrogen production strategies in regions with similar climatic conditions to Diyala and serves as a blueprint for future renewable energy-driven hydrogen production initiatives.
{"title":"Assessment of industrial-scale green hydrogen production using renewable energy","authors":"Q. Hassan, Sameer Algburi, A. Z. Sameen, H. M. Salman","doi":"10.1177/09576509231219339","DOIUrl":"https://doi.org/10.1177/09576509231219339","url":null,"abstract":"The global pivot towards sustainable energy solutions necessitates a closer examination of green hydrogen production using renewable energy sources. This study aimed to assess the feasibility and efficiency of green hydrogen production on an industrial scale using solar and wind energy in Diyala city, Iraq. Experimental weather data, including solar irradiance, ambient temperature, and wind speed, were meticulously collected throughout 2022. The analysis indicated that, for wind energy, the optimum electrolyser capacity that matched a 1.5 MW wind turbine achieved a hydrogen production of 11,963 kg/year, with associated costs of $8.87/kg. In contrast, when focusing on solar energy, the ideal electrolyser capacity harmonizing with a 2 MW solar photovoltaic generated a notably higher hydrogen output of 94,432 kg/year at a more competitive cost of $6.33/kg. These findings underscore the potential economic advantages of solar-based green hydrogen production over wind-based methods in Diyala city. Furthermore, the significant difference in hydrogen production yields between the two methods emphasizes the need to optimize renewable infrastructure based on location-specific renewable resources. This study offers valuable insights into tailoring green hydrogen production strategies in regions with similar climatic conditions to Diyala and serves as a blueprint for future renewable energy-driven hydrogen production initiatives.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":"64 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2023-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139241732","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 : 2023-11-24DOI: 10.1177/09576509231214929
Hamed Sedighi, P. Akbarzadeh, A. Salavatipour
The impact of curved Gurney flaps on the performance of a 660 kW V47 horizontal axis wind turbine (HAWT) is analyzed in this study. The trailing edge of the turbine blades is passively modified by curved flaps. The continuity and momentum equations are solved using a Reynolds-averaged Navier-Stokes solver and Shear-Stress-Transport turbulent model. The effect of the direction and radius of curved flaps on the aerodynamic performance of the wind turbine (torque and power generation, flow separation, and thrust loads) is examined. The study examines how the curved flap’s performance on HAWT is affected by the blade pitch angle ([Formula: see text]) and wind speed ([Formula: see text]). According to the results, curve flaps have a positive impact on the output torque at lower pitch angles ([Formula: see text]). The average torque increase for [Formula: see text] and [Formula: see text] is 3.7% for curve flaps, while it is only 2.9% for flat flaps. This conclusion is not valid for higher pitch angles ([Formula: see text]) where the flap disrupts the aerodynamic performance. Further, the use of curve flaps with the radius of [Formula: see text] (inward-type) can improve the torque produced (up to [Formula: see text]) compared to other curved flaps and even flat flaps, especially around the nominal operating point. This conclusion is valid for [Formula: see text], while for higher pitch angles, the flat Gurney flap has better performance generally.
{"title":"Performance improvement of horizontal axis wind turbines using curved gurney flap: 3D numerical investigation","authors":"Hamed Sedighi, P. Akbarzadeh, A. Salavatipour","doi":"10.1177/09576509231214929","DOIUrl":"https://doi.org/10.1177/09576509231214929","url":null,"abstract":"The impact of curved Gurney flaps on the performance of a 660 kW V47 horizontal axis wind turbine (HAWT) is analyzed in this study. The trailing edge of the turbine blades is passively modified by curved flaps. The continuity and momentum equations are solved using a Reynolds-averaged Navier-Stokes solver and Shear-Stress-Transport turbulent model. The effect of the direction and radius of curved flaps on the aerodynamic performance of the wind turbine (torque and power generation, flow separation, and thrust loads) is examined. The study examines how the curved flap’s performance on HAWT is affected by the blade pitch angle ([Formula: see text]) and wind speed ([Formula: see text]). According to the results, curve flaps have a positive impact on the output torque at lower pitch angles ([Formula: see text]). The average torque increase for [Formula: see text] and [Formula: see text] is 3.7% for curve flaps, while it is only 2.9% for flat flaps. This conclusion is not valid for higher pitch angles ([Formula: see text]) where the flap disrupts the aerodynamic performance. Further, the use of curve flaps with the radius of [Formula: see text] (inward-type) can improve the torque produced (up to [Formula: see text]) compared to other curved flaps and even flat flaps, especially around the nominal operating point. This conclusion is valid for [Formula: see text], while for higher pitch angles, the flat Gurney flap has better performance generally.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":"2012 15","pages":""},"PeriodicalIF":1.7,"publicationDate":"2023-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139239359","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 : 2023-11-23DOI: 10.1177/09576509231218482
Wensong Xue, Z. Fang, Tianhao Wang, Zhigang Li, Jun Li
To improve the stability of the conventional labyrinth seal (LS), in this paper, four novel fully partitioned helically labyrinth seals (FPHGLS) were designed and they were in comparison with one FPPGLS. The influences of the preswirl ratio and the helical groove pitch on the leakage flow and rotordynamic characteristics were numerically investigated, using the transient computational fluid dynamics (CFD) method based on the multi-frequency elliptical whirling orbit model. The accuracy and availability of the present transient numerical method were demonstrated based on the experiment data. The results show that the partition walls design can significantly increase the direct damping and cross-coupling stiffness for labyrinth seals and the helical teeth design can significantly decrease the cross-coupling stiffness and tangential force. When the helical groove pitch is equal to the seal length, the leakage nearly remains unchanged. Compared to the baseline design (LS), the FPPGLS and the FPHGLS have similar and significantly larger direct stiffness and direct damping. The two designs possess positive direct stiffness throughout the frequency range. The FPPGLS and FPHGLS possess significantly higher direct damping (∼323.7% larger than LS). But the FPPGLS possesses the largest cross-coupling stiffness among three seals at two preswirl ratios. From preswirl ratio = 0.13–0.84, the cross-coupling stiffness of the FPHGLS decreases by 53.4-310.1% compared with the FPPGLS. Increasing the helical groove pitch increases both direct stiffness and direct damping and reduces cross-coupling stiffness, but it also leads to greater leakage losses. In general, the novel FPHGLS whose helical groove pitch is equal to seal length possesses superior rotordynamic characteristics and similar leakage characteristic. This work provides the reference of the seal design and safety operation for the turbomachinery.
{"title":"Rotordynamic characteristics of a novel labyrinth seal with partition walls and helical groove teeth","authors":"Wensong Xue, Z. Fang, Tianhao Wang, Zhigang Li, Jun Li","doi":"10.1177/09576509231218482","DOIUrl":"https://doi.org/10.1177/09576509231218482","url":null,"abstract":"To improve the stability of the conventional labyrinth seal (LS), in this paper, four novel fully partitioned helically labyrinth seals (FPHGLS) were designed and they were in comparison with one FPPGLS. The influences of the preswirl ratio and the helical groove pitch on the leakage flow and rotordynamic characteristics were numerically investigated, using the transient computational fluid dynamics (CFD) method based on the multi-frequency elliptical whirling orbit model. The accuracy and availability of the present transient numerical method were demonstrated based on the experiment data. The results show that the partition walls design can significantly increase the direct damping and cross-coupling stiffness for labyrinth seals and the helical teeth design can significantly decrease the cross-coupling stiffness and tangential force. When the helical groove pitch is equal to the seal length, the leakage nearly remains unchanged. Compared to the baseline design (LS), the FPPGLS and the FPHGLS have similar and significantly larger direct stiffness and direct damping. The two designs possess positive direct stiffness throughout the frequency range. The FPPGLS and FPHGLS possess significantly higher direct damping (∼323.7% larger than LS). But the FPPGLS possesses the largest cross-coupling stiffness among three seals at two preswirl ratios. From preswirl ratio = 0.13–0.84, the cross-coupling stiffness of the FPHGLS decreases by 53.4-310.1% compared with the FPPGLS. Increasing the helical groove pitch increases both direct stiffness and direct damping and reduces cross-coupling stiffness, but it also leads to greater leakage losses. In general, the novel FPHGLS whose helical groove pitch is equal to seal length possesses superior rotordynamic characteristics and similar leakage characteristic. This work provides the reference of the seal design and safety operation for the turbomachinery.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":"165 6","pages":""},"PeriodicalIF":1.7,"publicationDate":"2023-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139243355","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 : 2023-11-21DOI: 10.1177/09576509231217559
MJ Shahriyari, H. Khaleghi, M. Sadoddin, E. Benini
In this study, the effects of solidity and rotor speed ratio on the performance of a contra-rotating fan are investigated numerically. Simulation results have been validated by experimental tests. The test stand construction and the measurements have been performed according to ISO-5801 standard. In order to investigate the effect of blade solidity, simulations have been conducted with constant blade count of the front rotor and four configurations of the rear rotor (having 6, 8, 12 and 16 blades), and also constant blade count of the rear rotor and three configurations of the front rotor (having 8, 12, and 16 blades). Results suggest that there is an optimum solidity for the rear rotor, which gives maximum pressure rise and efficiency. Furthermore, the effects of the rotor speed ratios have been investigated in this study. It is shown that the speed of the front rotor is more effective on the fan performance, as compared to the rear rotor. Results reveal that the performance drop caused by a 25% reduction in the rear rotor blade count, can be compensated by 5% increase of the front rotor rotational speed. Therefore, a suitable choice of the speed ratio can result in light-weight and high-performance contra-rotating stages.
{"title":"Impact of solidity and speed ratio on the performance of a contra-rotating fan","authors":"MJ Shahriyari, H. Khaleghi, M. Sadoddin, E. Benini","doi":"10.1177/09576509231217559","DOIUrl":"https://doi.org/10.1177/09576509231217559","url":null,"abstract":"In this study, the effects of solidity and rotor speed ratio on the performance of a contra-rotating fan are investigated numerically. Simulation results have been validated by experimental tests. The test stand construction and the measurements have been performed according to ISO-5801 standard. In order to investigate the effect of blade solidity, simulations have been conducted with constant blade count of the front rotor and four configurations of the rear rotor (having 6, 8, 12 and 16 blades), and also constant blade count of the rear rotor and three configurations of the front rotor (having 8, 12, and 16 blades). Results suggest that there is an optimum solidity for the rear rotor, which gives maximum pressure rise and efficiency. Furthermore, the effects of the rotor speed ratios have been investigated in this study. It is shown that the speed of the front rotor is more effective on the fan performance, as compared to the rear rotor. Results reveal that the performance drop caused by a 25% reduction in the rear rotor blade count, can be compensated by 5% increase of the front rotor rotational speed. Therefore, a suitable choice of the speed ratio can result in light-weight and high-performance contra-rotating stages.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":"60 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2023-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139253278","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 : 2023-11-20DOI: 10.1177/09576509231217025
Rui Liu, Xuan Yang, Li Huang, Xinrui Li, Gang Shen, Dehao Ju, Mingzhi Feng, Xingcai Lu
Multiple injection is one of the advanced technologies employed in modern diesel engines to improve combustion efficiency, reduce pollutant emissions, and minimize combustion noise. The application of multiple injection in marine diesel engines differs from its use in vehicles or heavy-duty engines, as it is not commonly combined with Exhaust Gas Recirculation (EGR). However, there is a scarcity of studies specifically examining the combustion characteristics of medium-speed marine diesel engines utilizing multiple injection. Given the large space scale of marine diesel engine, a constant volume chamber with a visible diameter of 240 mm was used, and an injector with a nozzle diameter of 0.465 mm was employed in the experiment. The spray development and combustion process were recorded by Mie-scattering and flame natural luminosity imaging respectively. Both conventional and double injection combustion processes were analyzed in detail. The results show that although the liquid phase spray does not fully penetrate to the cylinder wall in marine diesel engines, the flame penetrates to the cylinder wall rapidly, the flame burns near the wall almost throughout the entire combustion duration. The combustion characteristics of the double injection are significantly different, the flame propagation speed of the pilot and main injection fuel is one-third to one-half of that of a single injection with a long duration. For single injection spray with long injection duration, the flame penetration velocity is determined by the sequential ignition velocity of the fuel. While the flame penetration velocity for sprays with short injection duration mainly depends on the jet penetration velocity. The investigation on the impact of dwell time, fuel distribution, and injection pressure on the combustion process of double injection also provides valuable insights for optimizing multiple injection strategies.
{"title":"Experimental investigation on spray and flame characteristics of a marine diesel engine with single and double injection","authors":"Rui Liu, Xuan Yang, Li Huang, Xinrui Li, Gang Shen, Dehao Ju, Mingzhi Feng, Xingcai Lu","doi":"10.1177/09576509231217025","DOIUrl":"https://doi.org/10.1177/09576509231217025","url":null,"abstract":"Multiple injection is one of the advanced technologies employed in modern diesel engines to improve combustion efficiency, reduce pollutant emissions, and minimize combustion noise. The application of multiple injection in marine diesel engines differs from its use in vehicles or heavy-duty engines, as it is not commonly combined with Exhaust Gas Recirculation (EGR). However, there is a scarcity of studies specifically examining the combustion characteristics of medium-speed marine diesel engines utilizing multiple injection. Given the large space scale of marine diesel engine, a constant volume chamber with a visible diameter of 240 mm was used, and an injector with a nozzle diameter of 0.465 mm was employed in the experiment. The spray development and combustion process were recorded by Mie-scattering and flame natural luminosity imaging respectively. Both conventional and double injection combustion processes were analyzed in detail. The results show that although the liquid phase spray does not fully penetrate to the cylinder wall in marine diesel engines, the flame penetrates to the cylinder wall rapidly, the flame burns near the wall almost throughout the entire combustion duration. The combustion characteristics of the double injection are significantly different, the flame propagation speed of the pilot and main injection fuel is one-third to one-half of that of a single injection with a long duration. For single injection spray with long injection duration, the flame penetration velocity is determined by the sequential ignition velocity of the fuel. While the flame penetration velocity for sprays with short injection duration mainly depends on the jet penetration velocity. The investigation on the impact of dwell time, fuel distribution, and injection pressure on the combustion process of double injection also provides valuable insights for optimizing multiple injection strategies.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":"50 3","pages":""},"PeriodicalIF":1.7,"publicationDate":"2023-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139254957","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 : 2023-11-18DOI: 10.1177/09576509231216187
Davood Altafi, M. Mojaddam, Majid Bastankhah
This study compares the local losses of a radial compressor in the range from surge to choke considering shock phenomena, boundary layer separation, and mixing mechanisms. For this purpose, formulation of the local entropy generation rate (EGR) is added to the computational fluid dynamics (CFD) solver, which models the turbulent flow field of the compressor through the RANS approach. For validation, the numerical pressure rise curve of the compressor is compared with the experimental data. The results indicate that at the design point, the impeller, diffuser, and the volute account for approximately 50.8%, 30.0%, and 12.3% of the EGR, respectively, with approximately 5% in the impeller backspace, 1% in the diffuser cavity, and less than 0.5% in the inlet duct. Approaching the surge condition, local losses due to mixing and shock waves decline while boundary layer losses increase. Based on comprehensive analysis of the leading-edge boundary layer, the largest dead-air zone is found at the design point, resulting in a lower diffusion entrance loss and a higher mixing loss. Furthermore, the EGR variation in the diffuser channel is investigated by shedding light on mixing dynamics and classification of the channel flow regime into three different zones based on mixing ratio (MR). The outcomes show that the flow regime tends to mix more quickly at a higher MR, resulting in a slight decrease in EGR, which benefits compressor performance. We demonstrate that the mixing rate of flow regimes decreases in both the leading-edge boundary layer and the radial diffuser approaching the surge margin.
{"title":"Entropy generation rate analysis of turbocharger radial flow compressor in range from surge to choke","authors":"Davood Altafi, M. Mojaddam, Majid Bastankhah","doi":"10.1177/09576509231216187","DOIUrl":"https://doi.org/10.1177/09576509231216187","url":null,"abstract":"This study compares the local losses of a radial compressor in the range from surge to choke considering shock phenomena, boundary layer separation, and mixing mechanisms. For this purpose, formulation of the local entropy generation rate (EGR) is added to the computational fluid dynamics (CFD) solver, which models the turbulent flow field of the compressor through the RANS approach. For validation, the numerical pressure rise curve of the compressor is compared with the experimental data. The results indicate that at the design point, the impeller, diffuser, and the volute account for approximately 50.8%, 30.0%, and 12.3% of the EGR, respectively, with approximately 5% in the impeller backspace, 1% in the diffuser cavity, and less than 0.5% in the inlet duct. Approaching the surge condition, local losses due to mixing and shock waves decline while boundary layer losses increase. Based on comprehensive analysis of the leading-edge boundary layer, the largest dead-air zone is found at the design point, resulting in a lower diffusion entrance loss and a higher mixing loss. Furthermore, the EGR variation in the diffuser channel is investigated by shedding light on mixing dynamics and classification of the channel flow regime into three different zones based on mixing ratio (MR). The outcomes show that the flow regime tends to mix more quickly at a higher MR, resulting in a slight decrease in EGR, which benefits compressor performance. We demonstrate that the mixing rate of flow regimes decreases in both the leading-edge boundary layer and the radial diffuser approaching the surge margin.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":"35 3 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2023-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139261527","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 : 2023-11-17DOI: 10.1177/09576509231216502
Lei Shi, Hongwei Ma, Xinghang Yu, Rong Jin, Tianyou Wang
The continuous throttling process is of great interest for compressor designers. Previous experimental studies mainly consider the temporal evolution characteristics of the pre-stage stall at the impeller inlet or outlet regions. In this study, we explore the spatial-temporal evolution characteristics of pre-stage-stall using a pressure array consisting of 15 high-response sensors. The dynamic evolution characteristics of the pressure signal on the time and frequency domains and the underlying unsteady flow structure evolution during the transition process were analyzed. We find that the evolution characteristics of pressure irregularity varied with the streamwise positions. The evolution process from the pre-stage stall point to the stage stall point can be divided into three stages based on the disturbance scale and pressure fluctuations, namely (I) the coexistence of the impeller RI, the mild impeller stall, and the mild diffuser stall, (II) the interaction of stall cell and RI disturbance, (III) a single large stall cell. In stage I, the streamwise influential regions of the stall cells are mainly confined in the impeller passage. In stage II, the stall cell expands upstream and gradually interacts with the RI disturbance. The wavelength of RI-related disturbance increases while the related pressure fluctuation decreases. In stage III, several stall cells merge into one large cell.
压缩机设计人员对连续节流过程非常感兴趣。以往的实验研究主要考虑叶轮进口或出口区域预级失速的时间演变特征。在本研究中，我们使用由 15 个高响应传感器组成的压力阵列来探索前级失速的时空演变特征。分析了压力信号在时域和频域上的动态演化特征以及过渡过程中潜在的非稳态流动结构演化。我们发现，压力不规则性的演变特征随流向位置的变化而变化。根据扰动尺度和压力波动情况，可将前阶段失速点到阶段失速点的演化过程分为三个阶段，即（I）叶轮RI、轻度叶轮失速和轻度扩散器失速共存阶段；（II）失速单元与RI扰动相互作用阶段；（III）单一大失速单元阶段。在第一阶段，滞流单元的流向影响区域主要局限在叶轮通道内。在第二阶段，失速单元向上游扩展，并逐渐与 RI 干扰相互作用。与 RI 相关的扰动波长增加，而相关的压力波动减小。在第三阶段，几个失速单元合并成一个大单元。
{"title":"Spatial-Temporal evolution characteristics of pre-Stage-stall in a centrifugal compressor with a vaneless diffuser and a volute","authors":"Lei Shi, Hongwei Ma, Xinghang Yu, Rong Jin, Tianyou Wang","doi":"10.1177/09576509231216502","DOIUrl":"https://doi.org/10.1177/09576509231216502","url":null,"abstract":"The continuous throttling process is of great interest for compressor designers. Previous experimental studies mainly consider the temporal evolution characteristics of the pre-stage stall at the impeller inlet or outlet regions. In this study, we explore the spatial-temporal evolution characteristics of pre-stage-stall using a pressure array consisting of 15 high-response sensors. The dynamic evolution characteristics of the pressure signal on the time and frequency domains and the underlying unsteady flow structure evolution during the transition process were analyzed. We find that the evolution characteristics of pressure irregularity varied with the streamwise positions. The evolution process from the pre-stage stall point to the stage stall point can be divided into three stages based on the disturbance scale and pressure fluctuations, namely (I) the coexistence of the impeller RI, the mild impeller stall, and the mild diffuser stall, (II) the interaction of stall cell and RI disturbance, (III) a single large stall cell. In stage I, the streamwise influential regions of the stall cells are mainly confined in the impeller passage. In stage II, the stall cell expands upstream and gradually interacts with the RI disturbance. The wavelength of RI-related disturbance increases while the related pressure fluctuation decreases. In stage III, several stall cells merge into one large cell.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":"67 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2023-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139265405","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 : 2023-11-14DOI: 10.1177/09576509231216021
Xiaopeng Xin, Yilong Min, Dingyi Pan, Zhenyu Liu, Jianrong Tan
With ever-increasing demand for high efficiency and high stability gas turbine under the goal of carbon neutrality, the design of L-inlet duct has set stricter demands for low pressure loss and low flow distortion. No general optimization guidelines on both pressure loss and distortion for L-inlet duct were found in open literature. Four geometry parameters including inlet width, inlet length, contraction geometry angle and truncated cone geometry angle are explored for their effects on the trends of pressure loss and flow distortion. Optimization geometry parameters of the L-inlet duct are analysed, and the flow characteristics are thoroughly examined. The flow field characteristic of ΔP t , DC60, SC60 from surrogate model are validated by CFD, the relative errors are 0.37%, −3.92% and 1.75%, respectively. At the design point EF = 35 comparing with original scheme of the L-inlet duct, ΔP t decreases 21.14%, DC60 decreases 45.37%, and SC60 decreases 38.7%. For all off design conditions, the optimization results are better than original scheme. It is estimated that gas turbines can achieve a 0.144% reduction in power loss and a 0.333% improvement in surge margin.
{"title":"Fast multi-objective optimization design of gas turbine L-inlet duct","authors":"Xiaopeng Xin, Yilong Min, Dingyi Pan, Zhenyu Liu, Jianrong Tan","doi":"10.1177/09576509231216021","DOIUrl":"https://doi.org/10.1177/09576509231216021","url":null,"abstract":"With ever-increasing demand for high efficiency and high stability gas turbine under the goal of carbon neutrality, the design of L-inlet duct has set stricter demands for low pressure loss and low flow distortion. No general optimization guidelines on both pressure loss and distortion for L-inlet duct were found in open literature. Four geometry parameters including inlet width, inlet length, contraction geometry angle and truncated cone geometry angle are explored for their effects on the trends of pressure loss and flow distortion. Optimization geometry parameters of the L-inlet duct are analysed, and the flow characteristics are thoroughly examined. The flow field characteristic of ΔP t , DC60, SC60 from surrogate model are validated by CFD, the relative errors are 0.37%, −3.92% and 1.75%, respectively. At the design point EF = 35 comparing with original scheme of the L-inlet duct, ΔP t decreases 21.14%, DC60 decreases 45.37%, and SC60 decreases 38.7%. For all off design conditions, the optimization results are better than original scheme. It is estimated that gas turbines can achieve a 0.144% reduction in power loss and a 0.333% improvement in surge margin.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":"39 9","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134992490","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}
Diagonal flow fans offer substantial energy-saving potential and find broad application across various sectors. Their performance relies heavily on factors like outlet guide vanes and spacing relative to moving blades. However, research into enhancing fan performance through optimized guide vanes and spacing remains limited. In this study, we focus on improving the accuracy of predicting the internal flow field of diagonal flow fans. This paper incorporate rotation and curvature effects using the Large Eddy Simulation (LES) model and introduce stress terms with helicity constraints to create a non-linear subgrid-scale model. This refined model enables more precise numerical simulations. By employing accurate simulations, we optimize the outlet guide vane configuration and conduct sensitivity analysis. We utilize a Radial Basis Function (RBF) model coupled with the Sobol method for this purpose. The optimized guide vane design exhibits enhanced resistance to airflow separation compared to the original, resulting in notable reductions in flow losses within the grille channel. Experimental tests are performed on the diagonal flow fan both before and after optimization. At the specified operating point, the second guide vane optimization leads to a 1.28 m 3 /min increase in fan flow, a 4.33% rise in total pressure efficiency, and a 2.2 dB noise reduction. These findings underscore the accuracy of the helicity correction model in predicting diagonal flow fan behavior. The multi-objective optimization approach, combining the RBF proxy model with the Sobol method, proves highly reliable. It offers valuable design insights for similar fans and establishes a credible design methodology.
{"title":"The multi-objective optimisation design of outlet guide vanes of diagonal flow fan based on sobol sensitivity analysis","authors":"Zijian Mao, Yu Luo, Shuiqing Zhou, Weiya Jin, Weiping Feng","doi":"10.1177/09576509231210902","DOIUrl":"https://doi.org/10.1177/09576509231210902","url":null,"abstract":"Diagonal flow fans offer substantial energy-saving potential and find broad application across various sectors. Their performance relies heavily on factors like outlet guide vanes and spacing relative to moving blades. However, research into enhancing fan performance through optimized guide vanes and spacing remains limited. In this study, we focus on improving the accuracy of predicting the internal flow field of diagonal flow fans. This paper incorporate rotation and curvature effects using the Large Eddy Simulation (LES) model and introduce stress terms with helicity constraints to create a non-linear subgrid-scale model. This refined model enables more precise numerical simulations. By employing accurate simulations, we optimize the outlet guide vane configuration and conduct sensitivity analysis. We utilize a Radial Basis Function (RBF) model coupled with the Sobol method for this purpose. The optimized guide vane design exhibits enhanced resistance to airflow separation compared to the original, resulting in notable reductions in flow losses within the grille channel. Experimental tests are performed on the diagonal flow fan both before and after optimization. At the specified operating point, the second guide vane optimization leads to a 1.28 m 3 /min increase in fan flow, a 4.33% rise in total pressure efficiency, and a 2.2 dB noise reduction. These findings underscore the accuracy of the helicity correction model in predicting diagonal flow fan behavior. The multi-objective optimization approach, combining the RBF proxy model with the Sobol method, proves highly reliable. It offers valuable design insights for similar fans and establishes a credible design methodology.","PeriodicalId":20705,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy","volume":"114 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135818386","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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