Light emissions during chemical reactions provide insights into various scenarios to better understand explosions and water hammers. For example, hydrogen burning and explosions emit blue light, organic carbon combustion and explosions emit combinations of blue and yellow light, water phase changes emit infrared and less visible white light, and white light explosions ignite when multiple chemical reactions are involved. Since experimental tests to observe infrared light during water hammers have not yet been performed, test data from water boiling tests and volcanoes are compared to larger water hammer and steam explosion incidents. Considering these facts and examining a series of photos and videos from the literature and Internet, determinations are proven with respect to water hammers, steam explosions, Piper Alpha water hammer explosions, and chemical explosions. Such evidence proves that steam explosions are important for water hammer accidents, but chemical explosions explain other explosions that have long been considered to be steam explosions. These other explosions include nuclear power plant explosions, hydro-volcanic explosions, and hydrogen explosions, where some of these explosions are, in fact, related to water hammers. This article is primarily a photographic essay to explain the differences between different types of explosions and water hammers, although combustion and explosion principles are expanded and explained to support this essay.
{"title":"Explosion Differentiation Using Light Emissions—Nuclear Reactor, Steam, Water Hammer, Hydrogen, Piper Alpha, and Hydro-Volcanic Explosions","authors":"R. Leishear","doi":"10.1115/1.4056472","DOIUrl":"https://doi.org/10.1115/1.4056472","url":null,"abstract":"\u0000 Light emissions during chemical reactions provide insights into various scenarios to better understand explosions and water hammers. For example, hydrogen burning and explosions emit blue light, organic carbon combustion and explosions emit combinations of blue and yellow light, water phase changes emit infrared and less visible white light, and white light explosions ignite when multiple chemical reactions are involved. Since experimental tests to observe infrared light during water hammers have not yet been performed, test data from water boiling tests and volcanoes are compared to larger water hammer and steam explosion incidents. Considering these facts and examining a series of photos and videos from the literature and Internet, determinations are proven with respect to water hammers, steam explosions, Piper Alpha water hammer explosions, and chemical explosions. Such evidence proves that steam explosions are important for water hammer accidents, but chemical explosions explain other explosions that have long been considered to be steam explosions. These other explosions include nuclear power plant explosions, hydro-volcanic explosions, and hydrogen explosions, where some of these explosions are, in fact, related to water hammers. This article is primarily a photographic essay to explain the differences between different types of explosions and water hammers, although combustion and explosion principles are expanded and explained to support this essay.","PeriodicalId":8652,"journal":{"name":"ASME Open Journal of Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76117761","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Akif Eren Tatli, D. You, A. Ghanavati, H. Metghalchi
Recompression cycles have the potential to offer high performance when design parameters such as feasibility, performance, and compactness are considered. These cycles have recently gained attention especially in nuclear and concentrating solar power plants because of their high efficiency and environmentally friendly. A study has been done to investigate and learn more about recompression cycles. In this paper, a recompression Brayton cycle has been analyzed by performing parametric studies on the effectiveness of recuperators, pressure ratio, and split ratio as well as other input variables. To understand the relations between these factors and the performances of the cycle, argon was used as a working fluid because of its constant specific heat. The solution to temperatures at each state has been derived analytically, which is presented as a function of independent input variables. Thermal efficiency and exergy efficiency of this cycle have been determined in these analyses. The model indicates following results: entropy generation of recuperators is lower at a minimum split and decreases with increasing effectiveness. When the cycle is optimized for maximum efficiency it does not operate on maximum specific net work. The energy and exergy efficiencies of the cycle increase with increasing pressure ratio reaching a maximum value at the optimum pressure ratio. The effect of split ratio on temperature difference around recuperators shows that energy recovered at low temperature is higher at a minimum split which yields a higher efficiency in the cycle. The performance of the cycle is strongly affected by turbine inlet temperature.
{"title":"Insight Into Recompression Brayton Cycle","authors":"Akif Eren Tatli, D. You, A. Ghanavati, H. Metghalchi","doi":"10.1115/1.4062258","DOIUrl":"https://doi.org/10.1115/1.4062258","url":null,"abstract":"\u0000 Recompression cycles have the potential to offer high performance when design parameters such as feasibility, performance, and compactness are considered. These cycles have recently gained attention especially in nuclear and concentrating solar power plants because of their high efficiency and environmentally friendly. A study has been done to investigate and learn more about recompression cycles. In this paper, a recompression Brayton cycle has been analyzed by performing parametric studies on the effectiveness of recuperators, pressure ratio, and split ratio as well as other input variables. To understand the relations between these factors and the performances of the cycle, argon was used as a working fluid because of its constant specific heat. The solution to temperatures at each state has been derived analytically, which is presented as a function of independent input variables. Thermal efficiency and exergy efficiency of this cycle have been determined in these analyses. The model indicates following results: entropy generation of recuperators is lower at a minimum split and decreases with increasing effectiveness. When the cycle is optimized for maximum efficiency it does not operate on maximum specific net work. The energy and exergy efficiencies of the cycle increase with increasing pressure ratio reaching a maximum value at the optimum pressure ratio. The effect of split ratio on temperature difference around recuperators shows that energy recovered at low temperature is higher at a minimum split which yields a higher efficiency in the cycle. The performance of the cycle is strongly affected by turbine inlet temperature.","PeriodicalId":8652,"journal":{"name":"ASME Open Journal of Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83476321","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mighten C Yip, S. Alaie, E. Romito, Tejas Doshi, A. A. Amiri Moghadam, B. Mosadegh, S. Dunham
This paper describes the methodology for rapid prototyping of nitinol structures by heat setting. Nitinol is a shape memory alloy commonly used in implantable medical devices. The proposed technique, based on 3D printing, can be used to effectively iterate multiple nitinol designs for different types of medical devices. We describe a rapid and low-cost process of ceramic replica molding of standard 3D printed parts to create high-temperature resistant fixtures, suitable for heat setting of nitinol. The technique represents a low cost (<$20 materials per fixture) and rapid (as quickly as 16 h for a volume less than 1.25 × 105 mm3) method for shaping nitinol, a technique that typically is costly, labor intensive, and requires specialized equipment. Our method satisfies a need for cost-effective, rapid prototyping of nitinol for implantable medical devices, and we show an example set of shaped nitinol wires, clips, and stents. This method is straightforward and can be easily applied by researchers to rapidly iterate medical device designs.
{"title":"Low-Cost and Rapid Shaping of Nitinol for Medical Device Prototyping","authors":"Mighten C Yip, S. Alaie, E. Romito, Tejas Doshi, A. A. Amiri Moghadam, B. Mosadegh, S. Dunham","doi":"10.1115/1.4062282","DOIUrl":"https://doi.org/10.1115/1.4062282","url":null,"abstract":"\u0000 This paper describes the methodology for rapid prototyping of nitinol structures by heat setting. Nitinol is a shape memory alloy commonly used in implantable medical devices. The proposed technique, based on 3D printing, can be used to effectively iterate multiple nitinol designs for different types of medical devices. We describe a rapid and low-cost process of ceramic replica molding of standard 3D printed parts to create high-temperature resistant fixtures, suitable for heat setting of nitinol. The technique represents a low cost (<$20 materials per fixture) and rapid (as quickly as 16 h for a volume less than 1.25 × 105 mm3) method for shaping nitinol, a technique that typically is costly, labor intensive, and requires specialized equipment. Our method satisfies a need for cost-effective, rapid prototyping of nitinol for implantable medical devices, and we show an example set of shaped nitinol wires, clips, and stents. This method is straightforward and can be easily applied by researchers to rapidly iterate medical device designs.","PeriodicalId":8652,"journal":{"name":"ASME Open Journal of Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84142077","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The accurate characterization of compressor rotordynamic coefficients during the design phase reduces the risk of subsynchronous vibration problems occurring in the field. Although rotordynamists extensively investigate discrete compressor components (such as seals and front shrouds) to tackle instability issues, integrated or system-level analysis of compressor rotordynamics is very sparse. In reality, the impeller, eye-labyrinth seal, and the front shroud heavily influence one another; and the collective dynamic behavior of the system differs from the sum of the dynamic behavior of isolated components. A computational fluid dynamics (CFD)-based approach is taken to evaluate the dynamic behavior of the system as a whole. The geometry and operating conditions in this work are based on the recent experimental study of Song et al. (2019, “Non-Axisymmetric Flows and Rotordynamic Forces in an Eccentric Shrouded Centrifugal Compressor—Part 1: Measurement,” ASME J. Eng. Gas Turbines Power, 141(11), p. 111014. 10.1115/1.4044874) on centrifugal compressor. The commercial CFD code cfx 19.0 is used to resolve Reynolds-averaged Navier–Stokes equations to quantify the eye-labyrinth seal and front cavity stiffness, damping, and added mass. The entire compressor stage is modeled to uncover the coupled behavior of the components and assess the stability of the whole system instead of just discrete components. In the current work, three CFD approaches, namely quasi-steady, transient static eccentricity, and transient mesh deformation techniques are studied and benchmarked against analytical and experimental results from the literature. Having established the efficacy of the proposed approach, four types of swirl brakes are proposed and analyzed for stability. The novel swirl brakes create negative swirls at the brake cavities and stabilize both the front shroud and the eye-labyrinth seal simultaneously.
在设计阶段，压缩机转子动力系数的准确表征降低了现场发生次同步振动问题的风险。尽管涡旋动力学家广泛研究离散的压缩机部件(如密封件和前罩)来解决不稳定性问题，但对压缩机涡旋动力学的集成或系统级分析非常少。在现实中，叶轮、眼迷宫密封和前罩之间相互影响很大;系统的整体动力行为不同于孤立部件的动力行为之和。采用基于计算流体动力学(CFD)的方法对整个系统的动态行为进行了评估。本工作的几何和运行条件基于Song等人(2019)最近的实验研究，“偏心冠状离心压缩机中的非轴对称流动和旋转动力-第一部分:测量”，ASME J. Eng。燃气轮机动力，41(11)，p. 111014。10.1115/1.4044874)的离心压缩机。商用CFD代码cfx 19.0用于求解reynolds -average Navier-Stokes方程，以量化眼迷宫密封和前腔刚度、阻尼和附加质量。对整个压气机级进行建模，以揭示组件的耦合行为，并评估整个系统的稳定性，而不仅仅是离散组件。在目前的工作中，研究了三种CFD方法，即准稳态、瞬态静态偏心和瞬态网格变形技术，并对文献中的分析和实验结果进行了基准测试。在确定了该方法的有效性后，提出了四种类型的涡流制动器，并对其稳定性进行了分析。新型涡流制动器在制动腔处产生负涡，同时稳定前罩和眼迷宫密封。
{"title":"Swirl Brake Design for Improved Rotordynamic Vibration Stability Based on Computational Fluid Dynamics System Level Modeling","authors":"MD Shujan Ali, Farzam Mortazavi, A. Palazzolo","doi":"10.1115/1.4062934","DOIUrl":"https://doi.org/10.1115/1.4062934","url":null,"abstract":"\u0000 The accurate characterization of compressor rotordynamic coefficients during the design phase reduces the risk of subsynchronous vibration problems occurring in the field. Although rotordynamists extensively investigate discrete compressor components (such as seals and front shrouds) to tackle instability issues, integrated or system-level analysis of compressor rotordynamics is very sparse. In reality, the impeller, eye-labyrinth seal, and the front shroud heavily influence one another; and the collective dynamic behavior of the system differs from the sum of the dynamic behavior of isolated components. A computational fluid dynamics (CFD)-based approach is taken to evaluate the dynamic behavior of the system as a whole. The geometry and operating conditions in this work are based on the recent experimental study of Song et al. (2019, “Non-Axisymmetric Flows and Rotordynamic Forces in an Eccentric Shrouded Centrifugal Compressor—Part 1: Measurement,” ASME J. Eng. Gas Turbines Power, 141(11), p. 111014. 10.1115/1.4044874) on centrifugal compressor. The commercial CFD code cfx 19.0 is used to resolve Reynolds-averaged Navier–Stokes equations to quantify the eye-labyrinth seal and front cavity stiffness, damping, and added mass. The entire compressor stage is modeled to uncover the coupled behavior of the components and assess the stability of the whole system instead of just discrete components. In the current work, three CFD approaches, namely quasi-steady, transient static eccentricity, and transient mesh deformation techniques are studied and benchmarked against analytical and experimental results from the literature. Having established the efficacy of the proposed approach, four types of swirl brakes are proposed and analyzed for stability. The novel swirl brakes create negative swirls at the brake cavities and stabilize both the front shroud and the eye-labyrinth seal simultaneously.","PeriodicalId":8652,"journal":{"name":"ASME Open Journal of Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84503082","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Edward J. Ransley, Scott A. Brown, Emma C. Edwards, Tom Tosdevin, Kieran Monk, Alastair M. Reynolds, Deborah Greaves, Martyn R. Hann
Abstract Physical modeling of floating offshore wind turbines (FOWTs) is challenging due to the complexities associated with the simultaneous application of two different scaling laws, governing the hydrodynamic and aerodynamic loading on the structure. To avoid these issues, this paper presents a real-time hybrid testing (RTHT) strategy in which a feedback loop, consisting of an on-board fan and control algorithm, is utilized to emulate the aerodynamic forces acting on the FOWT system. Here, we apply this strategy to a 70th-scale IEA Wind 15 MW reference wind turbine mounted on a version of the VolturnUS-S platform. Unlike other similar methods, which directly simulate the aerodynamic loads for the fan’s control using an aerodynamic code running in parallel with the experiment, this example utilizes a surrogate model trained on numerical model data calculated in advance. This strategy enables high-fidelity numerical model data, or even physical data, to be included in the aerodynamic emulation, by removing the requirement for real-time simulation, and, therefore, potentially enables more accurate loading predictions to be used in the experiments. This paper documents the development of the real-time hybrid testing system in the Coastal Ocean And Sediment Transport (COAST) Laboratory at the University of Plymouth in the UK, including the hardware, software, and instrumentation setup, and demonstrates the power of the surrogate-based aerodynamic emulator based on numerical data calculated using OpenFAST.
{"title":"Real-Time Hybrid Testing of a Floating Offshore Wind Turbine Using a Surrogate-Based Aerodynamic Emulator","authors":"Edward J. Ransley, Scott A. Brown, Emma C. Edwards, Tom Tosdevin, Kieran Monk, Alastair M. Reynolds, Deborah Greaves, Martyn R. Hann","doi":"10.1115/1.4056963","DOIUrl":"https://doi.org/10.1115/1.4056963","url":null,"abstract":"Abstract Physical modeling of floating offshore wind turbines (FOWTs) is challenging due to the complexities associated with the simultaneous application of two different scaling laws, governing the hydrodynamic and aerodynamic loading on the structure. To avoid these issues, this paper presents a real-time hybrid testing (RTHT) strategy in which a feedback loop, consisting of an on-board fan and control algorithm, is utilized to emulate the aerodynamic forces acting on the FOWT system. Here, we apply this strategy to a 70th-scale IEA Wind 15 MW reference wind turbine mounted on a version of the VolturnUS-S platform. Unlike other similar methods, which directly simulate the aerodynamic loads for the fan’s control using an aerodynamic code running in parallel with the experiment, this example utilizes a surrogate model trained on numerical model data calculated in advance. This strategy enables high-fidelity numerical model data, or even physical data, to be included in the aerodynamic emulation, by removing the requirement for real-time simulation, and, therefore, potentially enables more accurate loading predictions to be used in the experiments. This paper documents the development of the real-time hybrid testing system in the Coastal Ocean And Sediment Transport (COAST) Laboratory at the University of Plymouth in the UK, including the hardware, software, and instrumentation setup, and demonstrates the power of the surrogate-based aerodynamic emulator based on numerical data calculated using OpenFAST.","PeriodicalId":8652,"journal":{"name":"ASME Open Journal of Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135584275","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Wahida Tina, Elizabeth Donaldson, Thomas E. Dickinson, W. Schmidt
The once-through steam generator (OTSG) produces superheated steam using purified feed water. The plant-specific water quality, steam quality, high temperature, and pressure operations lead to the leakage of the OTSG tubes with economic, safety, and environmental consequences. Tube leakage is one of the most frequent causes of OTSG tube failure. A leaking tube was discovered within the OTSG unit of the 110 MW cogeneration plant. The failed section of the tube was removed from the steam generator. Several metallurgical examinations of this tube segment were performed to identify the failure mode and cause. A portion of the tube was analyzed using optical emission spectroscopy (OES) to determine the alloy composition. The results confirmed that the tubing was fabricated from a material consistent with chemical specifications for ASME Specification SB 407 Inconel Alloy 800 (UNS N08800). Glass bead blasting was used to determine the deposit-weight-density (DWD). The DWD value was a maximum of 5.1 g/ft2. The maximum internal deposit thickness was 0.002 in. No evidence of overheating was observed. Scanning electron microscope-energy-dispersive x-ray analysis (SEM-EDXA) was used to determine the elemental composition of the internal deposits. The results indicated that the internal gray deposits primarily comprised iron, chromium, and nickel compounds. There were also fewer amounts of sodium, silicon, aluminum, potassium, and calcium species. The subject tube failure involved a through-wall crack that occurred as stress corrosion cracking (SCC). Additions of caustic solution used in OTSG water treatment practices potentially induced corrosive substances into the tube.
{"title":"Failure Analysis of Once-Through Steam Generator (OTSG) Tube","authors":"Wahida Tina, Elizabeth Donaldson, Thomas E. Dickinson, W. Schmidt","doi":"10.1115/1.4062769","DOIUrl":"https://doi.org/10.1115/1.4062769","url":null,"abstract":"\u0000 The once-through steam generator (OTSG) produces superheated steam using purified feed water. The plant-specific water quality, steam quality, high temperature, and pressure operations lead to the leakage of the OTSG tubes with economic, safety, and environmental consequences. Tube leakage is one of the most frequent causes of OTSG tube failure. A leaking tube was discovered within the OTSG unit of the 110 MW cogeneration plant. The failed section of the tube was removed from the steam generator. Several metallurgical examinations of this tube segment were performed to identify the failure mode and cause. A portion of the tube was analyzed using optical emission spectroscopy (OES) to determine the alloy composition. The results confirmed that the tubing was fabricated from a material consistent with chemical specifications for ASME Specification SB 407 Inconel Alloy 800 (UNS N08800). Glass bead blasting was used to determine the deposit-weight-density (DWD). The DWD value was a maximum of 5.1 g/ft2. The maximum internal deposit thickness was 0.002 in. No evidence of overheating was observed. Scanning electron microscope-energy-dispersive x-ray analysis (SEM-EDXA) was used to determine the elemental composition of the internal deposits. The results indicated that the internal gray deposits primarily comprised iron, chromium, and nickel compounds. There were also fewer amounts of sodium, silicon, aluminum, potassium, and calcium species. The subject tube failure involved a through-wall crack that occurred as stress corrosion cracking (SCC). Additions of caustic solution used in OTSG water treatment practices potentially induced corrosive substances into the tube.","PeriodicalId":8652,"journal":{"name":"ASME Open Journal of Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85976334","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Counter-rotating fan provides significant benefits over the conventional fan in terms of overall performance and size. For electric propulsion application, a counter-rotating fan provides compactness and reduction in weight to achieve higher pressure rise with less power consumption as compared to the unducted propeller. Past literature suggests counter-rotating fans, designed with higher loading in the front rotor, have a flat performance map and a wider range of stable operation. The recommendation of higher aerodynamic loading is not clear what needs to be the aerodynamic load split amongst the rotors. This, in particular, benefits the electrical vehicle to have higher maneuver capability during operation. The paper discusses the design methodology of counter-rotating fans for application in roadable electric aircraft and the effect of different aerodynamic load distributions for both rotors on its overall performance. Fans are designed for different total-pressure rise and loading distributions as (1) 50–50%, (2) 55–45%, (3) 60–40%, and (4) 65–35% in front and rear rotor. It is observed that, as the loading increases for the front rotor, blade camber increases and hence to more prone toward flow separation near the trailing edge under an adverse pressure gradient. Wake coming from the front rotor grows thicker with higher loading, leading to flow acceleration (thus total-pressure loss) in the axial gap between these rotors. As a consequence, flow incidents on the rear rotor other than the design incidence, and thus the rear rotor operates under off-design. With 55–45% loading, both the rotors achieve desired total-pressure rise and stable operating range. The detailed flow field study is discussed to bring important outcomes for achieving the desired performance.
{"title":"Effects of Total Pressure Distribution on Performance of Small-Size Counter-Rotating Axial-Flow Fan Stage for Electrical Propulsion","authors":"T. Bandopadhyay, Chetan S. Mistry","doi":"10.1115/1.4053962","DOIUrl":"https://doi.org/10.1115/1.4053962","url":null,"abstract":"\u0000 Counter-rotating fan provides significant benefits over the conventional fan in terms of overall performance and size. For electric propulsion application, a counter-rotating fan provides compactness and reduction in weight to achieve higher pressure rise with less power consumption as compared to the unducted propeller. Past literature suggests counter-rotating fans, designed with higher loading in the front rotor, have a flat performance map and a wider range of stable operation. The recommendation of higher aerodynamic loading is not clear what needs to be the aerodynamic load split amongst the rotors. This, in particular, benefits the electrical vehicle to have higher maneuver capability during operation. The paper discusses the design methodology of counter-rotating fans for application in roadable electric aircraft and the effect of different aerodynamic load distributions for both rotors on its overall performance. Fans are designed for different total-pressure rise and loading distributions as (1) 50–50%, (2) 55–45%, (3) 60–40%, and (4) 65–35% in front and rear rotor. It is observed that, as the loading increases for the front rotor, blade camber increases and hence to more prone toward flow separation near the trailing edge under an adverse pressure gradient. Wake coming from the front rotor grows thicker with higher loading, leading to flow acceleration (thus total-pressure loss) in the axial gap between these rotors. As a consequence, flow incidents on the rear rotor other than the design incidence, and thus the rear rotor operates under off-design. With 55–45% loading, both the rotors achieve desired total-pressure rise and stable operating range. The detailed flow field study is discussed to bring important outcomes for achieving the desired performance.","PeriodicalId":8652,"journal":{"name":"ASME Open Journal of Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82422855","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Bolted joints are commonly used structural connections as they provide a strong secure joint along with ease of assembly/disassembly. While analytical models for the axial stiffness of bolted joints are well developed, models for moment (angular) stiffness of bolted structures, such as ball screw bearing support blocks, are needed to help engineers rapidly design more efficient precision machines. This paper develops a parametric moment stiffness model for bolted connections which is verified via numerical and experimental methods. Application of the model is illustrated with a ball screw system design spreadsheet, available in Supplemental Material on the ASME Digital Collection, applied to two case studies (machine tool linear axis and high-speed 3D printer) to show how predicting the moment stiffness of ball screw support bearing blocks helps in expanding the available design space and enhance the design performance.
{"title":"An Analytical Model for Pitch Moment Stiffness of Bolted Connections and Its Application in Ballscrew Bearing Support Block Selection","authors":"Akshay Harlalka, A. Slocum","doi":"10.1115/1.4054474","DOIUrl":"https://doi.org/10.1115/1.4054474","url":null,"abstract":"\u0000 Bolted joints are commonly used structural connections as they provide a strong secure joint along with ease of assembly/disassembly. While analytical models for the axial stiffness of bolted joints are well developed, models for moment (angular) stiffness of bolted structures, such as ball screw bearing support blocks, are needed to help engineers rapidly design more efficient precision machines. This paper develops a parametric moment stiffness model for bolted connections which is verified via numerical and experimental methods. Application of the model is illustrated with a ball screw system design spreadsheet, available in Supplemental Material on the ASME Digital Collection, applied to two case studies (machine tool linear axis and high-speed 3D printer) to show how predicting the moment stiffness of ball screw support bearing blocks helps in expanding the available design space and enhance the design performance.","PeriodicalId":8652,"journal":{"name":"ASME Open Journal of Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75293004","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A new pneumatic cylinder assembly is proposed as an alternative to classical cylinders which are well known for their poor energetic efficiency. The new system comprises an added expansion volume which permits to recover the energy content of a filled cylinder by a real thermodynamic expansion instead of simply releasing the filled air to the atmosphere. The energetic performance of the new system is evaluated and compared with the performance of an equivalent single cylinder producing the same mechanical work. The paper explains the operation principle and properties through numeric simulation and presents a small experimental prototype.
{"title":"Revisiting the Industrial Pneumatic Technology—An Innovative Development for an Increased Energetic Efficiency","authors":"A. Rufer","doi":"10.1115/1.4054327","DOIUrl":"https://doi.org/10.1115/1.4054327","url":null,"abstract":"\u0000 A new pneumatic cylinder assembly is proposed as an alternative to classical cylinders which are well known for their poor energetic efficiency. The new system comprises an added expansion volume which permits to recover the energy content of a filled cylinder by a real thermodynamic expansion instead of simply releasing the filled air to the atmosphere. The energetic performance of the new system is evaluated and compared with the performance of an equivalent single cylinder producing the same mechanical work. The paper explains the operation principle and properties through numeric simulation and presents a small experimental prototype.","PeriodicalId":8652,"journal":{"name":"ASME Open Journal of Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73431708","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A new design paradigm for nuclear power plants is needed to complement the increasing adoption of low marginal cost variable renewable energy resources. The situation is reflected in the wholesale electricity price–duration curve with four distinct economic opportunities: (a) a hundred or so hours per year of high-value peaking power; (b) about 4000–5000 h of moderate electric prices; (c) about 2000 h per year when renewables set the marginal price at or near zero; and (d) about 1000 h of flexible ramping between the b and c regions. The current approach to the low-carbon energy transition reduces the need for baseload power and requires curtailment of conventional, nuclear, and even renewable generation, decreasing their capacity factors and increasing their fixed charges for electricity generation. Flexible low-carbon dispatchable power plants capable of daily cycling along with storage and time shifting of low-cost nondispatchable renewable power will be needed. Although nuclear power plants have demonstrated load-following capability, cycling can be limited by reactor kinetics (xenon poisoning) as well as by thermal stresses and fatigue considerations in the steam cycle. Storage of nuclear heat is hampered by the relatively low operating temperatures of existing nuclear reactors (but not advanced reactors) that lowers thermal to electric conversion efficiency, which in turn increases the required quantity of storage medium and the cost of storage. The quantity of storage medium can be reduced by integration of thermal energy storage with high-grade heat as in the liquid salt combined cycle (LSCC). The LSCC uses high-temperature gas turbine exhaust heat to increase the electricity output per unit of storage medium, uses the stored energy to add operating flexibility to a bottoming steam cycle, and substantially reduces the fuel heat rate. The low fuel heat rate improves economic competitiveness compared to alternative gas turbine-based power plants, especially when burning expensive fuels such as hydrogen. LSCC could be coupled to a nuclear power plant for time shifting both nuclear and renewable electricity and could support high utilization of a co-located hydrogen electrolysis plant. Further cost reduction could be achieved by using solid media for thermal energy storage, with the liquid salt used as a heat transfer medium.
{"title":"Storage-Coupled Nuclear Combined Cycle","authors":"W. Conlon, C. Forsberg","doi":"10.1115/1.4055277","DOIUrl":"https://doi.org/10.1115/1.4055277","url":null,"abstract":"\u0000 A new design paradigm for nuclear power plants is needed to complement the increasing adoption of low marginal cost variable renewable energy resources. The situation is reflected in the wholesale electricity price–duration curve with four distinct economic opportunities: (a) a hundred or so hours per year of high-value peaking power; (b) about 4000–5000 h of moderate electric prices; (c) about 2000 h per year when renewables set the marginal price at or near zero; and (d) about 1000 h of flexible ramping between the b and c regions. The current approach to the low-carbon energy transition reduces the need for baseload power and requires curtailment of conventional, nuclear, and even renewable generation, decreasing their capacity factors and increasing their fixed charges for electricity generation. Flexible low-carbon dispatchable power plants capable of daily cycling along with storage and time shifting of low-cost nondispatchable renewable power will be needed. Although nuclear power plants have demonstrated load-following capability, cycling can be limited by reactor kinetics (xenon poisoning) as well as by thermal stresses and fatigue considerations in the steam cycle. Storage of nuclear heat is hampered by the relatively low operating temperatures of existing nuclear reactors (but not advanced reactors) that lowers thermal to electric conversion efficiency, which in turn increases the required quantity of storage medium and the cost of storage. The quantity of storage medium can be reduced by integration of thermal energy storage with high-grade heat as in the liquid salt combined cycle (LSCC). The LSCC uses high-temperature gas turbine exhaust heat to increase the electricity output per unit of storage medium, uses the stored energy to add operating flexibility to a bottoming steam cycle, and substantially reduces the fuel heat rate. The low fuel heat rate improves economic competitiveness compared to alternative gas turbine-based power plants, especially when burning expensive fuels such as hydrogen. LSCC could be coupled to a nuclear power plant for time shifting both nuclear and renewable electricity and could support high utilization of a co-located hydrogen electrolysis plant. Further cost reduction could be achieved by using solid media for thermal energy storage, with the liquid salt used as a heat transfer medium.","PeriodicalId":8652,"journal":{"name":"ASME Open Journal of Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74002767","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：