The recent progress in commercial space flights and prospects for interplanetary space missions has attracted more attention towards developing sustainable built environments in microgravity conditions. An important factor in establishing a sustainable living condition for outer space applications is the ability to produce food. The thermal design considerations in a greenhouse have a major impact on the survival, water efficiency, quantity, and quality of plants produced. The extremely low environmental temperatures necessitate the use of heaters which do consume energy. Given the scarcity of energy access, it is important to achieve proper thermal conditions with the lowest possible energy requirements. This paper discusses the thermal design and considerations of a greenhouse in a microgravity environment (i.e. Martian environment) with extremely low ambient temperature conditions (nearly −200 K) and limited availability of solar radiation (maximum of 590 W/m 2). A parametric study is performed using COMSOL Multiphysics. The effects of varying several design parameters including heater capacity, and placement of heaters are investigated on the indoor thermal condition of the greenhouse. The temperature distribution inside the greenhouse is assessed for several design conditions and the desirable distributions for plant growth are further analyzed. The impact of microgravity conditions is also assessed through a comparison of results between microgravity and normal gravity conditions. The results from this study could be used towards the proper thermal design of greenhouses for the extreme conditions of outer space applications.
{"title":"Thermal Design and Parametric Study of a Greenhouse in Microgravity Conditions","authors":"Nivedha Karigiri Madhusudhan, H. Najafi","doi":"10.1115/imece2022-96211","DOIUrl":"https://doi.org/10.1115/imece2022-96211","url":null,"abstract":"\u0000 The recent progress in commercial space flights and prospects for interplanetary space missions has attracted more attention towards developing sustainable built environments in microgravity conditions. An important factor in establishing a sustainable living condition for outer space applications is the ability to produce food. The thermal design considerations in a greenhouse have a major impact on the survival, water efficiency, quantity, and quality of plants produced. The extremely low environmental temperatures necessitate the use of heaters which do consume energy. Given the scarcity of energy access, it is important to achieve proper thermal conditions with the lowest possible energy requirements. This paper discusses the thermal design and considerations of a greenhouse in a microgravity environment (i.e. Martian environment) with extremely low ambient temperature conditions (nearly −200 K) and limited availability of solar radiation (maximum of 590 W/m 2). A parametric study is performed using COMSOL Multiphysics. The effects of varying several design parameters including heater capacity, and placement of heaters are investigated on the indoor thermal condition of the greenhouse. The temperature distribution inside the greenhouse is assessed for several design conditions and the desirable distributions for plant growth are further analyzed. The impact of microgravity conditions is also assessed through a comparison of results between microgravity and normal gravity conditions. The results from this study could be used towards the proper thermal design of greenhouses for the extreme conditions of outer space applications.","PeriodicalId":292222,"journal":{"name":"Volume 8: Fluids Engineering; Heat Transfer and Thermal Engineering","volume":"46 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127642711","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}
Abdul Aziz Shuvo, Md. Omarsany Bappy, Amitav Tikadar, T. C. Paul, A. Morshed
Microchannel heat sinks (MCHS) are promisingly utilized to remove large heat flux from microelectronic devices. However, the velocity and thermal boundary layers grow continually in a straight microchannel. As a result, the performance of the microchannel degrades. Disrupting the formation of the boundary layer can enhance the performance of MCHS. One approach to achieve that goal is to develop a wavy channel rather than a straight microchannel (s-MCHS) which hinders the continual growth of boundary layers due to its waviness. Numerous researches suggested that wave amplitude increment and wavelength decrement enhanced the chaotic advection and better coolant mixing. Thus, heat transfer and pressure drop were increased in the MCHS. Although wavelength and wave amplitude in a wavy MCHS (w-MCHS) significantly impact heat transfer performance, the phase shift (θp) between two wavy walls in an MCHS also affects the flow and heat transfer characteristics. When the upper and lower sinusoidal walls are in different phases, the cross-sectional area of the MCHS varies. So, the cross-sectional flow area variation creates an adverse pressure gradient in the MCHS. which causes more flow reversal and better coolant mixing, resulting in improved thermal performance. The current study aims to study the flow and heat transfer characteristics in w-MCHS for three different phase shifts, θp = 0, π/2, π, under laminar flow conditions. Re ranges from 300 to 800 in the study. w-MCHS with phase shift, θp = π/2, π always shows higher Nusselt number (Nu) than s-MCHS and w-MCHS with phase shift, θp = 0. An increase in surface area due to phase shifts, θp = π/2 and θp = π in wavy MCHS, is negligible and the enhancement in heat transfer of phase-shifted w-MCHS is caused by interruption, reinitialization, and reattachment of boundary layers. In the current numerical study, Nu was found to increase with the phase shift and found 7 times higher than s-MCHS at phase shift, θp = π for wavelength (λ) = 3.5 mm. Besides higher heat transfer and better coolant mixing, the phase shift in wavy MCHS causes increased shear stress and pressure drop due to chaotic flow in wavy MCHS.
{"title":"Heat Transfer and Flow Characteristic of Sinusoidal Wavy Microchannel Heat Sink With Different Phase Shift","authors":"Abdul Aziz Shuvo, Md. Omarsany Bappy, Amitav Tikadar, T. C. Paul, A. Morshed","doi":"10.1115/imece2022-95864","DOIUrl":"https://doi.org/10.1115/imece2022-95864","url":null,"abstract":"\u0000 Microchannel heat sinks (MCHS) are promisingly utilized to remove large heat flux from microelectronic devices. However, the velocity and thermal boundary layers grow continually in a straight microchannel. As a result, the performance of the microchannel degrades. Disrupting the formation of the boundary layer can enhance the performance of MCHS. One approach to achieve that goal is to develop a wavy channel rather than a straight microchannel (s-MCHS) which hinders the continual growth of boundary layers due to its waviness. Numerous researches suggested that wave amplitude increment and wavelength decrement enhanced the chaotic advection and better coolant mixing. Thus, heat transfer and pressure drop were increased in the MCHS. Although wavelength and wave amplitude in a wavy MCHS (w-MCHS) significantly impact heat transfer performance, the phase shift (θp) between two wavy walls in an MCHS also affects the flow and heat transfer characteristics. When the upper and lower sinusoidal walls are in different phases, the cross-sectional area of the MCHS varies. So, the cross-sectional flow area variation creates an adverse pressure gradient in the MCHS. which causes more flow reversal and better coolant mixing, resulting in improved thermal performance.\u0000 The current study aims to study the flow and heat transfer characteristics in w-MCHS for three different phase shifts, θp = 0, π/2, π, under laminar flow conditions. Re ranges from 300 to 800 in the study. w-MCHS with phase shift, θp = π/2, π always shows higher Nusselt number (Nu) than s-MCHS and w-MCHS with phase shift, θp = 0. An increase in surface area due to phase shifts, θp = π/2 and θp = π in wavy MCHS, is negligible and the enhancement in heat transfer of phase-shifted w-MCHS is caused by interruption, reinitialization, and reattachment of boundary layers. In the current numerical study, Nu was found to increase with the phase shift and found 7 times higher than s-MCHS at phase shift, θp = π for wavelength (λ) = 3.5 mm. Besides higher heat transfer and better coolant mixing, the phase shift in wavy MCHS causes increased shear stress and pressure drop due to chaotic flow in wavy MCHS.","PeriodicalId":292222,"journal":{"name":"Volume 8: Fluids Engineering; Heat Transfer and Thermal Engineering","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126765845","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 laser transmission in the polymer powder bed includes three parts during the selective laser sintering (SLS) process: absorption, reflection, and scattering. Because of the granular nature of the polymer powder, the scattering phenomena causes the photons isotropic travel in the medium, which affects directly the photons’ distribution in the powder bed. In this paper, we numerically simulate the laser heat source traveling in a powder polymer bed, as in the SLS process, by introducing the Mie theory with Monte-Carlo method, instead of the Bear-Lambert Law, to correctly represent the heating energy distribution in the material. The obtained energy distribution is then introduced in the energy equation to solve the heat transfer problem in such non homogeneous medium. All the material transformation are also introduced, as the melting process, the coalescence, air diffusion and porosity evolution, based on classical theories. Meanwhile, we carry out a parametric thermal analysis and discussed based on process parameters, like the laser power, laser moving length and the material preheating temperature. Their influence on the temperature evolution is quantified. These analysis results can be used as a guide for providing technical database to SLS process, helpful for various industries in automotive, aerospace and medical areas.
{"title":"Heat Transfer During Polymer Selective Laser Sintering Process: Parametric Analysis","authors":"Lan Zhang, M. Boutaous, S. Xin, D. Siginer","doi":"10.1115/imece2022-96664","DOIUrl":"https://doi.org/10.1115/imece2022-96664","url":null,"abstract":"\u0000 The laser transmission in the polymer powder bed includes three parts during the selective laser sintering (SLS) process: absorption, reflection, and scattering. Because of the granular nature of the polymer powder, the scattering phenomena causes the photons isotropic travel in the medium, which affects directly the photons’ distribution in the powder bed. In this paper, we numerically simulate the laser heat source traveling in a powder polymer bed, as in the SLS process, by introducing the Mie theory with Monte-Carlo method, instead of the Bear-Lambert Law, to correctly represent the heating energy distribution in the material. The obtained energy distribution is then introduced in the energy equation to solve the heat transfer problem in such non homogeneous medium. All the material transformation are also introduced, as the melting process, the coalescence, air diffusion and porosity evolution, based on classical theories. Meanwhile, we carry out a parametric thermal analysis and discussed based on process parameters, like the laser power, laser moving length and the material preheating temperature. Their influence on the temperature evolution is quantified. These analysis results can be used as a guide for providing technical database to SLS process, helpful for various industries in automotive, aerospace and medical areas.","PeriodicalId":292222,"journal":{"name":"Volume 8: Fluids Engineering; Heat Transfer and Thermal Engineering","volume":"60 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127141980","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}
Root canal therapy or endodontic treatment is a nonsurgical approach used to remove the infected pulp, disinfect, and reshape the canal. Despite more than a century of technological improvements in root canal procedures, clinical studies indicate that microbial flora remain in the canal following standardized cleaning and shaping procedures using antimicrobial irrigants. Unfortunately, accessing this ‘dead zone’ in the apical third has been challenging given the large number of parameters that govern the flow pattern. Computational fluid dynamics (CFD) presents a powerful tool to investigate flow behavior in areas where experimental measurements are difficult to perform. This paper is divided into two sections. First, the influence of irrigant flow rate and needle insertion depth on velocity characteristics are computationally investigated for a simplified root geometry. The needle type considered is a 30 gage KerrHawe with a side vent for fluid discharge. The simplified root canal was modeled as a frustum with a length of 18 mm, diameter of 1.59 mm at the orifice, and a diameter of 0.45 mm at the apical constriction (6.5% taper). Following this, a more realistic root geometry is used to investigate how the results from part 1 scale with root geometry.
{"title":"Numerical Investigation of Irrigant Flow Characteristics for Manual Endodontic Debridement","authors":"G. Janes, Tikran Kocharian, S. Manoharan","doi":"10.1115/imece2022-95982","DOIUrl":"https://doi.org/10.1115/imece2022-95982","url":null,"abstract":"\u0000 Root canal therapy or endodontic treatment is a nonsurgical approach used to remove the infected pulp, disinfect, and reshape the canal. Despite more than a century of technological improvements in root canal procedures, clinical studies indicate that microbial flora remain in the canal following standardized cleaning and shaping procedures using antimicrobial irrigants. Unfortunately, accessing this ‘dead zone’ in the apical third has been challenging given the large number of parameters that govern the flow pattern. Computational fluid dynamics (CFD) presents a powerful tool to investigate flow behavior in areas where experimental measurements are difficult to perform. This paper is divided into two sections. First, the influence of irrigant flow rate and needle insertion depth on velocity characteristics are computationally investigated for a simplified root geometry. The needle type considered is a 30 gage KerrHawe with a side vent for fluid discharge. The simplified root canal was modeled as a frustum with a length of 18 mm, diameter of 1.59 mm at the orifice, and a diameter of 0.45 mm at the apical constriction (6.5% taper). Following this, a more realistic root geometry is used to investigate how the results from part 1 scale with root geometry.","PeriodicalId":292222,"journal":{"name":"Volume 8: Fluids Engineering; Heat Transfer and Thermal Engineering","volume":"57 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132066119","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}
Aditya N. Sangli, Austin Hultmark, Graham Aldinger, Ranjeet Rao, D. M. Johnson, Ashutos Parhi, P. Sharma
Conventional spray nozzles are used in industries to atomize fluids for many applications. But these nozzles cannot atomize fluids having large viscosities and non-Newtonian characteristics. Dairy fluids like whey suspensions are examples of such fluids. Nozzles used in atomization of such suspensions for spray drying only operate with fluids having high water content. Atomizing suspensions with low water content will conserve energy by lowering the load on the spray dryer. In this study, we have used Filament Extension Atomization (FEA) technology to spray sweet dry whey suspension at 80% solids loading and Whey Protein Concentrate (WPC 80) at 50% solids loading. These concentrations are 30% above current industrial standards. We present our formulation techniques and non-Newtonian rheology characterization of the suspensions. By spraying the suspensions with FEA, we demonstrate tight control over drop size distribution in the spray with a D50 < 200 μm. Finally, we present a novel design for high throughput spraying of such dairy suspensions to be incorporated into industrial spray dryers.
{"title":"Filament Extension Atomization Spraying of High Concentration Whey Suspensions","authors":"Aditya N. Sangli, Austin Hultmark, Graham Aldinger, Ranjeet Rao, D. M. Johnson, Ashutos Parhi, P. Sharma","doi":"10.1115/imece2022-97022","DOIUrl":"https://doi.org/10.1115/imece2022-97022","url":null,"abstract":"\u0000 Conventional spray nozzles are used in industries to atomize fluids for many applications. But these nozzles cannot atomize fluids having large viscosities and non-Newtonian characteristics. Dairy fluids like whey suspensions are examples of such fluids. Nozzles used in atomization of such suspensions for spray drying only operate with fluids having high water content. Atomizing suspensions with low water content will conserve energy by lowering the load on the spray dryer. In this study, we have used Filament Extension Atomization (FEA) technology to spray sweet dry whey suspension at 80% solids loading and Whey Protein Concentrate (WPC 80) at 50% solids loading. These concentrations are 30% above current industrial standards. We present our formulation techniques and non-Newtonian rheology characterization of the suspensions. By spraying the suspensions with FEA, we demonstrate tight control over drop size distribution in the spray with a D50 < 200 μm. Finally, we present a novel design for high throughput spraying of such dairy suspensions to be incorporated into industrial spray dryers.","PeriodicalId":292222,"journal":{"name":"Volume 8: Fluids Engineering; Heat Transfer and Thermal Engineering","volume":"191 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132135639","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}
P. Sai Sudhir, Gangchen Ren, A. Chuttar, N. Shettigar, D. Banerjee
In this paper, machine learning (ML) techniques, more specifically artificial neural networks (ANN), are utilized to enhance the efficacy of Cold Finger Technique (CFT). Experiments were conducted by melting the PCM at different values of power input to an electrical heater (mounted at the base of the container and immersed in PCM). Temperature transients were recorded by three thermocouples that were mounted at locations corresponding to liquid-meniscus heights for melt fraction values of 30%, 60% and 85%. The surface temperature transients were measured using thermocouples mounted on the exterior of the container surface that were mounted at locations corresponding to liquid-meniscus heights for melt fraction values of 30%, 60% and 90%. The surface temperature transients afford a cheap, reliable and cost-effective option for predicting the required values in real-time (i.e., the time remaining to attain a desired melt fraction, say 85%, at any particular instant during the melting cycle). These results validated the approach reported by (Chuttar et al. 2022). The average prediction error in the last half hour (before reaching a target melt fraction of 85%) was less than 10 minutes for all but one of the datasets. The Mean Absolute Percentage Error (MAPE) was as low as 11% for some of the predicted values of the datasets.
本文利用机器学习(ML)技术，特别是人工神经网络(ANN)来提高冷指技术(CFT)的有效性。实验是通过在不同功率输入值下熔化PCM进行的，电加热器安装在容器底部并浸入PCM中。温度瞬态记录由三个热电偶安装在相应位置的液体半月板高度，熔体分数值为30%，60%和85%。使用安装在容器表面外部的热电偶测量表面温度瞬变，热电偶安装在液体半月板高度对应的位置，熔体分数值为30%，60%和90%。表面温度瞬变为实时预测所需值提供了一种廉价、可靠和具有成本效益的选择(即，在熔化周期的任何特定时刻达到所需熔化分数的剩余时间，例如85%)。这些结果验证了(Chuttar et al. 2022)报告的方法。除一个数据集外，最后半小时(在达到目标熔体分数85%之前)的平均预测误差小于10分钟。对于某些数据集的预测值，平均绝对百分比误差(MAPE)低至11%。
{"title":"Deploying Machine Learning (ML) for Improving Reliability and Resiliency of Thermal Energy Storage (TES) Platforms by Leveraging Phase Change Materials (PCM) for Sustainability Applications and Mitigating Food-Energy-Water (FEW) Nexus","authors":"P. Sai Sudhir, Gangchen Ren, A. Chuttar, N. Shettigar, D. Banerjee","doi":"10.1115/imece2022-97121","DOIUrl":"https://doi.org/10.1115/imece2022-97121","url":null,"abstract":"\u0000 In this paper, machine learning (ML) techniques, more specifically artificial neural networks (ANN), are utilized to enhance the efficacy of Cold Finger Technique (CFT). Experiments were conducted by melting the PCM at different values of power input to an electrical heater (mounted at the base of the container and immersed in PCM). Temperature transients were recorded by three thermocouples that were mounted at locations corresponding to liquid-meniscus heights for melt fraction values of 30%, 60% and 85%. The surface temperature transients were measured using thermocouples mounted on the exterior of the container surface that were mounted at locations corresponding to liquid-meniscus heights for melt fraction values of 30%, 60% and 90%. The surface temperature transients afford a cheap, reliable and cost-effective option for predicting the required values in real-time (i.e., the time remaining to attain a desired melt fraction, say 85%, at any particular instant during the melting cycle). These results validated the approach reported by (Chuttar et al. 2022). The average prediction error in the last half hour (before reaching a target melt fraction of 85%) was less than 10 minutes for all but one of the datasets. The Mean Absolute Percentage Error (MAPE) was as low as 11% for some of the predicted values of the datasets.","PeriodicalId":292222,"journal":{"name":"Volume 8: Fluids Engineering; Heat Transfer and Thermal Engineering","volume":"160 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133934273","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 feed forward machine-learning (ML) model is applied to study bubble induced turbulence and bubble mass transfer in a bubble column reactor. Using direct numerical simulation data for forced turbulence, bubble deformations and flow velocities are predicted. To predict mass transfer, ML sub-grid scale (SGS) modeling technique is introduced for the concentration of reactants and products undergoing parallel competitive reactions in the oxidation of toluene. The ML model replaces the iterative approach associated with the use of analytical profiles for previous SGS models for correcting concentration profiles in boundary layers. The present model, thus, offers a significant performance bonus as well as the flexibility to extend to more complex scenarios due to its data-driven nature.
{"title":"Machine-Learning Approach to Modeling Oxidation of Toluene in a Bubble Column Reactor","authors":"Raihan Tayeb, Yuwen Zhang","doi":"10.1115/imece2022-94564","DOIUrl":"https://doi.org/10.1115/imece2022-94564","url":null,"abstract":"\u0000 A feed forward machine-learning (ML) model is applied to study bubble induced turbulence and bubble mass transfer in a bubble column reactor. Using direct numerical simulation data for forced turbulence, bubble deformations and flow velocities are predicted. To predict mass transfer, ML sub-grid scale (SGS) modeling technique is introduced for the concentration of reactants and products undergoing parallel competitive reactions in the oxidation of toluene. The ML model replaces the iterative approach associated with the use of analytical profiles for previous SGS models for correcting concentration profiles in boundary layers. The present model, thus, offers a significant performance bonus as well as the flexibility to extend to more complex scenarios due to its data-driven nature.","PeriodicalId":292222,"journal":{"name":"Volume 8: Fluids Engineering; Heat Transfer and Thermal Engineering","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134171909","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}
This work studies the design of a device conveying dust and sand in order to understand how the particles impinge, erode and rebound from a target plate. The motivation behind this study is understanding dust ingestion and erosion in aviation gas-turbine engines. Erosion in engines due to surface impact is an important factor contributing to their reduction in performance. Ingestion of small particles such as sand, ash and ice cause harm to the engine, which can eventually lead to engine failure. The trajectory and size of the particles play an important role in predicting the damage occurring in the engine. In this study, a system is designed to deliver particles at a certain concentration and velocity to a target plate. The purpose of the target plate is to study particle damage on a surface. The domain consists of a constant area duct in which particles are injected in the upstream direction using a particle seeder. The particles exit the duct through a converging nozzle where they are accelerated to the desired exit conditions. One of the criteria of the particle injection system is that it is designed to ensure that the particles are concentrated in the center of the constant area duct, reducing erosion along the walls. This motivates the need for the particles to be conveyed with minimal rebounds within the duct, as excessive rebounds would reduce the particle velocities and potentially lead to particle fragmentation. The computational fluid dynamics (CFD) model is developed to influence and guide the design of an experimental rig. This rig will be used to analyze particle trajectories as well as impact and rebound speeds from the target. Another goal of the rig is to provide an insight into particle fragmentation after impact. Having good CFD predictions of the particle aerodynamics prior to impact with the target is critical to ensuring that the CFD simulation data is able to provide results that will ensure the reliability of the experiments. This research analyzes the aerodynamic effects of the flow on particles of various sizes as they impact a target surface. Particles respond differently to changes in the flow field based on their diameter, and so a discussion about their diameters is relevant. The smallest particle sizes follow the streamlines and act as tracers, while the larger particles tend to be more ballistic and are mostly unaffected by the change in flow. The angle of the target plate is also varied to observe the effects on the incoming particle trajectories. The variation in angle leads to different flow fields forming upstream of the target plate which in turn affects the particle dynamics as well as their impact and rebound properties. These studies are conducted to gain an understanding of how the dynamics of particle size and target plate angle affects the impact velocities and erosion. Two exit Mach Number (Mexit = 0.25, 0.7) configurations with particle diameters ranging from 20 micrometers to 200 micrometers are
为了了解颗粒如何从靶板上撞击、侵蚀和反弹，本工作研究了粉尘和沙子输送装置的设计。这项研究背后的动机是了解航空燃气涡轮发动机的尘埃摄入和侵蚀。由于地面撞击造成的发动机腐蚀是导致发动机性能下降的一个重要因素。吸入沙子、灰尘和冰等小颗粒会对发动机造成伤害，最终可能导致发动机故障。颗粒的运动轨迹和大小对预测发动机的损伤起着重要的作用。在这项研究中，设计了一个系统，以一定的浓度和速度将颗粒输送到目标板上。目标板的目的是研究颗粒在表面上的损伤。该区域由一个恒定面积的管道组成，其中粒子使用粒子播种机在上游方向注入。颗粒通过一个收敛喷嘴出口管道，在那里它们被加速到所需的出口条件。颗粒注入系统的标准之一是，它的设计要确保颗粒集中在等面积风管的中心，减少沿壁的侵蚀。这促使颗粒在管道内以最小的回弹传输，因为过度的回弹会降低颗粒速度，并可能导致颗粒破碎。为了影响和指导实验装置的设计，建立了计算流体动力学(CFD)模型。该装置将用于分析粒子轨迹以及目标的撞击和反弹速度。该设备的另一个目标是提供对撞击后颗粒破碎的洞察。在与目标碰撞之前，对颗粒空气动力学进行良好的CFD预测对于确保CFD模拟数据能够提供能够确保实验可靠性的结果至关重要。本研究分析了不同大小的颗粒在撞击目标表面时所产生的气动效应。颗粒的直径不同，对流场变化的响应也不同，因此对其直径的讨论是有意义的。最小的颗粒尺寸遵循流线并充当示踪剂，而较大的颗粒往往更具弹道性，并且大多数不受流量变化的影响。改变靶板的角度，观察对入射粒子轨迹的影响。角度的变化会导致靶板上游形成不同的流场，从而影响颗粒的动力学及其冲击和回弹性能。进行这些研究是为了了解颗粒大小和靶板角度的动力学如何影响冲击速度和侵蚀。两种出口马赫数(Mexit = 0.25, 0.7)配置，颗粒直径范围为20微米至200微米，以影响即将进行的实验。分析和比较了这些构型对靶板附近颗粒的气动影响。CFD模拟使用商用软件StarCCM+进行。采用Reynolds average Navier Stokes (RANS) CFD技术，结合拉格朗日粒子跟踪模型，对流动物理和粒子运动进行了分析。采用两方程可实现的k-ε RANS模型来模拟湍流物理;气相与拉格朗日粒子相是双向耦合的。拉格朗日方程使用Holzer-Sommerfeld相关计算粒子周围的阻力，并使用Sommerfeld相关计算剪切升力。
{"title":"A Computational Analysis of the Aerodynamic Effects on Particles Flowing From a Duct","authors":"Cairen J. Miranda, John S. Palmore","doi":"10.1115/imece2022-96748","DOIUrl":"https://doi.org/10.1115/imece2022-96748","url":null,"abstract":"\u0000 This work studies the design of a device conveying dust and sand in order to understand how the particles impinge, erode and rebound from a target plate. The motivation behind this study is understanding dust ingestion and erosion in aviation gas-turbine engines. Erosion in engines due to surface impact is an important factor contributing to their reduction in performance. Ingestion of small particles such as sand, ash and ice cause harm to the engine, which can eventually lead to engine failure. The trajectory and size of the particles play an important role in predicting the damage occurring in the engine.\u0000 In this study, a system is designed to deliver particles at a certain concentration and velocity to a target plate. The purpose of the target plate is to study particle damage on a surface. The domain consists of a constant area duct in which particles are injected in the upstream direction using a particle seeder. The particles exit the duct through a converging nozzle where they are accelerated to the desired exit conditions. One of the criteria of the particle injection system is that it is designed to ensure that the particles are concentrated in the center of the constant area duct, reducing erosion along the walls. This motivates the need for the particles to be conveyed with minimal rebounds within the duct, as excessive rebounds would reduce the particle velocities and potentially lead to particle fragmentation. The computational fluid dynamics (CFD) model is developed to influence and guide the design of an experimental rig. This rig will be used to analyze particle trajectories as well as impact and rebound speeds from the target. Another goal of the rig is to provide an insight into particle fragmentation after impact. Having good CFD predictions of the particle aerodynamics prior to impact with the target is critical to ensuring that the CFD simulation data is able to provide results that will ensure the reliability of the experiments.\u0000 This research analyzes the aerodynamic effects of the flow on particles of various sizes as they impact a target surface. Particles respond differently to changes in the flow field based on their diameter, and so a discussion about their diameters is relevant. The smallest particle sizes follow the streamlines and act as tracers, while the larger particles tend to be more ballistic and are mostly unaffected by the change in flow. The angle of the target plate is also varied to observe the effects on the incoming particle trajectories. The variation in angle leads to different flow fields forming upstream of the target plate which in turn affects the particle dynamics as well as their impact and rebound properties. These studies are conducted to gain an understanding of how the dynamics of particle size and target plate angle affects the impact velocities and erosion. Two exit Mach Number (Mexit = 0.25, 0.7) configurations with particle diameters ranging from 20 micrometers to 200 micrometers are","PeriodicalId":292222,"journal":{"name":"Volume 8: Fluids Engineering; Heat Transfer and Thermal Engineering","volume":"66 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132501585","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}
Potentially, for hypersonic access to space vehicles, the scramjet engine is the propulsion system of choice and will be required to operate in a variety of flight conditions. In many cases, the freestream dynamic pressure may be held constant, however, the Mach numbers may range from 4 to 12. Operating in such a broad Mach range, will in turn require the combustor to accommodate varying conditions. Computational Fluid Dynamics as an engineering tool has been used in this paper to analyze be fluid field physics within a scramjet isolator. Currently, with proven capability to diagnose scramjet isolator design challenges, especially those tools that will predict and prevent unstarts, are lacking. To overcome these challenges, the Integro-Differential Scheme (IDS), which was developed and improved in Ref [1–2], is used in the computational analyses’ aspects of this effort. In addition, the numerical model is designed with back-pressure manipulation capability that seeks to influence the real-time flow behavior within the isolator based on experiment. The base-line scramjet isolator is model after a Mach 1.8 isolator with a length to height ratio of 8.40 has been simulated in this paper. The aerodynamic conditions used in the design of the numerical model was extracted from the experimental data presented in Ref. [3]. The flow physics within the isolator numerical model was studied under two sets of back pressure conditions; namely, (a) natural designed condition and (b) fixed adverse conditions. It is noteworthy to mention, backpressure studies were conducted through the use of ‘smooth’ and ‘discrete’ pressure jumps. In addition, the backpressure conditions were allowed to vary real-time as the flow structures within the isolator were observed. The engineering analysis conducted herein demonstrated results that are in excellent agreement with the available experimental data. It was observed that under design conditions, the isolator flow field consisted of an oblique shock train, which was strongest closest to the entrance of the isolator. Also, it was observed during each ‘discrete’ change in back pressure value, a wave, comprising of a coupled pair of oblique shocks and a normal shock, resembling the ‘lambda shock pattern’ emerges from the exit of the isolator. During each test, this ‘lambda shock’ travels to the front of the isolator, interacting with and dominating each set of reflected waves along its path. In each case, the lambda shock interacts with the front-most and strongest pair of oblique shocks, rocking back and forth before the entire isolator flow field settles down into a new configuration. This process intensifies as the back pressure discrete jump increases in strength, and the oblique shock train transformed into a form that closely mimics a normal shock train, with the strongest ‘lambda shock’ at the head of the isolator. In general, it appears as if the isolator flow patterned itself as a flexible spring within the constant
{"title":"Controlling the Flow Structures Within a Scramjet Isolator With Backpressure Manipulations","authors":"F. Ferguson, Dehua Feng, Yang Gao","doi":"10.1115/imece2022-96157","DOIUrl":"https://doi.org/10.1115/imece2022-96157","url":null,"abstract":"\u0000 Potentially, for hypersonic access to space vehicles, the scramjet engine is the propulsion system of choice and will be required to operate in a variety of flight conditions. In many cases, the freestream dynamic pressure may be held constant, however, the Mach numbers may range from 4 to 12. Operating in such a broad Mach range, will in turn require the combustor to accommodate varying conditions. Computational Fluid Dynamics as an engineering tool has been used in this paper to analyze be fluid field physics within a scramjet isolator. Currently, with proven capability to diagnose scramjet isolator design challenges, especially those tools that will predict and prevent unstarts, are lacking. To overcome these challenges, the Integro-Differential Scheme (IDS), which was developed and improved in Ref [1–2], is used in the computational analyses’ aspects of this effort. In addition, the numerical model is designed with back-pressure manipulation capability that seeks to influence the real-time flow behavior within the isolator based on experiment. The base-line scramjet isolator is model after a Mach 1.8 isolator with a length to height ratio of 8.40 has been simulated in this paper. The aerodynamic conditions used in the design of the numerical model was extracted from the experimental data presented in Ref. [3]. The flow physics within the isolator numerical model was studied under two sets of back pressure conditions; namely, (a) natural designed condition and (b) fixed adverse conditions. It is noteworthy to mention, backpressure studies were conducted through the use of ‘smooth’ and ‘discrete’ pressure jumps. In addition, the backpressure conditions were allowed to vary real-time as the flow structures within the isolator were observed.\u0000 The engineering analysis conducted herein demonstrated results that are in excellent agreement with the available experimental data. It was observed that under design conditions, the isolator flow field consisted of an oblique shock train, which was strongest closest to the entrance of the isolator. Also, it was observed during each ‘discrete’ change in back pressure value, a wave, comprising of a coupled pair of oblique shocks and a normal shock, resembling the ‘lambda shock pattern’ emerges from the exit of the isolator. During each test, this ‘lambda shock’ travels to the front of the isolator, interacting with and dominating each set of reflected waves along its path. In each case, the lambda shock interacts with the front-most and strongest pair of oblique shocks, rocking back and forth before the entire isolator flow field settles down into a new configuration. This process intensifies as the back pressure discrete jump increases in strength, and the oblique shock train transformed into a form that closely mimics a normal shock train, with the strongest ‘lambda shock’ at the head of the isolator. In general, it appears as if the isolator flow patterned itself as a flexible spring within the constant ","PeriodicalId":292222,"journal":{"name":"Volume 8: Fluids Engineering; Heat Transfer and Thermal Engineering","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133113569","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}
Julie Shafer, Jong-Hang Lee, A. Thyagarajan, D. Banerjee
Recent advances in micro/nano-fabrication has enabled the deployment of nanostructured surfaces, nanochannels, and nanoporous membranes for development of new generation thermal management devices with remarkable potential for heat transfer enhancement. Anomalous heat transfer has been reported in studies involving heaters with nanostructured surfaces. For example, nanofins with lower thermal conductivity values can cause higher levels of enhancement in heat flux values, especially during phase change (such as for boiling on heaters with nanostructured surfaces). In addition, confinement of fluid in nanopores can also result in anomalous properties. This is manifest in anomalous production curves during hydraulic fracturing operations in oil and gas applications. A transport model that resolves these conundrums is termed as the “nanoFin Effect (nFE)”. nFE is governed by interfacial phenomena, i.e., the formation of thermal impedances in parallel circuit configuration, consisting of: (a) interfacial thermal resistance (also known as “Kapitza resistance”); (b) thermal capacitor; and (c) thermal diode (that form at the interface between each nanoparticle and the surface adsorbed thin-film of solvent molecules). nFE (i.e., primarily the interfacial thermal diode effect) also leads to preferential trapping of ions on the surface adsorbed thin film of solvent molecules leading to very high concentration gradients causing drastic reduction in corrosion. The motivation of this study was to explore nFE during thin film evaporation from nanopores. The methods used in this study include mounting a nano-thermocouple array (also termed as Thin Film Thermocouples or “TFT”) on a hot plate and observing the transient response recorded by the TFT array when a small liquid droplet (of fixed mass or volume) is dispensed on to an anisotropic AAO membrane containing nanopores. In this study, two different pore sizes were explored: 200 nm and 10 nm. The experiments were performed using isopropyl alcohol (IPA) droplets for four different temperature settings of the heated membrane (containing the nanopores).
{"title":"Experimental Study of the Nano-Fin Effect (nFE) During Thin Film Evaporation From Nanopores in Anodic Aluminum Oxide (AAO) Membrane Substrates Integrated With Nano-Thermocouple / Thin Film Thermocouple (TFT) Array","authors":"Julie Shafer, Jong-Hang Lee, A. Thyagarajan, D. Banerjee","doi":"10.1115/imece2022-96168","DOIUrl":"https://doi.org/10.1115/imece2022-96168","url":null,"abstract":"\u0000 Recent advances in micro/nano-fabrication has enabled the deployment of nanostructured surfaces, nanochannels, and nanoporous membranes for development of new generation thermal management devices with remarkable potential for heat transfer enhancement. Anomalous heat transfer has been reported in studies involving heaters with nanostructured surfaces. For example, nanofins with lower thermal conductivity values can cause higher levels of enhancement in heat flux values, especially during phase change (such as for boiling on heaters with nanostructured surfaces). In addition, confinement of fluid in nanopores can also result in anomalous properties. This is manifest in anomalous production curves during hydraulic fracturing operations in oil and gas applications. A transport model that resolves these conundrums is termed as the “nanoFin Effect (nFE)”.\u0000 nFE is governed by interfacial phenomena, i.e., the formation of thermal impedances in parallel circuit configuration, consisting of: (a) interfacial thermal resistance (also known as “Kapitza resistance”); (b) thermal capacitor; and (c) thermal diode (that form at the interface between each nanoparticle and the surface adsorbed thin-film of solvent molecules). nFE (i.e., primarily the interfacial thermal diode effect) also leads to preferential trapping of ions on the surface adsorbed thin film of solvent molecules leading to very high concentration gradients causing drastic reduction in corrosion.\u0000 The motivation of this study was to explore nFE during thin film evaporation from nanopores. The methods used in this study include mounting a nano-thermocouple array (also termed as Thin Film Thermocouples or “TFT”) on a hot plate and observing the transient response recorded by the TFT array when a small liquid droplet (of fixed mass or volume) is dispensed on to an anisotropic AAO membrane containing nanopores. In this study, two different pore sizes were explored: 200 nm and 10 nm. The experiments were performed using isopropyl alcohol (IPA) droplets for four different temperature settings of the heated membrane (containing the nanopores).","PeriodicalId":292222,"journal":{"name":"Volume 8: Fluids Engineering; Heat Transfer and Thermal Engineering","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129292205","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}
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