Clémence Rubiella, Ho-June Byun, Youchan Park, Hyungrok Do
In this experimental study, we are presenting the ability of laser-induced plasmas with successive pulsation to identify combustion instabilities (CI) of a premixed lab-scale combustor. An acoustic disturbance equivalent to a shockwave perturbation is generated in the main air supply line of a swirled injector prior to the fuel addition by focusing nanosecond laser pulses of 1.6 W average power at 10 Hz. The shockwaves are attenuated to be strong pressure waves when reaching the combustor and impact the pressure field for short periods. After plasma breakdowns, the system returns back to its original state after 4 ms once the added acoustic energy has been fully dissipated. Given a set geometry, it is observed that the laser-induced breakdown amplifies the characteristic frequency peaks of the combustor system when actuated in cold flow. Furthermore, when applied to reacting flows, the pulsating acoustic perturbations impact the pressure fluctuation in the combustor, e.g., reducing the amplitude of the primary characteristic frequency peak at certain conditions. The identification of the main instability modes thanks to the plasma shockwave provides proof of the potential use of this novel diagnosis strategy in various and complex combustion systems.
{"title":"Novel Combustion Instability Diagnosis Method with Upstream Pulsation of Repetitive Laser-Induced Plasmas","authors":"Clémence Rubiella, Ho-June Byun, Youchan Park, Hyungrok Do","doi":"10.1115/1.4064727","DOIUrl":"https://doi.org/10.1115/1.4064727","url":null,"abstract":"\u0000 In this experimental study, we are presenting the ability of laser-induced plasmas with successive pulsation to identify combustion instabilities (CI) of a premixed lab-scale combustor. An acoustic disturbance equivalent to a shockwave perturbation is generated in the main air supply line of a swirled injector prior to the fuel addition by focusing nanosecond laser pulses of 1.6 W average power at 10 Hz. The shockwaves are attenuated to be strong pressure waves when reaching the combustor and impact the pressure field for short periods. After plasma breakdowns, the system returns back to its original state after 4 ms once the added acoustic energy has been fully dissipated. Given a set geometry, it is observed that the laser-induced breakdown amplifies the characteristic frequency peaks of the combustor system when actuated in cold flow. Furthermore, when applied to reacting flows, the pulsating acoustic perturbations impact the pressure fluctuation in the combustor, e.g., reducing the amplitude of the primary characteristic frequency peak at certain conditions. The identification of the main instability modes thanks to the plasma shockwave provides proof of the potential use of this novel diagnosis strategy in various and complex combustion systems.","PeriodicalId":508252,"journal":{"name":"Journal of Engineering for Gas Turbines and Power","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139840239","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}
Unsteady flow distortion is of interest for the development air-breathing propulsion systems. These stochastic fluctuations can generate incompatibilities between intakes and aero-engines. Observing the extreme flow distortion events during experimental testing is not guaranteed and statistical models such as Extreme Value Theory (EVT) can be used to estimate the occurrence and magnitude of the fluctuations. However, the current industry standard does not provide guidance on how to apply these methods to obtain useful predictions. This work proposes a systematic process to assess the required number of observations for obtaining statistical convergence of the EVT predictions. This is achieved through shuffling of the data samples and relies on the availability of a sufficiently large initial dataset. This can be adopted by gas turbine engineers to evaluate the data recording requirements and to potentially reduce costs associated with experimental programs.
{"title":"Evaluation of Extreme Value Predictions for Unsteady Flow Distortion of Aero-Engine Intakes","authors":"Matteo Migliorini, P. Zachos, D. MacManus","doi":"10.1115/1.4064728","DOIUrl":"https://doi.org/10.1115/1.4064728","url":null,"abstract":"\u0000 Unsteady flow distortion is of interest for the development air-breathing propulsion systems. These stochastic fluctuations can generate incompatibilities between intakes and aero-engines. Observing the extreme flow distortion events during experimental testing is not guaranteed and statistical models such as Extreme Value Theory (EVT) can be used to estimate the occurrence and magnitude of the fluctuations. However, the current industry standard does not provide guidance on how to apply these methods to obtain useful predictions. This work proposes a systematic process to assess the required number of observations for obtaining statistical convergence of the EVT predictions. This is achieved through shuffling of the data samples and relies on the availability of a sufficiently large initial dataset. This can be adopted by gas turbine engineers to evaluate the data recording requirements and to potentially reduce costs associated with experimental programs.","PeriodicalId":508252,"journal":{"name":"Journal of Engineering for Gas Turbines and Power","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139841783","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}
Clémence Rubiella, Ho-June Byun, Youchan Park, Hyungrok Do
In this experimental study, we are presenting the ability of laser-induced plasmas with successive pulsation to identify combustion instabilities (CI) of a premixed lab-scale combustor. An acoustic disturbance equivalent to a shockwave perturbation is generated in the main air supply line of a swirled injector prior to the fuel addition by focusing nanosecond laser pulses of 1.6 W average power at 10 Hz. The shockwaves are attenuated to be strong pressure waves when reaching the combustor and impact the pressure field for short periods. After plasma breakdowns, the system returns back to its original state after 4 ms once the added acoustic energy has been fully dissipated. Given a set geometry, it is observed that the laser-induced breakdown amplifies the characteristic frequency peaks of the combustor system when actuated in cold flow. Furthermore, when applied to reacting flows, the pulsating acoustic perturbations impact the pressure fluctuation in the combustor, e.g., reducing the amplitude of the primary characteristic frequency peak at certain conditions. The identification of the main instability modes thanks to the plasma shockwave provides proof of the potential use of this novel diagnosis strategy in various and complex combustion systems.
{"title":"Novel Combustion Instability Diagnosis Method with Upstream Pulsation of Repetitive Laser-Induced Plasmas","authors":"Clémence Rubiella, Ho-June Byun, Youchan Park, Hyungrok Do","doi":"10.1115/1.4064727","DOIUrl":"https://doi.org/10.1115/1.4064727","url":null,"abstract":"\u0000 In this experimental study, we are presenting the ability of laser-induced plasmas with successive pulsation to identify combustion instabilities (CI) of a premixed lab-scale combustor. An acoustic disturbance equivalent to a shockwave perturbation is generated in the main air supply line of a swirled injector prior to the fuel addition by focusing nanosecond laser pulses of 1.6 W average power at 10 Hz. The shockwaves are attenuated to be strong pressure waves when reaching the combustor and impact the pressure field for short periods. After plasma breakdowns, the system returns back to its original state after 4 ms once the added acoustic energy has been fully dissipated. Given a set geometry, it is observed that the laser-induced breakdown amplifies the characteristic frequency peaks of the combustor system when actuated in cold flow. Furthermore, when applied to reacting flows, the pulsating acoustic perturbations impact the pressure fluctuation in the combustor, e.g., reducing the amplitude of the primary characteristic frequency peak at certain conditions. The identification of the main instability modes thanks to the plasma shockwave provides proof of the potential use of this novel diagnosis strategy in various and complex combustion systems.","PeriodicalId":508252,"journal":{"name":"Journal of Engineering for Gas Turbines and Power","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139780598","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}
Unsteady flow distortion is of interest for the development air-breathing propulsion systems. These stochastic fluctuations can generate incompatibilities between intakes and aero-engines. Observing the extreme flow distortion events during experimental testing is not guaranteed and statistical models such as Extreme Value Theory (EVT) can be used to estimate the occurrence and magnitude of the fluctuations. However, the current industry standard does not provide guidance on how to apply these methods to obtain useful predictions. This work proposes a systematic process to assess the required number of observations for obtaining statistical convergence of the EVT predictions. This is achieved through shuffling of the data samples and relies on the availability of a sufficiently large initial dataset. This can be adopted by gas turbine engineers to evaluate the data recording requirements and to potentially reduce costs associated with experimental programs.
{"title":"Evaluation of Extreme Value Predictions for Unsteady Flow Distortion of Aero-Engine Intakes","authors":"Matteo Migliorini, P. Zachos, D. MacManus","doi":"10.1115/1.4064728","DOIUrl":"https://doi.org/10.1115/1.4064728","url":null,"abstract":"\u0000 Unsteady flow distortion is of interest for the development air-breathing propulsion systems. These stochastic fluctuations can generate incompatibilities between intakes and aero-engines. Observing the extreme flow distortion events during experimental testing is not guaranteed and statistical models such as Extreme Value Theory (EVT) can be used to estimate the occurrence and magnitude of the fluctuations. However, the current industry standard does not provide guidance on how to apply these methods to obtain useful predictions. This work proposes a systematic process to assess the required number of observations for obtaining statistical convergence of the EVT predictions. This is achieved through shuffling of the data samples and relies on the availability of a sufficiently large initial dataset. This can be adopted by gas turbine engineers to evaluate the data recording requirements and to potentially reduce costs associated with experimental programs.","PeriodicalId":508252,"journal":{"name":"Journal of Engineering for Gas Turbines and Power","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139781953","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}
Tadbhagya Kumar, Pinaki Pal, Sicong Wu, Austin Nunno, Opeoluwa Owoyele, Michael Joly, D. Tretiak
In this work, a priori analysis of machine learning strategies is carried out with the goal of data-driven wall modeling for large eddy simulation (LES) of gas turbine film cooling flows. High-fidelity flow datasets are extracted from wall-resolved LES of flow over a flat plate interacting with the coolant flow supplied by a single row of 7-7-7 shaped cooling holes inclined at 30 degrees with the flat plate at different blowing ratios. Light Gradient Boosting Machine is employed as the ML algorithm for the data-driven wall model. Parametric tests are conducted to systematically assess the influence of a wide range of input flow features (velocity components, velocity gradients, pressure gradients, and fluid properties) on the accuracy of the ML wall model with respect to prediction of wall shear stress. In addition, the use of spatial stencil and time delay is also explored within the ML wall modeling framework. It is shown that features associated with gradients of the streamwise and spanwise velocity components have a major impact on the prediction fidelity of wall model, while the effect of gradients of the wall-normal velocity component is found to be negligible. Moreover, adding flow feature information from an x-y-z spatial stencil significantly improves the ML model accuracy and generalizability compared to just using local flow features from the matching location. Overall, best model performance is achieved when both spatial stencil and time delay features are incorporated within the data-driven wall modeling paradigm.
本研究对机器学习策略进行了先验分析，目的是为燃气轮机薄膜冷却流的大涡模拟（LES）建立数据驱动的壁面模型。从壁面分辨 LES 中提取了高保真流动数据集，这些数据集是平板上的流动与由与平板成 30 度倾斜的单排 7-7-7 形冷却孔以不同吹气比提供的冷却剂流相互作用的结果。数据驱动的壁面模型采用光梯度提升机作为 ML 算法。通过参数测试，系统地评估了各种输入流动特征（速度分量、速度梯度、压力梯度和流体特性）对 ML 壁模型预测壁面剪应力精度的影响。此外，还在 ML 壁模型框架内探讨了空间模版和时间延迟的使用。结果表明，与流向和跨向速度分量梯度相关的特征对壁模型的预测保真度有很大影响，而壁法向速度分量梯度的影响可以忽略不计。此外，与仅使用匹配位置的局部流动特征相比，添加来自 x-yz 空间模版的流动特征信息可显著提高 ML 模型的准确性和普适性。总之，在数据驱动的壁面建模范例中同时加入空间模版和时间延迟特征时，可以获得最佳的模型性能。
{"title":"Assessment of Machine Learning Wall Modeling Approaches for Large Eddy Simulation of Gas Turbine Film Cooling Flows: An a Priori Study","authors":"Tadbhagya Kumar, Pinaki Pal, Sicong Wu, Austin Nunno, Opeoluwa Owoyele, Michael Joly, D. Tretiak","doi":"10.1115/1.4064556","DOIUrl":"https://doi.org/10.1115/1.4064556","url":null,"abstract":"\u0000 In this work, a priori analysis of machine learning strategies is carried out with the goal of data-driven wall modeling for large eddy simulation (LES) of gas turbine film cooling flows. High-fidelity flow datasets are extracted from wall-resolved LES of flow over a flat plate interacting with the coolant flow supplied by a single row of 7-7-7 shaped cooling holes inclined at 30 degrees with the flat plate at different blowing ratios. Light Gradient Boosting Machine is employed as the ML algorithm for the data-driven wall model. Parametric tests are conducted to systematically assess the influence of a wide range of input flow features (velocity components, velocity gradients, pressure gradients, and fluid properties) on the accuracy of the ML wall model with respect to prediction of wall shear stress. In addition, the use of spatial stencil and time delay is also explored within the ML wall modeling framework. It is shown that features associated with gradients of the streamwise and spanwise velocity components have a major impact on the prediction fidelity of wall model, while the effect of gradients of the wall-normal velocity component is found to be negligible. Moreover, adding flow feature information from an x-y-z spatial stencil significantly improves the ML model accuracy and generalizability compared to just using local flow features from the matching location. Overall, best model performance is achieved when both spatial stencil and time delay features are incorporated within the data-driven wall modeling paradigm.","PeriodicalId":508252,"journal":{"name":"Journal of Engineering for Gas Turbines and Power","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139597477","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 primary purpose of this study is the reduction of local entropy production in a contra-rotating stage. As such, the unsteady flow phenomena and the impact of radial load distribution on these phenomena and local entropy production need to be clarified. In this study, the SBES turbulence model is utilized to capture the vortices in the flow separation zone, and the γ-Reθ transition model is employed to predict the transition phenomenon within the boundary layer. Entropy production rate models suitable for different turbulence models are constructed separately to calculate local entropy production. Vortex visualization is achieved according to the Lambda_ci criterion, and the relative vorticity change rate is used to analyze the components of the tip clearance vortices. The transition phenomenon is analyzed from the perspectives of both the Euler and the Lagrange descriptions. The primary findings can be summarized as follows: The transition begins earlier and progresses more rapidly in the rear rotor. Wake propagation, occurring at double the frequency, entropy production rate within the boundary layer changes in synchrony with the wall shear stress at the same frequency. Additionally, an investigation of the tip clearance vortices concludes that the main structure of the tip clearance vortices coincides with the flow pattern of the high entropy production rate region, and the flow structure related to the high divergence area is essential for considering subsequent optimization with the aim of reducing the entropy production rate.
{"title":"Numerical Analysis of Unsteady Phenomena in a Contra-Rotating Stage Based On the Reduction of Local Entropy Production","authors":"Xingyu Jia, Xi Zhang, Qiushuang Yan, Zicheng Zhao","doi":"10.1115/1.4064557","DOIUrl":"https://doi.org/10.1115/1.4064557","url":null,"abstract":"\u0000 The primary purpose of this study is the reduction of local entropy production in a contra-rotating stage. As such, the unsteady flow phenomena and the impact of radial load distribution on these phenomena and local entropy production need to be clarified. In this study, the SBES turbulence model is utilized to capture the vortices in the flow separation zone, and the γ-Reθ transition model is employed to predict the transition phenomenon within the boundary layer. Entropy production rate models suitable for different turbulence models are constructed separately to calculate local entropy production. Vortex visualization is achieved according to the Lambda_ci criterion, and the relative vorticity change rate is used to analyze the components of the tip clearance vortices. The transition phenomenon is analyzed from the perspectives of both the Euler and the Lagrange descriptions. The primary findings can be summarized as follows: The transition begins earlier and progresses more rapidly in the rear rotor. Wake propagation, occurring at double the frequency, entropy production rate within the boundary layer changes in synchrony with the wall shear stress at the same frequency. Additionally, an investigation of the tip clearance vortices concludes that the main structure of the tip clearance vortices coincides with the flow pattern of the high entropy production rate region, and the flow structure related to the high divergence area is essential for considering subsequent optimization with the aim of reducing the entropy production rate.","PeriodicalId":508252,"journal":{"name":"Journal of Engineering for Gas Turbines and Power","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139596118","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}
Ken Miura, Akemi Ito, Yuta Nakamura, Rina Yamada, Koichi Nishibe, Miyuki Usui, Naoki Iijima
Lubricating oil consumption (LOC) of engines causes particulate matter in exhaust gas and abnormal combustion like pre-ignition which becomes a serious problem in hydrogen engines. Lubricating oil transports upward into the combustion chamber of an engine via the sliding surface, the gap, and the side and back of a piston ring. The target of this study was clarifying the mechanism of oil flowing between an oil control ring lower flank and the groove which was the first entrance of lubricating oil supplied from the crank shaft. Oil film thickness at the lower flank of the oil control ring was measured by laser induced fluorescence method using optical fibers embedded in the lower flank of the ring groove. The measured oil film thickness was compared with forces acting on the lower rail of three-piece type oil control ring. The oil film thickness change was well explained using those forces and it was found that friction force at the sliding surface and pressure in the ring groove were dominant on the oil film thickness under all operating conditions tested in this study.
{"title":"A Study On the Oil Film Thickness Between the Lower Rail of Oil Control Ring and Lower Flank of Oil Control Ring Groove of an Engine","authors":"Ken Miura, Akemi Ito, Yuta Nakamura, Rina Yamada, Koichi Nishibe, Miyuki Usui, Naoki Iijima","doi":"10.1115/1.4064582","DOIUrl":"https://doi.org/10.1115/1.4064582","url":null,"abstract":"\u0000 Lubricating oil consumption (LOC) of engines causes particulate matter in exhaust gas and abnormal combustion like pre-ignition which becomes a serious problem in hydrogen engines. Lubricating oil transports upward into the combustion chamber of an engine via the sliding surface, the gap, and the side and back of a piston ring. The target of this study was clarifying the mechanism of oil flowing between an oil control ring lower flank and the groove which was the first entrance of lubricating oil supplied from the crank shaft. Oil film thickness at the lower flank of the oil control ring was measured by laser induced fluorescence method using optical fibers embedded in the lower flank of the ring groove. The measured oil film thickness was compared with forces acting on the lower rail of three-piece type oil control ring. The oil film thickness change was well explained using those forces and it was found that friction force at the sliding surface and pressure in the ring groove were dominant on the oil film thickness under all operating conditions tested in this study.","PeriodicalId":508252,"journal":{"name":"Journal of Engineering for Gas Turbines and Power","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139595631","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}
S. K. Oruganti, Roberto Torelli, Kenneth Kim, Eric Mayhew, Chol-Bum M. Kweon
Airborne compression ignition engines must operate with reliable ignition systems to achieve proper ignition at every cycle, particularly at high altitudes. Glow-plug-based ignition assistant (IA) devices can provide the necessary energy to preheat the fuel and ensure ignitability of the fuel-air mixture. Ignitability of liquid sprays can be facilitated via direct impingement onto the hot IA surface; however, this comes with adverse effects on the IA durability. Therefore, optimizing an IA's design requires detailed understanding of the physics of fuel spray impingement of superheated surfaces. To this end, this work aims to formulate a new phenomenological thermal spray-wall interaction framework for modeling the film boiling-induced heat transfer, atomization, and dispersion of fuel spray droplets impinging onto a superheated IA device. A qualitative comparison of the new phenomenological model is performed against optical experiments from the literature of an F-24 fuel spray injected onto an IA device located 12 mm away from the injector tip. The temperature of the IA was set at 1400 K. The fuel injection pressure was 400 bar, while the ambient gas pressure and temperature were 30 bar and 800 K, respectively. The performance of the phenomenological model is evaluated in comparison with two other state-of-art models from the literature. A qualitative analysis of the different spray and fuel-air mixture characteristics is performed to outline the differences in the predictions offered by the new phenomenological model and the two state-of-art spray-wall interaction models.
机载压燃发动机必须配备可靠的点火系统，才能在每个循环中实现正确点火，尤其是在高海拔地区。基于火花塞的点火辅助（IA）装置可提供预热燃料所需的能量，并确保燃料-空气混合物的可燃性。液体喷雾的可燃性可通过直接撞击到热的辅助点火装置表面来实现；但这会对辅助点火装置的耐用性产生不利影响。因此，要优化 IA 的设计，就必须详细了解燃料喷雾撞击过热表面的物理学原理。为此，这项工作旨在制定一个新的现象学热喷射-壁相互作用框架，用于模拟薄膜沸腾引起的热传导、雾化以及燃料喷射液滴撞击过热内燃机设备的分散。新的现象学模型与文献中的光学实验进行了定性比较，实验中，F-24 燃料喷射到距离喷射器顶端 12 毫米的 IA 设备上。IA 的温度设定为 1400 K。燃料喷射压力为 400 巴，环境气体压力和温度分别为 30 巴和 800 K。通过与文献中另外两个最新模型的比较，对现象模型的性能进行了评估。对不同的喷射和燃料-空气混合物特性进行了定性分析，以概述新的现象学模型和两种最先进的喷壁相互作用模型在预测结果上的差异。
{"title":"A Phenomenological Thermal Spray Wall Interaction Modeling Framework Applied to A High Temperature Ignition Assistant Device","authors":"S. K. Oruganti, Roberto Torelli, Kenneth Kim, Eric Mayhew, Chol-Bum M. Kweon","doi":"10.1115/1.4064481","DOIUrl":"https://doi.org/10.1115/1.4064481","url":null,"abstract":"\u0000 Airborne compression ignition engines must operate with reliable ignition systems to achieve proper ignition at every cycle, particularly at high altitudes. Glow-plug-based ignition assistant (IA) devices can provide the necessary energy to preheat the fuel and ensure ignitability of the fuel-air mixture. Ignitability of liquid sprays can be facilitated via direct impingement onto the hot IA surface; however, this comes with adverse effects on the IA durability. Therefore, optimizing an IA's design requires detailed understanding of the physics of fuel spray impingement of superheated surfaces. To this end, this work aims to formulate a new phenomenological thermal spray-wall interaction framework for modeling the film boiling-induced heat transfer, atomization, and dispersion of fuel spray droplets impinging onto a superheated IA device. A qualitative comparison of the new phenomenological model is performed against optical experiments from the literature of an F-24 fuel spray injected onto an IA device located 12 mm away from the injector tip. The temperature of the IA was set at 1400 K. The fuel injection pressure was 400 bar, while the ambient gas pressure and temperature were 30 bar and 800 K, respectively. The performance of the phenomenological model is evaluated in comparison with two other state-of-art models from the literature. A qualitative analysis of the different spray and fuel-air mixture characteristics is performed to outline the differences in the predictions offered by the new phenomenological model and the two state-of-art spray-wall interaction models.","PeriodicalId":508252,"journal":{"name":"Journal of Engineering for Gas Turbines and Power","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139530681","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}
As emissions regulations for greenhouse gas emissions become more strict, it is important to increase the efficiency of engines by improving on the design and operation. Current optimization methods involve performing large numbers of experimental investigations on physical engines or making use of detailed Computational Fluid Dynamics modeling efforts to provide visual and statistical insights on in-cylinder behavior. The latter still requires experimental data for model validation. Both of these methods share a common set of problems, that of being monetarily expensive and time consuming. Previous work has proposed an alternative method for engine optimization using machine learning (ML) models and experimental validation data to predict scalar values representing different parameters. With such models developed, one can then quickly iterate on operating conditions to find the point that maximizes an application-dependent reward function. While these ML methods provide information on individual performance parameters, they lack key information of in-cylinder indicators such as cylinder pressure traces and heat release curves that are traditionally used for performance analysis. This work details the process of implement- ing a Multilayer Perceptron (MLP) model capable of accurately predicting crank-angle resolved high-speed in-cylinder pressure using equivalence ratio, fuel injection pressure and injection timing as input features. It was demonstrated that the model was able to approximate engine behavior with mean squared error lower than 0.05 on a 1-55 range in the test set. This approach shows potential for greatly accelerating the optimization process in engine applications.
随着温室气体排放法规的日益严格，通过改进设计和操作来提高发动机效率显得尤为重要。目前的优化方法包括在物理发动机上进行大量实验研究，或利用详细的计算流体动力学建模工作来提供有关气缸内行为的直观和统计见解。后者仍然需要实验数据来验证模型。这两种方法都有一个共同的问题，那就是昂贵和耗时。之前的工作提出了一种发动机优化的替代方法，使用机器学习（ML）模型和实验验证数据来预测代表不同参数的标量值。有了这些已开发的模型，就可以快速迭代运行条件，以找到最大化与应用相关的奖励函数的点。虽然这些 ML 方法可以提供单个性能参数的信息，但它们缺乏气缸内指标的关键信息，例如传统上用于性能分析的气缸压力轨迹和热释放曲线。这项工作详细介绍了多层感知器（MLP）模型的实施过程，该模型能够使用等效比、燃油喷射压力和喷射正时作为输入特征，准确预测曲柄角度解析的高速气缸内压力。结果表明，该模型能够在测试集的 1-55 范围内以低于 0.05 的均方误差逼近发动机行为。这种方法显示了在发动机应用中大大加快优化过程的潜力。
{"title":"A Deep Learning Approach to Predict In-Cylinder Pressure of a Compression Ignition Engine","authors":"Rodrigo Ristow Hadlich, J. Loprete, D. Assanis","doi":"10.1115/1.4064480","DOIUrl":"https://doi.org/10.1115/1.4064480","url":null,"abstract":"\u0000 As emissions regulations for greenhouse gas emissions become more strict, it is important to increase the efficiency of engines by improving on the design and operation. Current optimization methods involve performing large numbers of experimental investigations on physical engines or making use of detailed Computational Fluid Dynamics modeling efforts to provide visual and statistical insights on in-cylinder behavior. The latter still requires experimental data for model validation. Both of these methods share a common set of problems, that of being monetarily expensive and time consuming. Previous work has proposed an alternative method for engine optimization using machine learning (ML) models and experimental validation data to predict scalar values representing different parameters. With such models developed, one can then quickly iterate on operating conditions to find the point that maximizes an application-dependent reward function. While these ML methods provide information on individual performance parameters, they lack key information of in-cylinder indicators such as cylinder pressure traces and heat release curves that are traditionally used for performance analysis. This work details the process of implement- ing a Multilayer Perceptron (MLP) model capable of accurately predicting crank-angle resolved high-speed in-cylinder pressure using equivalence ratio, fuel injection pressure and injection timing as input features. It was demonstrated that the model was able to approximate engine behavior with mean squared error lower than 0.05 on a 1-55 range in the test set. This approach shows potential for greatly accelerating the optimization process in engine applications.","PeriodicalId":508252,"journal":{"name":"Journal of Engineering for Gas Turbines and Power","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139531482","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}
Konstantinos I. Papadopoulos, V. Gkoutzamanis, A. Kalfas
This paper expands the one-engine-inoperative conventional oversizing consideration to account for aircraft propulsion systems with multiple energy sources and thrust-generating media. Components in a generic hybrid propulsion system are categorized into power-generation, power-transmission and thrust-generation. For a given architecture, each possible single component failure is simulated to identify elements affected or eliminated by the respective loss of power, through the use of connection matrices. Failures are linked to losses in supplied and propulsive power, creating a list of oversizing factors for all individual components. Each element is oversized according to its corresponding maximum oversizing rate, defining the ideally redundant propulsion system. Case studies for conventional, all-electric and hybrid-electric powertrains highlight the need for balancing the number of components between minimum excess power and increasing the probability of a failure. Additionally, it is shown that asymmetrical configurations should not have major imbalance of power to avoid significant oversizing. The proposed methodology is applied to a 19-passenger, commuter aircraft. Increasing oversizing rate close to ideal leads to lower optimum energy consumption and increases redundancy. However, payload capacity penalties are required, up to 4 passengers for ideal oversizing. Heavier variants without penalties are up to 4% more efficient in terms of energy-per-weight in their carrying capacity against counterparts of the same oversize rate with reduced payload capacity. The proposed method maintains the principles of the conventional oversizing process, and highlights the tradeoffs needed between redundancy and performance in sizing novel propulsion systems.
{"title":"Oversizing Novel Aircraft Propulsion Systems for Power Redundancy","authors":"Konstantinos I. Papadopoulos, V. Gkoutzamanis, A. Kalfas","doi":"10.1115/1.4064479","DOIUrl":"https://doi.org/10.1115/1.4064479","url":null,"abstract":"\u0000 This paper expands the one-engine-inoperative conventional oversizing consideration to account for aircraft propulsion systems with multiple energy sources and thrust-generating media. Components in a generic hybrid propulsion system are categorized into power-generation, power-transmission and thrust-generation. For a given architecture, each possible single component failure is simulated to identify elements affected or eliminated by the respective loss of power, through the use of connection matrices. Failures are linked to losses in supplied and propulsive power, creating a list of oversizing factors for all individual components. Each element is oversized according to its corresponding maximum oversizing rate, defining the ideally redundant propulsion system. Case studies for conventional, all-electric and hybrid-electric powertrains highlight the need for balancing the number of components between minimum excess power and increasing the probability of a failure. Additionally, it is shown that asymmetrical configurations should not have major imbalance of power to avoid significant oversizing. The proposed methodology is applied to a 19-passenger, commuter aircraft. Increasing oversizing rate close to ideal leads to lower optimum energy consumption and increases redundancy. However, payload capacity penalties are required, up to 4 passengers for ideal oversizing. Heavier variants without penalties are up to 4% more efficient in terms of energy-per-weight in their carrying capacity against counterparts of the same oversize rate with reduced payload capacity. The proposed method maintains the principles of the conventional oversizing process, and highlights the tradeoffs needed between redundancy and performance in sizing novel propulsion systems.","PeriodicalId":508252,"journal":{"name":"Journal of Engineering for Gas Turbines and Power","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139531217","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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