Article
Thermodynamics
Weijie Liu, Ranran Xue, Liang Zhang, Qian Yang, Huiru Wang
Summary: This experimental study investigates the nonlinear response of a premixed methane/air low-swirl flame to imposed acoustic excitation, revealing complex amplitude dependence of the flame at different frequencies and the influence of flame dynamics due to flame rollup and shear layer instabilities.
COMBUSTION AND FLAME
(2022)
Article
Computer Science, Interdisciplinary Applications
M. Fiore, R. Gojon, G. Saez-Mischlich, J. Gressier
Summary: This paper investigates the use of spectral proper orthogonal decomposition (SPOD) to characterize flow structures around the T106 low-pressure turbine cascade. The SPOD metric is based on hydrodynamic flow disturbances and is used to identify large energy disturbances and synchronization processes with incoming wakes. The input data for SPOD is obtained from large-eddy simulations of the T106 cascade.
COMPUTERS & FLUIDS
(2023)
Article
Construction & Building Technology
Yixun Liu, Chun-Ho Liu, Guy P. Brasseur, Christopher Y. H. Chao
Summary: The study implemented Proper orthogonal decomposition (POD) to analyze turbulence structures in the atmospheric surface layer (ASL) over real urban morphology, revealing potential impacts on urban wind risks and air quality. The results demonstrate the high capability of POD in reducing data dimensions and extracting flow characteristics, providing new insights for urban planning and air quality improvement.
SUSTAINABLE CITIES AND SOCIETY
(2023)
Article
Construction & Building Technology
Shahin Masoumi-Verki, Payam Gholamalipour, Fariborz Haghighat, Ursula Eicker
Summary: This study focuses on the impact of different stratification conditions on airflow and pollutant dispersion in urban areas. By simulating non-isothermal boundary layer airflow and concentration fields, it is found that unstable stratification has a greater effect on turbulence statistics and thermal stratification affects pollutant dispersion mechanisms.
BUILDING AND ENVIRONMENT
(2021)
Article
Engineering, Marine
Xiuqing Xing, My Ha Dao, Baili Zhang, Jing Lou, Wei Siang Tan, Yongdong Cui, Boo Cheong Khoo
Summary: In this study, the gappy Proper Orthogonal Decomposition (POD) method is used to fuse wind-tunnel measured pressure data and computational fluid dynamics (CFD) simulation results, reconstructing the pressure field and calculating the force coefficients on a marine vessel. The technique is demonstrated for wind load evaluations on the LNG carrier GALEA. The results show a reasonable agreement with the wind-tunnel measured results and those obtained from CFD simulations.
Article
Engineering, Multidisciplinary
Stefania Fresca, Andrea Manzoni
Summary: DL-ROMs are proposed to overcome limitations of conventional ROMs, but require expensive training. The proposed method combines POD and multi-fidelity pretraining to avoid the costly training stage of DL-ROMs.
COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING
(2022)
Article
Construction & Building Technology
Bingchao Zhang, Hong Hu, Hideki Kikumoto, Ryozo Ooka
Summary: This study uses spectral proper orthogonal decomposition (SPOD) to analyze the impact of turbulence on natural ventilation in a building. The results show that turbulence produces two main ventilation routes: cross ventilation in the low-frequency region and single-sided ventilation in the high-frequency region. Additionally, the installation location of window casements has a significant influence on turbulence-induced ventilation.
BUILDING AND ENVIRONMENT
(2022)
Article
Engineering, Aerospace
Lele Ming, Yadong Wu, Zeyuan Yang, Zihuan Zhu, Hua Ouyang, Lili Li
Summary: This study investigates the internal flow of a continuous variable curvature S-duct using large eddy simulation (LES) method. The analysis reveals the generation, development, and evolution mechanisms of distortion and swirl, and provides important input conditions for subsequent compressor distortion research and influence analysis of mass injection pre-compressor cooling technology.
AEROSPACE SCIENCE AND TECHNOLOGY
(2023)
Article
Thermodynamics
Tao Zhou, Kai Zhao, Feng Li, Kefu Wang, Nan Meng, Duo Wang
Summary: This paper investigates the impact of inner and outer pilot swirlers on flame structures and thermo-acoustic instabilities in triple-swirler staged combustors. Using POD technique, energetic modes in combustor velocity and OH radical mass fraction fields are obtained. Increasing the inner pilot swirl number enhances vortex shedding mode and flame radial propagation mode, while weakening axial propagation mode. On the other hand, increasing outer pilot swirl number primarily affects the enhancement of vortex shedding mode and positively influences other flame fluctuation modes. The vortex shedding in the inner shear layer is the main factor affecting thermo-acoustic instability in the combustion chamber. The impact of energy ratio of this mode on thermo-acoustic instability increases nonlinearly with the increased pilot swirl number due to the comprehensive impacts of vortex shedding mode, spatial distribution, and premixed flame area proportion.
CASE STUDIES IN THERMAL ENGINEERING
(2023)
Article
Thermodynamics
Jiajun He, Qingsong An, Jiangshan Jin, Shuai Feng, Kemu Zhang
Summary: In this study, a visualization experiment and proper orthogonal decomposition (POD) method were used to study the variations in the cavitation shedding frequency and analyze the cavitation flow structure in a 3 mm square nozzle. Large eddy simulation (LES) was performed to explore the causes of cavitation shedding, and the relationship between cavitation and vortices. The re-entrant jet mechanism was found to be the main reason for the shedding of cavitation clouds.
JOURNAL OF THERMAL SCIENCE
(2023)
Article
Thermodynamics
Mengcheng Yuan, Ping Wang, Yang Zhang, Antonio Ferrante
Summary: In this study, Large Eddy Simulation is used to simulate a strut-stabilized model scramjet, considering both flame thickening and turbulence/flame interaction. The complex physical phenomena in supersonic reactive flow are predicted efficiently, and the results show good agreement with experimental data. The flame structure and heat release rate are comprehensively analyzed, and the thermal-acoustic coupling as well as multiple factors causing oscillation characteristics are discussed.
CASE STUDIES IN THERMAL ENGINEERING
(2023)
Article
Computer Science, Interdisciplinary Applications
M. Fiore, H. Parisot-Dupuis, B. Etchebarne, R. Gojon
Summary: This paper investigates the aero-acoustic coupling phenomenon and proposes an improved SPOD algorithm for identifying the hydrodynamic and acoustic fields, which is validated in large-eddy simulations of supersonic jets.
COMPUTERS & FLUIDS
(2022)
Article
Thermodynamics
Weijie Liu, Ranran Xue, Liang Zhang, Qian Yang, Huiru Wang
Summary: This study experimentally investigates the dynamic response of a forced low-swirl methane/air premixed flame, revealing that flame response is influenced by swirl number, with time delay decreasing as swirl number increases. The flame oscillates mainly in the axial direction at low frequency and turns into radial direction at high frequency, with flame intensity fluctuation mainly controlled by the flame tail.
FLOW TURBULENCE AND COMBUSTION
(2022)
Article
Engineering, Multidisciplinary
Ruijia Cao, Jianping Yuan, Xiangxu Kong, Zhenfa Xu, Guoyi Peng, Ning Qiu
Summary: The aim of this study is to develop a contour extraction method for investigating the temporal and spatial characteristics of cavitation evolution in high-speed inducers. By processing the raw images and using proper mathematical methods, the evolution of cavitation was studied. The experimental results show that cavitation evolution is an unsteady process, and the characteristics of cavitation vary under different operating conditions.
MEASUREMENT SCIENCE AND TECHNOLOGY
(2023)
Article
Engineering, Civil
Qingshan Yang, Feixin Chen, Bowen Yan, Tian Li, Jinhui Yan, Xinzan Hu
Summary: This study investigates the effects of free-stream turbulence on motion-induced aerodynamic forces of a long-span flexible flat roof. The results show that free-stream turbulence has dual effects on the motion-induced aerodynamic forces, with a decrease in forces as the turbulence intensity increases. The dominance of the motion-induced effects diminishes under high free-stream turbulence conditions.
JOURNAL OF WIND ENGINEERING AND INDUSTRIAL AERODYNAMICS
(2022)
