Convergence Characteristics of the Multiple Error Filtered-x LMS Algorithm

Guoyue Chen,Kenji Muto,Masato Abe,Toshio Sone 한국소음진동공학회 2003 한국소음진동공학회 국제학술대회논문집 Vol.2003 No.8

Effects of fluid thermophysical properties on cavitating flows

Tairan Chen,Biao Huang,Guoyu Wang,Kun Wang 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.10

We studied the thermo-fluid cavitating flows and evaluated the effects of physical properties on cavitation behaviors. The thermo-fluid(including liquid nitrogen, liquid hydrogen and hot water) cavitating flows around a 2D hydrofoil were numerically investigated. TheFavre-averaged Navier-Stokes equations with the enthalpy-based energy equation, transport equation-based cavitation model, and the k-ω SST turbulence model were applied. The thermodynamic parameter Σ, defined as ( 2 2 ) / ( 2 ) v l v l r L r C T e ¥ å = was used to assess thethermodynamic effects on cavitating flows. The results manifest that the thermal energy solution case yields a substantially shorter andmushier cavity attached on the hydrofoil due to the thermodynamic effects, which shows better agreement with the experimental data. The temperature drop inside the cavity decreases the local saturated vapor pressure and hence increases the local cavitation number; itcould delay or suppress the occurrence and development of the cavitation behavior. The thermodynamic effects can be evaluated bythermophysical properties under the same free-stream conditions; the thermodynamic parameter Σ is shown to be critical in accuratelypredicting the thermodynamic effects on cavitating flows. The surrogate-based global sensitivity analysis of liquid nitrogen cavitatingflow suggests that ρv, Cl and L could significantly influence temperature drop and cavity structure in the existing numerical framework,while ρv plays the dominant role on temperature drop when properties vary with changing temperature. The liquid viscosity ml slightlyaffects the flow structure but hardly affects the temperature distribution.

Numerical study on the influence of interphase interaction in sheet/cloud cavitating flows around a 2D hydrofoil

Guanghao Chen,Guoyu Wang,Biao Huang,Changli Hu,Taotao Liu 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.3

We investigated the influence of interphase interaction on unsteady sheet/cloud cavitating flows around a 2D hydrofoil numerically. Inthe computations, the homogeneous (without the consideration of interphase interaction) and inhomogeneous (with the consideration ofinterphase interaction) multiphase flow models are used, respectively. The inhomogeneous model assumes that both phases co-exist atevery point in the flow field and each phase is governed by its own set of conservation laws. The exchanges of mass, interphase dragforce and momentum transfer induced by interphase mass transfer are treated explicitly as transfer terms. The results show that the distributionsof interphase drag force and momentum transfer induced by mass transfer are highly related with the velocity difference of twophases and interphase mass transfer rate, respectively. Without the consideration of interphase interaction, the over-prediction of turbulenteddy viscosity in the rear of attached cavity causes the reentrant jet to lose its momentum and becomes too weak to cut across thecavity sheet. However, when considering the interphase interaction, the predicted turbulent kinetic energy in the rear of attached cavitycan be reduced considerably; thus, turbulent eddy viscosity drops significantly in this region, and the reentrant jet becomes much stronger,so typical cloud cavitation shedding occurs. Compared with those predicted without the consideration of interphase interaction, a betteragreement with experimental results concerning the time evolution of cavity shape, time-averaged lift/drag coefficient, frequency andmean u-velocity profiles is obtained with the consideration of interphase interaction.

Three-dimensional unsteady cavitating flows around an axisymmetric body with a blunt headform

Changli Hu,Guoyu Wang,Guanghao Chen,Biao Huang 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.3

We investigated the three-dimensional characteristics in the unsteady cavitating flow over an axisymmetric body with a blunt headform. A high-speed video camera was used to visualize the cavitating flow structures. A modified PANS (Partially-averaged Navier-Stokes) turbulence model coupled with Kubota cavitation model was used to simulate the time-evolution process of the unsteady cavitatingflows. The finite-time Lyapunov exponent (FTLE) and Lagrangian coherent structures (LCS) methods are applied to investigate thethree-dimensional flow patterns. The results show that the numerical method is capable of simulating the unsteady cavitating flow forcapturing the attached cavity with maximum-length, the cavity break-off and U-type shedding, in accordance with the qualitative featuresobserved in the experiment. Three-dimensional characteristics are extremely impressive in the unsteady cavitating flows. The re-entrantflows originate from different circumferential positions at the closure region of the attached cavity, and move upstream at differentspeeds. Moreover, substantial circumferential motions in the unsteady cavitating flow are found based on Lagrangian trajectories, and itis reasonably deduced that the U-type shedding cavity is primarily induced by the effect of re-entrant flow motions consisting of movingupstream and circumferential flows as well.

Apolipoprotein H: a novel regulator of fat accumulation in duck myoblasts

Ziyi Pan,Guoqing Du,Guoyu Li,Dongsheng Wu,Xingyong Chen,Zhaoyu Geng 한국축산학회 2022 한국축산학회지 Vol.64 No.6

Apolipoprotein H (APOH) primarily engages in fat metabolism and inflammatory disease response. This study aimed to investigate the effects of APOH on fat synthesis in duck myoblasts (CS2s) by APOH overexpression and knockdown. CS2s overexpressing APOH showed enhanced triglyceride (TG) and cholesterol (CHOL) contents and elevated the mRNA and protein expression of AKT serine/threonine kinase 1 (AKT1), ELOVL fatty acid elongase 6 (ELOVL6), and acetyl-CoA carboxylase 1 (ACC1) while reducing the expression of protein kinase AMP-activated catalytic subunit alpha 1 (AMPK), peroxisome proliferator activated receptor gamma (PPARG), acyl-CoA synthetase long chain family member 1 (ACSL1), and lipoprotein lipase (LPL). The results showed that knockdown of APOH in CS2s reduced the content of TG and CHOL, reduced the expression of ACC1, ELOVL6, and AKT1, and increased the gene and protein expression of PPARG, LPL, ACSL1, and AMPK. Our results showed that APOH affected lipid deposition in myoblasts by inhibiting fatty acid beta-oxidation and promoting fatty acid biosynthesis by regulating the expression of the AKT/AMPK pathway. This study provides the necessary basic information for the role of APOH in fat accumulation in duck myoblasts for the first time and enables researchers to study the genes related to fat deposition in meat ducks in a new direction.

Numerical simulations and surrogate-based optimization of cavitation performance for an aviation fuel pump

Xing’an Zhao,Biao Huang,Tairan Chen,Guoyu Wang,Deming Gao,Jing Zhao 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.2

We used computational modeling to investigate the cavitation performance of an aviation fuel pump, and optimize structural parameters using the surrogate-based method. In the numerical simulation, a rotation-curvature correction was adapted to the k-ε turbulence model, and a four-component surrogate fuel was selected to reproduce the physical properties of the China RP-3 kerosene. Then the performance of the aviation fuel pump was predicted. In the optimization, based on the series of the numerical results, Surrogate-based analysis and optimization (SBAO) was used to optimize the structural parameters of the fuel pump (the variation of the outlet blade angle for the inducer △β b1 and the variation of the inlet blade angle for the impeller △β b2 ). The results show that the prediction of cavitation performance agrees well with the experimental data. The results show that cavitation areas are mainly distributed in the inlet of the inducer. The volume of cavities grows with the decreasing NPSHa. The head of the fuel pump has a sudden head-drop when NPSHa ≤ 5.64 m. Furthermore, the surrogate-based approach is available in structural optimization of the fuel pump. The cavitation performance of the optimized pump improved about 22 % with a little drop of head coefficient when △β b1 = 4.33° and △β b2 = 3.24°. The numerical approach employed in this paper can accurately predict the cavitating flow of the high rotating speed fuel pump and the surrogate-based method is available in the structural optimization for a better cavitation performance.

Diversity, Interspecific Interaction and Abundance of Undergrowth in Monocultures and Integrated Systems of Natural Rubber Plantation in Danzhou, Southern China

Chima, Uzoma Darlington,Qi, Dongling,Wu, Zhixiang,Lan, Guoyu,Chen, Li Institute of Forest Science 2022 Journal of Forest Science Vol.38 No.2

The negative impact of monoculture rubber plantations on biodiversity and associated ecological processes/ecosystem services has led to suggestions on the use of integrated land use systems for rubber cultivation and production in order to ensure environmental sustainability. However, there is paucity of information on the effect of such integrated land use systems on the diversity and abundance of the rubber plantation undergrowth. We evaluated and compared undergrowth plant species composition, richness, abundance, diversity and interaction, in three integrated systems (Rubber-Strelitzia reginae Integrated System - RSrIS, Rubber-Podocarpus nagi Integrated System - RPnIS & Naturally Managed Rubber Plantation - NMRP) with three Rubber Monoculture Plantations (RMP₁, RMP₂ & RMP₃) adjacent to the integrated systems, respectively, at the Investigation and Experiment Station of Tropical Crops, Danzhou, Hainan, China. Undergrowth species density was higher in the rubber monocultures than in the integrated systems except in RSrIS. Species richness and diversity were also higher in the monocultures except in NMRP. Species similarity/interaction between the monocultures and the integrated systems was highest between RMP₃ and NMRP. The NRMP proved to be the best model of natural rubber integrated system for the conservation of undergrowth species richness, diversity and interspecific interaction. However, the conservation of undergrowth species in other forms of integrated natural systems can be enhanced by considering the ecology of species to be integrated in terms of their growth characteristics, competitive nature, and ability to grow in association with other species.