A triaxial tensile machine for three-dimensional membrane components: Experimental investigations and numerical simulations

2018 ◽  
Vol 65 ◽  
pp. 206-216 ◽  
Author(s):  
Jianhui Hu ◽  
Wujun Chen ◽  
Yipo Li ◽  
Chengjun Gao ◽  
Taibai Shi ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Three Dimensional ◽  
Experimental Investigations ◽  
Membrane Components

Development and validation of a novel quasi-dimensional combustion model for un-scavenged prechamber gas engines with numerical simulations and engine experiments

2020 ◽  
pp. 146808742095133 ◽  
Author(s):  
Konstantinos Bardis ◽  
Panagiotis Kyrtatos ◽  
Guoqing Xu ◽  
Christophe Barro ◽  
Yuri Martin Wright ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Design Parameters ◽  
Combustion Model ◽  
Experimental Investigations ◽  
Computationally Efficient ◽  
Lean Burn ◽  
Dimensional Models ◽  
Three Dimensional Models

Lean-burn gas engines equipped with an un-scavenged prechamber have proven to reduce nitrogen oxides (NOx) emissions and fuel consumption, while mitigating combustion cycle-to-cycle fluctuations and unburned hydrocarbon (UHC) emissions. However, the performance of a prechamber gas engine is largely dependent on the prechamber design, which has to be optimised for the particular main chamber geometry and the foreseen engine operating conditions. Optimisation of such complex engine components relies partly on computationally efficient simulation tools, such as quasi and zero-dimensional models, since extensive experimental investigations can be costly and time-consuming. This article presents a newly developed quasi-dimensional (Q-D) combustion model for un-scavenged prechamber gas engines, which is motivated by the need for reliable low order models to optimise the principle design parameters of the prechamber. Our fundamental aim is to enhance the predictability and robustness of the proposed model with the inclusion of the following: (i) Formal derivation of the combustion and flow submodels via reduction of the corresponding three-dimensional models. (ii) Individual validation of the various submodels. (iii) Combined use of numerical simulations and experiments for the model validation. The resulting model shows very good agreement with the numerical simulations and the experiments from two different engines with various prechamber geometries using a set of fixed calibration parameters.

scholarly journals An experimental study and modelling of roughness effects on laminar flow in microchannels

2007 ◽  
Vol 594 ◽  
pp. 399-423 ◽  
Author(s):  
G. GAMRAT ◽  
M. FAVRE-MARINET ◽  
S. LE PERSON ◽  
R. BAVIÈRE ◽  
F. AYELA
Keyword(s):  
Laminar Flow ◽  
Numerical Simulations ◽  
Three Dimensional ◽  
Volume Averaging ◽  
Roughness Height ◽  
Experimental Investigations ◽  
Layer Model ◽  
Roughness Effects ◽  
Relative Roughness ◽  
Effective Roughness

Three different approaches were used in the present study to predict the influence of roughness on laminar flow in microchannels. Experimental investigations were conducted with rough microchannels 100 to 300μm in height (H). The pressure drop was measured in test-sections prepared with well-controlled wall roughness (periodically distributed blocks, relative roughness k* =k/0.5H≈0.15) and in test-sections with randomly distributed particles anchored on the channel walls (k* ≈0.04–0.13). Three-dimensional numerical simulations were conducted with the same geometry as in the test-section with periodical roughness (wavelength L). A one-dimensional model (RLM model) was also developed on the basis of a discrete-element approach and the volume-averaging technique. The numerical simulations, the rough layer model and the experiments agree to show that the Poiseuille number Po increases with the relative roughness and is independent of Re in the laminar regime (Re<2000). The increase in Po observed during the experiments is predicted well both by the three-dimensional simulations and the rough layer model. The RLM model shows that the roughness effect may be interpreted by using an effective roughness height keff. keff/k depends on two dimensionless local parameters: the porosity at the bottom wall; and the roughness height normalized with the distance between the rough elements. The RLM model shows that keff/k is independent of the relative roughness k* at given k/L and may be simply approximated by the law: keff/k = 1 − (c(ϵ)/2π)(L/k) for keff/k>0.2, where c decreases with the porosity ϵ.

scholarly journals Numerical and experimental investigations on vibration of simulated CANDU fuel bundles subjected to turbulent fluid flow

2021 ◽  
Author(s):  
Xuan Zhang
Keyword(s):  
Numerical Simulations ◽  
Nuclear Reactor ◽  
Plate Theory ◽  
Three Dimensional ◽  
Element Model ◽  
Experimental Investigations ◽  
Flow Induced Vibration ◽  
Flow Measurements ◽  
Eddy Simulation ◽  
Fuel Bundle

Vibration of simulated CANDU fuel bundles induced by coolant flow is investigated in this thesis through experiments and numerical simulations. Two simulated bundles and a hydraulic loop are built to mimic the situation of the fuel bundles located at the inlet of a fuel channel in a CANDU nuclear reactor. Fuel bundle vibration mechanism is investigated through experiments and numerical simulations. The three-dimensional turbulent flow that passes through the simulated bundles is modeled using the large eddy simulation (LES) and solved with parallel processing. The local cross flows induced by the presence of endplates at the inlet location and bundle interface location are investigated. The fluid forces are obtained as excitations for the fuel bundle vibration analysis. A finite element model of the fuel bundles is developed with the endplates modeled using the 3rd order thick plate theory. The response of the inlet fuel bundle to the fluid excitations is solved in the time and the frequency domain. The added mass and the fluid damping are approximated with the theory on the flow-induced vibration of slender bodies in a parallel flow. Measurements are obtained and used to validate the numerical prediction under various operating flow conditions.

scholarly journals Numerical and experimental investigations on vibration of simulated CANDU fuel bundles subjected to turbulent fluid flow

2021 ◽  
Author(s):  
Xuan Zhang
Keyword(s):  
Numerical Simulations ◽  
Nuclear Reactor ◽  
Plate Theory ◽  
Three Dimensional ◽  
Element Model ◽  
Experimental Investigations ◽  
Flow Induced Vibration ◽  
Flow Measurements ◽  
Eddy Simulation ◽  
Fuel Bundle

Vibration of simulated CANDU fuel bundles induced by coolant flow is investigated in this thesis through experiments and numerical simulations. Two simulated bundles and a hydraulic loop are built to mimic the situation of the fuel bundles located at the inlet of a fuel channel in a CANDU nuclear reactor. Fuel bundle vibration mechanism is investigated through experiments and numerical simulations. The three-dimensional turbulent flow that passes through the simulated bundles is modeled using the large eddy simulation (LES) and solved with parallel processing. The local cross flows induced by the presence of endplates at the inlet location and bundle interface location are investigated. The fluid forces are obtained as excitations for the fuel bundle vibration analysis. A finite element model of the fuel bundles is developed with the endplates modeled using the 3rd order thick plate theory. The response of the inlet fuel bundle to the fluid excitations is solved in the time and the frequency domain. The added mass and the fluid damping are approximated with the theory on the flow-induced vibration of slender bodies in a parallel flow. Measurements are obtained and used to validate the numerical prediction under various operating flow conditions.

Effect of the Nozzle Radiation on the Fused Filament Fabrication Process: Three-Dimensional Numerical Simulations and Experimental Investigation

2019 ◽  
Vol 141 (8) ◽  
Author(s):  
Benoît Cosson ◽  
André Chateau Akué Asséko
Keyword(s):  
Temperature Field ◽  
Numerical Simulations ◽  
Source Term ◽  
Three Dimensional ◽  
Temperature Fields ◽  
Experimental Investigations ◽  
Fused Filament Fabrication ◽  
Proposed Model ◽  
The Heat Balance ◽  
Good Agreement

This paper addresses heat distribution issues in fused filament fabrication (FFF) process. Three-dimensional (3D) numerical simulations and experimental investigations are performed during additive manufacturing of parts by FFF process. The transient numerical simulations of the filament temperature field are based on the finite difference method. Experimental measurements of the temperature field are carried out using infrared thermography. The proposed model mainly highlights the contribution of heat exchange from the nozzle to the fabricated part and from filament to filament. Optimum adhesion of filaments deposited by FFF requires control of the thermal history. The nozzle radiation is taken into account as a source term in the heat balance equation. The temperature fields of the printed parts computed by numerical simulations are in very good agreement with the temperature fields measured by infrared thermograph. The 3D numerical model provides information on how the nozzle affects the temperature field of the printed part. This source term must be taken into account for the optimization of the FFF process.

scholarly journals Structural Characterization of Receptor–Receptor Interactions in the Allosteric Modulation of G Protein-Coupled Receptor (GPCR) Dimers

2021 ◽  
Vol 22 (6) ◽  
pp. 3241
Author(s):  
Raudah Lazim ◽  
Donghyuk Suh ◽  
Jai Woo Lee ◽  
Thi Ngoc Lan Vu ◽  
Sanghee Yoon ◽  
...  
Keyword(s):  
G Protein ◽  
Protein Interactions ◽  
Metabotropic Glutamate Receptor ◽  
Three Dimensional ◽  
Allosteric Modulation ◽  
Experimental Investigations ◽  
G Protein Coupled Receptor ◽  
Metabotropic Glutamate ◽  
Gpcr Activation ◽  
G Protein Coupled

G protein-coupled receptor (GPCR) oligomerization, while contentious, continues to attract the attention of researchers. Numerous experimental investigations have validated the presence of GPCR dimers, and the relevance of dimerization in the effectuation of physiological functions intensifies the attractiveness of this concept as a potential therapeutic target. GPCRs, as a single entity, have been the main source of scrutiny for drug design objectives for multiple diseases such as cancer, inflammation, cardiac, and respiratory diseases. The existence of dimers broadens the research scope of GPCR functions, revealing new signaling pathways that can be targeted for disease pathogenesis that have not previously been reported when GPCRs were only viewed in their monomeric form. This review will highlight several aspects of GPCR dimerization, which include a summary of the structural elucidation of the allosteric modulation of class C GPCR activation offered through recent solutions to the three-dimensional, full-length structures of metabotropic glutamate receptor and γ-aminobutyric acid B receptor as well as the role of dimerization in the modification of GPCR function and allostery. With the growing influence of computational methods in the study of GPCRs, we will also be reviewing recent computational tools that have been utilized to map protein–protein interactions (PPI).

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