Experimental Investigations and Numerical Simulations for the Seismic Assessment of a Masonry Building

2021 ◽  
pp. 57-70
Author(s):  
Mariella Diaferio ◽  
Marilena Venerito ◽  
Michele Vitti
Keyword(s):  
Numerical Simulations ◽  
Seismic Assessment ◽  
Experimental Investigations ◽  
Masonry Building

URANS Simulations and Experimental Investigations on Unsteady Aerodynamic Effects in the Blade Tip Region of a Shrouded Fan Configuration

2017 ◽  
Author(s):  
Gi-Don Na ◽  
Frank Kameier ◽  
Nils Springer ◽  
Michael Mauß ◽  
C. O. Paschereit
Keyword(s):  
Applied Sciences ◽  
Numerical Simulations ◽  
Aerodynamic Performance ◽  
Design Parameters ◽  
Experimental Investigations ◽  
Acoustic Measurements ◽  
Noise Emission ◽  
Industrial Partner ◽  
University Of Applied Sciences ◽  
Blade Tip

The acoustical characteristics of cooling fans are an essential criterion of product quality in the automotive industry. Fan modules have to suffice growing customer expectations which are reflected in the comfort requirements set by car manufacturers around the world. In order to locate dominant acoustic sources and to reduce the noise emission generated by a shrouded fan configuration, numerical simulations and experimental investigations are performed. The working approach considers variously modified fan geometries and their evaluation regarding arising vortex flow phenomena and their effect on a decreased sound pressure level (SPL) in consideration of an improvement or the constancy of aerodynamic fan performance. Particular emphasis lies on the analysis of secondary flows in the blade tip region by post-processing CFD-results. Due to the large number of geometrical modifications investigated and the importance of highly resolved eddy structures, a hybrid approach is chosen by applying the SAS-SST turbulence model in URANS simulations. The SAS (Scale Adaptive Simulation) delivers LES (Large Eddy Simulation) content in unsteady regions of a RANS-simulation and exhibits not nearly the high computational effort needed to perform a full scale LES. An assessment of the actual propagation of noise emission into the far-field is made by performing experimental investigations on the most promising modifications. The acoustic measurements are carried out in a fan test stand in the anechoic chamber of Duesseldorf University of Applied Sciences. The aerodynamic performance is measured in a fan test rig with an inlet chamber setup in accordance to ISO 5801. The measured acoustical and aerodynamic performances are validated by the industrial partner. The results of the acoustic measurements are in turn utilized to determine indicators of noise radiation in the numerical simulation. Within this work an innovative geometry modification is presented which can be implemented into shrouded fan configurations with backward-skewed blades. The new design exhibits a reduced SPL (A-weighted) of approx. 4 dB over the entire operating range while showing no significant deterioration on the aerodynamic performance. While the design was registered for patent approval cooperatively by the industrial partner and Duesseldorf University of Applied Sciences, further investigations regarding variations of design parameters are performed and presented in this paper. All numerical simulations are performed with ANSYS CFX, a commercial solver widely spread in the industry. Methods similar to those shown in this work can be implemented in the design phase of axial fans in order to develop acoustically optimized fan geometries.

scholarly journals Thermal Behavior of an Extensive Green Roof: Numerical Simulations and Experimental Investigations

2016 ◽  
Vol 34 (S2) ◽  
pp. S226-S234 ◽  
Author(s):  
Antonio Gagliano ◽  
Francesco Nocera ◽  
Maurizio Detommaso ◽  
Gianpiero Evola
Keyword(s):  
Thermal Behavior ◽  
Numerical Simulations ◽  
Green Roof ◽  
Experimental Investigations ◽  
Extensive Green Roof

Seismic Assessment of Masonry Building Clusters with a Dedicated NLA Software

2016 ◽  
Vol 847 ◽  
pp. 191-203 ◽  
Author(s):  
Marco Vailati ◽  
Giorgio Monti ◽  
Giorgia di Gangi
Keyword(s):  
Stochastic Approach ◽  
Seismic Assessment ◽  
Masonry Building ◽  
Structural Units ◽  
Global Response ◽  
Computational Tools ◽  
Modeling And Analysis ◽  
Future Version ◽  
Level Of Knowledge ◽  
Typical Scenario

A building context as complex as that of many historical centers in Europe is the typical scenario where more and more technicians found themselves at work. In addition to the usual difficulty of dealing with the complexity of masonry building clusters, they particularly feel the lack of the essential support of dedicated computational tools. In fact, the calculation codes currently available do not address modeling and analysis of building clusters in a personalized manner. VENUS, Italian acronym for Nonlinear Assessment of Structural Units, is a software developed in C++, which deals with the seismic assessment of building clusters in an integrated manner, accompanying the practitioner from the early stages of defining the level of knowledge, to the management of the design quantities, until the graphic elaboration of the results. Finally, it allows to test the effectiveness of a local intervention with traditional and innovative strengthening techniques and to evaluate its effects on the global response. Finally, a brief description of a stochastic approach foreseen in a future version of the software is discussed.

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.

Numerical Simulation for Two-Phase Flows in Fuel Cell Minichannels

2011 ◽  
Vol 8 (4) ◽  
Author(s):  
Jean-Baptiste Dupont ◽  
Dominique Legendre ◽  
Anna Maria Morgante
Keyword(s):  
Fuel Cell ◽  
Numerical Simulations ◽  
Two Phase Flow ◽  
Numerical Code ◽  
Experimental Investigations ◽  
Pressure Jump ◽  
Phase Flow ◽  
Two Phase Flows ◽  
Two Phase ◽  
Flow Configurations

This work presents direct numerical simulations of two-phase flows in fuel cell minichannels. Different two-phase flow configurations can be observed in such minichannels, which depend on gas-flow rate, liquid holdup, and wettability of each wall. These flows are known to have a significant impact on the fuel cell’s performance. The different two-phase flow configurations must be studied specially concerning the prediction of the transition among them. In the fuel cell minichannels, experimental investigations are difficult to perform because of the small size of the device and the difficult control of the wettability properties of the walls. In such systems, numerical approach can provide useful information with a perfect control of the flow characteristics, particularly for the wettability aspect. The numerical code used in this study is the JADIM code developed at IMFT, which is based on a “volume of fluid” method for interface capturing without any interface reconstruction. The numerical description of the surface tension is one of the crucial points in studying such systems where capillary effects control the phase distribution. The static and the dynamics of the triple line between the liquid, the gas, and the wall is also an essential physical mechanism to consider. The numerical implementation of this model is validated in simple situations where analytical solutions are available for the shape and the pressure jump at the interface. In this paper we present the characteristics of the JADIM code and its potential for the studies of the fuel cell internal flows. Numerical simulations on the two-phase flows on walls, in corners, and inside channels are shown.

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