scholarly journals Study of a Controlled Piezoelectric Damper

Sensors ◽  
2021 ◽  
Vol 21 (10) ◽  
pp. 3509
Author(s):  
Michał Makowski ◽  
Lech Knap
Keyword(s):  
Numerical Model ◽  
Vibration Reduction ◽  
Experimental Studies ◽  
Piezoelectric Actuators ◽  
Vibration Damper ◽  
Active Systems ◽  
Numerical Studies ◽  
Short Time ◽  
Time Of Operation ◽  
Original Construction

In this work an original construction of a vibration damper controlled by means of a valve with a short time of operation lag is presented. The valve-controlling properties of the damper regulates the flow of fluid between the chambers of the damper and was constructed using piezoelectric actuators, whose characteristic feature is the possibility to change dimensions, e.g., length, under the influence of voltage. As a result, by changing voltage it is possible to control the throttle of the flow by changing the width of a gap, which influences a change of damping forces. Such a solution enables a quicker change of damping forces than in other kinds of controlled damper. Due to the obtained properties, the damper may be applied to reduce the vibrations of vehicles and machines that undergo quick-change loads. In the article, the results of experimental studies of the aforementioned damper are presented. Based on the results, dissipative characteristics were determined. Also, results of numerical studies comprising the development of a numerical model of a controlled piezoelectric damper are shown. Results of numerical studies, as well as experimental studies, are presented in the form of dissipative characteristics. Comparison of results of numerical and experimental studies confirms the possibility to apply this kind of construction in semi-active systems of vibration reduction of vehicles and machines.

Numerical Predication of Swept Blade Aerodynamic Effects

2004 ◽  
Author(s):  
C. Xu ◽  
R. S. Amano
Keyword(s):  
Turbine Blade ◽  
Pressure Coefficient ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Flow Angle ◽  
Transonic Compressor ◽  
Compressor Rotor ◽  
Numerical Studies ◽  
Flow Loss ◽  
Short Time

Three-dimensional blading has been used in the process of turbomachine designs. To meet the need for efficient turbine blade designs, CFD predictions of a complex 3D flow field in turbine blade passages had been used. Because the numerous advantages of 3-D CFD have been reported in the open literature, many industries already use 3D blading in their turbomachines. In addition, blade lean and sweep have been implemented to increase the blade row efficiency. Experimental studies have shown the advantages of these features. However, most of the experimental results combined other features together, making it difficult to determine the effects of individual features. The development of CFD techniques has made it possible to do three-dimensional turbulent flow analyses in a very short time. In this study, numerical studies are presented to study the sweep effects on a transonic compressor airfoil. The focus of the paper is to investigate the sweep effects without changing other compressor blade features i.e. keeping the blade out flow angle the same for all cases. The purpose of the study is to enhance the understanding of the sweep in a transonic compressor rotor blade. The results showed that the sweeps redistributes the flow reducing the secondary flow loss, depending on the baseline. It was shown that forward sweep reduces the tip loading in terms of the static pressure coefficient.

scholarly journals Numerical and Experimental Investigation of Rectangular Liquid-Containing Structures under Seismic Excitation

2020 ◽  
Vol 6 (1) ◽  
pp. 1
Author(s):  
Iman Bahreini Toussi ◽  
Reza Kianoush ◽  
Abdolmajid Mohammadian
Keyword(s):  
Fluid Dynamics ◽  
Experimental Investigation ◽  
Numerical Model ◽  
Experimental Studies ◽  
Experimental Tests ◽  
Industrial Applications ◽  
Shaking Table ◽  
Seismic Excitation ◽  
Seismic Excitations ◽  
Numerical Studies

Liquid-containing structures are used for various municipal and industrial applications. The functionality of these structures in seismic regions is crucial. The main purpose of this study is to investigate the behavior of liquid under seismic excitations using numerical modelling. For this purpose, experimental and numerical studies are conducted. In the experimental tests, a ground-supported rectangular tank is excited on a shaking table. The tests are videotaped from two directions and subsequently analyzed frame-by-frame. Four different orientations are tested to investigate the effect of bilateral excitation. In the numerical simulations, the same tank is modeled in OpenFOAM—a computational fluid dynamics program—and the same excitations are applied. The results from the numerical and the experimental studies are compared, and reliability of the numerical model is discussed. Furthermore, using the numerical model, the pressure on the roof of the tank is obtained at various locations and examined for different excitations.

Numerical and experimental studies of water disinfection in UV reactors

2019 ◽  
Vol 80 (8) ◽  
pp. 1456-1465
Author(s):  
H. Y. Li ◽  
H. Osman ◽  
C. W. Kang ◽  
T. Ba ◽  
J. Lou
Keyword(s):  
Boundary Layer ◽  
Numerical Model ◽  
Experimental Studies ◽  
Water Disinfection ◽  
Reactor Performance ◽  
Ansys Fluent ◽  
Performance Simulation ◽  
Numerical Studies ◽  
Uv Dose ◽  
Boundary Layer Mesh

Abstract Performance of UV reactors for water disinfection is investigated in this paper. Both experimental and numerical studies are performed on base reactor LP24. Enterobacteria phage MS2 is chosen as the challenge microorganism in the experiments. Experiments are conducted to evaluate the effect of different parameters, i.e. flow rate and UV transmission, on the reactor performance. Simulation is carried out based on the commercial software ANSYS FLUENT with user defined functions (UDFs) implemented. The UDF is programmed to calculate UV dose absorbed by different microorganisms along their flow trajectories. The effect with boundary layer mesh and without boundary layer mesh for LP24 is studied. The results show that the inclusion of boundary layer mesh does not have much effect on the reactor performance in terms of reduction equivalent dose (RED). The numerical results agree well with the experimental measurements, hence validating the numerical model. With this achieved, the numerical model is applied to study other scaled reactors: LP12, LP40, LP60 and LP80. Comparisons show that LP40 has the highest RED and log inactivation among all the reactors while LP80 has the lowest RED and log inactivation.

scholarly journals SIMULATION OF POWDER SINTERING USING A DISCRETE ELEMENT MODEL

2013 ◽  
Vol 7 (3) ◽  
pp. 175-179 ◽  
Author(s):  
Jerzy Rojek ◽  
Szymon Nosewicz ◽  
Katarzyna Pietrzak ◽  
Marcin Chmielewski
Keyword(s):  
Numerical Model ◽  
Experimental Studies ◽  
Spherical Shape ◽  
Element Model ◽  
Discrete Element ◽  
Discrete Elements ◽  
Numerical Studies ◽  
Powder Sintering ◽  
Evolution Of Microstructure ◽  
Cohesive Interaction

Abstract This paper presents numerical simulation of powder sintering. The numerical model introduced in this work employs the discrete element method which assumes that material can be modelled by a large assembly of discrete elements (particles) of spherical shape interacting among one another. Modelling of sintering requires introduction of the cohesive interaction among particles representing interparticle sintering forces. Numerical studies of sintering have been combined with experimental studies which provided data for calibration and validation of the model. In the laboratory tests evolution of microstructure and density during sintering have been studied. Comparison of numerical and experimental results shows a good performance of the numerical model developed

Design of Swept Blade for Turbomachinery

2005 ◽  
Author(s):  
C. Xu ◽  
R. S. Amano
Keyword(s):  
Turbine Blade ◽  
Design Process ◽  
Pressure Coefficient ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Transonic Compressor ◽  
Compressor Rotor ◽  
Numerical Studies ◽  
Flow Loss ◽  
Short Time

To meet the needs of efficient turbine blade designs, CFD predictions of a complex 3D flow field in turbine blade passages have been incorporated in the design process during the last decade. Owing to the numerous advantages possessed by a 3-D CFD technology many industries already use a 3D blading technique in the design process of turbomachines. In addition, blade lean and sweep have been implemented to increase the blade row efficiency. Experimental studies have shown some advantages of these features. However, most of the experimental results were combined with other features together as well; thus making it difficult to determine the effects of individual superior features. The development of CFD techniques has made it possible to do three-dimensional turbulent flow analyses in a very short time. In this study, numerical studies are presented to demonstrate the sweep effects on a transonic compressor airfoil. The purpose of this study is to investigate the sweep effects without changing other compressor blade features; i.e. keeping the blade outflow angles and section shapes to be the same at design sections for all cases. Through this study the sweep effect in a transonic compressor rotor blade was tested. The results showed that the sweeps redistribute the flow reducing the secondary flow loss, depending on the baseline. It was shown that the forward sweep reduces the tip loading in terms of the static pressure coefficient.

scholarly journals Hydraulic Transients in Viscoelastic Pipeline System with Sudden Cross-Section Changes

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4071
Author(s):  
Michał Kubrak ◽  
Agnieszka Malesińska ◽  
Apoloniusz Kodura ◽  
Kamil Urbanowicz ◽  
Michał Stosiak
Keyword(s):  
Numerical Model ◽  
Cross Section ◽  
Laboratory Data ◽  
Experimental Studies ◽  
Distribution Networks ◽  
Water Hammer ◽  
Fluid Distribution ◽  
Pipeline System ◽  
Hydraulic Transients ◽  
Single Pipe

It is well known that the water hammer phenomenon can lead to pipeline system failures. For this reason, there is an increased need for simulation of hydraulic transients. High-density polyethylene (HDPE) pipes are commonly used in various pressurised pipeline systems. Most studies have only focused on water hammer events in a single pipe. However, typical fluid distribution networks are composed of serially connected pipes with various inner diameters. The present paper aims to investigate the influence of sudden cross-section changes in an HDPE pipeline system on pressure oscillations during the water hammer phenomenon. Numerical and experimental studies have been conducted. In order to include the viscoelastic behaviour of the HDPE pipe wall, the generalised Kelvin–Voigt model was introduced into the continuity equation. Transient equations were numerically solved using the explicit MacCormack method. A numerical model that involves assigning two values of flow velocity to the connection node was used. The aim of the conducted experiments was to record pressure changes downstream of the pipeline system during valve-induced water hammer. In order to validate the numerical model, the simulation results were compared with experimental data. A satisfactory compliance between the results of the numerical calculations and laboratory data was obtained.

Film thickness in elastohydrodynamically lubricated slender elliptic contacts: Part I – numerical studies of central film thickness

2021 ◽  
pp. 135065012110477
Author(s):  
Marius Wolf ◽  
Sergey Solovyev ◽  
Fatemi Arshia
Keyword(s):  
Film Thickness ◽  
State Of The Art ◽  
Experimental Studies ◽  
Elastohydrodynamic Lubrication ◽  
Large Parameter ◽  
Numerical Studies ◽  
Minimum Film Thickness ◽  
Subsequent Publication ◽  
New Formula ◽  
Increasing Load

In this paper, analytical equations for the central film thickness in slender elliptic contacts are investigated. A comparison of state-of-the-art formulas with simulation results of a multilevel elastohydrodynamic lubrication solver is conducted and shows considerable deviation. Therefore, a new film thickness formula for slender elliptic contacts with variable ellipticity is derived. It incorporates asymptotic solutions, which results in validity over a large parameter domain. It captures the behaviour of increasing film thickness with increasing load for specific very slender contacts. The new formula proves to be significantly more accurate than current equations. Experimental studies and discussions on minimum film thickness will be presented in a subsequent publication.

The Research of Energy Conversion and Heat Transfer in the Ceramic Foams of Solar Energy Converter

2011 ◽  
Author(s):  
Yangbo Deng ◽  
Fengmin Su ◽  
Chunji Yan
Keyword(s):  
Heat Transfer ◽  
Numerical Model ◽  
Solar Radiation ◽  
Solar Energy ◽  
Numerical Models ◽  
Air Flow ◽  
Energy Converter ◽  
Ceramic Foams ◽  
Numerical Studies ◽  
Flow Through

The solar energy converter in Concentrated Solar Power (CSP) system, applies the solid frame structure of the ceramic foams to receive the concentrated solar radiation, convert it into thermal energy, and heat the air flow through the ceramic foams by convection heat transfer. In this paper, first, the pressure drops in the studied ceramic foams were measured under all kinds of flow condition. Based on the experimental results, an empirical numerical model was built for the air flow through ceramic foams. Second, a 3-D numerical model was built, for the receiving and conversion of the solar energy in the ceramic foams of the solar energy converter. Third, applying two aforementioned numerical models, the numerical studies of the thermal performance were carried out, for the solar energy converter filled with the ceramic foams, and results show that the structure parameters of the ceramic foams, the effective reflective area and the solar radiation intensity of the solar concentrator, have direct impacts on the absorptivity and conversion efficiency of the solar energy in the solar energy converter. And the results of the numerical studies are found to be in reasonable agreement with the experimental measurements. This paper will provide a reference for the design and manufacture of the solar energy converter with the ceramic foams.

Study on Vibration Reduction of Finishing Lapping Machine for Bearing Race

2011 ◽  
Vol 199-200 ◽  
pp. 1496-1500
Author(s):  
Jia Man ◽  
Lian Hong Zhang ◽  
Yong Liang Chen
Keyword(s):  
Vibration Amplitude ◽  
Vibration Reduction ◽  
Experimental Studies ◽  
Machining Efficiency ◽  
Bearing Race ◽  
Excitation Force ◽  
Lapping Machine ◽  
Light Material ◽  
Vibration Performance

It is key to improve the machining efficiency of finishing lapping machine to restrain the vibration that raise with work speed. The vibration amplitude is influenced by the excitation force of unbalanced crank-rocker mechanism and the anti-vibration performance of guide. Following improving schemes as adding counterweight to crank-rocker mechanism, adopting the light material motion components and enhancing the anti-vibration performance of guide are proposed based on theoretical and experimental studies. The improving schemes are verified by the experiment.

scholarly journals Investigations on Torsion of the Two-Chords Single Laced Members

2017 ◽  
Vol 25 (2) ◽  
pp. 147-160
Author(s):  
Paweł Lorkowski ◽  
Bronisław Gosowski
Keyword(s):  
Cross Sections ◽  
Experimental Studies ◽  
The Finite Element Method ◽  
Second Moment ◽  
Steel Columns ◽  
Numerical Studies ◽  
Traction Network ◽  
Railway Traction ◽  
Parametric Analyses ◽  
The Relationship

Abstract The paper presents experimental and numerical studies to determine the equivalent second moment of area of the uniform torsion of the two-chord steel single laced members. The members are used as poles of railway traction network gates, and steel columns of framed buildings as well. The stiffness of uniform torsion of this kind of columns allows to the determine the critical loads of the spatial stability. The experimental studies have been realized on a single - span members with rotation arrested at their ends, loaded by a torque applied at the mid-span. The relationship between angle of rotation of the considered cross-section and the torque has been determined. Appropriate numerical model was created in the ABAQUS program, based on the finite element method. A very good compatibility has been observed between experimental and numerical studies. The equivalent second moment of area of the uniform torsion for analysed members has been determined by comparing the experimental and analytical results to those obtained from differential equation of non-uniform torsion, based on Vlasov’s theory. Additionally, the parametric analyses of similar members subjected to the uniform torsion, for the richer range of cross-sections have been carried out by the means of SOFiSTiK program. The purpose of the latter was determining parametrical formulas for calculation of the second moment of area of uniform torsion.

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