Number of found documents: 2882
Published from to

Analýza kmitání modelu kola turbíny
Voronova, Evgeniya; Maturkanič, Dušan; Procházka, Pavel; Hodboď, Robert; Košina, Jan
2017 - Czech
Ve zprávě jsou shrnuty a analyzovány výsledky ověřovacího měření kola při otáčkách 2000 min^-1 . Stanoveny účinky přítomnosti vakua nebo podtlaku na vibrace kola při otáčkách 100 min^-1a při otáčkách 500 min^-1 . Porovnání měření při odlišných otáčkách, s volným kmitáním nebo s vynuceným kmitáním.\n The paper describes the verification tests which were performed for 2000 rpm. Determined effects of vacuum on wheel vibration at 100 rpm and at \n500 rpm. Compare measurements at different speeds, with free oscillation or forced oscillation.\n Keywords: vibratin; turbine; blade; laser; non-contact measurment Available at various institutes of the ASCR
Analýza kmitání modelu kola turbíny

Ve zprávě jsou shrnuty a analyzovány výsledky ověřovacího měření kola při otáčkách 2000 min^-1 . Stanoveny účinky přítomnosti vakua nebo podtlaku na vibrace kola při otáčkách 100 min^-1a při otáčkách ...

Voronova, Evgeniya; Maturkanič, Dušan; Procházka, Pavel; Hodboď, Robert; Košina, Jan
Ústav termomechaniky, 2017

CFD motivated applications of model order reduction
Isoz, Martin
2017 - English
The ongoing advances in numerical mathematics and available computing power combined with the industrial needs promote a development of more and more complex models. However, such models are, due to their complexity, expensive from the point of view of the data storage and the time necessary for their evaluation. The model order reduction (MOR) seeks to reduce the computational complexity of large scale models. We present an approach to MOR based on the proper orthogonal decomposition (POD) with Galerkin projection. The problems arising from the nonlinearities present in the original model are adressed within the framework of the discrete empirical interpolation method (DEIM). The main contribution of this work consists in providing a link between the POD-DEIM based MOR and OpenFOAM. OpenFOAM is an open-source CFD toolbox capable of solving even industrial scale processes. Hence, the availability of a link between OpenFOAM and POD-DEIM based MOR enables a direct order reduction for large scale systems originating in the industrial practice. Keywords: model order reduction; CFD; OpenFOAM Fulltext is available at external website.
CFD motivated applications of model order reduction

The ongoing advances in numerical mathematics and available computing power combined with the industrial needs promote a development of more and more complex models. However, such models are, due to ...

Isoz, Martin
Ústav termomechaniky, 2017

CFD study of gas flow through structured separation columns packings mellapak 250.x and mellapak 250.y
Isoz, Martin
2017 - English
In order to increase the size of the gas-liquid interface area and consequently the intensity of the mass transfer, the separation columns are usually lled with a geometrically complex packing. The packing highly increases intricacy of the ow in the column and also makes almost all types of hydrodynamic measurements impossible. Hence a reliable model of the ow in the complex geometry of the separation column packing is sought by the industry. We provide a CFD model for the gas ow through two types of commercial structured packings, Mellapak 250.X and Mellapak 250.Y. We validate the model on experimental data and use it to study the gas mixing capabilities of the packings. Keywords: CFD; OpenFOAM; structured packing; distillation, absorption Available at various institutes of the ASCR
CFD study of gas flow through structured separation columns packings mellapak 250.x and mellapak 250.y

In order to increase the size of the gas-liquid interface area and consequently the intensity of the mass transfer, the separation columns are usually lled with a geometrically complex packing. The ...

Isoz, Martin
Ústav termomechaniky, 2017

Ultrasonic biopolymer characterisation by hysteresis quantification
Zatloukalová, Jana; Tokar, Daniel; Kopecká, Karolína; Převorovský, Zdeněk
2017 - English
Nonlinear characteristics are advanced indicators of the structure of viscoelastic materials. In this contribution, we focus on biopolymers (such as articular cartilage and skin tissue), and their typical amount of energy lost by mechanical loading/unloading represented by a hysteresis curve. For hysteresis modeling we use the PreisachMayergoyz space model, and restricted power distribution (Guyer extended distribution). Besides the power distribution parameters, the stress protocol is required as an input to obtain the modeled hysteresis curve, and to compare with experimental results. Knowing the experimental curve, an iterative numerical procedure for identification of true density function of opening and closing pressures was applied, and an optimization algorithm sought for the best (characteristic) distribution parameters for the specific soft tissue. Material properties can be evaluated based on the described quantification, and potentially used for medical purposes and healing or cosmetics treatment evaluation. Keywords: hysteresis; ultrasound; biopolymers Available at various institutes of the ASCR
Ultrasonic biopolymer characterisation by hysteresis quantification

Nonlinear characteristics are advanced indicators of the structure of viscoelastic materials. In this contribution, we focus on biopolymers (such as articular cartilage and skin tissue), and their ...

Zatloukalová, Jana; Tokar, Daniel; Kopecká, Karolína; Převorovský, Zdeněk
Ústav termomechaniky, 2017

Experimentální a MKP analýza kompozitní hybridní hlavně
Mochar, Dominik; Gabriel, Dušan; Trnka, Jan; Chlada, Milan; Valeš, František; Masák, Jan
2017 - Czech
Zpráva shrnuje výsledky výzkumu zamereného na posouzení konstrukce šesti ruzne vinutých vzorku kompozitních hybridních hlavní vyrobených firmou Compo Tech PLUS, spol. s r.o. pro návrh hlavne zbrane. Experimentálne byly stanoveny casové prubehy deformací na povrchu kompozitních hlavní vyvolané rázovým zatížením. Získané výsledky byly následne vyhodnoceny pomocí waveletové tranformace. V druhé cásti zprávy je popsána MKP analýza kompozitní hlavne s optimálne navrženým vinutím metodou konecných prvku v programech Abaqus a MARC. In this work experimental and numerical investigation of composite gun barrels was studied. The history of the stress-induced deformations located at the center of gun barrels on the outer surface generated by impact loading was measured for six types of barrels. The obtained signals were subsequently evaluated using wavelet transformation. Finally, the finite element analysis in Abaqus and MARC software for optimum composite material M46J was performed.\n\n Keywords: composite gun barrels; contact-impact analysis; drop weight tester; air cannon Available at various institutes of the ASCR
Experimentální a MKP analýza kompozitní hybridní hlavně

Zpráva shrnuje výsledky výzkumu zamereného na posouzení konstrukce šesti ruzne vinutých vzorku kompozitních hybridních hlavní vyrobených firmou Compo Tech PLUS, spol. s r.o. pro návrh hlavne zbrane. ...

Mochar, Dominik; Gabriel, Dušan; Trnka, Jan; Chlada, Milan; Valeš, František; Masák, Jan
Ústav termomechaniky, 2017

PIV měření 2D modelu ventilu Doosan s řízením proudění
Uruba, Václav; Procházka, Pavel P.; Skála, Vladislav
2017 - Czech
Zpráva obsahuje výsledky měření na modelu ventilu s řízením proudění pro firmu Doosan. Jako vzor pro model ventilu sloužil typický ventil používaný pro regulaci páry ve vstupním potrubí parní turbíny. Řízení je prováděno vkládáním usměrňovacích prvků a vyfukováním vzduchu ze slotů. Účelem studie je zhodnotit různé způsoby řízení proudění ve ventilu z hlediska ovlivnění odtržení mezní vrstvy v difuzoru. The report contains results of experimental investigation on a Doosan valve model with flow-control. The typical valve used in a steam turbine inlet pipe was considered. The flow-control was implemented by inserting flow-directing elements and by blowing from various slots. The study purpose was evaluation of various ways of flow-control strategies from the point of view of a boundary layer separation. Keywords: valve; Coanda effect; flow-control Available at various institutes of the ASCR
PIV měření 2D modelu ventilu Doosan s řízením proudění

Zpráva obsahuje výsledky měření na modelu ventilu s řízením proudění pro firmu Doosan. Jako vzor pro model ventilu sloužil typický ventil používaný pro regulaci páry ve vstupním potrubí parní turbíny. ...

Uruba, Václav; Procházka, Pavel P.; Skála, Vladislav
Ústav termomechaniky, 2017

Influence of the nasal cavities to human voice quality
Vampola, T.; Horáček, Jaromír
2017 - English
Nasal cavities (NC) form the side branches of the human vocal tract and exhibit antiresonance and resonance properties which influence the produced voice quality. This study investigates the possibility of these resonances to contribute to the speaker's or singer's formant cluster around 3 - 5 kHz. A reduced finite element (FE) model was created which allows numerical simulation of the effects of changing the volumes of NC on the acoustic resonance and antiresonance characteristics of the vocal tract. This model, created from an accurate three-dimensional (3D) FE model of the human vocal tract for vowel [a:] and [i:] is computationally-effective and allows parametric changes of the volume connecting the nasal tract with the human vocal tract. Developed FE models of acoustic spaces of nasal and vocal tract for vowels /a:/ and /i:/ are used to study the influence of (NC) on phonation of these vowels. Acoustics frequency-modal characteristics are studied by modal analysis and numerical simulation of acoustic signals in time domain is performed by transient analysis of the FE models. Keywords: human vocal tract; nasal cavities; human voice quality Available at various institutes of the ASCR
Influence of the nasal cavities to human voice quality

Nasal cavities (NC) form the side branches of the human vocal tract and exhibit antiresonance and resonance properties which influence the produced voice quality. This study investigates the ...

Vampola, T.; Horáček, Jaromír
Ústav termomechaniky, 2017

Computationally Efficient Model of the Human Vocal Fold
Štorkán, J.; Vampola, T.; Horáček, Jaromír
2017 - English
One mass model of the vocal folds with three degrees of freedom in 2D space was created and used to simulate the movement of the vocal folds. Vocal folds are modeled as a solid mass stored flexibly in 2D. The model is excited by aerodynamic forces. The flow is solved by analytical model incompressible and non-viscous fluid with constant flow. In case of close of the glottis are aerodynamic forces replaced by Hertz model of the contact forces. Movement equations are solved by numerical method. The model allows to solve the movement of the vocal folds in the time domain, pressure field acting on the vocal folds or contact pressures. Keywords: simulation of vocal folds; ideal fluid flow; nonlinear vibration; self-exciting vibration Available at various institutes of the ASCR
Computationally Efficient Model of the Human Vocal Fold

One mass model of the vocal folds with three degrees of freedom in 2D space was created and used to simulate the movement of the vocal folds. Vocal folds are modeled as a solid mass stored flexibly in ...

Štorkán, J.; Vampola, T.; Horáček, Jaromír
Ústav termomechaniky, 2017

Design of low-subsonic blade cascade model for aero-structural dynamic testing
Pešek, Luděk; Hála, Jindřich; Šulc, Petr; Chládek, Štěpán; Bula, Vítězslav; Uruba, Václav; Cibulka, Jan
2017 - English
Low-subsonic blade cascade model for aerodynamic testing was design in the Institute. The aim is to study the flow dynamics and flutter phenomenon in the cascade with moving blade profiles. The numerical calculations of two proposed cascades were performed for analysis of influence of stagger angle, incident angle of flow and inter-blade phase angles of the relative movement of blades. The results of numerical simulations of fluid dynamics of non-stationary flow both as viscid and non-viscid are presented. Futhermore the solution of the physical model of the designed cascade including excitation of profiles, measuring of the profile displacement and aerodynamic forces are described. Keywords: blade cascade; flutter; low-subsonic; experimental research Available at various institutes of the ASCR
Design of low-subsonic blade cascade model for aero-structural dynamic testing

Low-subsonic blade cascade model for aerodynamic testing was design in the Institute. The aim is to study the flow dynamics and flutter phenomenon in the cascade with moving blade profiles. The ...

Pešek, Luděk; Hála, Jindřich; Šulc, Petr; Chládek, Štěpán; Bula, Vítězslav; Uruba, Václav; Cibulka, Jan
Ústav termomechaniky, 2017

Modelling of Flow in Linear Blade Cascade with Thick Trailing Edge at a Lower Reynolds Number
Straka, P.; Příhoda, Jaromír
2017 - English
In the paper there are compared results of numerical simulation of compressible turbulent flow through a low-pressure turbine blade cascade with relatively thick trailing edges for various physical models. Steady, unsteady, fully turbulent, transitional, two-dimensional and three-dimensional models are compared. Results show that: a) steady simulation gives an incorrect prediction of the boundary layer development, b) two-dimensional unsteady simulation leads to inaccurate prediction of the far wake development and c) only three-dimensional unsteady transitional simulation gives sufficiently accurate prediction. Results of numerical simulations are compared with the experimental data. Keywords: linear blade cascade; boundary layer transition; vortex series Available at various institutes of the ASCR
Modelling of Flow in Linear Blade Cascade with Thick Trailing Edge at a Lower Reynolds Number

In the paper there are compared results of numerical simulation of compressible turbulent flow through a low-pressure turbine blade cascade with relatively thick trailing edges for various physical ...

Straka, P.; Příhoda, Jaromír
Ústav termomechaniky, 2017

About project

NRGL provides central access to information on grey literature produced in the Czech Republic in the fields of science, research and education. You can find more information about grey literature and NRGL at service web

Send your suggestions and comments to nusl@techlib.cz

Provider

http://www.techlib.cz

Facebook

Other bases