Number of found documents: 2874
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Rotary laser vibration laboratory
Maturkanič, Dušan; Procházka, Pavel; Voronova, Evgeniya; Košina, Jan
2017 - English
The rotary laser vibration laboratory started the test operation at the Institute of Thermomachanics AS CR, v.v.i. at the end of 2015. The facility enables the research of high power turbomachines rotary bladed wheels. The paper describes the verification tests which were performed and focused on the equipment parameters at different conditions. Keywords: vibration; turbine; blade; laser; non-contact measurement; sensor; diagnostics Available at various institutes of the ASCR
Rotary laser vibration laboratory

The rotary laser vibration laboratory started the test operation at the Institute of Thermomachanics AS CR, v.v.i. at the end of 2015. The facility enables the research of high power turbomachines ...

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

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

EXPERT SYSTEM SHELL ARCHITECTURE BASED ON DECISION NETWORK
Věchet, Stanislav; Krejsa, Jiří; Chen, K.S.
2017 - English
Presented paper deals with preliminary design of an empty expert system suitable for system monitoring in various engineering applications. Discussed expert system is rule-based with the possibility of importance factor definition within each rule. The deduced result can be composited from more than one possible hypothesis based on different confidence level. The core of the system is based on Bayesian decision network and simple autonomous mobile robot use-case is used for results presentation. Keywords: expert System; decision Network; knowledge engineering Available at various institutes of the ASCR
EXPERT SYSTEM SHELL ARCHITECTURE BASED ON DECISION NETWORK

Presented paper deals with preliminary design of an empty expert system suitable for system monitoring in various engineering applications. Discussed expert system is rule-based with the possibility ...

Věchet, Stanislav; Krejsa, Jiří; Chen, K.S.
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

Numerical Simulation of Laminar-Turbulent Transition in Accelerated Flows
Fürst, J.; Příhoda, Jaromír
2017 - English
The article deals with the evaluation of two RANS based models for simulation of transitional flows including heat transfer. The work is focused on the transition and heat transfer in cases of accelerated flows over a flat plate and through a test turbine cascade. Keywords: turbulence; laminar-turbulent transition; finite volume method Fulltext is available at external website.
Numerical Simulation of Laminar-Turbulent Transition in Accelerated Flows

The article deals with the evaluation of two RANS based models for simulation of transitional flows including heat transfer. The work is focused on the transition and heat transfer in cases of ...

Fürst, J.; Příhoda, Jaromír
Ústav termomechaniky, 2017

Simulation of Transonic Flow Through a Mid-Span Turbine Blade Cascade with the Separation-Induced Transition
Straka, P.; Příhoda, Jaromír; Fenderl, D.
2017 - English
The paper deals with the numerical simulation of the transonic flow through a mid-span turbine blade cascade by means of an in-house code based on the EARSM turbulence model of Hellsten [1] completed by the algebraic transition model of Straka and Příhoda [2]. The simulation using the transition model of Langtry and Menter [3] and Menter et al. [4] implemented in the commercial code ANSYS Fluent was used for the comparison. Simulations were carried out for the transonic regime close to the nominal regime. The flow separation on the suction side of the blade is caused by the interaction of the reflected shock wave with the boundary layer. The attention was focused on the modelling of the transition in the separated flow especially on the modelling of the length of the transition region. Numerical results were compared with experimental results. Keywords: mid-section blade cascade; boundary layer transition; shock wave interaction Fulltext is available at external website.
Simulation of Transonic Flow Through a Mid-Span Turbine Blade Cascade with the Separation-Induced Transition

The paper deals with the numerical simulation of the transonic flow through a mid-span turbine blade cascade by means of an in-house code based on the EARSM turbulence model of Hellsten [1] completed ...

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

Analysis of non-harmonic excitation of synthetic jet actuators
Kordík, Jozef; Trávníček, Zdeněk
2017 - English
Axisymmetric synthetic jet actuator based on a loudspeaker was tested experimentally. The actuator was driven by a voltage waveform, whose shape was derived from a pulse-width modulated signal. While the duty cycle and frequency of the excitation signal were varied the outlet velocities were measured by a hot-wire probe. Integral quantities such as characteristic velocity, momentum flux, and kinetic energy flux were evaluated from the outlet velocities. Their maxima were located as functions of frequency and the duty cycle. The found maximal values were compared with results obtained for harmonic excitation. The highest improvement (about 18%) was achieved for kinetic energy flux. Keywords: synthetic jet; synthetic jet actuator; momentum flux Available at various institutes of the ASCR
Analysis of non-harmonic excitation of synthetic jet actuators

Axisymmetric synthetic jet actuator based on a loudspeaker was tested experimentally. The actuator was driven by a voltage waveform, whose shape was derived from a pulse-width modulated signal. While ...

Kordík, Jozef; Trávníček, Zdeněk
Ústav termomechaniky, 2017

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